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Scientists develop a way to monitor CO2 leaks on the seafloor

Some scientists believe that a feasible strategy for climate change mitigation is to inject carbon dioxide (CO2) deep into the seafloor. If this plan was put into action, however, scientists have not yet established a reliable way to monitor these sites for gas leakage. 

Researchers from the American Chemical Society (ACS) may have now found a solution to this problem. By studying natural sources of CO2 release off the coast of Italy, the experts managed to design models for potential deep sea storage sites.

Off the Norwegian coast, the multinational energy company Equinor operates a facility that captures and stores almost a megaton of CO2 in an offshore sandstone aquifer that is located deep in the ocean. If CO2 is leaked here, it is less threatening to humans because the water acts as a buffer.

On the other hand, the leaked gas can dissolve into seawater, which decreases the pH and poses a risk to marine life. As of now, scientists lack a strategy to locate or quantify CO2 leaks across the ocean floor. 

Led by Jonas Gros, the ACS team analyzed pH changes near natural CO2 seeps in the vicinity of Panarea, a small island off the coast of northern Sicily. The experts collected gas and water samples from deep CO2 plumes to develop a computer model that could predict the pH changes in water that result from gas leakage.

The model was able to pinpoint over 79 percent of the CO2 dissolved within four meters of the seafloor. The team also found that their model could predict a pattern of pH variation in waters surrounding the leakage site that was similar to actual data collected by sensors towed underwater. 

Through routine sampling, the new technology could be used to guide monitoring strategies and to estimate the marine ecosystem impacts of CO2 releases in the deep sea.

The study is published in the journal Environmental Science and Technology.

By Chrissy Sexton, Staff Writer

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Image Credit: Christian Howe

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