karbonatbikarbonatkretsloppet

The carbonate-bicarbonate cycle, often referred to as the carbon cycle in a broader context, describes the complex movement of carbon through the Earth's atmosphere, oceans, land, and living organisms. A key part of this cycle involves the interconversion between carbonate ions (CO3^2-) and bicarbonate ions (HCO3^-), particularly in aquatic environments. These forms are crucial for regulating pH and facilitating the transport of carbon.

In the oceans, atmospheric carbon dioxide dissolves into seawater, forming carbonic acid (H2CO3). This acid then dissociates into hydrogen ions and bicarbonate ions. The bicarbonate ions can further dissociate to form carbonate ions and more hydrogen ions. Conversely, if the concentration of hydrogen ions decreases, bicarbonate ions can combine with them to form carbonic acid, which can then release CO2 back into the atmosphere. This buffering system is vital for maintaining the ocean's alkalinity.

Weathering of rocks on land also plays a role. Carbonic acid in rainwater reacts with rocks, releasing ions including bicarbonate, which are then transported to the oceans. Marine organisms utilize carbonate ions to build their shells and skeletons. When these organisms die, their remains can form carbonate rocks, sequestering carbon for geological timescales. The carbonate-bicarbonate system is therefore a fundamental process influencing both short-term and long-term climate regulation and the availability of dissolved inorganic carbon for biological and geological processes.