Pollutants Flashcards
Define: Primary and secondary pollutants
Primiray: pollutants emmited directly into the air. (CO, NO/NOx, SOx, VOC, OM)
Secondary: are formed in the air when they react with other pollutants. (Sulfuric & Nitric Acid, NO2, Ozone, Secondary Particulates)
ie. Groundlevel ozone formed when NOx and VOC react in presence of light.
Atmospheric layers:
Defined by temperature change
1: Troposphere (0-12km) (80% mass of atmosphere) (weather, N2 78%, O2 21%, water vap 3% 1.5: Tropopause (temp invert warmer than below)
2: Stratosphere (12-50km) 2.5. Stratopause
3: Mesosphere 3.5. Mesopause
4: Thermosphere 4.5. Thermopause
5: Exosphere 5.5. Exopause
Pollutant types (classification)
Suspended particulate matter, gases, and vapors that are present in high concentration with net detrimental effects on environment and ecosystem as a whole
CAC
Criteria Air Contaminants : SOx, NOx, CO, PM (PM10 and PM 2.5.
Also frequently set for Ozone, H2S, Lead, HF, Formaldehyde (HCHO).
Greenhouse gases
CO2, Methane, N2O, CFC (chlorofluorocarbons), bromides/iodides, other gases (hydrocarbons, tropospheric ozone, water vapor), aerosols
Ozone depleting substances
CFC, Halons, Carbon Tetrachloride, Methyl Chloroform
Air pollution sources
Anthropogenic: Combustion (contaminants, incomplete combustion), transport, process emissions, consumer products and activities, personal
Natural: Biogenic (flaura, fauna), VOCs, pollen, geological, forest fires, weathering rock, ocean waves, wind (dust)
Impacts of pollution
human/animal health, vegetation, property, visibility
Airshed
Airmass that is geographically bound (valley, mtn… NOT country/municipal borders)
Emissions vs immissions
emissions: emited
imissions: concentration ambient
Particulate matter types
Coarse PM10 (typically natural sources), fine PM 2.5 (mostly human activities and reactions taking place in air; Finer particles are more damaging. Impact not only size but ALSO chemical composition PM's most studied type of pollutant. Larger fall out quicker due to gravity, finer float longer and can chemically react.
Physical behaviour/movement of particles in atmosphere
- Diffusion (random Brownian molecular movement)
- Dispersion (external flow effect causing discrete movement)
- Rx with atmospheric gases for creation
- Coagulation (create bigger chunk)
- Condensation (vapour to liquid)
- Sedimentation (dry deposition removal)
- Precipitation (wet deposition removal)
Particulate matter chem processes and composition
Org pollutants and NOx, Atmos gas to particle conversion, combustion process.
-Chem composition: inorg particles -toxic metals - org particles - radioactive particles
Human entry points: breathing, swallowing, dermal
CO
- intermediate in oxidtion of methane by hydroxyl radical
- degradation chlorophyll in autum
- anthropogenic (more in less tech advance countries, inc. burning no scrubbing)
- Toxicity (prevents O2 in blood stream)
NOx Nitrogen Oxides
NO - Colourless, odourless (competes with O2 in body)
NO2- pungent, red-brown
natural sources (lightning, biol process) combustion of fossil fuels (mostly NO)
NOX, NO less toxic NO2,
N2O, microbiol process, unreactive,
Sulphur oxides
Human activities (S in coal, metallurgical processes)
Natural (Marine, volcanic, biol decay org matter)
Effects atmos SO2: inc breathing effort but not really toxic, harmful to plants, deterioration building materials, acid rain, NOX plus VOCs make ground level ozone
Troposphere
oxidative medium (radicals: OH, NO3, O, HO2, H2O2) photochem rx, high conc water vapor.
-3 end removal processes: -chem conversion to h2o, o2 -dry deposition (gases absorbed by plants, water, soil)
-wet deposition
(goes elsewhere in system…)
CH4 dominant hydrocarb, gas phase chem involves oxidation of org molecules in presence of oxides of nitrogen with sunlight
Air pollution and health
Mortality (death), Morbidity (disease) studies
Study controlled acute human exposure
AQHI: 1-10 scale takes into consideration: O3, OM2.5, NO2
