Thermal Pollution

Question 1

What is the main source of hot water that leads to thermal pollution?

Answer 1

Hot water from steam turbine power stations that uses cold water from a lake,river or the sea. The coolant water is then returned to the source but at a higher temperature

Question 2

What ecological effects can the warmer water have and why?

Answer 2

Effect the dissolved oxygen concentrations because they are controlled by the temperature

Question 3

Why can most aquatic organisms not live at high temperatures?

Answer 3

Proteins are denatured

Question 4

What does it mean if an organism is thermophilic?

Answer 4

It is ‘heat-loving’
It can survive above 40oC

Question 5

How can temperatures in water that are hotter than usual, indirectly harm aerobic organisms?

Answer 5

As the temperature increases the solubility of oxygen declines

Question 6

Where are low oxygen levels rarely a problem?

Answer 6

In the atmosphere

Question 7

How much oxygen is in the air?

Answer 7

In every litre of air there is about 210cm3 of oxygen

Question 8

When are anaerobic conditions usually found, considering the fact there is so much oxygen in the air for aerobic conditions?

Answer 8

When a volume of air has become enclosed and deoxygenating processes have occurred
E.g. decomposition of organic matter

Question 9

When is deoxygenating more likely to be problem?

Answer 9

In water because at 20oC a litre of water holds a maximum of 6cm3 of dissolved oxygen- less than 3% of amount found in air

Question 10

What can higher temperatures mean for aquatic organisms who are near the end of their range of tolerance already, in terms of dissolved oxygen?

Answer 10

An increase in temperature can cause the oxygen to come out the solution which leads to the death of sensitive organisms

Question 11

What are the possible physiological changes that can happen because of higher water temperatures?

Answer 11

Increased metabolic rates
Increased raise of egg development
Introduction of non-indigenous species
Greater pollutant toxicity
Reduced resistance to disease

Question 12

How can increased metabolic rates as a result of thermal pollution be a problem?

Answer 12

More energy is used and there is less surplus energy for growth

Question 13

How can increased rate of development as a result of thermal pollution be a problem?

Answer 13

Eggs hatch earlier

Question 14

How can non-indigenous species as a result of thermal pollution be a problem?

Answer 14

They can be introduced from warmer climates and out-compete indigenous species

Question 15

How can increased pollutant toxicity as a result of thermal pollution be a problem?

Answer 15

Toxins are metabolised quicker

Question 16

What is used to make sure effluent water doesnt cause deoxygenating?

Answer 16

Cooling towers

Question 17

Is the warm water from power stations a bigger issue in smaller bodies of water or larger, why?

Answer 17

In smaller bodies
Warm water can disperse and be diluted in larger volume because there is more cool Water
Smaller- can mean a harmful temperature rise

Question 18

What is the purpose of cooling towers?

Answer 18

To reduce waste water temperature by dispersing the heat into the atmosphere and returning cooler water to the source

Question 19

How does a cooling tower work?

Answer 19

By spraying hot water in the lower part of a tall hollow rowe
Air in the tower absorbs heat from water and rises up escaping into the atmosphere
This causes an up draught which draws more air through the shower spray

Question 20

How can cooling towers solve the issue with the concentration of dissolved oxygen?

Answer 20

The shower mixes the water with air so it is more saturated with dissolved oxygen

Question 21

How much cooling water is required for a 2000MW power station?

Answer 21

200 million litres
The water is usually returned 5-8oC higher