Publications by authors named "Sayantan Sarkar"

15 Publications

  • Page 1 of 1

Peat-forest burning smoke in Maritime Continent: Impacts on receptor PM and implications at emission sources.

Environ Pollut 2021 Apr 2;275:116626. Epub 2021 Feb 2.

Department of Civil and Environmental Engineering, National University of Singapore, 117576, Singapore; NUS Environmental Research Institute, National University of Singapore, 117411, Singapore. Electronic address:

This study characterizes the impacts of transported peat-forest (PF) burning smoke on an urban environment and evaluates associated source burning conditions based on carbon properties of PM at the receptor site. We developed and validated a three-step classification that enables systematic and more rapid identification of PF smoke impacts on a tropical urban environment with diverse emissions and complex atmospheric processes. This approach was used to characterize over 300 daily PM data collected during 2011-2013, 2015 and 2019 in Singapore. A levoglucosan concentration of ≥0.1 μg/m criterion indicates dominant impacts of transported PF smoke on urban fine aerosols. This approach can be used in other ambient environments for practical and location-dependent applications. Organic carbon (OC) concentrations (as OC indicator) can be an alternate to levoglucosan for assessing smoke impacts on urban environments. Applying the OC concentration indicator identifies smoke impacts on ∼80% of daily samples in 2019 and shows an accuracy of 51-86% for hourly evaluation. Following the systematic identification of urban PM predominantly affected by PF smoke in 2011-2013, 2015 and 2019, we assessed the concentration ratio of char-EC/soot-EC as an indicator of smoldering- or flaming-dominated burning emissions. When under the influence of transported PF smoke, the mean concentration ratio of char-EC to soot-EC in urban PM decreased by >70% from 8.2 in 2011 to 2.3 in 2015 but increased to 3.8 in 2019 (p < 0.05). The reversed trend with a 65% increase from 2015 to 2019 shows stronger smoldering relative to flaming, indicating a higher level of soil moisture at smoke origins, possibly associated with rewetting and revegetating peatlands since 2016.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envpol.2021.116626DOI Listing
April 2021

Sources and atmospheric processing of brown carbon and HULIS in the Indo-Gangetic Plain: Insights from compositional analysis.

Environ Pollut 2020 Dec 19;267:115440. Epub 2020 Aug 19.

Department of Earth Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, 741246, Nadia, India; School of Engineering, Indian Institute of Technology (IIT) Mandi, Kamand, Himachal Pradesh, 175075, India. Electronic address:

We present here spectroscopic compositional analysis of brown carbon (BrC) and humic-like substances (HULIS) in the Indian context under varying conditions of source emissions and atmospheric processing. To this end, we study bulk water-soluble organic matter (WSOM), neutral- and acidic-HULIS (HULIS-n and HULIS-a), and high-polarity (HP)-WSOM collected in the eastern Indo-Gangetic Plain (IGP) with respect to UV-Vis, fluorescence, FT-IR, H NMR and C characteristics under three aerosol regimes: photochemistry-dominated summer, aged biomass burning (BB)-dominated post-monsoon, and fresh BB-dominated winter. Absorption coefficients (b; Mm) of WSOM and HULIS fractions increase by a factor of 2-9 during winter as compared to summer, with HULIS-n dominating total HULIS + HP-WSOM absorption (73-81%). Fluorophores in HULIS-n appear to contain near-similar levels of aromatic and unsaturated aliphatic conjugation across seasons, while HULIS-a exhibits distinctively smaller-chain structures in summer and post-monsoon. FT-IR spectra reveals, among others, strong signatures of aromatic phenols in winter WSOM suggesting a BB-related origin. H NMR-based source attribution coupled with back trajectory analysis indicate the presence of secondary and BB-related organic aerosol (SOA and BBOA) in the post-monsoon and winter, and marine-derived OA (MOA) in the summer, which is supported by C measurements. Overall, these observations uncover a complex interplay of emissions and atmospheric processing of carbonaceous aerosols in the IGP.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envpol.2020.115440DOI Listing
December 2020

Optical properties of aerosol brown carbon (BrC) in the eastern Indo-Gangetic Plain.

Sci Total Environ 2020 May 4;716:137102. Epub 2020 Feb 4.

Department of Earth Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, 741246, Nadia, India; Centre for Climate and Environmental Studies, Indian Institute of Science Education and Research (IISER) - Kolkata, Mohanpur, 741246, Nadia, India. Electronic address:

We report here measurements of aerosol black carbon (BC) and aqueous and methanol-extractable brown carbon (BrC and BrC) from a receptor location in the eastern Indo-Gangetic Plain (IGP) under two aerosol regimes: the photochemistry-dominated summer and biomass burning (BB) dominated post-monsoon. We couple time-resolved measurements of BC and aerosol light absorption coefficients (b) with time-integrated analysis of BrC UV-Vis and fluorescence characteristics, along with measurements of total and water-soluble organic carbon (OC and WSOC), and ionic species (NH, K, NO). In the BB regime, BC and its BB-derived fraction (BC) increased by factors of 3-4 over summertime values. In comparison, b and b (absorption coefficients of BrC and BrC at 365 nm) increased by a factor of 5 (9.7 ± 7.8 vs 2.1 ± 1.4 Mm) and 2.5 (17.2 ± 9.0 vs 6.9 ± 2.9 Mm), respectively, in the BB period over summer, and were highly correlated (r = 0.82-0.87; p < 0.01) with the BB-tracer nssK. The wavelength dependence of b (Ångstrom exponent: 5.9-6.2) and the presence of characteristic fluorescence peaks at 420-430 nm suggested presence of humic-like substances (HULIS) in the aged BB aerosol, while significant association between BrC and NO (r = 0.73; p < 0.01) possibly indicated formation of water-soluble nitroaromatic compounds. BrC contributed 55% to total BrC absorption at 300-400 nm while that for the water-insoluble component (WI-BrC) increased from 41% at 340 nm to ~60% at 550 nm, suggesting formation of water-insoluble polycyclic aromatic hydrocarbons (PAHs) and/or N-PAHs. Mass absorption efficiencies at 365 nm (MAE) of BrC and BrC in the BB regime (0.95 ± 0.45 and 1.17 ± 0.78 m g, respectively) were in line with values expected from photobleaching of BB source emissions after transport to the eastern IGP. Overall, BrC and BrC were significant components of light absorbing aerosol in the BB regime, with contributions of 9 ± 5% and 16 ± 7%, respectively, to radiative forcing vis-à-vis BC in the 300-400 nm range.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2020.137102DOI Listing
May 2020

Spatially resolved distribution, sources and health risks of heavy metals in size-fractionated road dust from 57 sites across megacity Kolkata, India.

Sci Total Environ 2020 Feb 27;705:135805. Epub 2019 Nov 27.

Department of Earth Sciences, Indian Institute of Science Education and Research (IISER), Kolkata, Mohanpur 741246, Nadia, India.; Centre for Climate and Environmental Studies, Indian Institute of Science Education and Research (IISER), Kolkata, Mohanpur 741246, Nadia, India.. Electronic address:

This work reports the first assessment of contamination levels, source contributions and health risks associated with heavy metals (HMs) in road dust from Kolkata, the second-most polluted metropolis in India. To this end, samples collected from 57 locations across 6 land-use categories: residential, roadside, traffic, railway, port and industrial areas in the city during 2018 were analyzed for 11 major and trace metals (Ca, Mg, Fe, Al, Mn, Ni, V, Cu, Zn, Cr, Pb) in three size fractions: <75 μm, 75-125 μm and 125-300 μm. Overall, Mn, Zn, Cr, Pb, V, Cu and Ni were enriched in the smallest fraction by factors of 1.2-2.7. Based on metal distribution across land-use categories, crustal dust (Fe, Al, V), construction activities (Ca, Mg), metallurgical processes (Pb), and non-exhaust abrasive emissions from brake, tire and paint wear (Cu, Zn, Cr) were found to be significant. HMs such as Cu, Zn, Cr and Pb were considerably enriched over background levels as suggested by three contamination indices: Enrichment Factor (EF; overall range: 2.4-12.0), Index of Geo-accumulation (I; overall range: 1.1-3.4), and Pollution Index (PI; overall range: 3.1-15.6). Geospatial mapping identified HM contamination hotspots (integrated PI >4) in west-central and northern parts (the older sections) of the city represented by industrial, port, and traffic-congested residential areas. Using positive matrix factorization (PMF), the following sources were apportioned for the three size fractions: crustal dust (48-66%), construction activities (18-20%), vehicular abrasion (7-21%), industrial emissions (5-8%), a Cr-dominated mixed source (6%) and an unassigned source (7%). Finally, health risk assessment in the form of cumulative hazard index (HI) and incremental lifetime cancer risk (ILCR) found that children (mean HI: 1.29 and ILCR: 2E-04) are comparatively more vulnerable than adults (mean HI: 0.22 and ILCR: 8E-05) to HM exposure, with the ingestion exposure pathway dominating over dermal contact and inhalation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2019.135805DOI Listing
February 2020

Size-segregated deposition of atmospheric elemental carbon (EC) in the human respiratory system: A case study of the Pearl River Delta, China.

Sci Total Environ 2020 Mar 2;708:134932. Epub 2019 Nov 2.

School of Atmospheric Sciences, & Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Guangzhou 510275, P. R. China; Southern Laboratory of Ocean Science and Engineering (Guangdong, Zhuhai), Zhuhai 519000, P.R. China. Electronic address:

It has increasingly become apparent in recent years that atmospheric elemental carbon (EC) is potentially a more sensitive indicator of human health risks from ambient aerosol exposure compared to particulate mass. However, a comprehensive evaluation of the factors affecting EC exposure is lacking so far. To address this, we performed measurements of size-segregated EC in Guangzhou, China, followed by an estimation of deposition in the human respiratory system. Most ambient EC was in the fine mode suggesting significant cloud processing, and ~40% was deposited in the human respiratory tract, with predominant deposition in the head region (47%), followed by the pulmonary (30%) and tracheobronchial (23%) regions. A significant fraction (36%) of deposited EC were coarse particles indicating the need to consider coarse-mode EC in future health effect studies. Infants and children exhibited greater vulnerability to EC exposure than adults, and the deposition amount varied linearly with breathing rate, a proxy for physical exertion. The nature of breathing was found to constrain EC inhalation significantly, with oronasal breathing associated with lower total deposition and nasal breathing leading to lower deposition in the tracheobronchial and pulmonary regions. Overall, these observations strengthen the need to include EC as an additional air quality indicator.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2019.134932DOI Listing
March 2020

Evaluation of factors influencing secondary organic carbon (SOC) estimation by CO and EC tracer methods.

Sci Total Environ 2019 Oct 29;686:915-930. Epub 2019 May 29.

School of Atmospheric Sciences, Sun Yat-sen University, Guangzhou 510275, PR China; Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Guangzhou 510275, PR China; Southern Laboratory of Ocean Science and Engineering (Guangdong, Zhuhai), Zhuhai 519000, China. Electronic address:

Secondary organic carbon (SOC) is known to account for a substantial fraction of fine-mode carbonaceous aerosol. Owing to a limited understanding of SOC formation processes and the absence of direct measurement methods, SOC concentrations are mostly estimated using a tracer-based method utilizing either elemental carbon (EC) or carbon monoxide (CO) as tracers. The performance of these tracer-based methods depends heavily on accurate determination of the (OC/Tracer) value. The minimum R squared (MRS) method is currently recognized as a relatively reasonable tool to determine (OC/Tracer). This study estimated SOC based on the MRS method with EC and CO as tracers, followed by the Monte Carlo method to analyze quantitatively the effects of measurement uncertainty, emission scenario and sample size on SOC estimates. We report here four major findings: i) the concentration of O was used as an indicator to atmospheric secondary reaction potential, and it was found that the mass proportion of SOC in total OC estimated by CO as the tracer is more consistent with the seasonality of actual secondary reaction potential; ii) the estimation results are highly sensitive to the measurement uncertainty in different emission scenarios, which leads us to conclude that the CO tracer method is more robust than the EC tracer method due to large inherent uncertainties in current EC measurements; iii) oversimplification of emission scenarios has substantial impacts on the estimated SOC value, and careful evaluation of the interdependence between sources should be performed to minimize this bias; and iv) the estimation bias of SOC can be reduced by increasing the sample size, and the tracer method can be expected to generate robust results for sample sizes over 1000. These findings are important in terms of providing a reference to choose appropriate tracers, emission scenarios and sample sizes for robust estimation of SOC in future studies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2019.05.402DOI Listing
October 2019

Impacts of peat-forest smoke on urban PM in the Maritime Continent during 2012-2015: Carbonaceous profiles and indicators.

Environ Pollut 2019 May 20;248:496-505. Epub 2019 Feb 20.

NUS Environmental Research Institute, National University of Singapore, 5A Engineering Drive 1, 117411, Singapore; Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, 117576, Singapore. Electronic address:

This study characterizes impacts of peat-forest (PF) smoke on an urban environment through carbonaceous profiles of >260 daily PM samples collected during 2012, 2013 and 2015. Organic carbon (OC) and elemental carbon (EC) comprising eight carbonaceous fractions are examined for four sample groups - non-smoke-dominant (NSD), smoke-dominant (SD), episodic PM samples at the urban receptor, and near-source samples collected close to PF burning sites. PF smoke introduced much larger amounts of OC than EC, with OC accounting for up to 94% of total carbon (TC), or increasing by up to 20 times in receptor PM. SD PM at the receptor site and near-source samples have OC3 and EC1 as the dominant fractions. Both sample classes also exhibit char-EC >1.4 times of soot-EC, characterizing smoldering-dominant PF smoke, unlike episodic PM at the receptor site featuring large amounts of pyrolyzed organic carbon (POC) and soot-EC. Relative to the mean NSD PM at the receptor, increasing strength of transboundary PF smoke enriches OC3 and OC4 fractions, on average, by factors of >3 for SD samples, and >14 for episodic samples. A peat-forest smoke (PFS) indicator, representing the concentration ratio of (OC2+OC3+POC) to soot-EC, shows a temporal trend satisfactorily correlating with an organic marker (levoglucosan) of biomass burning. The PFS indicator systematically differentiates influences of PF smoke from source to urban receptor sites, with a progressive mean of 3.6, 13.4 and 20.1 for NSD, SD and episodic samples respectively at the receptor site, and 54.7 for the near-source PM. A PFS indicator of ≥5.0 is proposed to determine dominant influence of transboundary PF smoke on receptor urban PM in the equatorial Asia with ∼90% confidence. Assessing >2900 hourly OCEC data in 2017-2018 supports the applicability of the PFS indicator to evaluate hourly impacts of PF smoke on receptor urban PM in the Maritime Continent.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envpol.2019.02.049DOI Listing
May 2019

Development of Ahmedabad's Air Information and Response (AIR) Plan to Protect Public Health.

Int J Environ Res Public Health 2018 07 10;15(7). Epub 2018 Jul 10.

Indian Institute of Public Health, Gandhinagar (IIPH-G), Gandhinagar 382042, India.

Indian cities struggle with some of the highest ambient air pollution levels in the world. While national efforts are building momentum towards concerted action to reduce air pollution, individual cities are taking action on this challenge to protect communities from the many health problems caused by this harmful environmental exposure. In 2017, the city of Ahmedabad launched a regional air pollution monitoring and risk communication project, the Air Information and Response (AIR) Plan. The centerpiece of the plan is an air quality index developed by the Indian Institute of Tropical Meteorology’s System for Air Quality and Weather Forecasting and Research program that summarizes information from 10 new continuous air pollution monitoring stations in the region, each reporting data that can help people avoid harmful exposures and inform policy strategies to achieve cleaner air. This paper focuses on the motivation, development, and implementation of Ahmedabad’s AIR Plan. The project is discussed in terms of its collaborative roots, public health purpose in addressing the grave threat of air pollution (particularly to vulnerable groups), technical aspects in deploying air monitoring technology, and broader goals for the dissemination of an air quality index linked to specific health messages and suggested actions to reduce harmful exposures. The city of Ahmedabad is among the first cities in India where city leaders, state government, and civil society are proactively working together to address the country’s air pollution challenge with a focus on public health. The lessons learned from the development of the AIR Plan serve as a template for other cities aiming to address the heavy burden of air pollution on public health. Effective working relationships are vital since they form the foundation for long-term success and useful knowledge sharing beyond a single city.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijerph15071460DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6068810PMC
July 2018

Characterization of diurnal variations of PM acidity using an open thermodynamic system: A case study of Guangzhou, China.

Chemosphere 2018 Jul 21;202:677-685. Epub 2018 Mar 21.

Department of Chemical and Bimolecular Engineering, National University of Singapore, 117576, Singapore. Electronic address:

Aerosol acidity has significant implications for atmospheric processing, and high time-resolution measurements can provide critical insights into those processes. This paper reports diurnal variations of aerosol acidity characterized using an open thermodynamic system in Guangzhou, China. Hourly measurements of PM-associated ionic species and related parameters were carried out during June-September 2013 followed by application of the Extended Aerosol Inorganic Model in open mode to estimate aerosol pH. The model-estimated aerosol pH was 2.4 ± 0.3, and the pH diurnal profile exhibited peaks in the early morning (6 a.m.) and troughs in the afternoon (2 p.m.) that appeared to be constrained by liquid water content (LWC) and free H. A linear regression model was developed to predict aerosol pH, which performed strongly with 4 variables during daytime (NH, Na, SO and RH; R = 0.95) and 3 during nighttime (NH, SO and RH; R = 0.91). The effect of aerosol acidity on the partitioning of HNO, HCl and NH was studied based on theoretical considerations and measurement data. The fractions in particulate phase for acidic compounds correlated strongly with pH (R = 0.64-0.69) while that for NH, interestingly, was weak (R = 0.17). Analytical expressions were developed to explain these observations and it was concluded that the partitioning of HCl and HNO was more sensitive to pH compared to that of NH. These results are significant in terms of potential atmospheric depletion rates of HCl and HNO in the region and stress the need for future studies in this direction.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chemosphere.2018.03.127DOI Listing
July 2018

A quantitative assessment of distributions and sources of tropospheric halocarbons measured in Singapore.

Sci Total Environ 2018 Apr 29;619-620:528-544. Epub 2017 Nov 29.

NUS Environmental Research Institute, National University of Singapore, 5A Engineering Drive 1, Singapore 117411, Singapore; Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576, Singapore.

This work reports the first ground-based atmospheric measurements of 26 halocarbons in Singapore, an urban-industrial city-state in Southeast (SE) Asia. A total of 166 whole air canister samples collected during two intensive 7 Southeast Asian Studies (7SEAS) campaigns (August-October 2011 and 2012) were analyzed for C-C halocarbons using gas chromatography-electron capture/mass spectrometric detection. The halocarbon dataset was supplemented with measurements of selected non-methane hydrocarbons (NMHCs), C-C alkyl nitrates, sulfur gases and carbon monoxide to better understand sources and atmospheric processes. The median observed atmospheric mixing ratios of CFCs, halons, CCl and CHCCl were close to global tropospheric background levels, with enhancements in the 1-17% range. This provided the first measurement evidence from SE Asia of the effectiveness of Montreal Protocol and related national-scale regulations instituted in the 1990s to phase-out ozone depleting substances (ODS). First- and second-generation CFC replacements (HCFCs and HFCs) dominated the atmospheric halocarbon burden with HFC-134a, HCFC-22 and HCFC-141b exhibiting enhancements of 39-67%. By combining near-source measurements in Indonesia with receptor data in Singapore, regionally transported peat-forest burning smoke was found to impact levels of several NMHCs (ethane, ethyne, benzene, and propane) and short-lived halocarbons (CHI, CHCl, and CHBr) in a subset of the receptor samples. The strong signatures of these species near peat-forest fires were potentially affected by atmospheric dilution/mixing during transport and by mixing with substantial urban/regional backgrounds at the receptor. Quantitative source apportionment was carried out using positive matrix factorization (PMF), which identified industrial emissions related to refrigeration, foam blowing, and solvent use in chemical, pharmaceutical and electronics industries as the major source of halocarbons (34%) in Singapore. This was followed by marine and terrestrial biogenic activity (28%), residual levels of ODS from pre-Montreal Protocol operations (16%), seasonal incidences of peat-forest smoke (13%), and fumigation related to quarantine and pre-shipment (QPS) applications (7%).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2017.11.087DOI Listing
April 2018

Accumulation and risks of polycyclic aromatic hydrocarbons and trace metals in tropical urban soils.

Environ Monit Assess 2014 May 29;186(5):2907-23. Epub 2013 Dec 29.

Environmental Monitoring and Assessment Laboratory, School of Environmental Sciences, Jawaharlal Nehru University, Room number 325, New Delhi, 110067, India,

The study deals with the combined contribution of polycyclic aromatic hydrocarbons (PAHs) and metals to health risk in Delhi soils. Surface soils (0-5 cm) collected from three different land-use regions (industrial, flood-plain and a reference site) in Delhi, India over a period of 1 year were characterized with respect to 16 US Environmental Protection Agency priority PAHs and five trace metals (Zn, Fe, Ni, Cr and Cd). Mean annual ∑16PAH concentrations at the industrial and flood-plain sites (10,893.2 ± 2826.4 and 3075.4 ± 948.7 μg/kg, respectively) were ~15 and ~4 times, respectively, higher than reference levels. Significant spatial and seasonal variations were observed for PAHs. Toxicity potentials of industrial and flood-plain soils were ~88 and ~8 times higher than reference levels. Trace metal concentrations in soils also showed marked dependencies on nearness to sources and seasonal effects. Correlation analysis, PAH diagnostic ratios and principal component analysis (PCA) led to the identification of sources such as coal and wood combustion, vehicular and industrial emissions, and atmospheric transport. Metal enrichment in soil and the degree of soil contamination were investigated using enrichment factors and index of geoaccumulation, respectively. Health risk assessment (incremental lifetime cancer risk and hazard index) showed that floodplain soils have potential high risk due to PAHs while industrial soils have potential risks due to both PAHs and Cr.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10661-013-3589-1DOI Listing
May 2014

Risk assessment of inhalation exposure to polycyclic aromatic hydrocarbons in school children.

Environ Sci Pollut Res Int 2014 Jan 19;21(1):366-78. Epub 2013 Jun 19.

Environmental Monitoring and Assessment Laboratory, Room No. 325, School of Environmental Sciences, 1Jawaharlal Nehru University, New Delhi, 110067, India.

Polycyclic aromatic hydrocarbons (PAHs) associated with the inhalable fraction of particulate matter were determined for 1 year (2009-2010) at a school site located in proximity of industrial and heavy traffic roads in Delhi, India. PM10 (aerodynamic diameter ≤10 μm) levels were ∼11.6 times the World Health Organization standard. Vehicular (59.5%) and coal combustion (40.5%) sources accounted for the high levels of PAHs (range 38.1-217.3 ng m(-3)) with four- and five-ring PAHs having ∼80 % contribution. Total PAHs were dominated by carcinogenic species (∼75%) and B[a]P equivalent concentrations indicated highest exposure risks during winter. Extremely high daily inhalation exposure of PAHs was observed during winter (439.43 ng day(-1)) followed by monsoon (232.59 ng day(-1)) and summer (171.08 ng day(-1)). Daily inhalation exposure of PAHs to school children during a day exhibited the trend school hours > commuting to school > resting period in all the seasons. Vehicular source contributions to daily PAH levels were significantly correlated (r = 0.94, p < 0.001) with the daily inhalation exposure level of school children. A conservative estimate of ∼11 excess cancer cases in children during childhood due to inhalation exposure of PAHs has been made for Delhi.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-013-1912-6DOI Listing
January 2014

Profile of PAHs in the inhalable particulate fraction: source apportionment and associated health risks in a tropical megacity.

Environ Monit Assess 2013 Feb 20;185(2):1199-213. Epub 2012 Apr 20.

School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.

The present study proposed to investigate the atmospheric distribution, sources, and inhalation health risks of polycyclic aromatic hydrocarbons (PAHs) in a tropical megacity (Delhi, India). To this end, 16 US EPA priority PAHs were measured in the inhalable fraction of atmospheric particles (PM(10); aerodynamic diameter, ≤ 10 μm) collected weekly at three residential areas in Delhi from December 2008 to November 2009. Mean annual 24 h PM(10) levels at the sites (166.5-192.3 μg m(-3)) were eight to ten times the WHO limit. Weekday/weekend effects on PM(10) and associated PAHs were investigated. Σ(16)PAH concentrations (sum of 16 PAHs analyzed; overall annual mean, 105.3 ng m(-3); overall range, 10.5-511.9 ng m(-3)) observed were at least an order of magnitude greater than values reported from European and US cities. Spatial variations in PAHs were influenced by nearness to traffic and thermal power plants while seasonal variation trends showed highest concentrations in winter. Associations between Σ(16)PAHs and various meteorological parameters were investigated. The overall PAH profile was dominated by combustion-derived large-ring species (85-87 %) that were essentially local in origin. Carcinogenic PAHs contributed 58-62 % to Σ(16)PAH loads at the sites. Molecular diagnostic ratios were used for preliminary assessment of PAH sources. Principal component analysis coupled with multiple linear regression-identified vehicular emissions as the predominant source (62-83 %), followed by coal combustion (18-19 %), residential fuel use (19 %), and industrial emissions (16 %). Spatio-temporal variations and time-evolution of source contributions were studied. Inhalation cancer risk assessment showed that a maximum of 39,780 excess cancer cases might occur due to lifetime inhalation exposure to the analyzed PAH concentrations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10661-012-2626-9DOI Listing
February 2013

Health risk assessment of polycyclic aromatic hydrocarbons and heavy metals via dietary intake of vegetables grown in the vicinity of thermal power plants.

Food Chem Toxicol 2012 May 1;50(5):1642-52. Epub 2012 Feb 1.

Environmental Monitoring and Assessment Laboratory, Room No. 325, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.

Six different vegetables grown in the vicinity of three thermal power plants and a background site in Delhi, India were analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs) and 7 heavy metals (Cd, Cu, Cr, Ni, Zn, Fe and Mn). Annual mean concentrations of PAHs and all metals were found to be significantly higher (ANOVA, p<0.001) at power plant sites as compared to the background site. Higher abundances of coal tracer PAHs such as Phen, Anth, Flan, Pyr and Chry in power plant vegetables suggested possible impacts of coal combustion emissions. Higher ratios of polluted sample-to-background sample of vegetables were found especially for Cr, Cd, Ni and Zn. Spinach and radish showed greater accumulation of PAHs and metals on a mass basis at the power plant sites while vegetables belonging to the gourd family showed highest relative enrichment. Power plant samples showed 184-475% greater metal pollution index (MPI) values as compared to the background location while health risk indices (HRI) for Cd and Ni exceeded the safe limit for most vegetables. Incremental lifetime cancer risk (ILCR) assessment showed that up to 58 excess cancer cases are likely in Delhi for lifetime ingestion exposure to PAHs at their observed concentrations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.fct.2012.01.032DOI Listing
May 2012

Chemical speciation of respirable suspended particulate matter during a major firework festival in India.

J Hazard Mater 2010 Dec 18;184(1-3):321-330. Epub 2010 Aug 18.

Environmental Monitoring and Management Laboratory, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.

Ambient respirable particles (PM ≤ 10 μm, denoted by PM(10)) were characterized with respect to 20 elements, 16 polycyclic aromatic hydrocarbons (PAHs), elemental and organic carbon (EC and OC) during a major firework event-the "Diwali" festival in Delhi, India. The event recorded extremely high 24-h PM(10) levels (317.2-616.8 μg m(-3), 6-12 times the WHO standard) and massive loadings of Ba (16.8 μg m(-3), mean value), K (46.8 μg m(-3)), Mg (21.3 μg m(-3)), Al (38.4 μg m(-3)) and EC (40.5 μg m(-3)). Elemental concentrations as high as these have not been reported previously for any firework episode. Concentrations of Ba, K, Sr, Mg, Na, S, Al, Cl, Mn, Ca and EC were higher by factors of 264, 18, 15, 5.8, 5, 4, 3.2, 3, 2.7, 1.6 and 4.3, respectively, on Diwali as compared to background values. It was estimated that firework aerosol contributed 23-33% to ambient PM(10) on Diwali. OC levels peaked in the post-Diwali samples, perhaps owing to secondary transformation processes. Atmospheric PAHs were not sourced from fireworks; instead, they correlated well with changes in traffic patterns indicating their primary source in vehicular emissions. Overall, the pollutant cocktail generated by the Diwali fireworks could be best represented with Ba, K and Sr as tracers. It was also found that chronic exposure to Diwali pollution is likely to cause at least a 2% increase in non-carcinogenic hazard index (HI) associated with Al, Mn and Ba in the exposed population.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhazmat.2010.08.039DOI Listing
December 2010