Mitigation of arsenic accumulation in rice: An agronomical, physico-chemical, and biological approach – A critical review

Abstract

Human exposure to As through rice consumption is a worldwide health concern. There is an urgent need to either remediate As contaminated paddy soils, or to screen for low As accumulating rice varieties, thereby limiting the build up of As in their grains. This review presents a number of agronomic, physico-chemical, and biological approaches that may reduce the As content in paddy agroecosystems. Studies have shown that alternative water management practices significantly reduce As accumulation in rice grains. The application of Si sources into As contaminated paddy soils may limit As(III) uptake. The supplementation of redox-sensitive elements (i.e. Fe and Mn) and the incorporation of biochar (BC) may also immobilize As in the paddy environment. Inoculation of microorganisms is another in-situ method to reduce As in rice grains. Accumulation of As in rice grains can also be largely reduced through altering the expression of genes in rice plants. However, applicability of potential As mitigation approaches is dependent on the biogeochemical properties of the paddy agroecosystems, water management practices, availability of sources, and cost. This article expands on research gaps and provides future research directions to enable the production of safer rice grains with reduced As accumulation.

Keywords:

• Arsenic methylation
• biochar
• microorganisms
• rice
• soil amendments
• water management