Geochemical Baselines and Contamination Sources of Heavy Metals in Urban Soils of the Kathmandu Valley

Geochemical Baselines and Contamination Sources of Heavy Metals in Urban Soils of the Kathmandu Valley | 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 Geochemical Baselines and Contamination Sources of Heavy Metals in Urban Soils of the Kathmandu Valley Hemu Kharel Kafle, Saurav Marahatta, Sapana Bhujel, Ram Kumar Shrestha, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8500418/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 Geochemical Baseline Values (GBVs) provide a critical reference for distinguishing between inherent elemental concentrations and anthropogenic accumulation. This study establishes GBVs of twenty-two elements, in the soils of the Kathmandu Valley. Elemental analysis of 106 soil samples was carried out using DELTA X-ray Fluorescent Spectrometer. Local GBVs are further applied to estimate the pollution status of heavy metals, with results compared against standard global background values. Soil contamination was quantified using pollution indices and the Enrichment Factor (EF). Soil fertility was assessed via soil organic matter (SOM) content, and its relationship with heavy metals was investigated using Pearson coefficient matrix. Pollution source identification was performed using Principal Component Analysis (PCA). Among three methodological approaches, the kneedle algorithm, proved most suitable for defining GBVs in our study area. The established baselines for Tungsten (15.33 mg/kg), Rubidium (170.59 mg/kg), Thorium (22.88 mg/kg), Uranium (5.18 mg/kg), Cadmium (10.96 mg/kg), and Zinc (112.17 mg/kg) exceeded global averages. Local GBVs revealed significant contamination and increased enrichment by Copper (Cu), Lead (Pb), and Manganese (Mn), whereas global references showed the high contamination of Cadmium (Cd) and Arsenic (As). Kathmandu valley soils exhibited moderate SOM content (3.03%). PCA analysis delineated three distinct sources; a lithogenic factor (Mn, Ni, As, Cr), an anthropogenic factor (Zn, Cu, Pb) linked to SOM, and an isolated Cd dominated factor. This research demonstrates the necessity of region-specific baselines for reliable environmental assessment and provides a clear, multi method delineation of contaminant sources. Geochemical baseline values Heavy metals Kathmandu Valley Pollution indices Soil contamination Full Text Additional Declarations No competing interests reported. Supplementary Files SupplementaryFile.docx 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-8500418","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":569757768,"identity":"4a15cb6c-08b6-41fe-a112-d93f8a95755e","order_by":0,"name":"Hemu Kharel Kafle","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA1klEQVRIiWNgGAWjYBACAx4Ghg8PGGwM2EjRwjgjgSGNdC2HDYh3mDnP4YcNCRXnjfnYjz9g+LinlsFcugG/FsveNsOGhDO3zdh4cgwYZzw7zmA55wABh51nMH+Q2Hbbho0hh4GZ58AxBoMbCYS0sH9sSPx3zoaN//kDIrWc7TFsSGw4YMYmkWAA1FJDhJYzZwobEo4lG7NJvDE4OOPAAR6DO4T8ciZ9Y8OHGjvD+f3pDx98OFAnZ3C7Ab8WFAA0/jAPgwQJOkCgjoFkLaNgFIyCUTDsAQCs2UkbuePnUQAAAABJRU5ErkJggg==","orcid":"","institution":"Kathmandu Institute of Applied Sciences","correspondingAuthor":true,"prefix":"","firstName":"Hemu","middleName":"Kharel","lastName":"Kafle","suffix":""},{"id":569757771,"identity":"3ff69ad8-9c6e-4d9b-9e23-42bc37770bd7","order_by":1,"name":"Saurav Marahatta","email":"","orcid":"","institution":"Tribhuvan University","correspondingAuthor":false,"prefix":"","firstName":"Saurav","middleName":"","lastName":"Marahatta","suffix":""},{"id":569757774,"identity":"43b57f69-1590-4449-93e0-5cbadfc224f5","order_by":2,"name":"Sapana Bhujel","email":"","orcid":"","institution":"Kathmandu Institute of Applied Sciences","correspondingAuthor":false,"prefix":"","firstName":"Sapana","middleName":"","lastName":"Bhujel","suffix":""},{"id":569757776,"identity":"e44e351b-85e3-46d0-b6ce-1f5e5c5f9778","order_by":3,"name":"Ram Kumar Shrestha","email":"","orcid":"","institution":"Tribhuvan University","correspondingAuthor":false,"prefix":"","firstName":"Ram","middleName":"Kumar","lastName":"Shrestha","suffix":""},{"id":569757780,"identity":"818805ce-03a0-4f16-a252-de6c00e199cc","order_by":4,"name":"Roshan Babu Ojha","email":"","orcid":"","institution":"Nepal Agricultural Research Council","correspondingAuthor":false,"prefix":"","firstName":"Roshan","middleName":"Babu","lastName":"Ojha","suffix":""}],"badges":[],"createdAt":"2026-01-02 11:23:36","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8500418/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8500418/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":101942691,"identity":"196fbbb6-1825-4cff-9514-90ffc0c7ce45","added_by":"auto","created_at":"2026-02-05 09:33:57","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1234463,"visible":true,"origin":"","legend":"","description":"","filename":"Mnauscriptsoil.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8500418/v1_covered_64bca48f-979a-4735-92d0-2ff2cdf4dfdf.pdf"},{"id":100910505,"identity":"42ed3e2e-5902-481b-8fb2-43feac37ce5b","added_by":"auto","created_at":"2026-01-22 16:52:23","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":223931,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryFile.docx","url":"https://assets-eu.researchsquare.com/files/rs-8500418/v1/d2121c0f25ff1265aeb822b0.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Geochemical Baselines and Contamination Sources of Heavy Metals in Urban Soils of the Kathmandu Valley","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"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":"Geochemical baseline values, Heavy metals, Kathmandu Valley, Pollution indices, Soil contamination","lastPublishedDoi":"10.21203/rs.3.rs-8500418/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8500418/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eGeochemical Baseline Values (GBVs) provide a critical reference for distinguishing between inherent elemental concentrations and anthropogenic accumulation. This study establishes GBVs of twenty-two elements, in the soils of the Kathmandu Valley. Elemental analysis of 106 soil samples was carried out using DELTA X-ray Fluorescent Spectrometer. Local GBVs are further applied to estimate the pollution status of heavy metals, with results compared against standard global background values. Soil contamination was quantified using pollution indices and the Enrichment Factor (EF). Soil fertility was assessed via soil organic matter (SOM) content, and its relationship with heavy metals was investigated using Pearson coefficient matrix. Pollution source identification was performed using Principal Component Analysis (PCA). Among three methodological approaches, the kneedle algorithm, proved most suitable for defining GBVs in our study area. The established baselines for Tungsten (15.33 mg/kg), Rubidium (170.59 mg/kg), Thorium (22.88 mg/kg), Uranium (5.18 mg/kg), Cadmium (10.96 mg/kg), and Zinc (112.17 mg/kg) exceeded global averages. Local GBVs revealed significant contamination and increased enrichment by Copper (Cu), Lead (Pb), and Manganese (Mn), whereas global references showed the high contamination of Cadmium (Cd) and Arsenic (As). Kathmandu valley soils exhibited moderate SOM content (3.03%). PCA analysis delineated three distinct sources; a lithogenic factor (Mn, Ni, As, Cr), an anthropogenic factor (Zn, Cu, Pb) linked to SOM, and an isolated Cd dominated factor. This research demonstrates the necessity of region-specific baselines for reliable environmental assessment and provides a clear, multi method delineation of contaminant sources.\u003c/p\u003e","manuscriptTitle":"Geochemical Baselines and Contamination Sources of Heavy Metals in Urban Soils of the Kathmandu Valley","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-22 16:52:18","doi":"10.21203/rs.3.rs-8500418/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":"6cae7a03-2f56-400c-97bf-be77cb8c8d40","owner":[],"postedDate":"January 22nd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-02-02T15:41:34+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-22 16:52:18","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8500418","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8500418","identity":"rs-8500418","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}