engleski

Application of phytoremediation for heavy-metal removal using common wild plant species in green city areas of Varaždin, Croatia

Phytoremediation is a method for removing various types of contaminants from the environment using plants. This method has proved highly efficient for the removal of heavy metals. As is known, heavy metals in high concentrations are very toxic for living organisms. They are usually present in the soil, below certain concentrations as a result of the soil’s mineral content, and above certain concentrations as a result of pollution from various sources: fossil-fuel consumption (traffic, industry, households), landfills, waste water, agriculture (mineral fertilizers and pesticides) etc. The aim of this study was to examine how common wild plants can successfully remove heavy metals from green city areas. During June and July 2013, in 16 locations in Varaždin, soil and plant samples were collected from precisely defined areas. Three plant species were examined: dandelion (Taraxacum officinale agg.), ribwort plantain (Plantago lanceolata L.) and white clover (Trifolium repens L.). The following heavy metals were detected: cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), nickel (Ni) and zinc (Zn). For the detection of the amounts of heavy metals, the method of atomic absorption spectrometry was used. In the soil samples for eight locations, maximum allowed amounts of heavy metals were exceeded. In plant samples, the highest accumulation of cadmium was recorded in Taraxacum officinale, with 0.945 mg/kg ; of copper, in Plantago lanceolata, with 239.03 mg/kg ; of iron, in Plantago lanceolata, with 246.25 mg/kg ; of manganese, in Taraxacum officinale, with 49.60 mg/kg ; of nickel, in Taraxacum officinale, with 5.498 mg/kg ; of lead, in Plantago lanceolata, with 3.88 mg/kg ; and of zinc, in Trifolium repens, with 216.50 mg/kg. The levels obtained could have practical value in the process of removal of heavy metals from contaminated soils by phytoremediation. The advantage of the use of common wild plant species is that they do not need to be sown. Furthermore, green city areas are mown, on average, 10 times during the growing season, and in this way a considerable amount of swath biomass, and hence heavy metal, can be removed. Accordingly, it can be concluded that common wild plants can be used for phytoremediation of heavy metals in an environmentally-friendly and inexpensive way, but over a lengthy period. Besides contaminated green city areas, this method can be applied to other contaminated surfaces with similar climatic conditions.

Croatia; heavy metals; phytoremediation; Varaždin; wild plant species

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