Modeling Anthropogenic Substances

The research published in this book uses the presently most comprehensive multicompartment model, the first which comprises a coupled atmosphere-ocean general circulation model (GCM). GCMs are the state-of-the-art tools used in climate research. The study is on the marine and total environmental distribution and fate of two chemicals, an obsolete pesticide (DDT) and an emerging contaminant (perflu-orinated compound) and contains the first description of a whole historic cycle of an anthropogenic substance, i.e. from the introduction into the environment until its fading beyond phase-out. 

With these five equations (Eqs. 23-42 to 23-46), two of them partial differential equations, the limits of the analytical approach and the goals of this book are clearly exceeded. However, at this point we take the occasion to look at how such equations are solved numerically. User-friendly computer programs, such as MAS AS (Modeling of Anthropogenic Substances in Aquatic Systems, Ulrich et al., 1995) or AQUASIM (Reichert, 1994), or just a general mathematical tool like MATLAB and MATHE-MATICA, can be used to solve these equations for arbitrary constant or variable parameters and boundary conditions. 

Ulrich, M. M., D. M. Imboden, and R. P. Schwarzenbach, MASAS - A user-friendly simulation tool for modeling the fate of anthropogenic substances in lakes , Environ. Software, 10, 177-198 (1995). 

It is now universally accepted that chemicals of commerce and those that may be formed inadvertently by processes such as combustion should be subjected to evaluation for their possible adverse effects on humans, the environment, and its various ecosystems. Earth surface processes are continually active with atmospheric, oceanic, and terrestrial media forces that foster chemical mobilization with long-range chemical transport within continental land masses, across the oceans, and on a global scale between the hemispheres. Monitoring data from remote locations provide evidence of this transport and these assertions are confirmed by the theoretical results of a variety of multimedia chemical fate and transport models. At the local level, the other geographic extreme, chemical sources are more intense and the pathways shorter and the impacts are therefore more severe. Anthropogenic substances have been mobilized and now exist in every nook, cranny, and recess of the physical environment and within many biological species. 

These types of models, while incomplete, are steps toward the formulation of composite models, which depend on future availability of compositional data. Moreover, these structural models are an important aid in understanding the interactions between anthropogenic chemicals and terrestrial organic matter. However, due to the heterogeneity of humic substances in the environment, provision of an exact, general structure does not seem feasible. 

In the works devoted to study and development of MEISs numerous examples on their application to the analysis of various problems were certainly presented. They are formation of harmful substances during fuel combustion and cleaning of combustion products from these components, fuel processing, atmospheric pollution with anthropogenic emissions, stationary and nonstationary flow distribution in hydraulic systems, etc. These examples should illustrate practical efficiency of MEISs, their capabilities for revealing specific features of the modeled process and determining directions of its improvement. 

Estimates of annual amounts of emissions released into the earth s atmosphere are remarkably different from each other, depending on the choice of balance models [5-24]. For the anthropogenic sources, the following substances may be listed in decreasing order of importance carbon dioxide, carbon monoxide, sulphur oxides, hydrocarbons, nitrogen oxides and liquid and solid particles. A summary of relative contributions of these substances to total emissions of main types of anthropogenic sources is given in Table 5.8. 

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