Sayantan Sarkar

Indian Institute of Technology Mandi | भारतीय प्रौद्योगिकी संस्थान मंडी · School of Civil and Environmental Engineering

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...

We report measurements of 30 major and trace elements (TEs) in sediment cores from two high-altitude lakes, West Pine Pond (WPP), and Clear Pond (CP), in the Adirondack Mountains of New York State using inductively coupled plasma–mass spectrometry. The data are used to deduce atmospheric deposition histories of TEs over ~130 years. The cores were c...

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 C1-C2 halocarbons using gas chr...

India is currently the second-largest emitter of black carbon (BC) in the world, with emissions projected to rise steadily in the coming decades. In view of the large variations associated with BC emission inventories in this region, model outputs of BC mass and radiative forcing (RF) need to be validated against long-term regionally-representative...

This study provides insights into the fluorophoric composition of aqueous brown carbon (BrCaq) and chemically-separated humic-like substances (HULIS): neutral HULIS (HULIS-n; at pH = 7) and acidic HULIS (HULIS-a; at pH = 2) on a seasonal and day-night basis in the eastern Indo-Gangetic Plain (IGP), India. A coupled approach including excitation-emi...

This study reports size-resolved dithiothreitol (DTT)-based oxidative potential (OP: total and water-soluble) in rural kitchens using liquefied petroleum gas (LPG), firewood (FW), and mixed biomass (MB) fuels in northeastern (NE) India. In comparison to LPG, volume-normalized total OP (OPtotal(v)DTT) was enhanced by a factor of ∼5 in biomass-using...

We present here the first measurements of nitroaromatic compounds (NACs) including nitrophenols (NPs), nitrocatechols (NCs) and nitrosalicylic acids (NSAs) from the Indian subcontinent and their role in constraining brown carbon (BrC) absorption. NACs at a rural receptor site in the eastern Indo-Gangetic Plain (IGP) (annual average: 185±94 ng m-3)...

This study reports day-night and seasonal variations of aqueous brown carbon (BrCaq) and constituent humic-like substances (HULIS) (neutral and acidic HULIS: HULIS-n and HULIS-a) from the eastern Indo-Gangetic Plain (IGP) of India during 2019-2020. This is followed by the application of the receptor model positive matrix factorization (PMF) for opt...

Exposure to a total of 51 targeted and non-targeted polycyclic aromatic hydrocarbons (PAHs) and their oxygenated and alkylated derivatives associated with size-segregated aerosol was investigated in rural kitchens using liquefied petroleum gas (LPG), mixed biomass (MB) and firewood (FW) fuels in northeastern India. The averaged PM10-associated pare...

Methylamines are a class of highly reactive organic alkaline gases in the atmosphere. At present, the gridded emission inventories of amines used in the atmospheric numerical model is mostly based on the amine/ammonia ratio method and do not consider the air-sea exchange of methylamines, which oversimplifies the emission scenario. Marine biological...

This study reports black carbon (BC) characteristics and climate effects for a 22-month period during 2018–2020 at a receptor location in the eastern Indo-Gangetic Plains (IGP). The overall averaged BC mass concentration was 7.8 ± 4.7 μg m−3, and the nighttime average (9.1 ± 6.1 μg m−3) was nearly double that of the daytime (5.8 ± 3.5 μg m−3). BC w...

This study presents the source apportionment of coarse-mode particulate matter (PM10) extracted by 3 receptor models (PCA/APCS, UNMIX, and PMF) at semi-urban sites of the Indian Himalayan region (IHR) during August 2018–December 2019. In this study, water-soluble inorganic ionic species (WSIIS), water-soluble organic carbon (WSOC), carbon fractions...

This presentation highlights the severity in carcinogenic health risk among the biomass-dependent population of rural northeastern India based on the size-resolved measurements of 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) and taking into account the Benzo[a]pyrene equivalent (BaPeq) concentration. It also revealed that the elevated...

Light-absorbing organic aerosols, often referred to as brown carbon (BrC), significantly contribute to atmospheric brown clouds and are a major climate forcing agent over South Asia. In addition to direct emissions in the form of fine mode aerosol, BrC forms secondarily in the atmosphere via homogeneous and heterogeneous chemical reactions involvin...

Humic-like substances (HULIS) are complex macromolecular components of light-absorbing water-soluble organic carbon (brown carbon; BrC aq) consisting of polyacidic and monocyclic/polycyclic structures. HULIS contribute to climate forcing via strong absorption at UV and near-visible wavelengths, and by facilitating the formation of cloud condensatio...

Mass-size distribution of respirable aerosol and 13 associated trace elements (TEs) were investigated in rural kitchens using liquefied petroleum gas (LPG), firewood and mixed biomass fuels across three northeastern Indian states. The averaged PM10 (particulate matter with aerodynamic diameter ≤ 10 μm) and ΣTE concentrations were 403 and 30 μg m-3...

This presentation talks about the comprehensive analysis of mass-size distribution of aerosol and associated trace elements during indoor cooking from six rural locations across three states of northeastern India. It elaborates the variation in i) mass concentration as functions of state and fuel type, ii) size distribution as a function of fuel ty...

This post talks about the size distribution of dithiothreitol-based aerosol oxidative potential with contrast as a function of aerosol solubility and fuel used for cooking purpose (modern vs traditional fuel) in rural indoor kitchens.

Methylamines can readily react with acidic gases in the atmosphere, which consequently has an important impact on the atmospheric environment. It is difficult to measure amines in field studies due to their high reactivity, and therefore, numerical modelling is an effective tool to study ambient amines. However, the contribution of marine biologica...

This study employs ISORROPIA-II for the evaluation of aerosol acidity and quantification of contributions from chemical species and meteorological parameters to acidity variation in the Indian context. PM2.5 samples collected during summer (April-July 2018), post-monsoon (September-November 2018), and winter (December 2018-January 2019) from a rura...

We hypothesize that firework events involving the combustion of charcoal fuel, organic binders, metal salts, and cellulose-based wrapping material could be significant transient sources of aerosol brown carbon (BrC). To test this, we couple high time-resolution (1 min) measurements of black carbon (BC) and BrC absorption from a 7-wavelength aethalo...

This work is a 7-year study of monsoonal rainwater chemistry (n = 302), over mid-Brahmaputra plain during 2012 to 2018. The samples were analyzed for major chemical parameters viz. pH, electrical conductivity (EC), and ions (SO42−, NO3−, Br−, Cl−, F−, Mg2+, Ca2+, K+, NH4+, Na+, and Li+) to assess the chemistry. The mean pH of rainwater varied among...

This poster talks about the fuel-wise variation in the size distribution of aerosol-bound trace metals, their exposure, region-wise respiratory deposition fraction, and consequently deposition fluxes for the rural northeastern Indian population.

This poster talks about the seasonal variation in carbonaceous and ionic species at a rural receptor location in the eastern Indo-Gangetic Plain and their role in driving aerosol acidity.

We report the first characterization of aerosol brown carbon (BrC) composition in the Indian context using excitation emission matrix (EEM) fluorescence spectroscopy coupled with parallel factor (PARAFAC) analysis. We find that biomass burning (BB)-dominated wintertime aerosols in the Indo-Gangetic Plain (IGP) outflow are characterized by two humic...

Single particle aerosol mass spectrometers (SPAMS) have created significant interest among atmospheric scientists by virtue of their ability to provide real-time size-resolved information on the chemical composition of aerosols. The objective of this study is to evaluate the newly developed single particle analysis technique in terms of chemical ch...

It is important to evaluate how ambient particles are deposited in the human respiratory system in view of the adverse effects they pose to human health. Traditional methods of investigating human exposure to ambient particles suffer from drawbacks related either to the lack of chemical information from particle number-based measurements or to the...

This study was carried out to determine sources and health risks of fine particulate (PM2.5) bound polycyclic aromatic hydrocarbons (PAHs) and carbonaceous species in the ambient atmosphere of Delhi. Aerosol samples were collected from October 2017 to September 2018 in an institutional cum residential area of Delhi. Annual PM2.5 level was found to...

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 PM2.5 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...

This study reports the characterization of optical properties of Arctic aerosol and surface snow collected at Ny-Ålesund, Svalbard during the polar summer. Methanol-soluble brown carbon (BrC) extracts showed higher absorption coefficients at 300 nm compared to water-soluble BrC and also exhibited a tail of absorption toward higher wavelengths due t...

This poster talks about the mass-size distribution of aerosol in different rural kitchen settings of scientifically-unexplored northeastern India and its implication for human health in terms of respiratory deposition.

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 colle...

We report here measurements of aerosol black carbon (BC) and aqueous and methanol-extractable brown carbon (BrCaq and BrCme) 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...

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...

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...

Southern China has experienced severe photochemical pollution events in recent years, and the tropospheric ozone has emerged as the major pollutant of concern. Despite some recent efforts, the role of natural factors in constraining long-term trends of ozone in this region is poorly understood. In this study, we addressed this issue using troposphe...

This brief introduction describes the organization and contents of our book. This volume is an effort to present, in one readable collection, the diversity of environmental issues. Researchers from different fields of subject like Political Science, Environmental Science, Economics, Geography, Pollination Biology, History, English, Earth Sciences a...

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)...

This study characterizes impacts of peat-forest (PF) smoke on an urban environment through carbonaceous profiles of >260 daily PM 2.5 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),...

Black and brown carbon, aerosols, CWTs

Aerosol pH is often calculated based on different standard states thus making it inappropriate to compare aerosol acidity parameters derived thereby. However, such comparisons are routinely performed in the atmospheric science community. This study attempts to address this issue by comparing PM2.5 aerosol pH based on different scales (molarity, mol...

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 PM2.5-associated ionic species and re...

Aerosol pH is often calculated based on different standard states thus making it inappropriate to compare aerosol acidity parameters derived thereby. Such comparisons are however routinely performed in the atmospheric science community. This study attempts to address this issue for the first time by providing a theoretical framework to compare and...

Fast-growing cities in the Global South have an important role to play in climate change mitigation. However, city governments typically focus on more pressing socio-economic needs, such as reducing urban poverty. To what extent can social, economic and climate objectives be aligned? Focusing on Kolkata in India, we consider the economic case for l...

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 Prote...

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 %)...

Size-fractionated aerosol samples collected at two sites in Delhi in 2003 were analyzed for carbonaceous species (elemental and organic carbon, EC and OC) and water-soluble ions. Light extinction coefficients (bext) and standard visual range (SVR) were calculated from chemical speciation data. The visual air quality of Delhi was found to be poor...

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 a...

The inhalable fraction of ambient particles (particulate matter with aerodynamic diameter less than 10 µm, denoted by PM10) collected at three residential sites in Delhi, India during December 2008–November 2009 were characterized with respect to 8 major and trace metals(Fe, Mn, Cd, Cu,Ni, Pb, Zn and Cr). Mean annual 24–h PM10 levels varied from 16...

Ambient respirable particles (PM10; aerodynamic diameter ≤10 μm) collected in a tropical urban environment (Delhi, India) during December 2008-November 2009 were characterized with respect to 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) and 8 major and trace metals (Fe, Mn, Cd, Cu, Ni, Pb, Zn and Cr). Concentrations of Σ16PAHs (annual...