唐山市南湖城市中央生态公园土壤重金属形态特征研究

Study on Chemical Form Distribution Characteristic of Soil Heavy Metals in Nanhu Ecological Park in Tangshan

土壤重金属元素的存在形态是衡量其环境效应的关键参数。选择唐山市南湖城市中央生态公园为研究区,采集了20个表层土壤样品,采用BCR三步连续提取法对土壤中的重金属(Cu、Pb和Cr)不同形态(酸可提取态、氧化物结合态、有机结合态、残渣态)特征进行分析,并采用相关分析探讨影响重金属化学形态的影响因素。研究结果表明:土壤中Cr和Cu主要以残渣态和酸可提取态存在,Pb主要以氧化物结合态和残渣态存在;Cr的酸可提取态较其他元素高,对环境的潜在风险较大。相关分析显示,土壤pH与重金属的酸提取态含量呈极显著负相关,与Cu和Pb的氧化物结合态含量呈极显著正相关,土壤有机质含量与Cu和Pb的有机结合态含量呈极显著正相关关系。在生态公园建设过程中,可通过适当提高土壤pH的方法来减少重金属的酸可提取态含量,降低其生态环境风险。

The fraction distribution of heavy metals is the key parameter of its environment effects. In this article, form distribution characteristic of soil heavy metals （Cr, Cu, Pb） and its influencing factors were investigated in Nanhu ecological park in Tangshan. A total of 20 soil samples were collected and analyzed. Using BCR（European Community Bureau of Reference） sequential extraction procedure, four fractions of soil heavy metals, weak acid soluble fraction, reducible fraction, organic matter fraction and residual fraction, were extracted in the topsoil （0-20 cm） , and its influencing factors were studied by correlation analysis. The results showed that Cr and Cu were dominated mainly by the fraction of residual fraction and weak acid soluble fraction, while Pb was existed by the fraction of residual Pb and reducible Pb; Only Cr indicated some potential environmental risks, because of its higher values in weak acid soluble forms. Correlation analysis indicated the soil pH value had very significantly negative correlation with the heavy mental weak acid soluble forms, very significantly positive correlation with the reducible fraction of Cu and Zn. The content of soil organic matter had very significantly positive correlation with the organic forms of Cu and Pb. In the process of ecological park construction, the environmental risks can reduce though out reduce weak acid soluble fraction of heavy mental, which can achieve by raising soil pH slightly.