共查询到20条相似文献，搜索用时 31 毫秒
1.
Duncan Leadbitter 《Marine pollution bulletin》1996,33(7-12):269-272
Sydney's sewage disposal problems have been the catalyst for wider questioning by the community about the management of the water cycle in the Sydney Basin. Public concern over the deepwater ocean outfalls generated an involvement in the Environmental Monitoring Programme (EMP) which provided a number of insights into the marine environment offshore Sydney, interactions between agencies and the role of public interest groups. The EMP has not provided sufficient information to make decisions about the value of higher levels of treatment. However, public interest in these outfalls is being subsumed by demands for the greater recycling of water and mechanisms for reducing water use. 相似文献
2.
The discharge of sewage to the ocean can be an issue of public and scientific concern. Such has been the case in Sydney over at least the past 25 years. In this paper, the history of Sydney's sewage discharge is outlined, and the decisions taken to address concerns about the environmental effects of shoreline discharge of large volumes of primary treated sewage effluent are described. Design criteria are described for deepwater outfall systems that, since 1990–1991, have discharged 80% of Sydney's sewage after primary treatment at North Head, Bondi and Malabar Sewage Treatment Plants (STP). The integrated elements of a comprehensive five year Environmental Monitoring Programme (EMP) are set out. Other papers in this volume describe the result of EMP component studies. The five year EMP was designed to provide the basis to assess the environmental performance of the new deepwater outfall systems during the first two years of their operation and to provide a baseline against which further change may be measured. 相似文献
3.
The Environmental Specimen Bank (es-BANK) for Global Monitoring at the Center for Marine Environmental Studies, Ehime University, Japan has more than four decades of practical experience in specimen banking. Over the years, es-BANK has archived specimens representing a wide range of environmental matrices, i.e. fishes, reptiles, birds, aquatic mammals, terrestrial mammals, human, soils, and sediments. The samples have been collected as part of the various monitoring programs conducted worldwide. The current review is a summary of selected studies conducted at the Center for Marine Environmental Studies, on temporal and spatial trends of legacy and emerging contaminants in the marine environment. One of the major conclusions drawn from the studies is that environmental problems are no more regional issues and, thus, environmental specimen banking should not be limited to national boundaries, but should have a global outlook. 相似文献
4.
Toxic effects on macroalgae have been compiled. Eighty-two articles have been found in literature during 1959-2000. A total of 120 substances were investigated using 65 different macroalgae species. About one-third of the tested compounds were organic substances (33%), another third metal-organic substances (35%), and the last third were oils (14%), metals (8%), detergents (7.5%) and other inorganic chemicals (2.5%). Half of the substances were only tested once on a single species. Likewise, toxicity data has only been reported for one chemical tested on a single occasion for about half of the 65 species. Thus little is known about the toxic effects on marine macroalgae. The objectives of the previous studies undertaken varied and therefore the toxicity data was presented in numerous ways, e.g. using different exposure times, temperature, light intensity, light regime, salinity, and nutrients, which makes a direct comparison of the data difficult. This review also shows that many stages in the lifecycle of macroalgae are often more sensitive to toxic substances than other aquatic organisms. Consequently, tests using macroalgae may discover toxicity earlier, which would in turn also protect the fauna. If toxic compounds have a negative affect on the distribution and growth of structurally and functionally dominating macroalgae, there may indirectly be a large and harmful influence on the whole marine coastal ecosystem. For this reason tests on macroalgae should be included in control programs along the coasts. 相似文献
5.
Everhard Muyzert 《Geophysical Prospecting》2018,66(8):1535-1547
Autonomous marine vehicles instrumented with seismic sensors allow for new efficient seismic survey designs. One such design is the swarm survey, where a group, or swarm, of slow moving autonomous marine vehicles record seismic data from shots fired by a source vessel sailing around circles within the swarm. The size of the swarm is dictated by the maximum offset requirement of the survey, and it can be shaped to acquire wide‐ and full‐azimuth data. The swarm survey design equation describes the relationship between the source and receiver positions of the survey and the subsurface coverage or fold. It is used to adapt the swarm to the seismic survey requirements and to calculate survey duration time estimates as function of available equipment. It is shown that a survey conducted by a slowly moving swarm requires six times fewer shots than an equivalent seabed node survey conducted over 85.5 km2. Swarm surveys can also be adapted to efficiently conduct infill surveys and replace multi‐vessel undershoots. The efficiency of the survey can further be increased when the autonomous marine vehicles are towing short streamers with multiple receivers. Synthetic tests show that the seismic images for swarm surveys are comparable to those from streamer surveys, while little variation in image quality is found when reducing the number of autonomous marine vehicles but equipping them with a short streamer with multiple receivers. 相似文献
6.
A five year Environmental Monitoring Programme (EMP) was set up in east-Australian coastal waters to determine the environmental effects of diverting most of Sydney's primary treated sewage from cliff face outfalls to diffuser outfall systems some 3 km offshore in 60–80 m of water. Many component EMP studies adopted Before and After Control Impact (BACI and ‘beyond BACI’) designs, to isolate outfall impacts on the marine ecosystem from background variability. Although seasonal patterns dominated ambient conditions in coastal waters, long-term climatic signals, such as the El Nino Southern Oscillation (ENSO), were apparent during the EMP. The Southern Oscillation Index (SOI) indicated the two year post-commissioning study period of 1991–1993 was dominated by an El Nino episode, while the 1989–1990 pre-commissioning period experienced a La Nina episode. Anomalous rainfall conditions and ocean temperature structure were associated with these episodes with respect to long-term records. Rainfall patterns suggested that the pre-commissioning period experienced high rainfall causing an increased incidence of stormwater pollution in coastal waters. Effects of the lower rain levels during post-commissioning phase were, however, outweighed by the dramatic improvements due to the commissioning of the deepwater outfalls. Decreased thermal stratification was experienced during the winter months of the 1992–1993 El Nino episode, and promoted increased dilutions associated with a greater frequency in sewage plume surfacing. There was, however, no apparent short-term effect of this change in plume behaviour on the marine environment as measured by EMP indicators. 相似文献
7.
海洋天然气水合物资源调查中,电磁法已成为地震勘探最有效的补充手段之一,而我国海洋水合物电磁探测中的拖曳式电场接收机此前是空白.本文从方法原理、仪器设备和海洋试验等方面,对海洋拖曳式水平电偶极-偶极方法进行研讨.建立三维电阻率模型,进行数值模拟,讨论收发距、发射频率、拖曳装置离海底高度等参数与电场异常响应的关系,针对特定模型给出了最佳观测参数以指导仪器硬件设计与海洋测试.在此基础上,采用高级嵌入式计算机的智能化控制、前端低噪声斩波放大、高精度同步采集等技术,研制了由拖体、承压舱、采集电路、低噪声电场传感器等组成的海洋拖曳式水平轴向电场接收机,其系统噪声达到2 nV/√HZ
@(1~100Hz).将自主研制的电场接收机用于国内首次拖曳式电偶极-偶极方法的海洋试验与评估,并对海试资料进行了处理与分析.研究结果表明,所研发的仪器达到了设计指标,能够用于海洋天然气水合物调查. 相似文献
8.
Yoann Le Bars Valentin Vallaeys Éric Deleersnijder Emmanuel Hanert Loren Carrere Claire Channelière 《Ocean Dynamics》2016,66(4):589-603
With the second largest outflow in the world and one of the widest hydrological basins, the Congo River is of a major importance both locally and globally. However, relatively few studies have been conducted on its hydrology, as compared to other great rivers such as the Amazon, Nile, Yangtze, or Mississippi. The goal of this study is therefore to help fill this gap and provide the first high-resolution simulation of the Congo river-estuary-coastal sea continuum. To this end, we are using a discontinuous-Galerkin finite element marine model that solves the two-dimensional depth-averaged shallow water equations on an unstructured mesh. To ensure a smooth transition from river to coastal sea, we have considered a model that encompasses both hydrological and coastal ocean processes. An important difficulty in setting up this model was to find data to parameterize and validate it, as it is a rather remote and understudied area. Therefore, an important effort in this study has been to establish a methodology to take advantage of all the data sources available including nautical charts that had to be digitalized. The model surface elevation has then been validated with respect to an altimetric database. Model results suggest the existence of gyres in the vicinity of the river mouth that have never been documented before. The effect of those gyres on the Congo River dynamics has been further investigated by simulating the transport of Lagrangian particles and computing the water age. 相似文献
9.
DENG Shenghui LU Yuanzheng & XU Daoyi . Research Institute of Petroleum Exploration Development Beijing China . Key Laboratory of Oil Gas Reservoir of PetroChina Beijing China . China University of Geosciences Beijing China . Institute of Geology China Earthquake Administration Beijing China 《中国科学D辑(英文版)》2005,48(12):2049-2060
The pioneering studies by Newell[1,2] about 40 years ago and the statistical work of Raup and Sepkoski[3] have made the end-Triassic mass extinction event of marine organisms gradually familiar to the geologists. Evidences of considerable extinction have been ob- tained both in the terrestrial and marine ecosystems[4―10]. Based on the database of Benton[11], 61 of the 257 sta-tistic animal families which lived in the Late Triassic and Early Jurassic disappeared within or at the end of the … 相似文献
10.
Geochemical analysis of fine grained (<20 μm) tephra found in ice cores is inherently difficult, due to the typically low number and small size of available particles. Ice core tephra samples require specialized sample preparation techniques to maximize the amount of information that can be gained from these logistically limited samples that may provide important chronology to an ice record, as well as linking glacial, marine and terrestrial sediments. We have developed a flexible workflow for preparation of tephra and cryptotephra samples to allow accurate and robust geochemical fingerprinting, which is fundamental to tephrochronology. The samples can be prepared so that secondary electron imagery can be obtained for morphological characterization of the samples to ensure that the sample is tephra-bearing and then the sample can be further prepared for quantitative electron microprobe analysis using wavelength dispersive techniques (EMP-WDS), scanning electron microscopy with energy dispersive spectrometry (SEM-EDS), laser ablation inductively coupled mass spectrometry (LA-ICP-MS) or secondary ion mass spectrometry (SIMS). Some samples may be too small for typical instrumentation conditions to be used (i.e. 20 μm beam on the EMP) to analyze for geochemistry and we present other techniques that can be employed to obtain accurate, although less precise, geochemistry. Methods include analyzing unpolished tephra shards less than 5 μm in diameter with a 1 μm beam on an SEM; using the “broad beam overlap” EMP method on irregular particles less than 20 μm in diameter, and analyzing microlitic shards as well as aphyric shards using EMP to increase the number of analyzed shards in low abundance tephra layers. The methods presented are flexible enough to be employed in other geological environments (terrestrial, marine and glacial) which will help maximize and integrate multiple environments into the overall tephra framework. 相似文献
11.
Stachowitsch M 《Marine pollution bulletin》2003,46(7):801-805
It is proposed that a new, fifth era should be added to the four historical phases of marine research identified by Rupert Riedl, specifically an era devoted to studying and ameliorating disturbed marine ecosystems. In an age of global environmental deterioration, many marine ecosystems and organisms are high on the list of threatened entities. This poor status prompts research that would otherwise have been unnecessary and hinders research that would normally have been conducted. I argue that research into intact marine ecosystems is becoming increasingly difficult, and that most of our future insights into marine habitats will stem from knowledge gained by examining various disfunctions of those systems rather than their functions. The new era will therefore differ from past research in its underlying aim, the range of topics studied, the selection and funding of those topics, the validity of its conclusions, and in its urgency. Sea turtles and cetaceans are cited as case studies at the organismic level, shallow-water benthic communities, including coral reefs, at the ecosystem level. 相似文献
12.
Hiroshi Kobayashi Keiichi Tamura Shunsuke Tanimoto 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):1135-1141
In order to improve seismic design technology of bridges, it is necessary to evaluate the vibration characteristics of a bridge–soil system that consists of soil, foundation structure, pier and superstructure. However, there have been few experimental studies on seismic behavior of bridge–soil system. In this paper, we conducted the hybrid vibration experiment on seismic behavior of bridge–soil system, and examined the applicability of hybrid vibration experiment to study seismic response of bridge–soil system. Based on the experiment results, seismic response of bridge was quantitatively studied. 相似文献
13.
Numerical and experimental investigations on inelastic cyclic performance of mid‐span gusset plate connections 
下载免费PDF全文
下载免费PDF全文 The design and detailing of gusset plate connections greatly influence the seismic performance of a special concentrically braced frame (SCBF). Recently, a balanced design approach has been proposed in order to develop significant inelastic deformation from multiple yield mechanisms and to delay the failure of connections of SCBF system. Although extensive studies have been conducted on the corner gusset plate connections of SCBFs, research on the detailing of mid‐span beam gusset plates is rather limited. This study aims at investigating the required free length for the detailing of the mid‐span gusset plates with different brace slenderness ratios. A nonlinear finite element analysis has been conducted for a braced frame with 4 different values of linear clearance in the mid‐span gusset plates and 2 values of brace slenderness ratios. In all simulation models, the corner gusset plates have been designed using balanced design approach and detailed using an elliptical clearance of 8 times the gusset plate thickness. An experimental study has also been conducted on 2 gusset plate sub‐assemblages having similar brace slenderness ratio but with 2 different values of linear clearance in the middle gusset plates. The lateral drift capacity corresponding to the brace fracture and the level of damage are found to be dependent on the detailing of the gusset plates. Based on the results of numerical and experimental studies, the required free length has been recommended for the detailing of middle gusset plates of SCBFs of different brace slenderness ratios. 相似文献
14.
诸多研究表明我国深部资源潜力巨大,但目前的开发开采深度普遍停留在500 m以浅,开展"攻深探盲"是构建国家资源安全体系的有效途径.应用最先进的科学技术手段,提取深部地质信息,已成为我国当前地球物理科学研究的发展方向.作为地球物理学的重要分支,电磁法是矿产资源探查的主体手段之一.在分析我国现阶段航空、地面及海洋电磁探测技术进展的基础上,本文重点说明了极低频电磁法（简称WEM法）,多通道瞬变电磁法（简称MTEM）和电性源短偏移瞬变电磁法（简称SOTEM）等电磁探测新技术.WEM法建立一套包括岩石层、大气层和电离层在内的全空间电磁传播理论,通过新研制的观测系统,获取地下10 km的地电信息;MTEM方法是地下埋深4 km目标体精细勘查的有效手段;SOTEM实现地下1.5 km深度范围内目标体的精细探测.通过多种电磁探测技术组合,可实现地下10 km深度范围内多尺度探测,达到"望远镜+放大镜+显微镜"探测效果.同时,本文指出进一步研发与新方法配套的装备、资料处理技术和大数据人工智能识别等将是我国电磁法未来的发展方向. 相似文献
15.
The study was undertaken to assess the marine environmental effects from feed and waste associated with aquaculture activities. Metal compositions of sediment, lobster, and feed were used to evaluate the extent of detectable effects at 0 m (under the cage) and 50 m distance. Sediments that were collected under the cages and were characterised as hypoxic or anoxic, showed elevated levels of Cu, Zn, organic carbon, and % <63 microm particles, and low Mn and Fe. At 50 m there was a major reduction in waste chemical impact. Using lobster, a bioindicator species, as a tool for detecting near-field impacts, showed accumulations of high Cu associated with active aquaculture sites. Chemical compositions and metal ratios normalised with organic carbon, were used to assess the sediment conditions associated with environmental monitoring program ratings (EMP--normal, hypoxic, and anoxic). Principal component analysis (PCA) was used to explore chemical data at all sites for differentiating normal, hypoxic and anoxic sediment conditions. Selected variables (Cu, Zn, Fe, Mn, organic carbon, and particles <63 microm) were sufficient for the PCA approach with >90% explainable variance of first two components. The groupings based on PCA and cluster analysis were similar to EMP classifications with some exceptions of mis-identification by EMP. The sediment chemistry components were valid indicators for evaluating marine environmental conditions and for assessing aquaculture operating sites. The developed techniques, using chemical variables in combination with EMP and the statistical approach should be useful to predict the effects of aquaculture practices and the suitability of aquaculture operations. 相似文献
16.
Irgarol 1051 (2-methythiol-4-tert-butylamino-6-cyclopropylamino-s-triazine) is an algaecide commonly used in antifouling paints. It undergoes photodegradation which yields M1 (2-methylthio-4-tert-butylamino-6-amino-s-triazine) as its major and most stable degradant. Elevated levels of both Irgarol and M1 have been detected in coastal waters worldwide; however, ecotoxicity effects of M1 to various marine autotrophs such as cyanobacteria are still largely unknown. This study firstly examined and compared the 96 h toxicities of Irgarol and M1 to the cyanobacterium Chroococcus minor and two marine diatom species, Skeletonema costatum and Thalassiosira pseudonana. Our results suggested that Irgarol was consistently more toxic to all of the three species than M1 (96 h EC50 values: C. minor, 7.71 microug L(-1) Irgarol vs. > 200 microg L(-1) M1; S. costatum, 0.29 microg L(-1) Irgarol vs. 11.32 microg L(-1)M1; and T. pseudonana, 0.41 microg L(-1) Irgarol vs. 16.50 microg L(-1)M1). Secondly, we conducted a meta-analysis of currently available data on toxicities of Irgarol and M1 to both freshwater and marine primary producers based on species sensitivity distributions (SSDs). Interestingly, freshwater autotrophs are more sensitive to Irgarol than their marine counterparts. For marine autotrophs, microalgae are generally more sensitive to Irgarol than macroalgae and cyanobacteria. With very limited available data on M1 (i.e. five species), M1 might be less toxic than Irgarol; nonetheless this finding warrants further confirmation with additional data on other autotrophic species. 相似文献
17.
The potential impacts of naval sonar on cetaceans has led to a series of court cases and statements of concern by international organizations. However, there has been no research conducted on attitudes of the general public with respect to this issue. To investigate this, a preliminary public survey was conducted in Fairfax, Virginia (the Washington, DC Metro region). The majority of the public sampled believed that naval sonar impacted marine mammals (51.3%), that the US Navy should not be exempt from environmental regulations in time of peace (75.2%), and that sonar use should be moderated if it impacts cetaceans (75.8%). Individuals who were conservative, Republican, and have served in the military were more likely to believe the Navy should be exempt from marine mammal protection regulations. In addition, expert interviews were conducted to gain opinions on the potential ramifications of the recent US Supreme Court case on naval sonar mitigation. 相似文献
18.
V. U. Smakhtin 《水文研究》2002,16(13):2613-2620
Subsurface flow is an important component of the catchment hydrological cycle. Various mechanisms of this process and their role in storm‐flow generation attracted the attention of many researchers throughout the twentieth century. The results of most of these studies are well documented. However, similar studies conducted in the past by many Russian hydrologists have never been made available to the English speaking hydrological community. This paper attempts to fill this gap and briefly review some of these investigations, focusing on their main results. It starts with the review of the early experimental studies (after 1930s–1950s), which allow the main characteristics of subsurface storm flow to be established. This is followed by a review of the research conducted in 1960s, which resulted in some conceptualization of the subsurface flow mechanisms. The paper also draws some parallels between this, mostly unknown, subsurface flow research in Russia and the better‐known contemporary studies of this process. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
19.
Polydimethylsiloxanes (PDMS) defoamers are used to improve process efficiency under extreme conditions during gas-oil separation, when other chemicals fail to perform. They are also used to reduce the oil content of process waters discharged to the marine environment, thereby serving an important function in reducing oil pollution. As a consequence of these applications small quantities of PDMS may also be released into the environment. This paper reviews the fate of PDMS in the marine environment and the extensive effect studies that have been conducted. These demonstrate the absence of adverse effects on a wide range of marine species. 相似文献
20.
Characteristics of Cd isotopic compositions and their genetic significance in the lead-zinc deposits of SW China 总被引：2，自引：0，他引：2
ChuanWei Zhu HanJie Wen YuXu Zhang HaiFeng Fan ShaoHong Fu Juan Xu TingRong Qin 《中国科学:地球科学(英文版)》2013,56(12):2056-2065
Up to now, the evaporation and condensation, as well as the biological absorption and inorganic absorptions, have been proved to be major factors in Cd isotope fractionation. And Cd isotopes have been widely applied in studies on the universal evolution and marine environment and so on. However, only a few researches have been conducted in applying Cd isotopes to trace the source of metallogenic material and the evolution of the ore-forming fluid in a complex mineralization environment, especially in a hydrothermal ore-formation system. We measured the Cd isotopic compositions of sphalerite, galena, and ores from five lead-zinc deposits in SW China, and found that the δ 114/110Cd values varied from ?1.53‰ to 0.34‰, with a total range of 1.87‰, which is greater than most of measured geological samples. Meanwhile, through contrasting the Cd content with Cd isotopic compositions of different deposits, it may be concluded that different genetic lead-zinc deposits have different Cd content and isotopic compositions, which could be a tool for the studies on the origin of ore deposits. Also, the biomineralization and crystal fractionation may also result in Cd isotope fractionation. In a word, although the research of Cd isotopes is presently at the preliminary stage (especially in hydrothermal ore-formation system), this study demonstrated that Cd isotopes can give a clue in tracing the evolution of ore-forming fluid and metallogenic environment. 相似文献