| Heavy metals pollution affects the normal growth and physiological and metabolic activities of organisms in the environment system,and even threatens its life.It has become an important troubling pollution problem.Study on heavy metals pollution in soil and cherry system can not only provide scientific and effective evaluation for orchard soil and fruits and vegetable health,but also provide systematic and scientific guidance for soil management and restoration,and provide effective guarantee for food safety.In this study,7 heavy metals,Pb,Zn,Cu,Cd,Cr,As and Hg in the system of soil and cherry,from two large cherry planting bases in Guanzhong Area,were determined.The thesis was carried out from the following aspects,pollution characteristic,pollution assessment,pollution source and enrichment characteristic.The paper tried to analysis the concentrations characteristics of heavy metals in soil and cherry.Several assessment methods were used to evaluate the heavy metals in soil and cherry.The pollution sources of heavy metals in soil were analyzed.The enrichment of heavy metals in the system of soil and cherry was analyzed.The following conclusions were summarized.(1)From the concentrations of heavy metals in soil,the mean concentrations of Pb,Zn,Cu,Cd,Cr,As,Hg in soil of Dizhai Village were 31.09 mg/kg,80.51 mg/kg,26.75 mg/kg,2.38 mg/kg,81.38 mg/kg,9.15 mg/kg,0.05 mg/kg,respectively.The mean concentrations of heavy metals in soil of Jinxing Village were 34.50 mg/kg,74.33 mg/kg,25.69 mg/kg,5.77 mg/kg,83.25 mg/kg,12.18 mg/kg,0.06 mg/kg.The mean concentrations of heavy metals in soil of Hounian Village were 22.84 mg/kg,67.24 mg/kg,23.75 mg/kg,6.65 mg/kg,67.66 mg/kg,14.01 mg/kg,0.03 mg/kg.The mean concentrations of heavy metals in soil of three villages were mostly higher than the soil background values of Shaanxi Province except Cu.The results of one-way ANOVA of heavy metals in soil showed that the differences of the concentrations of Pb,Zn,Cd and Cr were extremely remarkable among the three villages,while Cu、As、Hg were not significant.(2)According to results of pollution assessment,the Nemero comprehensive pollution index of heavy metals in soil of Dizhai Village,Jinxing Village and Hounian Village were 1.696.6.888,7.935.respectively,more than 1,exceeding the vigilance,indicating that the soil was polluted to varying degrees.Combined with the single(actor pollution index,it was concluded that the pollution of heavy metals in soil was caused by the single pollution of Cd.The geoaccumulation index of Cd in soil of Dizhai Village,Jinxing Village and Hounian Village were 3.738,5.417 and 5.622,respectively,reffered to severe pollution,serious pollution and serious pollution.Zn,Cu,As showed no pollution.Only the soil of Jinxing Village was slightly polluted by Pb and Cr.the soil of Dizhai Village and Jinxing Village were slightly polluted by Hg while Hounian Village not polluted.The total ecological risk index of Dizhai Village,Jinxing Village and Hounian Village were 549.574,2032.279.417,2275.033,respectively.Dizhai Village was severe pollution and Jinxing Village and Hounian Village were serious pollution.The single ecological risk index showed that the three villages had obvious Cd pollution and all reached serious pollution.The results of health risk assessment showed that the health risk factors were 0.135,0.165 and 0.160,respectively,indicating that heavy metals in soil would not produce non-carcinogenic health risks to the human body.(3)The heavy metals in soil of Dizhai Village could be divided into three sources:Cu,Cd,Zn and Cr come from the same source,which might come from fertilizer of agricultural pollution.Pb was from traffic pollution of roads.As and Hg probaly were natural sources.The heavy metals in soil of Jinxing Village could be divided into two sources:Pb,Zn,Cu,Cd,Cr,As and Hg were presumed to come from natural source,the concentrations of Cd were high in soil,and obviously polluted by external pollution,so probably polluted by agricultural fertilizer.The heavy metals in soil of Hounian Village could be divided into two sources:As and Hg might come from natural process.Pb,Zn,Cu,Cd,Cr and were common agricultural fertilizer pollution.(4)From the concentrations of heavy metals in cherry,the mean concentrations of Pb,Zn,Cu,Cd,Cr,As,Hg in cherry of Dizhai Village were 3.24 mg/kg,6.88 mg/kg,1.99 mg/kg,0.51 mg/kg,7.98 mg/kg,0.13 mg/kg,0.007 mg/kg,respectively.The mean concentrations of heavy metals in cherry of Jinxing Village were 3.10 mg/kg,5.95 mg/kg,3.24 mg/kg,0.41 mg/kg,7.25 mg/kg,0.11 mg/kg,0.004 mg/kg.The mean concentrations of heavy metals in cherny of Hounian Village were 4.46 mg/kg 7.19 mg/kg,4.29 mg/kg,0.18 mg/kg,6.73 mg/kg,0.17 mg/kg,0.001 mg/kg.The mean concentrations of heavy metals in cherry of three villages were mostly higher than the national standard of fruit limit except Cu.The results of one-way ANOVA of heavy metals in cherry showed that the differences of the concentrations of Cu and Hg were extremely remarkable among the three villages and As was significant,while Pb,Zn,Cd and Cr were not significant.(5)According to results of pollution assessment,the comprehensive pollution indexes of Dizhai Village,Jinxing Village and Hounian Village were 23.759,22.694 and 32.238 respectively,belonged to severe pollution.Combined with the single factor pollution index,the pollution index of the three villages was caused by heavy metals of Pb,Cd and Cr,especially was Pb.The results of health risk assessment showed,the total target risk coefficients of Dizhai Village,Jingxing Village and Hounian Village were 0.403,0.355 and 0.429,less than 1,so would not pose any health risk to human body.(6)Different heavy metals showed different enrichment abilities in the system of soil and cherry The descending order of enrichment of heavy metals in Dizhai Village was Cd>Hg>Pb>Cr>Zn>Cu>As.The descending order of enrichment of heavy metals in Jingxing Village was Cu>Pb>Cr>Zn>Cd>Hg>As.The descending order of enrichment of heavy metals in Hounian Village was Pb>Cu>Zn>Cr>Hg>Cd>As.Generally speaking,heavy metal Cd had strong accumulation ability due to its strong chemical activity.Cu and Zn,as the essential trace elements for growth of plant,had strong enrichment ability.Pb also showed strong enrichment capacity.From the correlation analysis of the concentrations of heavy metals between cherry and soil,there were certain correlations of Cr,As between cherry and soil of Dizhai Village,and there were certain correlations of Pb,Zn,Cd,As between cherry and soil of Jingxing Village,while only Cd in Hounian Village.On the whole,the correlation of heavy metals between soil and cherry was not significant,speculated related to heavy metals’ ability of migration,transformation and accumulation in the system of soil cherry.Combined with enrichment of heavy metals,enrichment ability of heavy metal is low on the whole. |
