Scientists at Caltech and the University of Southern California have discovered that adding a common enzyme will make the slow part of the chemical reaction that sequesters carbon dioxide into the ocean go 500 times faster. They believe that, if they can scale this process up, it could make a real difference in reducing the level of carbon dioxide in the atmosphere.
The researchers were investigating how long it takes calcite to dissolve in sea water. Earlier methods relied on measuring the change in pH in the seawater as calcium carbonate dissolved. The researchers developed a new method using the relatively rare carbon-13 isotope.
By engineering a sample of calcite made entirely of the rare carbon-13, dissolving it in seawater and measuring the change in the ratio of carbon-12 to carbon-13 in the seawater over time, they were able to achieve results which were about 200 times more accurate than the older technique.
The oceans hold about 50 times as much carbon dioxide as the atmosphere. Carbon dioxide combines with water at the surface forming carbonic acid. The acidified surface ocean waters eventually circulates to the deep where they it reacts with dead calcium carbonate shells on the sea floor forming calcite, the precursor of limestone and marble – sequestering the carbon dioxide. However, this process takes tens of thousands of years to complete
Using their improved measuring technique, the researchers realised that the slow part of the process is the time that it takes for the carbon dioxide to dissolve at the surface. And that by adding carbonic anhydrase – a common enzyme which, among other things, helps maintain the pH balance of blood in humans and other animals – they could speed up the reaction by a factor of 500.
The researchers are now investigating ways of scaling up the process. They believe that, if they can succeed in this, it could make a real difference in reducing the level of carbon dioxide in the atmosphere.