土壤-蔬菜系统中镉的生物富集效应及土壤阈值研究

为保障蔬菜质量安全,避免重金属Cd污染,通过野外调查采集土壤-蔬菜样品224对,分析土壤和蔬菜中的Cd含量,研究不同种类蔬菜对Cd富集的差异及影响因素,并探讨了不同种类蔬菜的土壤Cd阈值。结果表明:蔬菜对Cd的富集受土壤Cd含量影响,与其呈显著性正相关关系,同时与土壤pH和有机质呈负相关关系。各蔬菜可食用部分中Cd的富集系数为0. 001～4. 901,平均值为0. 16。不同种类蔬菜对Cd的富集不同,其富集大小顺序为叶菜类茎菜类根菜类果菜类。利用log-logistic模型对研究数据进行拟合,并结合《食品中污染物限量》(GB2762-2017)中规定的蔬菜中污染物标准限值得到叶菜类、根菜类、茎菜类和果菜类蔬菜对应的土壤阈值分别为0. 25、0. 31、0. 33和0. 50 mg/kg。

Study on Bioaccumulation of Cadmium in Soil-vegetable System and Pollution Threshold in Soil

In order to ensure quality and safety of vegetable and avoid heavy metal pollution of Cd, this study collected 224 pairs of soil-vegetable samples through field investigations and analyzed contents of Cd in these samples. The different enrichments of Cd in different types of vegetable and the thresholds of Cd in soil for different types of vegetable were studied, and potential influencing factors were discussed. The results showed that:the enrichment of Cd by vegetable was affected by the content of Cd in soil, the enrichment of Cd in vegetable had a significant positive correlation with the content of Cd in soil, and had negative correlations with soil pH and organic matter content. The enrichment coefficient of Cd in edible parts of vegetable ranged from 0.001 to 4.901, with an average value of 0.16. Different types of vegetable had different enrichment effects of Cd, following an order of leaf vegetable > stem vegetable > root vegetable > fruit vegetable. According to the national standards for maximum levels of heavy metal contaminants in food (GB2762-2017) and the analytical result of the Log-logistic model, the Cd thresholds in soil for leaf vegetable, root vegetable, stem vegetable and fruit vegetable were 0.25, 0.31, 0.33 and 0.50 mg/kg, respectively.