Abstract
The water fern (Azolla pinnata L.) was grown in culture solution with arsenate (As(V)) and dimethylarsinic acid (DMAA). Arsenic concentrations were measured in tissues of the plant after harvest. Plant of control and solution having lower phosphate concentration accumulated significantly higher amount of arsenate compared to that of higher phosphate solution. The Azolla pinnata L. accumulated about 7 folds arsenate than that of DMAA when the plants were grown in solution containing 4.0 μM of arsenate and no phosphate. With the increase of phosphate concentration in culture solution the arsenate uptake into the plant decreased significantly (p ‹ 0.001). The arsenate accumulation in Azolla pinnata L. decreased by 40% for the addition of 100 μM of phosphate in the solution. However, the Azolla pinnata L. accumulated 0.034±0.005 μmol g-1 dry weight of DMAA from solution having 4.0 μM of DMAA and no phosphate. The phosphate concentration did not affect DMAA uptake into the plant significantly. Arsenate uptake was clearly correlated with iron and phosphate uptake into the water fern though DMAA uptake was not. The results suggest that arsenate uptake in the macrophytes might be dependent on phosphate and iron uptake while DMAA was independent thereof.
