No mercury from Greenland glacial runoff in sessile coastal biota

No mercury from Greenland glacial runoff in sessile coastal biota | 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 No mercury from Greenland glacial runoff in sessile coastal biota Jakob Thyrring, Dorte Krause-Jensen, Birgit Olesen, Poul Bjerregaard This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8804831/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Melting glaciers have been claimed to be a significant and unaccounted-for source of mercury (Hg) in Greenland, raising concerns for economics, communities and ecosystem health. Here we demonstrate, however, that benthic species from Greenland fjords contain negligible concentrations of mercury across > 100 km spatial gradients and decadal time scales. Our results, together with other studies on Hg in Greenland’s waters, sediments, and planktonic species, cannot reproduce the previously reported mercury contamination from glaciers, and there is now substantial evidence against the claim that Greenland ice sheet has implications for Hg budgets and coastal ecosystems. Biological sciences/Ecology/Ecophysiology Earth and environmental sciences/Environmental sciences/Environmental chemistry/Environmental monitoring Figures Figure 1 Figure 2 Introduction Mercury (Hg) is a highly neurotoxic compound, entering marine ecosystems through atmospheric transport, coastal erosion, and riverine export, where it bioaccumulates and biomagnifies in food webs 1 . In the Arctic, elevated Hg levels in marine fish, birds, and mammals are well documented 2 , and Indigenous People who harvest and consume marine resources are disproportionately exposed to contamination 3 . Indeed, Hg contamination in Arctic marine systems is of high environmental and societal concern, and the risk of contamination is exacerbated by Arctic amplification (the Arctic’s amplified warming), accelerating permafrost thaw, cryosphere melt, and increasing rainfall and soil erosion 4 . Thus, providing accurate information on Hg contamination is important as both communities and nations rely on marine resources for food and export industries. Arctic Hg contamination has been continuously monitored across the terrestrial, aquatic, and atmospheric realms for decades, and the Arctic Monitoring & Assessment Program (AMAP) under the Arctic Council has published several comprehensive reports on the status of Hg 2,5 . Notably, a recent study by Hawkings et al. 6 reported an unaccounted-for and unprecedented discharge of Hg from melting glaciers in Southwest Greenland. The influx was estimated to represent ~10% of the global riverine Hg flux, and the alarming results raised concerns over the associated societal and ecosystem-wide consequences. However, there are substantial disparities among this study and other studies reporting very low and insignificant Hg contributions of meltwater to downstream waters and sediments in Greenland’s catchments and fjords 7–9 , and the role of glaciers and the Greenland Ice Sheet as a Hg source remains debated. For example, a re-examination of Hg in sediments from Southwest Greenland catchments showed very low levels of Hg contamination 7 . However, sediment Hg concentrations may be uncorrelated to concentrations of the biota 10 . Thus, there is a need to establish robust datasets on biota Hg concentrations to gain a more holistic understanding of potential Hg contamination from glacial meltwater. To this end, sessile benthic species are excellent bioindicators for contamination, and they represent an important pathway for Hg incorporation into food webs. For instance, bivalves and macroalgal species have been extensively used as indicator species in monitoring programs in Greenland, and globally. Results and discussion Here we measured Hg concentration in bivalves and macroalgae collected in three Southwest Greenland fjords over a time frame of 13 years. We document negligeable Hg levels, with no increase over time or correlation with glacial melt, emphasizing that glacial melt is not a biologically significant source of Hg contamination. Specifically, we determined Hg concentrations in three foundation species, the blue mussel ( Mytilus edulis ) and the brown canopy-forming macroalgae Fucus vesiculosus and Ascophyllum nodosum . Mytilus edulis and F. vesiculosus were measured along an inland-ocean gradient of glacial meltwater in Nuup Kangerlua and Ameralik, two neighbouring Southwest Greenland fjords adjacent to the Greenland Ice Sheet (Fig. 1). Furthermore, we related temporal trends in meltwater runoff from the Qasigiannguit ice cap in Kobbefjord (Fig. 1) to Hg concentrations of A. nodosum over a 13-year period. All measurements documented negligeable concentrations of Hg in the biota as they did not exceed the Oslo-Paris Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) background concentration of 50 ng g -1 dw, defined as the concentration of a contaminant at a pristine uncontaminated site 11 . The Hg concentration in F. vesiculosus was consistently below 7 ng g -1 dw at all sites along the salinity gradients in Nuup Kangerlua and Ameralik (Fig. 2a,b). For M. edulis, average ( ± SD) concentrations ranged 26.6 ± 9.3 ng Hg g -1 dw across sites in Ameralik, and 43.3 ± 11.8 ng g -1 across sites in Nuup Kangerlua with no significant differences among sites in the fjord (Nuup Kangerlua: F 5.39 = 1.85, df = 5, p = 0.13; Ameralik: F 3,24 = 2.31, df = 3, p = 0.10). Mytilus edulis from site G4 (outer fjord site of Nuup Kangerlua) had significantly higher Hg levels (55.9 ± 17.3 ng g -1 ) than mussels at the oceanic sites Y1 (30 ± 11.3 ng g -1 ) and Y2 (29.9 ± 13.7 ng g -1 ) (p 0.05). The mean Hg concentration of A. nodosum from Kobbefjord ranged between 4.9 and 20.2 ng Hg g -1 dw (Fig. 2c). The Hg levels of A. nodosum were uncorrelated to the meltwater runoff from the nearby glacier (t = -2.02, p > 0.05). The studied fjords have different types of glaciers; Nuup Kangerlua is influenced by marine-terminating glaciers, while Ameralik and Kobbefjord only receive glacial meltwater from land-terminating glaciers. For the same fjords, a previous study concluded that up to 43 tonnes of dissolved Hg were annually discharged from Southwest Greenland glaciers alone 6 . However, regardless of the fjord system, year of study, or type of biota, our data show no trace of contamination as the Hg concentrations in the biota remained below the OSPAR background concentration reflecting pristine conditions. Therefore, we conclude that glacial meltwater runoff is not contaminating sessile benthic species with Hg. Our study thereby supports recent findings of no evidence of Hg contamination or bioaccumulation in planktonic species from West Greenland fjords 12 . The results also align with other recent studies on Hg budgets in West and East Greenlandic fjords. For example, a study on Hg in water and sediment samples across 21 glacial outlets in West Greenland 7 as well as a full-water-column study of Hg distribution in the East Greenland Sermilik fjord 9 concluded that glacial meltwater has insignificant implications for Hg budgets. By contrast, in Sermilik Fjord, the Hg content increased from the glacier towards the ocean, a pattern attributed to the fjord being a net sink of oceanic Hg 9 . This pattern is supported by our results where the highest concentrations in Nuup Kangerlua were also observed in the outer fjord (G4). Our findings add to the now substantial evidence against the claim that glacial meltwater is a major source of mercury, suggesting that methodological or analytical biases may unintentionally have contributed to irreproducible results by Hawkins et al 6 , as discussed elsewhere 7 . The publication of negative results, such as these, and scrutiny of unusual scientific results, are critical to upholding scientific rigor, safeguarding public trust in science, and solving the reproducibility crisis in scientific research 13–15 . In the current case, the “negative” results are indeed positive when considering the wide-ranging implications that the claimed mercury contamination could have had on natural systems, coastal economies, and societies. Methods Intertidal Mytilus edulis and Fucus vesiculosus were collected during low tide in August 2023 in both Nuup Kangerlua and Ameralik. Mytilus edulis was also collected on a small island outside the fjords (site Y1 and Y2) (Fig. 1). Ascophyllum nodosum, which forms an annual air bladder allowing reconstruction of tissue age 16 , was obtained from the inner part of Kobbefjord through different samplings: 1) New samples of long >10-year old specimens collected in September 2023, allowing reconstruction of annually sequentially formed tissue over the period 2013-2023; 2) Archival samples (stored at Aarhus University, Denmark) of 1 year old tissue segments collected by the Greenland Ecosystem Monitoring Program over the period 2012-2023 and, hence, representing tissue formed sequentially over the years 2011-2022. All biota tissue samples were dried in a drying oven at 60°C for 48 h or until constant weight and subsequently grinded. Mercury analyses Total mercury was determined by means of a Milestone DMA-80 Direct Mercury Analyser. The quality of the determinations was validated by incorporation of a certified reference material from the Canadian National Research Council (TORT-standards; lobster hepatopancreas) in each series. The TORT-standard has a certified value of 270 ± 60 ng Hg g -1 . Seven determinations gave a mean value of 288 ± 4.4 ng Hg g -1 (mean ± SEM). Blanks were included in each series. Mussel and algal samples of 20-50 and 100-200 mg dried material, respectively, were analysed. Statistical analyses Variation in Hg concentrations among sites were assed using ANOVAs. TukeyHSD post hoc pair-wise tests were used to compare significant effects. Hg concentration was log-transformed to ensure homogeneity and normality of distribution. The Hg concentration at site G4 was compared to the background concentration using Wilcox test. The relationship between A . nodosum Hg concentrations and run-off was assessed using Pearson’s correlation coefficients. Declarations Acknowledgements JT acknowledges support from the Carlsberg Foundation (CF21-0564) and Independent Research Fund Denmark (grant ID: 10.46540/3120-00045B). DKJ acknowledges support from The European Union's Horizon 2020 through Polar Ocean Mitigation Potential project (POMP: 101136875) and from the Greenland Ecosystem Monitoring program (https://g-e-m.dk/, MarineBasis Nuuk). We thank Núria Marbà, Constança Albuquerque and Carlos Duarte for contributing to the collection and processing of Ascophyllum nodosum . Competing interests We declare no competing interests. Data availability The data used in Fig. 2 is available via Zenodo at https://doi.org/10.5281/zenodo.14621741, and the glacial runoff data presented in Fig. 2c is available at https://data.g-e-m.dk. References Douglas, T. A. et al. The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review. Env Chem 9, 321–355 (2012). AMAP. AMAP Assessment 2021: Mercury in the Arctic. Arctic Monitoring and Assessment Programme (AMAP), Tromsø, Norway. Viii + 324pp. (2021). Adlard, B. et al. Levels and trends of metals in human populations living in the Arctic. Int J Circumpolar Health 83, (2024). Dastoor, A. et al. Arctic mercury cycling. Nat Rev Earth Environ 3, 270–286 (2022). AMAP. AMAP Assessment 2011: Mercury in the Arctic. Arctic Monitoring and Assessment Programme (AMAP), Oslo, Norway. Xiv + 193 Pp. (2011). Hawkings, J. R. et al. Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet. Nat Geosci 14, 496–502 (2021). Jørgensen, C. J. et al. Large mercury release from the Greenland Ice Sheet invalidated. Sci Adv 10, eadi7760 (2024) Søndergaard, J., Rigét, F., Tamstorf, M. P. & Larsen, M. M. Mercury transport in a low-arctic river in Kobbefjord, West Greenland (64° N). Water Air Soil Pollut 223, 4333–4342 (2012). Lindeman, M. R., Straneo, F., Adams, H. M., Nelson, M. J. S. & Schartup, A. T. Low mercury concentrations in a Greenland glacial fjord attributed to oceanic sources. Commun Earth Environ 5, 1–10 (2024). Bjerregaard, P., Schmidt, T. G. & Mose, M. P. Elevated mercury concentrations in biota despite reduced sediment concentrations in a contaminated coastal area, Harboøre Tange, Denmark. Environ Pollut 260, 113985 (2020). OSPAR. Background Document on CEMP Assessment Criteria for the QSR 2010. pp. 23 . (2009). Asiedu, D. A., Søndergaard, J., Jónasdóttir, S., Juul-Pedersen, T. & Koski, M. Concentration of mercury and other metals in an Arctic planktonic food web under a climate warming scenario. Mar Pollut Bull 194, 115436 (2023). Baker, M. Is there a reproducibility crisis? Nature 533, 452–454 (2016). Brazil, R. Illuminating ‘the ugly side of science’: fresh incentives for reporting negative results. Nature (2024) 10.1038/D41586-024-01389-7 West, J. D. & Bergstrom, C. T. Misinformation in and about science. Proc Natl Acad Sci 118, e1912444117 (2021). Baardseth, E. Synopsis of biological data on knobbed wrack Ascophyllum nodosum. FAO Fish Synopsis 38, 1–40 (1970). Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Posted Version 1 posted 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-8804831","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":586912777,"identity":"808c9f0e-52de-4bf3-8fa5-0dca597980f6","order_by":0,"name":"Jakob Thyrring","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA1klEQVRIiWNgGAWjYDACCRBhwMDAjxBKw6+DB6ZFsoE0LSBdB4jVYi/dY/a5ouCO3ebjzQ8f/mCwS2xgT0vAb4vMGeOZZwyeJW87c8zYmIchObGB59kB/FokcowZGwwOJ5vdyGGTZmBgTmyQSG8gTovx/Ddskj8Y6onXYmcgwcMmwcNwGKgljYDDbqQVg7QkSJxJA/rF4LhxG8+zBLxa2Gckb2Zs+HPYnr/9MDDEKqpl+9nTDPBqYWDgACtIhLgfyGYjoB5kzwMQaU9Y4SgYBaNgFIxYAAD7EUD2dKYrxwAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0002-1029-3105","institution":"Aarhus University","correspondingAuthor":true,"prefix":"","firstName":"Jakob","middleName":"","lastName":"Thyrring","suffix":""},{"id":586912778,"identity":"1dce4742-3c50-4392-aa67-7346f7aa0a40","order_by":1,"name":"Dorte Krause-Jensen","email":"","orcid":"https://orcid.org/0000-0001-9792-256X","institution":"Aarhus University","correspondingAuthor":false,"prefix":"","firstName":"Dorte","middleName":"","lastName":"Krause-Jensen","suffix":""},{"id":586912779,"identity":"53bcf988-5ba2-484e-8ce2-91864cb9a127","order_by":2,"name":"Birgit Olesen","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Birgit","middleName":"","lastName":"Olesen","suffix":""},{"id":586912780,"identity":"4a85b706-8e49-42ae-9498-62beb4ffd327","order_by":3,"name":"Poul Bjerregaard","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Poul","middleName":"","lastName":"Bjerregaard","suffix":""}],"badges":[],"createdAt":"2026-02-06 09:01:23","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8804831/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8804831/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":102984089,"identity":"2a0453df-18c1-44f8-8438-28146f2b597d","added_by":"auto","created_at":"2026-02-19 09:51:19","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":590820,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSampling sites in Southwest Greenland fjords. \u003c/strong\u003eSpecimens of \u003cem\u003eMytilus edulis\u003c/em\u003e and \u003cem\u003eFucus vesiculosus\u003c/em\u003e were collected at four sites in the\u003cstrong\u003e \u003c/strong\u003eAmeralik (A1–A4) and Nuup Kangerlua (G1–G4) fjord systems, and at two oceanic sites (Y1–Y2). \u003cem\u003eAscophyllum nodosum \u003c/em\u003ewas collected in the inner part of Kobbefjord (red dot). Satellite image provided by Google Earth.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8804831/v1/15291a852d0c825804c6ccdc.png"},{"id":102984088,"identity":"8980c6e8-3007-46c9-a082-7f963f215015","added_by":"auto","created_at":"2026-02-19 09:51:19","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":37803,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMean (±SD, \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003en\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e = 5-10) mercury concentration in biota: \u003c/strong\u003e\u003cem\u003eMytilus edulis \u003c/em\u003eand \u003cem\u003eFucus vesiculosus\u003c/em\u003e\u003cstrong\u003e \u003c/strong\u003ealong an inland-ocean gradient in Nuup Kangerlua (a)\u003cem\u003e \u003c/em\u003eand Ameralik (b). Temporal trends for \u003cem\u003eAscophyllum\u0026nbsp;nodosum\u003c/em\u003e in relation to annual meltwater runoff from the Qasigiannguit ice cap (light-blue line) in the Kobbefjord (c). Data in (c) represent retrospective analyses of annual growth segments from \u0026gt;10-year-old specimens collected in 2023 (New specimen; 2013-2023), and analyses of specimens from the Greenland Ecosystem Monitoring Program collection (Archival specimen; 2011–2022). Dotted line represents the OSPAR background concentration of 50 ng Hg g\u003csup\u003e-1\u003c/sup\u003e\u0026nbsp;dw, defined as the concentration of a contaminant at a pristine uncontaminated site.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8804831/v1/871f465c132b1a47ac224793.png"},{"id":105567205,"identity":"81c9027f-5413-43a7-9eb7-d76e7d761c01","added_by":"auto","created_at":"2026-03-27 12:58:41","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":918693,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8804831/v1/f2c0f97f-4e02-4173-8d11-3dbafc818117.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"No mercury from Greenland glacial runoff in sessile coastal biota","fulltext":[{"header":"Introduction","content":"\u003cp\u003eMercury (Hg) is a highly neurotoxic compound, entering marine ecosystems through atmospheric transport, coastal erosion, and riverine export, where it bioaccumulates and biomagnifies in food webs\u003csup\u003e1\u003c/sup\u003e. In the Arctic, elevated Hg levels in marine fish, birds, and mammals are well documented\u003csup\u003e2\u003c/sup\u003e, and Indigenous People who harvest and consume marine resources are disproportionately exposed to contamination\u003csup\u003e3\u003c/sup\u003e. Indeed, Hg contamination in Arctic marine systems is of high environmental and societal concern, and the risk of contamination is exacerbated by Arctic amplification (the Arctic\u0026rsquo;s amplified warming), accelerating permafrost thaw, cryosphere melt, and increasing rainfall and soil erosion\u003csup\u003e4\u003c/sup\u003e. Thus, providing accurate information on Hg contamination is important as both communities and nations rely on marine resources for food and export industries.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eArctic Hg contamination has been continuously monitored across the terrestrial, aquatic, and atmospheric realms for decades, and the Arctic Monitoring \u0026amp; Assessment Program (AMAP) under the Arctic Council has published several comprehensive reports on the status of Hg\u003csup\u003e2,5\u003c/sup\u003e. Notably, a recent study by Hawkings et al.\u003csup\u003e6\u003c/sup\u003e reported an unaccounted-for and unprecedented discharge of Hg from melting glaciers in Southwest Greenland. The influx was estimated to represent ~10% of the global riverine Hg flux, and the alarming results raised concerns over the associated societal and ecosystem-wide consequences. However, there are substantial disparities among this study and other studies reporting very low and insignificant Hg contributions of meltwater to downstream waters and sediments in Greenland\u0026rsquo;s catchments and fjords\u003csup\u003e7\u0026ndash;9\u003c/sup\u003e, and the role of glaciers and the Greenland Ice Sheet as a Hg source remains debated. For example, a re-examination of Hg in sediments from Southwest Greenland catchments showed very low levels of Hg contamination\u003csup\u003e7\u003c/sup\u003e. However, sediment Hg concentrations may be uncorrelated to concentrations of the biota\u003csup\u003e10\u003c/sup\u003e. Thus, there is a need to establish robust datasets on biota Hg concentrations to gain a more holistic understanding of potential Hg contamination from glacial meltwater. To this end, sessile benthic species are excellent bioindicators for contamination, and they represent an important pathway for Hg incorporation into food webs. For instance, bivalves and macroalgal species have been extensively used as indicator species in monitoring programs in Greenland, and globally.\u003c/p\u003e"},{"header":"Results and discussion","content":"\u003cp\u003eHere we measured Hg concentration in bivalves and macroalgae collected in three Southwest Greenland fjords over a time frame of 13 years. We document negligeable Hg levels, with no increase over time or correlation with glacial melt, emphasizing that glacial melt is not a biologically significant source of Hg contamination. Specifically, we determined Hg concentrations in three foundation species, the blue mussel (\u003cem\u003eMytilus edulis\u003c/em\u003e) and the brown canopy-forming macroalgae \u003cem\u003eFucus vesiculosus\u003c/em\u003e and \u003cem\u003eAscophyllum nodosum\u003c/em\u003e. \u003cem\u003eMytilus edulis\u003c/em\u003e and \u003cem\u003eF. vesiculosus\u003c/em\u003e were measured along an inland-ocean gradient of glacial meltwater in Nuup Kangerlua and Ameralik, two neighbouring Southwest Greenland fjords adjacent to the Greenland Ice Sheet (Fig. 1). Furthermore, we related temporal trends in meltwater runoff from the Qasigiannguit ice cap in Kobbefjord (Fig. 1) to Hg concentrations of \u003cem\u003eA. nodosum\u0026nbsp;\u003c/em\u003eover a 13-year period. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll measurements documented negligeable concentrations of Hg in the biota as they did not exceed the Oslo-Paris Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) background concentration of 50 ng g\u003csup\u003e-1\u003c/sup\u003e dw, defined as the concentration of a contaminant at a pristine uncontaminated site\u003csup\u003e11\u003c/sup\u003e. The Hg concentration in \u003cem\u003eF. vesiculosus\u003c/em\u003e was consistently below 7 ng g\u003csup\u003e-1\u0026nbsp;\u003c/sup\u003edw at all sites along the salinity gradients in Nuup Kangerlua and Ameralik (Fig. 2a,b). For \u003cem\u003eM. edulis,\u0026nbsp;\u003c/em\u003eaverage (\u003cstrong\u003e\u0026plusmn;\u003c/strong\u003eSD) concentrations ranged 26.6 \u0026plusmn; 9.3 ng Hg g\u003csup\u003e-1\u0026nbsp;\u003c/sup\u003edw across sites in Ameralik, and 43.3 \u0026plusmn; 11.8 ng g\u003csup\u003e-1\u003c/sup\u003e across sites in Nuup Kangerlua with no significant differences among sites in the fjord (Nuup Kangerlua: F\u003csub\u003e5.39\u003c/sub\u003e= 1.85, df = 5, p = 0.13; Ameralik: F\u003csub\u003e3,24\u003c/sub\u003e = 2.31, df = 3, p = 0.10). \u003cem\u003eMytilus edulis\u0026nbsp;\u003c/em\u003efrom site G4 (outer fjord site of Nuup Kangerlua) had significantly higher Hg levels (55.9 \u0026plusmn; 17.3 ng g\u003csup\u003e-1\u003c/sup\u003e) than mussels at the oceanic sites Y1 (30 \u0026plusmn; 11.3 ng g\u003csup\u003e-1\u003c/sup\u003e) and Y2 (29.9 \u0026plusmn; 13.7 ng g\u003csup\u003e-1\u003c/sup\u003e) (p \u0026lt; 0.05; Fig. 2b); however, even the highest level was not significantly higher than the OSPAR background concentration (Wilcox test: p \u0026gt; 0.05). The mean Hg concentration of \u003cem\u003eA.\u0026nbsp;nodosum\u003c/em\u003e from Kobbefjord ranged between 4.9 and 20.2 ng Hg g\u003csup\u003e-1\u003c/sup\u003e dw (Fig. 2c). The Hg levels of \u003cem\u003eA. nodosum\u003c/em\u003e were uncorrelated to the meltwater runoff from the nearby glacier (t = -2.02, p \u0026gt; 0.05).\u003c/p\u003e\n\u003cp\u003eThe studied fjords have different types of glaciers; Nuup Kangerlua is influenced by marine-terminating glaciers, while Ameralik and Kobbefjord only receive glacial meltwater from land-terminating glaciers. For the same fjords, a previous study concluded that up to 43 tonnes of dissolved Hg were annually discharged from Southwest Greenland glaciers alone\u003csup\u003e6\u003c/sup\u003e. However, regardless of the fjord system, year of study, or type of biota, our data show no trace of contamination as the Hg concentrations in the biota remained below the OSPAR background concentration reflecting pristine conditions. Therefore, we conclude that glacial meltwater runoff is not contaminating sessile benthic species with Hg. Our study thereby supports recent findings of no evidence of Hg contamination or bioaccumulation in planktonic species from West Greenland fjords\u003csup\u003e12\u003c/sup\u003e. The results also align with other recent studies on Hg budgets in West and East Greenlandic fjords. For example, a study on Hg in water and sediment samples across 21 glacial outlets in West Greenland\u003csup\u003e7\u003c/sup\u003e as well as a full-water-column study of Hg distribution in the East Greenland Sermilik fjord\u003csup\u003e9\u003c/sup\u003e concluded that glacial meltwater has insignificant implications for Hg budgets. By contrast, in Sermilik Fjord, the Hg content increased from the glacier towards the ocean, a pattern attributed to the fjord being a net sink of oceanic Hg\u003csup\u003e9\u003c/sup\u003e. This pattern is supported by our results where the highest concentrations in Nuup Kangerlua were also observed in the outer fjord (G4).\u003c/p\u003e\n\u003cp\u003eOur findings add to the now substantial evidence against the claim that glacial meltwater is a major source of mercury, suggesting that methodological or analytical biases may unintentionally have contributed to irreproducible results by Hawkins et al\u003csup\u003e6\u003c/sup\u003e, as discussed elsewhere\u003csup\u003e7\u003c/sup\u003e. The publication of negative results, such as these, and scrutiny of unusual scientific results, are critical to upholding scientific rigor, safeguarding public trust in science, and solving the reproducibility crisis in scientific research\u003csup\u003e13\u0026ndash;15\u003c/sup\u003e. In the current case, the \u0026ldquo;negative\u0026rdquo; results are indeed positive when considering the wide-ranging implications that the claimed mercury contamination could have had on natural systems, coastal economies, and societies.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eIntertidal \u003cem\u003eMytilus edulis\u0026nbsp;\u003c/em\u003eand \u003cem\u003eFucus vesiculosus\u0026nbsp;\u003c/em\u003ewere collected during low tide in August 2023 in both Nuup Kangerlua and Ameralik. \u003cem\u003eMytilus edulis\u0026nbsp;\u003c/em\u003ewas also collected on a small island outside the fjords (site Y1 and Y2) (Fig. 1). \u003cem\u003eAscophyllum nodosum,\u0026nbsp;\u003c/em\u003ewhich forms an annual air bladder allowing reconstruction of tissue age\u003csup\u003e16\u003c/sup\u003e, was obtained from the inner part of Kobbefjord through different samplings: 1) New samples of long \u0026gt;10-year old specimens collected in September 2023, allowing reconstruction of annually sequentially formed tissue over the period 2013-2023; 2) Archival samples (stored at Aarhus University, Denmark) of 1 year old tissue segments collected by the Greenland Ecosystem Monitoring Program over the period 2012-2023 and, hence, representing tissue formed sequentially over the years 2011-2022. All biota tissue samples were dried in a drying oven at 60\u0026deg;C for 48 h or until constant weight and subsequently grinded.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eMercury analyses\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eTotal mercury was determined by means of a Milestone DMA-80 Direct Mercury Analyser. The quality of the determinations was validated by incorporation of a certified reference material from the Canadian National Research Council (TORT-standards; lobster hepatopancreas) in each series. The TORT-standard has a certified value of 270 \u0026plusmn; 60 ng Hg g\u003csup\u003e-1\u003c/sup\u003e. Seven determinations gave a mean value of 288 \u0026plusmn; 4.4 ng Hg g\u003csup\u003e-1\u003c/sup\u003e (mean \u0026plusmn; SEM). Blanks were included in each series. Mussel and algal samples of 20-50 and 100-200 mg dried material, respectively, were analysed.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eStatistical analyses\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eVariation in Hg concentrations among sites were assed using ANOVAs. TukeyHSD post hoc pair-wise tests were used to compare significant effects. Hg concentration was log-transformed to ensure\u0026nbsp;homogeneity and normality of distribution. The Hg concentration at site G4 was compared to the background concentration using Wilcox test. \u0026nbsp;The relationship between \u003cem\u003eA\u003c/em\u003e. \u003cem\u003enodosum\u003c/em\u003e Hg concentrations and run-off was assessed using Pearson\u0026rsquo;s correlation coefficients.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eJT acknowledges support from the Carlsberg Foundation (CF21-0564) and Independent Research Fund Denmark (grant ID: 10.46540/3120-00045B). DKJ acknowledges support from The European Union\u0026apos;s Horizon 2020 through Polar Ocean Mitigation Potential project (POMP: 101136875) and from the Greenland Ecosystem Monitoring program (https://g-e-m.dk/, MarineBasis Nuuk). We thank N\u0026uacute;ria Marb\u0026agrave;, Constan\u0026ccedil;a Albuquerque and Carlos Duarte for contributing to the collection and processing of \u003cem\u003eAscophyllum nodosum\u003c/em\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe declare no competing interests.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data used in Fig. 2 is available via Zenodo at https://doi.org/10.5281/zenodo.14621741, and the glacial runoff data presented in Fig. 2c is available at https://data.g-e-m.dk.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eDouglas, T. A. \u003cem\u003eet al.\u003c/em\u003e The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review. \u003cem\u003eEnv Chem \u003c/em\u003e9, 321\u0026ndash;355 (2012).\u003c/li\u003e\n\u003cli\u003eAMAP. \u003cem\u003eAMAP Assessment 2021: Mercury in the Arctic. Arctic Monitoring and Assessment Programme (AMAP), Troms\u0026oslash;, Norway. Viii + 324pp.\u003c/em\u003e (2021).\u003c/li\u003e\n\u003cli\u003eAdlard, B. \u003cem\u003eet al.\u003c/em\u003e Levels and trends of metals in human populations living in the Arctic. \u003cem\u003eInt J Circumpolar Health\u003c/em\u003e 83, (2024).\u003c/li\u003e\n\u003cli\u003eDastoor, A. \u003cem\u003eet al.\u003c/em\u003e Arctic mercury cycling. \u003cem\u003eNat Rev Earth Environ\u003c/em\u003e 3, 270\u0026ndash;286 (2022).\u003c/li\u003e\n\u003cli\u003eAMAP. \u003cem\u003eAMAP Assessment 2011: Mercury in the Arctic. Arctic Monitoring and Assessment Programme (AMAP), Oslo, Norway. Xiv + 193 Pp.\u003c/em\u003e (2011).\u003c/li\u003e\n\u003cli\u003eHawkings, J. R. \u003cem\u003eet al.\u003c/em\u003e Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet. \u003cem\u003eNat Geosci\u003c/em\u003e 14, 496\u0026ndash;502 (2021).\u003c/li\u003e\n\u003cli\u003eJ\u0026oslash;rgensen, C. J. \u003cem\u003eet al.\u003c/em\u003e Large mercury release from the Greenland Ice Sheet invalidated. \u003cem\u003eSci Adv \u003c/em\u003e10, eadi7760 (2024) \u003c/li\u003e\n\u003cli\u003eS\u0026oslash;ndergaard, J., Rig\u0026eacute;t, F., Tamstorf, M. P. \u0026amp; Larsen, M. M. Mercury transport in a low-arctic river in Kobbefjord, West Greenland (64\u0026deg; N). \u003cem\u003eWater Air Soil Pollut\u003c/em\u003e 223, 4333\u0026ndash;4342 (2012).\u003c/li\u003e\n\u003cli\u003eLindeman, M. R., Straneo, F., Adams, H. M., Nelson, M. J. S. \u0026amp; Schartup, A. T. Low mercury concentrations in a Greenland glacial fjord attributed to oceanic sources. \u003cem\u003eCommun Earth Environ\u003c/em\u003e 5, 1\u0026ndash;10 (2024).\u003c/li\u003e\n\u003cli\u003eBjerregaard, P., Schmidt, T. G. \u0026amp; Mose, M. P. Elevated mercury concentrations in biota despite reduced sediment concentrations in a contaminated coastal area, Harbo\u0026oslash;re Tange, Denmark. \u003cem\u003eEnviron Pollut\u003c/em\u003e 260, 113985 (2020).\u003c/li\u003e\n\u003cli\u003eOSPAR. \u003cem\u003eBackground Document on CEMP Assessment Criteria for the QSR 2010. pp. 23\u003c/em\u003e. (2009).\u003c/li\u003e\n\u003cli\u003eAsiedu, D. A., S\u0026oslash;ndergaard, J., J\u0026oacute;nasd\u0026oacute;ttir, S., Juul-Pedersen, T. \u0026amp; Koski, M. Concentration of mercury and other metals in an Arctic planktonic food web under a climate warming scenario. \u003cem\u003eMar Pollut Bull\u003c/em\u003e 194, 115436 (2023).\u003c/li\u003e\n\u003cli\u003eBaker, M. Is there a reproducibility crisis? \u003cem\u003eNature\u003c/em\u003e 533, 452\u0026ndash;454 (2016).\u003c/li\u003e\n\u003cli\u003eBrazil, R. Illuminating \u0026lsquo;the ugly side of science\u0026rsquo;: fresh incentives for reporting negative results. \u003cem\u003eNature\u003c/em\u003e (2024) 10.1038/D41586-024-01389-7\u003c/li\u003e\n\u003cli\u003eWest, J. D. \u0026amp; Bergstrom, C. T. Misinformation in and about science. \u003cem\u003eProc Natl Acad Sci\u003c/em\u003e 118, e1912444117 (2021).\u003c/li\u003e\n\u003cli\u003eBaardseth, E. Synopsis of biological data on knobbed wrack Ascophyllum nodosum. \u003cem\u003eFAO Fish Synopsis\u003c/em\u003e 38, 1\u0026ndash;40 (1970).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8804831/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8804831/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMelting glaciers have been claimed to be a significant and unaccounted-for source of mercury (Hg) in Greenland, raising concerns for economics, communities and ecosystem health. Here we demonstrate, however, that benthic species from Greenland fjords contain negligible concentrations of mercury across \u0026gt;\u0026thinsp;100 km spatial gradients and decadal time scales. Our results, together with other studies on Hg in Greenland\u0026rsquo;s waters, sediments, and planktonic species, cannot reproduce the previously reported mercury contamination from glaciers, and there is now substantial evidence against the claim that Greenland ice sheet has implications for Hg budgets and coastal ecosystems.\u003c/p\u003e","manuscriptTitle":"No mercury from Greenland glacial runoff in sessile coastal biota","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-19 09:51:15","doi":"10.21203/rs.3.rs-8804831/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a6b6629c-f339-41fd-9871-05ea874dc08d","owner":[],"postedDate":"February 19th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":62447646,"name":"Biological sciences/Ecology/Ecophysiology"},{"id":62447647,"name":"Earth and environmental sciences/Environmental sciences/Environmental chemistry/Environmental monitoring"}],"tags":[],"updatedAt":"2026-03-27T11:31:33+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-19 09:51:15","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8804831","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8804831","identity":"rs-8804831","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}