Biomonitoring of Lead (Pb2+) And Cadmium (Cd2+) Pollution Emitting From Automobiles on Motorway (M-3) And National Highway (N-5), Pakistan

study was carried out to estimate metal pollution lead and cadmium (Pb2+ and Cd2+) emitting from automobiles and selection of suitable metal indicators which reflect the pollution level in the atmosphere.Two roads i.e. Motorway (M-3) and National Highway (N- 5) were selected for the purpose of study.The dust and plant samples were collected and Pb2+ and Cd2+ contents were recorded at five selected sites of M-3 and N-5.The dust and plant samples 50 m away from both roads were kept as reference control while soil control were taken 15 m away due to irrigated field started and analyzed for Pb2+ and Cd2+ profile.The maximum Pb2+ concentration (conc.) i.e. 0.00075 mg g-1 was observed in dust samples of Hojan Town and minimum conc.(0.00016 mg g-1) was recorded in Kamalpur Sargodha road.The data collected from N-5 showed maximum Pb2+ conc.(0.000244 mg g-1) at ZIS-textiles and minimum Pb2+ conc.(0.00042 mg g-1) for roadside side dust samples.The maximum Pb2+ conc.(0.00044 mg g-1) was found in roadside soil of Hojan town than that of control (0.00018 mg g-1) at M-3 while the high Pb2+ value (0.0032 mg g-1) for roadside soil samples of Sitara valley was followed by conc. (0.00021 mg g-1) recorded for Chak.No. 60 Saudagarpur to their respective controls at N-5.All the gas exchange attributes like photosynthetic and transpiration rate, stomatal conductance (gs), internal Carbon dioxide concentration (Ci), water use efficiency (WUE) of roadside plants on both roads decreased for plants which were growing away from the roadside.A decrease was also estimated in total soluble sugars, total free amino acids and total soluble proteins in all the under study plants on both roads.The Pb2+ conc. was high in smoke samples of bus and coach at Pindi Bhattian Interchange on M-3 and same conc.was noted at Gutwala interchange at N-5.The C. procera accumulated more Pb2+ (0.0024 mg g-1) in their unwashed leaves while 0.00017 mg g-1 was found in washed leaves however low Pb2+ conc.was noticed in P.robelenii at M- 3 while at N-5, N. oleander accumulated more Pb2+ i.e. 0.00186 mg g-1 in their leaves while less accumulation of Pb2+ (0.0012 mg g-1) was noticed in unwashed leaves of P. hysterophorus.The high Cd2+ contents (0.000024 mg g-1) were found in unwashed leaves of C. ciliaris and low conc.(0.000016 mg g-1) was recorded in C. procera at M-3 while high deposition of Cd2+ i.e. 0.00007 mg g-1 was noticed in P.hysterophorus and low Cd2+ traces (0.00002 mg g-1) was measured in unwashed leaves of C.ciliaris at N-5