Microbiological transformation transport processes

The introduction of chemicals into the environment is considerable. Large amounts of organic compounds are released into the environment every year by industrial and agricultural processes, traffic, urban waste disposal and ecological disasters. Once present in the environment, they are subjected on the one hand to transport processes in air, water and soil and, on the other hand, they are subjected to the influence of the reactor environment , i.e. transformation products may be formed by chemical, photochemical and microbiological transformation processes. Chemical reactions with other pollutants present in the environment can also take place. As a result of these processes, a variety of new and unexpected compounds can be formed from the originally released pollutants and, as a rule, they are more polar than the parent compounds. 

Besides its low natural concentrations, Hg is mostly anthropogenically introduced into the environment. The anthropogenic sources of Hg are numerous and worldwide. The annual emissions are estimated to be between 2700 and 6000 tons. The global cycle of Hg involves the emission of the metal from land and water surfaces into the atmosphere, its transport in the atmosphere on a global scale, possible conversion to unidentified soluble species, and return to land and water by various depositional processes [4]. In the aquatic system numerous transformations take place, which are mainly microbiological processes. An overview of the most common Hg species in the environment is given in Figure 22.1. 

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