human impact Flashcards
greenhouse effect
the trapping of the sun’s warmth in the atmosphere
greenhouse gases
gases in the atmosphere that absorb infrared rays and have three or more atoms
examples of greenhouse gases
water vapour carbon dioxide methane surface ozone nitrous oxide
surface ozone
a pollutant that occurs near the earth’s surface
enhanced greenhouse effect
when human activities are responsible for the excessive release of greenhouse gases, which intensifies the greenhouse effect
role of trees in co2 levels
forests are carbon sinks, trees absorb large amounts of co2 for photosynthesis from the atmosphere. less trees, less absorption.
human activity that affects co2 levels
industrialization and deforestation
global warming
higher co2 levels in the atmosphere resulting in an enhanced greenhouse effect which leads to an increase in the earth’s atmosphere
human activities which release the most co2
the burning of fossil fuels (coal, petrol, diesel) for electricity, transport and industrial processes
how to reduce co2 emissions
save electricity
create awareness
introduce incentives
human activities that release methane
- industries (the production / distribution of natural gas)
- livestock farming
- waste from homes (landfills)
methane emissions issues
methane is much more effective at trapping heat energy and is released during natural decomposition
carbon footprint
the sum of all co2 emissions resulting from your activities during a period of time
carbon footprint depends on
how much elec / energy you use
use of air transport
your daily transport
ways to reduce carbon footprint
use less air transport
recycle
buy energy-saving appliances
effects of global warming
rise in sea levels - bc of the melting polar ice caps
rise is sea surface temp
inc in extreme weather conditions (drought, floods (sea levels)
loss of biodiversity (habitats destroyed by climate change)
how to combat global warming
- afforestation
- alternative energy sources
- strategies for energy efficiency
desertification
the process during which semi-arid/arid land is transformed into a desert
causes of desertification
- higher temperatures & changes in rainfall patterns due to climate change
- deforestation
- poor farming methods (overgrazing)
effects of desertification
- loss of biodiversity (changing habitats)
- poor soil quality
- reduced productivity (food production is limited)
how to limit desertification
- alternatives to fossil fuels
- reducing deforestation (forests trap and release water)
deforestation
the permanent destruction of natural, indigenous trees to clear the area for other purposes
causes of deforestation
urbanisation (for homes)
agriculture (soil for farming)
wood for fuel
effects of deforestation
soil erosion & degradation (less nutrients in the soil)
loss of biodiversity (habitats)
global warming
how to reduce deforestation
recycle paper
create awareness
plant trees
ozone layer
the layer of gas located around the earth in the stratosphere
ozone
highly reactive gas, three oxygen molecules
ozone depletion
the thinning of the ozone layer due to the release of certain chemicals and gases that contain chlorine or bromine
ODSs
stable, non-toxic gases, which migrate towards the stratosphere bc of their stability. they are broken up by UV rays and the chlorine/bromine atoms are released
CFCs
most common ODSs, used in cooling agents ie.) fridges, freezers, air conditioners
effects of ozone depletion
damage human heath: skin cancer, dna mutations
damage agriculture: major food crops are vulnerable to an inc in UV radiation
damage to materials: plas, wood, rubb are broken down by UV radiation
how to reduce ozone depletion
reduce CFC products
limit release of ODSs
water availability is influenced by
dam construction
wetland destruction
droughts and floods
dam
a barrier that is built across a river in order to block and control water flow
dam purposes
flood control (regulate river levels)
generates hydroelectricity
supply for industrial and domestic use
irrigation
disadv of dam construction
loss of biodiversity (habitats can flood and river banks can dry out)
water loss through evaporation (large surface)
prevention of seasonal river flooding, can reduce soil fertility
wetland
a piece of land saturated by surface or groundwater, has waterlogged soil and aquatic plants
role of wetlands
purify water by acting as filters
store water (ensure reliable water supply)
replenish the water table
factors that affect wetland survival
draining for grazing and crops
pollution
urban development
poor farming practices that reduce water availability
inefficient irrigation methods (large quantities of water are lost thru evaporation w spray irrigation)
overgrazing (leads to wind and water erosion)
reducing poor farming practices
- introduce contour ploughing on slopes
- drip irrigation
- crop rotation to avoid soil leaching
how alien plants deplete the water table
usually need more water to survive than ind plants, many have developed root systems which can absorb groundwater at deeper levels
reducing the effect of alien plants
create awareness
remove them through chem, mech, bio control
plant more indigenous plants
aquifer
the underground layer of permeable rock that is saturated with water and from which underground water can be extracted through a borehole
when water is extracted from the ground faster than it is replenished
- lowered water table, aquifers are depleted
- salinisation of ground water (salt water from the coast seeps in to replace the freshwater)
- water in rivers and lakes is reduced
examples of water wastage
- leaking pipes & dripping taps
- bathing instead of showering
- poor farming practices
- water pollution (sewage)
reducing water wastage
reducing leakage
create awareness
desalination of sea/mine water
water quality
the physical, chemical and biological characteristics of water
areas in which water is used
domestic
agriculture
industrial & mining
things which affect water quality
pollutants
mining
alien invasive
effects of pollutants on water quality
- when water is contaminated w sewage, the harmful microorganisms can cause disease
- heavy metals in industrial waste water end up in water bodies
thermal pollution
when warm water is pumped into rivers and oceans by factories
reducing industrial pollution
- strict measures to reduce industry waste
- recycling wastewater
- cooling of wastewater before release
agricultural pollutants
insecticides and pesticides that are sprayed onto crops accumulate in rivers and dams after heavy rains
leaching
when artificial fertilizer does not cling to soil particles and is washed away by rain
surface run-off
nutrient rich water that eventually ends up in rivers and dams
algal bloom
large amounts of minerals in the water which cause a drastic increase in the growth of freshwater algae
eutrophication
excessive richness of nutrients in a body of water due to run-off from the land, which causes a dense growth of plant life
effects of mining on water quality
large quantities of water are used in processing raw materials in mines. this contaminated water is released and pollutes the environment.
acid mine water (AMD) (drainage)
formed when reactive minerals in rocks are exposed to water in mining activities to form acids
invasive plants
alien plants that flourish, successfully out-competing indigenous plants
- can cause eutrophication
reasons for water purification
- many available freshwater sources are contaminated
- many people in rural areas do not have access to safe water (have to purify their own)
food security
exists when all people have physical and economic access to sufficient, safe and nutritious food to meet their nutritional needs for a healthy life
factors influencing food security
- exponential human population growth (due to better medical field, increased agricultural productivity)
- droughts and floods (crops fail, livestock are lost)
- poor farming practices : monoculture
monoculture
a farming practice where a single crop or plant species is planted on the same piece of land for a number of years (soil nutrients become depleted, crop size and quality decreases)
genetic modification
the deliberate changing of an organism’s traits by manipulating its genetic material
advantages of GM food
- greater crop yields
- high nutritional value
- longer shelflife
- animals produce more meat, milk, eggs
disadvantages of GM food
- can affect human health (causes allergies)
- can be unaffordably expensive in the long run
biodiversity
the biological diversity and variety of life in a particular area
importance of maintaining biodiversity
IMPROVES
- air quality (plants species purify air)
- water quality (wetland ecosystems cleanse wastes and treat sweage)
- soil quality (some species can condition soils and break down org matter)
threats to biodiversity
- habitat destruction
- poaching and hunting wildlife
- pollution leading to cc
- alien invasive plants
how habitat destruction occurs
occurs through:
- urbanisation
- deforestation
- mining (trees and topsoil are removed so that mines can be developed)
poaching
- the illegal hunting / trapping of animals and removal of plants
- often targets endangered species
mechanical control of alien plants
- plants and trees are cut down or burned, labor intensive
chemical control of alien plants
herbicides, is effective but can adversely affect the surrounding plant and animal species, pollutes water and soil
biological control of alien plants
- natural enemies (insects eg) from the plants natural habitat used
- deliberately effect the plants with pathogenic viruses
indigenous knowledge
the knowledge indigenous cultures / communities gained through their interaction with the environment. they determined which plants are edible, poisonous and which store water.
sustainable use
the use of resources to fulfil human needs while ensuring there is sufficient supply for future gens
where is devil’s claw found
in the Kalahari desert in SA, Namibia, Botswana
uses for devil’s claw
can be used to treat arthritis and rheumatism
can also be used as: a sedative, diuretic
sustainable use of devil’s claw
very difficult to cultivate, cannot be harvested without a permit
where rooibos is found
endemic to the Cederberg Mountain in WC
uses for rooibos
- caffeine free
- rich in anti-oxidants
- calming effect
- relieves digestive problems
fynbos
the type of vegetation that occurs exclusively in the SWern area of WC
fynbos consists of
reeds, ericas and proteas
threats to fynbos survival
- invasive alien plants
- fires caused by human error at the wrong time and too frequently can wipe out species (some fynbos only flower after a fire)
- urbanisation
measures for sustainable fynbos survival
- eradicating alien plants
- controlled fires at the right time which are essential for seed germination
where african potato grows
in natural grasslands in the eastern summer rainfall regions of SA
african potato reproduction
do not grow from seeds easily: they reproduce by division of their corm to form new plants. therefore, removal of the corm drastically reduces their numbers
african potato uses
- strengthen the immune system\
- can treat TB, UTIs and constipation
solid waste
is solid or semi-solid insoluble material such as garbage, sewage sludge, etc
main categories of waste
general
hazardous
general waste
waste that does not pose an immediate danger or threat to health or the environment
general waste examples
household waste
waste from cons sites, businesses
hazardous wastes
waste that contains harmful/toxic/explosive substances that will effect health & the environment
landfill site
a site where waste is dumped into a giant hole in the ground and covered with soil
hazards landfills near residential areas pose
- attract pests
- dust and odors
phytoremediation
the use of green plants to remove toxic substances from soil water sediment air to render them harmless
management and rehabilitation of dumpsites
- waste is compacted to reduce volume and covered w soil everyday to prevent further air contact
- rain water that filters through it accumulates in pipes and is tested regularly for the levels of chemicals. this water is treated to prevent contamination.
- methane gas is used as an energy source.
advantages of recycling
less waste is generated
less space is used for landfills
reduces the cost of municipal waste disposal
household waste categories
dry - recyclable
wet - non recyclable
hazardous - should not be placed in household bins
organic - can be used for compost
process of generating elec from methane
drawn into pipes from landfill sites and collected and burned at a central points. this drives a generator which generates elec.
- has reduced impact of greenhouse gas emissions (O and CO2)
- less emissions from powerplants
nuclear waste is produced by
power plants
mining industires
the use of radioactive materials
three groups of radioactivity level
low, intermediate, high level
