白令海和楚科奇海表层沉积硅藻分布特征

对我国第二次和第三次北极科学考察在白令海和楚科奇海获取的部分表层沉积物样品进行了详细的硅藻分析,旨在了解白令海和楚科奇海表层沉积硅藻的主要分布情况。研究发现海冰对北极硅藻有着显著的影响,在最小冰边缘线以北海域,由于常年被海冰覆盖,表层沉积物中的硅藻数量极少甚至缺失,而在此范围以南海域,硅藻含量则甚为丰富。白令海和楚科奇海表层沉积物中最主要的硅藻种类及组合有：角毛藻休眠孢子(Chaetoceros resting spores),海冰硅藻组合(以Fragilariopsis oceanica和Fragilariopsis cylindrus为代表),极地硅藻组合(优势种有Bacterosira bathyomphla,Thalassiosira antarctic v. borealis及其休眠孢子),沿岸底栖硅藻组合(主要有Paralia sulcata和Delpheneis surirella),诺氏海链藻(Thalassiosira nordenskioeldii)和塞米新细齿藻(Neodenticula seminae)等。上述硅藻种类及组合具有显著的空间分布差异性,并与现代海洋环境因素密切相关,因此对于白令海和楚科奇海古海洋环境研究具有重要意义。     

白令海表层沉积硅藻的种类组成与分布

摘要 利用2010年中国第四次北极科学考察白令海获取的6个站位的沉积物样品,分析了表层1cm的沉积硅藻,共检出分属于37个属的101个硅藻种（含变种和变型）,并编制了种类名录。这些种类可分为4个生态类群：（1）广温种;(2)北方温带种;(3)极地种;(4)海冰种。白令海西南海盆区以北方温带种占绝对优势,主要有Neodenticula seminae,Thalassiosira trifulta,Rhizosolenia hebetata f. hiemalis、Actinocyclus curvatulus;而在东北陆架区以极地种为主,主要包括Fragilariopsis oceanica,Thalassiosira antarctica spora,Thalassiosira nordenskioeldii、Thalassiosira hyalina。海盆区站位沉积硅藻丰度最高,为3.7×106个/g湿重(不包括角毛藻休眠孢子）,而东部陆架区丰度最低,仅有0.7×106个/g。本文同时探讨了表层沉积硅藻分布与环境的关系。     

2012 年夏季水团输送对挪威-格陵兰海营养盐及浮游植物群落结构的影响

依托2012 年第五次北极科学考察分析了夏季挪威-格陵兰海域营养盐和光合色素的分布情况, 探讨 水团输送对该海域营养盐分布及对该海域浮游植物群落结构分布的影响。结果显示挪威海和格陵兰海域调 查站位上层(200 m)水体中AT 断面的硝酸盐、磷酸盐及硅酸盐平均浓度分别为9.0(±5.0)、0.65(±0.29)和 1.8(±1.6) μmol·L^–1, BB 断面的硝酸盐、磷酸盐及硅酸盐平均浓度分别为8.9(±3.8)、0.71(±0.22)和1.8(± 1.6) μmol·L^–1。挪威海和格陵兰海域上层水体中硅酸盐相对于硝酸盐远远不足, 且呈显著硅限制, 该限制随 纬度的升高有所减轻, 表现为北冰洋入流水的硅酸盐输送。光合色素与温度和营养盐的关系表现为: 与温度 呈正相关, 与营养盐呈负相关。光合色素的分布结果表明, 挪威-格陵兰海域浮游植物群落表层以硅藻或硅 藻和定鞭金藻为主, 次表层(叶绿素最大层)则以硅藻为优势种, 并且硅藻更易聚集于混合层下方温跃层上 方, 定鞭金藻在表层水体低营养盐的条件下更具竞争力。此外, 由于受大西洋入流分支的影响, 浮游植物向挪 威-大西洋流流经区域聚集(温度更高且营养盐充分), 形成区域浮游植物分布差异。     

南极半岛西北海域表层沉积物中硅藻的初步研究

本文对南极半岛西北海域22个表层沉积物中的硅藻进行了初步研究,鉴定出硅藻82种.根据硅藻的数量分布和生态特征,将本区硅藻分为三个组合;1.Yhalassiosiraantarctica—Charcatia actionchilus—Eucampia balautium组合.2.Th.antarctica——Nitzschiakerguelensis—Coscinodiscus lentignosus组合.3.Coscinodiscus lentiginosus——Eucampiabalaustium—Nitzschia kerguelesis—Schimperiella antarctica组合.文章还通过沉积物中和水体中硅藻的对比,水动力状况,以及海水对硅藻壳体的溶解作用等特征.讨论了区内硅藻壳体的沉积作用.     

滇池内湖滨带底泥的有机质分布规律

2008年4月,用自制柱状采泥器及彼德森采泥器在滇池草海和外海采集内湖滨带底泥柱状样(每5 cm分一层)和表层样(0～10 cm).其中,草海内湖滨带底泥表层样12个,柱状样9个;外海内湖滨带底泥表层样22个,柱状样7个.研究结果表明,滇池内湖滨带底泥表层有机质含量为2.20～154.62 g/kg,滇池草海内湖滨带底泥中平均有机质含量为76.94 g/kg,明显高于外海(16.56 g/kg),这主要是因为草海是沼泽化湖湾且附近村落密集;草海内湖滨带底泥有机质含量的最大值出现在西岸,而外海内湖滨带底泥有机质含量也是西岸高于东岸,这主要是由于周围农业和渔业的影响所致.由于外源污染输入量及湖内自净能力等的综合作用逐年波动,使内湖滨带底泥有机质含量垂直分布未明显随深度增加而一直增加或降低.滇池内湖滨带底泥表层pH为7.03～7.96,略偏碱性,外海内湖滨带底泥pH水平略高于草海,底泥含水率除个别采样点外变化不大,多数低于50%.     

南极附近水域微小型藻类的研究 Ⅳ．中山站潮间带微小型硅藻的分布

本文首次报道东南极中山站沿岸潮间带冰融期砂和砾质砂中微小型硅藻的分布、种类组成及各站位间种类组成的相似性。中山站潮间带微小型硅藻主要分布在中山湾Ｂ站，１９８９年１月和１９９０年２月每克砾砂细胞丰度分别在０．８×１０３～３６５１×１０３个和４．５×１０３～２６１８×１０３个，并具有细胞个体小、丰度大等特点，其优势种为冰川舟形藻Ｎａｖｉｃｕｌａｇｌａｃｉｅｉ。     

白令海深海异常沉积特征及成因分析

利用中国历次北极科学考察航次在白令海北部陆坡及海盆等深水区所采集的沉积物样品,对其开展沉积学等研究,系统归纳该海域常见的异常沉积类型及特征,并初步探讨其可能成因。BR02孔出现至少3段浊积层,浊积层主要分布于末次冰消期至中全新世。B5-4孔存在至少2段火山碎屑沉积层,其沉积年代分别约为1.3 ka BP和13.2 ka BP。B5-7站表层沉积物中的硅藻组合以新近系硅藻化石Kisseleviella carina Sheshukova-Poretzkaya和Kisseleviella ezoensis Akib为主,且与附近海域其他表层沉积物的硅藻组合面貌差异明显,可能是沉积物再沉积结果,其初始沉积年代大约为早中新世。白令海北部陆缘/陆坡区附近遍布的海底大峡谷对该区沉积物沉积过程具有重要影响,可能是导致该区浊流沉积与再沉积物的主要原因。此外,白令海位于欧亚板块、太平洋板块及北美板块交汇区边缘,其独特的地理位置决定该区地震与火山等构造活动相对活跃,进而进一步促使该区海底异常沉积现象频发。     

白令海和楚科奇海测区沉积物硫酸盐还原菌初步研究

用 MPN法测定了取自白令海和楚科奇海 35个沉积物样品中的硫酸盐还原菌 (SRB)含量。所有样品的 SRB平均含量约 1 .68× 1 0 5个 .g- 1,变幅约为 0～ 2 .2 8× 1 0 6个 .g- 1。分析并比较了 SRB含量在表层、次表层或混合层样中及不同站位、测区间的差异 ,大体看来 ,SRB含量表层少于次表层。若以白令海峡为界 ,在海峡两侧 SRB含量的增加呈相反趋势 :即在白令海呈向南增加、在楚科奇海呈向北增加的趋势 ;经向分布也显示出相反的趋势 :在白令海呈向东增加、在楚科奇海呈向西增加的趋势。结果还表明 SRB在不同培养温度中有各自的出现率 ,反映测区SRB以适冷菌为主。温度是其主要控制因子。相当多的中温菌也有出现     

北部湾北部滨海湿地水体和表层沉积物中营养元素分布与污染评价

2009年4～5月,对北部湾北部滨海湿地水体和表层沉积物进行了取样调查,研究水体中营养盐和表层沉积物中碳、氮和磷元素含量、分布及其影响因素,并在此基础上评价了滨海湿地水体富营养化水平和表层沉积物的污染状况.研究区水体中的溶解无机氮(dissolved inorganic nitrogen,DIN)、活性磷酸盐PO43-—P和化学需氧量(CODMn)平均含量分别为(211.84±37.44) μg/L、(11.01±12.11) μg/L和(0.92±0.32) mg/L;表层沉积物中总氮(TN)、总磷(TP)和总有机碳(TOC)的平均含量分别为(373±355) μg/g、(232.28±157.34) μg/g和(0.45±0.46)％.北部湾北部滨海湿地水体中的DIN含量和PO43-—P含量在茅尾海和廉州湾东部西场海区都很高,且水体富营养化比较严重,大规模的海水养殖可能是造成该现象的主要原因.研究区水体中CODMn含量空间分布呈近岸高、远岸低的特征.研究区铁山港顶部、南流江口、大风江口、钦江和茅岭江口较细的表层沉积物中的TN、TP和TOC含量较高.研究区表层沉积物的TOC/TN值分布表明,钦江口、钦州港区、防城港、企沙港区和珍珠湾东北部的沉积物有机质含量受到了强烈的陆源影响.根据加拿大安大略省环境质量评价标准,除了钦州湾顶部的龙门港区、大风江口中部和铁山港顶部西北角一小部分区域的表层沉积物中的TOC、TN和TP含量分别略高于1％、550μg/g和600μg/g,已被明显污染,而处于最低级别或严重危害级别,会对部分底栖生物产生影响外,其他绝大部分区域都属安全级别,为清洁或部分已被轻微污染.     

白令海北部陆坡全新世以来的生物标志物记录及其古环境意义

通过白令海北部陆坡区B2-9站位沉积物柱样高分辨率的生物标志物(菜子甾醇、甲藻甾醇、长链烯酮、n-C30-diol)提取和分析,获得了近1万年来浮游植物群落和初级生产力、高碳烷烃输入与陆源植被变化等相关记录,研究结果显示,全新世以来表层浮游植物和初级生产力都经历了"高-低-高"的变化过程,并具有明显的阶段性,可能受控于陆架坡折处海冰的分布、上层海洋营养盐供应和全新世气候与环境的变迁;浮游植物群落结构较为稳定,硅藻是初级生产力的主要贡献者,甲藻次之,颗石藻和黄绿藻比前两者低了1个数量级,硅藻与甲藻之间具有明显的竞争关系,前者明显占据优势,是白令海有机碳汇的主要贡献者;正构烷烃总量分别在7.8 ka BP,6.7 ka BP和5.4 ka BP,经历了3次阶梯状的下降过程,并呈现出4个相对稳定的阶段,其主要受控于早全新世海平面上升以及周边陆地植被源区的气候与环境变化;正构烷烃分子组合特征显示其来自陆地高等植物、且陆源植被结构较为稳定,木本植物占据优势;单体碳同位素研究表明正构烷烃的主碳峰为n-C27,对烷烃总量的贡献最大,可能与当时陆源繁盛的木本植物及输入有关,含量较高的n-C23则可能主要来源于北半球沿海广泛分布的一类沉水植物。     

Ancient Eskimo dwelling sites and Holocene relative sea-level changes in southern Disko Bugt, central West Greenland

A coordinated geological-archaeological investigation has been carried out in southern Disko Bugt with the primary purpose of elucidating Holocene relative sea-level (RSL) changes. Two RSL curves representing the Early-Middle Holocene emergence of respectively southeastern and southwestern Disko Bugt have been constructed. Elevations of paleo-Eskimo sites of different ages have been surveyed and supplemented with similar elevations compiled from the literature. Detailed investigations have been carried out at two partly submerged Dorset I sites. At both sites, the stratigraphy of the foreshore has been recorded in terrain profiles.
It is concluded that the RSL history of southern Disko Bugt was one of steady emergence during Early-Middle Holocene followed by submergence in Late Holocene. The stratigraphy of the foreshore at the two Dorset I sites indicates that RSL has been at least 2-2.5 m below sea-level, and that the Transgression to present sea-level started after ca 1 ka B.P.     

The net phytoplankton in Kongsfjorden, Svalbard, July 1988, with general remarks on species composition of arctic phytoplankton

Examination of 17 samples collected by a 20 μm meshed meshed net in Kongsfjorden, Svalbard, 8–19 July 1988, showed a dominance of dinoflagellates and the chrysophyte Dinobryon Balticum in the surface layers, whereas the diatom and the haptophyte Phaecystis pouchetii abundance increased with depth. The diatom Pseudo-nitzschia granii appeared together with P. pouchetii through the whole water column, and Actinocyclus curvatulus was one of the few diatoms present also in the surface samples. Two samples, from 15 and 50 m, respectively, were cleaned of organic material and mounted in Naphrax for a more critical identification of the diatoms. We were able to group the species according to habitats, especially types of ice. The planktonic Thalassiosira antarctica var. borealis, T. hyalina, T. nordenskioeldii, Bacterosira bathyomphaia, Chaetoceros furcellatus, C. socialis and Fragilariopsis oceanica were present mainly as resting stages representing a post-bloom situation. These species and T. gravida appear early in the season and may have started to grow already under the ice. Fragilariopsis cylindrus and F. oceanica seem to have a closer affinity to ice than Thalassiosira and Chaetoceros spp. although they are common in the plankton. Some Nitzschia species which are usually regarded as typical sea-ice diatoms and have thicker and older ice as the main habitat were present only in small cell numbers in the plankton samples. The last component, evidently introduced from Atlantic water in the Norwegian Sea, consisted of diatoms with a more oceanic distribution, e. g. Fragilariopsis pseudonana and a small form of Thalassiosira bioculata .     

Re-exposed basement landforms in the Disko region, West Greenland — disregarded data for estimation of glacial erosion and uplift modelling

Classifications of large-scale landscapes in Greenland have traditionally been based on type and intensity of glacial erosion, with the general idea that present landforms are mainly the result of erosion from ice sheets and glaciers. However, on southern Disko and in areas offshore in Disko Bugt, a basement surface has preserved remnants of weathered gneiss and pre-Paleocene landforms, recently exhumed from Paleocene basalt. Isolated hills and lineaments have been mapped in a digital terrain model and aerial photographs. Offshore have hills been mapped from seismic lines. The medium size bedrock forms on southern Disko as tors, clefts and roche moutonées have been studied in the field. Remnant saprolites were inventoried, sampled and analysed according to grain size and clay mineralogy. The basement surface retains saprolites up to 8 m thick in close relation to the cover rocks. The landforms in the basement rocks belong essentially to an etched surface only slightly remodelled by glacial erosion and, below the highest coastline, also by wave action. The outline of hills is governed by two lineament directions, ENE–WSW representing the schistocity of the gneiss and NW–SE fracture zones. These structures are thus interpreted to have been exploited by the deep weathering while the frequent N–S lineaments have not and thus might be younger. Main ice-flow has been from the NE and has resulted in plucking of SW facing lee sides, however the resulting bedrock forms are mainly controlled by structures and orientation of joints. The identification of re-exposed sub-Paleocene etch forms on Disko and the hills of similar size offshore, forming a hilly relief, have implications for identification of a hilly relief south of Disko Bugt, its relation to younger planation surfaces as well as for conclusions of uplift events.     

Holocene talus accumulation rates,—and their influence on rock glacier growth. A case study from Igpik,Disko—West Greenland

Frich, Povl and Brandt, Erik: Holocene talus accumulation rates,—and their influence on rock glacier growth. A case study from Igpik, Disko—West Greenland. Geografisk Tidsskrift 85: 32–44 Copenhagen, October 1985.

The Igpik area is located ten km east of Godhavn on the south-coast of the island Disko. Geologically the area is dominated by Tertiary basalt formations.

A general geomorphological classification of this area, which covers approximately three square kms, has been made. Based on radiocarbon ages of former marine levels in the Disko Bugt area, the beginning of talus accumulation has been determined for two talus cones situated on raised beaches. They have ages of 5800 and 7900 ¹⁴C y. B.P. Using theodolite readings, the volumes of three different talus cones have been determined and two average talus accumulation rates have been calculated for the cones located on raised beaches. These values are transformed into an average Holocene rockwall retreat rate of 0.0005 and 0.0015 m/year, respectively. The total volume of two lobate rock glaciers is calculated to be 2.2 mill, cu.m and as they are located inside 9000 years old local moraines, the average Holocene mass-transfer through the third talus cone has been estimated to 1.4 10⁶ tons×m/sq.km/y. Finally the results are discussed, with reference to other areas, and as a possible threshhold for the initiation of rock glaciers.     

南极长城湾网采浮游植物的数量分布

198 5年 2月在南极长城湾进行了浮游植物采样 ,在鉴定出的 3 1种浮游植物中 ,冷水性种类占的比例最大。湾内浮游植物细胞数量平均为 1 6 2 .5× 1 0 4 个 / m3 ,其分布湾内低于湾口。优势种类为聚生角刺藻、无刺冀根管藻和条纹盒形藻 ,前者的分布集中于湾内 ,后两者密集在湾口。     

A Compilation of Radiocarbon Dates from Disko Bugt,Central West Greenland/Meteorological Observations in 1996 at the Arctic Station,Qeqertarsuaq (Godhavn), Central West Greenland/A Discussion on Pingos in Mellemfjord,Disko, Central West Greenland/Open System Pingos in Mellemfjord,Disko, Central West Greenland: A Reply to Gurney and Worsley

188 new and previously published radiocarbon dates on Holocene material from Disko Bugt, central West Greenland, are presented together with relevant informations (laboratory number, place name, dated material, geografic coordinates, altitude and δ¹³C-value) about the dates.

In October 1990 an automatic weather station was established at the Arctic station (65 °15′N,53 °31′W), Qeqertarsuaq (Godhavn), Central West Greenland. The Station register parameters each 20 min., and the parameters have been described in an earlier paper in this journal by Nielsen et al. (1995). The present paper summarises main points of the climate during 1996.

Open system, or more correctly, hydraulic pingos, are genetically poorly understood. A continuing problem concerns their need for a perennial groundwater supply (intra- or sub-permafrost). This has to be maintained despite the existence of continuous permafrost in many areas where they are located. Recent work on Disko Island has suggested a new type of hydraulic pingo developing only in a “marsh environment”. It is argued that the marsh setting is not relevant to the formation of these features and that they are simply hydraulic pingos.

Abstract

A group of marsh initiated open system pingo remnants from the Iterdlagssûp kûgssua valley mouth, in Mellemfjord, Disko Island, Central West Greenland was described in Christiansen (1995). Gurney and Worsley (1997) state that the location of this group of pingo remnants in the Iterdlagssûp kûgssua valley mouth is of no relevance to their genesis, and that they presumably were the result of an assumed late Holocene sea level regression, causing permafrost to be established in the valley bottom. In this reply the arguments by Gurney and Worsley (1997) on the Iterdlagssûp kûgssua valley pingos are commented, and it is argued by way of sea level information, frost penetration and water supply that the special setting must indeed have caused pingo initiation and growth. Furthermore, the area has experienced a relative sea level rise during the late Holocene.     

Bottom sediments in Ho Bugt—a wadden sea environment

Pejrup, Morten: Bottom sediments in Ho Bugt—a wadden sea environment. Geografisk Tidsskrift 81: 11–16, Copenhagen, June 1981.

Twenty eight samples of bottom sediment from Ho Bugt, located at the west coast of Jutland, have been anlysed, and the variations within the fine and the coarse fractions described in detail. A method for classifying estuarine- and wadden-sea sediments is presented. The classification together with special characteristics found for the coarse fraction is used as a basis for a sediment chart for the northern part of Ho Bugt.