西南地质高背景区蔬菜Pb的安全生产阈值与土地质量类别划分

Safety Production Threshold and Land Quality Classification of Vegetable Pb in High Geological Background Area of Southwest China

为确保西南地质高背景区与人类活动交互叠加的农田土壤Pb污染蔬菜品种的安全生产,选取西南地区广泛食用的蔬菜作物32种,利用相关性分析和多元线性回归分析等方法研究了土壤-蔬菜中Pb累积规律和关键制约因子,西南地区农田土壤Pb生态安全阈值采用物种敏感度分布法确定.结果表明,研究区土壤ω(Pb)为47.59~462.38 mg·kg^(-1),高于云南省土壤Pb背景值(90 mg·kg^(-1))的1.88倍,68.40%的土壤样品超过农用地土壤污染风险管控标准的筛选值.蔬菜类作物可食用部分ω(Pb)为0.02~0.49 mg·kg^(-1),超标率达到20.49%,表现为:叶菜类>根茎类>茄类>食用豆类>辣椒类.基于土壤pH值、OM和CEC构建了蔬菜Pb吸收累积模型,显示pH值为影响蔬菜Pb累积的首要关键因子.蔬菜Pb物种敏感度分布曲线显示叶菜类、茄类和食用豆类对Pb的敏感度较差,根据蔬菜产地"优先保护、安全利用和严格管控"这3类区域土壤划分标准确定Pb阈值分别为:≤100、100~353和≥353 mg·kg^(-1).

In order to ensure the safe production of vegetables in Pb-contaminated farmland under the complex interactions of an extreme geological background area and human activities in Southwest China,32 types of widely planted vegetable varieties in the southwest region were collected.Correlation analysis,multiple linear regression analysis,and other methods were used to study the accumulation of Pb in soil^(-)vegetables and the key constraints.The threshold of soil Pb ecological security in farmland in southwest China was determined by the method of species sensitivity distribution.The results showed thatω(Pb)of the soils was 47.59-462.38 mg·kg^(-1),which was 1.88 times higher than that of the background value of soil Pb in Yunnan Province(90 mg·kg^(-1)),and 68.40%of the soil samples exceeded the screening value of the"Soil Environmental Quality Agricultural Land Soil Pollution Risk Management Standard"(GB 15618-2018).The content of Pb in the edible parts of vegetable crops ranged from 0.02 to 0.49 mg·kg^(-1),and the exceeding rate reached 20.49%.Pb concentration in the vegetables was in the decreasing sequence of leafy vegetables>roots and stems vegetables>eggplant vegetables>edible bean vegetables>pepper vegetables.Based on soil pH,OM,and CEC,the model of Pb accumulation in vegetables was constructed,in which pH was the first critical factor affecting Pb accumulation in vegetables.The sensitivity index of vegetable Pb species showed that leafy vegetables,eggplant vegetables,and a small number of frame bean vegetables were less sensitive to Pb.The soil Pb classification thresholds of the three types(priority protection,safe use,and strict control)of areas for vegetable safety production was≤100,100-353,and≥353 mg·kg^(-1),respectively.