Water Quality - Causes of water deterioration

Question 1

What are the 4 major categories of human pollutants, examples and sources?

Answer 1

Infectious agents - bacteria, viruses, protozoa - human excreta
Organic chemicals - pesticides, lastics, detergents, oil - industry and agriulture
Inorganic chemicals - acids, caustics, salts, metals - industrial effluent, household cleaners, surface run off
Radioactive materials - uranium, caesium - mining, power plants, weapon production

Question 2

What are the major categories of water pollutants in by ecosystem dirsuption?

Answer 2

Sediment - soil, silt - land erosion
Plant nutrients - nitrates, phosphates - fertilisers, sewage, manure
Oxygen demanding wastes - manure, plant residues - sewage, agricultural run off, paper mills, food processing
Thermal - heat - power plamts, industrial cooling

Question 3

How does agriculture affect water quality?

Answer 3

Fertilisers - source of nitrate pollution
contamination from fertilisers depends on - amount of fertiliser applied
- characteristics of soil
- crops
- climate
- the recieving water bodies

Question 4

What is the full name of the EC Nitrate directive in which designates zones as nitrate vulnerable?

Answer 4

91/676/EEC

Question 5

How does urban storm water cause problems to rivers?

Answer 5

Due to heavy rain sewage may use the overflow system causing potential pollution. This is called a combined sewer overflow (CSO). It is not a rare problem and is estimated to occur once a week in the River Thames.

Question 6

How do water bodies become acidic?

Answer 6

Rain is acidified by anthropogenic release of sulphates and nitrogen oxides giving it a pH of

Question 7

How does acidified waters affect water quality?

Answer 7

Species richness declines as pH falls
Removes natural buffering (Ca and Mg)
More Aluminium leached from soil which becomes toxic at low pH

Question 8

How is mining and quarrying a problem to water quality?

Answer 8

Sub-surface mining often progresses below the water table and so water must be constantly pumped out of the mine to prevent flooding
When the mine is abandoned they cease to remove the water and the mine floods
Mines are often major culprits of acid drainage

Question 9

What did the Water Act of 1989 give river authorities?

Answer 9

Statutory duty relating to quality of controlled waters

• surface water, rivers, reservoirs
• underground water
• estuaries
• sea to a distance of 3 miles from the shore

Question 10

What are the 2 dimensions of pollution?

Answer 10

Space - point sources (fish farms, effluents) and diffuse sources (agricultural run off, acid rain)
Time - continuous (sewage discharge) and intermittent (urban storm water, pollution episodes)