Dr. Trailokya Saud | National Physical Laboratory (original) (raw)

Papers by Dr. Trailokya Saud

ScienceDirect, 2020

The National Aerosol Facility (NAF) has been built at IIT Kanpur, India for studying the aerosol ... more The National Aerosol Facility (NAF) has been built at IIT Kanpur, India for studying the aerosol behavior under simulated severe nuclear reactor accident conditions. Plasma torch aerosol generator (PTAG) has been employed in this facility for generating metal oxide particles with desirable properties. Plasma synthesis closely simulates the particle generation characteristics from degraded core during a postulated severe nuclear reactor accident. This study presents the effect of controlling parameters namely electrical power, carrier gas flow rate and powder feed rate of PTAG on the mass characteristics of synthesized metal oxide particles. The structural and morphological information of the synthesized particles has also been obtained via analysis performed using X-ray diffraction (XRD) method and Transmission electron microscopy (TEM). A set of optimized parameters has been finalized based on the outcome of this study. The study aims to standardize the generator system in order to perform future NAF experiments.

Atmospheric Research, 2020

This paper discusses the size resolved cloud condensation nuclei (CCN) properties of two cesium b... more This paper discusses the size resolved cloud condensation nuclei (CCN) properties of two cesium bound compounds viz. CsI and CsOH. These properties are important in context of risk analysis and management of probable environmental releases during postulated nuclear reactor accident conditions. If released as fission product aerosols, these particles have potential to act as CCN, when exposed to humid environment. On activation , their evolution-deposition dynamics and consequently fate is expected to be affected in closed and/or open atmosphere. Size resolved CCN efficiency spectra (20-300 nm) are obtained for 0.2-1% supersaturation (SS) for pure CsI and CsOH particles employing a DMT-CCN counter. The essential parameters estimated from these measurements are activation diameter and size-averaged hygroscopicity (κ) at targeted SS levels. Experimental results were also compared with the standard theories available in the literature. Accuracy of the deposition rates for these particles (if released) in reactor component systems estimated by nuclear reactor accident analyses codes will improve when CCN properties are also taken into account. CCN efficiency spectra and activation diameters at specific SS for CsI and CsOH particles are being reported for the first time. Information on these properties strengthen the database which is vital for simulating behavioral characteristics of these particles. This in turn has capability to improve environmental source term estimations in the most unlikely scenario of containment breach during severe reactor accident conditions.

Annales Geophysicae

In this paper, we present the effect of total solar eclipse on surface O 3 , NO, NO 2 , NH 3 , CO... more In this paper, we present the effect of total solar eclipse on surface O 3 , NO, NO 2 , NH 3 , CO mixing ratio and the meteorological parameters on 15 January 2010 at Thiruvanathapuram, India. On the day of total solar eclipse (i.e., 15 January 2010), the decrease in mixing ratio of surface O 3 and NO 2 is observed after the beginning of the solar eclipse events (11:15 to 15:30). Decrease in surface O 3 may be due to decreased efficiency of the photochemical ozone formation, whereas, mixing ratio of NO and NH 3 have been changed following the night time chemistry. Surface O 3 reduced to 20.3 ppb after 22 min of full phase of the eclipse. During the solar eclipse period, the ambient temperature and wind speed have decreased, whereas, relative humidity has increased as expected.

Large aerosol optical depth (AOD) observed over the Indian subcontinent during the monsoon season... more Large aerosol optical depth (AOD) observed over the Indian subcontinent during the monsoon
season in the satellite data challenges the common notion of aerosol washout by monsoon rain.
Here, we examined recovery of aerosol field after washout by monsoon rain over various rainfall homogeneous zones of India in view of the duration of rainfall, recovery time and source
strength. Mean (±1 standard deviation) seasonal aerosol optical depth, AOD is highest over the
central northeast 1 (0.74±0.22) followed by central northeast 2 (0.60±0.11), northwest
(0.61±0.15), west-central (0.54±0.13), northeast (0.29±0.08), peninsular India (0.39±0.07) and
hilly region (0.33±0.08) in the monsoon season. Post-washout aerosol recovery in India is not a
linear function to the recovery period relative to the two successive satellite overpasses. Fastest
recovery is observed in the central northeast region dominated by anthropogenic emission. In
general, washout is more for 9-hour spell than 3-hour spell, but not spatially uniform over the
various rainfall homogeneous zones. In central northeast region it is observed that updraft plays
an important role in post precipitation aerosol build up whereas in dust-dominated northwest
India, monsoon rainfall (whenever occurs) suppresses dust emission because of the increased soil
moisture and therefore inhibits the recovery. The number of grids where washout outweighs
recovery during the monsoon season for a 3-hour rainfall increases by 5.6% with an increase in
rain rate from <2 mm/day to >4 mm/day, while the corresponding increase for a 9-hour rainfall
event is 2.8%. AOD reduces in ‘cloudy-sky’ condition relative to ‘clear-sky’ condition because
aerosols are scavenged by cloud drops as the clouds grow vertically during the monsoon.
Quantitatively, AOD decreases by 16% per 100 hPa increase in cloud base height.

This paper presents the emission factors (EF) of particulate matter (PM), organic carbon (OC), el... more This paper presents the emission factors (EF) of particulate matter (PM), organic carbon (OC), elemental carbon (EC), SO2, NO, NO2 and water soluble ions emitted by residential biomass fuels collected from the rural sector of Western India. Burning process has been simulated using a dilution chamber. Average EF of PM, OC and EC from fuel wood (FW), agricultural residues (AR) and dung cakes (DC) from Western India are estimated as: PM: 1.69 ± 0.98 g kg-1, 2.15 ± 1.00 g kg-1 and 5.37 ± 3.90 g kg-1; OC: 0.43 ± 0.29 g kg-1, 00.54 ± 0.22 g kg-1, 1.14 ± 0.67 g kg-1; EC: 0.25 ± 0.16 g kg-1, 0.23 ± 0.11 g kg-1 and 0.14 ± 0.08 g kg-1 respectively. Similarly, the average EF of SO2, NO and NO2 from FW, AR and DC are determined to be: SO2: 0.66 ± 0.37 g kg-1, 0.29 ± 0.45 g kg-1 and 0.74 ± 0.48 g kg-1; NO: 0.55 ± 0.25 g kg-1, 0.74 ± 0.37 g kg-1 and 0.50 ± 0.23 g kg-1; NO2: 1.05 ± 0.49 g kg-1, 1.41 ± 0.81 g kg-1 and 0.91 ± 0.45 g kg-1 respectively. Cl- has the highest average EF (FW: 97.03 ± 74.98 mg kg-1, AR: 175.71 ± 145.78mg kg-1, DC: 158.15 ± 109.07 mg kg-1) among the anions, followed by PO43-(FW: 116.59 ± 63.43 mg kg-1, AR: 58.45 ± 1.42 mg kg-1, DC: 85.77 ± 78.85 mg kg-1) and NO3- (FW: 64.23 ± 68.38 mg kg-1, AR: 36.78 ± 22.80 mg kg-1, DC: 50.25 ± 49.33 mg kg-1). Similarly, among the cations, the highest emitters are Na+ (FW: 40.25 ± 26.64 mg kg-1; AR: 47.96 ± 18.35 mg kg-1, DC: 30.51 ± 23.39 mg kg-1), K+ (FW: 29.32 ± 23.95 mg kg-1, AR: 50.89 ± 34.62 mg kg-1, DC: 18.23 ± 14.54 mg kg-1) and NH4+ (FW: 27.93 ± 22.59 mg kg-1; AR: 46.37 ± 41.79 mg kg-1, DC: 41.74 ± 36.01 mg kg-1). The total emissions of trace gases, PM and its chemical composition from FW, AR and DC have been calculated using laboratory generated EFs over Western India.

"Source apportionment study of aerosols over Bay of Bengal (BOB) were investigated during Integr... more "Source apportionment study of aerosols over Bay of Bengal (BOB) were investigated
during Integrated Campaign on Aerosol Radiation Budget (ICARB) in the premonsoon
(March-April 2006) and winter season (December-January 2008-09) season. Positive
matrix factorization (PMF) was applied to identify sources of ambient particulate matter
using daily chemical composition data collected in the premonsoon (TSP) and winter
season (PM10). Sea salt (SS), secondary aerosol (SA), Si-dust, fossil fuel combustion
(FFC), biomass burning (BB) sources have been identified in both the seasons,
however their relative contribution were different. The combined contribution of Si-dust,
secondary aerosol and fossil fuel combustion, constitute ~ 67% of particulate matter in
premonsoon, whereas, secondary aerosols and biomass burning were the major
contributors (63.2%) to particulate matter in winter season. The identified sources
effectively predict the measured particulate concentration in the premonsoon (r2 =
0.74) and winter season (r2 = 0.82). Another receptor model, principal component
analysis (PCA) was done to increase the plausibility of the results obtained by PMF.
PCA resulted in the identification of the sources that were comparable to the PMF
outputs. PCA of TSP in the premonsoon season resulted in the extraction of three
components (crustal dust + secondary aerosol, biomass burning, fossil fuel combustion
+ industrial emission) that explained the 83% of the variance in the data. Similarly, in
winter season, PCA resulted in the extraction of four components (biomass burning +
secondary aerosol, industrial emission, crustal dust, sea salt) that explained the 86% of
the variance of the data."

Particulate polycyclic aromatic hydrocarbon (PAH) concentrationwas estimated during Integrated C... more Particulate polycyclic aromatic hydrocarbon (PAH) concentrationwas estimated during Integrated
Campaign on Aerosol, Gases and Radiation Budget (ICARB-W) in winter (2008–2009) on board
the Sagar Kanya over Bay of Bengal (BOB). The concentration of particulate PAH (Ó11 6.65 ±
2.86 ng/m3) over BOB ranged from 0.28 ng/m3 to 1.15 ng/m3. The concentration ofmiddle and high
molecular weight PAHs (4–6 rings), accounted for N50% of total PAHs. Analysis of photochemical
oxidation using ratios of BaA/Chy and BaP/BbF suggested the fresh release of air masses from local
sources or from the nearest coastal areas of BOB. Principal component analysis (PCA) and
correlation between tPAHs, nss-K+, nss-SO4 2., NO3
., organic carbon (OC) and elemental carbon
(EC) suggested that motor vehicle emission, biomass burning and coal combustion may be the
possible principal sources of PAHs over BOB during the study period.

The highly populated Indian regions are currently in a phase of rapid economic growth resulting i... more The highly populated Indian regions are currently in a phase of rapid economic growth resulting in high
emissions of carbonaceous aerosols. This leads to poor air quality and impact on climate. The chemical
composition of carbonaceous aerosols has rarely been studied in industrial areas of India. Here, we
investigated carbonaceous aerosols in particulate matter (PM) on monthly basis in the industrial area of Delhi
in 2011. The concentrations of organic C and elemental C in PM10 were analyzed. Results show a clear
seasonal variability of organic and elemental C. PM10 ranged 95.9–453.5 μg m−3, organic C ranged 28.8–
159.4 μg m−3, and elemental C ranged 7.5–44.0 μg m−3; those values were higher than the reported values.
Organic and elemental C were correlated with each other in pre-monsoon and winter seasons, implying the
existence of similar emission sources such as coal combustion, biomass burning and vehicular exhaust. The
annual average contribution of total carbonaceous aerosols in PM10 was estimated as 62 %.

Polycyclic aromatic hydrocarbons (PAHs) are of special interest due to their carcinogenicity, and... more Polycyclic aromatic hydrocarbons (PAHs) are of special interest due to their carcinogenicity, and ubiquitous presence in the environment. Emissions of PAH vary with use of biomass fuels. In this study, the experimentally determined emission factors and emission estimates of PAH emitted from biomass fuels (dung cake, fuelwood and crop residue) from rural household of six states (Delhi, Uttar Pradesh, Punjab, Haryana, Uttarakhand and Bihar) over the IGP, India, are presented. The gaseous phase and particulate phase PAHs emissions are simultaneously determined from various biomass fuels. The average emission factors of total PAHs from dung cakes, fuelwood and crop residue over the IGP, India are estimated as 59.5 ± 19.9 mg kg−1, 52.5 ± 19.6 mg kg−1 and 40.9 ± 15.2 mg kg−1 respectively. The emission factor of particulate phase PAHs (56.5 mg kg−1, 45.3 mg kg−1 and 35.8 mg kg−1) was found higher as compared to gaseous phase PAHs (3.1 mg kg−1, 7.2 mg kg−1 and 5.1 mg kg−1) from dung cakes, fuel-wood and crop residue, respectively. Anthracene, fluoranthene, pyrene, benzo[a]anthracene and chrysene are predominant PAHs in all biomass fuels. The emission estimates of PAH over IGP are determined as 2.95 ± 0.98 Gg yr−1, 3.13 ± 1.08 Gg yr−1 and 0.66 ± 0.26 Gg yr−1 from dung cakes, fuelwood and crop residue, respectively.

In the present paper, we have determined emission factor of chemical composition of the emission ... more In the present paper, we have determined emission factor of chemical composition of the emission from the burning of biomass (e.g. Dung cake, Acacia, Neem, Mulberry, Indian Rosewood, Pigeon pea etc.) commonly used as a residential fuel in the rural sector of Indo-Gangetic Plain (IGP) (Delhi, Punjab, Haryana, Uttar Pradesh, Bihar and West Bengal), India. For comparison, we have selected only those biomass fuels, which are used in at least three of the above mentioned states. Dung cake from all the states reports highest emission of particulate matter (PM) (15.68 g Kg−1), Organic Carbon (OC) (4.32 g Kg−1) and Elemental Carbon (EC) (0.51 g Kg−1). Among all biomass fuels studied, agricultural residue reports substantial amount of emission of Na+ (104 mg Kg−1), K+ (331 mg Kg−1) and Cl− (447 mg Kg−1) particularly in Pigeon pea and Mustard stem. Eucalyptus (fuel wood) emits large amounts of Ca2+ (21.47 mg Kg−1) and NO3− (614 mg Kg−1). The emission of PM from dung cake is higher in Delhi (19.31 g Kg−1) and followed by Uttar Pradesh (17.58 g Kg−1) > Haryana (15.46 g Kg−1) > Bihar (14.99 g Kg−1) > Punjab (12.06 g Kg−1) > West Bengal (5.90 g Kg−1). Carbonaceous aerosols (OC and EC) and dominant Ionic species (Cl−, K+, SO42−, NO3− and PO43−) are altogether contributing 40-70% of total emissions. Characteristics and ratios of chemical species of emissions may help to develop a methodology of discriminating the sources of ambient particulate matter. Using a laboratory determined emission factor of chemical species, we have determined the emission budget over IGP, India.

Biomass burning emits large amount of aerosols and trace gases into the atmosphere, which have s... more Biomass burning emits large amount of aerosols and trace gases into the atmosphere, which have
significant impact on atmospheric chemistry and climate. In the present study, we have selected seven
Indian states (Delhi, Punjab, Haryana, Uttar Pradesh, Uttarakhand, Bihar and West Bengal) over the IGP,
India. Samples of biomass fuel (FuelWood, Crop Residue and Dung Cake) from rural household have been
collected (Saud et al., 2011a). The burning process has been simulated using a dilution sampler following
the methodology developed by Venkatraman et al. (2005). In the present study, emission factor represents
the total period of burning including pyrolysis, flaming and smoldering. We have determined the
emission factors of organic carbon (OC) and elemental carbon (EC) from different types of biomass fuels
collected over the study area. Average emission factors of OC from dung cake, fuel wood and crop residue
over IGP, India are estimated as 3.87 1.09 g kg1, 0.95 0.27 g kg1, 1.46 0.73 g kg1, respectively.
Similarly, average emission factors of EC from dung cake, fuel wood and crop residue over IGP, India are
found to be 0.49 0.25 g kg1, 0.35 0.07 g kg1 and 0.37 0.14 g kg1, respectively. Dung cake and
crop residue are normally not used in Uttarakhand. Annual budget of OC and EC from biomass fuels used
as energy in rural households of IGP, India is estimated as 361.96 170.18 Gg and 56.44 29.06 Gg
respectively. This study shows the regional emission inventory from Indian scenario with spatial
variability.

Concentrations of ambient NH3, NO, NO2 and SO2 were measured over Bay of Bengal (BoB) during 28 ... more Concentrations of ambient NH3, NO, NO2 and
SO2 were measured over Bay of Bengal (BoB) during 28
December 2008 to 25 January 2009 to study their diurnal
variation and relationship of NH3 with other trace gases
over BoB. The measurements were done under the winter
phase of Integrated Campaign on Aerosols and Radiation
Budget (W ICARB). For the first time, ambient NH3 was
monitored precisely over BoB based on chemiluminescence
method, having estimation efficiency more precise than the
chemical trap method. The average concentration of ambient
NH3, NO, NO2 and SO2 were recorded as 4.78±1.68,
1.89±1.26, 0.31±0.14 and 0.80±0.30 μgm−3, respectively,
over BoB. The prominent latitudinal and longitudinal
variations of the trace gases were observed over BoB,
whereas NH3 and NO showed the non-significant diurnal
variation. Results reveal that the concentration of ambient
NH3 negatively correlated with ambient NO2 (r2 =−0.56),
SO2 (r2 =−0.58) and ambient temperature (r2 =−0.27) during
the study.

Ammonia (NH3 ) not only plays important role in acidification and eutrophication of aquatic ecos... more Ammonia (NH3 ) not only plays important role in
acidification and eutrophication of aquatic ecosystems1
but also neutralizing atmospheric acids (H2SO4, HNO3
and HCl) and forms inorganic aerosols2-4 [(NH4)2SO4,
NH4NO3 and NH4Cl]. Agricultural practices, livestock,
transport and industrial activities2,5 are different
anthropogenic sources of atmospheric NH3, along with
natural sources like forest fire and emission from soil.
This study estimated concentration of NH3, NO and NO2
and related particulate matter (PM10) over northern Indo
Gangetic Plain (IGP) and correlated NH3 concentration
with related particulates in the formation of secondary
aerosol over IGP.

ScienceDirect, 2020

Atmospheric Research, 2020

Annales Geophysicae