Ozone layer depletion is the destruction of ozone gas of upper atmospheric layer (stratosphere), caused by substances formed from breakdown of ozone-depleting substances (ODS). The ozone layer plays an ultimately significant role in absorbing ultraviolet radiation that are hazardous to living creatures on the Earth. It was until 1974, chlorine was found to be the catalyst which speeds up the ozone depletion.
CAUSES OF OZONE DEPLETION
Natural Causes of Ozone Depletion: Stratospheric Clouds
The ozone hole over Antarctica is formed by a slew of unique atmospheric conditions over the continent that combine to create an ideal environment for ozone destruction.
Winds over the Antarctica continent blow in a unique clockwise direction creating a so called “polar vortex” causing the air over Antarctica does not mix with air in the rest of the earth’s atmosphere. The chilling temperatures on the Antarctica (up to -110 F) result in the formation of polar stratospheric clouds (PSC’s) which are a mixture of frozen H2O and HNO3. Due to their extremely cold temperatures, PSC’s form an electrostatic attraction with CFC molecules as well as other halogenated compounds
In the Antarctic summer, as the temperature rises, high energy photons are able to photolyze the halogenated compounds, freeing halogen radicals that then catalytically destroy O3. Because Antarctica is constantly surrounded by a polar vortex, radical halogens are not able to be diluted over the entire globe. The ozone hole develops as result of this process. In March 2006, the winds circling high above the Arctic allowed near-record amounts of ozone-destroying gases, collectively known as nitrogen oxides or NOx, to descend some 50km from the mesosphere to the top of Earth’s stratosphere. NOx, is a generic term for a group of highly reactive gases, all of which contain nitrogen and oxygen in varying amounts, especially nitric oxide (NO) and nitrogen dioxide(NO2). NOx destroys ozone, heating up the stratosphere by absorbing ultraviolet radiation. In addition, strong winds bring more nitrogen oxides down to the stratosphere.
Man-made Causes of Ozone Depletion: Ozone-depleting substances (ODS
)The main cause for the depletion of ozone is determined as excessive release of chlorine and bromine from man-made compounds such as chlorofluorocarbons (CFCs). CFCs (chlorofluorocarbons), halons, CH3CCl3 (Methyl chloroform), CCl4 (Carbon tetrachloride), HCFCs (hydro-chlorofluorocarbons), HBFCs (hydro-bromofluorocarbons) and CH3Br (methyl bromide) are found to have direct impact on the depletion of the ozone layer. These are categorized as ozone-depleting substances (ODS). Ozone-Depleting Substances have been proven to be eco-friendly, very stable and non-toxic in the atmosphere below. Hence, they have gained popularity over the years. However, their stability allow them to float and remain static high up in the stratosphere. When up there, ODS are comfortably broken down by the strong UV light and the resultant chemical is chlorine and bromine. Chlorine and bromine are known to deplete the ozone layer at supersonic speeds. One chlorine molecule has the capability to break down thousands of ozone molecules.
EFFECTS OF OZONE DEPLETION
- Damage to human health
- Devastation to environment
- Threat to marine ecosystems
- Effect on animals
- Impacts certain materials
Overexposure to strong UVB light causes non-melanoma skin cancer, cataracts, sunburns, weakening of immune system and quick aging.
Many crops species are vulnerable to strong UVB radiation and overexposure may well lead to minimal growth, photosynthesis and flowering. Hence, ozone layer depletion will cause reduction of nutrient contents and crop yield of plants.
UVB radiation kills phytoplankton, resulting in reduced survival rates for these organisms. In the aquatic food chain, plankton appear high up. Hence, killing of phytoplankton disrupt food chain in the marine.
In domesticated animals, too much UV radiation could also lead to skin and eye cancer. It will also bring about mutations in animals.
Materials like plastics, wood, fabrics, rubber are massively degraded by too much ultraviolet radiation. Increase in solar UVB levels will therefore accelerate synthetic polymers and naturally occurring biopolymers to breakdown, limiting the length of time for which they are useful outdoor.
SOLUTIONS TO OZONE DEPLETION
- Desist from using pesticides. Pesticides in form of aerosol contains CFCs, a kind of ODS, which contribute enormously to ozone layer depletion.
- Encourage car-pooling. These vehicles emit a lot of greenhouse gases that eventually form smog, a catalyst in the depletion of ozone layer. E.g. NOx, CF
- Promote eco-friendly vehicle. Promote vehicles that use hybrid engine or electro-zero emission engine. This can reduce the emission of nitrogen oxides (NOx) which contribute in ozone layer depletion.
- Prohibit the use of harmful nitrous oxide. The Montreal Protocol formed in 1989 helped a lot in the limitation of Chlorofluorocarbons (CFCs). However, the protocol never covered nitrous oxide, which is a known harmful chemical that can destroy the ozone layer. Nitrous oxide is still in use today. Governments must take action now and outlaw nitrous oxide use to reduce the rate of ozone depletion.