Temporal and spatial variations of organochlorine pesticides in the suspended particulate matter from Lake Chaohu, China

• DDXs were the predominant component of OCPs.
• p,p′-DDT was dominant in the DDXs, suggesting that it is still used in the catchment.
• Very similar compositions of OCPs, DDXs and HCHs in the SPM and air particulate matter.
• DDT and DDX residues pose some adverse effects on the aquatic organisms.

The residual levels of organochlorine pesticides (OCPs) in the suspended particulate matter (SPM) from Lake Chaohu were measured. The temporal–spatial distributions, potential sources, water-SPM partition and ecological risks of OCPs were studied. Total 17 OCP components were detected with total contents of 172.68 ± 434.88 ng/g. The total DDT parent compounds and their metabolic products (DDXs), with a total average content of 138.76 ± 407.27 ng/g, was the predominant components. The compositions of OCPs, DDXs and HCHs in the SPM were very similar to those in the air particulate, especially in spring and summer. Temporally, the highest residual levels of DDXs, HCHs and OCPs were found in August, which is very similar to temporal distribution trends in the water. Spatially, the highest residual levels of DDXs and OCPs in the SPM were found in the eastern lake area, followed by the western and the central lake areas. There were significant positive relationships between the contents of OCPs and DDXs in the SPM and those in the water. All water-SPM partition coefficient (Kd) values of OCPs were higher than 1, except those for p,p′-DDE, p,p′-DDT, HCB and γ-chlordane. The ratios of o,p′-/p,p′-DDT and DDT/(DDD + DDE) for all detectable SPM samples were less and greater than 1.00, respectively, which might indicate the new inputs of industrial DDTs. The ratios of α-/γ-HCH and β-/(α+γ)-HCH were less than 4 and 0.5, respectively, for the most of detectable SPM samples, which might demonstrate the recent inputs of lindane. The DDT and DDX residues in some SPM samples exceeded their corresponding probable effect concentrations, which indicated their adverse effects on the aquatic organisms.