Optimal Soil Eh, pH, and Water Management for Simultaneously Minimizing Arsenic and Cadmium Concentrations in Rice Grains

Toshimitsu Honma, Hirotomo Ohba, Ayako Kaneko-Kadokura, Tomoyuki Makino, Ken Nakamura, Hidetaka Katou

Research output: Contribution to journalArticlepeer-review

146 Citations (Scopus)

Abstract

Arsenic (As) and cadmium (Cd) concentrations in rice grains are a human health concern. We conducted field experiments to investigate optimal conditions of Eh and pH in soil for simultaneously decreasing As and Cd accumulation in rice. Water managements in the experiments, which included continuous flooding and intermittent irrigation with different intervals after midseason drainage, exerted striking effects on the dissolved As and Cd concentrations in soil through changes in Eh, pH, and dissolved Fe(II) concentrations in the soil. Intermittent irrigation with three-day flooding and five-day drainage was found to be effective for simultaneously decreasing the accumulation of As and Cd in grain. The grain As and Cd concentrations were, respectively, linearly related to the average dissolved As and Cd concentrations during the 3 weeks after heading. We propose a new indicator for expressing the degree to which a decrease in the dissolved As or Cd concentration is compromised by the increase in the other. For minimizing the trade-off relationship between As and Cd in rice grains in the field investigated, water management strategies should target the realization of optimal soil Eh of -73 mV and pH of 6.2 during the 3 weeks after heading.

Original languageEnglish
Pages (from-to)4178-4185
Number of pages8
JournalEnvironmental Science and Technology
Volume50
Issue number8
DOIs
Publication statusPublished - 2016 May 3
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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