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91.
International climate negotiations that aim at reducing global greenhouse gas emissions are strongly influenced by a conflict between rich and poor countries and by a lack of consensus about the urgency of emission reduction measures. We have previously in an experimental game characterised the implied challenge of avoiding dangerous climate change as the “collective-risk social dilemma”. Here we introduce heterogeneous wealth and two time horizons into the collective-risk social dilemma game. We show that rich players are willing to substitute for missing contributions by the poor, provided the players collectively face intermediate climate targets that, if not reached, are potentially followed by simulated intermediate costly climate risks. However, despite some increase in the contributions of the rich against the final collective target, the final target is reached less often than the intermediate target. Our results provide experimental evidence that similar, intermediate time horizons between climate risks and climate change mitigation planning are a necessary, though not sufficient, component of successful climate negotiations. 相似文献
92.
Erping BI Torsten SCHMIDT 《地学前缘》2005,12(Z1):199-208
有机组分的土水分配系数(Kd)是描述有机组分在地下系统中吸附特征的重要参数。同时,它也是物质运移模拟和环境评价中的主要参数之一。影响Kd的因素可概括为三个方面:土壤性质、有机组分本身特征及水相的物理化学性质。一般而言,对于非极性和弱极性有机组分,土壤中的有机质含量(foc )是影响Kd的最主要因素。但是,对于极性有机组分(POCs), 特别是在土壤有机质含量较低的情况下,土壤中矿物的种类和含量、水化学组分特征(pH、离子力等)经常在吸附过程中起重要作用。实验室内测定Kd的方法包括批实验和柱实验方法。批实验法适用于研究Kd较高情况下的吸附。在Kd较低的情况下,如低有机质土壤对极性有机污染物的吸附,土柱色谱法(SCC)是更适宜的选择。另外,可用土柱色谱法快速了解各种因素对吸附过程的影响,并获取详细的吸附和解吸信息。应用土柱色谱法时应当注意非平衡吸附和可能的柱堵塞问题。很多文献中提到结合柱实验和已有的吸附数据来预测土壤有机碳标准化的分配系数Koc(=Kd/foc)。但是,如果没有考虑吸附中特定的作用过程(如矿物吸附),对极性有机组分Koc的预测将会产生很大的误差。在环境评价中,将从一种土壤测定的Koc 应用到不同性质的土壤中,可能会导致错误的认识。在进行室内实验时,应把标准土(如Eurosoi 相似文献
93.
Timothy P. Jones Steven M. Fortier Volker Mosbrugger Jochen Roessler Thorsen Utescher & Abdul R. Ashraf 《地学学报》1997,9(1):19-23
A detailed stable carbon isotopic profile of a late Miocene browncoal seam from the Lower Rhine Embayment, Germany, reveals two clear separate cycles of different frequency: this is the first instance of this type of isotopic signature being recognized within coals. The ratio of the two frequencies suggests this isotopic signal possibly resulted from climatic or vegetational responses to orbital forcing. The cyclicity has been enhanced by the application of conventional filtering methods on the data set. An analysis of the seam's palynology indicates a correlation between heavier isotopic compositions and the presence of Sequoiapollenites polyformosus , whose parent plant is believed to have favoured moist climates and higher groundwater tables. 相似文献
94.
Torsten Haberzettl Flavio S. Anselmetti Sabine W. Bowen Michael Fey Christoph Mayr Bernd Zolitschka Daniel Ariztegui Barbara Mauz Christian Ohlendorf Stephanie Kastner Andreas Lücke Frank Schäbitz Michael Wille 《Quaternary Science Reviews》2009,28(25-26):2927-2939
Paleoenvironmental records extending well into the last glacial period are scarce in the steppe regions of southern South America. Here, we present a continuous record for the past 55 ka from the maar lake Laguna Potrok Aike (51°58′ S, 70°23′ W, southern Patagonia, Argentina). Previous studies on a sedimentary core from a lake level terrace near the northern margin of the lake covered parts of Oxygen Isotope Stage (OIS) 3 (59–29 ka) whereas a second core from the centre of the basin comprised the last 16 ka. Tephrostratigraphical constraints and OSL ages from a third core located below the lake level terrace provide the crucial piece to close the gap between the previous coring sites. High-resolution XRF and magnetic susceptibility as well as grain size data indicate a positive hydrological balance alongside with relatively high aeolian activity during the glacial which is contemporaneous with increased dust fluxes in Antarctica. This is therefore the first evidence for contemporaneity of aeolian deposition in both the target area (Antarctica) and in the major source area of Patagonia. During the Holocene climatic conditions driving sediment deposition seem to have been more variable and less dominated by wind compared to glacial times. The identification of a minor lake level lowering at approximately 4 cal ka BP allows to refine earlier paleoenvironmental reconstructions for the Holocene. Within error margins the OSL ages are consistent with published radiocarbon-dated records offering hence a valuable tool for further studies of the sediments from Laguna Potrok Aike. The new chronology confirms the age of three tephra layers up to now only found in Laguna Potrok Aike sediments and ascribed to OIS 3. 相似文献
95.
Jean Vallance Lluís Fontboté Massimo Chiaradia Agnès Markowski Susanne Schmidt Torsten Vennemann 《Mineralium Deposita》2009,44(4):389-413
The Jurassic (approximately 145 Ma) Nambija oxidized gold skarns are hosted by the Triassic volcanosedimentary Piuntza unit
in the sub-Andean zone of southeastern Ecuador. The skarns consist dominantly of granditic garnet (Ad20–98) with subordinate pyroxene (Di46–92Hd17–42Jo0–19) and epidote and are spatially associated with porphyritic quartz-diorite to granodiorite intrusions. Endoskarn is developed
at the intrusion margins and grades inwards into a potassic alteration zone. Exoskarn has an outer K- and Na-enriched zone
in the volcanosedimentary unit. Gold mineralization is associated with the weakly developed retrograde alteration of the exoskarn
and occurs mainly in sulfide-poor vugs and milky quartz veins and veinlets in association with hematite. Fluid inclusion data
for the main part of the prograde stage indicate the coexistence of high-temperature (500°C to >600°C), high-salinity (up
to 65 wt.% eq. NaCl), and moderate- to low-salinity aqueous-carbonic fluids interpreted to have been trapped at pressures
around 100–120 MPa, corresponding to about 4-km depth. Lower-temperature (510–300°C) and moderate- to low-salinity (23–2 wt.%
eq. NaCl) aqueous fluids are recorded in garnet and epidote of the end of the prograde stage. The microthermometric data (Th
from 513°C to 318°C and salinity from 1.0 to 23 wt.% eq. NaCl) and δ18O values between 6.2‰ and 11.5‰ for gold-bearing milky quartz from the retrograde stage suggest that the ore-forming fluid
was dominantly magmatic. Pressures during the early retrograde stage were in the range of 50–100 MPa, in line with the evidence
for CO2 effervescence and probable local boiling. The dominance of magmatic low-saline to moderately saline oxidizing fluids during
the retrograde stage is consistent with the depth of the skarn system, which could have delayed the ingression of external
fluids until relatively low temperatures were reached. The resulting low water-to-rock ratios explain the weak retrograde
alteration and the compositional variability of chlorite, essentially controlled by host rock compositions. Gold was precipitated
at this stage as a result of cooling and pH increase related to CO2 effervescence, which both result in destabilization of gold-bearing chloride complexes. Significant ingression of external
fluids took place after gold deposition only, as recorded by δ18O values of 0.4‰ to 6.2‰ for fluids depositing quartz (below 350°C) in sulfide-rich barren veins. Low-temperature (<300°C)
meteoric fluids (δ18Owater between −10.0‰ and −2.0‰) are responsible for the precipitation of late comb quartz and calcite in cavities and veins and
indicate mixing with cooler fluids of higher salinities (about 100°C and 25 wt.% eq. NaCl). The latter are similar to low-temperature
fluids (202–74.5°C) with δ18O values of −0.5‰ to 3.1‰ and salinities in the range of 21.1 to 17.3 wt.% eq. CaCl2, trapped in calcite of late veins and interpreted as basinal brines. Nambija represents a deep equivalent of the oxidized
gold skarn class, the presence of CO2 in the fluids being partly a consequence of the relatively deep setting at about 4-km depth. As in other Au-bearing skarn
deposits, not only the prograde stage but also the gold-precipitating retrograde stage is dominated by fluids of magmatic
origin. 相似文献
96.
Acta Geotechnica - An elastic–plastic constitutive model considering particle breakage for simulation of crushable granular soils behavior is proposed. In the model, elastic strain rates are... 相似文献
97.
Tilman Gocht Johannes A.C. Barth Michaela Epp Maik Jochmann Michaela Blessing Torsten C. Schmidt Peter Grathwohl 《Applied Geochemistry》2007,22(12):2652
Concentrations and isotope compositions of polycyclic aromatic hydrocarbons (PAHs) were determined in natural soils of Southern Germany. In selected profiles perylene concentrations increased with soil depth when compared to the other PAH compounds present. However, its low solubility made vertical transport by seepage water unlikely. Therefore two mechanisms are discussed that could have caused the unusual distribution of perylene in these soils:
- (a) Atmospheric deposition of combustion-derived (i.e. pyrogenic) perylene in the top-soil and
- (b) in situ generation in the sub-soil of these specific terrestrial environments. This could have been caused by microbial activities or other catalytic processes yet unknown.
98.
Michael Schmidt Martin Fengler Torsten Mayer-Gürr Annette Eicker Jürgen Kusche Laura Sánchez Shin-Chan Han 《Journal of Geodesy》2007,81(1):17-38
This article provides a survey on modern methods of regional gravity field modeling on the sphere. Starting with the classical
theory of spherical harmonics, we outline the transition towards space-localizing methods such as spherical splines and wavelets.
Special emphasis is given to the relations among these methods, which all involve radial base functions. Moreover, we provide
extensive applications of these methods and numerical results from real space-borne data of recent satellite gravity missions,
namely the Challenging Minisatellite Payload (CHAMP) and the Gravity Recovery and Climate Experiment (GRACE). We also derive
high-resolution gravity field models by effectively combining space-borne and surface measurements using a new weighted level-combination
concept. In addition, we outline and apply a strategy for constructing spatio-temporal fields from regional data sets spanning
different observation periods. 相似文献
99.
Machaček Jan Staubach Patrick Tavera Carlos Eduardo Grandas Wichtmann Torsten Zachert Hauke 《Acta Geotechnica》2022,17(11):5253-5273
Acta Geotechnica - This paper presents an approach for the automatic parameter calibration (AC) of a hypoplastic constitutive soil model. The calibration software developed in this work simplifies... 相似文献
100.
Christoph Mayr Andreas Lücke Nora I. Maidana Michael Wille Torsten Haberzettl Hugo Corbella Christian Ohlendorf Frank Schäbitz Michael Fey Stephanie Janssen Bernd Zolitschka 《Journal of Paleolimnology》2009,42(1):81-102
A combination of carbon-to-nitrogen ratios (TOC/TN), Rock Eval-analyses, and stable isotope values of bulk nitrogen (δ15N) and organic carbon (δ13Corg) was used to characterize bulk organic matter (OM) of a piston core from the Patagonian maar lake Laguna Potrok Aike (Argentina)
for the purpose of palaeoenvironmental reconstruction. Sedimentary data were compared with geochemical signatures of potential
OM sources from Laguna Potrok Aike and its catchment area to identify the sources of sedimentary OM. Correlation patterns
between isotopic data and TOC/TN ratios allowed differentiation of five distinct phases with different OM composition. Before
8470 calibrated 14C years before present (cal. yrs BP) and after 7400 cal. yrs BP, isotopic and organo-geochemical fingerprints indicate that
the sediments of Laguna Potrok Aike consist predominantly of soil and diatom OM with varying admixtures of cyanobacterial
and aquatic macrophyte OM. For a short phase of the early Holocene (ca. 8470–7400 cal. yrs BP), however, extremely high input
of soil OM is implied by isotopic fingerprints. Previous seismic and geochronological results indicate a severe lake-level
drop of 33 m below present-day shortly before 6590 cal. yrs BP. It is suggested that this lake level drop was accompanied
by increased erosion of shore banks and channel incision enhancing soil OM deposition in the lake basin. Thus, isotopic data
can be linked to hydrological variations at Laguna Potrok Aike and allow a more precise dating of this extremely low lake
level. An isotopic mixing model was used including four different sources (soil, cyanobacteria, diatom and aquatic macrophyte
OM) to model OM variations and the model results were compared with quantitative microfossil data. 相似文献