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

北冰洋对大气中二氧化碳的吸收起着不成比例的巨大作用。这部分是由于其冷水中二氧化碳的高溶解度，以及与大陆架下面的广阔海洋区域有关的物理和生物过程。北冰洋正在失去海冰，由于海水融化和河流流入的增加，海冰正在变新鲜。我们不确定这些变化将如何影响海洋作为一个强大的二氧化碳汇的作用。北冰洋从河流中接收了大量的淡水和碳（有机和无机），碳的输送对区域碳循环有很强的影响。这是因为从河流中吸收的大部分有机碳通过生物过程转化为二氧化碳（二氧化碳分压，pCO2w）。海洋系统中的河水也有降低海水pH值和增加水对碳酸钙溶解度的趋势。这是因为它的总碱度（TA）或缓冲能力较低。随着碳酸钙在水中溶解度的增加，碳酸钙的饱和状态（）降低。这些过程（较低的pH值和较低的饱和状态）共同导致海洋酸化（OA）。许多生物产生各种类型的碳酸钙用于贝壳和骨骼，如果海水中的碳酸钙不饱和，生物就很难产生贝壳，或者它们的贝壳会溶解。因此，海洋酸化加剧会对海洋生态系统产生负面影响。

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 () 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 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.