寿光市蔬菜大棚土壤重金属含量的环境质量评价

Evaluation on Environmental Quality of Heavy Metal Contents in Soils of Vegetable Greenhouses in Shouguang City

对寿光市蔬菜生产基地的大棚土壤进行了重金属Cd,Hg,As,Pb,Cr,Cu,Zn和Ni含量的抽样调查分析,并采用单项质量指数与综合质量指数相结合的方法对重金属的环境质量状况进行评价.结果表明,蔬菜大棚土壤各重金属的平均含量均低于温室蔬菜产地环境质量评价标准(HJ333—2006)的限值,土壤环境质量定为1级,属于清洁水平,适宜发展无公害蔬菜.重金属含量之间多呈正相关关系,其中w(Cd)与w(Pb),w(Pb)与w(Cr),w(Cu)与w(Zn)的相关性达到了显著水平(P<0.05),w(Cr)与w(Ni)的相关性达到了极显著水平(P<0.01).除Pb与Ni外,其他重金属含量均与大棚使用年限呈正相关关系,w(Zn)与棚龄的相关性最强,达极显著水平(P<0.01).与棚外麦地土壤相比,棚内土壤重金属含量明显较高,Hg,Cd,Zn含量明显高于自然背景值.部分地区的蔬菜大棚土壤有Cd和Ni元素超标的现象,Cd的样本超标率为15.4%,Ni的样本超标率为5.8%.为了有效地降低环境风险,建议适当降低施肥量,种植抗重金属污染能力较强的蔬菜.

Contents of heavy metals Cd, Hg, As, Pb, Cr, Cu, Zn and Ni in soils of greenhouses in the vegetable production bases of Shouguang City were investigated by randomly sampling. The environmental quality conditions Of these heavy metals were evaluated by methods of single quality index and comprehensive quality index. Results showed that the average contents of heavy metals in soils of vegetable greenhouses were all under the limit values prescribed by Environmental Quality Evaluation Standard for Farmland of Greenhouse Vegetables Production （HJ333-2006）. The soil environmental quality was set at the first class belonging to clean level and was fit for the plantation of nonenvironmental pollution vegetable. Most of the heavy metals were positively correlated in contents, and the correlation of Cd and Pb, Pb and Cr, Cu and Zn reached a significant level （ P 〈 0.05 ）, while the correlation of Cd and Ni reached a very significant level （ P 〈 0.01 ）. Except Pb and Ni, the other elements were all positively correlated with the age of greenhouses. The correlation of Zn and greenhouse age was the strongest and reached a very significant level （ P 〈 0.01 ）. Compared with wheat soils outside greenhouses, the contents of heavy metals in soils within greenhouses were obviously higher. Contents of Hg, Cd and Zn were much higher than local natural background value. The contents of Cd and Ni in soils of the greenhouses of some areas were beyond the limit values and the beyond rate was 15.4% and 5.8 % respectively. To reduce environmental risks effectively, the amount of fertilizers used were proposed to be decreased, and more vegetables resistant to the pollution of heavy metals to be planted.