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| Effects of instability of ferrihydrite on arsenic chemical behavior in soil under different water regimes |
| Received:September 18, 2019 |
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| KeyWord:ferrihydrite;arsenic;dry-wet cycle;transformation/dissolution |
| Author Name | Affiliation | E-mail | | ZHANG Tuo | College of Environmental Science & Engineering, China West Normal University, Nanchong, 637009, China
Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Environment, Ministry of Agriculture and Rural Affairs, Beijing 100081, China | | | ZENG Xi-bai | Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Environment, Ministry of Agriculture and Rural Affairs, Beijing 100081, China | zengxibai@caas.cn | | SU Shi-ming | Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Environment, Ministry of Agriculture and Rural Affairs, Beijing 100081, China | | | WANG Ya-nan | Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Environment, Ministry of Agriculture and Rural Affairs, Beijing 100081, China | | | BAI Ling-yu | Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Environment, Ministry of Agriculture and Rural Affairs, Beijing 100081, China | |
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| Abstract: |
| In order to utilize ferrihydrite as an efficient and stable amendment of arsenic(As)-contaminated farmland, three typical red soils were sampled in three towns in Shimen Region, Hunan Province, and were used for the indoor soil incubation experiment. Sequential extraction and Diffusive gradients in the thin-films technique(DGT)were employed in this research to study the effect of soil moisture on the stability of ferrihydrite in soils. The results determined the transformation rate of ferrihydrite(0.1% W/W)in three soils(one uncontaminated soil and two contaminated soils)using three soil water management regimes[100% SWHC(Soil water holding capacity), DWC(Dry/wet cycle)and 30% SWHC]. Ferrihydrite transformed the fastest at 100% SWHC(16.50%~22.78% in the three soils)while the maximum transformation at 30% SWHC and DWC was only 8.77% and 10.96%, respectively. The concentration of DGT labile As was significantly decreased with all the treatments of the two contaminated soils, especially at 100% SWHC, where the concentration of labile As was reduced 42.08% and 60.75% in mid and high As concentration soils, respectively. Using the 100% SWHC and DWC regimes, the concentration of labile As increased as a result of ferrihydrite transformation/dissolution. After ferrihydrite addition, the content of arsenic in Fraction 1(F1-As)and Fraction 2(F2-As)both increased under 100% SWHC and DWC, while no transformation of As fractionation was observed in 30% SWHC. The study indicates that ferrihydrite is instable at 100% SWHC and DWC water regimes and As has the potential to be rereleased to the environment during the remediation period. It is important to regulate soil moisture at a proper level to ensure ferrihydrite stability. |
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