Electrical conductivity of NaCl-bearing aqueous fluids to 600 °C and 1 GPa     

Ryosuke?Sinmyo  Hans?KepplerEmail author 《Contributions to Mineralogy and Petrology》2017,172(1):4

The electrical conductivity of aqueous fluids containing 0.01, 0.1, and 1 M NaCl was measured in an externally heated diamond cell to 600 °C and 1 GPa. These measurements therefore more than double the pressure range of previous data and extend it to higher NaCl concentrations relevant for crustal and mantle fluids. Electrical conductivity was generally found to increase with pressure and fluid salinity. The conductivity increase observed upon variation of NaCl concentration from 0.1 to 1 M was smaller than from 0.01 to 0.1 M, which reflects the reduced degree of dissociation at high NaCl concentration. Measured conductivities can be reproduced (R ² = 0.96) by a numerical model with log \(\sigma\) = ?1.7060– 93.78/T + 0.8075 log c + 3.0781 log \(\rho\) + log \(\varLambda\) ₀(T, \(\rho\)), where \(\sigma\) is the conductivity in S m^?1, T is temperature in K, c is NaCl concentration in wt%, \(\rho\) is the density of pure water (in g/cm³) at given pressure and temperature, and \(\varLambda\) ₀ (T, \(\rho\)) is the molar conductivity of NaCl in water at infinite dilution (in S cm² mol^?1), \(\varLambda\) ₀ = 1573–1212 \(\rho\) + 537 062/T–208 122 721/T ². This model allows accurate predictions of the conductivity of saline fluids throughout most of the crust and upper mantle; it should not be used at temperatures below 100 °C. In general, the data show that already a very small fraction of NaCl-bearing aqueous fluid in the deep crust is sufficient to enhance bulk conductivities to values that would be expected for a high degree of partial melting. Accordingly, aqueous fluids may be distinguished from hydrous melts by comparing magnetotelluric and seismic data. H₂O–NaCl fluids may enhance electrical conductivities in the deep crust with little disturbance of v _p or v _p/v _s ratios. However, at the high temperatures in the mantle wedge above subduction zones, the conductivity of hydrous basaltic melts and saline aqueous fluids is rather similar, so that distinguishing these two phases from conductivity data alone is difficult. Observed conductivities in forearc regions, where temperatures are too low to allow melting, may be accounted for by not more than 1 wt% of an aqueous fluid with 5 wt% NaCl, if this fluid forms a continuous film or fills interconnected tubes.  相似文献   

Quality of geological CO2 storage to avoid jeopardizing climate targets     

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   

Exploring pathways for sustainable water management in river deltas in a changing environment   总被引：2，自引：1，他引：1  

Marjolijn Haasnoot  Hans Middelkoop  Astrid Offermans  Eelco van Beek  Willem P. A. van Deursen 《Climatic change》2012,115(3-4):795-819

Exploring adaptation pathways into an uncertain future can support decisionmaking in achieving sustainable water management in a changing environment. Our objective is to develop and test a method to identify such pathways by including dynamics from natural variability and the interaction between the water system and society. Present planning studies on long-term water management often use a few plausible futures for one or two projection years, ignoring the dynamic aspect of adaptation through the interaction between the water system and society. Our approach is to explore pathways using multiple realisations of transient scenarios with an Integrated Assessment Meta Model (IAMM). This paper presents the first application of the method using a hypothetical case study. The case study shows how to explore and evaluate adaptation pathways. With the pathways it is possible to identify opportunities, threats, timing and sequence of policy options, which can be used by policymakers to develop water management roadmaps into the future. By including the dynamics between the water system and society, the influence of uncertainties in both systems becomes clearer. The results show, among others, that climate variability rather than climate change appears to be important for taking decisions in water management.  相似文献   

Greening in the circumpolar high-latitude may amplify warming in the growing season   总被引：1，自引：0，他引：1  

Jee-Hoon Jeong  Jong-Seong Kug  Baek-Min Kim  Seung-Ki Min  Hans W. Linderholm  Chang-Hoi Ho  David Rayner  Deliang Chen  Sang-Yoon Jun 《Climate Dynamics》2012,38(7-8):1421-1431

We present a study that suggests greening in the circumpolar high-latitude regions amplifies surface warming in the growing season (May–September) under enhanced greenhouse conditions. The investigation used a series of climate simulations with the Community Atmospheric Model version 3—which incorporates a coupled, dynamic global vegetation model—with and without vegetation feedback, under both present and doubled CO₂ concentrations. Results indicate that climate warming and associated changes promote circumpolar greening with northward expansion and enhanced greenness of both the Arctic tundra and boreal forest regions. This leads to additional surface warming in the high-latitudes in the growing season, primarily through more absorption of incoming solar radiation. The resulting surface and tropospheric warming in the high-latitude and Arctic regions weakens prevailing tropospheric westerlies over 45–70N, leading to the formation of anticyclonic pressure anomalies in the Arctic regions. These pressure anomalies resemble the anomalous circulation pattern during the negative phase of winter Arctic Oscillation. It is suggested that these circulation anomalies reinforce the high-latitude and Arctic warming in the growing season.  相似文献   

The chemical composition of medieval wood ash glass from Central Europe     

Karl Hans Wedepohl  Klaus Simon 《Chemie der Erde / Geochemistry》2010,70(1):89-97

Medieval wood ash glass classified as 6 early medieval wood ash glasses, 17 wood ash glasses, 5 early wood ash lime glasses, 7 wood ash lime glasses and 9 mixed alkali glasses has been analyzed by microprobe and ICP-mass spectrometry on 61 elements. Their calcium oxide to potassium oxide ratio (CaO/K₂O) increases from early to late medieval glasses according to an increase of the proportion of twigs in the bulk amount of wood (logs plus twigs). Twigs because of their relatively large proportion of bark contain more calcium than wood logs. The ratio CaO/K₂O of the glasses from not yet evaluated excavations can be used for dating. The observation that the 25 minor elements Be, Sc, V, Cr, Ge, Y, Nb, REE (La to Lu), Ta, W and Bi occur in almost equal concentrations in the five subtypes of wood ash glass makes it highly probable that these elements were introduced into the starting mixtures of the glasses by means of quartz from quartz-rich sand with heavy minerals. The majorities of the wood ash glasses contain so-called europium anomalies within the group of rare-earth elements (REE). Their Eu concentrations normalized to those of the Continental Earth's Crust are lower than the normalized samarium and gadolinium concentrations. These Eu anomalies are apparently inherited from the granitic source of quartz in the upper Continental Earth's Crust. Soda ash and soda lime glass as the other major types in the history of glass contain no Eu anomaly. Therefore a different source of quartz has caused this important element constellation for these glass types. The elements K, Cu, Rb and S are physiologically separated from Ca, P, Mn, Sr and B during the growth of the wood and bark, respectively, in the trees. Different sources of the metals Cu and Co were used for colouring the glasses of our report.  相似文献   

A ~180,000 years sedimentation history of a perialpine overdeepened glacial trough (Wehntal, N-Switzerland)     

Flavio S. Anselmetti  Ruth Drescher-Schneider  Heinz Furrer  Hans Rudolf Graf  Sally E. Lowick  Frank Preusser  Marc A. Riedi 《Swiss Journal of Geoscience》2010,103(3):345-361

A 30 m-deep drill core from a glacially overdeepened trough in Northern Switzerland recovered a ~180 ka old sedimentary succession that provides new insights into the timing and nature of erosion–sedimentation processes in the Swiss lowlands. The luminescence-dated stratigraphic succession starts at the bottom of the core with laminated carbonate-rich lake sediments reflecting deposition in a proglacial lake between ~180 and 130 ka ago (Marine Isotope Stage MIS 6). Anomalies in geotechnical properties and the occurrence of deformation structures suggest temporary ice contact around 140 ka. Up-core, organic content increases in the lake deposits indicating a warming of climate. These sediments are overlain by a peat deposit characterised by pollen assemblages typical of the late Eemian (MIS 5e). An abrupt transition following this interglacial encompasses a likely hiatus and probably marks a sudden lowering of the water level. The peat unit is overlain by deposits of a cold unproductive lake dated to late MIS 5 and MIS 4, which do not show any direct influence from glaciers. An upper peat unit, the so-called «Mammoth peat», previously encountered in construction pits, interrupts this cold lacustrine phase and marks more temperate climatic conditions between 60 and 45 ka (MIS 3). In the upper part of the core, a succession of fluvial and alluvial deposits documents the Late Glacial and Holocene sedimentation in the basin. The sedimentary succession at Wehntal confirms that the glaciation during MIS 6 did not apparently cause the overdeepening of the valley, as the lacustrine basin fill covering most of MIS 6 is still preserved. Consequently, erosion of the basin is most likely linked to an older glaciation. This study shows that new dating techniques combined with palaeoenvironmental interpretations of sediments from such overdeepened troughs provide valuable insights into the past glacial history.  相似文献   

Altimetry with GNSS-R interferometry: first proof of concept experiment   总被引：1，自引：0，他引：1  

Antonio Rius  Oleguer Nogués-Correig  Serni Ribó  Estel Cardellach  Santi Oliveras  Enric Valencia  Hyuk Park  José Miguel Tarongí  Adriano Camps  Hans van der Marel  Roel van Bree  Bas Altena  Manuel Martín-Neira 《GPS Solutions》2012,16(2):231-241

The Global Navigation Satellite System Reflectometry (GNSS-R) concept was conceived as a means to densify radar altimeter measurements of the sea surface. Until now, the GNSS-R concept relied on open access to GNSS transmitted codes. Recently, it has been proposed that the ranging capability of the technique for ocean altimetric applications can be improved by using all the signals transmitted in the bandwidth allocated to GNSS, which includes open access as well as encrypted signals. The main objective of this study is to provide experimental proof of this enhancement through a 2-day experiment on the Zeeland Bridge (The Netherlands). In the experiment, we used a custom built GNSS-R system, composed of high gain GPS antennas, calibration subsystem, and an FPGA-based signal processor which implemented the new concepts, an X-band radar altimeter and a local geodetic network. The results obtained indicate that the new approach produces a significant improvement in GNSS-R altimetric performance.  相似文献   

Rockfalls into forests: Analysis and simulation of rockfall trajectories — considerations with respect to mountainous forests in Switzerland   总被引：3，自引：1，他引：2  

Simone?PerretEmail author  Fabian?Dolf  Hans?Kienholz 《Landslides》2004,1(2):123-130

Rockfalls are a major threat to settlements and transportation routes in many places. Although the general protective effect of forests against rockfalls is currently not questioned, little is known about the ideal properties of a forest stand that provides good protection. Therefore, in this study the question was assessed of how mountainous forests may influence rockfalls of single boulders. An actual rockfall trajectory was measured, recorded, analysed and simulated with a rockfall model. Rockfalls into different forest scenarios were also modelled for the site. Results showed that the actual rockfall event can be well simulated. Furthermore, a completely forested slope reduces velocity and energy of the falling blocks much better than a sparsely forested slope. For the profile discussed in this paper, the largest effect upon falling 3 m³ blocks was obtained with a high forest containing 350 trees per ha. The results confirmed common assumptions on ideal properties of a protective forest stand against rockfalls.  相似文献   

The influence of cyanobacteria on oil polluted intertidal soils at the Saudi Arabian Gulf shores   总被引：3，自引：0，他引：3  

Barth HJ 《Marine pollution bulletin》2003,46(10):1245-1252

In 1991 the second Gulf War lead to the largest oil spill in human history. Over 770 km of coastline from southern Kuwait to Abu Ali Island (Saudi Arabia) were smothered with oil and tar, erasing most of the local plant and animal communities. In the following year cyanobacteria colonized most of the oil polluted shores. In the study area at the Saudi Arabian Gulf coast north of Jubail three different processes were observed that followed the extensive formation of cyanobacterial mats. The first one is desiccation, cracking, and peeling of the cyanobacterial mats, thereby removing the uppermost part of the oiled sediment. The second is the resettlement of burrowing macrofauna like crabs and benthic animals such as gastropods, which outcompete the cyanobacteria again. The third process is further extensive growth of cyanobacteria building thick laminated mats. These layers, completely seal the surface and hence produce an anaerobic milieu which inhibits oil degradation. As long as such cyanobacteria exist, they will prevent microbial oil degradation as well as any resettlement by macrofauna.  相似文献   

Gigantic volcanic eruptions and climatic change in the early Eocene     

Hans Egger  Ewald Brückl 《International Journal of Earth Sciences》2006,95(6):1065-1070

23 layers of altered volcanic ash (bentonites) originating from the North Atlantic Igneous Province have been recorded in early Eocene deposits of the Austrian Alps, about 1,900 km away from the source area. The Austrian bentonites are distal equivalents of the “main ash-phase” in Denmark and the North Sea basin. We have calculated the total eruption volume of this series as 21,000 km³, which occurred in 600,000 years. The most powerful single eruption of this series took place 54.0 million years ago (Ma) and ejected ca. 1,200 km³ of ash material, which makes it one of the largest basaltic pyroclastic eruptions in geological history. The clustering of eruptions must have significantly affected the incoming solar radiation in the early Eocene by the continuous production of stratospheric dust and aerosol clouds. This hypothesis is corroborated by oxygen isotope values, which indicate a global decrease of sea surface temperatures between 1 and 2°C during this major phase of explosive volcanism.  相似文献