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21.
Asbj?rn Torvanger Alv-Arne Grimstad Erik Lindeberg Nathan Rive Kristin Rypdal Ragnhild Bieltvedt Skeie Jan Fuglestvedt Petter Tollefsen 《Climatic change》2012,114(2):245-260
We explore allowable leakage for carbon capture and geological storage to be consistent with maximum global warming targets of 2.5 and 3 °C by 2100. Given plausible fossil fuel use and carbon capture and storage scenarios, and based on modeling of time-dependent leakage of CO2, we employ a climate model to calculate the long-term temperature response of CO2 emissions. We assume that half of the stored CO2 is permanently trapped by fast mechanisms. If 40?% of global CO2 emissions are stored in the second half of this century, the temperature effect of escaped CO2 is too small to compromise a 2.5 °C target. If 80?% of CO2 is captured, escaped CO2 must peak 300?years or later for consistency with this climate target. Due to much more CO2 stored for the 3 than the 2.5 °C target, quality of storage becomes more important. Thus for the 3 °C target escaped CO2 must peak 400?years or later in the 40?% scenario, and 3000?years or later in the 80?% scenario. Consequently CO2 escaped from geological storage can compromise the less stringent 3 °C target in the long-run if most of global CO2 emissions have been stored. If less CO2 is stored only a very high escape scenario can compromise the more stringent 2.5 °C target. For the two remaining combinations of storage scenarios and climate targets, leakage must be high to compromise these climate targets. 相似文献
22.
Steven Goderis Elin Kalleson Roald Tagle Henning Dypvik Ralf-Thomas Schmitt Jörg Erzinger Philippe Claeys 《Chemical Geology》2009,258(3-4):145-156
The goal of this study is to identify the type of projectile responsible for the formation of the late Precambrian Gardnos impact structure in Norway. Fifteen impactite samples, predominantly impact breccias and suevites from the central and northeastern part of the structure, were analyzed for platinum group elements (PGE) and Au using nickel-sulfide fire assay combined with inductively coupled plasma mass spectrometry (ICP-MS). Major and trace elements were measured in the same samples using X-ray fluorescence (XRF). In addition, the concentrations of siderophile elements Ni, Cr, and Co were determined by ICP-MS after acid digestion. The samples collected at the contact between suevite and the sedimentary infill yielded the highest PGE concentrations (Ir = 1.926 ng/g, Ru = 3.494 ng/g, Pt = 4.716 ng/g, Rh = 0.766 ng/g, Pd = 2.842 ng/g for GC6). The CI-normalized PGE patterns are characterized by Ru and Rh enrichments suggesting a non-chondritic impactor. Concentration plots of the different PGE display an excellent correlation (R > 0.99), indicative of a single source for the PGE enrichment. The Ni/Cr ratio of the Gardnos impactor (2.56 ± 0.20) agrees with that of chondrites (2 to 7), whereas Ir is depleted relative to Ni in this projectile (Ni/Ir ratio of 92 000 ± 8000 compared to an average Ni/Ir ratio of 23 150 ± 4250 for chondrites). There is no clear indication of selective post-depositional remobilization of the characteristic highly siderophile elements. The Ni/Ir and Cr/Ir data combined with the non-chondritic PGE ratios probably indicate a differentiated projectile. Based on (1) the similarity of the inter-element ratios of the impactor with the iron phase of non-magmatic iron meteorites and (2) the presence of characteristics of both chondrites and iron meteorites (Ni/Cr and Ni/Ir ratios), an IA or IIIC non-magmatic iron meteorite is a very plausible impactor. 相似文献
23.
Karin Holmgren Jan Risberg Johan Freudendahl Mussa Achimo Anneli Ekblom Joao Mugabe Elin Norstr?m Sandra Sitoe 《Journal of Paleolimnology》2012,48(2):311-322
Stratigraphic variations in diatom composition and phytolith abundance in a sediment core from a small, hydrologically isolated waterbody, Lake Nhauhache, Mozambique, provide evidence of water-level fluctuations over the past ~2,300?years. Ten AMS radiocarbon dates on bulk sediment samples show that the lake came into existence about 2,300?years ago and that it has dried out since then, but only for brief time periods. Changes in the diatom assemblage composition indicate that lake level fluctuated in response to shifting humidity conditions. The changes reflect wetter conditions ca. 300 BC?CAD 800, more variable conditions between AD 800 and 1150, a distinct dry phase within the time span AD 1150?C1700 and a return thereafter to more humid conditions until present. There is general agreement between the Lake Nhauhache record and other records from the Southern Hemisphere summer rainfall region. This suggests that sediments from small interdunal lakes, which are abundant along the coast of southern Africa, provide reliable, regional paleoenvironmental information about an area from which more such data are needed. 相似文献
24.
Rigid sliding block analysis is a common analytical procedure used to predict the potential for earthquake-induced landslides
for natural slopes. Currently, predictive models provide the expected level of displacement as a function of the characteristics
of the slope (e.g., geometry, strength, yield acceleration) and the characteristics of earthquake shaking (e.g., peak ground
acceleration, peak ground velocity). These predictive models are used for developing seismic landslide hazard maps which identify
zones with risk of earthquake-induced landslides. Alternatively, these models can be combined with Shakemaps to generate “near-real-time”
Slidemaps which could be used, among others, as a tool in disaster management. Shakemaps (a publicly available free service
of the United States Geological Survey, USGS) provide near-real-time ground motion conditions during the time of an earthquake
event. The ground motion parameters provided by a Shakemap are very useful for the development of Slidemaps. By providing
ground motion parameters from an actual earthquake event, Shakemaps also serve as a tool to decouple the uncertainty of the
ground motion in sliding displacements prediction. Campania region in Italy is studied for assessing the applicability of
using Shakemaps for regional landslide-risk assessment. This region is selected based on the availability of soil shear strength
parameters and the proximity to the 1980 Irpina (M
w
= 6.9) Earthquake. 相似文献
25.
Adaptation to climate change impacts on urban storm water: a case study in Arvika, Sweden 总被引：1，自引：0，他引：1
Jonas Olsson Hideo Amaguchi Elin Alsterhag Maria Dåverhög Per-Erik Adrian Akira Kawamura 《Climatic change》2013,116(2):231-247
Already today, the functionality of many sewer and storm water systems are not up to the required standards and consequently flooding problems are experienced in case of heavy storms. System upgrades are required, which are however complicated by the expected future increase in short-term rainfall intensities as a result of climate change. In this case study, focusing on the town of Arvika, Sweden, this issue is investigated in three main steps. In the first, extreme value analyses of 30-min rainfall from an ensemble of climate projections are carried out to estimate the future increase and generate a future design storm. In the second, the existing system’s response to both today’s and future design storms are simulated by a coarse sewer model setup (MOUSE) and a detailed coupled surface-sewer model setup (TSR). In the third and final step, system upgrades are designed and evaluated by both models. The results indicate an increase by 10–30 % of today’s short-term rainfall extremes by the end of the century. Upgrading the system to achieve a satisfactory performance for the future design storm would cost approximately twice as much as an upgrade based on today’s design storm. 相似文献
26.
E.?RantaEmail author G.?Stockmann T.?Wagner T.?Fusswinkel E.?Sturkell E.?Tollefsen A.?Skelton 《Contributions to Mineralogy and Petrology》2018,173(10):78
Petrogenetic studies of carbonatites are challenging, because carbonatite mineral assemblages and mineral chemistry typically reflect both variable pressure–temperature conditions during crystallization and fluid–rock interaction caused by magmatic–hydrothermal fluids. However, this complexity results in recognizable alteration textures and trace-element signatures in the mineral archive that can be used to reconstruct the magmatic evolution and fluid–rock interaction history of carbonatites. We present new LA–ICP–MS trace-element data for magnetite, calcite, siderite, and ankerite–dolomite–kutnohorite from the iron-rich carbonatites of the 1.3 Ga Grønnedal–Íka alkaline complex, Southwest Greenland. We use these data, in combination with detailed cathodoluminescence imaging, to identify magmatic and secondary geochemical fingerprints preserved in these minerals. The chemical and textural gradients show that a 55 m-thick basaltic dike that crosscuts the carbonatite intrusion has acted as the pathway for hydrothermal fluids enriched in F and CO2, which have caused mobilization of the LREEs, Nb, Ta, Ba, Sr, Mn, and P. These fluids reacted with and altered the composition of the surrounding carbonatites up to a distance of 40 m from the dike contact and caused formation of magnetite through oxidation of siderite. Our results can be used for discrimination between primary magmatic minerals and later alteration-related assemblages in carbonatites in general, which can lead to a better understanding of how these rare rocks are formed. Our data provide evidence that siderite-bearing ferrocarbonatites can form during late stages of calciocarbonatitic magma evolution. 相似文献
27.
Elin Enfors 《Global Environmental Change》2013,23(1):51-60
Recent efforts to achieve a much needed productivity increase in farming systems across semi-arid and dry sub-humid sub-Saharan Africa have highlighted the potential of small-scale water system innovations (SWSIs). This paper takes a social–ecological resilience approach to investigate how this type of water management technology would influence agro-ecosystem dynamics, using a catchment in northeastern Tanzania as an example. The analysis finds that three external drivers (increasing dryspell frequency, population growth, and institutional changes) have interacted with a set of key variables in the studied system to shape a development trajectory over the past half-century where off-farm ecosystem services are being degraded while agricultural yields remain low and people remain poor. The analysis further finds that the evaluated SWSIs have the potential to destabilize feedbacks maintaining this social–ecological trap through several different mechanisms, and thereby open up for new development trajectories. A concluding discussion identifies a number of challenges to this type of transformation in sub-Saharan Africa, and outlines the type of investment approaches that would be needed to go from potential to reality. 相似文献
28.
Elin Almroth Anders Tengberg Johan H. Andersson Svetlana Pakhomova Per O.J. Hall 《Continental Shelf Research》2009,29(5-6):807-818
The effect of resuspension on benthic fluxes of oxygen (O2), ammonium (NH4+), nitrate (NO3?), phosphate (PO43?), silicate (Si(OH)4), dissolved inorganic carbon (DIC), total dissolved iron (Fe) and total dissolved manganese (Mn) was studied at three different stations in the Gulf of Finland (GoF), Baltic Sea during three cruises in June–July 2003, September 2004 and May 2005. The stations were situated on different bottom types in the western, central and eastern part, respectively, of the open GoF. The fluxes were measured in-situ using the autonomous Göteborg benthic lander. To simulate resuspension events, the stirring speed was increased in two of the four chambers of the lander after approximately half of the incubation time. The other two chambers were used as control chambers. Clear effects of resuspension were observed on the oxygen fluxes where an increase of the consumption was observed in 88% of the cases and on average with 59% (stdev=53). The NH4+ fluxes were affected in 50% of the cases (4 out of 8 incubations) at stations with low bottom water oxygen concentrations, but in no cases where the bottom water was oxygenated (0 out of 9 incubations). The NH4+ fluxes decreased by 26±27% in 2005 and by 114±19% in 2003. There was no clear effect of resuspension on the fluxes of any of the other solutes in this study. Thus, resuspension events did not play a significant role in release/uptake of NO3?, PO43?, Si(OH)4, DIC, Fe and Mn in GoF sediments. However, increased oxygen consumption as a result of resuspension may lead to spreading of anoxic/suboxic bottom water conditions, and thus indirectly to increased benthic release of phosphate, ammonium and iron. 相似文献
29.
Lena Viktorsson Elin Almroth-Rosell Anders Tengberg Roman Vankevich Ivan Neelov Alexey Isaev Victor Kravtsov Per O. J. Hall 《Aquatic Geochemistry》2012,18(6):543-564
Benthic fluxes of soluble reactive phosphorus (SRP) and dissolved inorganic carbon (DIC) were measured in situ using autonomous landers in the Gulf of Finland in the Baltic Sea, on four expeditions between 2002 and 2005. These measurements together with model estimates of bottom water oxygen conditions were used to compute the magnitude of the yearly integrated benthic SRP flux (also called internal phosphorus load). The yearly integrated benthic SRP flux was found to be almost 10 times larger than the external (river and land sources) phosphorus load. The average SRP flux was 1.25?±?0.56?mmol?m?2?d?1 on anoxic bottoms, and ?0.01?±?0.08?mmol?m?2?d?1 on oxic bottoms. The bottom water oxygen conditions determined whether the SRP flux was in a high or low regime, and degradation of organic matter (as estimated from benthic DIC fluxes) correlated positively with SRP fluxes on anoxic bottoms. From this correlation, we estimated a potential increase in phosphorus flux of 0.69?±?0.26?mmol?m?2?d?1 from presently oxic bottoms, if they would turn anoxic. An almost full annual data set of in situ bottom water oxygen measurements showed high variability of oxygen concentration. Because of this, an estimate of the time which the sediments were exposed to oxygenated overlying bottom water was computed using a coupled thermohydrodynamic ocean?Csea and ecosystem model. Total phosphorus burial rates were calculated from vertical profiles of total phosphorus in sediment and sediment accumulation rates. Recycling and burial efficiencies for phosphorus of 97 and 3%, respectively, were estimated for anoxic accumulation bottoms from a benthic mass balance, which was based on the measured effluxes and burial rates. 相似文献
30.
Fieldwork has long been fundamental to human geography; however, increasingly unreceptive institutional environments have led to a decline in fieldwork in undergraduate human geography programs. We argue that mobility research presents an opportunity to reinvigorate the undergraduate field trip in human geography. We report on a second-year field course to Noosa, Australia, that blends new technologies with conventional survey techniques to capture data on a spectrum of human spatial behaviour. Over the course of a single weekend, students collect GPS traces of tourist mobility, survey businesses on the journey to work, collect residential migration histories and trace population dynamics on Noosa beach. Over the three years the course has been running, students have constructed a large repository of data on this Australian mobility hotspot, of which we report highlights. Results from standardised student course evaluations confirm the pedagogical value of these initiatives for human geography undergraduates. 相似文献