- Water Pollution
Answers to Review Questions and Critical Thinking 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
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,
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
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
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.