38 research outputs found

    Carbon uptake by mature Amazon forests has mitigated Amazon nations' carbon emissions

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    Background: Several independent lines of evidence suggest that Amazon forests have provided a significant carbon sink service, and also that the Amazon carbon sink in intact, mature forests may now be threatened as a result of different processes. There has however been no work done to quantify non-land-use-change forest carbon fluxes on a national basis within Amazonia, or to place these national fluxes and their possible changes in the context of the major anthropogenic carbon fluxes in the region. Here we present a first attempt to interpret results from groundbased monitoring of mature forest carbon fluxes in a biogeographically, politically, and temporally differentiated way. Specifically, using results from a large long-term network of forest plots, we estimate the Amazon biomass carbon balance over the last three decades for the different regions and nine nations of Amazonia, and evaluate the magnitude and trajectory of these differentiated balances in relation to major national anthropogenic carbon emissions. Results: The sink of carbon into mature forests has been remarkably geographically ubiquitous across Amazonia, being substantial and persistent in each of the five biogeographic regions within Amazonia. Between 1980 and 2010, it has more than mitigated the fossil fuel emissions of every single national economy, except that of Venezuela. For most nations (Bolivia, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname) the sink has probably additionally mitigated all anthropogenic carbon emissions due to Amazon deforestation and other land use change. While the sink has weakened in some regions since 2000, our analysis suggests that Amazon nations which are able to conserve large areas of natural and semi-natural landscape still contribute globally-significant carbon sequestration. Conclusions: Mature forests across all of Amazonia have contributed significantly to mitigating climate change for decades. Yet Amazon nations have not directly benefited from providing this global scale ecosystem service. We suggest that better monitoring and reporting of the carbon fluxes within mature forests, and understanding the drivers of changes in their balance, must become national, as well as international, priorities

    Safety of intravenous ferric carboxymaltose versus oral iron in patients with nondialysis-dependent CKD: an analysis of the 1-year FIND-CKD trial.

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    Background: The evidence base regarding the safety of intravenous (IV) iron therapy in patients with chronic kidney disease (CKD) is incomplete and largely based on small studies of relatively short duration. Methods: FIND-CKD (ClinicalTrials.gov number NCT00994318) was a 1-year, open-label, multicenter, prospective study of patients with nondialysis-dependent CKD, anemia and iron deficiency randomized (1:1:2) to IV ferric carboxymaltose (FCM), targeting higher (400-600 µg/L) or lower (100-200 µg/L) ferritin, or oral iron. A post hoc analysis of adverse event rates per 100 patient-years was performed to assess the safety of FCM versus oral iron over an extended period. Results: The safety population included 616 patients. The incidence of one or more adverse events was 91.0, 100.0 and 105.0 per 100 patient-years in the high ferritin FCM, low ferritin FCM and oral iron groups, respectively. The incidence of adverse events with a suspected relation to study drug was 15.9, 17.8 and 36.7 per 100 patient-years in the three groups; for serious adverse events, the incidence was 28.2, 27.9 and 24.3 per 100 patient-years. The incidence of cardiac disorders and infections was similar between groups. At least one ferritin level ≥800 µg/L occurred in 26.6% of high ferritin FCM patients, with no associated increase in adverse events. No patient with ferritin ≥800 µg/L discontinued the study drug due to adverse events. Estimated glomerular filtration rate remained the stable in all groups. Conclusions: These results further support the conclusion that correction of iron deficiency anemia with IV FCM is safe in patients with nondialysis-dependent CKD

    Chemical and Nd isotope constraints on granitoid sources involved in the Caledonian Orogeny in Scotland

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    Major- and trace-element data and Nd isotope compositions for granitoid samples from the Grampian Highlands in Scotland show a systematic evolution in the composition of their sources in the course of the Caledonian Orogeny. Granitoids of 511-451 Ma, related to the collision of the Midland Valley island arc with the Grampian terrane, show S-type affinity and fractionated REE patterns with minor Eu anomalies and low initial epsilon(Nd) values of -14.1 to -11.2 suggesting melting of predominantly Dalradian metasediments. Subsequently formed granitoids of 425-406 Ma derived from an assumed Andean plate margin comprise a wide spectrum of rock types including I-type granite-granodiorite, and S-type granitoids, monzonites and alkali granites. The trace-element patterns of these rocks and the range of initial epsilon(Nd) values of -2.1 to -6.9 are consistent with melting of variably rejuvenated crust as found in continental margin settings. We conclude that the Grampian Highlands were affected by two major crust-modifying events during the Caledonian Orogeny: predominantly recycling of older crust during docking of the Midland Valley arc and addition of juvenile, mantle-derived material to the crust during the convergence of Avalonia with Laurentia.</p

    Petrogenesis of albite-rich mid- to late Proterozoic tephra-fall deposits ('brown beds')

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    The discovery of volcanogenic 'brown beds' in Dalradian and Torridonian (Sleat Group and Diabaig Group) sequences in Scotland has raised questions about their origin and provenance. New discoveries of a grey facies cognate to the 'brown beds' have led to an hypothesis which proposes that these beds originated as tephra-fall deposits of intermediate to mafic composition. Subsequent prehnite-pumpellyite- and greenschist-facies metamorphism generated an albite-chlorite-muscovite-quartz-calcite assemblage. Recent sub-aerial weathering selectively dissolved interstitial calcite and oxidized iron, which left an albite-rich 'brown bed' with a porous saccharoidal texture. Field relationships and mineralogy support their origin as tephra-fall deposits and their widespread occurrence suggests they are not localized phenomena. Crucially, the weathered 'brown beds' point to the existence of otherwise cryptic grey metamorphosed tuffs which tend to blend in with their host metasediments.</p

    Petrogenesis of albite-rich mid- to late Proterozoic tephra-fall deposits ('brown beds')

    No full text
    The discovery of volcanogenic 'brown beds' in Dalradian and Torridonian (Sleat Group and Diabaig Group) sequences in Scotland has raised questions about their origin and provenance. New discoveries of a grey facies cognate to the 'brown beds' have led to an hypothesis which proposes that these beds originated as tephra-fall deposits of intermediate to mafic composition. Subsequent prehnite-pumpellyite- and greenschist-facies metamorphism generated an albite-chlorite-muscovite-quartz-calcite assemblage. Recent sub-aerial weathering selectively dissolved interstitial calcite and oxidized iron, which left an albite-rich 'brown bed' with a porous saccharoidal texture. Field relationships and mineralogy support their origin as tephra-fall deposits and their widespread occurrence suggests they are not localized phenomena. Crucially, the weathered 'brown beds' point to the existence of otherwise cryptic grey metamorphosed tuffs which tend to blend in with their host metasediments.</p

    Incorporating “virtual” and “real world” field trips into introductory geography modules

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    The “field trip” is a key pedagogical tool within geographical education to encourage deep learning, though they are increasingly difficult to implement due to reduced budgets, safety concerns and increasing class sizes. We incorporated three field-learning activities into a large introductory module. A traditional staff-led trip was the most effective activity in terms of enjoyment, knowledge, and deep thinking and awareness. Self-paced field activities and video podcasts had less pedagogical value, though can still support lectures and the staff-led field trip. An integrated approach will best maximize deep learning opportunities

    Petrogenesis of Malaysian granitoids in the Southeast Asian tin belt:Part 1. Geochemical and Sr-Nd isotopic characteristics

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    The Malaysian granitoids of the Southeast Asian tin belt have been traditionally divided into a Permian to Late Triassic "I-type"- dominated arc-related Eastern province (Indochina terrane) and a Late Triassic "S-type"-dominated collision-related Main Range province (Sibumasu terrane), separated by the Bentong-Raub Paleo-Tethyan suture that closed in the Late Triassic. The present study, however, shows that this model is oversimplified and that the direct application of Chappell and White's (1974) I- and S-type classification cannot account for many of the characteristics shared by Malaysian granitoids. Despite being commonly hornblende bearing, as is typical for I-type granites, the roof zones of the Eastern province granites are hornblende free. In addition, the Main Range province granitoids contain insignificant primary muscovite, and are dominated by biotite granites, mineralogically similar to many of the plutons of the Eastern province. In general, the Malaysian granitoids from both provinces are more enriched in high field strength elements than typical Cordilleran I- and S-type granitoids. The mineralogy and geochemistry of the Eastern province granitoids, and their relationship with contemporaneous volcanics, confirm their I-type nature. The bulk liquid lines of descent of both granitic provinces largely overlap with one another. Sr-Nd isotopic data further demonstrate that the Malaysian granitoids, especially those of the Main Range, were hybridized melts derived from two "end-member" source regions, one of which is isotopically similar to the Kontum orthoamphibolites and the other akin to the Kontum paragneisses of the Indochina block. However, there are differences in the source rocks for the two provinces, and it is suggested in this paper that these are related to differing proportions of igneous and sedimentary protoliths. The incorporation of sedimentary-sourced melts in the Eastern province is insignificant, which allowed the granites in this belt to maintain their I-type nature. The presence of minor primary tin mineralization in the Eastern province compared to the much more significant tin endowment in the Main Range is considered to reflect the incorporation of a smaller proportion of sedimentary protolith in the melt products of the former.</p
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