The compound, carbon tetrachloride, contributes to the destruction of the Earth's ozone layer, which protects us from harmful ultraviolet radiation. As a result, the production of carbon tetrachloride since 2010 is banned worldwide will result in its release to the atmosphere
. However, recent studies have shown that global emissions have not declined as expected, with some 40,000 tonnes still emitted each year.
The source of these emissions has confused researchers for many years.
In addition to staff from South Korea, Switzerland, Australia and the US, researchers at the University of Bristol aspired to quantify emissions from East Asia.
They used soil-based and airborne atmospheric concentration data from near the Korean Peninsula and two models that show the transport of atmospheric gases
their results, which were published in the journal Geophysical Research Letters, that about half of the "missing" global carbon tetrachloride emissions were from eastern China between 2009 and 201
Lead author, Dr. Mark Lunt of the School of Chemistry at the University of Bristol said, "Our results show that emissions of carbon tetrachloride from the East Asia region account for a large proportion of global emissions and are significantly larger than some earlier studies have suggested.
"Not only that, but despite the exit from carbon tetrachloride production for emissions in 2010, we found no evidence of a subsequent decline in emissions. "
In fact, emissions from certain regions may have risen slightly since 2010. The results of the study indicate that a new source of emissions has emerged in the Chinese province of Shandong after 2012.
While the results of this and earlier studies in Europe and The US now accounts for much of the global distribution of carbon tetrachloride emissions, there are still major gaps in knowledge, and recent reports have shown that very large amounts of this gas can be inadvertently emitted during the production of other chemicals such as chlorine.
Dr Matt Rigby , Reader in Atmospheric Chemistry at the University of Bristol and co-author, said, "Our work shows where carbon tetrachloride emissions are located. However, we do not yet know the processes or industries that are responsible for it. This is important because we do not know whether it is produced intentionally or unintentionally. "
He added," There are areas in the world, such as India, South America and other parts of Asia, where emissions of ozone-depleting gases persist but detailed atmospheric measurements are lacking. "
It is hoped that this work can now be used by scientists and regulators to identify the cause of these emissions from East Asia, and if these emissions can be avoided, this would bring recovery accelerate stratospheric ozone layer.
Dr Lunt said: "Studies like these show the importance of ozone-depleting gases to continue to monitor ozone depletion as a problem that has been solved. But the monitoring of manmade ozone depleting gases in the atmosphere is essential to ensure the continued success of the phasing out of these compounds.
University of Bristol
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