Controls on surface water carbonate chemistry along North American ocean margins

Abstract

Syntheses of carbonate chemistry spatial patterns are important for predicting ocean acidification impacts, but are lacking in coastal oceans. Here, we show that along the North American Atlantic and Gulf coasts the meridional distributions of dissolved inorganic carbon (DIC) and carbonate mineral saturation state (Ω) are controlled by partial equilibrium with the atmosphere resulting in relatively low DIC and high Ω in warm southern waters and the opposite in cold northern waters. However, pH and the partial pressure of CO2 (pCO2) do not exhibit a simple spatial pattern and are controlled by local physical and net biological processes which impede equilibrium with the atmosphere. Along the Pacific coast, upwelling brings subsurface waters with low Ω and pH to the surface where net biological production works to raise their values. Different temperature sensitivities of carbonate properties and different timescales of influencing processes lead to contrasting property distributions within and among margins.

Autonomous Observation of Seasonal Carbonate Chemistry Dynamics in the Mid‐Atlantic Bight

“…TA:DIC provides context for the CO 2 buffering capacity of seawater. Oceanic buffering capacity for CO 2 reaches a minimum at TA:DIC = 1, meaning water with TA:DIC closest to 1 is most susceptible to acidification (Cai et al, 2020; Egleston et al, 2010; Z. A. Wang et al, 2013).…”

Long‐Term Changes of Carbonate Chemistry Variables Along the North American East Coast

“…• Figure S1 • Figure S2 • Figure S3 • Figure S4 • Figure S5 • Figure S6 • Figure S1 • Figure S7 • Figure S8 • Figure S9 • Figure S10 of Maine to the New York Bight (Bailey & Hachey, 1951). It transports the fresher and colder water into the Mid-Atlantic Bight (MAB) (Chapman & Beardsley, 1989) and has low Ω arag and total alkalinity (TA) (Cai et al, 2020). The Gulf Stream flows northward parallel to the coast and separates from shelf water regions near Cape Hatteras.…”

“…The Gulf Stream flows northward parallel to the coast and separates from shelf water regions near Cape Hatteras. It is warm and salty and has high Ω arag and TA (Cai et al, 2020). It strongly affects the shelf water dynamics along its propagation pathway in the South Atlantic Bight (SAB) (Atkinson et al, 1983;Lee et al, 1991).…”

Effects of Wind-Driven Lateral Upwelling on Estuarine Carbonate Chemistry

“…CO 2 dynamics often mirror O 2 dynamics, since all chemical species are advected or diffused by the same physical processes (currents and mixing) while the production and consumption of DIC and O 2 are affected by common biological processes such as phytoplankton production and organic matter respiration. However, while surface-water O 2 equilibrates with the atmospheric concentration relatively quickly, surface-water pCO 2 is slow to adjust and rarely reaches equilibrium with respect to the atmospheric pCO 2 due to the buffering effect of a much greater DIC pool on aqueous CO 2 (Cai et al, 2020(Cai et al, , 2021. Thus the effects of short-term wind effects may be different between O 2 and CO 2 .…”