Question 1

Which of the following is responsible for the growing hypoxic, or dead zone, problem in the Gulf of Mexico?

Accepted Answer

Animal feed lots and agricultural fertilizers used throughout the Midwest contribute to nutrient runoff into rivers that feed into the Gulf of Mexico, leading to excessive algal growth and subsequent oxygen depletion in the water, creating the hypoxic or dead zone problem.

Question 2

What best explains why municipal governments are now focusing on waste reduction and recycling programs?

Accepted Answer

As the number of landfills has declined, it has driven up the cost of waste disposal. This has led municipal governments to focus on waste reduction and recycling programs as a cost-saving measure.

Question 3

Acid rain has a negative impact on ecosystems and accelerates the chemical weathering of concrete structures and marble building materials. Which of the following compounds released by human activity are responsible for acid rain?

Accepted Answer

Sulfur dioxide and nitrogen oxide are released by human activities such as burning fossil fuels, and are responsible for acid rain due to their ability to form sulfuric acid and nitric acid when they react with water in the atmosphere. Carbon monoxide, carbon dioxide, ozone and nitrogen oxide are also released by human activity, but do not contribute significantly to acid rain formation.

Question 4

Which of the following best describes why open dumps in the U.S. were banned in 1983?

Accepted Answer

Open dumps were attracting wild animals such as rats and seagulls, which could carry diseases and pose safety risks. Additionally, fires in open dumps would create air pollution, which was a health hazard for nearby communities.

Question 5

Liquid hazardous wastes are commonly injected into deep, saline aquifers for disposal.

Accepted Answer

This is a common practice known as deep well injection. However, it is important to note that this disposal method comes with potential risks and safety concerns.

Question 6

Municipal sewage treatment plants are very effective at breaking down human waste prior to discharging the wastewater into rivers. Why then, do so many U.S. plants continue to cause water quality problems in rivers?

Accepted Answer

Municipal sewage treatment plants, while effective at breaking down human waste, often struggle with combined sewage and stormwater systems that can release raw sewage during heavy rain events. Additionally, these plants are not very effective at removing heavy metals, hazardous chemicals, or pharmaceuticals from the water, all of which contribute to ongoing water quality issues in rivers.

Question 7

What does the term half-life describe?

Accepted Answer

The term half-life refers to the amount of time it takes for half of the radioactive atoms in a substance to decay into stable isotopes. This is a fundamental concept in nuclear physics and is used to describe the rate of decay of radioactive materials.

Question 8

Which of the following statements is NOT true regarding groundwater contamination?

Accepted Answer

Confined aquifers are surrounded by impermeable rock or sediment layers, which prevent contamination from surface sources. In contrast, unconfined aquifers are only partially covered by permeable sediment layers, making them more susceptible to contamination from surface sources.

Question 9

What explains why leachate is a problem in sanitary landfills?

Accepted Answer

Leachate is formed when rainwater or other liquids come into contact with waste in a landfill. It can pick up harmful chemicals from the waste and cause groundwater contamination, which can lead to environmental and health problems.

Question 10

Radon gas can accumulate in people's homes and pose a serious lung cancer risk. What is the source of the radon gas?

Accepted Answer

Radon gas is a radioactive gas that is a product of the natural radioactive decay of uranium minerals found in rocks and sediment. As these minerals decay, they release radon gas, which can seep into homes and other buildings.

Question 11

The terms polluted and contaminated have different meanings when it comes to substances put in the environment by human activity. With respect to these substances, what does polluted mean?

Accepted Answer

Polluted means that the concentration of the substance in the environment is high enough to cause harm to living organisms.

Question 12

Which of the following pollution sources would be considered to be a non-point source?

Accepted Answer

All of the listed pollution sources are non-point sources, meaning that the pollution does not originate from a single point source (such as a factory discharge pipe), but rather comes from diffuse sources such as agricultural runoff, urban stormwater runoff, and atmospheric deposition from sources such as cars and livestock.

Question 13

Which of the following is NOT an example of low-level radioactive waste?

Accepted Answer

Spent nuclear fuel is considered high-level radioactive waste, not low-level. The other choices listed are examples of low-level radioactive waste.

Question 14

Scrubbers are being used in the U.S. to reduce sulfur dioxide emissions associated with the burning of fossil fuels.

Accepted Answer

Scrubbers are a common technology used in the U.S. to reduce sulfur dioxide emissions from power plants and industrial facilities that burn fossil fuels.

Question 15

Which of the following makes up the largest percentage of U.S. municipal waste?

Accepted Answer

According to the Environmental Protection Agency, paper makes up the largest percentage of municipal waste generated in the United States. Approximately 25% of municipal solid waste consists of paper and paperboard products.

Question 16

Certain forms of the element mercury move up through the food chain and into humans. What is primary problem that mercury is known to cause in people?

Accepted Answer

Mercury exposure, especially in the form of methylmercury found in contaminated fish, can cause birth defects and loss of cognitive ability in children.

Question 17

Eutrophication and oxygen depletion in natural wasters can be very damaging to stream ecosystems. Which of the following is the primary cause of oxygen depletion in streams?

Accepted Answer

Excessive nutrients, particularly nitrogen and phosphorus, can cause algal blooms in streams. When these algae die and decompose, bacteria consume oxygen during the process, leading to depleted oxygen levels in the water. This can harm fish and other aquatic organisms that require oxygen to survive.

Question 18

Which of the following explains why many household septic systems end up contaminating the shallow groundwater system?

Accepted Answer

All of the answers listed here can contribute to septic system contamination of shallow groundwater. The water table being too high can prevent proper drainage and cause wastewater to back up into the system. The drain field becoming plugged with solids can reduce the system's ability to filter and treat wastewater before it enters the surrounding soil. Pouring household chemicals down the drain can damage the septic system and contaminate the groundwater. Finally, if the material under the drain field is not permeable enough, wastewater may not be adequately filtered and treated before it reaches the surrounding groundwater.

Question 19

In addition to secured landfills, hazardous waste can be disposed of through high temperature incineration. What best explains why incineration is a controversial technique?

Accepted Answer

The main controversy surrounding incineration as a hazardous waste disposal technique is that it is not 100% effective in destroying all hazardous compounds in the waste, and some of these compounds can be released into the air. This can potentially harm human health and the environment.

Question 20

When radioactive isotopes decay they emit radiation that is harmful to humans. Which of the following forms of radiation have the highest energy and ability to penetrate solid materials?

Accepted Answer

Gamma rays have the highest energy and smallest wavelength, which allows them to penetrate solid materials easily. Beta particles and alpha particles are less penetrating and have less energy, while microwaves and ultraviolet waves have even lower energies and longer wavelengths.

Quiz 15: Pollution and Waste Disposal