Study of heavy metal uptake of Populus nigra in relation to phytoremediation

Introduction The emission of heavy metals due to anthropogenic activities is an increasing risk for the plant-animal-human food chain. Phytoremediation is regarded as an environmetal friendly cleanup method to rehabilitate soils, sediments or groundwater contaminated with inorganic or organic contaminants (Kimives et al., 2005; Mathene Gaspar and Anton, 2004; Robinson et al., 2006). There are many different kinds of pyhtoremediation technique based on processes of plant uptake such as phytostabilization, phytoextraction, phytovolatilization, rhizofiltration and phytodegradation. Phytoextraction is often used technique to remove heavy metals (HM) from soil and translocate HM’s into plants. Most of HM are accumulated in tissues of roots but several elements are translocated into the above-ground plant tissues. Uptake of heavy metals into plants through roots depends on the plant’s uptake efficiency, the transpiration rate, microbial activities in the rhizoshpere, the HM types and concentration and several soil factors (Adriano et al., 2004; Dietz and Schnoor, 2001). Poplars seem to be favorite and commonly used test plants (Quinn et al., 2001; Takacs et al., 2005) in phytoremediation due to their rapid growth rates, high evapotranspiration rates and ease of propagation. They have tolerance to a wide range of environmental conditions and ability to take up high levels of some contaminants (Quinn et al., 2001; Robinson et al., 2006). On the other hand, they are not part of food chain definietly. We investigated the heavy metal accumulation of poplar trees (Populus nigra) as test plants from soil loaded with five HM's (Cd, Zn, Pb, Ni, Mn) in a pot experiment. Concentrations of HM’s in roots, shoots and leaves were compared in different harvesting times (after 2, 4, 6 and 8 monthes).