Humans and Environment
Improvements in farming
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Use of technology
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Agricultural machinery has replaced humans and improved efficiency due to the ability to
farm much larger areas of land
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Chemical fertilizers
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Improve yields
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Fertilisers increase the amount of nutrients in the soil for plants, meaning that they grow
larger and produce more fruit
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Insecticides and herbicides
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These chemicals kill off unwanted insects and weed species, meaning that there is less
damage done to plants and fruit lost to insects (insecticides), as well as reducing
competition from other plant species (herbicides)
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Selective breeding
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Animals and crop plants which produce a large yield are selectively bred to produce breeds
that reliably produce high yields
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Monoculture
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When only one species of crop is grown at once. This is done to maximise efficiency and
simplicity
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However, doing this has a negative impact on the environment. There is a loss of
biodiversity, this can harm food chains and reduce population of some species
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Intensive farming
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More livestock in a smaller area
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The temperatures are controlled
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Fed with high energy foods and antibodies to prevent diseases
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Increases yield of crops as well as animals
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Therefore, production of milk, eggs and meat increases but it is unsustainable
Food shortage
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Caused by natural disasters, increasing population, poverty and unequal food distribution
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Causes deforestation, more greenhouse gases, global warming, natural disasters and rising
sea levels
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Habitat destruction
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Habitats are destroyed by humans to make space for other economic activities
Causes of destruction
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Clearing land for farming and housing
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With an increasing population, there is a higher demand for food, this can only be done by
increasing land
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Natural resource extraction
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Some resource extraction takes a lot of space for e.g mining
Marine pollution
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Oil spills and other waste pollutes oceans and kills sea life. Eutrophication can occur if
fertilizers enter waterways, this causes huge decrease in biodiversity
Effects of deforestation
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Extinction
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Habitat destruction can lead to extinction of spaces that live there
Soil erosion
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Without roots to anchor the soil, it is carried away by wind and heavy rains. This
decreases fertility of these areas
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Flooding
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Forests prevent flooding by slowing time that water takes to reach the ground they also
allow water to be absorbed into the soil.
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Increased CO2 in atmosphere
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Trees absorb CO2 from the atmosphere. If there are fewer trees, less CO2 is absorbed
thus there is more in the atmosphere, increasing global warming.
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Plastics have a large negative impact on both land and water habitats due to their
non-biodegradability
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Eutrophication
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Fertilisers are washed from fields into the waterways by rain. This brings an access of
nutrients in to the habitat
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The nutrients cause plants to grow rapidly, and there is an algae bloom across the surface
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Algae covers the surface of the water, preventing sunlight from passing through. This
means that plants cannot photosynthesise, less oxygen is released into the water. The
dead plants are broken down by decomposers, which use up the remaining oxygen from the
water
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Female contraceptive hormones
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These hormones are excreted by body in urine, then make their way into water supply, as
they are not filtered out of sewage treatments. When they reach male aquatic organisms
such as fish and frogs, it causes feminisation, male organisms begin to produce eggs and
lose the ability to reproduce
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Acid rain
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Sulfur dioxide is formed when fossil fuels are burnt
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Burning of fossil fuels releases nitrogen oxides
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SO2 and NO2 dissolve to form acid rain
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Acid water in river adds toxic chemicals and causes food shortages, both of which reduce
fish life
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Acid soils are more acidic by acid rain
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It causes corrosion of infrastructure and damages tree bark and leaves
To prevent acid rain, sulphur dioxide is removed from gases before they are released into the
atmosphere. Sulphur can also be removed from fossil fuels before burning
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Soil and water can be made less acidic by adding powdered limestone or slaked lime(alkali)
Sewage treatment
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Sewage is waste liquid coming from houses, industries etc.
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Sewage is harmful therefore it is treated to make it safe
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First, raw sewage is passed through screens. These trap large objects such as grit which may
have been washed off roads. The screened liquid is then left for a while in settlement tanks,
where any insoluble particles drift to the bottom and form a sediment. After these 2 steps,
there are 2 ways to treat the sewage
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Trickling filter
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The liquid from the settlement tank is sprinkled over a trickling filter bed. It is made of
small stones and clinkers. Aerobic bacteria live on these stones which contain many aerobic
organisms, and these bacteria feed on various nutrients in the sewage. Protoctists then
feed on these bacteria, fungi feed on soluble nutrients. These microorganisms make up a
complex ecosystem in the trickling filter bed
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This liquid is then trickled onto the surface of the stones through holes in a rotating pipe.
This makes sure that air gets mixed with the liquid. The liquid filters slowly, giving the
organisms enough time to feed.
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By the time the water is in the bottom of the bed, it looks clear and smells clean and
contains no pathogenic organisms and can be safely allowed to run into a river or sea
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Activated sludge
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The liquid from the settlement tank goes into an aeration tank, it also contains aerobic
microorganisms. Oxygen is provided by bubbling air through the tank. The microorganisms
make the sewage harmless.
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Sustainable development is defined as development which meets the needs of people today as well
as increasing population without damaging the environment
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Endangerment is harmful to a species as it greatly reduces the gene pool by decreasing number of
alleles available
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Prevention of extinction
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Monitoring → species need to be monitored
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Education → allows people to understand why a species is becoming extinct
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Captive breeding → bred in captivity where their chance of survival is greater
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Seed banks → seed from endangered plant species can be preserved so that plants may be
grown in the future
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Conservation is important to prevent the extinction of species and to protect the extinction of
species and to protect the environment
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Improve sustainability to make sure there are resourced still available in the future