Redox reactions and weak buffering capacity lead to acidification in the Chesapeake Bay

• Published in: Nature Communications
• Main Authors: Cai, Wei-Jun, Huang, Wei-Jen, Luther, George W., III, Pierrot, Denis, Li, Ming, Testa, Jeremy, Xue, Ming, Joesoef, Andrew, Mann, Roger L., Brodeur, Jean, Xu, Yuan-Yuan, Chen, Baoshan, Hussain, Najid, Waldbusser, George G., Cornwell, Jeffery, Kemp, W. Michael
• Format: Text
• Language: unknown
• Published: W&M ScholarWorks 2017
• Subjects: DISSOLVED INORGANIC CARBON; OCEAN ACIDIFICATION; COASTAL WATERS; ANOXIC WATERS; RIVER ESTUARY; CO2 SYSTEM; BIOGEOCHEMICAL PROCESSES; INDUCED DESTRATIFICATION; MARINE ECOSYSTEMS; DIOXIDE SYSTEM; Fisheries Science Peer-Reviewed Articles; Marine Biology; Waters River; Ocean acidification
• Online Access: https://scholarworks.wm.edu/vimsarticles/7; https://scholarworks.wm.edu/context/vimsarticles/article/1006/viewcontent/Cai_et_al_2017_Nature_Communications.pdf

The combined effects of anthropogenic and biological CO2 inputs may lead to more rapid acidification in coastal waters compared to the open ocean. It is less clear, however, how redox reactions would contribute to acidification. Here we report estuarine acidification dynamics based on oxygen, hydrogen sulfide (H2S), pH, dissolved inorganic carbon and total alkalinity data from the Chesapeake Bay, where anthropogenic nutrient inputs have led to eutrophication, hypoxia and anoxia, and low pH. We show that a pH minimum occurs in mid-depths where acids are generated as a result of H2S oxidation in waters mixed upward from the anoxic depths. Our analyses also suggest a large synergistic effect from river-ocean mixing, global and local atmospheric CO2 uptake, and CO2 and acid production from respiration and other redox reactions. Together they lead to a poor acid buffering capacity, severe acidification and increased carbonate mineral dissolution in the USA's largest estuary.