Immobilization Of Heavy Metals Contaminated Soil By Tobacco Stem Biochar And Sepiolite Powder For Tobacco Cultivation

In order to assess the feasibility of the tobacco stalk biochar and sepiolite powder composite for tobacco(Nicotiana tabacum L.)cultivation on the heavy metals contaminated soil,the pot experiment was conducted in the Pingshan experimental ground in Zhejiang A & F University in 2016.In the present study,the effects of the biochar and its compound materials to soil ratio(0%,2%,4% and 8%,dw/dw)on soil fertility,the heavy metals bioavailability,the redox enzyme and microbial community structure of the soil and the heavy metals concentration in the tobacco leaves mianstream smoke were studied.The major results are as follows:1.The soil p H value increased significantly after applying the biochar to heavy metals contaminated soil.Organic matter,water soluble organic carbon and available phosphorus had the highest value in the treatment of TB3,which increased by 102.1%,95.5% and 242.6% respectively compared with the control.The content of total phosphorus and alkali hydrolyzable nitrogen in soil reached the most significantly effect on TB2 treatment,and increased by 22.2% and 5.3% respectively compared with the control.The urease,alkaline phosphatase activity was significant increased and synthetic enzyme activity reached the maximum value in the treatment of TB3.The number of bacteria,fungi,bacteria was significantly increased.the biochar could reduced bio-available fration.leaf yield increased by 54.1% compared with the control in TB3,The content value of Cu,Cd,Zn in the leaves were lowest in TB2,compared with the control group were reduced by 18.4%,23.4%,26.5%.2.The soil p H value and soil nutrients were significantly improve after appling biocar-sepiolite mixture in soil.The contents of organic matter and water-soluble organic carbon in the treated TBS3 were significantly higher than control,and the values were 52.2g/kg and 0.3g/kg,respectively.The content of total phosphorus in the treatment of TB3 was significantly increased.The content of available phosphorus was decreased.In TBS2,the effect of remaditor on nitrogen is the best.The urease,alkaline phosphatase activity was increased,however the dehydrogenase activity decreased after applied biocar-sepiolite mixture.The bacteria and fungi community number reached the maximum value in TBS3 and TBS2 respectively,and increased by 4.8 and 2.8 times compared with the control.Actinomycetes reached the maximum at TBS3 treatment.The transformation rate of heavy metals Cu,Cd,Pb and Zn from secondary to primary phase was the highest in TBS3.Tobacco production was increased and the content of heavy metals in tobacco was decreased after applied biocar-sepiolite mixture.The Pb content in the leaves was lowest in the treatment of TBS3,and reduced 5.3% compared with the control.The content of Cu,Cd and Zn was lowest in the treatment of TBS2,which were reduced by 10.9%,14.8% and 17.6% respectively compared with the control.3.Application of the tobacco stalk biochar and the sepiolite composite to the heavy metals contamninated soil could reduce heavy metals concentration in the tobacco leaves mainstream smoke.The contents of Cu,Cd,Pb and Zn in the mainstream smoke was lowest in TBS1,which were reduced by70.5%,66.7%,55.6% and 36.3% respectively compared with the control.