DOI: 10.1594/pangaea.864827
title: CFC, and noble gas measurements during POLARSTERN cruise ANT-XXIX/3

description: During the austral summer expedition PS81, ANT-XXIX/3 with the German research ice breaker Polarstern in 2013, research was carried out to investigate the role of environmental factors on the distribution of benthic communities and marine mammal and krill densities around the northern tip of the Antarctic Peninsula. For these studies collated in this special issue and studies in this area, we present a collection of environmental parameters with probable influence on the marine ecosystems around the Antarctic Peninsula.
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 3 = doubtful; / = flag 4 = bad, # = flag 6 = mean of replicatesWe took water samples for stable noble gas isotopes (3He, 4He, Ne) (407 in copper tubes, 186 in AWS, of which 77 were replicate samples applying both sampling methods for inter-comparison) from 73 stations (profiles from bottom to surface) along 9 sections (7 in the north-western Weddell Sea, 2 in the Bransfield Strait, plus one extra station deployed from a life boat within the caldera of Deception Island). In total 421 samples were analyzed sucsessfull.In the IUP Bremen noble gas lab the samples are processed in a first step with a UHV (ultra high vacuum) gas extraction system. The required vacuum conditions are achieved by a rotary pump and an oil diffusion pump. To maintain contamination-free samples, the extraction system is checked for leaks on each sample separately. Sample gases are transferred via water vapour into a glass ampoule kept at liquid nitrogen temperature. Quality checks of this sample preparation line are done on a routine basis. This includes special vacuum checks and preparing accurately defined samples for internal control measurement.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 cryo system. Every 2 to 4 samples 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, doi:10.1080/10256010902871929).Error estimate for absolute He and Ne concentrations and the D(d3He):D(4He) &lt; 1.0 %D(Ne) &lt; 1.0 %D(d3He) &lt; 0.5 %For the chlorofluorocarbons (CFC-11, CFC-12), we took 940 samples on 77 stations (bottom-surface-profiles) along 10 sections (7 in the north-western Weddell Sea, 2 in the Bransfield Strait, 1 in the southern Drake Passage). 759 samples were analyzed sucessfully.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, 10.1029/2000JD900141). A more detailed description of the measurement system is given by Bulsiewicz et at. (1998, doi:10.1029/98JC00140).Concentrations of CFC-11 and CFC-12 reported on SIO 98 scale (Prinn et al., 2000, doi:10.1029/2000JD900141). Overall accuracy, including that off the calibration scale is estimated to be 2.5% for CFC-11 and 1.5% for CFC-12 (whichever is greater). The accuracy accounts for uncertainties of calibrated sample volume, calibration curve, extraction efficiency, standard and working gas, water blank, etc. Acknowledgment: Sampling on board and measurement of CFCs and noble gases at the IUP Bremen was funded by the Deutsche Forschungsgemeinschaft within the SPP 1158 "Antarktisforschung", grant HU 1544/4-1. We thank Julian Gutt, Michael Schröder and the scientific party to participate in the ANT-XXIX/3 expedition and for the excellent assistance and cooperation on board. We thank also master and crew of RV Polarstern.
description: Supplement to: Dorschel, Boris; Gutt, Julian; Huhn, Oliver; Bracher, Astrid; Huntemann, Marcus; Huneke, Wilma G C; Gebhardt, Andrea Catalina; Schröder, Michael (2016): Environmental information for a marine ecosystem research approach for the northern Antarctic Peninsula (RV Polarstern expedition PS81, ANT-XXIX/3). Polar Biology, 39(5), 765-787