Geophysical-geochemical investigation of fire-prone landfills     

Vladimir Frid  Dmitri Doudkinski  Gady Liskevich  Efim Shafran  Arie Averbakh  Nikolay Korostishevsky  Larisa Prihodko 《Environmental Earth Sciences》2010,60(4):787-798

This paper deals with the integration of electrical resistivity tomography and geochemical methods for studying four different fire-prone landfills. Landfill gas composition (CH₄, H₂S, O₂, CO, CO₂) and subsurface temperature were measured with the constant net 50 × 50 m from the depth 10–60 cm. 28 electrical resistivity tomography lines were surveyed, while Wenner and Sclumberger electrode arrays were employed for all measurements. At the studied sites the landfill gas and temperature measurements mapped gas and temperature anomalies over underground fire sources. 2D electrical resistivity tomography lines, performed over these anomalies, showed these fire sources as high-resistivity zones. The joint employment of the electrical imaging and geochemical survey seems to be a useful tool in carrying out diagnostic investigations at fire-prone landfills.  相似文献   

Atmosphere-ionosphere response to the M9 Tohoku earthquake revealed by multiinstrument space-borne and ground observations： Preliminary results     

Dimitar Ouzounov  Sergey Pulinets  Alexey Romanov  Alexander Romanov  Konstantin Tsybulya  Dmitri Davidenko  Menas Kafatos  Patrick Taylor 《地震学报(英文版)》2011,(6):557-564

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Two decadally resolved records from north‐west European peat bogs show rapid climate changes associated with solar variability during the mid–late Holocene     

Dmitri Mauquoy  Dan Yeloff  Bas Van Geel  Dan J. Charman  Antony Blundell 《第四纪科学杂志》2008,23(8):745-763

Two ¹⁴C accelerator mass spectrometry (AMS) wiggle‐match dated peat sequences from Denmark and northern England record changes in mire surface wetness reconstructed using plant macrofossil and testate amoebae analyses. A number of significant mid–late Holocene climatic deteriorations (wet shifts) associated with declines in solar activity were recorded (at ca. 2150 cal. yr BC, 740 cal. yr BC, cal. yr AD 930, cal. yr AD 1020, cal. yr AD 1280–1300, cal. yr AD 1640 and cal. yr AD 1790–1830). The wet shifts identified from ca. cal. yr AD 930 are concurrent with or lag decreases in solar activity by 10–50 years. These changes are replicated by previous records from these and other sites in the region and the new records provide improved precision for the ages of these changes. The rapidly accumulating (up to 2–3 yr cm^?1, ～1310 yr old, 34 ¹⁴C dates) Danish profile offers an unprecedented high‐resolution record of climate change from a peat bog, and has effectively recorded a number of significant but short‐lived climate change events since ca. cal. yr AD 690. The longer time intervals between samples and the greater length of time resolved by each sample in the British site due to slower peat accumulation rates (up to 11 yr cm^?1, ～5250 yr old, 42 ¹⁴C dates) acted as a natural smoothing filter preventing the clear registration of some of the rapid climate change events. Not all the significant rises in water table registered in the peat bog archives of the British and Danish sites have been caused by solar forcing, and may be the result of other processes such as changes in other external forcing factors, the internal variability of the climate system or raised bog ecosystem. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

New Olivine Reference Material for In Situ Microanalysis     

Valentina G. Batanova  Jay M. Thompson  Leonid V. Danyushevsky  Maxim V. Portnyagin  Dieter Garbe‐Schnberg  Erik Hauri  Jun‐Ichi Kimura  Qing Chang  Ryoko Senda  Karsten Goemann  Catherine Chauvel  Sylvain Campillo  Dmitri A. Ionov  Alexander V. Sobolev 《Geostandards and Geoanalytical Research》2019,43(3):453-473

A new olivine reference material – MongOL Sh11‐2 – for in situ analysis has been prepared from the central portion of a large (20 × 20 × 10 cm) mantle peridotite xenolith from a ~ 0.5 My old basaltic breccia at Shavaryn‐Tsaram, Tariat region, central Mongolia. The xenolith is a fertile mantle lherzolite with minimal signs of alteration. Approximately 10 g of 0.5–2 mm gem quality olivine fragments were separated under binocular microscope and analysed by EPMA, LA‐ICP‐MS, SIMS and bulk analytical methods (ID‐ICP‐MS for Mg and Fe, XRF, ICP‐MS) for major, minor and trace elements at six institutions world‐wide. The results show that the olivine fragments are sufficiently homogeneous with respect to major (Mg, Fe, Si), minor and trace elements. Significant inhomogeneity was revealed only for phosphorus (homogeneity index of 12.4), whereas Li, Na, Al, Sc, Ti and Cr show minor inhomogeneity (homogeneity index of 1–2). The presence of some mineral and fluid‐melt micro‐inclusions may be responsible for the inconsistency in mass fractions obtained by in situ and bulk analytical methods for Al, Cu, Sr, Zr, Ga, Dy and Ho. Here we report reference and information values for twenty‐seven major, minor and trace elements.  相似文献   

Chemical and isotopic compositions of thermal springs,fumaroles and bubbling gases at Tacaná Volcano (Mexico–Guatemala): implications for volcanic surveillance     

Dmitri Rouwet  Salvatore Inguaggiato  Yuri Taran  Nicholas Varley  José A. Santiago S. 《Bulletin of Volcanology》2009,71(3):319-335

This study presents baseline data for future geochemical monitoring of the active Tacaná volcano–hydrothermal system (Mexico–Guatemala). Seven groups of thermal springs, related to a NW/SE-oriented fault scarp cutting the summit area (4,100m a.s.l.), discharge at the northwest foot of the volcano (1,500–2,000m a.s.l.); another one on the southern ends of Tacaná (La Calera). The near-neutral (pH from 5.8 to 6.9) thermal (T from 25.7°C to 63.0°C) HCO₃–SO₄ waters are thought to have formed by the absorption of a H₂S/SO₂–CO₂-enriched steam into a Cl-rich geothermal aquifer, afterwards mixed by Na/HCO₃-enriched meteoric waters originating from the higher elevations of the volcano as stated by the isotopic composition (δD and δ¹⁸O) of meteoric and spring waters. Boiling temperature fumaroles (89°C at ~3,600m a.s.l. NW of the summit), formed after the May 1986 phreatic explosion, emit isotopically light vapour (δD and δ¹⁸O as low as −128 and −19.9‰, respectively) resulting from steam separation from the summit aquifer. Fumarolic as well as bubbling gases at five springs are CO₂-dominated. The δ¹³C_CO2 for all gases show typical magmatic values of −3.6 ± 1.3‰ vs V-PDB. The large range in ³He/⁴He ratios for bubbling, dissolved and fumarolic gases [from 1.3 to 6.9 atmospheric ³He/⁴He ratio (R _A)] is ascribed to a different degree of near-surface boiling processes inside a heterogeneous aquifer at the contact between the volcanic edifice and the crystalline basement (⁴He source). Tacaná volcano offers a unique opportunity to give insight into shallow hydrothermal and deep magmatic processes affecting the CO₂/³He ratio of gases: bubbling springs with lower gas/water ratios show higher ³He/⁴He ratios and consequently lower CO₂/³He ratios (e.g. Zarco spring). Typical Central American CO₂/³He and ³He/⁴He ratios are found for the fumarolic Agua Caliente and Zarco gases (3.1 ± 1.6 × 10¹⁰ and 6.0 ± 0.9 R _A, respectively). The L/S (5.9 ± 0.5) and (L + S)/M ratios (9.2 ± 0.7) for the same gases are almost identical to the ones calculated for gases in El Salvador, suggesting an enhanced slab contribution as far as the northern extreme of the Central American Volcanic Arc, Tacaná.  相似文献   

Sill dynamics and fjord deep water renewal: Idealized modeling study     

Dmitri Leonov  Mitsuhiro Kawase 《Continental Shelf Research》2009

Fjord exchange circulation and its response to abrupt changes in forcing is examined by means of an idealized modeling experiment. Puget Sound, a fjord-type estuary in western North America (State of Washington), is the main context for this study. Parameters of the idealized model are representative of the entrance sill at Admiralty Inlet and the Main Basin of Puget Sound. Sensitivity to some of the model parameters relevant to a 3D realistic model is discussed. An idealized tidal forcing with fortnightly modulation drives a qualitatively realistic cycle of exchange circulation while the other boundary conditions are kept fixed in time. The cycle is characterized by fortnightly pulses of deep water intrusions with a sharp front at the leading edge and reversed circulation cells below the sill depth developing between the intrusions. This basic state is then perturbed and response of the circulation to abrupt changes in oceanic salinity and river discharge is examined.  相似文献   

Estimating thermal inflow to El Chichón crater lake using the energy-budget,chemical and isotope balance approaches     

Yuri Taran  Dmitri Rouwet 《Journal of Volcanology and Geothermal Research》2008

El Chichón crater lake appeared immediately after the 1982 catastrophic eruption in a newly formed, 1-km wide, explosive crater. During the first 2 years after the eruption the lake transformed from hot and ultra-acidic caused by dissolution of magmatic gases, to a warm and less acidic lake due to a rapid “magmatic-to-hydrothermal transition” — input of hydrothermal fluids and oxidation of H₂S to sulfate. Chemical composition of the lake water and other thermal fluids discharging in the crater, stable isotope composition (δD and δ¹⁸O) of lake water, gas condensates and thermal waters collected in 1995–2006 were used for the mass-balance calculations (Cl, SO₄ and isotopic composition) of the thermal flux from the crater floor. The calculated fluxes of thermal fluid by different mass-balance approaches become of the same order of magnitude as those derived from the energy-budget model if values of 1.9 and 2 mmol/mol are taken for the catchment coefficient and the average H₂S concentration in the hydrothermal vapors, respectively. The total heat power from the crater is estimated to be between 35 and 60 MW and the CO₂ flux is not higher than 150 t/day or ~ 200 gm^− 2 day^− 1.  相似文献   

On the spatial structure and dispersion of slow magnetosonic modes coupled with Alfvén modes in planetary magnetospheres due to field line curvature     

Dmitri Yu. Klimushkin  Pavel N. Mager 《Planetary and Space Science》2008,56(9):1273-1279

The structure of the slow mode coupled with Alfvén mode in the axially symmetric magnetosphere is studied in the paper. Due to the coupling, the slow magnetosonic wave gets dispersion across magnetic shells and becomes not strictly guided. The slow mode is found to be captured between the resonant and cutoff surfaces, where the wave vector radial component goes to infinity and to zero, accordingly. The resonant surface is farther from the Earth than the cutoff surface. The slow mode resonance frequency is much lower than the Alfvén resonance frequency due to small value of the sound velocity near the equator. The maximum of the slow mode amplitude expressed in terms of the parallel magnetic field is concentrated near the equator, but expressed in hydromagnetic terms is concentrated near the ionospheres.  相似文献   

Shallow virtual source redatuming by multi‐dimensional deconvolution          下载免费PDF全文

Joost van der Neut  Dmitri Alexandrov  Andrey Bakulin 《Geophysical Prospecting》2016,64(1):4-18

Recently, new on‐shore acquisition designs have been presented with multi‐component sensors deployed in the shallow sub‐surface (20 m–60 m). Virtual source redatuming has been proposed for these data to compensate for surface statics and to enhance survey repeatability. In this paper, we investigate the feasibility of replacing the correlation‐based formalism that undergirds virtual source redatuming with multi‐dimensional deconvolution, offering various advantages such as the elimination of free‐surface multiples and the potential to improve virtual source repeatability. To allow for data‐driven calibration of the sensors and to improve robustness in cases with poor sensor spacing in the shallow sub‐surface (resulting in a relatively high wavenumber content), we propose a new workflow for this configuration. We assume a dense source sampling and target signals that arrive at near‐vertical propagation angles. First, the data are preconditioned by applying synthetic‐aperture‐source filters in the common receiver domain. Virtual source redatuming is carried out for the multi‐component recordings individually, followed by an intermediate deconvolution step. After this specific pre‐processing, we show that the downgoing and upgoing constituents of the wavefields can be separated without knowledge of the medium parameters, the source wavelet, or sensor characteristics. As a final step, free‐surface multiples can be eliminated by multi‐dimensional deconvolution of the upgoing fields with the downgoing fields.  相似文献