Initial Transformation of Photo-Viable Free Amino Acids in the Presence of Surrogate and Standard Dissolved Organic Matter Under Sunlit Irradiation
Date of Award
Open Access Master's Thesis
Master of Science in Environmental Engineering (MS)
Administrative Home Department
Department of Civil and Environmental Engineering
Committee Member 1
Committee Member 2
With more than half of the nation’s drinking water affected by wastewater discharge from upstream and more indirect and direct reuse of treated wastewater, human health and ecotoxicological impacts resulting from effluent organic material (EfOM) will increase. Dissolved free amino acids (DFAAs), nitrogen components of EfOM, are essential nitrogen sources for microorganisms and play important roles in global N-cycling in natural aquatic environments. Several DFAAs including histidine, methionine, and tyrosine in sunlit surface waters are susceptible to direct and indirect photochemical transformation with reactive oxygen species. In this study, we investigated the reaction kinetics and initial reaction mechanisms involved in the fate of DFAAs through temperature-dependent bench-top photolysis experiments. Three prevalent surrogate DOM compounds were chosen (1,4-naphthoquinone, umbelliferone, 2-naphthaldehyde) which have been shown to be critical photosensitizers in the natural environment leading to the production of photochemically-produced reactive intermediates (PPRI) such as singlet oxygen (1O¬2), excited triplet state CDOM (3CDOM*), and hydroxyl radicals (HO•). All chosen surrogate DOM compounds and amino acids are structurally unique generating distinct degradation pathways of amino acids at three different temperatures (10 °C, 20 °C, 30 °C).
Kibler, Ryan J., "Initial Transformation of Photo-Viable Free Amino Acids in the Presence of Surrogate and Standard Dissolved Organic Matter Under Sunlit Irradiation", Open Access Master's Thesis, Michigan Technological University, 2020.