Grantee Research Project Results
1997 Progress Report: Development of Lightweight Instrumentation for Measurement of Long-Lived Trace Gases
EPA Grant Number: R825222Title: Development of Lightweight Instrumentation for Measurement of Long-Lived Trace Gases
Investigators: Avallone, Linnea M.
Institution: University of Colorado at Boulder
EPA Project Officer: Hahn, Intaek
Project Period: December 1, 1996 through November 30, 2001
Project Period Covered by this Report: December 1, 1996 through November 30, 1997
Project Amount: $466,074
RFA: Exploratory Research - Early Career Awards (1996) RFA Text | Recipients Lists
Research Category: Early Career Awards
Objective:
The primary goal of the research supported under this grant is the development, testing, and deployment of a prototype, lightweight gas chromatograph system, based on micro-GC technology. As originally conceived, this GC system would be integrated into a suite of sensors (the rest of which are funded through a grant from the NASA Atmospheric Effects of Aviation Program) to be flown on a commercial airliner. The aim of this larger project is to obtain extensive measurements of several key trace species (O3, CO2, H2O, and C2Cl4) in the upper troposphere (8-12 km altitude). This dataset can be used for a variety of purposes, including testing of global three-dimensional chemical transport models and models of ozone precursor emissions and ambient air quality, and the assessment of the effects of subsonic aviation on upper tropospheric and lower stratospheric ozone distributions.Progress Summary:
During the development and testing phase of this project, we have chosen to focus our efforts on a measurement of tetrachloroethene (C2Cl4) in the upper troposphere, as this species is of greatest interest to the anticipated community of users of the aircraft dataset. To that end, we have carried out tests of the chromatography and sampling system to verify that we can indeed measure C2Cl4 quantitatively and with relatively rapid time response. Much of this work has been done in collaboration with Dr. Donald Blake and his group at the University of California at Irvine. Specifically, it has been shown that C2Cl4 can be trapped quantitatively on a pre-column, thermally desorbed, and separated on an analytical column, with a "cycle-time" of about 6 minutes, and at temperatures at or below 50 oC. These parameters are important because we desire measurements with approximately 100 km resolution (which corresponds to about 8 minutes on a typical aircraft) and will not have the ability to use either cryogens or very high temperatures. Furthermore, tests have shown that we can readily detect the small concentrations (less than 10 parts per trillion) typically present in the upper troposphere. Additional studies have shown that the materials we plan to use in the sampling system (tubing, compressor diaphragm, etc.) are inert to C2Cl4.A preliminary design review (PDR) for the aircraft sensor package was held recently. During the PDR we presented our design for the GC system (along with designs for the other 3 sensors, integrated flow system, computer and data acquisition system, and mounting rack), which was created to enhance the precision of measurement. Essentially, we plan to incorporate two identical pre-column/column/detector assemblies; at a given time, one of these will be analyzing an ambient sample while the other will be measuring an on-board standard. The outcome of the PDR was generally extremely positive, but we have been strongly discouraged from attempting to fly an electron capture detector as part of the GC system. At this time we are pursuing both other possible detectors and a more authoritative answer from either the FAA or the airline industry regarding the issue of flying a radioactive source. Until this issue is resolved, we will be unable to move forward on the construction of the lightweight GC for aircraft use.
Future Activities:
We plan to have an integrated instrument package, designed to fly on NASA?s DC-8 research aircraft, finished by spring 1999, with test flights during the summer of 1999. For the GC system specifically, we plan a test of ambient, free tropospheric air at the University of California?s White Mountain Research Center this summer. Column assemblies will be completed by the end of summer 1998, and integrated to detectors, upon resolution of the issues described above. We also plan to continue testing and design of a similar instrument that could be used for ground-based field studies. This will move forward with the hire of a post-doctorate in late summer 1998.Journal Articles:
No journal articles submitted with this report: View all 17 publications for this projectSupplemental Keywords:
air, ozone, carbon dioxide, carbon tetrachloride, chemistry, monitoring, analytical., RFA, Scientific Discipline, Air, air toxics, Environmental Chemistry, climate change, tropospheric ozone, Atmospheric Sciences, Ecology and Ecosystems, monitoring, ambient ozone data, ozone occurrence, chemical composition, chemical transport model, gas chromatography, atmospheric chemical cycles, chemical kinetics, carbon dioxide, diode laser spectrometer, atmospheric monitoring, field measurements, lightweight instrumentation, measurement methods , three dimensional model, convective boundary layer, trace gas measurementRelevant Websites:
http://cloud1.arc.nasa.gov/solve/Progress 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.