Uptake and accumulation behaviour of angiosperms irrigated with solutions of different arsenic species.

Uptake and metabolisation of arsenic as a function of both the plant type and the chemical form of arsenic were examined. For this purpose two different plant species (Silene vulgaris and Plantago major) were selected that differed in their vitality and accumulation behaviour on arsenic-loaded substrates. The plants were cultivated on soil and irrigated with aqueous solutions of an inorganic arsenic compound (arsenious acid) and an organic compound (dimethylarsinate). The arsenic species accumulated in the parts of the plants above ground were extracted by PLE and determined using IC-ICP-MS. The concentrations and metabolisation products of arsenic found in the extracts indicate different mechanisms of arsenic uptake and transformation in both angiosperms. The arsenic species pattern showed that S. vulgaris was more arsenic--tolerable than P. major which is attributed to a low arsenate to arsenite concentration ratio in the plant compartments. S. vulgaris was also able to demethylate and reduce dimethylarsinate to form arsenite in a high extent. P. major accumulated only eight times lower concentration of arsenic, and the arsenate to arsenite concentration ratio shifted to higher values. Metabolisation products of dimethylarsinate did not occur under the present experimental conditions. The vitality of the angiosperms seems to be very dependent on the ability of the plant to reduce arsenate to arsenite.