Janakpuri, India
Janakpuri, India

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Singh K.,National Physical Laboratory India | Tiwari S.,Indian Institute of Tropical Meteorology | Jha A.K.,Central Pollution Control Board | Aggarwal S.G.,National Physical Laboratory India | And 4 more authors.
Natural Hazards | Year: 2013

Size distribution of PM10 mass aerosols and its ionic characteristics were studied for 2 years from January 2006 to December 2007 at central Delhi by employing an 8-stage Andersen Cascade Impactor sampler. The mass of fine (PM2.5) and coarse (PM10-2.5) mode particles were integrated from particle mass determined in different stages. Average concentrations of mass PM10 and PM2.5 were observed to be 306 ± 182 and 136 ± 84 μg m-3, respectively, which are far in excess of annual averages stipulated by the Indian National Ambient Air Quality Standards (PM10: 60 μg m-3 and PM2.5: 40 μg m-3). The highest concentrations of PM10-2.5 (coarse) and PM2.5 (fine) were observed 505 ± 44 and 368 ± 61 μg m-3, respectively, during summer (June 2006) period, whereas the lower concentrations of PM10-2.5 (35 ± 9 μg m-3) and PM2.5 (29 ± 13 μg m-3) were observed during monsoon (September 2007). In summer, because of frequent dust storms, coarse particles are more dominant than fine particles during study period. However, during winter, the PM2.5 contribution became more pronounced as compared to summer probably due to enhanced emissions from anthropogenic activities, burning of biofuels/biomass and other human activities. A high ratio (0.58) of PM2.5/PM10 was observed during winter and low (0.24) during monsoon. A strong correlation between PM10 and PM2.5 (r 2 = 0.93) was observed, indicating that variation in PM10 mass is governed by the variation in PM2.5. Major cations (NH4 +, Na+, K+, Ca2+ and Mg2+) and anions (F-, Cl-, SO4 2- and NO3 -) were analyzed along with pH. Average concentrations of SO4 2- and NO3 - were observed to be 12.93 ± 0.98 and 10.33 ± 1.10 μg m-3, respectively. Significant correlation between SO4 2- and NO3 - in PM1.0 was observed indicating the major sources of secondary aerosol which may be from thermal power plants located in the southeast and incomplete combustion by vehicular exhaust. A good correlation among secondary species (NH+, NO3 - and SO4 2-) suggests that most of NH4 + is in the form of ammonium sulfate and ammonium nitrate in the atmosphere. During winter, the concentration of Ca2+ was also higher; it may be due to entrainment of roadside dust particles, traffic activities and low temperature. The molar ratio (1.39) between Cl- and Na+ was observed to be close to that of seawater (1.16). The presence of higher Cl- during winter is due to western disturbances and probably local emission of Cl- due to fabric bleaching activity in a number of export garment factories in the proximity of the sampling site. © 2013 Springer Science+Business Media Dordrecht.

Tiwari S.,Indian Institute of Tropical Meteorology | Chate D.M.,Indian Institute of Tropical Meteorology | Srivastaua A.K.,Indian Institute of Tropical Meteorology | Bisht D.S.,Indian Institute of Tropical Meteorology | Padmanabhamurty B.,B 3B 8C
Geofizika | Year: 2012

Daily, monthly, seasonal and annual moving means of PM1, PM 2.5 and PM10 concentrations from August, 2007 to October, 2008 at Delhi (28° 35′ N; 77° 12′ E), the seventh populous megacity in the world are presented. PM1, PM2.5 and PM10 concentrations varied seasonally with atmospheric processes and the anthropogenic activities. PM10 decreases during monsoon by ∼25-80 μg m-3 and PM1 and PM2.5 by ∼10-15 μg m-3 from their pre-monsoon levels. Emissions from fireworks during Deepawali in the post-monsoon season increases PM1, PM2.5 and PM10 levels by 300, 350 and 400 μg m -3, respectively over their monsoon levels. Seasonal variation of mixing heights, temperatures, winds and rainfall, accounts for the inter-annual variability of PM1, PM2.5, and PM10. Accordingly, wintertime PM1, PM2.5 and PM10 components contribute by ∼30-33% to annual levels. PM10 in summer is higher by 8% to that of PM2.5 and by 9% to that of PM1 PM10 components in post-monsoon are lower by 5% to that of PM 2.5 and by 7% to that of PM1. Also, PM1, PM2.5 and PM10 levels were higher during October, 2008 than those in 2007, but their levels were almost remain the same in August and September of 2007 and 2008. Moving means of PM1, PM2.5 and PM10 and their concentrations in different seasons are useful in policy making decisions thereupon aiming to improve the air quality in Delhi.

Tiwari S.,Indian Institute of Tropical Meteorology | Chate D.M.,Indian Institute of Tropical Meteorology | Bisht D.S.,Indian Institute of Tropical Meteorology | Srivastava M.K.,Banaras Hindu University | Padmanabhamurty B.,B 3B 8C
Atmospheric Research | Year: 2012

Precipitation chemistry studies were conducted at Kothi (32.31°N, 77.20°E), a rural Indian location, in the North Western Himalayas during June to October of 2006 and 2007. The volume weighted mean pH values ranged from 5.16 to 6.36 with a mean of 5.68±0.26 indicating mostly alkaline precipitation events. However, 18% samples were found acidic due to dominance of acidic components. The alkaline to acidic ions ratio (1.05) confirms that acidic components are neutralized by alkali radicals in rainwater. Of the total ionic composition 159μeq/l, in rainwater samples, dominant were Ca 2+ (19%) followed by Na + (14%). Among the anions, Cl - (17%) was slightly higher than SO 4 2- (16%) and NO 3 - (11%). The ratio (NO 3 -+Cl -)/SO 4 2-) 1.05 indicates acidity in rainwater by the cumulative effects of HNO 3, H 2SO 4 and HCl. The ratios NH 4 +/NO 3 - as 0.76 and NH 4 +/SO 4 2- as 0.50 show the pre-dominance of atmospheric NH 4NO 3 and (NH 4) 2SO 4. Significant correlation between Na + and Cl - (r=0.97; p<0.0001) and between SO 4 2- and NO 3 - (r=0.60; p<0.0001) indicates their origin from similar sources. Neutralization factor calculations show that Ca 2+ plays a major role in the neutralizing processes. Enrichment factors indicate that Ca 2+, SO 4 2- K + and Mg 2+ were originated from non-marine sources. The principle component analysis indicates the influence of transportation of air-born primary and secondary particles on the chemical composition of rainwater. © 2011 Elsevier B.V.

Tiwari S.,Indian Institute of Tropical Meteorology | Chate D.M.,Indian Institute of Tropical Meteorology | Srivastava M.K.,Banaras Hindu University | Safai P.D.,Indian Institute of Tropical Meteorology | And 3 more authors.
Natural Hazards | Year: 2012

Temporal variation of PM 10 using 2-year data (January, 2007-December, 2008) of Delhi is presented. PM 10 varied from 42 to 200 μg m -3 over January to December, with an average 114. 1 ± 81. 1 μg m -3. They are comparable with the data collected by Central Pollution Control Board (National Agency which monitors data over the entire country in India) and are lower than National Ambient Air Quality (NAAQ) standard during monsoon, close to NAAQ during summer but higher in winter. Among CO, NO 2, SO 2, rainfall, temperature, and wind speed, PM 10 shows good correlation with CO. Also, PM 10, PM 2. 5, and PM 1 levels on Deepawali days when fireworks were displayed are presented. In these festive days, PM 10, PM 2. 5, and PM 1 levels were 723, 588, and 536 μg m -3 in 2007 and 501, 389, and 346 μg m -3 in 2008. PM 10, PM 2. 5, and PM 1 levels in 2008 were 1. 5 times lower than those in 2007 probably due to higher mixing height (446 m), temperature (23. 8°C), and winds (0. 36 ms -1). © 2011 Springer Science+Business Media B.V.

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