3.2 The physical environment

The emphasis should be placed on understanding how anthropogenic activities are inter-connected with physical processes, to formulate management strategies and plan sustainable activities.

Supplies of renewable physical resources may be maintained by the control of activities that may cause over-exploitation and by protecting the processes that aid their production.

Supplies of non-renewable physical resources may be extended by controlling exploitation and developing improved technologies to harness them.

The atmosphere

How atmospheric energy processes involving ultra violet (UV), infrared (IR) and visible light in the stratosphere and troposphere affect life-support systems

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Additional information

Origins and roles of UV and IR in the atmosphere.

  • Insolation.
  • Emissions from the earth.
  • Thermal stratification.
  • Chemical processes.
How different wavelengths of electromagnetic light behave in the atmosphere:
  • transmission
  • absorption
  • conversion to heat
  • conversion to chemical energy
  • reflection.
 

Global climate change: how interconnected natural systems cause environmental change

Students should select, analyse and evaluate the data available on natural and anthropogenic climate change.

Content

Additional information

Greenhouse gases

The anthropogenic sources of greenhouse gases, residence times and relative effects: CO2, CH4, NOx, tropospheric ozone, CFCs.

Changes in oceans

Changes in thermohaline circulation in the North Atlantic.

Changes in ocean, wind and current patterns: El Niño.

Sea level rise.

Changes in the cryosphere

Reduced snow cover – amount and duration.

Glaciers: changes in extent and speed of movement.

Land ice caps and ice sheets: changes in thickness and movements.

Ice shelves: changes in the break-up of ice shelves and the impact on land ice movements.

Sea ice: changes in thickness and area of sea ice cover.

Changes in climate processes

Precipitation changes:

  • amount, duration, timing and location
  • changes in proportions of rain and snow.

Wind pattern changes: direction, velocity.

Difficulties monitoring and predicting climate change

Students should understand the limitations in the available data when attempting to predict future natural and anthropogenic climate change. They should be able to evaluate the reliability of existing information and discuss the methods that are used to fill gaps in current knowledge including remote sensing.

Students should be able to discuss the importance of accurate, representative data in climate modelling.

Uncertainty of ecological impacts of climate change:

  • changes in species survival caused by changes in abiotic factors
  • changes in species survival caused by changes in biotic factors
  • changes in species distribution
  • population fragmentation.

Why there is uncertainty over the use of some data in drawing conclusions.

  • Lack of historical data: atmospheric composition, temperature, weather patterns.
  • Limited reliability of proxy data.
  • Lack of understanding of natural processes that control weather, ocean currents and their interconnections.
  • How understanding is improved by climate modelling.
  • Natural changes and fluctuations that mask changes caused by anthropogenic actions.
  • Time delay between cause and effect.

Feedback mechanisms and tipping points

Impact of negative feedback mechanisms caused by:

  • increased low-level cloud
  • increased photosynthesis.
Impact of positive feedback mechanisms:
  • melting permafrost
  • ocean acidification
  • reduced albedo
  • melting methane hydrate
  • increased forest and peat fires
  • increased cirrus clouds
  • more rapid decomposition of dead organic matter in soil.

The role of tipping points in climate change.

Carbon footprints and sustainable development

Students should compare the per capita carbon emissions and carbon footprints for different countries to evaluate different strategies to achieve sustainable development.

How the control of greenhouse gases may help achieve sustainable lifestyles.

Ozone depletion

Students should consider the success of tackling ozone depletion and compare this with other environmental issues.

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Additional information

The study of ozone depletion should be used as an example of an environmental issue where all the stages of scientific investigation are present.

  • Identification of an environmental issue.
  • Formulation of a hypothesis.
  • Collection, analysis and evaluation of data.
  • Proposal for solutions.
  • Enactment of solutions.

Rowland-Molina hypothesis

The properties of chlorofluorocarbons (CFCs) that lead to stratospheric ozone depletion.

  • Persistence of CFCs.
  • Dissociation by UV.
  • Reactions of chlorine with ozone.

Effects of ozone depletion.

Why increased UV(B) reaching the Earth’s surface may cause problems:

  • human health
  • damage to plants
  • damage to marine organisms.

Collection, analysis and interpretation of data, an evaluation of data collection methods available and the reliability of data produced

The collection of data on ozone depletion:

  • ground-based data collection
  • aerial/satellite surveys
  • variability of results: spatial, temporal, altitude.

Why ozone depletion has been greatest over Antarctica

Unusual atmospheric conditions over Antarctica:

  • very low temperatures
  • ice crystals
  • stratospheric clouds
  • polar vortex winds.

The restoration of the ozone layer

Main features of the Montreal Protocol (on Substances that Deplete the Ozone Layer) (1987):

  • use of alternative processes
  • use of alternative materials
  • collection and disposal of CFCs and other ozone-depleting substances (ODSs).

Evaluation of the effectiveness of the methods used to restore the ozone layer compared with the effectiveness of tackling other atmospheric pollution problems

An analysis of the evidence for changes in area of ozone depletion, ozone concentrations and UV levels.

A comparison with the effectiveness of tackling climate change.

Opportunities for skills development and independent thinking

Mathematical skill number Opportunities for skills development and independent thinking
MS 0.2 Students could use standard form when dealing with carbon reservoir masses and transfer rates.
MS 1.3 Students could plot atmospheric carbon dioxide levels, atmospheric temperature and solar output over time represented on a graph.
MS 1.4 Students could consider probability when assessing the various possible causes of climate change.
MS 1.10 Students could use standard deviation values to assess the significance of fluctuations in ozone levels over Antarctica.
MS 1.11 Students could calculate the percentage difference between estimated values and real outcomes from computer models of global climate change.
MS 2.2 Students could use and manipulate an equation to estimate carbon sequestrian rates.
MS 3.1 Students could construct a flow diagram of carbon reservoirs and transfer processes in the carbon cycle.
MS 3.4 Students could use data on different scenarios of carbon emissions to predict a graph of atmospheric CO2 concentration.

Working scientifically

Students could plan activities in a range of environmental contexts related to the atmosphere, including ones where first hand experience of practical activities may not be possible.

Practical skill number Opportunities for skills development and independent thinking
PS 1.2 Students could analyse the reliability of past data collected on ozone depletion.
PS 1.4

Students could plan how to collect representative data on changes in flow in the North Atlantic Conveyor.

Students could plan how to collect data on UV levels in Antarctica to monitor the recovery of stratospheric ozone.

PS 2.1 Students could assess the reliability of using proxy data to monitor climate change.
PS 2.2 Students could assess uncertainties over predictions of sea ice loss, changes in atmospheric temperature and sea level rise.
PS 3.1 Students could construct graphs on changes in factors related to climate change: land ice volume, sea ice area, atmospheric CO2 concentration.
PS 3.3 Students could assess degrees of uncertainty of data collected on climate change and predictions of changes that will occur in the future.

Opportunitites to investigate the required methodologies of which students must have first hand experience. Further details can be found in Appendix A: Working scientifically

Methodology skill Opportunities for skills development and independent thinking
Me 2 Students could plan the location of temperature sampling sites and timing to produce reliable data on climate change.

The hydrosphere

The impact of unsustainable exploitation

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Additional information

Students should understand that the natural hydrological cycle is in a state of dynamic equilibrium. Human activities that alter the rates of processes in the hydrological cycle can lead to changes in residence times and quantities in the reservoirs of the cycle.

Students should be able to use the technical terminology related to the hydrological cycle to discuss anthropogenic changes and strategies that may allow sustainable exploitation.

Students should be able to explain how human activities change processes in the hydrological cycle.

Students should be able to explain the consequences of changes in the hydrological cycle.

 

Analysis and evaluation of strategies for sustainable management

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Additional information

Students should use examples of water resources that have been exploited unsustainably.

 

Ocean currents: the importance of thermohaline circulation in distributing heat and regulating climate

Content

Additional information

Students should discuss the impacts of changes in thermohaline circulation on the climate of countries around the North Atlantic, including the UK.

 

Increasing sustainability by treating contaminated water

Content

Additional information

The methods used to remove the following contaminants:
  • litter
  • suspended solids
  • some metals and odours
  • organic pollutants
  • salt
  • pathogens.
 

Increasing sustainability by economical use and the exploitation of new sources

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Additional information

Management of water resources:

  • metering
  • low water-use appliances
  • greywater use
  • exploitation of new sources
  • rainwater catchment
  • new reservoirs/estuary barrages
  • unexploited aquifers
  • inter-basin transfers.
 

Opportunities for skills development and independent thinking

Mathematical skill number Opportunities for skills development and independent thinking
MS 0.1 Students could convert data and change the units used in transfer rates, volumes and residence times in the hydrological cycle.
MS 0.4 Students could estimate results to sense check that the calculated values are appropriate, such as when calculating residence times in different water reservoirs.
MS 1.2 Students could calculate the mean rate of water transfer between two water reservoirs.
MS 1.3 Students could interpret data relating to aquifer flow rates.
MS 1.6 Students could use data on changing transfer rates to calculate changes in the mean water content in an aquifer.
MS 1.7 Students could analyse a scatter graph of per capita water use against mean GDP to suggest reasons for different rates of water use.
MS 1.8 Students could make order of magnitude calculations using data on per capita and national water use.
MS 3.1 Students could construct a flow diagram using data on processes and reservoir storage.
MS 3.6 Students could calculate the rate of infiltration into rocks of different permeabilities.

Working scientifically

Students could plan activities in a range of environmental contexts related to the hydrosphere, including ones where first-hand experience of practical activities may not be possible.

Practical skill number Opportunities for skills development and independent thinking
PS 1.2 Students could analyse data on deforestation and precipitation levels.
PS 1.4 Students could plan monitoring programmes for the salinization of aquifers.
PS 2.1 Students could analyse results of previous studies on catchment area changes and difficulties in producing representative data.

Mineral resources

Minerals extracted from the lithosphere

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Additional information

The mineral resources extracted from the lithosphere are non-renewable as they are reformed too slowly to be replaced within timescales that would allow human use. Long-term use relies on an understanding of the scientific methods that will increase supplies, extend use and find alternatives for those in restricted supplies.

Students should understand the importance of resources extracted from the lithosphere on society.

  • Metals and metal ores.
  • Industrial minerals.
  • Construction materials.

Geological processes that produced localised concentrations of recoverable mineral deposits

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Geological processes
  • Hydrothermal deposition.
  • Metamorphic processes.
  • Proterozoic marine sediments.
  • Physical sediments.
  • Biological sediments.

Reserves and resource

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The reserves include the amount of material that can be exploited using existing technology under current economic conditions.

The resource includes all the material that could be exploited technically and economically now or in the future.

 
Lasky’s principle

As the linear purity of a deposit decreases, there is a logarithmic increase in the amount of the material that is included.

The ability to exploit low-grade deposits results in a large increase in the reserves.

How a range of exploratory techniques work

Students should understand the methods that are used to discover the localised concentrations of deposits produced by geological processes.

Content

Additional information

Exploratory techniques

  • Satellite imagery.
  • Seismic surveys.
  • Gravimetry.
  • Magnetometry.
  • Resistivity.
  • Trial drilling.

Factors affecting mine viability

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For a mining operation to be viable, a wide range of geological and economic criteria must be met.

  • Ore purity and cut-off ore grade.
  • Chemical form.
  • Associated geology: overburden, hydrology.
  • Economics: cut-off ore grade and mining costs.

Control of the environmental impacts of mineral exploitation

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Additional information

All mining activities impact on the environment, but good site management and post-mining restoration can minimise problems.

  • Turbid drainage water.
  • Spoil.
  • Leachate neutralisation.
  • Site management.
  • Site restoration.

Strategies to secure future mineral supplies

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Additional information

As high-grade deposits become depleted, it is important to develop new technologies to find and extract new deposits, including low-grade and less accessible deposits.

Manufactured products should be designed to minimise the amount of material needed and extend the lifetime of material use.

  • Improvements in exploratory techniques including remote sensing.
  • Bioleaching with acidophilic bacteria.
  • Phytomining.
  • Cradle to Cradle design.

Recycling

The advantages of recycling:

  • conservation of mineral resources
  • reduced energy use (of mineral extraction)
  • reduced mineral extraction/processing impacts
  • reduced waste disposal impacts.
  • Difficulties with recycling schemes
  • identification of materials.
  • Separation of mixed materials.
  • Reduction in quality.
  • Increased transport costs/impacts.
  • Collection difficulties.
  • Lack of consumer cooperation.

Opportunities for skills development and independent thinking

Mathematical skill number Opportunities for skills development and independent thinking
MS 0.5 Students could estimate the impact of a change in cut-off ore grade on the abundance of mineral reserves using the exponential trend of Lasky's principle.
MS 1.1 Students could demonstrate understanding that calculated results can only be reported to the limits of the least accurate measurement, eg in estimating lifetimes of mineral reserves.
MS 1.7 Students could analyse a scatter graph of per capita water use against mean GDP to suggest reasons for different rates of water use.
MS 1.8 Students could make order of magnitude calculations using data on per capita and national water use.
MS 1.11 Students could identify the uncertainties of predictions in mineral reserves using trends in population, per capita use and improvements in extraction technology.

Working scientifically

Students could plan activities in a range of environmental contexts related to the hydrosphere, including ones where first hand experience of practical activities may not be possible.

Practical skill number Opportunities for skills development and independent thinking
PS 1.2 Students could analyse trial core survey data to assess mine vaidity.
PS 3.2 Analyse metal ion concentration data in a mining area to identify the sources of contamination.

Biogeochemical cycles

The importance of biogeochemical cycles for living organisms

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Additional information

Many elements have low availability to living organisms. Biogeochemical cycles involve inter-linked processes that allow materials to be recycled and repeatedly re-used.

 

The carbon cycle including human influences

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Additional information

The processes in the carbon cycle that are affected by human activities
  • Photosynthesis.
  • Aerobic respiration.
  • Anaerobic respiration.
  • Combustion.
  • CO2 dissolving in the sea/exsolving from the sea.
  • Biomass movements.
  • Changes in carbon reservoirs.
  • Increased atmospheric concentration of CO2.
  • Less soil dead organic matter.
  • Increased concentrations of dissolved CO2, carbonic acid, hydrogen carbonate ions.
  • Increased atmospheric concentration of methane.
  • Reduced amount of carbon in plant biomass.
  • Reduced amount of carbon in fossil fuels.
Sustainable management of the carbon cycle: methods of counteracting human activities that alter the natural equilibria of the carbon cycle
  • Alternatives to fossil fuel use.
  • Carbon sequestration.
  • Carbon Capture and Storage (CCS).
  • Matching afforestation to deforestation.
  • Increasing soil organic matter.
  • Conservation of peat bogs.

The nitrogen cycle including human influences

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Additional information

The processes in the nitrogen cycle that are affected by human activities
  • The Haber Process fixing nitrogen in ammonia, mainly to produce agricultural fertilisers.
  • Land drainage increases nitrogen fixation and reduces denitrification.
  • The growth of legume crops increases nitrogen fixation in plant proteins.
  • Sewage disposal increases nitrate movements to rivers and the sea, together with phosphates, causes eutrophication.
  • Combustion processes cause nitrogen and oxygen to react, producing oxides of nitrogen.
  • Decomposition and ammonification affected by organic waste disposal policies.
  • Consequences of changes in nitrogen reservoirs.
  • Eutrophication.
  • Global climate change.
  • NOx toxicity.
  • Photochemical smogs.
Sustainable management of the nitrogen cycle and methods of counteracting human activities that alter the natural equilibria of the nitrogen cycle

Methods of counteracting anthropogenic nitrogen movements:

  • reduced combustion processes
  • use of natural nitrogen fixation processes instead of the Haber process
  • management of biological wastes
  • methods of reducing soil nitrate leaching.

The phosphorus cycle including human influences

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Additional information

The processes in the phosphorus cycle that are affected by human activities

Phosphorus compounds are mobilised in more soluble forms for use in agricultural fertilisers.

Eutrophication is caused by nutrient enrichment of water bodies, combined with the effect of nitrates.

Sustainable management of the phosphorus cycle and methods of counteracting human activities that alter the natural equilibria of the phosphorus cycle

The lack of abundant reservoirs of phosphates in the atmosphere or hydrosphere is often the limiting factor on biological productivity:

  • the use of biological wastes as fertilisers
  • breeding of crops that absorb phosphates more efficiently
  • providing suitable conditions for soil mycorrhizal fungi increases phosphate uptake combustion processes.

Opportunities for skills development and independent thinking

Mathematical skill number Opportunities for skills development and independent thinking
MS 0.1 Students could convert values and units used in transfer rates, reservoir mass and residence time in the nitrogen cycle.
MS 0.2 Students could convert numbers in standard and ordinary form when using masses in biogeochemical cycles.
MS 2.2 Students could use and manipulate equations of nutrient transfer rates.
MS 3.1 Students could use data on reservoirs and transfer processes to construct a flow diagram of the nitrogen or phosphorus cycle.

Soils

How human activities affect soil fertility

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Additional information

Activities that control soil conditions and affect fertility.

  • Aeration of soil by ploughing and drainage.
  • Addition of soil nutrients.
  • Irrigation.
  • Soil compaction, increasing bulk density.
  • pH control.

Causes of soil degradation and erosion

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Additional information

Types of soil erosion

  • Rain splash.
  • Wind blow.
  • Surface runoff.

Natural features that reduce erosion.

  • Vegetation.
  • Soil organic matter.
  • High infiltration rate.

The Universal Soil Loss Equation (USLE) can be used to estimate erosion rates.

 

Human activities that cause soil erosion and degradation.

  • Ploughing vulnerable soils.
  • Vegetation removal.
  • Overgrazing.
  • Reducing soil organic matter.
  • Reducing soil biota.
  • Cultivating steep slopes.
  • Soil compaction by machinery or trampling.

The environmental impacts of soil erosion.

  • Reduced productivity.
  • Sedimentation in rivers and reservoirs.
  • Downstream flooding.
  • Coastal sedimentation.
  • Increased atmospheric particulates.
  • Desertification.
  • Landslides.

Soil management strategies to increase sustainability

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Additional information

Methods that can be used to reduce soil erosion:

  • long-term crops
  • contour ploughing
  • tied ridging
  • terracing
  • windbreaks
  • multicropping
  • strip cropping
  • mulching
  • increasing soil organic matter.
 

Opportunities for skills development and independent thinking

Mathematical skill number Opportunities for skills development and independent thinking
MS 0.3 Students could use data on mass and mass change during heating to estimate the percentage water and organic matter composition of soil.
MS 1.1 Students could demonstrate appropriate numbers of significant figures in calculations of soil water and organic matter content.
MS 2.4 Students could use data and the Universal Soil Loss Equation to estimate rates of soil loss.
MS 3.2 Students could demonstrate their ability to use data presented in a number of formats and be able to use these data, eg soil erosion rates presented in graphs, tables and formulae.

Working scientifically

Students could plan activities to investigate environmental issues which they could carry out eg:
  • the impact of soil texture on soil water content
  • the impact of soil water content on organic matter levels
  • the effect of slope on rain splash soil erosion
  • the effect of vegetation cover on rain splash erosion
  • the impact of soil compaction on soil water levels.

Students could plan activities in a range of broader environmental contexts related to soils, including ones where first hand experience of practical activities may not be possible eg: the effect of soil erosion on downstream ecosystems.

Practical skill number Opportunities for skills development and independent thinking
PS 1.1 Students could plan a strategy to monitor and reduce soil erosion, within the context of global food supply problems.
PS 4.1 The practical skills of using equipment within scientific studies are expanded, as appropriate, in detail in the selected methodologies and sampling techniques below.

Opportunities to investigate the required methodologies of which students must have first hand experience. Further details can be found in Appendix A: Working scientifically

Methodology skill number Opportunities for skills development and independent thinking
Me 2 Students could mark out a transect across a field to investigate changes in edaphic factors down a slope or away from a hedge/field margin.
Me 3 Students could calcuate mean values of selected factor, eg water content, to find the number of samples required to calculate a reliable mean.

Opportunities to investigate the required sampling techniques of which students must have first hand experience. Further details can be found in Appendix A: Working scientifically

Sampling technique skill number Opportunities for skills development and independent thinking
ST 1 Students could investigate the effect of a hedgerow on the downwind wind velocity, in the context of soil erosion.
ST 3

Students could compare the water and organic matter contents of soil from fields with different long-term management systems.

Students could use sedimentation or soil sieves to compare the textures of soils from areas with different bedrocks.