New Micro Sensors May Monitor Ocean Acidification Due to Climate Change

Ocean acidification could potentially be a major issue in the future. It could drastically impact ecosystems and affect fisheries across the globe. Yet the first step in potentially curtailing and combating ocean acidification is monitoring it. Now, scientists have taken that first step by developing a cost-effective micro sensor for long-term monitoring of ocean acidification.

Ocean acidification is occurring due to rising levels of atmospheric carbon dioxide (CO2). This gas is absorbed by the oceans and when it dissolves in seawater, forms a mild acid. This, in turn, is slowly causing the pH of the oceans to decrease globally and could impact marine ecosystems.

"We need to monitor seawater pH to a high level of precision and accuracy, and over long periods of time, in order to detect changes in the carbon system," said Victoire Rerolle, one of the researchers, in a news release.

The new sensor works on the same principles as litmus paper, which changes color depending on the acidity of the solution that it's placed in. A microfluidic chip within the sensor is small, reasonably cheap to produce and uses small amounts of reagents. The sensor itself uses a dye which changes color with pH. The dye is added to the sample and then the color is measured using an LED light source and a device called a spectrometer. The microfluidic element simply describes the component needed to mix the seawater sample with the dye and the cell to measure the color.

The sensor doesn't just measure pH in the ocean overall, though. It could also be used to measure more localized human impact. The micro sensors could be deployed to detect leakages from carbon capture and storage sites by measuring any nearby fluctuations in pH.

The work isn't over, though, the researchers plan to develop an in situ system that can be deployed on ocean observing platforms.

"Now that we know that the bench top system works, we can use the technology from other systems to create in situ pH micro sensors," said Rerolle in a news release. "This is what we are working on now, in collaboration with oceanographers based at NOC."

The findings are published in the journal Anaytica Chimica Acta.