Toxic trapper

Iron combats arsenic menace

Published: Tuesday 30 November 2004

iron deposits on the roots of rice plants can block their uptake of arsenic, as per scientists from China. The findings could help researchers breed rice varieties that are able to resist contamination.

Arsenic contamination of groundwater is a key public health problem in India and Bangladesh. The toxin even enters crops and vegetables via contaminated water used for irrigation. Research led by Andrew Mehard of the uk-based University of Aberdeen has established that for people whose drinking water is moderately contaminated, tainted rice could be the dominant source of arsenic exposure. But until now, researchers were perturbed about how some rice plants escaped the menace of arsenic.

The Chinese researchers, from the Research Centre for Eco-Environmental Sciences, found that when rice grows in flooded fields, iron deposits (clearly visible as a reddish coating) form on their roots. The arsenic gets trapped in these deposits. Depending on the rice variety, significantly different amounts of arsenic is trapped. Moreover, more iron deposits form when the phosphorous levels of the soil are low. "This implies that if a low-phosphorus chemical fertiliser is used, more arsenic may be blocked," the researchers assert.

The scientists have teamed up with researchers from the University of Aberdeen to develop arsenic-resistant rice varieties in the near future. But they will need to assess whether these varieties have a high yield or not.

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