Investigation of precious metals; Cu, Ag and Au in soil of Dir lower Pakistan: a phytoremediation approach using deep feeder eucalyptus leaves

This study was aimed to determine precious metals in the hilly regions of Lower Dir, a district in Pakistan through phytoremediation approach using leaves of a deep feeder Eucalyptus. Precious metals; Cu, Ag, and Au were targeted. Soil and leaves samples from 30 different localities were collected. Soil samples were dried in oven and then digested, the leaves samples of Eucalyptus were also dried, and digested. Both soil and leaves samples of Eucalyptus were subjected to elemental analysis through atomic absorption spectrometry. Concentration of Cu was high in soil samples of Ramyal, Chakdara and Khawas (3.096 mg/Kg, 0.723 mg/Kg and 0.588 mg/Kg respectively) whereas concentration of Cu in leaves samples of Eucalyptus was high in samples collected from Ramyal, Badwan, and Bombolai respectively as; 2.003 mg/Kg, 0.164 mg/Kg and 0.106 mg/Kg. Au was not detected in any sample. The highest concentration of Ag in soil was found in samples collected from Qala Asbanr, Shamlai and Khawas (0.351 mg/Kg, 0.058 mg/Kg and 0.036 mg/Kg), while highest concentration of Ag in leaves samples of Eucalyptus was found in samples collected from Qilla, Bombolai and Khawas as; 0.048 mg/Kg, 0.036 mg/Kg and 0.029 mg/Kg respectively. The bioconcentration factor was also calculated and was found higher for the samples collected from Ramyal Chakdara, Trai Timergara, Shamlai Chakdara and Badwan as; 0.646, 0.625, 0.561 and 0.504 respectively for Copper whereas no Gold uptake was recorded. The higher bioconcentration values recorded for Ag were 0.888, 0.805, 0.538, and 0.395 for samples collected from Badwan, Khawas Asbanr, Turnow Asbanr and Bombolai Asbanr respectively. The findings of the study suggest that copper and silver reservoirs are there in the selected areas which needs to be explored by government agencies whereas no gold is present in these areas.