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| Aging kinetics and main controlling factors of Cr(Ⅵ)in typical farmland soils in China |
| Received:July 19, 2020 |
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| KeyWord:hexavalent chromium;soil;aging;pH;organic matter |
| Author Name | Affiliation | E-mail | | MU Zu-ting | School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China | | | ZHANG Yan-yi | High-tech Zone Branch of Qingdao Municipal Bureau of Ecology and Environment, Qingdao 266000, China | | | MA Yi-bing | Macao Environmental Research Institute, Macau University of Science and Technology, Macao 999078, China | ybma@must.edu.mo | | LI Shi-wei | School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China | | | LI He-lian | School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China | | | HAN Xue-mei | School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China | |
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| Abstract: |
| Soil properties play an important role in aging of Cr(Ⅵ). Owing to the diversity of soil types in China, the aging process and main controlling factors of Cr(Ⅵ)in different farmland soils still need to be investigated. In the present study, 12 farmland soils with different properties, in China, were collected and spiked with Cr(Ⅵ). A solution of 0.05 mol·L-1 EDTA was used to extract available Cr(Ⅵ) and Cr(Ⅲ). Their dynamic process and main controlling factors were investigated using a combination of HPLC-ICP-MS, dynamic model fitting, and multiple linear regression. Results showed that the available Cr(Ⅵ)decreased rapidly from 6.71%~68.71% to 4.53%~45.17% at the initial time(t<60 d), and then decreased slowly and equilibrated gradually(3.25%~34.35%). Pseudo-second-order model described well the aging process of Cr(Ⅵ)in all soils during the entire aging time(R2>0.99). Results of multiple stepwise regression analysis showed that soil pH was the main factor controlling the aging rate of Cr(Ⅵ). Based on the pseudo-second-order model, the approximate aging equilibrium time of spiked Cr(Ⅵ)was derived to be from 6 to 158 days; soil pH and organic matter content were the main controlling factors. In addition, the available Cr(Ⅲ)generated from the reduction of Cr(Ⅵ)increased rapidly and peaked(0.27%~3.27%)at 2 to 30 days, then decreased rapidly, and finally attained equilibrium(0.01%~2.19%). The aging process of Cr(Ⅲ)may be related to Cr(Ⅵ) reduction and aging and Cr (Ⅲ)self-aging. |
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