Heavy metals in coastal water systems.A case study from the northwestern Gulf of Thailand

A geochemical survey of the northwestern part of the Thailand Gulf (Inner Gulf) was carried out in order to define concentrationsand distribution patterns of selected heavy metals (V, Cr, Co, Ni, Cu, Zn, and U) in the coastal system and estuarine area of the MaeKlong river. The results indicate the presence of two different sources of heavy metals in the studied environment and allowed us to identifya lithogenic component that significantly influences the composition of coastal waters and suspended particulate matter (SPM).Comparison of the normalized heavy metals concentrations both in the studied samples and in those reported for the Sn–W ores presentin the surrounding areas suggests an important anthropogenic contribution to the chemistry of the seafloor sediments. Vanadium andnickel enrichment factors (EF) calculated for coastal waters indicate that contamination by hydrocarbons discharge took place in theinvestigated area.