Concentrations and sources of persistent organochlorine residues in the sediments and soils from an industrially impacted area in Anhui, China

Abstract

In this study, a typical site that had been contaminated by the chemical industry in the past was selected for investigation. To reveal the pollution status, 18 organochlorine pesticides (OCPs) and seven polychlorinated biphenyls (PCBs) in the surface soil and sediment samples were analysed by gas chromatography-mass spectrometry (GC-MS). The levels of the persistent organochlorine residues in the sediment ranged from 44.59–143.29 ng/g, whereas they were 13.94–97.91 ng/g in the soil. A principal component analysis identified that PCBs and dichlorodiphenyltrichloroethanes (DDTs) were the primary sources of the organochlorine residues in the study area. The p,p'-DDT/(p,p'-DDE + p,p'-DDD) values were all below 1, which indicated that the historical inputs of the technical DDT and dicofol were the major sources of DDTs rather than recent inputs. The composition diversity of the hexachlorocyclohexane (HCH) isomers showed that the main sources in the soil were the past use of pesticides, whereas the sediment sources might be due to the historical use of technical HCHs and recent lindane inputs. The ecological risk assessment showed that γ-HCH could pose the highest risks for benthic organisms, followed by DDTs and heptachlor epoxide. These compounds are known to bio-accumulate in fatty tissues. Therefore, routine monitoring of the persistent organochlorine residues in the area is needed and the health risks to local residents should be assessed.

Occurrences, Possible Sources, and Risk Impacts of Organochlorine Pesticides in Soil of Changchun Central Urban Area, Northeast China

“…After lindane-which was historically used for agricultural pests and diseases, entered the soil-it was affected by the expansion of the central urban area of Changchun, resulting in the presence of historical sources of lindane in the residual OCPs in the soil of the central urban area. This was similar to the residual form of HCHs in the soil of the Anhui industrial zone [38].…”

Review of scientific literature on available methods of assessing organochlorine pesticides in the environment

“…The LODs are measures of the lowest level of a pesticide that can be detected with acceptable precision and accuracy under specified test conditions [ 253 ]. Researchers have defined LODs in various ways, such as the logarithm of odds estimated on the basis of signal-to-noise ratio of 3 (3(S/N)) [ 205 ], the lowest concentration that produced a chromatographic peak that was three times larger than the background noise [ 48 ], higher value between the IDL and LOQ of blank samples [ 254 ], lowest addition level for the recovery analysis [ 85 ], amount of analytes per sample corresponding to the lowest calibration [ 255 , 256 ], and the concentration of analytes in a sample that yielded peak S/N [ 19 , 257 ]. The LOQ on the other hand is the lowest amount of a particular type of pesticide in the tested sample that can be determined under the specified test conditions with acceptable precision and accuracy [ 258 ].…”