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<p>This study examines the distribution of rare earth elements (REEs) in suspended particulate matter (SPM) collected from 50 sites along the Indus River Basin to distinguish between natural and anthropogenic controls on sediment geochemistry. Natural processes dominate bulk REE fluxes, with Himalayan granitic and metamorphic rocks contributing elevated ΣREE concentrations averaging 172.1&#xa0;mg/kg, exceeding Upper Continental Crust values. Weathering signals are expressed through high Chemical Index of Alteration (CIA) values (87.5–89.9), light REE depletion downstream ((La/Yb)ₙ = 0.33–1.34) via clay adsorption, and heavy REE mobilization through carbonate complexation. In contrast, anthropogenic impacts are marked by strong gadolinium anomalies (δGd &gt; 1.6) associated with medical wastewater and La/Ce enrichment linked to industrial discharges, overprinted on a persistent negative europium anomaly (Eu/Eu* ≈ 0.61) from felsic bedrock. Together, these findings demonstrate that Indus River REE dynamics are shaped by a dual control: Himalayan erosion governs sediment provenance, while unregulated urban inputs introduce emerging contamination risks, underscoring the need for monitoring frameworks in South Asian River systems.</p> Graphical Abstract <p> This graphical abstract summarizes a study on rare earth element (REE) dynamics, focusing on sediment sources, weathering processes, anthropogenic contamination, and ecological risks. The background problem highlights the need to distinguish between natural weathering and human- induced pollution, especially during monsoon seasons. The methods section describes the analysis of 50 suspended particulate matter (SPM) samples using PAAS-normalized patterns, chemical indices, geochemical signatures, and pH conditions, comparing urban and rural areas. Key findings reveal average total REE concentrations of 172.1&#xa0;mg/kg, with light REEs (LREEs) dominating and heavy REEs (HREEs) depleted. Chemical Index of Alteration (CIA) values range from 87.5 to 89.9, indicating significant weathering. Gd anomalies (δGd &gt;1.6) and Eu anomalies (Eu/Eu* = 0.61) suggest anthropogenic influences. REE concentrations in SPM exceed those in Upper Continental Crust (UCC), with Total Dissolved Solids (TDS) ranging from 103 to 510&#xa0;mg/L. Weathering processes involve clay adsorption of LREEs and carbonate complex formation with HREEs. Anthropogenic sources include medical wastewater and industrial discharges, contributing to urban Gd anomalies and La/Ce enrichments. Implications confirm Himalayan felsic sources under intense subtropical weathering, with emerging REE contamination necessitating urgent monitoring. Conclusions emphasize the need for integrated frameworks to address ecological risks associated with REE dynamics in these river systems.</p>

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Provenance, Weathering, and Anthropogenic Inputs: A Tripartite Control on REE Signatures in Indus River Suspended Sediments

  • 期刊论文

  • 发表日期：

    2025年12月8日

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  • Akhtar Rehman,
  • Maliha Ghani,
  • Fu Benchen,
  • Shafee Ahmad,
  • Muhammad Hamza,
  • Asad Aziz,
  • Muhammad Sibt e Ali,
  • Nazir Ur Rehman,
  • Naveed Rehman

摘要

This study examines the distribution of rare earth elements (REEs) in suspended particulate matter (SPM) collected from 50 sites along the Indus River Basin to distinguish between natural and anthropogenic controls on sediment geochemistry. Natural processes dominate bulk REE fluxes, with Himalayan granitic and metamorphic rocks contributing elevated ΣREE concentrations averaging 172.1 mg/kg, exceeding Upper Continental Crust values. Weathering signals are expressed through high Chemical Index of Alteration (CIA) values (87.5–89.9), light REE depletion downstream ((La/Yb)ₙ = 0.33–1.34) via clay adsorption, and heavy REE mobilization through carbonate complexation. In contrast, anthropogenic impacts are marked by strong gadolinium anomalies (δGd > 1.6) associated with medical wastewater and La/Ce enrichment linked to industrial discharges, overprinted on a persistent negative europium anomaly (Eu/Eu* ≈ 0.61) from felsic bedrock. Together, these findings demonstrate that Indus River REE dynamics are shaped by a dual control: Himalayan erosion governs sediment provenance, while unregulated urban inputs introduce emerging contamination risks, underscoring the need for monitoring frameworks in South Asian River systems.

Graphical Abstract

This graphical abstract summarizes a study on rare earth element (REE) dynamics, focusing on sediment sources, weathering processes, anthropogenic contamination, and ecological risks. The background problem highlights the need to distinguish between natural weathering and human- induced pollution, especially during monsoon seasons. The methods section describes the analysis of 50 suspended particulate matter (SPM) samples using PAAS-normalized patterns, chemical indices, geochemical signatures, and pH conditions, comparing urban and rural areas. Key findings reveal average total REE concentrations of 172.1 mg/kg, with light REEs (LREEs) dominating and heavy REEs (HREEs) depleted. Chemical Index of Alteration (CIA) values range from 87.5 to 89.9, indicating significant weathering. Gd anomalies (δGd >1.6) and Eu anomalies (Eu/Eu* = 0.61) suggest anthropogenic influences. REE concentrations in SPM exceed those in Upper Continental Crust (UCC), with Total Dissolved Solids (TDS) ranging from 103 to 510 mg/L. Weathering processes involve clay adsorption of LREEs and carbonate complex formation with HREEs. Anthropogenic sources include medical wastewater and industrial discharges, contributing to urban Gd anomalies and La/Ce enrichments. Implications confirm Himalayan felsic sources under intense subtropical weathering, with emerging REE contamination necessitating urgent monitoring. Conclusions emphasize the need for integrated frameworks to address ecological risks associated with REE dynamics in these river systems.