Revision test Feb 27 2025: topic 4.4

Self testing

1. Outline the different types of aquatic pollutants

• Nutrient pollution

2. State 3 direct methods that can be used to test the quality of aquatic systems

• idk

3. State 2 indirect methods that can be used to test the quality of aquatic systems

• idk

4. Define biochemical oxygen demand and explain how it can be measured

• biochemical oxygen demand is checking how the oxygen levels in water are affected by organisms in it

• it can be measured by small samples of water and how oxygen affects it

5. Define and give examples of indicator species

• indicator species are species chosen specifically to help scientists see the changes in ecosystems, for example, shrimp are good indicator species since they are tolerant of pollution, so if there are problems with the shrimp, it indicates to scientists that something is wrong with the water quality

6. Outline the use of biotic indices in measuring pollution

• idk

7. Outline the process of biodegradation leading to methane, hydrogen sulfide, and ammonia

   • the biodegradation of organic materials require oxygen. During this process of biodegradation, methane starts to form, thus creating methane and ammonia poisoning

8. Explain the process and impacts of eutrophication

   • Eutrophication happens when there is a large input of nutrients, causing water plants (such as algae and seaweed) to thrive. this leads to the plants covering the surface of the water, not allowing sunlight to enter the water, killing aquatic ecosystems in the process

9. Outline the major causes of nutrient enrichment that can lead to eutrophication

   • agricultural fertilizers

10. Evaluate pollution management strategies with respect to water pollution

• Pollution management strategies can help

Answers

1. Outline the different types of aquatic pollutants

• Aquatic pollution includes the following:

  • toxic metals

    • released from the burning of coal and dumped directly by industrial effluent

    • in the form of methylmercury, the metal can bioaccumulate in organisms and then magnifying along food chains

    • common toxic metal: Mercury

  • Synthetic compounds

    • are persistent and biomagnify in food chains

    • due to the nature of how the earth spins on its axis, these compounds end up in much higher concentrations in polar regions

    • common example: POPs (persistent organic pollutants)

  • Hot water

    • commonly released from thermal power plants to generate steam which turns the turbines

    • the water is always warmer than it was originally and can change the local ecosystem

    • certain amount of dissolved oxygen in water decreases as the temperature decreases

    • common examples of companies that might use hot water: oil, gas, coal, nuclear

  • oil spills

    • usually occur from the extraction and transportation of oil

    • usually leaks from ships and boats

    • oil sticks to the organisms preventing them form being able to move or breath

  • radioactive pollution

    • can enter water from industrial accidents

    • particles move around in ocean currents and can bioaccumulate organisms

    • examples of where this happened: Fukushima and Daiichi

2. State 3 direct methods that can be used to test the quality of aquatic systems

• water temperature

• pH

• presence of E. Coli

3. State 2 indirect methods that can be used to test the quality of aquatic systems

• biological oxygen demand

• biotic index of water

4. Define Biochemical oxygen demand and explain how it can be measured

• 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

• BOD is used to indirectly measure the amount of organic matter within a water sample

• it is measured as the mass (in milligrams) of dissolved oxygen consumed per liter of water when a water sample is incubated in a dark chamber (20℃) for 5 days

  • it must be compared by a control of uncontaminated water

5. Define and give examples of indicator species

• indicator species is an organism whose presence reflects a specific environmental condition

• indicator species can signal a change in the biological condition of a particular ecosystem and thus can be used to diagnose the health of an ecosystem

• example species:

  • lichen —> air pollution

  • stonefly and mayfly nymphs —> clean water

  • tubifex worms —> indicators of oxygen depleted water

6. Outline the use of biotic indices in measuring pollution

• A biotic index indirectly measures pollution by assaying the impact on species within the community according to their tolerance, diversity and relative abundance

7. Outline the process of biodegradation leading to methane, hydrogen sulfide and ammonia

• biodegradation of organic material utilizes oxygen, which can lead to anoxic conditions and subsequent anaerobic decomposition, which in turn leads to formation of methane, hydrogen sulfide and ammonia (toxic gases)

8. Explain the process and impacts of eutrophication

• the nutrient enrichment leads to algal blooms which can block light penetrating the water

• as the algae use up the nutrients they start to die and fall to the bottom of the water body. decomposition results in the oxygen being used up in the water and hence anoxic conditions. this leads to the death of organisms in the water and dead zones

9. Outline the major causes of nutrient enrichment that can lead to eutrophication

• Industrial

  • dissolving of nitrogen oxides from fossil fuels and nitrogen compounds produced by cars and factories

• natural

  • natural runoff (dissolved nitrates and phosphates from soil and rock

• agricultural

  • inorganic fertilizer runoff (nitrates and phosphates)

  • manure runoff from feedlots and fields applied with organic fertilizer (nitrates, phosphates, and ammonia)

  • runoff and erosion from cultivation and poor land use

10. Evaluate pollution management strategies with respect to water pollution