Biogeochemistry of dissolved gallium and lead isotopes in the northeast Pacific and western Arctic Oceans

• Main Author: McAlister, Jason
• Format: Thesis
• Language: English
• Published: University of British Columbia 2015
• Subjects: Arctic; Arctic Ocean; Pacific; North Atlantic
• Online Access: http://hdl.handle.net/2429/53506

This thesis presents novel applications of dissolved Ga and Pb isotope ratios as oceanographic tracers of biogeochemical cycling and trace metal input mechanisms in the northeast Pacific Ocean, the Columbia River plume, and the Western Arctic Ocean. Conclusions of this thesis are based on the first multi-year transect of dissolved Ga in the northeast Pacific Ocean along Line P, the first dissolved Ga concentrations reported in the Arctic Ocean, and the first Line P transect of Pb isotope ratios. This thesis introduces 5 new tracer applications contributing to oceanographic research, dissolved Ga traces: 1) advective inputs of trace metals in the northeast Pacific, 2) Pacific and Atlantic source waters in the western Arctic, and 3) plume transport of the Columbia River, Ga/Pb traces: 4) fluvial freshwater inputs, and Pb isotope ratios trace: 5) geographically and temporally distinct trace metal inputs to the northeast Pacific. Dissolved Ga is positively correlated with the variable spice, interpreted to trace advective trace metal inputs from the California Undercurrent and North Pacific Intermediate Waters bisecting the Line P transect. This thesis identifies the Ga/Pb ratio as a tracer of an interface along Line P of fluvial trace metal inputs. Isotopic ratios of Pb trace eolian Asiatic and fluvial North American sources, identifying a front of differential trace metal inputs along Line P. Dissolved Ga is identified as a conservative tracer of Pacific waters in the Arctic and applies the conservative nature of dissolved Ga to interpretation of calculated rates of nitrogen fixation within shallow waters of the Beaufort Gyre, impacting phosphate concentrations and ecosystems in both the Arctic and North Atlantic Oceans. Finally, dissolved Ga traces conservative and non-conservative behaviour under upwelling and downwelling conditions associated with the dynamic Columbia River plume. This thesis contributes the five tracer applications described above to interpretation of trace metal inputs and advection in the northeast Pacific Ocean and source waters and nitrogen and phosphate coupling in the western Arctic Ocean. Science, Faculty of Earth, Ocean and Atmospheric Sciences, Department of Graduate