AbstractThe uptake of anthropogenic carbon dioxide (CO2) from the atmosphere has resulted in a decrease in seawater aragonite saturation state (Ωarag), which affects the health of carbonate‐bearing organisms and the marine ecosystem. A substantial short‐term variability of surface water Ωarag, with an increase of up to 0.32, was observed in the central Mid‐Atlantic Bight off the Delaware and the Chesapeake Bays over a short period of 10 days in summer 2015. High‐frequency underway measurements for temperature, salinity, percentage saturation of dissolved oxygen, oxygen to argon ratio, pH, fCO2, and measurements based on discrete samples for pH, dissolved inorganic carbon, and total alkalinity are used to investigate how physical and biogeochemical processes contribute to the changes of Ωarag. Quantitative analyses show that physical advection and mixing processes are the dominant forces for higher Ωarag in slope waters while biological carbon removal and CO2 degassing contribute to increased Ωarag in shelf waters.
