MATLAB及其在扇区水泥胶结测井(SBT)资料成像处理中的应用

MATLAB是集数学、图形处理和程序语言设计于一体的著名数学软件。它以矩阵为基本的数值计算单元,对数据进行分析处理、可视化等。利用这些优点,在MATLAB界面下编程处理扇区水泥胶结测井(SBT)现场采集的测量资料,最终以图像方式显示了套管井中0°~360°的套管波衰减数据。将处理结果与Atlas专用处理软件的处理结果进行分析对比,表明两者具有良好的一致性。     

2006年青海玉树地震类型和发震构造分析

2006年7月18和19日在青海玉树相继发生了5.0、5.6和5.4级地震。本文通过玉树地震台记录的地震波形及青海省地震台网监测结果分析该地震事件属于震群型地震;通过现场考察及宏观烈度区、余震分布和震源机制解、区域构造分析认为发震构造为乌兰乌拉湖-玉树构造带。     

强降温对设施农业影响风险研究

强降温天气对设施农业生产影响很大、风险较高。为了减少和降低强降温对设施农业的危害,提高设施农业生产应对强降温天气的处置和抗风险能力,采用关中东部设施农业生长季(当年11月—次年4月)11个气象站1961—2015年逐日平均气温、最低气温资料和同期灾情资料,基于ARCGIS平台,研究强降温对设施农业的影响和风险。结果表明:对于设施农业来说,24 h降温≥10℃的高风险区在白水、澄城和合阳,24 h降温≥8℃的高风险区在白水、澄城、合阳、蒲城和潼关。潼关种植设施农业的强降温风险高,不适宜大面积种植设施农业。蒲城设施蔬菜大棚24 h降温8℃的风险高,应采取措施加以应对。对设施农业来说,要高度重视11月和3—4月的强降温天气。另外,1—2月应重视持续低温造成的影响,11—12月要考虑强降温伴随的大风、降雪的综合影响。     

Geostatistical Seismic Inversion with Self-Updating of Local Probability Distributions

Mathematical Geosciences - Three-dimensional subsurface elastic models inverted from seismic reflection data are the basis of the geo-modeling workflow. These models are often used to predict the...     

Effect of Carbonation and Drying-Wetting Cycles on Chloride Diffusion Behavior of Coral Aggregate Seawater Concrete

Based on seawater immersion,drying-wetting cycles,carbonation and drying-wetting cycles for coral aggregate sea-water concrete(CASC)with different strength grades,the effect of carbonation and drying-wetting cycles on chloride diffusion be-havior of CASC is studied.The results show that the free surface chloride concentration(Cs),free chloride diffusion coefficient(Df)and time-dependent index(m)of CASC in the drying-wetting cycles is obviously higher than that in seawater immersion.The Df and m of CASC of carbonation and drying-wetting cycles is higher than that in the drying-wetting cycles.Carbonation increases the Df and m of CASC,which is against CASC to resist chloride corrosion.The corrosion possibility of CASC structures in different ex-posed areas is as follows:splash zone(carbonation and drying-wetting cycles)>tidal zone(drying-wetting cycles)>underwater zone(seawater immersion).Besides,the chloride diffusion rate of C65-CASC is 17.8%-63.4%higher than that of C65-ordinary aggre-gate concrete(OAC)in seawater immersion(underwater zone).Therefore,anti-corrosion measures should be adopted to improve the service life of CASC structure in the oceanic environment.     

21st Anniversary of the Bulletin

Abstract

The drought event which reached severe levels in 1972 and 1973 caused a major disaster in the Sahalian and sub-Sahalian zones in Africa. This disaster has drawn attention to the need for data surveys and detailed studies for meaningful long-term measures to combat the effects of future droughts.

The study reported in this paper is an attempt to assess the hydrological aspects of the drought event in Nigeria in 1972 and 1973. There exist relatively long and reliable records of rainfall within the drought zone, while records for runoff, water level and groundwater are few and far between. Data available are analysed to determine evidence of trend and persistence (short and long-term). An examination of the rainfall records showed that extreme dry years at all the stations tended to recur at about the same time. The time interval between these extreme dry years was about 30 years. It was also observed from the spectral analysis of the records that most of the spectra for all the stations showed a generally high level of variance at low frequency.

The limited information on runoff and groundwater precludes a detailed statistical analysis from being carried out on the annual series of runoff. However, the runoff data at some stations snowed that the magnitude of runoff in the drought year 1972/1973 was about 22–72 per cent of the average value for the length of record available (about eight years). Moreover, the long-term water-level record of Lake Chad revealed a similar trend for the occurrence of extreme dry years to that observed in the rainfall record.     

Mangrove habitat use by fishes in Southeastern Brazil: are there temporal changes in the structure of the community?

We compared fish community structure in Guaratiba Mangrove, SE Brazil, among three seasons of the hydrological cycle [(i) spring, increasing temperature and rainfall, decreasing salinity; (ii) summer/early fall, high temperature and rainfall, intermediate salinity; (iii) late fall/winter, low temperature and rainfall, high salinity] and between the years 2002–2003 and 2008–2009. The aim was to test the hypothesis that the fish community structure changes seasonally, associated with seasonal changes in environmental conditions, and that changes occurred between the two yearly periods because of increased anthropogenic activities. The sampling protocol for the two surveys was identical. A total of 63 species was recorded, with 38 species occurring in 2002–2003, and 53 species in 2008–2009. The main changes in the mangrove's fish assemblage between 2002–2003 and 2008–2009 were (i) an increase in species richness, fish density and total biomass; and (ii) an increase in the zoobenthivorous species of gerreids Eucinostomus argenteus, Diapterus rhombeus and Ulaema lefroyi, and a decrease in the planktivorous clupeid Harengula clupeola. Other abundant species, such as the opportunistic atherinopsid. Atherinella brasiliensis, the detritivorous mullet Mugil liza and the zoobenthivorous pufferfish Sphoeroides testudineus did not differ in abundance between the two yearly periods. Ten species occurred only in 2002–2003, and 23 species only in 2008–2009, indicating significant changes in community structure over the 6‐year period. Seasonal changes in community structure were more conspicuous in 2008–2009, when species abundance and richness were greatest. The highest fish abundance was recorded in spring and in summer/early fall, and the lowest in late fall/winter. The increased abundance and richness over time may be at least partially attributable to protection policies because of the effective implementation of a biological reserve in the area.     

Spatial patterns and environmental drivers of benthic infaunal community structure and ecosystem function on the New Zealand continental margin

To investigate regional drivers of spatial patterns in macro- and meio-faunal community structure (abundance, biomass and taxonomic diversity) and ecosystem function (sediment community oxygen consumption [SCOC]), we sampled two regions in close proximity on New Zealand's continental margin—the Chatham Rise and the Challenger Plateau. Sites (n = 15) were selected in water depths ranging from 266–1212 m to generate a gradient in sedimentary properties and, in particular, surface pelagic productivity. Both macro- and meio-fauna abundance and biomass was 2–3.5 times higher on the Chatham Rise than on the Challenger Plateau, reflecting regional differences in pelagic primary production. We also found significant inter- and intra-regional differences in macro-fauna taxonomic diversity with two distinctive site groupings in each region. Univariate and multivariate measures of macro-fauna community attributes were most strongly correlated with sediment photosynthetic pigment (explaining 24%–59% of the variation). Sediment pigment content was as equally important in explaining meio-fauna community structure (36%–7%). Unlike community structure, SCOC was most strongly correlated with depth (44%), most likely reflecting temperature effects on benthic metabolism. Our results highlight the importance of a benthic labile food supply in structuring infaunal communities on continental margins and emphasise a tight coupling between pelagic and benthic habitats.     

The influence of natural variation in discharge on juvenile brown trout population dynamics in a nursery tributary of the Motueka River,New Zealand

The effects of natural flow variation on juvenile brown trout population dynamics were investigated by biannual sampling over 5.5 years in the Rainy River, a tributary of the Motueka River. A large flood in late March (50-year return period) substantially reduced the density (by 66%) and biomass (by 73%) of 0+ trout over autumn–spring, but the cohort responded with compensatory survival to achieve similar density and biomass by spring as in other years. A low-flow event in February–April (return period >8.4 years), when 7-day low flows fell to 56% of the 7-day mean annual low flow (MALF) and were less than the MALF for 46 days, had no adverse affect on the population. We found no evidence for density-dependent growth. However, there was strong evidence for a two-phase self-thinning response in density, with no self-thinning occurring over summer (i.e. the 0+ population remained below carrying capacity) until a threshold mass of 22.08 g (length=123.7 mm) was attained in autumn after which severe self-thinning took place over autumn to spring. The results indicate that over spring–autumn the population is insensitive to flow reduction and that over autumn–spring the effects of high (and probably low) flow events on local abundance and biomass are offset by compensatory (density-dependent) survival. However, effects on the contribution of migrants to the downstream population remain unknown. The study identified ecological redundancy, which could be exploited for flow allocation. Significantly, it has shown that minimum flows equivalent to the MALF (often advocated by New Zealand conservation and fisheries management organisations) are not always necessary for sustaining juvenile trout populations.     

福建漳平北坑场钼多金属矿床辉钼矿Re-Os同位素年龄

福建漳平钼多金属矿床位于闽西南晚古生代坳陷东缘。中生代以来,闽西南坳陷经历了强烈的构造岩浆作用的改造,并伴随多期次成矿作用的发生。已有同位素年代学研究成果表明该区存在早侏罗世、中侏罗世以及早白垩世成矿作用,但缺少与晚侏罗世大规模岩浆作用相关的成矿年代学记录。本文选取漳平北坑场钼多金属矿床开展辉钼矿的Re-Os同位素年代学研究。根据Re-Os同位素测年结果,结合矿床围岩蚀变及矿化特征以及与岩体的相互关系,指出钼矿化的形成经历了多个成矿阶段,其中小规模的矿化发生在148.8±2.2Ma。主矿化阶段形成的矿床以细脉或网脉状赋存于下二叠统翠屏山组石英细砂岩中,其等时线年龄为139.8±2.3Ma~143.7±2.1Ma,为晚侏罗世~早白垩世成矿。成矿物质主要来源于特提斯向环太平洋构造域转换后闽西南地区晚侏罗世－早白垩世壳源花岗岩浆。