Prediction of reaeration and deoxygenation rate constant in Selbe River, Mongolia: Dissolved oxygen and BOD assimilative capacity of the river

Prediction of reaeration and deoxygenation rate constant in Selbe River, Mongolia: Dissolved oxygen and BOD assimilative capacity of the river | 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 Research Article Prediction of reaeration and deoxygenation rate constant in Selbe River, Mongolia: Dissolved oxygen and BOD assimilative capacity of the river Usukhbayar Puntsagsuren, Bodigerel Lkhagvasuren, Gerelt-Od Dashdondog, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5035103/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 In rivers, the processes of deoxygenation and reaeration play crucial roles in self-purification, particularly influenced by temperature changes. This study is the first to consider Mongolia's river's dissolved oxygen (DO) and biochemical oxygen demand (BOD) assimilative capacity. The objective of the study was to determine the deoxygenation rate (k 1 ) and the reaeration rate (k 2 ) constants of the Selbe River, in Ulaanbaatar, Mongolia. The mean k 1 was calculated using two models, namely the Thomas slope and first-order function methods. The results showed that the first-order function model was more suitable for describing k 1 , which is 0.116 ± 0.012 and 0.266 ± 0.0281 respectively in 10 and e of logarithm base because the sampling standard deviation of the model we used is more reliable than the Thomas method. The mean k 2 was estimated by 8 models out of 22 different available models. Jha’s model was more reasonable because it had the lowest sampling standard deviation compared with other models. Accordingly, the mean k 2 in the Selbe River was found to be 3.41 ± 0.67 at 4.97 mean temperature of Celsius. As a result of using k 1 and k 2 , there is 0.7 mg/L of mean critical oxygen deficit, 0.3 d of critical time, and 4.7 km of the longest distance using the purification model for steady-state at 20ºC because non-point pollution sources occurred in most sampling points. Additionally, considerations should include the trend towards stronger rainfall events, changes in land use density with an increasing number of pit latrines, variations in soil types, and the presence of private wells, all of which are potential drivers of changes in water hygiene. Hydrology BOD Dissolved oxygen deoxygenation rate reaeration rate critical time and deficit oxygen Full Text Additional Declarations The authors declare no competing interests. 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. 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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-5035103","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":349785974,"identity":"fa86afa8-7bdf-4900-a2b3-f25b5cecb60b","order_by":0,"name":"Usukhbayar Puntsagsuren","email":"","orcid":"","institution":"German-Mongolian Institute for resources and Technology","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Usukhbayar","middleName":"","lastName":"Puntsagsuren","suffix":""},{"id":349785975,"identity":"2f8e985c-b4c9-4592-a4f9-b01774636102","order_by":1,"name":"Bodigerel 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declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003ePrediction of reaeration and deoxygenation rate constant in Selbe River, Mongolia: Dissolved oxygen and BOD assimilative capacity of the river\u003c/strong\u003e\u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"German-Mongolian Institute for resources and 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processes of deoxygenation and reaeration play crucial roles in self-purification, particularly influenced by temperature changes. This study is the first to consider Mongolia's river's dissolved oxygen (DO) and biochemical oxygen demand (BOD) assimilative capacity. The objective of the study was to determine the deoxygenation rate (k\u003csub\u003e1\u003c/sub\u003e) and the reaeration rate (k\u003csub\u003e2\u003c/sub\u003e) constants of the Selbe River, in Ulaanbaatar, Mongolia. The mean k\u003csub\u003e1\u003c/sub\u003e was calculated using two models, namely the Thomas slope and first-order function methods. The results showed that the first-order function model was more suitable for describing k\u003csub\u003e1\u003c/sub\u003e, which is 0.116 ± 0.012 and 0.266 ± 0.0281 respectively in 10 and e of logarithm base because the sampling standard deviation of the model we used is more reliable than the Thomas method. The mean k\u003csub\u003e2\u003c/sub\u003e was estimated by 8 models out of 22 different available models. Jha’s model was more reasonable because it had the lowest sampling standard deviation compared with other models. Accordingly, the mean k\u003csub\u003e2\u003c/sub\u003e in the Selbe River was found to be 3.41 ± 0.67 at 4.97 mean temperature of Celsius. As a result of using k\u003csub\u003e1\u003c/sub\u003e and k\u003csub\u003e2\u003c/sub\u003e, there is 0.7 mg/L of mean critical oxygen deficit, 0.3 d of critical time, and 4.7 km of the longest distance using the purification model for steady-state at 20ºC because non-point pollution sources occurred in most sampling points. 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