DDX Profiles in Agricultural Fields Used for Cucurbit Production in Sakarya, Turkey

DDT (2,2-bis(chlorophenyl)-1,1,1- trichloroethane) and its metabolites DDD (2,2-bis(chlorophenyl)-1,1 -dichloroethane) and DDE (2,2-bis(chloraphenyl)-1,1 dichloroethylene) have half-lives in soil measured in years or decades and are classified as Persistent Organic Pollutants (POPs). In this study, p,p-DDT, p,p-DDD, and p,p-DDE residues were investigated in select agricultural fields of Sakarya Province, Turkey, where Cucurbitaceae have been grown for many years. Total squash and pumpkin production in Sakarya is approximately 3% of total cucurbit production of Turkey but little is known about the concentrations of DDT, DDD, and DDE in these agricultural soils. Thirty-three soil samples were collected from agricultural fields in different counties of Sakarya. p,p-DDT was detected in all soil samples, with concentrations ranging from 0.23ng/g to 123ng/g soil (dry weight). The concentrations of p,p-DDT metabolites ranged from nondetectable (<0.06ng/g) to 120ng/g for p,p-DDD and from nondetectable (<0.03ng/g) to 294ng/g for p,p-DDE. The highest total DDX (sum of p,p-DDT, p,p-DDD, and p,p-DDE) concentrations among the soil samples was 428ng/g in a sample collected from Karasu County. Further research in this field was conducted to measure p,p-DDT, p,p-DDE, and p,p-DDD concentrations at multiple locations as a function of soil depth. p,p-DDT concentrations were measured from 52ng/g to 1935ng/g at 060cm depth. The highest DDX concentration was observed at a location where plants have been actively grown since 1987. The lowest DDX concentrations were observed where crops have not been grown since 1987. Our data proved that soil DDX levels at the field gradually increased as a function of how extensively the field has been used for cucurbits production. However, it is not certain whether the application of p,p-DDT was terminated or if there may still be illegal usage in agricultural soils.