中国部分林地土壤重金属含量特征及污染评价

Heavy Metal Contents Distribution and Contamination Assessment in Some Chinese Forest Soils

为掌握中国林地土壤重金属污染状况,选取中国13个具有代表性林地土壤,结合经典的重金属污染评价方法,分析土壤中重金属(铅、镉、铜、锌)的含量分布特征和污染程度,通过相关和回归分析,研究土壤理化性质对土壤重金属全量及有效态含量的影响。结果表明:不同地区林地土壤重金属含量波动较大,绝大部分位点土壤重金属含量均未超过GB 15618—2018中筛选值。以筛选值作为评价标准时,绝大部分土壤重金属单因子指数小于1,说明供试土壤重金属处于清洁与尚清洁状态;内梅罗综合指数评价结果显示,除武夷山、卧龙自然保护区土壤重金属处于警戒线等级外,其他地区均处于清洁。以管制值为评价标准时,土壤重金属污染指数以及内梅罗综合污染指数均处于小于0.7。潜在生态风险指数评价结果表明,研究区域大部分位点土壤中Cd存在中等或较高的潜在生态风险,土壤中重金属呈轻微等级的综合潜在生态风险。地质累积指数表明,大部分土壤重金属均存在不同程度的累积,其中部分样点Cd、Zn达到中度污染水平,累积效应更加显著。相关性与回归性分析显示,土壤pH与有效态Cu呈显著正相关性,基于土壤理化性质的多元回归方程可以较好地预测土壤中有效态Pb和Cu的含量,相关系数R2分别达到0.962和0.895。

In order to detect the pollution situation of heavy metals in forest soil,13 representative soil samples were selected in wide range of China to analyze the distribution characteristics and pollution status of heavy metals(lead,cadmium,copper,zinc)in forest soil by classic heavy metal pollution assessment methods.Meanwhile,the correlation and regression analysis was applied to evaluate the relationship between soil physical-chemical properties and total and soluble metal concentrations.The results show that the contents of heavy metal in different areas fluctuate greatly,which are below the screening values of GB 15618—2018 in most sites.The assessment values by single pollution index are less than 1 in most soil sties as the screening values for compared standard,indicating that the heavy metals in the tested soil samples are clean.The Nemero pollution index evaluation results show that the pollution grade of most soil samples is clean,except Wuyi Mountain and Wolong Nature Reserve at the alert level.The evaluation values by single pollution index and Nemero pollution index methods of soil heavy metal(Pb and Cd)are less than 0.7 as the risk intervation values for compared standard.The single factor ecological risk index show that there is a medium or high potential ecological risk for most sites,while slight potential ecological risk is detected for complex ecological risk index of all soil heavy metals.As show by geo-accumulation index,different degrees of accumulation for heavy metals are observed for most sites,in which moderate pollution of Cd and Zn exist with obvious accumulative effect.Correlation and regression analysis show that the pH is significantly positively correlated with the available Cu.The soluble Pb and Cu concentrations can be better predicted by multiple regress equations combined with significant soil properties,and the correlation coefficient R 2 is 0.962 for Pb and that for Cu is 0.895,respectively.