ABSTRACT
There are several million different chemical compounds known to us and 100,000 of these chemicals have environmental interest as they have industrial use and can be found in our everyday products. They are a threat to our environment and health (see Chapter 6). These compounds can, as all chemical compounds, participate in chemical reactions in the environment and are thereby transformed to other compounds. The properties of the compounds (see Chapter 3) determine the distribution in the sphereslithosphere, hydrosphere, atmosphere, and technosphere. The ability to decompose has also been mentioned, and this process determines the time a compound remains in the environment. The decomposition can either be chemical or microbiological. This chapter mainly focuses on the chemical reactions in the environment of the emitted chemical compounds, including the chemical decomposition processes, but it also covers a few important physical processes that determine the transfer processes between the spheres. It is very important to perform calculations of these possible processes because they determine in which sphere and with which chemical compound we are dealing as a result of these transformation processes, and it determines thereby the environmental and health effect. To mention two illustrative examples: (1) It is important whether a toxic substance is in the atmosphere or in the lithosphere-just consider sulfur dioxide. (2) Heavy metals are able to form complexes, for instance, with chloride ions and the complexes have a completely different solubility, mobility, and effect (the toxic effect is usually much less). It is implicit that cadmium is much less toxic in a marine environment than in freshwater bodies. This chapter presents the chemical reaction calculations, where the equilibrium calculations are crucial. A method to use graphic representation to overview the different possible compounds by the equilibrium will be a core topic. It is possible to make the calculations without the graphs, but in this context it is preferable to use and demonstrate the graphic method because the results are given as very illustrative graphic overviews. Owing to the possibilities for fast calculations using computers, it is not necessary to use
the graphic method, but the graphs present a good overview of the different components and their concentration. A few physical-chemical calculation methods that we have not yet covered in Chapters 3 and 4 are also included to ensure that we can answer the crucial question: Which components at which concentrations do we have and where in the environment? The calculations included in this chapter focus on the distribution among the atmosphere, hydrosphere, and lithosphere by the presentation of Henry’s law and adsorption isotherms. In this context, we discuss the estimation methods in addition to what is covered in Chapter 4. Examples have been used throughout the chapter to give the best possible illustration of the calculation methods.
