CO2 and O2 variability in the partially ice-covered Arctic Ocean

• Main Author: Islam, ASM F
• Format: Thesis
• Language: unknown
• Published: University of Montana 2015
• Subjects: CO2; O2; variability; Arctic; Ocean; Arctic Ocean; Canada; canada basin; Ocean acidification
• Online Access: https://scholarworks.umt.edu/etd/4537; https://scholarworks.umt.edu/context/etd/article/5568/viewcontent/auto_convert.pdf

Limited carbon cycle research has been conducted so far in the Arctic Ocean (AO) compared to many other open-ocean and coastal environments, with relatively few studies of the inorganic carbon cycle and air-sea gas exchange. Understanding these processes in depth and understanding the physical, chemical, and biological processes that control carbon dioxide (CO2) and dissolved oxygen (DO) variability in the AO are crucial to predicting the future of the carbon cycle in the region and its impact on greenhouse gases and marine ecosystem processes, such as ocean acidification. To study the AO carbon cycle, in situ time-series data have been collected from the Canada Basin of the AO during late summer to autumn of 2012. Partial pressure of CO2 (pCO2), DO concentration, temperature, salinity, and chlorophyll-a fluorescence (Chl-a) were measured at 6-10 m depth under little ice and multi-year ice on two drifting platforms. The pCO2 levels were always below atmospheric saturation, whereas the seawater was almost always slightly supersaturated with respect to DO. Although the two time-series data were on an average only 222 km apart they had 10 ± 10% and 63 ± 16% ice cover and differed significantly in contributions from gas exchange and net community production (NCP). Modeled variability of CO2 and DO suggest that gas exchange, NCP and horizontal gradients are the main sources of the CO2 and DO variability in the partially ice-covered AO. Horizontal gradients dominated the more densely ice-covered region, with no significant NCP in the surface. These results suggest that the signature imparted on CO2 and DO in open water is widely disbursed under-ice and that biological production under multi-year ice is negligible due to lack of light and nutrients.