贵州菜园土壤重金属赋存形态分布及生物有效性分析

Distribution and Bioavailability of Heavy Metals in Vegetable Soils in Guizhou

选取贵州沿河、龙里、兴义地区的菜园土壤共计22个样点作为研究对象，利用原子吸收光谱法测定土壤中重金属（Cd、Cu、Zn）总量及其5种化学形态（可交换态、碳酸盐结合态、铁（锰）氧化物结合态、有机质及硫化物结合态、残渣晶格结合态）的含量，并就菜园土壤重金属对农作物生物有效性的影响进行分析。结果表明，所研究的菜园土壤中Cu和Zn含量均小于贵州土壤背景值，其活性态含量在总量中所占的比例较低。土壤中Cd总量的平均值明显大于本地土壤背景值，且其活性态Cd含量很高，平均值占总量的46％。土壤的pH值在4．22～7．83，土壤pH的差异对土壤中Cu和Zn的生物有效性影响不大，对Cd金属形态含量有明显影响。贵州菜园土壤中Cu和Zn的总体环境风险较小，但Cd的总量和活性态含量较高，对生物有效性存在较高风险，并有可能会影响到农产品安全。

Total amount of Cd, Cu and Zn and content of 5 kinds of chemical forms of 22 soil samples from vegetable soils of Yanhe, Longli and Xingyi were determined by atomic absorption spectroscopy and the effect of heavy metals on crop bioavailability was analyzed. The results showed that Cu and Zn content in tested soils was lower than the background value of Guizhou soil, and the content of their active forms in total contents was very poor, mean total Cd content in tested soils was obviously higher than local soil background value and the Cd content with active form accounted for 46% of total content, pH value of tested soils had no obvious effect on bioavailability of Cu and Zn in soil but had significant effect on content of Cd chemical form. Because total Cd content and active Cd content in vegetable soil is higher, which may affect safety of agricultural products in Guizhou.