Mercury geochemistry of marine sediments from the eastern Laptev Sea: The spatial distribution, levels, and contamination assessment.

Twenty-seven sediment samples from the eastern Laptev Sea were analyzed for mercury and total organic carbon as well as grain-size distribution. The average total mercury (THg) concentrations in sediments are 29 ± 14 µg kg-1. A significant correlation of THg content with total organic carbon and clay and silt fractions was shown. The 210Pb-dated sediment core was used to evaluate the contamination degree and flux of THg in sediments from the eastern Laptev Sea. The average sedimentation rate for the all dated intervals was 0.17 cm/year. The THg flux increased from 20 to 28 µg/m2/year in the period of 1892-1950 to 53-59 µg/m2/year in the modern period of 2011-2015. According to various indices, the ecological risk from THg in studied sediment was low.

Distribution and assessment of trace metals in modern bottom sediments in the southwestern Chukchi Sea.

Sediment samples from 53 stations of the southwestern Chukchi sea were investigated to the spatial distributions and assess the state of trace metals contamination using ecological indices. The mean concentrations (mg kg-1) in sediments were: Cr (70.5), Ni (41.0), Cu (16.5), Zn (82.7), As (15.90), Cd (0.27), Pb (15.96), Hg (32.0 µg kg-1). The spatial distribution pattern of trace metals was similar with maximum values in the northern of the Chukchi Sea in the outer shelf sediments, while the high values of Cd were noted at stations located in the southern part of the sea where a strong influence of the Pacific waters penetrating through the Bering Strait. The ecological indices indicated no signs of anthropogenic pollution in the study sediments of the Chukchi Sea. Received data are of value for detecting and tracking future chemical changes in the sediments of the Chukchi sea, particularly in light of environmental changes.