Bio- accumulation of Cd, Cr, Cu, Ni and Pb in a wild grass, Parthenium hysterophorus L. Asteraceae, growing naturally on barren land and evaluation of phyto-extraction potential of the plant for studied metals

Because of the inbuilt bio-accumulation mechanism several plants have shown a remarkable capability of accumulation of metals from contaminated soil into roots, tubers and upper parts of the plants. This study was undertaken to evaluate the bio-accumulation potential of a wild grass, Parthenium hysterophorus L., Asteraceae grown on the barren land along with the National highways for Cd, Cr, Cu, Ni and Pb by determining the bio-accumulated levels of these metals in the samples of soil, roots and shoot of the plant. The various bio-concentration factors (BCFs), translocation factors (TFs) and Biological accumulation coefficients (BACs) for studied metals were evaluated, to find out the suitability of Parthenium plant for phyto-extration of the studied metals. The order of observed levels of heavy metals in the samples of soil, root and shoots were: Pb (8.12±0.48) > Cr (7.18± 0.39) > Cu (5.64± 0.26) > Ni (3.91± 0.21) > Cd (1.31± 0.08) and Pb (6.67± 0.34) > Cu (6.11 ±0.27) >Cr (6.05± 0.23) >Ni (4.14± 0.18) > Cd (1.42± 0.11) and Pb (7.22±0.29) > Cr (5.97±0.23)>Cu (5.96 ±0.25)>Ni (5.13±0.21) > Cd (1.70±0.14 mg/Kg, dw), respectively. The soil to roots bio-concentration factors, BCFRoot for studied metals were: Cd (1.08) > Cu (1.08) >Ni (1.06) > Cr (0.84)>Pb (0.82). The order of root to shoot translocation factors, TFShoot for these metals in Parthenium hysterophorus L., was: Ni (1.24) > Cd (1.20) > Pb (1.08) > Cr (0.99~1.00)> Cu (0.98~1.00). The various soil to shoot biological accumulation coefficients, BACShoot for studied metals in Parthenium plant were, Ni (1.31) > Cd (1.30)> Cu (1.06) > Pb (0.89) >Cr (0.83), respectively. Comparatively higher BCF >1, TF >1 and higher BAC values for metals under study suggested that the plant Parthenium hysterophorus L has potential to translocate these metals to the above ground parts of the plants and thereby their phyto-extraction from contaminated soil.