Rebecca J Sheesley

• Ph.D, University of Wisconsin
• Professor (Full) at Baylor University

Black carbon (BC) contributes to Arctic climate warming, yet source attributions are inaccurate due to lacking observational constraints and uncertainties in emission inventories. Year-round, isotope-constrained observations reveal strong seasonal variations in BC sources with a consistent and synchronous pattern at all Arctic sites. These sources...

Marine aerosol plays a vital role in cloud‐aerosol interactions during summer in the Arctic. The recent rise in temperature and decrease in sea ice extent have the potential to impact marine biogenic sources. Compounds like methanesulfonic acid (MSA) and non‐sea‐salt sulfate (nss‐SO4²⁻), oxidation products of dimethyl sulfide (DMS) emitted by marin...

Understanding the drivers for high ozone (O3) and atmospheric particulate matter (PM) concentrations is a pressing issue in urban air quality, as this understanding informs decisions for control and mitigation of these key pollutants. The Houston, TX metropolitan area is an ideal location for studying the intersection between O3 and atmospheric sec...

Share link: https://authors.elsevier.com/a/1hWgo4pTZHnydm In June 2020, a record level of Saharan dust was transported across the Atlantic Ocean impacting air quality in the Caribbean Basin and the United States (US). Satellite images showed the transport, while a series of ground-based monitoring stations captured the surface impacts as the Sahara...

Rapid warming is likely increasing primary production and wildfire occurrence in the Arctic. Projected changes in carbonaceous aerosols during the summer will impact atmospheric chemistry and climate, but our understanding of these processes is limited by sparse observations. Here, we characterize carbonaceous aerosol in Alaska, USA: Toolik Field S...

We characterized optical properties (absorption, scattering, and backscattering coefficients, Ångström exponents, single scattering albedo) of aerosols during dust events at an urban site in El Paso, Texas using in-situ, real-time measurements. Simultaneous measurements of particulate matter (PM10, PM2.5) and wind data from an adjacent Texas Commis...

In June 2023, an elevated smoke layer from record-breaking Canadian wildfires was transported across the eastern half of the United States, impacting air quality for millions of people. Houston, TX experienced a notable biomass burning (BB) event associated with this wildfire smoke from Jun 4 to 9, 2023. The vertical transport of this smoke layer d...

As the Arctic rapidly warms, sea ice extent is decreasing and oil and gas extraction activities are expanding. Local combustion emissions affect the Arctic atmospheric aerosol chemical mixing state (the distribution of chemical species across the aerosol population), which impacts climate‐relevant properties. Bulk and single‐particle measurements o...

It has been widely reported that isoprene emissions from the Arctic ecosystem have a strong temperature response. Here we identify sedges (Carex spp. and Eriophorum spp.) as key contributors to this high sensitivity using plant chamber experiments. We observe that sedges exhibit a markedly stronger temperature response compared to that of other iso...

Highly reactive volatile organic compounds (HRVOCs) from mobile and petrochemical sources are important players in atmospheric photochemistry that contribute to the formation of ozone (O3). In a typical elevated O3 episode, we applied a high-resolution large eddy simulation (LES), coupled with the Weather Research and Forecasting model with chemist...

Plain Language Summary Isoprene plays an important role in atmospheric chemistry and climate. As the climate warms, ecosystems release more isoprene into the air due to higher temperatures and changes in plant species composition. The Arctic is a hotspot for climate change. In this study, we investigated how temperature affects isoprene emissions f...

As criteria pollutants from anthropogenic emissions have declined in the US in the last 2 decades, biomass burning (BB) emissions are becoming more important for urban air quality. Tracking the transported BB emissions and their impacts is challenging, especially in areas that are also burdened by anthropogenic sources like the Texas Gulf Coast. Du...

Pesticides registered with the U.S. EPA for mosquito control are called adulticides and are released directly into the atmosphere as aerosols to target flying mosquitos. This adulticide application approach is different from traditional (agricultural) pesticide applications, yet the fate and transport of adulticides in large metropolitan areas is l...

Changing urban emission landscapes and increasing population make it imperative to understand the driving forces for air quality in growing urban areas. Recent field studies in an industrial area in Houston and a semiurban area in San Antonio reveal unique emission signatures for these two growing Texas cities. A comparison of benzene, toluene, xyl...

As criteria pollutants from anthropogenic emissions have declined in the US in the last two decades, biomass burning (BB) emissions are becoming more important for urban air quality. Tracking the transported BB emissions and their impacts is challenging, especially in areas that are also burdened by anthropogenic sources like the Texas Gulf coast....

We measured submicron aerosols (PM1) at a beachfront site in Texas in Spring 2021 to characterize the "background" aerosol chemical composition advecting into Texas and the factors controlling this composition. Observations show that marine "background" aerosols from the Gulf of Mexico were highly processed and acidic; sulfate was the most abundant...

The population of Texas has increased rapidly in the past decade. The San Antonio Field Study (SAFS) was designed to investigate ozone (O3) production and precursors in this rapidly changing, sprawling metropolitan area. There are still many questions regarding the sources and chemistry of volatile organic compounds (VOCs) in urban areas like San A...

Significance Physical and chemical properties of individual atmospheric particles determine their climate impacts. Hygroscopic inorganic salt particles mixed with trace amounts of organic material are predicted to be liquid under typical tropospheric conditions in the summertime Arctic. Yet, we unexpectedly observed a significant concentration of s...

Aerosols play an important yet uncertain role in modulating the radiation balance of the sensitive Arctic atmosphere. Organic aerosol is one of the most abundant, yet least understood, fractions of the Arctic aerosol mass. Here we use data from eight observatories that represent the entire Arctic to reveal the annual cycles in anthropogenic and bio...

The Arctic is warming two to three times faster than the global average, and the role of aerosols is not well constrained. Aerosol number concentrations can be very low in remote environments, rendering local cloud radiative properties highly sensitive to available aerosol. The composition and sources of the climate-relevant aerosols, affecting Arc...

As the Arctic continues to change and warm rapidly, it is increasingly important to understand the organic carbon (OC) contribution to Arctic aerosol. Biogenic sources of primary and secondary OC in the Arctic will be impacted by climate change, including warming temperatures and earlier snow and ice melt. This study focuses on identifying potentia...

San Antonio, the second-most populous city in Texas and the seventh-most populous city in the United States (US), has been designated a marginal non-attainment area by the US Environmental Protection Agency with respect to the 2015 ozone (O3) National Ambient Air Quality Standard. While stationary air quality monitoring sites are operated in the re...

Hydroxymethanesulfonate (HMS) is produced in the aqueous-phase reaction of formaldehyde (HCHO) and sulfur dioxide (SO₂) and has been proposed as a significant contributor to midlatitude wintertime pollution events. Here we report HMS detection within submicrometer atmospheric aerosols during frequent late summer, regional fog events in an Arctic oi...

Environmental chambers are a commonly used tool for studying the production and processing of aerosols in the atmosphere. Most are located indoors and most are filled with air having prescribed concentrations of a small number of reactive gas species. Here we describe portable chambers that are used outdoors and filled with mostly ambient air. Each...

During the summer months, urban areas are literal hot spots of mosquito-borne disease transmission and air pollution. Public health authorities release aerosolized pesticides directly into the atmosphere to help control adult mosquito populations and thereby reduce the threat of diseases, such as Zika Virus. The primary adulticides (i.e. pesticides...

Environmental chambers are a commonly used tool for studying the production and processing of aerosols in the atmosphere. Most are located indoors and most are filled with air having prescribed concentrations of a small number of reactive gas species. Here we describe portable chambers that are used outdoors and filled with mostly ambient air. Each...

To investigate major sources and trends of particulate pollution in Houston, total suspended particulate (TSP) and fine particulate matter (PM2.5) samples were collected and analyzed. Characterization of organic (OC) and elemental (EC) carbon combined with realtime black carbon (BC) concentration provided insight into the temporal trends of PM2.5 a...

The rapid decrease in Arctic sea ice is motivating development and increasing oil and gas extraction activities. However, few observations of these local Arctic emissions exist, limiting the understanding of impacts on atmospheric composition and climate. To address this knowledge gap, the chemical composition of atmospheric aerosols was measured w...

Urban trees could represent important short- and long-term landscape sinks for elemental carbon (EC). Therefore, we quantified foliar EC accumulation by two widespread oak tree species––Quercus stellata (post oak) and Quercus virginiana (live oak)––as well as leaf litterfall EC flux to soil from April 2017 to March 2018 in the City of Denton, Texas...

Number concentrations of ice-nucleating particles (NINP) in the Arctic were derived from ground-based filter samples. Examined samples had been collected in Alert (Nunavut, northern Canadian archipelago on Ellesmere Island), Utqiaġvik, formerly known as Barrow (Alaska), Ny-Ålesund (Svalbard), and at the Villum Research Station (VRS; northern Greenl...

Number concentrations of ice nucleating particles (NINP) in the Arctic were derived from ground-based filter samples. Examined samples had been collected in Alert (Nunavut, Northern Canadian Archipelago on Ellesmere Island), Utqiagvik, formerly known as Barrow (Alaska), Ny Ålesund (Svalbard) and at the Villum Research Station (VRS, North Greenland)...

The air quality of the Texas Gulf Coast region historically has been influenced heavily by regional shipping emissions. However, the effects of the recently established North American Emissions Control Area on aerosol concentrations and properties in this region are presently unknown. In order to better understand the current sources and processing...

Ambient black carbon (BC) has detrimental effects on both human health and near-term global warming. To mitigate these negative effects, there have been significant efforts to reduce emissions of BC from anthropogenic and biomass burning sources in California's Bay Area since the 1960s. Recent reductions in BC have mainly been from fossil fuel comb...

The air quality of the Texas Gulf Coast region historically has been influenced heavily by regional shipping emissions. However, the effects of the recently established North American Emissions Control Area on aerosol concentrations and properties in this region are presently unknown. In order to better understand the current sources and processing...

Chemical mass balance (CMB) modeling and radiocarbon measurements were combined to evaluate the sources of carbonaceous fine particulate matter (PM2.5) in Shenzhen, China during and after the 2011 summer Universiade games when air pollution control measurements were implemented to achieve air quality targets. Ambient PM2.5 filter samples were colle...

Loss of sea ice is opening the Arctic to increasing development involving oil and gas extraction and shipping. Given the significant impacts of absorbing aerosol and secondary aerosol precursors emitted within the rapidly warming Arctic region, it is necessary to characterize local anthropogenic aerosol sources and compare to natural conditions. Fr...

Long-term data on organic aerosol concentration and optical properties is needed in the Arctic to improve characterization of radiative forcing by atmospheric aerosols. This study presents the seasonal trends (summer 2012- summer 2013) of organic carbon (OC) and water-soluble organic carbon (WSOC) along with optical properties of light-absorbing OC...

The present study investigates primary and secondary sources of organic carbon for Bakersfield, CA, USA as part of the 2010 CalNex study. The method used here involves integrated sampling that is designed to allow for detailed and specific chemical analysis of particulate matter (PM) in the Bakersfield airshed. To achieve this objective, filter sam...

The Indo-Gangetic Plain (IGP) in northern India, Pakistan and Bangladesh is a major source of carbonaceous aerosols in South Asia. However, poorly constrained seasonality of their sources over the IGP leads to large uncertainty in climate and health effects. Here, we present a first dataset for year-round radiocarbon (Δ14C) and stable carbon (δ13C)...

Atmospheric particulate matter (PM) samples were collected from four ground-based sites located in the Houston, TX (Sept 21-28, 2013) and were analyzed for 12 organophosphate esters (OPEs; current-use plasticizers and flame retardants). Samples analyzed included daytime, nighttime, and 24 hour PM2.5 (PM <2.5 µm aerodynamic diameter) and total suspe...

Long-term measurements of the light absorption coefficient (babs) obtained with a particle soot absorption photometer (PSAP), babs (PSAP), have been previously reported for Barrow, Alaska, and Ny-Ålesund, Spitsbergen, in the Arctic. However, the effects on babs of other aerosol chemical species co-existing with black carbon (BC) have not been criti...

The atmospheric concentrations of seven current-use pesticides in particulate matter were determined at four locations throughout the Houston metropolitan area in TSP and PM2.5 samples from September 2013. Atmospheric concentrations in both TSP and PM2.5 ranged from below method detection limits (MDLs) to nearly 1100 pg m(-3). The three compounds m...

Particulate matter was measured in Conroe, Texas (~60 km north of downtown Houston, Texas) during the September 2013 DISCOVER-AQ campaign to determine the sources of particulate matter in the region. The measurement site is influenced by high biogenic emission rates as well as transport of anthropogenic pollutants from the Houston metropolitan area...

Large-scale emissions of carbonaceous aerosols (CA) from South Asia impact both regional climate and air quality, yet their sources are not well constrained. Here, we use source-diagnostic stable and radiocarbon isotopes (δ13C and Δ14C) to characterize CA sources to a semi-urban site (Hisar: 29.2°N, 75.2°E) in the NW Indo-Gangetic Plain (IGP), and...

A novel thermal desorption gas chromatography mass spectrometry (TD-GCMS) technique was developed for the analysis of levoglucosan and other polar compounds in atmospheric organic aerosol. The method employs an in situ derivatization to add tri-methylsilyl groups to alcohol functional groups on simple carbohydrates, like levoglucosan and sterols. T...

To quantify the contributions of fossil and biomass sources to the wintertime Arctic, radiocarbon source apportionment is reported for elemental (EC) and organic carbon (OC) fractions of six PM10 samples collected during a wintertime (2012-2013) campaign in Barrow, AK. Radiocarbon apportionment of EC indicates that fossil sources contribute an aver...

Black carbon (BC) aerosols impact climate and air quality. Since BC from fossil versus biomass combustion have different optical properties and different abilities to penetrate the lungs, it is important to better understand their relative contributions in strongly affected regions such as South Asia. This study reports the first year-round 14C-bas...

Sample preparation represents about two-thirds of the cost of analysis and often presents logistical bottlenecks in analytical and environmental chemistry laboratories, so reducing our capacity and preparedness to quantify organic pollutants rapidly and accurately. Selective pressurized liquid extraction (SPLE) is an analytical technique that build...

The 2010 CalNex (California Nexus) field experiment offered an opportunity for detailed characterization of atmospheric particulate carbon composition and sources in Bakersfield, CA. In the current study, the authors describe and employ a new protocol for reporting unresolved complex mixture (UCM) in over 30 daily samples. The Bakersfield, CA site...

Black carbon (BC) aerosols formed by incomplete combustion of fossil fuels, biofuel and biomass exert a large warming impact on regional climate and may severely impact respiratory health. Short-term campaign observations using natural abundance 14C of BC indicate that biomass combustion may rival the contributions from fossil fuel combustion. This...

Rural and background sites provide valuable information on the concentration and optical properties of organic, elemental, and water-soluble organic carbon (OC, EC, and WSOC), which are relevant for understanding the climate forcing potential of regional atmospheric aerosols. To quantify climate- and air quality-relevant characteristics of carbonac...

Traditional monitoring networks measure only total elemental carbon (EC) and organic carbon (OC) routinely. Diagnosing model biases with such limited information is difficult. Measurements of organic tracer compounds have recently become available and allow for more detailed diagnostic evaluation of CMAQ modeling results, which allow for more expli...

Ambient measurements of 78 source specific tracers of primary and secondary carbonaceous fine particulate matter collected at four Midwestern United States locations over a full year (March 2004 - February 2005) provided an unprecedented opportunity to diagnostically evaluate the results of a numerical air quality model. Previous analyses of these...

Water-soluble organic carbon (WSOC) is typically a large component of carbonaceous aerosols with a high propensity for inducing cloud formation. The sources of WSOC, which may be both of primary and secondary origins, are in general poorly constrained. This study assesses the concentrations and dual-carbon isotope (14C and 13C) signatures of South...

Secondary organic aerosols (SOA), known to form in the atmosphere from oxidation of volatile organic compounds (VOCs) emitted by anthropogenic and biogenic sources, are a poorly understood but substantial component of atmospheric particles. In this study, we examined the chemical and physical properties of SOA at Bakersfield, California, a site inf...

Atmospheric Brown Clouds (ABC), regional-scale haze events, are a significant concern for both human cardiopulmonary health and regional climate impacts. In order to effectively mitigate this pollution-based phenomenon, it is imperative to understand the magnitude, scope and source of ABC in regions such as South Asia. Two sites in S. Asia were cho...

It is of high interest to determine the impact of large urban centers on regional aerosol. However, it is difficult to ascertain impact using only chemical or meteorological data. A combination of techniques would enable more accurate assessment of the frequency, magnitude and character of the urban outflow at a background site. The study site is c...

The air quality and regional climate in South and East Asia are considerably affected by atmospheric aerosols produced by anthropogenic activities. Recent studies have investigated the sources of the black carbon aerosol component in these regions. This study seeks to make progress in apportioning the sources of the water soluble organic carbon (WS...

The quantification of source contributions is of key importance for proposing environmental mitigation strategies for particulate organic matter. Organic molecular tracer analysis of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes was conducted on a set of winter samples from two regional receptor sites in South Asia: the Island of Hanimaadho...

Through absorption of sun light atmospheric black carbon (BC) is expected to influence regional/global climate by warming the atmosphere and dimming the surface. To evaluate the impact of these effects it is of interest to examine both the radiative properties of BC and the concentrations in air. Building on recent developments we present a novel a...

Combustion-derived soot or black carbon (BC) in the atmosphere has a strong influence on both climate and human health. In order to propose effective mitigation strategies for BC emissions it is of importance to investigate geographical distributions and seasonal variations of BC emission sources. Here, a radiocarbon methodology is used to distingu...

Considerable uncertainty still exists regarding the contribution of resuspended soil and road dust to PM2.5 organic carbon (OC) in US urban areas. Contributing factors are the limited knowledge of the OC content of resuspended soils and road dusts, and the variability of the ratio of OC to traditional soil markers such as silicon and aluminum. This...

High wintertime concentrations of black carbon aerosols (BCA) over South Asia and the Northern Indian Ocean are thought to have a large impact on the regional climate. Direct absorption of sunlight by BCAs causes heating of the atmosphere and cooling at the surface. To quantify such effects it is important to characterize a number of different prop...

Black carbon is a short-lived climate forcing agent, which makes studies of climate impacts and emission source contribution highly relevant on a regional scale. Urban areas are known to have high concentrations of black carbon and other combustion-derived pollutants, but BC is readily transported on a regional level. Therefore it is important to m...

Organic aerosol measurements with high temporal resolution can differentiate primary organic carbon (POC) from secondary organic carbon (SOC) and can be used to distinguish morning rush hour traffic emissions and subsequent photo-oxidation. In the current study, five hour filter samples were collected during the Summer Study for Organic Aerosols at...

New chemical analysis methods for the characterization of atmospheric particulate matter (PM)* samples were developed and demonstrated in order to expand the number of such methods for use in future health studies involving PM. Three sets of methods were, developed, for the analysis (1) of organic tracer compounds in low-volume personal exposure sa...

Water-soluble organic carbon (WSOC) constitutes a large fraction of climate-forcing organic aerosols in the atmosphere, yet the sources of WSOC are poorly constrained. A method was developed to measure the stable carbon isotope (δ(13)C) and radiocarbon (Δ(14)C) composition of WSOC for apportionment between fossil fuel and different biogenic sources...

South Asia is one region of vital importance for assessing human impact on radiative forcing by atmospheric aerosols. Previous research in the region has indicated that black carbon is a significant component of the regional aerosol load. In contrast, there is more ambiguous information regarding the contribution of secondary organic aerosols (SOA)...

High wintertime concentrations of black carbon aerosols (BCA) over South Asia and the northern Indian Ocean are thought to have a large impact on the regional climate. Direct absorption of sunlight by BCAs causes heating of the atmosphere and cooling at the surface. To quantify such effects it is important to characterize a number of different prop...

High wintertime concentrations of black carbon aerosols (BCA) over South Asia and the northern Indian Ocean are thought to have a large impact on the regional climate. Direct absorption of sunlight by BCAs causes heating of the atmosphere and cooling at the surface. To quantify such effects it is important to characterize a number of different prop...

South Asia is one region of vital importance for assessing human impact on radiative forcing by atmospheric aerosols. Previous research in the region has indicated that black carbon is a significant component of the regional aerosol load. In contrast, there is more ambiguous information regarding the contribution of secondary organic aerosols (SOA)...

Light-absorbing carbonaceous matter constitutes one of the largest uncertainties in climate modeling. The high concentrations of black carbon - soot - in South Asian Atmospheric Brown Clouds lead to strong atmospheric heating and large surface cooling that is as important to regional climate forcing as greenhouse gases, yet the sources of these aer...

Industrial sources can have a significant but poorly defined impact on ambient particulate matter concentrations in select areas. Detailed emission profiles are often not available and are hard to develop because of the diversity of emissions across time and space at large industrial complexes. A yearlong study was conducted in an industrial area i...

Monthly average ambient concentrations of more than eighty particle-phase organic compounds, as well as total organic carbon (OC) and elemental carbon (EC), were measured from March 2004 through February 2005 in five cities in the Midwestern United States. A multi-variant source apportionment receptor model, positive matrix factorization (PMF), was...

To investigate the impact of the number of observations on molecular marker-based positive matrix factorization (MM-PMF) source apportionment models, daily PM2.5 samples were collected in East St. Louis, IL, from April 2002 through May 2003. The samples were analyzed for daily 24-h average concentrations of elemental and organic carbon, trace eleme...

Personal exposures to fine particulate matter air pollution (PM(2.5)), and to its traffic-related fraction, were investigated in a group of urban children with asthma. The relationships of personal and outdoor school-site measurements of PM(2.5) and elemental carbon (EC) were characterized for a total of 40 fifth-grade children. These students, fro...

The high-molecular weight water-soluble organic compounds present in atmospheric aerosols underwent functional-group characterization using liquid chromatography tandem mass spectrometry (LC-MS/MS), with a focus on understanding the chemical structure and origins of humic-like substances (HULIS) in the atmosphere. Aerosol samples were obtained from...

Natural abundance radiocarbon analysis facilitates distinct source apportionment between contemporary biomass/biofuel (14C "alive") versus fossil fuel (14C "dead") combustion. Here, the first compound-specific radiocarbon analysis (CSRA) of atmospheric polycyclic aromatic hydrocarbons (PAHs) was demonstrated for a set of samples collected in Lyckse...

South Asia has a large impact from combustion aerosols which can have serious ramifications for climate forcing in the region. Source apportionment is a valuable tool for estimating contributions to atmospheric particulate matter. By combining d13C and D14C isotope analysis of total organic carbon (TOC), elemental carbon (EC) and soot carbon (SC) w...

Recent development in compound-specific radiocarbon analysis (CSRA) now allows application of this analytical dimension toward source apportionment of natural and anthropogenic compounds in the atmosphere. CSRA studies of semi-volatile n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in air collected at various locations throughout Europe comb...

Carbonaceous aerosols cause strong atmospheric heating and large surface cooling that is as important to South Asian climate forcing as greenhouse gases, yet the aerosol sources are poorly understood. Emission inventory models suggest that biofuel burning accounts for 50 to 90% of emissions, whereas the elemental composition of ambient aerosols poi...

Natural abundance radiocarbon analysis facilitates distinct source apportionment between contemporary biomass/biofuel (14C "alive") versus fossil fuel (14C "dead") combustion. Here, the first compound-specific radiocarbon analysis (CSRA) of atmospheric polycylic aromatic hydrocarbons (PAHs) was demonstrated for a set of samples collected in Lycksel...

High black carbon (BC) concentrations have been reported for South Asia, but there is still significant debate concerning the origin of this BC and sampling campaigns have often focused on off-shore measurements in the Indian Ocean. BC comprises a major fraction of light absorbing carbon (LAC) in the atmosphere. Source apportionment of South Asian...

Ambient PM2.5 samples were collected in five midwestern United States cities throughout 2004: East St. Louis, Illinois; Detroit Michigan; Cincinnati, Ohio; Bondville, Illinois; and Northbrook, Illinois. Monthly composites were analyzed using chemical derivatization coupled with GC-MS analysis to estimate the contributions of several sources to the...

A large study has been undertaken to assess the exposure to diesel exhaust within diesel trucking terminals. A critical component of this assessment is an analysis of the variation in carbonaceous particulate matter (PM) across trucking terminal locations; consistency in the primary sources can be effectively tracked by analyzing trends in elementa...

Personal exposure to particle-phase molecular markers was measured at a trucking terminal in St Louis, MO, as part of a larger epidemiologic project aimed at assessing carbonaceous fine particulate matter (PM) exposure in this occupational setting. The integration of parallel personal exposure, ambient worksite area and ambient urban background (St...

Organic carbon (OC) comprises a large fraction of fine particulate matter (PM2.5) in Mexico City. Daily and select 12-h PM2.5 samples were collected in urban and peripheral sites in Mexico City from 17–30 March 2006. Samples were analyzed for OC and elemental carbon (EC) using thermal-optical filter-based methods. Real-time water-soluble organic ca...

To assess the contribution of sources to fine particulate organic carbon (OC) at four sites in North Carolina, USA, a molecular marker chemical mass balance model (MM-CMB) was used to quantify seasonal contributions for 2 years. The biomass burning contribution at these sites was found to be 30–50% of the annual OC concentration. In order to provid...