Atmospheric Bulk Deposition of PAHs over Brahmaputra Valley: Characteristics and Influence of Meteorology

Abstract

Bulk atmospheric deposition of Polycyclic Aromatic Hydrocarbons (PAHs) in Guwahati city of the Brahmaputra Valley have been characterised for a period of one year. The ∑PAHs (USEPA's priority 16) and benzo(s)pyrene (BaP) concentrations in the collected bulk deposit ranged between 2.2 and 1035 ng mL -1 , and BDL and 5.6 ng mL -1 respectively. Greater deposition of PAHs was observed during the dry season and the deposition of low molecular weight PAHs (LMWPAHs) were particularly high. The study revealed explicit effect of the prevailing meteorology on the bulk atmospheric deposition characteristics of PAHs. Greater number of inversion days and lowering of inversion height during the dry season were found to enhance deposition of PAHs. Diagnostic ratios indicated pyrogenic origin of the PAHs derived from combustion of diesel, coal and wood combustion. The deposition of LMWPAHs was greatly influenced by temperature. The diurnal variation of relative humidity, and wind pattern were found to affect deposition of PAHs.

Concentration, source identification, and exposure risk assessment of PM2.5-bound parent PAHs and nitro-PAHs in atmosphere from typical Chinese cities

“…Additionally, calm winds, a vertical temperature inversion, low temperature, low atmospheric mixing height, and low levels of precipitation are common in winter under stagnant conditions, and are not conducive to the diffusion and dilution of airborne PAHs in the larger cities. Under these atmospheric conditions, pollutant dispersion is low, leading to a shift from the gaseous to particulate phase, which can accumulate and create higher concentrations of PAHs in PM2.5 47 . Conversely, during summertime, high precipitation, wind speed, and temperature, along with enhanced photodecomposition of PAHs, result in increased dispersion and thus a decrease in the concentration of PAHs 48 .…”

Land–Ocean Exchange Mechanism of Chlorinated Paraffins and Polycyclic Aromatic Hydrocarbons with Diverse Sources in a Coastal Zone Boundary Area, North China: The Role of Regional Atmospheric Transmission

“…This may be because of the heating that occurs in urban residential areas, which became a local point source closer to the coast site during winter. It may also be because of the lower humidity in the atmosphere (the mean value is 33%), which could further enhance the sedimentation of particulate matter 43 during land−ocean migration.…”

Polycyclic Aromatic Hydrocarbons (PAHs) at High Mountain Site in North China: Concentration, Source and Health Risk Assessment

“…(Kamal et al, 2016). PAHs are widely distributed in atmosphere , and they can pose adverse health effects to human beings because of their well-known carcinogenic, mutagenic and teratogenic properties (Bhargava et al, 2004;Hussain et al, 2016). For example, exposure to PAHs and their secondary metabolites may changes in the original sequence of the DNA, which cause DNA mutation, and lead to increased human health risks (Kelly et al, 2007;Wilcke, 2007;Li et al, 2016c).…”