Decreasing arsenic in rice: Interactions of soil sulfate amendment and water management. (1st April 2023)

• Record Type: Journal Article
• Authors: Fang, Xu; Christl, Iso; Colina Blanco, Andrea E.; Planer-Friedrich, Britta; Zhao, Fang-Jie; Kretzschmar, Ruben
• Is Part Of: Environmental pollution. Volume 322(2023)
• Publication Date: 2023-04-01
• Subjects: Food safety -- Yield -- Inorganic As -- DMA -- Iron plaque -- Intermittent flooding; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2023.121152
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Accumulation of inorganic arsenic (iAs) and dimethylarsenate (DMA) in rice threatens human health and rice yield, respectively. We studied the yet unclear interactions of soil sulfate amendment and water management for decreasing As accumulation in rice grain in a pot experiment. We show that soil sulfate amendment (+200 mg S/kg soil) decreased grain iAs by 44% without clearly increasing grain DMA under intermittent flooding from booting stage to maturation. Under continuous flooding during this period, sulfate amendment decreased grain iAs only by 25% but increased grain DMA by 68%. The mechanisms of sulfate amendment effects on grain iAs were not explained by porewater composition or in-planta As sequestration but were allocated to the rhizosphere. Grain iAs closely correlated with As in the root iron-plaque (r = 0.92) which was effectively decreased by sulfate amendment and may have acted as an iAs source for rice uptake. Although both sulfate amendment and intermittent flooding substantially increased porewater DMA concentrations, it was the continuous flooding, irrespective of sulfate amendment, that resulted in rice straighthead disease with 47–55% less yield and 258–320% more DMA in grains than intermittent flooding. This study suggests that combining soil sulfate amendment and intermittent flooding can help to secure the quantity and quality of rice produced in As-affected areas. Our results also imply the key role of rhizosphere processes in controlling both iAs and DMA accumulation in rice which should be elucidated in the future. Graphical abstract: Highlights: Under intermittent flooding, sulfate amendment decreased grain iAs by 44%. Under continuous flooding, sulfate amendment decreased grain iAs only by 25%. Only under continuous flooding, sulfate amendment clearly increased grain DMA. Porewater chemistry and plant As distribution cannot explain grain iAs or DMA. Rhizosphere processes are proposed to control both grain iAs and DMA.