Geology and Nonrenewable Mineral Resources Chapter 15 Geology and Nonrenewable Mineral Resources

GEOLOGIC PROCESSES The earth’s interior consists of: Core: innermost zone with solid inner core and molten outer core that is extremely hot. (Iron and Nickel) Mantle: solid rock with a rigid outer part (asthenosphere) that is melted pliable rock. Crust: Outermost zone which underlies the continents. (Silicon and oxygen SiO2)

Tectonic plate Inner core Spreading center Collision between two continents Oceanic tectonic plate Ocean trench Oceanic tectonic plate Plate movement Plate movement Tectonic plate Oceanic crust Oceanic crust Subduction zone Continental crust Continental crust Material cools as it reaches the outer mantle Cold dense material falls back through mantle Hot material rising through the mantle Mantle convection cell Figure 15.3 Natural capital: the earth’s crust is made up of a mosaic of huge rigid plates, called tectonic plates, which move around in response to forces in the mantle. Mantle Two plates move towards each other. One is subducted back into the mantle on a falling convection current. Hot outer core Inner core Fig. 15-3, p. 337

Oceanic crust (lithosphere) Abyssal plain Continental slope Folded mountain belt Volcanoes Abyssal plain Abyssal floor Oceanic ridge Abyssal floor Abyssal hills Trench Craton Oceanic crust (lithosphere) Abyssal plain Continental slope Continental shelf Continental rise Mantle (lithosphere) Continental crust (lithosphere) Mantle (lithosphere) Figure 15.2 Natural capital: major features of the earth’s crust and upper mantle. The lithosphere, composed of the crust and outermost mantle, is rigid and brittle. The asthenosphere, a zone in the mantle, can be deformed by heat and pressure. Mantle (asthenosphere) Fig. 15-2, p. 336

Animation: Geological Forces PLAY ANIMATION

Figure 15.4 Natural capital: the earth’s major tectonic plates. The extremely slow movements of these plates cause them to grind into one another at convergent plate boundaries, move apart from one another at divergent plate boundaries, and slide past one another at transform plate boundaries. QUESTION: What plate are you floating on? Fig. 15-4, p. 338

GEOLOGIC PROCESSES The San Andreas Fault is an example of a transform fault. Figure 15-5

Wearing Down and Building Up the Earth’s Surface Weathering is an external process that wears the earth’s surface down. Figure 15-6

MINERALS, ROCKS, AND THE ROCK CYCLE Mineral resource: is a concentration of naturally occurring material in or on the earth’s crust that can be extracted and processed into useful materials at an affordable cost.

Rock Cycle Figure 15-8

ENVIRONMENTAL EFFECTS OF USING MINERAL RESOURCES The extraction, processing, and use of mineral resources has a large environmental impact. Figure 15-9

Natural Capital Degradation Extracting, Processing, and Using Nonrenewable Mineral and Energy Resources Steps Environmental effects Mining Disturbed land; mining accidents; health hazards, mine waste dumping, oil spills and blowouts; noise; ugliness; heat Exploration, extraction Processing Transportation, purification, manufacturing Solid wastes; radioactive material; air, water, and soil pollution; noise; safety and health hazards; ugliness; heat Use Figure 15.10 Natural capital degradation: some harmful environmental effects of extracting, processing, and using nonrenewable mineral and energy resources. The energy required to carry out each step causes additional pollution and environmental degradation. Transportation or transmission to individual user, eventual use, and discarding Noise; ugliness; thermal water pollution; pollution of air, water, and soil; solid and radioactive wastes; safety and health hazards; heat Fig. 15-10, p. 344

ENVIRONMENTAL EFFECTS OF USING MINERAL RESOURCES A variety of methods are used based on mineral depth. Surface mining: shallow deposits are removed. Subsurface mining: deep deposits are removed. (disturbs less than 1/10th of the land & produces less waste)

Open-pit Mining Machines dig holes and remove ores, sand, gravel, and stone. Toxic groundwater can accumulate at the bottom. Figure 15-11

Area Strip Mining Earth movers strips away overburden, and giant shovels removes mineral deposit. Often leaves highly erodible hills of rubble called spoil banks. Figure 15-12

Contour Strip Mining Used on hilly or mountainous terrain. Unless the land is restored, a wall of dirt is left in front of a highly erodible bank called a highwall. Figure 15-13

Mountaintop Removal Machinery removes the tops of mountains to expose coal. The resulting waste rock and dirt are dumped into the streams and valleys below. Figure 15-14

Mining Impacts Metal ores are smelted or treated with (potentially toxic) chemicals to extract the desired metal. Figure 15-15

Mining impacts Scarring and disruption of land surface Subsidence Major air and water pollution (5.5 metric tons of gold to make 2 wedding rings ) Acid mine drainage (rain plus sulfuric acid from bacteria action on iron sulfide) Mining industry produces more toxic emissions than any other industry

AMD

Removing Metals from Ores Ore=rock and mineral Gangue=waste material Tailings=large piles of solid waste Smelting=heating or chemicals removes mineral from ore. (cyanide salts are used) YUCK! (very pollutive, sulfur dioxide and suspended particles)

Supplies of mineral resources Economically depleted=cost more to find and process than its worth 5 choices: recycle, reuse, use less, find a substitute or do without Depletion time=time it takes to use up 80% of mineral

Sustainable Use of Nonrenewable Minerals Solutions Sustainable Use of Nonrenewable Minerals • Do not waste mineral resources. • Recycle and reuse 60–80% of mineral resources. • Include the harmful environmental costs of mining and processing minerals in the prices of items (full-cost pricing). • Reduce subsidies for mining mineral resources. • Increase subsidies for recycling, reuse, and finding less environmentally harmful substitutes. • Redesign manufacturing processes to use less mineral resources and to produce less pollution and waste. Figure 15.18 Solutions: ways to achieve more sustainable use of nonrenewable mineral resources. QUESTION: Which two of the solutions do you think are the most important? • Have the mineral-based wastes of one manufacturing process become the raw materials for other processes. • Sell services instead of things. • Slow population growth. Fig. 15-18, p. 351

Sulfuric acid producer Sludge Pharmaceutical plant Local farmers Sludge Greenhouses Waste heat Waste heat Waste heat Fish farming Waste heat Surplus natural gas Electric power plant Fly ash Oil refinery Surplus sulfur Waste calcium sulfate Figure 15.19 Solutions: the industrial ecosystem in Kalundborg, Denmark, reduces waste production by mimicking a natural food web. The wastes of one business become the raw materials for another. QUESTION: Is there an industrial ecosystem near where you live or go to school? If not, why not? Waste heat Cement manufacturer Surplus natural gas Sulfuric acid producer Wallboard factory Area homes Fig. 15-19, p. 352

Surface Mining Control and Reclamation Act of 1977 -requires mining companies to restore surface mined land by grading and replanting it. -minimally successful -first.....re-contour the land to it’s original topography -next…..replenish topsoil with nutrients -next…….replant native vegetation -last….monitor the results for 5-10 years (hard to accomplish in arid areas……why????)