长江下游典型工农业交错区土壤重金属含量随时间变化特征

Characteristics of temporal variations of heavy metals in the soil at the industry-agriculture transition area from the lower Yangtze River region

以长江下游八卦洲工农业交错区为研究区,研究了表层土壤2014年相对于2003年重金属等元素含量变化特征、富集机制与影响因素.结果表明,2014年研究区土壤Cd、Zn、Cu、Cr平均含量较2003年发生显著的增加,其增加率分别为32%、15%、14%和11%;Hg平均含量发生了显著的下降,下降率是20%;As、Pb和Ni含量未随时间呈现出显著变化.土壤Cu、Zn、Ni、Cr、Cd和As在大多采样点表现为含量的增加;Hg在大多数采样点表现为含量降低.分析表明,重金属富集范围和程度的变化主要受研究区周围工业分布以及调整的影响,大气沉降是土壤Cd、Cu、Zn、Cr、Ni等重金属富集加强最主要的贡献因子,而土壤Hg含量的降低主要与Hg的地球化学行为特性以及产业结构调整有关.土壤重金属富集不仅与外源物质输入有关,元素本身的地球化学性质和行为导向也是非常重要的影响因素.

An industry-agriculture transition area from the lower Yangtze River region was selected to study the variations of heavy metals in the soil and the mechanism of enrichment. The results show that the concentrations of Cd,Zn,Cu and Cr increased significantly in 2014 relative to 2003,and the rate of increase was 32%,15%,14% and 11% respectively. The concentration of As,Pb and Ni presented no significant change,and the concentration of Hg presented significant decrease. Most of the sampling sites show an increase in the concentrations of Cu,Zn,Ni,Cr,Cd and As.Only20% of samples showed in creased concentration of Hg. The changes of rates and ranges of heavy metals enrichments were affected by the adjustment of industry sectors, and the atmospheric deposition may be the most important contribution to soil Cd,Zn,Cu,Cr,Ni,etc enrichment. The decrease of soil Hg concentration may be related to the specific geochemical behavior and therelocation of mercury-related enterprises. The results of the present study imply that the soil heavy metal enrichment is not only related to the exterior matter import such as atmospheric deposition,but also influenced by their geochemical characteristics.