杭州市和睦湿地农田土壤重金属污染评价及关联特征研究

调查了和睦湿地农田土壤中的重金属污染现状,结果表明：南星桥、九曲桥、幸福桥和九曲桥南土壤中的Cu、Zn、Ni全量相对较高;从单项污染指数看,俞家桥北土壤中Zn的单项污染指数超过1.0,其它均小于1.0,受污染影响不大;从综合污染指数看,和睦湿地多处农田土壤属安全级,达清洁水平,但少数土壤重金属污染等级已达警戒级。从单项累积指数看,和睦湿地农田土壤中重金属Cu、Zn、Ni和Pb的累积程度相对较高;从综合累积指数看,和睦湿地农田土壤中重金属污染多为中度或轻度累积。就土壤重金属含量与其理化性质相关分析发现,土壤Cu含量与土壤速效K含量呈显著负相关,而与土壤阳离子交换量呈显著正相关;土壤Ni含量与土壤速效P、速效K含量呈显著负相关。和睦湿地农田土壤重金属多达中、轻累积水平,且可能与土壤肥料施用方式密切有关,应引起相关部门高度重视。

An Assessment and Characterization of Heavy Metal Pollution in the Farmland of Hemu Wetland

Based on an analysis of heavy metal pollution in the farmland soil of Hemu wetland, it was found that the total contents of Cu, Zn, Ni in such areas as Nanxing Bridge （NXB）, Jiuqu Bridge （JQB）, and Xingu Bridge （XFB） were relatively high. The pollution index of single elements of northern Yujia Bridge （YJB） surpassed 1.0 while those of other regions were lower than 1.0, indicating that the effects of pollution were moderate. Judging from the aggregated pollution Index （API）, the warning pollution level was found for some soils, while the most of them were at the security level and clean level. Furthermore, the single accumulation index of Cu, Zn, Ni and Pb in farmland soils of Hemu wetland was relatively high, while most heavy metal pollution were classifi ed as mild or moderate in terms of the comprehensive accumulation index. Studies on heavy metal contents and their physicochemical properties showed that the content of soil Cu correlated negatively with that of available K and positively with the cation exchange capacity of the soil, both in a signifi cant way. However, the content of Ni in soil correlated negatively with soil available P and K. To conclude, the accumulation level of heavy metal in the farmland of Hemu wetland was relatively high, which might have something to do with the ways of fertilizers application and therefore attention should be given by the relevant authorities.