Environmental Engineering Reference
In-Depth Information
The potential energy possessed, for example, by boulders on a slope is a product of the
erosion of the valley by the water and ice. Potential energy is also derived from earth
movements, for mountain building lifts the rock to leave it higher than the surrounding
Earth surface. Since these mountain-building processes are powered by heat energy
within Earth, they represent the transformation of heat energy to kinetic and, ultimately,
potential energy. The potential energy is subsequently converted to kinetic energy as the
rock particles tumble, sludge or wash downslope. Friction with the surface and between
the particles releases further energy in the form of heat.
ECOLOGICAL TRANSFERS
On land the formation of soil, the growth of plants and the support given by this
vegetation to animals all reflect further energy transfers and conversions.
In the case of terrestrial ecosystems (Figure 2.18) the development of soil cover
involves weathering, which in turn reflects the transfer of chemical energy from rocks to
soil. Plants take up substances from the soil and store the chemical energy in their tissue.
They also use radiant energy from the sun, and chemical and heat energy from the
atmosphere, all three forms being converted to chemical energy by the plant. As the
vegetation dies, or animals devour the plant material, this energy is cycled through the
environment. Animals convert the chemical energy to heat for bodily warmth and to
kinetic energy for motion. They return some energy to the soil and the atmosphere as
chemical energy.
