Effects Of Different Passivation On Adsorption And Activity Of Heavy Metal In Soil Simulated Fertilization With Livestock Manure

With the development of poultry breeding and increasing of heavy metal such asCu and Zn additive amount in feed, heavy metals in animal manures have become theconsidering resource of heavy metals in agricultural soils in China by the fertilizationof livestock and poultry manure. Consequently, there will be of the significance tostudy the form distribution of heavy metals in livestock and poultry manures and soils(dark brown forest soil from Liaoheyuan) simulated fertilization by livestock andpoultry manures as well as the effects of different passivation agents (sepiolite,bentonite, desulfurization gypsum and fly ash) on the activity of heavy metals in soilsunder simulated fertilization by livestock and poultry manures (pig manure) in thepaper.Results from the content of heavy metals in different types of livestock andpoultry manure showed that the contents of Cu and Zn demonstrate the same order：pig manure> chicken manure> cow manure, and the contents in the livestock manureare all Zn> Cu; results from the distribution of heavy metals in different types oflivestock and poultry manure showed that the distribution of Cu were organic>residual≈Fe-Mn oxides> carbonate≈exchangeable for chicken manure and pigmanure and residual> organic> Fe-Mn oxides> carbonate≈exchangeable for cowdung, the amount of organic and residual accounted for nearly60%in the total Cu ofchicken manure and pig manure and nearly90%in the cow dung. Obviously, theproportion of carbonate and exchangeable (as the active forms) accounted for the totalCu was very low in the chicken manure and pig manure. The distribution of Zn for thethree kinds of livestock and poultry manure were residual>>organic>>Fe-Mn oxides>carbonate≈exchangeable, the amount of organic and residual accounted for morethan90%and that of carbonate and exchangeable (as the active forms) only less than10%in the total Zn for the three kinds of livestock and poultry manure.Results from the activity and distribution of Cu and Zn in the soils underdifferent processing conditions showed that the activity of Cu and Zn increased for thesoils with lower contents of Cu and Zn and decreased for that with higher contents of Cu and Zn (the fraction of the exchangeable increased and that of the carbonatedecreased) under simulated fertilization by livestock and poultry manures. Thedistribution of Cu and Zn in the soils treaded with different proportions and kinds ofpassivation agents were all the same followed as the order of residual>> organic>Fe-Mn oxides> carbonate> exchangeable. Nevertheless, the effects of different kindsof passivation agents on the activities of Cu and Zn in soils were significant distinctly,the passivation effects in soils were sepiolite>bentonite>fly ash>desulfurizationgypsum for Cu and bentonite>sepiolite> fly ash>desulfurization gypsum for Zn.Furthermore, the activities of Cu and Zn in soils decreased with increasing addedamount of different passivation agents under simulated fertilization with the livestockand poultry manure (pig manure), and the passivation effects in soils were similar tothat added passiviation agents only, i.e. sepiolite>bentonite>fly ash>desulfurizationgypsum for Cu and bentonite> sepiolite> fly ash>desulfurization gypsum for Zn.Results from the adsorption thermodynamics of Cu and Zn in soils showed thatthe adsorption capacity of Cu and Zn on/in the soils were in the order of cow dung>pig manure> chicken manure under simulated fertilization with livestock and poultrymanures and bentonite> sepiolite> fly ash> desulfurization gypsum under add ingdifferent passiviation agents. Compared with sepiolite and desulfurization gypsum,sepiolite can improve the capacity of adsorption of Cu and Zn on/in the soilssignificantly under simulated fertilization with livestock and poultry manures. Theadsorption thermodynamic characteristics of Cu and Zn on/in the soils undersimulated fertilization with livestock and poultry manures and treated with differentpassivation agents can all be described by Freundlich equation.