Chlorofluorocarbons measured on water bottle samples during POLARSTERN cruise ANT-XXII/3
During the expedition a total of 800 samples on 60 CTD stations were collected for chlorofluorocarbons (CFC-11 and CFC-12), of which 723 where successfully analysed. The water samples from the rosette system were collected into 100 ml glass ampoules and sealed off after a CFC free headspace of pure...
| Main Authors: | , , , |
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| Format: | Dataset |
| Language: | English |
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PANGAEA - Data Publisher for Earth & Environmental Science
2013
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| Online Access: | https://dx.doi.org/10.1594/pangaea.770667 https://doi.pangaea.de/10.1594/PANGAEA.770667 |
| Summary: | During the expedition a total of 800 samples on 60 CTD stations were collected for chlorofluorocarbons (CFC-11 and CFC-12), of which 723 where successfully analysed. The water samples from the rosette system were collected into 100 ml glass ampoules and sealed off after a CFC free headspace of pure nitrogen had been applied.The Chlorofluorocarbon (CFC-11 and CFC-12) water samples from the CTD-bottle-system are stored in glass ampoules without contact to the atmosphere during the tapping. Immediately after sampling the ampoules are flame sealed after a CFC free headspace of pure nitrogen had been applied.The loss of CFCs into the headspace is considered by a careful equilibration between liquid and gas phase under controlled conditions before the sealed ampoules are opened and a precise measurement of the volume of the headspace. The determination of CFC concentrations in the IUP Bremen gas chromatography lab is accomplished by purge and trap sample pre-treatment followed by gas chromatographic (GC) separation on a capillary column and electron capture detection (ECD). The system is calibrated by analyzing several different volumes of a known standard gas. CFC concentrations are calibrated on SIO98 scale (Prinn et al., 2000, doi:10.1029/2000JD900141). A more detailed description of the measurement system is given by Bulsiewicz et at. (1998, doi:10.1029/98JC00140).Accuracy (i.e. uncertainties of calibrated sample volume, calibration curve, extraction efficiency, standard and working gas, water blank, etc.):- CFC-12 < 1.8 %- CFC-11 < 3.1 %Precision (i.e. mean error from 16 replicate samples):- CFC-12 < 0.006 pmol/kg or < 1.2 % (which ever is greater)We do not give a value for the precision of CFC-12. Offline sample chromatograms regularly show a negative peak in the vicinity of the CFC-11 peak, which decreases the accuracy of CFC-11 in comparison to CFC-12, and which does not allow giving an objective estimate of a precision for CFC-11.Sampling on board and measurement of CFCs at the IUP Bremen was funded by the Deutsche Forschungsgemeinschaft within the SPP 1158 "Antarktisforschung", grant RH 25/27. We thank Eberhard Fahrbach, Gerd Rohardt, Mario Hoppema and the scientific party to participate in the ANT-XXII/3 expedition and for the excellent assistance and cooperation on board. We further thank the master and crew of RV Polarstern.CFC measurements: Klaus BulsiewiczQuality flags: ? = doubtful; / = bad; # = mean of replicates |
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