Stratospheric Ozone Depletion, Regional Ozone, Aerosols: Connections to Climate Change
Jeff Gaffney
Chemistry Department
University of Arkansas at Little Rock
DOE Biological and Environmental ScienceClimate 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-CF3 + uv light Clradicals
Cl + O3 ClO + O2
ClO + O Cl + O2Catalytic Destruction of Ozone
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!
TROPOSPHERIC OZONE – O3 -Without UV?
Formed from Photolysis of NO2
Professor Frances Blacet – UCLA
(MY ACADEMIC GRANDFATHER!)
Stratospheric Ozone
UV light – Chapman Cycle
NO2 + visible light NO + O
O + O2 + M(N2, etc.) O3 + M
BUT… O3 + NO NO2 + O2
Ozone production will depend on light and NO/NO2 ratio only!
No NET Ozone
At end of Day
Ozone
0
60
Time
NO was coming from CARS and INDUSTRYNO DOES NOT ABSORB RADIATIONNO Titrates Ozone – No Ozone until NO GoneNo ozone unless NO2 > NO
SO MAYBE IT IS A THERMAL REACTION
2NO + O2 2NO2
Rate Law:
d[NO2]/dt = k[NO]2[O2]
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 StrategyControl Strategy
Easy to use catalytic converters to reduce Easy to use catalytic converters to reduce VOC and CO emissionsVOC and CO emissionsHarder to reduce NOx emissionsHarder to reduce NOx emissionsURBAN CONTROL URBAN CONTROL –– lower VOCslower VOCsLEADS TO REGIONAL OZONE LEADS TO REGIONAL OZONE PRODUCTION AS ISOPRENE IS EMITTED PRODUCTION AS ISOPRENE IS EMITTED FROM THE TREES IN SUMMER!FROM THE TREES IN SUMMER!
Primary AerosolsPrimary AerosolsCombustionCombustionDDiesel Soots iesel Soots
Biomass BurningBiomass Burning
Secondary Inorganic AerosolsNH4NO3, (NH4)2SO4, etc.
Secondary Organic AerosolHumic Like Substances (HULIS) Oxidized Organic Compounds
Types of AerosolsTypes of Aerosols
AEROSOLS-CLOUDS – ARE NOW THE BIG UNCERTAINTY
MODELED AEROSOL
LIFETIMES
INCREASE WITH ALTITUDE
Jacobs Group – INDOEX results
LONG LIFETIMES
Windblown Dust!!!
AEROSOL IMPACTS DEPENDS ON POSITION IN THE
ATMOSPHERE, THEIR RADIATIVE PROPERTIES, AND THEIR LIFETIMES
Urban
Regional
Global
So stratospheric ozone depletion due to So stratospheric ozone depletion due to gases from troposphere.gases from troposphere.Methane Methane -- hydrogen hydrogen -- lead to water in lead to water in stratosphere stratosphere -- amplifies aerosols and amplifies aerosols and depletion.depletion.LONG RANGE TRANSPORT LONG RANGE TRANSPORT -- Ozone andOzone and
Aerosols Aerosols -- requires Global Cooperationrequires Global Cooperation
ITS ONE EARTH AND ONE ATMOSPHERE..
http://www.atmos.anl.gov/GCEP/
THE FUTURE WILL NEED NEW INSIGHT AND APPROACHES AND A WILLINGNESS TO “CHANGE” GLOBALLY!
THAT’S WHERE WE HOPE YOU WILL MAKE A DIFFERENCE!
NEED DIRECTIONS –
BE HAPPY TO HELP
LEAD YOU DOWN
THE RIGHT PATH
CONTACT
JEFF GAFFNEY
http://www.er.doe.gov/ http://www.ualr.edu
HAVE A GREAT SUMMER IN GCEP!
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