River influences on air-sea exchange of CO2 and carbon system dynamics in Canadian subarctic coastal waters

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The Arctic Ocean plays a disproportionally large role in the uptake of atmospheric CO2. This is due in part to the high CO2 solubility in its cold waters, and physical and biological processes associated with an expansive ocean area underlain by continental shelf. The Arctic Ocean is losing sea ice and is freshening through the combination of increased sea melt and river inflow. We are uncertain as to how these changes will impact the ocean's role as a strong CO2 sink. The Arctic Ocean receives an enormous amount of freshwater and carbon (both organic and inorganic) from rivers and the carbon delivery has a very strong influence on regional carbon cycles. This is because much the organic carbon received from rivers is converted to CO2 (CO2 partial pressure, pCO2w) by biological processes.  River water in the marine system also has the tendency to reduce the seawater's pH and increase in the water's solubility for calcium carbonate. It does this because it has a lower total alkalinity (TA), or buffering capacity. As the solubility increases in water, the saturation state (O) for the calcium carbonate decreases. The combination of these processes (lower pH and lower saturation state) leads to ocean acidification (OA). Many organisms produce types of calcium carbonate for shells and skeletons, and if the seawater becomes undersaturated in calcium carbonate, it will be more difficult for the organisms to produce shells, and/or their shells can dissolve. Hence intensifying ocean acidification can negatively impact the marine ecosystem. The underlying thread of my research is to understand the carbon cycle of coastal waters in the Canadian Arctic. The research that I propose has three objectives, namely: (i) Understand how, and the extent to which pCO2w, DIC, TA, and O evolve in estuaries from river to ocean; (ii) Characterize spatial patterns in the air-sea CO2 flux and OA within a shelf sea and understand what physical and biological processes contributed to the observed variability; (iii) Develop parameterizations for pCO2w, DIC, TA that are shown to be suitable for application in biogeochemical models for coastal waters. Research will be conducted in Hudson and James Bay (hereafter HBC), and will involve the sampling of water in rivers, along estuaries and in the adjacent coast ocean. Water samples will be analysed for  water carbon chemistry. The program will provide opportunity for 6 students, 3 PhD, and 3 MSc students. Research associated with my objectives will allow my students and I to quantify the role of rivers on contemporary and future inorganic carbon systems of the HBC, including its CO2 source/sink and status and progression of OA. Because of its potential impacts on marine ecosystem, OA represents a potential threat to food security. Information resulting from this program will be invaluable to federal and provincial policy-makers, as well as territorial and co-management bodies.