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

jsgaffney@ualr.edu

http://www.er.doe.gov/ http://www.ualr.edu

HAVE A GREAT SUMMER IN GCEP!