环洞庭湖区典型蔬菜基地土壤重金属污染状况研究

对环洞庭湖区典型蔬菜基地的土壤,按成土母岩母质研究了其重金属污染现状。结果表明:第四纪红土发育的土壤综合污染指数处于警戒线附近,仅Cd出现15%的超标,未受到其他重金属的污染;板页岩与河流冲积物发育的土壤综合污染指数平均为1.14和1.02,均达到轻污染水平,污染元素均为Cd、Cu和Ni,板页岩发育的超标率分别为56%、75%和38%,河流冲积物发育的超标率分别为45%、26%和12%。该区土壤Cd污染比较严重可能是较高的Cd背景值和长期大量施用磷肥带入Cd元素共同造成的;Cu污染可能是长期施用大量粪肥引起的;N i虽然也有超标,但可能并非受到外界污染,而是背景值较高引起的。该区第四纪红土发育的土壤质量较好,宜继续发展蔬菜种植;对河流沉积物和板页岩发育的土壤应注意Cd和Cu的污染。

Pollution Status of Heavy Metals in Soils of Typical Vegetable Bases Around Dongting Lake Region

We surveyed pollution status of heavy metals in soils classified by parent materials for typical vegetables bases around Dongting Lake region.The results showed that the soils derived from Quaternary red clay contain warning limit of heavy metals,and only 15% of the soils are polluted by Cd.However,exceeding official limits of Cd,Cu and Ni account for 56%,75% and 38% for the total soils that derived from slate shale,and the percentages were 45%,26% and 12% in soil that derived from alluvial deposit of rivers.The both were in little pollution,with comprehensive pollution indexes of 1.14 and 1.02,respectively.The pollution of Cd in soils may be caused by its highly background and the utilization of superfluous phosphorus fertilizer for decades around Dongting lake region.The use of a large amount of manure may be another origin of Cu pollution in soils.And the over-limit rate of Ni in soils was so high for its high background.In conclusion,quality of the soils derived from the Quaternary red clay was suitable for vegetable,and we should pay attention to the pollution of Cd and Cu in the soils derived from slate shale and alluvial deposit of rivers.