Monsoon flooding removes arsenic from rice-paddy soils in Bangladesh, according to a study published online this week in Nature Geoscience. Because Bangladesh relies heavily on arsenic-contaminated groundwater for the irrigation of rice, the finding could prove to be important in helping to sustain future rice production in the area.

Linda Roberts and colleagues show that floodwater releases 13-62% of the arsenic that is added to rice-paddy soils through irrigation with arsenic-contaminated groundwater each year. The arsenic is then removed when the floodwater recedes.

They suggest that soils that aren't periodically flooded by monsoon rains are particularly at risk of arsenic accumulation, which could result in a reduction in the yield and quality of rice.