L21: water resources ii

What can affect water quality?

• climate change

• agriculture

• forestry

• population growth

• Geogenic contaminants

• Engineering works

• Industrialisation

How does climate change affect water?

warmer temperature heats water

surface water warmer holds less oxygen

How does agriculture affect water?

increased nutrients (nitrogen and phosphate) in the surface and groundwater duw to runoff fertilisers

How does forestry affect water?

acidification

How does geogenic affect water?

Weathering of rocks containing arsenic lead and uranium

these naturally occurring contaminants fin their way into drinking water

How does engineering works affect water?

river channelisation

dams

sand removal

How does industrialisation affect water?

discharges of polluted or warm water

What are the parameters of water quality?

• biological quality → rivers and lakes

• Nitrate → rivers and groundwater

• Oxygen demand

• total phosphorus → lakes

• nitrogen → estuaries and coastal

What are the biological/ ecological status of water and their impacts?

High → none or minor

Good → slight

moderate → moderate

poor → major

bad → severe

Is ecological status worse in summer or winter?

worse in summer because river water temperature higher and oxygen demand higher from more aquatic organisms alive

transitional waters?

estuaries, lagoons, other near shore water in freshwater-saline water mixing zone

What % of rivers are high?

8%

What % of lakes are high?

31%

What % of transitional waters are high?

18%

What % of coastal waters are high?

45

What are the main causes of river pollution?

low and moderate pollution caused mainly by agriculture ( 58%, 47%)

serious pollution is municipal (80%) and industrial (20%)

Where has a higher nitrate concentration and why?

southeast because fertiliser use is higher in this area

Where has a higher phosphate concentration and why?

the northwest because there is less thick soils which trap phosphate particles

How does faecal matter enter water ways?

• domestic wastewater treatment systems

• farmyard run-off

• grazing animals

• land spreading of manure or slurry

What are vulnerable areas of Microbiological contamination  

• karst aquifers

• fractured aquifers

• areas with exposed outcrop or shallow soil

How much of drinking water supply is sourced from surface water?

81.5%

vulnerable pollution

How much of drinking water supply is sourced from groundwater?

11%

How much of drinking water supply is sourced from local springs?

7%

Quality parameters of drinking water supply?

• bacteria

• chemicals

• metals

• turbidity

• total dissolved solids

• pH

• hardness

In 2020 how much group water schemes are contaminated?

20 out of 380

Why is chlorine added to water supply?

disinfection

What are the risks of chlorination?

if supply has naturally occurring organic matter which can create trihalomethanes

What is an example of a pathogen that is resistant?

cryptosporidium

How much of water supply in fluorinated?

75%

How many countries benefit from flouridation?

210million in 39 countries

Since when has fluoridation been mandatory in ireland?

1964

What is the max in ireland and EU?

ireland → 1.0ppm

EU → 1.5ppm

What is an excess of fluoride in water supply?

fluorosis

EPA Remedial Action List 

1. Water free of bacteria

2. Water free of protozoan organism

3. water free of chemical substances

4. water treatment plants are operated correctly

Nitrate in groundwater?

1/5 monitoring sites have nitrate conc. greater than 25mg/l

if higher than 10mg/l has anthropogenic organic or inorganic inputs