Browsing by Author "A.S. Pipal"

Now showing 1 - 4 of 4

Aerosol characteristics at a rural station in southern peninsular India during CAIPEEX-IGOC: physical and chemical properties
(Springer Verlag, 2015) D.S. Bisht; A.K. Srivastava; A.S. Pipal; M.K. Srivastava; A.K. Pandey; S. Tiwari; G. Pandithurai
To understand the boundary layer characteristics and pathways of aerosol–cloud interaction, an Integrated Ground Observational Campaign, concurrent with Cloud Aerosol Interaction and Precipitation Enhancement Experiment, was conducted by the Indian Institute of Tropical Meteorology, Pune, under Ministry of Earth Sciences at Mahabubnagar (a rural environment, which is ~100 km away from an urban city Hyderabad in Andhra Pradesh), during the period of July–November 2011. Collected samples of PM2.5 and PM10 were analyzed for water-soluble ionic species along with organic carbon (OC) and elemental carbon (EC). During study period, the average mass concentrations of PM2.5 and PM10 were about 50(±10) and 69(±14) μg m−3, respectively, which are significantly higher than the prescribed Indian National Ambient Air Quality Standards values. The chemical species such as sum of anions and cations from measured chemical constituents were contributed to be 31.27 and 38.49 % in PM2.5 and 6.35 and 5.65 % to the PM10, whereas carbonaceous species contributed ~17.3 and 20.47 % for OC and ~3.0 and 3.10 % for EC, respectively. The average ratio of PM2.5/PM10 during study period was ~0.73(±0.2), indicating that the dominance of fine size particles. Carbonaceous analysis results showed that the average concentration of OC was 14 and 8.7 μg m−3, while EC was 2.1 and 1.5 μg m−3 for PM10 and PM2.5, respectively. The ratios between OC and EC were estimated, which were 6.6 and 5.7 for PM10 and PM2.5, suggesting the presence of secondary organic aerosol. Total carbonaceous aerosol accounts 23 % of PM10 in which the contribution of OC is 20 % and EC is 3 %, while 20 % of PM2.5 mass in which the contribution of OC is 17 % and EC is 3 %. Out of the total aerosols mass, water-soluble constituents contributed an average of 45 % in PM10 and 38 % in PM2.5 including about 39 % anions and 6 % cations in PM10, while 31 % anions and 7 % cations in PM2.5 aerosol mass collectively at study site. © 2014, Springer-Verlag Berlin Heidelberg.
Sources and characteristics of carbonaceous aerosols at Agra "World heritage site" and Delhi "capital city of India"
(Springer Verlag, 2014) A.S. Pipal; S. Tiwari; P.G. Satsangi; Ajay Taneja; D.S. Bisht; A.K. Srivastava; M.K. Srivastava
Agra, one of the oldest cities "World Heritage site", and Delhi, the capital city of India are both located in the border of Indo-Gangetic Plains (IGP) and heavily loaded with atmospheric aerosols due to tourist place, anthropogenic activities, and its topography, respectively. Therefore, there is need for monitoring of atmospheric aerosols to perceive the scenario and effects of particles over northern part of India. The present study was carried out at Agra (AGR) as well as Delhi (DEL) during winter period from November 2011 to February 2012 of fine particulate (PM2.5: d < 2.5 μm) as well as associated carbonaceous aerosols. PM2.5 was collected at both places using medium volume air sampler (offline measurement) and analyzed for organic carbon (OC) and elemental carbon (EC). Also, simultaneously, black carbon (BC) was measured (online) at DEL. The average mass concentration of PM2.5 was 165.42 ± 119.46 μg m-3 at AGR while at DEL it was 211.67 ± 41.94 μg m-3 which is ~27 % higher at DEL than AGR whereas the BC mass concentration was 10.60 μg m-3. The PM2.5 was substantially higher than the annual standard stipulated by central pollution control board and United States Environmental Protection Agency standards. The average concentrations of OC and EC were 69.96 ± 34.42 and 9.53 ± 7.27 μm m-3, respectively. Total carbon (TC) was 79.01 ± 38.98 μg m-3 at AGR, while it was 50.11 ± 11.93 (OC), 10.67 ± 3.56 μg m-3 (EC), and 60.78 ± 14.56 μg m-3 (TC) at DEL. The OC/EC ratio was 13.75 at (AGR) and 5.45 at (DEL). The higher OC/EC ratio at Agra indicates that the formation of secondary organic aerosol which emitted from variable primary sources. Significant correlation between PM2.5 and its carbonaceous species were observed indicating similarity in sources at both sites. The average concentrations of secondary organic carbon (SOC) and primary organic carbon (POC) at AGR were 48.16 and 26.52 μg m-3 while at DEL it was 38.78 and 27.55 μg m-3, respectively. In the case of POC, similar concentrations were observed at both places but in the case of SOC higher over AGR by 24 in comparison to DEL, it is due to the high concentration of OC over AGR. Secondary organic aerosol (SOA) was 42 % higher at AGR than DEL which confirms the formation of secondary aerosol at AGR due to rural environment with higher concentrations of coarse mode particles. The SOA contribution in PM2.5 was also estimated and was ~32 and 12 % at AGR and DEL respectively. Being high loading of fine particles along with carbonaceous aerosol, it is suggested to take necessary and immediate action in mitigation of the emission of carbonaceous aerosol in the northern part of India. © 2014 Springer-Verlag Berlin Heidelberg.
Study of the carbonaceous aerosol and morphological analysis of fine particles along with their mixing state in Delhi, India: A case study
(Springer Verlag, 2015) S. Tiwari; A.S. Pipal; Philip K. Hopke; D.S. Bisht; A.K. Srivastava; Shani Tiwari; P.N. Saxena; A.H. Khan; S. Pervez
Because of high emissions of anthropogenic as well as natural particles over the Indo-Gangetic Plains (IGP), it is important to study the characteristics of fine (PM2.5) and inhalable particles (PM10), including their morphology, physical and chemical characteristics, etc., in Delhi during winter 2013. The mean mass concentrations of fine (PM2.5) and inhalable (PM10) (continuous) was 117.6±79.1 and 191.0± 127.6 μg m−3, respectively, whereas the coarse mode (PM10–2.5) particle PM mass was 73.38±28.5 μg m−3. During the same period, offline gravimetric monitoring of PM2.5 was conducted for morphological analysis, and its concentration was ~37% higher compared to the continuous measurement. Carbonaceous PM such as organic carbon (OC) and elemental carbon (EC) were analyzed on the collected filters, and their mean concentration was respectively 33.8 and 4.0 μg m−3 during the daytime, while at night it was 41.2 and 10.1 μg m−3, respectively. The average OC/EC ratio was 8.97 and 3.96 during the day and night, respectively, indicating the formation of secondary organic aerosols during daytime. Effective carbon ratio was studied to see the effect of aerosols on climate, and its mean value was 0.52 and 1.79 during night and day, indicating the dominance of absorbing and scattering types of aerosols respectively into the atmosphere over the study region. Elemental analysis of individual particles indicates that Si is the most abundant element (~37–90%), followed by O (oxide) and Al. Circularity and aspect ratio was studied, which indicates that particles are not perfectly spherical and not elongated in any direction. Trajectory analysis indicated that in the months of February and March, air masses appear to be transported from the Middle Eastern part along with neighboring countries and over Thar Desert region, while in January it was from the northeast direction which resulted in high concentrations of fine particles. © Springer-Verlag Berlin Heidelberg 2015.
Variability in atmospheric particulates and meteorological effects on their mass concentrations over Delhi, India
(Elsevier BV, 2014) S. Tiwari; D.S. Bisht; A.K. Srivastava; A.S. Pipal; A. Taneja; M.K. Srivastava; S.D. Attri
Simultaneous and continuous measurements of PM2.5 and PM10 along with other co-existent pollutants viz., black carbon (BC), CO, NO and NOx were carried out over Delhi with high resolution (5min) datasets from 1st Sept. 2010 to 23rd Aug. 2012. Arithmetic mean mass concentrations of PM2.5 and PM10 were about 130±103 and 222±142μgm-3 respectively during the entire measurement period, which are considerably higher than the annual averages of PM2.5 and PM10, stipulated by the National and International standards. It was noticed that the fine mode particles (PM2.5) were higher than the coarse mode particles (PM10-2.5) during post-monsoon (~89%), winter (~69%) and monsoon (~64%) periods; however, PM10-2.5 was higher (~22%) than PM2.5 during summer. Arithmetic mean mass concentrations of BC, CO, NO and NOx were about 7±5μgm-3, 2±1ppm, 17±17ppb and 30±24ppb, respectively. In the present study, highest fraction of BC (~6%) in PM2.5 mass was in winter, whereas the lowest fraction (~4%) was in summer. Relationships among PMs (particulate matters) and other pollutants indicated that the fine mode particles are highly correlated with BC (0.74) and CO (0.51). The effects of meteorological parameters on aerosols have been studied and a significant negative relationship (-0.45) between mixing height (MH) and PM2.5 has been noticed. Higher correlation was during winter (-0.55), however lower was in summer (-0.16). Relation between visibility (VIS) and PM2.5 was higher during post-monsoon (-0.85) and winter (-0.78) when the visibility was around 2km; however, it was relatively less correlated when VIS was greater than 2km during summer and monsoon. Relationship between PM2.5 and relative humidity (RH) showed a significant negative correlation (-0.56) for the entire study period. A positive correlation (0.32) was observed during the winter period with fine mode particles whereas negative correlation was seen with coarse mode particles during monsoon (-0.70) and summer (-0.51). © 2014.