Unit 4 Earth Systems and Resources

Transcription

1 Unit 4 Earth Systems and Resources

2 The Earth s resources were determined when the planet formed.

3 The Earth s Layers Core- the innermost zone of the planet made of nickel and iron. Inner core (soild) & outer core (liquid) Mantle- above the core containing magma (thickest layer) Crust- the outermost layer of the planet. Continental (granite) and oceanic (basalt)

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5 The Earth s Layers Asthenosphere- the outer part of the mantle, composed of semimolten rock. Lithosphere- the brittle outermost layer of the planet that is approximately 100 km thick.

6 Major Features of the Earth s Crust and Upper Mantle Fig. 14-2, p. 348

7 Convection and Hot Spots The Earth is very hot at the center. This heat causes plumes of hot magma to well upward from the mantle. Hotspots- places where molten material from the mantle reach the lithosphere.

8 Theory of Plate Tectonics Plate tectonics- the theory that states that Earth s lithosphere is divided into plates, most of which are in constant motion.

9 Tectonic Plates

10 Pangaea 10

11 Consequences of Plate Movement Volcanoes- as a plate moves over a hot spot, rising magma forms a volcano.

12 Types of Plate Contact Divergent plate boundaries- when plates move apart from one another. Convergent plate boundaries- when plates move toward one another and collide. Transform fault boundaries- then plates move sideways past each other.

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14 Faults and Earthquakes Faults- a fracture in rock across which there is movement. Earthquakes- occur when the rocks of the lithosphere rupture unexpectedly along a fault.

15 Faults and Earthquakes Fault zone- large expanses of rock where movement has occurred. Epicenter- the exact point on the surface of Earth directly above the location where the rock ruptures. Richter scale- a measure of the largest ground movement that occurs during an earthquake. The scale increases by a factor of 10, so an earthquake of 7 is 10 times greater than an earthquake of 6.

16 Landslides may occur on hilly ground Liquefaction of recent sediments causes buildings to sink Two adjoining plates move laterally along the fault line Earth movements cause flooding in low-lying areas Shock waves Epicenter Focus Fig. 14-7a, p. 351

17 Tsunami Giant undersea wave caused by an earthquake, volcanic eruption or landslide Travel > 450 mph Tsunami wave may be 1m deep in ocean Becomes 30.5m high on shore Magnitude 9.3 earthquake in Indian Ocean Triggered tsunami that killed over 230,000 people in South Asia and Africa Detection of tsunamis Buoys in open ocean

18 The Rock Cycle Rock cycle- the constant formation and destruction of rock.

19 The Rock Cycle Igneous rocks- rocks that form directly from magma. Intrusive igneous- form from within Earth as magma cools. Extrusive igneous- from when magma cools above Earth. (ex. A volcano that ejects magma out will form this) Sedimentary rocks- form when sediment such as mud, sands, or gravels are compressed by overlying sediments. Metamorphic rocks- form when sedimentary, igneous or other metamorphic rocks are subjected to high temperatures and pressures.

20 Sedimentary Sediments from eroded rocks or plant/animal remains Transported by water, wind, gravity Deposited in layers and compacted Sandstone Shale Dolomite Limestone Lignite Bituminous coal 20

21 Igneous Forms below or at earth s surface from magma Granite Lava rocks Metamorphic Preexisting rock subjected to high pressures, high temperatures, and/or chemically active fluids Anthracite Slate Marble 21

22 Weathering and Erosion Weathering- when rocks are exposed to air, water, certain chemicals or biological agents that degrade the rock. Physical weathering- the mechanical breakdown of rocks and minerals.

23 Weathering and Erosion Chemical weathering- the breakdown of rocks and minerals by chemical reactions.

24 Erosion Erosion- the physical removal of rock fragments from a landscape or ecosystem. Wind, water, ice transport and living organisms can erode materials. Deposition- the accumulation or depositing of eroded material such as sediment, rock fragments or soil.

25 Soil Soil is important because it Is a medium for plant growth Serves as a filter for water A habitat for living organisms Serves as a filter for pollutants

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27 The Formation of Soil Factors that determine the formation of soil: Parent material- what the soil is made from influences soil formation Climate- what type of climate influences soil formation Topography- the surface and slope can influence soil formation Organisms- plants and animals can have an effect on soil formation Time- the amount of time a soil has spent developing can determine soil properties.

28 The Formation of Soil Parent Material- the rock material from which soil is derived.

29 Soil Composition Mineral Particles (45%) Weathered rock Organic Material (5%) Litter, animal dung, dead remains of plants and animals Water (25%) Air (25%)

30 Soil Properties 30

31 Soil Horizons As soils form, they develop characteristics layers. E Horizon Is heavily Leeched Soil

32 Soil Horizons O horizon- (organic layer) composed of the leaves, needles, twigs and animal bodies on the surface. A horizon- (topsoil) the zone of organic material and minerals mixed together. B horizon- (subsoil) composed primarily of mineral material with very little organic matter C horizon- (parent material) the least weathered horizon and is similar to the parent material.

33 Physical Properties of Soil Texture- the percentage of sand, silt and clay the soil contains.

34 Soil Properties Soil texture affects soil properties Coarse textured soil (sandy) Excellent drainage Fine textured soil (high in clay) Poor drainage Low oxygen levels in soil Due to negatively charged surface, able to hold onto important plant nutrients (K +, Ca 2+, NO 2- )

35 Soil Properties Affected by Soil Texture 35

36 Physical Properties of Soil Porosity- how quickly the soil drains (which depends on its texture)

37 Soil Properties Soil Acidity Measured using ph scale ph of most soils range from 4 8 Affects solubility of certain plant nutrients Optimum soil ph is 6 7, because nutrients are most available to plants at this ph

38 Chemical Properties of Soil Cation exchange capacity- the ability of a soil to adsorb and release cations, positively charged mineral ions. Soil bases- calcium, magnesium, potassium and sodium Soil Acids- aluminum and hydrogen Base saturation- the proportion of soil bases to soil acids

39 Biological Properties of Soil Many organisms are found in the soil including fungi, bacteria, protozoans, rodents and earthworms. 39

40 Soil Organisms Soil organisms provide ecosystem services Def: Important environmental benefits that ecosystems provide Examples Decaying and cycling organic material Breaking down toxic materials Cleansing water Soil aeration

41 Major Soil Groups Variations in soil forming factors cause variation in soils around globe Soil Taxonomy Separates soils into 12 orders Subdivided into more than 19,000 soil series that vary by locality Five common soil orders Spodosols, alfisols, mollisols, aridosols, oxisols

42 Spodosols Major Soil Groups Form under coniferous forests O-horizon composed of decaying needles E-horizon is ash - gray under A-horizon Not good farmland - too acidic

43 Alfisols Major Soil Groups Brown to graybrown A-horizon Precipitation high enough to leach most organics and nutrients out of O-, A- and B-horizons Soil fertility maintained by leaf litter

44 Mollisols Major Soil Groups Found in temperate, semi-arid grassland Very fertile soil Thick, dark brown/ black A-horizon Soluble nutrients stay in A-horizon due to low leaching

45 Aridosols Major Soil Groups Found in arid regions of all continents Low precipitation preclude leaching and growth of lush vegetation Development of salic horizon possible

46 Oxisols Major Soil Groups Found in tropical and subtropical areas with high precipitation Very little organic material accumulation due to fast decay rate B-horizon is highly leached and nutrient poor

47 Elemental Composition of the Earth s Crust 47

48 The Life Cycle of a Metal Resource Fig , p. 355

49 Reserves Reserves- the known quantity of a resource that can be economically recovered. 49

50 Important Minerals and Their Uses

51 Types of Mining Surface mining- removing minerals that are close to Earth s surface. Strip mining- removing strips of soil and rock to expose ore. Open pit mining- the creation of a large pit or hole in the ground that is visible from the surface. Mountain top removal- removing the entire top of a mountain with explosives. Placer mining- looking for metals and stones in river sediments. 51

52 Types of Mining Subsurface mining- mining for resources that are 100 m below Earth s surface. 52

53 Surface Mining 53

54 See the Trailer on The Last Mountain Standing 54

55 Formation of Mineral Deposits Result of natural processes Magmatic concentration As magma cools heavier elements (Fe and Mg) settle Responsible for deposits of Fe, Cu, Ni, Cr Hydrothermal processes Minerals are carried and deposited by water heated deep in earth s crust Sedimentation Weathered particles are transported by water and deposited as sediment on sea floor or shore Evaporation Salts are left behind after water body dries up

56 Negative Effects of Mining 80% or more of mined ore consists of impurities - called tailings Contain toxic materials Smelting plants emit large amounts of air pollutants Requires a lot of energy (fossil fuels combustion) 56

57 Natural Capital Degradation Extracting, Processing, and Using Nonrenewable Mineral and Energy Resources Steps Mining Exploration, extraction Processing Transportation, purification, manufacturing Use Transportation or transmission to individual user, eventual use, and discarding Environmental Effects Disturbed land; mining accidents; health hazards; mine waste dumping; oil spills and blowouts; noise; ugliness; heat Solid wastes; radioactive material; air, water, and soil pollution; noise; safety and health hazards; ugliness; heat Noise; ugliness; thermal water pollution; pollution of air, water, and soil; solid and radioactive wastes; safety and health hazards; heat Fig , p. 356

58 Environmental Impacts of Disturbs large area Prone to erosion Mining Uses large quantities of water Must pump water out of mine to keep it dry Acid Mine Drainage (AMD) Pollution caused when sulfuric acid and dissolved lead, arsenic or cadmium wash out of mines into nearby waterways

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60 Mine Tailings 60

61 Acid Mine Drainage 61

62 How to mitigate the issues with Remediation of lands mining Prevention is less costly than cleaning pollution Use Phytoremediation by using plants to trap pollutants Trap pollutants before get into streams and wetlands Recycle and reduce use of minerals that are in short suppy Invent new substances to replace minerals Change throw away attitude 62

63 Aluminum Cans Ready for Recycling Fig , p. 366

64 Solutions: Sustainable Use of Nonrenewable Minerals Fig , p. 366