title: Optimal Soil Eh, pH, and Water Management for Simultaneously Minimizing Arsenic and Cadmium Concentrations in Rice Grains.
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.
authors.affiliation: Niigata Agricultural Research Institute, Nagaoka, Niigata 940-0826, Japan.
authors.forename: Toshimitsu
authors.initials: T
authors.lastname: Honma
authors.affiliation: Niigata Agricultural Research Institute, Nagaoka, Niigata 940-0826, Japan.
authors.forename: Hirotomo
authors.initials: H
authors.lastname: Ohba
authors.affiliation: Niigata Agricultural Research Institute, Nagaoka, Niigata 940-0826, Japan.|Ojiya Branch, Nagaoka Agriculture Extension Center , Ojiya, Niigata 947-0028, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Kaneko-Kadokura
authors.affiliation: National Institute for Agro-Environmental Sciences, Tsukuba, Ibaraki 305-8604, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Makino
authors.affiliation: National Institute for Agro-Environmental Sciences, Tsukuba, Ibaraki 305-8604, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: National Institute for Agro-Environmental Sciences, Tsukuba, Ibaraki 305-8604, Japan.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Katou
mesh_terms: D057914:Agricultural Irrigation; D000383:Agriculture / Q000379:methods*; D001151:Arsenic / Q000032:analysis; D002104:Cadmium / Q000032:analysis; D002523:Edible Grain / Q000737:chemistry; D055868:Floods; D005506:Food Contamination; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007564:Japan; D012275:Oryza / Q000737:chemistry; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis
chemical_list: D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium; D001151:Arsenic