Sources, Composition, and Mixing State of Submicron Particulates over the Central Indo-Gangetic Plain

Abstract

Submicron particulates, collected between 2015 and 2018 in an urban environment over the central Indo-Gangetic Plain, South Asia, were analyzed. Particulate concentration was typically high during winter (DJF, 115 ± 50 μg m–3) and post-monsoon seasons (ON, 79 ± 52 μg m–3). Submicron particulates constituted a major fraction (69%) of fine particulates (PM2.1) without much seasonal discrepancies. Particulates were metal-enriched (17 ± 6%) with signature of crustal and road dust resuspensions. Metal enrichment was evident specifically for Zn, Co, and Cr. Sulfate was the most robust ion contributing 10% (±4%) of particulate mass followed by nitrate (6 ± 3%) and ammonium (4 ± 2%). Overall, water-soluble ions accounted for one-third of particulate mass mainly comprised secondary ones. The n-alkane homologues (C17–C35) showed prevalence of low-molecular-weight (LMW) alkanes (<C25) with the carbon preference index (CPI) close to one (1.3 ± 0.3) referring predominant contribution of burning of fossil fuels. Similarly, prevalence of LMW fatty acids (≤C20) with a high CPI (9.9) indicates emissions from residential cooking. The presence of dicarboxylic acids and phthalates with a vital signature of anthropogenic emissions was also traced. Strong enrichment of levoglucosan (600 ± 388 ng m–3) was noted especially during peak biomass-burning episodes. Single-particle analysis indicates high abundance of carbonaceous particles (CPs) having both chain-like soot spherules and amorphous tar balls. These CPs were mostly pure, externally mixed against secondary particles for which the mixing state varied among the seasons. Source apportionment by an advanced receptor model indicates secondary aerosols and biomass-burning emissions as the major sources of submicron aerosols (43%), followed by resuspensions of mineral dusts (18%) and emissions from refuse/waste combustion (18%).

Profiling Temporal Pattern of Particulate Matter (PM10) and Meteorological Parameters in Jakarta Province during 2020-2021

“…The higher concentration of monthly PM 10 index in Jakarta Province was recorded around August 2020 and remain relatively high until November 2020 before reached the lowest in December 2020. This finding is in line with the previous study about aerosol air pollution 2012-2016 in SEA region stated that in Maritime countries such as Indonesia reach the peak of PM 10 level around September-October, exacerbated by forest burning (29). Particulate pollution levels and sources were differed in Jakarta between the dry and wet seasons in 2018-2019.…”

“…Particulates pollutant across Indo-Gangetic Plain during the period of 2015-2018 showed the high concentration detected during winter and post monsoon, moreover the consistency of the fine particulates was contributed in majority by submicron particulates (69%), submicron aerosol (43%), mineral dusts (18%), and particles emitted from combusting process (30). In addition, study about aerosol air pollutant in SEA region for ground fine particulate found factors to drive the air quality disruption within the region such as urban-rural gradation, biomass combustion influence on atmospheric condition, seasonal and climate variation (29). While, In Indonesia, fine particulate and coarse particulate concentration in urban area are 1.24 and 2.03 heavier than rural areas respectively (29).…”

“…In addition, study about aerosol air pollutant in SEA region for ground fine particulate found factors to drive the air quality disruption within the region such as urban-rural gradation, biomass combustion influence on atmospheric condition, seasonal and climate variation (29). While, In Indonesia, fine particulate and coarse particulate concentration in urban area are 1.24 and 2.03 heavier than rural areas respectively (29). Similarly, spacetime variation of PM 2.5 was reported within intra-urban and intra-urban areas in the US (31).…”

“…While, study in Petailing Jaya found the characteristics of PM 10 concentration was driven by seasonal dynamics during non-hazy climate (33). Moreover, maritime countries in SEA including Indonesia is considered to have relatively stable temperature, air humidity and rainfall (29). It can be underlined that meteorological in combination with anthropogenic factors drive fine particulate pollution in metropolitan urban areas including Jakarta.…”

“…PM 2.5 concentration at night was considered lower than daytime, due to low temperature retains the plumes at ground surface resulted higher concentration at ground level and bring higher adverse health impacts (32). The other source of particulate pollutants in SEA region is biomass combustion and agriculture activities, moreover satellite MODIS data showed high annual forest fire intensity in Indonesia during dry season (from April to September or October within Java, Bali and North West Nusa) (29). The emission sources of PM 10 have identical activities pattern with other pollutants sources such as SO 2 , CO, and NO 2 , that enables cross selection method in assessing air quality (19), whereas traffic and vehicle emission is frequently indicated as the primary contributor for the PM 10 level in capital city (14).…”