| Mining and smelting have become very active in order to meet the needs of industries around the world;however,those activities release a lot of toxic substances such as heavy metals to the environment.These exposures are the focus of many researchers around the world.Considering all aspects,this research carried out a preliminary survey on the analysis of twelve heavy metals in 91 samples of agricultural soil,5 different agricultural products(potato,Chinese cabbage,garlic bolt,corn,hairy vetch),8 samples of drinking water and human body(68 samples of scalp hair and 66 samples of urine)near mining(Pb-Zn mine ore)and smelting areas of Hezhang,China.The main objective is to assess the concentration,characteristics and distribution of heavy metals,using modified BCR-SEPs to interpret the mobility,dynamics,reveal the migration and risk assessment of studied metals;to investigate the relationship between the fraction of heavy metals in agricultural soils and the potential health risks on residents exposed to heavy metals in the vicinity of the old lead zinc smelting areas,mountain area(considered as control area)and active mining area.Our research content and results are presented as follows:The concentrations of Pb,Sb,Zn,Hg,Bi,As,and Cu in soil and plant are very high,especially in mining area among Pb(15245.10 mg kg-1),Sb(327.03 mg kg-1)and Zn(9003.73 mg kg-1)in soil which exceed the background value of soil.The concentrations of heavy metals in plant samples in the mountain area and villages affected by mining and smelting diverse by sites and species,and the concentrations were significantly superior to legislation limits.Compared to other study areas Bi,Hg,Sb,and Zn concentrations in the plant samples from near the mining area were higher,and the As,Co,and Cu concentrations were also higher in the plant samples from the smelting areas.However,the other metals also displayed diverse concentrations with different sampling locations and different kind of plants.Multivariate statistical analysis indicated that in the mining area,the production of As,Bi,Cd,Cu,Hg,Pb,Sb,and Zn belong to the anthropogenic sources;in smelting area,As,Be,Cd,Co,Cu,Pb,Sb,and Zn are produced by the zinc smelting which stopped in 2004.The other heavy metals are mainly belonging to natural sources.According to spatial distribution,the concentrations depend on the nearby mining and smelting activities.The chemical speciations of heavy metals in soil are relatively higher than in the residue,especially in the research field of Cu and Cr.The Co element was the highest percentage in acid secondary-phase.However,some elements such as Zn in mining area and As,Co in both smelting and mountainous areas are relatively higher in acid soluble fraction(F1).Tucker 3 results showed As,Cd,Cu,Zn,mainly from mining and smelting activities,mining areas was particularly obvious,essentially in residual fraction.The enrichment factors(EFs)and ecological risk index(RI)of soil in mining area are recorded the most harmful,which shows the high enrichment and very high ecological risk for As,Bi,Cd,Cu,Hg,Pb,Sb,and Zn.Transfer factors(TFs)in the smelting and mountainous areas are high,implying a threat to human consumption.Compared to previous studies conducted in China and other western countries,the concentration levels of Be,Bi,Co,Cr,Ni,Sb,and Pb in the human hair and urine of the smelting and mining areas are higher.Besides,most heavy metals in hair and urine were higher in mining and smelting areas respectively.Considering gender differences,the content of heavy metals in hair and urine of females were more likely than male to expose to heavy metals.According to age's similarities,higher values of male's hair were in range of 18-40;in urine>66 in mining and smelting areas.However,female's most higher value in hair from mining area was 41-65 and in smelting was 18-40,and urine in smelting was in 6-18 and mining area was in>66.Vegetables showed the highest contribution in the average daily intake of heavy metals compared to soil and water.In fact,Hazards Index(HI)is higher in vegetables and soil.Considering carcinogenic risk(R)of total metals values in vegetable(2.09E-01;4.40E-01)and soil(1.11E-03;2.73E-03)in smelting and mining areas respectively,these values will give local people a higher potential risk of cancer. |
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