Topic 5.6Depletion of Stratospheric Ozone

Ozone Overview

• The ozone layer is the part of the Earth's atmosphere which contains relatively high concentrations of ozone (O3). • Although the concentration of ozone in the ozone layer is very small,

it is vitally important to life because it absorbs biologically harmful ultraviolet (UV) radiation from the Sun. • The "thickness" of the ozone layer varies by a large factor worldwide,

being in general smaller near the equator and larger as one moves towards the poles. • It also varies with season, being in general thicker during the spring

and thinner during the autumn.

Role of Ozone

• Ozone plays a key role in the temperature structure of the Earth's atmosphere. • Without the filtering action of the ozone layer, more of the Sun's UV-B

radiation would penetrate the atmosphere and would reach the Earth's surface. • Ultraviolet radiation is absorbed during the formation and destruction

of ozone from oxygen.• Without the ozone layer, all living organisms on Earth would be

destroyed.

Effects of UV on living organisms

• Increase in mutation rates in DNA causing cancer•Can cause eye cataracts•Can damage the ability to carry out photosynthesis in

plants and phytoplankton•Reduces primary production and therefore total

productivity

Management Solutions

United Nations Environment Programme (UNEP) in forging International agreements

• ITIHC (International Trade in Harmful Chemicals)• air pollution• contamination of international waterways• provide information to countries and public on disadvantages of

pollution

1997 Montreal Protocol • international agreement on the emission of ozone-depleting

substances• froze production and consumption of CFC’s with goal of zero

production by year 2000• LEDC’s granted a longer time to implement the treaty• China and India have not met their quotas under the MP because of

their rapid economic growth and high demand for refrigeration & AC’s• good example of a successful international cooperative effort to alter

human impact on the environment

Assignment

• Get into your groups and plan out your lab.• Choose your variables and begin to write the plan section.• I need to know what your pollutant will be by today. • Email me your choice of pollutant today!• We will be conducting the lab on Tuesday. The beans we are using are

on my desk, so you can look at them and get information.