Negative environmental consequences of fossil fuel use and concerns about the security of petroleum supplies have led to the implementation of policies to increase the use of renewable energy. In the effort to promote ethanol/gasoline blends as an alternative fuel, potential negative impacts on the environment have been overlooked. Ethanol is mainly produced from corn in the Midwest and then transported to the coasts to be mixed with gasoline. With the increased usage and the long distances of transport, a spill is reported on the average of every two days. Moreover, currently, the U.S. (specifically the Midwest and the Central Valley in California) heavily depends on the use of pesticides for crop production (<i>e.g.,</i> production of corn), contaminating the agricultural watersheds. The coincidence of ethanol spills and high pesticide usage in agricultural watersheds raises the concern that ethanol might enhance the concentration of regulated organochlorine pesticides in surface waters. Thus, this research addresses the food-energy-water nexus by assessing the potential impact on surface water quality, specifically the fate of organochlorine pesticides, following an ethanol/ethanol-blend fuel spill along agricultural/urban watersheds. Measurements show that the aqueous solubility of organochlorine pesticides may increase by three to seven orders of magnitude in the presence of ethanol. The relationship between the aqueous solubility of the pesticides and the ethanol mass fraction can be described by a two-part log-linear model, with the breakpoint occurring at an ethanol mass fraction of approximately 0.35 for the pesticides examined. The solubility relationship is heavily influenced by cosolvent-solvent interactions, with the breakpoint occurring due to a shift in these interactions, and consequently in the solubilization mechanism. The enhancement in the aqueous solubility of organochlorine pesticides by the presence of ethanol can affect other properties that influence the mobilization of such pesticides in the water column. For example, in the presence of an organic liquid, like gasoline, the aqueous solubility enhancement may affect the partitioning behavior of the pesticides between the organic liquid and the aqueous phase.

Impact on surface water quality due to the enhanced solubility of organochlorine pesticides following an ethanol-blend fuel spill

255th National Meeting (2018)

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