Methods of remediation may concentrate on neutralizing the acid
deposited in an environment. Acids can be neutralized by adding a base.
Since an abundant, low-cost, and nontoxic material is often needed,
limestone, CaCO 3 , is commonly used. For example, limestone might be
added to a lake to increase its pH. Powdered limestone could also be spread
over agricultural lands to increase the pH of the soil. Many nutrients are
more soluble in acidic soils and therefore might be washed away by rain. As
a result, the addition of fertilizer is also required. Deforestation caused by
acid deposition may be addressed by treating the soil and then replanting.
When asked to explain the trends shown in a graph, a good
starting point is to describe what they are. Writing this down first
should also help you compose your explanation.(c) Maximum 1 point.
Look at the graph of CFC production and account for the trends you
observe. (1 point for correctly accounting for one possible reason for the
trends as shown in the graph.) Between 1984 and 1988, both developed and
developing countries used ozone-depleting chemicals at a fairly consistent
rate of approximately 1 million tons per year.
This sample may provide more detail than necessary. The
important point is that the amounts for both developed and
developing countries fell dramatically at the same time and
basically at the same rate. This suggests that the drops come as a
result of the implementation of new laws. Since we are dealing
with a global situation, it is likely to be in the form of an
international agreement.
After 1988, the amount used by both developed and developing countries
decreased sharply and at a fairly constant rate for the next seven years. By
1996, developed countries used 50,000 tons per year and developing
countries used 150,000 tons. Use remained at approximately these levels for
the next two years.
The reduction is likely to be due to countries implementing technologies to
comply with the Montreal Protocol (1989), which set limits for the emission
of chemicals that cause depletion of the ozone layer. The biggest reduction
has come from using alternatives to chlorofluorocarbons (CFCs)—the
principal ozone-depleting agents. Alternatives include HFCs and HCFCs.