Quantitative Analysis of Atmospheric OH by Active Titration
{'Code': '06020104', 'Directorate': {'LongName': 'Directorate For Geosciences'}, 'Division': {'LongName': 'Div Atmospheric & Geospace Sciences'}}
{'SignBlockName': 'Jarvis L. Moyers'}
In the past dozen years atmospheric scientists have determined              that the hydroxyl radical (OH) apparently plays a pivotal role in               controlling the trace chemical composition of the lower atmosphere              (troposphere).  Hydroxyl radicals (a pair) are produced when an ozone           molecule (O ) is decomposed by ultraviolet light to form an                                3                                                                    energetic oxygen atom which then reacts with a water molecule.  It is           believed that the hydroxyl radical is the primary species responsible           for converting a number of water insoluble reduced chemical compounds           (e.g. methane, sulfur dioxide, carbon monoxide, nitrogen dioxide,               ammonia and others) into condensable and/or water soluble oxidized              species.  It is this oxidation by OH which permits these compounds to           be cleansed from the atmosphere by precipitation or the gradual                 settling of small solid and liquid particles.  Our understanding of             the atmospheric photochemical oxidation process has been developed              primarily by laboratory and computer modeling studies.  To date it              has not been possible to evaluate the completeness of the theory of             tropospheric photochemical cycles.  To test this theory requires                making direct atmospheric measurements of OH and its relationships to           the compounds believed to be responsible for its creation and                   destruction.  The detection of the hydroxyl radical in the ambient              atmosphere has been a primary objective of atmospheric chemists for             the past several years.  The difficulty in measuring this species               results from its exceedingly low concentration in the atmosphere.               Theory predicts OH to be in concentrations one million to a hundred             million times smaller than ozone, its parent compound (which itself             has a tropospheric concentration of less than one part in ten                   million).  The techniques presently available for measuring OH are              not sufficiently sensitive to make the necessary measuremetns in the            atmosphere to study the chemistry of this important species.                                                                                                    In this project an experimental determination of tropospheric                   boundary layer hydroxyl radical concentrations using an active                  titration technique will be attempted.  The method involves release             of a mixture of two classes of gases: titrant gases which are                                                         _______                                   destroyed predominantly by reaction with OH on a time scale of a day            or two; and dispersant gases which are inert essentially and used to                        __________                                                          determine the dispersion rate of the mixture once it is released into           the atmosphere.  The time rate of change of the ratio of the titrant            and dispersant gas concentrations can be related to the local OH                concentration.  Several unsaturated halocarbons as titrants and                 certain saturated halocarbons as dispersants will be measured and               their concentrations measured with an electron-capture gas                      chromatograph.
{'FirstName': 'Ronald', 'LastName': 'Prinn', 'EmailAddress': 'rprinn@mit.edu', 'StartDate': '07/15/1987', 'EndDate': None, 'RoleCode': 'Principal Investigator'}
{'Name': 'Massachusetts Institute of Technology', 'CityName': 'Cambridge', 'ZipCode': '021394301', 'PhoneNumber': '6172531000', 'StreetAddress': '77 MASSACHUSETTS AVE', 'CountryName': 'United States', 'StateName': 'Massachusetts', 'StateCode': 'MA'}
{'Code': '1524', 'Text': 'ATMOSPHERIC CHEMISTRY'}
{'url': 'https://www.nsf.gov/awardsearch/download?DownloadFileName=1986&All=true', 'xml': '8617419.xml'}