Analysis and Evaluation of Soil Heavy Metal Environmental Quality in Farmlands of Vegetables Cultivated in Open Field of Shandong Province,China

Soil heavy metals contents,Cd,Hg,As,Pb,Cr,Cu,Zn and Ni,in farmlands of vegetables cultivated in open field of Shandong Province were investigated by randomly sampling.The environmental quality conditions of these heavy metals were evaluated by methods of single quality index and complex quality index.Results showed that the average contents of heavy metals in vegetable soils of Laiyang,garlic soils of Jinxiang and scallion soils of Zhangqiu were all under the limit values prescribed byFarmland environmental quality evaluation standards for edible agricultural products(HJ 332—2006).The heavy metal contents varied greatly among different sites.The coefficients of variation(C.V.)of the studied eight heavy metals were among 10 % and 60% in Laiyang,among 20% and 120% in Jinxiang,and among 12% and 51% in Zhangqiu.The single quality indices of the eight elements in the studied three places were all lower than or equal to 0.7.The comprehensive quality index of the eight elements was 0.56 in Laiyang,0.50 in Jinxiang,and 0.43 in Zhangqiu.The soil environmental quality in the studied three places were all set at the first class belonging to clean level and were fit for the plantation of no pollution vegetables.But the contents of heavy metals in some areas were beyond the limit values,and the beyond rate of Cu in Laiyang was 13.64 %,the beyond rate of Cd,Cu and Hg in Jinxiang was 5.41%,5.41% and 2.70% respectively,the beyond rate of Ni in Zhangqiu was 4.76%.Most of the heavy metals were positively correlated in contents,and the correlation of Cd and Zn,Cu and Zn,Pb and Cr reached a very significant level(P0.01),while the correlation of As and Ni,Ni and Zn,Zn and Pb,Pb and Cu,Cu and Cr reached a significant level(P0.05).Contents of most of the tested heavy metals were higher than natural background value of agricultural soils in Shandong Province,which indicated that metals were accumulated in the studied soils.Compared with the natural background values,the soil Cu content in Laiyang increased nearly 2 times,and the soil Hg content increased nearly 4 and 3 times in Jinxiang and Zhangqiu respectively.Investigation on other farmlands of vegetables cultivated in open field of Shandong Province showed that the soils were not contaminated by heavy metals.