Phytotransformations of perchlorate contaminated waters

Six vascular plant species (sweet gum, black willow, pickleweed, smartweed, water-lily and duckmeat) were used to determine the uptake and transformat ion of perchlorate at three concentrations (0.2, 2.0, and 20.0 mgl(-1)) for 10 days under laboratory conditions. Perchlorate uptake followed a first-o rder reaction, with rate constants ranging between 0.001 to 0.007 h(-1). Ac cumulation of perchlorate was between 0 to 981 mg kg(-1) of plant weight fo r various plants. Based on the results the accumulation of perchlorate was in the order: smartweed > pickleweed > sweet gum > water-lily > willow. Ana lysis of plant tissues (roots, stems, and leaves) confirmed the presence of transformation products, chlorate, chlorite and chloride. The distribution of perchlorate and its products indicate that the transformation reaction occurred in each tissue independently of the other and accumulation of bypr oducts was significantly higher in leaves than in roots or stem. No externa l signs of perchlorate toxicity were observed at these high concentrations in plant tissues suggesting that these plant species show potential for phy toremediation.