Concentrations of dissolved and particulate heavy metals in waters above the northwestern slope of the Paramushir Island (Sea of Okhotsk)

Distributions of Mn, Fe, Cu, Cd, Cr, Co and Ni in sea water are investigated (42 samples, dissolved and particulate forms) in the vicinity of the underwater gas vent field on the northwestern slope of the Paramushir Island. While regular background distributions of the elements occur in the shore zone, there is a column of elevated concentrations of particulate matter, particulate Mn, and dissolved Mn, Fe, Cu, Cd, Cr, Co and Ni that coincides with location of the gas plume. This column can be traced as high as 780 m above the bottom. High metal concentrations in water of the plume are attributable to physico-chemical concentration at the phase interface; the source of elevated mineral concentrations is obviously flux of dissolved minerals from interstitial waters, which extends to considerable distances in vertical direction.

(Table 2) Contents of trace elements in plankton from the White Sea

With a view to more complete understanding of the role of phyto- and zooplankton in biogeochemical cycles, spatial distributions of Fe, Mn, Co, Ni, Cr, Cu, Cd, Pb, Zn, As, Hg, and Corg in the White Sea seston (21 samples) collected in August 2004 during Cruise 64 of R/V ''Professor Shtokman'' were studied. It was shown that the elements in study are accumulated in plankton with enrichment factors from 10**2 for Hg to 10**5 for Fe, as compared to seawater. Spatial distribution of trace elements is determined by sources of their supply and correlates with distribution of primary production and biomass of zooplankton. Increased values of trace element contents (excluding As) are characteristic of the Dvina Bay, whereas the highest As concentrations were found in the Kandalaksha Bay.