Geochemistry of the suspended sediment in the estuaries of the Mandovi and

Abstract Geochemistry of the suspended particulate matter (SPM) collected during the monsoon was determined to identify the sources of SPM and to understand the physico-chemical processes in the Mandovi and Zuari River estuaries. The concentrations of SPM decrease seaward in both estuaries, but are relatively high at bay stations. Kaolinite is the most dominant clay mineral in the upstream of both rivers. Smectite increases seaward in both estuaries and is abundant in the bay. Upstream stations of Mandovi, where ore deposits are stored on the shore, exhibit high Fe, Mn, ΣREE and, middle REE- and heavy REE-enriched REE patterns. Channel stations of both estuaries exhibit middle REE- and light REE-enriched patterns, which gradually changed seaward to middle REE- and heavy REE enriched patterns. Canal stations exhibit highest concentrations of major and trace metals. High metal/Al ratios occur at stations in the upstream of Zuari and at the confluence of canal in the Mandovi estuary. Enrichment factors of metals indicate that Mn is significantly polluted while other metals are moderately polluted. The δ13C and δ15N of organic matter indicate that the terrigenous organic matter at the upstream is diluted seaward by marine organic matter. Organic matter at bay stations is largely marine and altered-type. The compositions of SPM are controlled by the particulates from ore dust, geology of the drainage basins and physico-chemical processes in the estuaries. Particulate