| Abstract
| - Chloroacetic acids (CAAs) and trifluoroacetic acid (TFA)are widely distributed environmental pollutants. The originof CAAs is still under debate, while TFA is considered tobe a major atmospheric degradation product of recentlyintroduced hydrochlorofluorocarbons (HCFCs) andhydrofluorocarbons (HFCs). Because of the phytotoxicpotential of the CAAs, i.e., monochloroacetic acid (MCA),dichloroacetic acid (DCA), and trichloroacetic acid (TCA),and the persistence of TFA, these compounds are ofconsiderable environmental concern. Hence, it is importantto know their fluxes and their spatial and temporaldistribution in the environment. In this study, the occurrenceand mass fluxes of MCA, DCA, TCA, and TFA wereassessed on a regional scale over Switzerland, based onmore than 1000 concentration measurements in rainand snow, surface water, groundwater, and wastewater.Among different precipitation events, the measuredconcentrations varied significantly from <11 to 7100 ng/L.However, no statistically different average haloaceticacid (HAA) concentrations among six precipitation samplingsites located in various areas in Switzerland wereobserved (range of average concentrations: MCA 1430−2770 ng/L, DCA 390−1370 ng/L, TCA 95−380 ng/L, TFA 33−220 ng/L). The similar average HAA concentrations inprecipitation at a remote site close to the free troposphereat an elevation of 3580 m above sea level (Jungfraujoch)and at a site that receives precipitation which scavenged theEarth's boundary layer (urban site Dübendorf/Zürich)suggests that HAAs are derived from well-mixed precursor(s) in the atmosphere. When moving from precipitationto surface waters (i.e., rivers), the TFA/CAA ratios increasedby a factor of 10−11 for TFA/MCA and TFA/DCA and bya factor of 1.2 for TFA/TCA. Mass flux calculations show thatprecipitation is the dominant source of the HAAs,particularly of MCA, DCA, and TFA (>95%). In the case ofTCA, wastewater effluents contributed 27% of the totalinput. The results further indicate that, as compared to theCAAs, TFA is quite persistent in the aquatic and terrestrialenvironment and may thus accumulate in soils andgroundwater.
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