Enduring Understanding:

• Human activities have physical, chemical, and biological consequences for the atmosphere.

Learning Objective:

• Identify the sources and effects of air pollutants.

Essential Knowledge:

• Coal combustion releases air pollutants including carbon dioxide, sulfur dioxide, toxic metals, and particulates.

• The combustion of fossil fuels releases nitrogen oxides into the atmosphere. They lead to the production of ozone, formation of photochemical smog, and convert to nitric acid in the atmosphere, causing acid rain. Other pollutants produced by fossil fuel combustion include carbon monoxide, hydrocarbons, and particulate matter.

• Air quality can be affected through the release of sulfur dioxide during the burning of fossil fuels, mainly diesel fuels.

• Through the Clean Air Act, the Environmental Protection Agency (EPA) regulated the use of lead, particularly in fuels, which dramatically decreased the amount of lead in the atmosphere.

• Air pollutants can be primary or secondary pollutants.

Combustion of Fossil Fuels

• The combustion of fossil fuels releases the energy stored during photosynthesis

  • Remember glucose is C6H12O6, the main receptacle of energy

  • All fossil fuels contain carbon and hydrogen

  • The combustion of carbon creates carbon dioxide

  • This carbon has not been in circulation or the atmosphere for millions of years

• Coal contains many other elements absorbed by plants during their life or trapped in the sediments along with organic matter

  • These impurities are also released during combustion

  • Specific elements vary by region

• We will talk about coal and diesel in these notes

Coal

• The plant matter is compressed with heat

  • The first stage of decomposing plant matter is peat, which is sometimes used as an energy source

  • Lignite is the first proper coal, created with the least time, and has many impurities

  • Bituminous has been compacted for longer, with fewer impurities

  • Anthracite is the best and most energy-producing kind of coal, compressed for the longest time, and has the least amount of impurities

Impurities

• Impurities in coal are released during combustion

  • Sulfur in the coal becomes sulfur dioxide

  • Mainly present when coal is formed in marine biomes

• Toxic metals

  • Lead

  • Mercury

  • Nickel

  • Arsenic

• Partially combusted “soot”

  • A form of particulate matter (PM)

  • Can carry many of the metals and heavier elements into the lungs

• Coal is considered one of if not the dirtiest fossil fuel

  • Coal plants can use filters and clean coal processing to decrease sulfur dioxide emissions

  • Crude oil (petroleum) also contains sulfur

• Diesel fuel combustion creates large amounts of sulfur dioxide

  • The EPA began regulating diesel fuel sulfur levels in 1993

Pollutants

• The chemistry of fuels comes from the source plant matter

  • Carbon

  • Hydrogen

  • Nitrogen

  • Oxygen

  • Sulfur

  • Note that these were a lot of our major biogeochemical cycles (CHNOPS)

• These chemicals, when burned, create primary pollutants

  • Primary pollutants interact in the atmosphere to create secondary pollutants

  • Anything that has negative effects on human health or the environment is a pollutant

• Primary pollutants include…

  • CO, carbon monoxide

  • CO2, carbon dioxide

  • SO2, sulfur dioxide

  • NOx, nitrous oxides

  • N2O, nitrous oxide

  • NH3, ammonia

  • Hydrocarbons, including volatile organic compounds (VOCs)

  • Particulate matter

• NOx, once in the atmosphere, can interact with sunlight to create tropospheric ozone (O3)

  • They can also create nitric acid, creating acid raid

Effects

• Pollutants cause harm to human life or the environment

  • Air pollutants are likely to come in contact with the eyes, nose, and throat, causing irritation

  • Inhaled pollutants exacerbate existing lung conditions and can cause permanent damage

  • Air pollutants can damage plant tissue during photosynthesis and respiration