St. George Campus - TIME AND LOCATION TBD

UTSC - EV140

UTSC Campus - TIME AND LOCATION TBD

St. George Campus

St. George Campus - LM158

UofT - St. George Campus - WB 407

St. George Campus

Location: Petrie Science & Engineering Building, room 317

Department of Chemistry, University of York
https://www.york.ac.uk/chemistry/staff/academic/d-g/edwardsp/

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
Associate PROFESSOR
CHEMICAL & ENVIRONMENTAL ENGINEERING
YALE UNIVERSITY

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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Departmental Colloqia

The macro-molecular and elemental composition of marine phytoplankton

Davenport East Seminar Room - St. George Campus

Departmental Colloquia

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.

https://sustainability.info.yorku.ca/sustainability-seminar-series/

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