@article {castrillejo_comparability_2023,
	title = {Comparability of Radiocarbon Measurements in Dissolved Inorganic Carbon of Seawater Produced at ETH-Zurich},
	journal = {Radiocarbon},
	year = {2023},
	note = {Publisher: Cambridge University Press},
	month = {03/2023},
	pages = {1{\textendash}10},
	abstract = {Radiocarbon observations (Δ14C) in dissolved inorganic carbon (DIC) of seawater provide useful information about ocean carbon cycling and ocean circulation. To deliver high-quality observations, the Laboratory of Ion Beam Physics (LIP) at ETH-Zurich developed a new simplified method allowing the rapid analysis of radiocarbon in DIC of small seawater samples, which is continually assessed by following internal quality controls. However, a comparison with externally produced 14C measurements to better establish an equivalency between methods was still missing. Here, we make the first intercomparison with the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility based on 14 duplicate seawater samples collected in 2020. We also compare with prior deep-water observations from the 1970s to 1990s. The results show a very good agreement in both comparisons. The mean Δ14C of 12 duplicate samples measured by LIP and NOSAMS were statistically identical within one sigma uncertainty while two other duplicate samples agreed within two sigma. Based on this small number of duplicate samples, LIP values appear to be slightly lower than the NOSAMS values, but more measurements will be needed for confirmation. We also comment on storage and preservation techniques used in this study, including the freezing of samples collected in foil bags.},
	keywords = {14C, comparison, DIC, dissolved inorganic carbon, radiocarbon, SEAWATER},
	issn = {0033-8222, 1945-5755},
	doi = {10.1017/RDC.2023.16},
	url = {https://www.cambridge.org/core/journals/radiocarbon/article/comparability-of-radiocarbon-measurements-in-dissolved-inorganic-carbon-of-seawater-produced-at-ethzurich/B9F6C6AA45835FA3ED0BF8E0CD9788E3},
	author = {Castrillejo, Maxi and Hansman, Roberta L. and Graven, Heather D. and Lester, Joanna G. and Bollhalder, Silvia and K{\"u}ndig, Kayley and Wacker, Lukas}
}
@article {2630,
	title = {An Investigation of Gas Exchange and Water Circulation in the Amundsen Sea Based On Dissolved Inorganic Radiocarbon},
	journal = {Geophysical Research Letters},
	volume = {453},
	year = {2018},
	month = {Apr-11-2020},
	pages = {12,368 - 12,375},
	abstract = {We used radiocarbon isotope ratios in dissolved inorganic carbon to assess gas exchange and water circulation in the western Amundsen Sea. Radiocarbon isotope ratios indicate that Circumpolar Deep Water enters the basin along the seafloor and that the upper layer is formed through modification of this water mass. In the Amundsen Sea Polynya, radiocarbon isotope ratios of surface water are higher than those of underlying Winter Water, implying rapid absorption of atmospheric CO2. A CO2 absorption rate of 45mmol m(-2) d(-1) calculated for a site in the central polynya is higher than that near the Dotson Ice Shelf (28mmolm(-2) d(-1)). The turnover time of water in the Dotson Trough region of the western Amundsen Sea is estimated to be 10-30years, based on results from a box model and radiocarbon mass balance.

Plain Language Summary The western Amundsen Sea is experiencing raid physical changes including rapid glacial melting and declining sea ice cover. The suggested heat source is the intrusion of warm Circumpolar Deep Water (CDW) along the seafloor of the Amundsen Shelf. Therefore, understanding the behavior of the intruded CDW, especially how long it stays on the shelf, is important. Physical oceanographic studies have examined the flux of CDW onto and out of the Amundsen Shelf. However, the turnover time of water in the Amundsen Sea is still poorly understood. In this paper, we use radiocarbon isotope signature from dissolved inorganic carbon to examine how rapidly atmospheric CO2 is absorbed into the Amundsen Sea Polynya and how long the water should stay in the western Amundsen Shelf to have the observed radiocarbon isotope signature. Based on our results and the current understanding of the water circulation in the western Amundsen Sea, we found that the water sits on the Amundsen Shelf for a few decades before it moves off shelf.},
	keywords = {Amundsen sea, dissolved inorganic carbon, gas exchange, radiocarbon, water circulation},
	issn = {0094-8276},
	doi = {10.1029/2018GL079464},
	url = {http://apps.webofknowledge.com/InboundService.do?product=WOS\&Func=Frame\&DestFail=http\%3A\%2F\%2Fwww.webofknowledge.com\%3FDestParams\%3DUT\%253DWOS\%25253A000453250000030\%2526customersID\%253DAlerting\%2526smartRedirect\%253Dyes\%2526action\%253Dretrieve\%2526mode\%25},
	author = {Kim, Bumsoo and Lee, SangHoon and Kim, Minkyoung and Hahm, Doshik and Rhee, Tae Siek and Hwang, Jeomshik}
}
@article {Zigah2017,
	title = {Constraining the sources and cycling of dissolved organic carbon in a large oligotrophic lake using radiocarbon analyses},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {208},
	year = {2017},
	pages = {102-118},
	abstract = {Abstract We measured the concentrations and isotopic compositions of solid phase extracted (SPE) dissolved organic carbon (DOC) and high molecular weight (HMW) \{DOC\} and their constituent organic components in order to better constrain the sources and cycling of \{DOC\} in a large oligotrophic lacustrine system (Lake Superior, North America). \{SPE\} \{DOC\} constituted a significant proportion (41-71\%) of the lake \{DOC\} relative to \{HMW\} \{DOC\} (10-13\%). Substantial contribution of 14C-depleted components to both \{SPE\} \{DOC\} (Δ14C = 25 to 43{\textperthousand}) and \{HMW\} \{DOC\} (Δ14C = 22 to 32{\textperthousand}) was evident during spring mixing, and depressed their radiocarbon values relative to the lake dissolved inorganic carbon (DIC; Δ14C \~{} 59{\textperthousand}). There was preferential removal of 14C-depleted (older) and thermally recalcitrant components from \{HMW\} \{DOC\} and \{SPE\} \{DOC\} in the summer. Contemporary photoautotrophic addition to \{HMW\} \{DOC\} was observed during summer stratification in contrast to \{SPE\} DOC, which decreased in concentration during stratification. Serial thermal oxidation radiocarbon analysis revealed a diversity of sources (both contemporary and older) within the \{SPE\} DOC, and also showed distinct components within the \{HMW\} DOC. The thermally labile components of \{HMW\} \{DOC\} were 14C-enriched and are attributed to heteropolysaccharides (HPS), peptides/amide and amino sugars (AMS) relative to the thermally recalcitrant components reflecting the presence of older material, perhaps carboxylic-rich alicyclic molecules (CRAM). The solvent extractable lipid-like fraction of \{HMW\} \{DOC\} was very 14C-depleted (as old as 1270-2320 14C years) relative to the substances isolated by acid hydrolysis of \{HMW\} DOC. Our data constrain relative influences of contemporary \{DOC\} and old DOC, and \{DOC\} cycling in a modern freshwater ecosystem.},
	keywords = {atmospheric co2, Carbohydrate-like substance, Carboxylic-rich alicyclic molecules (CRAM), Contemporary DOC, dissolved inorganic carbon, dissolved organic carbon, Freshwater carbon cycling, Heteropolysaccharides (HPS), High molecular weight DOC, Lake Superior, Lipid-like fraction, Old DOC, Oligotrophic lake, Protein-like substance, radiocarbon, Serial thermal oxidation, Solid phase extracted DOC, Stable isotope, Unhydrolysable material},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2017.03.021},
	url = {http://www.sciencedirect.com/science/article/pii/S0016703717301722},
	author = {Prosper K. Zigah and Elizabeth C. Minor and Ann P. McNichol and Li Xu and Josef P. Werne}
}
@article { ISI:000389875700006,
	title = {DISSOLVED INORGANIC RADIOCARBON IN THE NORTHWEST PACIFIC CONTINENTAL MARGIN},
	journal = {RADIOCARBON},
	volume = {58},
	number = {{3}},
	year = {2016},
	month = {SEP},
	pages = {517-529},
	type = {Article},
	abstract = {This article presents a modified method for extraction of dissolved inorganic carbon (DIC) from seawater for radiocarbon measurement by accelerator mass spectrometry (AMS). Standard tests indicate that the extraction efficiencies of DIC are >96\%, and the respective precisions of. Delta C-14-DIC and delta C-13-DIC analyses are 6\% and 0.1\% or better. Using the method, we report. Delta C-14-DIC profiles collected from the shelf and slope in the East China Sea (ECS) of the northwest Pacific Ocean. Both the DIC concentration and. Delta C-14-DIC in the shelf and slope regions seem primarily affected by the Kuroshio Current. It is estimated that 54-65\% of the bottom water in the shelf region could be from the intrusion of Kuroshio intermediate water, which carries a high concentration and low. Delta C-14 values of DIC, and which influenced the DIC and its Delta C-14 signature on the shelf. Compared with the. Delta C-14-DIC profiles at other sites in the northwest Pacific reported previously, it appears that the. Delta C-14-DIC distributions are mainly controlled by the major oceanic currents in the region, and large variations in. Delta C-14-DIC occurred mostly in the upper 800m of the water column. The similarity of. Delta C-14-DIC at depth suggests that the deep-water circulation patterns have been relatively stable in the northwest Pacific Ocean in the last 20 yr.},
	keywords = {continental margin, dissolved inorganic carbon, East China Sea, radiocarbon, stable carbon isotope},
	issn = {0033-8222},
	doi = {10.1017/RDC.2016.23},
	author = {Ge, Tiantian and Wang, Xuchen and Zhang, Jing and Luo, Chunle and Xue, Yuejun}
}
@conference {1279,
	title = {An Ocean-Wide DIC-13 Data Set},
	booktitle = {2000 Ocean Sciences Meeting, San Antonio, TX (USA), 24-28 Jan 2000},
	year = {2000},
	note = {Date revised - 2007-04-01SuppNotes - Abstracts available.Last updated - 2016-12-21},
	month = {January 2000},
	publisher = {American Geophysical Union, 2000 Florida Ave., N.W. Washington, DC 20009 USA},
	organization = {American Geophysical Union, 2000 Florida Ave., N.W. Washington, DC 20009 USA},
	abstract = {High quality DIC-13 measurements were made throughout the world{\textquoteright}s oceans at the University of Washington (UW) and the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Facility during both the OACES and WOCE programs. We are currently merging these two data sets which represent 25000 individual DIC- 13 measurements from 1260 stations. We will present the inter-laboratory calibration and standardization data. Based on 135 measurements on CO2 gas extracted at UW, the mean offset between the two labs is 0.01 o/oo, similar to the offset observed from an exchange of DIC standards (0.012 o/oo). Stations measured by both laboratories will also be examined for offsets, although one comparison in the Indian Ocean shows no significant differences. We will present our progress towards a global atlas of DIC-13, primarily maps of the merged data sets in the Pacific, Southern, and Indian Oceans. In this poster we will concentrate on regions that have been under-sampled in the past, e.g. the Southern Ocean. Additionally, we will examine the relationship of DIC-13 to PO4 and to DIC-14. A preliminary analysis of DIC-13 and PO4 from three WOCE lines in the Pacific indicates that the expected relationship is observed in the deep waters and that the data from different water masses occupy well-defined regions of the graph. We are examining the potential for using the relationship between DIC-14 and DIC-13 to improve our understanding of the penetration of bomb radiocarbon into the ocean as well as fundamental processes in the deep ocean. The relationship is complex yet the data from shallow to intermediate depths (100 to 1000m) follow two distinct parallel lines that are related to the hemisphere in which},
	keywords = {carbon cycling, Carbon dioxide, Deep water, dissolved inorganic carbon, ISW, Indian Ocean, Marine, Mass Spectrometry, Ocean circulation, Phosphates, PS, Antarctic Ocean, Q2 09146:TSD distribution, water masses and circulation, Stable isotopes, Standardization, Water masses, World Ocean, World Ocean Circulation Experiment (WOCE)},
	url = {https://search.proquest.com/docview/19610793?accountid=29119},
	author = {McNichol, A P and Quay, P D and Stuart, D R and Sonnerup, R E and Key, R M}
}
