RESUMO
This review has been undertaken to understand the effectiveness of ocean acidification on oceanic micronutrient metal cycles (iron, copper and zinc) and its potential impacts on marine biota. Ocean acidification will slow down the oxidation of Fe(II) thereby retarding Fe(III) formation and subsequent hydrolysis/precipitation leading to an increase in iron bioavailability. Further, the increased primary production sustains enzymatic bacteria assisted Fe(III) reduction and subsequently the binding of weaker ligands favours the dissociation of free Fe(II) ions, thus increasing the bioavailability. The increasing pCO2 condition increases the bioavailability of copper ions by decreasing the availability of free CO32- ligand concentration. The strong complexation by dissolved organic matter may decrease the bioavailable iron and zinc ion concentration. Since ocean acidification affects the bioavailability of essential metals, studies on the uptake rates of these elements by phytoplankton should be carried out to reveal the future scenario and its effect on natural environment.
