SCIENTIFIC CORRESPONDENCE may be metabolized anaerobically in Environmental Trifluoroacetate soils8• The ages of the respective spring waters are unknown; therefore, further SIR - Partially fluorinated ethanes 20 to 150 pg m - 3 ( see table), at Waldstein studies are required to determine the ori­ (HFCs) are being introduced as coolants from 20 to 40 pg m- 3, and in Zurich are gin of TFA in these samples. for refrigeration and air conditioning as about 65 pg m-3 ( data not shown). The total amount of TFA in precipita­ alternatives for the ozone-depleting chlo­ Similarly, we found that TFA levels in tion on Germany is about 30 metric tons rofluorocarbons. For 1,1,1,2-tetrafluo­ rain water are 25-280 ng 1- 1 in Bayreuth annually ( average precipitation 800 mm, roethane, the most important HFC (see table), and in Zurich and at Alpthal surface area 357,000 km2). The annual (134a), an annual production of 230,000 (Switzerland) are 40-80 ng 1- 1 ( data not flow of TFA from the four main rivers of metric tons is expected for the year 20101, shown). The Roter Main River Germany to the sea (flow rates: Rhine, 30-40 % of which will be atmosphericallf (Bayreuth) contained 60-280 ng 1- 1 TFA, 2,170 m3 s- 1; Weser, 360 m3s-1; Elbe, 815 oxidized to trifluoroacetic acid (TFA)2· . similar to the levels in other rivers and m3s- 1; Danube 1,420 m3s- 1) is about 55 Based on the assumption that there is at lakes in Germany. TFA in spring waters in tons per year. Because half of the Rhine present no environmental TFA, levels of the Fichtelgebirge mountains in Germany and Danube water originate in other 5-20 pg m-3 in air and of 100-160 ng 1- 1 are 70-320 ng 1- 1• Lake Kinneret (Israel) countries, TFA export by rivers from Ger­ in precipitation have been forecast for and the Jordan River have concentrations many corresponds to wet deposition. 20104•5• However, air and water samples of 200 and 250 ng 1- 1, respectively, and The inhalation anaesthetic halothane collected in Germany, Switzerland and the Dead Sea 6,400 ng I - 1• The last figure (1, 1,1-trifluoro-2-bromo-2-chloro-ethane) Israel in 1995 already contain levels of is perhaps an example of evaporative is a major precursor of TFA; about 870 TFA in the range predicted for 2010. accumulation, as discussed previously7. metric tons a year are depositied through­ We collected air samples (30- 60 m3) Similar concentrations of TFA in pre­ out the world9 • The atmospheric lifetime using denuder tubes with alkaline coating cipitation and in spring water indicate of halothane is about a year, so TFA at a rate of 0.6 m3 h _, _ We determined that it is neither degraded nor absorbed to formed by this route should be evenly dis­ TFA by GC-MS6, always in triplicate. The the soil and may reach the ground water, tributed globally; less than 0.1 % would be air concentrations in Bayreuth range from although it has been suggested that TFA expected to be deposited on Germany. The estimated global TFA rainwater level TFA-CONCENTRATIONS IN AIR, PRECIPITATION AND SURFACE WATERS IN 1995 from this source and from tropospheric HFC-134a10 seems to be about 3 ng 1-1• Air Rain Surface waters Thus, relatively high average concentra­ 3 1 (pg m- ) (ng 1- ) (ng 1- 1) tions of TFA in rain (100 ng 1- 1) suggest that there are additional, unknown Roter Main Rivers / Springs Lake/Seawater sources. March 55±20 100± 50 160± 27 215 MB Ocean surface waters have TFA con­ (n= 3) (n=8) (n=3) 200 D 1 p centrations of 40-250 ng 1- (see table). 150 Although this indicates a potentially large April 70±40 40±4 80 260 N environmental inventory of TFA, more (n=9) (n= 4) data on oceanic depth profiles are needed May 50± 15 130± 65 140 130 S Sp 70 LF before we can reach any conclusions (n= 5) (n= 6) 110 ESp 115 LW about the origin of this TFA. 80 Nb Sp 70 WM Sp Hartmut Frank 320 F Sp Armin Klein June 50 190;240 110 Dirk Renschen Department of Environmental Chemistry July 25;25 70±20 100 E 90 NS and Ecotoxico/ogy, (n= 5) 100 w 40 BS 630 R University of Bayreuth, 60 Ww D-95440 Bayreuth, Aug. 120± 110 Germany (n=3) 1. McCulloch, A. Env. Int. 21, 353-362 (1995). 2. Wallingt on T. J. , Hurley, M. D .. Ball, J. C. & Kaiser, E. Sept. 70;120 100 60 LC W. Environ. Sci. Technol. 26, 1318-1324 (1994) 250 Atl.F 3. Rodriguez, J.M., Ko, M. K. W., Sze, N. D. & Heisey, C. W Proc. AFEAS Workshop on Atmospheric Wet and Dry Oct. 30 75 280 70 Atl.l Deposition of Carbonyl and Haloacetyl Halides 25-32 Nov. 20 60±55 110 250 J 200 LK (AFEAS, Brussels 1992). (n = 3) 4 . Franklin, J. Chemosphere 27, 1565-1601 (1993). 6,400 OS 5. Kotamarti, V. R. et al. (Abstr.) Eos 75, 137 (1994). Dec. 20 30 60 6. Frank, H., Renschen, D., Klein, A. & Scholl, H. J. High Res. Chromatogr. 18. 83- 88 (1995). 7. Tromp, T. K., Ko, M. K. W.. Rodriguez, J. M. & Sze, N. Average 50 100 140 D. Nature 376, 327- 330 (1995). 8. Visscher, P. T., Cu lbertson, C. W. & Oremland, R. S. Nature 369, 729- 731 (1994). All values are corrected for blank contribution.Three blank samples were always prepared in 9 . McCulloch, A. AFEAS Workshop on Environmental Fate of Triflouroacetic Acid (ed. Chumley, T. G.) Ch. 4(AFEAS, parallel; blank TFA concentrations were 10±3 ng/ L, giving a limit of determination of 20-40 ng Miami Beach, 1994). 1- 1 . For air the limit of determination is 20 pg m- 3 (air sample volume = 50 m3 ). Sampling 10. Montzka, S. A. et al. Geophys. Res. Zett. 23, 169- 172 sites: air/precipitation/ Rater Main: Bayreuth (360 m a.s.l.; E:11'35', N:49"56'); Surface (1996) waters: MB, Mistelbach (Bayreuth); D, Danube (Regensburg); P, Pegnitz (Nurnberg) N, Neckar (Tubingen); S Sp, Saale Spring (Fichtelgebirge mountains, FG); E Sp, Eger Spring (FG); Scientific Correspondence Nb Sp, Naab Spring (FG); WM Sp, White Main Spring (FG); F Sp, Friesen Spring (FG); E, Elbe Scientific Correspondence is intended to (Hamburg-Altona); W, Weser (Bremerhaven); R, Rhine (Duisburg-Ruhrort); Ww, Warnow (Ros­ provide a forum in which readers may tock); J, Jordan (shortly below Lake Kinneret/ lsrael); LF, Lake Fichte! (FG); LW, Lake Weis­ raise points of a scientific character. senstadt (FG); NS, North Sea (Husum); BS, Baltic Sea (Warnemunde); LC, Lake Constance Priority will be given to letters of fewer (Constance); Atl.F, Atlantic (lie d'Yeu/ France); Atl.l, Atlantic (Mace Head/Ireland); LK, Lake Kin­ than 500 words and five references. neret (Capernaum/ lsrael); DS, Dead Sea (En Bokek/ lsrael). 34 NATURE · VOL 382 · 4 JULY 1996 .