RUI: Photochemical Pathways and Photoproducts of Current and Emerging Sub-Arctic Aquatic Contaminants

University Of Alaska Anchorage Campus, Anchorage AK

Investigators

Abstract

This award is jointly funded by the Environmental Chemical Science Program in the Chemistry Division and the Established Program to Stimulate Competitive Research (EPSCoR). Drs. Tomco and Redman at the University of Alaska-Anchorage will investigate the environmental breakdown rates of three contaminants found in Alaskan waterways, as caused by sunlight. The mechanism of this process can be unique to cold, high-latitude regions, where extreme seasonal changes in daily sunlight exposure occur. Several factors that affect this process will be investigated, including the role of natural organic matter, reactive oxygen species, and temperature dependence. The breakdown products formed as each contaminant degrades will be identified. This study is expected inform the development of predictive water quality assessments that can be useful for identifying the attenuation rates in these systems. The project will engage undergraduate and graduate students in research, provide opportunities to learn advanced instrumental methods in mass spectrometry, and target inclusion of Alaska Native students and women to work toward broadening participation in such physical science studies. This study will investigate the aquatic photochemical pathways by which emerging contaminants in the sub-Arctic are degraded and the extent to which high latitude environmental factors will impact persistence. Subarctic environmental conditions have a unique timeline of contaminant attenuation compared to temperate conditions, and a unique relative contribution of direct and indirect processes. This study specifically assesses three priority compounds: 12α-hydroxy-rotenone, 6-PPD quinone, and fluridone. 6-PPD quinone is the quinonoid oxidation product from oxidation of N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, a widely used tire additive and anti-oxidant. Each of these have recently been detected persistently in Alaskan waterways, but no information exists regarding photochemical pathways and photo-transformation products in natural waters. This study will determine individual contributions of dissolved organic matter, hydroxyl radicals, singlet oxygen, and triplet excitation states. The temperature dependence of each process will be compared at 4, 12, and 20 degrees C, which spans the typical range of surface water temperatures. Photoproducts resulting from each process will be profiled using high resolution mass spectrometry combined with non-targeted analytical approaches. This information is expected to provide a better fundamental understanding of the environmental drivers for these photochemical processes. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.