Oceanography

Carbon Dioxide and Carbonate cycles

Carbon dioxide has the most complicated behavior of all the gases in seawater. It occurs as a dissolved gas and in several other chemical forms. It is highly soluble in seawater.The carbondioxide enter the sea from the atmosphere and  respiration of plants and animals in the ocean.When carbon dioxide (gas) dissolves, it forms a weak acid (H₂CO₃), which acts as a buffer to stabilize the acidity of seawater. (Acidity is another way of expressing the abundance of hydrogen ions in water.)

Addition of acid (H⁺) creates more bicarbonate, which combines with acids to keep the acidity of the mixture unchanged. Thus respiration and decomposition processes producing carbon dioxide hardly affect the acidity of seawater, nor does removal of carbon dioxide during photosynthesis. Carbonate and bicarbonate freely give up and accept hydrogen ions in sea water, thus creating a buffer against sharp changes in acidity. Because of its complex chemical behavior, carbon dioxide is involved in many processes in the ocean.