|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Analysis and Interpretation of Ozone Layer Depletion and Its Significants: A Review |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Paper Id :
19204 Submission Date :
2024-08-19 Acceptance Date :
2024-08-24 Publication Date :
2024-08-25
This is an open-access research paper/article distributed under the terms of the Creative Commons Attribution 4.0 International, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. DOI:10.5281/zenodo.13365673 For verification of this paper, please visit on
http://www.socialresearchfoundation.com/innovation.php#8
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Abstract |
In this research article, a study has been done on halogen-containing ozone layer
depleting substances. And the number of hydrochlorofluorocarbons (HCFCs) and
chlorofluorocarbons (CFCs), chlorine and bromine are emissions caused by
ozone layer depletion and in which years has also been displayed year by year.
It is clear from this study that due to awareness across the world, the
emission of ozone depleting substances has reduced. The ozone layer is
predicted to recover almost completely by the middle of the twenty-first
century if ODS (Ozone depleting substances) emissions continue to drop. The
lengthy recovery period is brought on by the sluggish rate at which natural
processes remove ODS from the environment. The ozone layer acts like an
umbrella over the earth due to which harmful rays do not reach the earth. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Keywords | Hydrochlorofluorocarbons (HCFCs), Chlorofluorocarbons (CFCs), Chlorine and Bromine. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Introduction | The atmosphere only contains trace levels of ozone. However, ozone is essential to agricultural and ecological sustainability, as well as human health. The stratosphere, or layer of the atmosphere over 10 kilometers (6 miles) above the surface, is home to the majority of Earth's ozone. The stratospheric "ozone layer," which protects Earth's surface from the Sun's harmful UV rays, contains about 90% of the atmospheric ozone. The ozone layer in the stratosphere shields life on the planet from solar UV radiation. During the latter part of the 20th century, compounds that deplete the ozone layer and include halogenated substances. The ozone layer was depleting due to halogen-containing ozone-depleting substances (hODSs) from human activity, primarily in the form of chlorofluorocarbons. The most obvious sign of ozone depletion was the ozone hole over the South Pole, but between 60° S and 60° N, total column ozone was decreasing1. Ozone layer monitoring by the middle of the 1980s proved that depletion was in fact happening. Unexpected at the time of discovery, the most significant ozone loss was discovered to be occurring over Antarctica every spring. Because of how extensive and concentrated the ozone depletion occurs in this area; the loss is frequently referred to as the "ozone hole." In other parts of the world, including the Arctic and the northern and southern mid-latitudes, there has also been evidence of ozone layer depletion. Naturally, extremely intense solar UV radiation regularly splits oxygen molecules, creating ozone in the stratosphere. This ozone is being spontaneously destroyed by catalytic reactions mostly involving nitrogen and hydrogen oxides, while it is also being carried pole ward and downward by the air movements in the stratosphere. Ozone depletion increases by the release of a number of compounds created by humans, including methyl bromide, hydrochlorofluorocarbons, long-lived chlorofluorocarbons, and halons that contain bromine. This was first seen in the late 1970s and has resulted in a decrease in the protective stratospheric ozone layer, especially in latitudes between medium and high. (WMO, 2014)2. By way of surface-emitted ozone-depleting substances (ODSs) such hydrochlorofluorocarbons (HCFCs) and chlorofluorocarbons (CFCs), chlorine and bromine are transported to stratosphere. The levels of bromine and chlorine in the troposphere peaked in 1997 and 1993, respectively, as a result of the actions implemented under the Montreal Protocol. (WMO,2018)3.
Fig:1 Representation of ozone layer concentration in Troposphere and Stratosphere in atomosphere. The "ozone layer," a thin layer of bluish gas located 20 to 50 kilometers above Earth's surface, envelops our globe. The triatomic allotrope of oxygen is called ozone (03). If all of the ozone were to be brought down to the Earth's surface, it would only form a thin, 3 mm-thick rings around the planet. Because the stratosphere's ozone layer protects the Earth's surface from ultraviolet (UV) radiation produced by the Sun, it is commonly referred to as the "ozone shield." The industrial pollution is destroying it, and how the international community has addressed this issue by implementing corrective measures in recognition of the serious repercussions of global ozone loss.4 (Fig: 1) |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Objective of study |
In this research article, a study has been done on halogen-containing ozone layer depleting substances.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Review of Literature | The largest record was set by the O3 hole over the Arctic in 2020, and the largest, deepest, and most persistent ones were among the ones over the Antarctic in 2020 and 2021. In actuality, the electron-induced reaction (CRE) model driven by cosmic rays accurately anticipated these data, contrary to what was expected from photochemical models.5-8As will be demonstrated by the observed data in this study, all-season low-temperature cyclones are centred at an altitude of about 15 km above the tropics (30°N–30°S), where the temperatures are low at 190–200 K and the cosmic rays ionisation strength peaks. The latter are chilly enough to create tropical stratospheric clouds (TSCs), which are similar to polar stratospheric clouds (PSCs), which are necessary for surface reactions that result in an O3 hole. They are comparable to those in the polar stratospheric vortex over Antarctica during the winter.8This should result in a distinct active halogen evolution for the tropical lower stratosphere: in the absence of stable chlorine/bromine reservoirs (HCl and ClONO2) due to their rapid destruction on TSC surfaces, there is no ClO dimer (Cl2O2) and O3-depleting reaction cycles are much more effective in the presence of constant intense sunlight. Consequently, halogen-catalyzed processes are far more effective at destroying tropical O3, and even modest concentrations of active halogen can significantly reduce the amount of ozone over the tropics throughout the year. Well-observed are the O3 holes across the Arctic and Antarctica.9-11As stratospheric chlorine is processed on the surfaces of polar stratospheric clouds (PSCs), it is transformed from reservoir forms (such as HCl and ClONO2) to active, ozone-destroying forms (ClOx = ClO + 2Cl2O2). Because PSCs need low temperatures (≤195 K) to form, the amount of ozone depletion in the Arctic varies greatly between years.12-13 Ozone
recovery, or healing, has been observed in the upper stratosphere and the lower
stratosphere during Antarctic springtime as a result of the delayed decline in
the overall loading of these halogens that followed. Although there is a
substantial reported inter annual fluctuation that has prevented its discovery
thus far, some recovery is also expected in Arctic ozone.14-16Arctic
winter year 2019/20 experienced a sustained period of low temperatures in the
lower stratosphere and a The forcing was constrained by greenhouse gases, and the impact of increased solar activity and tropospheric ozone precursors was ignored, so the results obtained are incomplete. To get total column ozone (TCO) evolution from 1900 to 2100, built and applied a statistical model that takes into account ozone-depleting chemicals, human greenhouse gases, and natural processes that influence ozone.20-22 The main cause of the Antarctic ozone hole and stratospheric ozone depletion was an increase in the number of CFCs in the atmosphere. In retaliation, countries decided to phase down worldwide CFC production by 2010. This included production for dispersive purposes, which would eventually release the chemicals into the atmosphere. Refrigerants, foam-blowing agents, and aerosol sprays are a few examples of CFC dispersive applications. The phase-out has prevented significant more ozone layer depletion in the stratosphere, and global warming because long-lived CFCs have potential for thousands of times more global warming than carbon dioxide over a 100-year time horizon.23-26 |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Analysis | The most recent year for which consolidated global statistics are available is 2022, when concentrations of the three primary greenhouse gases carbon dioxide, methane, and nitrous oxide—reached record high measured levels (1984–2022). The three greenhouse gas concentrations continued to rise in 2023, according to real-time data from certain places. Greenhouse gas concentrations in the atmosphere show how emissions from sources other than humans, including natural sinks, and human activity, are balanced. Since the industrial revolution, human activity has been the primary cause of the increase in greenhouse gas concentrations in the atmosphere, which has led to climate change. The calculation of global average mole fractions of greenhouse gases, sometimes known as the "concentration" in the atmosphere, is based on in situ observations obtained at various locations via the Global Atmosphere Watch (GAW) Programme of WMO and partner networks. The most recent year for which consolidated global statistics are available is 2022, during which the atmospheric concentrations of greenhouse gases reached previously unheard-of heights. The globally averaged concentrations of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) were, respectively, 150%, 264%, and 124% of pre-industrial (1750) levels, at 417.9 ± 0.2 ppm, 1923 ± 2 ppb, and 335.8 ± 0.1 ppb. Following 2021, the rate of growth in CH4 was the second highest on record, while the rate of increase in N2O was the highest. At 2.2 ppm, the rate of CO2 growth was marginally lower than the 2.46 ppm 10-year average27. At 2.2 ppm, the rate of CO2 growth was marginally lower than the 2.46 ppm per year, the ten-year average. The growth rate of CO2 is often lower in years that begin with La Niña, like 2022, and higher in years that begin with El Niño, like 2016.28 Levels of CO2, CH4, and N2O continued to rise in 2023, according to real-time data from particular places, such as Mauna Loa29 (Hawaii, United States of America) and Kennaook /Cape Grim30 (Tasmania, Australia).
Fig. 2. Representation Of Year Wise Emission Of Ozone Layer Depleting Substances In World.
Hydrochlorofluorocorbons (HCFCs) Chlorine and bromine, which deplete the ozone layer, are absent from hydrofluorocarbons (HFCs). Certain HFCs have a significant potential to cause global warming, much as persistent CFCs and HCFCs. The Kigali Amendment to the Montreal Protocol, which was ratified in 2016 and went into effect in 2019, establishes deadlines for the reduction of particular HFCs' production and consumption. The Kigali Amendment was created to prevent unchecked radiation forcing growth in the ensuing decades, even if the radiation forcing caused by HFCs is currently negligible. Certain nations provide the United Nations Framework Convention on Climate Change (UNFCCC) with annual emission estimates of HFCs since HFCs were added as one group to the Kyoto Protocol's 1997 gas basket. The Kigali Amendment mandated more reporting on HFC emissions and consumption as well as manufacturing. The main reason HFC-23 is treated differently is that it is mostly released into the atmosphere as a waste product of the HCFC-22 manufacturing process. As more Parties ratify this Amendment, this reporting will get more comprehensive.31 Since the phasedown of ozone-depleting substances (ODSs), hydrofluorocarbons (HFCs) have become more widely produced and utilized in various applications, including refrigeration, air conditioning, and foam blowing. Apart from the emissions that arise from these applications, certain HFCs, specifically HFC-23, are also discharged as by-products while producing other substances. Long-lived HFCs are strong greenhouse gases even though they are safe for the stratosphere's ozone layer and typically have lower radiative efficiencies than the most prevalent ODSs. Methyl Chloroform 1,1,1-trichloroethane, an organic molecule with the chemical formula CH3CCl3, is also referred to as methyl chloroform and chlorothene. It is a 1,1,2-trichloroethane isomer. Once, vast amounts of this colorless, sweet-smelling liquid were produced industrially to be used as a solvent. Its use is being phased out quickly since it is classified as an ozone-depleting compound under the Montreal Protocol32. For a while now, there has been a great deal of worry about urban air pollution, and laws have been put in place to restrict the emissions of dangerous compounds. Concerns about the potential depletion of stratospheric 03 due to specific halocarbons being released have also been raised more recently, and measures to restrict their release rates are currently being taken. Substances classified as potentially dangerous to the troposphere and stratosphere are not classified according to the same criteria, and in fact, the criteria are more likely to be opposed.33 Methyl Bromide Methyl bromide is an odorless, colorless gas that is used to treat a wide range of pests in shipping and agricultural, including as rats, nematodes (also known as roundworms), weeds, fungus, and insects. Before planting crops, agricultural growers sterilize the soil by injecting methyl bromide around two feet into the ground. After a treatment, the soil is quickly covered with plastic tarps, but between 50 and 95 percent of the methyl bromide eventually finds its way into the sky. In order to stop pests from
entering the country, methyl bromide is also used to treat imported items including
logs, grapes, and asparagus. Official quarantine requirements for overseas
shipments are frequently satisfied via treatments. Methyl bromide in the atmosphere causes the ozone layer to thin, increasing the amount of UV radiation that reaches the surface of the planet. According to the Montreal Protocol on Substances that Deplete the Ozone Layer, methyl bromide is classified as a Class I ozone-depleting substance (ODS).34 Carbon Tetrachloride Historically, carbon tetrachloride (CCl4) has been employed as a feedstock for the synthesis of various chemicals, including chlorofluorocarbons (CFCs), as well as a solvent and cleaning agent. Since 2010, the Montreal Protocol has prohibited the manufacturing and use of CCl4 for dispersive purposes; nevertheless, it is still produced for some approved exemptions and for use as a nondispersive feedstock. Since it is believed that almost all CCl4 produced is later consumed, recycled, or destroyed, these substrate uses are unregulated35.The gas is recognized as an air toxin that depletes the ozone layer; it makes up between 10 and 15 percent of the substances that cause this depletion in the atmosphere nowadays. Consequently, production has been prohibited worldwide for an extended period of time for applications that cause CCl4 to leak into the environment. Regional opposite modeling studies are comparatively less sensitive to uncertainties in the CCl4 lifetime than global emissions estimation utilizing atmospheric data and models. They can also assist in addressing the geographical origin of the variations between emission predictions derived from the Environment Program of the United Nations production and feedstock reports and the actual global mole fraction obtained figures. Few regional opposite modeling studies of CCl4 emissions have been conducted, spanning some of the world's most economically active regions. These studies use observations of CCl4 in conjunction with a transport model and an inference statistical method to estimate emissions. Year wise emission of carbon tetrachloride is mention in table -1. Halons The main purpose of halon is to put out fires. It is used in both portable and built-in fire extinguishers. There have been several documented applications as tracers for investigations of circulation in buildings and the atmosphere. Bromine, which is present in all halons, has the ability to degrade ozone 40–100 times more effectively than chlorine. Thirty to forty percent of the Antarctic ozone hole is caused by the combined effects of chlorine and bromine in the stratosphere. Chlorine is mostly obtained via halons and methyl bromide1. Halon-2402 (C2Br2F4), halon-1301 (CBrF3), and halon-1211 (CBrClF2) are the most widely utilized halons. Compared to the CFCs, the halons have a different, albeit simpler, numbered system. The total quantity of carbon atoms is represented by the first digit from the left, followed by the amount of fluorine atoms, the lots of chlorine atoms, and the number of bromines atoms2. In Western Europe and the Western Hemisphere, portable fire extinguisher systems are the main applications for halon-1211. Systems for floods that contain fire and explosives employ halon-1301. The former Soviet states, China, Japan, and Russia all employ halon-2402 as a fire extinguisher agent. While other groups are developing viable substitutes, there are currently no drop-in halons available. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Conclusion |
Use of several
kinds of banned substances. Among these are methyl bromide (MB), methyl
chloroform (TCA), bromochloromethane (BMC), corbon tetrachloride (CTC),
hydrobromofluorocabons (HBFCs), hydrochlorofluorocarbons (HCFCs),
hydrofluorocarbons (HFCs) and other fully halogenated (CFCs). In the EU, substances that have the potential to destroy the stratosphere's ozone layer are being phased out. Ozone-depleting substances (ODS) have been successfully reduced in consumption since 2010 according to the Ozone Regulation; altogether, more chemicals are exported and destroyed than are produced. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| References |
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
