叶菜类蔬菜产地镉环境质量类别划分技术研究

以农业农村部环境监测总站对我国主要叶菜类蔬菜产地的例行监测数据为基础，综合考虑种类和土壤理化性质的影响，深入探讨了应用物种敏感性分布法（SSD）基于不同累积概率建立我国叶菜类蔬菜产地“优先保护类、安全利用类和严格管控类”的土壤镉环境质量类别划分阈值，并对其合理性验证.结果表明：pH值、阳离子交换量（CEC）和土壤有机质（SOM）对叶菜类蔬菜富集镉的影响均达到了极显著水平（P<0.01），并由其构建的三因子生物有效性模型为lgBCF=-0.122pH+0.025lgSOM-0.048lgCEC+1.252（R²=0.746，P<0.01，n=134），可解释叶菜类蔬菜富集系数74.6%的变异；利用上述模型将不同土壤理化性质条件下叶菜类蔬菜镉的生物富集系数（BCF）归一化处理可最大程度降低土壤理化性质对其富集镉的影响，凸出叶菜类蔬菜的内在敏感性；利用归一化后的BCF通过log-logistic拟合函数构建SSD曲线得到，不同叶菜类蔬菜种类对镉的敏感性差异明显；依据SSD曲线基于保护80%、50%和5%的叶菜类蔬菜种类分别推导出pH≤6.5、6.5

Study on the classification technology of the environmental quality category of cadmium in leaf vegetable production area

In order to establish the classification thresholds of cadmium content in the soil in the leafy vegetable production area in China, first the effects of vegetable types and soil physical and chemical properties on bioconcentration factor (BCF) was investigated. Then, the species sensitivity distribution (SSD) method was applied to develop the thresholds based on the routine monitoring data from the main vegetable production areas provided by the Agro-Environmental Monitoring Center of China. Results showed that the accumulation of cadmium in leafy vegetables were extremely and significantly influenced by soil pH, cation exchange capacity (CEC) and soil organic matter (SOM) (P<0.01). A three-factor bioavailability model was established as lg(BCF)=-0.122pH+0.025lgSOM- 0.048lgCEC+1.252(R²=0.746,P<0.01,n=134). The fitted model could explain 74.6% of the total variation in leaf vegetable enrichment. The model was then used to normalize BCF of leaf vegetable cadmium under different soil physical and chemical properties to minimize the influence of soil physical and chemical properties on cadmium accumulation, and to highlight the inherent sensitivity of leaf vegetable. The SSD curve was constructed by a log-logistic fitting function which was based on the normalized BCF. The results showed that the sensitivity of different leafy vegetables to cadmium was significant. Based on the protection rate of 80% (priority protection), 50% (safe use), and 5% (strictly control) for leafy vegetables, we derived the cadmium thresholds from SSD curves for these three categories: soil pH≤6.5, 6.5