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地震空间分布的多分维谱探讨 总被引：1，自引：0，他引：1
本文首先介绍了计算地震空间分布多分维谱的方法,如推广G—P法、固定质量法和固定半径法,然后利用推广G—P法计算理论模型(如Henon映射、随机模型)的多分维谱并分析计算中有关参数的影响(如计算样本大小和标度区确定),结果表明:度量半径r应小于研究区域的直径的1/4以减小边界效应。最后计算并分析地震资料(如1976年唐山地震地区的地震目录)。 相似文献
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Dissolved aluminium and the silicon cycle in the Arctic Ocean 总被引：1，自引：0，他引：1
Concentrations of dissolved (0.2 µm filtered) aluminium (Al) have been determined for the first time in the Eurasian part of the Arctic Ocean over the entire water column during expedition ARK XXII/2 aboard R.V. Polarstern (2007). An unprecedented number of 666 samples was analysed for 44 stations along 5 ocean transects. Dissolved Al in surface layer water (SLW) was very low, close to 1 nM, with lowest SLW concentrations towards the Canadian part of the Arctic Ocean and higher values adjacent to and in the shelf seas. The low SLW concentrations indicate no or little influence from aeolian dust input. Dissolved Al showed a nutrient-type increase with depth up to 28 nM, but large differences existed between the different deep Arctic basins. The differences in concentrations of Al between water masses and basins could largely be related to the different origins of the water masses. In the SLW and intermediate water layers, Atlantic and Pacific inflows were of importance. Deep shelf convection appeared to influence the Al distribution in the deep Eurasian Basin. The Al distribution of the deep Makarov Basin provides evidence for Eurasian Basin water inflow into the deep Makarov Basin. A strong correlation between Al and Silicon (Si) was observed in all basins. This correlation and the nutrient-like profile indicate a strong biological influence on the cycling and distribution of Al. The biological influence can be direct by the incorporation of Al in biogenic silica, indirect by preferential scavenging of Al onto biogenic siliceous particles, or by a combination of both processes. From the slope of the overall Al–Si relationship in the intermediate water layer (AIDW; ~ 200–2000 m depth), an Al/Si ratio of 2.2 atoms Al per 1000 atoms Si was derived. This ratio is consistent with the range of previously reported Al/Si uptake ratio in biogenic opal frustules of diatoms. In the deepest waters (>2000 m depth) a steeper slope of the Al–Si relationship of 7.4 to 13 atoms Al per 1000 atoms Si likely results from entrainment of cold shelf water into the deep basins, carrying the signal of dissolution of terrigenous particles with a much higher Al:Si ratio of crustal abundance. Only a small enrichment with such crustal Al and Si component may readily account for the higher Al:Si slope in the deepest waters. 相似文献
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于1997年11—12月(枯水期)、1998年8月和10月(丰水期)，对长江从金沙江至河口干流和主要支流、湖泊入江口各种形式的无机氮进行调查。结果表明，长江枯、丰期，干、支流NO3—N平均浓度变化很小，NO2—N、NH4—N浓度枯水期显著高于丰水期，支流高于干流；长江NO3—N、NH4—N和DIN在枯、丰期具有基本相似的迁移过程；长江水中无机N的迁移变化主要取决于NO3—N，NO3—N始终是三态无机N的主要存在形式，三态无机N处于较稳定的热力学平衡状态中；长江干流无机N与径流量呈正相关表明长江水中无机N主要来自于面源。 相似文献
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Lichenometry is a dating technique that has problems relating to questionable assumptions. The development of a size frequency approach, previously used in attempts to resolve some of the problems, is described and applied to the dating of four debris flows marginal to the San Rafael Glacier in Southern Chile. This study provides examples of the development's application, its problems and directions for further work. The size frequency approach, based on new assumptions, uses parameters derived from population size frequency distributions of the lichen species Placopsis patagonica to provide relative and absolute dating for rock surfaces. Changes in the shapes of distributions suggest the relative age of populations. Absolute dating is based on a curve (spanning a 24 year time period) derived from mean diameter size/age correlations. A stratified random sampling design permits the use of inferential statistics. Standard deviations and confidence intervals show error margins, the degree of relatedness between neighbouring populations, and populations that are anomalous. One-way analysis of variance is used to indicate where populations may safely be grouped. The size frequency approach appears to be particularly suitable for use on unstable debris flows where secondary movements are common. The approach also demonstrates that lichen growth and colonization are sensitive to aspect differences and other variations in microhabitat. 相似文献
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Distributions and vertical variation patterns of sound speed of surface sediments in South China Sea
The distributions of sound speed show different characteristics in continental shelf, continental slope and Nansha Trough. The differences have closely related to the distributions of sediment physical properties in the southern South China Sea. According to the analysis of sound speeds and physical properties variation characteristics with buried depth, the vertical variations of sound speed are closely related to sediment texture, sedimentary environment, transport, erosion, compaction, consolidation, etc. The comparison results indicate 3 vertical variation patterns of sound speed: increasing model, invariant model and complicate variation model. The above 3 variation models represent the vertical distribution characteristics of sound speed in different depositional environments. Different variation patterns have different key factors which generally contain porosity or grain size. The calculated sound speeds with Buckingham’s theory of compressional waves in fluid-like marine sediments follows the trend of measured speeds accurately. 相似文献
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In this paper, we determined the concentrations of antimony species (antimonite (Sb(III)), antimonate (Sb(V)) and dissolved inorganic antimony (DISb)) and arsenic, in Bohai Bay seawaters, as well as the relationships of the analytes with environmental factors such as seawater characteristics (e.g., suspended particulate material (SPM), salinity and total organic carbon (TOC)), heavy metals, nutrients and phytoplankton species, and evaluated the sources of arsenic and antimony. Dissolved arsenic and antimony concentrations in the surface waters were ranging spatially from 1.03 to 1.26 ng/ml and 0.386 to 1.075 ng/ml, with mean values of 1.18 and 0.562 ng/ml, respectively. Sb(V) as the prominent chemical species constituted about 89%. Regarding arsenic concentrations in the surface waters, there was a tendency for a small variation. However, antimony species concentrations were much variable than arsenic. The highest arsenic and antimony concentrations were found near the Haihe Estuary. These distribution patterns were controlled mainly by environmental factors, biological activities and sources. In this region, DISb and Sb(V) negatively correlated with salinity. Besides, arsenic and antimony correlated well with the nutrients, chlorophyll a and phytoplankton, implying that arsenic and antimony had been involved in biological cycling. In addition, according to our estimate, about 333.5×108 mg/year of arsenic and 454.2×108 mg/year of antimony reached Bohai Bay via rivers. 相似文献
8.
本世纪以来台湾及邻近海域的强震活动特征 总被引：1，自引：0，他引：1
本文分析了台湾及其邻近海域M≥7级地震的时空演变特点，并对其进行了分区讨论，发现该区各活动时段的地震活动有集丛分布的特征，该区东部地区与下扬子地区，西部地区与闽东地区地震有一定的呼应关系，并对今后几年地震活动趋势作出了估计。 相似文献
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1997年11-12月(枯水期)，1998年8月和10月(丰水期)，对长江从金沙江至河口干流和主要支流、湖泊入江口总氮、总溶解氮、总有机氮等进行调查。结果表明，长江水中各种形态氮的浓度，枯水期明显高于丰水期，支流明显高于干流；长江TN和TDN在枯、丰期具有基本类似的迁移变化过程；DIN是长江水的TDN的主要存在形式，丰水期TDN的迁移变化主要取决于DIN；TDN是长江水中TN的主要存在形式，TN的迁移变化主要取决于TDN或者由DIN和TON共同决定；丰水期各种形态的氮中只有有机氮比较容易为悬浮颗粒物质所吸附；长江干流枯水期TDN浓度与长江径流呈较好的线性正相关关系；枯水期TN、丰水期TN和TDN浓度与长江径流的正相关主要发生在上游，这与长江水中氮主要来自于面源有关。 相似文献