Environmental Science

This course (designed for grades 11 or 12) is an alternative to the Physics, Chemistry, or Physical Geology courses toward completion of the three units of credit required for high school graduation. Through the course, students investigate issues of environmental quality at local, regional, national, and global levels—such as resource management and the capacity of technology to address environmental problems. This course also explores the chemical cycles, which characterize systems in equilibrium and disequilibrum. Within the course, there are six main themes from which to develop standards-based learning cycle lessons:

• Chemical Cycles in Nature
• Systems in Equilibrium
• Energy in the Environment
• Development of New Materials
• Ecology
• Earth's Resources
• Human Impact on the Earth System

Chemical Cycles in Nature

• Natural systems share the same physical principles of the conservation and transformation of matter and energy.
• Over long spans of time, matter and energy are transformed among living things, and between them and the physical environment. In these grand-scale cycles, the total amount of matter and energy remains constant, even though their form and location undergo continual change.
• Biogeochemical cycles are essentially the continuous transport and transformation of materials in the environment. Materials are transported through the biosphere, atmosphere, hydrosphere, and lithosphere in a series of interdependent cycles. These cycles include the circulation of elements and nutrients upon which life and the Earth’s climate depend.

Systems in Equilibrium

• Complex systems tend to show cyclic fluctuations around a state of approximate equilibrium, which can be thought of as a balance in a model (e.g., life, chemical, physical) from which predictions can be made.
• In the long run, however, systems inevitably change. For example, an ecosystem changes when climate changes or when very different, new, invasive species appear as a result of migration, evolution, or introduction by humans.

Energy in the Environment

• Different sources of energy and ways of using them have different costs, implications, and risks.
• Sunlight is the direct source of most of the energy on Earth. It becomes available for use in several ways. The energy of sunlight is captured directly in plants and it also heats Earth’s air, land, and water, causing wind and rain. Resources such as direct sunlight, wind, and water are known as renewable resources.
• Plant resources like wood and grasses are self-renewing—however, only at a limited rate and only if it is planted at the same rate it is harvested. These resources are also known as renewable resources.
• Resources already accumulated in the Earth such as coal, oil, natural gas, and uranium are the result of millions of years of sun energy stored in plants and animals. These nonrenewable resources will become more difficult to obtain as the most readily available sources are depleted.
• New technology may make it possible to use the remaining sources more efficiently by digging deeper, processing lower-concentration ores, or mining the ocean bed. An exact time of when nonrenewable resources will be depleted is difficult to estimate. The ultimate limit may be prohibitive cost rather than complete disappearance—a question of when the energy required to obtain the resources becomes greater than the energy those resources provide.

Development of New Materials

• The growth of technology has led to the use of some natural materials faster than they can be replaced by Earth’s processes (e.g. petroleum).
• There is a continuing search for alternative materials. In many cases, they have been found or invented (e.g., ethanol, biofuels).
• Increasingly, the disposal of used materials has become a problem. Organic materials degrade readily. However, this process is slowed considerably in the world’s ever-expanding landfills. Other materials, such as aluminum and glass, are easily recycled into new products.
• Some materials, such as certain types of plastics, are not easily recycled; nor do they degrade quickly when returned to the environment.
• Solving these problems of disposal requires technological innovations paired with social understanding.

Ecology

• Ecosystems change when significant climate changes occur or when one or more new species appear as a result of immigration or speciation.
• Earth is made up of a series of interconnected systems. A change in one system affects other systems. Interactions among the Earth’s lithosphere, hydrosphere, atmosphere, cryosphere, and biosphere have resulted in the ongoing changes of Earth’s global system. Thermal energy transfers in the world’s oceans impact physical features (e.g., ice caps, oceanic and atmospheric currents) and weather patterns.
• Humans live at the interface between the atmosphere (driven by solar energy) and the upper mantle (where convection creates changes in Earth’s crust). At times, these normal changes can be hazardous to humans.
• Birth rates, fertility rates, and death rates are affected by various environmental factors including population density, resource use, nutritional status, and toxins.

Earth's Resources

• Earth's resources include both renewable and nonrenewable resources.
• Earth's resources can be categorized into three main groups: energy (e.g. fossil fuels, radioactive materials, water, wind, and solar), metals (e.g. iron, copper, zinc, lead, aluminum, gold, silver, and many more), and non-metals (sand, gravel, limestone, soil, gypsum, sulfur, gemstones, and many more).
• Energy and resource use in the United States has changed as technology and demand has increased.
• In addition to the depletion of fossil fuels for energy, other nonrenewable resources are being depleted as consumers continue to expand their use of the materials. Road and building construction, manufacturing, and agriculture use large amounts of metals, sand, gypsum, soil, gravel, and limestone.
• Energy consumption varies globally, depending on availability of specific resources and economic development of the specific country.
• Laws to conserve and protect Earth's resources are continually being developed and discussed at Local, State, National, and Global levels.
• Alternate energy sources are becoming important as fossil fuels are being depleted or difficult to obtain. Hybrid vehicle technology, biofuels, geothermal energy, hydro-power, solar energy, and wind energy are some of the more common forms of alternative energy research that continue to be developed, improved, and made available to the public.

Human Impact on Earth’s Ecosystems

• Factors of human population impact natural systems such as levels of education, children in the labor force, education and employment of women, infant mortality rates, costs of raising children, birth control methods, and cultural norms.
• The structure and stability of ecosystems are affected by changes in their biotic and abiotic components as a result of human activity. Biotic and abiotic global changes have occurred in the past and will continue to occur in the future.
• Populations can increase through linear or exponential growth, with corresponding effects on resource use and environmental pollution. This increase in population can reach or temporarily exceed the carrying capacity of a given environment.
• As societies have grown, become stable, and come to value aspects of the environment, vulnerability to natural processes of change (e.g., tectonic activity, weather patterns) has increased.
• Conservation of resources—through recycling, reduction in use, reuse, and reclamation—is necessary to ensure the future habitability of Earth.