Spatio-temporal variation in cadmium released by automobiles along two roads in Pakistan.
Cadmium (Cd) is a highly toxic metal in the environment. Automobiles release a considerable amount of Cd along roads. In this study, we assessed the level of Cd in five herbaceous plant species (Calotropis procera, Datura alba, Ricinus communis, Parthenium hysterophorus and Cenchrus ciliaris) commonly growing along two roads i.e. Motorway (M-2) and Faisalabad-Sargodha road (FSR) in the Punjab, Pakistan. Plant and soil samples were collected in all the four seasons from roadsides. Samples taken 100 m away from roads were designated as control. Cd was analyzed in all the plants and soil samples by Inductively Coupled Plasma Atomic Emission Spectrophotometer (ICP-AES). Spatial and temporal variation of Cd concentrations both in plants and soils was clearly seen in results. With compared to control ones, plants and soils showed higher concentration of Cd along roads. The highest contamination of Cd was recorded during summer, whilst, the least was noticed during winter. Among plants, Calotropis procera leaves accumulated the highest level of Cd which proved as bioindicator of Cd. The Cd concentrations in plants along roadsides positively correlated with traffic density. So, control measures are required to overcome transport sector related pollution which may become severe in forthcoming days.