Arsenic Uptake by Aquatic Macrophyte Spirodela polyrhiza L.: Interactions with Phosphate and Iron 1 2 3 4 5 6

The uptake of arsenate (As(V)) and dimethylarsinic acid (DMAA) by aquatic macrophyte Spirodela polyrhiza L. was investigated to determine the influence of arsenic interaction with PO43- and Fe ions. Plants were grown hydroponically on standard Murashige and Skoog (MS) culture solutions. Arsenic concentrations in Fe-oxide (Fe-plaque) on plant surfaces were determined by citrate-bicarbonate-ethylenediaminetetraacetic acid (CBE) technique. Spirodela polyrhiza L. accumulated 51-fold arsenic from arsenate solution compared to that from DMAA solution with initial concentrations of 4.0 and 0.02 µM of arsenic and phosphate, respectively. The arsenate uptake was negatively (p < 0.001) correlated with phosphate uptake and positively (p < 0.05) correlated with iron uptake. About 56 % of the total arsenic was accumulated into the plant tissues while 44 % was adsorbed on Fe plaque (CBE-extract), when the plants were grown on arsenate solution. The DMAA uptake into the plant was neither affected by the phosphate concentrations no