Flashcards in Water Sources and Sustainability Deck (59)
what is eutrophication
Eutrophication is the increased concentration of nutrients, phosphate and nitrates in a water way that promotes an algae bloom. The process can occur naturally through the breakdown of leaves and weathering rocks or can be caused by humans when fertiliser used on crops runs-off into waterways.
List the 5 effects of Eutrophication
- The creation of dense blooms of noxious, foul smelling phytoplankton that reduce water clarity and harm water quality.
- Limit light penetration, reducing growth and causing die-offs of plants while also lowering the success of predators that need light to pursue and catch prey.
- High rates of photosynthesis associated with eutrophication can deplete dissolves carbon and raise the pH to extreme levels during the day. Elevated pH can turn organism that rely in the perception on dissolved chemicals ‘blind’ as it impairs their chemosensory abilities.
- When the dense algae bloom eventually die, microbials decomposition severely depletes dissolved oxygen creating a hypoxic or anoxic ‘dead zone’ lacking sufficient oxygen to support most organisms.
- Some algae release toxins into the waterways which leads to bioaccumulation.
Outline the first 2 steps of the eutrophication process.
1. Nutrient load up. Excessive nutrients (nitrate and phosphate) from fertiliser runoff are flushed from the land into waterways by rainwater.
2. Plants flourish. These pollutants cause aquatic plant growth of algae, duckweed and other plants. Algae covers the water surface.
outline the 3rd and 4th step of eutrophication
3. Algae blooms, oxygen is depleted. Algae blooms preventing sunlight reaching other plants, meaning photosynthesis cannot occur. The plants die and oxygen in the water is depleted. As producers die, consumers of the plants begin to die too.
4. Decomposition further depletes oxygen. Dead plants and organisms are broken down by bacteria called decomposers using up even more oxygen in the water. This process continues as organisms further down the food chain continue to die.
Outline the 5th step of eutrophication
5. Death of the ecosystem. Oxygen levels reach a point where no life is possible, algae has used up all nutrients and will begin to die. Decomposers will break down algae, using the limited oxygen available. No oxygen will result in the death of an ecosystem.
What is bioaccumulation
The accumulation of non-biodegradable matter in the tissues of one organism, passed along from the previous organism in the food chain. As the concentrations of non-biodegradable substances build up, the toxicity also builds up until it affects the organisms higher in the food chain.
What are substances that can bioaccumulate
- Heavy metals.
- Novel organic substances.
- Some organic pollutants.
Why can these specific substances bioaccumulate
These substances are lipophilic (oil loving) and accumulate in the fatty tissue of organisms this means it stays in the organism’s body.
what is an oil spill
The result of old damaged equipment and human error. Extracting oil from the ground and moving it to refineries etc. can result in the release of oil into the environment.
what effects the size of the impact of an oil spill
There is no clear relationship between the amount of oil and its impact on biodiversity. Smaller spills in a sensitive environment at the wrong season/time of year may have a large impact, compared with a large spill at a different time of year in the same or different environment.
Oil spills affect on birds
- Oil spills effect the feathers of birds and the fur of mammals. This reduces their ability to insulate/regulate body temperature, making organisms sensitive to temperature fluctuations and less buoyant in the water.
- Impairs bird’s ability to fly, impairing their ability to forage and escape from predators. As birds preen (clean themselves) they may ingest the oil that has coated their feathers, causing damage to the kidney and digestive tract. These factors together result in dehydration and metabolic imbalance.
Oil spills effect on the environment and other organisms
- Large spills result in fouled coastlines, polluted fisheries, dead and injured wildlife and lost tourism revenue. These affects can be brought about by the oil itself or the clean-up process.
- The oil impairs the ability of offspring to use scent to locate their mother as the oil has such as strong smell. This increases the chance of babies being rejected, left to starve.
- Fur marine mammals, oil coats the fur of organisms such as sea otters and seals, reducing insulating effects, possibly resulting in hypothermia.
- Oil also has the ability to blind organisms and organisms may be poisoned and die from oil entering the lungs.
The build-up of too much soil and suspended particles in water.
Causes of sedimentation
Inadequately managed activities such as farming, land clearing, building roads and mining can put too much soil and particulate matter in river. Sedimentation can be caused by land clearing as the water that was once previously absorbed by plants, would no longer be absorbed and would run off downhill, into a water source, collecting particles.
effect of sedimentation
- Sediment can harm plants and animals by carrying toxic chemicals into the water, smothering fish eggs and small organisms getting sick if they consume the water further reducing the quality of water.
- Sedimentation also increases the turbidity, effecting photosynthesis, providing an attachment site for pathogens, fills in water ways quicker and effects the predator prey relationships.
- Run off can lead to eutrophication, picking up nutrients and fertilisers etc.
What is the over use of water sources
The process in which water sources are drying up as too much water is being drawn from them for humans use, faster than it can be replenished.
how are surface and ground water affected by over usage of water
Surface Water: Lakes, rivers and other surface water sources drying up because too much water is being drawn from them.
Ground Water: The drying of aquifers faster, then the water can be replenished. Drought periods have compounded this, so that the result is a loss in habitats, which reduces food, available and the amount of drinking water.
Physical and chemical pollution
The disposal of physical waste which can directly harm an organism as well as oil spills and pesticide/herbicide run off which can result in bioaccumulation.
Dams and reservoirs
Stops water flow from what was once a whole ecosystem, meaning organisms must adapt or die.
Depletes water supplies and aquatic habitats.
Logs are removed (de- snagging) for recreational activities. Removing logs removes habitats, increases turbidity, removes breeding grounds and removes hiding spots for prey leaving them vulnerable.
invasive and introduced species
Introducing more predators and competition for native organisms.
Activities such as overfishing, decreasing populations of organisms at a faster rate than which they can replenish themselves.
Properties of potable water
- Low Turbidity.
- Nutrient levels are not at a level in which eutrophication has occurred.
- Neutral pH 6-7. Not alkaline or acidic, heavy metals may be dissolved.
- Low salinity.
Sources of potable water
1. Surface Water. The water in rivers, streams, creeks, lakes and reservoirs.
2. Ground Water. Ground water is part of the water cycle, precipitation seeps down through the soil until it reaches rock material that is saturated with water. Water is stored in the spaces between the rock particles.
3. Desalination. A process that takes away the mineral components from saline water. Salt water is desalinated to produce water suitable for human consumption or irrigation.
1. Salt water is heated causing water as a liquid to turn into a vapour through evaporation. Salt is left behind in this process.
2. Water vapour cools and condenses, this can be collected and is now fresh water with no salt.
This process can be considered quite outdated, as heating the source requires a large amount of energy and a large amount of salt is left behind with no purpose.
1. Sea water is pumped into desalination plant from the ocean and passes through a pre-treatment filtration to remove the majority of large and some small particles.
2. The filtered sea water is then forced under pressure through a semi-permeable membrane which only allows water to pass through (no bacteria, viruses or other impurities).
3. About ½ of the water that enters from the sea becomes fresh drinking water.
4. The remaining water with salt and other impurities is returned to the ocean via diffusers which ensures it mixes quickly to prevent impact on marine environment.
5. The desalinated water is then subject to further treatment to meet drinking water standards.
Membrane process overall
This is a more recent and widely used process. The process relies on a semi-permeable membrane with pores, so tiny that salt cannot pass through, reverse osmosis is used.