A radiocarbon tracer method for measuring tropospheric OH
Thesis/Dissertation
·
OSTI ID:7195993
A radiochemical method for measuring the ground-level ambient hydroxyl radical (OH) concentration was refined. The method uses {sup 14}CO as a tracer of the atmospheric OH-CO reaction in a UV transparent photochemical reactor. The OH concentration is inferred from the resulting {sup 14}CO{sub 2} activity, reaction time, tracer concentration, and CO-OH reaction rate constant. The causes of the highly variable measurements obtained with the method prior to 1985 were overcome with the development of an isotopic-dilution system for the purification of the {sup 14}CO{sub 2}, and a column packed with porous polymer beads for the removal of the interfering ambient {sup 222}Rn. In contrast to other methods, which are limited by atmospheric concentration fluctuations, precision of the Radiocarbon Tracer method is limited only by {sup 14}C counting uncertainty. Therefore, refinements of purification techniques could result in an OH detection limit of about 10{sup 4} radicals cm{sup {minus}3}. Forty-three experiments performed on five days in October 1987 revealed the first tropospheric OH variations ever reproduced. Calculations with a non-steady-state photochemical model with variable NO{sub x} concentrations agreed with clean air OH measurements performed near Colfax, WA and others.
- Research Organization:
- Washington State Univ., Pullman, WA (USA)
- OSTI ID:
- 7195993
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
540111* -- Environment
Atmospheric-- Basic Studies-- Radiometric Techniques-- (1990-)
ALPHA DECAY RADIOISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON 14
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
DAYS LIVING RADIOISOTOPES
EARTH ATMOSPHERE
EVEN-EVEN NUCLEI
HEAVY NUCLEI
HYDROXYL RADICALS
ISOTOPE APPLICATIONS
ISOTOPE DILUTION
ISOTOPES
LIGHT NUCLEI
MEASURING METHODS
NUCLEI
OXIDES
OXYGEN COMPOUNDS
RADICALS
RADIOISOTOPES
RADON 222
RADON ISOTOPES
REMOVAL
TRACER TECHNIQUES
TROPOSPHERE
YEARS LIVING RADIOISOTOPES
540111* -- Environment
Atmospheric-- Basic Studies-- Radiometric Techniques-- (1990-)
ALPHA DECAY RADIOISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON 14
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
DAYS LIVING RADIOISOTOPES
EARTH ATMOSPHERE
EVEN-EVEN NUCLEI
HEAVY NUCLEI
HYDROXYL RADICALS
ISOTOPE APPLICATIONS
ISOTOPE DILUTION
ISOTOPES
LIGHT NUCLEI
MEASURING METHODS
NUCLEI
OXIDES
OXYGEN COMPOUNDS
RADICALS
RADIOISOTOPES
RADON 222
RADON ISOTOPES
REMOVAL
TRACER TECHNIQUES
TROPOSPHERE
YEARS LIVING RADIOISOTOPES