Biology 381 |
5. Long range transport of air pollutants. |
5.1 Required Reading and other announcements.
No required reading. Web links to chernobyl provide for interesting reading.
5.2 The dilution solution to pollution.
Ever since man's discovery of fire, the attitude that "dilution is the solution to pollution" has dominated our thinking about pollution abatement.
Given adequate space for pollutants to disperse, the atmosphere has some capacity to assimilate wastes without any deleterious effect.
Figure 13-1, Nebel (1987).
By emitting pollutants higher into the atmosphere, mixing and dilution is facilitated, and the amount of area exposed to toxic levels of the emitted pollutant is decreased.
Can you raise any concerns about the use of this "solution"?
Scientists and governments alike are beginning to realize that the dilution solution has been carried to extreme.
5.3 Long-range transport of air pollutants.
Scientific evidence now suggests that pollutants may be transported over tremendous distances, a phenomenon aptly labeled as long range transport of air pollutants, or LRTAP.
Three types of evidence support the occurrence of LRTAP.
Direct monitoring of pollutant transport.
Satellite imagery provides evidence of long range transport.
Monitoring of pollutant loading in remote areas.Satellite imagery of pollutant transport. Title page photograph, Office of Technology Assessment, Congress of the United States, 1985. Acid Rain and transported air pollutants. Implications for public policy. UNIPUB, New York, 323 pp.
How do we know that the ozone and sulfate in this haze is anthropogenic?In remote areas, ozone concentrations are correlated with carbon monoxide, an unreactive "tracer" of man-made pollution.
The nuclear mishap at Chernobyl, USSR (April 26, 1986).
http://www.greenpeace.org/~comms/nukes/chernob/cherfoto.html
http://www.brama.com/ukraine/cbyl.htmlhttp://www-bcf.usc.edu/~meshkati/blast.jpg
Large amounts of radioactivity (perhaps >1014 Becquerels) were released into the environment, with the greatest emissions occurring during the first ten days of the event.
Daily release of radioactive substances into the atmosphere during the Chernobyl accident. Figure 1, Medveddev (1987).
The accident left a major fall-out trail in Belarus, Ukraine and Russia.http://www.edvz.sbg.ac.at/~belyakov/lhp/chern.html
Ten days after the accident, radioactive material from the plant was detectable at low levels over much the entire Northern Hemisphere.http://www.brama.com/ukraine/cbyl.html
http://www.greenpeace.org/~comms/nukes/chernob/cherfoto.html
Long term trends in Atmospheric turbidity at Mauna Loa, Hawaii.Occurrence of ecological damage in remote areas.http://mloserv.mlo.hawaii.gov/default.htm
Atmospheric turbidity at Mauna Loa, Hawaii; Figure 13-3, Nebel (1987).
Atmospheric turbidity in Mauna Loa has been increasing (1957-1967), presumably as a result of LRTAP.Where variation exists in environmental data, natural events may distort short-term views of long-term trends.
Lead in Greenland glaciers.
Lead levels in Greenland Glaciers; Figure 13-5, Nebel (1987).
Long-term trends in concentrations of lead in Greenland glaciers indicates long-range transport of lead to remote regions is increasing.The rate of long-range transport has increased dramatically since 1940-1950.
Figure 4, Taylor (1981).
The height of injection into the atmosphere.
Figure 2.7, Park (1987)
Long-range transport is favoured by turbulent atmospheric conditions, with a vertical temperature gradient and high wind speeds.
Localized pollution episodes are favoured in stagnant air masses under conditions of temperature inversions.
Once in the atmosphere, particulates are deposited by three processes, sedimentation, impaction, and washout.
Sedimentation occurs on surfaces, and is most important with large, heavy particles because sedimentation rates varies with particle density.
The efficiency of collection by impaction (per unit surface area) increases with decreasing diameter of the obstruction, increasing diameter of the particle, and with the stickiness of the collecting surface.The efficiency of washout by rainfall also increases with particle size.
Small,light particles tend to remain in the atmosphere for longer periods of time that large, dense particles. Thus, small light particles are more prone to long-range transport.
Figure 3-1, Bubenick, D.V., 1984. Acid rain information book. Second edition. Noyes publications, Park Ridge, New Jersey, 397 pp.
Figure 5-1, Smith, W.H., 1981. Air pollution and forests. Interactions between air contaminants and forest ecosystems. Springer Verlag, New York. 379 pp.
5.5 Pollution episodes.
Two factors control the final concentration of air pollutants, output and dispersion.
One of the common factors in most of our "pollution disasters" is not a sudden increase in output, but rather sudden changes in the dispersion of air pollutants.
Two factors are important, still weather and temperature inversions.
Figure 13-9, Nebel (1987).
5.6 Tools for investigating the effects of air pollutants.
Controlled environment chambers
http://www.biology.ualberta.ca/biotron.hp/biotron.htm
Field Observations
Open top chambers
http://bio-www.uia.ac.be/bio/pleco/opentop.html
Free Air CO2 Exchange (FACE) facilities
http://www.lter.umn.edu/biocon/
Figure 13-15, Nebel (1987)
5.7 Designing a pollution nightmare.
5.8 Additional world wide web information.
Deadly Meltdown. Because the Soviets kept details secret, the Western press speculated about actual developments at Chernobyl. A Times Inc. report from 1986.
A Greenpeace Photo album. A collection of photos from the reactor site and surrounding area.
Dr. Meshkati's Page on Chernobyl. A pile of Chernoble links.