ABSTRACT
Rice is the main staple food for billions people worldwide. Geogenic and anthropogenic sources lead to concentration of As, in particular, above the plow pan of paddy soils. Flooded conditions increase the As concentrations in paddy soil-water system above those of non-flooded conditions. Formation of rice root plaque, availability of metal (hydr) oxides (i.e., Fe and Mn), dissolved organic carbon (DOC), competing ions (i.e., P and Si), and microorganisms play an important role in As speciation and distribution in rice rhizosphere and subsequent uptake by rice plant. Arsenic species are acquired by rice roots through the pathways for nutrients and metabolized via a variety of mechanisms. A number of metabolic pathways including As(III) efflux, and As-thiol complexation and sequestration may decrease As burden in rice tissues.
