The increase of anthropogenic carbon dioxide (CO2) has decreased seawater pH and carbonate mineral saturation state, a process known as ocean acidification (OA), which threatens the health of organisms and ecosystems. In estuaries and coastal hypoxic waters, anthropogenic CO2-induced acidification is enhanced by intense respiration and weak acid–base buffer capacity. Here I provide a succinct review of our state of knowledge of drivers for and biogeochemical impacts on estuarine acidification. I will review how river–ocean mixing, air–water gas exchange, biological production–respiration, anaerobic respiration, calcium carbonate (CaCO3) dissolution, and benthic inputs influence aquatic acid–base properties in estuarine waters. I will emphasize the spatial and temporal dynamics of partial pressure of CO2 (pCO2), pH, and calcium carbonate mineral saturation states (Ω), with examples from the Chesapeake Bay, the Mississippi River plume and hypoxic zone, and other estuaries to illustrate how natural and anthropogenic processes may lead to estuarine and coastal acidification.
Cai W.-J., 2023. Estuarine acidification under a changing climate. In: Kennish M. J., Paerl H. W. & Crosswell J. R. (Eds.), Climate change and estuaries, pp. 171-182. Boca Raton: CRC Press. Book chapter (restricted access).
