Engineering Geological Map of the Sakha （Yakutia） Republic     

Vladimir B. Spektor  Yaroslav I. Torgovkin  Alena A. Shestakov  Valentin V. Spektor  Lena D. Ivanov  Boris M. Kozmin 《寒旱区科学》2014,6(5):0484-0493

The Engineering Geological Map of the Sakha（Yakutia） Republic covers about 3 million kilometers which is one-fifth of the territory of Russia.The map displays ground and geocryological conditions and active faults.Seismic intensity,schemes of zoning by factors of engineering geological conditions,and the general scheme of engineering geological zoning of the Sakha（Yakutia） Republic or the SR（Y）,are shown on the inset maps.The map is required to provide information for planning,construction and exploitation of engineering structures in the SR（Y）.A distinguishing feature of the map is the indication of almost blanket distribution of the frozen ground class.Types of the frozen ground class are separated by lithology,while ground varieties are separated by temperature.Fresh and ultra-fresh suprapermafrost water is predominant within the territory.The compiled map indicates parts of the Arctic-Asian and Baikalo-Stanovoi planetary seismic belts that make engineering geological conditions more complicated.  相似文献   

Temporal and spatial trends of total petroleum hydrocarbons in the seawater of Bohai Bay, China from 1996 to 2005     

Ye Li  Shitao Peng  Lena Q. Ma 《Marine pollution bulletin》2010,60(2):238-243

The temporal and spatial distribution of total petroleum hydrocarbons (TPH) in the seawater of Tianjin Bohai Bay during 1996-2005 was investigated for the first time. TPH concentrations in 480 seawater samples collected from 16 stations during a 10-year span were quantified by ultra-violet fluorescence spectroscopy. Petroleum hydrocarbons were ubiquitous in the seawater, and their concentrations were highly variable, ranging from 23.7 to 508 μg L⁻¹. TPH concentrations in the seawater varied with seasons, showing a decreasing order of winter > spring > summer. Over the 10-year period, TPH at all stations steadily decreased. The highest values obtained were at stations near the port areas and Dagu outfall where shipping activities and land-based waste water discharges were the major sources of pollution. Our results provided the background information on the extent of TPH contamination in the seawater and highlighted the need to further control TPH pollution in Tianjin Bohai Bay.  相似文献   

Anthropogenic influence on the degradation of an urban lake - The Pampulha reservoir in Belo Horizonte, Minas Gerais, Brazil     

Kurt Friese  Gerald Schmidt  Jorge Carvalho de Lena  Dieter W. Zachmann 《Limnologica》2010,40(2):114-125

The artificial reservoir Lagoa da Pampulha in central Brazil has been increasingly affected by sediment deposition and pollution from urban and industrial sources. This study investigates water chemistry and heavy metal concentrations and their fractionation in the lake sediment using ICP-OES, ICP-MS, and XRD analyses. Fractionation analysis was done by sequential extraction under inert gas as well as after oxidation. The lake exhibits a permanent stratification with an oxygen-free hypolimnion below 2 m depth. Nutrient concentrations are enriched for phosphorous components (SRP, PO₄). In the sediment it was not possible to detect oxygen. Carbon, sulfur, and most of the analyzed heavy metals are enriched in the top sediment layer with a pronounced downward decrease, indicating the presence of an anthropogenic influence. Statistical analysis, including correlations and a Principal Component Analysis (PCA) of depth-related total concentration data, helps to distinguish presumably anthropogenic heavy metals from geogenic components. Some samples with high element concentrations in the sediment also show elevated concentrations in their pore water. Analyses of element distribution between sediment and pore water suggest a strong bonding of heavy metals to the anoxic sediment. The trend towards elevated solubility in the pore water of oxidized samples is clear for most of the analyzed elements. Fractionation analysis reveals characteristic associations of selected elements to specific mineral bonding forms. In addition, it indicates that the behavior of heavy metals in the sediment is strongly influenced by organic substances. These substances provide buffering against oxidation, acidification, and metal release. The high nutrient loading causes reducing conditions in the lake sediment. These conditions trigger the accumulation of sediments rich in S²⁻, which stabilizes the fixation of heavy elements. In the future, care must be taken to reduce the supply of contaminants and to prevent the release of heavy metals from sediments dredged for remediation purposes.  相似文献   

Climate change, patch choice, and intensification at Pont d'Ambon (Dordogne, France) during the Younger Dryas     

Emily Lena Jones   《Quaternary Research》2009,72(3):371-376

This paper considers the impact of the Younger Dryas on the prehistoric inhabitants of Pont d'Ambon, a site in the Dordogne region of southwestern France, through an examination of the zooarchaeological remains from this site. An investigation of patch choice indicates that patch choice evenness declines during the Younger Dryas due to increasing local dominance of the grassland patch. Analyses of demographic composition, cutmark frequency, and marrow processing in the wild European rabbit (Oryctolagus cuniculus) assemblage suggest intensified rabbit use during this period. This study thus supports the hypothesis that changing climate had significant impacts on the prehistoric inhabitants of Pont d'Ambon. However, the traditional climate hypothesis—that changing climate negatively impacted the availability of larger fauna, forcing a switch to smaller, lower-ranked prey items—is not supported here. The inhabitants of Pont d'Ambon seem to have adapted to changing climate by efficiently exploiting the new species available to them, and possibly, during the Younger Dryas, by intensifying their use of one of these new species, the European rabbit.  相似文献   

Detailed geomorphological survey of a small mountain drainage area, Abisko, northern Swedish Lapland     

Lena Rubensdotter 《Geografiska Annaler: Series A, Physical Geography》2002,84(3-4):267-273

A thorough geomorphological survey of a small (2km²) drainage area has been conducted using digital magnification of aerial photographs in conjunction with field visits. The result presented is a geomorphological map where individual geomorphological features down to metre size can be identified. The study was done in connection with a project focusing on the relationship between geomorphological processes and lacustrine sedimentation. Good knowledge of the geomorphological setting and the related process activity in the catchment is important in studies using lacustrine sediments as environmental archives.
The survey reveals a small–scale geomorphology dominated by a number of different periglacial upfreezing forms together with bedrock–controlled slope processes. Three different geographically separated geomorphological assemblages were recognised with few sediment transportation pathways connecting them. Composition of substrate, soil water content and vegetation cover combined with different slope angles are probably the most important factors controlling the distribution of the geomorphological features.  相似文献   

The role of water in the 1944 Vesuvius eruption     

Daniela Dolfi  Raffaello Trigila 《Contributions to Mineralogy and Petrology》1978,67(3):297-304

The P-T path of magma associated with the 1944 Vesuvius eruption has been outlined on the basis of probe mineralogy and the relationships between the crystallising phases. Equilibrium P-T values, obtained from the reactions:

1. CaMgSi₂O_6(liq) = CaMgSi₂O_6(cpx)
2. NaAlSi₃O_{8 (liq)} = NaAlSi₃O_{8 (plag)}
3. CaAl₂Si₂O_{8 (plag)}=CaAl₂SiO_6(cpx)+SiO_2(liq) have been established for three intracrustal crystallisation stages: I) 8.0 kbar and 1255 °C; II) 4.0 kbar and 1178 °C; III) 0.5 kbar and 1105 °C.

The H₂O content in the magma has been estimated from an experimental calibration of \(a_{^{CaMgSi_2 O_6 } }^{liq}\) as a function of \(X_{H_2 O}^{liq}\) at P _tot = 2 kbar. The estimated water contents of the magma for the three stages, I) 0.7%; II) 0.9%; III) 1.1%, are consistent with the pattern of activity of the 1944 Vesuvius eruption and with the relationship between the lavas. The shallow depth of H₂O-saturation of the magma, 0.24 kbar at 1100 °C, is consistent with the eruption sequence of lava flows followed by lava fountain activity.  相似文献   

Pyroclastic deposits as a guide for reconstructing the multi-stage evolution of the Somma-Vesuvius Caldera   总被引：1，自引：0，他引：1  

Raffaello Cioni  Roberto Santacroce  Alessandro Sbrana 《Bulletin of Volcanology》1999,61(4):207-222

 The evolution of the Somma-Vesuvius caldera has been reconstructed based on geomorphic observations, detailed stratigraphic studies, and the distribution and facies variations of pyroclastic and epiclastic deposits produced by the past 20,000 years of volcanic activity. The present caldera is a multicyclic, nested structure related to the emptying of large, shallow reservoirs during Plinian eruptions. The caldera cuts a stratovolcano whose original summit was at 1600–1900 m elevation, approximately 500 m north of the present crater. Four caldera-forming events have been recognized, each occurring during major Plinian eruptions (18,300 BP "Pomici di Base", 8000 BP "Mercato Pumice", 3400 BP "Avellino Pumice" and AD 79 "Pompeii Pumice"). The timing of each caldera collapse is defined by peculiar "collapse-marking" deposits, characterized by large amounts of lithic clasts from the outer margins of the magma chamber and its apophysis as well as from the shallow volcanic and sedimentary units. In proximal sites the deposits consist of coarse breccias resulting from emplacement of either dense pyroclastic flows (Pomici di Base and Pompeii eruptions) or fall layers (Avellino eruption). During each caldera collapse, the destabilization of the shallow magmatic system induced decompression of hydrothermal–magmatic and hydrothermal fluids hosted in the wall rocks. This process, and the magma–ground water interaction triggered by the fracturing of the thick Mesozoic carbonate basement hosting the aquifer system, strongly enhanced the explosivity of the eruptions. Received: 24 November 1997 / Accepted: 23 March 1999  相似文献   

Changes in eruptive style during the A.D. 1538 Monte Nuovo eruption (Phlegrean Fields, Italy): the role of syn-eruptive crystallization     

Claudia D’Oriano  Elisa Poggianti  Antonella Bertagnini  Raffaello Cioni  Patrizia Landi  Margherita Polacci  Mauro Rosi 《Bulletin of Volcanology》2005,67(7):601-621

The Monte Nuovo eruption is the most recent event that occurred at Phlegrean Fields (Italy) and lasted from 29 September to 6 October 1538. It was characterized by 2 days of quasi-sustained phreatomagmatic activity generating pumice-bearing pyroclastic density currents and forming a 130-m-high tuff cone (Lower Member deposits). The activity resumed after a pause of 2 days with two discrete Vulcanian explosions that emplaced radially distributed, scoria-bearing pyroclastic flows (Upper Member deposits). The juvenile products of Lower and Upper Members are, respectively, phenocryst-poor, light-coloured pumice and dark scoria fragments with K-phonolitic bulk compositions, identical in terms of both major and trace elements. Groundmass is formed by variable proportions of K-feldspar and glass, along with minor sodalite and Fe-Ti oxide present in the most crystallized samples. Investigations of groundmass compositions and textures were performed to assess the mechanisms of magma ascent, degassing and fragmentation along the conduit and implications for the eruptive dynamics. In pumice of the Lower Member groundmass crystal content increases from 13 to 28 vol% from the base to the top of the sequence. Products of the Upper Member consist of clasts with a groundmass crystal content between 30 and 40 vol% and of totally crystallized fragments. Crystal size distributions of groundmass feldspars shift from a single population at the base of the Lower Member to a double population in the remaining part of the sequence. The average size of both populations regularly increases from the Lower to the Upper Member. Crystal number density increases by two orders of magnitude from the Lower to the Upper Member, suggesting that nucleation dominated during the second phase of the eruption. The overall morphological, compositional and textural data suggest that the juvenile components of the Monte Nuovo eruption are likely to record variations of the magma properties within the conduit. The different textures of pumice clasts from the Lower Member possibly reflect horizontal gradients of the physical properties (P, T) of the ascending magma column, while scoriae from the second phase are thought to result from the disruption of a slowly rising plug crystallizing in response to degassing. In particular, crystal size distribution data point to syn-eruptive degassing-induced crystallization as responsible for the transition in eruptive style from the first to the second phase of the eruption. This mechanism not only has been proved to profoundly affect the dynamics of dome-forming calc-alkaline eruptions, but may also have a strong influence in driving the eruption dynamics of alkaline magmas of intermediate to evolved compositions.Editorial responsibility: J. Donnelly-Nolan  相似文献   

Potassic primary melts of Vulsini (Roman Province): evidence from mineralogy and melt inclusions     

Vadim Kamenetsky  Nicole Métrich  Raffaello Cioni 《Contributions to Mineralogy and Petrology》1995,121(3):336-336

The online version of the original article can be found at  相似文献   

Arsenic in the groundwater of Ouro Preto (Brazil): its temporal behavior as influenced by the hydric regime and hydrogeology     

José Augusto Costa Gonçalves  Jorge Carvalho de Lena  José Fernando Paiva  Hermínio Arias Nalini Jr  Janice Cardoso Pereira 《Environmental Geology》2007,53(4):785-793

In the city of Ouro Preto (MG), water catchment for public supply originates from superficial drainage, springs, old abandoned mines and some driven wells. In the rocks of the region, As is originally found in gold-enriched sulphide-bearing mineral deposits. The weathering process introduces As into the hydrological system by dissolution of this element into the leachate. Measurement of the As content in the groundwater of some catchments was carried out during 1 year and these measurements demonstrated high As content—up to 224 μg L⁻¹ of As(V)—during the rainy season (the maximum concentration limit according to World Health Organization is 10 μg L⁻¹). Lower values were observed during the dry season and in some sampling stations, As was not even detected. The As concentration variability during 1 year shows a strict and direct relationship to seasonal and hydrological conditions. For city authorities, responsible for public water supply, it is necessary to perform a complete inventory of the water sources used and constantly monitor the As content in the water.  相似文献