Influence of algae on amitrole and atrazine residues in water

Removal of [14C]amitrole (3-amino-s-triazole) from water by three algae was more complete at pH 7.5 or above than at lower pH levels. [14C]atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine) removal was affected little by pH. Absorption of [14C]amitrole steadily increased over 24 h, whereas [14C]atrazine removal reached equilibrium by 6 h. [14C]amitrole removal by Scenedesmus quadricauda was directly related to herbicide concentration while [14C]atrazine removal was inhibited by increasing concentrations. Optimum light and temperature for algal growth favored [14C]amitrole uptake. [14C]atrazine removal was unaffected by either darkness or low temperature. [14C]atrazine was not metabolized by Scenedesmus and apparent photosynthesis was inhibited in the four algae. Growth of algae was prevented by 1 ppm by weight atrazine. [14C|amitrole was readily metabolized by Scenedesmus. Three 14C metabolites were extracted from cells while four chromatographically different 14C metabolites occurred in the suspension fluid. Growth of Chlamydomonas reinhardti was particularly resistant to amitrole.