A review of the processes and effects of droughts and summer floods in rivers and threats due to climate change on current adaptive strategies

Europe is expected to experience a greater frequency of floods and droughts as precipitation and evapotranspiration patterns are modified by climate change in future. Several large scale drought and flooding events have occurred in Europe since 2000. Studies of drought are rare but indicate important impacts on freshwater habitats, water quality, plants and animals, which may have wider consequences for ecosystem functioning. The main factors determining the impacts of droughts and floods are event duration and seasonality of the event. A diverse habitat distribution and the presence of refugia at the reach scale confer the most resilience against droughts and floods. Management measures will also be impacted particularly with regard to riparian zones, channel morphology, flow and floodplain connectivity. However there is a conflict between management actions that target the effects of drought, and those that target floods. This report reviews information on droughts and aseasonal floods (summer floods) published since 2000 with a principal focus on small lowland rivers. Using several recent (post 2000) reviews on these topics, we describe abiotic and biotic effects of droughts and floods, providing recent European examples where possible. We explain the current status of droughts and summer floods in Europe, and where the main sources of data can be found. We highlight the threats posed by these phenomena to some of the most common current adaptive management strategies in place in the EU. To this end we use measures already described within REFRESH under Deliverables 1.1 and 1.2, and we focused solely on adaptive measures relating to riparian zones, channel morphology, flow and floodplain connectivity

Bohr Density of Simple Linear Group Orbits

We show that any non-zero orbit under a non-compact, simple, irreducible linear group is dense in the Bohr compactification of the ambient space

Lithium-6 : Evolution from Big Bang to Present

The primordial abundances of Deuterium, he4, and li7 are crucial to determination of the baryon density of the Universe in the framework of standard Big Bang nucleosynthesis (BBN). li6 which is only produced in tiny quantities and it is generally not considered to be a cosmological probe. However, recent major observational advances have produced an estimate of the li6/li7 ratio in a few very old stars in the galactic halo which impacts the question whether or not the lithium isotopes are depleted in the outer layers of halo stars, through proton induced reactions at the base of (or below) the convective zone. li6 is a pure product of spallation through the major production reactions, fast oxygen and alphas interacting on interstellar H, He (especially in the early Galaxy). The rapid nuclei are both synthesized and accelerated by SN II. In this context, the \li6 evolution should go in step with that of beryllium and boron, recently observed by the Keck and HST telescopes. Li6 adds a new constraint on the early spallation in the Galaxy. In particular, if confirmed, the Li6/Be9 ratio observed in two halo stars (HD 84937, BD +263578) gives strong boundary conditions on the composition and the spectrum of the rapid particles involved. We show that Li6 is essentially intact in halo stars, and a fortiori \li7. We can define a range of the Li6 abundance in the very early Galaxy consistent with Big Bang nucleosynthesis (5.6 10(-14) to 3. 10(-13) . Following the evolution at increasing metallicity, we explain the abundance in the solar system within a factor of about 2.Comment: 16 pages, 4 figure

Biogeochemical cycling of polybrominated diphenyl ethers (PBDEs) in the Strait of Georgia

The temporal and spatial distribution of dissolved and particulate PBDEs seawater concentration has been monitored in the Strait of Georgia (SoG) since 2013. We aim to determine the sources, sinks and biogeochemical cycling of PBDE congeners in the water column in SoG. Particulate PBDEs concentrations show high temporal and spatial variability, indicating that the outfalls from the waste water treatment plants are major point sources. Changes in congener distributions in relation to total particulate PBDE concentrations suggest that the less brominated congeners desorb from sewage particles and add to the dissolved PBDEs pool more rapidly than the more brominated congeners. We also measured very low particulate PBDE concentrations during phytoplankton blooms, which suggest slow kinetics of adsorption or uptake of dissolved PBDEs by phytoplankton. In contrast, the concentrations of dissolved PBDEs in the SoG are more uniform and indicate that the outfalls from waste water treatment plants are not major direct point sources. Other potential sources include atmospheric deposition and desorption from effluent particles after their dispersion. A depth profile of dissolved PBDEs shows higher concentrations of the BDE-47, 99 and 153 at the surface, indicating contributions from the atmosphere or from the Fraser River. However, their highest concentrations were found at, or above, the buoyancy depth of the outfall plume from the Iona Waste Water Treatment Plant. Results obtained to date suggest a differential partitioning of PBDE congeners after their discharge from waste water treatment plants. Less brominated congeners are preferentially desorbed from sewage particles and are preferentially transported towards the surface by the estuarine circulation of the SoG, while the more brominated congeners predominantly remain associated with particles and accumulate on the seafloor. This working hypothesis will be further tested by measuring the kinetics of adsorption/desorption of PBDEs on phytoplankton and sewage particles using C-14 labelled PBDE congeners

Export fluxes of calcite in the eastern equatorial Pacific from the Last Glacial Maximum to present

Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 19 (2004): PA2018, doi:10.1029/2003PA000986.The eastern equatorial Pacific (EEP) is an important center of biological productivity, generating significant organic carbon and calcite fluxes to the deep ocean. We reconstructed paleocalcite flux for the past 30,000 years in four cores collected beneath the equatorial upwelling and the South Equatorial Current (SEC) by measuring ex230Th-normalized calcite accumulation rates corrected for dissolution with a newly developed proxy for “fraction of calcite preserved.” This method produced very similar results at the four sites and revealed that the export flux of calcite was 30–50% lower during the LGM compared to the Holocene. The internal consistency of these results supports our interpretation, which is also in agreement with emerging data indicating lower glacial productivity in the EEP, possibly as a result of lower nutrient supply from the southern ocean via the Equatorial Undercurrent. However, these findings contradict previous interpretations based on mass accumulation rates (MAR) of biogenic material in the sediment of the EEP, which have been taken as reflecting higher glacial productivity due to stronger wind-driven upwelling.This research was partly supported by NSF grant OCE-0095617 and funds from the Northern Illinois University Graduate School (Loubere); the NASA Michigan Space Grant Consortium Seed Grant for summer, 2001 for 230Th analyses at WHOI (Mekik); the French Ministere de l’Education Nationale, de la Recherche et de la Technologie, and a EURODOC grant from the Region Rhone-Alpes (Pichat)

用FDI 存量衡量国外子公司经营活动存在偏差

研究人员经常将母国在东道国的子公司创造的增加值（VA）称作外国直接投资（FDI）， 并使用国际收支平衡表中的FDI流量和存量进行度量。实际上FDI记录的是国内公司和国外公司之间的长期金融交易，因此FDI存量和流量衡量的范围较窄。例如，法国对澳大利亚的FDI存量，是衡量法国母公司拥有的在澳大利亚的子公司的股份和再投资收益，以及在澳大利亚的子公司对法国母公司的净负债

Strengthening of the Northeast Monsoon over the Flores Sea, Indonesia, at the time of Heinrich event 1

Paleoclimate evidence from South America and Asia has been interpreted to indicate that tropical rainfall migrated southward during the Northern Hemisphere cooling associated with Heinrich stadial 1 (HS1), an event of massive iceberg discharge to the North Atlantic ca. 18–15 ka. Although arid conditions associated with such a shift are well documented in southern Asia, as far south as Borneo, debate still exists regarding the precipitation response in southern Indonesia and Australia during HS1. This study utilizes concentrations of the long-lived nuclide 232Th as a proxy for detrital riverine input and 230Th normalization to estimate the history of preserved fluxes reaching the seafloor in the Flores Sea, located between southern Sulawesi and the Lesser Sunda Islands, Indonesia. Because the only source of 232Th to the ocean is continental minerals, this proxy is a robust indicator of continental weathering. The 230Th normalized burial fluxes of lithogenic and biogenic matter demonstrate that both detrital and biogenic fluxes in the Flores Sea were higher during HS1 than any other period in the past 22 k.y. High detrital fluxes indicate enhanced precipitation runoff from surrounding landmasses during a period of maximum southward shift of the Intertropical Convergence Zone. This study further constrains the northern limit of enhanced rainfall associated with a southward shift of Australian monsoon-related rainfall at the time of HS1 and highlights the value of 232Th as a proxy of continental input to deep-sea sediment records

Do tests devised to detect recent HIV-1 infection provide reliable estimates of incidence in Africa?

International audienceThe objective of this study was to assess the performance of 4 biologic tests designed to detect recent HIV-1 infections in estimating incidence in West Africa (BED, Vironostika, Avidity, and IDE-V3). These tests were assessed on a panel of 135 samples from 79 HIV-1-positive regular blood donors from Abidjan, C?d'Ivoire, whose date of seroconversion was known (Agence Nationale de Recherches sur le SIDA et les H?tites Virales 1220 cohort). The 135 samples included 26 from recently infected patients (180 days), and 15 from patients with clinical AIDS. The performance of each assay in estimating HIV incidence was assessed through simulations. The modified commercial assays gave the best results for sensitivity (100% for both), and the IDE-V3 technique gave the best result for specificity (96.3%). In a context like Abidjan, with a 10% HIV-1 prevalence associated with a 1% annual incidence, the estimated test-specific annual incidence rates would be 1.2% (IDE-V3), 5.5% (Vironostika), 6.2% (BED), and 11.2% (Avidity). Most of the specimens falsely classified as incident cases were from patients infected for >180 days but <1 year. The authors conclude that none of the 4 methods could currently be used to estimate HIV-1 incidence routinely in C?d'Ivoire but that further adaptations might enhance their accuracy