4.4 Water Pollution Flashcards
(33 cards)
BOD definition
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
why can BOD be used to measure pollution
high levels of pollution -> more organic matter (like sewage or waste) -> more bacteria present to break it down -> use up more oxygen -> BOD = high
what is an indicator species
can be used as an indirect measure of pollution and/or environmental degradation
the presence or absence and health of these indicator species can be used to suggest conditions in the environment
example of biotic indices that can measure pollution levels
tolerance, diversity and abundance of organisms
eutrophication, what happens?
increase in nitrates and/or phosphates, leading to rapid growth of algae, accumulation of dead organic matter, a high rate of decomposition, increased BOD, oxygen-dependent organisms die
natural causes of eutrophication
- Nutrients added from decomposing biomass
- upwelling ocean currents bringing nutrients to the surface
- primary succssion = gradual eutrophication (nutrients are stored + trapped by vegetation)
human causes of eutrophication
- Run off of fertilisers or manure from agricultural land
- domestic wastewater that contains detergents (that have phosphates)
- non treated sewage
positive feedback in eutrophication
negative feedback in eutrophication
Input of nutrients increases
(e.g., nitrates/phosphates enter a lake from fertilizers)
->
Algae and aquatic plants grow
The added nutrients stimulate photosynthetic organisms to increase in biomass.
->
Nutrients are taken up and stored in plant biomass
As algae and plants absorb nutrients, nutrient levels in the water decrease.
->
Reduced nutrient availability limits further growth
As the nutrients become limited again, plant/algal growth slows down.
impacts of eutrophication environmental
- more bacteria increase BOD → makes water anoxic
- algal blooms → less light penetration to underwater plants
- reduced oxygen levels leads to death of organisms
- diversity of primary producers changes (few, fast growing algae dominate) and finally decreases (dominant species change)
- NPP increases
- turbitdiy (murkiness) increases -> decrease of light reaching submerged plants
impacts of eutrophication society
financial: loss of fertilisers from fields may reduce crop productivity and therefore farm yield and profit
health: nitrate-enriched water is associated with higher rates of stomach cancer and ‘blue baby syndrome’
characteristics of dead zones
(usually due to eutrophication)
- extreme algal blooms
- oxygen deficient water
- loss of biodiversity
- death of surface plants
- death of organic organisms
- increased turbidity
1 pollution management strategy
altering human activity
- legislation limit use of nitrate rich fertilisers
- educational campaigns to promote organic farming
- public campaigns in Australia have encouraged people to:
use zero- or no- phosphate detergents, wash only full loads in washing machines, wash vehicles only on porous surfaces + away from gutters, reduce use of fertilisers on lawns and gardens
2 pollution management strategy
regulating and reducing pollutants at point of emission
- plant buffer zones around fields to avoid run off (cost effective BUT requires land use changes)
- use fertiliser only at times of low rainfall, to reduce runoff (low cost / easy to implement BUT relies on accurate weather forecasting)
3 pollution management strategy eutrophication
clean up and restoration
- pump oxygen into anoxic lakes and ponds
- introduce plants to absorb excess nutrients
- temporary removal of fish -> allows primary producers to recover / controls algal growth -> water quality improved = reintroduce fish
abiotic features that one can measure
- ph of water
- dissolved oxygen levels
- amount of sunlight
- turbidity of water
biotic features that one can measure for water pollution
- birth and death rate of different species
- species abundance and richness
- simpsons diversity index
- lincoln index
- amount of decomposers
- habitat + genetic diversity
- algae -> use area or volume
2 examples of indicator species
- high levels of river pollution = tubifex (worm)
- low levels of river pollution = stonefly nymph (bug)
4 sources of freshwater pollution: agricultural runoff
pesticides, fertilisers, and animal waste from farms can wash into waterbodies during rainfall (like lakes and rivers)
4 sources of freshwater pollution: sewage
sewage and wastewater from households, often chemically treated but still containing harmful bacteria, chemicals, and pathogens enter water bodies when discharged into rivers and seas leading to waterborne diseases like malaria (through contamination
4 sources of freshwater AND MARINE pollution: industrial discharge
due to poor waste management, many industries drain untreated toxic waste directly into freshwater sources like rivers and canals, which then flow into larger bodies like seas, causing pollution through chemicals such as lead / nitrates that lead to eutrophication, temperature changes and serious harm to aquatic ecosystems
4 sources of freshwater pollution: solid domestic waste
improper disposal of solid domestic waste - such as plastics, packaging and household chemicals - can lead to water pollution when this waste is dumped or washed into freshwater bodies, releasing toxins/microplastics that harm marine life.
2 sources of marine pollution: oil spills
often caused by accidents involving oil tankers, release large amounts of oil into the sea where it does not dissolve, severy harming marine life, depending on spills size, toxicity and oceans capacity to dillute it.
2 sources of marine pollution: sewage from cruise ships
they can discharge untreated sewage into the ocean, pollution marine waters with pathogens, nutrients and toxins.
