Behaviour and distribution patterns of particulate metals in estuarine andcoastal surface waters near Mangalore, southwest coast of India

Physico-chemical properties of water (pH, dissolved oxygen, salinity and su spended matter concentrations) and geochemistry (Cu, Pb, Zn, Ni, Co, Mn, Fe , Al, Ca and loss-on-ignition) of suspended particulates have been measured for the first time in the Netravati-Gurpur estuary and the adjacent coasta l environment, southwestern India. The main objective was to understand the influence of physicochemical properties of estuarine and coastal waters on the behaviour, association and dispersal patterns of particulate metals. Suspended particulate matter (SPM) from the estuarine and coastal environme nts have higher Cu, Pb and Zn (by factors of 1.5-2.7) than the Netravati-Gu rpur riverine SPM, indicating enrichment of these metals with increasing sa linity. In contrast, Al, Fe, Mn, Co and Ni contents and the corresponding m etal/Al ratios are marginally lower (by factors of 1.1-1.5) than those for riverine SPM, suggesting not only a decrease of terrigenous influx seaward, but also removal of trace metals from the particulate phase. R-mode factor analysis of the data has shown that detrital particles (with Fe oxide coat ing), clays and Mn-oxide are the major factors that control particulate met al association. Factor score distribution patterns suggest that detrital pa rticles coated with Fe oxide are deposited in the estuary and nearshore reg ion, whereas clays and Mn-oxide seem to be transported further into the coa stal sea. Copper, Pb and Zn show an anomalous behaviour and are negatively loaded on all the three major factors.