The Control of Fe and pH on the Photodegradation and Characterization of Dissolved Organic Matter in Small, Oligotrophic Canadian Shield Freshwaters

• Main Author: Mead, Jennifer
• Format: Master Thesis
• Language: English
• Published: University of Waterloo 2017
• Subjects: Dissolved Organic Matter; Photodegradation; DOM Characterization; Dillon; Molot; Ocean acidification
• Online Access: http://hdl.handle.net/10012/11942

Carbon is an essential building block for life and is involved in many biotic and abiotic processes. Thus it is imperative to have a comprehensive understanding of carbon cycling. Recent research has established that inland lakes are important contributors to the regional carbon cycle because they store, process and emit large masses of carbon over relatively short timescales (ie. days to years). Lakes receive 1.9 Pg C y-1 of terrestrially-derived carbon but only export approximately half of that to oceans while the remainder is either transferred to the sediment as particulate organic carbon (POC) or evaded to the atmosphere as carbon dioxide (CO2; Molot and Dillon, 1996; Cole et al. 2007). Increased atmospheric CO2 has caused global environmental problems including ocean acidification, temperature increases leading to melting glacial ice and sea level rise, and changes in precipitation patterns including extreme weather resulting in flooding and droughts. Investigating the mechanisms that affect these processes is important for understanding the global carbon cycle and predicting future changes to the lake systems under the stress of climate change. As the largest input of terrestrial carbon to lakes, dissolved organic carbon (DOC) (composed of a complex mixture of thousands of different organic molecules less than 0.1-0.7μm) is important to lake ecosystem function. Large quantities of DOC are converted into other forms of carbon within lakes and some of the transport mechanisms between sources and sinks do not add up. Photodegradation of DOC is an important abiotic process for DOC loss. Products of DOC photodegradation including POC, dissolved organic carbon (DIC; can evade to the atmosphere as CO2), and photolytically altered DOC affect the size of carbon pools in lakes. Concomitantly, pH and Fe can influence the rates of carbon transformation, yet these influences are poorly understood. The goal of my research was to explain an important gap in our understanding of why some carbon goes to the atmosphere as ...