St. George Campus - LM158
UTSC Campus - TIME AND LOCATION TBD
St. George Campus - TIME AND LOCATION TBD
Location: Petrie Science & Engineering Building, room 317
Department of Chemistry, University of York
A talk of two parts: NOx control of nocturnal biogenic VOC oxidation in the South East US and recent advances in the use of low cost sensors for atmospheric science
The influence of nitrogen oxides (NOx) on daytime atmospheric oxidation cycles is well known, with clearly defined high- and low-NOx regimes. Night-time oxidation of volatile organic compounds also influences secondary pollutants but lacks a similar clear definition of high- and low-NOx regimes, even though such regimes exist. Decreases in anthropogenic NOx emissions in the US and Europe coincided with increases in Asia over the last 10 to 20 years, and have altered both daytime and nocturnal oxidation cycles. I will present measurements from day- and night-time research flights over the southeast US in 1999 and 2013, supplemented by atmospheric chemistry simulations, to investigate the NOx control of nocturnal BVOC oxidation.
The second part of my talk will focus on recent work to enable the use of low cost sensors for atmospheric chemistry research. Over recent years the use of low cost sensors for atmospheric measurements has exploded. Significant issues with these devices, however, have so far limited their use for atmospheric chemistry research. This short section of the talk will show approaches we have taken to address these issues in order to enable the use of these potentially exciting new tools.
Cool cloud chemistry: From photochemistry of organic aerosols to atmospheric ice nucleation
Wednesday, July 24, 2019
3:00 – 4:00 PM
200 College Street, WB 407
New perspectives on sources of reactive gas-phase organic compounds & the chemical complexity of secondary organic aerosol
DREW R. GENTNER
CHEMICAL & ENVIRONMENTAL ENGINEERING
Abstract: Gas-phase organic compounds (including volatile organic compounds; VOCs) are key precursors to secondary organic aerosol (SOA) and tropospheric ozone. Through several bottom-up approaches, we evaluate the evolving role of non-combustion-related emissions in urban air quality, and demonstrate that non-combustion-related sources now contribute a major, but poorly-characterized fraction of SOA and ozone precursors from anthropogenic sources. We present an expanded framework for classifying volatile, intermediate, and semi-volatile emissions from this diverse array of sources that emphasizes a life cycle approach over longer timescales and multiple separate emission pathways. We also perform an extensive untargeted molecular-level intercomparison of SOA from three diverse field sites and an environmental chamber. Despite similar bulk composition, we report large molecular-level variability between multi-hour organic aerosol samples at each site, with 66% of compounds differing between consecutive samples. Through observations and model results, we evaluate the roles of emissions, chemical age, and oxidation conditions in driving this variability, and its potential implications.
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The macro-molecular and elemental composition of marine phytoplankton
Davenport East Seminar Room - St. George Campus
A Million Year History of Atmospheric Methane: Implications for Future Changes
Measuring Atmospheric Pollutant Emissions, Mixing, and Deposition in the Athabasca Oil Sands Region
The extraction and processing of oil sands in the Athabasca region of northern Alberta releases more than 45 kt (Kilotonnes) of SO2 and 95 kt of particulate matter into the atmosphere every year. The region is fertile ground for the study of: atmospheric pollutant emission measurement techniques; pollutant mixing processes; and source determination methods. This talk will overview a number of studies in this region related to the emissions of atmospheric pollutants, mixing of pollutants into the surrounding environment, and deposition of pollutants into the boreal forest. The Top-Down Emission Rate Retrieval Algorithm (TERRA) calculates emissions from the production facilities using aircraft-based measurements. Model simulations improve TERRA and optimize flight patterns for future campaigns. Aircraft measurements assess model predictions of smoke-stack plume-rise, demonstrating a significant model underestimation of plume rise height. Image analysis algorithms automatically determine plume-rise height from continuous video recordings of facility smoke stacks. The York Athabasca Jack Pine (YAJP) 33m-tall instrumented tower is situated in a forested region surrounded by oil sands facilities. The YAJP tower measures energy balance and CO2 and moisture fluxes throughout the year (and will soon be outfitted with instrumentation to measure ozone). Two intensive summer field studies at the YAJP measured aerosol mixing and deposition, and ozone and SO2 profiles in the lower atmosphere. All of these topics will be discussed in the context of improving the methods that are used to quantify sustainability.
What’s In My Drinking Water? Revealing the Chemicals We Can’t See
Drinking water disinfection by-products (DBPs) are an unintended consequence of using chemical disinfectants to kill harmful pathogens in water. DBPs are formed by the reaction of disinfectants with naturally occurring organic matter, bromide, and iodide, as well as from anthropogenic pollutants, such as pharmaceuticals and pesticides. Potential health risks of DBPs from drinking water include bladder cancer, early-term miscarriage, and birth defects. Several DBPs, such as trihalomethanes (THMs), haloacetic acids (HAAs), bromate, and chlorite, are regulated in the U.S. and in other countries, but other “emerging” DBPs, such as iodo-acids, halobenzoquinones, halonitromethanes, haloamides, halofuranones, and nitrosamines are not widely regulated. This presentation will provide a state-of-the-science overview of the formation of DBPs and how we use gas chromatography (GC) and liquid chromatography (LC) with high resolution-mass spectrometry to comprehensively identify unknown DBPs. In addition, recent work will be presented on the impacts of hydraulic fracturing on DBP formation, as well as new research using granular activated carbon (GAC) to try to remove DBP precursors and make drinking water safer.
Linking Global Contaminant Releases to Health in an Era of Environmental Change
Data-constrained annual carbon fluxes and boreal ecosystems:combining airborne, tower and remote sensing measurements
Chlorophyll Fluorescence and Photosynthesis at the Landscape Scale
Davenport East Seminar Room - St. George Campus
The Problem with Persistence: PFAS as Extreme Emerging Water Contaminant
Per and polyfluorinated alkyl substances (PFAS) comprise a large group of industrial chemicals that have become pervasive environmental contaminants. Among them, long-chain perfluorinated alkyl acids are now recognized as extremely persistent, bioavailable, and bioaccumulative substances. Growing concern regarding their toxicological effects has led to (largely voluntary) phaseouts in the US and Europe. Short-chain acids were suggested as immediate drop-in replacements because they do not bioaccumulate and are therefore considered less toxic. Yet emerging data on the potential toxicity of even very low levels of certain PFAS is driving regional “action levels” in drinking water in the part per trillion range.
At the same time, a wide variety of “alternative PFAS” have increased production to fill market demand. Thousands of different PFAS, with a variety of chain lengths, degrees of fluorination, and functional groups are now used in industries ranging from fire fighting to industrial processing to personal care products to food packaging. Very little is known about the bioaccumulation potential and toxic effects of these replacement compounds.
In this seminar, we will explore why current risk assessment paradigms and water treatment approaches fail to adequately capture or mitigate the risks posed by PFAS and discuss strategies for addressing this pressing global contamination problem.
Dr. Carla Ng is an Assistant Professor in Civil and Environmental Engineering at the University of Pittsburgh, with a secondary appointment in Chemical & Petroleum Engineering. She received her PhD in Chemical & Biological Engineering from Northwestern University in 2008. The research in Dr. Ng’s group focuses on the development of models for the fate of chemicals in organisms and ecosystems, at the intersection of chemistry, biology and engineering. Active research areas include the development of mechanistic models for the bioaccumulation of emerging contaminants in organisms, tracking the fate of legacy and current-use pesticides in tropical environments, and exploring the role of the industrial food system on the fate of environmental contaminants, with implications for human exposure.
Atmospheric impact of the surface chemistry of nitrogen and halogen species over soil, ocean, and snow
Chemical reactions on various ground surfaces, including soil, snow, and ocean are increasingly recognized to play an important role in the chemistry of the atmospheric boundary layer. However, our understanding of this surface chemistry and the transport to/from the ground is still incomplete. This is, in part, because the observation of species undergoing chemistry at the surface requires analytical methods that overcome sampling artifacts and allow the determination of vertical fluxes. In addition, most atmospheric chemistry models were not designed to include chemical reactions and bidirectional fluxes at the ground.
Here the significance of chemistry at the ground (soil), snow, and ocean surface will be illustrated for three different chemical systems and environments: Nitrogen chemistry in polluted urban areas impacts radical levels and thus ozone and aerosol formation. Iodine chemistry over the tropical ocean lowers background ozone concentrations in the marine boundary layer and in coastal cities. Bromine chemistry over snow is known to deplete ozone and mercury during spring. Observations with long-path Differential Optical Absorption Spectroscopy instruments, combined with high-resolution one-dimensional atmospheric chemistry and transport models elucidate the chemistry and transport processes in these environments. These results allow identification of common characteristics, uncertainties, and a better quantitative descriptions of the influence of the surface on the composition of the overlaying atmosphere.
Atmospheric Chemistry and Anthropogenic Influence over the
Amazon Tropical forest: The Green Ocean Amazon
The Observations and Modeling of the Green Ocean Amazon 2014–2015 (GoAmazon2014/5) experiment took place around the urban region of Manaus in central Amazonia across 2 years. The urban pollution plume was used to study the susceptibility of gases, aerosols, clouds, and rainfall to human activities in a tropical environment. Many aspects of air quality, weather, terrestrial ecosystems, and climate work differently in the tropics than in the more thoroughly studied temperate regions of Earth. GoAmazon2014/5, a cooperative project of Brazil, Germany, and the United States, employed an unparalleled suite of measurements at nine ground sites and on board two aircraft to investigate the flow of background air into Manaus, the emissions into the air over the city, and the advection of the pollution downwind of the city. Herein, to visualize this train of processes and its effects, observations aboard a low-flying aircraft are presented. Comparative measurements within and adjacent to the plume followed the emissions of biogenic volatile organic carbon compounds (BVOCs) from the tropical forest, their transformations by the atmospheric oxidant cycle, alterations of this cycle by the influence of the pollutants, transformations of the chemical products into aerosol particles, the relationship of these particles to cloud condensation nuclei (CCN) activity, and the differences in cloud properties and rainfall for background compared to polluted conditions. The observations of the GoAmazon2014/5 experiment illustrate how the hydrologic cycle, radiation balance, and carbon recycling may be affected by present-day as well as future economic development and pollution over the Amazonian tropical forest.