18. The ozone layer can be protected by
I.
using substitutes for ozone-depleting chemicals.
II.
reducing cattle production.
III.
recycling old refrigerators.
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
6. Which of the following pairs are both examples of recycling?
A.
Manufacturing new aluminum cans from old ones; biodegradation of plastic
bags
B.
Processing newspapers into toilet paper; breaking down of raw sewage in the
oceans
C.
Converting used car tires to rubberized road surfaces; producing compost
from organic waste
D.
Producing methane from landfill sites; incinerating plastics
23. If a lake is sprayed with a non-biodegradable insecticide to kill mosquitoes,
after a few years the highest concentrations of insecticide are most likely to
be found in the
A.
upper layers of the lake.
B.
tissues of the mosquitoes and other insects.
C.
tissues of the freshwater plants.
D.
tissues of predatory fish and fish-eating birds.
________ levels of BOD indicate _________ levels of dissolved oxygen.
Eutrophication is a result of high levels of ____________ and ___________.
Ozone depleting substances include ___________________ and
______________________.
What does “divert sewage effluent” mean?
List the main clean up methods of pollutants.
ANSWER KEY:
18. B
6. A
23. D
High; low
Nitrogen; phosphate
Halogenated gases (CFCs); nitrogen oxides (fossil fuels)
What does “ divert sewage effluent” mean?
To divert sewage from body of water
List the main clean up methods of pollutants.
1. Precipitation (e.g. treatment with a solution of aluminum or ferrous salt
to precipitate phosphates)
2. Removal of nutrient-enriched sediments, for example by mud pumping
3. Removal of biomass (e.g. harvesting of common reed) and using it for
thatching or fuel