The dynamics of arsenic in four paddy fields in the Bengal delta

Stroud, Jacqueline L.; Norton, Gareth J.; Islam, Md. Rafiqul; Dasgupta, Tapash; White, R.P.; Price, Adam H.; Meharg, Andrew A.; McGrath, Steve P.; Zhao, Fang

doi:10.1016/j.envpol.2010.12.016

Cited by 98 publications

(33 citation statements)

References 24 publications

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“…14,15 Arsenite (As(III)) is more weakly bound to most soil minerals than As(V); thus, As(V) reduction results in As release into soil solutions, especially under anaerobic conditions such as paddy soil. 16,17 On the other hand, some heterotrophic as well as chemoautotrophic microorganisms are able to oxidize As(III) to As(V). 18 Arsenite oxidation is suggested to facilitate As sequestration in metal oxides and is often used as a tool to remediate As-contaminated waters and soils.…”

Section: ■ Introductionmentioning

confidence: 99%

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Arsenic Uptake by Rice Is Influenced by Microbe-Mediated Arsenic Redox Changes in the Rhizosphere

Jia

Huang

Chen

et al. 2014

Environ. Sci. Technol.

180

116

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Arsenic (As) uptake by rice is largely determined by As speciation, which is strongly influenced by microbial activities. However, little is known about interactions between root and rhizosphere microbes, particularly on arsenic oxidation and reduction. In this study, two rice cultivars with different radial oxygen loss (ROL) ability were used to investigate the impact of microbially mediated As redox changes in the rhizosphere on As uptake. Results showed that the cultivar with higher ROL (Yangdao) had lower As uptake than that with lower ROL (Nongken). The enhancement of the rhizospheric effect on the abundance of the arsenite (As(III)) oxidase gene (aroA-like) was greater than on the arsenate (As(V)) reductase gene (arsC), and As(V) respiratory reductase gene (arrA), resulting in As oxidation and sequestration in the rhizosphere, particularly for cultivar Yangdao. The community of As(III)-oxidizing bacteria in the rhizosphere was dominated by α-Proteobacteria and β-Proteobacteria and was influenced by rhizospheric effects, rice straw application, growth stage, and cultivar. Application of rice straw into the soil increased As release and accumulation into rice plants. These results highlighted that uptake of As by rice is influenced by microbial processes, especially As oxidation in the rhizosphere, and these processes are influenced by root ROL and organic matter application. ■ INTRODUCTIONArsenic (As) contamination and its health impacts are widespread around the world. 1,2 Large areas of paddy soils are contaminated by As due to irrigation with As-tainted groundwater, mining, and other industrial activities. Rice is particularly efficient in accumulating As, compared with other cereal crops, as a result of its anaerobic growth conditions. 3 This poses potential harm to people through ingestion of rice, especially in Southeast Asia where rice is consumed as the staple food. 4−6 Rhizospheric chemical processes, such as iron oxidation−reduction and iron plaque formation on root surfaces, play an important role in affecting As uptake by rice plants, and they are largely influenced by oxygen release from rice roots. 7,8 The aerated rice rhizosphere and O 2 -releasing root surface are usually coated with iron (Fe) and manganese (Mn) oxides, while As is precipitated with these oxides mainly as arsenate (As(V)). 8,9 In addition to chemical processes, As speciation and mobility in soils, sediments, and natural water systems are mainly driven by microbial transformations. 10−12 Anaerobic bacteria containing the respiratory reductase (ArrA) can use As(V) as the terminal electron acceptor in respiration and conserve energy from this process. 13 Another pathway for microbial As(V) reduction lies in the widespread As detoxification by As(V) reductase (ArsC). 14,15 Arsenite (As(III)) is more weakly bound to most soil minerals than As(V); thus, As(V) reduction results in As release into soil solutions, especially under anaerobic conditions such as paddy soil. 16,17 On the other hand, some heterotrophic as well a...

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Section: ■ Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Arsenic Uptake by Rice Is Influenced by Microbe-Mediated Arsenic Redox Changes in the Rhizosphere

Jia

Huang

Chen

et al. 2014

Environ. Sci. Technol.

180

116

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“…Rice is the staple food crop and one of the major sources of As intake for the population living in some regions of Bangladesh, West Bengal, China, Taiwan and Thailand. In these areas, people suffer from the high As levels in soils and groundwater (Brammer and Ravenscroft 2009;Fendorf et al 2010;Stroud et al 2011). In Bangladesh, As-contaminated groundwater is used as drinking water by tens of millions of people and is also used for rice cultivation, particularly during the dry season.…”

Section: Introductionmentioning

confidence: 99%

Phosphate deficiency signaling pathway is a target of arsenate and phosphate transporterOsPT1is involved in As accumulation in shoots of rice

Kamiya

Islam

Duan

et al. 2013

Soil Science and Plant Nutrition

144

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Arsenate [As(V)] is toxic to organisms, and phosphate (Pi) transporter can mediate As(V) uptake due to their similarity in chemical structure. In the rice (Oriza sativa L.) genome, 13 Pi transporter genes (OsPTs) are present. Their response to As(V) and contribution to As(V) accumulation are unknown. We determined absolute mRNA amount of OsPTs in rice seedlings and OsPT1, OsPT2, OsPT4, and OsPT8 were quantified by real-time polymerase chain reaction (PCR). OsPT2, OsPT4, and OsPT8 were highly induced by Pi deficiency, while OsPT1 was not. In accordance with Pi deficiency response, OsPT2, OsPT4, and OsPT8 induction by Pi deficiency were severely suppressed by As(V). Those data suggest that As(V) affects Pi deficiency signaling in rice. To examine the As(V) transport activity of OsPT1 in planta, we obtained T-DNA mutant of OsPT1 (ospt1). The transcript expression level of OsPT1 in ospt1 was reduced by 70% in shoots and 50% in roots compared to those in the wild-type (WT), and arsenic (As) concentrations in shoots were reduced by 60% compared to WT. We further overexpressed OsPT1-GFP in rice. Overexpression lines showed higher As accumulation in shoots compared to wild-type. OsPT1-GFP is localized to plasma membrane. These results indicate that OsPT1 is involved in As(V) uptake from soil or apoplast.

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“…Large areas of farmland have been contaminated by arsenic (As) due to the irrigation with As-enriched groundwater or the contamination by mining and other activities (Zhu et al 2008b;Smith et al 2000;Li et al 2011). In paddy soils, As is released into soil solution mainly in the form of arsenite (As(III)), by As-reducing bacteria and by the reductive dissolution of iron oxyhydroxides which reduces the binding sites of As on minerals (Stroud et al 2011;Xu et al 2008). Elevated concentration of As(III) in the soil solution under anaerobic condition provides As sources to rice plants (Roberts et al 2010;Jia et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Arsenic bioavailability to rice plant in paddy soil: influence of microbial sulfate reduction

2015

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Purpose High arsenic (As) mobility in anaerobic paddy soil due to microbial Fe-and As-reducing processes results in As accumulation into rice plants. Sulfur (S) also undergoes microbial reducing processes in the anaerobic paddy soil, while this process interacts with the Fe-and As-reducing processes, forms secondary minerals, and thus influences As mobility in paddy soil. This work was carried out to investigate the role of sulfur and sulfate-reducing bacteria (SRB) in As redox transformation and bioavailability to rice plant in an anaerobic paddy soil. Materials and methods Anaerobic incubation experiments with or without sulfate (SO 4 2− ) and SRB were carried out to monitor S and iron (Fe) dynamics and their relations to As speciation and release to soil solution. Rice cultivation in pot experiment was then carried out to check the SO 4 2− amendment in bioavailability and uptake into rice plants.Results and discussion The inoculation of an enriched SRB community into the sterilized paddy soil increased reduction and release of As to the soil solution after flooding, showing its ability in arsenate (As(V)) as well as SO 4 2− reduction to arsenite (As(III)) and sulfide (S 2− ), respectively. Sulfate addition (2 and 100 mM) into the anaerobic paddy soil increased the reduction of SO 4 2− and ferric iron (Fe 3+ ) and resulted to lower dissolved As in the soil solution, which limited As mobility in the paddy soil. Application of SO 4 2− (100 mg kg −1 ) into paddy soil finally decreased the concentration of dissolved As in the soil solution by 23.5 % and also decreased As content in rice roots and iron plaque by 22.6 and 30.5 %, respectively. Conclusions The results revealed the important role of sulfur and the SRB activity in As speciation and mobility in anaerobic paddy soil, implying a lower As bioavailability to rice plants under sulfur-enriched anaerobic paddy soil, and an efficient way to reduce As accumulation in rice plants by sulfur fertilization in paddy soils.

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The dynamics of arsenic in four paddy fields in the Bengal delta

Cited by 98 publications

References 24 publications

Arsenic Uptake by Rice Is Influenced by Microbe-Mediated Arsenic Redox Changes in the Rhizosphere

Arsenic Uptake by Rice Is Influenced by Microbe-Mediated Arsenic Redox Changes in the Rhizosphere

Phosphate deficiency signaling pathway is a target of arsenate and phosphate transporterOsPT1is involved in As accumulation in shoots of rice

Arsenic bioavailability to rice plant in paddy soil: influence of microbial sulfate reduction

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