Homework Clinic
Science Clinic => Environmental Studies => Topic started by: jasdeep_brar on Jul 15, 2018
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Describe the negative effects of pollutants on crops, forests, and other materials. Which pollutants are mainly responsible for these effects?
What will be an ideal response?
Question 2
What is meant by population momentum and what is its cause?
What will be an ideal response?
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Answer to Question 1
Negative effects of air pollution on crops, forests, and other materials include the following: (t)he dying off of vegetation in large urban areas and the damage to crops, orchards, and forests downwind of urban centers are caused mainly by exposure to ozone and other photochemical oxidants. Estimates of crop damage by ozone range from 2 billion to 6 billion per year, with an estimated 1 billion in California alone. The negative impact of air pollution on wild plants and forest trees may be even greater than on agricultural crops. Significant damage to valuable ponderosa and Jeffrey pines occurred along the entire western foothills of the Sierra Nevada in California. Forests under stress from pollution are more susceptible to damage by insects and other pathogens than unstressed forests. Walls, windows, and other exposed surfaces turn gray and dingy as particulates settle on them. Paints and fabrics deteriorate more rapidly, and the sidewalls of tires and other rubber products become hard and checkered with cracks because of oxidation by ozone. Metal corrosion is increased dramatically by sulfur dioxide and acids derived from sulfur and nitrogen oxides, as are weathering and deterioration of stonework.
The pollutants mainly responsible for these effects are ozone and sulfuric and nitric acid.
Answer to Question 2
Population momentum is when a country's population continues to grow even after the total fertility rate is reduced to the replacement level. Population momentum occurs because such a small portion of the population is in the upper age groups (where most death occurs) and many children are entering their reproductive years. Even if these . . . (individuals) have only two children per woman, the number of births will far exceed the number of deaths.