Stratospheric Ozone Depletion, Regional Ozone, Aerosols: Connections to Climate Change Jeff Gaffney Chemistry Department University of Arkansas at Little Rock
DOE Biological and Environmental Science Climate Change Research Division
Biosphere Breathing
1927 Chloroflurocarbons developed by Thomas Midgley, Jr. CFC s or Freons Not Flammable Not Toxic Very Safe as compared to Butane or Ammonia used for refrigeration working fluids. GOOD INTENTIONS can lead to UNFORSEEN IMPACTS
1974 F. Sherwood Rowland And Mario Molina Propose that CFC s could harm Stratospheric Ozone Layer. Cl-CF 3 + uv light Cl radicals Cl + O 3 ClO + O 2 Catalytic Destruction of Ozone ClO + O Cl + O 2 1995 Nobel Prize in Chemistry shared with Paul Crutzen
Antarctic Ozone Hole.. Proof of Theory
Proof that ClO is at the heart of it..
Ozone depletion Lower in atmosphere Than predicted.. Same height as Polar Stratospheric Clouds and Aerosols Water, Ice, Aerosols Amplify Chemistry!
WORLD LEADERS AGREE TO LIMIT USE OF CFC S MONTREAL PROTOCOL
GLOBAL IMPACTS DEPEND ON LIFETIMES LONG LIFETIMES MEANS LONG IMPACTS DOES NOT CLEAN UP OVERNIGHT!
STILL NEED BETTER REFRIGERANTS AND REPLACEMENTS.. REQUIRES A COMPLETE UNDERSTANDING OF CHEMICAL, BIOLOGICAL, AND PHYSICAL PROPERTIES PROBLEM NOT SOLVED!
SO FREONS ARE STARTING TO GO DOWN OR HAVE STOPPED INCREASING AND ACTIONS ON DRY CLEANING AGENTS APPARENT!
BUT.. HCFC S ARE RISING NOT AS BIG A DEAL FOR STRATOSPHERIC OZONE DEPLETION BUT THEY ARE POTENT GREENHOUSE GASES!
Photochemical Smog Formation LOS ANGELES TROPOPSPHERIC OZONE!
Stratospheric Ozone UV light Chapman Cycle TROPOSPHERIC OZONE O 3 - Without UV? Formed from Photolysis of NO 2 Professor Frances Blacet UCLA (MY ACADEMIC GRANDFATHER!)
NO 2 + visible light NO + O O + O 2 + M(N 2, etc.) O 3 + M BUT O 3 + NO NO 2 + O 2 Ozone production will depend on light and NO/NO 2 ratio only! 60 Ozone 0 No NET Ozone At end of Day Time
NO was coming from CARS and INDUSTRY NO DOES NOT ABSORB RADIATION NO Titrates Ozone No Ozone until NO Gone No ozone unless NO 2 > NO SO MAYBE IT IS A THERMAL REACTION 2NO + O 2 2NO 2 Rate Law: d[no 2 ]/dt = k[no] 2 [O 2 ] SLOWS DOWN AT LOW CONCENTRATIONS
Ari Haagen-Smit Cal Tech
Plant Growth Hormone Studies as Graduate Student Joined Cal Tech as Chemist in Division of Biology Work in the 1940s Flavors Pineapple Perfumes and Volatiles from Plants Chemistry of Natural Products
Applying His Plant Methods He showed that the products were indeed Organic oxidized compounds. He took auto exhaust and sunlight and showed that it would produce ozone and a similar brew of organics that he had collected. Haagen-Smog Did not have a detailed mechanism but did show that Volatile organics and nitrogen oxides in presence of sunlight would produce air pollution.
Dr. Arie Haagen-Smit discovery of the nature and causes of photochemical smog identified nitrogen oxides and hydrocarbons as key agents in producing oxidants (a key component of which was ozone). Will talk about another oxidant peroxyacetyl nitrate (PAN) in later lecture. His work led to Anti-Smog Bills
Control Strategy Easy to use catalytic converters to reduce VOC and CO emissions Harder to reduce NOx emissions URBAN CONTROL lower VOCs LEADS TO REGIONAL OZONE PRODUCTION AS ISOPRENE IS EMITTED FROM THE TREES IN SUMMER!
Types of Aerosols Primary Aerosols Combustion Diesel Soots Biomass Burning Secondary Inorganic Aerosols NH 4 NO 3, (NH 4 ) 2 SO 4, etc. Secondary Organic Aerosol Humic Like Substances (HULIS) Oxidized Organic Compounds
AEROSOLS-CLOUDS ARE NOW THE BIG UNCERTAINTY
LONG LIFETIMES Windblown Dust!!! MODELED AEROSOL LIFETIMES INCREASE WITH ALTITUDE Jacobs Group INDOEX results
AEROSOL IMPACTS DEPENDS ON POSITION IN THE ATMOSPHERE, THEIR RADIATIVE PROPERTIES, AND THEIR LIFETIMES Urban Regional Global
ITS ONE EARTH AND ONE ATMOSPHERE.. So stratospheric ozone depletion due to gases from troposphere. Methane - hydrogen - lead to water in stratosphere - amplifies aerosols and depletion. LONG RANGE TRANSPORT - Ozone and Aerosols - requires Global Cooperation
THE FUTURE WILL NEED NEW INSIGHT AND APPROACHES AND A WILLINGNESS TO CHANGE GLOBALLY! THAT S WHERE WE HOPE YOU WILL MAKE A DIFFERENCE! http://www.atmos.anl.gov/gcep/
http://www.er.doe.gov/ http://www.ualr.edu NEED DIRECTIONS BE HAPPY TO HELP LEAD YOU DOWN THE RIGHT PATH CONTACT JEFF GAFFNEY jsgaffney@ualr.edu HAVE A GREAT SUMMER IN GCEP!