A KINETIC APPROACH ON THE ESTIMATION OF IRON UPTAKE BY APIUM-NODIFLORUM PLANTS

A kinetic approach was developed to indicate the inherent capacity of aquatic plants to absorb heavy metals. The concept was based on the hy pothesis that heavy metal uptake by plants follows a first-order mathe matical model depending on the heavy metal concentration in the biomas s of this plant. This method enabled the evaluation of two parameters: (i) the specific metal uptake rate (k) and (ii) the maximum specific content (E-pl,E- infinity) of this metal in the aquatic plant. The spe cific uptake rate coefficient of the metal depended upon the concentra tion of the metal in the liquid phase, as can be seen from a Michaelis -Menten-type equation. This equation has two constants: (i) a maximum specific metal uptake rate (k(max)) and (ii) a K-S coefficient. The ma ximum specific uptake rate coefficient was useful in the evaluation of the ability of different aquatic plants to absorb specific heavy meta l, as well as in the evaluation of the selectivity of absorption betwe en two or more metals by the plant. The maximum specific heavy metal c ontent can be used for quantitative evaluation of an aquatic plant's a bility to select this heavy metal. The ability of an aquatic plant to clean its aquatic environment from the metal can be evaluated in terms of the K-S-coefficient. An example of this kinetic approach is given by using Apium nodiflorum. Experimental data from an aquatic system of Apium nodiflorum were collected and applied to the proposed kinetic a pproach for the estimation of parameters E-pl,E- infinity k(max) and K -S of the proposed kinetic model, whereas the adequacy of the model wa s examined by simulating a real process and comparing the predicted an d measured values using chi(2)-test.