ABSTRACT
Arsenic is immobilized under oxidizing conditions and solubilized under reducing conditions whereas the opposite holds true for the solubilization/ immobilization of Cadmium (Cd) in paddy fields. Prolonged submergence, particularly at the heading stage, has been shown to successfully decrease the Cd contents in brown rice, owing to immobilization under reducing conditions (e.g., Inahara et al. 2007). Prolonged submergence, at the same time, enhances Arsenic (As) solubilization through the development of strongly reduced conditions, which could lead to an increased As uptake by rice plants. Water management practices aimed at reducing the dissolved Cd concentration is likely compensated with an increase in the dissolved As concentration, and vice versa. Consequently, a “trade-off” relationship may exist between the dissolved As and Cd concentrations in paddy soils.
