Levels of airborne halocarbons in Swiss forests as determined by needle analysis

Rationale

Chironico - one of the sites used in this study.

Haloacetic acids are atmospheric oxidation products of halogenated C2-hydrocarbons. Quantitatively, the most relevant are the C2-chlorocarbons: 1,1,1-tricholoroethane, trichloroethane and tetrachloroethane. Annual global production of the C2-halocarbons is currently >2 Mt. Halocarbon exposure can result in degradation of photosynthetic pigments in trees and affect xenobiotic metabolism in plants. Their atmospheric oxidation products, particularly the haloacetic acids, are more potent and some have been used as herbicides. The potential increase in haloacetic acids in the environment as a result of introducing C2-chlorofluorohydrocarbons as substitutes for CFCs, brings a need for further investigation.

Project aims

The aim of this project is to determine the levels of trichloroacetate in needles of conifer species in Swiss forests and to compare these with levels in other European forests.

Methods and work plan

Samples will be collected from LTFER plots in October 1997 as part of routine foliar sampling for element assessments. At the University of Bayreuth, TCA will be extracted with 1.5 ml diethyl ether, derivatized to the methyl ester with diazomethane and analysed by capillary gas chromatography and electron capture detection. Results will be verified by negative-ion chemical-ionization mass spectrometry and selected-ion monitoring of the ions m/z 35 and m/z 37 (CL-).

Publications

• Frank, H., Scholl, H., Sutinen, S. and Norokorpi, Y. 1992. Trichloroacetic acid in conifer needles in Finland. Ann. Bot. Fennici 29, 263-267.
• Frank, W., Neves, H.J.C. and Frank, H. 1991. Levels of airborne halocarbons at urban and mountain forest sites in Germany and at the Atlantic coast. Chemosphere 23, 609-626.
• Frank, W., Scholl, H., Renschen, D., Rether, B., Laouedj, A. and Norokorpi, Y. 1993. Haloacetic acids, phytotoxic secondary air pollutants. Environ. Sci. and Pollut. Res. 1, 1-11.

Participants

• Harmut Frank (University of Bayreuth)
• John Innes