A Negative Effect of Co-solvent on Atrazine Biodegradation in Experimental River Microcosms

TLDR: In this paper, a 0.1% concentration of acetonitrile as a co-solvent greatly suppressed the microbial degradation of herbicide atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino]-s-triazine] throughout the experimental period (84 days).

Abstract: A water-miscible solvent, such as acetone, acetonitrile or methanol, is often employed as a co-solvent to dissolve an organic test chemical of low water solubility in an environmental fate study using a laboratory model microcosm. These co-solvents, however, may disrupt the microflora in the water/sediment tested, and affect the biodegradation of the target compound. In the present study, a 0.1% concentration of acetonitrile as a co-solvent greatly suppressed the microbial degradation of herbicide atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] throughout the experimental period (84 days). The rapid growth of specific microbes was considered to deprive atrazine-degrading microbes of their habitat (mainly the surface area of sediment particles) in the microcosm.