Mercury in White Sea Bottom Sediments: Distribution, Sources, and Deposition Chronology

Resumo

For the first time, vertical and lateral distribution patterns of mercury in White Sea bottom sediments have been determined. An abrupt change in the nature of mercury concentrations has been revealed, with a general tendency to decrease with depth. Natural variations in mercury concentrations within 0.01–0.03 µg/g dry weight (dw) have been established. An upper value of 0.03 µg/g dw is taken for the natural background content of the element. The distribution of mercury concentrations in the sequence of bottom sediments is influenced by both anthropogenic and natural factors and processes. With distance from the marine–estuary boundary of the Northern Dvina River, the river’s role in supplying mercury to the White Sea is reduced, and global and regional atmospheric mass transfer take over. The mercury content is used as an indicator of landslide processes in Kandalaksha Gulf of the White Sea. The accumulation chronology of mercury in White Sea sediments is studied, and the proportion of anthropogenic mercury is calculated.