Organochlorine compounds in flounders of genus Hippoglossoides Gottsche, 1835 from the Far Eastern seas of Russia

Abstract

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) are global superecotoxicants belonging to a group of persistent organic pollutants (POPs). Fish and seafood are an important source of high-grade protein and polyunsaturated fatty acids, especially for residents of coastal areas. Up to 90 % of all pollutants enter the human body through food. Final depot of POPs in environment is marine ecosystems; therefore, POPs can accumulate in various objects of marine fisheries. The paper presents information on the concentrations of OCPs [HCH isomers (α-, β-, γ-), as well as DDT and its metabolites (DDD and DDE)], and polychlorinated biphenyls (PCBs) in muscles of flounders of genus Hippoglossoides Gottsche, 1835 from the Far Eastern seas of Russia (the Sea of Okhotsk, the Tatar Strait, and the Sea of Japan). Lipids were extracted from fish tissue samples with a mixture of hexane and acetone, followed by destruction of fatty components by concentrated sulfuric acid. OCPs and PCBs were separated by column chromatography with polar and non-polar solvents. Xenobiotics were quantified by gas chromatography – mass spectrometry. To assess quality of this methodology, a standard addition method was used. The average reproducibility of analyte concentrations varied 94.6 to 103.7 %, and it indicates reliability of the data obtained as well as effectiveness of methods applied. Average concentrations of ∑DDT, ∑HCH, ∑OCP (∑DDT + ∑HCH), and ∑PCB were: (62 ± 89), (50 ± 52), (100 ± 125), and (92 ± 45) ng·g⁻¹ of lipids in the samples from the eastern part of the Sea of Okhotsk; (20 ± 17), (36 ± 37), (54 ± 41), and (99 ± 43) ng·g⁻¹ of lipids from the southern part of the Sea of Okhotsk; (40 ± 29), (62 ± 36), (102 ± 50), and (1616 ± 1177) ng·g⁻¹ of lipids from the Sea of Japan, respectively. In the samples from the Tatar Strait, the average levels of ∑HCH, ∑OCP, and ∑PCB were (221 ± 182), (224 ± 180), and (455 ± 317) ng·g⁻¹ of lipids, respectively. DDT was detected in three samples. In the flounders from the eastern part of the Sea of Okhotsk, the highest concentrations of DDT and average concentrations of HCH were recorded, which may be due to the location of a “repository” of pesticides on the Kamchatka Peninsula, where OCPs are buried. The entrance of PCBs into the waters of the southern part of the Sea of Okhotsk can be associated both with intensive shipping and effluents from landfills that carry residual amounts of PCBs into the ecosystem. The southern part of the Sea of Okhotsk is the cleanest of the areas studied and is characterized by the lowest content of DDT, HCH, and PCB in organisms. DDT was practically absent in the flounders from the Nevelsky Bay (the Tatar Strait). At the same time, they showed the highest level of HCH, represented only by β-isomer, which indicates a prolonged circulation of the toxicant in the ecosystem. According to the decree of the Government of the Sakhalin Region, on the territory of Sakhalin there are landfills for out-of-use or banned pesticides; storage of them was performed (at the time of the decree entering the force) with violations that could lead to serious environmental pollution. Most likely, they became the source of pollution of the Tatar Strait. Another source of HCH pollution is currents that carry the waters of the Sea of Japan through the Nevelsky Bay into the Sea of Okhotsk. High levels of PCBs in the waters of the bay may result from intensive shipping and possible impact of household waste dumps on the Sakhalin Island. Flounders from the Sea of Japan are characterized by the highest POPs pollution. The entrance of OCPs into the sea may be due to surface runoffs, river flows, storage leaks of pesticides banned for use, and atmospheric transport from Asian countries where the use of some OCPs is still permitted. The determined levels of PCBs are an order of magnitude higher than those in the flounders from the Sea of Okhotsk and the Tatar Strait, which may be due to active shipping in Sea of Japan waters, influence of operating oil and coal ports in the city of Nakhodka, as well as local pollution of the coastal zone (so called wild beaches). Thus, we have studied the accumulation of organochlorine pesticides (HCH and DDT) and polychlorinated biphenyls in the muscles of flounders from the Far Eastern seas of Russia. With the existing global background of POPs formed on the planet, the levels of these compounds in the flounders of the southern part of the Sea of Okhotsk can be taken as background ones. The Sea of Japan is subject to the greatest anthropogenic pressure, and PCB concentrations are significantly higher in this area than in the Far Eastern seas of Russia and in the compared regions of the world as a whole.

Keywords: DDT, HCH, PCB, flounder, genus Hippoglossoides, Far Eastern seas of Russia