Lecture 5: Resources from Our Changing Planet PDF

Lecture 5: resources from our changing planet Populationa and resources: People overpopulation ● Too many people living in a given geographic area Consumption overpopulation ● Each individual consumes too large a share of resources *both lead to increased use of resources and destruction of enviro...

Lecture 5: resources from our changing planet Populationa and resources: People overpopulation ● Too many people living in a given geographic area Consumption overpopulation ● Each individual consumes too large a share of resources *both lead to increased use of resources and destruction of environment* ● 25% of humans consume ○ 50% energy ○ 86% aluminum ○ 76% harvested timber ○ 61% meat ○ 42% fresh water ● 75% of pollution and waste Resources: ● Non-renewable ○ Limited supply, do not regnereate (or very, very slowly) ○ Fossil fuels ■ Millions of years oto accumulate oil, gas, coal ○ Nuclear fuel ■ Safety and waste a concern ○ Minerals ■ Metals: iron, aluminum ■ Industrial: gravel, sand ■ Critical: lithium, nickel, cobalt ○ Environmental impacts of mining ○ Our consumption of these non-renewable materials is changing the earth ● Renewable resources ○ Virtually unlimited, replenish over short time period (e.g. forests, fisheries, groundwater, agricultural land and soil) ○ Easy to overexploit ■ E.g. fish stocks → used in a non-renewable way ○ Renewable energy ■ Hydropower → environmental impacts ■ Solar → expensive ■ Wind → unpredictable ■ Geothermal → limited locales (for electricity) Minerals and mining: ● The importance of mining for Canada ○ $97 B (6% of Canada’s GDP is directly linked to mining Canadian mining assets totalled $273 B in 2020 (of this 69% were located abroad) ○ Canadian companies in 2021 spent $3.6 B on exploration and appraisal ● “Critical minerals” ○ Important for green/digital economy and security ● Primary (in host rock) vs secondary (after moving) mineral deposits ○ Primary ■ Hydrothermal ore deposit and gold vein (industrail: open pit or underground) ○ Secondary ■ Placer deposits and gold nugget (artesinal: panning or dredging) ○ *these determine the type of exploration, extraction, and production required* ● Mineral resources cycle ○ Largest underground salt mine: Goderich, Ontario ○ Largest open pit mine: Bingham Canyon Mine, Utah, 1,2 km deep, 4km wide ○ “Monte Kali” near Heringen, Germany 100m high, mining of potash for over 125 yrs, 200M tons of salt, 14,000 tons/day added ● Mine tailings – wastes that comes from mining ○ Gold ■ Ore typically contains 1g/ton ■ Ore is crushed ■ Gold may be removed from rock by acid leaching or now more ○ Oil sands ■ Bitumen is removed from sand using hot water ● Acid rock drainage – leaching of metals, weathering of exposed sulfides creates sulfuric acid ○ E.g. Britannia Mine, BC ■ Operating from the 1880s, was largest copper mine in British Empire in the 1920s ■ Local groundwater and surface water polluted by sulphuric acid and dissolved metals from the mning ○ WQC = water quality criteria ● Reclamation ○ Return land to end use (habitat, agriculture, development) Case study: Efemcukuru gold mine ● A “sustainable” mining operation in western Turkiye near Izmir ● Partly owned by Eldorado Gold, a Canadian company ● Vein ore deposit requires underground mining to follow the deposit to depth ● In lifetime of operation it is estimated that 8.5 million tons of ore will be mined ● Estimated mine life of 7 years (a relatively short time…) ● conservation/reclamation ○ Backfill excavation ○ Filtered waste water mixed with cement for backfill ○ Slope stabilization and site rehabilitation with olive groves What is gold? ● Native chemical element Au ● Dence, soft, malleable, ductile ● Very non-reactive chemically ● Used in jewelry, electrical connectors, IR shielding, teeth ● Mainly used as a common financial standard ● Alloyed with other metals to strengthen Au ● “Karat” unit measures purity ○ 24kt gold is pure (100%) gold ○ 18 kt gold is approx 75% gold Diamonds: ● A natural mineral ● Solid form of carbon © with atoms in cubic diamond crustla structure ● Hardest known natural material (hardness 10 on Moh scale) Diamonds created beneath the lithosphere (high pressure: 4-6 GPa; 150-200km beneath the surface) Brought to the surface in kimberlite pipes Volcanic ultramafic magma from mantel possibly containing diamond xenoliths A properly cut diamond takes into account the internal reflection of light in the diamond An ideal cut internally reflects the light back out to make a more brilliant diamond Color is influenced by chemical or structural impurities in diamond Huge variation in colour, although some are especially rare Clarity: ● Flaws in diamonds can result from inclusions fractures (during cutting, etc) ● Most natural diamonds have inclusions, hence the flawless diamonds have most value ● The inclusions can give us interesting scientific information on the age/conditions in the earth’s mantle Production in Canada: ● Most diamonds in canada are mined in the NWT ○ E.g. Diavik mine starts producing in 1998 ● Part of kimberlite filed archean in the slave province (a geological unit) The challenge: ● The operation ○ ~2.8 carats per ton of ore ○ ~reserves of 52.8 million carats ○ Employing 1000 people onsite for 25-30 years lifespan of the mine ○ Close connections and involvement with local indigenous groups ○ “Ethically and sustainably” sourced diamonds