Mathematical models and their significance in environmental chemistry. The soil

The practice of using the soil as a final destination for industrial residues and for biological and non biological processes, requires great caution considering that the soil is the last active barrier against the dangers of diffusion in the environment of hazardous substances. Studies can no longer be limited to the single processes which intervene in the interactions between chemical substances and the soil, and a more complete assessment of the problem in quantitative terms is becoming more and more necessary and urgent. In this context, mathematical modelling has a fundamental importance. Three models are here presented applied to the transformations of chemical products in the soil: the fate of thiocarbamate herbicides in the soil system, the effect of atrazine on denitrification, the effect of atrazine on the transformations of a nitrogen fertiliser (urea). There is also an illustration of the complex structure of the environmental data and a description of how the stochastic movement of water determines the humidity profile of the soil and hence the movement of soluble compounds.