Aerosol and rain water study during Indian summer monsoon

Journal of atmospheric …, 2010

Size-segregated aerosol samples were collected continuously from July 2009 to June 2010 at urban area of Raipur, the eastern central India. The collected samples were analyzed for PM 10 mass and its water-soluble dicarboxylate species and major inorganic ions. Results showed that the annual mean PM 10 concentration was 270.5 µg/m 3 , which varied from 109.8 to 455.6 µg/m 3 . The higher concentration of PM 10 mass was found during winter season followed by spring and summer, and lower during monsoon season. High PM 10 mass concentration in Raipur could be attributed to the anthropogenic activities which may include high rate of construction activities, biomass combustion and mechanical erosion from road dusts. The concentrations of total dicarboxylates (TDCs) ranged from 325.3 to 1537.7 ng/m 3 with an average of 904.0 ng/m 3 constituting only 0.3% of PM 10 mass. The oxalate (C 2 ) and malonate (C 3 ) were the dominant DCs followed by succinate (C 4 ) and phthalate (Ph). The water-soluble major inorganic ions constituted 10.0% of PM 10 mass with SO 4 2and NO 3 being the dominant species followed by Cland Ca 2+ . The concentrations of dicarboxylates and major inorganic ions also showed maxima in winter and spring than summer and monsoon seasons. The ratio of malonate to succinate was used to distinguish primary sources from secondary sources of these dicarboxylates. The average C 3 /C 4 ratio in spring and summer was 1.6 and 2.1, respectively, which suggested a large contribution of secondary sources to particulate dicarboxylates formation. Correlation analysis of DCs with SO 4 2and K + was investigated to interpret their possible secondary formation pathways. Source identification study by principal component analysis (PCA) revealed that photochemical, secondary sources and vehicular emissions were the main sources contributing to overall PM 10 mass with minor contribution from paved road dust and explained almost 95.5% variance of total aerosol data set.

The total suspended particulate (TSP) samples were collected from April 2013 to April 2014 at the urban location of Pokhara valley in western Nepal. The major aims were to study, quantify, and understand the concentrations and variations of TSP and major water-soluble inorganic ions (WSIIs) in the valley with limited data. The annual average TSP mass concentration was 135.50 ˘ 62.91 µg/m 3. The average analyzed total WSIIs accounted for 14.4% of total TSP mass. Major anions and cations in TSP samples were SO 4 2ánd Ca 2+ , respectively. Seasonal differences in atmospheric conditions explain the clear seasonal variations of ions, with higher concentrations during pre-monsoon and winter and lower concentrations during the monsoon period. Neutralization factor calculations suggested that Ca 2+ in the Pokhara valley mostly neutralizes the acidity in the atmosphere. Principle component analysis, NO 3 ´ /SO 4 2´ratio, and non-sea salt fraction calculations suggested that the WSIIs in the valley were mostly derived from anthropogenic activities and crustal mineral dust, which was also supported by the results from precipitation chemistry over the central Himalayas, Nepal. In addition, back trajectories analysis has suggested that the air pollution transported from and through Indo-Gangetic Plains (IGP) during the dry periods, which has resulted in high ionic loadings during this period. Average NO 3 ´ /SO 4 2´ratio was found to be 0.69, indicating the dominance of stationary sources of TSP in Pokhara valley. Secondary inorganic aerosols can have an adverse health impact on the human population in the valley. The data set from this one-year study provides new insights into the composition of WSIIs in the foothills of the Himalayas, which can be of great importance for understanding the atmospheric environment in the region.

Aerosol Air Qual …, 2011

This paper reports the atmospheric concentrations of PM 2.5 and PM 1 mass, water soluble inorganic components and their seasonal variations measured between the period of July 2009 and June 2010 in Durg city (20°23' to 22°02'N and 80°46' to 81°58'E), India. A cascade impactor sampler with Whatman 41 glass filters was used to collect aerosol samples in PM 2.5 and PM 1 size fractions. The results showed that the annual mean concentration of PM 2.5 and PM 1 were 135.0 µg/m 3 and 64.7 µg/m 3 , respectively. Annual cycle shows highest concentration of PM 2.5 and PM 1 mass and water soluble ions in winter season and the lowest during rainy season. This is attributed to the enhanced production of aerosols and prevailing meteorological conditions. The higher PM 1 /PM 2.5 ratio (0.48) during the whole campaign clearly indicates larger PM 1 particle fractions were in PM 2.5 at this location. Out of the total aerosol mass, water soluble constituents contributed an average of 11.57% (7.48% anions, 4.09% cations) in PM 2.5 and 16.98% (11.14% anions, 5.85% cations) in PM 1 . The concentrations of SO 4 2and NO 3 were highest in all size fractions and accounted for 32.76% and 13.38% of the total mass of the water soluble ions in PM 2.5 and 32.78% and 12.21% in PM 1 size fractions. Na + , Mg 2+ and Ca 2+ , derived from the soil dust particles, were higher in spring and summer, as the dry weather in this season was favorable for the resuspension of soil particles. The seasonal variation of Cl -, K + and secondary components (NH 4 + , NO 3 and SO 4 2-) were similar with high concentrations in winter and low concentrations in fall. Two principal components explaining 76.6% and 65.9% of the variance for PM 2.5 and PM 1 data set respectively were identified. Factor 1 has significant loading of species of anthropogenic origins and factor 2 showed partial associations with species of natural origins.

Aerosol and Air Quality Research, 2014

Water-soluble ionic constituents (Cl-, NO 3-, SO 4 2-, Na + , NH 4 + , K + , Mg 2+ and Ca 2+) of PM 2.5 were measured using Ambient Ion Monitor coupled-to Ion Chromatograph (AIM-IC) with a time resolution of one hour at Ahmedabad (an urban location in semi-arid region of western India) during summer and winter to study the diurnal and seasonal variations. Maximum abundances of most of the species were observed during afternoon hours in summer, whereas minimum concentrations were found during winter at the same local time. During summer, the concentration levels of most of the constituents in a diurnal cycle are largely influenced by ambient relative humidity variation. During winter, the emission strength and boundary layer dynamics impact the diurnal cycle. Secondary inorganic species like NH 4 + , NO 3 and SO 4 2exhibit significant differences in their relative abundances during winter and summer. Four factors have been derived by Positive Matrix Factorization (PMF) analysis on water-soluble ionic constituents. These are secondary, sea-salt, mineral dust sources and the fourth factor is associated with K + , which is likely to be biomass burning emission.

Open Journal of Air Pollution, 2015

Atmospheric fine particulate matters (PM2.5) were collected with an Envirotech Instrument (Model APM 550) at the roof of Khundkur Mukarram Hussain Science Building, University of Dhaka, Bangladesh between January and February, 2013. PM2.5 samples were collected on Quartz fiber filters during day and night time. Water soluble ions (sulfate, nitrate, phosphate, chloride, bromide, sodium, potassium and calcium) were analyzed with Ion Chromatography (Model 881, Metrohm Ltd., Switzerland) and Flame photometer (Model PFP7, Jenway, UK). Average PM2.5 mass was 136.1 µg•m −3 during day time and 246.8 µg•m −3 during night time with a total average of 191.4 µg•m −3. Nighttime PM2.5 concentration was about double compared than that of daytime presumable due to the low ambient temperatures with high emissions from heavy duty vehicles. The 24-hour average PM2.5 mass (average of day and night) was about eight times higher than WHO (25.0 µg•m −3) and about three times higher than DoE, Bangladesh (65.0 µg•m −3) limit values. The total average concentrations of sulfate, nitrate, phosphate, bromide, chloride, sodium, potassium and calcium were 5.30, 7.75, 0.62, 0.16, 1.19, 1.30, 8.11, and 3.09 µg•m −3 , respectively. The concentrations of the water soluble ions were much higher during nighttime than daytime except nitrate, bromide and potassium. Excellent correlations were observed between sulfate and nitrate, sodium and chloride, bromide and phosphate indicating joint sources of origin. Potassium, sulfate, nitrate and calcium are the most dominant species in PM2.5. Water soluble ionic components in Dhaka contributed about 15% mass of the PM2.5. Ratio analysis showed that sodium and chloride were from mainly sea salt. Potassium has varieties of sources other than biomass burning. Sulfate and nitrate are mainly from fossil fuel origin. This is the first study of the day and night variation of the water soluble ionic species at the fine particulate matters (PM2.5) in Bangladesh.

Rainwater samples collected at Sinhagad on 65 rain occasions during monsoon season (June – September 2005) and on 23 rain occasions during post-monsoon season (October-November 2005) with standard rain collection instruments, i.e. wet-only (WO) and bulk collectors (BC), were considered for the present study. Sinhagad is a hill station on a mountaintop in the Western Ghats, located about 40 km southwest of Pune. The following ionic components were determined: H + , NH 4 + , Ca 2+ , Mg 2+ , K + , Na + , SO 4 2-, NO 3 2-, Cl -and F -. The pH analyses showed that rainwater in both the seasons were alkaline. The major neutralizing component was associated with Ca 2+ . In monsoon rains, the major anion was Cl -and the major cation was Na + ; whereas in post-monsoon the major anion was SO 4 2-and the major cation was Ca 2+ . The concentrations of nss SO 4 2-, NO 3 2-and NH 4 + were found to be higher during post-monsoon than monsoon. Surprisingly high concentrations of Ca 2+ and SO 4 2-wer...

Atmospheric Environment, 2016

h i g h l i g h t s 76% higher loading of chemical constituents over Delhi than Pune. Higher secondary aerosols in RW over Delhi from NW direction. ~4 and 26% acidic samples were observed in Pune and Delhi. Lower concentrations of ions from the Arabian Sea.

Journal of Arid Environments, 2019

This paper presents the seasonal features of major carbonaceous components in aerosols, their source characteristics and the role of meteorology in influencing the chemical characteristics of aerosols at a semi-arid location Udaipur (24.5°N; 73.6°E), India, based on the analysis of PM 10 samples (N = 128) collected during 2010-14. The samples were analysed for OC (organic carbon), EC (elemental carbon), CC (carbonate carbon), WSOC (water-soluble OC), WSTN (water-soluble total nitrogen) and water-soluble inorganic ions. Primary and secondary OC (POC and SOC), water-insoluble OC (WIOC) and water-soluble organic nitrogen (WSON) were also estimated. The carbonaceous aerosols (TC) contributed to~23% of PM 10 loading. Both EC and OC mass loading showed high values during dry period (October to May) (OC = 26 ± 14 μg m −3 , EC = 3.2 ± 2.2 μg m −3 with the PM 10 mass loading of 140 ± 52 μg m −3) compared to wet period (June to September) (OC = 16 ± 10 μg m −3 , EC = 1.4 ± 0.8 μg m −3 with the PM 10 mass loading of 84 ± 43 μg m −3). While the crustal species, biomass tracers and anthropogenic species dominated during dry period, the sea salt species (Na + , Cl − , ss-SO 4 , ss-Mg, ss-Ca, ss-K) were comparatively higher in wet period. OC was found to be predominantly water-insoluble and secondary in nature. Local anthropogenic/natural emissions and marine transported aerosols (by south-westerlies) contributed during wet period, while dry period is influenced by transported anthropogenic aerosols from IGP and northern India (by north/north-easterlies) along with mineral aerosols from desert regions (by westerlies). Monthly average contribution of total carbonaceous aerosols (TCA = OM (organic matter) +EC + CC) varied from 20 to 42%, over a year while the water-soluble ionic fraction varied from 16 to 36% of the PM 10 mass. The un-analysed part which is mostly mineral dust contributed 39-55%.

Frontiers in Sustainable Cities, 2021

In this study, we have coupled measurements, modeling, and remote sensing techniques to better delineate the source characteristics and variability of air pollutants in Delhi primarily during the post-monsoon season in 2019. We show a comparison of ambient PM2.5 (particulate matter having aerodynamic diameter ≤2.5 μm) levels and associated elements during the post-monsoon with those during a relatively clean season of monsoon (experiencing frequent wet precipitation). Air-mass back trajectories from Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model have been used to infer the possible source pathways of PM2.5 impacting at the receptor site in Delhi. The average concentrations of PM2.5 during monsoon (June–July) and post-monsoon (October–November) were 42.2 ± 15.5 μg m−3 (range: 22–73 μg m−3) and 121.4 ± 53.6 μg m−3 (range: 46–298 μg m−3), respectively. The PM2.5 samples were analyzed for heavy and trace elements (Si, S, Na, Mg, Al, Cl, Ca, K, Ti, V, Cr, Mn, Fe,...

Bulletin of Environmental Contamination and Toxicology, 2012

To track the particulate pollution in Sichuan Basin, sample filters were collected in three urban sites. Characteristics of water-soluble inorganic ions (WSIIs) were explored and their sources were analyzed by principal component analysis (PCA). During 2012-2013, the PM 2.5 concentrations were 86.7 ± 49.7 µg m -3 in Chengdu (CD), 78.6 ± 36.8 µg m -3 in Neijiang (NJ), and 71.7 ± 36.9 µg m -3 in Chongqing (CQ), respectively. WSIIs contributed about 50% to PM 2.5 , and 90% of them were secondary inorganic ions. NH 4 + and NO 3 -roughly followed the seasonal pattern of PM 2.5 variations, whereas the highest levels of SO 4 2-appeared in summer and autumn. PM 2.5 samples were most acidic in autumn and winter, but were alkaline in spring. The aerosol acidity increased with the increasing level of anion equivalents. SO 4 2-primarily existed in the form of (NH 4 ) 2 SO 4 . Full neutralization of NH 4 + to NO 3 -was only observed in low levels of SO 4 2-+ NO 3 -, and NO 3 -existed in various forms. SO 4 2-and NO 3 -were formed mainly through homogeneous reactions, and there was the existence of heterogeneous reactions under high relative humidity. The main identified sources of WSIIs included coal combustion, biomass burning, and construction dust.