Video Transcript
Which of the following activities
is considered a source of chemical pollution? (A) Plastic bags and bottles being
thrown into the ocean. (B) Factories discharging waste
into rivers. (C) The meltdown of a nuclear
reactor. (D) Animals dying near streams and
rivers. Or (E) nitrogen dioxide being
generated by combustion engines.
Pollution is caused by
pollutants. There are different types of
environmental pollutants. There are natural pollutants and
artificial pollutants. Natural pollutants are pollutants
that contaminate the environment and are generated by natural disasters or
phenomena. Artificial pollutants, on the other
hand, are pollutants that contaminate the environment and are generated by human
activity.
Natural pollutants include animal
carcasses, which pollute streams and rivers, and volcanic eruptions, which release
ash and dust and cause fires producing the greenhouse gas carbon dioxide. We can therefore eliminate answer
choice (D) as it is a natural pollutant, not a chemical pollutant.
A chemical pollutant is a type of
artificial water pollutant. The other types of artificial water
pollution are biological, radiant, and thermal. An example of biological water
pollution is human and animal waste being disposed of in waterways. Animal waste may appear naturally
in water sources, but we are concerned with large quantities from herds of
livestock. Human and animal waste contains
pathogens that can spread disease, having entered the water supply.
Radiant pollution occurs when
nuclear reactors leak or radioactive substances are dumped into seas or oceans. Answer choice (C), the meltdown of
a nuclear reactor, would come under this category. Thus, it is radiant water
pollution, not chemical water pollution. Thus, answer choice (C) is not the
answer to this question.
Thermal pollution is the artificial
rise or fall in the temperature of a water source. For example, water may be used as a
coolant in nuclear power stations. As the water is cycled through the
plants, the temperature increases. When this water is released, it is
at an artificially high temperature.
Chemical pollution generally comes
from factories discharging waste into waterways. This closely matches answer choice
(B), factories discharging waste into rivers. So it seems as though (B) is the
correct answer to this question. But let’s quickly check the answer
choices that we haven’t eliminated yet.
Answer choice (E) is nitrogen
dioxide being generated by combustion engines. This is classed as air
pollution. Thus, answer choice (E) is
incorrect. Answer choice (A) is plastic bags
and bottles being thrown into the ocean. This doesn’t fit well into the four
main categories of artificial water pollutants. Answer choice (B) is clearly a
closer match to the description of chemical water pollution. Thus, answer choice (A) is
incorrect.
Therefore, the activity which is
considered a source of chemical pollution is (B), factories discharging waste into
rivers.
