Arsenic Uptake and Accumulation in Rice (Oryza sativa L.) at Different Growth Stages following Soil Incorporation of Roxarsone and Arsanilic Acid

Experiments were conducted with rice (Oryza sativa L.) by adding 0, 10, 20, 30, 40, 50 mg kg^-1 of arsenic (As) to soil (with roxarsone and arsanilic acid, presented as As concentrations) at a field with an isolation chamber. The aims were to evaluate the effects of As- (roxarsone or arsanilic acid) contaminated soil on rice agronomic parameters and uptake of As in different plant parts of the rice plant. The results showed that As (roxarsone or arsanilic acid) could significantly reduce plant height, effective tiller number, straw weight and grain yield (P < 0.01). As concentrations in different parts of the plant varied with the growth stages, and behaved similarly. At the maturing stage, the level in different parts peaked in all treatments, with tissue As concentrations showing the pattern: root > leaf > stem > husk > grain. In addition, at the mature stage, the As concentrations in different parts of the rice plant increased with increasing concentrations of roxarsone and arsanilic acid. The highest concentration of As found in grain was 0.82 mg kg^-1, which did not exceed the statutory permissible limit for rice grain (1.0 mg As kg^-1), and in the leaf and stem it was approximately 6.0 mg kg^-1, which was significantly higher than that in the controls. The results showed that rice could accumulate As from contaminated soil (roxarsone or arsanilic acid), which may be transferred to human beings via the food chain.