河北省设施蔬菜土壤微量金属元素状况评价及来源分析

对河北省设施蔬菜土壤微量金属元素调查与评价表明,土壤出现不同程度的重金属污染和微量元素积累.以无公害蔬菜产地环境为评价标准,采用指数法评价,土壤重金属综合污染指数为1.25,属3级,轻污染水平.单项污染指数评价是镉(Cd)>铬(Cr)>砷(As)>铅(Pb),Cd、Cr单项污染指数分别为1.59,1.14,均属3级轻污染水平,As和Pb的单项污染指数分别为0.35和0.05,属1级安全水平;土壤Cd的超标率为73.7%,Cd超标率为68.4%.与河北省土壤自然背景值比较,土壤Pb和As含量在背景值以下,Cd和Cr含量分别是背景值的12倍和4倍.土壤微量元素呈现不同程度的积累趋势.土壤微量元素有效Fe、有效Mn、有效Cu和有效Zn含量分别是对照农田的5.7,2.9,4.0和15倍.以菜地土壤微量元素分级标准,4种金属元素处于高含量比例分别为65.8%,25.1%,100%,83.6%.在评价基础上,分析指出化肥尤其是进口磷肥是河北省设施蔬菜土壤Cd污染的主要来源,没有重金属限量标准的畜禽粪便和有机肥是Fe、Cu、Zn和Cr的主要来源.

The Evaluation and Sources Analysis of Heavy Metal and Micro-element in Soil for Protected Vegetable in Hebei Province

The investigation and evaluation of heavy metal and micro-element in soil indicated that the soil appeared heavy metal pollution and micro-element accumulation for protected vegetable in Hebei Province. Compared to the standard of envirnemt in base for no-pollution vegetable, the synthetic pollution index for heavy metal was 1.25 and it was polluted lightly. The individual pollution index was Cd>Cr>As>Pb. The index for Cd and Cr were 1.59 and 1.14 respectively, and both belonged to the third class. The index for Pb and As were 0. 05 and 0.35 ,and belonged to the first class and no pollution respectively. The ratio of exceeded standard for Cd and Cr were 73.7% and 68.4%. Compared to the background of Cd and Cr of soil in Hebei,the content of Pb and As were low. And the content of Cd and Cr were respectively twelve times and four times. The result showed that the soil micro-element took on accumulation in according to assessment standard of protected vegetable. The content of DTPA-Fe,DTPA-Mn,DTPA-Cu,DTPA-Zn were respectively 5.7 times,2.9 times,4.0 times and 15 times compared to farmland. In according to assessment standard, the ratio of high level for micro-element were indidually 65.8%, 25.1% ,100% and 83.6%. On the base of appraisal,it was analysed the source of heavy metal Cd was chemical fertilizer especially phosphorus fertilizer, the sources of micro-element Fe,Cu,Zn and Cr were dejeeta and organism fertilizer made of livestock and birds, litter and contamination without standard of limit for heavy metal content.