U2 T6 Flashcards
Proportion of global use of water in %
Agriculture : 70%
Industry: 15%
Domestic uses: 15%
What does abstractive uses involve
Abstractive uses involve removing the water from where it was found
What does domestic uses include
Washing, flushing toilets, food preparation, drinking, watering house and garden plants and recreation.
Tell some differences about the use of water in MEDCs and LEDCs (about restriction and water quality)
In MEDCs the water is purified before use and the amount available does not usually restrict its use. In LEDCs shortage often restrict use to essential activities. The technology may not be available to purify it so water- borne diseases are common.
Name some industries that use large amount of water
Many industries, such as power stations, the chemical industry and some mining and mineral processing industries, require large amount of water.
What does major industrial uses of water include ?
Major industrial uses of water include cooling, heating washing, steam generation, transport as a solvent.
For what are used the cooling towers?
Cooling towers are used to cool condenser water before it is returned to a river.
What is the biggest single agricultural use of water?
Irrigation
Why is water necessary in agricultural uses
- crops and livestock need water to survive , if it is not naturally available the it must be provided —> irrigation
There are 3 main reasons for irrigating crops. What are these?
- To replace water lost in evaporation ô prevent plant dying out
- For growth as it is used in photosynthesis to produce sugar and moist air allows stomata to stay open in full light and absorb maximum CO2
- For the transport of mineral ions, it aids nutrient uptake as nutrients can only be absorbed by roots if they are dissolved in water
On what depends the degree to which water needs to be purified?
It depends upon its intended use. What may be very important for one use may not be so important or another use.
What is the most important large-scale water use where quality is very important ? What criteria are used to assess the water quality?
Public water supply is the most important large-scale water use where quality is very important and supplies may require a lot of treatment. Many physical, chemical and biological criteria are used to assess the water quality for public supply
How must be potable water?
Potable water does not have to be completely pure, but it must not contain unacceptable levels of hazardous materials nor look, taste or smell unpleasant.
How is the concentration (of turbidity) expressed?
As TSS (Total Suspended Solids)
What could you say about turbidity in water?
Suspended solids must be removed because they give water an unpleasant appearance and taste and the settling of suspended solids would block pipes.
What can happen if pH concentration is too high or low?
If water is too acidic it can dissolve copper pipes. If the pHis too high it can make the water taste unpleasant. The ideal range is pH 6.4 to 8.5
What does make the water harder ?
Dissolved calcium ions make the water “harder”
What are the “good” and “bad” thing of hard water
Hard water is good for health as it can help to reduce tooth decay, osteoporosis and heart disease.
But it can react with soap to produce scum and produces solid limescale if the water is heated
What could you say about pesticide concentration? (Toxicity)
All pesticides are toxic, but not necessarily very toxic to humans. Water should be treated to remove virtually all pesticides.
What does heavy metal concentration in water causes?
Heavy metals, such as lead and mercury are neurotoxins and damage the nervous system, but low concentrations cause no detectable damage.
What does dissolved O2 causes in water ?
Low dissolved oxygen levels can make water smell musty or of hydrogen sulfide (=”bad eggs” smell). Some toxic metals are more soluble in water with a low dissolved oxygen content.
Why is chlorine added to water?
Chlorine is added to water to keep it sterile.
What may react with chlorine and reduce its concentration?
Their materials present in the water and the pipe’s wall itself may react with chlorine and reduce its concentration. It may be necessary to add more chlorine or use chloramines, which gradually releases more chlorine,
What could cause sewage contamination of water ?
Sewage contamination of water could cause the spread of many serious diseases caused by pathogens such as cholera and typhoid, but the bacteria that cause these are uncommon, so testing for them would not prove there was no sewage present.
It’s important to test the presence of a specific bacteria to know if sewage contamination of water has occurred . Which bacteria and why?
E. coli is a very common gut bacterium and is always present if sewage contamination has occurred whether or not there are disease- causing pathogens present.
What is the mesure used to calculate the number of bacteria similar to E. coli that are present per litre of water.
It’s the “coliform count”.
For potable water the coliform count should be 0
What are the quality requirement and the problem that would be caused for potable water for public water supply
Quality requirement: water that looks, smells and tastes good and. Obtains no hazardous chemicals
Problem that would be caused: public health risks and acceptability
What are the quality requirement and the problem that would be caused for spray irrigation?
Quality requirement: low turbidity and no toxins (e.g. Heavy metals)
Problem that would be caused: sediments would block pipes could harm crops or consumers
What are the quality requirement and the problem that would be caused for power station condensed water?
Quality requirement : no gross solids
Problem that would be caused: pipes would block
What are the quality requirement and the problem that would be caused by power station boiler steam water?
Quality requirement : absolutely pure water
Problems that would be caused: mineral deposits would build up in boiler pipes and reduce water flow and heat exchange
What are the quality requirement and the problem that would be caused by textile washing?
Quality requirement: “soft” water with low dissolved calcium content
Problem that would be caused: scum would form during washing
Name 4 non-abstractive uses
- Energy
- Transport
- Recreation
- Wildlife conservation
Explain - energy- non abstractive uses
Hydro electric schemes use kinetic energy of moving river water to generate electricity. A dam is usually built to hold back a reservoir so the river flow is altered but the water is not removed
Water abstracted for power generation is altered in one main way before it is returned to a river. How is it altered? It is first collected into ponds, what might these be use for?
Cooling water is usually warmer than it was abstracted. It is often collected into ponds so that it doesn’t pollute the river. Warm water holds less oxygen and so it would be harmful to many invertebrates and fishes. However, the ponds can be used as fisheries where the conditions are suitable for non native fish.
Water from rivers, lake and sea is used to cool condenser steam in fossil fuel and nuclear stations. It is returned to the source at a slightly higher or lower temperatures?
Higher
What could you say about the evolution of transport in non abstractive uses of water?
Water was the first mass transport system for bulk goods on the sea, rivers and later on specially built canals. The importance of rivers and canals declined with the rise of railways and road transport, but ship transport by sea remains very important.
Name a few recreational uses of water
Water bodies are used for many recreational uses such as sailing, canoeing, holiday boating, sport fishing and swimming.
Say a few things about the role of water in wildlife conservation. Why are wetlands important for conservation of wildlife?
Wetlands provide very valuable wildlife habitats. Many of these have been created by human activities, such as reservoirs and flooded gravel pits. Wetland in the UK are particularly important for migratory water birds because the mild winters prevent the water from freezing.
Conflicts about water use may be caused in 2 ways, which ones?
- abstracting and storing water can cause problems for other users of the water in the surrounding area
- other user groups in the area may threaten the water supplies.
What kind of activities reservoirs provide?
Recreational and educational activities
How conflicts about water uses may be solved?
By using time zoning or space zoning. Prohibition and restriction of activities may also help to reduce problems but can cause some.
Name 3 abstractive uses of water
Domestic uses
Industrial uses
Agricultural uses
Name 8 water quality requirement
- Turbidity
- pH
- Calcium content
- Pesticide concentration
- Heavy metal concentration
- Dissolved O2
- Chlorine retention
- E.coli abundance
