The study makes an attempt to assess the impact of uncontrolled waste dumps on soil chemical and biochemical properties. Investigations were carried out on five waste disposal sites situated in the south-eastern outskirts or the city of Lublin. The samples of soils collected from the adjacent arabic land were used as reference material. In soils of four landfills, which were established relatively recently (lour to five years ago); several times higher activity of the examined enzymes (dehydrogcnascs, acid phosphatase, basic phosphatase, urcasc, protease) than in the soils from the adjacent cultivated land was determined. Opposite ti-ends were found in the case ofa waste dump established 20 years ago. The determined lack ofnegative influence or the examined waste dumps on the soil chemical and biochemical properties of the adjacent arabic land shows that the range or the contamination effect on the surrounding area was limited.

Consider the semilinear system defined by

x(i+1) = Ax(i) + f(x(i)), i≥ 0

x(0) = x0 ϵ ℜn

and the corresponding output signal y(i)=Cx(i), i ≥ 0, where A is a n x n matrix, C is a p x n matrix and f is a nonlinear function. An initial state x(0) is output admissible with respect to A, f, C and a constraint set Ω in ℜp if the output signal (y(i))i associated to our system satisfies the condition y(i) in Ω, for every integer i ≥ 0. The set of all possible such initial conditions is the maximal output admissible set Γ(Ω). In this paper we will define a new set that characterizes the maximal output set in various systems (controlled and uncontrolled systems). Therefore, we propose an algorithmic approach that permits to verify if such set is finitely determined or not. The case of discrete delayed systems is taken into consideration as well. To illustrate our work, we give various numerical simulations.