Atrazine Removal Using Aquatic Plants: A Kinetic Approach

Aquatic and terrestrial plants and microorganisms were screened to test their ability to remove the herbicide, atrazine, from the environment. Plants included hornwort (Ceratophyllum demersum), switchgrass (Panicum virgatum), reed canarygrass (Phalarius arundinacea), annual ryegrass (Lolium multiflorum), and two varieties ofperennial ryegrass (Lolium perenne). Microorganisms studied included a fungus of the genus Penicillium and an uncharacterized sample ofneuston (floating microbial community) dominated by green algae. The atrazine­ metabolizing fungus was found to afford a variety of as yet uncharacterized degradation products. An aquatic plant, hornwort, was found to take up atrazine from dilute aqueous solution (50 fJ.g/L, 0.23 fJ.M), a concentration typical of spring runoff in the northern United States. The rate of uptake was light-dependent, and even in the absence ofplants atrazine was lost, due to induced photochemical reactions initiated by nitrate and an iron (III) complex in the nutrient solution used in the experiments. Breakdown products of atrazine in the presence ofplants included deethylatrazine, deisopropylatrazine, and a glutathione conjugate of atrazine. Hydroxyatrazine was not detected. Autoradiography indicated that labeled material largely remained within the plant cells, indicating that microorganisms played a minor role in the disappearance ofatrazine. The deethyland deisopropyl derivatives were also formed by photochemical processes in the absence ofplants.