Changes over time in persistent organic pollutants (POP) concentrations in soils in lower Dniester region, Republic of Moldova
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504.53.054:556.531(478-13) (1)
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CULIGHIN, Elena. Changes over time in persistent organic pollutants (POP) concentrations in soils in lower Dniester region, Republic of Moldova . In: Ecological and environmental chemistry : - 2022, Ed. 7, 3-4 martie 2022, Chișinău. Chisinau: Centrul Editorial-Poligrafic al USM, 2022, Ediția 7, Vol.1, pp. 182-183. ISBN 978-9975-159-07-4.. 10.19261/eec.2022.v1
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Ecological and environmental chemistry
Ediția 7, Vol.1, 2022
Conferința "Ecological and environmental chemistry 2022"
7, Chișinău, Moldova, 3-4 martie 2022

Changes over time in persistent organic pollutants (POP) concentrations in soils in lower Dniester region, Republic of Moldova

CZU: 504.53.054:556.531(478-13)

Pag. 182-183

Culighin Elena
 
Institute of Chemistry
 
Proiecte:
 
Disponibil în IBN: 17 martie 2022


Rezumat

Dniester hydrographic district covers approximately 60% of the Republic of Moldova territory ensuring 63% of the annual water quantity and it encompass ~80% of country‘s underground waters. Soils, more precisely, agricultural lands and the practices applied on them serve as a source of point pollution of groundwater and surface waters, in addition to other sources such as the household sector, the food industry, the agricultural sector, the energy sector and other sources of continuous pollution. Moldova is considered an agrarian country whose main resource and wealth are fertile soils. Substances from the group of persistent organic pollutants (POPs) pose a particular danger to the health of the population and to environmental factors. During the seventies of the last century, organochlorine compounds from this group were widely used in agriculture as insecticides and fungicides. Considering that the impact of the environment on the human body is inevitable, it is necessary to monitor the content of organic pollutants in soils in the Republic of Moldova, aimed at reducing the risk of toxic substances by reducing their impact on living organisms. The study aims to identify the changes over time of POPs concentrations in the soils from 16 sites along the Dniester River. Results of the research done in 2010 were compared with the investigations in 2020 of the same sites. Random sampling was used, and complex samples were collected from the dept of 0-10 cm. Gas Chromatography coupled with mass spectrometry was used for POPs identification and quantification according to EPA and ISO methods. The degradation status of DDTs was assessed using the ratio (DDE + DDD)/DDT, which ranged from 0.052 to 0.472 in 2010 and from 0.045 to 8.78 in 2019. These reports show old sources of DDT pollution, indicating that DDT residues were significantly transformed into their degradation products in these areas. The distribution of HCH isomers varied between soil samples. This may be associated with the isomerization of HCH during the soil transformation process, as well as with differences in physicochemical properties and degradation rates.The value of the ratio of isomers β (α + γ) was used for the identification of aged sources of pollution. In the present study, in 53% of the results from 2010 the ratio of isomers β (α + γ) was > 1 and for 69% of the analysed soils in 2019. Thus, we can conclude that in these regions the source of pollution is the past use of technical HCH (the share of samples in which the ratio of β (α + γ)> 1 isomers is greater than 50%). The value of the α-HCH γ-HCH ratio varied from 0.12 to 7.8 (2010) and from 0.0 to 8.3 (2019), indicating that there is a slight increase in the HCH transformation under natural conditions and that both lindane and technical HCH were sources of HCH contamination. In conclusion, the study has shown that the contamination level has not changed significantly over time, subsequently there is a need for the remediation of the studied sites.