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Enviro revision:, Energy and the environment, Natural ecosystems and human…
Enviro revision:
3.8 An integrated approach for sustainable agriculture
Aims of sustainable agriculture:
meeting the needs of the population for agricultural produce
making efficient use of non-renewable resources
supporting the natural ecosystem and mimicking natural processes with farming techniques
sustaining the economic independence of farmers
Organic fertilisers:
tend to release their nutrients slowly, reducing the risk of eutrophication
in many areas are a waste product, so using them for agricukute saves on disposal costs
are already present on many farms, so there are minimal transport costs assosiated with using them
do not require energy for their manufacuture
also improve the soil structure
Grazing benefits:
prevention of overgrazing and reducing the ability of grazed plants to regrow
maintaining appropriate soil fertility by moving livestock between different fields
maintaining good drainage
Crop rotation benefits:
less risk of pests and diseases because the crop is not grown in the same plot as the previous year
efficient use of cultivation techniques
efficient use of available fertilisers
increasing the likelihood of at least one good crop in any one year
Irrigation benefits:
minimising the amount of water used
targeted delivery of water to the plants
the ability to only use the system when the plants need water
automation of the process to reduce the amount of labour needed to operate it
reduced risk of salinisation of the water in the soil
3.2 Soils for plant growth
Combination of factors for a plant to grow successfully
The availability of important mineral nutrients to supports plant growth
Plants require a supply of nitrogen, phosphorus, potassium and other essential elements to contruct proteins and other chemicals to carry out plant processes. Mineral nutrients obtained through the roots of the plant.
Anchorage to hold the roots securely in one place
A supply of water
Oxygen around the roots to enable the root cells to respire
Soil pH
Some plants fail to grow well in certain soils even if supplied with additional fertiliser. pH of the soil will also impact on the availability of these mineral nutrients within the soil.
Signs of mineral nutrient deficiencies in plants
Nitrogen-
slow growth, yellowing leaves
Phosphorus-
leaves dull with blue-green colour, leaves fall early
Potassium-
poor-quality fruits and seeds, leaves with brown edges
Sulfur-
yellowing of the leaves
Calcium-
death of plant tissues, poor fruit storage
Magnesium-
yellowing leaves between the leaf veins, early leaf fall
Iron-
yellowing leaves between the veins, failure to flower
Copper-
dark green leaves become twisted and withered
Zinc-
leaves show poor development, might only grow to a very small size
Boron-
leaves misshapen and malformed
Soil organic content
Organisms involved in breaking down organic mater
Earthworms:
help break down vegetation by digesting it as it passes through their bodies and excreting the remains
Fungi:
feed directly on dead matter and are particularly good at breaking down touch materials such as woody items
Bacteria:
work on organic material at a smaller scale, covering waste products into simple chemicals that can be used by plants
High levels or organic matter have the following
positive
effects
Increase the water-holding capacity of a well-drained soil.
The organic matter acts like a sponge and absorbs additional water when it is available and releases it when it is required by plants. Less irrigation is required.
Increase the air spaces in the soil.
The open sponge-like structure of organic matter allows the air to penetrate, which is very useful for soils that naturally have few air spaces. Plant roots need oxygen for respiration, and insufficient oxygen results in roots death.
Increase the number of decomposer organisms.
Extra organic matter means a more abundant food source. E.g. increase in works increases the number of tunnels or burrows in the soil, providing additional drainage in poorly drained soils and less compaction, increasing the amount of oxygen available to plant roots.
Prevent the loss of mineral nutrients.
Some mineral nutrients are washed away in excess water. Humus, the material left after organic matter has been partially decomposed, has the ability to hold onto mineral nutrients until they are needed by plants.
Sandy soils verses clay soils
Air content:
clay soils have small air spaces that can limit the amount of oxygen reaching plant roots. This in turn can limit respiration and the amount of possible root growth. Sandy soils have large air gaps allowing good transmission with high levels of oxygen and therefore a healthy root system.
Water content:
water tends to cling to the surface of particles. A clay soil has far more particles, and therefore a far larger surface area, compared with sandy soil. Clay soils therefore hold significantly more water.
Characteristics of soils
Sandy soils:
free draining, low water-holding capacity, quick to warm up, easier to cultivate, poor retention of nutrients, greater risk of erosion.
Clay soils:
high water-holding capacity, slow to warm up, small air spaces which are harder for roots or organisms to penetrate and contain less oxygen, water does not drain away faulty, hard to cultivate, retains nutrients well
3.5 The impact of agriculture on people and the environment
Overuse of insecticides and herbicides
Chemical sprays to control populations of insects and weeds has increases yield and also prevented the loss of food in storage. Regular use of the one insecticide chemical can cause resistance within the pest population. This means the toxic chemical no longer kills all the target pest in individuals. The best practice for farmers is to use a range of different pesticides so that if resistance starts to build up to one product another products is still likely to be toxic to the pest.
Misuse of fertilisers
For farmers, it might be most cost effective to apply a lot of fertiliser all at one time. If the weather or soil conditions are not right at that time, this can mean that much of the nutrient content is wasted; heavy rain can dissolve the mineral nutrients and carrying them away as it runs-off the land or soaks through the soil (leaching).
Excess water containing dissolved fertilisers drains into rivers and lakes, upsetting the natural balance of mineral nutrients there. Excess amounts of nitrogen and phosphorus can cause
eutrophication.
Eutrophication-
a sequence of events starting with enrichment of water by mineral nutrients or organic matter that leads to a reduction in oxygen levels in the water and the death of fish and other animals.
Misuse of irrigation
Damage to the soil structure:
when wet, air pockets are lost and the soil is compacted.
Death of plant roots:
waterlogged soils prevent plant roots getting sufficient oxygen to respire and cells start to die.
Loss of nutrients:
nutrients dissolve in the water in soil, and as water drains away nutrients are taken away with it.
Soil erosion:
large amounts of water run-off will take some of the soil particles with it.
Soil capping
: the surface of the soil can become hard and compact, which makes it harder for plants to grow through the soil.
Salinisation:
salt content of the soil can increase.
Preventing soil cultivation:
if the water content is too high, the soil can be too heavy to cultivate. Machines get stuck because the soil structure cannot support their weight.
Overproduction and waste
Waste from over-production:
too much of a crop might mean that some will not be sold.
Waste of storage space:
it may take longer to sell a crop, so buildings are needed to store the spare harvest. Some crops need special conditions so they do not spoil.
Waste of transportation:
to sell all the crop, a farmer may need to travel larger distances, using more fuel etc.
Waste of quality produce:
if a crop starts to decrease in quality because it has not been sold quickly enough, it will be worth less money.
Waste of labour:
the farmer may have to staff to help grow and care for the crop , which is not an efficient use of time and labour if too much crop is produced.
3.4 Increasing agricultural yields
Pressure on food production:
increasing world population needing more resources
climate change affecting the availability of fertile land
increasing settlement sizes reducing available farmland
increasing in the standard of living creating a demand for more food variety
large populations impacting on the availability of water for irrigation
Solutions to world hunger
Reducing the population increase, this well decrease the predicted demand for food. E.g. China's one child policy are an attempt to reduce population numbers in a managed way.
Growing more staple crops that are high yielding, and fewer luxury items that are not so productive. Current resources could be used to grow a greater mass of food if humans ate more staple foods and fewer luxury items.
Ensuring greater food equality, Some people dont have enough to eat, others have more than they need.
Eating less meat. it wastes resources.
Techniques for improving crop yield
Crop rotation
- Growing different types of plants in different plots each year. Related plants are grown together during a season, then at the start of the next season moved to a different plot of land that has just been used for a different plant group.
diseases in the soil affecting the plant are left behind and have nothing in infect
pests need to find the new site and so their number are reduced
the soil in the new plot is more likely to have the nutrients the corp needs
Fertilisers-
contain minerals which are essential for healthy plant growth. When used correctly, increases crop yield because they add to the amount of mineral nutrients already present in the soil.
Organic vs inorganic
Organic fertilisers are substances that have been derived from natural sources.
Inorganic fertilisers are manufactured within a factory.
Irrigation-
Availability of water within the soil is a major limitation to the growth of a crop. Water is also in demand for human consumption, industry and livestock.
Control of competing organisms
- A weed is a plant that is growing in an inappropriate place. Weeds need to be controlled because they
compete with crops of water, light and nutrients
reduce the quality of a seed or grain crop
make cultivation difficult, tangling up tools and clogging up machines
can block drainage systems with excessive growth
can be a source of pests and diseases that also attack the crop
can look untidy, which might have an impact in tourism areas.
Controlling pests and diseases-
Pest is an animal that attacks or feeds upon the crop plant. A chemical used to control a pest is known as a
pesticide.
The most common pests of plants are insects. Chemical used to control insects is called an
insecticide.
Crop disease is caused by fungi, bacteria or viruses. These are known as
pathogens
.
Biological control- advantages
no chemical residues left in crop
no impact of spreads on the surrounding ecosystem
population control agent should increase and breed
when the pest has been controlled, lack of food will mean the predator will naturally reduce in numbers
no need to wear protective gear when applying the predator
Disadvantages
the control is not as instant as chemical control
climatic conditions means pests breed faster than the predator
predator might not stay on the crop and move elsewhere
predator might escape into local countryside and impact the natural ecosystem
Efficiency gains through mechanism
- Many crops are labour intensive to produce, availability of workforce limited the amount of land that could be cultivated. Using machines mean larger areas can be cultivated easily by one person. Power of machines means work like ploughing can take place when there is more water in the soil.
Selective breeding-
Improves the performance of crops and livestock.
Process:
identify which characteristics of the species are important
choose parents that exhibit these characteristics
raie the offspring from these paresnt
select the best offspring that show the desired characteristics
repeat the process
Controlling the crop environment-
Over very large areas it can be difficult or expensive to try and control the environment, although there are some important techniques.
providing shade for cattle so that they do not get hot
using windbreaks at the edges of crops to reduce wind speed and prevent damage to the crops
removing trees that shade a crop in order to maximise the light the plants receive.
Greenhouse- collective term for structures that support the controlled growth of plants.
3.1 Methods to reduce soil erosion
Terracing-
Prevents the erosion of soil by rainwater on steep slopes. When rainfall falls on a natural slope, it runs down the hillside due to gravity. The volume of water increases and so does the speed. Both of these factors dislodge soil, which is then carries within the surface run-off. When the speed of water decreases the soil particles will be deposited. Re-modelling the hillside into a series of terraces means that when heavy rain does occur it is less likely to run down a slope.
Contour ploughing
- Area of land is plotted there are benefits to ploughing so that the ridges and troughs run along the contours the land. Holds water back and prevents large torrents of water running down the slope, so preventing the formation of larger gullies and run-off of topsoil.
Bunds:
Artificial banks at the edges of growing spaces designed to hold back water. Useful for crops that need to be submerged at some stage or require very moist soils.
3.1 The Soil
Four main components that make up soil
Mineral particles
: combination of rock fragments and other smaller inorganic items
Organic content
: mixture of living plants and animals and their dead remains
Air
: held within the spaces between the particles and organic content of the soil
Water
: also held within the soil pores and is the water that is available for plants to grow
These particles come from
weathering
and
erosion
of the parent rock (rock underlying the soil) and over time these rocks are broken down into smaller and smaller particles (weathering). Movement of these fragments is known as erosion.
Paticle size
Sand:
largest mineral component of soil. Irregular shape means they do not pack together so there are large pores between the grains of sand; this allows water, air and soil organisms to move through sand easily.
Silt:
smaller then sand. Feels soapy and silky to touch and when rubbed between fingers the particles slip over each other easily.
Clay
: smallest mineral component. Small size means they pack together, which reduces the ability of water to drain through the soil. When damp, feels sticky and easily moulded; when dry they stick together solidly.
3.3 Agriculture
Factors affecting typed of agriculture
Climate
Culture
Technology
Economics
Types of agriculture
Subsistence vs commercial
Subsistence farming
is the cultivation and production of food to meet the needs of the farmers and their families. If there is any surplus it is often exchanged for their things the family needs, and perhaps a small amount of cash.
Commercial farming
is the cultivation of products with the main focus of selling them for cash. While some of the food may be used bu the farmers this is only a very small proportion compared with the amount that is sold. Commercial farms often use technology to increase yields to grow crops to obtain money to buy things they need.
Arable vs pastoral
Arable farming
is the production of plants for consumption by humans.
Pastoral farming
is the production of animals or animal-related products. This may also be known as livestock farming or grazing.
A third type of farming exists; farms that grow crops for food and rear animals. This is commonly referred to as
mixed farming.
Extensive vs intensive
Extensive production
occurs when there is a relatively small amount of production from a large area of land.
Intensive production
occurs where large amounts are produced from small areas of land. This style of production tends to have high 'inputs' such as a lot of labour, fertilisers or machinery.
3.6 Causes and impact of soil erosion
How top soil can be eroded
Removal of natural vegetation:
demand for land and once the soil structure is removed its not strong enough to withstand rainfall and flooding/run-off picks up topsoil.
Over cultivation:
start to lose soil structure. Ploughing or digging breaks up large clumps into smaller amounts makes smaller particles more vulnerable to erosion.
Overgrazing:
pressure means number of livestock can reduce the vegetation to ground level. Weakens plants because they do not have sufficient foliage to photosynthesise.
Wind erosion:
removal of vegetation makes the soil prone to being blown around by the wind.
Water erosion:
Heavy rainfall, rainwater run-off, gulley erosion- streams contain a volume of water moving at speed that erodes the local soil even further, forming deeper crevices.
Energy and the environment
2.1 Fossil fuel formation
Fossil fuels:
carbon-based fuels, formed over many millions of years ago from the decay of living matter.
Formation of oil and natural gas:
Small animals and plants die and fall to the bottom of the sea. Remains covered by sediment and as the sediment starts forming layers, they start to change into sandstone as the temperature and pressure increases. Heat and pressure turn the remains into crude oil and natural gas. They seperate and rise through the sandstone.
Formation of coal:
Vegetation died and forms peat. Peat is compressed between layers of sediment. Further compression formed coal.
2.2 Energy resources and the generation of electricity
Why demand is increasing
Increasing population size
Increasing industrialisation and urbanisation
Improvements in standards of living and expectations
Non renewable resources:
An item or resource that exists in a limited amount that cannot be replaced.
Fossil fuels (coal, oil and natural gas)
Nuclear power (using uranium)
Renewable resources:
An item or resource that will not be used up or can be replaced
Geothermal power
Hydro-electric power
Tidal power
Wav epower
Wind power
Solar power
Biofuels (wood, biogas, bioethanol)
How energy sources are used to generate electricity
Nuclear power:
Uranium releases high amounts of energy when nuclear fission (splitting of the atom) occurs. This energy is used to heat water, produce steam, and rotates the turbines.
Geothermal power:
Cold water is pumped under pressure into a layer of hot rocks. Rocks heat the water and theft water returns to the surface under pressure and heats the second supply of water using a heat exchanger. Stems is produced in the second supply moves the turbine, generating electricity.
Wind power:
Have blades that rotate due to the wind. Breaks slow down or stop the rotor in wind conditions, preventing damage to the blade. As the turbine rotates, the generator produces electricity.
Solar power:
Bank of cells organised into solar panels produce a significant amount of electricity.
Tidal power:
Uses the natural rise and fall in the level of water in the area. When the levels drop, water is held back by a tidal barrage.
Wave power:
Also uses turbine and generator. Uses the smaller differences in water levels that are caused by wind
Hydro-electric power:
Uses a dam on a river to store water in a reservoir. Water is released from the reservoir that flows through the turbine, rotating it and the turbine then activates a generator that generates electricity.
Advantages and disadvantages of fossil fuels
Advantages:
Plentiful supply
Provides job opportunities
The technology used is well-known and the methods of extraction are well practiced
Disadvantages:
Carbon dioxide and toxic gases are released when burnt; contributes to global warming
Damages local area
Limited supply
Advantages and disadvantages of fuel types
Biofuels:
Advantages:
Renewable source
Growing more plants uses carbon dioxide
Plentiful supply
Disadvantages:
Carbon dioxide and toxic gases are released when burnt
Lot of land needed
Removal of natural ecosystems
Nuclear power:
Advantages:
Does not produce carbon dioxide
Large amount of energy produced with a small amount of fuel
Provides job opportunites
Disadvantages:
Risk of radiation leakage
Radioactive waste cannot be recycles
Limited supply
Geothermal power
Advantages:
Does not produce carbon dioxide
Unlimited supply
Disadvantages:
Expensive to install
Only certain areas have suitable conditions
Wind power:
Advantages:
Does not produce carbon dioxide
Renewable
Disadvantages:
Only certain locations are suitable
Generation of electricity is weather-dependent
Visual impact
Uses a large area
Solar power:
Advantages:
Does not produce carbon dioxide
Disadvantages:
Weather dependent
Tidal power:
Advantages:
Does not produce carbon dioxide
Tidal movements are not weather-dependent
Disadvantages:
Limited to specific areas
Impact of tourism and local fisherman
Hydro-electric power:
Advantages:
Does not produce carbon dioxide
Water can be reused
Disadvantages:
Dams impact the natural flow of water
Villages and ecosystems may be destroyed
2.3 Energy demand
Domestic demand:
Created by affordability, availability and social status.
Most purchases that are considered as necessities now increase the demand for energy supplies.
Industrial demand:
Manufacturing requires the use of large amounts of energy throughout the production
Advanced manufacturing techniques made the products, that were once luxury items, cheaper so more people buy them, demand for the product increases, demand for energy also increases
Transport:
Manufactures supply customers across the globe.
This decreases production costs in countries that import, but increases the transport costs as they require large amounts of fossil fuels to operate
Personal and national wealth:
If economic conditions are good:
higher employment
more money to spend on luxury items
increase in demand for the product
increase in demand for energy
If economic conditions are poor:
families have less money to spend on luxury items
need to make savings
reduce the use of fuel
reduce the purchase and use of electrical items
decrease in the demand of energy
Climate:
demand for energy with regard to climate depends on the country
people living in a temperate climate are likely to experience colder winters, so energy demand for heating would be higher. Also experience fewer hours of daylight which increases the usage of electrical lighting.
Climate change increased the energy consumption. Need for additional heating and installation and operation of air-conditioning units.
2.4 Management of energy sources
Strategies for the efficient management of energy resources:
Insulation:
constructing using material with good insulation properties prevents loss of heat.
Double glazing:
two panes of glass with a gap in the middle to act as an insulator
Laws passed by a government to make changes rapidly:
Stricter building regulations:
New constructions must be more energy efficient
Preventing the sales of inefficient types of electrical devices
Incentives to encourage the purchase of more efficient technologies:
Insulating older houses that are energy efficient
Replacing older, inefficient electrical devices
Scrapping older, inefficient cars, that emit more pollutants
Transport policies:
Regulations regarding the quality of exhaust gases from vehicles
Restrictions on where vehicles may go
Taxation on fuels
Improving public transport so it is easier and cheaper than using cars
Improving routes for cyclists and pedestriand
Encouraging car-sharing
Developing of new resources
Fracking: Obtaining oil or gas from shale rock by splitting them open using water, sand and chemicals.
A vertical hole (2-3km deep) is drilled to reach the shale rock. Water, sand and chemical are pumped down into the shale rock layer. This causes the rock to fracture, releasing oil and natural gas, which are forced back to the surface and collected.
Advantages:
access to more oil and gas
less pollution than burning coal
need to import reduces
provide many jobs locally
Disadvantages:
risk of toxins entering the water table
chemicals are toxic and may affect local residents
uses lots of water
noise pollution
natural areas damaged
2.5 Impact of oil pollution
Phytoplankton-
Oil floats on the surface of the water and blocks the sunlight from entering. Phytoplankton cant photosynthesise, so they die.
Fish-
Shortage of food because of the death of phytoplankton. Fish become short of oxygen and die.Oil affects their gills.
Reefs-
Complete devastation of the reef due to lack of oxygen.
Beaches-
Oil coats rocks. Organisms in shallow water and rock pool may die due to toxic effects of the soil. Animal food sources and tourism are affected.
2.6 Management of oil pollution
Reducing oil spills in making environments
MARPOL (Marine Pollution)
Regulations of the MARPOL
Supervise the transport of oil at sea
all tankers must be certified to show they have appropriate systems in use
can result in heavy fine or the ship may not be permitted to leave port
Tanker design
Oil spill can be caused by damage to the hull
- increase in the number of compartments within the hull of the ship:
if one of the compartment's damaged, the contents of the whole ship aren't lost.
- Double-hulled tankers:
if the outer layer is damaged, the contents are still secure by the inner plate.
Minimising the impact of oil spills
Floating booms:
floating barrier is used to surround the oil slick, preventing if from spreading. This process works well when the soil covers a relatively small area and the sea is calm
Detergent sprays:
detergents help break down the oil slick into smaller droplets, that eventually degrade, and disperse it. Effective on smaller spills, cause damage to coral reefs
Skimmers:
clean the water using a material that oil easily attaches to. Drags oil off the seawater surface, that is then scrapped off into a container. When sea is calm.
Natural ecosystems and human activity
9.1 The ecosystem
Ecosystem structure:
Population:
all the organisms of one species living in a defined area.
Community:
group of populations of different species that live together in an area and interact with each other.
Abiotic:
non-living comonponets of the environment that may affect living things.
Biotic:
living components of the environment that may affect other living things.
Ecosystem:
all the living things together with the non-living things in an area.
Habitat
- place within an ecosystem where an organism lives.
Niche
- role of a species within the ecosystem.
Abiotic factors:
Temperature
- living things have a range of temperatures within which they can survive.
Humidity
- measure of how damp the air is, some living things cannot survive in dry air.
Water
- essential for life, raw material for photosynthesis and chemical reactions.
Oxygen
- not soluble in water so al aquatic organisms have adaptations, plants with roots in waterlogged soil have adaptations.
Salinity
- how salty something is, mains effects aquatic animals.
Light
- essential for photosynthesis.
pH
- measure the acid or alkaline of water.
Ecosystem process:
Producers:
organisms within an ecosystem that can carry out photosynthesis.
Herbivore:
primary consumer, eats plants and producers.
Carnivore:
secondary and tertiary consumer.
Primary consumer:
organisms that derive food from producers.
Secondary consumer:
organisms that derive their food from primary consumers.
Tertiary consumers:
organisms that derive their food from secondary consumers.
Decomposers:
organisms that derive their food from bodies of dead organisms.
Biotic interactions
Competition:
Living things need a range of resources from the environment, including other living and non living things. Many more young are produced than will survive, often more competition for resources.
Predation:
One animal eating another.
Pollination:
Male gametes swim through aqueous environment to get to the female gamete.
Energy flow:
glucose + oxygen --> carbon dioxide + water
Energy used for the processes the plant needs such as transporting food and making proteins, and given off into the environment as heat. 10% of the energy is fixed from sunlight by the plant. 90% energy lost 10% passed on.
9.2 Estimating biodiversity in ecosystems
Sampling: quadrants and transects
A= abundant C= common F= frequent O= occasional R= rare
Quadrant is a fram of known area that can be placed over part of the site to be sampled. Gridded quadrant is to count the number of squares that the plant appears in and take the total percentage cover.
Placing the quadrant:
Quadrant should be placed randomly in each two areas, called random sampling. Aim to see how the species change alone a gradient in the environment, the quadrant should be placed along a line (transect), called systematic sampling.
Sampling mobile organisms:
pitfall traps and pooters:
Porter is a simple piece of equipment getting animals out of the net and into a specimen container. For larger animals other traps can be used or from an aeroplane.
When to us systematic sampling:
If the investigation is looking at how distribution changes over an environmental gradient, systematic sampling will be used. If your investigation requires u to compare areas, then random sampling using a grid is the most suitable method.
9.3 The causes and impacts of habitat loss
The drainage of wetlands: Causes
Drainage for agriculture
Dredging for flood portection
Use of disposal of waste created by road construction
Discharge of pollutants
Peat removal
Removal of groundwater
Intensive agricultural practices:
Agriculture poses the greatest threat to species survival because of the habitat loss. Agrochemicals used are soluble in water and cane carried away from farms where they are applied.
Deforestation:
Climax community - stable community characteristic of an area that persists as long as the climate does not change. In these areas trees from continuous cover provide habitats for a wide range of species.
Loss of biodiversity and genetic depletion:
Artificial selection hugely beneficial in providing food for a growing population. Modern strains of crop plants may not be able to adapt to changes in the future, such as climate change. Important to retain biodiversity in projects.
9.4 The causes and impacts of deforestation
Causes of deforestation:
Major cause of habitat loss. Most obvious cause is the need for wood. Timber needed in MEDC's for products in luxury furniture.
Another reason for deforestation is to clear land for farming, roads or settlements. If economic deposits are found, rock and mineral extraction may occur, leading to future deforestation.
Impacts of deforestation:
Habitat loss:
Tropical rainforests have lots of biodiversity, so loss of habitat is very serious and the huge volume of trees act as massive carbon stores and they are home to many species.
Soil erosion and desertification:
Forest reduces the impact of heavy rainfall on the ground, reducing soil erosion. Tree roots hold the soil in place and the layer of fallen leaves and branches protects the soil.
Climate change:
Consistent change in long-term weather patterns. Caused by changes in the levels of various greenhouse gases un the atmosphere.Main gases are carbon dioxide and methane. Currently they are rising and atmospheric temperatures are too. Trees remove carbon dioxide from the atmosphere and deforestation reduces the number of trees, which reduces how much carbon dioxide the Earth's forests can move.
9.5 The need for sustainable management of forests
Carbon sinks and carbon stores:
When a forest is growing because trees are young, takes more carbon dioxide in photosynthesis than it gives out in respiration, so it is a carbon sink. Mature forest in which all of the trees are old and not growing actively, takes in and gives out the same quantity of carbon dioxide and is a carbon store.
Role in the water cycle:
Forests add water to the atmosphere in transpiration. Leads to the formation of clouds which release the water back as precipitation. When forests are cut down, this process is reduced, which can lead to local droughts in the area of deforestation. Forests generate moisture in the atmosphere that can also affect rainfall around the world.
Prevention of soil erosion:
By intercepting rain, the forest reduces heavy rainfall on the forest fall, this reducing soil erosion.
Debris such as tree leaves on the floor of the forest slows run-off, again reducing soil erosion.
The roots of trees hold soil in place.
Forests on the coast reduce erosion by absorbing energy from storms.
Ecotourism:
Responsible travel to a natural area that promotes conservation of the environment. Visitors travel with the aim go appreciating its natural beauty. Reason to manage forests sustainably and a method by which this can be achieved.
9.6 Strategies for conserving the biodiversity and genetic resources of natural ecosystems
Sustainable harvesting of wild plant and animal species, sustainable forestry and agroforestry:
Many plants have medicinal properties because of the secondary metabolites they produce. Many attempts to control the harvesting of wild-grown medicinal plants, involving a management plan.
In forestry selective logging is used where it removes only the mature trees of the species that are of value. Immature trees of the value species are left, allowing the forest to repair itself.
Agroforestry is a land management system in which crops are grown around trees. Trees enrich the soil when the leaves fall, provide food for animals and firewood for people.
National parks, wildlife and ecological reserves and corridors:
Once an area has been designed as a national park, it should be protected from damage. Laws usually implemented that ban or limit activities such as hunting and logging. Sometimes its difficult to stop these activities and enforcement can require a combination of regular inspection and the threat of fines or imprisonment for breaking the law.
Extractive reserves:
Attempt to balance between destroying the forest for short-term benefit and stopping all economic activity, which can have an impact on local people. Rainforests preservation is linking to the necessity of ensuring justice and opportunities for the people who live there.
World biosphere reserves:
Another way of trying to strike a balance between conservation while at the same time meeting peoples' needs. Buffer zone is an area where more research is carried out. The transition zone is where local communities and conservation organisations work together to manage the area for the benefit of the people who live there.
Rocks and minerals in their environment
1.1 Formation of rocks
The Rock Cycle:
representation of the changes between the three rock types and processes causing them.
Types of rocks
Igneous:
Made when liquid magma cools to form solid rock. Molten rock below surface is called magma, and lava when it reaches the surface.
Extrusive igneous rock: if the rock cools quickly, small crystals are formed e.g. basalt.
Intrusive igneous rock: if the rock cools slowly, large crystals are formed e.g. granite.
Sedimentary:
Formed by the weathering of existing rocks at the Earth's surface. Fossils may be present. Sediments accumulate into layers and get pressurised due to the newer deposits above them. The sediments are transported by water and wind (erosion). Particles like clay, silts, sands, gravels and small boulders are found in sediments. E.g. limestone, sandstone, shale
Metamorphic:
Formed from existing rock when heat and/or pressure causes changes in the rock crystals without melting it. The changes can be physical, chemical or both. E.g. marble and shale.
1.2 Extraction of rocks and minerals from the earth
Exploring from minerals:
Prospecting:
process of searching for minerals by examining the surface of the rocks.
Remote sensing:
process in which information is gathered about the Earth's surface from above. Photographs of the area are taken from air. Images are carefully analysed for mineral presence. Aerial photography can cover more ground than a person on the surface.
Radiation detection:
Mineral deposits are weathered at the Earth's surface, forming mineral oxides. Detected bu their unique radiation pattern.
Satellite signals:
Some satellites send signals to the Earth's surface and collect the reflected signals, indicating the presence of minerals. Systems work in all weather conditions.
Geochemical analysis:
Analysing the chemical properties of rocks. Samples can be taken from stream sediments, soil or rocks. Location of the sample points can be accurately found using GPS.
Geophysics:
Method to identify mineral ores present in rocks using their physical properties. Series of vibration are sent through the Earth's surface. Sensors are placed at different distances from the source of vibrations on the surface. Vibrations create shock waves that travel down into the rock layers. Reflected back to the sensors on the surface. Shock waves record different patterns depending on the mineral present in the rock layers.
Methods of extraction:
Surface mining:
includes open-cast and strip mining.
Open-pit mining
is used when a valuable deposit is located near the surface. Vegetation and top soil is removed. Rocks are broken up using explosives. Loose rock is removed using diggers.
Strip mining
is used to mine a seam of mineral. Overburden is removed as a thin strip. Mainly used to mine coal.
Sub-surface mining:
includes
deep and shaft mining
Vertical shaft is sunk down to the rock later containing minerals. Horizontal tunnel is made, following the mineral later. minerals are extracted by digging and loose rock is brought from the mine and poled up on waste heaps. Minerals are brought to the surface and transported in trucks or trains.
Decision making
Factors affecting rock and mineral extraction
Costs of exploration and extraction-
Fewer technical difficulties of mining on a large scale using open-pit mining as there'd be low extraction costs per tonne. Shaft mining is costlier to set up and maintain as the cost per tonne will get higher.
Geology-
High-grade ores yield of the required chemical elements than low-grade ores. Small deposits of high-grade ore are worth mining. Small deposits of low-grade ore that cannot be mined as a profit are left as reserves.
Accessibility-
Transporting the ore from the mine to processing plants can be difficult and expensive. Cost of building road to processing plant or nearest port for export is to be considered. Mining company must be given a license. Long term-agreement between government and mining company must be reached to avoid rapid rises in tax.
Environmental impact assessment-
For a license application to be approved, the company must have a plan to keep the loss of habitat minimal and restoration of land proceeding the completion of the mining.
Supply and demand-
Increase in world demand for any mineral ore will elevate the prices. Profit form working mines depends on changes in supply and demand. If demand is too high, mines that were not profitable before become worth mining. If demand falls, working mined may get into a loss due to the transport and extraction expenses.
1.3 Impact of rock and mineral extraction
Environmental factors:
Ecological impacts:
Loss of habitat as the vegetation is cleared, plants do not have a place to grow, so the animals depending on them for food and shelter are affected. After deep mining has been working for several years, more habitats will be destroyed due to the increased overburden aboveground.
Pollution:
Noise pollution:
due to machinery and explosives, disturbs the behaviour of animal species and causes hearing problems for people.
Water pollution:
water supplies may also be polluted, making it unsafe for people to drink. Water may become acidic and dissolve toxic metal ions-this combination kills many aquatic organisms.
Bioaccumulation:
organisms absorb the ions and retain them in their body, reaching concentration higher than that in water.
Biomagnification:
the concentrations increase higher up in the food chain and cause the death of top consumers.
Land pollution:
toxic nature of the waste doesn't allow plant growth even years after the mining is stopped.
Air pollution:
dust particles settle on the vegetation, not allowing sunlight to reach the leaves and thus, reducing the rate of photosynthesis.
Visual pollution:
landscape is damaged.
Economic impacts:
Provides employment for people and taxes for the government
.
Jobs are created directly to extract the mineral; further jobs are created to supply transport and mining equipment.
More jobs created when mineral is refined to make products; generate more income when activity occur in the same country.
The income earned can be used for buying goods and services and investing in infrastructure projects.
Improvements to transport; improvements to services e.g. healthcare and education. Services can be helpful for miners and their families. Investing in infrastructure projects can help the country in building more well-designed communities.
1.4 Managing the impact of rock and mineral extraction
Safe disposal of mining waste:
Mine waste must be stored to prevent collapse. Sit of the mine must precent the chances of water pollution.
Land restoration
Soil improvement:
After landfilling, mine waste can be covered by a layer of soil, can be enriched in fertilisers.
Tree planting:
After improving the soil fertility, plants and trees can be grown in that area, helping an ecosystem to be reborn.
Bioremediation:
Process of removing pollutants from waste using living organisms.
In-situ-
treatment of contaiminated waste where it's left
Ex-situ-
removal of contaminated waste form a site to a treatment plant. Often slow.
Making natural reserves:
Several tree and herb species introduced, as populations grow they create habitats for many species, nature reserves become valuable green spaced for human recreated and help in maintaining biodiversity.
Using as landfill sites:
Landfilling:
waste is tipped into a hole; levelled off and compacted from time to time.
Sanitary filling:
the waste is used to fill a hole, but alternating layers of waste and sand are used.
1.5 Sustainable use of rocks and minerals
Sustainable resource:
resource that can be continuously replenished
Sustainable development:
meets the needs of the present, without compromising the ability of future generations to meet their own needs.
Strategies for the sustainable use of rocks and minerals:
Increasing the efficiency of the extraction of rocks and minerals:
Mine wastes must be processed for the second time. This allows the valuable minerals to be recovered and reduces the risk of pollution due to mine waste.
Chemical treatment of the waste and biological treatment extracts much of the valuable mineral still within it.
Improvements in the performance of the machines used in mining and processing.
Greater use of data analysis by computers.
Increasing the efficiency of the use of rocks and minerals:
Engineering solutions e.g. design steel beams with same strength but using less steel.
The need to recycle rocks and minerals:
Recycling uses less energy than processing the ores.
Recycling also produces less waste and thus, reduces the risk of pollution.
Legislation:
The governments pass laws that require manufactures to become responsible for recycling and reuse.
Atmosphere
7.2 Atmospheric pollution and its causes
Short-wave radiation:
incoming or short-wave solar radiation, visible light and ultraviolet radiation.
Long-wave radiation:
outgoing or terrestrial radiation, as the Earth produces very visible light or ultraviolet radiation, all radiation from the Earth is infrared.
Primary pollutant:
emitted directly from the source.
Secondary pollutant: forms through chemical reactions with primary pollutants.
Photochemical smog:
air pollution in the atmosphere accompanied by high levels of ozone and nitrogen oxides from vehicles and caused by the action of sunlight on the pollutants.
Volatile organic compounds (VOC's):
chemicals that easily enter the atmosphere as gases, mainly from evaporation.
Acid rain:
Precipitation with a pH value of less than 6. Acidity results from burning fossil fuels in factories and power stations, which release sulphur dioxide and nitrogen oxides into the atmosphere. Dry deposition is vehicle emissions that add further nitrogen oxides. If these gases mix with water vapour and oxygen in the atmosphere, weak solutions of nitric and sulphuric acids are created, which can them be moved bu winds. Solutions fall to Earth as acid rain and is called wet deposition.
Ozone depletion:
Ozone layer exists becuase oxygen filtering from the top of the troposphere reacts under the influence of ultraviolet radiation to form ozone. Screens the Earth from the Sun's harmful radiation. As ozone
depletes
in the stratosphere, it forms a 'hole'. Hole allowed harmful ultraviolet radiation to enter the Earth's atmosphere. Clouds form from tiny ice particles in the intense cold, and on their surfaces chemical reactions involving CFC's take place, releasing chlorine, which reacts with the oxygen in the ozone layer.
The enhances greenhouse effect:
Greenhouse gas:
human activities that increase their abundance.
Carbon dioxide:
burning fossil fuels, deforestation.
Methane:
Cattle and rice production, coal mine ventilation, deforestation and decomposition of waste.
CFC's:
aerosol sprays, fire extinguishers, refrigeration, air conditioning.
Nitrogen oxides:
vehicle exhausts, chemical fertilisers.
Tropospheric ozone:
chemical reactions involving nitrogen dioxides and unburnt fuel vapours.
7.3 The impact of atmpospheric pollution
Smog:
Irritation of eyes and throat, increasing respiratory diseases such as asthma, fine particles carried into the lungs leading to lung cancer, breathing difficulties. Ability of plants to make and store food through photosynthesis is reduced, growth, reproduction and general health of plants decline.
Acid rain:
Acidification of groundwater makes water undrinkable and can cause diarrhoea and stomach upsets, aluminium leached from the soil into the groundwater linked to dementia, limestone buildings are chemically weathered, crop yields decline. Trees affected as foliage dies, acidification of groundwater damaged tree roots, nutrients such as calcium are leached out of the soil, aquatic and animal life in lakes is poisoned and decreases as acidity levels increase.
Ozone depletion:
Higher levels of ultraviolet radiation causes sun burn, skin cancers, retina damage, immune system can be suppressed. Extra ultraviolet radiation inhibits the reproductive cycle of phytoplankton, could affect the populations of other animals, changes in biochemical composition makes some plant levels less attractive as food, melting ice sheets, glaciers and can lead to rise in sea-levels.
Climate change:
Damage to low-lying countries, warmer weather may mean farmers grow different crops and have longer growing seasons, increased droughts could lead to desertification, negative impact on certain economic activities.
7.1 The structure and composition of the atmosphere
Aerosoles:
sprays containing fine particles and/or droplets that become suspended in the atmosphere.
Temperature inversion:
when temperatures increase with altitude. High air pressure, calm conditions, valleys surrounding.
Thermosphere --> mesopause --> mesosphere --> stratopause --> stratosphere --> tropopause --> troposphere
The natural greenhouse effect:
Radiation emitted by Sun.
Some radiation passes through layer of greenhouse gases.
Earth absorbs radiation and heats up.
Earth emits radiation.
Greenhouse gases absorb outgoing radiation and atmosphere heats up.
7.4 Managing atmospheric pollution
International conferences
1979: Geneva Convention on Long Range Transboundary Air Pollution: Controlling and reducing air pollution across borders by international corporations.
1987: Montreal Protocol: Ban and controlled use of CFC's to slow down ozone depletion.
1992: Rio Earth Summit: Agreement Agenda 21 passed with aim to cut environmental pollution and conserve resources and wildlife habitat.
1997: Kyoto Protocol: Signed over 100 countries to cut carbon dioxide emissions by 5% compared to 1990 levels.
1999: Gothenburg Protocol: Aimed to reduce pollutants and levels of acid rain and tropospheric ozone.
2009: Copenhagen Conference: MEDC's and LEDC's agreed to limits on greenhouse gas emissions.
2015: Paris Climate Conference: 195 countries agreed to limit rise in global temperature which will cut carbon dioxide emissions by 40%.
Oceans and fisheries
5.1 The resource potential of the oceans
Food:
Most important resource that humans obtain from the oceans. Includes true fish, shellfish, sunfish and other animals that live in the sea. Main fisheries located on continental shelves because water is shallow there, so light can penetrate and there is more oxygen than further down.
Chemicals and building materials:
3.5% of seawater is made up of dissolved substances. Many materials in the oceans have been eroded from the land, where rain and wind break down rocks. Particles are dissolved and enter oceans via rivers. Salt, magnesium, gold, tin, titanium, diamonds.
Wave and tidal energy:
Energy in waves that break on the shores. If this energy can be harvested it would be to twice the present world production.
Tourism:
Diving, snorkelling, windsurfing and jet skiing are some activities oe there is simply sunbathing or dep-sea fishing. Whale watching increasingly more popular, whaling eventually got banned in the early 1980's that people began to see watching whales as an economic alternative to killing them.
Transport:
Ships ar ean important way of transporting people and goods. Pleasure cruises are still important in the economic sector and bulk freight is still transported from country to country on ships.
Potential for safe drinking water:
Water that is salty is not safe to drink because your body has to remove salt, which would require more water. Possible to derive safe drinking water from salt water by desalination.
5.3 Exploitation of the oceans: impact on fisheries
Overfishing of marine fish species:
Lack of growth is probably explained by overfishing. 75% if the world's marine fisheries are threatened. Main reason for fishing used to be economic gain. Leads to fishery in which the number of fish caught is based on how many are available.
Yield from world fisheries has only remained constant because it has been possible switch to new species. Symptoms of severe overfishing are a reduced catch at the same time as an increased fishing effort.
Target species is not the only casualty of overfishing. When fish are caught commercially, the wrong species, sex or individuals that are too small are caught, called bycatch.
Trawl nets:
catch all kinds of unwanted species and damage the seabed during their use.
Drift nets:
drift with the current and are not anchored.
Various kinda of seine net:
hang like a curtain in the water.
Dredge nets:
dragged along the seabed, dig into the seabed with teeth or water jets to catch shellfish.
Farming marine species:
Farming fresh-water fish, aquaculture, carried out for a number of years and are an important source of income and food.
Farming marine fish, mariculture, is generally more difficult. Issue is that species we prefer are carnivorous fish which means they are the top of food chains and require a range of other species to feed on.
5.4 Strategies fr managing the harvesting of marine species
Net types and mesh size and shape:
Some nets are banned in certain areas. If the mesh size is too small, net will catch juvenile fish and if this happens the number of fish available to grow to maturity and reproduce is reduced.
Agreement stated a minimum 40mm square-mesh cod end or a diamond-mesh size of at least 50mm should be used for trawling activities. Diamond shape matched fish more easily and for this reason a square mesh panel is often included in an otherwise diamond net.
Quotas:
One of the most important ways in which fisheries can be managed. Legislators, governments, set limits on how many and what type of fish can be caught. If they get it right, enough fish should be left to reproduce and replenish the fishery for the following season.
Closed seasons and protected areas:
Legislative bodies can also pass laws that can close fisheries down for a part of the year. Usually around breeding season to keep the population going.
5.2 World fisheries
Major ocean currents:
Surface currents - movement of the surface water of the sea in a constant direction. Prevailing wind - the direction from which the wind always blows in a particular area.
Finding the fish:
Phytoplankton make their own food through photosynthesis. This process requires light, water and carbon dioxide. Light is the limiting factor and water absorbs light energy and most ocean water has absorbed all of the sunlight by a depth of only 200m. This 200m deep zone is the euphoric zone. Below this photosynthesis will not happen which is why fish are found where the water is shallow, on continental shelves.
Managing natural hazards
6.1 What is a natural hazard
Most common classification is based on the cause of the hazard:
geological hazards, earthquakes and volcanic eruptions.
climatic hazards, droughts, tropical cyclones, floods.
Can also be based on:
magnitutde or intensity of the event
speed at which the event takes place
duration of the envent
frequency of the event
A
natural disaster
is when a natural hazard causes the damage and the people affected are unable to cope.
A
natural hazard
is a naturally occurring event that will have negative impact on people.
For a disaster to be entered into the database of the UN at least one of the following conditions must be met:
report of 10 or more people killed
report of 100 or more people affected
state of emergency declared by the government of the affected country
request by the relevant national government for international assistance
Impact of a natural disaster on a community will depend on the:
length of time people are exposed to the natural hazard
vulnerability of the people affected
people's ability to cope with the effects
6.2 What causes earthquakes and volcanic eruptions?
Fold mountains:
mountains created where two or more tectonic plates are pushed together, compressing the rocks and folding them upwards.
Plate tectonics:
theory that helps explain the formation of some of the important features on the Earth's surface and how the continents move.
Oceanic crust:
mainly made of basalt, thinner, denser, younger, it can sink and it continually being renewed and destroyed.
Continental crust:
mainly made of granite, thicker, lighter, older, it cannot sink.
Plate boundaries:
Constructive (divergent):
Two oceanic plates are pulling away from each other. Gap or weakness formed and magma from the mantle rises to the surface because on convection currents. Magma solidifies when contact is made with cold ocean water.
Destructive (converging):
Found between a continental place and an oceanic plate. Oceanic plate and a continental plate move towards each other and the denser, organic plate is forced down under the lighter, continental plate.
Subduction zone.
If two continental plates move towards each other, this is a
collision zone.
Conservative:
No plate is being created or destroyed. Plates are sliding past each other.
Characteristics of earthquakes:
Focus:
location under the Earth's surface where the earthquake originates.
Epicentre: point on the Earth's surface directly above the focus.
Richter scale: measure of the magnitude of an earthquake.
Liquefaction: process where loose sediments with a high water content behave like liquid when shaken by an earthquake.