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1.
Alkylphenolic compounds are present in estuarine and marine environments. They are moderately bioaccumulative, and oestrogenic to fish following three week, in vivo, exposures. The effects of prolonged exposure are, as yet, unclear. Sand goby (Pomatoschistus minutus) were exposed to measured concentrations of 4-tert-octylphenol (OP) in a 28-day, dose-ranging study, and a six month temporal response study. Following 28-days exposure to measured 31+/-6 or 101+/-47 microg l(-1) OP (mean+/-SD), immature male sand goby showed elevated vitellogenin (VTG) mRNA expression. Plasma alkali-labile phosphate concentrations were elevated in both sexes and were higher in females than males. Although measured OP concentrations were variable, they were significantly different for each treatment and a range of concentration-dependent effects were observed. The LC(50) for chronic OP exposure (8 weeks) was 29+/-6 microg l(-1), and both sexes demonstrated concentration and duration dependent increases in VTG mRNA expression. Exposure to 28+/-20 microg l(-1) OP (median+/-95% CI) for 6 months inhibited development of male nuptial colouration and sperm duct glands. These findings are discussed in relation to environmental concentrations of alkylphenols and ecological concerns.  相似文献   
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An integrated system named METEOMOHID, developed by MeteoGalicia in the first stage of the Prestige accident in November 2002 was used successfully in an operational form to support decision making and assist in recovering tasks. Afterwards, METEOMOHID has been enhanced with the aim of developing an operational oceanography system to be used in the NW of the Iberian Peninsula. The METEOMOHID system includes local area hydrodynamic coastal ocean modelling (MOHID), real time atmospheric forcing from a local meteorological model (ARPS). Using the available data from the Prestige crisis, a set of simulations were designed in order to reproduce the oil spill drift. The implementation of a detailed vertical resolution in the model has allowed obtaining a detailed surface dynamic, improving our knowledge of the behaviour of tarballs into the water column. Thus, the wind-driven Eckman drift, the direct dragging of the wind were detached, and the possible existence of subsurface oil was assessed. In addition, the present work evaluates the effects of introducing climatologic large scale currents in the METEOMOHID system.  相似文献   
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Apatite fission track thermochronology (AFTT) and paleomagnetic (PM) results have been used to constrain the Late Paleozoic to Cenozoic landscape evolution of the Lachlan Fold Belt (LFB) around the Northparkes copper-gold deposit in east-central New South Wales. The present-day landscape of this region of the LFB is relatively flat with little expression of the underlying rock and has previously been interpreted to indicate long-term stability of the region since the end of LFB orogenesis in the Early Carboniferous. This was presumably borne out by PM analyses from thick weathered horizons within open pits at the mine, which suggested that significant periods of weathering, and hence relative landscape stability, prevailed during the Early to middle Carboniferous and at some time during the Cenozoic. Results from AFTT analyses, however, indicate that the region must have experienced significant episodes of cooling/denudation during the mid-Permian to mid-Triassic and during the early Cenozoic, as well as episodes of heating/burial during the Late Carboniferous to mid-Permian and during the late Mesozoic. When combined, the AFTT and PM results are in fact consistent and indicate that since the late Paleozoic the landscape of the LFB around the Northparkes deposit has evolved through multiple episodes of denudation and deposition as well as periods of relative stability during which the thick weathering horizons formed. Together these results establish a complementary chronological framework that constrains the Late Palaeozoic to Cenozoic landscape evolution of the Northparkes region and highlights the importance of using dual data sets in elucidating the long-term landscape evolution of similar "stable" terranes.  相似文献   
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Tsang  CF 《地球科学》2000,25(5):443-450
对大空间尺度和长时间跨度的地下水流动及污染物质运移进行预测的需求, 使水文地质研究面临异乎寻常的挑战.这些需求来自于对核废料地质储放方法的安全性评价、地下水污染状况评价及其治理方案的选择.流动系统的非均质性是地下水流动及物质运移模拟中最主要的困难之一, 这种困难来自对非均质系统进行特征描述(通过原位观测实现)、概念化及模拟.评述了非均质介质中流动运移模拟的一些重要问题与挑战, 讨论了解决的途径.讨论的主题包括: 动力流动的沟道化, 示踪剂穿透曲线, 裂隙岩石中流体流动的多尺度, 观测的不同尺度, 模拟、预测与非均质性以及系统特征描述和预测性模拟的分析.   相似文献   
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Filamentous cyanobacteria often dominate benthic microbial communities of antarctic lakes and usually exhibit saturation of photosynthesis at light intensities approximately 100 microEinst m-2 s-1. Incident light regimes are controlled by ice and snow accumulations overlaying water columns during much of the year. Thus, light availability to microbial mats is often below saturation intensity and is strongly influenced by modest changes in climatic factors. A model of net primary production for benthic mat communities of the subantarctic Sombre Lake, Signy Island, was developed (1) to evaluate depth-specific productivities of mat communities, (2) to test the relative importances of model parameters to mat production, and (3) to explore the potential impacts of climate change on mat production as manifested through changes in light regime. Simulated rates of net primary production corresponded to observations on a daily basis (approximately 1-4 micrograms C fixed mg-1 ash-free DW of mat d-1) but were an order of magnitude lower than estimates of net annual production based on field measurements (< or = 3 vs. 11-45 g C m-2 yr-1, respectively). Close examination suggested that the simulated values were more plausible. A detailed sensitivity analysis of model behavior revealed that variations in the time of ice and snow melt in spring accounted for 40-60% of the total variation in model behavior, emphasizing the importance of climatic factors to net primary production of mat communities and the sensitivity of mat production to climate change.  相似文献   
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由ONRAM 100,300,1000/2三个型号组成的ONRAM系列全液压金刚石钻机是美国爱达荷哈哥拜(HAGBY)公司的产品,地面、坑道两用。是为A级品位控制、勘探,岩土工程、矿山开发和注浆孔钻进而设计的,可全面钻进,特别适用于坑道中的扇面钻进。基本型钻机的技术规格见附表。  相似文献   
9.
分析了国务院《关于加强地质工作的决定》出台后,钻探技术面临的新形势;结合《国家中长期科学和技术发展规划纲要(2006~2020年)》对能源、水和矿产资源勘探开发、环境保护以及天然气水合物勘探开发技术的重视,分析了钻探技术面临的新机遇和新任务。最后提出了我国钻探技术研究发展的新目标。  相似文献   
10.
Cypermethrin is a synthetic pyrethroid that is particularly toxic to crustacea. It is therefore applied as a chemotherapeutant in the salmonid aquaculture industry for the treatment of sea lice infestations. After use, cypermethrin is released directly into the marine environment, to be diluted by fresh seawater. The shore crab, Carcinus maenas is found in the vicinity of fish farms, and may come into contact with released cypermethrin. The detoxification enzyme, glutathione S-transferase (GST) has been implicated in cypermethrin metabolism in terrestrial arthropods, but this has not yet been demonstrated in crustacea. In this paper we investigate the response of GST activity in Carcinus to cypermethrin exposure, and also the time course of the induction process. GST activity is significantly increased in Carcinus exposed to nominal concentrations of 50 and 500 ng/l of water-borne cypermethrin. Carcinus demonstrate a significant elevation in GST activity following intra-cephalothoracic injection with 10 ng of cypermethrin. GST activity returns to basal levels after 36 h. The potential application of GST activity in Carcinus as a biomarker of cypermethrin exposure is discussed.  相似文献   
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