Technical note : an inverse method to relate organic carbon reactivity to isotope composition from serial oxidation

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 14 (2017): 5099-5114, doi:10.5194/bg-14-5099-2017.Serial oxidation coupled with stable carbon and radiocarbon analysis of sequentially evolved CO2 is a promising method to characterize the relationship between organic carbon (OC) chemical composition, source, and residence time in the environment. However, observed decay profiles depend on experimental conditions and oxidation pathway. It is therefore necessary to properly assess serial oxidation kinetics before utilizing decay profiles as a measure of OC reactivity. We present a regularized inverse method to estimate the distribution of OC activation energy (E), a proxy for bond strength, using serial oxidation. Here, we apply this method to ramped temperature pyrolysis or oxidation (RPO) analysis but note that this approach is broadly applicable to any serial oxidation technique. RPO analysis directly compares thermal reactivity to isotope composition by determining the E range for OC decaying within each temperature interval over which CO2 is collected. By analyzing a decarbonated test sample at multiple masses and oven ramp rates, we show that OC decay during RPO analysis follows a superposition of parallel first-order kinetics and that resulting E distributions are independent of experimental conditions. We therefore propose the E distribution as a novel proxy to describe OC thermal reactivity and suggest that E vs. isotope relationships can provide new insight into the compositional controls on OC source and residence time.This research was supported by the NSF Graduate Research Fellowship Program grant no. 2012126152 (Jordon D. Hemingway), NASA Astrobiology grant no. NNA13AA90A and NSF grant no. EAR-1338810 (Daniel H. Rothman), and the WHOI Independent Study Award (Valier V. Galy)

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

Seasonal hydrology drives rapid shifts in the flux and composition of dissolved and particulate organic carbon and major and trace ions in the Fraser River, Canada

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 12 (2015): 5597-5618, doi:10.5194/bg-12-5597-2015.Rapid changes in the volume and sources of discharge during the spring freshet lead to pronounced variations in biogeochemical properties in snowmelt-dominated river basins. We used daily sampling during the onset of the freshet in the Fraser River (southwestern Canada) in 2013 to identify rapid changes in the flux and composition of dissolved material, with a focus on dissolved organic matter (DOM). Previous time series sampling (at twice monthly frequency) of dissolved inorganic species in the Fraser River has revealed smooth seasonal transitions in concentrations of major ions and tracers of water and dissolved load sources between freshet and base flow periods. In contrast, daily sampling reveals a significant increase in dissolved organic carbon (DOC) concentration (200 to 550 μmol L−1) occurring over a matter of days, accompanied by a shift in DOM optical properties, indicating a transition towards higher molecular weight, more aromatic DOM composition. Comparable changes in DOM composition, but not concentration, occur at other times of year, underscoring the role of seasonal climatology in DOM cycling. A smaller data set of total and dissolved Hg concentrations also showed variability during the spring freshet period, although dissolved Hg dynamics appear to be driven by factors beyond DOM as characterized here. The time series records of DOC and particulate organic carbon (POC) concentrations indicate that the Fraser River exports 0.25–0.35 % of its annual basin net primary productivity. The snowmelt-dominated hydrology, forested land cover, and minimal reservoir impoundment of the Fraser River may influence the DOC yield of the basin, which is high relative to the nearby Columbia River and of similar magnitude to that of the Yukon River to the north. Anticipated warming and decreased snowfall due to climate changes in the region may cause an overall decrease in DOM flux from the Fraser River to the coastal ocean in coming decadesThis work was partially supported by a WHOI Ocean Ventures Fund award to BMV and NSF grants EAR-1226818 to BPE, OCE-0851015 to TIE, BPE, and VG, and OCE-0851101 to RGMS, and support to BPE from Jane and James Orr

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

Die rechtliche Regelung des Instituts der kostenlosen Rechtshilfe in der Republik Kroatien mit besonderer Berücksichtigung der gesetzlichen Regelungen in den postjugoslawischen Staaten

“Pravo i pravdu nećemo nikome prodati, uskratiti ili odgoditi.” 40. paragraf Velike povelje sloboda Pravo na pristup pravosuđu (access to justice) jedno je od temeljnih ljudskih prava. Ostvarivanje toga prava uvelike ovisi o dostupnosti pravne pomoći svim građanima bez obzira na njihov socioekonomski status. Stoga je postojanje učinkovitog sustava besplatne pravne pomoći u svakoj zemlji jedan od temeljnih jamaca ostvarivanja ljudskih prava u svakodnevnom životu. U radu se razmatra razvoj i uređenje instituta besplatne pravne pomoći u Republici Hrvatskoj te u ostalim postjugoslavenskim državama s ciljem regionalnog prikaza njegova uređenja.«To no one will we sell, to no one will we refuse or delay, right or justice» 40th paragraph of the Magna Charta The paper considers the development and regulation of the institute of legal aid in the Republic of Croatia and in the other post-Yugoslav states with the aim of providing a regional outline of their regulation. In recent years legislators in the post-Yugoslav states have been increasingly involved in the regulation of legal aid and, in order to develop modern legal systems, they adopted laws aimed at ensuring and protecting the right to legal aid. The normative activities for regulating legal aid began with the constitutional guarantee for such aid, and were made effective by the provisions of the criminal codes and the civil procedure acts. Later, under the influence of the acquis communautaire of the modern European states they were to be included in the provisions of separate laws of the post-Yugoslav states. This shows that there was an evolution in the development of the right to legal aid, not only as the right to such aid in the form of good will and charity of the state, but also as one of the fundamental human rights guaranteed by constitutional and legal norms.“Niemandem werden wir Recht oder Gerechtigkeit verkaufen, verweigern oder verzögern.“ Magna Carta, § 40 In dieser Arbeit werden die Entwicklung und Regelung des Instituts der kostenlosen Rechtshilfe in der Republik Kroatien und in den anderen postjugoslawischen Staaten erörtert, wodurch seine Regelung in der Region dargestellt werden soll. In den letzten Jahren ist die Regelung des Anspruchs auf kostenlose Rechtshilfe zu einer wichtigen Aufgabe für die Gesetzgeber in den postjugoslawischen Staaten geworden, die zwecks Aufbau moderner Rechtsordnungen Gesetze verabschiedeten, deren Gegenstand die Wahrnehmung und der Schutz des Rechts auf kostenlose Rechtshilfe ist. Die normative Aktivität zur Einrichtung der kostenlosen Rechtshilfe begann mit der Verfassungsgarantie des Rechtsanspruches auf kostenlose Rechtshilfe, die in den Bestimmungen der Straf- und der Zivilprozessordnung ihren konkreten Niederschlag fanden, um sich unter dem Einfluss der Trends in der Gesetzgebung der modernen europäischen Staaten zu Bestimmungen in Sondergesetzen der postjugoslawischen Staaten zu verwandeln. Dies belegt eine Evolution in der Entwicklung des Rechtsanspruchs auf kostenlose Rechtshilfe als nicht allein des Anspruchs auf Hilfe in Form einer wohltäterischen Geste von staatlichem guten Willen, sondern als eines Grundrechts, das durch Verfassungs- und Gesetzesnormen garantiert wird

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

Technical note: An inverse method to relate organic carbon reactivity to isotope composition from serial oxidation

Serial oxidation coupled with stable carbon and radiocarbon analysis of sequentially evolved CO₂ is a promising method to characterize the relationship between organic carbon (OC) chemical composition, source, and residence time in the environment. However, observed decay profiles depend on experimental conditions and oxidation pathway. It is therefore necessary to properly assess serial oxidation kinetics before utilizing decay profiles as a measure of OC reactivity. We present a regularized inverse method to estimate the distribution of OC activation energy (E), a proxy for bond strength, using serial oxidation. Here, we apply this method to ramped temperature pyrolysis or oxidation (RPO) analysis but note that this approach is broadly applicable to any serial oxidation technique. RPO analysis directly compares thermal reactivity to isotope composition by determining the E range for OC decaying within each temperature interval over which CO₂ is collected. By analyzing a decarbonated test sample at multiple masses and oven ramp rates, we show that OC decay during RPO analysis follows a superposition of parallel first-order kinetics and that resulting E distributions are independent of experimental conditions. We therefore propose the E distribution as a novel proxy to describe OC thermal reactivity and suggest that E vs. isotope relationships can provide new insight into the compositional controls on OC source and residence time.National Science Foundation (U.S.) (Grant 2012126152)United States. National Aeronautics and Space Administration (Grant NNA13AA90A)National Science Foundation (U.S.) (Grant EAR-1338810

Controls on the age of plant waxes in marine sediments – A global synthesis

Sedimentary high molecular weight (HMW) n-alkyl lipids derived from the waxes of terrestrial plants are common target compounds in biogeochemical and paleoenvironmental research. These plant waxes derive predominantly from the epicuticular cover of vascular plant leaves and their relative and absolute abundances and stable isotopic composition can be used as proxies to decipher, e.g., continental climate and land-ocean carbon transfer processes. In marine sediments, however, compound-specific radiocarbon analysis has revealed that plant waxes are often not syn-depositional, but instead are substantially 14C-depleted (‘pre-aged’) upon deposition. This 14C-depletion can be caused by various processes that either promote retention of plant waxes during transport from source to sink such as storage in soils or entrainment in deposition-resuspension loops in rivers and on continental shelves or, alternatively, by processes that add HMW n-alkyl lipids from other sources (e.g., petrogenic inputs). Here, we review the intrinsic and extrinsic processes affecting the sedimentary plant wax 14C composition (ranging from chemical processes to continental-scale environmental conditions), how plant wax 14C compositions translate into mean ages, and which processes control plant wax mean ages in marine sediments. Finally, we use a compilation of available and new compound-specific plant wax 14C data to provide a synthesis and evaluate the major controls on plant wax mean ages in marine sediments at the global scale