A Biogeochemical Perspective on Acidification and Buffering Capacity in the Piscataqua Estuary

Coastal ecosystems are particularly vulnerable to the impacts of ocean acidification, and our understanding of the carbon system in these environments requires further exploration. The buffering capacity, the ocean’s ability to resist changes in pH, can be altered by both physical and biogeochemical processes. The correlation between changes in four biogeochemical processes (i.e., sulfate reduction, nitrification, denitrification, carbonate dissolution) and changes in seawater carbon system parameters (i.e., pH, dissolved inorganic carbon, and total alkalinity) was investigated. These biogeochemical processes are hypothesized to be significant drivers of alterations to the seawater carbon chemistry in coastal regions, such as the Piscataqua Estuary. Two experiments were conducted, one month apart, to examine temporal variation. Sediment cores were collected at the UNH Marine Research Pier in New Castle, NH, which is near the water intake site for UNH’s Coastal Marine Laboratory (CML). The sediment cores were prepared at CML and incubated until oxygen concentrations in the overlying water declined to slightly above 3 mg/L. This approach excludes the influence of physical mixing (e.g., river-ocean mixing), a primary driver in altering the buffering capacity, to focus solely on biogeochemical processes. Gaining insight into the complex feedback loops associated with benthic biogeochemical processes and the carbon system parameters will facilitate more accurate predictions of how species respond to the effects of ocean acidification.

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Primary Presenter: Sanjana Varanasi, University of New Hampshire (sanjana.varanasi@unh.edu)

Authors:

Sanjana Varanasi, University of New Hampshire - Ocean Process Analysis Laboratory  (sanjana.varanasi@unh.edu)

Christopher Hunt, University of New Hampshire - Ocean Process Analysis Laboratory  (christopher.hunt@unh.edu)

Craig Tobias, University of Connecticut  (craig.tobias@uconn.edu)

Peter Ruffino, University of Connecticut  (peter.ruffino@uconn.edu)