Pollutant sources in an arsenic-affected multilayer aquifer in the Po Plain of Italy: Implications for drinking-water supply

摘要: Abstract In aquifers 160 to 260 m deep that used for public water-supply in an area ~ 150 km2 around the town of Cremona, Po Plain Northern Italy, concentrations arsenic (As) are increasing with time some wells. The increase is due drawdown As-polluted groundwater (As ≤ 144 μg/L) from overlying at depths 65 150 m response large-scale abstraction supply. As threatens drinking-water quality locally, and by inference does so across entire Plain, where natural As-pollution > 10 μg/L) a basin-wide problem. Using new legacy data Cl/Br, δ18O/δ2H other hydrochemical parameters 32 wells, 9 surface waters, sewage outfall rainwater, we show aquifer (160–260 m below ground level), which tapped widely water-supply, partly recharged seepage (65–150 m level). Groundwater appears free anthropogenic influences typically  10 μg/L). Outfalls sewage-treatment plants black water septic tanks firstly affect then locally infiltrate shallow under high channel-stages. Wastewater permeating carries it NO3 SO4 suppress reduction iron oxyhydroxides sediments release groundwater.