English Abstract For a variety of environmental studies it is useful to
get a quick impression of how certain tracers penetrate the soil. Under
some restrictive assumptions, it is possible to predict the concentration
and the amount of material which has passed, and which is present, below
some level without the detailed knowledge of the structure of the soil
matrix. In this report a survey is given of formulas describing the
behaviour of a tracer without or with decay with linear adsorption in a
one-dimensional semi-infinite medium with various boundary conditions.
These boundary conditions are: instantaneous injection or exposure,
continuous injection or exposure, or block pulse injection or exposure.
Interest is focussed on the questions at what time a specified amount of
material is present below or has passed a givin depth. A computer program
is described which supplies an answer to this question (ZEROCD). Another
computer program (PROFCD) visualizes all relevant results (resident and flux
concentration, resident and transported mass, fraction of resident (or
transported) mass to total injected amount). Although the underlying
assumptions may be too simple for realistic situations, yet, by varying the
input parameters, the user can find upper and lower bounds for various
unknowns (e.g. concentration, time of arrival and so on), without much
modelling effort, because the time of calculation of both programs is very
short. The latter may also facilitate the performance of a formal
uncertainty analysis. Furthermore, its very short calculation time makes
this software package pre-eminently useful to produce a first, rapid
assessment of the evolution of pollution in a wide range of typical soil
profiles within the framework of large scale environmental studies. Another
application of the programs is the possibility to serve as a reference for
verification of numerical computer codes, a key element of the INTRAVEL
project.