Air Pollution Quiz Study Guide PDF

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Air Pollution Study Guide Lecture 1 – Atmospheric Drivers of Air Pollution/Air Quality Air Pollution vs Air Quality  natural/man-made substances in atmosphere quantities/concentrations higher than normal ambient levels vs. conditions of ambient air based on National Ambient Air Quality Standards concentration levels Temp inversion on air pollution dispersion vertical temp gradients define different atmospheric layers. Troposphere relatively unstable – characterizes day to day as temp, cloud cover, precipitation, humidity. VERY important in air pollution transport and dispersion. Atmospheric Stability – air mass rise or sink spontaneously. Important role in formation of precipitation (wet deposition) & mixing pollutants away from surface. Temp/elevation determinant of atmos. stability. Ease of moisture, energy, momentum, matter move vertically in atmosphere at place & time. Stable Atmosphere – little vertical mixing. Difficult for energy, moisture & matter to transport vertically. Pollutants emitted near surface, stay near/at source. Unstable Atmosphere – air forced to rise, continue to rise even when initial lifting force is removed. Enhanced upward transport of moisture and energy from surface Neutral Atmosphere – Parcel or air neither rise nor sink. Internal temp same as ambient envir. Lecture 2 – Atmospheric Motion Cyclones (L) surface winds counterclockwise in Northern Hem. & converge. Air Mass spiral inwards. Surface air ascends, condensation, cloud formation, precip. Anticyclones (H) Air mass spiral outwards around (H) P center. & diverge. Upper level air descend (subsidence) & warmed adiabatically. Clear, calm weather. Trap air near surface (sinking motion). Land-sea breezes  DAY-Land heats more qucky than sea & circulation pattern w/sea breeze. NIGHT-land cools more quickly, circulation pattern w/land breeze. Enables transport of pollutants. Air masse and fronts: effects on air pollution Mountain Breeze Lecture 3 – Air Pollution and Pollutants Criteria/Common Air Pollutants – commonly found in air. Aka – primary pollutants 6 Criteria – PM 2.5/10, Ground-level/Tropospheric Ozone(O3), CO, SO2/SOx, NO2/NOx, Pb. Toxic to health Fugitive PollutantsEmissions, leaks through pipes or storage tanks Sources – Urban/Industrial, Agriculture, Natural Emissions. Natural Sources– Wind Erosion, Forest Fires, Volcanic Eruptions, Biogenic emissions(wetlands) Urban/Industrial–Power generation(fossil),Industrial facilities(mining, paper pharamceut), Transportation Primary Pollutantspollutants emitted directly from source & does not undergo chem. Or physical transformations.EX: CO,VOC Secondary pollutantsformed in atmosphere result of chemical reactions among primary pollutants. EX: Tropospheric Ozone. Pollutants in CT – Pb, CO, NO, PM2.5&10, VOC in Hartford, Bridgeport & New Haven. High SO2 – New London, Bridgeport, Windham. Lecture 4 & 5 – Gas-Phase Pollutants Gas Phase Pollutants – COx – colorless/odorless, largest source –cars. Extremely toxic in home. Carbon Sink – transformation of chem pollutants into more stable substances. CO oxidized in atmos. CO2 on reaction w/ OH. SOx- sulfur & oxygen compounds produced when sulfur containing fossil fuels are burned. SO2-Dominates emissions from man-made sources. Volcanic eruptions&hot springs –natural sources. NOx- contribute to acird prec & photochemical smog. (ozone in lower atmosphere). Cars = primary source. N2O- N based fertilizers, deforestation, biomass burning. KEY IN GREENHOUSE GAS. SECONDARY POLLUTANTS - O3 – from sunlight initiated oxidation of VOCs in presence of nitrogen oxides. Occurs in Stratospheric Ozone (absorbs UV radiation, forms protective layer that shields us from suns

Air Pollution Study Guide harmful UV rays) & Tropospheric Ozone (VOC+NOx+Heat+Sunlight=Ozone. Car, Industrial emissions, gasoline vapors, chemical solvents = major source of NOx & VOC to form ozone. NO2 split by sun & forms O atoms & NO. O atoms react w/ molecular O in air & forms O3. NO2+O2 NO+O3 VOC – emitted by biogenic&anthropogenic sources. Easily Evaporate at temp of its natural temp. Sourcessolvents (degreasing, dry cleaning), hydrocarbons (organic compounds CH4), cars. PM – very small pieces of solid material dispersed & suspended in atmosphere. Source – smoke, soot, dust. Burning fuels in cars, homes, industries. PM10-arsenic, copper, Pb, asbestos, zinc. PM2.5-smaller than2.5um. Lecture 7 – Transport and Dispersion of Air Pollution Factors influencing transport and dispersion of pollutants 1. Wind (speed & direction). Horizontal pressure & temp gradients. Friction related to surface roughness. Important for dilution of plume. 2. Turbulence (i)Mechanical Turbulence – air moving over and around built structures/vegetation, increase w/ wind speed, influenced by surface roughness. (ii) Thermal Turbulence – heating/cooling of earth’s surface, triggers vertical flow (convection cells of rising warm air and descending cooler air). Turbulence can enhance pollutant mixing & dispersion (except downwash in turbulence wake downwind of source). 3. Atmospheric Stability – in stable atmosphere conditions inhibit vertical motion. Unstable atmosphere enhance vertical motion. Vertical air motion depend on vertical temp gradient. 4. Temp Inversion. Subsidence Inversion – descent of air within high pressure mass. Inversion layer tend to form aloft. May cover large area & persist for days. Radiation Inversion – radiation at night from earth’s surface into the local atmosphere, due to cooling of the ground. Intensified in river valleys, results in pollutants being trapped. Stronger inversion may form over urban areas (heat island effect or dust dome). DISPERSION – Point Source Pollutants – emitted in plume form. Air quality depends on dispersion and height of plume. Different shapes of plumes and atmospheric stability conditions Looping – unstable atmosphere (limited/no vertical motion), calm wind, common during daytime, strong turbulence (good for dispersing pollutants. Fanning – formed under ground based inversion condition (stable). Expands horizontally, not vertically. Low ground level concentration. Lofting – ground level inversion layer, before sunrise or if stack is tall, none/limited ground level concentration Fumigation- stable atmosphere above plume emission. Unstable below. Trapping – radiation inversion at ground level subsidence. Inversion at high-level altitude Coning – neutral to isothermal temp lapse rate, strong wind, no turbulence, good for dispersing pollutants. Effects of Pollutants on Visibility – gas absorption & scattering, aerosols & hydrometeor particle absorption, aerosols & hydrometer particle scattering (reflection, refraction, dispersion, & diffraction).  Visibility defined by ability of our eyes to distinguish an object from surrounding background. Scattering solar radiation by aerosols is main process limiting visibility in troposphere. Anthropogenic aerosols in urban envir. Reduce visibility. Reduction is greatest at high relative humidity when aerosols swell by uptake of water increasing cross-sectional area for scattering (haze formation) Lecture 8 – Removal and Deposition of Air Pollutants Dry Deposition  acid chemicals incorporated into dust or smoke & fall to ground through dry. Stick to ground, buildings, homes, cars, trees. Half of acidity in atmosphere falls back to earth. Direct transfer of gas and particulate phase substance to veg, water, etc. sedimentation & diffusion to surfaces.

Air Pollution Study Guide Wet Deposition  acidic rain, fog, snow. Fall to ground in rain, snow, fog, mist. Affects plants animals. NOxHNO3. SOXH2SO4 +Deposition velocity=-flux of chemical species to a surface (-F)/concentration at some height (C) Residence time of pollutants (t)=total mass of pollutant (Q)/emission or removal (g/yr)(P)

Review Questions  National Ambient Air Quality Standards (NAAQS) have been established for Criteria Pollutants  Concentration of air pollutants normal measured in terms of volume or mass in g/m^3  Lead, PM10, and Sulfur dioxide are Criteria Air Pollutants. Mercury is not  Residential Wood Burning is the most common source of PM2.5 in CT  If the velocity of wind moving past a stationary air pollution emission source changes from 1m/sec to 4 m/sec the pollutant concentration will reduce to ¼ of the original level  Fugitive Air Pollutants – emissions of gases or vapors from pressurized equipment due to leaks and other unintended or irregular releases of gases, mostly from industrial activities. Fugitive Air Pollutants contribute to Air Pollution and Climate Change.  Why is concentration of water vapor & CO2 in atmosphere so variable in space & time  atmosphere varies in temperature and pressure is all 4 layers (troposphere, stratosphere, mesosphere, and thermosphere). Troposphere relatively unstable and always changing day to day. Surface boundary layer and roughness layer characterized by strong diurnal variation of atmosphere variables. H2O varies due to constant phase change. CO2 varies due to uptake by plants through photosynthesis....