Study Notes on Earth Resources and Management
USING AND CARING FOR EARTH RESOURCES
Earth Resources Definition
Earth Resource: Materials of value to humans that are extracted (or extractable) from the solid earth. Includes:
Minerals
Rocks
Energy resources
Soil
Water
(Air?)
Excludes: Living resources, human resources.
Renewable Resource: A resource that can be renewed, replenished, or regenerated on a human time scale.
Nonrenewable Resource: A resource that cannot be renewed, replenished, or regenerated on a human time scale.
Inexhaustible Resource: A resource that cannot be depleted or completely used up.
Sustainable Management of Resources
Sustainable Management: The wise use of resources where the rate of resource generation is less than the rate of resource use.
Key Approaches:
Extend availability through recycling.
Rely on renewable resources.
Manage depletion of nonrenewable resources.
Concerns: If the rate of resource generation equals the rate of resource use, sustainability becomes a problem.
Problems: Lack of ability to regenerate resources, e.g., some fish populations.
Solution: Artificial renewal which could potentially lead to loss of diversity.
Resource Limitations Facts
Earth is a closed system; resources are finite.
Earth's population is increasing at an exponential rate, leading to likely resource depletion.
Depletion rate is dependent on Earth's carrying capacity and resource consumption rate.
Minerals and Rock Resources
Importance of Minerals:
Backbone of modern societies; availability is a measure of wealth in society.
Essential in daily life and overall economy.
Processed materials from minerals account for 5% of US Gross Domestic Product (GDP).
Notably, mineral resources are nonrenewable.
Mineral Resource: Usable economic commodity extracted from naturally formed material (elements, compounds, minerals, or rocks).
Reserve: The portion of a resource that is identified and currently available for extraction. Influenced by:
Geologic factors
Technological factors
Economic factors
Legal factors.
Types of Mineral Resources
Utilization: Materials are utilized for various industries, including:
Metal production and technology.
Construction materials.
Agricultural industry (fertilizers).
Chemical industry.
Consumer goods (precious gemstones, cosmetics, food).
Energy mineral resources (e.g., uranium).
Metallic Ore: Useful metallic minerals that can be mined for profit. Economic feasibility depends on:
Technology
Economics
Political factors.
Concentration Factor (CF) Calculations:
Where:
= Concentration factor of the metal in the ore
= Concentration of the metal in average continental crust
A higher CF indicates a richer ore.
Cost Factors in Minerals
Cost Factors:
Concentration Factor can vary from 4 to 2,500 times.
Influenced by world demand, energy costs, labor costs, distance to market, and environmental costs including remediation.
Distribution of Mineral Resources
Global Distribution: Uneven distribution leads to geopolitical tensions.
Some countries export many resources, while others rely on imports.
U.S. Distribution: Varied resource availability across states, with some states rich in resources while others have low availability.
Types of Mineral Deposits
Igneous Rocks and Magmatic Deposits: High concentrations of minerals such as feldspar, tourmaline, beryl, and chromite formed through cooling and gravity settling.
Hydrothermal Ores: Formed by deposition of dissolved minerals from hot fluids, commonly including copper, lead, zinc, and gold.
Plate Tectonics: Related to the origins of many ore deposits. High temperatures, pressures, and partial melting release metals along plate boundaries.
Metamorphic Deposits: Formed under heat and pressure, including minerals like graphite and asbestos.
Sedimentary and Other Deposits: Include evaporate minerals formed from chemical reactions and placers formed by stream action from weathering.
Mineral Supply and Demand
Global Demand: Increasing due to industrialization, fluctuating from 2% pre-WWII to around 10% during WWII to the mid-1970s.
U.S. Production vs. World Supply: Despite being only 4.5% of the world population, the U.S. consumes a disproportionately high share of mineral resources.
Future Challenges: Mineral reserves will eventually be depleted, leading to resource shortages and international tensions.
Conservation of Mineral Resources
Options for Conservation:
Control consumption rates and consider substituting scarce resources with more abundant ones.
Recycling metals and resources significantly reduces the need for new extraction.
Recycling Importance: Mitigates environmental impacts, reduces waste, and saves natural resources. Many metals are successfully recycled; however, some commodities remain difficult to recycle.
Environmental Impact of Mineral Resources
Exploration and Testing Impact: Minimal impact generally but requires careful planning in sensitive areas (arid, wetlands, permafrost).
Mining Procedures Impact: Varies significantly based on hydrologic conditions, climate, rock and soil types, and topography.
Mining Operations Effects: Include land disturbances, pollution from emissions and waste, and special conditions from chemical mining processes.
Regulatory Measures: Ongoing environmental regulations such as the Clean Air Act and land reclamation efforts target to mitigate negative impacts of mining activities.
Responses to Limited Mineral Availability
Strategies:
Find alternative sources
Substitute resources where possible
Increase recycling practices
Enhance efficiency
Future Considerations
Technology's Role: The potential of biotechnology in mineral extraction could lead to cleaner processes.
New exploration techniques like remote sensing and geophysical studies offer methods to locate previously inaccessible deposits.
Marine mineral resources, particularly from seawater and hydrothermal vents, are under exploration despite current technical and political hurdles.
Surface Mining: This method involves the removal of soil and rock overlying mineral deposits. It includes several subtypes:
Strip Mining: Involves stripping away overburden to access horizontal mineral seams. Commonly used for coal and some metals.
Open-pit Mining: Involves digging a large pit in the ground to extract minerals. This method is often used for copper and gold.
Quarrying: A form of open-pit mining specifically for extracting stone, rock, and gravel for construction purposes.
Underground Mining: Involves creating tunnels or shafts to reach mineral deposits located deep underground. Types include:
Shaft Mining: Accessing deep deposits by vertical shafts driven into the ground.
Room and Pillar Mining: Involves mining material in a series of rooms while leaving pillars of material to support the roof.
Longwall Mining: A method where a long wall of coal is mined in a single slice, with the mined-out area subsequently collapsing.
Placer Mining: Involves the extraction of valuable minerals from stream beds or sediment. Often involves washing and sifting through dirt and gravel.
Mountaintop Removal Mining: A form of surface mining that involves removing the summits of mountains to expose coal seams, followed by disposing of the waste materials in adjacent valleys.
Types of Mineral Resources
Igneous:
Disseminated: Diamonds (South Africa)
Crystal Settlings: Chromite (Stillwater, Montana)
Late Magmatic: Magnetite (Adirondack Mountains, New York)
Pegmatite: Beryl and lithium (Black Hills, South Dakota)
Hydrothermal: Copper (Butte, Montana)
Metamorphic:
Contact Metamorphism: Lead and silver (Leadville, Colorado)
Regional Metamorphism: Asbestos (Quebec, Canada)
Sedimentary:
Evaporite (lake or ocean): Potassium (Carlsbad, New Mexico)
Placer (stream): Gold (Sierra Nevada foothills, California)
Glacial: Sand and gravel (Northern Indiana)
Deep Ocean: Manganese oxide nodules (Central and southern Pacific Ocean)
Biological: Phosphorus (Florida)
Weathering:
Residual Soil: Bauxite (Arkansas)
Secondary Enrichment: Copper (Utah)