The heavy metal partitioning in the particle flux of the subarctic White Sea (Northwestern Russia)

Abstract

This research addresses the environmental factors that affect the heavy metal accumulation and partition in the particle fluxes of the White Sea. The particulate material was collected between 2006 and 2014 with sediment traps at 9 stations from depths of 25–220 m to determine its geochemical composition. Contribution of terrigenous and hydrogenous processes was estimated based on the sequential leaching procedure which allowed distinguishing the geochemical fractions: exchangeable, Fe–Mn authigenic oxyhydroxides; organic matter/sulfides; residual (fixed in clastic minerals). Terrigenous processes were dominated in the accumulation of Al, Fe, Cr, Ni, Co, and Mo (60–90% of the total content), while the accumulation of Mn, Cu, Cd, and Pb was primarily associated with hydrogenic processes (authigenic oxyhydroxides' formation, sorption processes, and organic compounds). These two groups of chemical elements demonstrated a different distribution pattern in particle fluxes with water depth. Growth of the total particle fluxes with the water depth took place as a rule against the background of authigenic mineral formation (Fe–Mn oxyhydroxides), a slight increase in the lithogenic components, and the slow destruction of organic matter. In areas, where the vertical particle flux dominates, increased content of elements related to the Fe–Mn oxyhydroxides and bound to organic matter, were detected. The influence of anthropogenic sources based on the criteria of contamination level (EF x and I geo) was found only for Cd in some samples. An insignificant anthropogenic contribution is also possible for Cu and Ni, comparing with the background concentrations.