In 1967, for the first time, Parizek and Ostadalova reported that Se could effectively prevent mortality caused by high doses of Hg in rats.  Since then, a large number of subsequent studies have confirmed that Hg−Se antagonism is a widespread phenomenon in microorganisms, fish, poultry, humans, and other mammals. However, by comparison, there have been few related studies conducted for plants.

Researchers from FENG Xinbin's group at the Institute of Geochemistry, Chinese Academy of Sciences (IGCAS) and Thorjorn Larssen's group at the Norwegian Institute for Water Research (NIVA) and their coauthors measured the concentrations of Se, Inorganic Hg, and Methyl-Hg in different parts of rice plants (root, stem, leaf, husk, and grain) as well as the corresponding soils of root zones collected from a Hg mined area, where Hg and Se co-occur due to historic Hg mining and retorting activities.

The researchers reported that increasing Se concentrations in soil from root zone may significantly inhibits the uptake and translocation of both inorganic Hg and Methyl-Hg in in the aerial shoots, which may be related to the formation of an Hg−Se insoluble complex in the rhizospheres and/or roots (Zhang H., Feng X., et al., ES&T, 2012: 46(18), 10040–10046). This finding is very important regarding the possibility of adding Se in soil to reduce Hg accumulation in rice in Hg mining area. However, before practical applications, it should be always kept in mind that the margin between Se’s essentiality, deficiency, and toxicity amount to humans and animals is very narrow.

This work is supported by grants from the Youth Innovation Promotion Association of the Chinese Academy of Sciences, Natural Science Foundation of China, and Sino-Norwegian cooperation project, “Capacity building for reducing mercury pollution in China - a case study in Guizhou province”, which was funded by the Norwegian Government.

(By ZHANG Hua)