Atmospheric Concentrations of Polycyclic Aromatic Hydrocarbons and Nitro PAHs

Abstract

newline Polycyclic Aromatic Hydrocarbons (PAHs) and Nitro-PAHs are ubiquitous organic pollutants. Their elevated concentration in the ambient air is a serious matter of concern as these carcinogenic, mutagenic and teratogenic for humans. Despite their environmental importance, very fewer studies have been conducted on PAHs over Indian cities, and this is the first study on the gas-particle partition of PAHs and Nitro-PAHs over the Indo-Gangetic Plain. Aerosol sample in the dual-phase (gas and particle) are collected simultaneously for the first time in Agra at a rural and traffic dominated site from October-2015 to November-2017. High Volume Sampler was used to collect gas and particulate phase samples on quartz microfiber filter papers (QFFs) and Poly Urethane Foam (PUF) plugs, respectively. Samples were extracted in a mixture of DCM and n-hexane. 16 priority PAHs and 2 Nitro-PAHs were analyzed using Gas Chromatograph-Mass Spectrometry (GC-MS). The total concentration of PAHs (gas + particulate) was 2481 and 1011 ng m-3 at traffic and rural site, respectively whereas total concertation of Nitro-PAHs was 90 and 28 ng m-3 at traffic and rural site, respectively. A higher concentration of PAHs and Nitro-PAHs was observed during winter at both the traffic and rural sites. Gas-particle partitioning of PAHs in the ambient air of Agra is governed by the dual model and shows that the PAHs concentration is influenced by the OC and EC concentration in the atmosphere. Pankow model shows that PAHs are emitted from the samples close to the sampling location and do not get enough time to get partition in between both the phases. A statistically significant correlation (plt0.0001) for Clausius Clapeyron plots was obtained which indicates the temperature dependency of gas-phase PAHs at both sites. Source analysis of PAHs and Nitro-PAHs shows that the PAHs concentration at traffic site is mainly due to traffic and combustions source whereas at rural site PAHs concentration is mainly due to biomass combustion and pyrogenic sources. ILCR values of PAHs and Nitro-PAHs shows that humans are prone to cancer risk from dermal exposure pathway, followed by ingestion and inhalation. Adults are more prone to cancer risk followed by children and infants. newlineKeywords: Polycyclic Aromatic Hydrocarbons (PAHs), Nitro-PAHs, Gas-particle partitioning, newlineSource apportionment, ILCR. newline