Accumulative Heavy Metal Features of Soil and Potential Ecological Risk Assessment on Vegetable Base in Tianmen City

Putting the soil of five vegetable bases in Tianmen city as the research object,the content and accumulation characteristics of heavy metals in soil were studied,and the source of the pollutants was analyzed,and then an assessment on potential ecological harm of heavy metals in soil with the method of potential ecological harm index put forward by Hakanson was made.The results showed that the average contents of heavy metal Hg,Cd,As,Cr,Pb,Cu in the soil of the five vegetable bases were 0.066,0.168,6.850,67.940,10.730 and 27.090 mg / kg respectively,which were lower than the national standard Ⅱ soil environmental quality level,but the average contents of Hg,Cd,Cr,Cu in different bases were higher than soil background values of Hubei,presenting a clear cumulative phenomenon,and heavy metal comprehensive accumulation level in soil was mild.The main pollution sources of heavy metals were heavy metal settlement in the atmosphere,chemical fertilizers,pesticides,poultry,animal feces,living garbage containing heavy metals and plastic sheet ing residual film;the results of potential ecological harm index showed that potential ecological harm degree of heavy metals in the soil was at a slight ecological harm state,Hg and Cd were the main ecological harm factors in soil.