A dangerous ozone-depleting compound is still used in China, despite being banned worldwide by the Montreal Protocol, a new study finds.
East China has emitted significant amounts of this substance – known as carbon tetrachloride (CCl4) – which is known to eat ozone, a protective layer in the earth's atmosphere that protects the world from dangerous ultraviolet radiation.
The new research is further evidence that points to China as a source of ozone -destructive emissions. Last summer, a New York Times study found factories in the country unleashed banned substances that destroyed the ozone layer. [Earth from Above: 1
Ozone sits high in the Earth's stratosphere, about 10 kilometers above the ground, where it absorbs much of the sun's ultraviolet (UV) radiation. This radiation increases the risk of cancer and eye damage in humans. A manmade hole already exists in the ozone layer over the Antarctic. So, to protect the ozone, all countries in the world have collectively agreed to ban the substances that destroy this layer, including CCl4, which was banned worldwide in 2010 in an update to the Montreal Protocol. Despite this agreement, around 44,000 tonnes (40,000 tonnes) are banned. Year after year, mysterious tonnes were emitted, as recent studies have shown.
To investigate, an international team of scientists from Australia, South Korea, Switzerland, the United Kingdom and the United States worked together to pinpoint the origin of these puzzles. The team used data from ground-based and airborne atmospheric concentration sensors near the Korean Peninsula and two models that simulated how gases move in the atmosphere.
These techniques paid off; The researchers found that about half of these mysterious emissions came from eastern China between 2009 and 2016.
"Our results show that emissions of carbon tetrachloride from the East Asia region account for a large proportion of global emissions," said study author Mark Lunt, a visiting chemistry scholar at the University of Bristol in England, said in a statement. "And [these emissions] are much larger than some previous studies have suggested."
CCl4 emissions are so high that "despite the phasing out of carbon emissions for emission use in 2010, there are no signs of any future reduction in emissions, said Lunt, with some regions, including the Chinese province of Shandong after 2012, having he said, "It's even pumped out more emissions than before," he said.
However, the scientists found that they are unsure of where the other CCl4 emissions came from, and it is possible that large amounts of this gas will be produced accidentally if other chemicals, such as Chlorine, the researchers said.
"Our work shows the position of carbon tetrachloride emissions," studies co-author Matt Rigby, a reader in atmospheric chemistry at the University of Bristol, said in the statement, "but we still know not the processes or industries responsible for it. This is important because we do not know whether it is produced intentionally or unintentionally. "
More atmospheric research could uncover other culprits." There are areas of the world – such as India, South America, and other parts of Asia – where emissions of ozone depleting gases Rigby said, "In the future, these results could help scientists and regulators understand exactly where and why these emissions are happening in China, because the sooner these emissions are stopped, the faster the ozone will recover, according to the researchers.
"There is a temptation to see ozone depletion as a solved problem," said Lunt. "But monitoring man-made ozone depleting gases in the atmosphere is important. to ensure the continued success of the termination of these compounds. "
The study was completed on Sept. 28 he online in the journal Geophysical Research Letters  Originally published on Live Science.