Location of a large mysterious source of banned substance depletion of the ozone layer discovery

As a result, carbon tetrachloride production has been banned worldwide since 2010 for uses that cause its release into the atmosphere. However, recent studies have shown that global emissions have not decreased as expected: about 40,000 tonnes were still emitted each year.

The origin of these programs intrigues researchers for many years.

Alongside collaborators from South Korea, Switzerland, Australia, and the United States, researchers from the University of Bristol have sought to quantify the emissions of Asia from the United States. ;Is.

To do this, they used atmospheric and ground – based atmospheric concentration data from the Korean peninsula, as well as two models simulating the transport of gases into the atmosphere.

Their results, published in the journal Letters of geophysical research, show that almost half of the world's "missing" carbon tetrachloride emissions came from eastern China between 2009 and 2016.

Lead author Dr. Mark Lunt of Bristol University School of Chemistry said, "Our results show that carbon tetrachloride emissions from the East Asia region are an important part of global emissions and are significantly larger than some previous studies suggested.

"Not only that, but despite the phasing out of carbon tetrachloride production for emissive use in 2010, we have found no evidence of further emission reductions."

In fact, emissions from some regions may have increased slightly since 2010. The results of the study show the emergence of a new source of emissions from Shandong Province in China after 2012 .

While the results of this study and previous studies in Europe and the United States now account for much of the global distribution of carbon tetrachloride emissions, our knowledge is still very skewed. In addition, recent reports have suggested that very large quantities of this gas could be inadvertently emitted during the production of other chemicals such as chlorine.

Matt Rigby, professor of atmospheric chemistry at the University of Bristol and co-author, said: "Our work shows the location of carbon tetrachloride emissions, but we do not yet know which processes or industries are responsible. because we do not know if it is intentionally or inadvertently produced. "

He also added: "There are parts of the world such as India, South America and other parts of Asia, where the depleting gas emissions layer of Ozone may be in progress, 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. In the end, if these emissions could be avoided, it would accelerate the recovery of the stratospheric ozone layer.

Dr. Lunt said, "Studies such as this one show that it's important to continually monitor ozone-depleting gases." It's tempting to consider that depletion of the ozone layer is a problem that has been solved.the atmosphere is essential to the continued success of the elimination of these compounds. "

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More information:
Mr. F. Lunt et al, Continued Emissions of Carbon Tetrachloride, an Ozone-Depleting Substance, from East Asia, Letters of geophysical research (2018). DOI: 10.1029 / 2018GL079500