Environmental science studies the interactions between the physical, chemical, and biological components of the environment, including their effects on all types of organisms. Earth science (also known as geoscience), is an inclusive term for all sciences related to Earth (geology, meteorology, oceanography, etc). Although environmental and earth science cover essentially the same material, environmental science places greater emphasis on the biological realm, while earth science places greater emphasis on the physical realm.
Environmental and earth science study the interactions of four major systems or “spheres” (figure 8.6).
- The geosphere consists of the core, mantle and crust of the Earth.
- The atmosphere contains all of the Earth’s air and is divided into troposphere, stratosphere, mesosphere, thermosphere and ionosphere.
- The hydrosphere contains all of the solid, liquid and gaseous water on Earth, extending from the depths of the sea to the upper reaches of the troposphere where water is found. Ninety-seven percent of the hydrosphere is found in salty oceans, and the remainder is found as vapor or droplets in the atmosphere and as liquid in ground water, lakes, rivers, glaciers and snowfields.
- The biosphere is the collection of all Earth’s life forms, distributed in major life zones known as biomes: tundra, boreal forest, temperate deciduous forest, temperate grassland, desert, savannah, tropical rainforest, chaparral, freshwater, and marine.
Although the four systems have their unique identities, there is substantial interaction between them. Environmental scientists study the effects of events in one sphere on the other spheres. For example, a volcanic eruption in the geosphere may cause profound direct and indirect effects on the hydrosphere, atmosphere and biosphere as follows:
Example 1 (Volcano) On May 18, 1980, Mount Saint Helens, in the state of Washington, erupted. This event altered the surrounding environment, and provided scientists with an opportunity to study the effects of volcanic eruptions on the geosphere, hydrosphere, atmosphere and biosphere. Such studies are vital because volcanic eruptions will continue to occur, and will have increasing impact on humans as people continue to settle lands closer to dormant volcanoes. The following are but a few of the myriad of interactions resulting from a volcanic eruption.
Volcano >> geosphere >> atmosphere >> hydrosphere >> biosphere
Volcanoes (an event in the geosphere) release a large amount of particulate matter into the atmosphere. These particles serve as nuclei for the formation of water droplets (hydrosphere). Rainfall (hydrosphere) often increases following an eruption, stimulating plant growth (biosphere). Particulate matter in the air (atmosphere) falls out, initially smothering plants (biosphere), but ultimately enriching the soil (geosphere) and thereby stimulating plant growth (biosphere).
Volcano >> geosphere >> hydrosphere >> biosphere
Volcanoes (events in the geosphere) may release a substantial amount of hot lava (geosphere), which causes mountain glaciers (hydrosphere) to melt. Mudflows (geosphere) and flooding may occur downstream from volcanoes and may inundate streamside communities (biosphere).
Volcano >> geosphere >> atmosphere >> biosphere >> geosphere
Volcanoes (events of the geosphere) release a large amount of carbon dioxide (atmosphere), the raw material for sugar production in plants (biosphere). This may increase photosynthetic production and eventually increase the amount of biomass, which, after a very long time, forms coal and oil deposits (geosphere).
Volcano >> complex interactions
Volcanoes (geosphere) may emit large quantities of sulfur dioxide (atmosphere). When atmospheric sulfur dioxide combines with water (hydrosphere), sulfuric and sulfurous acid form. Rain (hydrosphere) may bring these acids to the Earth, acidifying soils (geosphere), lakes and rivers (hydrosphere). Acidic water leaches nutrients from the soil (geosphere) into the water table (hydrosphere), making the soil less fertile for plants (biosphere), and the subterranean water supply (hydrosphere) less potable for humans (biosphere). Acid rain falling on lakes and streams reduces the pH of the water (hydrosphere), which may result in a decrease in phytoplankton and zooplankton growth (biosphere). If photosynthesis is reduced, atmospheric concentrations of carbon dioxide can build up and stimulate global warming (atmosphere) which may contribute to increased melting of glaciers (hydrosphere).
Sample ESS Events
Gulf oil sill
Salt water intrusion
Wind farm development