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[Visitor (58.214.*.*)]answers [Chinese ]Time :2020-07-25
Environmental geochemistry mainly studies the chemical properties of the human environment, studies the migration and transformation laws of pollutants in the environment, and studies the impact of environmental chemicals on organisms and human health.

From the perspective of geochemistry: the human environment can be divided into five geochemical systems, namely, surface lithosphere system, atmospheric system, water system, soil-biological system and technological system. In order to improve the quality of the human environment, it is necessary to deeply understand the geochemical properties of these systems. These systems are gradually evolved and produced sequentially in the course of geological history, and their chemical properties are constantly changing.
In modern times, humans have used powerful technology to change the face of nature on a large scale. A large number of chemical substances have been excavated from the depths of the earth's crust, and more and more types and numbers of compounds that do not exist in nature have been synthesized. Some of them are inevitably spread into the environment. On the basis of the original environmental material cycle, these new material cycles are superimposed, which has a serious impact on the quality of the human environment.

One of the important tasks of environmental geochemistry is to study the processes and trends of modern environmental chemistry changes in a timely manner. On the basis of the original geochemistry, we can further study the geochemical properties of the various systems that make up the human environment.
The pollutants emitted by man-made pollutants continuously move in space and change their existing forms in the environment. The result of this migration and transformation can develop in a favorable direction, such as the dilution, diffusion, decomposition, and even disappearance of pollutants; it can also develop in an unfavorable direction, such as the accumulation of pollutants under certain conditions and transform into a lasting Secondary pollutants.

The existence of pollutants in the environment can be constantly changed through various chemical actions, such as dissolution, precipitation, hydrolysis, complexation and integration, oxidation, reduction, chemical decomposition, photochemical decomposition, and biochemical decomposition.
Pollutants exist in different forms, and their toxicity is often different. For example, the toxicity of hexavalent chromium is greater than that of trivalent chromium, and the toxicity of copper complex ion is less than copper ion, and the more stable the complex ion, the less toxicity.

Pollutants exist in different forms, and organisms can absorb them differently. For example, rice is easy to absorb metal mercury and methyl mercury, but does not absorb mercury sulfide. In environmental pollution research, not only the total amount of pollutants, but also the form of pollutants must be studied.

In a specific environment, the existence of pollutants depends on the geochemical conditions of the environment, such as environmental acid-base conditions, oxidation-reduction conditions, the type and quantity of colloids in the environment, and the quantity and nature of organic matter in the environment.
The study of geochemistry shows that every specific area on the surface of the earth has its unique geochemical properties, so applying the principles and methods of geochemistry can better clarify the migration and transformation laws of pollutants in the environment. Research in this area is helpful for evaluating environmental quality and predicting the trend of environmental quality changes; helping to understand nature's natural purification capacity for pollutants; helping to formulate environmental standards and formulating measures to transform the polluted environment.
Environmental geochemistry is developed on the basis of biogeochemistry. Regarding the relationship between environmental elements and life elements, as early as the 1940s, biogeochemical research pointed out that the chemical elements contained in organisms are proportional to those in the biosphere; the main elements that make up organisms are all in the biosphere. Elements that easily form gases and water-soluble compounds.
The composition of the human body is the result of human beings' metabolism and material exchange with the environment over a long period of time, and the establishment of a dynamic balance through processes such as heredity and mutation. Obviously, the various chemical substances released by humans into the environment will inevitably enter the organisms and human bodies to varying degrees. When the body tissues cannot tolerate these substances, serious consequences will occur. The Minamata disease caused by mercury pollution and the pain disease caused by cadmium pollution are prominent examples in this regard.
The task of environmental geochemistry in this area is not only to study the relationship between the changes of modern environmental chemical composition and life, the chemical composition of the human body, and human health, but also to study the relationship between cosmic elements, crust elements, marine elements and life elements in a broader geological background. Research on the geochemical evolution of life processes and other issues.

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