APES Unit 7

Sulfur Dioxide

Created by coal combustion, metal factories, vehicles that burn diesel fuel; causes respiratory irritation, smog, and acid precipitation

Nitrogen Oxides

Created by fossil fuel combustion, vehicle emissions, and diesel generators; creates ozone, photochemical smog, and acid precipitation

Carbon Monoxide

Created from incomplete combustion; creates ozone and is lethal to humans

Particulate Matter

Created by fossil fuel and biomass combustion; causes respiratory irritation and smog

Ozone (Tropospheric)

Created by the photochemical oxidation of Nitrogen Dioxide; causes respiratory irritation, smog, and plant damage

Lead

Accumulates in plants and is created by waste incineration; it’s a neurotoxicant

Carbon dioxide

Greenhouse gas; not an air pollutant

Primary air pollutants

Emitted directly from sources such as vehicles, power plants, factories, or natural sources

Secondary air pollutants

Primary pollutants that have transformed in presence of sunlight, water, and oxygen 

Sulfuric acid and nitric acid

dissociate in the presence of water into sulfate and nitrate ions, and hydrogen ions

Acidic rain water

Has a high Hydrogen concentration; makes things acidic

Limestone

neutralizes pH in acidic water/soil

Mitigating Acid Rain

Limiting Sulfur dioxide and Nitrogen oxides

Which number on the pH scale represents neutral?

7

Which numbers on the pH scale represents acidic solutions?

0-6

Which numbers on the pH scale represents basic solutions?

8-10

Why is normal rainfall slightly acidic?

Carbon dissolves in it and forms carbonic acid

What pH values could rain have?

1-4

What are the two parts to acid deposition?

Wet and dry

How are winds involved in where acid deposition falls?

The wind blows acidic particles and gases onto buildings, cars, homes, and trees.

Compounds that are the primary causes of acid rain

Sulfur dioxide and Nitrogen oxides

How does the process of acid rain begin?

Nitrogen oxides and sulfur dioxides react with oxygen gas and water in the atmosphere to form nitric and sulfuric acid.

How does acid rain form?

In the presence of water, sulfuric acid and nitric acid dissociate into hydrogen ions, sulfate, and nitrate.

Impact of acid rain

Hydrogen protons make soil and water acidic

Urban Heat Island Effect

Urban areas have higher surface & air temperature than surrounding areas due to lower albedo

Thermal inversion

A cooler air mass becomes trapped near earth’s surface

Because warm air rises:

air convection carries air pollutants away from earth’s surface and distributes them higher into the atmosphere

When cold air at the surface is trapped beneath the warm air:

Convection doesn’t carry pollutants up and away

Effects of Thermal Inversion

Air pollutants trapped closer to Earth cause respiratory irritation; decreased tourism revenue and photosynthesis

Ozone should stay in the:

stratosphere

We are in the:

troposphere

Photochemical Smog Precursors

Nitrogen dioxide and volatile organic compounds

How sunlight forms photochemical smog

It dissociates nitrogen dioxide into nitrogen oxide and oxygen; VOCs bind with nitrogen oxide and form photochemical oxidants; free oxygen atoms bind with diatomic oxygen, creating ozone. Ozone combines with photochemical oxidants to form photochemical smog.

How warmth impacts photochemical smog

Speeds ozone formation and evaporation of VOCs

VOCs

Volatile (vaporizing) Organic Compounds

Factors that increase smog formation

More traffic, hotter temperatures (low albedo), more VOCs, and higher demand for electricity

Environmental impacts of smog

Reduces sunlight (limits photosynthesis), and ozone damages plant stomata and irritates animals’ respiratory systems

How smog impacts humans

Respiratory irritant (worsens asthma, bronchitis, and COPD); irritates eyes; increased healthcare costs due to increase in treatment

Lightning strikes - natural source of air pollutants

They convert diatomic nitrogen in the atmosphere into nitrogen oxides.

Plants - natural source of air pollutants

They emit volatile organic compounds.

Forest fires - natural source of air pollutants

They release carbon monoxide, particulate matter, and nitrogen oxides. Combustion of biomass also releases carbon dioxide and water vapor (greenhouse gases).

Volcanoes - natural source of air pollutants

Releases sulfur dioxide, particulate matter, carbon monoxide, and nitrogen oxides

Natural sources of carbon dioxide and particulate matter

Cellular respiration, aerobic decomposition, anaerobic decomposition, (sea salt, pollen, and ash)

PM₁₀

Particulate matter that is less than 10 micrometers big; Particles or droplets like dust, pollen, ash, or mold; Too small to be filtered out by nose hairs and trachea cilia; can irritate respiratory tract & cause inflammation

PM_2.5

Particulate matter that is less than 2.5 micrometers big; Particles from combustion; More likely to travel deep into the lungs due to smaller size

Air pollutants in developing countries

Carbon monoxide, particulate matter, nitrogen oxides, and volatile organic compounds from biofuels

Where air pollutants come from in developed countries:

chemicals in products: adhesives in furniture, cleaning supplies, insulation, lead paint 

Asbestos

a long, silicate particle previously used in insulation

CO is an asphyxiant:

causes suffocation

Sources of VOCs:

adhesives, cleaners, plastics, and fabrics

Radon Gas

Radioactive gas released by decay of uranium naturally found in rocks underground (granite especially); second leading cause of lung cancer

Dust and mold

Natural indoor air pollutants that can worsen asthma, bronchitis, COPD, emphysema

Reducing emissions =

reducing air pollutants

Clean Air Act

Allows EPA to set acceptable levels for criteria air pollutants

Pollution Credits

Earned by companies that reduce emissions well below EPA-set levels

CAFE Vehicle Standards

standards require the entire US “fleet” of vehicles to meet certain average fuel 

Vapor Recovery Nozzle

Capture hydrocarbon VOCs released from gasoline fumes during refueling

Catalytic Converter

converts nitrogen oxides, carbon monoxide, and other hydrocarbons into carbon dioxide, diatomic nitrogen, oxygen gas, and water

Crushed Limestone

Used to reduce sulfur dioxide from coal power plants

Fluidized Bed Combustion

Fluidizing jets of air pumped into combustion “bed”

Dry Scrubbers (nitrogen oxides, sulfur oxides, and volatile organic compounds)

Large pipe filled with chemicals that absorb or neutralize oxides from exhaust streams

Wet scrubbers (nitrogen oxides, sulfur oxides, volatile organic compounds, and particulate matter)

May involve chemical agents that absorb or neutralize nitrogen oxides, sulfur oxides, VOCs, but also include mist nozzles that trap PM in water droplets as well

Electrostatic Precipitator

Power plant and factory emissions passed through device with a charged electrode, giving particles a positive or negative charge

Baghouse Filter for particulate matter

Large fabric bag filters that trap PM as air from combustion and industrial process passes through 

Urban Noise Pollution

Any noise at great enough volume to cause physiological stress or hearing loss

Noise pollution wildlife effects (land)

can disrupt animal communication, migration, and damage hearing

Noise pollution wildlife effects (aquatic)

comes from the noise of ship engines, military sonar, and seismic air blasts from oil & gas surveying ships; causes hearing loss, disrupted communication, mating calls, predator and prey navigation