Ch12 - Water Pollution

Answers to Review Questions and Critical Thinking Questions

Review Questions

1. Water pollution is the degradation of water quality as measured by biological, chemical, or physical criteria.
2. Biochemical oxygen demand is the amount of oxygen used for bacterial decomposition of organic matter in water.
3. The level of fecal coliform is used as an indicator of biological pollution, and is used because the direct measurement of individual pathogens is difficult.
4. Cultural eutrophication of water bodies is caused by rapid increase in algae and other plant life, in turn caused by human-caused increases in nitrogen and phosphorous, and results in death of submerged plants and reduced oxygen levels.
5. Point sources are discrete and localized sources of pollution, while non-point sources are more widespread and diffuse, representing no single, specific source.
6. Acid mine drainage is acidic water that drains from coal or metal mines, caused by oxidization of sulfur-bearing Earth materials and reaction with water.
7. Saltwater intrusion is the movement of saltwater into coastal freshwater aquifers, and is caused by overpumping of groundwater.
8. Primary, secondary, and advanced wastewater treatments refer to the level of treatment performed. Primary treatment involves the removal of particulate matter, while secondary treatment involves the aerobic decomposition of organic matter remaining in the water after primary treatment. Advanced treatment uses chemicals, sand filters, or carbon filters to remove nutrients, heavy metals, or specific chemicals.
9. A septic system may fail because of poor soil drainage, because of overloading with wastes, or because of introduction of contaminants that cannot be broken down.
10.Wastewater renovation and conservation involves the application of wastewater to crops, natural purification of wastewater as it passes through the soil, recharge of the groundwater system, and reuse by pumping from the ground and into new municipal or other use.

Critical Thinking Questions
1. A student addressing this assignment will need to examine land uses in the area and identify the pollution sources. Ideas regarding reduction of pollution from those sources should address environmental impacts of the pollution, the costs and benefits involved with reduction, and the willingness of the public, community leaders, and business owners to address pollution reduction.
2. An answer to this question will depend largely on local conditions and wastewater treatment processes. If there is a geologically and biologically suitable area for wastewater renovation and recovery, a likely use for renovated wastewater, money available for such a project, and some limitation on water resources that would make water recovery beneficial, the concept might be useful. Use of biological systems would also depend on the situation and the contaminants of concern
3. A student addressing this question will need to consider the sources of their perceptions regarding their drinking water. An informed answer requires knowledge of the water supply source, possible natural and human threats to water quality at that source, the quality of the water delivery system, and other factors.