Purpose Previous studies show that application ofbiochar can reduce the bioavailability of heavy metals in soil.A plant growth experiment was carried out to evaluate the effect of tobacco stalk-and dead pig-derived biochars on the extractability and redistribution of cadmium(Cd)and zinc(Zn)in contaminated soil,and the impact on tobacco(NicotianatabacumL.)plant growth.Materials and methods The top 20 cm of a soil contaminated with Cd and Zn was used in this study.Biochars derived from tobacco stalk and dead pig were applied to the soil at four application rates(0,1%,2.5%and 5%)and tobacco plants were grown.After 80-days growth,the pH,electrical conductivity,CaCl2-extractable heavy metals and fractions of heavy metals in soil samples,as well as the plant biomass and the concentrations of heavy metals in the plant were determined.Results and discussionThe plant growth experiment demonstrated that tobacco stalk biochar and dead pig biochar significantly(P< 0.05)increased the pH,but had no significant effect on the electrical conductivity of the soil.The CaCl2-extractable Cd and Zn content decreased as the application rates increased.The concentration of extractable Cd and Zn decreased by 64.2%and 94.9%,respectively,for the tobacco stalk biochar treatment,and 45.8%and 61.8%,respectively,for the dead pig biochar treatment at 5%application rate.After biochar addition,the exchangeable Cd was mainly transformed to fractions bound to carbonates and Fe-Mn oxides,while the Zn was immobilized mainly in the fraction bound to Fe-Mn oxides.Tobacco stalk biochar increased the tobacco plant biomass by 30.3%and 36.2%for shoot and root,respectively at the 5%application rate.Dead pig biochar increased the tobacco plant biomass by 43.5%and 40.9%for shoot and root,respectively at the 2.5%application rate.Both biochars significantly(P< 0.05)decreased the Cd and Zn accumulation by tobacco plant.ConclusionsAs a soil amendment,tobacco stalk biochar was more effective at removing Cd,whereas dead pig biochar was more effective at removing Zn,and a higher application rate was more effective than a lower application rate.Overall,biochar derived from tobacco stalk was more effective,than dead pig biochar,at remediating soil contaminated with Cd and Zn,as well as promoting tobacco growth.
Bioavailability Biochar Immobilization Metal uptake Soil contamination
Xing Yang Kouping Lu Kim McGrouther Lei Che Guotao Hu Qiuyue Wang Xingyuan Liu Leilei Shen Huagang Huang Zhengqian Ye Hailong Wang
Yancao Production Technology Center,BijieYancao Company of Guizhou Province,Bijie,Guizhou 551700,Chi Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province,Zhejiang A & F University,L Scion,Private Bag 3020,Rotorua 3046,New Zealan School of Engineering,HuzhouUniversity,Huzhou,Zhejiang 313000,China Guangdong Dazhong Agriculture Science Co.Ltd.,Hongmei Town,Dongguan,Guangdong 523169,China Ningbo Bureau of Animal Husbandry and Veterinary,Ningbo,Zhejiang 315012,China Yancao Production Technology Center,BijieYancao Company of Guizhou Province,Bijie,Guizhou 551700,Chi Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province,Zhejiang A & F University,L