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The potential for global forest cover The restoration of forested land at a global scale could help capture atmospheric carbon and mitigate climate change. Bastin et al. used direct measurements of forest cover to generate a model of forest restoration potential across the globe (see the Perspective by Chazdon and Brancalion). Their spatially explicit maps show how much additional tree cover could exist outside of existing forests and agricultural and urban land. Ecosystems could support an additional 0.9 billion hectares of continuous forest. This would represent a greater than 25% increase in forested area, including more than 200 gigatonnes of additional carbon at maturity.Such a change has the potential to store an equivalent of 25% of the current atmospheric carbon pool. Science , this issue p. 76 ; see also p. 24

AbstractWe have investigated the spectroscopic properties (absorption spectra, emission spectra, emission lifetimes) of three triads in CH2Cl2: C2‐M‐C2, C343‐M‐C343, and C2‐M‐C343, in which M is a shape‐persistent macrocyclic hexagonal backbone composed of two 2,2′‐bipyridine (bpy) units embedded in opposing sides, and C2 and C343 are coumarin 2 and coumarin 343, respectively. All the components are strongly fluorescent species (Φ=0.90, 0.79, and 0.93 for M, C2, and C343, respectively, as established by investigating suitable model compounds). In each triad excitation of M leads to almost quantitative energy transfer to the lowest coumarin‐localised excited state. Upon addition of acid, the two bpy units of the M component undergo independent protonation leading to monoprotonated (e.g., C2‐M⋅H+‐C2) and diprotonated (e.g., C2‐M⋅2 H+‐C2) species. Further addition of acid leads to protonation of the coumarin component so that each triad is involved in four protonation equilibria. Protonation causes strong (and reversible, upon addition of base) changes in the absorption and fluorescence properties of the triads because of inversion of the excited‐state order and/or the occurrence of electron‐transfer quenching processes.

AbstractLand Surface Phenology (LSP) is the most direct representation of intra‐annual dynamics of vegetated land surfaces as observed from satellite imagery. LSP plays a key role in characterizing land‐surface fluxes, and is central to accurately parameterizing terrestrial biosphere–atmosphere interactions, as well as climate models. In this article, we present an evaluation of Pan‐European LSP and its changes over the past 30 years, using the longest continuous record of Normalized Difference Vegetation Index (NDVI) available to date in combination with a landscape‐based aggregation scheme. We used indicators of Start‐Of‐Season, End‐Of‐Season and Growing Season Length (SOS, EOS and GSL, respectively) for the period 1982–2011 to test for temporal trends in activity of terrestrial vegetation and their spatial distribution. We aggregated pixels into ecologically representative spatial units using the European Landscape Classification (LANMAP) and assessed the relative contribution of spring and autumn phenology. GSL increased significantly by 18–24 days decade−1 over 18–30% of the land area of Europe, depending on methodology. This trend varied extensively within and between climatic zones and landscape classes. The areas of greatest growing‐season lengthening were the Continental and Boreal zones, with hotspots concentrated in southern Fennoscandia, Western Russia and pockets of continental Europe. For the Atlantic and Steppic zones, we found an average shortening of the growing season with hotspots in Western France, the Po valley, and around the Caspian Sea. In many zones, changes in the NDVI‐derived end‐of‐season contributed more to the GSL trend than changes in spring green‐up, resulting in asymmetric trends. This underlines the importance of investigating senescence and its underlying processes more closely as a driver of LSP and global change.

AbstractWe report the design, synthesis and evaluation of dynamic “octopus” amphiphiles with emphasis on their efficiency as activators in synthetic membrane‐based sensing systems. Previously, we found that the in situ treatment of charged hydrazides with hydrophobic aldehydes or ketones gives amphiphilic counterion activators of polyion transporters in lipid bilayers, and that their efficiency increases with the number of their hydrophobic tails. Herein, we expand this series to amphiphiles with one cationic head (guanidinium or ammonium) and four exchangeable hydrophobic tails. These results, with the highest number of tails reported to date, confirm that dynamic octopus amphiphiles provide access to maximal activity and selectivity. Odorants, such as muscone, carvone, or anisaldehyde are used to outline their usefulness in differential sensing systems that operate based on counterion‐activated DNA transporters in fluorogenic vesicles. The enhanced ability of octopus amphiphiles to enable the discrimination of enantiomers as well as that of otherwise intractable ortho, meta, and para isomers and short cyclo‐/alkyl tails is demonstrated. These findings identify dynamic octopus amphiphiles as being promising for application to differential sensing, “fragrant” cellular uptake, and slow release.

Abstract This study considers effects of pressure of up to 110 kbar on line position and fluorescence lifetime τ for 4 T 1 → 6 A 1 transition in LMA:Mn 2+ and LMA:Mn 2+ , Nd 3+ . Energy transfer between Mn 2+ and Nd 3+ in LMA:Mn 2+ , Nd 3+ has also been considered. Results indicate pressure induced line shift towards longer wavelengths, a red-shift in both crystals with the same rate of 0.182 nm kbar −1 . Pressure influences fluorescence lifetime τ in the considered crystals differently; whereas for LMA:Mn 2+ increasing pressure causes slow linear decrease of τ , and for LMA:Mn 2+ , Nd 3+ τ increases linearly as pressure raises. Energy transfer efficiencies decrease with pressure. High pressure induced red-shift can be explained by a simple model.

Abstract Geodiversity and geoheritage studies are multidisciplinary, drawing from all sides of geosciences and extending them into the humanities, geoarchaeology, spatial planning, territorial and risk management, economics, tourism, or culture using integrated and interdisciplinary research approaches. During the last three decades, geodiversity and geoheritage research experienced a considerable growth that confirms both scientific and public relevance of these topics. In this introductory text, a brief review of current literature is presented and the importance of geodiversity and geoheritage for sustainable development, geohazard resilience and associated themes is discussed. Last, but not least, the aims and structure of this volume are outlined.

Abstract Thermal cross-linking in presence of residual solvent dimethylsulfoxide without any addition of cross-linker molecules is described. This elegant method increases spectacularly the mechanical and hydrolytic stability of sulfonated aromatic polymers (SAP), making them suitable for use in liquid water also at 145 °C. Data on water uptake, mechanical properties and proton conductivity are presented and discussed from a bond energy point of view. The developed method is also inexpensive, being incorporated in the normal membrane casting procedure. This opens new horizons and hitherto conventionally disregarded SAP membranes should be reconsidered as fuel cell membranes.

This study assesses the environmental impact of polyethylene terephthalate (PET) bottle-to-fibre recycling using the methodology of life-cycle assessment (LCA). Four recycling cases, including mechanical recycling, semi-mechanical recycling, back-to-oligomer recycling and back-to-monomer recycling were analysed. Three allocation methods are applied for open-loop recycling, i.e. the “cut-off” approach, the “waste valuation” approach and the “system expansion” approach. Nine environmental impact indicators were analysed, i.e. non-renewable energy use (NREU), global warming potential (GWP), abiotic depletion, acidification, eutrophication, human toxicity, fresh water aquatic ecotoxicity, terrestrial ecotoxicity and photochemical oxidant formation. The LCA results are compared with virgin PET fibre and other commodity fibre products, i.e. cotton, viscose, PP (polypropylene) and PLA (polylactic acid). The LCA results show that recycled PET fibres offer important environmental benefits over virgin PET fibre. Depending on the allocation methods applied for open-loop-recycling, NREU savings of 40–85% and GWP savings of 25–75% can be achieved. Recycled PET fibres produced by mechanical recycling cause lower environmental impacts than virgin PET in at least eight out of a total of nine categories. Recycled fibres produced from chemical recycling allow to reduce impacts in six to seven out of a total of nine categories compared to virgin PET fibres. Note that while mechanical recycling has a better environmental profile than chemical recycling, chemically recycled fibres can be applied in a wider range of applications than mechanically recycled fibres.

The future trajectory of greenhouse gas concentrations depends on interactions between climate and the biogeosphere. Thawing of Arctic permafrost could release significant amounts of carbon into the atmosphere in this century. Ancient Ice Complex deposits outcropping along the ~7,000-kilometre-long coastline of the East Siberian Arctic Shelf (ESAS), and associated shallow subsea permafrost, are two large pools of permafrost carbon, yet their vulnerabilities towards thawing and decomposition are largely unknown. Recent Arctic warming is stronger than has been predicted by several degrees, and is particularly pronounced over the coastal ESAS region. There is thus a pressing need to improve our understanding of the links between permafrost carbon and climate in this relatively inaccessible region. Here we show that extensive release of carbon from these Ice Complex deposits dominates (57 ± 2 per cent) the sedimentary carbon budget of the ESAS, the world’s largest continental shelf, overwhelming the marine and topsoil terrestrial components. Inverse modelling of the dual-carbon isotope composition of organic carbon accumulating in ESAS surface sediments, using Monte Carlo simulations to account for uncertainties, suggests that 44 ± 10 teragrams of old carbon is activated annually from Ice Complex permafrost, an order of magnitude more than has been suggested by previous studies. We estimate that about two-thirds (66 ± 16 per cent) of this old carbon escapes to the atmosphere as carbon dioxide, with the remainder being re-buried in shelf sediments. Thermal collapse and erosion of these carbon-rich Pleistocene coastline and seafloor deposits may accelerate with Arctic amplification of climate warming.

AbstractWe report on the synthesis, optical properties and energy‐transfer features of a series of transition‐metal‐containing complexes and dyads, based on a pre‐organised truxene scaffold. In this series, the [Ru(bpy)3]2+ and [Os(bpy)3]2+ photoactive terminals are coupled to the bridging aromatic truxene core through rigid ethynyl linkers. The photoinduced energy‐transfer processes taking place from the Ru‐ to the Os‐based levels, and from the truxene bridging ligand to the terminal‐metal chromophores are studied and the pathways and mechanisms are discussed. The photoinduced energy‐transfer process observed in the dyad proceeds rapidly through: i) an efficient 1L→1Os direct energy transfer followed by intersystem crossing to 3Os, and ii) a fast 1L→1Ru energy‐transfer step and subsequent intersystem crossing to 3Ru followed by a 3Ru→3Os energy‐transfer process. The first 1L→1Os and 1L→1Ru steps are controlled by a dipole–dipole interaction (Förster mechanism), whereas the subsequent 3Ru→3Os step proceeds by means of a long‐range (≈24 Å) through‐bond mediated Dexter mechanism, facilitated by the conjugation along the bpy‐truxene‐bpy molecular axis.