Occurrence and spatio-vertical distribution of DDT in soils of abandoned DDT factory area, Amangarh, Pakistan

Abstract

The insecticide dichlorodiphenyltrichloroethane (DDT) was mainly used in Pakistan as pest control in agriculture and for the eradication of malaria. For the DDT production, a factory was established in 1963 in Amangarh, near Nowshera district, Khyber Pakhtunkhwa, Pakistan. In 2001, the Pakistan government banned the usage of DDT, and subsequently, the Amangarh DDT factory also stopped its production. The present study was designed to investigate the occurrence of DDT residues after its closure. Total ∑DDT from soil samples at each depth was extracted by using a standard solvent extraction method. For the characterization of soil physical properties, three-to-five composite soil samples were collected from the site for soil particle size distribution, while soil pH and electrical conductivity were determined in a 1:5 ratio (soil water solution). The mean concentrations of ∑DDT in surface (0–15 cm), subsurface (15–30 cm) and deep horizon (30–45 cm) soil were 125.5, 143.6 and 148.9 mg kg−1, respectively. The concentrations of ∑DDT in 89% of the samples were higher than the probable effects level and threshold effects level. The contamination of ∑DDT was considerably higher than the standard limit (17 mg kg−1). The highest concentration of ∑DDT in the subsurface and deep horizon indicated that the ∑DDT percolated deep into the soil and may also have contaminated the groundwater.