Cadmium(Cd)is a toxic trace metal that occurs naturally in agricultural soils and can accumulate in the edible parts of crops,notably in cereal grains.This study investigated the extent to which sulfur(S)fertilization...Cadmium(Cd)is a toxic trace metal that occurs naturally in agricultural soils and can accumulate in the edible parts of crops,notably in cereal grains.This study investigated the extent to which sulfur(S)fertilization increases the availability of Cd in a calcareous(Calc)and a non-calcareous(Ncalc)soil.Changes in Cd availability and speciation were monitored over a 21-d incubation period,along with changes in pH and the concentrations of sulfate,nitrate,calcium,magnesium,aluminum(Al),manganese(Mn),and nickel(Ni)in the potassium nitrate(KNO_(3))extracts,after the addition at agronomic rates of three forms of S fertilizers:elemental S(S(0)),potassium sulfate(K_(2)SO_(4)),and ammonium sulfate((NH_(4))_(2)SO_(4)).Elemental S did not increase the Cd concentration in the KNO_(3)extracts of either soil due to its too limited oxidation to sulfates.The two sulfate fertilizers had contrasting effects on Cd concentration depending on the nature of the counter cation(K^(+)or NH_(4)^(+)).While K_(2)SO_(4)caused almost no change in Cd concentration in either soil,(NH_(4))_(2)SO_(4)increased Cd concentration in both soils.The nitrification of NH_(4)^(+)reduced soil pH,thereby increasing the concentrations of Cd,Al,Mn,and Ni in the Ncalc soil over time,as evidenced by the strong negative correlations between soil pH and the concentrations of these four elements in the KNO3 extract after 21 d.In the Calc soil,the mechanism of Cd concentration increase after(NH_(4))_(2)SO_(4)addition was more difficult to understand and could result from the proton-mediated alteration of Cd-bearing phases such as carbonates,following ammonia(NH_(3))volatilization.The relevance of these results for the S fertilization of cereals in Cd-contaminated soils is discussed.展开更多
基金supported by the CNRS-INSU EC2CO program in the framework of the CADSOU project,by the Nouvelle Aquitaine Region in the framework of the ESTOCADE project,and by the French National Research Institute for Agriculture,Food and Environment(INRAE)The authors are grateful to Ms.Melike Emet(INRAE,UMR ISPA)and Ms.Sylvie Bussière(INRAE,UMR ISPA)for their help treating the samples,and to Ms.Francesca Degan(ARVALIS-Institut du végétal)and Ms.Séverine Piutti(INRAE,UMR LAE)for helpful comments.
文摘Cadmium(Cd)is a toxic trace metal that occurs naturally in agricultural soils and can accumulate in the edible parts of crops,notably in cereal grains.This study investigated the extent to which sulfur(S)fertilization increases the availability of Cd in a calcareous(Calc)and a non-calcareous(Ncalc)soil.Changes in Cd availability and speciation were monitored over a 21-d incubation period,along with changes in pH and the concentrations of sulfate,nitrate,calcium,magnesium,aluminum(Al),manganese(Mn),and nickel(Ni)in the potassium nitrate(KNO_(3))extracts,after the addition at agronomic rates of three forms of S fertilizers:elemental S(S(0)),potassium sulfate(K_(2)SO_(4)),and ammonium sulfate((NH_(4))_(2)SO_(4)).Elemental S did not increase the Cd concentration in the KNO_(3)extracts of either soil due to its too limited oxidation to sulfates.The two sulfate fertilizers had contrasting effects on Cd concentration depending on the nature of the counter cation(K^(+)or NH_(4)^(+)).While K_(2)SO_(4)caused almost no change in Cd concentration in either soil,(NH_(4))_(2)SO_(4)increased Cd concentration in both soils.The nitrification of NH_(4)^(+)reduced soil pH,thereby increasing the concentrations of Cd,Al,Mn,and Ni in the Ncalc soil over time,as evidenced by the strong negative correlations between soil pH and the concentrations of these four elements in the KNO3 extract after 21 d.In the Calc soil,the mechanism of Cd concentration increase after(NH_(4))_(2)SO_(4)addition was more difficult to understand and could result from the proton-mediated alteration of Cd-bearing phases such as carbonates,following ammonia(NH_(3))volatilization.The relevance of these results for the S fertilization of cereals in Cd-contaminated soils is discussed.
