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排序方式: 共有106条查询结果,搜索用时 17 毫秒
21.
Assessment of the effects of a marine urban outfall discharge on caged mussels using chemical and biomarker analysis 总被引:1,自引:0,他引:1
de los Ríos A Juanes JA Ortiz-Zarragoitia M López de Alda M Barceló D Cajaraville MP 《Marine pollution bulletin》2012,64(3):563-573
To assess the presence of endocrine disruptors in treated marine outfall discharges and their possible effects, mussels (Mytilus galloprovincialis) were caged in the environmental mixing zone of the outfall of the Santander sanitation system and in one control area. After 30, 60 and 90 days, samples were collected to perform chemical analyses (metals, anionic surfactants, alkylphenols, bisphenol A, phthalates and estrogenic hormones), biomarkers of general stress (lysosomal membrane stability-LMS, histopathology) and biomarkers of endocrine disruption (vitellogenin-like proteins and gonad index). There were no significant differences between outfall and control sites on contaminant levels, except for 4-tert-octylphenol which was higher in the outfall site. Bacteriological counts were higher in the outfall area. No relevant differences in biomarkers were detected between treated and control mussels. A significant reduction in LMS occurred in both groups after 90 days caging, indicating a stress situation possibly related to caging or to post-spawning reproductive state. 相似文献
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We use an analytical model for the post-injection spreading of a plume of CO2 in a saline aquifer under the action of buoyancy and capillary trapping to show that the spreading behavior is at all times
strongly influenced by the shape of the plume at the end of the injection period. We solve the spreading equation numerically
and confirm that, at late times, the volume of mobile CO2 is given by existing asymptotic analytical solutions. The key parameters governing plume spreading are the mobility ratio,
M, and the capillary trapping number, Γ—the former sets the shape of the plume at the end of the injection period, and the latter sets the amount of trapping. As
a quantitative measure of the dependence of the spreading behavior on the initial shape, we use a volume ratio. That is, we
evolve the plume from a true end-of-injection initial shape and also from an idealized “step” initial shape, and we take the
ratio of these mobile plume volumes in the asymptotic regime. We find that this volume ratio is a power-law in M, where the exponent is governed exclusively by Γ. For conditions that are representative of geologic CO2 sequestration, the ratio of mobile volumes between “true” and “step” initial plume shapes can be 50% or higher. 相似文献
24.
Maria C. Arango Fleur O. Strasser Julian J. Bommer Ruben Boroschek Diana Comte Hernando Tavera 《Journal of Seismology》2011,15(1):19-41
Earthquake hazard along the Peru–Chile subduction zone is amongst the highest in the world. The development of a database
of subduction-zone strong-motion recordings is, therefore, of great importance for ground-motion prediction in this region.
Accelerograms recorded by the different networks operators in Peru and Chile have been compiled and processed in a uniform
manner, and information on the source parameters of the causative earthquakes, fault-plane geometries and local site conditions
at the recording stations has been collected and reviewed to obtain high-quality metadata. The compiled database consists
of 98 triaxial ground-motion recordings from 15 subduction-type events with moment magnitudes ranging from 6.3 to 8.4, recorded
at 59 different sites in Peru and Chile, between 1966 and 2007. While the database presented in this study is not sufficient
for the derivation of a new predictive equation for ground motions from subduction events in the Peru–Chile region, it significantly
expands the global database of strong-motion data and associated metadata that can be used in the derivation of predictive
equations for subduction environments. Additionally, the compiled database will allow the assessment of existing predictive
models for subduction-type events in terms of their suitability for the Peru–Chile region, which directly influences seismic
hazard assessment in this region. 相似文献
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In this paper we extend to three-phase flow the nonequilibrium formalism proposed by Barenblatt and co-workers for two-phase porous media flow. The underlying idea is to include nonequilibrium effects by introducing a pair of effective water and gas saturations, which are linked to the actual saturations by a local evolution equation. We illustrate and analyze how nonequilibrium effects lead to qualitative and quantitative differences in the solution of the three-phase flow equations. 相似文献
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28.
Optimal Stopping Location of a High Speed Train using GIS and Multicriteria Decision‐making 下载免费PDF全文
This article develops a methodology using a Geographical Information System (GIS) to evaluate the best location to stop a high speed passenger train when faced with an undesired event. The proposed method is based on multicriteria decision‐making where different stretches of line which could be chosen as the stopping point are ranked depending on the characteristics of the line, the surrounding area and its accessibility for equipment. The method was integrated into the GIS to develop an expert support system for decision makers faced with different kinds of undesired events. It has been applied to a case study on the high speed line between Valladolid and Madrid (Spain). The proposed method is new and has not previously been applied to high speed railway networks and could be adapted to other case studies. The speed of the algorithm provides an almost instantaneous reply within seconds of an emergency situation occurring. The method can therefore be part of an overall support system for decision making in undesired rail events. 相似文献
29.
Annelie Skoog Ruben Lara Gerhard Kattner 《Deep Sea Research Part I: Oceanographic Research Papers》2001,48(12):217
Dissolved organic nitrogen (DON), dissolved organic carbon (DOC) and inorganic nutrient concentrations were determined in samples from an area encompassing the Northeast Water Polynya from June to August 1993. In June, still ice-covered polynya area surface waters (PySW) had significantly higher (p<0.05) DOC concentrations (110 μM, n=68) than surface water outside the polynya area (96 μM, n=6). Melting ice and ice algae are suggested as DOC sources. DOC concentrations found in this study are consistent with other studies showing higher DOC concentrations in the Arctic than in other ocean areas. As the productive season progressed, DOC concentrations in Polynya surface water (PySW) decreased (p<0.05) from 110 to 105 μM, while DON concentrations increased (p<0.05) from 5.6 to 6.1 μM, causing a significant decrease (p<0.05) in the C : N ratios of DOM from spring (C : N ratio 20) to summer (C : N ratio 17). We found a significant (p<0.05) decrease in the DOM C : N ratio in all water masses within the polynya area as the productive season progressed. DON was the largest fraction of total dissolved nitrogen (TDN) in PySW and surface waters outside the polynya area. TDN was calculated as the sum of DON, nitrate, nitrite and ammonium concentrations. DON increased (p<0.05) from 62% to 73% of TDN in PySW from spring to summer, a result of increasing DON concentrations and decreasing inorganic nitrogen concentrations over the productive season. The seasonal accumulation of DON and the corresponding decrease in nitrate concentrations in waters with primary production indicate that it is important to take the DON pool into account when estimating export production from nitrate concentration decreases in surface waters. PySW TDN concentrations decreased (p<0.05) from 9.1 (n=61) to 8.6 μM (n=60) from spring (May 25 through June 19) to summer (July 1 through July 27). The seasonal decrease in surface water TDN concentrations corresponded to increases in TDN concentrations in deeper water masses within the Polynya. Most of the TDN increase in deep water was in the form of DON. A possible explanation is that PON was dissolved (partially remineralized) in the water column at mid depths, causing increases in the DON concentration. Transfer of N from PySW (with a short residence time in the polynya area) to Polynya Intermediate Water and deep waters of the Norske and Westwind Trough with multi-year residence times keeps N from leaving the polynya area. In spring, nutrients from degradation of OM in PyIW could support primary production. The role of PyIW as an OM trap could be important in supporting primary production in the polynya area. 相似文献
30.
M. Cristina Fossi Letizia Marsili Giancarlo Lauriano Caterina Fortuna Simone Canese Stefania Ancora Claudio Leonzio Teresa Romeo Ruben Merino Esteban Abad Begoa Jimnez 《Marine environmental research》2004,58(2-5):269
Various studies have revealed high concentrations of contaminants such as organochlorines (OCs) and heavy metals in Mediterranean cetaceans. A geographical trend of contamination (PCBs and DDTs) has been found for striped dolphin (Stenella coeruleoalba). In this study we used a non-lethal approach (skin biopsy) to investigate bioaccumulation of OCs, including polychlorobiphenyls (PCBs), DDTs, polychlorodibenzo-p-dioxins (PCDDs), polychlorodibenzofurans (PCDFs), trace elements (Hg, Cd, Pb) and CYP1A activity (BPMO) in nine striped dolphins sampled in the Aeolian area (Sicily – Italy) in summer 2002. The arithmetic mean value of BPMO activity in this group was 43.46 AUF/g tissue/h. This value is approximately 3 times and 5 times lower, respectively, than the value found in the Ionian and in the Ligurian groups. Skin biopsies of striped dolphins emerged as a suitable material for assessing the toxicological status of the various Mediterranean groups. 相似文献