Longterm dynamics of prior pollutants concentration and total level of chemical contamination in the coastal areas at Vladivostok (Peter the Great Bay, Japan Sea)

Abstract

Contents of hydrocarbons, phenols, DDT and its metabolites, Cu, Pb, DDD/DDE and DDD+DDE/DDT ratios, and total level of chemical contamination (TPF index) in bottom sediments are traced for 16 stations in the coastal areas at Vladivostok in 1982−2018. The content of DDT, Cu and Pb, DDD/DDE ratio, and TPF had increased until the early 1990s and then had some stabilizing; the concentration of hydrocarbons was high and relatively stable until the middle 1990s, then dropped sharply and had new gradual growth since the early 2000s; the values of phenols concentration and (DDD+DDE)/DDT ratio were low until the middle 1990s — early 2000s and then increased swiftly. The reason for the pollution decreasing was possibly the lowering of economical activity in the 1990s. All contaminants and indices are very variable that’s why there is difficult to identify the processes responsible for their long-term dynamics. Conception of assimilatory capacity is applied to the bottom sediments. Self-purification of the sediments and maintenance of their contaminants balance is likely provided by microorganisms activity coupled with accumulation of contaminants by macrobenthos in the Amur Bay, by the microorganisms activity coupled with high rates of sediment accumulation in the Golden Horn Bay, and by the microorganisms activity and hydrodynamic sorting of sediments that washes the fine fractions enriched by contaminants in the open areas of the Ussuri Bay. Modern increasing of phenols concentration reflects probably a tendency to eutrophication. Situation of negative impact of chemical contamination (exceeding of ERLq threshold value) is detected for the last 35 years in the Golden Horn Bay but this period is much shorter in other areas with the minimal time in the open Ussuri Bay. The time of negative impact is strongly correlated with the total level of chemical contamination of sediments.