Trifluoroacetate in the Environment. Evidence for Sources Other Than HFC/HCFCs ARMIN JORDAN § AND HARTMUT FRANK* Environmental Chemistry and Ecotoxicology, University of Bayreuth, D-95440 Bayreuth, Germany The partly halogenated C 2 -hydro(chloro)fluorocarbons (HFC, HCFC) 1,1,1-trifluoro-2,2-dichloroethane (HCFC-123), 1,1,1,2-tetrafluoro-2-chloroethane (HCFC-124), and 1,1,1,2- tetrafluoroethane (HFC-134a) are CFC substitutes found at increasing levels in the atmosphere. Trifluoroacetate (TFA) is an atmospheric degradation product of these compounds and due to its perstistence its potential accumulation in some aquatic ecosystems is a matter of environmental concern. The present study was undertaken to determine the present-days base level of environmental TFA and whether model calculations are in line with the actual data. Average levels of about 120 ng L -1 as predicted for the year 2010 are found in rain in Germany already now, slightly higher than in rain collected in Switzerland or Nevada. In the major rivers in Germany, TFA is present at average concentrations of 140 ng L -1 . In air, levels of 45-60 pg m -3 have been found in Central Europe. Between March 1995 and September 1996, a period of substantial increase in atmospheric HFC-134a mixing ratio, the TFA concentrations in air and precipitation did not significantly increase. TFA is absent in old groundwater samples, and in river water from remote locations, concentrations are low. These data suggest that the total TFA in both compartments exceeds the formation potential of currently known sources, that TFA in atmosphere and rain is regionally associated with industrial or population density, and that other unresolved sources must contribute to the present concentrations. Introduction The role of chlorofluorocarbons in the depletion of strato- spheric ozone (1, 2) has led to an international agreement to discontinue their production (3). Partially fluorinated ethanes with relatively short atmospheric residence times are now being introduced as alternatives. Atmospheric concentrations of1,1,1,2-tetrafluoroethane (HFC-134a), the prominent CFC replacement compound for automotive air conditioning and domestic refrigeration which began to be produced in 1990, have been steadily increasing (4, 5). The most significant rise in atmospheric concentrations was from 1994 onward, a result of increased production volumes and subsequent emission.Investigation ofthe environmentalfate of this compound (6), especially of its atmospheric lifetime (e.g. ref 7) and its degradation products (e.g. ref 8), has revealed trifluoroacetyl fluoride (CF3COF) as a major end product.Its yield depends on temperature and pressure and amounts to 7-20% averaged over the troposphere (9). Trifluoroacetyl fluoride is taken up by clouds, hydrolyzed to TFAwithin days (10), and wet-deposited to land and ocean surfaces. The CFC substitutes HCFC-123 (CF3CHCl2) and HCFC-124 (CF3CHClF)are converted to trifluoroacetylhalides with higher yields (11, 12), but these substances are manu- factured in lower quantities. Laboratory investigations have suggested that TFAcould be reductivelymetabolized under methanogenic conditions in sediments (13), but others have failed to detect any microbialorabioticdegradation ofTFAunderenvironmental conditions (14, 15). Behavior in soils is similar to that of chloride and bromide, i.e., TFAis only slightly retained (16, 17). It seems to persist in the hydrosphere and is taken up by higher plants (17, 18) and trees with the transpiration water, accumulating in leaves and needles of conifers. Model calculations predict global mean TFAconcentra- tions in precipitation in Europe of about 14 ng L -1 in 1995 (19) and of 120 ng L -1 in 2010 (10). These latter levels are already reached now; TFA analyses in Southern Germany (20, 21) show concentrations ranging from 10 to 200 ng L -1 in precipitation and from 60 to 600 ng L -1 in surface waters. Similar data have been reported recently for the Western United States (22, 23). These observations imply that the global environmental inventory of TFAis much higher than the amounts resulting from the degradation of presently known precursors. The aim of this work was to extend the database of environmentalTFAconcentrations in order to enable global budgetestimations.Air,precipitation,and riverwatersamples have been taken regularly and analyzed for TFAfrom March 1995 to September 1996 in Bayreuth (Northern Bavaria, Germany). Surface and ocean waters from several other locations and continents have also been analyzed as well as groundwater samples of preindustrial origin. Experimental Section Sampling. All glass ware used for sampling and cleanup was thoroughly washed with hot tap water and deionized water. It was stored at 280 °C in an oven and cooled prior to use in a closed glove compartment,both flushed with air purified by passage through cartridges filled with activated charcoal and potassium hydroxide. Rain samples were collected in the botanical garden of the UniversityofBayreuth from May1995 to June 1996 using Pyrex glass funnels (diameter 40 cm) and 500-mL brown glass bottles. From May 1996 to September 1996, samples of canopy runoff were collected from a conifer forest and from a clearing nearby. Surface water samples were collected in 250-mL brown glass bottles with screw-caps lined with Teflon-laminated butyl-rubber disks. After rinsing five times with the water of the location,the bottle wasfilled byimmersion leavingabout 1 mL of air space under the lid. Air samples were collected using glass denuder tubes (2.5 m × 1 cm id) consisting of five segments of 0.5 m length connected with ground-joints and Teflon sleeves on both ends. The denuders were coated with aqueous saturated solution of sodium carbonate in glycerol (20) which was always done at the sampling site to avoid contamination from laboratory air. Three denuders were run in parallel, each one connected to a membrane pump (N 035.1.2 AN 18, KNF Neuberger, Freiburg, Germany) followed downstream by a gas-volume counter (NBG, Kromschro ¨der, Osnabru ¨ck, Germany). In most cases, air volumes of 50-60 m 3 per *Corresponding author phone: +49-921-552373; fax: +49-921- 552334; e-mail: Hartmut.Frank@uni-bayreuth.de. § Present address: Max-Planck Institute for Aeronomy, D-37191 Katlenburg-Lindau, Germany. Environ. Sci. Technol. 1999, 33, 522-527 522 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 33, NO. 4, 1999 10.1021/es980674y CCC: $18.00  1999 American Chemical Society Published on Web 01/05/1999