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Trichlorofluoromethane in groundwater—A Possible tracer and indicator of groundwater age
Author(s) -
Thompson Glenn M.,
Hayes J. M.
Publication year - 1979
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr015i003p00546
Subject(s) - groundwater , atmosphere (unit) , aquifer , hydrology (agriculture) , precipitation , tracer , environmental science , geology , geography , meteorology , physics , geotechnical engineering , nuclear physics
Trichlorofluoromethane, an entirely man‐made material, has become a detectable component of the atmosphere. Because of its unique atmospheric history, the presence of CCl 3 F in groundwater is potentially significant in terms of groundwater age. The age relationship stems from the fact that precipitation, exposed to CCl 3 F in the atmosphere, will pick up an amount that is proportional to the atmospheric CCl 3 F concentration. If a portion of this water infiltrates into the subsurface to become groundwater, it can be differentiated from older groundwater (that infiltrated prior to the buildup of CCl 3 F in the atmosphere) on the basis of its CCl 3 F content. In order to evaluate the temporal significance of CCl 3 F in groundwater, preliminary investigations were conducted in three areas where the hydrology was well understood and where tritium measurements had been made in the past. They were: the Wharton tract of southern New Jersey; Hot Springs National Park in Hot Springs, Arkansas; and the Edwards aquifer of south central Texas. Good agreement was observed between the CCl 3 F data and the hydrologic controls. The Texas study also revealed a series of anomalous CCl 3 F concentrations (up to 35 × 10 −9 g CCl 3 F/I H 2 O) that were too high to be of atmospheric origin. The anomalous points occurred in a line extending from the northwest corner of San Antonio for a distance of 74 km northeast along the Balcones fault zone and are interpreted as representing the migration of CCl 3 F from a point source, thus indicating the potential of this and similar compounds as hydrologic tracers.