Growing rice aerobically markedly decreases arsenic accumulation

X. Y. Xu, S. P. McGrath, A. A. Meharg, F. J. Zhao

Research output: Contribution to journalArticle

371 Citations (Scopus)

Abstract

Arsenic (As) exposure from consumption of rice can be substantial, particularly for the population on a subsistence rice diet in South Asia. Paddy rice has a much enhanced As accumulation compared with other cereal crops, and practical measures are urgently needed to decrease As transfer from soil to grain. We investigated the dynamics of As speciation in the soil solution under both flooded and aerobic conditions and compared As accumulation in rice shoot and grain in a greenhouse experiment. Flooding of soil led to a rapid mobilization of As, mainly as arsenite, in the soil solution. Arsenic concentrations in the soil solution were 7-16 and 4-13 times higher under the flooded than under the aerobic conditions in the control without As addition and in the +As treatments (10 mg As kg-l as arsenite or arsenate), respectively. Arsenate was the main As species in the aerobic soil. Arsenic accumulation in rice shoots and grain was markedly increased under flooded conditions; grain As concentrations were 10-15-fold higher in flooded than in aerobically grown rice. With increasing total As concentrations in grain, the proportion of inorganic As decreased, while that of dimethylarsinic acid (DMA) increased. The concentration of inorganic As was 2.6-2.9 fold higher in the grain from the flooded treatment than in that from the aerobic treatment. The results demonstrate that a greatly increased bioavailability of As under the flooded conditions is the main reason for an enhanced As accumulation by flooded rice, and growing rice aerobically can dramatically decrease the As transfer from soil to grain.

Original languageEnglish
Pages (from-to)5574-5579
Number of pages6
JournalEnvironmental Science & Technology
Volume42
Issue number15
Early online date26 Jun 2008
DOIs
Publication statusPublished - Aug 2008

Keywords

  • oryza-sativa L.
  • iron plaque
  • dietary exposure
  • irrigation water
  • basket survey
  • speciation
  • Bangladesh
  • grain
  • contamination
  • plants

Cite this

Growing rice aerobically markedly decreases arsenic accumulation. / Xu, X. Y.; McGrath, S. P.; Meharg, A. A.; Zhao, F. J.

In: Environmental Science & Technology, Vol. 42, No. 15, 08.2008, p. 5574-5579.

Research output: Contribution to journalArticle

Xu, X. Y. ; McGrath, S. P. ; Meharg, A. A. ; Zhao, F. J. / Growing rice aerobically markedly decreases arsenic accumulation. In: Environmental Science & Technology. 2008 ; Vol. 42, No. 15. pp. 5574-5579.
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AB - Arsenic (As) exposure from consumption of rice can be substantial, particularly for the population on a subsistence rice diet in South Asia. Paddy rice has a much enhanced As accumulation compared with other cereal crops, and practical measures are urgently needed to decrease As transfer from soil to grain. We investigated the dynamics of As speciation in the soil solution under both flooded and aerobic conditions and compared As accumulation in rice shoot and grain in a greenhouse experiment. Flooding of soil led to a rapid mobilization of As, mainly as arsenite, in the soil solution. Arsenic concentrations in the soil solution were 7-16 and 4-13 times higher under the flooded than under the aerobic conditions in the control without As addition and in the +As treatments (10 mg As kg-l as arsenite or arsenate), respectively. Arsenate was the main As species in the aerobic soil. Arsenic accumulation in rice shoots and grain was markedly increased under flooded conditions; grain As concentrations were 10-15-fold higher in flooded than in aerobically grown rice. With increasing total As concentrations in grain, the proportion of inorganic As decreased, while that of dimethylarsinic acid (DMA) increased. The concentration of inorganic As was 2.6-2.9 fold higher in the grain from the flooded treatment than in that from the aerobic treatment. The results demonstrate that a greatly increased bioavailability of As under the flooded conditions is the main reason for an enhanced As accumulation by flooded rice, and growing rice aerobically can dramatically decrease the As transfer from soil to grain.

KW - oryza-sativa L.

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KW - basket survey

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