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

Contribution à l'étude des saisies d'Ecstasy par spectrométrie de masse de rapports isotopiques (apport du rapport 15N/14N)

Illicit drugs have always been used by humans. With scientific progress, new drugs appear each year. At the present time, in France, Ecstasy is the most widespread illicit synthetic drug. The term Ecstasy generally refers to tablets containing 3,4-méthylendioxy-methamphetamine (MDMA). In order to struggle against traffics of drugs of abuse, many methods can be employed. In this study, 13C/12C and 15N/14N ratios of MDMA samples were measured by isotopic techniques, in particular by using a Gas chromatograph-combustion-isotope ratio mass spectrometer (GC-C-IRMS). The aim of such analyses was to confirm that links exists between precursors, synthetic pathways and MDMA, and in the same way to establish links between drug seizures...NANTES-BU Sciences (441092104) / SudocSudocFranceF

Methoxylated fatty acids in Blumeria graminis conidia

International audienceThe total fatty acids (FA) composition of Blumeria graminis f.sp. tritici conidia, the causal agent of wheat powdery mildew, was analyzed as a function of their age. A total of 19 FA (C 12–C 24 saturated and unsaturated) and unusual methoxylated fatty acids (mFA) were detected in young, intermediate and old conidia. Two very long chain methoxylated FA were identified by GC–MS as 3-methoxydocosanoic and 3-methoxytetracosanoic acids. Medium chain FA were predominant in young conidia (75%, including 13% of mFA) while very long chain fatty acids constituted the major compounds in old conidia (74%, including 30% of mFA). We have shown for the first time that the total FA composition is strongly correlated with the age of B. graminis f.sp. tritici (Bgt) conidia

Karelianite and vanadian phlogopite from the merelani hills gem zoisite deposits, Tanzania.

International audienc

C4 plants decline in the Himalayan basin since the Last Glacial Maximum

The Bengal Fan turbiditic system, supplied by the Ganga-Brahmaputra river system, provides an integrated record of Himalayan system erosion. Thanks to minor inputs of marine organic matter and almost complete preservation of riverine organic carbon, organic matter buried in Bengal Fan sediments is a proxy of Himalayan basin paleo-vegetation. The active channel-levee system of the middle fan documents the last 19 ka and allows the reconstruction of vegetation change in the Himalayan basin since the Last Glacial Maximum (LGM). We measured delta C-13 of organic carbon (C-org) in order to track changes in the proportions of C3 and C4 plants in the Himalayan basin. From LGM to mid-Holocene, delta C-13 of bulk C-org shifts of 3-4%. towards more negative values. Relative abundance of individual n-alkanes reveals that terrestrial higher plant inputs represent a dominant fraction of C-org buried in Bengal Fan sediments. delta C-13 of higher plants biomarkers mimic that of bulk C-org showing that the later can be used as continental paleo-vegetation proxy. delta C-13 negative shift from LGM to mid-Holocene, mostly indicates the transition from a dominant input of C4 plants to a dominant input of C3 plants and therefore reveals that C4 plants were more abundant in the basin under glacial conditions. Vegetation repartition in the basin simulated using the CARAIB dynamic vegetation model is consistent with C-org data. The model indicates a dominance of C4 plants in the Gangetic plain during the LGM while eastern part of the basin remains dominated by C3 plants. The comparison between our data and proxies of regional paleo-climate suggests that the large decline of C4 plants after the LGM was due to combined increase of atmospheric CO2 and humidity levels. Integrated record of Himalayan basin paleo-vegetation suggests more and conditions during the LGM than during the mid-Holocene and agrees with reconstructions of the monsoon indicating stronger SW monsoon during interglacial and stronger NE monsoon during glacial periods. (C) 2008 Elsevier Ltd. All rights reserved

Maintaining Resilient Infrastructure Systems in: Task Force 7 Infrastructure Investment and Financing, Policy Brief

Sommet du G20 , ROME, ITALIE, 30-/10/2021 - 31/10/2021Improving maintenance management and increasing investment in infrastructure maintenance makes it possible to boost the resilience of infrastructure against a variety of threats. This has a positive financial return for developed as well as developing countries. uilding on the issues outlined in two seminal T20 Policy Briefs Building Resilient Infrastructure Systems (ABDI, 2020) and Evaluating Resilient Infrastructure Systems (Evans et al., 2020), this Policy Brief: (i) advocates for a global maintenance framework addressing the specificities of developed and developing countries, (ii) calls for the development of infrastructure bonds and standardised ratings that include maintenance issues, capable of securing financial resources for maintenance and (iii) draws G20 members' attention to the issue of human resilience and the human factor to ensure the long-term maintainability of Quality InfrastructureL'amélioration de la gestion de la maintenance et l'augmentation des investissements dans la maintenance des infrastructures permettent de renforcer la résilience des infrastructures contre diverses menaces. Cela a un retour financier positif pour les pays développés comme pour les pays en développement. S'appuyant sur les questions décrites dans deux notes d'orientation fondamentales du T20 Building Resilient Infrastructure Systems (ABDI, 2020) et Evaluating Resilient Infrastructure Systems (Evans et al., 2020), cette note d'orientation : (i) plaide en faveur d'un cadre de maintenance mondial répondant aux spécificités des pays développés et en développement, (ii) appelle au développement d'obligations d'infrastructure et de notations standardisées qui incluent les problèmes de maintenance,capable de sécuriser les ressources financières pour la maintenance et (iii) attire l'attention des membres du G20 sur la question de la résilience humaine et du facteur humain pour assurer la maintenabilité à long terme de l'Infrastructure Qualité