Using continuous flow aquaria or static beakers and mixed biota communities, the fate and effects of atrazine were determined and the resilience of the systems after the removal of the compound were evaluated. In addition, the response of the different test systems to the herbicide were compared. Degradation and sorption of atrazine was low in the aquatic systems. The compound had a negative impact on primary producers at and above a concentration of 50 micrograms/L and possibly below. These effects were expressed best in oxygen production and dissolved nitrate in the systems. Results demonstrated that small static systems can furnish results similar to those of larger more complex systems, particularly for quick response parameters.