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50 Cards in this Set
- Front
- Back
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How long does it take soil to form? |
30 cm / 10000 years |
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What are the 7 limitations to sustainable soil management? |
1: erosion 2: urban encroachment 3: nutrient removal 4: salinisation 5: contamination 6: water supply 7: population trends |
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Which human practices exacerbate erosion? |
Ploughing, deforestation, over grazing |
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What are some techniques for erosion prevention? |
Wind breaks, intercropping, contour ploughing, terracing, strip cropping, no till, plant cover |
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Why is urban encroachment a problem for soil? |
Economic and population growth is higher on more productive land |
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How can soil fertility be preserved? |
Crop rotation, fertiliser addition |
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How does salinisation occur? |
Poorly managed irrigation that allows water to evaporate quickly and leave behind salt, or irrigation with salty water |
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How can salinisation be combatted? |
Drimage, trees to reduce water table, use the right water, add Ca to displace Na |
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Which products contaminate soil? |
Pesticides, heavy metals, spills, acid rain |
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How can irrigation be sustainable? |
Match crops to the climate, drup irrigation, prevent evaporation |
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Why is food waste a problem in developing countries? |
Inadequate storage and long transport distances |
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Why are food crops vulnerable? |
90% of human food comes from 15 plant and 8 animal species which are susceptible to disease |
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Why is the future production of food a challenge? |
9 billion people by 2050, increased fertiliser and energy costs, changing climate |
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How is water distributed on Earth? |
2.6% is fresh, of which 22% is groundwater, 1% is lakes/rivers/biosphere, and the rest is ice |
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Why is groundwater important? |
25% of people depend on it for drinking water but it is easily contaminated and takes a long time to recharge |
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What is significant about the Waimakarir River? |
It's a braided river in the Canterbury plains that comes from the Southern Alps, and 10% of its water recharges groundwater |
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What is significant about the Ogalala aquifer? |
Sustains 15% of the wheat and 40% of the cattle of the US but has been half drained in 40 years which also leads to subsidence |
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What are some ways to prevent deaths from flooding? |
Stop banks, flood ways, detention Sams, building elevation, flood plain zoning, warning systems, hydro dams |
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Why did the Aral Sea in the USSR disappear? |
Cotton growing required high water use which diverted the Aral Sea's incoming water flow |
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Why is there a global trade in minerals? |
Because they are distributed unevenly across Earth |
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What is an ore? |
Rock that contains enough of a mineral to make mining profitable |
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What is a mineral reserve? |
Known deposits that are currently economical to mine |
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What is a mineral resource? |
Total resource including estimates of unfound and noneconomic deposits |
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What are the four ways minerals are deposited? |
Magnetic concentrations, hydrothermal processes, sedimentary processes, evaporation |
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What are the three steps of mineral utilisation? |
Exploration, extraction, refining |
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What is depletion time and why is it difficult to predict ? |
It is the estimated time for 80% of the known reserves to be depleted, but is difficult to predict due to - new reserves being found - substitutes being found - increased re-use and recycling - new extraction tech - cost of energy changing |
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What is peak oil? |
Predicted time of max oil production, developed by Hubbert in 1956 |
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What happens when the price of oil goes up? |
More exploration, unconventional sources, new tech, better energy conservation, substitutes explored |
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What are the types of coal in order of least to most value? |
Lignite, bituminous, anthracite |
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How long is coal likely to last? |
Over 1000 years at current consumption rates |
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Why is Southland lignite considered a potential coal resource? |
Large amount in a shallow easily accessed area, could displace imports of urea and fuel, security of supply |
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Where does geothermal heat come from? |
Radioactive decay and residual heat |
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What is the heat source of the Taupo Volcanic Zone? |
Magma |
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How much electricity in NZ comes from geothermal sources? |
22% |
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What are some environmental concerns of using geothermal energy? |
Reservoir draw down (land subsidence, natural Cl features die) and disposal of waste fluids that contain heavy metals and heat |
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How is nuclear energy released? |
Fission of a nucleus into smaller fragments |
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What are the main concerns behind nuclear energy? |
Accidents, wastes, security, cost |
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How does a photovoltaic cell work? |
Solar energy is absorbed through the flow of electrons |
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What is the global potential for hydro electric? |
15% |
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What are some sources of NZ wastewater? |
City sewage, dairy, meat, veg processing, pulp and paper, piggeries |
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What are the aims of treating wastewater? |
Preventing the spread of disease, water pollution, eutrophication, and oxygen depletion |
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What does primary treatment do? |
- Screens out big suspended and floating sediments which go to landfills or incinerators - Gravitational settling of grits which go to landfills and other solids go to sludge |
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What does secondary treatment do? |
Utilises microorganisms to decompose organic matter in order to remove BOD/COD and convert nitrate to nitrogen |
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Why are aerobic and anaerobic systems combined? |
Because aerobic organisms convert nitrogen compounds to nitrate which must then be converted by anaerobic organisms into nitrogen through the production of methane |
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What do clarifiers do? |
Remove microbial materials from treated wastewater |
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What are the 5 Rs? |
Reduce, re-use, recycle, recover, residual management |
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Why is recycling paper and plastic difficult? |
Paper can only be recycled to an inferior product and plastic cannot be recycled back into food grade products |
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What are the features of a sanitary landfill? |
Impermeable clay or plastic lining, runoff collected and treated, compaction, daily cover |
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Why are minerals not sustainably managed? |
They are a limited resource |
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What is the scientific method? |
1. Recognise a problem 2. Develop hypothesis 3. Experiment/test 4. Interpret data 5. Report in scientific literature |
