Assessment of Heavy Metals and Antioxidant Enzyme as Bioindicators with their Spatial Variation along the roadside Vegetation of Islamabad (T-1323) (MFN 6259)

Abstract

Air pollution monitoring using plants as bio indicators is emerging as potentially effective and economic approach to assess air pollution. The present study focused on biomonitoring of air pollution in Islamabad road ways. In the study both plant species (Dalbergia sissoo & Bauhinia varigeta) utilized as bio monitors for heavy metals assessment along roadside vegetation of Islamabad main roads. For the purpose the plant tissues (leaf and bark) and soil was sampled from different locations. Samples were thoroughly digested and analysed by using atomic absorption spectrophotometer (AAS). Concentration of Pb, Cd, Cr, Ni and Mn were determined in samples of leaves, barks and soil at 9 selected locations in both plants. The mean concentration of metals in the various locations along the roadside were in the order Cr > Cd > Pb in leaves of both plants. The mean concentration of metals in barks were in the order of Cr > Cd > Pb > Ni > Mn. whereas in soil only Ni concentration was higher than the permissible limit. Only Cr showed high level of pollution index (IPI) in Dalbergia sissoo while pollution load indicates the quality is deteriorated at the four sites (Pirwadai, IJP Road, Golra Mor, Sareena Hotel). Interpolation maps were developed to hotspot the spatial variation of metal contamination by Pb, Cr, Cd, Ni and Mn in the study area. Plants response to heavy metal stress via enzymes, though antioxidant enzymes (SOD, CAT, and GPOX) activity was analysed in the same samples. The results revealed that heavy metal stress increased the activities of all three antioxidant enzymes (SOD, CAT, GPOX) despite of differential inducement among metals in both plant species. Results identified metal accumulation in plants from nonlethal and increased concentration, also suggested that Dalbergia sissoo is more tolerant to heavy metal stress as compared to Bauhinia varigeta, which can clean up ambient air and can be used as phytoaccumulator to reduce soil pollution load.