Ozone Causes Ecosystem Impacts

Sara Busken

Mona Shores High School

Ozone“Good up high” “Bad nearby”

Good Ozone Depletion

1970’s Researchers discover “hole” in Stratospheric ozone which blocks UV rays

1980’s CFC’s identified as cause of thinning

1989 Montreal Protocol world wide treaty banning use of CFC’s

It takes decades for CFC’s to dissipate, but the thinning has slowed

Tropospheric Ozone = SMOG

Ozone Formation in the Lower Atmosphere

VOC + NOx + Sunlight

OZONE

Tropospheric Ozone Record

Global Distribution of Tropospheric Ozone

Free-Air CO2 Enrichment Experiments (FACE)

Open-air control of atmosphere conditions

Fairly large scale

Longer term than previous chamber experiments

Major investment of research money

Large teams of researchers

Aspen FACE Experiment, Rhinelander, WI

1 treatment per ring4 treatments x 3 blocks = 12 rings

ElevatedCO2

ElevatedO3

ElevatedCO2 + O3

AmbientControl

ppm CO2:ppb O3:

36032

56032

36056

56056

Experimental Design

CO2 and Ozone Effects on Trees

CO2 effects:+ photosynthesis+ growth+ water use efficiency– wood density

O3 effects:– photosynthesis– growth– wax cuticle of leaves+ leaf senescence

Large starch grains

Normal aspen chloroplast

Intact thylakoid membranes

Ozone damaged chloroplast

Disintegration of thylakoid membrane

Membrane degradation material

Small starch grains

Cell-level Ozone Damage

0

2000

4000

6000

8000

Aspen Aspen-Birch

Aspen-Maple

Cu

mu

lati

ve

Ne

t P

rim

ary

Pro

du

cti

vit

yg

m-2

Stems & Branches

Fine Roots Coarse Roots

Foliage

Co

ntr

ol

CO

2

O3

CO

2 +

O3

Co

ntr

ol

CO

2

O3

CO

2 +

O3

Co

ntr

ol

CO

2

O3

CO

2 +

O3

a

c aa

a a

b b

b

aa

ab

CO2 and O3 Effects on Tree Growth

• Tree growth increases under elevated CO2 and

decreases under O3 in Aspen (not Birch)

• Carbon sequestration under elevated CO2 is

overestimated in models which do not consider

O3 impacts

• O3 damage to protective coating of leaves

(cuticular wax) reduces resistance to insects

(e.g., leaf miner)

• CO2 reduces the damaging effects of O3, but O3

counteracts growth stimulation by CO2

Research Findings I

• Cycling of C and N increases under elevated

CO2, but effects differ among FACE sites

• O3 counteracts most CO2-induced

enhancements in ecosystem processes (soil

respiration, N availability…)

• Elevated CO2 delays normal autumn leaf

senescence, predisposing some trees to winter

dieback

• Aspen and birch insects and diseases increase

under elevated CO2 and O3

– Cascading responses, trophic interactions

Research Findings II

Ozone affects plant & human health

“sunburns” lungs breathing difficulties

during exercise permanent lung damage

after repeated exposure

Photosynthesis Leaf size Leaf longevity Fine root biomass

Trophosphericozone &

Nitrogen cycle

Increased production of N pollutants

SMOGSMOG

Global change interactions

From Vitousek et al. 1997

Rates of global nitrogen fixation

• Increase production of greenhouse gases: nitric & nitrous oxide

• Eutrophication: ground water, streams, lakes, ocean

• Dead Zone (50 areas worldwide, including the Gulf of Mexico)

Hypoxic zone in the Gulf of Mexico is the

size of NJ.

Consequences of doubling Nitrogen fixation

From: www.ers.usda.gov

Two-thirds of Nitrogen in Mississippi comes from fertilizers & manure

How can you reduce bad ozone

•Choose a cleaner commute — car pool, use public transportation, bike or walk when possible. •Combine errands to reduce "cold starts" of your car and avoid extended idling.•Be sure your tires are properly inflated.•Keep car, boat and other engines properly tuned, and avoid engines that smoke. •Follow gasoline refueling instructions for efficient vapor recovery. Be careful not to spill fuel and always tighten your gas cap securely