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941.
942.
Susana Bolhão Muiños James R. Hein Martin Frank José Hipólito Monteiro Luís Gaspar Tracey Conrad 《Marine Georesources & Geotechnology》2013,31(1):40-70
Eighteen deep-sea ferromanganese crusts (Fe-Mn crusts) from 10 seamounts in the northeast Atlantic were studied. Samples were recovered from water depths of ~1,200 to ~4,600 m from seamounts near Madeira, the Canary and Azores islands, and one sample from the western Mediterranean Sea. The mineralogical and chemical compositions of the samples indicate that the crusts are typical continental margin, hydrogenetic Fe-Mn crusts. The Fe-Mn crusts exhibit a Co + Cu + Ni maximum of 0.96 wt%. Platinum-group element contents analyzed for five samples showed Pt contents from 153 to 512 ppb. The resource potential of Fe-Mn crusts within and adjacent to the Portuguese Exclusive Economic Zone (EEZ) is evaluated to be comparable to that of crusts in the central Pacific, indicating that these Atlantic deposits may be an important future resource. 相似文献
943.
The calcarean sponge Paraleucilla magna is classified as being an invasive species on the Mediterranean Sea, where it causes economic damages to mollusc farms. On the Brazilian coast, this species is considered to be cryptogenic, and information on its ecology is scarce. The same is true for Sycettusa hastifera, another calcarean sponge with a worldwide distribution. Data on the ecology of these species could help in elucidating their potential to become a threat if they are found to be exotic species in Brazil. In the present work, we studied habitat selection, growth and mortality of early juveniles of P. magna and habitat selection of S. hastifera in a Marine Reserve from Southeastern Brazil, where these species are abundant in the benthic community. Granite plates were used for habitat selection analysis, varying in substrate inclination (vertical and horizontal) and exposure to light and hydrodynamism (exposed and sheltered). To analyse the growth and mortality rates, sponges were mapped and then measured once a week for 10 weeks. If a monitored sponge was not found in the following week, it was considered to be dead. Our results showed that, although P. magna and S. hastifera are capable of inhabiting substrates exposed to different environmental conditions, they showed habitat preferences. Growth of the juveniles of P. magna seemed not to have damaged any neighbouring invertebrates. The mortality of juveniles of this species was higher during the first 2 weeks of life but its causes could not be elucidated. 相似文献
944.
Common carp (Cyprinus carpio L.) exhibits significant morphological variability in the shape and size of the caudal fin. In this study, we used 190 progeny from two F1 parents to identify and map quantitative trait loci (QTLs) that influence caudal fin length (CFL) and the ratio (RCS) between caudal fin length and standard length (SL) based on a microsatellite genetic map of common carp. A total of 15 QTLs were detected in seven different linkage groups. One significant and eight suggestive QTLs affecting CFL were identified on LG8, LG14, LG29, LG32 and LG44, which explained 8.0%–22.1% of the phenotypic variation; six suggestive QTLs affecting RCS were detected on LG8, LG32, LG46 and LG48, which explained 7.0%–15.4% of the phenotypic variation. The QTLs for caudal fin length detected in this study may serve as a starting point for identification of genes involved in caudal fin development in common carp. 相似文献
945.
徐州地区新元古界赵圩组地层在赵圩村出露良好,整体为一套碳酸盐岩沉积,岩性组合可划分为4 段:鲕粒灰岩段、
风暴事件沉积段、叠层石段和白云岩段,其中叠层石段又划分为A 和B两个单元。剖面内部发育大量风暴沉积记录,并与
正常沉积在垂向上互层叠置,整体具有向上频率变弱、规模变小的趋势。典型的风暴沉积标志包括丘状交错层理、粒序层理、
冲刷- 充填构造、冲刷切削构造、砾屑灰岩层、生物礁丘截切现象等。文中划分出4 种风暴沉积序列类型,说明每种序列类
型指示的古地理和古环境意义,以及在剖面上的分布组合特征。依据剖面岩性与风暴沉积的分布组合规律,认为赵圩组由
下至上构成一个总体向上变深,而后又变浅的沉积序列,沉积环境演化依次为浅滩-近岸浅水潮下带-碳酸盐岩开阔台地-
碳酸盐岩局限台地-深水斜坡-潮坪、泻湖,气候总体炎热干旱。风暴频发可能与沉积期本区所处的较低的古纬度有关。 相似文献
946.
???DNSC08-GRA????е????????????????????????????????Stokes??????????????????????????????????????????????Stokes????????-??????????????????3.4 cm???????????????????????????????GPS/????????м??????????????????????1.17 m???????????????С?7 cm?? 相似文献
947.
运用CUM-AIC方法处理泰安地震台水平摆观测资料,发现其2011年10月13日河南省范县和山东省鄄城交界发生的4.3级地震前存在异常信号,分析显示该方法能较好地提取潮汐形变短临异常。 相似文献
948.
949.
形变仪器影响观测质量因素 总被引:3,自引:2,他引:1
通过对泰安地震台形变仪器观测资料质量的统计分析,发现影响观测质量的主要因素包括:观测环境的改善、优化可以提高观测精度;仪器管理和数据处理水平可以影响数据精度;降雨、吸潮等可以对曲线趋势变化造成影响;环境恶化,如外界抽水等干扰,会使曲线日变固体潮失真,从而掩盖真实的地壳信息。 相似文献
950.
Hong-Di He Wei-Zhen Lu 《Stochastic Environmental Research and Risk Assessment (SERRA)》2012,26(8):1053-1061
This paper reports an investigation on the periodic variation of pollutant levels at a typical traffic intersection of Hong Kong. Carbon monoxide, carbon dioxide and particulate matters (PM x ) were measured respectively and the measured data show periodic variations with the traffic signal intervals. The power spectral density (PSD) approach was used to inspect the trends and periodic oscillations of measured pollutants. Singular spectrum analysis was applied to decompose the measured data into statistically significant non-linear trends and oscillations in the process. From the results, most of the trends tend to increase due to the upcoming rush hour during the experiment. In addition, all the oscillations changed regularly with a period of 136?s, which is coincident with the traffic signal period and the frequency calculated by using PSD. The trends, together with the oscillations, collectively explain the most percentage of the variability of the data in the time series and provide the principal components of the data in understanding the periodic variation of the pollutant concentration. It can be deduced that vehicle emission is the major contributor to the air pollution in downtown area and pedestrians should be more alerted when crossing the busy traffic intersections. 相似文献