Arsenic release from flooded paddy soils is influenced by speciation, Eh, pH, and iron dissolution

Yamaguchi, Noriko; Nakamura, Takakazu; Dong, Dian-Tao; Takahashi, Yoshio; Amachi, Seigo; Makino, Tomoyuki

doi:10.1016/j.chemosphere.2011.02.044

Cited by 297 publications

(173 citation statements)

References 45 publications

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“…Arsenic concentrations of soils A and B were 37.1 and 39.5 mg kg −1 , respectively. Detailed soil properties of soils A and B were reported by Yamaguchi et al (2011). The soils were passed through a 2-mm sieve under field moist conditions and stored in a refrigerator at 7°C until use.…”

Section: Soil Samplesmentioning

confidence: 99%

“…Although microbial activity can affect arsenic mobilization indirectly via reductive dissolution of iron (hydr)oxides associated with arsenic (Cummings et al 1999), numerous studies have revealed that As(V) reduction might be a key process controlling arsenic mobilization (Yamamura et al 2008;Ohtsuka et al 2013). Recently, Yamaguchi et al (2011) found that microbial activity was indispensable for reduction of As (V) to As(III), when two Japanese paddy soils were incubated under reducing conditions. Not only reductive dissolution of As(V), but adsorption and oxidation of As(III) in soils are also important processes to determine the toxicity, mobility and bioavailability of arsenic in terrestrial environments.…”

Section: Introductionmentioning

confidence: 99%

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Effect of soil microorganisms on arsenite oxidation in paddy soils under oxic conditions

Dong

Yamaguchi

Makino

et al. 2014

Soil Science and Plant Nutrition

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The contribution of abiotic and biotic processes to the oxidation of arsenite [As(III)] when anaerobic paddy soils were shifted to oxic conditions was investigated. Soil slurries were first incubated under reducing conditions to allow indigenous arsenic (As) to be dissolved into the liquid phase as As(III), and were then switched to oxic incubation conditions with shaking. One day after switching to oxic incubation, As(III) almost disappeared from the liquid phase without any increase of arsenate [As(V)], suggesting that dissolved As(III) was coprecipitated or adsorbed on the soil solid phase. X-ray adsorption near-edge structure (XANES) analysis revealed that the predominant species of As in the solid phase before the oxic incubation was As(III), ranging from 74 to 85% of total As. After 1 d of the oxic incubation, the proportion of As(III) decreased to 46-47%. This oxidation step was an abiotic process and 28-38% of As(III) was oxidized per day on average. However, the abiotic oxidation ceased within 24 h probably due to passivation of reactive sites on the mineral surface. Afterward, a second slow oxidation step (2.5-2.8% per day on average) became predominant. Interestingly, this step was microbiologically mediated, since it did not occur in sterilized soil slurries. Determination of putative arsenite oxidase gene (aioA) sequences suggested that arsenite-oxidizing bacteria are actually present in our soil slurries. Our results suggest that microbial As(III) oxidation accounts for more than 30% of total As(III) oxidation, and thus it is an important process especially after abiotic oxidation ceases.

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Section: Soil Samplesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of soil microorganisms on arsenite oxidation in paddy soils under oxic conditions

Dong

Yamaguchi

Makino

et al. 2014

Soil Science and Plant Nutrition

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“…Iron oxide is believed to be the dominant factor controlling the bioavailability and mobility of As in the soil [38]. In paddy soil under flooding conditions, ferric iron is reduced to ferrous iron, and As sequestrated on iron oxide is then released to soil pore water [29,30]. This is in fact one of the key reasons why rice often contains much higher As than upland crops [7].…”

Section: Abiotic Factors Influencing the Speciation And Mobility Of Amentioning

confidence: 99%

“…The other is the detoxification mechanism of microorganisms including As(V) reduction and As(III) efflux out from cells [55]. A recent report suggested that the constant and high (more than 80%) As(III) proportion of total As in solution phase of paddy soil was attributed to microbial activity [30].…”

Section: Arsenic Speciation Modulated By Micro-organismsmentioning

confidence: 99%

“…Arsenate is reduced to As(III) readily, becoming the dominant form [26][27][28], and As becomes more mobile in soil solution due to the increased concentration of As(III). Ferric (hydr)oxide undergoes reductive dissolution under anaerobic conditions, this process also causes As release from soils or iron oxide minerals [29,30]. Redox reactions in soils are mainly controlled by microbial activities [31].…”

Section: Abiotic Factors Influencing the Speciation And Mobility Of Amentioning

confidence: 99%

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Effects of microbial processes on the fate of arsenic in paddy soil

2012

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Arsenic (As) is a metalloid toxic to organisms including humans. Arsenic in rice represents a significant exposure pathway for the general population, particularly for those subsisting on rice. Arsenic transformation, namely reduction, oxidation and methylation, in soil-rice systems has fundamental impacts on its mobility and toxicity. In addition to soil chemical properties (pH, Eh, metallic oxides, organic matter), microorganisms play critical roles in As transformation and mobility in paddy soil, such as through ArsM (As(III) S-adenosylmethyltransferase) and interactions with iron oxides or organic matters. Arsenic species in paddy soil directly influence As speciation in rice grain because the methylated As species in rice are mainly derived from microbial methylation in paddy soil. This paper aims to provide an overview on the status of the knowledge and gaps on the chemical aspects of As transformation in soil-rice system in conjunction with microbial ecology and functional genes. In addition, potential pathways (manipulation of microorganisms in paddy soil and genetic engineering) to decrease total As and/or inorganic As in rice grain are proposed.

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