What do near-term observations tell us about long-term developments in greenhouse gas emissions?     

Detlef P. van Vuuren  Jae Edmonds  Steven J. Smith  Kate V. Calvin  Joseph Karas  Mikiko Kainuma  Nebojsa Nakicenovic  Keywan Riahi  Bas J. van Ruijven  Rob Swart  Allison Thomson 《Climatic change》2010,103(3-4):635-642

Long-term scenarios developed by integrated assessment models are used in climate research to provide an indication of plausible long-term emissions of greenhouse gases and other radiatively active substances based on developments in the global energy system, land-use and the emissions associated with these systems. The phenomena that determine these long-term developments (several decades or even centuries) are very different than those that operate on a shorter time-scales (a few years). Nevertheless, in the literature, we still often find direct comparisons between short-term observations and long-term developments that do not take into account the differing dynamics over these time scales. In this letter, we discuss some of the differences between the factors that operate in the short term and those that operate in the long term. We use long-term historical emissions trends to show that short-term observations are very poor indicators of long-term future emissions developments. Based on this, we conclude that the performance of long-term scenarios should be evaluated against the appropriate, corresponding long-term variables and trends. The research community may facilitate this by developing appropriate data sets and protocols that can be used to test the performance of long-term scenarios and the models that produce them.  相似文献   

The comparability of carbonatitic fluid inclusions in ijolites with natrocarbonatite lava     

M. J. Le Bas  J. A. Aspden 《Bulletin of Volcanology》1981,44(3):429-438

The composition of carbonate, sulphate, halide and other phases trapped as fluid inclusions in apatite crystals in ijolite and urtite from sub-volcanic complexes in East Africa have been determined using the electron micro-probe. The bulk composition of these inclusions is alkali-rich and closely comparable to the natrocarbonatite lava from the active volcano of Oldoinyo Lengai in N. Tanzania. The inclusions are interpreted as having been originally immiscible alkali carbonate-rich droplets within a nephelinitic melt. The evidence suggests that magma of the composition of natrocarbonatite lava is that most likely for the parent magma during carbonatite petrogenesis.  相似文献   

Sr and Pb isotopic composition of five USGS glasses (BHVO-2G, BIR-1G, BCR-2G, TB-1G, NKT-1G)   总被引：2，自引：0，他引：2  

Marlina Elburg  Pieter Vroon  Bas van der Wagt  Arnaud Tchalikian 《Chemical Geology》2005,223(4):196-207

Sr isotopic compositions and Rb / Sr ratios of three USGS glasses (BHVO-2G, BIR-1G, BCR-2G) are identical to those of the original USGS reference materials. NKT-1G and TB-1G give values of 0.70351 and 0.70558, respectively. Pb isotopic ratios were measured by the standard-sample bracketing technique on an MC-ICP-MS, which give results that are comparable in accuracy and reproducibility to double spike analyses. However, assessment of the reproducibility of the technique is hampered by inhomogeneous contamination of all USGS reference materials analysed. This contamination is likely to be the reason why the USGS glasses do not all have the same Pb isotopic composition as their unfused originals. Powdered glasses, distributed for characterisation of the glasses by bulk analytical techniques, do not all have the same Pb isotopic compositions as the solid glass material, and can therefore not be used for this purpose.  相似文献   

Modeling large-scale cohesive sediment transport affected by small-scale biological activity     

Bas W. Borsje  Mindert B. de Vries  Suzanne J.M.H. Hulscher  G.J. de Boer 《Estuarine, Coastal and Shelf Science》2008

Biological activity on the bottom of the seabed is known to have significant influence on the dynamics of cohesive sediment on a small spatial and temporal scale. In this study, we aim to understand the large-scale effects of small-scale biological activity. Hereto, effects of biology are quantitatively incorporated into the process-based sediment transport module of Delft3D. This Bio-mud model is used to study cohesive sediment transport and deposition patterns in the Western Wadden Sea for a period of 1 year to capture seasonal changes.  相似文献   

Groundwater chemistry of Al under Dutch sandy soils: Effects of land use and depth     

Ellen P.M.J. Fest  Erwin J.M. Temminghoff  Jasper Griffioen  Bas Van Der Grift  Willem H. Van Riemsdijk 《Applied Geochemistry》2007

Aluminium has received great attention in the second half of the 20th century, mainly in the context of the acid rain problem mostly in forest soils. In this research the effect of land use and depth of the groundwater on Al, pH and DOC concentration in groundwater under Dutch sandy soils has been studied. Both pH and DOC concentration play a major role in the speciation of Al in solution. Furthermore, the equilibrium with mineral phases like gibbsite, amorphous Al(OH)₃ and imogolite, has been considered. Agricultural and natural land use were expected to have different effects on the pH and DOC concentration, which in turn could influence the total Al concentration and the speciation of Al in groundwater at different depths (phreatic, shallow and deep). An extensive dataset (n = 2181) from the national and some provincial monitoring networks on soil and groundwater quality was used. Land use type and groundwater depth did influence the pH, and Al and DOC concentrations in groundwater samples. The Al concentration ranged from <0.4 μmol L⁻¹ at pH > 7 to 1941 μmol L⁻¹ at pH < 4; highest Al concentrations were found for natural-phreatic groundwater. The DOC concentration decreased and the median pH increased with depth of the groundwater. Natural-phreatic groundwater showed lower pH than the agricultural-phreatic groundwater. Highest DOC concentrations were found for the agricultural-phreatic groundwater, induced by the application of organic fertilizers. Besides inorganic complexation, the NICA-Donnan model was used to calculate Al³⁺ concentrations for complexation with DOC. Below pH 4.5 groundwater samples were mainly in disequilibrium with a mineral phase. This disequilibrium is considered to be the result of kinetic constraints or equilibrium with organic matter. Log K values were derived by linear regression and were close to theoretical values for Al(OH)₃ minerals (e.g. gibbsite or amorphous Al(OH)₃), except for natural-phreatic groundwater for which lower log K values were found. Complexation of Al with DOC is shown to be an important factor for the Al concentrations, especially at high DOC concentrations as was found for agricultural-phreatic groundwater.  相似文献   

Ecohydrological parameters indicating different types of shallow groundwater   总被引：3，自引：0，他引：3  

Bas Pedroli 《Journal of Hydrology》1990,120(1-4):381-404

Ecohydrology, the interdisciplinary field of research directed to the application of hydrological knowledge to landscape ecology, is introduced to evaluate a test data set of 412 analyses of groundwater samples from 60 locations in a Dutch coversand area, numerically classified into 17 water types. Three types of simple groundwater quality classification are identified: single parameter, combined parameter and multiparameter.

Single quality parameters like pH, electrical conductivity (EC) and ion concentration values, are rarely used in ecohydrology. The representation of the complex conditional relationships between groundwater and the living part of ecosystems with these parameters is unsatisfactory, as also proved with the test data set. It is difficult to differentiate groundwater types reliably on the basis of one single parameter.

Combined quality parameters which are widely used are a pH-EC plot, a plot of pHCO₃ vs. (pH-pCa), after Kemmers, and an IR-EC plot after van Wirdum, where the ionic ratio (IR) is a Ca/(Ca + Cl) ratio. The latter two parameters indicate the residence time of the groundwater sampled as well as the hydrochemical conditions related to vegetation distribution and development. The IR is very popular for discriminating between atmocline (precipitation-like) and lithocline (long-residence groundwater-like) water types. In the test data set, objections to its use are discussed with regard to the conditions assumed in its application. Especially in the intermediate IR range, which should indicate potentially marked ecologic gradients, its theoretical basis is narrow. However, general relationships can be deduced from the IR-EC plot. In the test data set as well as in the general Dutch setting, the transformation of atmocline into lithocline water types determines to a large extent ecosystem diversity, although a third, metacline, pollution-induced water type increasingly interferes.

Finally, multiparameter classification of groundwater types is discussed. Statistical classification gives good results but is site specific. It is recomended that efforts be combined in the search for an internationally applicable composite classification adapted to ecohydrological research.  相似文献   

Multi-unit building address geocoding: An approach without indoor location reference data     

Bas Nottrot  Erwin Folmer  Debraj Roy  Bob Scheer  Peter Merx 《Transactions in GIS》2023,27(1):57-83

Accurately mapped locations within multi-unit properties are useful for several organizations in today's society. Published work on geocoding methods either require detailed location reference data or does not apply to multi-unit buildings. In this research, a generalizable method is realized to map apartment addresses to their explicit locations without access to indoor location reference data based on publicly available address- and geospatial-building information. The performance of this approach is measured by conducting a comparative study between a linear interpolation baseline and gradient-boosted decision trees model. The proposed method can successfully geocode addresses across different building shapes and sizes. Furthermore, the model significantly outperforms the baseline in terms of positional accuracy proving the feasibility of approximating apartment locations by their address- and geospatial-building information.  相似文献   

RCP2.6: exploring the possibility to keep global mean temperature increase below 2��C     

Detlef P. van Vuuren  Elke Stehfest  Michel G. J. den Elzen  Tom Kram  Jasper van Vliet  Sebastiaan Deetman  Morna Isaac  Kees Klein Goldewijk  Andries Hof  Angelica Mendoza Beltran  Rineke Oostenrijk  Bas van Ruijven 《Climatic change》2011,109(1-2):95-116

The RCP2.6 emission and concentration pathway is representative of the literature on mitigation scenarios aiming to limit the increase of global mean temperature to 2°C. These scenarios form the low end of the scenario literature in terms of emissions and radiative forcing. They often show negative emissions from energy use in the second half of the 21st century. The RCP2.6 scenario is shown to be technically feasible in the IMAGE integrated assessment modeling framework from a medium emission baseline scenario, assuming full participation of all countries. Cumulative emissions of greenhouse gases from 2010 to 2100 need to be reduced by 70% compared to a baseline scenario, requiring substantial changes in energy use and emissions of non-CO₂ gases. These measures (specifically the use of bio-energy and reforestation measures) also have clear consequences for global land use. Based on the RCP2.6 scenario, recommendations for further research on low emission scenarios have been formulated. These include the response of the climate system to a radiative forcing peak, the ability of society to achieve the required emission reduction rates given political and social inertia and the possibilities to further reduce emissions of non-CO₂ gases.  相似文献   

Public spaces in the occupied Palestinian territories     

Zahraa Zawawi  Eric Corijn  Bas Van Heur 《GeoJournal》2013,78(4):743-758

Most research on the Palestinian-Israeli conflict has focused on macro and meso-levels of abstraction by exploring national territorial and urban scales. This article, however, takes a more micro-level approach by investigating one specific public space in detail. It analyses the transformation and use of Dawar, the main public space of the city of Nablus, during the First (1987–1993) and Second (2000–2005) Intifadas. Public spaces in Palestinian cities have been transformed during the two Intifadas on both the physical and the socio-economic levels. Changing power relations affect the way public spaces are produced and regulated. Citizens, too, (re)produce public spaces through everyday practices, uses, and—in our case—explicit forms of resistance. The study proposes an analytical framework to look at public spaces as the result of power relations by combining the work of two French theorists, Michel Foucault and Henri Lefebvre. This framework is then applied to Dawar during the two Intifadas.  相似文献   

Seasonal evolution of runoff generation on agricultural land in the Belgian loess belt and implications for muddy flood triggering   总被引：1，自引：0，他引：1  

Olivier Evrard  Karel Vandaele  Charles Bielders  Bas van Wesemael 《地球表面变化过程与地形》2008,33(8):1285-1301

Muddy floods due to agricultural runoff are a widespread and frequent phenomenon in the European loess belt, and particularly in central Belgium. These floods are triggered when high quantities of runoff are generated on cropland and cause severe erosion. Three soil surface characteristics are relevant to determine the runoff potential of cultivated soils: soil cover by crops and residues, soil surface crusting and roughness. These characteristics have been observed on 65 cultivated fields throughout 2005. A heavy rainfall event representative for events triggering muddy floods in the region (60 mm h^?1 during 30 minutes) has been simulated using a 0·5 m² simulator on fields with the 17 most observed combinations of soil surface characteristics in central Belgium. Runoff is not observed in the case of (ploughed) bare uncrusted soils, nor in the case of soils covered by crops showing a transitional crust and a moderate roughness (1–2 cm). In the cases where runoff has been observed, mean runoff coefficients ranged from 13% (wheat in July) to 58% (sugar beet or maize in May and June). Grassed buffer strips (GBSs) and grassed waterways (GWWs) show a higher runoff coefficient (62% for GBSs and 73% for GWWs) than most cultivated soils (13–58%). Furthermore, it is demonstrated that small plot measurements can be used to estimate runoff generation at the field scale. A classification of runoff generation risk based on the surveys of soil surface characteristics has been applied to common crops of central Belgium. February as well as the period between May and September are the most critical for runoff at the field scale. However, it appears from monitoring of a 16 ha catchment that the highest runoff volumes and peak discharges are recorded between May and August after heavy rainfall, explaining why 85% of muddy floods are recorded during this period in central Belgium. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献