Field experiment confirms high macroplastic trapping efficiency of wood jams in a mountain river channel

Field experiment confirms high macroplastic trapping efficiency of wood jams in a mountain river channel | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Field experiment confirms high macroplastic trapping efficiency of wood jams in a mountain river channel Maciej Liro, Paweł Mikuś, Anna Zielonka This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5405242/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 23 Jan, 2025 Read the published version in Scientific Reports → Version 1 posted 10 You are reading this latest preprint version Abstract Identifying macroplastic deposition hotspots in rivers is essential for planning cleanup efforts and assessing the risks to aquatic life and the aesthetic value of river landscapes. Recent fieldwork in mountain rivers has shown that wood jams retain significantly more macroplastic than other emergent surfaces within river channels. Here, we experimentally verify these findings by tracking the deposition of 64 PET bottles after 52–65 days of transport in the mid-mountain Skawa River (Polish Carpathians) under low to medium flow conditions. Despite variations in river channel management and the resulting morphological patterns along the study reach, the majority (71.9%, n = 46) of tracked bottles were trapped by wood jams near the low-flow channel. Interestingly, the trapping efficiency was three times higher in the straight, regulated reach (14.8% per km) compared to the highly sinuous, unregulated reach (4.5% per km). In the regulated reach, water inundations and wood jams are confined to a narrow zone near the low-flow channel, which may explain the high macroplastic trapping efficiency under low to medium flow conditions. In contrast, in the unmanaged, seminatural reach, where wood jams and water inundation occur over broader areas formed by extensive gravel bars, the trapping potential is lower under similar flow conditions. Our findings confirm that wood jams and channel morphology are key predictors of macroplastic trapping in mountain rivers. Together with previous observations, this underscores the significant role of flow conditions in shaping riverine macroplastic hotspots across reaches with different morphologies. Specifically, regulated mountain river reaches show a higher potential for hotspot formation during low to medium flows, while unregulated reaches tend to form hotspots during flood events. Earth and environmental sciences/Solid earth sciences/Geomorphology Earth and environmental sciences/Solid earth sciences/Sedimentology field experiment macroplastic deposition macroplastic storage plastic-wood jams Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Tracking macroplastic deposition hotspots in rivers is essential for understanding its pathways within fluvial systems, assessing risks to biota and human health, and guiding targeted cleanup efforts 1 . Mountain rivers, as unique components of fluvial systems, play a crucial role for humans, wildlife, and society by providing water resources, diverse habitats, and high aesthetic value 2 , 3 . However, these benefits can be significantly reduced by macroplastic pollution, though our understanding of its impacts remains limited 4 . Precisely identifying macroplastic deposition hotspots along mountain rivers is critical for evaluating these risks and selecting effective cleanup sites, enabling the removal of plastic debris from channels before it causes further harm, such as breaking down into microplastics 5 or being ingested by animals 6 . Wood, along with mineral sediment, is one of the components of a river’s load that can significantly modify fluvial processes. It may exhibit even greater temporal and spatial dynamics than mineral sediment and the channel forms associated with it 7 . The distribution of wood in river channels depends on the structure of local forests, the intensity of channel processes, and the river’s capacity to supply, transport, and retain wood in depositional forms 8 . The factors determining the deposition sites of large wood, as well as its influence on channel morphology, are largely dependent on stream size 9 . In contrast to narrow channels of first-to-third-order reach, where woody is generally not transported far and usually appears as entire trees spanning over the channel 9 , 10 , fifth-order and higher-order streams can transport nearly all wood accumulations due to sufficient channel width, depth, and high flood flows 9 , 11 . Resulted wood accumulations play a key role in shaping and evolving bars, altering water flow direction, and causing or preventing bank erosion 10 . Exposed surfaces within the active zone of mountain rivers provide ideal sites for the deposition of living driftwood and shrubs capable of vegetative regeneration, capturing fine-grained sediment from floodwaters and initiating island formation 12 . In low-energy sections of lowland rivers, large wood assume the role of " chief engineer " guiding channel processes 13 . The presence of wood in rivers has recently been recognized as important in the context of macroplastic pollution. Previous studies have shown that wood accumulations and macroplastics often coexist in various river systems due to their similar transport and deposition patterns 14 , 15 , 16 , 17 . Recent works have also shown that wood jams—heterogeneous mixtures of logs, branches, rootwads, fine organic matter, and mineral deposits 18 —function as highly effective macroplastic traps in mountain rivers 19 . For example, data obtained from mountain rivers in Polish Carpathians demonstrated that wood jams trap one to three orders of magnitudes more macroplastic debris (in terms of mass) than surrounding surfaces covered by woody vegetation, herbaceous vegetation, and unvegetated river sediments, respectively 19 . This high trapping efficiency of wood jams is attributed to their high surface roughness and specific structure, which create hydraulic conditions and specific obstacle for macroplastic transported in flotation (e.g., bottles) and suspension (e.g., foil bags) 19 . Moreover, the widespread occurrence of wood jams in wide, unregulated sections of mountain rivers results in a 36-fold increase in macroplastic trapping efficiency in their active channel zones compared to narrow, channelized reaches 19 . However, these findings are based on sampling macroplastics that were already trapped during previous flow events of varying magnitudes and have not yet been experimentally verified by tracking plastic items transported under specific hydrological conditions. In this paper, we report the results of a short-term (52–65 days) field experiment using tracked 1-liter PET bottles, conducted during low- to medium-flow conditions in a 20-km-long mountainous section of the Skawa River in the Polish Carpathians. Based on the existing state-of-the-art 19 , we test the hypothesis that wood accumulations will trap more tracked macroplastic objects than other surfaces present in the mountain river channel (H1) and that unregulated, wide channel section of the river will trap more macroplastic objects than a narrower, regulated one (H2). Study area The study was conducted in the Skawa River, located in the Polish Carpathians. The Skawa is a right-bank tributary of the Vistula, Poland's largest river, extending 96 kilometers and originating at an elevation of 700 m a.s.l.. The Skawa follows a mountainous hydrological regime, characterized by low hydrological inertia, which results in significant flow variability. The total catchment area covers 1,160 km², with an average annual flow of 11 m³/s in its lower course. The riverbed is primarily composed of gravel and cobbles, with sections of bedrock present in the central part of the study area. Much of the river was regulated in the second half of the 20th century, with regulatory works including channel straightening and bank reinforcement through riprap structures. These interventions increased flow energy and reduced sediment supply, resulting in over 2 meters of channel incision 20 . The field experiment was conducted along a 18-kilometer stretch of the river, from the village of Osielec to the Świnna Poręba Dam Reservoir (Fig. 1 ). Here, the river’s width varies from 5 to 40 meters. Within this section, four reaches with distinct morphological patterns were identified based on the present-day characteristics of the river channel and its history of anthropogenic modification (Table 1 ). Reaches 1 and 2 illustrate regulated, straightened, and deepened Carpathian river channels flowing through densely populated valleys. In these sections, local gravel deficits have resulted in bedrock exposure. In contrast, Reach 3 represents spontaneous renaturalization, where previously regulated channels have returned to natural bar-braided and island-braided patterns with an alluvial bed. Due to their contrasting geomorphic characteristics (Fig. 2), similar lengths, and proximity, Reaches 2 and 3 were selected for a detailed comparison of macroplastic trapping efficiency to test hypothesis H2. Reach 4 remains regulated because of nearby road infrastructure, buildings, and the downstream dam reservoir. The emission of mismanaged plastic waste in the areas surrounding the study reach ranges from 1.6 tons/km²/year in the uppermost reach to 261.2 tons/km²/year in the lowermost reach 21 . Table 1 Basic geomorphological characteristics of the studied section of the Skawa River. Reaches selected for detailed analysis are underlined. Reach Length [km] Channel gradient (m/m) Mean channel width (m) Median grain size (mm) Channel bottom Channel pattern Channel regulaion 1 8.62 0.00529 25 83 alluvial-bedrock sinuous, single-thread Rip-rap regulated banks 2 1.35 0.005619 43 71 alluvial-bedrock straight, single-thread Rip-rap regulated banks 3 3.34 0.00472 135 70 alluvial sinuous, bar-braided, island-braide no regulation 4 6.91 0.00403 58 66 alluvial-bedrock sinuous, single-thread Rip-rap regulated banks Throughout the entire study section, the riverbanks are overgrown with shrubs and woody vegetation from the Salicaceae family, alongside mature riparian forests developing in the floodplain zones farther from the channel. This vegetation provides a source of woody debris, varying in size, which is transported into the river channel during flood events. Figure 2 . The views of the morphological patterns and wood jams present in reaches 2 and 3 used for detailed field work testing H2. A1 - a view of the narrow section; A2 - typical wood jam stored on vegetated riprap within the narrow section; B1 - view of the multi-thread section; B2 - typical wood jam accumulated on a gravel bar within the multi-thread section. Field inventory of wood jams and geomorphic characteristics To collect additional data explaining potential differences in trapping efficiency between river reaches with contrasting morphological patterns (reaches 2 and 3), a detailed inventory of wood jams—suggested by previous studies as effective macroplastic traps—was conducted after the experiment in these two reaches. The inventory focused on the zones inundated by the highest river flows observed during the experiment (Fig. 1 C). The maximum water inundation during the experiment reached 1.30 meters above the average low-flow level (Fig. 2). For each wood jam (as defined by 18 ), dimensions, surface area, mass, volume, height above the water surface, and the type of surface were recorded. The inventoried wood jams were generally small (Table 2 ) and were of a similar structure and build. In the narrow section (reach 2), wood jams were strongly associated with high-roughness areas, such as cobbles and shrubby vegetation, primarily located on the concave banks of the channel, particularly downstream of riffles (Fig. 2A1, 2A2). In contrast, in the wide, unregulated section (reach 3), wood jams were typically found in the frontal and lateral zones of bars and islands separating the low-water channels (Fig. 2B1, 2B2). Almost all wood jams in the narrow section consisted of fine woody debris deposited around living willows. In the wide, multi-thread section, wood jams were often deposited on bare gravel, grass, or shrubs, with initial accumulation around a ‘key member,’ such as a single log, root wad, or shrub (for details, see Fig. B2). Table 2 Comparison of (A) geomorphic and (B) wood jam characteristics in reaches 2 and 3. Statistical comparisons were performed based on measurements done and calculated based on Statistically significant differences between the reaches for the given parameters are highlighted in bold. Wide reach (R3) Narrow reach (R2) A. Geomorphic and wood jams features (not tested statistically) Section length (km) 3.34 1.35 Total area of low-flow water table (ha) 16.63 3.5 Total area of inundated zone (ha) 23.75 5.77 Total volume of wood jams within the inundated zone (m 3 ) 140.6 87.9 Total mass of wood jams within the inundated zone (t) 10547 6592 Number of wood jams within the inundated zone (items per 1 km of river length) 10.5 50.4 Number of wood jams within the inundated zone (items per 1ha) 2.1 11.8 Specific mass of wood jams within the inundated zone (kg per ha) 1480 2892 Volume of wood jams within the inundated zone (m 3 per 1 ha) 5.92 15.2 Specific wood area in the inundated zone (m 2 per 1 km of river length) 48.7 97 Volume of wood jams within the inundated zone (m 3 per 1 km of river length) 20.3 67.1 B. Geomorphic and wood jam features (tested statistically) n = 35 n = 68 p value Mean width of low-flow channel (m) 26.1 23.1 p = 0.14 Mean width of inundated zone (m) 75.2 42.4 p < 0.0001 Mean mass of wood jams within the inundated zone (t) 301.3 96.9 p < 0.0001 Mean elevation of wood jams above low-flow water table (m) 0.53 0.83 p = 0.00015 Total wood area in the inundated zone (m 2 ) 163 131 p < 0.0001 Mean volume of wood jam within the inundated zone (m 3 ) 4 1.29 p < 0.0001 Results and discussion Plastic bottle deposition During the 52 to 65 days of low-flow conditions in the studied reach, we recorded transport distances ( n = 64) ranging from 0.37 km to 16.27 km, with a median of 1.68 km (Fig. S1 ). Most bottles were deposited on wood jams (71.9%, n = 46) (Fig. 3 A), and the proportion of deposition on wood jams compared to other surface types varied across reaches: 61.8% in Reach 3, 68.4% in Reach 1, 68.8% in Reach 2, and 100% in Reach 4. The elevation above the low-flow water level at which bottles were deposited was normally distributed, ranging from 0 to 1.2 m, with a mean of 0.44 m (SD = 0.29). No statistically significant differences in deposition elevation were observed among the four reaches (Fig. 4 B). The trapping efficiency of plastic bottles (the proportion of bottles introduced into the reach that were deposited along its 1 km length) was three times higher in the straight, regulated reach (14.8% per km) compared to the sinuous, unregulated reach (4.5% per km). The obtained results highlight significant differences in macroplastic deposition between sites with and without wood jams (Fig. 4 ), confirming previously observed patterns of macroplastic and woody debris coexistence in fluvial systems 14 , 16 , 17 . Our data not only corroborates earlier findings that macroplastic and woody debris deposition coincide spatially due to their similar properties and transport dynamics 14 , but also demonstrates that, beyond these similarities, wood jams themselves act as highly effective macroplastic traps 19 . Previous field studies in mid-sized mountain rivers in temperate climates and small mountain streams in Mediterranean climates indicates that the amount of macroplastic deposited on wood jams exceeded that found on other surfaces, such as woody vegetation, herbaceous vegetation, and exposed river sediments, by factors of 19, 129, and 180 19 and by factors of 10, 150, and 600 22 ). Despite differences in river flow conditions, sizes, and riparian vegetation types across the above-mentioned studies, consistently wood jams were documented as the most effective macroplastic traps within active river channels. Our short-term experiment confirms these findings using macroplastic tracking technique. While confirming previously indicated patterns of high macroplastic trapping efficiency (H1), our results also reveal a novel insight giving new perspective to the previous observations on different macroplastic trapping efficiencies of river reaches having different morphologies (H2). Previous work suggested that wider, unmanaged river sections trap more macroplastic than narrower, regulated ones 19 . However, our results show that during low to medium flow conditions, where inundation is confined to areas near the low-flow channel, substantially more macroplastic is trapped in the narrower, regulated reach. These findings suggest that river morphology is an important predictor of macroplastic deposition hotspots, with the influence of flow conditions playing a critical role. Specifically, it can be hypothesized that hotspots of macroplastic deposition are more likely to form in regulated river reaches during low to medium flows (as shown in our experiment), whereas unregulated reaches may have a higher potential for hotspot formation during flood events, when wood jams more distant from the low flow channel in wider reaches also start to operate as plastic trap. Field mapping indicates that the higher abundance of wood jams in the narrower, inundated zone during low to medium flows in the regulated reach, compared to the wider, unregulated one (Table 2 ), plays a significant role in macroplastic trapping. Additionally, increased surface roughness from dense woody vegetation and riprap reinforcement along the banks in the regulated sections likely contributes to this effect. While our experimental method—using printed trackers inserted into plastic bottles—offers a low-cost approach, it also has few limitations. Specifically, this method allowed us to track only a small proportion of the bottles introduced into the study reach, limiting the completeness of the data. For instance, it does not provide detailed information on the number of remobilization events or the residency time of bottles within different surface covers or morphologies. We were also unable to evaluate transport distances of bottle which were not found during field surveys in the study which limit potential for assessing exact travel distance of bottle in river. Definitely, future studies employing more advanced and precise tracking technologies, such as GPS or RFID tags (see e.g., 23 ), will offer more comprehensive insights into the transport, remobilization, and storage patterns of macroplastic within river reaches of varying morphologies (e.g., regulated vs. unmanaged) and surface characteristics. Such improvements will enhance our understanding of macroplastic dynamics, particularly in relation to different surface cover types and bank reinforcement strategies, thereby advancing the accuracy and applicability of our findings. The lifespan of macroplastic deposition hotspots formed by wood jams, as well as their remobilization, is closely related to the fluvial processes that govern the formation and persistence of wood jams—specifically, occurrence of flood events 19 . It is well-documented that wood accumulation in rivers typically occurs during the falling limb of the flood wave, that is, at high water levels (e.g., 24 , 25 , 26 ). Our previous research has demonstrated that wood jams, regardless of their elevation above the low-flow channel, trap similar amounts of macroplastic. This suggests that macroplastic deposition on these structures can occur both during high-flow stages, when wood jams are formed, and during lower flows, which are still capable of inundating the wood jams developed but still not too high to remobilise them 19 . This indicates a dual mechanism for macroplastic deposition: high flows facilitate the formation of wood jams and the trapping of macroplastic, while subsequent lower flows can continue to deposit macroplastic on the already-formed jams, enhancing their long-term effectiveness as traps. Throughout our experiment, water level fluctuations remained within the range of a 1-year flood (Fig. 1 ). Detailed field mapping within this zone revealed notably higher concentrations of wood jams in the narrower, single-thread sections inundated during the experiment, compared to the wider, unmanaged section. In these narrower sections, wood jams were mostly found in the distal parts of riffles and immediately downstream, particularly along channel banks regulated by ripraps and overgrown with young Salicaceae shrubs. In wider, multi-thread sections, wood jams typically occurred in the proximal parts of islands or at eroded bends, where flow direction changes abruptly. Overall, the experiment confirms that wood debris accumulations are primary sites for intense macroplastic deposition in mountain river channels 19 . Furthermore, the results from our experiment provide a more detailed view of this process, showing that during low to moderate flows, only wood accumulations located in the immediate vicinity of the active channel contribute to trapping macroplastics transported by the river. Thus, presence of wood jams in the close proximity of the low-flow channel is crucial for controlling macroplastic deposition during these flow stages. This finding supplements our earlier observations, which indicated that, when analyzing the entire active channel zone inundated during low, medium, and high flows, wide, multi-thread sections capture significantly more macroplastic—often dozens of times more—than narrow, regulated sections 19 . Our fieldwork indicated that significantly more wood jams are concentrated within the low- to moderate-flood zone in the regulated reach (Table 1 ), which may explain why the trapping efficiency of this reach—calculated as the percentage of bottles introduced to each reach ( n = 60 per reach) and found within one kilometer of their lengths—was higher than in the wider, unmanaged reach (Figs. 3 and 4 ). Future field experiments conducted in river reaches with varying morphological patterns and spanning both low and high flow stages could further verify our findings (for methods see e.g., 23 ). Given the growing body of evidence suggesting a direct link between woody debris presence and macroplastic storage 19 , 16 , 17 , future studies could examine this relationship more closely along the entire river continuum, including streams of various orders with differing interactions between stream size and the effects of woody debris on fluvial processes (see, e.g., 10 , 7 ). This could be achieved, for example, by evaluating macroplastic trapping at individual wood jams throughout the river course, from headwaters to the river mouth. Future research should also examine the amount of macroplastic remobilized by floodwaters in conjunction with mobilized wood jams. Numerical modeling approaches previously used to track wood transport and deposition in rivers appear well-suited for such studies (for methods see, e.g., 27 , 28 ). Outlook This study demonstrates that wood jams can significantly enhance macroplastic deposition in rivers—an effect that should be integrated into future analyses of macroplastic pathways in fluvial systems. We found that this enhancement depends on both river morphology and flow conditions. Our results show that narrow, regulated river reaches with wood jams along the riverbank trap more macroplastic during low to medium flows, while previous studies indicate that wider, unregulated reaches serve as deposition hotspots during flood flows. These findings highlight the need for further research connecting large woody debris dynamics with the fate of macroplastic debris throughout entire fluvial systems to improve our understanding of its transport, remobilization, and storage patterns in rivers with diverse morphologies and surface characteristics. Methods Field experiment All bottles were numbered using foil markers placed inside, securely sealed with caps, and released into the studied section of the Skawa River at three locations (Fig. 1 A-B) on July 11th, 2022. A total of 57, 60, and 60 one-liter PET bottles were introduced directly into the low-flow channel at the uppermost points of reaches 1, 2, and 3, respectively. The bottles were not introduced into reach 4 at the beginning of experiment, and all bottles found there were transported from the upstream reaches. Field surveys to recover the marked bottles were conducted 52 days (September 1st), 57 days (September 6th), and 65 days (September 14th) after release. Four individuals (two on each riverbank) retrieved 64 of the 196 tagged bottles during these surveys. The travel distance for each bottle was measured as the thalweg distance between the release point and the retrieval location using a Trimble R4 RTK GPS receiver. In all four reaches, data on deposition sites were collected and categorized as follows: low-flow channels, gravel bars, side channels, and channel banks. To test H1, deposition in each of these geomorphic features was further classified based on whether it occurred with or without wood jams throughout the entire study section. Macroplastic trapping efficiency, defined as a percent proportion of bottles introduced and trapped within 1 kilometer of a specific river reach, was calculated for reach 2 (narrow, regulated) and reach 3 (wide, unmanaged) to test H2. Data analysis The data sampled for each group of surface covers were non-normally distributed (Shapiro-Wilk test). Characteristics of inventoried wood jams and the geomorphology of the studied reaches 2 and 3 were compared using the Mann-Whitney U test. Parameters showing significant differences ( p < 0.05) were highlighted in bold (Table 2 ) and visualized graphically using violin plots (Fig. S2). To determine if wood jams trap more macroplastic than other surface types, the proportion (%) of tracked bottles found on surfaces with and without wood jams was evaluated for each of the four study reaches (H1). To assess whether more macroplastic is trapped in the wide, unmanaged reach compared to the narrow, channelized reach (H2), the macroplastic trapping efficiency of these two reaches was calculated as a percent proportion of bottles introduced to each reach ( n = 60 per reach) and found within one kilometer of their lengths. All analyses and visualizations were performed in the R programming environment. Declarations Data availability Data would be made available by the corresponding author upon request. Funding The study was completed within the scope of the Research Project 2020/39/D/ST10/01935 financed by the National Science Centre of Poland. Author information Authors and Affiliations Institute of Nature Conservation, Polish Academy of Sciences, al. Adama Mickiewicza 33, 31-120 Kraków Maciej Liro, Paweł Mikuś, Anna Zielonka Contributions ML: Conceptualization, Field Experimentation, Formal analysis, Data curation Writing – original draft,. R Methodology, Project administration. PM: Conceptualization, Field Experimentation, Formal analysis, Data curation Writing – original draft,. R Methodology. AZ: Conceptualization, Field Experimentation, Formal analysis, Data curation Writing – original draft,. R Methodology. ML and PM contributed equally to this work. Corresponding author Correspondence to Paweł Mikuś and Maciej Liro. Ethics declarations Competing interests The authors declare no competing interests. Additional information Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. References Tasseron, P. et al. Defining plastic pollution hotspots. Sci. Total Environ. 934 , 173294. https://doi.org/10.1016/j.scitotenv.2024.173294 (2024). Hauer, F. R. et al. Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes. Sci. Adv. 2 , e1600026. https://doi.org/10.1126/sciadv.1600026 (2016). Wohl, E. et al. The natural wood regime in rivers. BioScience 69 , 259–273. https://doi.org/10.1093/biosci/biz013 (2019). Liro, M., van Emmerik, T. H. M., Zielonka, A., Gallitelli, L. & Mihai, F. C. The unknown fate of macroplastic in mountain rivers. Sci. Total Environ. 865 , 161224. https://doi.org/10.1016/j.scitotenv.2022.161224 (2023a). Liro, M., Zielonka, A. & van Emmerik, T. H. M. Macroplastic fragmentation in rivers. Environ. Int. 180 , 108186. https://doi.org/10.1016/j.envint.2023.108186 (2023b). Blettler, M. C. M., Abrial, E., Khan, F. R., Sivri, N. & Espinola, L. A. Freshwater plastic pollution: Recognizing research biases and identifying knowledge gaps. Water Res. 143 , 416–424. https://doi.org/10.1016/j.watres.2018.06.015 (2018). Gurnell, A. M., Piégay, H., Swanson, F. J. & Gregory, S. V. Large wood and fluvial processes. Freshw. Biol. 47 , 601–619. https://doi.org/10.1046/j.1365-2427.2002.00916.x (2002). Swanson, F. J., Johnson, S. L. & Gregory, S. V. Flood disturbance in a forested mountain landscape. BioScience 48 , 681–689. https://doi.org/10.2307/1313331 (1998). Piégay, H., Gurnell, A. M. & France, S. E. Large woody debris and river geomorphological patterns: Examples from S Engl. Geomorphology 19 , 99–116 https://doi.org/10.1016/S0169-555X(96)00045-1 . (1997). Nakamura, F. & Swanson, F. J. Effects of coarse woody debris on morphology and sediment storage of a mountain stream system in Western Oregon. Earth Surf. Process. Landf. 18 , 43–61. https://doi.org/10.1002/esp.3290180104 (1993). Gurnell, A. M., Petts, G. E., Harris, N., Ward, J. V. & Tockner, K. Large wood retention in river channels: The case of the Fiume Tagliamento, Italy. Earth Surf. Process. Landf. 25 (200003), 255–275. https://doi.org/10.1002/(SICI)1096-9837 (2000). )25:3%3C255::AID-ESP56%3E3.0.CO;2-H. Mikuś, P. & Wyżga, B. Long-term monitoring of the recruitment and dynamics of large wood in Kamienica Stream, Polish Carpathians. J. Mt. Sci. 17 , 1281–1293. https://doi.org/10.1007/s11629-019-5954-1 (2020). Gurnell, A. M. et al. A conceptual model of vegetation–hydrogeomorphology interactions within river corridors. River Res. Appl. 32 , 142–163. https://doi.org/10.1002/rra.2928 (2016). Shumilova, O. et al. Floating matter: A neglected component of the ecological integrity of rivers. Aquat. Sci. 81 , 25. https://doi.org/10.1007/s00027-019-0619-2 (2019). Al-Zawaidah, H., Ravazzolo, D. & Friedrich, H. Macroplastics in rivers: Present knowledge, issues and challenges. Environ. Sci. Process. Impacts . 23 , 535–552. https://doi.org/10.1039/d0em00517g (2021). Hoellein, T. J., Kim, L. H., Lazcano, R. F. & Vincent, A. E. S. Debris dams retain trash, mostly plastic, in urban streams. Freshw. Sci. 43 , 94–106. https://doi.org/10.1086/729305 (2024a). Hoellein, T. J., Schwenk, B. A., Kaźmierczak, E. M. & Petersen, F. Plastic litter is part of the carbon cycle in an urban river: Microplastic and macroplastic accumulate with organic matter in floating debris rafts. Water Environ. Res. 96 , e11116. https://doi.org/10.1002/wer.11116 (2024b). Thévenet, A., Citterio, A. & Piégay, H. A new methodology for the assessment of large woody debris accumulations on highly modified rivers (example of two French piedmont rivers). Regul. River . 14 (1998110), 467–483. https://doi.org/10.1002/(SICI)1099-1646 (1998). )14:6%3C467::AID-RRR514%3E3.0.CO;2-X. Liro, M., Mikuś, P. & Wyżga, B. First insight into macroplastic storage in a mountain river: The role of in-river vegetation cover, wood jams, and channel morphology. Sci. Total Environ. 838 , 156354. https://doi.org/10.1016/j.scitotenv.2022.156354 (2022). Wyżga, B. A review on channel incision in the Polish Carpathian rivers during the 20th century. Dev. Earth Surf. Process. 11 , 525–533. https://doi.org/10.1016/S0928-2025(07)11142-1 (2007). Liro, M. et al. Mountains of plastic: Mismanaged plastic waste along the Carpathians watercourses. Sci. Total Environ. 888 , 164058. https://doi.org/10.1016/j.scitotenv.2023.164058 (2023c). Liro, M. & Gallitelli, L. Plastic-wood jam: Macroplastic deposition on woody debris along a Mediterranean mountain river. Hydrobiologia (under review). Duncan, E. M. et al. Message in a bottle: Open-source technology to track the movement of plastic pollution. PLoS One . 17 , e0269218. https://doi.org/10.1371/journal.pone.0269218 (2022). Abbe, T. B. & Montgomery, D. R. Large woody debris jams, channel hydraulics and habitat formations in large rivers. Regul. River . 12 , 201–221. https://doi.org/10.1002/(SICI)1099-1646(199603)12:2/3%3C201 (1996). ::AID-RRR390%3E3.0.CO;2-A. Bertoldi, W., Drake, N. A. & Gurnell, A. M. Interactions between river flows and colonizing vegetation on a braided river: Exploring spatial and temporal dynamics in riparian vegetation cover using satellite data. Earth Surf. Process. Landf. 36 , 1474–1486. https://doi.org/10.1002/esp.2166 (2011). Mikuś, P., Wyżga, B., Kaczka, R. J., Walusiak, E. & Zawiejska, J. Islands in a European mountain river: Linkages with large wood deposition, flood flows, and plant diversity. Geomorphology 202 , 115–127. https://doi.org/10.1016/j.geomorph.2012.09.016 (2013). Ruiz-Villanueva, V. et al. Recent advances quantifying large wood dynamics in river basins: New methods and remaining challenges. Rev. Geophys. 54 , 611–652. https://doi.org/10.1002/2015RG000514 (2016a). Ruiz-Villanueva, V., Wyżga, B., Zawiejska, J., Hajdukiewicz, M. & Stoffel, M. Factors controlling large-wood transport in a mountain river. Geomorphology 272 , 21–31. https://doi.org/10.1016/j.geomorph.2015.04.004 (2016b). Additional Declarations No competing interests reported. Supplementary Files Liroetal.supplementarymaterials.docx Cite Share Download PDF Status: Published Journal Publication published 23 Jan, 2025 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 09 Dec, 2024 Reviews received at journal 07 Dec, 2024 Reviews received at journal 03 Dec, 2024 Reviewers agreed at journal 27 Nov, 2024 Reviewers agreed at journal 27 Nov, 2024 Reviewers invited by journal 26 Nov, 2024 Editor assigned by journal 26 Nov, 2024 Editor invited by journal 21 Nov, 2024 Submission checks completed at journal 19 Nov, 2024 First submitted to journal 06 Nov, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5405242","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":384471526,"identity":"f87f691e-09b8-4368-a354-8c8766b81480","order_by":0,"name":"Maciej Liro","email":"","orcid":"","institution":"Polish Academy of Sciences","correspondingAuthor":false,"prefix":"","firstName":"Maciej","middleName":"","lastName":"Liro","suffix":""},{"id":384471527,"identity":"60a46f5a-0aa4-49a7-b449-c0e9117ae3ca","order_by":1,"name":"Paweł Mikuś","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAzUlEQVRIiWNgGAWjYDACZjYgUSEBJECMA2ChBiK0nEHRwkhAC0glYxsDCVp029nSJH/Os5AzZ2BL+/DjjE1ig3Qjfi1mh9mOSfNukzC2bGA7PLPnRlpig8xBQlrY26QZt0kkbjjA3szA8+FwboNEImEtkj/nQLQw/iFOC9sxCd4GkBa2w8w8N4jTkmzNcwzol2a2ZGaZM2n1bQT9cv6Y4c0fNXVy5uxtxoxvjtkY80s3H8CrBQ4MmKEMNgniNAC1wFlEaxkFo2AUjIKRAgDpL0ShYqKx1AAAAABJRU5ErkJggg==","orcid":"","institution":"Polish Academy of Sciences","correspondingAuthor":true,"prefix":"","firstName":"Paweł","middleName":"","lastName":"Mikuś","suffix":""},{"id":384471528,"identity":"62e62338-fbcb-4f40-809d-1bf0653d5e26","order_by":2,"name":"Anna Zielonka","email":"","orcid":"","institution":"Polish Academy of Sciences","correspondingAuthor":false,"prefix":"","firstName":"Anna","middleName":"","lastName":"Zielonka","suffix":""}],"badges":[],"createdAt":"2024-11-06 20:23:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5405242/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5405242/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-87147-9","type":"published","date":"2025-01-23T15:56:54+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":71810115,"identity":"f7863c14-120b-47c8-b8fb-a9edd1a0daac","added_by":"auto","created_at":"2024-12-18 18:12:14","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":275190,"visible":true,"origin":"","legend":"\u003cp\u003eLocation of the study site in the Carpathians (A), the detailed location of bottle input points for the experiment within the river (B), and water hydrograph during the experiment (C).\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-5405242/v1/14bd673cd461ac9917d72e30.jpeg"},{"id":71811149,"identity":"0a2eafa5-d582-44aa-a654-e5a917ad1f3c","added_by":"auto","created_at":"2024-12-18 18:28:15","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":2320331,"visible":true,"origin":"","legend":"\u003cp\u003eThe views of the morphological patterns and wood jams present in reaches 2 and 3 used for detailed field work testing H2. A1 - a view of the narrow section; A2 - typical wood jam stored on vegetated riprap within the narrow section; B1 - view of the multi-thread section; B2 - typical wood jam accumulated on a gravel bar within the multi-thread section.\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-5405242/v1/4cded3de6b5a456db63b06b1.jpeg"},{"id":71810312,"identity":"21564b22-01ee-4113-a067-ef47a1b0b1df","added_by":"auto","created_at":"2024-12-18 18:20:14","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":354379,"visible":true,"origin":"","legend":"\u003cp\u003eThe proportions of experimental bottles deposited on different types of emergent surfaces of river channel with and without wood jams.\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-5405242/v1/3b108d29153a59eb8f467fb4.jpeg"},{"id":71810128,"identity":"e9983039-4eae-4025-8337-fb466ef1110e","added_by":"auto","created_at":"2024-12-18 18:12:15","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":784825,"visible":true,"origin":"","legend":"\u003cp\u003eHydromorphological features of the narrow, regulated Reach 2 (A) and the unmanaged, sinuous Reach 3 (B), with the locations of wood jams and accumulated tagged plastic bottles.\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-5405242/v1/577fb7cffb2486ba28ba1a7b.jpeg"},{"id":74858299,"identity":"cf67d7eb-3e73-40c7-92e8-83a16aebd187","added_by":"auto","created_at":"2025-01-27 16:06:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4129231,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5405242/v1/c85e7f02-3d60-47a1-97af-0c01557b92e5.pdf"},{"id":71810313,"identity":"751c461f-d3b1-421a-81a1-e019507ab062","added_by":"auto","created_at":"2024-12-18 18:20:14","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":362998,"visible":true,"origin":"","legend":"","description":"","filename":"Liroetal.supplementarymaterials.docx","url":"https://assets-eu.researchsquare.com/files/rs-5405242/v1/195086200a436484e21da493.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Field experiment confirms high macroplastic trapping efficiency of wood jams in a mountain river channel","fulltext":[{"header":"Introduction","content":"\u003cp\u003eTracking macroplastic deposition hotspots in rivers is essential for understanding its pathways within fluvial systems, assessing risks to biota and human health, and guiding targeted cleanup efforts\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. Mountain rivers, as unique components of fluvial systems, play a crucial role for humans, wildlife, and society by providing water resources, diverse habitats, and high aesthetic value\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. However, these benefits can be significantly reduced by macroplastic pollution, though our understanding of its impacts remains limited\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. Precisely identifying macroplastic deposition hotspots along mountain rivers is critical for evaluating these risks and selecting effective cleanup sites, enabling the removal of plastic debris from channels before it causes further harm, such as breaking down into microplastics\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e or being ingested by animals\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eWood, along with mineral sediment, is one of the components of a river\u0026rsquo;s load that can significantly modify fluvial processes. It may exhibit even greater temporal and spatial dynamics than mineral sediment and the channel forms associated with it\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e. The distribution of wood in river channels depends on the structure of local forests, the intensity of channel processes, and the river\u0026rsquo;s capacity to supply, transport, and retain wood in depositional forms\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. The factors determining the deposition sites of large wood, as well as its influence on channel morphology, are largely dependent on stream size\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. In contrast to narrow channels of first-to-third-order reach, where woody is generally not transported far and usually appears as entire trees spanning over the channel\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e,\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e, fifth-order and higher-order streams can transport nearly all wood accumulations due to sufficient channel width, depth, and high flood flows\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e,\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. Resulted wood accumulations play a key role in shaping and evolving bars, altering water flow direction, and causing or preventing bank erosion\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. Exposed surfaces within the active zone of mountain rivers provide ideal sites for the deposition of living driftwood and shrubs capable of vegetative regeneration, capturing fine-grained sediment from floodwaters and initiating island formation\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. In low-energy sections of lowland rivers, large wood assume the role of \"\u003cem\u003echief engineer\u003c/em\u003e\" guiding channel processes\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe presence of wood in rivers has recently been recognized as important in the context of macroplastic pollution. Previous studies have shown that wood accumulations and macroplastics often coexist in various river systems due to their similar transport and deposition patterns\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. Recent works have also shown that wood jams\u0026mdash;heterogeneous mixtures of logs, branches, rootwads, fine organic matter, and mineral deposits\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e\u0026mdash;function as highly effective macroplastic traps in mountain rivers\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. For example, data obtained from mountain rivers in Polish Carpathians demonstrated that wood jams trap one to three orders of magnitudes more macroplastic debris (in terms of mass) than surrounding surfaces covered by woody vegetation, herbaceous vegetation, and unvegetated river sediments, respectively\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. This high trapping efficiency of wood jams is attributed to their high surface roughness and specific structure, which create hydraulic conditions and specific obstacle for macroplastic transported in flotation (e.g., bottles) and suspension (e.g., foil bags)\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. Moreover, the widespread occurrence of wood jams in wide, unregulated sections of mountain rivers results in a 36-fold increase in macroplastic trapping efficiency in their active channel zones compared to narrow, channelized reaches\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. However, these findings are based on sampling macroplastics that were already trapped during previous flow events of varying magnitudes and have not yet been experimentally verified by tracking plastic items transported under specific hydrological conditions.\u003c/p\u003e \u003cp\u003eIn this paper, we report the results of a short-term (52\u0026ndash;65 days) field experiment using tracked 1-liter PET bottles, conducted during low- to medium-flow conditions in a 20-km-long mountainous section of the Skawa River in the Polish Carpathians. Based on the existing state-of-the-art\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e, we test the hypothesis that wood accumulations will trap more tracked macroplastic objects than other surfaces present in the mountain river channel (H1) and that unregulated, wide channel section of the river will trap more macroplastic objects than a narrower, regulated one (H2).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eStudy area\u003c/h3\u003e\n\u003cp\u003eThe study was conducted in the Skawa River, located in the Polish Carpathians. The Skawa is a right-bank tributary of the Vistula, Poland's largest river, extending 96 kilometers and originating at an elevation of 700 m a.s.l.. The Skawa follows a mountainous hydrological regime, characterized by low hydrological inertia, which results in significant flow variability. The total catchment area covers 1,160 km\u0026sup2;, with an average annual flow of 11 m\u0026sup3;/s in its lower course. The riverbed is primarily composed of gravel and cobbles, with sections of bedrock present in the central part of the study area. Much of the river was regulated in the second half of the 20th century, with regulatory works including channel straightening and bank reinforcement through riprap structures. These interventions increased flow energy and reduced sediment supply, resulting in over 2 meters of channel incision\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe field experiment was conducted along a 18-kilometer stretch of the river, from the village of Osielec to the Świnna Poręba Dam Reservoir (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Here, the river\u0026rsquo;s width varies from 5 to 40 meters. Within this section, four reaches with distinct morphological patterns were identified based on the present-day characteristics of the river channel and its history of anthropogenic modification (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Reaches 1 and 2 illustrate regulated, straightened, and deepened Carpathian river channels flowing through densely populated valleys. In these sections, local gravel deficits have resulted in bedrock exposure. In contrast, Reach 3 represents spontaneous renaturalization, where previously regulated channels have returned to natural bar-braided and island-braided patterns with an alluvial bed. Due to their contrasting geomorphic characteristics (Fig.\u0026nbsp;2), similar lengths, and proximity, Reaches 2 and 3 were selected for a detailed comparison of macroplastic trapping efficiency to test hypothesis H2. Reach 4 remains regulated because of nearby road infrastructure, buildings, and the downstream dam reservoir. The emission of mismanaged plastic waste in the areas surrounding the study reach ranges from 1.6 tons/km\u0026sup2;/year in the uppermost reach to 261.2 tons/km\u0026sup2;/year in the lowermost reach\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBasic geomorphological characteristics of the studied section of the Skawa River. Reaches selected for detailed analysis are underlined.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eReach\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLength [km]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eChannel gradient (m/m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean channel width (m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMedian grain size (mm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eChannel bottom\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eChannel pattern\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eChannel regulaion\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.00529\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003ealluvial-bedrock\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003esinuous, single-thread\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eRip-rap regulated banks\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e2\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.005619\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003ealluvial-bedrock\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003estraight, single-thread\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eRip-rap regulated banks\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e3\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.00472\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e135\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003ealluvial\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003esinuous, bar-braided, island-braide\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eno regulation\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.00403\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003ealluvial-bedrock\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003esinuous, single-thread\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eRip-rap regulated banks\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e Throughout the entire study section, the riverbanks are overgrown with shrubs and woody vegetation from the Salicaceae family, alongside mature riparian forests developing in the floodplain zones farther from the channel. This vegetation provides a source of woody debris, varying in size, which is transported into the river channel during flood events.\u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure\u0026nbsp;2\u003c/b\u003e. The views of the morphological patterns and wood jams present in reaches 2 and 3 used for detailed field work testing H2. A1 - a view of the narrow section; A2 - typical wood jam stored on vegetated riprap within the narrow section; B1 - view of the multi-thread section; B2 - typical wood jam accumulated on a gravel bar within the multi-thread section.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eField inventory of wood jams and geomorphic characteristics\u003c/h2\u003e \u003cp\u003eTo collect additional data explaining potential differences in trapping efficiency between river reaches with contrasting morphological patterns (reaches 2 and 3), a detailed inventory of wood jams\u0026mdash;suggested by previous studies as effective macroplastic traps\u0026mdash;was conducted after the experiment in these two reaches. The inventory focused on the zones inundated by the highest river flows observed during the experiment (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eC). The maximum water inundation during the experiment reached 1.30 meters above the average low-flow level (Fig.\u0026nbsp;2).\u003c/p\u003e \u003cp\u003eFor each wood jam (as defined by\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e), dimensions, surface area, mass, volume, height above the water surface, and the type of surface were recorded. The inventoried wood jams were generally small (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) and were of a similar structure and build. In the narrow section (reach 2), wood jams were strongly associated with high-roughness areas, such as cobbles and shrubby vegetation, primarily located on the concave banks of the channel, particularly downstream of riffles (Fig.\u0026nbsp;2A1, 2A2). In contrast, in the wide, unregulated section (reach 3), wood jams were typically found in the frontal and lateral zones of bars and islands separating the low-water channels (Fig.\u0026nbsp;2B1, 2B2). Almost all wood jams in the narrow section consisted of fine woody debris deposited around living willows. In the wide, multi-thread section, wood jams were often deposited on bare gravel, grass, or shrubs, with initial accumulation around a \u0026lsquo;key member,\u0026rsquo; such as a single log, root wad, or shrub (for details, see Fig. B2).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of (A) geomorphic and (B) wood jam characteristics in reaches 2 and 3. Statistical comparisons were performed based on measurements done and calculated based on Statistically significant differences between the reaches for the given parameters are highlighted in bold.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWide reach\u003c/p\u003e \u003cp\u003e(R3)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNarrow reach (R2)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cp\u003eA. Geomorphic and wood jams features (not tested statistically)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSection length (km)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal area of low-flow water table (ha)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal area of inundated zone (ha)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal volume of wood jams within the inundated zone (m\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e140.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e87.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal mass of wood jams within the inundated zone (t)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10547\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6592\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber of wood jams within the inundated zone (items per 1 km of river length)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber of wood jams within the inundated zone (items per 1ha)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpecific mass of wood jams within the inundated zone (kg per ha)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1480\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2892\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVolume of wood jams within the inundated zone (m\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e per 1 ha)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpecific wood area in the inundated zone (m\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e per 1 km of river length)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e48.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVolume of wood jams within the inundated zone (m\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e per 1 km of river length)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e67.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB. \u003cb\u003eGeomorphic and wood jam features (tested statistically)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003en\u003c/b\u003e\u0026thinsp;\u003cb\u003e=\u0026thinsp;35\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003en\u003c/b\u003e\u0026thinsp;\u003cb\u003e=\u0026thinsp;68\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003ep\u003c/b\u003e \u003cb\u003evalue\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean width of low-flow channel (m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.14\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean width of inundated zone (m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e75.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e42.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003ep\u003c/b\u003e\u0026thinsp;\u003cb\u003e\u0026lt;\u0026thinsp;0.0001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean mass of wood jams within the inundated zone (t)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e301.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e96.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003ep\u003c/b\u003e\u0026thinsp;\u003cb\u003e\u0026lt;\u0026thinsp;0.0001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean elevation of wood jams above low-flow water table (m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003ep\u003c/b\u003e\u0026thinsp;\u003cb\u003e=\u0026thinsp;0.00015\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal wood area in the inundated zone (m\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e163\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e131\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003ep\u003c/b\u003e\u0026thinsp;\u003cb\u003e\u0026lt;\u0026thinsp;0.0001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean volume of wood jam within the inundated zone (m\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003ep\u003c/b\u003e\u0026thinsp;\u003cb\u003e\u0026lt;\u0026thinsp;0.0001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Results and discussion","content":"\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003ePlastic bottle deposition\u003c/h2\u003e \u003cp\u003eDuring the 52 to 65 days of low-flow conditions in the studied reach, we recorded transport distances (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;64) ranging from 0.37 km to 16.27 km, with a median of 1.68 km (Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). Most bottles were deposited on wood jams (71.9%, \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;46) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003eA), and the proportion of deposition on wood jams compared to other surface types varied across reaches: 61.8% in Reach 3, 68.4% in Reach 1, 68.8% in Reach 2, and 100% in Reach 4. The elevation above the low-flow water level at which bottles were deposited was normally distributed, ranging from 0 to 1.2 m, with a mean of 0.44 m (SD\u0026thinsp;=\u0026thinsp;0.29). No statistically significant differences in deposition elevation were observed among the four reaches (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003eB).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe trapping efficiency of plastic bottles (the proportion of bottles introduced into the reach that were deposited along its 1 km length) was three times higher in the straight, regulated reach (14.8% per km) compared to the sinuous, unregulated reach (4.5% per km).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe obtained results highlight significant differences in macroplastic deposition between sites with and without wood jams (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e), confirming previously observed patterns of macroplastic and woody debris coexistence in fluvial systems\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. Our data not only corroborates earlier findings that macroplastic and woody debris deposition coincide spatially due to their similar properties and transport dynamics\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e, but also demonstrates that, beyond these similarities, wood jams themselves act as highly effective macroplastic traps\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. Previous field studies in mid-sized mountain rivers in temperate climates and small mountain streams in Mediterranean climates indicates that the amount of macroplastic deposited on wood jams exceeded that found on other surfaces, such as woody vegetation, herbaceous vegetation, and exposed river sediments, by factors of 19, 129, and 180\u003csup\u003e19\u003c/sup\u003e and by factors of 10, 150, and 600\u003csup\u003e22\u003c/sup\u003e). Despite differences in river flow conditions, sizes, and riparian vegetation types across the above-mentioned studies, consistently wood jams were documented as the most effective macroplastic traps within active river channels.\u003c/p\u003e \u003cp\u003eOur short-term experiment confirms these findings using macroplastic tracking technique. While confirming previously indicated patterns of high macroplastic trapping efficiency (H1), our results also reveal a novel insight giving new perspective to the previous observations on different macroplastic trapping efficiencies of river reaches having different morphologies (H2). Previous work suggested that wider, unmanaged river sections trap more macroplastic than narrower, regulated ones\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. However, our results show that during low to medium flow conditions, where inundation is confined to areas near the low-flow channel, substantially more macroplastic is trapped in the narrower, regulated reach. These findings suggest that river morphology is an important predictor of macroplastic deposition hotspots, with the influence of flow conditions playing a critical role. Specifically, it can be hypothesized that hotspots of macroplastic deposition are more likely to form in regulated river reaches during low to medium flows (as shown in our experiment), whereas unregulated reaches may have a higher potential for hotspot formation during flood events, when wood jams more distant from the low flow channel in wider reaches also start to operate as plastic trap.\u003c/p\u003e \u003cp\u003eField mapping indicates that the higher abundance of wood jams in the narrower, inundated zone during low to medium flows in the regulated reach, compared to the wider, unregulated one (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), plays a significant role in macroplastic trapping. Additionally, increased surface roughness from dense woody vegetation and riprap reinforcement along the banks in the regulated sections likely contributes to this effect. While our experimental method\u0026mdash;using printed trackers inserted into plastic bottles\u0026mdash;offers a low-cost approach, it also has few limitations. Specifically, this method allowed us to track only a small proportion of the bottles introduced into the study reach, limiting the completeness of the data. For instance, it does not provide detailed information on the number of remobilization events or the residency time of bottles within different surface covers or morphologies. We were also unable to evaluate transport distances of bottle which were not found during field surveys in the study which limit potential for assessing exact travel distance of bottle in river. Definitely, future studies employing more advanced and precise tracking technologies, such as GPS or RFID tags (see e.g.,\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e), will offer more comprehensive insights into the transport, remobilization, and storage patterns of macroplastic within river reaches of varying morphologies (e.g., regulated vs. unmanaged) and surface characteristics. Such improvements will enhance our understanding of macroplastic dynamics, particularly in relation to different surface cover types and bank reinforcement strategies, thereby advancing the accuracy and applicability of our findings.\u003c/p\u003e \u003cp\u003eThe lifespan of macroplastic deposition hotspots formed by wood jams, as well as their remobilization, is closely related to the fluvial processes that govern the formation and persistence of wood jams\u0026mdash;specifically, occurrence of flood events\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. It is well-documented that wood accumulation in rivers typically occurs during the falling limb of the flood wave, that is, at high water levels (e.g.,\u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e,\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e,\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e). Our previous research has demonstrated that wood jams, regardless of their elevation above the low-flow channel, trap similar amounts of macroplastic. This suggests that macroplastic deposition on these structures can occur both during high-flow stages, when wood jams are formed, and during lower flows, which are still capable of inundating the wood jams developed but still not too high to remobilise them\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. This indicates a dual mechanism for macroplastic deposition: high flows facilitate the formation of wood jams and the trapping of macroplastic, while subsequent lower flows can continue to deposit macroplastic on the already-formed jams, enhancing their long-term effectiveness as traps. Throughout our experiment, water level fluctuations remained within the range of a 1-year flood (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Detailed field mapping within this zone revealed notably higher concentrations of wood jams in the narrower, single-thread sections inundated during the experiment, compared to the wider, unmanaged section. In these narrower sections, wood jams were mostly found in the distal parts of riffles and immediately downstream, particularly along channel banks regulated by ripraps and overgrown with young Salicaceae shrubs. In wider, multi-thread sections, wood jams typically occurred in the proximal parts of islands or at eroded bends, where flow direction changes abruptly. Overall, the experiment confirms that wood debris accumulations are primary sites for intense macroplastic deposition in mountain river channels\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. Furthermore, the results from our experiment provide a more detailed view of this process, showing that during low to moderate flows, only wood accumulations located in the immediate vicinity of the active channel contribute to trapping macroplastics transported by the river. Thus, presence of wood jams in the close proximity of the low-flow channel is crucial for controlling macroplastic deposition during these flow stages. This finding supplements our earlier observations, which indicated that, when analyzing the entire active channel zone inundated during low, medium, and high flows, wide, multi-thread sections capture significantly more macroplastic\u0026mdash;often dozens of times more\u0026mdash;than narrow, regulated sections\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. Our fieldwork indicated that significantly more wood jams are concentrated within the low- to moderate-flood zone in the regulated reach (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), which may explain why the trapping efficiency of this reach\u0026mdash;calculated as the percentage of bottles introduced to each reach (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;60 per reach) and found within one kilometer of their lengths\u0026mdash;was higher than in the wider, unmanaged reach (Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Future field experiments conducted in river reaches with varying morphological patterns and spanning both low and high flow stages could further verify our findings (for methods see e.g.,\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e).\u003c/p\u003e \u003cp\u003eGiven the growing body of evidence suggesting a direct link between woody debris presence and macroplastic storage\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e, future studies could examine this relationship more closely along the entire river continuum, including streams of various orders with differing interactions between stream size and the effects of woody debris on fluvial processes (see, e.g., \u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e,\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e). This could be achieved, for example, by evaluating macroplastic trapping at individual wood jams throughout the river course, from headwaters to the river mouth. Future research should also examine the amount of macroplastic remobilized by floodwaters in conjunction with mobilized wood jams. Numerical modeling approaches previously used to track wood transport and deposition in rivers appear well-suited for such studies (for methods see, e.g., \u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e,\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eOutlook\u003c/h3\u003e\n\u003cp\u003eThis study demonstrates that wood jams can significantly enhance macroplastic deposition in rivers\u0026mdash;an effect that should be integrated into future analyses of macroplastic pathways in fluvial systems. We found that this enhancement depends on both river morphology and flow conditions. Our results show that narrow, regulated river reaches with wood jams along the riverbank trap more macroplastic during low to medium flows, while previous studies indicate that wider, unregulated reaches serve as deposition hotspots during flood flows. These findings highlight the need for further research connecting large woody debris dynamics with the fate of macroplastic debris throughout entire fluvial systems to improve our understanding of its transport, remobilization, and storage patterns in rivers with diverse morphologies and surface characteristics.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eField experiment\u003c/h2\u003e \u003cp\u003eAll bottles were numbered using foil markers placed inside, securely sealed with caps, and released into the studied section of the Skawa River at three locations (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA-B) on July 11th, 2022. A total of 57, 60, and 60 one-liter PET bottles were introduced directly into the low-flow channel at the uppermost points of reaches 1, 2, and 3, respectively. The bottles were not introduced into reach 4 at the beginning of experiment, and all bottles found there were transported from the upstream reaches. Field surveys to recover the marked bottles were conducted 52 days (September 1st), 57 days (September 6th), and 65 days (September 14th) after release. Four individuals (two on each riverbank) retrieved 64 of the 196 tagged bottles during these surveys.\u003c/p\u003e \u003cp\u003eThe travel distance for each bottle was measured as the thalweg distance between the release point and the retrieval location using a Trimble R4 RTK GPS receiver. In all four reaches, data on deposition sites were collected and categorized as follows: low-flow channels, gravel bars, side channels, and channel banks. To test H1, deposition in each of these geomorphic features was further classified based on whether it occurred with or without wood jams throughout the entire study section. Macroplastic trapping efficiency, defined as a percent proportion of bottles introduced and trapped within 1 kilometer of a specific river reach, was calculated for reach 2 (narrow, regulated) and reach 3 (wide, unmanaged) to test H2.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eData analysis\u003c/h2\u003e \u003cp\u003eThe data sampled for each group of surface covers were non-normally distributed (Shapiro-Wilk test). Characteristics of inventoried wood jams and the geomorphology of the studied reaches 2 and 3 were compared using the Mann-Whitney U test. Parameters showing significant differences (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) were highlighted in bold (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) and visualized graphically using violin plots (Fig. S2).\u003c/p\u003e \u003cp\u003eTo determine if wood jams trap more macroplastic than other surface types, the proportion (%) of tracked bottles found on surfaces with and without wood jams was evaluated for each of the four study reaches (H1). To assess whether more macroplastic is trapped in the wide, unmanaged reach compared to the narrow, channelized reach (H2), the macroplastic trapping efficiency of these two reaches was calculated as a percent proportion of bottles introduced to each reach (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;60 per reach) and found within one kilometer of their lengths. All analyses and visualizations were performed in the R programming environment.\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData would be made available by the corresponding author upon request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was completed within the scope of the Research Project 2020/39/D/ST10/01935 financed by the National Science Centre of Poland.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAuthors and Affiliations\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInstitute of Nature Conservation, Polish Academy of Sciences, al. Adama Mickiewicza 33, 31-120 Krak\u0026oacute;w\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMaciej Liro, Paweł Mikuś, Anna Zielonka\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eContributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eML: Conceptualization, Field Experimentation, Formal analysis, Data curation Writing \u0026ndash; original draft,. R Methodology, Project administration. PM: Conceptualization, Field Experimentation, Formal analysis, Data curation Writing \u0026ndash; original draft,. R Methodology. AZ: Conceptualization, Field Experimentation, Formal analysis, Data curation Writing \u0026ndash; original draft,. R Methodology. ML and PM contributed equally to this work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorresponding author\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCorrespondence to Paweł Mikuś and Maciej Liro.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics declarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eCompeting interests\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdditional information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePublisher\u0026rsquo;s note\u003c/p\u003e\n\u003cp\u003eSpringer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eTasseron, P. et al. Defining plastic pollution hotspots. \u003cem\u003eSci. Total Environ.\u003c/em\u003e \u003cb\u003e934\u003c/b\u003e, 173294. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.scitotenv.2024.173294\u003c/span\u003e\u003cspan address=\"10.1016/j.scitotenv.2024.173294\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2024).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHauer, F. R. et al. Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes. \u003cem\u003eSci. Adv.\u003c/em\u003e \u003cb\u003e2\u003c/b\u003e, e1600026. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1126/sciadv.1600026\u003c/span\u003e\u003cspan address=\"10.1126/sciadv.1600026\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2016).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWohl, E. et al. The natural wood regime in rivers. \u003cem\u003eBioScience\u003c/em\u003e \u003cb\u003e69\u003c/b\u003e, 259\u0026ndash;273. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/biosci/biz013\u003c/span\u003e\u003cspan address=\"10.1093/biosci/biz013\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2019).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiro, M., van Emmerik, T. H. M., Zielonka, A., Gallitelli, L. \u0026amp; Mihai, F. C. The unknown fate of macroplastic in mountain rivers. \u003cem\u003eSci. Total Environ.\u003c/em\u003e \u003cb\u003e865\u003c/b\u003e, 161224. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.scitotenv.2022.161224\u003c/span\u003e\u003cspan address=\"10.1016/j.scitotenv.2022.161224\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2023a).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiro, M., Zielonka, A. \u0026amp; van Emmerik, T. H. M. Macroplastic fragmentation in rivers. \u003cem\u003eEnviron. Int.\u003c/em\u003e \u003cb\u003e180\u003c/b\u003e, 108186. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.envint.2023.108186\u003c/span\u003e\u003cspan address=\"10.1016/j.envint.2023.108186\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2023b).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBlettler, M. C. M., Abrial, E., Khan, F. R., Sivri, N. \u0026amp; Espinola, L. A. Freshwater plastic pollution: Recognizing research biases and identifying knowledge gaps. \u003cem\u003eWater Res.\u003c/em\u003e \u003cb\u003e143\u003c/b\u003e, 416\u0026ndash;424. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.watres.2018.06.015\u003c/span\u003e\u003cspan address=\"10.1016/j.watres.2018.06.015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2018).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGurnell, A. M., Pi\u0026eacute;gay, H., Swanson, F. J. \u0026amp; Gregory, S. V. Large wood and fluvial processes. \u003cem\u003eFreshw. Biol.\u003c/em\u003e \u003cb\u003e47\u003c/b\u003e, 601\u0026ndash;619. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1046/j.1365-2427.2002.00916.x\u003c/span\u003e\u003cspan address=\"10.1046/j.1365-2427.2002.00916.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2002).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSwanson, F. J., Johnson, S. L. \u0026amp; Gregory, S. V. Flood disturbance in a forested mountain landscape. \u003cem\u003eBioScience\u003c/em\u003e \u003cb\u003e48\u003c/b\u003e, 681\u0026ndash;689. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2307/1313331\u003c/span\u003e\u003cspan address=\"10.2307/1313331\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (1998).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePi\u0026eacute;gay, H., Gurnell, A. M. \u0026amp; France, S. E. Large woody debris and river geomorphological patterns: Examples from \u003cem\u003eS Engl. Geomorphology\u003c/em\u003e \u003cb\u003e19\u003c/b\u003e, 99\u0026ndash;116 \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0169-555X(96)00045-1\u003c/span\u003e\u003cspan address=\"10.1016/S0169-555X(96)00045-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. (1997).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNakamura, F. \u0026amp; Swanson, F. J. Effects of coarse woody debris on morphology and sediment storage of a mountain stream system in Western Oregon. \u003cem\u003eEarth Surf. Process. Landf.\u003c/em\u003e \u003cb\u003e18\u003c/b\u003e, 43\u0026ndash;61. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/esp.3290180104\u003c/span\u003e\u003cspan address=\"10.1002/esp.3290180104\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (1993).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGurnell, A. M., Petts, G. E., Harris, N., Ward, J. V. \u0026amp; Tockner, K. Large wood retention in river channels: The case of the Fiume Tagliamento, Italy. \u003cem\u003eEarth Surf. Process. Landf.\u003c/em\u003e \u003cb\u003e25\u003c/b\u003e (200003), 255\u0026ndash;275. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/(SICI)1096-9837\u003c/span\u003e\u003cspan address=\"10.1002/(SICI)1096-9837\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2000). )25:3%3C255::AID-ESP56%3E3.0.CO;2-H.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMikuś, P. \u0026amp; Wyżga, B. Long-term monitoring of the recruitment and dynamics of large wood in Kamienica Stream, Polish Carpathians. \u003cem\u003eJ. Mt. Sci.\u003c/em\u003e \u003cb\u003e17\u003c/b\u003e, 1281\u0026ndash;1293. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11629-019-5954-1\u003c/span\u003e\u003cspan address=\"10.1007/s11629-019-5954-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2020).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGurnell, A. M. et al. A conceptual model of vegetation\u0026ndash;hydrogeomorphology interactions within river corridors. \u003cem\u003eRiver Res. Appl.\u003c/em\u003e \u003cb\u003e32\u003c/b\u003e, 142\u0026ndash;163. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/rra.2928\u003c/span\u003e\u003cspan address=\"10.1002/rra.2928\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2016).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShumilova, O. et al. Floating matter: A neglected component of the ecological integrity of rivers. \u003cem\u003eAquat. Sci.\u003c/em\u003e \u003cb\u003e81\u003c/b\u003e, 25. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00027-019-0619-2\u003c/span\u003e\u003cspan address=\"10.1007/s00027-019-0619-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2019).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAl-Zawaidah, H., Ravazzolo, D. \u0026amp; Friedrich, H. Macroplastics in rivers: Present knowledge, issues and challenges. \u003cem\u003eEnviron. Sci. Process. Impacts\u003c/em\u003e. \u003cb\u003e23\u003c/b\u003e, 535\u0026ndash;552. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1039/d0em00517g\u003c/span\u003e\u003cspan address=\"10.1039/d0em00517g\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHoellein, T. J., Kim, L. H., Lazcano, R. F. \u0026amp; Vincent, A. E. S. Debris dams retain trash, mostly plastic, in urban streams. \u003cem\u003eFreshw. Sci.\u003c/em\u003e \u003cb\u003e43\u003c/b\u003e, 94\u0026ndash;106. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1086/729305\u003c/span\u003e\u003cspan address=\"10.1086/729305\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2024a).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHoellein, T. J., Schwenk, B. A., Kaźmierczak, E. M. \u0026amp; Petersen, F. Plastic litter is part of the carbon cycle in an urban river: Microplastic and macroplastic accumulate with organic matter in floating debris rafts. \u003cem\u003eWater Environ. Res.\u003c/em\u003e \u003cb\u003e96\u003c/b\u003e, e11116. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/wer.11116\u003c/span\u003e\u003cspan address=\"10.1002/wer.11116\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2024b).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTh\u0026eacute;venet, A., Citterio, A. \u0026amp; Pi\u0026eacute;gay, H. A new methodology for the assessment of large woody debris accumulations on highly modified rivers (example of two French piedmont rivers). \u003cem\u003eRegul. River\u003c/em\u003e. \u003cb\u003e14\u003c/b\u003e (1998110), 467\u0026ndash;483. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/(SICI)1099-1646\u003c/span\u003e\u003cspan address=\"10.1002/(SICI)1099-1646\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (1998). )14:6%3C467::AID-RRR514%3E3.0.CO;2-X.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiro, M., Mikuś, P. \u0026amp; Wyżga, B. First insight into macroplastic storage in a mountain river: The role of in-river vegetation cover, wood jams, and channel morphology. \u003cem\u003eSci. Total Environ.\u003c/em\u003e \u003cb\u003e838\u003c/b\u003e, 156354. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.scitotenv.2022.156354\u003c/span\u003e\u003cspan address=\"10.1016/j.scitotenv.2022.156354\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWyżga, B. A review on channel incision in the Polish Carpathian rivers during the 20th century. \u003cem\u003eDev. Earth Surf. Process.\u003c/em\u003e \u003cb\u003e11\u003c/b\u003e, 525\u0026ndash;533. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0928-2025(07)11142-1\u003c/span\u003e\u003cspan address=\"10.1016/S0928-2025(07)11142-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2007).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiro, M. et al. Mountains of plastic: Mismanaged plastic waste along the Carpathians watercourses. \u003cem\u003eSci. Total Environ.\u003c/em\u003e \u003cb\u003e888\u003c/b\u003e, 164058. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.scitotenv.2023.164058\u003c/span\u003e\u003cspan address=\"10.1016/j.scitotenv.2023.164058\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2023c).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiro, M. \u0026amp; Gallitelli, L. Plastic-wood jam: Macroplastic deposition on woody debris along a Mediterranean mountain river. \u003cem\u003eHydrobiologia\u003c/em\u003e (under review).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDuncan, E. M. et al. Message in a bottle: Open-source technology to track the movement of plastic pollution. \u003cem\u003ePLoS One\u003c/em\u003e. \u003cb\u003e17\u003c/b\u003e, e0269218. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1371/journal.pone.0269218\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0269218\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbbe, T. B. \u0026amp; Montgomery, D. R. Large woody debris jams, channel hydraulics and habitat formations in large rivers. \u003cem\u003eRegul. River\u003c/em\u003e. \u003cb\u003e12\u003c/b\u003e, 201\u0026ndash;221. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/(SICI)1099-1646(199603)12:2/3%3C201\u003c/span\u003e\u003cspan address=\"10.1002/(SICI)1099-1646(199603)12:2/3%3C201\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (1996). ::AID-RRR390%3E3.0.CO;2-A.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBertoldi, W., Drake, N. A. \u0026amp; Gurnell, A. M. Interactions between river flows and colonizing vegetation on a braided river: Exploring spatial and temporal dynamics in riparian vegetation cover using satellite data. \u003cem\u003eEarth Surf. Process. Landf.\u003c/em\u003e \u003cb\u003e36\u003c/b\u003e, 1474\u0026ndash;1486. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/esp.2166\u003c/span\u003e\u003cspan address=\"10.1002/esp.2166\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2011).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMikuś, P., Wyżga, B., Kaczka, R. J., Walusiak, E. \u0026amp; Zawiejska, J. Islands in a European mountain river: Linkages with large wood deposition, flood flows, and plant diversity. \u003cem\u003eGeomorphology\u003c/em\u003e \u003cb\u003e202\u003c/b\u003e, 115\u0026ndash;127. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.geomorph.2012.09.016\u003c/span\u003e\u003cspan address=\"10.1016/j.geomorph.2012.09.016\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2013).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRuiz-Villanueva, V. et al. Recent advances quantifying large wood dynamics in river basins: New methods and remaining challenges. \u003cem\u003eRev. Geophys.\u003c/em\u003e \u003cb\u003e54\u003c/b\u003e, 611\u0026ndash;652. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/2015RG000514\u003c/span\u003e\u003cspan address=\"10.1002/2015RG000514\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2016a).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRuiz-Villanueva, V., Wyżga, B., Zawiejska, J., Hajdukiewicz, M. \u0026amp; Stoffel, M. Factors controlling large-wood transport in a mountain river. \u003cem\u003eGeomorphology\u003c/em\u003e \u003cb\u003e272\u003c/b\u003e, 21\u0026ndash;31. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.geomorph.2015.04.004\u003c/span\u003e\u003cspan address=\"10.1016/j.geomorph.2015.04.004\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2016b).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"field experiment, macroplastic deposition, macroplastic storage, plastic-wood jams","lastPublishedDoi":"10.21203/rs.3.rs-5405242/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5405242/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIdentifying macroplastic deposition hotspots in rivers is essential for planning cleanup efforts and assessing the risks to aquatic life and the aesthetic value of river landscapes. Recent fieldwork in mountain rivers has shown that wood jams retain significantly more macroplastic than other emergent surfaces within river channels. Here, we experimentally verify these findings by tracking the deposition of 64 PET bottles after 52\u0026ndash;65 days of transport in the mid-mountain Skawa River (Polish Carpathians) under low to medium flow conditions. Despite variations in river channel management and the resulting morphological patterns along the study reach, the majority (71.9%, \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;46) of tracked bottles were trapped by wood jams near the low-flow channel. Interestingly, the trapping efficiency was three times higher in the straight, regulated reach (14.8% per km) compared to the highly sinuous, unregulated reach (4.5% per km). In the regulated reach, water inundations and wood jams are confined to a narrow zone near the low-flow channel, which may explain the high macroplastic trapping efficiency under low to medium flow conditions. In contrast, in the unmanaged, seminatural reach, where wood jams and water inundation occur over broader areas formed by extensive gravel bars, the trapping potential is lower under similar flow conditions. Our findings confirm that wood jams and channel morphology are key predictors of macroplastic trapping in mountain rivers. Together with previous observations, this underscores the significant role of flow conditions in shaping riverine macroplastic hotspots across reaches with different morphologies. Specifically, regulated mountain river reaches show a higher potential for hotspot formation during low to medium flows, while unregulated reaches tend to form hotspots during flood events.\u003c/p\u003e","manuscriptTitle":"Field experiment confirms high macroplastic trapping efficiency of wood jams in a mountain river channel","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-12-18 18:12:09","doi":"10.21203/rs.3.rs-5405242/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-12-09T08:15:52+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-12-07T14:37:40+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-12-03T19:49:45+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"130871994961561430145500787957945128757","date":"2024-11-27T16:52:04+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"182019357671939050588894901313236352297","date":"2024-11-27T10:23:01+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-11-27T03:16:47+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-11-27T02:53:47+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2024-11-22T03:08:33+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-11-19T10:56:48+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2024-11-06T20:10:39+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"fa6cc0c3-69fb-438f-b439-154593e67136","owner":[],"postedDate":"December 18th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":40964218,"name":"Earth and environmental sciences/Solid earth sciences/Geomorphology"},{"id":40964219,"name":"Earth and environmental sciences/Solid earth sciences/Sedimentology"}],"tags":[],"updatedAt":"2025-01-27T15:59:30+00:00","versionOfRecord":{"articleIdentity":"rs-5405242","link":"https://doi.org/10.1038/s41598-025-87147-9","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2025-01-23 15:56:54","publishedOnDateReadable":"January 23rd, 2025"},"versionCreatedAt":"2024-12-18 18:12:09","video":"","vorDoi":"10.1038/s41598-025-87147-9","vorDoiUrl":"https://doi.org/10.1038/s41598-025-87147-9","workflowStages":[]},"version":"v1","identity":"rs-5405242","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5405242","identity":"rs-5405242","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}