Radiometric dating of lake sediments from Signy Island (maritime Antarctic): evidence of recent climatic change

Sediment cores from three lakes (Moss, Sombre and Heywood) in the maritime Antarctic (Signy Island, South Orkney Islands) have been successfully dated radiometrically by²¹⁰Pb and¹³⁷Cs. The core inventories of both fallout radionuclides are an order of magnitude higher than that which can be supported by the direct atmospheric flux at this latitude. The elevated values may be explained by fallout onto the catchment during the winter being delivered directly to the lakes during the annual thaw. Two of the lakes (Sombre and Heywood) show marked increases in sediment accumulation afterc. 1950. This appears to be associated with a documented rise in temperature in the South Orkney Islands, which has caused extensive deglaciation at Signy Island.This is the tenth of a series of papers to be published by this journal following the 20 ^th anniversary of the first application of²¹⁰Pb dating of lake sediments. Dr P.G. Appleby is guest editing this series.     

烟台海域海难事故气象条件分析及预防对策

通过对1990－1999年烟台辖区海域海难事故资料及烟台海区相关气象资料统计分析，得出烟台沿海及附近海域难事故发生的一般规律及其与气象的关系，并提出了海难事故的预防对策。     

Quantitative models for reconstructing catchment ice-extent using physical-chemical characteristics of lake sediments

The physical characteristics of surface sediments from a suite of pristine lakes on Signy Island, maritime Antarctic, were used to develop a quantitative link between catchment ice-extent and lake-sediment response. Percentage dry weight, median particle size, percentage loss-on-ignition and wet density of the lakes' surface sediments were the most significant variables explaining contemporary catchment ice-extent. Two independent reconstruction models – Partial Least Squares (PLS) and a Modern Analog Technique (MAT) – were applied to dated sediment cores at two sites on Signy Island. The validity of the reconstructions was tested against historical information on catchment ice-extent. With sufficiently high sedimentation rates and sampling resolution, the models can predict sub-decadal changes in ice-extent. The model results are best regarded as indicators of erosion resulting from meltwater activity in the catchment. Comparison of results with Twentieth Century climate records affirms the hypothesis that climatic warming is the most likely cause for the ice retreat observed on Signy Island during the last 40 yrs. Similar reconstruction models using these simple sedimentary measures could be developed for analogous locations in the Antarctic and in Arctic and Alpine regions.     

Surface NO and NO2 mixing ratios measured between 30° N and 30° S in the Atlantic region

Surface NO and NO₂ mixing ratios were measured aboard the research vessel Polarstern during the mission ANT VII/1 from 24 September to 5 October 1988. The measurements were taken along the meridian at 30° W in the Atlantic region covering latitudes between 30° N and 30° S. The average mixing ratios were about 12 pptv NO/30 pptv NO₂ in the Northern Hemisphere and about 7 pptv NO/22 pptv NO₂ in the Southern. Elevated mixing ratios of 20 pptv NO/70 pptv NO₂ were found at 12° N (probably due to air masses originating from the surface of West Africa) and in the region of the ITCZ between 8° N and 5° N. Because of probable contamination by the ship, the measured mixing ratios mostly represent upper limits.     

Factors influencing the distribution of coastal lichens Hydropunctaria maura and Wahlenbergiella mucosa

Responses to abiotic and biotic stresses that potentially drive the vertical zonation of the intertidal lichens Hydropunctaria maura, an upper littoral lichen, and Wahlenbergiella mucosa, a lower littoral lichen, were investigated in field and laboratory experiments. When transplanted, both lichens exhibited an inability to survive outside their normal vertical distribution range. W. mucosa appeared to be unable to tolerate prolonged periods of desiccation following translocation from lower to upper littoral regions, whereas H. maura was unable to survive in lower littoral zones possibly owing to increased grazing pressure. The effect of desiccation in both lichens was compared using pulse amplitude modulated chlorophyll fluorescence and infra‐red gas analysis; results indicated a more hydration‐dependent nature of W. mucosa. Photosynthetic (algal) pigments and phenolic compounds were determined in both lichen thalli, and a range of additional coastal lichens occupying a natural gradient from upper to lower shore levels. Pigment composition and concentration in both lichen thalli were similar whereas levels of phenolic compounds were up to three times higher in W. mucosa than H. maura. Pigment and phenolic concentration and composition exhibited some seasonality across 13 different lichens originating from different shore levels. Phenolic concentration increased towards the lower shore, suggesting a potential anti‐herbivory function. This marks the first study of pigments and phenolics in coastal lichen communities, and prompts further investigations on the particular physiological features of marine and maritime lichens that enable them to thrive in this extreme environment.     

Measurements of stable carbon isotopic composition of ethane and propane over the western North Pacific and eastern Indian Ocean: A useful indicator of atmospheric transport process

Stable carbon isotopic composition of ethane and propane over the western North Pacific and eastern Indian Ocean between 31°N and 26°S was investigated from February through March 2004. The isotopic composition of ethane ranged from −28 to −18‰ and showed a gradual increase from north to south. Conversely, that of propane was between −31 and −24‰; it showed no systematic latitudinal variation. Investigation of the ethane/propane ratio indicates that ethane and propane that originated from northern mid-latitude countries in the eastern part of Eurasia were both transported into the western North Pacific region. However, the results of the isotopic analyses indicate the contribution of oceanic emission to the atmospheric propane during transport, although that contribution can not be discerned for ethane. A ship based stationary observation conducted in the western equatorial North Pacific showed that the isotopic composition of ethane varied from −25 to −19‰ and showed clear systematic diurnal variation: propane ranged between −32 to −26‰ and no such isotopic diurnal signal was observed. The diurnal variation for ethane is explained by entrainment of free tropospheric air, whereas the variation for propane was influenced by oceanic emissions as well as the entrainment. The contribution of oceanic emissions to the atmospheric propane inventory was considered from our isotopic observation. Isotopic composition of dissolved propane is estimated to be less than −38‰, and the contribution up to 79% was calculated when the isotopic composition of dissolved propane is assumed to be −40‰. Our study demonstrates that isotopic analysis can be more useful than ratio-based analysis to improve our present understanding of transport processes, especially for impact of the oceanic emissions on the atmospheric distribution of low level C₂–C₅ non-methane hydrocarbons such as propane in the remote marine atmosphere.     

Construing and constructing the South China Sea beyond state-led environmentalism: Vernacularizing geographical,geopolitical and sociotechnical imaginaries of territory

During the 2010s, the South China Sea (SCS) became a geopolitical flashpoint over the sovereignty of the Paracels and Spratlys. China envisioned its transformation of coral reefs into military bases and island cities as an SCS ‘green construction’ project. This article analyses how the SCS is discursively construed and practically constructed as maritime national territory, by mobilizing fishing legacies and extending state limits through ‘state-led environmentalism’ rhetoric. Drawing on ethnographic fieldwork in China, I show that state-led environmentalism is a hierarchical process that intermittently co-opts and excludes local populations to advance the state's territorial ambitions, which are anchored in geographical, geopolitical and socio-technical imaginaries of ‘maritime civilization’. Yet, I also show that in this process, the SCS emerges as spaces of vernacularized political claims. Thus, I argue that territory is not only a political technology of control but also vernacular practice through which universalizing discourses— whether on the Exclusive Economic Zone regime, sovereignty or nature—are adapted and modified.     

论证南海海疆国界线

追溯探查历史图件,根据1946年内政部方域司编制的一组"南海诸岛位置图"(南海诸岛位置图,南沙群岛,中沙群岛,西沙群岛,西沙群岛永兴岛及石岛,南沙群岛太平岛)和1948年出版的"中华民国行政区域图"分析,南海诸岛外围的断续线段是我国在南海的海疆国界线;当时划定,是与陆域国界相连的,海上国界是陆域国界的延伸,以断续线段表示是国际地图上对海疆国界线通用的表示方法,当时即获国际认可。上述结果为南海划界提供了科学依据。     

加强海洋制图研究助力海洋强国建设

在这篇短文中,主要简述了中国古代的海洋文明,认为海洋与中华民族的生存发展、国家统一强大、人民生产生活休戚相关,阐明海洋测量和制图一直是伴随世界强国发展的重要历史主线,建设现代化的海洋测量制图体系是中国建设海洋强国的需要.     

建设海洋强国的政治学解释——基于注意力配置的分析

基于注意力政治学的领导人注意力分析框架,对自2012年以来建设海洋强国这一国家级海洋战略的启动和实施进行分析,探讨建设海洋强国的作用机制。文章提出：1）领导人与政府有限的注意力是国际体系结构变化与国家行为产生之间的中介变量。2）国际局势变化、地方政府竞争、突发事件刺激和以往的从政经历是建设海洋强国的触发因素,驱使领导人和政府的注意力发生转移。3）领导人通过讲话、批示、视察等活动推动政策实施,这是测量领导人及政府对于建设海洋强国的注意力依据。注意力对建设海洋强国的作用机制体现在：1）国家海洋战略重置后,领导人与政府的注意力继续作用于新海洋战略的实施过程;2）领导人通过自身一系列的活动,如视察、批示,加快海洋战略的运行;3）通过设立高级别机构,高位推动建设海洋强国;4）通过国家媒体对海洋事务的持续议程设置,固定公众和社会注意力。上述作用机制有效地引导并锁定了中国对海洋事务的关注方向与重点,改变了传统中国“重陆轻海”的战略文化与社会认知。