atmospheric chemistry - take 2

No matter how sophisticated you may be, a huge granite mountain cannot be denied--it speaks in silence to the very core of your being. Ansel Adams

Art completes what nature cannot bring to finish. Aristotle

Art is lies that tell the truth. Picasso

Science has not yet taught us if madness is or is not the sublimity of the intelligence. Edgar Allan Poe

Atmospheric Chemistry - Take 2Atmospheric Chemistry - Take 2Energy equation in the atmosphere:Energy equation in the atmosphere:

E = hC/E = hC/Where Where is radiation wavelength is radiation wavelength

NN22 + h + h 2N ( 2N ( < 126 nm) < 126 nm) HHoo = 945 kJ mol = 945 kJ mol-1-1

OO22 + h + h 2O ( 2O ( < 240 nm) < 240 nm) HHoo = 498 kJ mol = 498 kJ mol-1-1

NN22 (g) + O (g) + O22 (g) (g) 2NO (g) 2NO (g) GGoo = +173 kJ mol = +173 kJ mol-1-1

Does not occur at ambient T but does at high TDoes not occur at ambient T but does at high T(engine combustion ~ 2500(engine combustion ~ 2500C)C)

The reverse reaction is favored thermodynamically but The reverse reaction is favored thermodynamically but too slow at ambient T (kinetics!) too slow at ambient T (kinetics!) other reactions other reactions

Atmospheric Chemistry - Tropospheric Atmospheric Chemistry - Tropospheric ozoneozone

2NO + O2NO + O2 2 2NO 2NO22

NO + ONO + O3 3 NO NO22 + O + O22

The second partner needed in the ozone formation cycle are The second partner needed in the ozone formation cycle are organic peroxides and free radicals (Organic molecules are organic peroxides and free radicals (Organic molecules are emitted from forests and other plants but also from human emitted from forests and other plants but also from human sources - e.g. solvents or fuel at filling stations)sources - e.g. solvents or fuel at filling stations)

CO + CO + OH OH H + COH + CO22

CHCH44 + + OH OH CHCH33 + H + H22OO

CHCH33 + + OH OH CCHH22 + H + H22OO

ROOH + ROOH + OH OH ROO ROO + H + H22OO


NONO22 (h (h, , <400 nm) <400 nm) NO + O NO + O

O + OO + O2 2 + M + M O O33

ROOROO + NO + NO RO RO + NO+ NO22

NO + ONO + O3 3 NO NO22 + O + O22


• If no nitrogen oxides are available, the reaction cycle cannot take place.If no nitrogen oxides are available, the reaction cycle cannot take place.• If too much nitrogen oxides are available the excess of nitrogen oxide NO If too much nitrogen oxides are available the excess of nitrogen oxide NO

reacts not only with the peroxy-radicals but removes the ozone again.reacts not only with the peroxy-radicals but removes the ozone again.• If no sunlight is available NO cannot be recycled again and the formation If no sunlight is available NO cannot be recycled again and the formation

of peroxy-radicals is not sufficient.of peroxy-radicals is not sufficient.


Urban traffic is not the only source of ozone Urban traffic is not the only source of ozone They can come They can come from other combustion processes: vegetations fires.from other combustion processes: vegetations fires.


NASA Earth Probe Total Ozone Mapping Spectrometer (TOMS) - Indonesian (Oct NASA Earth Probe Total Ozone Mapping Spectrometer (TOMS) - Indonesian (Oct 1997)1997)

Atmospheric Chemistry - Take 1Atmospheric Chemistry - Take 1Sources of CO and NOx Emissions in Europe

• In Europe, in 2001, 30 679 Gg of CO was emitted. The main source In Europe, in 2001, 30 679 Gg of CO was emitted. The main source of anthropogenic CO in the air was transportation (60%), and the of anthropogenic CO in the air was transportation (60%), and the industry contributed to 36% of the total emission. Waste industry contributed to 36% of the total emission. Waste management and agriculture were of marginal importancemanagement and agriculture were of marginal importance;

• Transportation was also the main source of NOx as it delivered Transportation was also the main source of NOx as it delivered 63% of the total emission which amounted 10 056 Gg in 2001. 63% of the total emission which amounted 10 056 Gg in 2001. Industry contributed to 35% of the total emission. Again, emissions Industry contributed to 35% of the total emission. Again, emissions from waste management and agriculture were of marginal from waste management and agriculture were of marginal importance.importance.

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Atmospheric Chemistry - Take 2Atmospheric Chemistry - Take 2Sources of HC and NOx Emissions in New England• Large industry such as chemical manufacturers, and combustion

sources such as power plants burning fossil fuels;• Small industry such as gasoline-dispensing facilities, autobody

paint shops, and print shops;• On-road automobiles, trucks and buses;• Off-road engines such as aircraft, locomotives, construction

equipment and gasoline-powered lawn and garden equipment.

Atmospheric Chemistry - Take 2Atmospheric Chemistry - Take 2Sequence of of chemical species appearing during a Sequence of of chemical species appearing during a

photochemical smog event.photochemical smog event.

Ozone formation and atmospheric Ozone formation and atmospheric conditionsconditions10AM10AM

Source: USEPA - Region 1 (New England)Source: USEPA - Region 1 (New England)

Ozone formation and atmospheric Ozone formation and atmospheric conditionsconditions11AM11AM

Ozone formation and atmospheric Ozone formation and atmospheric conditionsconditions12PM12PM

Change in regulation of ozoneChange in regulation of ozoneIn July 1997, based on information that the 1-hour ground-level ozone standard did not adequately protect public health, EPA established the 8-hour ozone standard. Scientific information shows that concentrations of ozone in the air can affect human health at low levels and over longer exposure periods concentrations to 0.08 ppm, averaged over eight hours. The 1-hour standard limits ozone concentrations to 0.12 parts per million (ppm), measured in hourly readings. Much of New England was previously designated nonattainment under the the 1-hour standard.

Ozone formation and climate changeOzone formation and climate change

Climate change can influence the concentration and Climate change can influence the concentration and distribution of air pollutants through a variety of direct distribution of air pollutants through a variety of direct and indirect processes:and indirect processes:

modification of biogenic emissionsmodification of biogenic emissions change of chemical reaction rateschange of chemical reaction rates mixed-layer heights that affect vertical mixing of mixed-layer heights that affect vertical mixing of

pollutants, andpollutants, and modifications of synoptic flow patterns that govern modifications of synoptic flow patterns that govern

pollutant transport.pollutant transport.

For example, warmer temperatures can result in For example, warmer temperatures can result in increased concentrations of photochemical oxidants increased concentrations of photochemical oxidants and increased rate of Oand increased rate of O33 production. production.

Ozone formation and climate changeOzone formation and climate changeThe frequency and duration of extreme ozone events is predicted to increase

under the climate scenarios for future decades.

Regional climate change was found to cause significant increases in the simulated 4th-highest 8-hr O3 concentration in summertime of future years. consider the effects of a changing climate when planning for the future attainment of regional-scale air quality standards such as the U.S. NAAQS (4th-highest annual daily maximum 8-hr O3 concentration).

Ozone formation and Reformulated Ozone formation and Reformulated GasolineGasolineHow should regulatory agencies determine if one RFG blend using a

particular oxygenate is preferable to another?

In attempting to mitigate ozone pollution, the USEPA currently addresses such questions by estimating the mass of VOC emissions resulting from the use of an individual RFG blend. If the estimated mass of emissions exceeds a specified amount, that fuel blend is disallowed. Although certain fuel blends, such as those using ethanol, might result in greater amounts of emissions in terms of mass (because of the volatility of ethanol), it is argued that those emissions have a lower ozone-forming potential compared with emissions from other fuel blends.

Therefore should EPA's assessment of RFG blends be based not only upon mass of emissions, but also upon their reactivity (i.e., ozone-forming potential)?

Ozone formation and Reformulated Ozone formation and Reformulated GasolineGasolineHow should regulatory agencies determine if one RFG blend using a

particular oxygenate is preferable to another?

Peak ozone concentrations in 41 metropolitan areas in the United States decreased by about 10% overall from 1986 to 1997 despite growing fuel usage. Nevertheless, in 1997, about 48 million people lived in areas of the United States that were classified as ozone "nonattainment" areas, and promulgation of the new 8-hr National Ambient Air Quality Standard (NAAQS) of 0.08 parts per million (ppm) for ozone is projected to triple the number of counties in nonattainment and to result in extensive nonattainment in rural areas of the eastern United States. The persistence of ozone pollution has sparked a need for innovative approaches to mitigation, and the RFG program is one such attempt.

Ozone formation and Reformulated Ozone formation and Reformulated GasolineGasoline

Air-quality models suggest that implementation of the RFG program reduces peak ozone concentrations by only a few percent. Even if the relative contribution of motor vehicles to the current inventory of ozone precursor emissions from all sources has been underestimated (which, historically, has often been the case), the reduction in peak ozone from the RFG program would still likely be less than 10% at most. Although long-term trends in peak ozone in the United States appear to be downward, it is not certain that any part of these trends can be significantly attributed to the use of RFG.

Source: National Academy of Science

Limit and Alarm ValuesLimit and Alarm Values For nitrogen dioxide (NOFor nitrogen dioxide (NO22), sulphur dioxide (SO), sulphur dioxide (SO22), lead (Pb) and ), lead (Pb) and

particulate matter of the diameter up to 10 µm (PMparticulate matter of the diameter up to 10 µm (PM1010), the limit ), the limit

values are given as values are given as mean annual concentrationmean annual concentration.. .. For ozone (OFor ozone (O33) and carbon monoxide (CO), the limit values are ) and carbon monoxide (CO), the limit values are

given as given as mean 8-hour concentrationmean 8-hour concentration.. For NOFor NO22, SO, SO22 and O and O33, apart from limit values, there are also alarm , apart from limit values, there are also alarm

values established. Those are values established. Those are mean 1-hour concentrationsmean 1-hour concentrations..







Source: Max Plank Source: Max Plank instituteinstitute

This afternoon This afternoon

Lab #3: Lead in Urban Regions: A temporal analysis.Lab #3: Lead in Urban Regions: A temporal analysis.

atmospheric chemistry - take 2

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