Related Experiment Video
Updated: Jul 13, 2026

Aerobic Biodegradation Testing of Materials Using a Natural Marine Seawater Inoculum and Closed Loop Respirometer
Published on: October 24, 2025
Photodegradation of natural organic matter from diverse freshwater sources
Anna R Winter1, Terry Anne E Fish, Richard C Playle
1Wilfrid Laurier University, Department of Biology, Waterloo, Ontario, Canada N2L 3C5.
Abstract:
Natural organic matter (NOM) is significant in determining fate, transport and toxicity of metals in aqueous systems but NOM is not a static component; NOM can undergo photochemical changes in chemical structure. These changes will modify NOM quality and in turn influence how metals are transported in the environment, as well as their toxicity to aquatic organisms. Natural organic matter was collected from five freshwater sources using a portable reverse osmosis unit, diluted to about 10 mg CL(-1), then exposed for 13 days to summer temperatures either in the dark or exposed to sunlight. Light exposed NOM had decreases in total organic carbon (TOC) of 8-35% compared to samples kept in a refrigerator (dark, 4 degrees C), and the NOM became optically lighter, as shown by specific absorbance coefficients (SAC) taken at 340 nm (55-76% decreases in SAC(340)). In contrast, dark exposed NOM showed much smaller decreases in TOC (< or = 3%) or SAC(340) (=32%). For light exposed samples fluorescence excitation-emission matrix spectroscopy showed loss of fluorescence mainly in the 330 nm excitation, 420-450 nm emission range, consistent with loss of fulvic- and humic-like, aromatic groups in the NOM. Commercial (Aldrich) humic acid showed similar changes when exposed to light, with decreases in fulvic and humic fluorescence peaks. Finely ground fish food, used as a source of protein-rich organic matter, showed similar decreases in TOC and SAC(340) when exposed to light, but showed increased SAC(340) in the foil wrapped samples, presumably because bacteria were involved in decomposition of the food organic matter. Overall, these results indicate photodegradation of terrestrially derived, aromatic functional groups (e.g., from lignin) in natural organic matter from various freshwater sources.
More Related Videos
05:46Identification of Pharmaceuticals in The Aquatic Environment Using HPLC-ESI-Q-TOF-MS and Elimination of Erythromycin Through Photo-Induced Degradation
Published on: August 1, 2018
09:38Single-throughput Complementary High-resolution Analytical Techniques for Characterizing Complex Natural Organic Matter Mixtures
Published on: January 7, 2019
Related Concept Videos
Freshwater Microbial Ecology
Microbial Wastewater Treatment
Bioremediation
Microbial Bioremediation of Hydrocarbons
Microbial Bioremediation of Pesticides
Biodeterioration