Chemical modeling of marine trace metals: Effects of ocean acidification to marine ecosystem

Chemical thermodynamic model is introduced to evaluate ecological effects of ocean acidification, which is predicted from increasing ocean uptake of carbon dioxide. The chemical model contains metal complex formation with two types of dissolved organic ligands in seawater. Concentration responses of copper and iron species in seawater to pH decrease were simulated. Free copper ion concentration, whose level is closely related to toxicity to phytoplankton, shows no response to ocean acidification as buffering effects by organic ligands. Ocean acidification leads to increase of bio-available iron (organic iron complex) in seawater, which causes increasing marine primarily production and following export flux of carbon into ocean interior. Chemical model regarding bioactive trace metals suggests presence of a negative feedback to the rising atmospheric CO₂.