Posts Tagged ‘freshwater’

  • List the significant abiotic (physical) factors of an ecosystem.

Ecosystems can be divided into 3 types:

  • Marine: the sea, salt marshes mangroves are all characterized by the salt content.
  • Freshwater: rivers, lakes and wetlands.
  • Terrestrial: land-based.

Each ecosystem has its on abiotic factors:

Marine:

  • salinity
  • pH
  • temperature
  • dissolved oxygen
  • wave action

Freshwater:

  • turbidity
  • flow velocity
  • pH
  • temperature
  • dissolved oxygen

Terrestrial:

  • temperature
  • light intensity
  • particle size
  • slope/aspect
  • soil moisture
  • drainage
  • mineral content
  • Describe  and evaluate methods  for measuring at least three abiotic (physical) factors within an ecosystem.

Abiotic factors that can be measured within an ecosystem include the following:

Marine:

  • salinity: this can be measured  using electrical conductivity ( with a datalogger) or by the density of the water (water with high salt content is more denser than low-salt water).
  • pH: this can be measured using a pH meter, or datalogging pH probe. Indicator solution may also be used.
  • temperature: ordinary thermometers are too fragile to use for fieldwork, and are hard to read. An electric thermometer allows temperature to be measured  in depth.
  • dissolved oxygen: a meter with oxygen-sensitive electrodes connected that measures dissolved oxygen. One should be careful as doing things wrong may contaminate the air.
  • wave action: this is measured by using a dynomometer which measures the force in waves.

Freshwater:

  • turbidity: can be measured using a Secchi disc, nephlometer or turbidimeter.
  • flow velocity: can be measured by timing how long it takes a floating object to travel a certain distance or by using a flow-meter.
  • temperature: ordinary thermometers are too fragile to use for fieldwork, and are hard to read. An electric thermometer allows temperature to be measured  in depth.
  • dissolved oxygen: a meter with oxygen-sensitive electrodes connected that measures dissolved oxygen. One should be careful as doing things wrong may contaminate the air.

Terrestrial:

  • temperature: ordinary thermometers are too fragile to use for fieldwork, and are hard to read. An electric thermometer allows temperature to be measured  in depth.
  • light intensity: is measured using a light-meter.
  • wind speed: a Beufort-scale is used to measure wind speed and precise measurements can be made with a digital anemometer.
  • particle size: this determines the drainage and water-holding capacity and is measured by using a series of sieves.
  • slope: this is measured using a clinometer and using a compass.
  • soil moisture: by weighing the samples then heating them it shows the amount of water that has evaporated and the moisture levels.
  • mineral content: the loss on the ignition test can determine mineral content. The samples are heated for several hours to let volatile substances to escape.
Abiotic data can be collected using instruments that avoid issues of objectivity as they directly measure quantitative data. Instruments allow us to record data that would otherwise be beyond the limit of our perception.
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  • Describe the Earth’s water budget.

There is only a small part of the Earth’s water that is fresh water, and of this over 80% is in the form of ice caps and glaciers, 0.6% is groundwater and the rest is made up of lakes, soil water, atmospheric water vapour, rivers and biota in decreasing order of storage. This means that most of the Earth’s water budget is not directly accessible by human populations. Fresh water is therefore an extremely limited resource. (precise numbers are not needed on exam)

*Turnover time: The time it takes for water to completely replace itself in part of the system it is in, this charges from different parts of the systems.

The degree to which water can be looked at as renewable or non-renewable depends on where it is found in the hydrological cycle. Renewable water resources are renewed yearly or even more frequently, however groundwater is non-renewable resource.

  • Describe and evaluate the sustainability of freshwater resource usage with reference to a case study.

Irrigation, industrialization, and population increase all make demands on the supplies of fresh water. Global warming may disrupt rainfall patterns and water supplies. The hydrological cycle gives humans fresh water but we are taking up so much water from the underground aquifers that there is no time for it to replenish.

The demand of water has increased in both MEDCs and LEDCs, as populations are increasing as well as agriculture changing and expanding industry. MEDCs need more water as they wash more often, water their gardens, and wash their cars. This means that the increasing use of water is making the demands higher. Water is not an infinite resource and has to be controlled more carefully, and new water resources need to be found.

Water can be managed if individuals and communities make changes and this should be supported by the government. Water should not be over used or wasted so that it is insured it can be enough for everyone.

This can be reached by:

  • making new buildings water efficient (rainwater for sanitation and showers)
  • fitting new homes with more water-efficient appliances (dishwashers and toilets)
  • expand metering to encourage households to use water more efficiently
  • in some rural areas drought resistant crops should be planted to reduce the need for irrigation
  • organic fertilizers cause less pollution and bio-control measures can be used to reduce crop pests

Environmental philosophies:

Environmental philisophies: plan to manage resources sustainability without diminishing them to a degree where they become non-replenishable. Techno-centrists would argue that solutions can be found to sustain both human population and overcome unsustainable use of water resources.

As populations grow, greater demands are made on water resources. Water resources are now becoming a limiting factor in many societies, and the availability of water for drinking, industry and agriculture need to be considered. Many societies now are dependent on groundwater which is non-renewable. As societies develop, water needs to be increased. The increased demand for water can lead to inequity of use and political consequences. When water supplies fail, populations will be forced to take dramatic steps, such as mass migration. Water shortages may also lead to civil unrest and wars.

CASE STUDY

Water shortages in the Middle East:

Water shortages in the Middle Eastern countries are very common and as time passes their water supply is decreasing. Even though the region only inhabits 5% of the world’s population, it only has 0.5% of the worlds fresh water. It is predicted that the water supply will decrease from 3430 cubic meters per year to a 667 cubic meters by 2025. This is causing countries such as Israel who is suffering from a major drought to stop pumping from their major pumps of fresh water. Many factors have lead to the demand of more water and the droughts have made this worse. Despite the shortages Israel is still sharing their supply with neighbouring country Jordan. Israel is building at the moment plants that supply a third of the countries water supply and a few more plants are also going to be completed in 2013 which could double this amount. Future water shortages could lead to conflicts between the neighbouring countries.