Environmental Engineering Reference
In-Depth Information
9
What Is Present
Analytical results having unexpected amounts or types of components
are not necessarily in error
The environment is made up of the atmosphere, hydrosphere, and lithosphere. The
atmosphere is relatively simple and its composition is relatively stable. Only those
elements, compounds, ions, and molecules that are gases or that can remain suspended in
the atmosphere will stay there for a significant period of time. The hydrosphere is more
complex, having various levels of salts and other compounds that originate in the
lithosphere containing it. The lithosphere is far more complex and can contain all the
elements, compounds, molecules, and ions present in the Earth. The three parts of the
environment cannot be separated from each other. Components occurring in one sphere
can and do move into the other spheres.
The three spheres are sampled for contaminants on a regular basis. For the most part
components occurring in the atmosphere are either its natural components or components
put there as a result of the activities of man. With few exceptions, such as reactions
among chlorine, ozone, and nitrogen oxides, the number and complexity of reactions
producing compounds, ions, and molecules in the atmosphere are both limited and
relatively simple.
Both the hydrosphere and lithosphere, particularly the soil, are different. Soil is
intimately connected to water because rain falls on it, infiltrates, percolates, and finally is
released into bodies of water. During these processes water picks up molecules, ions, and
elements from the soil. The soil is a great reactor, producing all manner of inorganic,
organic, and biochemical molecules, as well as ions, some of which will be dissolved by
the water moving through it. The question then becomes what types of compounds are
common and commonly produced in this reactor.
Added to the natural components produced by normal soil reactions will be
components produced by man and either unintentionally or intentionally added to soil and
water. Both these groups of compounds are important because they will show up in
samples taken from soil and water and because it is important not to confuse naturally
made and occurring components with contaminants added to soil and water by man.
Soil is a mixture of inorganic and organic solids plus a solution of inorganic and
organic ions, molecules, gases, and elements in water. It also has a gas phase made up of
nitrogen, oxygen, carbon dioxide, water vapor, argon, methane, and a number of other
minor gaseous constituents. Many think of the inorganic fraction as being inert and
unchanging. This is not true. The variety of inorganic components, their structure, and
their composition is vast. Likewise, the organic fraction is large and immensely varied.
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