Trifluralin, a dinitroaniline herbicide, is used to control annual grasses and broadleaf weeds. It has been banned in the EU since 2008. It is still sold in the US, however, where it is combined into consumer-grade mulch products. Since fall 2014, students at Hofstra have been working to characterize the environmental impacts of these trifluralin-amended mulches and to estimate their contribution to overall trifluralin loading in suburban environments. So far, the storm water pollution potential has been characterized through the leaching of trifluralin from amended mulch under simulated storm events and was found to be consistently above minimum reported chronic toxicity endpoints. Students have evaluated the hormonal activity of trifluralin, trifluralin-amended mulch, and mulch leachate using the BLYES and BLYAS reporter systems and found trifluralin to be a moderately potent endocrine disrupter with weakly estrogenic and moderately adrenergic activity (comparable to recently banned plastering agent bisphenol-a). More recently, by conducting a mass balance on total trifluralin in amended mulch products, we have found evidence of unique transformation products, and also evidence of irreversible sorption onto mulch surfaces. Last year we studied the photolysis of trifluralin in acetonitrile in order to assess the potential environmental and eco toxic impacts of the herbicide. Within this year, further analysis was done on the trifluralin in acetonitrile data in order to quantify transformation products and a ferioxalate actinometry experiment was conducted in order to determine the light intensity of the Eye Optics Solarlux 600W full spectrum solar simulation array. Over the summer, we conducted two separate investigations of transformation, one in water and one on thin layers (~3 mm) of mulch sealed between Pyrex sheets and teflon gaskets to control moisture. We also quantified degradation rates for trifluralin the parent, and attempted to identify the evolution of transformation products upon derivatization with BSTFA and MBTFA using gas chromatography and mass spectrometry.

Photolysis of the suburban-use herbicide trifluralin on retail mulch surfaces

253rd National Meeting (2017)

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