Spatial and temporal dynamics of biogeochemical processes in the Fraser River, Canada : a coupled organic-inorganic perspective
Citable URI
https://hdl.handle.net/1912/6919Location
Fraser River, CanadaSouthwestern Canada
DOI
10.1575/1912/6919Keyword
Biogeochemical cycles; Organic compoundsAbstract
The great geologic and climatic diversity of the Fraser River basin in southwestern Canada render it an excellent location for understanding biogeochemical cycling of sediments and terrigenous organic carbon in a relatively pristine, large, temperate watershed. Sediments delivered by all tributaries have the potential to reach the ocean due to a lack of main stem lakes or impoundments, a unique feature for a river of its size. This study documents the concentrations of a suite of dissolved and particulate organic and inorganic constituents, which elucidate spatial and temporal variations in chemical weathering (including carbonate weathering in certain areas) as well as organic carbon mobilization, export, and biogeochemical transformation. Radiogenic strontium isotopes are employed as a tracer of sediment provenance based on the wide variation in bedrock age and lithology in the Fraser basin. The influence of sediments derived from the headwaters is detectable at the river mouth, however more downstream sediment sources predominate, particularly during high discharge conditions. Bulk radiocarbon analyses are used to quantify terrestrial storage timescales of organic carbon and distinguish between petrogenic and biospheric organic carbon, which is critical to assessing the role of rivers in long-term atmospheric CO2 consumption. The estimated terrestrial residence time of biospheric organic carbon in the Fraser basin is 650 years, which is relatively short compared to other larger rivers (Amazon, Ganges-Brahmaputra) in which this assessment has been performed, and is likely related to the limited floodplain storage capacity and non-steady-state post-glacial erosion state of the Fraser River. A large portion of the dissolved inorganic carbon load of the Fraser River (>80%) is estimated to derive from remineralization of dissolved organic carbon, particularly during the annual spring freshet when organic carbon concentrations increase rapidly. This thesis establishes a baseline for carbon cycling in a largely unperturbed modern mid-latitude river system and establishes a framework for future process studies on the mechanisms of organic carbon turnover and organic matter-mineral associations in river systems.
Description
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2014
Collections
Suggested Citation
Thesis: Voss, Britta M., "Spatial and temporal dynamics of biogeochemical processes in the Fraser River, Canada : a coupled organic-inorganic perspective", 2014-09, DOI:10.1575/1912/6919, https://hdl.handle.net/1912/6919Related items
Showing items related by title, author, creator and subject.
-
Biogeochemical relationships between ultrafiltered dissolved organic matter and picoplankton activity in the Eastern Mediterranean Sea
Meador, Travis B.; Gogou, Alexandra; Spyres, Georgina; Herndl, Gerhard J.; Krasakopoulou, Evangelia; Psarra, Stella; Yokokawa, Taichi; De Corte, Daniele; Zervakis, Vassilis; Repeta, Daniel J. (2009-12-10)We targeted the warm, subsurface waters of the Eastern Mediterranean Sea (EMS) to investigate processes that are linked to the chemical composition and cycling of dissolved organic carbon (DOC) in seawater. The apparent ... -
Hydrological and biogeochemical controls on absorption and fluorescence of dissolved organic matter in the northern South China Sea
Wang, Chao; Guo, Weidong; Li, Yan; Stubbins, Aron; Li, Yizhen; Song, Guodong; Wang, Lei; Cheng, Yuanyue (John Wiley & Sons, 2017-12-29)The Kuroshio intrusion from the West Philippine Sea (WPS) and mesoscale eddies are important hydrological features in the northern South China Sea (SCS). In this study, absorption and fluorescence of dissolved organic ... -
Biogeochemical applications of compound-specific radiocarbon analysis
Pearson, Ann (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1999-10)Compound-specific carbon isotopic (δ13C and Δ14C) data are reported for lipid biomarkers isolated from Santa Monica Basin (SMB) and Santa Barbara Basin (SBB) surface sediments. These organic compounds represent ...