Tropospheric concentrations of the chlorinated solvents, tetrachloroetheneand trichloroethene, measured in the remote northern hemisphere

A fully automated twin ECD gas chromatograph system with sample enriching a dsorption-desorption primary stage was deployed on two field campaigns - Ny -Alesund, Svalbard, Arctic Norway (July-September 1997), and the RRS Discov ery CHAOS cruise of the northeast Atlantic (April-May 1998). Concentrations of an extensive set of halocarbons were detected at hourly intervals at pp tv levels. We present here the results obtained for the chlorinated solvent s, tetrachloroethene (PCE) and trichloroethene (TCE). Average baseline PCE and TCE concentrations of 1.77 and 0.12 pptv, respectively, were recorded i n Ny-Alesund. During pollution incidences, concentrations rose to 5.61 (PCE ) and 3.18 pptv (TCE). The cruise data showed average concentrations rangin g from 4.26 (PCE) and 1.66 pptv (TCE) for air masses originating over the N orth Atlantic and Arctic open oceans, to maxima of 15.59 (PCE) and 17.51 pp tv (TCE) for polluted air masses from Northern Europe. The data sets emphas ise the difficulties in defining remote sites for background tropospheric h alocarbon measurements, as Ny-Alesund research station proved to be a sourc e of tetrachloroethene. The data also suggest possible oceanic emissions of trichloroethene in the sub-tropical ocean. (C) 2001 Elsevier Science Ltd. All rights reserved.