This RAPID award is for the timely deployment of University of New Hampshire (UNH) personnel and equipment as part of a joint NOAA-University field campaign (Nitrogen, Aerosol Composition and Halogens on a Tall Tower - NACHTT) to take place during the winter/spring transition of 2011, at a rural site in Colorado (Boulder Atmospheric Observatory, Erie, CO).
The NACHTT campaign has as its goals the further investigation of the activation of photolabile halogens species, such as may generate chlorine radicals, by surface reactions on nitrogen oxide aerosol particles. Speciated volatile organic compound (VOC) analyses proposed by UNH researchers serves two distinct purposes, namely: i) providing an independent check on the extent of halogen oxidation occurring at the NACHTT study site, along with potential diagnostic information of the type and source of air masses found at the site
ii) taking advantage of an extensive suite of key nitrogen, aerosol and halogen species measured during NACHTT for tracing the winter/spring reactivity of monoterpene hydrocarbons, a class of naturally produced biogenic hydrocarbons whose gas-phase oxidation may lead to secondary products such as aromatic hydrocarbons and organic aerosol species , typically attributed to man-made pollution sources.
The first of these objectives contributes to the broader NACHTT measurement campaign. The second will lead to a further understanding of both the seasonality of biogenic VOC emissions at a rural, mind-continental site, along with their potential subsequent oxidation .
UNH graduate students will be involved in the field sampling, measurement, data reduction and synthesis aspects of the study. The outcome of the measurements will be explained to and made available to the public and other investigators through the UNH AIRMAP website.
The premise of this work was to investigate the role of biogenic volatile organic compound (BVOC) emissions, how their chemical transformation in the atmosphere influences its composition, how BVOC chemical transformation pathways occurring in the atmosphere influence the gas and condensed phase products, and what processes they facilitate. The Boulder Atmospheric Observatory (BAO) tower in Erie, CO during the Nitrogen, Aerosol Composition and Halogens on a Tall Tower (NACHTT) campaign was an ideal location to conduct this research because of i) the diverse potential gas phase precursor sources and ii) the comprehensive suite of measurements which were conducted concurrently. However, because of the incredibly high levels of VOCs encountered as a result of the large number of active gas wells in Colorado, the relatively clean atmospheric conditions anticipated were actually more representative of a highly polluted urban center. Thus, while it appears as though we have observed the in situ transformation of α-pinene to p-cymene, the overall impact of this photochemical processing is, in fact, negligible compared to the persistent background levels of aromatic hydrocarbons in this region. The light alkane mixing ratios at BAO were significantly higher than typically observed in rural/continental regions and are comparable to levels observed in urban areas (i.e., Houston, TX, Mexico) known to be influenced by petrochemical industry emissions. This work is currently working on addressing significant information gaps and will ultimately deliver sound science leading to an improved understanding of the seasonality in BVOC emissions and their influences on SOA formation, heterogeneous chemistry and its associated influences on aromatic hydrocarbon distributions, and oxidant cycling. Such information is essential for improving and developing reliable predictive capabilities for air quality, climate change, and the overall composition of the troposphere. Finally, this work provided two graduate students and with a unique opportunity to use state-of-the-art equipment and techniques to foster their ability to assess and manage highly complex systems which cross the boundaries of many scientific disciplines. The two graduate students, along with two research scientists, were directly involved with all facets of the field measurements, sample analysis, data reduction and analysis. They are all currently involved in manuscript preparation and presented results at the 2011 Fall American Geophysical Union Meeting. Our data are publicly available at the following site: http://esrl.noaa.gov/csd/groups/csd7/measurements/2011NACHTT/. Finally, this work was recently highlighted in the July 2012 journal International Innovation, which is an open access journal geared towards disseminating important scientific issues to the general public. This issue can be found at the following site: www.research-europe.com/magazine/REGIONAL/NORTH_AMERICA_JUNE12/index.html.
