Risk Assessment Of Heavy Metal Pollution In Soil-vegetable System In Lanzhou Petrochemical Industrial Complex

Heavy metal contamination is a global environmental problem.In Xigu Petrochemical Industrial Zone,due to historical issues,some of the land is used as vegetable field,making this problem more complicated.In this study,we conducted a contamination assessment in the vegetable fields and made some suggestions for local pollution control program.Main conclusions are as follows:1.The contents of As,Cd,Cr,Cu,Hg and Pb in the vegetable fields were higher than local background value,but lower than China Environmental Quality Standard values.The contents of heavy metals in cabbage cultivated in the vegetable field is lower than their relevant national standards.2.Potential ecological risk index indicate that the vegetable fields were considerably contaminated,mainly due to the accumulation of Cd and Hg.3.The results of the human health risk assessment showed that oral ingestion of soil particles and vegetable diet were the main exposure pathways for local residents.The health risks of local residents are mainly from the exposure of Cr and As.In addition,Pb could not also be ignored by its carcinogenic risk.4.PCA analysis and cluster analysis divided the heavy metals into three groups: Copper,Cd,Cr and Pb were mainly derived from industrial activities and transportation emissions;Mercrury was mainly from coal combustion;Arsenic was mainly from parent materials.5.Among all the plant species collected in Xigu Petrochemical Industrial Zone,Ulmus pumila cv.jinye,Malus spectabilis,Helianthus tuberosus and Prunus triloba have better phytoextraction performance,however,they are still not hyperaccumulators.Thus,if we choose them as local phytoremediation plants,we need to apply chelating agents,biochar or microbe to assist hytoremediation.6.Our recommendations are: 1)The petrochemical industry area is not suitable for agricultural activities.We should change its land use and remediate the contamination.2)To reduce the health risks,local residents should wear breathing masks to filter the particles in the air and try to avoid the consumption local cultivated vegetables.