Environmental Science for AP - FR Chapter 15 Air Pollution and Stratospheric Ozone Depletion

Air pollution

Introduction of chemicals, particulate matter, or microorganisms into the atmosphere at concentrations high enough to harm plants, animals, materials, or alter ecosystems.

Natural sources of air pollution

volcanoes, lightning, forest fires, plants

Anthropogenic sources of air pollution

on-road vehicles, power plants, industrial processes, waste disposal

6 criteria air pollutants

Nitrogen oxides, Ozone, Sulfur dioxide, Carbon monoxide, Lead, PM

Clean Air Act of 1970

The law aimed at combating air pollution, by charging the EPA with protecting and improving the quality of the nation's air. (Six major criteria air pollutants)

SO2 - causes

Sulfur dioxide - Combustion of fuels that contain sulfur, including coal, oil, and gasoline.

SO2 - consequences

Sulfur dioxide - Respiratory irritant, can exacerbate asthma and other respiratory ailments. Can harm stomates and other plant tissue. Converts to sulfuric acid in atmosphere, which is harmful to aquatic life and some vegetation.

SO2 - precursor to

Sulfur dioxide - Converts to sulfuric acid in the atmosphere - acid deposition

NOx - causes

Nitrogen oxides (NO, NO2)- All combustion in the atmosphere including fossil fuel combustion, wood, and other biomass burning.

NOx - consequences

Nitrogen oxides (NO, NO2) - Respiratory irritant, increases susceptibility to respiratory infection. Ozone precursor, leads to formation of photochemical smog. Converts to nitric acid in atmosphere, which is harmful to aquatic life and some vegetation. Contributes to over fertilizing terrestrial and aquatic systems.

NOx - precursor to

Nitrogen oxides (NO, NO2) - Ozone, photochemical smog
Converts to nitric acid in atmosphere, which is harmful to aquatic life and some vegetation. Contributes to over fertilizing terrestrial and aquatic systems.

CO - causes

Carbon monoxide - Incomplete combustion of any kind, malfunctioning exhaust systems, and poorly ventilated cooking fires.

CO - consequences

Carbon monoxide - Bonds to hemoglobin thereby interfering with oxygen transport in the bloodstream. Causes headaches in humans at low concentrations, can cause death with prolonged exposure at high concentrations.

PM10 or PM2.5 - causes

Particulate matter - Solid or liquid particles suspended in air. Combustion of coal, oil, biofuels, and diesel. Agriculture, road construction, and other activities that mobilize soil, soot, and dust.

Which PM is more dangerous? PM2.5 or PM 10?

PM 2.5 is smaller and can go deeper into the respiratory tract

PM10 or PM2.5 - consequences

Particulate matter -Can exacerbate respiratory and cardiovascular disease and reduce lung function. May lead to premature death. Reduces visibility and contributes to haze and smog.

Lead (Pb) - causes

Gas additive, oil and gas, coal, old paint.

Lead (Pb) - consequences

Impairs central nervous system. At low concentrations, can have measurable effects on learning and ability to concentrate.

Ozone (O3) - causes

Secondary pollutant formed by combination of sunlight, water, oxygen, VOCs, and NOx.

Ozone (O3) - consequences

Reduces lung function and exacerbates respiratory symptoms. Degrading agent to plant surfaces. Damages materials like rubber and plastic.

VOC - causes

Volatile Organic Compounds.
Hydrocarbons that become vapors at typical atmospheric temperatures. Evaporation of fuels, solvents, paints, improper combustion of fuels like gas. Plants are a large source.

VOC - consequences

Volatile Organic Compounds.
Precursor to ozone formation. Same are carcinogenic, some harm respiratory system.

Mercury (Hg) - causes

Combustion of coal, oil, gold mining. Bioaccumulates in the food chain

Mercury (Hg) - consequences

Impairs central nervous system. Bioaccumulates in the food chain (harmful to embryonic development)

CO2 - causes

Combustion of fossil fuels and clearing of land.

CO2 - consequences

Affects climate and alters ecosystems by increasing green house gas concentrations.

Primary pollutants

Pollutants directly from sources. CO, CO2, SO2, NOx, VOCs.

Secondary Pollutants

Primary pollutants that have undergone transformation in the presence of sunlight, water, oxygen, or other compounds. Ozone, sulfate, nitrate, sulfuric acid, nitric acid

photochemical smog

A brownish haze that is a mixture of ozone and other chemicals, formed when pollutants react with each other in the presence of sunlight

Source: NO

Consequence: lung irritation, emphysema, eye irritant

industrial smog

mixture of sulfur dioxide, droplets of sulfuric acid, and a variety of suspended solid particles emitted mostly by burning coal

thermal inversion

A situation in which a relatively warm layer of air at mid-altitude covers a layer of cold, dense air below. The cold air contains polluting gases and PMs remain trapped in high concentrations closest to the ground. Happens in cities located in valleys (Los Angeles)

Biological indicator

Living organisms or test systems that can be used to measure the health of the environment or the effectiveness of a sterilization process

Biological indicator for air pollution

lichen - algae and fungus
Lichens are biological indicators of air quality because they are sensitive to pollutants, concentrate pollutants, and are present in many environments - otherwise they can withstand drought, mineral depletion, wind, etc.

Acid deposition

any type of precipitation that has a pH lower than 5.6

causes of acid deposition

nitrogen oxides and sulfur dioxide are released into the atmosphere primarily by burning fossil fuels; they react with water and other chemicals in the presence of sunlight to produce nitric and sulfuric acids

Regional acid deposition

- mobility allows the precursors to acid deposition emitted in one region or one country, to affect another region or country

effects of acid deposition

Lowers the pH of lake water
Decreases species diversity in aquatic ecosystems
Mobilizes metals found in soils and releases these into surface waters
Damages statues, monuments, and buildings and other structures

solutions to acid deposition

prevention > clean-up

prevention: reduce use of coal, increase use of renewable energy resources, remove particulates from gasses in smokestack

clean-up: limestone (CaCO3)

why has acid deposition improved in the U.S.?

lower sulfur dioxide and nitrogen oxide emissions as a result of the Clean Air Act

Clean Air Act has led to the most dramatic reduction in which pollutant?

Lead - decreased 98% since 1970 due to the switch to unleaded gasoline

Clean Air Act Amendments of 1990

comprehensive regulations enacted by the U.S. Congress that address acid rain, toxic emissions, ozone depletion, and automobile exhaust - cap and trade of SO2

Ways to address air pollution

Avoid emissions in the first place.

Use cleaner, alternative fuels – occur naturally with different sulfur concentrations or can be refined and processed with concentrations reduced (more expensive)

Increase efficiency and conservation (less fuel used = less air pollution produced)

Control pollutants after combustion - regulations

wet scrubber

fine mists of water vapor trap particulates and convert them to a sludge that is collected and disposed of usually in a landfill

Baghouse Filter

Dirty air enters, combustion exhaust stream goes through and dust particles are trapped in a series of filter bags, cleaner and filtered air moves out of unit, shaker mechanism activated periodically to dislodge trapped particles which can then be collected from below unit.

catalytic converter

a platinum, coated device that oxidizes most of the VOCs and some of the CO that would otherwise be emitted in exhaust, converting them to CO2.

Electrostatic Precipitator

Dirty air enters, particles in combustion exhaust stream pass by negatively charged plates which give them that charge, then these particles are attracted to positively charged collection plates, cleaner air moves out, plates are occasionally discharged so particles fall out and be removed.

fluidized bed combustion

a clean-coal technology in which crushed coal is mixed with limestone to neutralize the acidic sulfur compounds produced during combustion

vapor recovery nozzle

an air pollution control device on a gasoline pump that prevents fumes from escaping into the atmosphere when fueling a motor vehicle

limit automobile usage

HOV lanes, bike lanes, charge user fees during heavy commute times

Sick Building Syndrome

Buildup of toxic compounds and pollutants indoors because of better insulation to save energy. Proved when symptoms subside when leave building.

reasons for sick building syndrome

1.) Inadequate or faulty ventilation
2.) Chemical contamination from indoor sources
3.) Chemical contamination from outdoor sources
4.) Biological contamination from
outside or inside

Indoor air pollution in developing countries

- Indoor burning of wood, charcoal, dung, crop residues, coal
- CO and PM are big risk - Acute respiratory infections, pneumonia, bronchitis, cancer
- Greatest risk to low-income populations

Indoor air pollution in developed countries

Materials made from plastics and other petroleum based materials – give off chemical vapors

Pollutants can accumulate

Indoor Pollutants

Furniture, Carpets, foam insulation, pressed wood: VOCs
Tobacco Smoke: Toxic and carcinogenic compounds
Old Paint: Lead
Floor and ceiling Tiles, pipe insulation: Asbestos
Rocks and soil beneath house: Radon
Household Products, pesticides, paints, cleaning fluids: VOCs and other compounds.
Fireplaces, wood stoves: Particulate Matter
Leaky or unvented gas or wood stoves and furnaces, running cars left running: CO.

Asbestos

A long, thin, fibrous silicate mineral with insulating properties, which can cause cancer when inhaled. Indoor air pollutant

Radon

Naturally occurring colorless and odorless radioactive gas found in some types of soil and rock that seeps into homes through cracks in the foundation, groundwater, or rocks. - dissolves in groundwater - 2nd leading cause of cancer in US

Indoor air pollutant VOCs

used in furniture, paint, and building materials. Formaldehyde from building materials, furniture, upholstery

CFC and Stratospheric Ozone Equations

O3 + Cl turns into ClO + O2. Then ClO +O turns into Cl +O2.

CFCs

Used to be used in refrigeration and propellants but destroys stratospheric ozone. Phased out

Stratospheric ozone depletion - cause

Use of CFCs

CFCs remain in the stratosphere for a century

UV radiation breaks CFCs into chlorine and carbon atoms

The chlorine atom splits ozone

Stratospheric ozone depletion - consequences

Increased UV radiation reaches earth’s surface harmful to human health, crops, forests, animals, and material such as plastic and paints

Specific consequences of an ozone hole on human health

Sunburn

Skin cancer

Eye damage - cataracts

Efficiency of immune system

Synergistic with other air pollutants

Specific consequences of an ozone hole on the environment

Reduction of primary productivity in oceans

Disruption of food chain (large animals first)

Damage to fish, amphibians, mammals

Widespread effects on major food crops

Decreased plant productivity

Montreal Protocol

meeting in 1987 where a group of nations met in Canada and agreed to take steps to fight against Ozone Depletion-CFC's banned

Stratospheric ozone hole - above Antarctic

High-altitude polar stratospheric clouds (ice clouds) form during the dark, frigid winter (-78°C)

A polar vortex (swirling winds) traps chlorine

When sun reappears in September (spring), UV radiation dissipates the clouds and releases the chlorine