Impacts Of A Single Untreated Domestic Effluent Discharge On Water Quality In An Amazonian Urban Stream: An Integrated Assessment Using Wqi And Legal Compliance Indicators

Impacts Of A Single Untreated Domestic Effluent Discharge On Water Quality In An Amazonian Urban Stream: An Integrated Assessment Using Wqi And Legal Compliance Indicators | 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 Impacts Of A Single Untreated Domestic Effluent Discharge On Water Quality In An Amazonian Urban Stream: An Integrated Assessment Using Wqi And Legal Compliance Indicators Edinelson Saldanha, Vando Jose Gomes, Ana Clara Anjo, Ruan Felix, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8817075/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract Urban streams are highly vulnerable to localized sources of pollution, particularly untreated domestic effluent discharges, even in regions characterized by high freshwater availability. This study evaluated the impacts of a single untreated domestic wastewater discharge on water quality in an urban tropical stream located in the Amazon region, using an integrated assessment framework combining the Water Quality Index (WQI) and a Legal Compliance Index (LCI). Physicochemical and microbiological parameters were monitored at three sampling points—upstream, at the effluent discharge, and downstream—during rainy and dry seasons. The results revealed severe degradation of water quality at points directly and indirectly influenced by effluent discharge, with recurrent exceedances of legal thresholds for dissolved oxygen, biochemical oxygen demand, total phosphorus, turbidity, and microbiological indicators. WQI values classified water quality as poor to very poor at all impacted points, with minimal variation between hydrological periods, indicating the dominance of continuous point-source pollution over seasonal effects. The LCI analysis confirmed widespread legal non-compliance, demonstrating that a single discharge point controlled the overall regulatory condition of the stream. The combined application of WQI and LCI provided a robust and complementary diagnosis of environmental and legal water quality conditions, highlighting limitations of relying solely on natural dilution capacity in water-abundant regions. The findings emphasize the need for targeted wastewater management interventions and spatially explicit monitoring strategies to protect urban streams. The integrated assessment framework applied in this study is transferable and can support water quality monitoring and management in other urban watersheds affected by localized pollution sources, particularly in rapidly urbanizing tropical regions. Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 14 May, 2026 Reviews received at journal 30 Mar, 2026 Reviewers agreed at journal 09 Mar, 2026 Reviewers invited by journal 08 Mar, 2026 Editor assigned by journal 26 Feb, 2026 Submission checks completed at journal 26 Feb, 2026 First submitted to journal 07 Feb, 2026 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-8817075","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":591124746,"identity":"60f1d345-8d2f-4da7-a188-57a74e2f92e9","order_by":0,"name":"Edinelson 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This study evaluated the impacts of a single untreated domestic wastewater discharge on water quality in an urban tropical stream located in the Amazon region, using an integrated assessment framework combining the Water Quality Index (WQI) and a Legal Compliance Index (LCI). Physicochemical and microbiological parameters were monitored at three sampling points\u0026mdash;upstream, at the effluent discharge, and downstream\u0026mdash;during rainy and dry seasons.\u003c/p\u003e \u003cp\u003eThe results revealed severe degradation of water quality at points directly and indirectly influenced by effluent discharge, with recurrent exceedances of legal thresholds for dissolved oxygen, biochemical oxygen demand, total phosphorus, turbidity, and microbiological indicators. WQI values classified water quality as poor to very poor at all impacted points, with minimal variation between hydrological periods, indicating the dominance of continuous point-source pollution over seasonal effects. 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