Arsenic behavior across soil-water interfaces in paddy soils: Coupling, decoupling and speciation

Yuan, Zhao-Feng; Gustave, Williamson; Boyle, John; Sekar, Raju; Bridge, Jonathan; Ren, Yuxiang; Tang, Xianjin; Guo, Bin; Chen, Zheng

doi:10.1016/j.chemosphere.2020.128713

Cited by 22 publications

(8 citation statements)

References 76 publications

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“…Additionally, the MAT approach is flexible and thus could easily be combined with other strategies to maximize the immobilization of soil As. For example, more efficient As immobilization could be achieved by coupling MAT with the addition of Mn oxides, which will trigger Mn cycling in saturated soils and stimulate chemical oxidation of As(III) to As(V) by Mn(IV) oxides . This indicates that MAT is scalable and can be readily integrated with other techniques to enhance the overall performance.…”

Section: Resultsmentioning

confidence: 99%

Sustainable Immobilization of Arsenic by Man-Made Aerenchymatous Tissues in Paddy Soil

Yuan,

Zhou,

Chen

et al. 2023

Environ. Sci. Technol.

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Arsenic (As) is a major environmental pollutant and poses a significant health risk to humans through rice consumption. Elevating the soil redox potential (Eh) has been shown to reduce As bioavailability and decrease As accumulation in rice grains. However, sustainable methods for managing the Eh of rice paddies are lacking. To address this issue, we propose a new approach that uses man-made aerenchymatous tissues (MAT) to increase soil Eh by mimicking O 2 release from wet plant roots. Our study demonstrated that the MAT method sustainably increased the soil Eh levels from −119 to −80.7 mV (∼30%), over approximately 100 days and within a radius of around 5 cm from the surface of the MAT. Moreover, it resulted in a significant reduction (−28.5% to −63.3%) in dissolved organic carbon, Fe, Mn, and As concentrations. MAT-induced Fe(III) (oxyhydr)oxide minerals served as additional adsorption sites for dissolved As in soil porewater. Furthermore, MAT promoted the oxidation of arsenite to the less mobile arsenate by significantly enhancing the relative abundance of the aioA gene (130% increase in the 0−5 cm soil zone around MAT). The decrease in As bioavailability significantly reduced As accumulation in rice grains (−30.0%). This work offers a low-cost and sustainable method for mitigating As release in rice paddies by addressing the issue of soil Eh management.

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Section: Resultsmentioning

confidence: 99%

Sustainable Immobilization of Arsenic by Man-Made Aerenchymatous Tissues in Paddy Soil

Yuan,

Zhou,

Chen

et al. 2023

Environ. Sci. Technol.

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“…The total heavy metal and As concentrations of the rice samples were analyzed using inductively coupled plasma mass spectrometry (ICP-MS, NexION 300X, Perkin Elmer, US). The As speciation (to determine percentages of inorganic and organic arsenic) was determined using ion chromatography with inductively coupled plasma mass spectrometry (IC-ICP-MS) as described in the literature (Yuan et al, 2021). Briefly, the IC used in this study was equipped with a standard 25 μL sample loop and an anion-exchange column.…”

Section: Sample Analysismentioning

confidence: 99%

Prevalence of arsenic contamination in rice and the potential health risks to the Bahamian population—A preliminary study

Watson

Gustave

2022

Front. Environ. Sci.

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Rice is among the most important staple foods worldwide. However, the consumption of rice and rice-based food products poses a potential health risk since rice is a paddy crop that is well known to accumulate high concentrations of arsenic (As) in its grain. In The Bahamas, although rice is heavily consumed, it is not grown locally. Instead, all the consumed rice and its derived products are imported. Recent food surveys in the major rice exporting countries have shown that a significant portion of their market rice products is contaminated with As. However, to date, the prevalence of As in the rice foods available in The Bahamas remains unknown. Therefore, in this study, we surveyed the occurrence of As in a selection of rice and rice products that were on sale in the Bahamian market. A total of 21 different rice brands were collected. The concentration of As and the potential health risk were estimated by target hazard quotient (THQ), hazard index (HI), and lifetime cancer risk (LCR). Our results showed that only the blue ribbon samples had an estimated inorganic arsenic (iAs) concentration above the World Health Organization (WHO) safety limits (200 μg/kg), which is based on global average consumption. However, when we factor for average rice consumption in The Bahamas, 79% of the rice samples had iAs concentration values indicative of carcinogenic risks and 57% had iAs concentration values that suggested non-carcinogenic health risks. Based on our results, we recommend urgent follow-up studies to further test rice varieties that show the greatest LCR and HI values and to also broaden the study to include more off-brand/generic varieties, cooked rice, and drinking water.

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“…Porewater was sampled in situ across 0-22 mm from the root bag/surface by Rhizon pro lers at days after paddy soil ooding (DAF) 0, 3, 8, 15, 24, 30 and 40 with or without rice growing in root bags. Multielement information in each 100 μL porewater sample was determined by the high-throughput analytical method developed by our group (Yuan et al 2020…”

Section: Porewater Sampling By Rhizon Pro Lersmentioning

confidence: 99%

Distinct and dynamic distributions of multiple elements and their species in the rice rhizosphere

et al. 2021

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The biogeochemical cycles of elements from soils to plants are mainly governed by their rhizosphere processes. Understanding these processes is challenging and remains largely unresolved due to the complex interrelationships among different elements and due to a lack of appropriate techniques for simultaneous spatiotemporal monitoring. MethodsThis study employed an In-situ Porewater Iterative (IPI) sampler array (0-22 mm measurement distance every 1.7 mm, with a time interval of 3 to 10 days) to capture the in situ spatiotemporal dynamics of ten elements (Fe, Mn, As, P, S, Cr, Co, Zn, Sb and Cd) in the paddy rhizosphere to examine their covarying changes in time and space dimensions. ResultsThe ndings revealed that the solute-phase concentration of most elements, other than Sb and Cd, increased to a peak after 30 days of paddy soil ooding and then decreased. Additionally, Sb and Cd continuously decreased during ooding. Fe (-52%), Mn (-17%), P (-43%), Co (-11%), and As species (-74%) were substantially immobilized within a 10 mm zone around the roots, while Zn (28%) and Cd (41%) increased. The greater immobilization of As and re-mobilization of Cd, in the rhizosphere, are stimulated by biotic oxidation of arsenite to arsenate with root oxygen loss and the pH decrease, respectively. ConclusionsOur study showed most sampled elements covaried with Fe both in time and space in the rhizosphere, but the elements are temporally and spatially determined by multiple biogeochemical processes in soils as well as exudates from plant roots.

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Arsenic behavior across soil-water interfaces in paddy soils: Coupling, decoupling and speciation

Cited by 22 publications

References 76 publications

Sustainable Immobilization of Arsenic by Man-Made Aerenchymatous Tissues in Paddy Soil

Sustainable Immobilization of Arsenic by Man-Made Aerenchymatous Tissues in Paddy Soil

Prevalence of arsenic contamination in rice and the potential health risks to the Bahamian population—A preliminary study

Distinct and dynamic distributions of multiple elements and their species in the rice rhizosphere

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