engleski

Competitive sorption and desorption of trace elements by bulk soil and its organo-mineral fraction

The alteration of soil conditions may result in the release of the TMs loads into the soil solution, thereby causing groundwater pollution and/or contamination of plants. Therefore, the aim of the study were to investigate competitive sorption behaviour of TMs (Cd, Cu, Ni, Pb and Zn) and identify soil characteristics that most determines the retention and mobility of heavy metals using 15 soil samples from two different types of karst poljes (Adriatic area, Croatia). Taking into account that sorption and retention of TMs in soil substantially depend on organic ligands that form stable organo-mineral complexes, sorption and desorption experiment was carried out on two soil fractions – bulk soil and its organo-mineral fraction (OMF). The highest sorption and retention capacity of bulk soil and OMF was determined for Pb and Cu, which compete for the same sorption sites, mostly on active surfaces of OM. Furthermore, the lowest sorption and retention capacity of bulk soil and OMF was found for Cd, Ni and Zn, which compete for the common sorption sites on the oxides and clay minerals that have a greater sorption capacity for the mentioned metals. It is concluded that when there is metal competition in soil, Pb and Cu are most strongly sorbed and retained metals, which makes them less bioavailable. In contrast, Cd, Ni and Zn are the least sorbed and retained metals in soil, and therefore may pose environmental risk.

trace metals; competitive sorption; sorption capacity; organo-mineral fraction; environmental risk

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