the atmosphere part 2 Flashcards
what is ozone?
allotrop of oxygen gas
-location= 9-18 miles above earths surface
what are UV-B effects?
-induces skin cancer by causing mutation in DNA and suppressing certain activities of immune system
-estimated 1% of depletion of ozone will lead to a 2-3% increase in the incidence of non-melanoma skin cancer
-common eye problems include cataracts, snow blindness
-impairs photosynthesis in many species
-impairs productivity of phytoplankton in aquatic ecosystems
what is natural ozone formation/destruction?
-english physicist Sidney Chapman formulated theory in 1930
-later added to by Belgian Marcel Nicolet- decomposition enhanced by hydrogen radicals
what are chlorofluorocarbons (CFCs)
-organic molecule containing chlorine, flourine, and carbon atoms
-good for air conditioning units, refrigerators, aerosol, solvents for cleaning
-used as most are non-toxic, non flammable, dissolve greases/oils without damaging electrical components, boiling points close enough to ambient temp
what is man-made damage?
-published nature article on threat to ozone layer from CFC gases
-suggested CFC could be transported to ozone layer, meeting such intense UV light that they would be separated into their constituents
what are CFCs in the troposphere?
-produced from human actions
-cause of global climate change
how is ozone depleted by CFCs?
-stage 1: CFCs absorb UV causing release of chlorine free radicals
-stage 2: chlorine reacts with monatomic oxygen
-stage 3: lack of monatomic oxygen to form ozone, leading to ozone concentration dropping
how do you measure ozone?
-using Dobson units
-estimates of total thickness of the ozone in the atmosphere as if it existed as a layer of pure ozone at sea level
-100DU= 1mm of ozone
-normal levels= 300DU
-‘ozone holes’= less than 220DU
what are the types of data collection?
-ground-based data
-satellite surveys
-air samples from stratosphere
what is the variability in ozone levels?
-ozone is most severe at altitudes of 12-24km
-worst ozone depletion occurs over antarctica
-ozone depletion in the arctic is less severe
what is ozone depletion over antarctica?
-severity of ozone depletion varies at different times of the year
•antarctic atmospheric processes:
-presence of polar vortex in winter
-CFCs/ODSs drawn to poles
-much lower temps leading to stratospheric clouds
-that allow surface chemicals reactions/ storage of chlorine
-increased UV causes more dissociation
what are the impacts of CFCs on humans?
-skin cancer
-eye damage-risk of mutations in DNA due to exposure to UV-B
what are the impacts of CFCs on plants and animals?
-reduced photosynthesis
-leaf damage
-lower crop yields
what is the montreal protocol?
-stipulates that the production and consumption of compounds that deplete ozone in stratosphere were to be phased out by 2000
-failure to comply was accompanied by stiff penalties
-expected to result in avoidance of 7280 million cases of skin cancer
what is the vienna convention?
-in response to Farmans publications in 1985 members of the united nations met at a convention in vienna
-aim was to preserve human health and to protect the environment from any harmful effects of the depletion of the ozone layer
