Effects Of Cd,Pb And Cr Concentrations In Soil On The Concentrations Of Cd,Pb And Cr In Tobacco Roots And Leaves

With the rapid development of economy and society,heavy metal pollution has become increasingly serious.Tobacco(Nicotiana tabacum L.)is an important economic crop,occupying an important position in China's national economy.As people focus on smoking and health,the security of tobacco was received more and more attention.Therefore,reducing heavy metal pollution in tobacco has become the key to improving the quality of tobacco safe.Cd,Pb and Cr is the common contaminant in soil,in order to study different concentrations of Cd,Pb and Cr in soil impact on the concentrations of Cd,Pb and Cr in tobacco roots and tobacco leaves,pot method was adopted in this experiment.Inductively coupled plasma(ICP-MS),Tessier sequential extraction of heavy metals in soil and other methods were adopted to study different concentrations of Cd,Pb and Cr in soil impacts on the concentrations of Cd,Pb and Cr in tobacco roots and leaves,and the correlation between different forms of Cd,Pb and Cr and the concentration of roots and leaves of tobacco.The results were as follows:1.Different concentrations of Cd,Pb and Cr in soil effects on the concentration ofCd,Pb and Cr in tobacco roots and leaves.Cd concentrations of tobacco in roots and the lower,middle,upper parts in leaves were increased as the concentration of Cd pollution concentrations.Cd concentrations in roots and leaves of the order is:lower leaves>middle leaves>upper leaves>root.Cd uptaked in tobacco only a small amount accumulated in the roots,but the majority were transportd to leaves.The difference of Cd concentration s in lower,middle and upper parts of tobacco leaves was not significant,indicating that the strong transfer capability of Cd in tobacco.When the Cd concentrations in soil<0.4 mg/kg,Cd concentrations of the production of tobacco leaves may be safer.When the Cd concentration in soil exceeds 0.4 mg/kg,Cd concentrations of the lower and middle parts of tobacco leaves will exceed the legal cigarette market in the maximum amount of Cd concentrations(0.87 mg/kg).And it may create a security risk.When the Cd concentration in soil exceeds 0.8 mg/kg,the Cd concentration of the upper leaves may create a security risk.With the increased of Pb concentrations,Pb concentrations of tobacco roots and the lower,middle and upper parts of leaves were increased as the concentrations of Pb pollution concentrations,and Pb concentrations in the roots and leaves of the order is:roots>lower leaves>middle leaves>upper leaves.Pb absorbed mostly concentrated in the roots,and the differences of the lower,middle and upper parts of tobacco leaves of Pb concentrations were not significant,indicating that the transfer capability of Pb was not strong.When the Pb concentrations in soil<300 mg/kg,Pb concentrations of the production of tobacco leaves may be safer.When the Pb concentrations in soil exceeding 300 mg/kg,the lower leaves of Pb concentration exceeded the legal cigarette market in the maximum amount of Pb(5.79 mg/kg).And it may create a security risk.With the increased of Cr concentrations in soil,Cr concentrations of tobacco roots and the lower,middle and upper parts of leaves were increased as the concentration of Cr contaminations increased,and Cr concentrations in the roots and leaves of the order is:root>the lower leaves>middle leaves>upper leaves.Cr absorbed mostly concentrated in the roots,and differences of the Cr concentrations of leaves on the parts of the lower,middle,upper was not significant.When the Cr concentration in soil<300 mg/kg,Cr concentrations of the production of tobacco leaves may be safer.2.Cd,Pb and Cr concentrations and their chemical speciation in soilWith the increased of Cd concentrations in soil,Cd concentrations of different chemical speciations were increased with the increased of Cd pollution.But there was no significant relationship between the different forms and concentrations of Cd.At different concentrations of Cd,Residual state as the main chemical speciation,followed by exchangeable and Fe-Mn oxide bound,carbonate bound again,and organic bound Cd account for the least partition coefficient.And when the soil were applied to 0.4?0.8 mg/kg Cd,Cd concentrations of the exchangeable and carbonate increased significantly compared with the control state.This leads to the more serious Cd pollution of tobacco leaves with increased Cd concentrations.With the increased of the Pb concentrations in soil,different chemical speciations of Pb concentrations increased.No significant relationship between share a variety of chemical speciations of Pb distribution coefficient and concentration.Pb treatments at different concentrations are based on the maximum residual share of the distribution coefficient,followed by organic bound,and the third for the Fe-Mn oxide fraction,the fourth of carbonate,exchangeable share Pb the distribution coefficient minimum.And when applied into the soil to 200 mg/kg Pb,Pb concentrations of exchangeable and carbonate were significantly increased compared with the control state.It's leads to the increase of Pb concentration in tobacco leaves.As applied Cr concentrations to soil increased,concentrations of different chemical forms increased.But there is no obvious relationship between the various chemical forms of Cr share distribution coefficient and concentration.Cr treatments at different concentrations are based on the maximum residual share of the distribution coefficient,followed by the organic fraction,and the third for the Fe-Mn oxides and carbonate bound,exchangeable share of the distribution coefficient Cr at least,less than 2%.When applied Cr concentrations into the soil to 200 mg/kg,exchangeable Cr concentrations compared with the control significantly increased.When applied Cr concentrations into the soil to ? 300mg/kg,carbonate-bound compared with the control Cr concentrations significantly increased.This leads to the increase of Cr concentration in tobacco leaves.3.Correlation analysis between concentrations of different chemical forms of Cd,Pband Cr in soil and Cd,Pb and Cr concentrations in tobacco roots and leavesCd concentrations of exchangeable,carbonate and residual Cd concentrations in soil were significantly and positively correlated with tobacco roots and lower leaves,middle leaves,upper leaves;Fe-Mn oxide bound Cd concentrations are associated with tobacco roots and lower leaves,upper leaves very significant concentrations of Cd,a significant positive correlation with Cd concentrations in middle leaves;Organic bound Cd and lower leaf tobacco roots and middle leaves,upper leaves of Cd concentrations correlation is not significant.Exchangeable,carbonate,Fe-Mn oxides,organic matter bound and residual Pb concentrations in soil and Pb concentrations of tobacco roots and lower,middle and upper parts of tobacco leaves were significantly and positively correlated;Exchangeable,carbonate,organic matter bound and residual Cr concentrations and tobacco roots and lower,middle and upper parts of tobacco in each Cr concentrations were significantly and positively correlated;Organic bound Cr concentrations and tobacco roots and lower,middle and upper parts of tobacco in each Cr concentrations were not significantly correlated.Organic bound Cr concentrations and tobacco roots and lower,middle and upper parts of tobacco leaves in each Cr concentrations were not significantly correlated.