Quantification of particle bound metallic load and PAHs in urban environment of Delhi, India: Source and toxicity assessment

The present investigation was carried out to observe the concentration variation of metals/metalloids and Polycyclic Aromatic Hydrocarbons (PAHs) associated with size-segregated particles and its probable emission sources along with the toxicity level in urban environment from the capital of India. Energy Dispersive X-ray Fluorescence (EDXRF) and Gas Chromatography-Mass Spectrometry (GC-MS) techniques were applied for the quantification of metals/metalloids and PAHs in fine (<2.5 μm) and coarse (>2.5 μm) mode particles for the samples collected from four different sensitive sites in Delhi (India) during the year 2012-13. The observed load of metals/metalloids as well as PAHs predominated the fine mode particles, while it was lesser in coarse mode particles regardless the sites. Among metals/metalloids; Si had the highest average percentage contribution (∼14%), and similarly Benzo[a]pyrene had highest average percentage contribution (∼23%) among PAHs. Source apportionment of metals/metalloids and PAHs were carried out by applying the Principal Component Analysis (PCA). Crustal re-suspension, vehicular transportations and industrial activities were found to be the major sources of metals/metalloids; while vehicular emission, burning of biomass and coal were the responsible factors for PAHs. Molecular Diagnostic Ratio (MDR) also showed similar emission sources of PAHs. Excess cancer risk were observed for Ni, As and Pb; where As had the highest inhalation carcinogenic risk.