Spatial distribution, possible sources and health risks of PAHs and OCPs in surface soils from Dajiuhu Sub-alpine Wetland, central China

The concentrations, spatial distribution, sources and health risks of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in Dajiuhu Sub-alpine Wetland, central China with totally 38 surface soil samples collected in July 2016 were investigated. The average concentrations were 42.4 +/- 38.5 ng.g(-1), 7.03 +/- 5.59 ng.g(-1) and 4.75 +/- 5.26 ng.g(-1) for Sigma(15)PAHs, HCHs (including alpha-HCH, beta-HCH, gamma-HCH, and delta-HCH) and DDTs (including o,p'-DDE, p,p'-DDE, o,p'-DDD, p,p'-DDD, o,p'-DDT, and p,p'-DDT), respectively. In general, the concentrations of POPs in peat soils (71.6 +/- 47.9 ng.g(-1) for PAHs, 22.9 +/- 11.0 ng.g(-1) for OCPs) were higher than those in non-peat soils (29.0 +/- 23.7 ng.g(-1) for PAHs, 6.61 +/- 3.06 ng.g(-1) for OCPs). The results of molecular diagnostic ratios and principal component analysis (PCA) indicated that PAHs in the study area were mainly originated from petroleum combustion and coal/biomass combustion emission. The relative low ratio of alpha-/gamma-HCH demonstrated that the residual HCHs in surface soils of Dajiuhu were mainly from continuous use of lindane; low ratio of o,p'-DDT/p,p'-DDT was found at most sites, indicating that DDTs were primarily come from historical use of DDTs. The incremental lifetime cancer risks (ILCRs) fluctuated from 10(-6) to 10(-5) for OCPs and 10(-7) to 10(-5) for PAHs, which indicated that OCPs and PAHs in the surface soils of Dajiuhu pose a potential cancer risk to local resident.