三亚鹿回头岸礁区人类活动及其对珊瑚礁的影响

通过在三亚鹿回头岸礁区开展人类活动的现场调查,发现礁区目前人类活动主要为以船捕鱼钓鱼、个人涉水捕鱼、采挖螺贝和潜水为主的水域活动和以养殖、餐饮为主的沿岸活动;人类活动强度和分布密度保持较低水平,水下人类活动印迹反映出过去礁区相对较频繁的人类活动状况。认为人类活动是导致三亚鹿回头珊瑚礁衰退的主要原因。基于以往定性资料,利用层次分析法计算了人类活动影响因子权重,并根据人类活动等级估算其影响指数,评价人类活动对珊瑚礁的影响。结果显示,近40年来人类活动对三亚鹿回头珊瑚礁总体为负面影响,但影响程度呈下降趋势,其中,上世纪70、80年代人类活动负面影响大,90年代小,目前的负面影响程度较小。主要原因在于上世纪90年代建立的三亚珊瑚礁国家级保护区和珊瑚礁立法保护,以及逐步加强的日常管理和环保宣传。但当前珊瑚礁仍面临不断增加的各类污染物排放活动的巨大威胁。     

海南岛鹿回头珊瑚岸礁沉积物的沉积特征

鹿回头岸礁处于比较平静的水动力条件下,自海向陆,可分出礁体生长带、外礁坪、内礁坪和海滩四个相带.沉积物的分布主要受水动力支配,沉积物粒匪分布和参数变化可以反映水动力条件的变化.通过对岸礁与陆源碎层物组成的无障壁海岸对比,进一步说明岸礁礁体生长带是重要的物源区,岸礁沉积物搬运的距离较短,且受生物、地形等因素的影响. 鹿回头岸礁沉积物的生物组分以软体动物壳屑为主,珊瑚屑次之,二者占总量的87.06%,再依次为钙藻、有孔虫、棘皮动物、苔藓虫和八射珊瑚骨扑.由陆向海,珊瑚、钙藻、有孔虫和苦藓虫层逐渐增加,软体动物壳层和八射珊瑚骨针则递减. 本区水尾岭上升礁剖面自下而上可分为原生礁、礁体生长带、礁坪和海滩四个相带,它代表了高海面渐进型序列.     

南沙群岛永暑礁澙湖沉积的晚全新世风暴事件记录

位于南沙群岛永暑礁西南小澙湖的南永4井岩芯柱中含多层珊瑚枝和珊瑚砾石的堆积,反映了突发性风暴事件造成的珊瑚碎屑快速搬运和堆积。全新世晚期约4 000 aBP以来,澙湖珊瑚砾堆积记录了1 400870BC、660BC390AD、600770AD和940-1992AD 4个主要的风暴事件频发时期,并且风暴的强度呈阶段性增强。风暴事件还表现出千年和百年尺度的周期性波动,具有1 280 a、370 a、210230 a、140150 a和90 a的准周期,与全新世气候环境的周期性变化相对应,很大程度上受太阳活动周期变化的影响。     

Nonparametric Geostatistical Simulation of Subsurface Facies: Tools for Validating the Reproduction of,and Uncertainty in,Facies Geometry

Delineation of facies in the subsurface and quantification of uncertainty in their boundaries are significant steps in mineral resource evaluation and reservoir modeling, which impact downstream analyses of a mining or petroleum project. This paper investigates the ability of nonparametric geostatistical simulation algorithms (sequential indicator, single normal equation and filter-based simulation) to construct realizations that reproduce some expected statistical and spatial features, namely facies proportions, boundary regularity, contact relationships and spatial correlation structure, as well as the expected fluctuations of these features across the realizations. The investigation is held through a synthetic case study and a real case study, in which a pluri-Gaussian model is considered as the reference for comparing the simulation results. Sequential indicator simulation and single normal equation simulation based on over-restricted neighborhood implementations yield the poorest results, followed by filter-based simulation, whereas single normal equation simulation with a large neighborhood implementation provides results that are closest to the reference pluri-Gaussian model. However, some biases and inaccurate fluctuations in the realization statistics (facies proportions, indicator direct and cross-variograms) still arise, which can be explained by the use of a single finite-size training image to construct the realizations.

     

Sediment Transport in a Proglacial Valley,Sermilik, East Greenland

Hasholt, Bent: Sediment Transport in a Proglacial Valley, Sermilik, East Greenland, Geografisk Tidsskrift 92:105–110, Copenhagen 1992.

Detailed investigations of sediment transport have been carried out in a proglacial valley at the Mitdluagkat Glacier in East Greenland. The results from 1989, 1990 and 1991 have been compared with earlier measurements of sediment transport. The hydrologie regime will be described and the effect of the development of an icing on the fluvial transport will be discussed.     

The Transnational Assembling of Marina Bay,Singapore

From Shanghai's Pudong to Dubai's Marina, waterfront developments are increasingly popular urban forms worldwide. Drawing on the literature on urban assemblages, I explore how urban waterfronts are produced out of the transnational assembling of models, knowledge and expertise. My case study here is Marina Bay, Singapore, a landscape that like much of the rest of Singapore is a product of talent and ideas from elsewhere. In this paper, two strategies employed by Singapore's urban authorities to court global expertise for Marina Bay's development are examined – their formation of an international panel of experts in the fields of urban planning, policy and design, and their launching of international competitions to attract top design firms. Like transfer agents that enable policies to travel, I argue that these individuals and firms are situated within wider knowledge circuits that straddle the globe, and are thus well placed to filter and channel ideas from elsewhere to Singapore. Drawing on selected developments within Marina Bay, I trace the routes taken by these ideas, the changes they underwent as they travelled, as well as their relationships with the actors that facilitated their journeys. In doing so, I hope to demonstrate the usefulness of understanding the urban as more‐than‐territorial in both theory and practice.     

Renaissance City Singapore: a study of arts spaces

The study of 'arts spaces' has generally focused on physical spaces for the arts in the form of arts districts, cultural infrastructure and museum spaces. Apart from the provision of such physical spaces, we argue that the study of the arts should also focus on such aspects as the social environments and the creative spaces in which artists operate. Such a holistic approach not only facilitates an understanding of the myriad challenges artists face in society, but also opens greater research opportunities to geographers interested in the arts. Our case study of Singapore as a 'Global City for the Arts' provides insights into physical spaces of the arts as well as the social and creative environments in which the arts operate.     

新加坡"港-城"关系转型的经验借鉴

目前国内港区的“港-城”关系仍处于初级互动阶段,已无法满足社会经济的转型需求。本文在比较国内外案例的基础上．认为新加坡的“港-城”关系深具借鉴意义。本文在系统梳理新加坡相关资料的基础上．划分了新加坡的“港-城”关系的演进阶段．提炼出了新加坡“港-城”空间关系转型的关键要点．抽象出了新加坡“港-城”职能关系转型的概念框架。通过对比以天津滨海新区为代表的国内港区与上世纪80年代新加坡的“港-城”关系．发现二者的转型背景和发展挑战高度相似。本文结合国内港区的“港-城”关系现状,在借鉴新加坡“港-城”关系转型的基础上,从“港-城”建设、人口发展、生态宜居等方面提出了重构方案。     

广西涠洲岛海域珊瑚礁现状及其保护策略研究

通过对2005年涠洲岛珊瑚礁生态调查,结合对以往资料和数据的分析,对比1984年和1964年2次调查结果,掌握涠洲岛珊瑚礁的现状.同时讨论了涠洲岛珊瑚礁区面临的生存威胁,提出保护和管理涠洲岛珊瑚礁的建议,以期建立可持续的生态旅游开发与新型的生态保护生态管理体系.     

东疆北部全新世气候不稳定性的湖泊沉积记录

对新疆东疆北部巴里坤湖2.5 m深的沉积剖面进行了年代学、沉积物粒度、TOC、磁化率和CaCO₃含量分析,对比研究确定了巴里坤湖的碳库年龄约为750 a,据此建立了研究剖面的年代序列。研究表明,各气候代用指标序列揭示了巴里坤湖地区全新世期间存在多次干湿气候波动,并伴随着一系列突发气候事件,其中有6次事件可以与全新世北大西洋浮冰碎屑事件及GISP2冰芯氧同位素记录进行良好对比,且呈现出显著约1.6 ka的变化周期,表明高纬度北大西洋地区的气候变化可能通过对西风环流的影响与中国西北干旱区的气候变化密切相关。谱分析揭示出研究区气候变化还具有显著的200 a,133 a,108 a和77 a周期,可能与太阳活动周期有关。6300—5200 cal a BP和4300—3500 cal a BP期间巴里坤湖地区气候较为干旱,结合广泛的区域对比认为,中全新世干旱事件具有普遍性。     

Sediment Fluxes and Varve Formation in Sihailongwan,a Maar Lake from Northeastern China

Data derived from monthly sediment traps in Sihailongwan, a maar lake in northeastern China, yielded a detailed record of seasonal sediment fluxes. Sediment fluxes correspond to seasonal climatic variations. The diatom flux shows two distinct peaks in September and November, whereas the flux of chrysophyte stomatocysts shows a maximum in May. The blooms of diatoms may be related to the subsequent deepening of the thermocline in September and lake overturn in spring and November, and influx of nutrient-rich groundwater sometime after the onset of the summer monsoon. The fluxes of organic matter and siliciclastics show a distinct seasonal pattern. They are varying between 0.03 and 0.56 g m⁻² d⁻¹ and reach a maximum in May. Quartz in the trap samples indicates that the siliciclastic matter may originate from distant aeolian sources. Sediment trap data and thin section investigations confirm the seasonality of Lake Sihailongwan sediments. Dark-colored layer, which mainly consists of valves of Cyclotella comta, might be deposited during autumn, and then is followed by a light-colored mixed layer starting with siliciclastics deposited after ice-out. The varved sediments in the U-shaped Lake Sihailongwan represent a sensitive siliciclastic and geochemical archive of paleoenvironmental variability in this data-sparse area. Detailed investigations of varved sediments should provide decadal to annual records of seasonal sediment flux and its relation to climatic parameters. Especially the diatomaceous layer is regarded to indicate summer climatic fluctuations, while the thick siliciclastic layer could be an indictor of dust events.     

三峡水库修建前长江宜昌-武汉段泥沙输移比及其影响因子

运用泥沙收支平衡(Sediment budget)的概念确定长江中游宜昌-武汉河段的泥沙输移比,并运用数理统计方法,研究了1955～1997年间河道泥沙输移比对水沙变化的响应.从总体上看,河道泥沙输移比有较显著的增大趋势.输移比的变化可分为4个阶段:1955～1962年为快速增大;1963～1975年亦为增大,但增速减慢;1976～1979年为迅速减小;1980～1997年为较快增大.在分析了若干水沙指标对河道泥沙输移比的影响的基础上,建立了宜昌-汉口河段泥沙输移比与宜昌站的来水量和来沙量以及3口分水比和分沙比、宜昌站洪峰流量之间的多元回归方程.1980～1997年间的方程表明,宜昌站来水量越多、3口分流比越小,宜昌一汉口河段泥沙输移比越大;宜昌站来沙量越少,3口分沙比越大,泥沙输移比越大;宜昌站洪水流量越大,泥沙输移比越小.     

海南岛澄黄滨珊瑚共生藻对环境变化的适应性

在全球气候变暖和人类活动加剧导致珊瑚礁严重衰退的背景下,以抗逆性强的澄黄滨珊瑚（Porites lutea）为研究对象,于 2013 年 10 月―2014 年 8 月在海南岛文昌和三亚对其共生藻密度及光合效率开展了季节性调查研究。结果显示：1）澄黄滨珊瑚共生藻的密度及光合效率均存在显著的季节变化,共生藻密度在冬季最低、夏季较高,其光合效率在冬季较高,春夏季较低。2）澄黄滨珊瑚共生藻密度的空间差异远小于其季节变化的差异,但水深 1~2 m 澄黄滨珊瑚共生藻的密度普遍高于水深 4~6 m 的澄黄滨珊瑚,三亚澄黄滨珊瑚共生藻的光合效率明显高于文昌。3）进一步分析发现,在诸多环境因子中,海表温度 SST 和水体营养是驱动海南岛澄黄滨珊瑚共生藻密度及光合效率变化的主要环境因素,而光合效率的空间差异则可能是珊瑚对生存环境长期驯化的结果。由于文昌和三亚沿岸海水养殖和潜水旅游等人类活动频繁,礁区海水面临富营养化的风险,推测海南岛澄黄滨珊瑚面临 SST 上升和营养胁迫联合效应的严重威胁。     

Chronology of Sediment Deposition in Upper Klamath Lake, Oregon

A combination of tephrochronology and ¹⁴C, ²¹⁰Pb, and ¹³⁷Cs measurements provides a robust chronology for sedimentation in Upper Klamath Lake during the last 45 000 years. Mixing of surficial sediments and possible mobility of the radio-isotopes limit the usefulness of the ¹³⁷Cs and ²¹⁰Pb data, but ²¹⁰Pb profiles provide reasonable average sediment accumulation rates for the last 100–150 years. Radiocarbon ages near the top of the core are somewhat erratic and are too old, probably as a result of detrital organic carbon, which may have become a more common component in recent times as surrounding marshes were drained. Below the tops of the cores, radiocarbon ages in the center of the basin appear to be about 400 years too old, while those on the margin appear to be accurate, based on comparisons with tephra layers of known age.Taken together, the data can be combined into reasonable age models for each site. Sediments have accumulated at site K1, near the center of the basin, about 2 times faster than at site CM2, on the margin of the lake. The rates are about 0.10 and 0.05 cm/yr, respectively. The chronological data also indicate that accumulation rates were slower during the early to middle Holocene than during the late Holocene, consistent with increasing wetness in the late Holocene.     

长江宜昌-武汉河段泥沙年冲淤量对水沙变化的响应

运用泥沙收支平衡 (Sediment budget) 的概念确定长江中游宜昌-武汉河段的泥沙冲淤量,并运用数理统计方法,研究了泥沙冲淤过程对水沙变化的响应。研究表明,所研究河段的输沙具有“多来多排”的特性,在平均的意义上,年输入沙量为年输出沙量的1.1345倍,由此求得总净来沙中有11.85%淤积在河道中。河段出口输出沙量随时间而增大,大致在1980年达到峰值,然后再减小。1980年以前河段出口输出沙量的增大,与3口分沙减少 (等价于河段净来沙增多) 和下荆江人工裁弯 (使河道输沙能力增大,因而可以将更多的泥沙输送到河段出口以下) 有关,1980年以后的减少,则与宜昌站来沙量的显著减少有关。建立了1980~1997年间宜昌-汉口#河段年冲淤量与宜昌站年来沙量之间的回归方程,通过该方程估算出使宜昌-汉口河段不淤的宜昌站临界来沙量为3亿t/a。为了定量评价宜昌站的来水量和来沙量以及3口分水比和分沙比、宜昌站洪峰流量的变化对于河段冲淤量的相对贡献,我们以1980~1997年和1955~1997年两个时间系列的数据分别建立了多元回归方程。1980~1997年间的方程表明,宜昌站的来水量和来沙量以及3口分水比和分沙比、宜昌站洪峰流量的变化对宜昌-汉口河段年冲淤量的贡献率分别为6.23%、31.56%、25.77%、32.71%和3.73%。     

Erosion and reorientation of the Sapodilla Cays,Mesoamerican Reef Belize from 1960 to 2012

The Sapodilla Cays Marine Reserve in southern Belize includes nine low-relief sand cays that were first surveyed in 1960. The purpose of this study is to reconstruct a 52-year history of the Sapodilla Cays (1960–2012) using a combination of historical topographic surveys, satellite imagery, and additional field data collection. Results suggest that the majority of islands are eroding with some islands having lost over 70% of their area, and many have become swash aligned, which suggests limited sediment availability. The proportion of area lost on each island is related to the width of the reef platform (to the 5?m isobaths) in the direction of the reef edge, while island area is dependent on the width of the reef platform in the direction of the resultant wind. This suggests that the width of the reef platform is a primary determinant of sediment supply between storms that tend to erode the eastern shoreline of the island through refraction along the reef edge. While storm erosion tends to be concentrated along the eastern shoreline through the loss of sediment offshore, alongshore transport to the lagoon shoreline, and the transfer of sediment to the interior of the island, net shoreline retreat is greatest along the lagoon, suggesting that the relatively small winter “northers” and a lack of sediment supply from the reef lagoon are responsible for the observed erosion. Extrapolations based on contemporary loss-rates suggest that the smallest cays will disappear by 2020, while the largest cays will begin to disappear by the end of century.     

3D Structural,Facies and Petrophysical Modeling of C Member of Six Hills Formation,Komombo Basin,Upper Egypt

Natural Resources Research - Two main reservoirs are producing in Komombo Basin: the first one belongs to the C Member of the Six Hills Formation, and the second belongs to the Albian/Cenomanian...