Distribution of metals in suspended matter and bottom sediments in the estuary of the Northern Dwina

A complex geochemical study of the estuary of the Severnaya Dvina River was performed using the results of three oceanographical expeditions in the White Sea in 1995-1997 under the INTAS 94-391 project. The character of the distribution of water temperature and salinity, the concentration of suspended matter, and the contents of Al, Fe, Mn, Co, Cu, Ni, Cr, Ph, Zn, and organic carbon in the suspended matter and bottom sediments of the estuary is shown. The dominant role of the riverine runoff in the supply of the elements studied to the estuary of the Severnaya Dvina River was revealed. It was found that, within the composition of the estuarine bottom sediments, metals existed mainly in mineral forms amounting to 60-99% of their total content. Two zones of accumulation of the bulk of the metals studied in the bottom sediments were identified in the estuary. The zones mentioned may be treated as local geochemical barriers within the river-sea boundary zone. The key factor determining the distribution of metals in the bottom sediments was the grain-size composition of the latter. The analysis of the data on the heavy metal contents in the bottom sediments and zoobenthos of the estuary of the Severnaya Dvina River revealed no anthropogenic pollution of the area studied [KEYWORDS: Trace-metals, samples]