Supplementary file 1_Pollution characteristics, receptor model-based source apportionment, and health risk of potentially toxic elements in the Godavari River, India.docx

The Godavari River, India’s second-longest river, faces rising contamination from Potentially Toxic Elements (PTEs) due to urbanisation, industrialisation, and intensive agriculture, posing risks to ecosystem health and public safety. This study quantified nine PTEs (Cr, Co, Ni, Cu, Zn, As, Cd, Hg, Pb) in water and sediment to assess pollution levels, identify sources, and evaluate ecological and human health risks. Samples (n = 17) were collected during lean season along the 1,465 km mainstem, analysed using ICP-MS, and subjected to receptor modelling (PMF, APCS-MLR) and risk assessment. In water (µg/L), Zn (7.20 ± 5.8) and Cr (6.58 ± 2.11) dominated; in sediments (mg/kg), Cr (16.58 ± 7.37) and Cu (14.95 ± 6.56) were predominant. Along the Maharashtra urban-industrial corridor, Cd exceeded WHO limits by 2.3-fold in downstream water, while upstream sediment Cr and Ni exceeded Threshold Effect Levels by 1.1- and 1.4-fold. Present sediment concentrations were lower than historical records, suggesting persistent source types though direct comparison is constrained by methodological differences between studies. PMF (Q/Qexp = 0.81; mean r2 = 0.87) demonstrated superior resolution over APCS-MLR, identifying three sources: lithogenic/mining (Cr-Ni-Co; ∼41%), urban/traffic (Cu-Zn-Pb; ∼41%), and agricultural/geogenic (As-dominated; ∼18%). Risk Quotient indicated moderate ecological risk from Ni (RQm = 0.10) and Zn (RQm = 0.24), while Potential Ecological Risk Index values (2.16–38.22) indicated low sediment risk. Screening-level human health assessment indicated Hazard Index below 1.0; however, children exhibited 3.4-fold higher exposure than adults, with Pb, As, and Cr as primary risk drivers representing all three source categories. This study provides the first integrated source-risk assessment for the Godavari River, identifying priority contaminants, intervention zones, and source-specific mitigation targets.