Zhong Song-Xiong, Yin Guang-Cai, Chen Zhi-Liang, Lin Qin-Tie, Huang Run-Lin, Liu De-Ling, Peng Huan-Long, Huang Ling, Wang Xin, Jiang Xiao-Lu
South China Institute of Environmental Science, Ministry of Environmental Protection, Guangzhou 510665, China.
School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China.
Huan Jing Ke Xue. 2017 Jun 8;38(6):2530-2537. doi: 10.13227/j.hjkx.201611237.
The massive release of soil arsenic and its enrichment in rice are significantly associated with the flooded and anaerobic management in paddy soil. Soil redox potential (Eh), pH and iron oxides exert remarkable impacts on arsenic release, which remain to be explored. In this study, long-term aerobic and anaerobic as well as intermittent aerobic incubation treatments were applied to investigate the influences of Eh, pH and iron content on arsenic release. It was found that anaerobic and flooded treatment contributed to the highest arsenic release. With decreasing Eh, significant enhancement in As(Ⅲ) and As(Ⅴ) contents in soil solution was observed. Particularly, As(Ⅲ) and As(Ⅴ) contents during the second phase increased by 1.37 and 0.99 μg·Lcompared with those in the first phase. Conversely, significant reduction in soil arsenic release (<0.05) occurred when intermittent aerobic treatment was adopted, and the lowest level of arsenic release was observed along with the longest treatment time (6 d). The exponent relationships between arsenic and soil Eh, pH and Fe content were also established, which indicated that arsenic release could be accelerated by lower pH and elevated Eh. In addition, a significant positive correlation was also found between iron(Ⅱ) content and arsenic content in soil solution. Since low Eh and elevated pH served as critical factors driving arsenic release, intermittent and aerobic water management was proved to be an effective method for the inhibition of arsenic release and uptake and accumulation of arsenic by rice.
土壤中砷的大量释放及其在水稻中的富集与稻田土壤的淹水和厌氧管理显著相关。土壤氧化还原电位（Eh）、pH值和铁氧化物对砷的释放有显著影响，这仍有待探索。在本研究中，采用长期好氧、厌氧以及间歇好氧培养处理，以研究Eh、pH值和铁含量对砷释放的影响。结果发现，厌氧和淹水处理导致最高的砷释放量。随着Eh的降低，土壤溶液中As(Ⅲ)和As(Ⅴ)含量显著增加。特别是，第二阶段的As(Ⅲ)和As(Ⅴ)含量与第一阶段相比分别增加了1.37和0.99μg·L。相反，采用间歇好氧处理时，土壤砷释放量显著降低（<0.05），且处理时间最长（6天）时砷释放量最低。还建立了砷与土壤Eh、pH值和铁含量之间的指数关系，表明较低的pH值和升高的Eh可加速砷的释放。此外，土壤溶液中铁(Ⅱ)含量与砷含量之间也存在显著正相关。由于低Eh和高pH值是驱动砷释放的关键因素，间歇好氧水分管理被证明是抑制砷释放以及水稻吸收和积累砷的有效方法。
