草海湖湿地重金属分布特征及污染负荷

Distribution Pattern of the Heavy Metals and Its Pollution Load in Caohai Wetland

该文测定了草海湿地土壤和草海表层沉积物中7种毒性重金属的含量,对比研究了重金属元素含量的时空变异特征,同时应用单因子污染指数法和污染负荷指数法对底泥、沼泽草地、农用地和林地土壤中重金属污染进行了评价。结果表明:本研究中7种重金属中,Cd,Zn,Hg含量明显高于贵州省土壤背景值,重金属Cd和Zn分布特征为:底泥>农用地>沼泽草地>林地;Cr的分布特征为:沼泽草地>林地>农用地>底泥;Pb和Cu含量的分布特征为:农用地>底泥>沼泽草地>林地;Hg的分布特征为:底泥>沼泽草地>农用地>林地;As的分布特征为:林地>农用地>沼泽草地>底泥;草海湖周边的农用地和沼泽湿地中Cd,Hg达到重污染程度,Zn为中度污染,Pb和As为轻度污染。草海底泥中Cd,Hg和Zn达到重污染水平,其余4种重金属尚未构成污染;草海底泥重金属污染水平为中等污染,枯水期污染略重,且靠近湖心的采样点污染较重,3个采样区都呈现距岸边越远污染越重的趋势。草海湿地底泥重金属污染较重,农用地次之,沼泽草地再次,林地无重金属污染。研究可为草海湿地重金属污染放置与治理提供基础数据。

This paper examined the content of 7 toxic heavy metals in the wetland soil and the surface sediment of Caohai Lake, then compared spatial and temporal variability of the contents of heavy metals, and also assessed the heavy-metal pollution of the sediment, swamp, farmland and woodland in this region through the single factor pollution index and the pollution load index at the same time. The results showed that the contents of Cd, Zn and Hg were significantly higher than the soil background values of Guizhou Province, the contents of Cd and Zn in the sediment were far greater than those in the farmland, followed by swamp, and the woodland fourth. The content of Cr was the first in swamp, the second in woodland, the third in farmland and the fourth sediment. The contents of Pb and Cu were the first in farmland, the second in sediment, the third in swamp and the fourth in woodland. The content of Hg was the first in sediment, the second in swamp; the third in farmland and the fourth in woodland. The content of As was the first woodland, the second in farmland, the third in swamp and the fourth in sediment. The contents of Cd and Hg in the farmland and swamp surrounding Caohai Lake have reached level of heavy pollution, but content of Zn was at the level of moderate pollution, contents of Pb and As were at the level of light pollution. The levels of Cd, Hg and Zn in sediment of Caohai Lake have reached heavy pollution while contents of the other 4 have not caused pollution. The heavy-metal pollution of the sediment in Caohai Lake can be classified into the medium level, and it became more severe during the dry season. Especially, the sampling point near the center of the lake was more seriously polluted. For the three sampling region, the further the sampling point from the lakeshore was, the more serious the contamination was. With respect to the four kinds of soils, it was found that the sediment was contaminated most severely followed by the farmland, then swamp, while the wood-land was pollution-free. It is supposed that this study could provide some fundamental data for the prevention and control of the heavy-metal contamination of Caohai Lake.