Bivalve shells represent a potentially important but poorly quantified source of total alkalinity (TA) in coastal ecosystems. Shell dissolution can locally buffer acidification and regenerate alkalinity, yet its importance relative to riverine inputs, ocean exchange, water-column processes, and other benthic reactions remains uncertain at the ecosystem scale. Here, I will develop a seasonal TA budget for Narragansett Bay, Rhode Island, to evaluate the contribution of bivalve-shell dissolution to coastal TA dynamics. The budget integrates long-term observations of salinity and carbonate chemistry, riverine TA inputs, exchange with Rhode Island Sound (open sea exchange), and estimates of benthic and water-column TA production and consumption. Shell-derived alkalinity regeneration is constrained using laboratory measurements of oyster- and clam-shell dissolution under environmentally relevant conditions. Preliminary analyses indicate that shell dissolution is strongly seasonal, with the greatest potential during high-pCO₂ and low-saturation-state conditions. By comparing shell-derived TA with the full seasonal TA budget, this study assesses the contribution of shell dissolution to the natural buffering capacity of Narragansett Bay and evaluates the potential of bivalve shell recycling to restore this ecosystem service and enhance coastal resilience to ocean acidification.
 

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