Air pollution
GEOLOGYTWO
J.D. Price
Pollution
For the purposes of this class, we will define pollution as anthropogenic
contributions to the natural system that demonstrably alter the
environment (change the natural system).
Concentration is the real culprit, and varies from contribution to
contribution.
Industrialization tends to
• Localize waste products - concentrated point sources (e.g. sewer
pipes and smokestacks)
• Increased energy use - increased waste products from energy
generating processes (I mean energy in its broad physical sense)
• Refine and consolidate natural chemicals far above natural levels (e.g. a
small natural oil seep vs. a 2 billion ton oil tanker)
Greenhouse gasses
Gas
CO2 (carbon dioxide)
CH4 (methane)
N2O (nitrous oxide)
freons & other CFCs*
water vapor
atm. level (2000 m)
368 ppm
1.76 ppm
0.3 ppm (~316 ppb)
0.001 ppm
variable; up to ~4%;
average of ~ 0.4%
*Something to note - all the other gasses are produced naturally, but
CFC’s are all the result of human input.
The atmosphere is both volumetrically
small and dynamic. Human activity
influences its chemistry. In the
stratosphere, anthropogenic release of
refrigerants has reduced the
concentration of ozone.
Ozone formation
Ozone is a triatomic version
of oxygen (O3)
It requires additional energy
to form, and does so in
strong electrical fields
(lightning) and under UV
radiation.
Once formed, it absorbs
harmful UV-B (! = 280 to
320 nm) into its structure.
Ozone measurement
We measure ozone by
the amount of UV
absorption. Ozone is a
minor component within
the atmosphere, even
within the “layer” in the
stratosphere. The
measurement is
presented as a Dobson
Unit - a vertically
independent scale over a
specified area.
Ozone hole
Image of excessively
depleted ozone over
Antarctica
2003
Note: October is start of
Austral Spring
Ozone concentration is always
diminished at poles due to light
conditions, stratospheric clouds,
and air movement. There is a
seasonality based on direct
sunlight and atmospheric
movement.
Global thinning
The “hole”: the depleted level of ozone within the mid
stratosphere over high latitudes each spring (Oct – south,
April – north)
The hole is not a region of the atmosphere where there is
excessive UV-B radiation (recall the relative amount of
direct solar radiation at the poles)
The holes’ locations are not widely distributed - they are a
polar phenomena.
The hole is a sink for ozone elsewhere
on the globe: net effect is an overall
thinning of mid stratosphere ozone
layers.
Depletion
Chlorine couples with
ozone, produces an O2
and ClO. This joins with
another O to make O2
and frees the Cl.
Ozone reduced, more
UV-B reaches Earth’s
surface.
CFC’s in the stratosphere
may lose Cl due to UV,
increasing Cl in
stratosphere.
CFC’s and warming
Recall that IR generated by the
earth is also part of the problem this is far IR (peak is at about 10
microns), There is absorption
here for H2O and CO2. And there
is a “window” around 10 µm
where these absorb little, but
CFC’s absorb a lot.
CFC (Chlorofluorocarbon) timeline
1930: Kinetic Chem. Co. develops Freon® (CFC fluid) to
replace toxic refrigerants (e.g. ammonia)
Freon - preferred refrigerant for much of the 20th C. Also
extensively used as an aerosol propellent.
1974 - F. S. Rowland and M. Molina demonstrate
decomposition of CFC’s could produce elevated Cl in
stratosphere react with ozone.
1987: Montreal Protocol initiated by 27 countries – promise
to cut CFC usage in half by 2000
2015?: Spring ozone depletion no longer observed
Measurement
NOAA data
Surface CFC concentration in dry air in parts per
thousand (ppt). CFC concentration has leveled off under
usage guidelines.
G’house gasses revisited
GH effect
per molec.
est. atm. increase
(2100 – pre-ind. levels)
equivalent CO2
increase
CO2
1 (ref.)
~280 ppm
(560-280)
280 ppm
CH4
25
~1.75 ppm
(2.5-0.75)
44 ppm
(25 x 1.75)
N2 O
230
~120 ppb
(390-270)
28 ppm
(230 x 0.12)
CFCs
15,000
~0.4 ppb
(0.4-0)
6 ppm
(15,000 x 0.0004)
Models
1) The NCAR (National Center for Atmospheric Research)
Model – NCAR is a branch of NOAA, the National Oceanic
and Atmospheric Administration.
2)The GFDL (Geophysical Fluid Dynamics Laboratory)
Model – GFDL is at Princeton. Their’s was one of the first
GCMs.
3) The GISS (Goddard Institute for Space Studies) Model.
Associated with Columbia U, funded primarily by NASA.
Understanding the rapidly changing atmospheric - hydrospheric
conditions requires evaluation of a large number of variables. Each of
these models takes a different route - but all generally agree. By the
end of the century, we can anticipate a 2 to 4ºC warmer atmosphere.
Late last year, this study
pointed out that we’re
missing a Greenhouse gas,
NF3. Used in high-tech
industry, release is
minimized, but substantial
and increasing.
Worrisome because of its
high GWP and lifetime
(550 years).
There is no policy protocol
for curbing NF3.
Carbon Reservoirs
The carbon cycle showing the reservoirs of carbon storage
(in gigatons) and movement in gigatons per year).
Six common air pollutants
Carbon Monoxide
Nitrogen Dioxide
Sulfur Dioxide
Particulates
Lead
Ground Level Ozone
Carbon Monoxide
•Carbon monoxide reduces oxygen delivery to the body's organs.
The thread is greater for those with heart disease.
•High levels of CO causes vision problems, reduced ability to work
or learn, reduced manual dexterity, and difficulty in performing
complex tasks. At extremely high levels, CO is poisonous and can
cause death.
•CO contributes to the formation of smog ground-level ozone,
which can trigger serious respiratory problems.
•Reductions in CO have resulted from tighter emission standards
on automobiles (e.g. catalytic converters).
CO
Particulate matter
PM
PM
•Small particles (<10µm) can become entrained deep in the lungs and
possibly enter the bloodstream to cause serious health problems.
•Fine particles (PM2.5) are the major cause of reduced visibility (haze)
•Clean air policy to reduce emissions at sources.
Size matters
Sulfur dioxide
Emissions are dominated by coal burning. Many coal sources contain
disseminated sulfide minerals - these end up oxidizing during
combustion
SO2
•Contributes to respiratory illness, particularly in children and the elderly,
and aggravates existing heart and lung diseases.
•Contributes to the formation of acid rain, which damages trees, crops,
historic buildings, and monuments; and makes soils, lakes, and streams
acidic.
•Contributes to the formation of atmospheric particles that cause
visibility impairment, most noticeably in national parks.
•Can be transported over long distances and deposited far from the point
of origin. This means that problems with SO2 are not confined to areas
where it is emitted.
•Ideally, much could be mitigated by not using sulfur rich coal, or not
using coal at all, but politics is an issue…
Reductions
US sulfur dioxide emissions have been declining since the adoption of the
Clean Air Act, largely due to “scrubbing” at coal-fire energy sources. This
could be reduced further by either restricting the sulfur content in coal,
moving to natural gas, or moving away from fossil fuels.
Acid formation
“Dry” SO2 and NO are also associated with acid deposition.
SO2 !" SO3 + H2O !"H2SO4 (sulfuric acid)
NO !"NO2 + OH !" HNO3 (nitric acid)
OH ?? - an important atmospheric oxidant produced from
O2 + uv ! O + O
O + H2O !"2 OH
Liquid droplets of sulfuric and nitric acid are major components of
“dry” acid deposition.
“Wet”
In fog and clouds,
HNO3 + H2O !"H++ NO3H2SO4 + H2O !"2H++ SO42-
The H+ (hydrogen ion) derived from these acids is the source of
excess acidity in acid precipitation and fog (wet deposition). About
half of acid deposition is “dry” and about half is wet.
Acid rain
Acidic rainfall is a problem east of the Mississippi because of a higher
density of coal-fired plants and sulfur-rich coal sources.
Sensitive, New York
The Adirondacks are an acid
sensitive area.
Orographic effect - lake weather
where water is precipitated out.
Not much CaCO3 in the soils to
buffer acid in rain. Robs this
nutrient from the plantlife.
Runoff ponds into numerous lake
basins - flushing is slowed.
Ohio Valley sulfur inputs end up
here.
Phelps Mountain photo courtesy of C. French.
Fuel from swamps
Coal is the end product of anoxic heating
and consolidation of organic materials think swamps that are then buried,
compressed, and heated over millions of
years.
When you burn a piece of coal, you’re
essentially burning off the hydrocarbon
material (what’s left of the plants) - and
that is what produces the heat, but you’re
also mobilizing everything else that was
buried with it.
We mentioned sulfides - this may include
small amounts of mercury sulfide. It may
also include a trace amounts of uranium or
thorium oxides or phosphates.
We’ll come back to this…
More radioactive than nuclear?
Source: Oak Ridge National Labs
Lead
Lead is a pollutant that is much improved from the part. Prior to 1973, the
largest source was automobiles - lead triethylate was added to fuels to
improve engine combustion. Now, it’s point sources from smelting and
battery making.
Nitrous oxides
•Helps form ground-level ozone, which can
trigger serious respiratory problems.
•forms nitrate particles, acid aerosolswhich also
cause respiratory problems.
•contributes to formation of acid rain.
•contributes to nutrient overload that deteriorates
water quality.
•contributes to atmospheric particles, that cause
visibility impairment.
•reacts to form toxic chemicals.
•contributes to global warming.
•NOx and the pollutants formed from NOx can be
transported over long distances,
NOx
Nitrogen oxides are also a greenhouse gas. Transportation
introduces most of these to the atmosphere.
Volatile Organic Compounds
The EPA defines VOC’s as compounds that participate in a
photoreaction. The typical implication of photoreactivity is in groundlevel ozone.
Ground Level Ozone
Ground-level ozone results from chemical reactions
between oxides of nitrogen (NOx) and volatile organic
compounds (VOC) in the presence of sunlight.
Breathing ozone can induce chest pain, coughing,
throat irritation, and congestion. It may worsen
bronchitis, emphysema, and asthma. Ozone can
reduce lung function; repeated exposure may scar
lungs.
Ground-level ozone damages vegetation and
ecosystems. In the United States alone, ozone is
responsible for an estimated $500 million in reduced
crop production each year (EPA).
SMOG
Ozone (O3) in the troposphere is a
very toxic lung irritant.
PAN (peroxyaclynitrate) is a most
potent eye and respiratory irritant in
smog.
Stagnant conditions and temperature
inversions exacerbate smog episodes.
Note that this catalyzes PAN and
ozone formation - comes back for
more.
Poison air
Great London Fog of
December, 1952.
Relation between
mortality and
pollutant
concentration. From
Wilkins (1954) and
www.ace.mmu.ac.uk/.
../ Air_Quality/02.html
Inversion layer
Sometimes the ground is colder - valleys* on cold nights will
cool off faster than the more dynamic air above. Creates a
boundary in which any relatively warm air becomes trapped.
*Many urban areas are concentrated into river valleys, because
of the cheap transportation rivers provide.
Asbestos and health
Crocidolite (amphibole) - 25mL per min
per mouse produces significant and
early increase in mutations. Rhin et al.,
2000
Chrysotile (tube) ~20 mg per rat show
correlation between fiber concentration
and chance of mesothelioma Jurand et
al.
In general, crocidolite has a much more pronounced effect. Is it
just crocidolite (riebeckite) or is it an amphibole problem?
Asbestos and health
The main cause of concern mesothelioma (cancer of the pleural
cells). This rare type of cancer
seems only relatable to high fiber
occupational exposure - Mossman et
al.
Left - Malignant mesothelioma from Chainian & Pass,
1997
Asbestosis - another occupational
disease where fibers have scarred
the lungs
So far, there is insufficient evidence for an effect due to casual
exposure. Is asbestos worth the attention?
Cancer remains enigmatic - cause and effect relationship
Dust
Particles that may be bioactive.
Mucus membranes can remove
large particles, macrophages small
equant ones. Macrophages may
struggle with elongate particle
less than 100 microns.
Electron optics are necessary to
resolve airborne asbestos
particles. Diffractometry is
needed to characterize mineral.
SE image of fibers
In general - dusts are not healthy. Prolonged exposure to any
mineral dust may be hazardous to health
Silicosis - long-term exposure to crystalline silica. Phage
resistant, small particles remain intact after phagiocytosis.
Pneumonoultramicroscopicsilicovolcanoconiosis* is silicosis
specifically brought on by long-term exposure to volcanic ash.
Boys** in Yakama, WA wear
dust masks in the days after
the May 18, 1980 eruption
of Mt. Saint Helens.
Yakama, in central
Washington, was darkened
by ash on May 18.
Dust in the environment is
difficult to remediate
*Longest word in OED and Websters, also mentioned on The Simpsons 2F07
**Prof owned same sporty orange vest in 1980, however his bike was 30% less cool
(darn fenders!).
Radon
Radon-222 is natural, but
we’ll mention it here because
human activity can promote
dwelling and working
environments that maximize
exposure.
Radon is produced from the
decay of U-238 in rocks.
Because it is a gas, it escapes
through cracks and may find
its way into air and water.
Prolonged exposure has been
linked to cancer.
Ventilation is key to reduce
exposure.
Radon
Radon levels are controlled by local geology. This county-by-county map
of the US shows low risk areas in yellow, moderate risk in orange, and
high risk in red. Rensselaer county is indeed red - areas like this contain
glacial materials, which contain uranium bearing rocks in high permeability
materials.
Depleted uranium
National Lead
Industries operated a
depleted uranium plant
in Colonie from
1951until 1984. A
recent study by Parish
et al., 2007 concluded
the plant made
significant releases of
small airborne particles
to the environment.
Health effects have
been chiefly noted in
former workers and
neighbors.
NLI local contamination
Plot of depth (cm) against both U (ppm)
and 238U/235U of the lake sediments. The
decline of U concentration at 90 cm is
inferred to coincide with the closure of the
plant in 1984. The dip in concentration of U
between 140 and 110 cm is the result of
sediments during I-90 construction.
Examples of lake sediment
U-rich particles