You are investigating a spring algae bloom that formed in the North Atlantic, when the seasonal mixed layer shoaled to about 50 m. This bloom lasted for one month and was dominated by coccolithophores that were rapidly exported. Fluxes of sinking organic carbon during these blooms was 50 mmol C m^-2.d^-1. The organic carbon:calcium carbonate ratio for this alga is about 4:1. Required:
a. Given that the initial dissolved inorganic carbon (DIC) and carbonate alkalinity (Ac) are 2,100 umol L^-1 and 2,300 μeq L^-1 respectively, estimate [CO32-] and pH?
b. Assume the rate of CO2 gas exchange with the atmosphere is slow compared to export of carbon as sinking particles, and make time course plots of DIC and Ac over the course of the bloom.
c. Approximate the total change in (CO3^2-) during the bloom, stating any assumptions made in the calculation. Did pH rise or fall? From a physiological perspective, do the changing conditions of the bloom favor or disfavor calcium carbonate precipitation?