Senior Project Advisor

Landis, Wayne G.

Document Type


Publication Date

Spring 2013


Herbicide, Chemical runoff, Chemical mixtures


Herbicide use in agricultural systems often causes runoff to contain chemical mixtures that may have greater deleterious effects on non-target organisms than the same chemicals would have when found alone. Little information is known about how some of these chemicals act in mixtures, though many of their individual effects have been described. It is important to understand what effects these chemical mixtures have to identify protective application levels. In this experiment, a 21-day chronic Daphnia magna toxicity test was conducted using an atrazine and Roundup® mixture. Five concentrations of atrazine were tested (0.4, 0.8, 1.2, 1.6, 2.0mg/L). The mixture treatments contained the same concentrations of atrazine with a constant concentration of Roundup® (450mg/L, 2% glyphosate ). A spike in reproduction was observed at the lowest concentration of atrazine (0.4mg/L), with a subsequent decrease in reproduction with increasing concentration of atrazine. In the mixture the Roundup® control caused significantly reduced reproduction in the D. magna, though the combination of atrazine and Roundup® resulted in increased reproduction. Log linear regression analysis was used to predict overall trends in the treatments.


Environmental Sciences

Subjects - Topical (LCSH)

Herbicides--Toxicology; Atrazine; Glyphosate; Runoff; Daphnia magna--Effect of chemicals on


student projects; term papers




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