INFLUENCE OF ENVIRONMENTAL FACTORS ON THE COMPOSITION AND FATE OF CUPRIC OXIDE (CuO) DERIVED OXYDATION PRODUCTS OF DISSOLVED ORGANIC MATTER (DOM)

Thawing permafrost and increased river discharge are releasing carbon, including lignins into Arctic rivers and coastal waters. Hudson and James Bays, at the southern edge of the Canadian Arctic, rank among the fastest-warming regions globally, making it critical to examine how environmental changes affect the composition and fate of dissolved organic matter (DOM). Lignin phenols, derived from the breakdown of terrestrial vascular plants, are molecularly diverse compounds used as biomarkers to trace DOM transformation and watershed vegetation. They are extracted via alkaline CuO oxidation and quantified using liquid chromatography coupled with high-resolution mass spectrometry. This study investigates the bio- and photo resistance of lignin phenols and CuO-derived oxidation products in surface DOM from the Moose and Winisk River outflows into Hudson and James Bays. Short-term in situ incubations (3 days) revealed that lignin phenol concentrations decreased under light (0.3%) but increased with microorganisms (0.7%). Conversely, fatty acid-like products rose under light (+3.8%), indicating photoresistence, while lignin phenols were photosensitive. Microorganisms caused fatty acid-like products to vary by +4.1% and -3.5%, suggesting production or consumption. Overall, lignin phenols were biorefractory, while fatty acid-like compounds responded to microorganisms depending on their DOM source. These findings highlight that the chemical properties of lignin phenols and CuO-derived oxidation products can be altered by environmental factor such as light and microbial activities.

Presentation Preference: Standard Oral (12 Minutes)

Primary Presenter: Magali Pucet, Université de Sherbrooke (magali.pucet@usherbrooke.ca)

Authors:

Magali Pucet, Université de Sherbrooke  (magali.pucet@usherbrooke.ca)

Céline Guéguen, Université de Sherbrooke  (celine.gueguen@usherbrooke.ca)