ALEXANDRA DANA CHITIMUS, VALENTIN NEDEFF, ION SANDU, CRISTIAN RADU, EMILIAN MOSNEGUTU, IOAN GABRIEL SANDU, NARCIS BARSAN MATHEMATICAL MODELING FOR THE ABSORPTION CAPACITY OF HEAVY METALS FROM THE SOIL IN THE CASE OF PHRAGMITES AUSTRALIS PLANT SPECIES This paper proposes a tridimensional mathematical model of the absorption capacity of heavy metals (cadmium and nickel) from the soil in the case of Phragmites Australis plant species (the soil and plant samples was taken from six locations/areas along the Bistriþa and Cracãu Rivers, belonging to the Siret hydrographic basin). The variable measures taken into consideration when carrying out the experiments and realizing the mathematical model are the distance from the water-soil interface from which the plant samples were taken and the concentration of the heavy metals in the soil. The mathematical model was elaborated and tested by means of the TableCurve 3D program used for generating linear and non-linear equations. A very high absorption capacity of cadmium from the soil was recorded A very high absorption capacity of cadmium from the soil was recorded, in the case of Phragmites Australis plant species (190÷234 % higher than in the soil). The correlation coefficient of the mathematic model was between 0.90 and 0.98.