High-frequency variability of CO 2 in Grand Passage, Bay of Fundy, Nova Scotia

• Published in: Biogeosciences
• Main Authors: R. M. Horwitz, A. E. Hay, W. J. Burt, R. A. Cheel, J. Salisbury, H. Thomas
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2019
• Subjects: Ecology; QH540-549.5; Life; QH501-531; Geology; QE1-996.5; Northwest Atlantic; Ocean acidification
• Online Access: https://doi.org/10.5194/bg-16-605-2019; https://doaj.org/article/452e5294e4564056a9640c3d59871f03

Assessing changes in the marine carbon cycle arising from anthropogenic CO 2 emissions requires a detailed understanding of the carbonate system's natural variability. Coastal ecosystems vary over short spatial and temporal scales, so their dynamics are not well described by long-term and broad regional averages. A year-long time series of p CO 2 , temperature, salinity, and currents is used to quantify the high-frequency variability of the carbonate system at the mouth of the Bay of Fundy, Nova Scotia. The seasonal cycle of p CO 2 is modulated by a diel cycle that is larger in summer than in winter and a tidal contribution that is primarily M2, with amplitude roughly half that of the diel cycle throughout the year. The interaction between tidal currents and carbonate system variables leads to lateral transport by tidal pumping, which moves alkalinity and dissolved inorganic carbon (DIC) out of the bay, opposite to the mean flow in the region, and constitutes a new feature of how this strongly tidal region connects to the larger Gulf of Maine and northwest Atlantic carbon system. These results suggest that tidal pumping could substantially modulate the coastal ocean's response to global ocean acidification in any region with large tides and spatial variation in biological activity, requiring that high-frequency variability be accounted for in assessments of carbon budgets of coastal regions.