湖州市不同土壤重金属的污染现状

湖州市是主要的农产品基地，其主要土壤类型有四种，即黄泥土、青紫泥、白泥土和湖松土。样品分析表明重金属元素在黄泥土和青紫泥中较高，白泥土和湖松土中较低。大多数重金属元素相对下蜀土是富集的，超过自然背景值的元素有Cu,Cd及部门土壤中的Pb和Hg。有机质、pH值和Eh值对重金属的含量和化学形态有影响，有机质愈高，重金属的含量愈高；pH值接近中性，重金属的含量亦高。土壤的氧化条件可使大多数重金属变为高价离子，它们的化合物活性较低，但Cr^6 易被植物吸收。湖州土壤中重金属的高值点与工业污水排放和大气沉降有关。土壤中对农作物有危害的重金属元素为Cd和Hg，局部地方为Pb。

Characteristics of Heavy Metal Enrichment in Soils in Huzhou City

Huzhou city is lied in the middle part of the Yangtze delta. It is a main base of agricultural products. There are four types of soils,ie. Yellow soil,Blue - violet soil, White soil and Loose - in - lake soil. The heavy metal contents in Yellow soil and Blue - violet soil are higher those of White soil and Loose - in -lake according to analysis of samples. Most of heavy metals in Huzhou Soils are enriched comparing to that in Xiashu soils. Copper,cadmium in whole area and lead,mercury in some spots are higher than that of the matural background. The organic matter,pHand Eh make great effects on the content and chemical forms of heavy metal. The much the organic marrer is ,the higher the content of heavy metal is. The content of heavy metal is high relatively when pH is clise to neutral. The oxidized condition in Huzhou soil makes almost if heavy metal high valence states,whereas their compounds have little activities. But Cr is easily absorbed by the plant. The high value spots of heavy metal in Huzhou city are relevant with the discharge of industrial sewage and the dropping in atmosphere. The harmful heavy metals for agricultural plants in soils are cadmium,mercury and lead.