engleski

SORPTION OF POTENTIALLY TOXIC METALS IN A GLEYSOL PROFILE AT THE VELIKA GORICA SITE (ZAGREB, CROATIA)

Potentially toxic metals (PTMs) form the important group of substances causing contamination of soil and groundwater. The subject of this study is a Gleysol profile developed in the vicinity of the Velika Gorica wellfield area of the Zagreb aquifer, Croatia. The main aims of the investigation were: a) to determine the sorption characteristics of zinc, copper and cadmium using a batch experiment and b) to build isotherms of PTMs in order to detect the potential impact of pollution on groundwater. Potential sources of contamination near the sampling area are traffic and intensive agriculture. Mathematical expressions were applied to establish the relationship between the concentration of the adsorbent in the liquid phase and the solid phase at equilibrium and in laboratory conditions. Relative sorption capacity was also used to compare the metal sorption capacity of the samples. Freundlich distribution coefficients were determined from sorption isotherms, and the sequence is Cu > Zn > Cd. The comparison of sorption isotherms has shown that Cu has the strongest sorption in the soil. Cu showed retention of 49 %, Zn of 32 %, while only 24 % of Cd is sorbed at this soil horizon (2Ag2). This can be explained by physical-chemical properties of soil horizon such as finer particles, the highest CEC values and OM content. Monitoring of Cd concentrations with depth in this type of soils is needed in order to quantify leaching of cadmium to the groundwater of the Zagreb aquifer system.

groundwater vulnerability, Freundlich isotherms, PTMs, soil contamination

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