Summary

Air pollution can be thought of as gaseous and particulate contaminants that are present in the earth’s atmosphere. Chemicals discharged into the air that have a direct impact on the environment are called primary pollutants. These primary pollutants sometimes react with other chemicals in the air to produce secondary pollutants. The commonly found air pollutants, known as criteria pollutants, are particle pollution, ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead. These pollutants can harm health and the environment, and cause property damage.

Acid rain is a term referring to a mixture of wet and dry deposition from the atmosphere containing higher than normal amounts of nitric and sulfuric acids. The precursors of acid rain formation result from both natural sources, such as volcanoes and decaying vegetation, and man-made sources, primarily emissions of sulfur dioxide (SO₂) and nitrogen oxides (NOx) resulting from fossil fuel combustion. Acid rain causes acidification of lakes and streams, contributes to the damage of trees and many sensitive forest soils. In addition, acid rain accelerates the decay of building materials and paints, contributes to the corrosion of metals and damages human health.

The ozone depletion process begins when CFCs and other ozone-depleting substances (ODS) are emitted into the atmosphere. Reductions in stratospheric ozone levels lead to higher levels of UVB reaching the Earth’s surface. The sun’s output of UVB does not change; rather, less ozone means less protection, and hence more UVB reaches the Earth. Ozone layer depletion increases the amount of UVB that lead to negative health and environmental effects.

The historical record shows that the climate system varies naturally over a wide range of time scales. In general, climate changes prior to the Industrial Revolution in the 1700s can be explained by natural causes, such as changes in solar energy, volcanic eruptions, and natural changes in greenhouse gas concentrations. Recent climate changes, however, cannot be explained by natural causes alone. Natural causes are very unlikely to explain most observed warming, especially warming since the mid-20th century. Rather, human activities can explain most of that warming.

The primary human activity affecting the amount and rate of climate change is greenhouse gas emissions from the burning of fossil fuels. Greenhouse gas concentrations in the atmosphere will continue to increase unless the billions of tons of our annual emissions decrease substantially. Increased concentrations are expected to increase Earth’s average temperature, influence the patterns and amounts of precipitation, reduce ice and snow cover, as well as permafrost, raise sea level and increase the acidity of the oceans. These changes will impact our food supply, water resources, infrastructure, ecosystems, and even our own health.

Review Questions

1. Ground-level ozone…

A. Protects us from radiation

B. Is a primary pollutant

C. Is a secondary pollutant

D. Reduces visibility but is mostly harmless to human health

E. Is emitted from motor vehicles

2. Secondary pollutants are pollutants…

A. Emitted from non-point sources

B. That are created from the reaction of primary pollutants and other chemicals

C. That are less hazardous than primary pollutants

D. That have reduced ability to stay aloft in the atmosphere

E. Emitted by Class 2 polluters

3. Depletion of the stratospheric ozone layer occurs when molecules of ozone are destroyed by chemicals such as…

A. CFC

B. DDT

C. O₃

D. PCB

E. CH₄

4. What is the function of the stratospheric ozone layer?

A. Provides the biosphere with a source of elemental oxygen

B. Protects against ultraviolet light

C. Shields the Earth from high-energy cosmic rays

D. Protects organisms from infrared radiation

E. Creates UVB radiation for vitamin D synthesis

5. Anthropogenic causes of acid rain are primarily due to which one of the following?

A. Destruction of the ozone layer

B. Emissions of sulfur dioxide and nitrogen oxides from the combustion of fossil fuels

C. Emissions of carbon dioxide from the combustion of fossil fuels

D. Industrial emissions of acids

E. Acids formed in the contrails of airplanes

6. The scientific consensus regarding global climate change is that these changes are…

A. Caused by natural, Earth-based phenomena such as volcanoes

B. Poorly understood and no scientific conclusions can be made at this time

C. Primarily caused by human activities

D. Caused by eccentricity in Earth’s orbit and by changes in solar intensity

E. No greater or different than changes seen in the medieval times

7. Greenhouse gases are known to raise air temperatures by…

A. absorbing infrared radiation

B. creating heat through chemical reactions with atmospheric pollutants

C. absorbing incoming visible light from the sun

D. trapping high energy molecules and atomic particles

E. releasing heat stored in high-altitude catalytic cycles

8. Changes in reflectivity of visible light affect how much energy enters Earth’s system. What term is used by scientists to describe the reflectivity of a surface?

A. Contrastivity

B. Libido

C. Mirror-effect

D. Alluvium

E. Albedo

9. What is the primary cause of ocean acidification?

A. Atmospheric CO2 dissolving in ocean water

B. Increases in acid rain

C. Increased erosion of acid-containing rocks

D. Water draining into the ocean has a higher pH from industrial pollutants

E. All of the above

10. Which one of the following is not a predicted consequence of global climate change?

A. Spread of diseases carried by insects, such as malaria

B. Rise in sea levels

C. Increases in the global average air and ocean temperatures

D. Intensity of precipitation events will likely increase on average.

E. All of the above

See Appendix for answers

Attribution

CK12. (2015). Reducing ozone destruction. Accessed August 31, 2015 at http://www.ck12.org/book/CK-12-Earth-Science-Concepts-For-High-School/section/13.32/. Available under Creative Commons Attribution License 3.0 (CC BY 3.0). Modified from Original.

EPA. (n.d.). Climate change. Accessed August 31, 2015 at http://www.epa.gov/climatechange/. Modified from original.

University of California College Prep. (2012). AP environmental science. Retrieved from http://cnx.org/content/col10548/1.2/. Available under Creative Commons Attribution 4.0 International License. (CC BY 4.0). Modified from original.

Essentials of Environmental Science by Kamala Doršner is licensed under CC BY 4.0. Modified from the original by Matthew R. Fisher and Joni Baumgarten.

“Review Questions” is licensed under CC BY 4.0 by Matthew R. Fisher.