Soil Improvement And Risk Assessment Of Heavy Metal Pollution In Vegetables Planted In Qingshuitang Industrial Zone,Zhuzhou

Qingshuitang District of Zhuzhou City is one of the typical soil heavy metal pollution areas in Hunan Province.Heavy metals in soil can migrate into human body through food chain such as vegetables.Vegetables are essential food in people's daily life.Once polluted by heavy metals,they will directly affect human health.Therefore,we can take two measures.Because there are many people and few land in our country,we can't stop farming in the soil polluted by heavy metals.Therefore,in order to avoid the harm of heavy metals in vegetables to human body,we can select the vegetables with low accumulation of heavy metals for planting.Through different formulas to improve the soil,improve the pH value of the soil,increase the passivation ratio of heavy metals,reduce the effective content of heavy metals in the soil,so as to achieve the purpose of repairing polluted soil and reducing the content of heavy metals in vegetables.This paper studies these two aspects.The vegetable planting soil of Daijiachong village and Zhusipo village near Qingshuitang Industrial Park in Zhuzhou City is acid soil.The content of Pb,Cd and Hg in the soil of the two villages is significantly higher than the national limit value(P<0.05),but the content of As does not exceed the standard.The vegetables planted in the two villages have been polluted to different degrees,among which the pollution degree in Daijiachong village is more serious than that in Zhusipo village.Among the 11 varieties of three kinds of vegetables,the order from high to low is Cd>Hg>Pb>As.The average comprehensive pollution index of leafy vegetables,rhizome vegetables and eggplant and fruit vegetables in daijiachong village and zhusipo village were 1.388,1.379 and 1.006,respectively.That is to say,the pollution indexes of the three kinds of vegetables are:leafy vegetables>root vegetables>melon vegetables.Regular consumption of heavy metal contaminated vegetables may cause harm to human health,which has potential health risks.Only melon vegetables can be planted in this kind of soil,and other vegetables are not suitable.The contaminated soil was repaired with 5 formulas.Except formula 3,the other four treatments can promote the growth of vegetables and increase the yield of vegetables.The contents of as,Pb,Cd and Hg in all the vegetables(cabbage,carrot,pepper)were in line with the national requirements and reached the safety standards.The five formulas can significantly improve the acidified soil,especially after one crop of vegetable planting,the soil becomes more neutral,and the available content of heavy metals in the soil further decreases.The comprehensive pollution indexes of pakchoi,carrot and capsicum planted after soil improvement were 0.90,1.02 and 0.69,respectively.Compared with that before soil improvement,the safety level of pakchoi,carrot and capsicum was significantly improved.As in vegetables of children and adults,the daily intake of heavy metals per unit weight add is higher than the international allowable intake dose RFD(P<0.05),which may have potential health risks to human body.The ADD values of Pb and Hg in vegetables of children and adults were significantly lower than that of RFD(P<0.05).The harm index HI of heavy metals in vegetables grown in different improved formula was significantly higher than that of adults(P<0.05).