Our environment is formed by — substances
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Environmental Chemistry
Environmental chemistry is the discipline that concerns itself with how chemicals are formed, how they are introduced into the environment, how they change after being introduced, the extent to which they enter and where they end up in organisms and other receptors, and the effects they have (usually the damage they do) once they get there.
6 Physical Chemistry in the Environment
Inorganic chemical reactions and organic chemical reactions are certainly an important aspect of environmental chemistry but there is another aspect of chemistry that must not be ignored, and this is physical chemistry.
When a chemical is released into the environment, it becomes distributed among the four major environmental compartments: (1) air, (2) water, (3) soil, and (4) flora and fauna, that is, living organisms. Each of the first three categories can be further subdivided in floral (plant) environments and faunal (animal, including human) environments. The fraction of the chemical that will move into each compartment is governed by the physicochemical properties of that chemical.
In addition, the distribution of chemicals in the environment is governed by physical processes such as (1) sedimentation, (2) adsorption, and (3) volatilization and the chemical can then be degraded by chemical and/or biological processes. Chemical processes generally occur in water or the atmosphere and follow one of four reactions: oxidation, reduction, hydrolysis, and photolysis. Biological mechanisms in soil and living organisms utilize oxidation, reduction, hydrolysis, and conjugation to degrade chemicals. The process of degradation will largely be governed by the compartment (water, soil, atmosphere, biota) in which the chemical is distributed, and this distribution is governed by the physical processes already mentioned (i.e., sedimentation, adsorption, and volatilization).
The impact of the changes in the chemical state of organic chemicals on the environment is only partially elucidated, but will be significant in many cases. Atmospheric abundance of radioactive gases could lead to substantial drift in the climate of the earth, including changes in temperature and precipitation, and in the frequency of occurrence of extreme events (such as hurricanes). Ecosystem damage and problems related to human health also result from regional and global pollution, such as acid rain (also called acidic precipitation), which can vary between mildly acidic and strongly acidic on the pH scale (Fig. 1.2) and can suppress life and, together with enhanced ozone levels, can lead to forest damage. In fact, when assessing the impact of chemicals on the environment, the most critical characteristics are: (1) the type of chemical discharged, which depends on the type of industries and processes used, and (2) the amount and concentration of the chemical. Solid wastes (containing chemicals) and/or gaseous emissions generated from industrial sources also contribute to the amount and concentration of chemicals in the environment.