Pollution Characteristics And Treatment Of Heavy Metal In Soils Around Topical Industrial Area,Xinxiang City

This paper initially through field investigation and indoor chemical analysis to investigate thedistribution characteristics and evaluation of Pb,Cd,Ni,Zn,Cu and Cr in soil and ground around HuanyuAvenue industrival area，and the chemical speciation of Cd,Niand Zn were analyzed by using Tessiersequential extraction procedure.The results showed that the contents of the heavy metals were63.08mg kg^-1，176.85mg kg^-1,307.2mg kg^-1,485.6mg kg^-1,38.7mg kg^-1and47.9mg kg^-1,and they were about176.85、5.12and1.62times of the value for target elements in the National Environmental Quality Standardfor soils, respectively. The concentration of Pb、Cu and Cr in soil were less than the normalized value.Thegreatest proportion of Ni and Zn were the Fe-Mn oxide fraction and residual fraction. The greatestproportion of Cd was the Fe-Mn oxide fraction and secondly is the carbonates fraction. The sequence of theheavy metal mobility was Cd> Zn> Ni. Every henvy metal had its potential ecological hazards. Thepotential ecological hazards of Cd is the highest, and it caused great ecological hazard in soils.Second,based on the investigation of the contents of heavy metals in soils and wheat grains and thesoil enzyme activites,analyse the correlation between heavy metals in soils and wheat grains,betweenheavy metal contents and enzymatic activities of soils,and use single factor soil pollution index and thepotential ecological hazards index for contamination assessment. The results showed that the contents ofthe heavy metals Zn and Cd were638.54mg kg^-1，19.45mg kg^-1,and they were about2.13and31.83times of the value for target elements in the Nationa Environmental Quality Standard for soils,respectively.The content of Cd、Ni and Cr in wheat grains exceed the food hygiene standards,whichindicated that the accumulation of Zn and Cd were higer.The canonical correlation analysis indicatedthat:the heavy metal content in wheat grains derived mainly from the heavy metal in soils,the ureaseactivity correlated closely with the content of Zn in soils, the catalase and invertase activity correlatedclosely with the content of Ni in soils.The paper evaluate the risk of the soils used the single andcomprehensive index methods and the method of potential ecological risk index.The results showed that Cdwas the main ecological risk factors in soils and the degree of the ecological risk was serious while the risksof other heavy metals. Third,taking soils in a newly constructed industry zone in Xinxiang as samples,the content of soilheavy metal Pb、Ni、Zn、Cr and Cu were determinated by atomic absorption spectrophotometer.Theecological risk assessment of heavy metal pollution in the industrial soils were discussed with the methodsof geoaccumulation index and potential ecological hazard index.The results showed that the soils werelightly polluted by Ni and Zn.Based on the of Henan soils,they were1.43and3.07times of the backgroundvalue.The results of the evaluation showed that the degree of ecological hazard is at a light level.A pot experiment was conducted to investigate the growing responses and accumulating charcteristicsof three omamental plants with different contents of heavy metal Cd in north Henan.The plants were treatedwith Cd(10,20,50,100,200mg·kg^-1).The results showed that Ricinus communis and Marigold grew welland did not showed evident toxic symptoms.The Huaping grass grew more slowly and the leaves turnedyellow gradually when the Cd concentrations were200mg·kg^-1.With the increasing Cd concentration,theaccumulation of Cd in plants were higer.The accumulation mobility decreased with increasing Cdconcentration in the soil. The accumulation mobility was Ricinus communis>Marigold> Huapinggrass.The uptake and accumulation of Cd concentration in roots was much higher than in stems andleaves,which related to the strong root system.The peaked accumulation in root of Ricinus communis was1046.78mg·kg^-1, Marigold was189.7mg·kg^-1. Ricinus communis and Marigold had higher tolerance andaccumulation to Cd,thus having a great application potential to phytoremediation of soil environment by Cdpollution.