Recent investigations into the emissions of carbon tetrachloride have revealed that eastern China has been releasing large amounts of the substance into the atmosphere. Carbon tetrachloride is a compound that contributes to the degradation of the ozone layer; it was banned globally in 2010. The study highlighting this discovery was published recently in Geophysical Research Letters.
Researchers collaborating from around the world analyzed data from ground-based and airborne atmospheric concentrations around the Korean peninsula in order to determine how high emission levels were. Although carbon tetrachloride has been banned for over eight years now, 40,000 tons of the compound are still emitted annually.
According to the researchers, the data shows that roughly half of the global emissions of carbon tetrachloride since the ban can be pinpointed to eastern China between the years of 2009 and 2016. Furthermore, the researchers stated that the ban has not, in fact, resulted in a subsequent decrease in emissions as was expected. Other research has also shown that large quantities of carbon tetrachloride could be being emitted as a by-product of the production process of other chemicals like chlorine.
Nevertheless, more research is still needed in order to fill in the gaps in our knowledge about global carbon tetrachloride emissions. One key missing piece of the puzzle concerns the emissions coming from the Chinese province of Shandong. Co-author Dr. Matt Rigby said: "Our work shows the location of carbon tetrachloride emissions. However, we don't yet know the processes or industries that are responsible. This is important because we don't know if it is being produced intentionally or inadvertently."
Identifying this information will help to speed up the healing process of the ozone layer. The ozone layer is important because it protects us from harmful ultraviolet radiation. Lead author Dr. Mark Lunt stated: "Studies such as this show the importance of continued monitoring of ozone-depleting gases. There is a temptation to see ozone depletion as a problem that has been solved. But the monitoring of human-made ozone-depleting gases in the atmosphere is essential to ensure the continued success of the phase-out of these compounds."