Dissolved Organic Matter in Subarctic Streams and Rivers: Direct and Proxy Measures of Quantity, Quality, and Mercury

• Main Author: Despault, Tara M
• Format: Text
• Language: English
• Published: Scholarship@Western 2016
• Subjects: Hudson Bay Lowlands; Dissolved Organic Matter (DOM); Mercury; Spatial Variability; Seasonal Variability; Spectroscopy; Biogeochemistry; Hydrology; Hudson; Hudson Bay; Subarctic
• Online Access: https://ir.lib.uwo.ca/etd/3652; https://ir.lib.uwo.ca/context/etd/article/5141/viewcontent/DespaultT_MScThesis2016_SGPS_Final_NoTitle.pdf

The drainage network of the Hudson Bay Lowlands (HBL) peatland complex regulates the transport of freshwater and solutes, including dissolved organic matter (DOM) and mercury, to Hudson Bay. Due to the remoteness and areal extent of the HBL, traditional, campaign-based sampling programs are unable to fully elucidate the region’s hydrology and biogeochemistry. This study investigated seasonal variability of DOM quantity and quality in two distinct stream orders to explore DOM sources to surface waters in the region, and assessed optical measurements as proxies for riverine DOM and mercury. In-stream primary production and enhanced microbial processing influenced DOM characteristics during base flow and negatively impacted mercury-DOM relationships in the higher order river. These autochthonous DOM sources reflected in-stream processes and not peatland-derived carbon, as were characteristic of the lower order stream. Optical measurements varied in their effectiveness as proxies depending on DOM source (e.g., groundwater and primary production) and concentration (peat-dominated streams).