Features of mercury geochemistry and the dynamics of its accumulation in bottom sediments of the northwestern Bering Sea over the past 150 years

Abstract

The Bering Sea shelf is a transit zone for water masses moving from the Pacific Ocean to the Arctic Ocean. Mercury geochemistry in bottom sediments of the northwestern Bering Sea shelf has been practically unstudied, whereas the Arctic seas are constantly being explored. Hg concentrations ranged from 6 ppb to 65 ppb in the bottom sediments of the study area. Based on the dating of sediment cores, the background concentration was 34 ppb. The concentration of Hg in fine sediment fractions was 60 ppb, in sandy fractions (>63 μm) varied from 17 to 43 μg ppb. In recent decades, a stable increase of mercury fluxes to bottom sediments has been observed. We used the Hg/TOC ratio as an indicator of mercury input to marine waters from natural terrigenous sources.