Chapter Notes: Natural Resources
Every day, you use materials and energy that come from Earth. The water you drink, the metal in your phone, the coal or natural gas that generates electricity, and the trees that provide paper all come from our planet. These materials and energy sources that we take from Earth are called natural resources. Understanding natural resources-where they come from, how we use them, and how to manage them wisely-is essential for building a sustainable future. In this chapter, you will explore the different types of natural resources, learn how they form, discover how humans use them, and examine the environmental impacts of resource extraction and consumption.
What Are Natural Resources?
A natural resource is any material or energy source that occurs in nature and is useful to humans. Natural resources include water, air, soil, minerals, fossil fuels, forests, wildlife, and sunlight. These resources are the foundation of human civilization. Without them, we could not grow food, build homes, manufacture products, or generate energy.
Natural resources can be classified in several important ways. The most common classification divides them into renewable resources and nonrenewable resources.
Renewable Resources
Renewable resources are natural resources that can be replenished naturally over relatively short periods of time. These resources regenerate through natural processes, so they can be used repeatedly if managed properly. Examples include:
- Solar energy: Energy from the Sun is constantly radiated to Earth and will continue for billions of years.
- Wind energy: Wind is created by uneven heating of Earth's surface by the Sun, making it a continuous resource.
- Water: The water cycle continuously moves water between the ocean, atmosphere, and land.
- Forests: Trees can be replanted and regrown after harvest.
- Soil: Healthy soil can regenerate nutrients through decomposition and natural processes, though this happens slowly.
- Biomass: Organic material from plants and animals that can be replaced by growing new organisms.
The key characteristic of renewable resources is that they regenerate. However, renewable does not mean unlimited. If renewable resources are used faster than they can regenerate, they can be depleted. For example, overfishing can reduce fish populations faster than they can reproduce, and cutting down forests faster than new trees can grow leads to deforestation.
Nonrenewable Resources
Nonrenewable resources are natural resources that exist in fixed amounts or are replenished by natural processes so slowly that they are considered limited on human timescales. Once used, these resources cannot be replaced within hundreds, thousands, or even millions of years. The most important nonrenewable resources include:
- Fossil fuels: Coal, oil (petroleum), and natural gas formed from the remains of ancient organisms over millions of years.
- Nuclear fuels: Uranium and other radioactive elements used in nuclear power plants.
- Minerals and metals: Iron, copper, gold, aluminum, and other metallic ores found in Earth's crust.
- Gemstones: Diamonds, rubies, and other precious stones.
Because nonrenewable resources form over geologic timescales-often millions of years-they are essentially finite. Once we extract and use them, they are gone. This makes careful management and conservation of nonrenewable resources critically important for future generations.
Fossil Fuels: Formation and Types
Fossil fuels are the most widely used energy sources in the modern world. They power our cars, heat our homes, and generate most of the world's electricity. Understanding how fossil fuels form and why they are nonrenewable helps explain both their value and the challenges they present.
How Fossil Fuels Form
Fossil fuels formed from the remains of organisms that lived millions of years ago. The process varies slightly for different types of fossil fuels, but all follow a similar pattern:
- Accumulation: Dead plants, algae, and tiny marine organisms accumulated in swamps, ocean floors, or lake bottoms.
- Burial: Layers of sediment (sand, mud, and minerals) buried the organic material, cutting off oxygen.
- Pressure and heat: Over millions of years, the weight of overlying sediment created intense pressure, and Earth's internal heat increased the temperature.
- Chemical transformation: The combination of heat, pressure, and time chemically transformed the organic material into coal, oil, or natural gas.
This process is called fossilization, and it takes between 50 million and 400 million years. That is why fossil fuels are nonrenewable-even though new organic material is being buried today, it will not become usable fossil fuel for millions of years.
Types of Fossil Fuels
Coal forms primarily from the remains of land plants that grew in ancient swamps and forests. As plant material was buried and compressed, it underwent a transformation through several stages:
- Peat: Partially decomposed plant material; the first stage.
- Lignite: Soft, brownish coal with relatively low energy content.
- Bituminous coal: Harder, black coal with higher energy content; the most abundant type.
- Anthracite: The hardest coal with the highest energy content; formed under the most intense pressure.
Coal is primarily used to generate electricity in power plants. When burned, coal releases stored chemical energy as heat, which boils water to create steam that turns turbines connected to generators.
Petroleum (crude oil) forms mainly from the remains of tiny marine organisms such as plankton and algae. These organisms settled to the ocean floor, were buried by sediment, and transformed under heat and pressure into liquid hydrocarbons. Oil is typically found trapped in porous rock layers beneath impermeable rock that prevents it from escaping to the surface.
Petroleum is refined into many products including gasoline, diesel fuel, jet fuel, heating oil, asphalt, and petrochemicals used to make plastics, medicines, and synthetic fabrics.
Natural gas forms in a similar way to petroleum but under different temperature and pressure conditions. The primary component is methane (CH4), though natural gas also contains small amounts of other hydrocarbons. Natural gas is often found together with petroleum deposits or in separate underground reservoirs. It is used for heating, cooking, generating electricity, and as a raw material in chemical manufacturing.
Example: A coal deposit formed from a forest that existed 300 million years ago during the Carboniferous Period.
The forest was repeatedly flooded and buried by sediment.
Over time, layers of plant material built up and were compressed.What type of coal would likely form at shallow depths with moderate pressure?
Solution:
At shallow depths, the pressure and temperature are relatively low.
This would produce coal in the earlier stages of transformation.
Lignite or bituminous coal would form, rather than anthracite which requires much deeper burial and higher pressure.
The coal deposit would most likely be lignite or bituminous coal.
Mineral Resources
Minerals are naturally occurring, solid, inorganic substances with a specific chemical composition and an ordered internal structure. Mineral resources are minerals or rocks that can be extracted from Earth and used by humans. They include metallic ores, industrial minerals, and building materials.
Metallic Minerals
Metallic minerals contain metals that can be extracted and used in manufacturing. Important metallic minerals include:
- Iron ore: Used to make steel for construction, vehicles, and machinery.
- Copper ore: Used in electrical wiring, plumbing, and electronics.
- Aluminum ore (bauxite): Used in aircraft, beverage cans, and foil.
- Gold and silver: Used in jewelry, electronics, and as stores of value.
- Rare earth elements: Used in smartphones, computers, and renewable energy technologies.
Most metallic minerals are found in ores-rocks that contain a high enough concentration of a valuable mineral to make mining economically worthwhile. For example, iron ore contains iron oxides mixed with other minerals and rock material.
Nonmetallic Minerals
Nonmetallic minerals do not contain extractable metals but are valuable for other uses:
- Salt (halite): Used for food, de-icing roads, and chemical manufacturing.
- Gypsum: Used to make wallboard (drywall) for construction.
- Phosphates: Used in fertilizers to help plants grow.
- Sand and gravel: Used in concrete, road construction, and glassmaking.
- Limestone: Used in cement, agriculture, and chemical industries.
How Mineral Deposits Form
Mineral deposits form through several geologic processes:
- Magmatic processes: As magma cools, dense metallic minerals can settle and concentrate at the bottom of magma chambers.
- Hydrothermal processes: Hot water dissolves minerals from rock and deposits them in cracks and fractures as the water cools.
- Weathering and erosion: Chemical weathering can concentrate minerals in soil, while erosion can transport heavy minerals to stream beds where they accumulate.
- Evaporation: When water evaporates from lakes or seas, dissolved minerals are left behind as evaporite deposits (like salt flats).
Like fossil fuels, most mineral resources are nonrenewable. Once a high-grade ore deposit is mined and the metal extracted, that deposit is exhausted. New mineral deposits form only through geologic processes that take thousands to millions of years.
Water Resources
Water is one of Earth's most essential natural resources. All living organisms need water to survive, and human societies require enormous quantities of freshwater for drinking, agriculture, industry, and sanitation.
The Water Cycle and Water Availability
Earth's water is constantly recycled through the water cycle (also called the hydrologic cycle). Water evaporates from oceans, lakes, and land surfaces, forms clouds, falls as precipitation, and flows back to the ocean through rivers and groundwater. This makes water a renewable resource.
However, freshwater-water with low concentrations of dissolved salts-makes up only about 2.5% of all water on Earth. Of that freshwater, about 70% is frozen in ice caps and glaciers, and another significant portion is deep underground. Only a small fraction of Earth's water is readily accessible as surface water in lakes and rivers or as shallow groundwater.
Groundwater
Groundwater is water stored underground in spaces between soil particles and in cracks in rocks. The zone where all spaces are filled with water is called the saturated zone, and its upper surface is the water table. A permeable rock layer that holds and transmits groundwater is called an aquifer.
Groundwater is extracted by drilling wells into aquifers. It supplies drinking water for about half of the U.S. population and is essential for irrigation in many agricultural regions.
Although groundwater is renewable, it can be depleted. When water is pumped out faster than it is naturally replenished by rainfall and infiltration, the water table drops. This is called groundwater depletion and can lead to wells running dry, land subsidence (sinking), and reduced flow in rivers and streams that are fed by groundwater.
Surface Water
Surface water includes water in rivers, lakes, and reservoirs. It is a critical source of freshwater for many purposes:
- Drinking water: Many cities draw water from rivers or reservoirs.
- Irrigation: Farmers divert river water to irrigate crops.
- Hydroelectric power: Dams on rivers generate electricity from flowing water.
- Transportation: Rivers and lakes serve as routes for shipping.
- Recreation: Lakes and rivers provide opportunities for fishing, boating, and swimming.
Surface water is vulnerable to pollution from industrial discharge, agricultural runoff containing fertilizers and pesticides, and sewage. Protecting surface water quality is essential for human health and ecosystem health.
Example: A farming community pumps 10 million liters of groundwater per day from an aquifer.
Natural recharge from rainfall adds only 6 million liters per day to the aquifer.What is happening to the aquifer, and what might be the long-term consequences?
Solution:
The community withdraws 10 million liters per day but only 6 million liters per day are replaced.
This means there is a net loss of 4 million liters per day from the aquifer.
Over time, the water table will drop, wells may run dry, and the land surface may sink due to loss of support.
The aquifer is experiencing groundwater depletion, which threatens the long-term water supply.
Forest Resources
Forests cover about 30% of Earth's land surface and provide a wide range of valuable resources and services. Forests are renewable resources, but only if they are managed sustainably.
Uses of Forest Resources
Forests provide many important resources:
- Timber: Wood for construction, furniture, and paper products.
- Fuelwood: Wood burned for heating and cooking, especially in developing countries.
- Non-timber products: Fruits, nuts, medicinal plants, rubber, and resins.
- Ecosystem services: Forests produce oxygen, absorb carbon dioxide, filter water, prevent soil erosion, regulate climate, and provide habitat for wildlife.
Deforestation and Sustainable Forestry
Deforestation is the permanent removal of forests to make way for agriculture, ranching, urban development, or mining. Deforestation has serious environmental consequences:
- Loss of biodiversity as forest species lose their habitat
- Increased carbon dioxide in the atmosphere, contributing to climate change
- Soil erosion and degradation
- Disruption of the water cycle and increased flooding
- Loss of resources for indigenous peoples and local communities
Sustainable forestry is the practice of managing forests so that they can be harvested for resources while maintaining their health and biodiversity for future generations. Sustainable practices include:
- Selective cutting rather than clear-cutting entire forests
- Replanting trees after harvest
- Protecting old-growth forests and sensitive ecosystems
- Managing forests to maintain habitat for wildlife
- Preventing illegal logging
Energy Resources
Energy is essential for modern life. We use energy to power vehicles, heat and cool buildings, run appliances and electronics, and manufacture goods. Energy resources can be divided into nonrenewable and renewable categories.
Nonrenewable Energy Resources
The vast majority of energy used worldwide comes from nonrenewable sources:
- Fossil fuels (coal, oil, natural gas): Provide about 80% of global energy. Burning fossil fuels releases carbon dioxide (CO2), a greenhouse gas that contributes to climate change, as well as pollutants that harm air quality.
- Nuclear energy: Generated by splitting uranium atoms in nuclear reactors. Nuclear power produces no greenhouse gases during operation but creates radioactive waste that must be stored safely for thousands of years.
Renewable Energy Resources
Renewable energy sources are increasingly important as alternatives to fossil fuels:
- Solar energy: Energy from sunlight captured by photovoltaic panels or concentrated solar power systems. Solar energy produces no pollution and is abundant, though it requires sunny conditions and energy storage for nighttime use.
- Wind energy: Kinetic energy of moving air captured by wind turbines. Wind power is clean and increasingly cost-effective, but wind is variable and turbines require suitable locations.
- Hydroelectric power: Energy from flowing water, typically captured by dams. Hydropower is reliable and produces no air pollution, but dams disrupt river ecosystems and can displace communities.
- Geothermal energy: Heat from Earth's interior used to generate electricity or heat buildings. Geothermal is reliable and clean but limited to regions with suitable geology.
- Biomass energy: Energy from burning organic materials like wood, crop waste, or biofuels made from plants. Biomass is renewable if plants are regrown, but burning it releases CO2.
Transitioning from nonrenewable to renewable energy sources is a major global challenge. Renewable energy technologies are improving rapidly, but fossil fuels still dominate because of their high energy density, existing infrastructure, and relatively low cost in many regions.
Environmental Impacts of Resource Extraction and Use
Extracting and using natural resources creates environmental impacts that must be understood and managed.
Mining Impacts
Mining removes minerals and ores from Earth's crust through surface mining (open-pit mines and strip mines) or underground mining. Environmental impacts include:
- Habitat destruction: Clearing land for mines destroys ecosystems.
- Soil erosion: Removal of vegetation and topsoil leads to erosion.
- Water pollution: Mine drainage can release toxic metals and acidic water into rivers and groundwater.
- Air pollution: Dust and emissions from mining equipment degrade air quality.
- Landscape scarring: Mines leave permanent marks on the landscape unless carefully reclaimed.
Modern mining regulations require companies to minimize impacts and restore mined land through reclamation-replanting vegetation, reshaping landforms, and treating polluted water.
Fossil Fuel Combustion
Burning fossil fuels releases several harmful pollutants:
- Carbon dioxide (CO2): The primary greenhouse gas driving climate change.
- Sulfur dioxide (SO2): Causes acid rain, which damages forests, soils, and aquatic ecosystems.
- Nitrogen oxides (NOx): Contribute to smog and acid rain.
- Particulate matter: Tiny particles that harm respiratory health.
- Mercury and other heavy metals: Toxic substances that accumulate in ecosystems.
Reducing fossil fuel use through energy efficiency and switching to renewable energy can significantly reduce these impacts.
Water Use and Pollution
Excessive water withdrawal can deplete rivers and aquifers, harming ecosystems and reducing water availability for future use. Water pollution from industrial waste, agricultural chemicals, and sewage degrades water quality, threatens aquatic life, and makes water unsafe for drinking.
Conservation and Sustainable Use
Because many natural resources are nonrenewable or can be depleted if overused, conservation-using resources wisely and reducing waste-is essential.
Conservation Strategies
Effective conservation involves multiple approaches:
- Reducing consumption: Using less energy, water, and materials decreases resource depletion.
- Increasing efficiency: Using resources more efficiently (like fuel-efficient vehicles or energy-efficient appliances) reduces waste.
- Reusing and recycling: Reusing products and recycling materials reduces the need to extract new resources.
- Protecting ecosystems: Preserving forests, wetlands, and other ecosystems maintains biodiversity and ecosystem services.
- Developing alternatives: Investing in renewable energy and sustainable materials reduces dependence on nonrenewable resources.
The Three Rs: Reduce, Reuse, Recycle
The three Rs are a simple framework for conservation:
- Reduce: Use less. Buy only what you need, choose products with less packaging, and avoid single-use items.
- Reuse: Use items multiple times. Repair broken items, donate or sell items you no longer need, and choose reusable products over disposable ones.
- Recycle: Process used materials into new products. Recycle paper, plastic, glass, and metals to reduce the need for mining and logging.
Recycling aluminum, for example, uses 95% less energy than producing new aluminum from ore. Recycling paper reduces the need to cut down trees. By following the three Rs, individuals can significantly reduce their environmental impact.
Example: A city of 100,000 people currently sends all its waste to a landfill.
The city implements a recycling program that diverts 30% of waste from the landfill.
Previously, the city generated 200 tons of waste per day.How much waste now goes to the landfill each day after recycling begins?
Solution:
Original waste = 200 tons per day
Recycling diverts 30% of waste: 0.30 × 200 = 60 tons per day recycled
Waste to landfill = 200 - 60 = 140 tons per day
After implementing recycling, the city sends 140 tons of waste to the landfill each day.
The Future of Natural Resources
As the human population grows and developing countries industrialize, global demand for natural resources continues to increase. Managing resources sustainably is one of the greatest challenges facing humanity.
Key considerations for the future include:
- Transitioning to renewable energy: Reducing reliance on fossil fuels will decrease greenhouse gas emissions and slow climate change.
- Improving resource efficiency: Technological innovations can help us use resources more efficiently and reduce waste.
- Protecting biodiversity: Conserving ecosystems ensures that natural resources continue to regenerate and provide ecosystem services.
- Developing sustainable agriculture: Growing food in ways that protect soil, water, and biodiversity is essential for long-term food security.
- Promoting circular economies: Designing products to be reused, repaired, and recycled reduces waste and resource consumption.
Understanding natural resources-how they form, how we use them, and how our use affects the environment-empowers you to make informed decisions as a consumer and citizen. Every choice you make about energy use, water consumption, waste disposal, and product purchases has an impact on Earth's natural resources. By choosing wisely and supporting sustainable practices, you can help ensure that future generations have access to the resources they need to thrive.
