The Influence of Land - Ocean Exchange on the Carbonate Mineral Saturation State Over the Continental Shelves (Invited)

River discharge mixes with, and is broadly distributed in the surface waters of the continental shelf. If the global annual river discharge were poured into the ocean to form a 5- meter layer, it would cover an area equivalent to 25% of the continental shelves’ surface area. Dissolved and particulate constituents in river discharge vary depending on regional climate, geology, land use, residence time, and atmospheric deposition over land. These regional differences can have considerable influence on the status of the carbonate mineral saturation (omega) over broad regions of the continental shelves. We discuss regional land-to-ocean flux variability in calcium, borate and non-carbonate alkalinity and their potential to confound estimates of omega in coastal waters. We also address the impact of land fluxes on net community production and coastal eutrophication, and the effect these processes can have on perturbing omega in coastal waters.