苏南某镇土壤重金属污染的景观格局特征

评价土壤重金属污染等级并掌握其空间格局特征,对区域土壤环境保护和治理具有重要意义.以苏南某镇8种土壤重金属As、Cd、Cr、Cu、Hg、Ni、Pb和Zn为研究对象,综合运用单因子评价法、内梅罗综合评价法、地统计分析法、景观格局的粒度效应及景观指数分析方法,在污染评价的基础上,分析了研究区土壤重金属的景观格局特征.结果表明:1研究区各土壤重金属单因子污染指数及内梅罗综合评价指数的均值取值范围为0.145~0.893,整体污染程度低,且南部地区污染程度低于北部;2 As、Pb、Hg和Zn面源污染特征明显,其中As和Pb空间分布特征相似,Hg和Zn空间分布特征相似;Cd、Cr、Cu、Ni点源污染特征显著,其中Cd和Cr空间分布特征相似,Cu和Ni空间分布特征相似;3土壤重金属景观的适宜粒度为30~40 m;4研究区土壤重金属低含量区域面积比例最大,较低含量区域边界最复杂,各污染程度区域分布相对集中且综合污染破碎化程度低.表明研究区重金属污染源数量尚少且分布集中,但有进一步发展的趋势,整体处于土壤重金属污染的早期阶段.

Landscape Patterns Characteristics of Soil Heavy Metal Pollution in a Town of Southern Jiangsu

It is of great significance to evaluate the soil heavy metal pollution level and to know their spatial distribution characteristics. Taking soil heavy metals As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in a town of southern Jiangsu as research objects, using the single factor evaluation method, Nemerow comprehensive evaluation method, geostatistical analysis method together with the landscape pattern grain effect and the landscape index analysis method, we studied their characteristics of landscape patterns in the study area based on pollution evaluation. The results showed that:① The average value range of single factor pollution index and Nemerow comprehensive evaluation index for soil heavy metals in study area was 0.145-0.893.The overall pollution level was low. The pollution level of south area was lower than that of north area; ② As, Pb, Hg, and Zn elements showed obvious non-point pollution characteristics.As and Pb showed a similar spatial distribution. So were Hg and Zn elements. In contrast, Cd, Cr, Cu and Ni elements showed obvious point pollution characteristics. Cd and Cr showed similar spatial distribution. So were Cu and Ni elements; ③ The suitable grain effect landscape index of nine soil heavy metals pollution landscape was 30-40 m; ④ The low concentration area of soil heavy metals in the study area accounted for the largest proportion. The border of lower concentration area was the most complex part. The distribution of all pollution level areas was relatively concentrated and the comprehensive pollution fragmentation degree was low. The source pollution of soil heavy metals was in concentrated distribution, and its number still counted low, but there was a tendency for further development. As a whole, it was still in the early pollution stage of soil heavy metals.