THE CONTRIBUTION OF NITRATE IN AGRICULTURAL RUNOFF TO THE SENSITIZED PHOTOCHEMICAL DEGRADATION OF ATRAZINE

Atrazine is a common agricultural herbicide that is soluble in water and persists due to its slow microbial degradation in surface water. The purpose of this study is to analyze the importance of an agricultural co-contaminant, nitrate, on the photochemical degradation of atrazine. Nitrate is photochemcially active and can sensitize the degradation of organic molecules, such as atrazine, by producing hydroxyl radicals upon light absorption. Water samples were gathered and filtered from four different agricultural streams in one day and characterized by pH, turbidity, dissolved organic carbon (DOC), and fluorescence (excitation emission matrices; EEMs). Samples would be spiked with various concentrations of nitrate and a known concentration of atrazine to observe how the chemical degrades upon irradiation. A set of control experiments of atrazine in DI water with nitrate at various concentrations and one experiment with no nitrate present were used to evaluate the influence of nitrate alone. From the measured change in concentrations, the rate of decay and half life of atrazine were calculated. These results will allow a better understanding of how atrazine degrades in different bodies of water based on the surrounding environment and sunlight exposure.