DOI: 10.1594/pangaea.931336
title: Noble gas (He, Ne isotopes) and transient tracer (CFC-11 and CFC-12) measurements from POLARSTERN cruise PS100 (northeast Greenland, 2016)

description: Noble gases (3He, 4He, 20Ne, 22Ne)In total we took 650 water samples for stable noble gas isotopes (3He, 4He, 20Ne, 22Ne) in copper tubes from 69 stations in Fram Strait, on the north-eastern Greenland shelf and nearby 79 North Glacier (79NG, Nioghalvfjerdsbræ). The water samples were stored from the CTD/water bottle system without contact to atmospheric air and preventing air bubbles into gas tight copper tubes, which are clamped of at both sides.In the IUP Bremen noble gas lab the samples were pre-processed with a UHV (ultra high vacuum) gas extraction system. Sample gases are transferred via water vapour into a glass ampoule kept at liquid nitrogen temperature. For analysis of the noble gas isotopes the glass ampoules are connected to a fully automated UHV mass spectrometric system equipped with a two stage cryogenic system. Regularly, the system is calibrated with atmospheric air standards (reproducibility &lt;0.2%). Also measurement of line blanks and linearity are done. The performance of the Bremen facility is described in Sültenfuß et al. (2009).The total errors for the noble gas measurements are estimated to be 0.4% for 4He, 0.4% for total Ne, and 0.4% for δ3He.Chlorofluorocarbons (CFC-11, CFC-12)For the transient tracers (chlorofluorocarbons, CFC-11 and CFC-12), we took samples on 80 stations in Fram Strait, on the north-eastern Greenland shelf and nearby 79 North Glacier (79NG, Nioghalvfjerdsbræ). The Chlorofluorocarbon (CFC-11 and CFC-12) water samples from the CTD-bottle-system were 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 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. 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. CFC concentrations are calibrated on SIO98 scale (Prinn et al., 2000). A more detailed description of the measurement system is given by Bulsiewicz et at. (1998).The overall accuracy is estimated to be 1.5% for CFC-11 and 1.0% for CFC-12. The accuracy accounts for uncertainties of calibrated sample volume, calibration curve, extraction efficiency, standard and working gas, water blank, etc.These noble-gas and CFC data are related to Kanzow et al. (2017). They will be first published in Huhn et al 2021, in prep).AcknowledgmentWe thank master and crew of FS Polarstern cruise PS 100. This work was partly funded by the DFG in the framework of the Priority Program SPP 1889 "Regional Sea Level and Society", grants RH25/43 to M. Rhein and HU 1544/7 to O. Huhn).
description: The tracer data set was carefully checked for accurate measurements and outliers. According to the WOCE standards the following flags were applied to each measurement:flag 2 = goodflag 3 = doubtfulflag 4 = badflag 6 = mean of replicatesflag 9 = no measurement (then, the data value is missing)