Analysis and simulation of bioaccumulation of selected metals from contaminated soil

Abstract

The aim of this study was: I) to determine Pb, Cd and Zn concentrations in alluvial soil before and after planting selected plant species, and II) modeling of the bioaccumulation process in the examined soil, using several plant species. Soil samples were collected from the northern part of Kosovo and Metohija, and the selected plants were: a) vegetables: Lactuca sativa L. and Allium cepa L.; b) legumes: Lotus corniculatus L. and Trifolium pratense L.; and c) grasses (weed plants): Cynodon dactylon (L.) Pers. and Festuca arundinaceae Schreb. The experimental part of the work was carried out by vegetation experiments, and heavy metal concentrations were determined by potentiometric stripping analysis (PSA). The obtained results show that: I) the heavy metal concentrations in the analyzed soil were above allowed values at all measuring points; II) the selected species accumulated heavy metals to some extent. Expressed in percentages, vegetables and legumes accumulated 9?11 % Pb, 12?33 % Cd and 11?19 % Zn. Cyndon dactylon Pers. accumulated about 69 % Pb, 24?40 % Cd and 43 % Zn. Festuca arundinaceae accumulated 39?40 % Zn, 58?81 % Cd, and Pb up to 70 %. The obtained results indicate high tolerance to heavy metals, especially in the case of Festuca arundinacea. By simulation of the bioaccumulation process it has been established that the dependence of the concentration of metal ions before and after planting represents a linear regression. Coefficients of the model, for the discussed cases of heavy metals and plant species, were determined by minimization of the mean square error, and quality of model fits was evaluated by the values of the statistical indicators the RSE (Residual Standard Error) and MRE (Mean Relative Error). The closer the values of these indicators are to zero, the more accurate the model is. It can be concluded that the adopted model describes sufficiently well the dependence of concentrations of Pb and Zn in the soil before and after planting. The mean relative error (MRE) in the case of Cd is slightly higher than 7 %, which suggests that the use of a non-linear model is needed for which it is necessary to have additional samples available, which can be the subject of further research.