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Background and Aims The accumulation of cadmium and lead in rice (Oryza sativa L.) grains is a potential threat to human health. In this study, the effect of selenium fertilization on the uptake and translocation of cadmium and lead in rice plants was investigated. Methods Rice plants were cultivated using cadmium and lead contaminated soils with selenium addition at three concentrations (0, 0.5 and 1 mg kg −1 ). At maturity, plants were harvested, and element concentrations in rice tissues were analyzed by using ICP-MS.Results Selenium application significantly increased seleniumaccumulationinricegrain,andmarkedlydecreased cadmium and lead concentrations in rice tissues. In brown rice grains, selenium application reduced cadmium concentrations by 44.4%, but had nosignificant effect onlead accumulation. Selenium application significantly decreased metal mobility in soils, at 0.5 mg kg −1 treatment, the translocation factor of cadmium and lead from soil to ironplaquedecreased by71and 33% respectively. Conclusions The mechanism of selenium mitigating of heavy metal accumulation in rice could be decreasing metal bioavailability in soil. Selenium fertilization could be an effective and feasible method to enrich selenium and reduce cadmium levels in brown rice.

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The structures, relative stabilities, vertical detachment energies and magnetic coupling properties of a series of manganese-based dinuclear superhalogens and their isoelectronic analogues are explored via a combined density functional theory and broken symmetry study. Both the capabilities of various exchange-correlation functionals and basis set effects are investigated. The large magnitudes of the calculated exchange coupling constants indicate clearly the apparent molecular magnetism of these new types of superhalogen. Encouragingly, the high possibility of the coexistence of both high stability and strong magnetic coupling in these new polynuclear superhalogens is also confirmed. Besides these, the larger magnitudes of the calculated coupling constants of iron-based clusters here, compared with the homodinuclear [Mn(2)Cl(5)](-) cluster, demonstrate the possibility of the existence of strong magnetic coupling in potential iron-based homo- and heterodinuclear superhalogens. The analysis of spin density distribution is also performed in order to understand the coupling mechanisms.