A note on reporting of reservoir 14C disequilibria and age offsets

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here for personal use, not for redistribution. The definitive version was published in Radiocarbon 58 (2016): 205-211, doi:10.1017/RDC.2015.22.Reservoir age offsets are widely used to correct marine and speleothem radiocarbon age measurements for various calibration purposes. They also serve as a powerful tracer for carbon cycle dynamics. However, a clear terminology regarding reservoir age offsets is lacking, sometimes leading to miscalculations. This note seeks to provide consistent conventions for reporting reservoir 14C disequilibria useful to a broad range of environmental sciences. This contribution introduces the F14R and δ14R metrics to express the relative 14C disequilibrium between two contemporaneous reservoirs and the R metric as the associated reservoir age offset.G.S. acknowledges the Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution with funding provided by the National Ocean Sciences Accelerator Mass Spectrometry Facility (OCE-1239667). S.R.B acknowledges Dean Minghua Zhang and Provost Dennis Assanis of Stony Brook University for financial support

Glacier meltwater and monsoon precipitation drive Upper Ganges Basin dissolved organic matter composition

Author Posting. © The Author(s), 2019. This is the author's version of the work. It is posted here by permission of Elsevier Ltd. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 244 (2019): 216-228, doi:10.1016/j.gca.2018.10.012.Mountain glaciers store dissolved organic carbon (DOC) that can be exported to river networks and subsequently respired to CO2. Despite this potential importance within the global carbon cycle, the seasonal variability and downstream transport of glacier-derived DOC in mountainous river basins remains largely unknown. To provide novel insight, here we present DOC concentrations and molecular-level dissolved organic matter (DOM) compositions from 22 nested, glaciated catchments (1.4 – 81.8 % glacier cover by area) in the Upper Ganges Basin, Western Himalaya over the course of the Indian summer monsoon (ISM) in 2014. Aliphatic and peptide-like compounds were abundant in glaciated headwaters but were overprinted by soil-derived phenolic, polyphenolic and condensed aromatic material as DOC concentrations increase moving downstream. Across the basin, DOC concentrations and soil-derived compound class contributions decreased sharply from pre- to post-ISM, implying increased relative contribution of glaciated headwater signals as the monsoon progresses. Incubation experiments further revealed a strong compositional control on the fraction of bioavailable DOC (BDOC), with glacier-derived DOC exhibiting the highest bioavailability. We hypothesize that short-term (i.e. in the coming decades) increases in glacier melt flux driven by climate change will further bias exported DOM toward an aliphatic-rich, bioavailable signal, especially during the ISM and post-ISM seasons. In contrast, eventual decreases in glacier melt flux due to mass loss will likely lead to more a soil-like DOM composition and lower bioavailability of exported DOC in the long term.We thank Britta Voss (WHOI) for assisting with sample collection; Travis Drake (FSU), and Ekaterina Bulygina (Woods Hole Research Center) for laboratory assistance; and the NHMFL ICR user program (NSF-DMR-1157490) for aiding in data acquisition and analysis. This study was partly supported by NSF-DEB-1145932 to R.G.M.S. J.D.H. was partially supported by the NSF Graduate Research Fellowship Program under grant number 2012126152, with additional support in the form of travel grants awarded by the MIT Houghten Fund and NHMFL. All data used in this study are available in the Supporting Information Tables S1 and S2

Mesures de spectrométrie et de dosimétrie neutron aux postes de travail pour l'étalonnage de dosimètres individuels PGP-DIN

International audience(ManuAcrit r e p le 3 juillet 2002, accepté le 29 septembre 2002) Dans le cadre de la mise en application des recommandations décrites dans la publication 60 de la CIPR, des mesures de spectrométrie neutron ont été réalisées à plusieurs postes de travail au CEA de Valduc. Le but de ces mesures était la détermination de nouveaux coefficients d'étalonnage h affecter aux dosimètres individuels neutron PGP-DIN afin de restituer correctement les doses reçues par les opérateurs séjournant h ces postes. Ces mesures ont été effectuées au cours de deux campagnes successives. La tluence neutronique et le débit d'équivalent de dose amhiantH*(IO) ont été mesurés en fonction de l'énergie avec le spectromètre ROSPEC et un système de sphères de BONNER. Les champs de radiations étant toutefois mixtes, c'est-à-dire présentant une composante neutronique et photonique, des mesures de débits d'équivalent de dose ambiant photon aux postes de travail considérés ont également été réalisées à l'aide de débitmètres d'ambiance. Les dosimètres individuels PGP-DIN ont été positionnés sur un fantôme (ISO) d'eau. Des calculs effectués h l'aide du code MCNP ont été comparés aux résultats expérimentaux. Neutron spectrometry and dosimetry measurement at workplaces for calibration of individual PGP-DIN dosimeters. Measurements to determine new coefficients for individual neutron dosimeters PGP-DIN complying with the ICRP 60 recommendations were performed at two workplaces at the CEA of Valduc: a storage r w m and a plutonium reprocessing plant. Two spectrometry campaigns were performed allowing a better assessment of doses received by operators worki.ng at these workplaces. Neutron energy fluence and ambient dose equivalent rate H*(10) distributions were measured as function of neutron energy by using the ROSPEC device and BONNER spheres spectrometer. The radiation field being mixed neutron and gamma, the gamma component was also evaluated: neutron and photon dose-rate meters were nsed to evaluate the ambient dose rate equivalent. Individual dosemeters were positioned on an ISO water slab phantom. In addition, calculations were performed using the MCNP simulation code for different configurations. ' Insiitui de radioprotection ct de sûre16 nucléaire, DPHD, B.P. 17. 92262 Fontcnay-aux-Roses Cedcx, France

Media justice: Madeleine McCann, intermediatization and "trial by media" in the British press

Three-year-old Madeleine McCann disappeared on 3 May 2007 from a holiday apartment in Portugal. Over five years and multiple investigations that failed to solve this abducted child case, Madeleine and her parents were subject to a process of relentless ‘intermediatization’. Across 24–7 news coverage, websites, documentaries, films, YouTube videos, books, magazines, music and artworks, Madeleine was a mediagenic image of innocence and a lucrative story. In contrast to Madeleine’s media sacralization, the representation of her parents, Kate and Gerry McCann, fluctuated between periods of vociferous support and prolonged and libellous ‘trial by media’. This article analyses how the global intermediatization of the ‘Maddie Mystery’ fed into and fuelled the ‘trial by media’ of Kate and Gerry McCann in the UK press. Our theorization of ‘trial by media’ is developed and refined through considering its legal limitations in an era of ‘attack journalism’ and unprecedented official UK inquiries into press misconduct and criminality

Arctic deltaic lake sediments as recorders of fluvial organic matter deposition

© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Earth Science 4 (2016): 77, doi:10.3389/feart.2016.00077.Arctic deltas are dynamic and vulnerable regions that play a key role in land-ocean interactions and the global carbon cycle. Delta lakes may provide valuable historical records of the quality and quantity of fluvial fluxes, parameters that are challenging to investigate in these remote regions. Here we study lakes from across the Mackenzie Delta, Arctic Canada, that receive fluvial sediments from the Mackenzie River when spring flood water levels rise above natural levees. We compare downcore lake sediments with suspended sediments collected during the spring flood, using bulk (% organic carbon, % total nitrogen, δ13C, Δ14C) and molecular organic geochemistry (lignin, leaf waxes). High-resolution age models (137Cs, 210Pb) of downcore lake sediment records (n = 11) along with lamina counting on high-resolution radiographs show sediment deposition frequencies ranging between annually to every 15 years. Down-core geochemical variability in a representative delta lake sediment core is consistent with historical variability in spring flood hydrology (variability in peak discharge, ice jamming, peak water levels). Comparison with earlier published Mackenzie River depth profiles shows that (i) lake sediments reflect the riverine surface suspended load, and (ii) hydrodynamic sorting patterns related to spring flood characteristics are reflected in the lake sediments. Bulk and molecular geochemistry of suspended particulate matter from the spring flood peak and lake sediments are relatively similar showing a mixture of modern higher-plant derived material, older terrestrial permafrost material, and old rock-derived material. This suggests that deltaic lake sedimentary records hold great promise as recorders of past (century-scale) riverine fluxes and may prove instrumental in shedding light on past behavior of arctic rivers, as well as how they respond to a changing climate.Funding was provided by the US National Science Foundation as part of the Arctic Great Rivers Observatory (NSF-0732522 and NSF-1107774), as well as the Netherlands Organization for Scientific Research (Rubicon #825.10.022, and Veni #863.12.004). Additional funding for the lake coring was provided from WHOI through its Ocean and Climate Change Institute

Constraints on the Timing and Extent of Deglacial Grounding Line Retreat in West Antarctica

Projections of Antarctica\u27s contribution to future sea level rise are associated with significant uncertainty, in part because the observational record is too short to capture long-term processes necessary to estimate ice mass changes over societally relevant timescales. Records of grounding line retreat from the geologic past offer an opportunity to extend our observations of these processes beyond the modern record and to gain a more comprehensive understanding of ice-sheet change. Here, we present constraints on the timing and inland extent of deglacial grounding line retreat in the southern Ross Sea, Antarctica, obtained via direct sampling of a subglacial lake located 150 km inland from the modern grounding line and beneath \u3e1 km of ice. Isotopic measurements of water and sediment from the lake enabled us to evaluate how the subglacial microbial community accessed radiocarbon-bearing organic carbon for energy, as well as where it transferred carbon metabolically. Using radiocarbon as a natural tracer, we found that sedimentary organic carbon was microbially translocated to dissolved carbon pools in the subglacial hydrologic system during the 4.5-year period of water accumulation prior to our sampling. This finding indicates that the grounding line along the Siple Coast of West Antarctica retreated more than 250 km inland during the mid-Holocene (6.3 ± 1.0 ka), prior to re-advancing to its modern position

Efficient organic carbon burial in the Bengal fan sustained by the Himalayan erosional system

Author Posting. © Nature Publishing Group, 2007. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature 450 (2007): 407-410, doi:10.1038/nature06273.Continental erosion controls atmospheric carbon dioxide levels on geological timescales through silicate weathering, riverine transport and subsequent burial of organic carbon in oceanic sediments. The efficiency of organic carbon deposition in sedimentary basins is however limited by the organic carbon load capacity of the sediments and organic carbon oxidation in continental margins. At the global scale, previous studies have suggested that about 70 per cent of riverine organic carbon is returned to the atmosphere, such as in the Amazon basin. Here we present a comprehensive organic carbon budget for the Himalayan erosional system, including source rocks, river sediments and marine sediments buried in the Bengal fan. We show that organic carbon export is controlled by sediment properties, and that oxidative loss is negligible during transport and deposition to the ocean. Our results indicate that 70 to 85 per cent of the organic carbon is recent organic matter captured during transport, which serves as a net sink for atmospheric carbon dioxide. The amount of organic carbon deposited in the Bengal basin represents about 10 to 20 per cent of the total terrestrial organic carbon buried in oceanic sediments. High erosion rates in the Himalayas generate high sedimentation rates and low oxygen availability in the Bay of Bengal that sustain the observed extreme organic carbon burial efficiency. Active orogenic systems generate enhanced physical erosion and the resulting organic carbon burial buffers atmospheric carbon dioxide levels, thereby exerting a negative feedback on climate over geological timescales

Global-scale evidence for the refractory nature of riverine black carbon

Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Nature Geoscience 11 (2018): 584-588, doi:10.1038/s41561-018-0159-8.Wildfires and incomplete combustion of fossil fuel produce large amounts of black carbon. Black carbon production and transport are essential components of the carbon cycle. Constraining estimates of black carbon exported from land to ocean is critical, given ongoing changes in land use and climate, which affect fire occurrence and black carbon dynamics. Here, we present an inventory of the concentration and radiocarbon content (∆14C) of particulate black carbon for 18 rivers around the globe. We find that particulate black carbon accounts for about 15.8 ± 0.9% of river particulate organic carbon, and that fluxes of particulate black carbon co-vary with river-suspended sediment, indicating that particulate black carbon export is primarily controlled by erosion. River particulate black carbon is not exclusively from modern sources but is also aged in intermediate terrestrial carbon pools in several high-latitude rivers, with ages of up to 17,000 14C years. The flux-weighted 14C average age of particulate black carbon exported to oceans is 3,700 ± 400 14C years. We estimate that the annual global flux of particulate black carbon to the ocean is 0.017 to 0.037 Pg, accounting for 4 to 32% of the annually produced black carbon. When buried in marine sediments, particulate black carbon is sequestered to form a long-term sink for CO2.A.C. acknowledges financial support from the University of Zurich Forschungskredit Fellowship and the University of Zurich (grant No. STWF-18-026). M.R., S.A. and M.S. acknowledge support from the University Research Priority Projection Global Change and Biodiversity (URPP-GCB). M.Z. acknowledges support from the National Natural Science Foundation of China (No. 41521064). T.E. acknowledges support from the Swiss National Science Foundation (“CAPS-LOCK” and “CAPS-LOCK2” #200021_140850). V.G. acknowledges financial support from an Independent Study Award from the Woods Hole Oceanographic Institution

Research Trends in Evidence-Based Medicine: A Joinpoint Regression Analysis of More than 50 Years of Publication Data

Background Evidence-based medicine (EBM) has developed as the dominant paradigm of assessment of evidence that is used in clinical practice. Since its development, EBM has been applied to integrate the best available research into diagnosis and treatment with the purpose of improving patient care. In the EBM era, a hierarchy of evidence has been proposed, including various types of research methods, such as meta-analysis (MA), systematic review (SRV), randomized controlled trial (RCT), case report (CR), practice guideline (PGL), and so on. Although there are numerous studies examining the impact and importance of specific cases of EBM in clinical practice, there is a lack of research quantitatively measuring publication trends in the growth and development of EBM. Therefore, a bibliometric analysis was constructed to determine the scientific productivity of EBM research over decades. Methods NCBI PubMed database was used to search, retrieve and classify publications according to research method and year of publication. Joinpoint regression analysis was undertaken to analyze trends in research productivity and the prevalence of individual research methods. Findings Analysis indicates that MA and SRV, which are classified as the highest ranking of evidence in the EBM, accounted for a relatively small but auspicious number of publications. For most research methods, the annual percent change (APC) indicates a consistent increase in publication frequency. MA, SRV and RCT show the highest rate of publication growth in the past twenty years. Only controlled clinical trials (CCT) shows a non-significant reduction in publications over the past ten years. Conclusions Higher quality research methods, such as MA, SRV and RCT, are showing continuous publication growth, which suggests an acknowledgement of the value of these methods. This study provides the first quantitative assessment of research method publication trends in EBM