Review: evaporation of mercury from soils. An integration and synthesis of current knowledge   总被引：8，自引：0，他引：8  

K. Schlüter 《Environmental Geology》2000,39(3-4):249-271

 Understanding the mechanisms of mercury evaporation from soil to the atmosphere is necessary for tracing the fate of mercury in the biological environment and for assessing potential health effects and the impact of anthropogenic mercury emissions on the environment. In this article an integrating overview of the current knowledge of the mechanisms of mercury evaporation is presented. Abiological and biological formation of Hg(0) and/or (CH₃)₂Hg in the uppermost soil layers are the rate limiting processes of mercury evaporation from soils in background areas; the evaporation rate in background areas is probably strongly influenced by deposited airborne mercury. The evaporation rate limiting factors in mercury enriched mineralized areas with large fractions of total mercury being volatile mercury species (relative to background soil in the non-mineralized vicinity) meteorological variations and the transport characteristics of soils for volatile mercury species. Mercury evaporation rates from background soils are usually <0.2 μg·m^–2·h^–1 and significantly smaller than from mercury-enriched mineralized areas. Received: 20 November 1995 / Accepted: 24 July 1996  相似文献   

High-altitude erratics in the Bernese Alps (Switzerland)     

Christian Gn?gi  Christian Schlüchter 《Swiss Journal of Geoscience》2012,105(3):401-415

Little is known about the Early Pleistocene landscape and glacial history of the Swiss Alps, largely because of the scarcity of sediments dating from that period. Here we investigate high-altitude, presumably Early Pleistocene relics of unconsolidated, near-surface sediments that occur at the Stockeseen site (close to the Stockhorn) and at Wagenmoos (close to Sibe H?ngste) in the Bernese Alps. We complemented our study by analysing cave gravels from 13 sites. Whereas the underlying bedrocks are part of the purely sedimentary Penninic Prealps and the Helvetic zone, the investigated sediments and cave gravels contain characteristic erratic crystalline clasts (HP-LT-metagabbro, medium-grade metamorphic quartzite, jadeitite, glaucophane-schist, low-grade metamorphic gabbro and peridotite). The erratics originate from Penninic and Austroalpine nappes which are exposed only south of the Bernese High Alps, today??s water divide. In combination with partly distinct glacial features of the indicator erratics, this suggests that transfluences existed from the Valais (Rh?ne valley) to the Bernese Alps. Our findings suggest two transfluence routes, one over a precursor of the Gemmipass to the palaeo-Kander valley, providing crystalline erratics towards Sibe H?ngste, and one over precursors of the Sanetschpass and Saanenm?serpass into the palaeo-Simmen valley and towards the Stockhorn. The Wagenmoos erratics must have been deposited before the re-routing of the palaeo-Aare river (from northward to westward) and its subsequent deepening, which indicates an Early Pleistocene timing of the respective transfluence. This is in agreement with published burial ages of ~1.87?Ma?±?0.21 for cave gravels with crystalline components in the cave system Réseau Siebenhengste?CHohgant (beneath the Wagenmoos site).  相似文献   

Combination of Precise Leveling and InSAR Data to Constrain Source Parameters of the Mw = 6.5, 26 December 2003 Bam Earthquake     

Mahdi Motagh  Jürgen Klotz  Farokh Tavakoli  Yahya Djamour  Siavash Arabi  Hans-Ulrich Wetzel  Jochen Zschau 《Pure and Applied Geophysics》2006,163(1):1-18

We used new precise leveling data acquired 40 days after the Bam earthquake in combination with radar interferometry observations from both ascending and descending orbits to investigate static deformation associated with the 2003 Bam earthquake. We invert this geodetic data set to gain insight into the fault geometry and slip distribution of the rupture. The best-fitting dislocation model is a steeply east-dipping right-lateral strike-slip fault that has a size of 11 by 8 km and strikes N2°W. We find that such smooth geometry fits available geodetic data better than previously proposed models for this earthquake. Our distributed slip model indicates a maximum strike slip of 3 m occurring about 3 to 5 km deep. The slip magnitude and depth of faulting taper to the north, where the fault approaches the Bam city. Inclusion of crustal layering increases the amount of maximum slip inferred at depth by about 4%.  相似文献   

Flow and Transport in the Obstacle Layer: First Results of the Micro-Scale Model MITRAS     

K. H. Schlünzen  D. Hinneburg  O. Knoth  M. Lambrecht  B. Leitl  S. López  C. Lüpkes  H. Panskus  E. Renner  M. Schatzmann  T. Schoenemeyer  S. Trepte  R. Wolke 《Journal of Atmospheric Chemistry》2003,44(2):113-130

A new atmospheric micro-scale chemistry, transport and stream model, MITRAS, has been developed within the Tropospheric Research Program (TFS). MITRAS is an obstacle resolving model solving simultaneously the governing equations for chemistry, pollutant transport including soot as well as for the flow and temperature field. The chemical reaction module is based on a simplified RACM mechanism. MITRAS has been tested against quality ensured wind tunnel data. The model results on soot and ozone concentrations as well as on the spatial representativeness of measurement sites underline the necessity for high-resolution flow simulations for case studies on close-to-source chemistry and pollutant transport within the urban canopy layer.  相似文献   

Evolution of parental magmas of Miocene shield basalts of Gran Canaria (Canary Islands): constraints from crystal,melt and fluid inclusions in minerals   总被引：7，自引：0，他引：7  

A. A. Gurenko  Thor H. Hansteen  Hans-Ulrich Schmincke 《Contributions to Mineralogy and Petrology》1996,124(3-4):422-435

 Picritic units of the Miocene shield volcanics on Gran Canaria, Canary Islands, contain olivine and clinopyroxene phenocrysts with abundant primary melt, crystal and fluid inclusions. Composition and crystallization conditions of primary magmas in equilibrium with olivine Fo_90-92 were inferred from high-temperature microthermometric quench experiments, low-temperature microthermometry of fluid inclusions and simulation of the reverse path of olivine fractional crystallization based on major element composition of melt inclusions. Primary magmas parental for the Miocene shield basalts range from transitional to alkaline picrites (14.7–19.3 wt% MgO, 43.2–45.7 wt% SiO₂). Crystallization of these primary magmas is believed to have occurred over the temperature range 1490–1150° C at pressures ≈5 kbar producing olivine of Fo_80.6-90.2, high-Ti chrome spinel [Mg/ (Mg+Fe²⁺)=0.32–0.56, Cr/(Cr+Al)=0.50–0.78, 2.52–8.58 wt% TiO₂], and clinopyroxene [Mg/(Mg+Fe)=0.79–0.88, Wo_44.1-45.3, En_43.9-48.0, Fs_6.8-11.0] which appeared on the liquidus together with olivine≈Fo₈₆. Redox conditions evolved from intermediate between the QFM and WM buffers to late-stage conditions of NNO+1 to NNO+2. The primary magmas crystallized in the presence of an essentially pure CO₂ fluid. The primary magmas originated at pressures >30 kbar and temperatures of 1500–1600° C, assuming equilibrium with mantle peridotite. This implies melting of the mantle source at a depth of ≈100 km within the garnet stability field followed by migration of melts into magma reservoirs located at the boundary between the upper mantle and lower crust. The temperatures and pressures of primary magma generation suggest that the Canarian plume originated in the lower mantle at depth ≈900 km that supports the plume concept of origin of the Canary Islands. Received: 23 October 1995/Accepted: 21 February 1996  相似文献   

Petrology, geochemistry, S, Cl and F abundances, and S oxidation state of sideromelane glass shards from Pleistocene ash layers north and south of Gran Canaria (ODP Leg 157)     

Andrey A. Gurenko  Hans-Ulrich Schmincke 《Contributions to Mineralogy and Petrology》1998,131(1):95-110

Major elements, S, F, Cl concentrations and relative proportions of S⁶⁺ to total S were analyzed with electron microprobe in sideromelane glass shards from Pleistocene volcaniclastic sediments drilled during ODP Leg 157. Glasses are moderately to strongly evolved and represent a spectrum from alkali basalt, basanite and nephelinite through hawaiite, mugearite and tephrite to phonolitic tephrite. Measured S⁶⁺/ΣS (0.03–0.98) and calculated Fe²⁺/Fe³⁺ (2.5–5.8) ratios in the melt yield preeruptive redox conditions ranging from NNO−1.4 to NNO+2.1. The morphology of the glass shards, variations of S and Cl concentrations (0.010–0.127 wt% S, 0.018–0.129 wt% Cl), calculated preeruptive temperatures (1030–1200 °C) and oxygen fugacities suggest that glasses deposited even within the same ash layers have diverse origin and may have resulted from both submarine and subaerial eruptions. Most vesicle-free glasses are characterized by high concentrations of S and represent undegassed or slightly degassed submarine lavas, whereas vesiculated glasses with low concentrations of S and Cl are strongly degassed and can be ascribed to the eruptions in shallow water or on land. Sideromelane glass shards at Sites 953 are thought to have resulted from submarine eruptions northeast of Gran Canaria, glasses at Site 954 represent mostly volcaniclastic material of shallow water submarine and subaerial eruptions on Gran Canaria and Tenerife, and glasses deposited at Site 956 resulted from submarine or explosive eruptions on Tenerife. Received: 8 April 1997 / Accepted: 27 October 1997  相似文献   

Multi-stage magma ascent beneath the Canary Islands: evidence from fluid inclusions     

Thor H. Hansteen  Andreas Klügel  Hans-Ulrich Schmincke 《Contributions to Mineralogy and Petrology》1998,132(1):48-64

Gabbroic and ultramafic xenoliths and olivine and clinopyroxene phenocrysts in basaltic rocks from Gran Canaria, La Palma, El Hierro, Lanzarote and La Gomera (Canary Islands) contain abundant CO₂-dominated fluid inclusions. Inclusion densities are strikingly similar on a regional scale. Histogram maxima correspond to one or more of the following pressures: (1) minimum 0.55 to 1.0 GPa (within the upper mantle); (2) between 0.2 and 0.4 GPa (the Moho or the lower crust); (3) at about 0.1 GPa (upper crust). Fluid inclusions in several rocks show a bimodal density distribution, the lower-density maximum comprising both texturally early and late inclusions. This is taken as evidence for an incomplete resetting of inclusion densities, and simultaneous formation of young inclusions, at well-defined magma stagnation levels. For Gran Canaria, pressure estimates for early inclusions in harzburgite and dunite xenoliths and olivine phenocrysts in the host basanites overlap at 0.9 to 1.0 GPa, indicating that such magma reservoir depths coincide with levels of xenolith entrainment into the magmas. Magma chamber pressures within the mantle, inferred to represent levels of mantle xenolith entrainment, are 0.65–0.95 GPa for El Hierro, 0.60–0.68 GPa for La Palma, and 0.55–0.75 GPa for Lanzarote. The highest-density fluid inclusions in many Canary Island mantle xenoliths have probably survived in-situ near-isobaric heating at the depth of xenolith entrainment. Inclusion data from all islands indicate ponding of basaltic magmas at Moho or lower crustal depths, and possibly at an additional higher level, strongly suggestive of two main crustal accumulation levels beneath each island. We emphasize that repeated magmatic underplating of primitive magmas, and therefore intrusive accretion, are important growth mechanisms for the Canary Islands, and by analogy, for other ocean islands. Comparable fluid inclusion data from primitive rocks in other tectonic settings, including Iceland, Etna and continental rift systems (Hungary, South Norway), indicate that magma accumulation close to Moho depths shortly before eruption is not, however, restricted to oceanic intraplate volcanoes. Lower crustal ponding and crystallization prior to eruption may be the rule rather than the exception, independent of the tectonic setting. Received: 30 May 1997 / Accepted: 6 February 1998  相似文献   

The lateral facies of ignimbrites at Laacher See volcano     

Rolf Schumacher  Hans-Ulrich Schmincke 《Bulletin of Volcanology》1990,52(4):271-285

Valley-fill ignimbrites of the Middle Laacher See Tephra (MLST) in the proximal depositional fan south of Laacher See volcano are laterally continuous with fine-grained overbank-facies deposits, 0.5–1.5 m thick, covering higher elevations and interfluves between the paleovalleys. The overbank deposits consist of up to 12 ash layers, each 4–10 cm thick, which show internal structures typical of ash-flow transport, such as poor sorting, reverse size-grading of pumice, local normal grading of coarse ash-sized lithics above a fine-grained basal layer, cross-stratification behind obstacles, and erosional unconformities. Thickness, median grain-size, and number of individual layers decrease systematically with distance from the vent. Overbank ash layers thicken at the valley slopes and form discrete valley-fill ignimbrite flow units in the paleochannels with median grain size increasing from 63 m to 350 m. Toward the center of paleochannels, however, the well-defined overbank facies is obscured by mutual erosion of individual flow units. Overlapping data fields in ternary grain-size variation diagrams indicate the overbank facies to have evolved from ash flows chiefly through depletion of lapilli and coarse ash. Overbank-facies ash layers do not represent dust layers resulting from elutriation clouds of ash flows (co-ignimbrite ash) or surge deposits developed on higher ground due to low concentration of solids. They are similar in some parameters to Taupo-type ignimbrite veneer deposits, but are interpreted differently. The thin, fine-grained, Laacher See ash layers are thought to have been deposited from diluted portions of the flow proceeding directly from the eruption column while the main pyroclastic flows were confined to the paleovalleys radiating away from the eruptive center. The wide distribution of the thin ash layers is attributed to the balance of deposition from various flow parts and turbulent entraining and heating of ambient air that sustained sufficient mobility of the diluted flows to spread across hills and level ground.  相似文献   

A fossiliferous resin from the Cenomanian of the Paris and Aquitanian basins of northwestern France     

Th. Schlüter 《Cretaceous Research》1983,4(3):265-269

The discovery of a Cenomanian fossiliferous resin at different localities in the Paris and Aquitanian basins of northwestern France is described. The abiotic peculiarities and methodological difficulties are mentioned and evidence for the following arachnid and insect orders given: Phalangiida, Araneae; Blattariae, Isoptera, Psocoptera (?), Heteroptera, Planipennia, Coleoptera, Hymenoptera, Lepidoptera and Diptera. Biostratonomic and palaeoecological implications are discussed.  相似文献   

Vegetation change caused by land-use intensification —examples from the Hilly Country of Saxony     

Dr. H. Schlüter  Dr. W. Böttcher  Dr. O. Bastian 《GeoJournal》1990,22(2):167-174

Land-use intensification, especially by industrilization of agriculture, has caused substantial changes in landscape, in particular in vegetation. This is demonstrated by some examples from the Saxon Hilly Country: Meadows of a flood plain rich in species were transformed into monotonous grassland and ploughed fields; formerly richly differentiated agro-phytocoenoses became extremely depleted; in fruit plantations a new herbicide-tolerating plant community developed; in small remains of agro-woods and in coniferous forests eutrophication favours nitrophilous species at the expense of acidophilous species.All in all, we perceive a dramatic reduction in the biotic diversity with regard to plant and animal species as well as biocoenoses. This is of great landscape-ecological significance: The self-regulation of matter and energy cycles is limited; compensation by inputs of matter and energy may cause irreversible damage to landscapes. By harmonization of economic and ecological goals, an optimum biotic diversity and ecological stability should be aimed at. Vegetation is crucial as a dominating biotic component of landscape and as an integral bioindicator in environmental monitoring.  相似文献