Grantee Research Project Results
1999 Progress Report: Measurements of Non-Methane Volatile Organic Compounds in the Lower Troposphere From Tethered Balloon and Kite Sampling Platforms by Internal Standard Calibration Using Ambient CFC Reference Compounds
EPA Grant Number: R825417Title: Measurements of Non-Methane Volatile Organic Compounds in the Lower Troposphere From Tethered Balloon and Kite Sampling Platforms by Internal Standard Calibration Using Ambient CFC Reference Compounds
Investigators: Helmig, Detlev , Karbiwnyk, Christine , Balsley, Ben , Mills, Craig , Birks, John
Current Investigators: Helmig, Detlev , Birks, John , Balsley, Ben , Karbiwnyk, Christine , Mills, Craig
Institution: University of Colorado at Boulder
EPA Project Officer: Chung, Serena
Project Period: October 1, 1996 through September 30, 1999
Project Period Covered by this Report: October 1, 1998 through September 30, 1999
Project Amount: $436,172
RFA: Analytical and Monitoring Methods (1996) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Environmental Statistics , Air Quality and Air Toxics , Water , Air , Land and Waste Management
Objective:
The main goal of this project is to develop an analytical method for the analysis of atmospheric volatile organic compounds (VOCs) using atmospheric chlorofluorocarbons (CFCs) as internal standard compounds. This technique will allow the development of low-cost, light-weight, and battery powered sampling packages to analyze VOCs in atmospheric samples from airborne sampling platforms such as tethered balloons and light aircraft. Along the way to achieving these goals, solid adsorbent sampling methods are investigated for their reproducibility in the analysis of selected CFCs and VOCs.Progress Summary:
Our humidity generator was used to measure the effects of sampling humid air. Water weight gain on the tubes was measured at different humidity levels. Water interference on detector response and peak shape at different humidity levels also was monitored. More experiments regarding water management methods for drying humid samples will be explored.The 8-port balloon sampler is being modified in an effort to make the package smaller and more rugged. The electronics board is reconfigured to fit inside the tube that holds the manifolds in place (along with the batteries). This will result in the electronics being more stable and protected. In addition, the sampler will be more compact. Improvements were implemented to the laboratory-based sampling system to improve accuracy and minimize losses. Stainless steel tubing was replaced with silco steel (Restek) to reduce compound losses to the walls. The sampling program for the 10-port sampler also was improved to allow more flexibility in sampling times.
Another student joined the project in September. Craig Mills from the University of Wales, Swansea, is fulfilling his research internship as part of his Undergraduate/Masters degree. His main contribution has been collecting profile samples from a small plane. He also has worked on improving the tube cleaning method, reducing background, detector calibrations, sample analysis, and the CFC internal standard calibrations.
We have taken several flights out of the Boulder, CO, airport to collect vertical profile samples (Figure 1). In addition to collecting samples on our 10-port sampler, temperature, pressure, relative humidity, and ozone are monitored to pinpoint the convective boundary layer.
Figure 1. Vertical profiles (in ppb compound) measured out of Boulder, CO (altitude 1.613 km) on tests flights in November 1999 and March 2000. While the VOCs show a significant concentration decrease with altitude, the CFCs show comparatively little variation. The VOCs also show a significant decrease in concentration during the March flight (a good air quality day) compared to November (a bad air quality day). Again, the CFCs do not show significant variation between the two sampling periods.
Steven Montzka (Climate Monitoring and Diagnostic Laboratory, National Oceanic and Atmospheric Administration) calibrated the CFCs present in our Niwot Ridge, CO, ambient air standard. This allowed us to begin calibrating the response factors for our internal standard method. Preliminary tests of our CFC internal standard calibration method look good. The correlation between our measured volumes and the volumes determined from the F-12 peak is shown in Figure 2.
Figure 2. The measured volumes of the Nov. 16, 1999 flight samples were used to determine the mixing ratios of sampled VOCs. The F-12 peak area in each sample was also used to determine the sampling volume. The correlation between these two methods of VOC quantitation is 1.4% from unity. Volumes acquired from the F-12 peak areas correspond well with measured volumes.
Future Activities:
Work to reduce measurement interference due to water vapor and gas phase contaminants of blank tubes is continuing. Vertical profile measurements from a small plane platform will continue so that a database can be developed. The data will allow us to monitor the precision of VOC quantitation using the CFC reference compounds compared to measured sampling volumes. We are preparing for several field missions in which vertical profiles will be collected from a tethered balloon platform. Two different light sampling packages (an 8-port sampler and individual sampling pump packages) were developed to sample from this platform. We expect to collaborate with several research groups during these missions.Journal Articles:
No journal articles submitted with this report: View all 8 publications for this projectSupplemental Keywords:
air, atmospheric chemistry, chemical transport, regional models, model evaluation., RFA, Ecosystem Protection/Environmental Exposure & Risk, Scientific Discipline, Air, Engineering, Chemistry, Ecology, Environmental Chemistry, tropospheric ozone, Monitoring/Modeling, biogenic emissions, gas chromatography, cfc, spectroscopic, remotely piloted vehicles, ambient particle properties, troposphere, aerosol analyzers, flame ionization, VOCs, kite sampling, Volatile Organic Compounds (VOCs), tethered bolloon monitoringProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.