Assessment of soil and soil trophic chains contamination by persistent organic pollutants

Abstract

Ukraine ratified the Stockholm Convention on Persistent Organic Pollutants (POPs) in 2001, and is now a party to this Convention. First, 12 POPs were introduced into the annexes to the Convention, nine of which are pesticides, and today the list includes 21 highly hazardous chemicals, posing a global threat to human health and the environment. Since POPs accumulate precisely in the fatty tissues of living organisms, people, as representatives of the upper stages of the food chain, are most vulnerable to the effects of POPs. The purpose of the research was to provide scientific substantiation of the agroecological assessment of soil contamination and components of the trophic chains by persistent organic pollutants. The research was conducted based on the Department of Ecotoxicology of the Institute of Agroecology and Nature Management of the National Academy of Sciences of Ukraine. Field experiments were carried out during 2012-2014 in the territories around non-operational warehouses of pesticides and on agricultural land located around the non-operational warehouses of poison chemicals located within the farms of Intergroinvest LLC Stavishchensky District and TzdV Shamraievsky Sugar Plant in the Skvirsky District of the Kyiv Oblast. Warehouses are in unsatisfactory condition, the buildings are partially destroyed, they are not closed, walls and ceilings are sometimes lacking; only some remnants of buildings remain in some warehouses, which indicates that the precipitates are freely entering the middle of buildings, which facilitates the migration of toxic compounds into objects the environment. The soil of the sanitary-protective zones of the poisons of Stavishchensky and Skvirsky districts contains significant amounts (22 - 145 MAC) of the remains of stable HOPs and serves as a powerful source of income for the following units of the trophic chains. To establish a large migration of organochlorine pesticides from the source of pollution, samples of soil, selected at 1, 5, 15, 25, 50, and 100 m from the composition of pesticides, were analyzed. All soil samples contain residual amounts of DDT that significantly exceed the established hygiene standards. Thus, the content of the sum of isomers and DDT metabolites in soil samples taken in the northern direction from the composition is 2.18 - 30.38 mg / kg of soil, which exceeds the MPC by 21.8 - 303.8 times. In general, there is a tendency for a gradual reduction of contamination by organochlorine pesticide residues as far as the separation from the composition, however, even at 100 m the content of the sum of isomers and metabolites of DDT exceeds the established hygienic norms, which requires additional inspections of the territory to establish limits of the contaminated zone. 2,4'-DDT was identified in a sample of soil, selected directly near the building of the warehouse (at 1 m), and significant samples (3-54 MAC) of 4,4'-DDT were found in all samples, which is a source, non-metabolized pesticide substance. High concentrations in the soil of 4,4'-DDT indicate the potential for pollution of the territory by persistent organochlorine pesticides and, consequently, toxic effects on the soil microflora, which causes inhibition of the microbiological decay of xenobiotics. The main part (about 62%) of the total amount of isomers and metabolites of DDT is the most stable metabolite of 4,4'-DDE. Its content in soil samples ranges from 1.32 mg / kg of soil at 100 m from the composition to 18.42 mg / kg of soil at 25 m from the composition of the pesticides. A similar situation regarding soil contamination with organochlorine pesticides is observed in the southern direction. Polychlorobiphenyls are compounds that are extremely stable in the environment. PCBs are among the globally distributed pollutants because of their high persistence and high utilization rates. In a layer of soil (0-20 cm), PCB was found at a concentration of 0.04 mg / kg at 50 m from the composition, to 0.37 mg / kg at 5 m from the composition. In the samples of the subterranean (20-40 cm) soil layer, the minimum values (0,01 mg / kg) were recorded at 50 m from the composition, the maximum value (0,10 mg / kg) at 5 m. The amounts of PCBs found indicate application in the past pesticides, which included polychlorinated biphenyls. Thus, the soils of the sanitary-protective zones of the composition of poison chemicals in the Stavishchensky district have a complex contamination with dangerous persistent organic pollutants (organochlorine pesticides and polychlorinated biphenyls).