Investigation and evaluation of DDT residues in soils in the suburbs of Beijing, China

Soils in the suburbs of Beijing were investigated and ∑DDTs was detected in the soil samples. The results show that the concentration of ∑DDTs in the soils ranges from 2.7008 to 292.4021 μg/kg with a mean of 41.6227 μg/kg. So the residue levels of DDT and its metabolites were lower. In the samples, p,p′-DDE and p,p′-DDT are the main components of residues. The ratios of p,p′-DDD/p,p′-DDE range from 0 to 1.2730 and are <1 in most samples, indicating that DDE is mainly degenerated from DDT. Thus it may be inferred that the soils in the suburbs of Beijing are mostly in an oxyphile environment. The ratios of (DDE+DDD)/DDT are in a range of 0.1044-1.4688 with a mean of 0.3557. The time for DDT use has been very short. Analysis shows that the risk of DDT residues in soils in the study area is relatively low, but according to the bioaccumulation in terrestrial food webs, the ecological risk of the residues of DDT in soils still exits.