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| Effects of ageing on the availability of endogenous copper and cadmium in biochar derived from Pennisetum sp. Stems |
| Received:September 12, 2019 |
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| KeyWord:biochar;endogenous heavy metal;speciation;leaching toxicity;ageing effect |
| Author Name | Affiliation | E-mail | | ZHANG Xue | School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, China | | | LIU Xiao-sheng | School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, China | | | SHEN Lu-lu | School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, China | | | CUI Hong-biao | School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, China | cuihongbiao0554@163.com |
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| Abstract: |
| The effects of ageing on the availability of endogenous heavy metals in biochar are unclear. In this study, two biochars with different concentrations of endogenous Cu and Cd were produced from the stems of Pennisetum sp. that were planted in clean soil(Hongrang Station; HR)and polluted soil(Jiuniu Village; JN). After ageing using dry-wet cycles(DW), freeze-thaw cycles(FT), and acidification(AF), the leaching toxicity and speciation distribution of Cu and Cd in the two biochars were investigated using the toxicity characteristic leaching procedure(TCLP)and the method proposed by the Community Bureau of Reference(BCR), respectively. Meanwhile, the potential ecological risk of endogenous Cu and Cd in the two biochars was assessed using the risk assessment code(RAC). The results showed that the leachability of Cu and Cd in the two biochars after FT ageing were higher than those after DW and AF. The leachable contents of Cu in the JN and HR biochars after FT ageing were increased by 50.6% and 571%, respectively, and those of Cd were increased by 161% and 620%, respectively. Moreover, all the ageing processes promoted the transformation of Cu and Cd from the oxidizable and reducible fractions to the acid-soluble fraction and increased the RAC values of endogenous Cu and Cd in the two biochars. In particular, the FT ageing process was the most effective at increasing the potential risk of endogenous Cu and Cd in the two biochars. This study showed that the ageing processes increased the availability of endogenous Cu and Cd in the two biochars and enhanced their potential ecological risk. |
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