Understanding estuarine acidification: the dissolved inorganic carbon to total alkalinity ratio in the Chesapeake and Delaware Bays

Cai, Wei-JunThough ocean acidification is well-documented, the nature of estuarine chemistry and the lack of high quality inorganic carbon data for most estuaries create a number of problems for scientists and managers seeking to answer the question of whether and how estuaries are acidifying and what is causing the change. Even when researchers document acidification, the existing regulatory system can be ill-suited to address the threat. In response to the gap in estuarine acidification research and policy, this dissertation uses the dissolved inorganic carbon (DIC) to total alkalinity (TA) ratio to address technical, conceptual and management challenges. Through conducting the first complete main stem Chesapeake Bay inorganic carbon study, I was able to establish baseline information about spatial and seasonal variability. The strength of the relationship between DIC/TA and pH in both the Chesapeake and Delaware Bays allowed me to model pH that differed less from the observed pH than traditional thermodynamic calculations, bypassing errors related to unknown organic acids and bases or inaccurate K1 and K2 equilibrium constants. Finally, I designed three methods for applying DIC/TA and the ratio method as estuarine management tools to the Chesapeake and Delaware Bays, allowing for quantification of relative vulnerability across time and space. These uses of the DIC/TA ratio provide novel, observation-based methods to monitor and compare estuarine acidification vulnerability at the local scale and address unmet managerial needs.University of Delaware, School of Marine Science and PolicyPh.D