不同恢复方式下二郎山公路创面的土壤重金属分布特征及其污染评价

Distribution Characteristics and Pollution Assessment of Heavy Metals in Wounded Soils of Erlang Mountain Highway under Different Restoration Methods

摘要: 于2018年4月以四川省雅安市二郎山公路创面土壤作为研究对象，分析人工恢复与自然恢复下土壤中4种重金属(Zn, Cr, Pb, Cu)的含量特征及其与土壤化学指标之间的相关性，以四川省土壤背景值和全国土壤重金属Ⅱ级背景值为评价标准，对两种恢复方式下的土壤重金属污染和潜在生态风险进行分析评价。结果显示：无论何种恢复方式下Zn的平均含量值最大，Cr的最低，在这两种恢复方式下4种重金属的平均含量由低到高的排序有所不同，人工恢复方式下为：Zn > Cu > Pb > Cr，自然恢复方式下为Zn > Cu > Cr > Pb。人工恢复方式下4种重金属的变异系数在22.80%~60.95%之间，自然恢复下在28.37%~69.67%之间，表明在两种恢复方式下土壤中重金属含量分布比较均匀，存在一定的相似性。除Pb最大值和Cu最大值比四川省背景值高外，其他重金属含量均未超过我国土壤环境质量标准的II级标准值。人工恢复和自然恢复方式下土壤中Cr、Pb、Zn、Cu含量之间呈极显著正相关，Zn、Cr、Pb三种元素可能来源相同。Cu元素与IP (无机磷)为负相关，其余三种金属元素为正相关；四种金属元素与 、TP、IP的相关性不显著。对比单因子指数法和内梅罗综合污染指数法与Hakanson潜在生态危害指数法得出的分析结果是基本一致，两种恢复方式下的综合污染指数都在2以下，为轻污染；人工恢复下的潜在生态危害系数及潜在生态危害指数均大于自然恢复状态下的值，可推测出人工干预的土壤恢复存在的重金属潜在生态危害较自然恢复下的高。

Abstract: In order to analyze the content characteristics of four heavy metals (Zn, Cr, Pb, Cu) in wounded soil under artificial and natural restoration and their correlation with soil chemical indexes, the soil of Erlangshan Highway in Ya’an City of Sichuan Province was taken as the research object in April 2018, and the soil background values of Sichuan Province and national soil heavy metals level II background values were used as evaluation criteria to analyze the soil heavy metal pollution and potential ecological risk under two restoration modes. The results showed that the average content of Zn was the largest and that of Cr was the lowest under any restoration mode. The order of the average content of four heavy metals was different from low to high under the two restoration modes. The order of the average content of four heavy metals was: Zn > Cu > Pb > Cr under artificial restoration mode and Zn > Cu > Cr > Pb under natural restoration mode. The variation coefficients of the four heavy metals were 22.80% - 60.95% under artificial restoration and 28.37% - 69.67% under natural restoration, which indicated that the distribution of heavy metals in soil under the two restoration methods was relatively uniform and there was some similarity. Except that the maximum values of Pb and Cu are higher than the background values of Sichuan Province, the contents of other heavy metals do not exceed the standard values of Grade II of China’s soil environmental quality standards. The contents of Cr, Pb, Zn and Cu in soil under artificial restoration and natural restoration were significantly positively correlated, and the three elements of Zn, Cr and Pb might come from the same source. Copper is negatively correlated with IP (inorganic phosphorus), while the other three metal elements are positively correlated. There is no significant correlation between the four elements and  , TP and IP. Comparing single factor index method and Nemerow comprehensive pollution index method with Hakanson potential ecological hazard index method, the analysis results are basically the same. The comprehensive pollution index under the two restoration methods is less than 2, which is light pollution. The potential ecological hazard coefficient and potential ecological hazard index under artificial restoration are higher than those under natural restoration, so it can be inferred that the soil under artificial intervention is better than that under natural restoration. The potential ecological hazards of heavy metals recovered are higher than those under natural restoration.