The Study Of Contents And Distribution Of Heavy Metals In Soils From One Vegetable Base

Health Soil environment is the major premise of agricultural production,one town area is mainly engaged in agricultural production,such as traditional farming and green leafy vegetables planting.it is the city's largest vegetable production base.Respectively In 2005 and 2014,according to different types of soil,64 points were stationed and sampled at the 15 villages in the town,the main cause of soil heavy metal pollution,namely,8 kinds of pollutions: Zn,Cu,Cr,Cd,Pb,Ni,Hg and As at the 15 villages in the town were analyzed,sequentially the degree and sources of pollution were discussed.According to the data on the analysis of the samples,the conclusions were as follows:1.In 2005,total Hg,total Cr,total As,total Pb,total Zn and DDT content of the soil in five villages all reach the standard,and benzenes are not detected;total Cu content in two villages reach the standard,average content exceed 0.0188,the highest content exceed 0.282.2.In 2014,total Cr,total Hg,total As and DDT content of the soil in five villages are all up to standard;Only in three villages the benzenes are detected;over-limit ratio of the total cadmium content in the soil was 100%,the average content exceed 1.08,the highest content exceed 2.37;over-limit ratio of the total Cu content was 40%,the average content exceed o 0.0322,the highest exceed 0.752;over-limit ratio of the total zinc content is 60%,the average content exceed 0.465,the highest content exceed 1.61.3.Over the decade from 2005 to 2014,in the five villages,eight monitoring projects including total mercury,total cadmium,total chromium,total arsenic,total plumbum,total copper,total zinc and benzenes in addition to the DDT,increased at different degree.compared with 2005,the result of five villages comprehensive pollution index of soil monitoring increased at large degree.In 2005,comprehensive pollution index of soil in five villages were in standard line,but in 2014,comprehensive pollution index of soil B village has been as high as 2.484,was moderate pollution,and crops are contaminated;Soil comprehensive pollution index in A village reached 1.856,soil comprehensive pollution index in C village reached 1.426,soil comprehensive pollution index in E village is up to 1.896,were moderate pollution,crops began to be contaminated;Only D village soil is still in standard line,but soil comprehensive pollution index is 0.824,also reached the warning line.4.The contamination situation of different heavy metals in different metals in 2014: The contents of benzex?As?Pb?Cr?Ni were no more than the corresponding standards.Only one point location in the paddy field exceeded standard;The rate of exceeding standard of Cu: Dry land 100%> Farming land 45.5%> Residential land 18.8%> Inland plains 16.7%> paddy field 4.55%;The rate of exceeding standard of Zn: Irrigable land100%= Dry land100%= Grassland100%>Paddy field68.18%> Inland plains50%= Forest land50%>Farming land45.5%> Residential land37.5%;The rate of exceeding standard of Cd: Irrigable land100%= Inland plains100%= Dry land100%= Forest land100%> Farming land81.81%> paddy field77.3%> Grassland66.7%> residential land54.5%.5.According to the collection of 8 different types of 64 soils: 1 point soil suffered severe pollution,accounting for 1.57% of the total points digits;Moderate pollution point number 5,accounting for 7.81% of the total points digits.Light pollution point number 37,accounting for 57.8% of the total points digits.6.Livestock farming,aquaculture,factory application of crop cultivation,the use of pesticides,chemical fertilizers,the generation of living garbage and stacked,irrigation water from industrial waste water pollution,the traffic in and out,a large amount of industrial waste gas emissions,is the major source of the pollution.