Ecological Risks Assessment Arising from the Atmospheric Deposition of Heavy Metals in the River Indus Near Kotri Barrage, Sindh, Pakistan

This study aims to assess ecological risks from heavy metal atmospheric deposition in the Indus River at Kotri Barrage, Sindh, Pakistan. Monitoring occurred at four locations, yielding 40 air samples analyzed for heavy metals via Triple Quadrupole Inductively Coupled Plasma Mass Spectrometry (TQ-ICP-MS). Pollution indicators, including Contaminant Factor (CF), Degree of Contamination (CD), Geo-accumulation Index (Igeo), Enrichment Factor (EF), Pollution Load Index (PLI), Potential Ecological Risk Index (PERI), and Nemerow Integrated Pollution Index (NIPI), quantified contaminant levels. Air monitoring revealed PM2.5 concentrations exceeding regulatory guidelines at all four sites. Heavy metal mean concentrations ranked as follows: Fe > Cr > Pb > Mn > As > Cu > Ni > Cd > Mo > Co, and deposition fluxes followed this order: Fe > Pb > Cr > Mn > As > Cu > Ni > Cd > Mo > Co. Pollution indices indicated moderate to extreme pollution for Fe, Cr, Cd at all sites, and Pb at site D. Emissions from a nearby coal-fired power plant and vehicular sources were identified as primary contributors to high heavy metal deposition. The Ecological Risk Index ranged from 150 to 600, signifying substantial ecological risk linked to Cd. These findings offer crucial insights for governmental agencies and policymakers to address pollution issues arising from heavy metal atmospheric deposition in the Indus River near Kotri Barrage.