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11.
日本的各个地震观测台网共有500个固定台。这些台站分属于许多个台网:由日本气象厅管理的全国性台网。以及由一些国立大学和其院所管理的区域性和地方性的台网,包括防灾科学技术研究所。大多数非JMA台网是在全国预报计划之下建立的,该计划于1965年开始。JMA台网已有百余年的历史,现在包括约190个配备有短周期和中周期的地震仪的台,其他的多大数台网所配备的仪器则是高灵敏度的短周期地震仪,其典型的固有周期为  相似文献   
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<正> 50年代早期出现的电子测距仪为测量事业带来了前所未有的速度和精度。然而,伴随此种新的测量方法而俱来的有仪器检定和规格化的过程,因为观测结果受到(变化的)气象状况和必需经常测定的种种仪器误差的影响。为此,对于测量界来说,应有测定仪器性能变化的一种方便和可靠的方法。检定基线则可为广大用户提供检定手段。检定基线(CBL)是精密测定的直线距  相似文献   
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<正> 本书论及了近年来近景摄影测量重大发展的状况。近景摄影测量并不仅仅涉及地形测图,而是有着广泛应用领域的测量技术。本书在向从事测量和数据获取的专业人员讲述近景摄影测量原理及用途。第一章概述近景摄影测量的起源,早期模拟方法的应用和近期解析技术的发展。当读者将注意力转向实用领域时便知,过去在近景摄影测量精度方面的研究限多,而对时间和费用两个“参数”的考虑则不足。为此,作者强调指出,要使近景摄影测量普遍用于生产过程,则应把研究重点转到时间和  相似文献   
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Sampling the sea bottom surface remains difficult because of the surface hydraulic shock due to water flowing through the gear (i.e., the bow wave effect) and the loss of epifauna organisms due to the gear’s closing mechanism. Slow-moving mobile epifauna, such as the ophiuroid Ophiothrix fragilis, form high-density patches in the English Channel, not only on pebbles like in the Dover Strait or offshore Brittany but also on gravel in the Bay of Seine (>5000 ind m−2). Such populations form high biomasses and control the water transfer from the water column to the sediment. Estimating their real density and biomass is essential for the assessment of benthic ecosystem functioning using trophic web modelling. In this paper, we present and discuss the patch patterns and sampling efficiency of the different methods for collecting in the dense beds of O. fragilis in the Bay of Seine. The large Hamon grab (0.25 m−2) highly under-estimated the ophiuroid density, while the Smith McIntyre appeared adequate among the tested sampling grabs. Nowadays, diving sampling, underwater photography and videos with remote operated vehicle appear to be the recommended alternatives to estimate the real density of such dense slow-moving mobile epifauna.  相似文献   
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The accelerating deterioration of the coral reefs of Eilat has raised debate over the exact causes and how they affect the reefs. The hypothesis of the present study was that a low recruitment rate of reef-building coral species may play an important role in the decline of the Eilat reefs. Our goal was to assess spatial and temporal recruitment patterns in Eilat, focusing on examining the possible impact of human activities. The results of coral recruitment to 10 series of ceramic tiles on metal racks, revealed very low overall recruitment relative to other geographical regions. In addition, we found that recruitment rates and recruit survival were lowest at sites closest to the major eutrophication sources in Eilat. The low recruitment rates may be chronically too low to compensate for the elevated coral mortality rates of recent years. The significant differences between the present study and a similar study carried out during the same period using a different method, emphasize the crucial need for a standardized method for recruitment assessment in coral reefs worldwide.  相似文献   
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The aim of this research was to compare the bioremediation treatment of seawater polluted with two different concentrations of weathered crude oil (0.2 for experiment (a) and 1.14% for experiment (b), v/v) by salt-tolerant consortia enriched from the sludge of a refinery wastewater treatment facility, in a SBR. The use of a commercial bioremediation stimulant (S200) was also evaluated as an alternative to the traditional nitrogen and phosphorus supplement.  相似文献   
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Endocrine disrupting chemicals such as organochlorines have been detected in a large number of marine fish. Histological observation of the gonads, measurement of serum vitellogenin (VTG) level and of liver polychlorinated biphenyl (PCB) content were performed to evaluate the reproductive health and the contamination with endocrine disruptors in bigeye tuna Thunnus obesus, collected in the northern Pacific Ocean in 1999 and 2000. Abnormalities commonly found in species affected by endocrine disruptors such as the presence of oocytes in the testis or elevated serum VTG levels were not found in any of males examined. Both males and females had only small amounts of liver PCB content. The results suggest that currently there is little if any risk of organochlorine contamination or endocrine disruption of gonadal function in bigeye tuna from the northern Pacific Ocean. However, further studies are necessary to evaluate the health status of the open sea fishery resources.  相似文献   
19.
We monitored seasonal changes of the abundance and composition of microorganisms in the fish-farm sediment in Kusuura Bay, Amakusa, Japan, using the quinone profiling technique, during bioremediation by introducing cultured colonies of polychaete, Capitella sp. I. In November 2004, approximately 9.2 million cultured worms were transferred to the fish-farm sediment, which increased rapidly, and reached 458.5 gWW/m(2) (528,000 indiv./m(2)) in March 2005. During this fast-increasing period of Capitella, the microbial quinone content of the surface sediment (0-2 cm) also increased markedly, and reached 237 micromol/m(2) in January 2005, although the water temperature decreased to the lowest levels in the year. Particularly, the mole fraction of ubiquinone-10 in total quinones in the sediment, indicating the presence of alpha subclass of Proteobacteria, increased by 9.3%. These facts suggest that the bacterial growth was enhanced markedly by the biological activities of worms in the sediment, and the bacteria played an important role in the decomposition of the organic matter in the sediment.  相似文献   
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