ASSESSMENT OF RAPESEED (Brassica Napus L.) EFFICIENCY FOR PHYTOREMEDIATION OF HEAVY METAL-CONTAMINATED SOILS

Soil pollution with toxic pollutants, including heavy metals (HMs), has become a serious global problem. One of the most economically and environmentally feasible alternatives applied for the remediation of HM-polluted sites is the phytoremediation technique. Rapeseed (Brassica Napus L.) belongs to Brasicaceae, and was selected in this work as a model crop for the phytoremediation of pollutes soils, since it is a well-known metal-tolerant plant and widespread in Romania. Therefore, our paper investigated the tolerance and accumulation capacity of Brassica Napus L. for different heavy metals (Ni(II), Co(II), Cu(II) and Zn(II)) from polluted soils. The experiments were performed in greenhouse conditions for 41 days. The plants were grown in polyethylene pots containing 650 grams of soil taken from the Dersca–Dorohoi peat field in the N-E part of Romania, which was artificially contaminated with different levels of metals. After 42 days of growth, the plants were sectioned into two parts (roots and stems with leaves), washed and dried at 105^oC and then subjected to wet mineralization. The samples were analyzed via flame atomic absorption spectrometry (AAS) in order to determine the quantity of metals accumulated in various parts of the plant. To assess the degree of accumulation of metals in plants, the bioconcentration factor (BCF), bioaccumulation coefficient (BAC) and translocation factor (TF) were considered. Our results revealed that Brassica Napus L. is not a heavy metal hyperaccumulator and is not suitable for phytoextraction at high metal ion concentrations, at least under the conditions tested and for the soil type considered. However, Brassica Napus L. has the potential for Ni, Co and Zn immobilization in roots, since BCF >1 and TF <1 for some treatments tested (levels around 10 to 290 mg/kg of pollutant in soil). Since BAC<1 for all treatments, the tested plant may be considered a metal shoot excluder.