GEG 3107 Lecture 8: Lecture 8
5 Dec 2016
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Document Summary
Contaminants can travel through the atmosphere, which is linked to the snow and sea ice as well as freshwater and terrestrial systems. In the antarctic, freshwater pathways are largely absent. Caused by emissions of ozone depleting chemicals (cfcs, hcfcs, carbon tetrachloride, halons, etc ), which are used as refrigerants, dry cleaning etc. Ozone is found in the stratosphere (~20-25 km) and absorbs uv-b radiation. In the winter the temperatures over the poles drop to around 183 c & clouds of ice crystals form in the ozone layer. Cl and br compounds adhere to the ice crystals. As the temperatures warm the cl and br become reactive & convert the ozone into o2, reducing the amount of ozone present. Later in the spring the ozone is restored from lower latitudes. Process is natural, but has increased in recent years (more depletion) There was a rapid decline in ozone from the 1970s until the mid-90s.
