Contamination Status, Environmental Factor and Risk Assessment of Polychlorinated Biphenyls and Hexachlorobutadiene in Greenhouse and Open-Field Agricultural Soils across China

With the popularization and high-intensity utilization of greenhouse cultivation for crops growth, the pollution of greenhouse soils has been of concern. Therefore, a national-scale survey was conducted to investigate the contamination status, sources, influence factors and the risks of polychlorinated biphenyls (PCBs) and hexachlorobutadiene (HCBD) in greenhouse and nearby open-field soils. Contents of PCBs ranged from <LOD to 673.78 ng/g (mean: 77.38 ng/g) in greenhouse soils, and <LOD to 552.53 ng/g (mean: 61.90 ng/g) in open-field soils. HCBD was detected in all greenhouse soils with content ranging from 0.85 to 24.18 ng/g (mean: 8.33 ng/g), and a range of <LOD-20.19 ng/g (mean: 6.39 ng/g) in open-field soils. The sources of PCBs were the disposal of electrical equipment, domestic coal, wood burning emissions, etc. Levels of PCBs and HCBD were not correlated with the soil properties but positively correlated with Pseudomonas as the PCBs-degrader in open-field soils. Although the higher values of mean contents were found in greenhouses, the health risks of sigma PCBs in open-field soils were higher than in greenhouse soils due to the higher percentages of high-toxicity PCBs, especially the carcinogenic risks to children (>10-6). This study provided a full insight on the contamination status and risks of PCBs and HCBD when guiding greenhouse agriculture activities.