Views:109 Author:Site Editor Publish Time: 2020-11-23 Origin:Site
Before the ozone layer is formed, organisms can live in water because water can reflect ultraviolet light. However, terrestrial organisms are unlikely to survive because DNA absorbs ultraviolet light, especially at wavelengths between 280 and 320 nanometers. The ultraviolet radiation interrupts DNA replication, causing reproduction failure and death. Therefore, the ozone layer is a prerequisite for the existence of terrestrial organisms.
The ultraviolet radiation can cause mutations during the replication process, leading to the production of cancerous cells. The cells most exposed to the ultraviolet radiation are skin cells, so the ultraviolet radiation is often associated with skin cancer and cataracts. Like humans, other animals such as birds and lizards are also affected.
The ozone molecule consists of three oxygen atoms, and most of the atmospheric ozone is in the stratosphere between 10 kilometers and 50 kilometers.
1. The oxygen molecule is decomposed into two oxygen atoms under ultraviolet radiation (UV-c) with a wavelength below 240 nanometers. Then these oxygen atoms (O) react with other oxygen molecules (O2) to generate ozone.
2. An ozone molecule can be decomposed into an oxygen molecule and an oxygen atom by solar ultraviolet radiation, and then the oxygen atom can react with other oxygen molecules to generate ozone. The ozone-oxygen atom cycle consumes ultraviolet radiation and converts it into heat.
3. The ultraviolet radiation can destroy the chemical bonds of DNA molecules, but fortunately, ozone can absorb that part of the ultraviolet radiation spectrum that damages DNA. Ozone is incapable of shielding UV-a (320-400 nanometers), but it can partially shield UV-b (280-320 nanometers), and completely shield the extremely powerful UV-c (200-280 nanometers).
4. Ozone can be destroyed by the catalytic process, in which ozone molecules are reduced, but the catalyst (chlorine, nitrogen, bromine, hydrogen) is regenerated to destroy other ozone molecules, then the new ozone is generated.
5. Trace gases with long life cycles, such as chlorofluorocarbons (CFCs), rise from the upper tropical troposphere to the stratosphere. After entering the stratosphere, chlorofluorocarbons generally move to mid-latitudes, and are taken out of the stratosphere and re-enter the troposphere. Another small part of the chlorofluorocarbons continue to rise to the top of the stratosphere (above the ozone layer), and is decomposed by very short-wavelength solar ultraviolet radiation, then release chlorine and destroy ozone.
6. The Antarctic ozone hole is directly caused by human pollution to the stratosphere (mainly HCFCs). The Antarctic ozone hole appears in the southern hemisphere every spring (August-October). Ozone holes are formed by chemical reactions that occur on the surface of stratospheric cloud (PSC) particles. These reactions release the chlorine in the benign components (HCl and ClONO2) to form components (ClO) that can quickly catalyze the destruction of ozone.
7. The fact that compounds like HCFCs can lead to ozone reduction has now reached an international consensus. The concentration of chlorine-containing compounds that can destroy ozone has begun to decrease in the low-level atmosphere (since 1996). The impact of airplanes and greenhouse gases on the atmosphere is being studied.
After learning this article, we can know the importance of the ozone layer to humans and the destructive effect of HCFCs on the ozone layer. In order to better protect the ozone layer and protect the human living environment, we must minimize the production of HCFCs.
Of course, in addition to the protective effect of the ozone layer on the human living environment, ozone is very helpful to our daily life. For example, ozone can be generated by an ozone generator, which can purify the air and preserve food, and purify water with ozone water treatment can remove the bacteria in the water. For more functions of ozone, if you are interested, please contact us.