Three-Dimensional Modeling of Shallow Shear-Wave Velocities for Las Vegas, Nevada, Using Sediment Type     

Barbara Luke  Helena Murvosh  Wanda Taylor  Jeff Wagoner 《中国地质大学学报(英文版)》2009,20(3)

A three-dimensional model of near-surface shear-wave velocity in the deep alluvial basin underlying the metropolitan area of Las Vegas, Nevada (USA), is being developed for earthquake site response projections. The velocity dataset, which includes 230 measurements, is interpolated across the model using depth-dependent correlations of velocity with sediment type. The sediment-type database contains more than 1 400 well and borehole logs. Sediment sequences reported in logs are assigned to one of four units. A characteristic shear-wave velocity profile b developed for each unit by analyzing closely spaced pairs of velocity profiles and well or borehole logs. The resulting velocity model exhibits reasonable values and patterns, although it does not explicitly honor the measured shear-wave velocity profiles. Site response investigations that applied a preliminary version of the velocity model support a two-zone ground-shaking hazard model for the valley. Areas in which clay predominates in the upper 30 m are predicted to have stronger ground motions than the rest of the basin.  相似文献   

The polycyclic aromatic hydrocarbon concentrations in soils in the Region of Valasske Mezirici, the Czech Republic     

Daniela Plachá  Helena Raclavská  Dalibor Matýsek  Mark H Rümmeli 《Geochemical transactions》2009,10(1):12-21

The polycyclic aromatic hydrocarbon (PAH) contamination of urban, agricultural and forest soil samples was investigated from samples obtained in the surroundings of Valasske Mezirici. Valasske Mezirici is a town located in the north-east mountainous part of the Czech Republic, where a coal tar refinery is situated. 16 PAHs listed in the US EPA were investigated. Organic oxidizable carbon was also observed in the forest soils. The PAH concentrations ranged from 0.86-10.84 (with one anomalous value of 35.14) and 7.66-79.39 mg/kg dm in the urban/agricultural and forest soils, respectively. While the PAH levels in the urban/agricultural soils are within the range typically found in industrialized areas, the forest soils showed elevated PAH concentrations compared to other forest soils in Western and Northern Europe. The PAH concentrations and their molecular distribution ratios were studied as functions of the sample location and the meteorological history. The soils from localities at higher altitudes above sea level have the highest PAH concentrations, and the PAH concentrations decrease with increasing distance from the town.  相似文献   

Climate variations,an overlooked factor influencing the recent marine environment. An example from Gullmar Fjord,Sweden, illustrated by benthic foraminifera and hydrographic data     

Helena?L.?FilipssonEmail author  Kjell?Nordberg 《Estuaries and Coasts》2004,27(5):867-881

Like most sill fjords, Gullmar Fjord on the Swedish west coast, is subject to periods of stagnation. Deep water is usually renewed annually, but since the late 1970s several low-oxygen events have been documented in the deepest part of the fjord. These events occurred during a time when the North Atlantic Oscillation (NAO) was in a highly positive phase. We investigated how the benthic environment, in the deepest part of the fjord, has varied during the 20th century, using benthic foraminifera and an extensive history of instrumental hydrographic data. The foraminifera have undergone one major faunal change and two minor modifications during this time. The major faunal change occurred in the late 1970s to early 1980s, when the common Skagerrak-Kattegat fauna was replaced by one dominated by the opportunistic, low-oxygen-tolerant species,Stainforthia fusiformis. This major faunal change appears to be related to the severe low-oxygen event in 1979–1980. In the latter part of the 1990s the fauna changed again; the concentration ofS. fusiformis was still high, but other low-oxygen-tolerant species also became important. This minor faunal modification occurred in connection with the 2-yr stagnation period between 1996 and 1998 when a low-oxygenevent evolved, the most severe recorded in Gullmar Fjord. Between 1930 and 1980, there was little faunal variation, and a stable fjord environment is indicated. During this time, negative NAO indexes dominated and climate was more continental, with an increase in winds from the northeast and east. In connection with a climate transition indicated by the NAO index switching from positive to negative, a minor faunal change occurred in the late 1920s to early 1930s: the concentration of the Skagerrak-Kattegat fauna increased markedly in the fjord. The fauna characterizing the positive NAO phase between 1900 and the late 1920s is very different from the present positive NAO fauna. The foraminiferal record laid down between approximately 1914 and 2001 indicates that between 1930 and 1980 Gullmar Fjord was a stable fjord environment. During the last 20 yr, it experienced conditions that were more fluctuating and changing. For the most part, changes in the foraminiferal fauna are caused by changes in the deep-water renewal, their extent and frequency, which in turn are caused by climatic oscillations.  相似文献   

Household routines—A time-space issue: A theoretical approach applied on the case of water and sanitation     

Helena Krantz   《Applied geography (Sevenoaks, England)》2006,26(3-4):227-241

The emerging chemical society and new political demands on improved ecological sustainability have put the urban water and sanitation system under pressure. It is recognised that the users need to partake in the problem solving, but to influence human practice we must understand it. A theoretical framework, founded on time-geography and cultural analysis, was developed and applied in a study on the interrelationship between changes in water and sanitation arrangements at the household level and residents’ routines. This article describes the theory cross-fertilisation and its prospect of application in studies of human environmental action.  相似文献   

The impact of environmental factors on the distribution pattern of aquatic plants along the Danube River corridor (Slovakia)     

Helena O&#x;aheov  Milan Valachovic   Richard Hrivnk 《Limnologica》2007,37(4):290-302

The aim of the study was to evaluate pattern of the aquatic macrophyte species distribution along the Danube fluvial corridor in Slovakia, and to identify the impact of environmental abiotic parameters on macrophyte species diversity. Field sampling was performed in the period 1999–2005 from the boat. Aquatic habitats were divided into 365 survey unit (SU). The survey of aquatic macrophytes and abiotic parameters followed the European standard approach EN 144184 2003. The plant mass estimate (PME – a semi-quantitative estimation of the amount of individual species in a SU, which takes into account three-dimensional development of plant stands) was estimated according to a five-point-scale in each SU; environmental pattern, were assessed over six abiotic parameters (river km, bank type, sediment type, flow velocity class, land-use type, and heavily man-modified water bodies). Altogether, four hydrologic connectivity types of aquatic habitats were distinguished: the Danube River, Open Arms, Separated Arms, and Seepage Water-bodies.

In total, 54 aquatic macrophytes were recorded for the whole data set of the Danube fluvial corridor. The PME data of true aquatic macrophytes and the length of SUs created a basis for numerical derivates, relative plant mass (RPM), mean mass indices (MMT, MMO) and the distribution ratio (d).

The results correspond with comparable studies on this topic: the highest macrophytes species diversity occurred in Separated Arms. On the contrary, macrophytes had the lowest richness in the Danube River main channel, although their diversity was slightly higher in heavily man-modified water bodies (such as the hydropower plant's reservoir and the abandoned main channel of the so-called Old Danube). Our results suggest that the lateral connectivity types of the river water bodies, primarily characterised by different hydrologic dynamics and human impact expressed as land-use types are responsible for the variability of aquatic macrophyte assemblages along the Danube corridor in Slovakia.  相似文献   

Sea-level changes during the Pleistocene-Holocene in the NW coastal zone of Portugal     

Helena Maria Granja  G. Soares de  Carvalho 《地学学报》1995,7(1):60-67

Research was undertaken to establish the present coastal dynamics of the area south of Espinho, Portugal, with special emphasis on the migration inland of beaches and the retreat of cliffs during at least the last century.
Besides the Holocene units (the Silvalde-Paramos tijuca Formation, 2310 ± 80 yr BP to 500 ± 80 yr BP, and the Cortegaca Beach Formation, 6850 ± 60 yr BP to 950 ± 80 yr BP), a Pleistocene unit (the Maceda Beach Formation, 29, 600 ± 690 yr BP to 14300 ± 160 yr BP) with trunks of Pinus sylvestris was recognized. The Cortegaca Beach Formation comprises a truncated podzol profile, the Al horizon dating from 3490 ± 60 yr BP to 950 ± 80 yr BP. The study and the dating of the Pleistocene and the Holocene formations suggest a model of evolution related to sea-level fluctuations and neotectonics, during the interval between 29,000 ± 690 yr BP and the post-XVth century (Little Ice Age).
The final purpose of the research is to apply the results to the prediction of the coastal zone evolution, and particularly to influence policy with respect to coastal zone management. This policy must take into account the inland migration of the beaches and the cliff retreat as a consequence of the natural dynamics of the earth that cannot be arrested or controlled by man.  相似文献   

SENSITIVITY OF THE RUSSIAN AGRICULTURE TO CHANGES IN CLIMATE, CO2 AND TROPOSPHERIC OZONE CONCENTRATIONS AND SOIL FERTILITY     

Oleg D. Sirotenko  Helena V. Abashina  Vera N. Pavlova 《Climatic change》1997,36(1-2):217-232

Russian agriculture sensitivity to changes in climate, soil and atmosphere chemistry were analyzed. Calculated data are presented on crop productivity of grain crops and grasses (C₃) under arid and humid scenarios of climate taking account of one-, two-, three and four-factor natural environment impacts. All four factors under studies (climatic parameters, CO₂ and tropospheric ozone concentrations, soil degradation extent) greatly impact agriculture productivity. The effect of interaction between all considered factors on agroecosystem productivity is studied. It is established that a simple additive scheme for explaining the complex effect of some factors can be much violated. In this case, not only variations in the mean crop yield levels but also variations in the degree of crop stability have been assessed in some regions, that may be more important for determining the social-economic consequences. It turned out that the recurrence of critically very low yields in steppe regions may increase two fold as a result of global warming.  相似文献   

Long-term TNT and DNT contamination: 1-D modeling of natural attenuation in the vadose zone: case study,Portugal     

Helena?I.?F.?AmaralEmail author  Ana Claúdia?Gama  Cláudia?Gon?alves  Judite?Fernandes  Maria?Jo?o?Batista  Manuela?Abreu 《Environmental Earth Sciences》2016,75(1):89

The vadose zone of a trinitrotoluene (TNT) and dinitrotoluene (DNT) contaminated site was investigated to assess the mobility of those explosives under natural conditions. Located in the left margin of the River Tejo Basin, Portugal, the site is located on unconsolidated sediments. Wastewaters associated with the 50-year explosives production were disposed in excavated ponds, from where water would infiltrate and pollute the unsaturated and saturated parts of the local aquifers. Two boreholes were drilled to 9 m depth in such a former waste pond to investigate the contaminant’s fate in the vadose zone. Sediment samples were taken every 1–2 m for analysis of the poly-nitroaromatics (p-NACs) and organic volatile compounds, pH, organic carbon content, cation exchange capacity and grain size analysis. The main contaminant was TNT representing >70 % of the total p-NACs concentration that peaked approximately 7 mg/kg in one borehole, even if the median in both boreholes was of ~1 mg/kg. DNT was 4–30 % of the total p-NACs and nitrotoluene (NT), up to 5 %. No other (volatile) organic compound was detected. The predominance of TNT as the main contaminant implies that any natural mass reduction has been inefficient to clean the site. Several 1-D model simulations of p-NACs cleaning of the vadose zone under natural conditions indicated that the most probable scenario of combined advection and partitioning will only remove TNT after 10’s of years, whereas DNT and NT will hardly be removed. Such low concentrations and long times for the p-NACs removal, suggest that by now those compounds have been washed-out to a level below standard limits.  相似文献   

A green space between life and death – a case study of activities in Gamlebyen Cemetery in Oslo,Norway     

Grete Swensen  Helena Nordh  Jan Brendalsmo 《Norsk geografisk tidsskrift. Norwegian journal of geography》2016,70(1):41-53

The amount of green space in urban areas is shrinking. Densification and the introduction of new user groups in most cities today is leading to more intensive use of public spaces and the need for more space. Urban cemeteries constitute a unique type of public space: while some may consider them primarily religious and contemplative spaces, others see them as primarily recreational or as heritage sites steeped in history. The authors examine the extent to which the pressure on cities’ open green areas combined with influences from intercultural encounters is mirrored in the use and character of cemeteries today – exemplified by Gamlebyen Cemetery (Gamlebyen Gravlund) in Oslo, Norway. They used observations in combination with short semi-structured interviews with those using the cemetery. The findings of pilot study conducted in 2013 suggest that religious aspects played a minor role and that the recreational aspects were more important to most of the interviewees. Many of them considered that the cemetery provided a pleasant green walkway on their way to work, busses or city services. The cemetery offered a combination of calmness, an aesthetically pleasant environment, and ‘cultivated nature’ in an urban context, and was thus an arena that invited respect and esteem.  相似文献   

Evolving coastal character of a Baltic Sea inlet during the Holocene shoreline regression: impact on coastal zone hypoxia     

Wenxin Ning  Anupam Ghosh  Tom Jilbert  Caroline P. Slomp  Mansoor Khan  Johan Nyberg  Daniel J. Conley  Helena L. Filipsson 《Journal of Paleolimnology》2016,55(4):319-338

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