Contamination of polychlorinated biphenyls and hexachlorobutadiene in greenhouse and open-field agricultural soils across China

Abstract

Combined with the physical isolation feature of greenhouse, the popularization of greenhouse throughout China makes the pollution of greenhouse soils more noteworthy as a result of its high yielding food exposed to human beings. Here, a national-scale survey was conducted to evaluate the contamination status, contaminated sources and human health risks of polychlorinated biphenyls (PCBs) and hexachlorobutadiene (HCBD) in greenhouse and open-field soils of 20 regions across China. The PCBs contents ranged from <LOD to 673.78 ng/g with the mean content of 77.38 ng/g in greenhouse soils and ranged from <LOD to 552.53 ng/g with the mean content of 61.90 ng/g in open-field soils. The HCBD contents ranged from 0.85 ng/g to 24.18 ng/g with the mean content of 8.33 ng/g in greenhouse soils and ranged from <LOD to 20.19 ng/g with the mean content of 6.39 ng/g in open-field soils. Among divided seven regions, higher levels of PCBs in greenhouse and open-field soils were found in north and south China. Furthermore, in most regions, correlation analysis indicated that soil PCBs in greenhouse and open-field were likely from the same emission sources. Higher levels of soil pollutants in greenhouse than in open-field may be contributed to the limited air-soil exchange. Compared with higher levels of ΣPCBs in greenhouse soils, the health risks of ΣPCBs in open-field soils were higher due to the higher percentages of high-toxicity PCBs, especially for the carcinogenic risks to children (> 10-6). This study provided a full insight into the contamination status and risks of PCBs and HCBD when guiding greenhouse agriculture activities.