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Arsenic accumulation by the aquatic fern Azolla: comparison of arsenate uptake, speciation and efflux by A. caroliniana and A. filiculoides |
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| Authors: | Zhang Xin Lin Ai-Jun Zhao Fang-Jie Xu Guo-Zhong Duan Gui-Lan Zhu Yong-Guan |
| Institution: | a State Key Lab of Urban and ONAL Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085, China b Department of Environmental Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China c Soil Science Department, Rothamsted Research, Hertfordshire AL5 2JQ, UK d Agricultural Ecology Institute, Fujian Academy of Agricultural Sciences, Fuzhou 350013, China e Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361003, China |
| Abstract: | This study investigates As accumulation and tolerance of the aquatic fern Azolla. Fifty strains of Azolla showed a large variation in As accumulation. The highest- and lowest-accumulating ferns among the 50 strains were chosen for further investigations. Azolla caroliniana accumulated two times more As than Azolla filiculoides owing to a higher influx velocity for arsenate. A. filiculoides was more resistant to external arsenate due to a lower uptake. Both strains showed a similar degree of tolerance to internal As. Arsenate and arsenite were the dominant As species in both Azolla strains, with methlyated As species accounting for <5% of the total As. A. filiculoides had a higher proportion of arsenite than A. caroliniana. Both strains effluxed more arsenate than arsenite, and the amount of As efflux was proportional to the amount of As accumulation. The potential of growing Azolla in paddy fields to reduce As transfer from soil and water to rice should be further evaluated. |
| Keywords: | Arsenic As speciation As tolerance As uptake Azolla Accumulation Detoxification |
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