Chemical Analysis and Source Apportionment of Particulate-Bound Polycyclic Aromatic Hydrocarbons (PAHs) in Northeast India

Particulate-bound Polycyclic Aromatic Hydrocarbons (PAHs) are recognized as critical pollutants due to their significant health impacts on both human and animal life. This study analyzed 16 PAHs identified by the United States Environmental Protection Agency (USEPA) in PM_2.5 samples collected from Jorhat, India, during the winter months (January to March 2020). Alongside examining the temporal variability of these compounds, the research also evaluated the influence of meteorological factors, including temperature, wind speed, relative humidity, and planetary boundary layer (PBL) height, on PAHs concentrations.
The findings revealed that ambient air temperature and PBL height have a more pronounced effect on PAHs concentrations compared to other meteorological parameters during the winter season. The average total PAH concentration during the study period was 157.2 ± 127.7 ng/m³, with a clear dominance of high molecular weight PAHs over low molecular weight ones. Among the 16 PAHs studied, benzo(b,j)fluoranthene was identified as the most abundant compound, contributing 27.26% to the total PAHs concentration, followed by dibenzo(a,h)anthracene at 10.37%.
Source identification was conducted using isomeric PAHs ratio analysis, which highlighted crop residue burning, vehicular emissions, and coal and wood combustion as the primary sources of PAHs emissions in Jorhat. A comparative analysis with other northern Indian cities revealed that vehicular emissions are a common contributor across all locations. However, there are distinct regional variations in source contributions. For instance, in Kolkata, PAHs emissions are significantly influenced by wood and coal combustion, while biomass burning is a notable contributor in Amritsar. In contrast, the primary sources of PM_2.5-bound PAHs in Jorhat are crop residue burning and coal/wood combustion, distinguishing it from the other cities studied.
This research emphasizes the importance of identifying regional emission sources to develop targeted strategies for mitigating PAHs pollution and protecting public health.