Environment: Red Sea releasing large quantities of polluting gases

Large quantities of non-methane hydrocarbon gases, such as ethane and propane, are being emitted from deep water sources in the northern Red Sea, reports a paper in Nature Communications. The study suggests that natural stores of these pollutants enter the atmosphere in quantities that exceed anthropogenic emissions from some oil-producing countries in the Middle East.

Efstratios Bourtsoukidis and colleagues collected measurements from around the Arabian Peninsula in July and August 2017 to quantify emissions of hydrocarbon pollutants and compared their observations with existing atmospheric models. The authors found that measurements of ethane and propane taken over the northern Red Sea were much higher than model estimates. By tracking the trajectory of air masses carrying the pollutants, they located an underwater source. They found that the quantity of hydrocarbon gases released was over 0.2 teragrams (200 million kilograms) per year - a value that rivals anthropogenic emissions from countries with high levels of oil and gas activity, such as the United Arab Emirates, Kuwait and Oman.

Once in the atmosphere, these gases interact with nitrogen oxides and trigger the formation of a suite of compounds like ozone, which are harmful to human health. The authors caution that projected increases in ship traffic and the associated rise in nitrogen oxide emissions could amplify ozone formation, with effects on air quality in the region.