How Humans Can Affect the Environment Flashcards
What do humans pollute?
- Waterways with sewage, fertiliser, and toxic chemicals
- Air with smoke and gases such as sulfur dioxide, which contributes to acid rain
- Land with toxic chemicals such as pesticides and herbicides. These can be washed into the water
What is the difference between a pesticide and a herbicide?
A pesticide kills animals (pests)
A herbicide kills plants (herbs…)
How do humans reduce the amount of land available for plants and animals?
By building, quarrying, farming, and dumping waste
What is produced when goods are made?
Industrial waste
How is the land polluted by humans?
- Sewage contains gut parasites and toxic chemicals. It must be treated properly to remove these
- Household and industrial waste placed in landfill can leak toxic chemicals. Some industrial waste, such as radioactive waste, is very hazardous
- Farming methods can pollute the land
- Herbicides and pesticides are poisons and can enter the food chain or be washed into rivers
- Chemical fertilisers can be washed into rivers
How is water polluted by humans?
- Herbicides, pesticides, and chemical fertilisers are washed into rivers + streams
- Fertilisers and untreated sewage can cause a high level of nitrates in the water
- Toxic chemicals from landfill also leak into the waterways and pollute the water, killing organisms such as fish
What produces sulfur dioxide and other acidic gases?
Burning fuels
Cars and power stations release them
How is acid rain produced?
Sulfur dioxide dissolves in the water in the air, forming acidic solutions
The solutions then fall as acid rain
This can happen a very long way from where the gases were produced
How can acid rain affect organisms?
- Trees can be damaged if the leaves are soaked in acid rain for long periods
- When trees are damaged, food and habitats for other organisms are lost
- Acid rain can also change the soil pH, damaging roots and releasing toxic minerals such as aliminium ions
- Enzymes are also very sensitive to pH
What has deforestation caused?
- Increased the rate of CO2 in the atmosphere due to the burning of trees or decay of wood by microorgamisms
- Reduced the rate at which CO2 is removed from the atmosphere by photosynthesis
- Reduced biodiversity due to loss of food + habitats
Why has deforestation occured?
- So that crops can be grown to produce ethanol-based biofuels
- So there can be increases in cattle + rice fields for food
What has led to an increase in the levels of methane in the atmosphere?
Cattle + rice growing
What does the destruction of peat bogs lead to?
- Releases CO2 into the atmosphere
- The peat is used in compost
- The compost is then decayed by microorganisms
- The decay is what leads to the release of CO2
How is carbon dioxide sequestered?
It is removed from the air by plants in photosynthesis and by dissolving in oceans, rivers, and lakes
What might an increase in the Earth’s temperature by only a few degrees celcius lead to?
- Changes to the Earth’s climate
- Rise in sea levels due to the melting of the ice caps and glaciers
- Reduce biodiversity
- Cause changes in migration patterns
- Result in changes in the distribution of species
How is ethanol produced from starch for use as a biofuel?
- Microorganisms respire anaerobically to produce it
- Sugars from crops are used as the energy source
- Glucose is produced from maize starch using carbohydrase
- The ethanol is then extracted via distillation to be used as a fuel
Digestion -> Fermentation -> Distillation
How is biogas produced?
By anaerobic fermentation by bacteria using waste carbohydrate
Which gas is the fuel in biogas?
Methane
How do biogas generators work?
- Provide the ideal conditions for bacteria to reproduce and germent the carbohydrates
- Maintained at a suitable temperature in an oxygen-free environment
- Some are designed to mix the contents
- They are either burried in the ground for insulation or have insulating jackets
Where do large-scale, commercial generators use waste from?
Sugar factories or sewage works
What makes biogas better quality?
More methane = better quality
Aside from methane, what else do biogas generators produce?
Slurry, which can be used as a fertiliser
Why is it more efficient for us to eat plants and not animals?
The food chain is shorter, so less energy will be wasted
How can we produce meat more efficiently?
- Preventing the animal from moving so it doesn’t waste energy on movement
- This is seen as cruel by many so is contraversial
- Keeping the animal in warm sheds so it doesn’t use as much energy from food to maintain its body temperature
What is sustainable food production?
Methods of producing food which can be sustained/carried out over time without destroying the fertility of the land or ocean
How are fish stocks in the oceans preserved?
- They are monitored
- Fishermen have quotas
- Fishermen have to use certian sized nets to avoid catching small, young fish
What is Fusarium used to produce?
Mycoprotein - a protein-rich food suitable for vegetarians
How is Fusarium grown?
Aerobically on cheap sugar syrup made from waste starch in a fermenter
What features do industrial fermenters have?
- Air supply providing oxygen for respiration
- Stirrers or gas bubbled used to keep the microorganism spread out and to provide and even temperature
- A water-cooled jacket around the outside, as the respiring microorganisms release energy which heats the contents (to maintain correct temp.)
- Sensors to monitor both pH and temperature
What human activities can affect the global environment?
- Deforestation - can increase levels of CO2
- Rice growing + cattle farming lead to increase in levels of methane
- Building dams to store water in reservoirs causes loss of habitat, drying out of rivers, and reduction of fertile land
