Chlorinated hydrocarbons in Scots pine needles in northern Britain

Concentrations of 4 chlorinated hydrocarbons, C2H3Cl3 (1,1,1-trichloroethene), CCl4 (tetrachloromethane), C2HCl3 (trichloroethene) and C2Cl4 (tetrachloroethene) have been measured in needles of Scots pine (Pinus sylvestris L.) growing close to two industrial sites and in a rural area in northern Britain. Pentane extracts of pine needles sampled over 14 months were analysed using gas chromatography with electron capture detection. Geometric mean concentrations were not significantly different among the sites, with values (in ng gʹ dry weight) of 7–15 for C2H3Cl3 3.2–6.5 for CCl4, 70–240 for C2HCl3 and 11–26 for C2C14. There was no evidence of accumulation with needle age, but more exposed sites (e.g. those higher in the canopy) showed significantly larger concentrations. The influence of possible local sources could not be detected.