Residues of organochlorine pesticides in irrigated sierozem-meadow soils around buried chemicals stock

The concentration and distribution of organochlorine pesticides (OCPs) were studied in sierozem-meadow soils around a buried obsolete chemicals stock in Mirzaabad district of Syrdarya region of Uzbekistan. 23 soil samples were collected from the topsoil (0-30 cm of soil depth) and 15 samples were collected from three soil profiles (down to 125 cm of soil depth) located in nearby vicinity of the stock. They were extracted using an automated Soxhlet extractor and analyses were done by gas chromatography-mass spectrometry. The detected OCPs were DDTs, HCHs, aldrin, dieldrin, endrin, chlorpyrifos, and endosulfans. The concentration of HCH was detected only as α-HCH in the range of 0-3.159 μg/kg. Only two isomers of DDT: p,p'-DDE and p,p'-DDD were found to be dominant, with the range of their values of 0.068-4.941 and 0-13.63 μg/kg, respectively. The concentrations of aldrin, dieldrin, endrin and chlorpyrifos in the samples collected around the source were in the range of 0-0.504, 0-1.117, 2.414-20.87 μg/kg and 0-3.819 μg/kg. β-endosulfan varied from a non-detectable amount to 74.56 μg/kg. According to results, the sum of DDTs was observed to be higher in the upper horizons, especially at depths of 0-10 and 10-50 cm, with the values 543.15 and 212.22 μg/kg, respectively, which can be a cause of concern. Due to their ability to migrate in the environment, accumulate in the food chain and be harmful to human health, monitoring the level of residues of organochlorine pesticides in soil is of vital importance.