Occurrence of Sedimentary Iron and Arsenic Along the Beas River and Implications for Arsenic Enrichment in the Sutlej-Indus River Basin, India

Arsenic (As) contamination of shallow alluvial aquifers in deltas of major rivers (Ganga, Meghna, Brahmaputra, Sutlej, Indus, etc.) in south Asia is the result of the microbially mediated reductive dissolution of iron (Fe)- and As-rich sediments, which are eroded from Himalayan rocks and transported to the deltas by rivers. The reductive dissolution is fueled by labile sedimentary and dissolved organic matter (OM). However, a very limited number of studies investigated the interactions between Fe, As, and DOC or OM in the Himalayan region. We hypothesize that the sediments transported by the Himalayan rivers shall contain elevated concentrations of Fe and As. We collected and analyzed riverbank sediment, river water, and sediment pore water samples from six locations along the Beas River in Himachal Pradesh (India), a major contributor to Sutlej-Indus River delta. Our results showed that the river sediments contained 12 ± 3 g/kg of total Fe, 4 ± 1 mg/kg of As, and 264 ± 122 mg/kg of Mn as measured by XRF. These As concentrations are approximately twice the crustal abundance of As, which is 2 mg/kg. The findings of this study will advance our understanding of how As is mobilized from the source to the delta.