Influence of phosphate and iron ions in selective uptake of arsenic species by water fern (Salvinia natans L.)

Abstract

Abstract In the present study, the effect of phosphate ion and iron hydroxides (Fe-plaques) on the selective uptake of arsenic species by water fern (Salvinia natans L.) was investigated. The plants were grown for 5 days in aqueous Murashige and Skoog (MS) culture media modified in arsenic and phosphate concentrations. Arsenic accumulations in S. natans L. increased with the increase of arsenate and DMAA concentrations in the culture solutions. Compared to the control treatment, S. natans L. accumulated significantly higher amount of arsenic from phosphate-deficient solutions, when the source was arsenate. However, arsenic uptake was not affected significantly by phosphate, when the source was dimethylarsinic acid (DMAA). From solutions containing 100 μM of phosphate and 4.0 μM of either arsenate or DMAA, the S. natans L. accumulated 0.14 ± 0.02 and 0.02 ± 0.00 μmol (g dry weight)−1 of arsenic, respectively. In contrast, plants accumulated 0.24 ± 0.06 and 0.03 ± 0.00 μmol (g dry weight)−1 of arsenic from solutions containing 4.0 μM of either arsenate and DMAA in phosphate deficient conditions, respectively. Thus, it is reasonable to state that increasing phosphate concentration in culture solutions decreased the arsenic uptake into the water fern significantly, when the source was arsenate. Moreover, arsenic and phosphate content in plant tissue correlated significantly (r = −0.66; p 0.05). Similarly, significant correlation was observed between arsenic and iron content in plant tissues (r = 0.66; p