Uptake of mercury (Hg) by seedlings of rice (Oryza sativa L.) grown in solution culture and interactions with arsenate uptake

We investigated the mercury (Hg) uptake by seedlings of rice (Oryza sativa L.) grown in solution and interactions between Hg and arsenate uptake. The results showed that increasing Hg2+ concentrations in the nutrient solution decreased both root and shoot biomass. Hg2+ at concentrations of 1.0 and 2.5 mg L−1 caused 50% reduction in root biomass. A 50% reduction in shoot biomass occurred at Hg2+ concentrations of around 0.5 mg L−1. Nevertheless, 0.5 mg As L−1 has no significant effect on plant yield. Hg accumulated in rice roots, and the Hg concentration factor in roots reached nearly 1900 at 2.5 mg Hg L−1. The addition of As slightly increased the Hg concentration in the roots. However, As concentrations in the roots decreased significantly with increasing Hg concentration in the growth solution to 1.0 or 2.5 mg Hg L−1. Shoot As concentrations decreased with increasing Hg concentrations in the growth solution, but increased again with further increase in Hg concentration to 2.5 mg L−1. Possible mechanisms of Hg uptake and interactions between Hg and As in the uptake process are also discussed.