Huge amounts of chlorine-containing solvents and pesticides produced today in China and India can destroy the ozone layer of the Earth in the near future, according to an article published in the journal Atmospheric Chemistry and Physics.
“The ozone problem of the Earth was considered a well-studied thing, which we managed to eliminate through the adoption of the Montreal Protocol.” It turned out that some substances that we did not consider to be a threat to the ozone layer because of their short life span are in fact its main enemy, ” – said David Oram (David Oram) from the University of East Anglia (Great Britain).
In 1985, Susan Solomon, a US chemist, and her colleagues discovered that freons and other halogen compounds destroy the ozone layer, which in some regions of Antarctica has already led to the appearance of “ozone holes” – zones through which ultraviolet radiation from the sun unimpeded reaches the surface of the Earth.
In subsequent years, large-scale international negotiations began, the result of which was the signing of the Vienna Convention in 1985 and the Montreal Protocol to it in 1987, in which most of the world’s states agreed to stop the production of substances that deplete the ozone layer.
The rapid adoption and implementation of such plans, as scientists learned two years ago, suspended the growth of the ozone hole, keeping it within Antarctica and the Arctic, but has not yet led to its reduction. The first “visible” results from the ban on the production of freon scientists expected to see in the second half of 2020, but this process, as recently discovered by Solomon and her colleagues, has already begun in recent years.
All the pluses from the ban on freons, according to Oram, may disappear in the coming years as a result of the fact that another type of molecule that destroys the ozone layer – dichloromethane (CH2Cl2) – began to accumulate in the atmosphere of the Antarctic. It is one of the most popular reagents in the food and chemical industry, and is used in the production of fluorocarbons, safe analogues of Freon.
Until recently, environmentalists believed that dichloromethane did not pose a threat to the ozone layer, since its molecules quickly decay under the action of sun and oxygen rays, but in June of this year scientists recorded huge concentrations of this substance in the air at the south pole of the Earth. Where did this gas come from and what caused its concentration to grow in recent years was not entirely clear.
Oram and his colleagues suggested that the source of these emissions could be the developing countries of South and South-East Asia, where dichloromethane is actively used in agriculture and in the agricultural industry, and other compounds of chlorine and hydrocarbons in the manufacture of plastics.
Guided by this idea, scientists made several expeditions to Singapore, India, Thailand and Taiwan, where they collected air samples at the surface of the Earth and in the upper layers of the troposphere and calculated the proportions of various chlorine-containing substances in them.
As these measurements showed, the main “producer” of these emissions was China – the concentration of dichloromethane and similar substances was extremely high in all layers of the atmosphere over Taiwan and the mainland part of the PRC. According to scientists, China accounts for about half of these emissions, and quite large quantities of these gases are emitted by India and the countries of South-East Asia.
“If these substances reach the stratosphere and contact the ozone layer, they can do as much harm as freons.” The Montreal Protocol has a real hole that will need to be closed in the near future, especially if the concentration of these substances continues to grow, ” – concludes the scientist.