Water pollution Flashcards
What is water pollution?
Water pollution is the contamination of bodies of water by pollutants either directly or indirectly
Name 4 sources of freshwater pollution
- Agricultural run-off
- Sewage
- Industrial discharge
- Solid domestic waste
What is the impact of oil (inorganic pollutant) on water
- floats on surface
- contaminates seabirds
- reduces oxygen levels
What is the impact of light + noise pollution on water ecosystems?
- Disrupt turtle nesting sites
- Upset whale navigation
- Change plant growth
- Upset bird cycles
What is the biochemical oxygen demand (BOD) ?
BOD is a measure of the amount of dissolved oxygen required to break down the organic material in a given volume of water through aerobic biological activity by microorganisms
What are indicator species?
plants and animals that show something about te environment by their presence, absence, abundance or scarcity
What is a biotic index?
A biotic index indirectly measures pollution by assaying the impact on species within the community according to their tolerance, diversity and relative abundance
Give an example of an indicator species
Indicator species are most sensitive to change so they are the early warning signs that something has changed in ecosystem
e.g. canaries taken down coal mines as they’re more sensitive than humans to poisonous gases, if gases present, canary would die so miners would know to get out
Why are invertebrates used to estimate levels of pollution?
- they are sensitive to decreases in oxygen concentration of water, caused by the action of aerobic bacteria as they decompose organic matter
- the presence of indicator species is used to calculate a biotic index
How do dead zones and anoxic conditions result from eutrophication?
- When its severe it results in dead zones in oceans//freshwater where theres not enough oxygen to support life
- in less severe cases, biodegradation of organic material uses up oxygen which can lead to anoxic conditions + then anaerobic decomposition, releasing methane and ammonia (toxic gases)
Name 5 impacts of eutrophication
- Anaerobic water
- Loss of biodiversity + shortened food chains
- Death of higher plants (eg flowering plants)
- Death of aerobic organisms (invertebrates, fish)
- Increased turbidity of water
Name 5 causes of eutrophication
- detergents
- fertilisers
- draining from intensive livestock rearing units
- sewage
- increased erosion of topsoil into water
Outline the process of eutrophication
- Eutrophication is increase in nutrients (e.g. phosphates + nitrates) in rivers + lakes
- May be from natural run-off from surroundings or decomposing biomass
- Also from agricultural actual and fertiliser
- Also from sewage
- Increase in biomass of algae caused by both human + natural eutrophication
- Algal blooms prevent plants underneath them receiving light and so increased bacteria feed on them and reduce oxygen content of water
- Reduced oxygen causes collapse of food chains
Where has the largest zone in the USA and what are the solutions?
- Gulf of Mexico has largest dead zone in USA
- Caused by excess nitrates+phosphates from Mississippi river basin agriculture
- Solution = a water quality trading scheme that allows those that can reduce nutrients at low cost to sell credits to this facing higher-cost nutrient reduction options
What are red tides?
- in coastal waters, algal blooms (large no. of phytoplankton) are sometimes caused by excess nutrients
- if these phytoplankton are a species of dinoflagellate, the bloom looks red
- algae produces toxins which kill fish + accumulate in shellfish, making humans v ill
