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| Influence of different kinds of biochar on Cd and Pb forms in soil |
| Received:October 15, 2017 |
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| KeyWord:biochar;Cd;Pb;immobilization;bioavailability |
| Author Name | Affiliation | E-mail | | AN Mei | College of Resources and Environment, Qingdao Agricultural University, Qingdao 266109, China | | | DONG Li | College of Resources and Environment, Qingdao Agricultural University, Qingdao 266109, China | | | ZHANG Lei | College of Resources and Environment, Qingdao Agricultural University, Qingdao 266109, China | zhanglei_zhxy@163.com | | SUN Chong-hai | College of Resources and Environment, Qingdao Agricultural University, Qingdao 266109, China | | | XIA Pei-yu | College of Resources and Environment, Qingdao Agricultural University, Qingdao 266109, China | |
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| Abstract: |
| The bioavailability of heavy metals in soils is closely related to their chemical fractions. In this study, four kinds(made from the common wastes of urban sludge and maize, cotton, and wheat straws) and two levels of biochar were added to soil contaminated with Cd and Pb to investigate their effects on the chemical fractions of Cd and Pb and to further analyze the immobilization and remediation of heavy metals in soil. The results showed that the physical and chemical properties of the soil were changed by biochar application and the pH, CEC, and SOM were significantly improved, especially with the 4% application treatments, with increases of 2.7%~11.6%, 12.7%~54.3%, and 252.0%~594.8%, respectively. Overall, adding the four kinds of biochar reduced the weak-acid-extractable and reducible fractions, whereas the oxidation and residue fractions increased. Regarding the immobilizing effect of soil Cd pollution, the cotton straw biochar showed the best passivation, followed by corn straw, wheat straw, and sludge biochar. When the cotton straw biochar was added at a rate of 4%, the weak-acid-extractable and reducible fractions of Cd decreased by 5.2% and 25.5%, respectively, and the oxidation and residue fractions increased by 177.8% and 166.7%, respectively. Similarly, adding the biochars showed passivation effects at different levels of the soil Pb pollution. Among the four kinds of biochars, the sequence of immobilizing effect was corn straw > wheat straw > cotton straw > sludge. Correlation analysis showed that the changes in soil physical and chemical properties were likely to be important factors that induced the changes in the heavy metal forms of the soil. The results implicated that applying biochar can effectively change the chemical fractions of heavy metals in soil and reduce bioavailability, thus can be used as a solution to soil heavy metal pollution. |
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