title: Airborne particulate in Varanasi over middle Indo-Gangetic Plain: variation in particulate types and meteorological influences.
abstract: The variation in particulate mass and particulate types (PM2.5and PM10) with respect to local/regional meteorology was analyzed from January to December 2014 (n = 104) for an urban location over the middle Indo-Gangetic Plain (IGP). Both coarser (mean ± SD; PM10161.3 ± 110.4 μg m-3, n = 104) and finer particulates (PM2.581.78 ± 66.4 μg m-3) revealed enormous mass loading with distinct seasonal effects (range: PM1012-535 μg m-3; PM2.58-362 μg m-3). Further, 56% (for PM2.5) to 81% (for PM10) of monitoring events revealed non-attainment national air quality standard especially during winter months. Particulate types (in terms of PM2.5/PM100.49 ± 0.19) also exhibited temporal variations with high PM2.5loading particularly during winter (0.62) compared to summer months (0.38). Local meteorology has clear distinguishing trends in terms of dry summer (March to June), wet winter (December to February), and monsoon (July to September). Among all the meteorological variables (average temperature, rainfall, relative humidity (RH), wind speed (WS)), temperature was found to be inversely related with particulate loading (rPM10-0.79; rPM2.5-0.87) while RH only resulted a significant association with PM2.5during summer (rPM100.07; rPM2.50.55) and with PM10during winter (rPM100.53; rPM2.50.24). Temperature, atmospheric boundary layer (ABL), and RH were cumulatively recognized as the dominant factors regulating particulate concentration as days with high particulate loading (PM2.5>150 μg m-3; PM10>260 μg m-3) appeared to have lower ABL (mean 660 m), minimum temperature (<22.6 °C), and high RH (∼79%). The diurnal variations of particulate ratio were mostly insignificant except minor increases during night having a high wintertime ratio (0.58 ± 0.07) over monsoon (0.34 ± 0.05) and summer (0.30 ± 0.07). Across the region, atmospheric visibility appeared to be inversely associated with particulate (rPM2.5-0.84; rPM10-0.79) for all humid conditions, while at RH ≥80%, RH appeared as the most dominant factor in regulating visibility compared to particulate loading. The Lagrangian particle dispersion model was further used to identify possible regions contributing particulate loading through regional/transboundary movement.
authors.affiliation: Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India.
authors.forename: Vishnu
authors.initials: V
authors.lastname: Murari
authors.affiliation: Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India.
authors.forename: Manish
authors.initials: M
authors.lastname: Kumar
authors.affiliation: Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India.
authors.forename: Alaa
authors.initials: A
authors.lastname: Mhawish
authors.affiliation: Environmental Monitoring Division, CSIR-Indian Institute of Toxicology Research, Lucknow, India.
authors.forename: S C
authors.initials: SC
authors.lastname: Barman
authors.affiliation: Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India. tb.iesd@bhu.ac.in.
authors.forename: Tirthankar
authors.identifier: http://orcid.org/0000-0002-9717-8248
authors.initials: T
authors.lastname: Banerjee
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring; D006813:Humidity; D007194:India; D055904:Meteorology; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D045483:Rivers; D012621:Seasons; D014919:Wind
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter
keywords: Boundary layer; Humidity; Indo-Gangetic Plain; Particulate; Visibility