Pollution

Question: Which three chemical elements are the most important for plant growth and make up the bulk of chemical fertilizers?

Answer: Modern chemical fertilizers include one or more of the three elements that are most important in plant nutrition: nitrogen, phosphorus, and potassium. Of secondary importance are the elements sulfur, magnesium, and calcium.

Question: Of the following, which is the most effective strategy to stem the impact of toxic waste?

Answer: Perhaps the most effective method of reducing the effects of toxic waste on human health and the environment would be to eliminate its production. Toxins can be reduced through the substitution of nonpolluting alternatives, such as oxygen for chlorine in the bleaching of wood, or through “green chemistry,” a movement that seeks to build chemical products and processes that reduce or eliminate the need for toxic substances.

Question: Which chemical below is a key component of photochemical smog?

Answer: A key component of photochemical smog, ozone is formed by a complex reaction between nitrogen dioxide and hydrocarbons in the presence of sunlight. It is considered to be a pollutant in the troposphere—the lowermost layer of the atmosphere—but not in the upper atmosphere, where it occurs naturally and serves to block harmful ultraviolet rays from the Sun.

Question: Which of the following elements is not a heavy metal?

Answer: Heavy metals damage organs and tissues when consumed, inhaled, or otherwise brought into the body. Lithium is an alkali metal. It is not considered as toxic as the heavy metals, and it sits with other alkali metals, including sodium (Na) and potassium (K), in the periodic table of elements.

Question: Which of the following is not considered a major pollutant in aquatic environments?

Answer: The two common oxides of sulfur are sulfur dioxide, SO₂, and sulfur trioxide, SO₃. The pungent odor of burning sulfur is actually due to the sulfur dioxide that is produced. It occurs in volcanic gases and in the atmosphere near industrial plants that burn coal or oil containing sulfur compounds.

Question: How many metric tons of plastic waste are thought to be discharged into the oceans every year?

Answer: Between 4.8 million and 12.7 million metric tons (between 5.3 million and 14 million short tons) of debris end up in the world’s oceans every year, and much of it is improperly discarded plastic litter.

Question: Which book is best known for raising awareness that the overuse of DDT and other chemicals was leading to declines in bird populations?

Answer: Silent Spring (1962) focused the world’s attention on the improper use of pesticides such as DDT and other persistent chemicals that accumulate in the food chain and disrupt the natural balance of ecosystems on a wide scale.

Question: Gaseous compounds of which two chemical elements are primarily responsible for the breakdown of Earth’s ozone layer?

Answer: Ozone depletion is caused by the release of chemical compounds containing gaseous chlorine or bromine from industry and other human activities. Ozone depletion is a major environmental problem because it increases the amount of ultraviolet radiation that reaches Earth’s surface, which increases the rate of skin cancer, eye cataracts, and genetic and immune system damage.