曹娥江流域的淡水贝类

报告了自１９８１年以来历次对曹娥江流域淡水贝类的调查结果。标本经鉴定计有５２种，其中腹足纲６科１３属３２种，瓣鳃纲４科１１属２０种。分析了流域中淡水贝类与栖息环境的关系。探讨了流域中淡水贝类的分布区划及经济意义。     

Differences in stable isotope compositions of freshwater snails from surface sediments of two Polish shallow lakes

The study reports and discusses the differences in δ¹³C and δ¹⁸O values of shells between several species of freshwater snails. Shells were derived from sediment samples collected from depths of 0.5, 1, 2 and 3 m along transects in two shallow eutrophic lakes located in mid-western Poland. Mean δ¹³C values of the shells ranged between −7.5 and −3.8‰ in Lake Jarosławieckie and between −8.1 and −5.2‰ in Lake Rosnowskie Duże, whereas mean δ¹⁸O values ranged between −2.2 and −0.2‰ and between −2.2 and 0.4‰ respectively in the studied lakes. A similar order of species in terms of shell isotope values, from least to most ¹³C and ¹⁸O-depleted was observed in both lakes and seems to indicate constancy of the factors controlling the stable isotope compositions of snail shells. We postulate that the nearly 4‰ difference in the mean carbon stable isotope values between the species was primarily controlled by the amount of metabolic carbon incorporated into the shells and the δ¹³C values of the snail food. Different growth cessation temperatures and microhabitats of the species studied result in temporally and spatially varied DIC δ¹³C values, water δ¹⁸O values and water temperature of shell precipitation, and may thus differentiate the δ¹³C and δ¹⁸O values of shells. The range of δ¹³C and δ¹⁸O values of individual shells from a sediment sample (mean 2.35 and 2.15‰, respectively) is interpreted as reflecting an intraspecific variability of isotope compositions in shells from a population and changes of the ambient conditions during the accumulation of the sediment layer. The species-specificity and intraspecific variability in C and O isotopic compositions of shells allow concluding that in palaeolimnological studies, stable isotope analyses should be performed on a set of mono-specific shells representing mean isotope compositions of the species for the interval studied rather than single shells or multispecific bulk shell material.     

19种淡水鱼类的生活史类型研究

研究了中华鲟、达氏鳇、施氏鲟、青鱼、草鱼、鲢、鳙、鲤、赤眼鳟、大眼鳜、鳜、黄尾密鲴、银鲴、花、、团头鲂、尖头塘鳢、鲫等19种淡水鱼类的生态参数（L∞、W∞、K、Tm、Tmax、M、PF）和生活史类型。3种鲟鱼类属k-选择,青鱼、草鱼、鲢、鳙偏向r-选择,其它12种鱼类属r-选择。种群繁殖力PF的数值大体上可反映出某种鱼类的生活史类型,运用Beverton－Holt平衡产量模式估算表明,只有合理控制捕捞强度和起捕年龄,既能保护资源,又能获得较好的经济效益。     

Les événements de la limite Permien–Trias : derniers survivants et/ou premiers re-colonisateurs parmi les ostracodes du Taurus (Sud-Ouest de la Turquie)The events of the Permian–Trias boundary: last survivors and/or first colonisers among the ostracods of the Taurides (southwestern Turkey)

Very few data on Early Triassic marine ostracods are available. In most of cases, the data concern the upper part of the Early Triassic. The Çürük da? section, located in the Western Taurides (Turkey), well stratigraphically constrained by conodonts and foraminifera, has been re-sampled for ostracod study. A significant fauna has been discovered in the Late Permian and the levels of the Earliest Triassic (Hindeodus parvus and Isarcicella isarcica staeschei zones). The ostracods of the basis of the Kokarkuyu Fm. are the oldest Triassic forms ever discovered. The occurrence of Palaeocopes in the earliest Triassic and similarity between the Permian and Induan assemblages suggest that the Lower Triassic Çürük da? ostracods represent a survival assemblage after the Permo-Triassic mass-extinction. To cite this article: S. Crasquin-Soleau et al., C. R. Geoscience 334 (2002) 489–495.     

Evidence for 17th-century tsunamis generated on the Kuril–Kamchatka subduction zone, Lake Tokotan, Hokkaido, Japan

In the seventeenth century, two tsunamis that were generated by earthquakes on the Kuril–Kamchatka subduction zone inundated the eastern coast of Hokkaido, northern Japan. Stratigraphic evidence for these two tsunamis and related land-level change in coastal Hokkaido consists of two landward-thinning sand layers in the sediments of Lake Tokotan, a coastal lagoon on the Hokkaido coast. The marine origin of these sand layers is indicated by the presence of brackish–marine diatoms. The rarity and high degree of fragmentation of diatom valves suggests that the sands were transported in a short time over a considerable distance. Tsunamis at this site were probably generated by great earthquakes along the Kuril–Kamchatka Trench. Volcanic ash deposits lying just above the sands suggest that tsunamis occurred in the late 17th century. Tsunamis during the historic period are not recorded in Lake Tokotan, which suggests that the sand layers were deposited by tsunamis substantially larger than historic tsunamis.     

西藏地区现代沉积物中介形类环境指示意义初探

于2008和2012年先后2次从西藏阿里和那曲地区61个不同水体,包括不同盐度的湖泊、湿地、浅水坑和河流等,共采集了78个水体表层沉积物样品,用以研究该地区现生介形类的生态分布及其环境指示意义.经鉴定,阿里和那曲地区现生介形类共计11属38种.除Ilyocypris neoaspera等5个种外,本次调查的介形类各属种均在湖泊中出现,尤以Limnocythere dubiosa的总壳瓣数最为丰富.Ilyocypris属中除Ilyocypris subdunshanensis和Ilyocypris xizangensis外,其余各种均喜浅水坑的小型浅水环境.Leucocythere dilitata、Limnocythere dubiosa、Limnocytherellina kunlunensis和Eucypris rischtanica为该地区的广盐种.其中Limnocythere dubiosa和Leucocythere dilitata适应盐度范围最广,在不同盐度的各类水体中均有出现.本次研究中的介形类均喜碱性水体,在p H值为8~9的水体中介形类各属种的丰度值达到最大.     

Ecophysiological Studies on Size-fractionated Phytoplankton Populations by Tracer Technique in Wadi el Majanin Dam,Libya

Wadi el Majanin, one of the largest hydraulic structures in Libya was studied for ecophysiological aspects in relation to ambient environment. The waterbody is alkaline (pH=7.2) and characteristic of hydrogen-carbonate (144.8 mg L^–1 CaCO₃) system. Vertical extinction coefficients (> 4.8) indicate very high (biogenic) turbidity. Conspicuous variations of a quantitative kind in algal development (e.g., Pediastrum bloom) together with abundant diatom populations (chlorococcales-diatom assemblage), apart from very common occurrence of cyanobacteria and euglenoids show eutrophic water condition. Winter-summer alternation induced pronounced seasonal variability in the rates of in situ planktonic algal photosynthetic activities (285.7...1305 mg m^–3 d^–1 C). Dark fixation activity, attributed largely to bacterial production, oscillated by order of 2-fold magnitude, characterized by summer maxima (47.6 mg m^–3 d^–1 C). Size-fractional analysis established that smaller forms (< 60 μm), broadly regarded nanno-phytoplankton, frequently dominated (c. 70%) overall algal productivity.     

The provenance,petrology and sedimentology of building stone in Bromyard,Herefordshire, UK

A multi-disciplinary study was undertaken of the Lower Old Red Sandstone building stones of Bromyard, Bromyard Downs and Bringsty Common, Herefordshire, UK, to trace their original quarry sources. 196 stone structures were recorded in detail and 3 broad lithological groups recognised. Combining old maps, archival sources, Light Detection and Ranging (LiDAR) data and testimony of local residents, the historic quarries in the area have been mapped. Field studies of the geology of quarries and outcrops have established the area of origin of two distinctive coarse grained lithologies. Intraformational conglomerates have been demonstrated, with some confidence, to be derived from Bromyard itself. Coarse, pebbly, quartzose sandstones have been traced to Bringsty Common and shown to be used only in the church in Bromyard before the 20th century. The origins of fine grained sandstone are found to be more complex. Through a combination of fieldwork and archival research, Clater Park Quarry is indicated as the origin of high quality green sandstones in Bromyard. 15 samples of sandstone from the Bromyard Downs, have been petrographically analysed by point counting to determine their clastic and mineralogical proportions. Early results of this analysis are presented which show modal variation in lithics, feldspars and cements that may serve to link quarries to buildings. Finally, it is suggested that at least some of the diversity of stone present in Bromyard is the result of slight variation in depositional processes in the immediately underlying bedrock.     

Liquid freshwater transport and Polar Surface Water characteristics in the East Greenland Current during the AO-02 Oden expedition

Dynamical features of the East Greenland Current (EGC) are synthesized from a survey conducted by the Swedish icebreaker Oden during the International Arctic Ocean - 02 expedition (AO-02) in May 2002 with emphasis on the liquid freshwater transport and Polar Surface Water. The data include hydrography and lowered acoustic doppler current profiler (LADCP) velocities in eight transects along the EGC, from the Fram Strait in the north to the Denmark Strait in the south. The survey reveals a strong confinement of the low-salinity polar water in the EGC to the continental slope/shelf—a feature of relevance for the stability of the thermohaline circulation in the Arctic Mediterranean. The southward transport of liquid freshwater in the EGC was found to vary considerably between the sections, ranging between 0.01 and 0.1 Sverdrup. Computations based on geostrophic as well as LADCP velocities give a section-averaged southward freshwater transport of 0.06 Sverdrup in the EGC during May 2002. Furthermore, Oden data suggest that the liquid freshwater transport was as large north of the Fram Strait as it was south of the Denmark Strait.     

Late-glacial paleoenvironment of Lake Algonquin sediments near Clarksburg,Ontario

Excavation below the Lake Algonquin gravel beach bar near Clarksburg, Ontario, exposed mollusc-bearing clay over a lens of plant debris. This is the northernmost and most deeply buried Lake Algonquin fossil site found thus far in Ontario. It is the first site to provide dates from directly below the Algonquin beach bar. Two radiocarbon dates of about 11 200 years confirm the age of isostatically transgressing Lake Algonquin. Plant macrofossils (21 taxa), pollen (39 taxa), molluscs (12 taxa), and ostracodes (18 taxa) indicate that the climate was colder than present by several degrees and the forest-tundra ecotone was nearby initially but retreated northward rather quickly. Upward increases in abundances and diversity of molluscs and ostracodes suggest it was a time of rapid migration and colonization of species.Deceased, 1 November 1994This is the 7th in a series of papers published in this special AMQUA issue. These papers were presented at the 1994 meeting of the American Quaternary Association held 19–22 June, 1994, at the University of Minnesota, Minneapolis, Minnesota, USA. Dr Linda C. K. Shane served as guest editor for these papers.