基于生物可利用性与宽浓度范围的Hakanson潜在生态风险指数法的创建——以小秦岭金矿区农田土壤为例

Hakanson潜在生态风险指数法是土壤重金属潜在生态风险评价的一种常用方法,研究与实践证明其有效性的同时,也发现了其不足之处:忽略了土壤重金属不同形态之间潜在生态风险的差异,且只重视重金属含量高于参考值时的生态风险,而对低于参考值时的情况没有给予考虑,以致特定情况下的评价结果不能很好地反映实际生态风险,因而有必要创建适用性更广的Hakanson潜在生态风险指数法。为此,基于全过程控制优化的思想,引入了生物可利用性毒性系数,并将修正浓度与参考值差值引入计算公式,创建了基于生物可利用性与宽浓度范围的Hakanson潜在生态风险指数法,实现了对重金属不同形态风险贡献的差异及重金属浓度低于参考值情况下潜在生态风险的准确把握。以小秦岭金矿区为典型区域,辅以对采集土样重金属总量及5种形态含量的分析,开展案例研究。结果表明,基于生物可利用性与宽浓度范围的Hakanson潜在生态风险指数法能客观地揭示土壤重金属的潜在生态风险,具有更大的适应性,是一种有效的潜在生态风险评价方法。

The improvement of Hakanson index based on bioavailability and wide concentration range: A case study of the farmland soil over the Xiaoqinling gold mining area for potential ecological risk assessment of heavy metals of contaminated soil

Hakanson comprehensive index method is one of the methods for the potential ecological risk assessment of heavy metals in contaminated soil. Although its effectiveness has been proved, there also exist several disadvantages. Firstly, the difference in the toxicity of each fraction of heavy metals is ignored. Secondly, it is applied to the case that heavy metal content is higher than the background value, while for the opposite case it is not suitable. As a result, the Hakanson comprehensive index can hardly reflect the real risk in some cases. To solve these problems, the authors tried to modify Hakanson comprehensive index method on the basis of the theory of the whole process control and optimization. The Xiaoqinling gold mining area, which is located in eastern Shaanxi Province and is the second largest gold mining area in China, was selected as a case study. The modified Hakanson comprehensive index method was checked, and the results show that the modified method is effective for potential ecological risk assessment, and hence has a greater adaptability.