TRICHLOROACETIC-ACID IN CONIFER NEEDLES AND ARBOREAL LICHENS IN FOREST ENVIRONMENTS

In the past, trichloroacetic acid (TCA) was a commonly used herbicide, which caused alterations in the properties of surface wax, inhibited growth and caused leaf necrosis. TCA is also a degradation product of short chain chlorocarbons which are used as solvents and degreasers in industry. TCA may also originate from the bleaching of kraft pulp wit h agents containing chlorine. In this study TCA concentrations in coni fer needles were determined in several rural forest areas in subarctic regions in Finland. TCA was analyzed as its methyl ester by GC/NCI-MS /SIR. The TCA levels in the third-year needles varied in the range 1-1 80 mu g kg(-1) (median 23 mu g kg(-1), n = 130); 90% of the values bei ng between 5 and 70 mu g kg(-1). No regional concentration trends coul d be observed. TCA was also present in arboreal lichens of conifers, w hich is further proof of its atmospheric origin. Comparison of the TCA levels in Usneaceae lichens with lichen biomass gave a significant ne gative correlation (P = 0.02), whereas TCA concentrations in needles a nd visible symptoms of tree vitality did not show causal relationships .