Organic matter in the ecosystem of Vladimir Bay (Sea of Japan): food resource and environmental risk factor
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Abstract
The article is devoted to the study of natural factors of toxicants accumulation in the components of the marine ecosystems environment, the assessment of environmental risk and human health risk. The study of the organic matter content in the aquatic environment and bottom sediments is extremely important for understanding the accumulation process in relation to toxic substances and elements entering the water area, for identifying negative processes and understanding potential environmental risks in the nature management. The aim of our investigation is the analysis of organic matter content in the marine environment of the Vladimir Bay and its impact on the accumulation of toxic elements and possible environmental risk. This scientific work was carried out using chemical-analytical, microbiological and hydrobiological methods, includes mathematical and cartographic data processing and calculation of pollution accumulation factors and human health risk.
The analysis of samples of seawater, bottom sediments and macrobenthos taken from the Vladimir Bay in 2012 and 2014 was carried out. The determined by us chemical-ecological and microbiological parameters of the bay waters make it possible to estimate the processes of organic matter accumulation in the aquatic environment and bottom sediments and to establish the trophic status of the ecosystem in the summer period. The dominant species and groups of macrobenthos have been identified. The indices of the benthic population abundance which indicating to high levels of biomass, have been determined. The number of metal-resistant groups of bacteria in surface waters was estimated. The heavy metals content in bottom sediments and its spatial distribution has been determined. The concentrations of heavy metals in the sea urchins gonads have been quantified. The results of the microbiological assessment have been correlated with the chemical scale of exceeding the maximum allowable concentracion. The significant pollution of the Bay waters (more than 3 units of MAC) by Cd is revealed. An excess of background concentrations and bulk earth values of several heavy metals in bottom sediments was found. The correlation between the concentrations of organic matter in bottom sediments and the content of heavy metals there is verified. A significant correlation in relation to Zn concentrations in the sediments and sea urchins gonads was found. The accumulation coefficient Cf (which characterizes the bottom sediments pollution of the bay by Zn as “high”, by Cd and Cu as “very high”) and the total coefficient Cd (which indicates that bottom sediments have an average degree of pollution), have been found. The environmental risk indices have been calculated. The bottom sediments are determined as “moderately toxic” according to the SQG-Q index. The concentrations of Cd and Pb in the gonads of sea urchins from the Vladimir Bay does not exceed the permissible values of the Customs Union standarts. However, the index of increasing lifetime cancer risk ILCR predicts the existence of oncological diseases risk related with gonads consuming.