State of Art in

Theoretical Models

Thermodynamics. Despite certain limitations, thermodynamics models can be very useful as the first approximation of the natural systems. The main advantage of thermodynamics is its simplicity. In the last two decades, a large amount of data on the properties of materials at equilibrium has been acquired. Although much progress has been made in understanding the application of thermodynamics to natural systems, actual composition of natural systems differs in most cases from the one predicted on the base of equilibrium models. There are several reasons for discrepancies between the real system and the equilibrium model (incorrect or insufficient initial data, chemical equilibrium reactions omitted in formulation of the model, reaction rates so low that equilibrium is only slowly attained in the real system, the natural system may not be closed). In the thermodynamics models, principal changes of their concept being not expected, the principal role of the Theoretical Models Subgroup will lie in gathering a consistent set of data concerning weathering processes, and formation of a concise database.

Kinetics. Up to now, the kinetic treatment of the chemical evolution and geochemical cycles had mostly been limited to the use of simple concepts. However, recent strong anthropogenic perturbations of the geological systems necessitate further investigation of the dynamic response of the geochemical cycle to such perturbations. In particular, the influence of positive and negative feedback processes on the distribution and speciation of elements in the geological environment must be much more seriously and quantitatively evaluated.

The study of kinetics is inherently more difficult than that of thermodynamics, as the time-dependent processes are path-dependent. The application of kinetics to problems of natural systems is still in the initial stage. For many natural systems, kinetics is the controlling factor, deciding their fate and evolution. This statement fully applies to weathering. More and more sophisticated instrumental methods will sure bring new results necessary to explain theoretically; on the opposite, the fenomenological approach is also expected to gain new impulses.

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Laboratory Experiments

Many of the above indicated theoretical solutions to problems encountered in weathering processes have been proposed or verified on the base of laboratory experiments. These experiments ranged from simple dissolution of single minerals through multiphase systems - from rocks at ambient conditions to specific environments (e.g. marine environment, acid mine drainage, acid precipitations etc.). The greatest obstacle hindering the more universal use of experimental data is the diversity of examination approaches, experiment arrangements and analytical methods used in their monitoring. Another serious shortcoming of weathering experiments is the insufficient duration of these experiments, usually not exceeding weeks. Short-time experiments (in terms of tens to hundreds of hours - most of the recent studies) are still too short, enabling to understand only the initial stages of the entire process.

Nonetheless, interesting results have already been obtained. One example for all: it has been recently found out, that introduction of strontium in the structure of gypsum substantially decreases the solubility of this mineral phase, produced in enormous quantities in desulphurisation of flue gases and can thus prevent the toxic elements incorporated therein to be released from the resulting waste in the aquatic phase. Search for additives to the weathering environment, serving as potential scavengers of potentially hazardous elements, is another very beneficial research trend.

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Applied Research

The applied research in anthropogenic weathering covers a very large area. It ranges from more or less observative investigation of paths, extent, and weathering rate of certain rocks and inorganic man-made materials derived from mineral matter to interactive validation of theoretical conclusions and experimental results.

The very broad range of applied research related to anthropogenic weathering requires worldwide summarisation, confrontation of results, and identification of gaps to be covered by the future research. The presented project will try to solve all these tasks.

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There is only little chance to suppress the ongoing deterioration of rocks integrated to our environment, or in some instances even lead it to a halt without a coordinative, unified approach of concerned researchers on an international level. Though still increasing, the number of scientists and institutions engaged in environmental research appears to be insufficient, unless such coordination is achieved and limited financial and manpower resources used in the most effective way. Prevention of research doubling, generally agreed choice of intercorrelative sampling-, analytical- and experimental methods, rapid communication of results is the least we can do to contribute to restoration of the already seriously damaged environment.

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