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Sample records for lake tanganyika east

  1. Hydrothermal vents is Lake Tanganyika, East African Rift system

    SciTech Connect

    Tiercelin, J.J.; Pflumio, C.; Castrec, M.

    1993-06-01

    Sublacustrine hydrothermal vents with associated massive sulfides were discovered during April 1987 at Pemba and Cape Banza on the Zaire side of the northern basin of Lake Tanganyika, East African Rift system. New investigations by a team of ten scuba divers during the multinational (France, Zaire, Germany, and Burundi) TANGANYDRO expedition (August-October 1991) found hydrothermal vents down to a depth of 46 m along north-trending active faults bounding the Tanganyika rift on the western side. Temperatures from 53 to 103 {degrees}C were measured in hydrothermal fluids and sediments. Veins of massive sulfides 1-10 cm thick (pyrite and marcasite banding) were found associated with vents at the Pemba site. At Cape Banza, active vents are characterized by 1-70-cm-high aragonite chimneys, and there are microcrystalline pyrite coatings on the walls of hydrothermal pipes. Hydrothermal fluid end members show distinctive compositions at the two sites. The Pemba end member is a NaHCO{sub 3}-enriched fluid similar to the NaHCO{sub 3} thermal fluids form lakes Magadi and Bogoria in the eastern branch of the rift. The Cape Banza end member is a solution enriched in NaCl. Such brines may have a deep-seated basement origin, as do the Uvinza NaCl brines on the eastern flank of the Tanganyika basin. Geothermometric calculations have yielded temperatures of fluid-rock interaction of 219 and 179 {degrees}C in the Pemba and Cape Banza systems, respectively. Abundant white or reddish-brown microbial colonies resembling Beggiatoa mats were found surrounding the active vents. Thermal fluid circulation is permitted by opening of cracks related to 130{degrees}N normal-dextral faults that intersect the north-south major rift trend. The sources of heat for such hydrothermal systems may relate to the existence of magmatic bodies under the rift, which is suggested by the isotopic composition of carbon dioxide released at Pemba and Cape Banza. 21 refs., 2 figs.

  2. Testing the stages model in the adaptive radiation of cichlid fishes in East African Lake Tanganyika

    PubMed Central

    Muschick, Moritz; Nosil, Patrik; Roesti, Marius; Dittmann, Marie Theres; Harmon, Luke; Salzburger, Walter

    2014-01-01

    Adaptive radiation (AR) is a key process in the origin of organismal diversity. However, the evolution of trait disparity in connection with ecological specialization is still poorly understood. Available models for vertebrate ARs predict that diversification occurs in the form of temporal stages driven by different selective forces. Here, we investigate the AR of cichlid fishes in East African Lake Tanganyika and use macroevolutionary model fitting to evaluate whether diversification happened in temporal stages. Six trait complexes, for which we also provide evidence of their adaptiveness, are analysed with comparative methods: body shape, pharyngeal jaw shape, gill raker traits, gut length, brain weight and body coloration. Overall, we do not find strong evidence for the ‘stages model’ of AR. However, our results suggest that trophic traits diversify earlier than traits implicated in macrohabitat adaptation and that sexual communication traits (i.e. coloration) diversify late in the radiation. PMID:25274371

  3. Upwelling couples chemical and biological dynamics across the littoral and pelagic zones of Lake Tanganyika, East Africa

    E-print Network

    Elser, Jim

    Upwelling couples chemical and biological dynamics across the littoral and pelagic zones of Lake and littoral zones of Lake Tanganyika near Kigoma, Tanzania. During the dry season of 2004, a rise, and phytoplankton chlorophyll in both the pelagic and the littoral zones, demonstrating that upwelling strongly

  4. Lake Tanganyika—A 'Melting Pot' of Ancient and Young Cichlid Lineages (Teleostei: Cichlidae)?

    PubMed Central

    Weiss, Juliane D.; Cotterill, Fenton P. D.; Schliewen, Ulrich K.

    2015-01-01

    A long history of research focused on the East Africa cichlid radiations (EAR) revealed discrepancies between mtDNA and nuclear phylogenies, suggesting that interspecific hybridisation may have been significant during the radiation of these fishes. The approximately 250 cichlid species of Lake Tanganyika have their roots in a monophyletic African cichlid assemblage, but controversies remain about the precise phylogenetic origin and placement of different lineages and consequently about L. Tanganyika colonization scenarios. 3312 AFLP loci and the mitochondrial ND2 gene were genotyped for 91 species representing almost all major lacustrine and riverine haplotilapiine east African cichlid lineages with a focus on L. Tanganyika endemics. Explicitly testing for the possibility of ancient hybridisation events, a comprehensive phylogenetic network hypothesis is proposed for the origin and diversification of L. Tanganyika cichlids. Inference of discordant phylogenetic signal strongly suggests that the genomes of two endemic L. Tanganyika tribes, Eretmodini and Tropheini, are composed of an ancient mixture of riverine and lacustrine lineages. For the first time a strong monophyly signal of all non-haplochromine mouthbrooding species endemic to L. Tanganyika (“ancient mouthbrooders”) was detected. Further, in the genomes of early diverging L. Tanganyika endemics Trematocarini, Bathybatini, Hemibatini and Boulengerochromis genetic components of other lineages belonging to the East African Radiation appear to be present. In combination with recent palaeo-geological results showing that tectonic activity in the L. Tanganyika region resulted in highly dynamic and heterogeneous landscape evolution over the Neogene and Pleistocene, the novel phylogenetic data render a single lacustrine basin as the geographical cradle of the endemic L. Tanganyika cichlid lineages unlikely. Instead a scenario of a pre-rift origin of several independent L. Tanganyika precursor lineages which diversified in ancient rivers and precursor lakes and then amalgamated in the extant L. Tanganyika basin is put forward as an alternative: the 'melting pot Tanganyika' hypothesis. PMID:25928886

  5. Big fish, little divergence: phylogeography of Lake Tanganyika’s giant cichlid, Boulengerochromis microlepis

    PubMed Central

    Koblmüller, Stephan; Odhiambo, Elizabeth A.; Sinyinza, Danny; Sturmbauer, Christian; Sefc, Kristina M.

    2014-01-01

    The largely endemic cichlid species flocks of the East African Great Lakes are among the prime examples for explosive speciation and adaptive radiation. Speciation rates differ among cichlid lineages, and the propensity to radiate has been linked to intrinsic and extrinsic factors such as sexual selection and ecological opportunity. Remarkably, only one cichlid tribe—the Boulengerochromini—comprises just a single species, Boulengerochromis microlepis, a predominantly piscivorous endemic of Lake Tanganyika and the world’s largest cichlid. While the lineage diverged from its closest relatives at the onset of the Lake Tanganyika radiation >8 MYA, mitochondrial control region sequences collected in this study dated the most recent common ancestor of B. microlepis to ~60–110 KYA. There was no evidence of phylogeographic structure in the lake-wide sample. Patterns of genetic diversity and demographic analyses were consistent with slow and steady population growth throughout the reconstructed timescale. Additionally, the shallow divergence within the species may be related to a possibly large variance in reproductive success in this highly fecund species. Trophic niche space restriction by sympatric piscivores, lack of geographic structure, low potential for sexual selection arising from the monogamous mating system and extinction may have contributed to keeping the lineage monotypic. PMID:25983338

  6. Tempo and Mode of Diversification of Lake Tanganyika Cichlid Fishes

    E-print Network

    Cotton, James

    diversification rates have been more than six times slower than in the species flocks of Lakes Victoria and Malawi dichromatic haplochromines, which have speciated explosively in Lakes Victoria and Malawi, have displayedTempo and Mode of Diversification of Lake Tanganyika Cichlid Fishes Julia J. Day1,2 *, James A

  7. Mating and Parental Care in Lake Tanganyika's Cichlids

    PubMed Central

    Sefc, Kristina M.

    2011-01-01

    Cichlid fishes of Lake Tanganyika display a variety of mating and parental care behaviors, including polygamous and monogamous mouthbrooding and substrate breeding, cooperative breeding, as well as various alternative reproductive tactics such as sneaking and piracy. Moreover, reproductive behaviors sometimes vary within species both in space and in time. Here, I survey reports on mating and parenting behaviors of Lake Tanganyika cichlid species and address the evolution of mating and parental care patterns and sexual dimorphism. Notes on measures of sexual selection intensity and the difficulties of defining mating systems and estimating selection intensities at species level conclude the essay. PMID:21822482

  8. HISTORICAL AND MODERN FLUCTUATIONS OF LAKES TANGANYIKA AND RUKWA AND THEIR RELATIONSHIP

    E-print Network

    Nicholson, Sharon E.

    ; Nicholson 1995). Though Lake Victoria's rise was the most dramatic, Lake Tanganyika rose over two meters Africa. With a surface area of 32,600 km2 , it is less than half the size of Lake Victoria, but drainsHISTORICAL AND MODERN FLUCTUATIONS OF LAKES TANGANYIKA AND RUKWA AND THEIR RELATIONSHIP TO RAINFALL

  9. What prevents outgassing of methane to the atmosphere in Lake Tanganyika?

    NASA Astrophysics Data System (ADS)

    Durisch-Kaiser, Edith; Schmid, Martin; Peeters, Frank; Kipfer, Rolf; Dinkel, Christian; Diem, Torsten; Schubert, Carsten J.; Wehrli, Bernhard

    2011-06-01

    Tropical East African Lake Tanganyika hosts the Earth's largest anoxic freshwater body. The entire water column holds over 23 Tg of the potent greenhouse gas methane (CH4). Methane is formed under sulphate-poor conditions via carbon dioxide reduction or fermentation from detritus and relict sediment organic matter. Permanent density stratification supports an accumulation of CH4 below the permanent oxycline. Despite CH4 significance for global climate, anaerobic microbial consumption of CH4 in freshwater is poorly understood. Here we provide evidence for intense methanotrophic activity not only in the oxic but also in the anoxic part of the water column of Lake Tanganyika. We measured CH4, 13C of dissolved CH4, dissolved oxygen (O2), sulphate (SO42-), sulphide (HS-) and the transient tracers chlorofluorocarbon-12 (CFC-12) and tritium (3H). A basic one-dimensional model, which considers vertical transport and biogeochemical fluxes and transformations, was used to interpret the vertical distribution of these substances. The results suggest that the anaerobic oxidation of CH4 is an important mechanism limiting CH4 to the anoxic zone of Lake Tanganyika. The important role of the anaerobic oxidation for CH4 concentrations is further supported by high abundances (up to ˜33% of total DAPI-stained cells) of single living archaea, identified by fluorescence in situ hybridization.

  10. Paleolimnological investigations of anthropogenic environmental change in Lake Tanganyika: I. An introduction to the project

    USGS Publications Warehouse

    Cohen, A.S.; Palacios-Fest, M. R.; McGill, J.; Swarzenski, P.W.; Verschuren, D.; Sinyinza, R.; Songori, T.; Kakagozo, B.; Syampila, M.; O'Reilly, C. M.; Alin, S.R.

    2005-01-01

    We investigated paleolimnological records from a series of river deltas around the northeastern rim of Lake Tanganyika, East Africa (Tanzania and Burundi) in order to understand the history of anthropogenic activity in the lake's catchment over the last several centuries, and to determine the impact of these activities on the biodiversity of littoral and sublittoral lake communities. Sediment pollution caused by increased rates of soil erosion in deforested watersheds has caused significant changes in aquatic communities along much of the lake's shoreline. We analyzed the effects of sediment discharge on biodiversity around six deltas or delta complexes on the east coast of Lake Tanganyika: the Lubulungu River delta, Kabesi River delta, Nyasanga/Kahama River deltas, and Mwamgongo River delta in Tanzania; and the Nyamuseni River delta and Karonge/Kirasa River deltas in Burundi. Collectively, these deltas and their associated rivers were chosen to represent a spectrum of drainage-basin sizes and disturbance levels. By comparing deltas that are similar in watershed attributes (other than disturbance levels), our goal was to explore a series of historical "experiments" at the watershed scale, with which we could more clearly evaluate hypotheses of land use or other effects on nearshore ecosystems. Here we discuss these deltas, their geologic and physiographic characteristics, and the field procedures used for coring and sampling the deltas, and various indicators of anthropogenic impact. ?? Springer 2005.

  11. Recent paleorecords document rising mercury contamination in Lake Tanganyika

    USGS Publications Warehouse

    Conaway, C.H.; Swarzenski, P.W.; Cohen, A.S.

    2012-01-01

    Recent Lake Tanganyika Hg deposition records were derived using 14C and excess 210Pb geochronometers in sediment cores collected from two contrasting depositional environments: the Kalya Platform, located mid-lake and more removed from watershed impacts, and the Nyasanga/Kahama River delta region, located close to the lake's shoreline north of Kigoma. At the Kalya Platform area, pre-industrial Hg concentrations are 23??0.2ng/g, increasing to 74ng/g in modern surface sediment, and the Hg accumulation rate has increased from 1.0 to 7.2??g/m 2/a from pre-industrial to present, which overall represents a 6-fold increase in Hg concentration and accumulation. At the Nyasanga/Kahama delta region, pre-industrial Hg concentrations are 20??3ng/g, increasing to 46ng/g in surface sediment. Mercury accumulation rate has increased from 30 to 70??g/m 2/a at this site, representing a 2-3-fold increase in Hg concentration and accumulation. There is a lack of correlation between charcoal abundance and Hg accumulation rate in the sediment cores, demonstrating that local biomass burning has little relationship with the observed Hg concentration or Hg accumulation rates. Examined using a sediment focusing-corrected mass accumulation rate approach, the cores have similar anthropogenic atmospheric Hg deposition profiles, suggesting that after accounting for background sediment concentrations the source of accumulating Hg is predominantly atmospheric in origin. In summary, the data document an increase of Hg flux to the Lake Tanganyika ecosystem that is consistent with increasing watershed sediment delivery with background-level Hg contamination, and regional as well as global increases in atmospheric Hg deposition. ?? 2011.

  12. Sediment infill within rift basins: Facies distribution and effects of deformation: Examples from the Kenya and Tanganyika Rifts, East Africa

    SciTech Connect

    Tiercelin, J.J.; Lezzar, K.E. ); Richert, J.P. )

    1994-07-01

    Oil is known from lacustrine basins of the east African rift. The geology of such basins is complex and different depending on location in the eastern and western branches. The western branch has little volcanism, leading to long-lived basins, such as Lake Tanganyika, whereas a large quantity of volcanics results in the eastern branch characterized by ephemeral basins, as the Baringo-Bogoria basin in Kenya. The Baringo-Bogoria basin is a north-south half graben formed in the middle Pleistocene and presently occupied by the hypersaline Lake Bogoria and the freshwater Lake Baringo. Lake Bogoria is fed by hot springs and ephemeral streams controlled by grid faults bounding the basin to the west. The sedimentary fill is formed by cycles of organic oozes having a good petroleum potential and evaporites. On the other hand, and as a consequence of the grid faults, Lake Baringo is fed by permanent streams bringing into the basin large quantities of terrigenous sediments. Lake Tanganyika is a meromictic lake 1470 m deep and 700 km long, of middle Miocene age. It is subdivided into seven asymmetric half grabens separated by transverse ridges. The sedimentary fill is thick and formed by organic oozes having a very good petroleum potential. In contrast to Bogoria, the lateral distribution of organic matter is characterized by considerable heterogeneity due to the existence of structural blocks or to redepositional processes.

  13. Trace metal enrichments in Lake Tanganyika sediments: Controls on trace metal burial in lacustrine systems

    NASA Astrophysics Data System (ADS)

    Poulson Brucker, Rebecca; McManus, James; Severmann, Silke; Owens, Jeremy; Lyons, Timothy W.

    2011-01-01

    We investigate the distributions of several key diagenetic reactants (C, S, Fe) and redox-sensitive trace metals (Mo, Cd, Re, U) in sediments from Lake Tanganyika, East Africa. This study includes modern sediments from a chemocline transect, which spans oxygenated shallow waters to sulfidic conditions at depth, as well as ancient sediments from a longer core (˜2 m) taken at ˜900 m water depth. Modern sediments from depths spanning ˜70-335 m are generally characterized by increasing enrichments of C, S, Mo, Cd, and U with increasing water depth but static Fe distributions. It appears that the sedimentary enrichments of these elements are, to varying degrees, influenced by a combination of organic carbon cycling and sulfur cycling. These modern lake characteristics contrast with a period of high total organic carbon (C org), total sulfur (S Tot), and trace metal concentrations observed in the 900 m core, a period which follows the most recent deglaciation (˜18-11 ky). This interval is followed abruptly by an interval (˜11-6 ky) that is characterized by lower C, S, U, and Mo. Consistent with other work we suspect that the low concentrations of S, Mo, and U may indicate a period of intense lake mixing, during which time the lake may have been less productive and less reducing as compared to the present. An alternative, but not mutually exclusive, hypothesis is that changes in the lake's chemical inventory, driven by significant hydrological changes, could be influencing the distribution of sedimentary trace elements through time.

  14. A 60,000-yr record of climate in Southeast Tropical Africa: Preliminary results from Lake Tanganyika

    NASA Astrophysics Data System (ADS)

    Tierney, J.; Russell, J.

    2006-12-01

    Few paleoclimate records exist that record high-frequency climate variability within tropical Africa, particularly during Marine Isotope Stage 3 (30-60,000 years BP). Thus very little is known about the potential role or response the region may have with regards to high-latitude abrupt climate change. However, climate variability in tropical East Africa is linked to large-scale changes in the convective intensity and location of the inter- tropical convergence zone (ITCZ) and the strength of the seasonal monsoonal winds from both the Atlantic and Indian Oceans. Understanding tropical African climate history may illuminate the causes and amplifying mechanisms of global climate change. We present here a multiproxy record of 60,000 years of climate variability from the sediments of Lake Tanganyika, southeast tropical Africa, which addresses outstanding questions regarding the role of East Africa in the context of abrupt climate change. Continuously accumulating hemipelagic sediments recovered from 650 m water depth from the southern half of Lake Tanganyika record hydrologic variability, terrestrial paleoenvironments, and changes in wind-driven upwelling intensity. Major element variations in Tanganyika sediments measured at 1 mm resolution by scanning XRF resolve changes in sediment geochemistry over decadal to centennial timescales, shedding light on the amplitude and frequency of short-term climate variability in this region. Additionally, records of bulk stable isotopes (?13C, ?15N), compound- specific ?D, and biogenic silica indicate rapid, dramatic changes in lake productivity, vegetation, and rainfall over millennial time-scales from Marine Isotope Stage 3 to present, including the Younger Dryas. In the case of the latter, the Younger Dryas is manifest in Lake Tanganyika as a sedimentary sequence of low diatom content, indicating reductions in southerly monsoonal windspeed and lake upwelling, and hydrogen isotope data over this interval indicate significant changes in moisture balance. These data suggest that the ITCZ occupied a more southerly position over Africa during the Younger Dryas, an interpretation consistent with previous studies conducted in this region. Older millennial-scale events exhibit similar lithological and geochemical changes, suggesting analogous shifts in the ITCZ over tropical Africa during Marine Isotope Stage 3.

  15. Century-Long Warming Trends in the Upper Water Column of Lake Tanganyika

    PubMed Central

    Kraemer, Benjamin M.; Hook, Simon; Huttula, Timo; Kotilainen, Pekka; O’Reilly, Catherine M.; Peltonen, Anu; Plisnier, Pierre-Denis; Sarvala, Jouko; Tamatamah, Rashid; Vadeboncoeur, Yvonne; Wehrli, Bernhard; McIntyre, Peter B.

    2015-01-01

    Lake Tanganyika, the deepest and most voluminous lake in Africa, has warmed over the last century in response to climate change. Separate analyses of surface warming rates estimated from in situ instruments, satellites, and a paleolimnological temperature proxy (TEX86) disagree, leaving uncertainty about the thermal sensitivity of Lake Tanganyika to climate change. Here, we use a comprehensive database of in situ temperature data from the top 100 meters of the water column that span the lake’s seasonal range and lateral extent to demonstrate that long-term temperature trends in Lake Tanganyika depend strongly on depth, season, and latitude. The observed spatiotemporal variation in surface warming rates accounts for small differences between warming rate estimates from in situ instruments and satellite data. However, after accounting for spatiotemporal variation in temperature and warming rates, the TEX86 paleolimnological proxy yields lower surface temperatures (1.46 °C lower on average) and faster warming rates (by a factor of three) than in situ measurements. Based on the ecology of Thaumarchaeota (the microbes whose biomolecules are involved with generating the TEX86 proxy), we offer a reinterpretation of the TEX86 data from Lake Tanganyika as the temperature of the low-oxygen zone, rather than of the lake surface temperature as has been suggested previously. Our analyses provide a thorough accounting of spatiotemporal variation in warming rates, offering strong evidence that thermal and ecological shifts observed in this massive tropical lake over the last century are robust and in step with global climate change. PMID:26147964

  16. Mapping landslide processes in the North Tanganyika - Lake Kivu rift zones: towards a regional hazard assessment

    NASA Astrophysics Data System (ADS)

    Dewitte, Olivier; Monsieurs, Elise; Jacobs, Liesbet; Basimike, Joseph; Delvaux, Damien; Draida, Salah; Hamenyimana, Jean-Baptiste; Havenith, Hans-Balder; Kubwimana, Désiré; Maki Mateso, Jean-Claude; Michellier, Caroline; Nahimana, Louis; Ndayisenga, Aloys; Ngenzebuhoro, Pierre-Claver; Nkurunziza, Pascal; Nshokano, Jean-Robert; Sindayihebura, Bernard; Philippe, Trefois; Turimumahoro, Denis; Kervyn, François

    2015-04-01

    The mountainous environments of the North Tanganyika - Lake Kivu rift zones are part of the West branch of the East African Rift. In this area, natural triggering and environmental factors such as heavy rainfalls, earthquake occurrences and steep topographies favour the concentration of mass movement processes. In addition anthropogenic factors such as rapid land use changes and urban expansion increase the sensibility to slope instability. Until very recently few landslide data was available for the area. Now, through the initiation of several research projects and the setting-up of a methodology for data collection adapted to this data-poor environment, it becomes possible to draw a first regional picture of the landslide hazard. Landslides include a wide range of ground movements such as rock falls, deep failure of slopes and shallow debris flows. Landslides are possibly the most important geohazard in the region in terms of recurring impact on the populations, causing fatalities every year. Many landslides are observed each year in the whole region, and their occurrence is clearly linked to complex topographic, lithological and vegetation signatures coupled with heavy rainfall events, which is the main triggering factor. Here we present the current knowledge of the various slope processes present in these equatorial environments. A particular attention is given to urban areas such as Bukavu and Bujumbura where landslide threat is particularly acute. Results and research perspectives on landslide inventorying, monitoring, and susceptibility and hazard assessment are presented.

  17. Discovery of sublacustrine hydrothermal activity and associated massive sulfides and hydrocarbons in the north Tanganyika trough, East African Rift

    SciTech Connect

    Tiercelin, J.J.; Mondeguer, A. ); Thouin, C. ); Kalala, T. )

    1989-11-01

    Massive sulfides and carbonate mineral deposits associated with sublacustrine thermal springs were recently discovered along the Zaire side of the north Tanganyika trough, western branch of the East African Rift. This hydrothermal activity, investigated by scuba diving at a maximum depth of 20 m, is located at the intersection of major north-south normal faults and northwest-southeast faults belonging to the Tanganyika-Rukwa-Malawi (TRM) strike-slip fault zone. The preliminary results presented here come from analyses of sulfide deposits, hydrothermal fluids, and associated hydrocarbons that result from geothermal activity in this part of the East African Rift filled by a thick pile of sediment, the north Tanganyika trough.

  18. Hidden biodiversity in an ancient lake: phylogenetic congruence between Lake Tanganyika tropheine cichlids and their monogenean flatworm parasites

    PubMed Central

    Vanhove, Maarten P. M.; Pariselle, Antoine; Van Steenberge, Maarten; Raeymaekers, Joost A. M.; Hablützel, Pascal I.; Gillardin, Céline; Hellemans, Bart; Breman, Floris C.; Koblmüller, Stephan; Sturmbauer, Christian; Snoeks, Jos; Volckaert, Filip A. M.; Huyse, Tine

    2015-01-01

    The stunning diversity of cichlid fishes has greatly enhanced our understanding of speciation and radiation. Little is known about the evolution of cichlid parasites. Parasites are abundant components of biodiversity, whose diversity typically exceeds that of their hosts. In the first comprehensive phylogenetic parasitological analysis of a vertebrate radiation, we study monogenean parasites infecting tropheine cichlids from Lake Tanganyika. Monogeneans are flatworms usually infecting the body surface and gills of fishes. In contrast to many other parasites, they depend only on a single host species to complete their lifecycle. Our spatially comprehensive combined nuclear-mitochondrial DNA dataset of the parasites covering almost all tropheine host species (N?=?18), reveals species-rich parasite assemblages and shows consistent host-specificity. Statistical comparisons of host and parasite phylogenies based on distance and topology-based tests demonstrate significant congruence and suggest that host-switching is rare. Molecular rate evaluation indicates that species of Cichlidogyrus probably diverged synchronically with the initial radiation of the tropheines. They further diversified through within-host speciation into an overlooked species radiation. The unique life history and specialisation of certain parasite groups has profound evolutionary consequences. Hence, evolutionary parasitology adds a new dimension to the study of biodiversity hotspots like Lake Tanganyika. PMID:26335652

  19. Hidden biodiversity in an ancient lake: phylogenetic congruence between Lake Tanganyika tropheine cichlids and their monogenean flatworm parasites.

    PubMed

    Vanhove, Maarten P M; Pariselle, Antoine; Van Steenberge, Maarten; Raeymaekers, Joost A M; Hablützel, Pascal I; Gillardin, Céline; Hellemans, Bart; Breman, Floris C; Koblmüller, Stephan; Sturmbauer, Christian; Snoeks, Jos; Volckaert, Filip A M; Huyse, Tine

    2015-01-01

    The stunning diversity of cichlid fishes has greatly enhanced our understanding of speciation and radiation. Little is known about the evolution of cichlid parasites. Parasites are abundant components of biodiversity, whose diversity typically exceeds that of their hosts. In the first comprehensive phylogenetic parasitological analysis of a vertebrate radiation, we study monogenean parasites infecting tropheine cichlids from Lake Tanganyika. Monogeneans are flatworms usually infecting the body surface and gills of fishes. In contrast to many other parasites, they depend only on a single host species to complete their lifecycle. Our spatially comprehensive combined nuclear-mitochondrial DNA dataset of the parasites covering almost all tropheine host species (N?=?18), reveals species-rich parasite assemblages and shows consistent host-specificity. Statistical comparisons of host and parasite phylogenies based on distance and topology-based tests demonstrate significant congruence and suggest that host-switching is rare. Molecular rate evaluation indicates that species of Cichlidogyrus probably diverged synchronically with the initial radiation of the tropheines. They further diversified through within-host speciation into an overlooked species radiation. The unique life history and specialisation of certain parasite groups has profound evolutionary consequences. Hence, evolutionary parasitology adds a new dimension to the study of biodiversity hotspots like Lake Tanganyika. PMID:26335652

  20. Monogamy in the maternally mouthbrooding Lake Tanganyika cichlid fish Tropheus moorii

    PubMed Central

    Egger, Bernd; Obermüller, Beate; Phiri, Harris; Sturmbauer, Christian; Sefc, Kristina M

    2006-01-01

    Supported by evidence for assortative mating and polygynandry, sexual selection through mate choice was suggested as the main force driving the evolution of colour diversity of haplochromine cichlids in Lakes Malawi and Victoria. The phylogenetically closely related tribe Tropheini of Lake Tanganyika includes the genus Tropheus, which comprises over 100 colour variants currently classified into six morphologically similar, polyphyletic species. To assess the potential for sexual selection in this sexually monochromatic maternal mouthbrooder, we used microsatellite-based paternity inference to investigate the mating system of Tropheus moorii. In contrast to haplochromines in Lake Malawi, multiple paternity is rare or even absent in broods of T. moorii. Eighteen of the 19 analysed families were consistent with genetic monogamy, while either a mutation or more than one sire explained the genotype of one offspring in another brood. We discuss the differences in breeding behaviour between T. moorii and the Lake Malawi haplochromines, and evaluate additional factors or alternatives to sexual selection as promoters of colour diversification. A preliminary survey of other Tropheini species suggested that multiple paternity is infrequent in the entire tribe. PMID:16790413

  1. Textural and compositional variability across littoral segments of Lake Tanganyika: The effect of asymmetric basin structure on sedimentation in large rift lakes

    SciTech Connect

    Soreghan, M.J.; Cohen, A.S.

    1996-03-01

    Lake Tanganyika, part of the East African rift system, represents one of the most widely cited modern analogs for interpreting ancient rift lakes. To date, few published detailed sedimentologic studies of the modern sediments allow for comparisons to outcrop- and well-bore-scale observations within ancient strata. Four recurrent structural margin types exist along the alternating half-graben structure of the lake: hinged margins, axial margins, accommodation zone margins, and escarpment margins. The hinged margin consists of a series of structurally controlled benches over which long, continuous tracts of bioclastic lag deposits predominate; clastic sands are limited to moderate-size silty deltas and long, narrow shoreface sands. The axial margin is dominated by a wave-dominated, silt-rich delta system. Accommodation zone margins consist of bioclastic lag deposits atop structural highs, whereas carbonate and clastic mud accumulates farther offshore. Escarpment margins contain small fan-delta deposits alternating along shore with talus deposits; offshore carbonate and clastic mud is present away from active gravity-flow deposition. Total organic carbon (TOC) and pyrolysis data from fine-grained samples subtly reflect the contrasts in margin types, but these values are controlled more directly by water depth. Although facies are similar among all margin types, their spatial distribution, in particular the degree to which facies tracts trend parallel to shore, best discriminates among the different margin types. These data suggest that unique but predictable associations of reservoir, seal, and source facies exist along each of the different margin types.

  2. Insights into the evolution of freshwater sponges (Porifera: Demospongiae: Spongillina): Barcoding and phylogenetic data from Lake Tanganyika endemics indicate multiple invasions and unsettle existing taxonomy.

    PubMed

    Erpenbeck, Dirk; Weier, Tina; de Voogd, Nicole J; Wörheide, Gert; Sutcliffe, Patricia; Todd, Jonathan A; Michel, Ellinor

    2011-10-01

    Sponges are a conspicuous element in many benthic habitats including in Africa's oldest, deepest lake, Lake Tanganyika. Despite their prevalence and pivotal ecological role as filter feeders, knowledge of the evolutionary history of sponges is in its infancy. Here, we provide the first molecular analysis targeting the evolution of sponges from Lake Tanganyika. Independent markers indicate the occurrence of several colonisation events which have shaped the current Tanganyikan lacustrine sponge biodiversity. This is in contrast to a range of previously studied organisms that have diversified within the lake from single lineages. Our tree reconstructions indicate the presence of two genera, Oncosclera and Eunapius, which are globally distributed. Therefore, we reject the hypothesis of monophyly for the sponges from Lake Tanganyika and challenge existing higher taxonomic structure for freshwater sponges. PMID:21669294

  3. Ancyrocephalidae (Monogenea) of Lake Tanganyika: III: Cichlidogyrus infecting the world's biggest cichlid and the non-endemic tribes Haplochromini, Oreochromini and Tylochromini (Teleostei, Cichlidae).

    PubMed

    Muterezi Bukinga, Fidel; Vanhove, Maarten P M; Van Steenberge, Maarten; Pariselle, Antoine

    2012-11-01

    Lake Tanganyika is the deepest and oldest African Great Lake and of economic importance. While the diversity of its endemic cichlid radiations yielded scientific interest, a number of cichlid tribes have few representatives in the lake. Some of those, namely Oreochromini (ex-Tilapiini), Haplochromini and Tylochromini, reach higher species numbers in riverine systems. Conversely, the phylogenetic position of the monospecific and endemic Boulengerochromini is unclear. The oreochromines Oreochromis tanganicae and Oreochromis niloticus, the haplochromine Astatotilapia burtoni, the tylochromine Tylochromis polylepis and the boulengerochromine Boulengerochromis microlepis, the largest cichlid species worldwide, were surveyed for ancyrocephalid monogenean gill parasites. Five new species are proposed. Cichlidogyrus gillardinae sp. n. is described from A. burtoni, Cichlidogyrus mbirizei sp. n. from O. tanganicae and Cichlidogyrus nshomboi sp. n. from B. microlepis. T. polylepis harbours Cichlidogyrus mulimbwai sp. n., Cichlidogyrus muzumanii sp. n. and a third, presently undescribed species. Four species known from outside the Tanganyika Basin were retrieved on the oreochromines. The host species are scientific models or important in the sectors of fisheries or ornamental fish trade. Moreover, their phylogenetic positions render them well-suited to help elucidate the historic relationships between riverine and lacustrine African cichlids. In this framework, their Cichlidogyrus fauna is compared to congeners known from African rivers and to the few Tanganyika representatives described. While the parasites of Oreochromis, A. burtoni and T. polylepis are reminiscent of those infecting related hosts throughout Africa, B. microlepis hosts a Cichlidogyrus morphotype typical of Lake Tanganyika. This supports its placement within an endemic cichlid radiation. PMID:22983218

  4. A Revised Holocene History of Lake Kivu, East Africa

    NASA Astrophysics Data System (ADS)

    Votava, J. E.; Johnson, T. C.; Hecky, R. E.

    2013-12-01

    The great lakes of the East African Rift valley are a vast chain of lakes formed in a region of active tectonics. These large, deep lakes are relatively old and many (e.g. Tanganyika, Malawi, and Turkana) have greatly influenced our understanding of terrestrial, tropical East African paleoclimate. Lake Kivu (max depth, 485m) sits at the heart of these rift lakes, north of Lake Tanganyika between the Democratic Republic of the Congo and Rwanda (roughly 250 km west of Lake Victoria). At over 1,400 meters in elevation, this 2,060 km2 mesotrophic lake has a complex stratification regime imposed by hydrothermal springs and deep waters supersaturated at STP in CO2 and CH4 gasses. The active Virunga Volcanoes to the north of the lake supply heated, high-salinity waters below 280 meters water depth maintaining the modern crenogenic meromixis. Based on detailed studies of diatom assemblages and bulk sedimentology, previous workers have suggested this hydrothermal activity began roughly 5,000 years BP. Unfortunately, dating and stratigraphic correlations of these original cores from the 1970 Woods Hole Oceanographic Institution's expedition have been problematic. Here we offer an improved chronology and new carbonate analyses from cores recovered in 2012 and 2013. Our AMS radiocarbon ages come from six terrigeneous macrofossils spanning the last 9,100 years (cal BP). These ages suggest a rather high sedimentation rate on the order of 70cm/kyr, and hence, our 8 m-long core provides us with a high-resolution lake history for the past 10,000 years. Most notable over the past 5,000 years in the lake history is the repeated onset and cessation of carbonate deposition, punctuated by organic-rich intervals. Earlier studies of the Woods Hole cores placed the onset of carbonate deposition at ca. 11,000 years BP suggesting changes in lake hydrology (i.e. closed to open), while the abrupt cessation of carbonate was dated at ca. 5,000 years BP and attributed to the beginning of significant hydrothermal activity in the lake. However our new chronology places these events much younger with the first major onset of carbonate deposition occurring around 4,300 years BP and ceasing ca. 2,700 years BP. Indeed much of central and northern Africa began to dry out at this time, following the African Humid Period ca. 15,000 to 5,000 years BP. Arid conditions could certainly favor carbonate precipitation and hence our revised ages of deposition agree well with regional paleoclimate studies. This new age model opens up the carbonate record of Lake Kivu for reinterpretation. We are investigating the extent to which the carbonate signal is influenced by internal changes and hydrothermal activity or by climate.

  5. Out of Tanganyika: Genesis, explosive speciation, key-innovations and phylogeography of the haplochromine cichlid fishes

    PubMed Central

    Salzburger, Walter; Mack, Tanja; Verheyen, Erik; Meyer, Axel

    2005-01-01

    Background The adaptive radiations of cichlid fishes in East Africa are well known for their spectacular diversity and their astonishingly fast rates of speciation. About 80% of all 2,500 cichlid species in East Africa, and virtually all cichlid species from Lakes Victoria (~500 species) and Malawi (~1,000 species) are haplochromines. Here, we present the most extensive phylogenetic and phylogeographic analysis so far that includes about 100 species and is based on about 2,000 bp of the mitochondrial DNA. Results Our analyses revealed that all haplochromine lineages are ultimately derived from Lake Tanganyika endemics. We find that the three most ancestral lineages of the haplochromines sensu lato are relatively species poor, albeit widely distributed in Africa, whereas a fourth newly defined lineage – the 'modern haplochromines' – contains an unparalleled diversity that makes up more than 7% of the worlds' ~25,000 teleost species. The modern haplochromines' ancestor, most likely a riverine generalist, repeatedly gave rise to similar ecomorphs now found in several of the species flocks. Also, the Tanganyikan Tropheini are derived from that riverine ancestor suggesting that they successfully re-colonized Lake Tanganyika and speciated in parallel to an already established cichlid adaptive radiation. In contrast to most other known examples of adaptive radiations, these generalist ancestors were derived from highly diverse and specialized endemics from Lake Tanganyika. A reconstruction of life-history traits revealed that in an ancestral lineage leading to the modern haplochromines the characteristic egg-spots on anal fins of male individuals evolved. Conclusion We conclude that Lake Tanganyika is the geographic and genetic cradle of all haplochromine lineages. In the ancestors of the replicate adaptive radiations of the 'modern haplochromines', behavioral (maternal mouthbrooding), morphological (egg-spots) and sexually selected (color polymorphism) key-innovations arose. These might be – together with the ecological opportunity that the habitat diversity of the large lakes provides – responsible for their evolutionary success and their propensity for explosive speciation. PMID:15723698

  6. 7. View southwest, east facade of Lake Forest (original Forest ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. View southwest, east facade of Lake Forest (original Forest Cottage structure incorporated into renamed structure) - Lake Placid Club, Forest Wing, East side of Mirror Lake Drive, North of State Route 86 & Main, North Elba, Essex County, NY

  7. 5. View north, south and east facade of Lake Forest ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. View north, south and east facade of Lake Forest (original Forest Cottage structure incorporated into renamed structure) - Lake Placid Club, Forest Wing, East side of Mirror Lake Drive, North of State Route 86 & Main, North Elba, Essex County, NY

  8. Comparative support for the expensive tissue hypothesis: Big brains are correlated with smaller gut and greater parental investment in Lake Tanganyika cichlids

    PubMed Central

    Tsuboi, Masahito; Husby, Arild; Kotrschal, Alexander; Hayward, Alexander; Buechel, Séverine D; Zidar, Josefina; Løvlie, Hanne; Kolm, Niclas

    2015-01-01

    The brain is one of the most energetically expensive organs in the vertebrate body. Consequently, the energetic requirements of encephalization are suggested to impose considerable constraints on brain size evolution. Three main hypotheses concerning how energetic constraints might affect brain evolution predict covariation between brain investment and (1) investment into other costly tissues, (2) overall metabolic rate, and (3) reproductive investment. To date, these hypotheses have mainly been tested in homeothermic animals and the existing data are inconclusive. However, there are good reasons to believe that energetic limitations might play a role in large-scale patterns of brain size evolution also in ectothermic vertebrates. Here, we test these hypotheses in a group of ectothermic vertebrates, the Lake Tanganyika cichlid fishes. After controlling for the effect of shared ancestry and confounding ecological variables, we find a negative association between brain size and gut size. Furthermore, we find that the evolution of a larger brain is accompanied by increased reproductive investment into egg size and parental care. Our results indicate that the energetic costs of encephalization may be an important general factor involved in the evolution of brain size also in ectothermic vertebrates. PMID:25346264

  9. 200 MAIN STREET, SALT LAKE CITY, UT. VIEW LOOKING EAST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    200 MAIN STREET, SALT LAKE CITY, UT. VIEW LOOKING EAST OF "MAIN' STREET. REPHOTOGRAPH OF HISTORIC SHIPLER PHOTO # 18273, UTAH STATE HISTORICAL SOCIETY COLLECTION. - Salt Lake City Cemetery, 200 N Street, Salt Lake City, Salt Lake County, UT

  10. INTERSECTION OF 445 NORTH & 1040 EAST, SALT LAKE CITY, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERSECTION OF 445 NORTH & 1040 EAST, SALT LAKE CITY, UT. VIEW LOOKING SOUTH. REPHOTOGRAPH OF HISTORIC SHIPLER PHOTO # 18272, UTAH STATE HISTORICAL SOCIETY COLLECTION. - Salt Lake City Cemetery, 200 N Street, Salt Lake City, Salt Lake County, UT

  11. PLAT X41601 EAST (SALT LAKE CITY CEMETERY LOCATER), SALT LAKE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PLAT X-4-160-1 EAST (SALT LAKE CITY CEMETERY LOCATER), SALT LAKE CITY, UT. VIEW LOOKING SOUTH AT CEMETERY BETWEEN OLIVE STREET (1020 EAST) AND 1000 EAST STREET, REPHOTOGRAPH OF HISTORIC SHIPLER PHOTO # 12049, UTAH STATE HISTORICAL SOCIETY COLLECTION. - Salt Lake City Cemetery, 200 N Street, Salt Lake City, Salt Lake County, UT

  12. 13C/Palynological evidence of differential residence times of organic carbon prior to its sedimentation in East African Rift Lakes and peat bogs

    NASA Astrophysics Data System (ADS)

    Hillaire-Marcel, Claude; Aucour, Anne-Marie; Bonnefille, Raymonde; Riollet, Guy; Vincens, Annie; Williamson, David

    Most terrestrial plants producing large amounts of organic matter in the East African Rift follow the Calvin (C3) photosynthetic pathway. Their end products have ?13C values of ca. -27 ± 2‰ (vs. PDB). On the contrary, most Cyperaceae (notably Cyperus papyrus and C. latifolius) are characterized by higher 13C contents ° 13C = -10.5 ± 1‰ ) in relation to their Hatch and Slack (C4) photosynthetic cycle. In consequence, ?13C values in total organic matter (TOM) from peat bog or lake cores essentially responded to the proportion of detritus from C4-Cyperaceae. Immediate evidence of the development or disappearance of Cyperaceae around lake margins or in peat bogs can be found in pollen assemblages. Lag times between pollen signals and correlative ° 13C shifts in TOM from cores are therefore indicative of the residence time of organic matter prior to its sedimentation. Delayed sedimentation of TOM will result in 14C anomalies which depend on several parameters, most of them being site specific as shown by examples from a peat bog in Burundi and from southern Lake Tanganyika. An independent assessment of the chronology by high resolution paleomagnetic correlations indicates a ca. 1.5 ka apparent 14C age of TOM in Lake Tanganyika at the Pleistocene-Holocene transition.

  13. Lake level change and total water discharge in East Africa Rift Valley from satellite-based observations

    NASA Astrophysics Data System (ADS)

    Hassan, Ayman A.; Jin, Shuanggen

    2014-06-01

    The measurement of total basin water discharge is important for understanding the hydrological and climatologic issues related to the water and energy cycles. Climatic extreme events are normal climatic occurrences in Africa. For example, extensive droughts are regular features in the last few decades in parts of East Africa, which suffers from a lack of in situ observations as well as a lack of regional hydrological models. In this study, multi-disciplinary different types of space-borne observations and global hydrological models are used to study total water discharge in the Great Rift Valley of East Africa (i.e. Lakes Victoria, Tanganyika, and Malawi) from January 2003 to December 2012. The data include the following: (1) total water storage (TWS) variations from Gravity Recovery and Climate Experiment (GRACE), (2) the lake level variations from Satellite Alimetric data, (3) rainfall from Tropical Rainfall Measurement Mission (TRMM) products, (4) soil moisture from WaterGAP Global Hydrology Model (WGHM), and (5) water fluxes from Global Land Data Assimilation System (GLDAS). Results show that a significant decline in the average lake level is found for all of the three lakes between 2003 and 2006. GRACE TWS variations of the whole basin area show the same pattern of variation as the average lake level variations estimated from Altimetric data. The TWS in the basin area of Lakes Victoria and Malawi is governed by the surface water stored in each lake itself, while for Lake Tanganyika, it is governed by both surface water and the soil moisture content in the basin area. Furthermore, the effect of rainfall on TWS is also studied. A phase lag of ~ 2 months is found between TRMM rainfall and GRACE TWS (generally, rainfall precedes the GRACE TWS) for the three lakes. In addition, the regional evapotranspiration ET is estimated from the water balance equation using GRACE land-water solutions, rainfall data from TRMM and runoff values obtained as a fraction of rainfall. It is found that the computed ET represents approximately 90% of the rainfall over the study region.

  14. Holocene Full-Vector Secular Variation from African Lakes

    NASA Astrophysics Data System (ADS)

    Lund, S.; Platzman, E. S.; Johnson, T. C.; Scholz, C. A.; Cohen, A. S.; Russell, J. M.

    2014-12-01

    We are developing a regional pattern of Holocene paleomagnetic secular variation (PSV) from four lakes in East Africa - Lake Turkana (3°N), Lake Victoria (1°S), Lake Tanganyika (5°S), and Lake Malawi (10°S). Detailed paleomagnetic and rock magnetic measurements have been made on two cores from Lake Malawi (9m meters in depth, last ~10,000 years), two cores from Lake Victoria (8 m, last ~8,000 years), 11 cores from Lake Turkana (2-9 m, last ~10,000 years), and one core from Lake Tanganyika (5 m, last ~5,000 years). Our rock magnetic studies identify significant intervals of magnetic mineral dissolution in Lakes Victoria and Tanganyika making parts of these cores unsuitable for relative paleointensity studies. On the other hand, rock magnetic variability in the Lake Malawi and Lake Turkana cores are stable and correlatable among cores. We have recovered directional secular variation records from Lakes Malawi, Victoria, and Turkana. Millennial-scale inclination and declination features can be correlated among cores at each lake and between lakes. We have also recovered relative paleointensity records from Lakes Malawi and Turkana. More than 20 radiocarbon dates and detailed seismic stratigraphy (Turkana) provide critical added information for correlating and dating the paleomagnetic records.

  15. 1. View west from east rock of the Lake Whitney ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. View west from east rock of the Lake Whitney Dam. Spillway is at right center. Abutment or training wall is at the photo's center. Shed at left center covers turbine installed in 1932. - Lake Whitney Water Filtration Plant, Lake Whitney Dam, East side of Whitney Avenue near intersection with Armory Street, Hamden, New Haven County, CT

  16. SEXTON'S HOUSE. 200 NORTH N STREET (895 EAST), SALT LAKE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SEXTON'S HOUSE. 200 NORTH N STREET (895 EAST), SALT LAKE CITY, UT. VIEW OF THE NORTHEAST. REPHOTOGRAPH OF HISTORIC SHIPLER PHOTO # 18996, UTAH STATE HISTORICAL SOCIETY COLLECTION. - Salt Lake City Cemetery, 200 N Street, Salt Lake City, Salt Lake County, UT

  17. Infestation and Pathological Alterations by Ergasilus sarsi (Copepoda) on the Tanganyika Killifish from Africa

    PubMed Central

    Kilian, Esmari; Avenant-Oldewage, Annemariè

    2013-01-01

    A total of 204 Ergasilus sarsi, a copepod, were collected from Tanganyika Killifish Lamprichthys tanganicanus in Lake Tanganyika during March 2010. The prevalence was 86.40%, the mean intensity was 7.56, and the mean abundance was 6.38. Only 27 of the fish were infested, and the highest infestation on one fish was 29. Proliferation of mucus cells and lamellar fusion occurred. Haemorrhage due to blood vessel compression was noted. This is the first record of E. sarsi from Tanganyika Killifish. This study is also the first to provide a description of the pathological alterations caused by E. sarsi. PMID:24341764

  18. Radiocarbon dating of East african lake levels.

    PubMed

    Butzer, K W; Isaac, G L; Richardson, J L; Washbourn-Kamau, C

    1972-03-10

    The fluctuations of the key East African lakes discussed are summarized in Fig. 4 which also includes the available evidence from Lake Rukwa (42) and Lake Chad (43) Exceot for Lake Victoria, all of these now lack surface outlets and are situated in much drier climates than the major lakes of the Western Rift Valley, which remain filled to their overflow levels. The apparent differendes among the fluctuations of the lakes are partly due to differendes in the nature of the evidence or the intensity of research or both, although there must also have been important local differences in the histories of the lakes Yet the consistencies are far more striking, most notably the coincidence of early Holocene high stands. Between 10,000 and 8,000 years ago, it seems that lakes in many parts of tropical Africa were greatly enlarged. Where evidence for the previous span of time is well resolved, it appears that transgressions leading to this high stand began about 12,000 years ago, and evidende from three basins (Victoria, Nakuru, and Chad) indicates a pause or minor recession just at or before 10,000 years ago. Wherever information is available for the period preceding 12,000 years ago, it can consistentlybe shown that lakes were much small-er . Several basins (Rudolf, Nakuru, and Chad) also show traces of much earlier phases of lake expansion. which are not yet well dated but which all occurred more then 20,000 years ago. The Holocene record subsequent to the maximum of 10,00 to 8,000 years ago is more complex. Three basins (Rudolf, Nakuru, and Chad) show an apparently concordant, positive oscillation at some point between 6000 and 4000 years ago, but it is uncertain how widely this episode is represented. Although many of these lakes that are now closed filled to overflowing at least once during the late Quaternary, it is evident from Fig. 4 that the periods of expansion were short-lived compared with phases of contraction to levels near those of today. This pattern may be in accord with fragmentary evidence from lower and middle Pleistocene formations, such as those of Olduvai(44)and Paninj (45), within which some relatively short-term lake expansions can be documented, but which lack evidence for any marked long-term departure from a balance of evaporation and precipitation similar to the present one Further, this pattern of brief moist pulsations, with a duration of perhaps 2000 to 5000 years, is also suggested by other late Pleistocene and Holocene sequences (based primarily on geomorphological and palynological evidence) from the Saharan area, Angola, and South Africa (46). In default of radiometric dating, such complex successions of relatively brief moist intervals provide few stratigraphic markers of broad applicability. This, together with the fact that vegetation, weathering processes, montane glaciers, lake size, lake salinity, and so forth are all likely to reflect the diverse aspects of Climatic change differently, underscores the strictures of Cooke (2) and Flint (3) against the use of pluvials and intrlvasas a basis for subdividing Quaternary time in Africa. Positive correlations between high-latitude glacial advances or maxima and intervals of high lake levels have been demonstrated or suggested for many areas of mid-latitude North America and Eurasia (47), and similar patterns have often been regarded as probable for tropical Africa as well. However, the evidence summarized above shows a notable lack of such correlations for the tropical lakes considered here. If glaciation and tropical lake levels were connected at all, then a far more complex-delayed, multiplefactor, or inverse-relationship must be sought for the late Quaternary (48). This renders the introduction of new climato-stratigraphic terms such as hypothermal and interstadial (49) of questionable value in East Africa. Further, whereas the so-called pluvial lakes of higher latitudes were probably due primarily to reduced evaporation (50), our computations for the early Holocene lakes Nakuru and Naivasha, as well as for the oscillations of Lake Rudolf and

  19. 68. View of north arm of Lake Tapps, looking east ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    68. View of north arm of Lake Tapps, looking east toward power line that crosses Hille Lake; the shore is composed of a dike built by the Pacific Coast Power Company as part of the Lake Tapps reservoir construction. Photo by Brian C. Morris, Puget Power, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

  20. 15. View east of original machine shop area. Lake ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. View east of original machine shop area. - Lake Whitney Water Filtration Plant, Armory Street Pumphouse, North side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

  1. Sensitivity of the East African rift lakes to climate variability

    NASA Astrophysics Data System (ADS)

    Olaka, L.; Trauth, M. H.

    2009-04-01

    Lakes in the East African Rift have provided excellent proxies to reconstruct past climate changes in the low latitudes. The lakes occupy volcano-tectonic depressions with highly variable climate and hydrological setting, that present a good opportunity to study the climatic and hydrogeological influences on the lake water budget. Previous studies have used lake floor sediments to establish the sensitivity of the East African rift lakes. This study focuses on geomorphology and climate to offer additional or alternative record of lake history that are key to quantifying sensitivity of these lakes as archives to external and internal climatic forcings. By using the published Holocene lake areas and levels, we analyze twelve lakes on the eastern arm of the East African rift; Ziway, Awassa, Turkana, Suguta, Baringo, Nakuru, Elmenteita, Naivasha, Natron, Manyara and compare with Lake Victoria, that occupies the plateau between the east and the western arms of the rift. Using the SRTM data, Hypsometric (area-altitude) analysis has been used to compare the lake basins between latitude 80 North and 30 South. The mean elevation for the lakes, is between 524 and 2262 meters above sea level, the lakes' hypsometric integrals (HI), a measure of landmass volume above the reference plane, vary from 0.31 to 0.76. The aridity index (Ai), defined as Precipitation/ Evapotranspiration, quantifies the water available to a lake, it encompasses land cover and climatic effects. It is lowest (arid) in the basin between the Ethiopian rift and the Kenyan rift and at the southern termination of the Kenyan Rift in the catchments of lake Turkana, Suguta, Baringo and Manyara with values of 0.55, 0.43, 0.43 and 0.5 respectively. And it is highest (wet) in the catchments of, Ziway, Awassa, Nakuru and Naivasha as 1.33,1.03 and 1.2 respectively, which occupy the highest points of the rift. Lake Victoria has an index of 1.42 the highest of these lakes and receives a high precipitation. We use a simple model written on a Matlab code to illustrate the lake volume and area response to climate of surficialy closed, graben shaped and panshaped lake basins. From preliminary results, lake basins that are sensitive to climate variability have a high HI and high aridity index, which will be presented in this conference

  2. STS-55 Earth observation of Lake Natron, Tanzania, East Africa

    NASA Technical Reports Server (NTRS)

    1993-01-01

    STS-55 Earth observation taken aboard Columbia, Orbiter Vehicle (OV) 102, shows Lake Natron in Tansania, in the 35-mile-wide East African Rift Valley. This lake is surrounded by sodium carbonate volcanoes. Through erosion, these salts of volcanic origin are transported into the rift valley lakes. The various shades of bright red reflecting from the lake result from the water chemistry and biotic blooms. The white spots in the lakebed are drying soda salts. The depth and circulation of the water in the southern end of the lake cause it to appear dark blue rather than bright red. In the repeated photographs of this lake from orbit, we have seen the extent and intensity of its colors fluctuate seasonally. In this photograph, the biotic activity appears to be at a peak. Such a large extent of red-colored water was not present in the photos taken from STS-56, just a few days before (04-10-93).

  3. 65. VIEW OF EAST LORING LAKE LOOKING NORTHWEST FROM DAM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    65. VIEW OF EAST LORING LAKE LOOKING NORTHWEST FROM DAM NEAR BUILDING 361 (MUNITIONS MAINTENANCE SQUADRON ADMINISTRATION BUILDING) IN BASE SPARES AREA. - Loring Air Force Base, Weapons Storage Area, Northeastern corner of base at northern end of Maine Road, Limestone, Aroostook County, ME

  4. Lacustrine mollusc radiations in the Lake Malawi Basin: experiments in a natural laboratory for evolution

    NASA Astrophysics Data System (ADS)

    Van Damme, D.; Gautier, A.

    2013-09-01

    In terminal Pliocene-early Pleistocene times, part of the Malawi Basin was occupied by paleo-lake Chiwondo. Molluscan biostratigraphy situates this freshwater lake either in the East African wet phase between 2.7-2.4 Ma or that of 2.0-1.8 Ma. In-lake divergent evolution remained restricted to a few molluscan taxa and was very modest. The lacustrine Chiwondo fauna went extinct at the beginning of the Pleistocene. The modern Lake Malawi malacofauna is depauperate and descends from ubiquistic southeast African taxa and some Malawi basin endemics that invaded the present lake after the Late Pleistocene mega-droughts. The Pleistocene aridity crises caused dramatic changes, affecting the malacofauna of all East African lakes. All lacustrine endemic faunas that had evolved in the Pliocene rift lakes, such as paleo-lake Chiwondo, became extinct. In Lake Tanganyika, the freshwater ecosystem did not crash as in other lakes, but the environmental changes were sufficiently important to trigger a vast radiation. All African endemic lacustrine molluscan clades that are the result of in-lake divergence are hence geologically young, including the vast Lavigeria clade in Lake Tanganyika (ca. 43 species).

  5. 330 NORTH & CENTER STREET (990 EAST) (8E1684E, SALT LAKE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    330 NORTH & CENTER STREET (990 EAST) (8-E-16-8-4E, SALT LAKE CITY CEMETERY LOCATER), SALT LAKE CITY, UT. VIEW LOOKING SOUTHWEST OVER THE CEMETERY. - Salt Lake City Cemetery, 200 N Street, Salt Lake City, Salt Lake County, UT

  6. Geophysical studies of Mono Lake, east-central California

    NASA Astrophysics Data System (ADS)

    Athens, N. D.; Ponce, D. A.

    2012-12-01

    Magnetic and gravity investigations were undertaken in Mono Lake, California to study regional crustal structures and to aid understanding the geologic framework of Mono Lake, in particular regarding potential geothermal resources and volcanic hazards throughout Mono Basin. Recent geophysical surveys included over 600 line-kilometers of high-resolution ship-borne magnetometer data that augmented existing airborne data, 22 line-kilometers of ground magnetic data that were collected along six traverses across Paoha Island, 56 gravity stations that were collected on Paoha and Negit Islands, and 28 rock samples that were collected for physical property data. Magnetic highs in the study area occur to the east and west of Mono Lake, where pre-Tertiary basement is exposed. Magnetic data indicate that Mono Lake itself is dominated by three prominent magnetic anomalies that are from west to east: a magnetic high along the northwest part of the lake associated with the moderately magnetic basalt cinder cone at Black Point, a magnetic high associated with the young volcanic centers at Paoha and Negit Islands, and a broad magnetic high along the eastern margin of the lake probably associated with moderately magnetic granitic basement rocks at depth. Because volcanic rocks exposed at the surface of Paoha and Negit Islands are only weakly magnetic, magnetic data suggest that more mafic volcanic rocks probably occur at depth and are the source of the anomaly. The linear and steep magnetic gradient across the eastern part of the lake may reflect a fault. A fault may also be imaged in the northeastern part of the lake, where a possible laterally offset magnetic anomaly may be present. Within Mono Lake, gravity station control is poor because land-based gravity stations are limited to Paoha and Negit Islands. The gravity low in the basin reflects a moderately deep sedimentary basin filled with low density lacustrine and volcanic deposits. Isostatic gravity data indicate the central part of Mono Lake corresponds approximately to a 30-mGal gravity low, yielding a basin depth of about 2.2 km, assuming a density contrast of 0.4 g/cm3 and using a semi-infinite slab approximation of the basin floor.

  7. Buried seed populations in the subarcticforest east of Great Slave Lake, Northwest Territories

    E-print Network

    Johnson, Edward A.

    Buried seed populations in the subarcticforest east of Great Slave Lake, Northwest Territories E. A~vrtn, Srrskatoon, Saskntchrrvan S7N OW0 Received June 18, 1975 JOHNSON,E. A. 1975. Buried seed populations in the subarctic forest east of Great Slave Lake, Northwest Territories. Can. J. Bot. 53: 2933-2941. Buried seeds

  8. 75 FR 34362 - Safety Zone; Festivals & Fireworks Celebration, East Moran Bay, Lake Huron, St. Ignace, MI

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-17

    ...encompass all waters of Lake Huron within a 600-foot...43'18.48'' W.: [DATUM: NAD 83]. All persons...Celebration, East Moran Bay, Lake Huron, St. Ignace...safety zone: All waters of Lake Huron within a 600-foot...43'18.48'' W.: [DATUM: NAD 83]. (b)...

  9. Ice cover, landscape setting, and geological framework of Lake Vostok, East Antarctica

    USGS Publications Warehouse

    Studinger, M.; Bell, R.E.; Karner, G.D.; Tikku, A.A.; Holt, J.W.; Morse, D.L.; David, L.; Richter, T.G.; Kempf, S.D.; Peters, M.E.; Blankenship, D.D.; Sweeney, R.E.; Rystrom, V.L.

    2003-01-01

    Lake Vostok, located beneath more than 4 km of ice in the middle of East Antarctica, is a unique subglacial habitat and may contain microorganisms with distinct adaptations to such an extreme environment. Melting and freezing at the base of the ice sheet, which slowly flows across the lake, controls the flux of water, biota and sediment particles through the lake. The influx of thermal energy, however, is limited to contributions from below. Thus the geological origin of Lake Vostok is a critical boundary condition for the subglacial ecosystem. We present the first comprehensive maps of ice surface, ice thickness and subglacial topography around Lake Vostok. The ice flow across the lake and the landscape setting are closely linked to the geological origin of Lake Vostok. Our data show that Lake Vostok is located along a major geological boundary. Magnetic and gravity data are distinct east and west of the lake, as is the roughness of the subglacial topography. The physiographic setting of the lake has important consequences for the ice flow and thus the melting and freezing pattern and the lake's circulation. Lake Vostok is a tectonically controlled subglacial lake. The tectonic processes provided the space for a unique habitat and recent minor tectonic activity could have the potential to introduce small, but significant amounts of thermal energy into the lake. ?? 2002 Elsevier Science B.V. All rights reserved.

  10. 33 CFR 165.T09-0452 - Safety Zone; Festivals & Fireworks Celebration, East Moran Bay, Lake Huron, St. Ignace, MI.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Celebration, East Moran Bay, Lake Huron, St. Ignace, MI...Celebration, East Moran Bay, Lake Huron, St. Ignace, MI...safety zone: All waters of Lake Huron within a 600-foot radius from...43?18.48? W.: [DATUM: NAD 83]. (b)...

  11. Large subglacial lakes in East Antarctica at the onset of fast-flowing ice streams.

    PubMed

    Bell, Robin E; Studinger, Michael; Shuman, Christopher A; Fahnestock, Mark A; Joughin, Ian

    2007-02-22

    Water plays a crucial role in ice-sheet stability and the onset of ice streams. Subglacial lake water moves between lakes and rapidly drains, causing catastrophic floods. The exact mechanisms by which subglacial lakes influence ice-sheet dynamics are unknown, however, and large subglacial lakes have not been closely associated with rapidly flowing ice streams. Here we use satellite imagery and ice-surface elevations to identify a region of subglacial lakes, similar in total area to Lake Vostok, at the onset region of the Recovery Glacier ice stream in East Antarctica and predicted by ice-sheet models. We define four lakes through extensive, flat, featureless regions of ice surface bounded by upstream troughs and downstream ridges. Using ice velocities determined using interferometric synthetic aperture radar (InSAR), we find the onset of rapid flow (moving at 20 to 30 m yr(-1)) of the tributaries to the Recovery Glacier ice stream in a 280-km-wide segment at the downslope margins of these four subglacial lakes. We conclude that the subglacial lakes initiate and maintain rapid ice flow through either active modification of the basal thermal regime of the ice sheet by lake accretion or through scouring bedrock channels in periodic drainage events. We suggest that the role of subglacial lakes needs to be considered in ice-sheet mass balance assessments. PMID:17314977

  12. Turbidite systems of lacustrine rift basins: Examples from the Lake Kivu and Lake Albert rifts, East Africa

    NASA Astrophysics Data System (ADS)

    Zhang, Xuewei; Scholz, Christopher A.

    2015-07-01

    The Holocene turbidite systems of Lake Kivu and the Pliocene turbidite systems of Lake Albert in the East African Rift were examined using high-resolution 2-D and 3-D seismic reflection data and sediment core information. Based on investigations of seismic facies and lithofacies, several key turbidity-flow depositional elements were observed, including channels, overbank levees with sediment waves, and depositional lobes. Analyses of the sources of the recent and ancient turbidite systems in these two extensional basins suggest that flood-induced hyperpycnal flows are important triggers of turbidity currents in lacustrine rift basins. From source to sink, sediment dispersal, facies distribution, and depositional thickness of the turbidite systems are strongly influenced by rift topography. The Lake Kivu and Lake Albert rifts serve as excellent analogues for understanding the sedimentary patterns of lacustrine turbidites in extensional basins.

  13. The Impact of the Geologic History and Paleoclimate on the Diversification of East African Cichlids

    PubMed Central

    Danley, Patrick D.; Husemann, Martin; Ding, Baoqing; DiPietro, Lyndsay M.; Beverly, Emily J.; Peppe, Daniel J.

    2012-01-01

    The cichlid fishes of the East African Great Lakes are the largest extant vertebrate radiation identified to date. These lakes and their surrounding waters support over 2,000 species of cichlid fish, many of which are descended from a single common ancestor within the past 10?Ma. The extraordinary East African cichlid diversity is intricately linked to the highly variable geologic and paleoclimatic history of this region. Greater than 10?Ma, the western arm of the East African rift system began to separate, thereby creating a series of rift basins that would come to contain several water bodies, including the extremely deep Lakes Tanganyika and Malawi. Uplifting associated with this rifting backponded many rivers and created the extremely large, but shallow Lake Victoria. Since their creation, the size, shape, and existence of these lakes have changed dramatically which has, in turn, significantly influenced the evolutionary history of the lakes' cichlids. This paper reviews the geologic history and paleoclimate of the East African Great Lakes and the impact of these forces on the region's endemic cichlid flocks. PMID:22888465

  14. Climatic change and evaporative processes in the development of Common Era hypersaline lakes, East Antarctica: A study of Lake Suribati

    NASA Astrophysics Data System (ADS)

    Nakashima, H.; Seto, K.; Katsuki, K.; Kaneko, H.; yamada, K.; Imura, S.; Dettman, D. L.

    2011-12-01

    The Antarctic continent was uplifted by glacioisostatic rebound due to the regression of ice sheets after the last glacial period. Today's saline lakes were formed in shallow basins originally below sea level. Antarctic hypersaline lakes are formed by concentration of isolated seawater bodies as affected by recent climate change. Many saline lakes are found in the ice-free area of the Soya coast, East Antarctica. Lake Suribati is located in Sukarvsnes on the Soya coast. It is a hypersaline lake with maximum salinity ~200 psu, and an observable stable halocline at 7~12m depth. This study uses Lake Suribati sediment core Sr4C-01, collected by the 46th Japanese Antarctica Research Expedition, to examine the relationship of climatic change to evaporative processes and solute concentration in Lake Suribati in the Common Era. Sr4C-01 core was collected at 9.53m water depth in Lake Suribati in 2005 (core length is 63cm). This core primarily consists of black mud and laminated black organic mud. In the interval from 10 to 24cm below the sediment surface evaporite crystals occur. The age of the Sr4C-01 core bottom is estimated to be ~3,500 cal yrs BP, based on AMS carbon-14 dating at 6 core horizons. The evaporite crystals were indentified as aragonite based on XRD. Total inorganic carbon (TIC) content is low, around 0.5%, throughout the Sr4C-01 core, with higher values, approximately 1~4%, in two intervals, 57~52cm and 29~10cm core depth. Variation in CaO content tracks TIC content. We suggest that synchronous change in CaO and TIC contents indicate the vertical change in the amount of aragonite. Two intervals of evaporite precipition imply two intervals of evaporation and concentration of lake water. Hypersaline lake conditions did not occur soon after the isolation from the sea, rather these occurred under repeated concentration and dilution of lake water. Dilution of saline lake water could occur through the inflow of melt water from local snow or ice, indicating a warm climate interval. During cool periods, local snow and ice sheet may have remained frozen. In this case, lake water volume would decrease by sublimation from the frozen lake surface, leading to salt concentration. Based on MgO and Na2O content data, we suggest that other Mg and Na evaporites occur in the core. If such evaporates can be identified, a detailed solute concentration process can be described. Analysis of evaporites in sediment core from Antarctic hypersaline lakes have great potential as proxy indicators for the study of climate change in Antarctica.

  15. Depositional environments of Late Triassic lake, east-central New Mexico

    SciTech Connect

    Hester, P.M. )

    1989-09-01

    The Redonda Member of the Chinle Formation represents deposition in a large, polymictic lake during the Late Triassic (Norian) in east-central New Mexico. This study documents and defines an extensive lacustrine system situated in western Pangaea which was influenced by both tectonic and climatic events. Areal extent of the lake may have been as much as 5,000 km{sup 2}.

  16. Viral metagenomics analysis of planktonic viruses in East Lake, Wuhan, China.

    PubMed

    Ge, Xingyi; Wu, Yongquan; Wang, Meiniang; Wang, Jun; Wu, Lijun; Yang, Xinglou; Zhang, Yuji; Shi, Zhengli

    2013-10-01

    East Lake (Lake Donghu), located in Wuhan, China, is a typical city freshwater lake that has been experiencing eutrophic conditions and algal blooming during recent years. Marine and fresh water are considered to contain a large number of viruses. However, little is known about their genetic diversity because of the limited techniques for culturing viruses. In this study, we conducted a viral metagenomic analysis using a high-throughput sequencing technique with samples collected from East Lake in Spring, Summer, Autumn, and Winter. The libraries from four samples each generated 234,669, 71,837, 12,820, and 34,236 contigs (> 90 bp each), respectively. The genetic structure of the viral community revealed a high genetic diversity covering 23 viral families, with the majority of contigs homologous to DNA viruses, including members of Myoviridae, Podoviridae, Siphoviridae, Phycodnaviridae, and Microviridae, which infect bacteria or algae, and members of Circoviridae, which infect invertebrates and vertebrates. The highest viral genetic diversity occurred in samples collected in August, then December and June, and the least diversity in March. Most contigs have low-sequence identities with known viruses. PCR detection targeting the conserved sequences of genes (g20, psbA, psbD, and DNApol) of cyanophages further confirmed that there are novel cyanophages in the East Lake. Our viral metagenomic data provide the first preliminary understanding of the virome in one freshwater lake in China and would be helpful for novel virus discovery and the control of algal blooming in the future. PMID:24132758

  17. 18O 16O ratios in cherts associated with the saline lake deposits of East Africa

    USGS Publications Warehouse

    O'Neil, J.R.; Hay, R.L.

    1973-01-01

    The cherts formed from sodium silicate precursors in East African saline, alkaline lakes have ??18O values ranging from 31.1 to 44.1. The ??18O values correlate in general with lake salinities as inferred from geologic evidence, indicating that most chert was formed from its precursor in contact with lake water trapped at the time of deposition. A few of the analyzed cherts probably formed in contact with dilute meteoric water. From the widely varying ??18O values we conclude that precursors were transformed to chert in fluids of widely varying salinity and aNa+/aH+ ratio. ?? 1973.

  18. Southern hemisphere tropical climate over the past 145ka: Results of the Lake Malawi Scientific Drilling Project, East Africa

    E-print Network

    Scientific Drilling Project, East Africa 1. Background to scientific drilling on Lake Malawi The suggestion by the limnogeology community. Lake drilling has now matured into an important means of recovering paleoclimate time the world. The Lake Malawi Scientific Drilling Project was one of the first proposed, and emerged from

  19. Occurrence and distribution of endocrine-disrupting compounds in the Honghu Lake and East Dongting Lake along the Central Yangtze River, China.

    PubMed

    Yang, Yuyi; Cao, Xinhua; Zhang, Miaomiao; Wang, Jun

    2015-11-01

    Lakes along the Yangzte River are very important for inhabitants due to their ecosystem service values. In this study, the level of eight endocrine-disrupting compounds (EDCs) was studied in the Honghu Lake and East Dongting Lake. In each lake, 21 water samples and 21 sediment samples were collected. The total concentrations of eight EDCs in surface water (47.60-419.82 ng L(-1), mean value: 225.65 ng L(-1)) and sediments (202.71-635.36 ng g(-1) dry weight (dw), mean value 371.90 ng g(-1) dw) of Honghu Lake were significantly higher than those in surface water (43.52-394.21 ng L(-1), mean value 153.03 ng L(-1)) and sediment (70.01-464.63 ng g(-1) dw, mean value 238.42 ng g(-1) dw) in East Dongting Lake. 4-Nonylphenol (NP), 4-octylphenol (OP), and bisphenol A (BPA) in surface water and sediments were main EDCs in two lakes. No correlation relationships were found between concentrations of EDCs in water and sediment from two lakes. The concentrations of OP and 17?-ethinylestradiol (EE2) in sediments of Honghu Lake had significant positive correlation with the content of total organic carbon (TOC). The concentrations of EDCs in outlet of Honghu Lake were comparable to those in the main lake, whereas the EDCs in outlet of East Dongting Lake were lower than those in the main lake. The EDCs in Honghu Lake and East Dongting Lake may have a significant potential biological effect on fish based on the estimation of EDC estrogenicity. PMID:26150298

  20. Additional results on palaeomagnetic stratigraphy of the Koobi Fora Formation, east of Lake Turkana (Lake Rudolf), Kenya

    USGS Publications Warehouse

    Hillhouse, J.W.; Ndombi, J.W.M.; Cox, A.; Brock, A.

    1977-01-01

    The magnetostratigraphy of the hominid-bearing sediments exposed east of Lake Turkana has been strengthened by new palaeomagnetic results. Ages obtained from several tuffs by the 40Ar/39Ar method suggest an approxmate match between the observed magnetozones and the geomagnetic polarity time scale; however, the palaeomagnetic results are also compatible with a younger chronology suggested by conventional K-Ar dating of the KBS Tuff. ?? 1977 Nature Publishing Group.

  1. STS-55 Earth observation of Lake Natron, Tanzania, East Africa

    NASA Technical Reports Server (NTRS)

    1993-01-01

    STS-55 Earth observation taken aboard Columbia, Orbiter Vehicle (OV) 102, shows Lake Natron. Taken with color infrared (CIR) film, the typical red-colored water appears greenish. The drying soda salts in the lakebed are seen in greater detail in this CIR view. From the signatures seen in this photograph, the lake appears to be highly saline and to contain aquatic biota with little or no chlorophyll. The biomass over the rift valley escarpment is clearly defined by the reddish color in this CIR photo. Refer to STS055-93-037 for a comparative view photographed in regular color.

  2. Active Lakes of the Recovery Ice Stream, East Antarctica: A Bedrock-Controlled Subglacial Hydrological System

    NASA Astrophysics Data System (ADS)

    Fricker, H. A.; Scambos, T. A.; Bell, R. E.; Carter, S. P.

    2014-12-01

    A connected system of active sub-glacial lakes was revealed beneath the Recovery Ice Stream, East Antarctica by ICESat laser altimetry acquired from 2003 to 2008. Here we combine repeat-track analysis of ICESat (2003-2009), Operation IceBridge laser altimetry and radio-echo sounding (RES; 2011 and 2012), and MODIS image differencing (2009-2011) to learn more about the surface and bedrock topographic setting of the lakes and the constraints on water flow through the system. IceBridge data reveal a ~1500 m deep, ~1000 km long bedrock trough under the main trunk of Recovery Ice Stream. We extend the lake activity time series to 2012 for the three lower lakes using IceBridge data: one lake underwent a large deflation between 2009 and 2011; another lake, which had been continuously filling between 2003 and 2010, started to drain after 2011. Hydrologic connections among the lakes appear to be direct and responsive. We reproduce the lake activity using a simple subglacial water model. The hydrologic system beneath Recovery Ice Stream is controlled by unusually pronounced bedrock topography (and not ice surface topography, as is the case for most Antarctic systems studied to date). We discuss potential causes of non-steady hydrologic behavior in major Antarctic catchments.

  3. Calibration and application of the branched GDGT temperature proxy on East African lake sediments

    NASA Astrophysics Data System (ADS)

    Loomis, Shannon E.; Russell, James M.; Ladd, Bethany; Street-Perrott, F. Alayne; Sinninghe Damsté, Jaap S.

    2012-12-01

    Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are a novel proxy for mean annual air temperature (MAAT) and have the potential to be broadly applicable to climate reconstruction using lacustrine sediments. Several calibrations have been put forth relating brGDGT distributions to MAAT using a variety of linear regressions, including the methylation (MBT) and cyclization (CBT) indices of brGDGTs, the relative abundances of the major, non-cyclized brGDGTs (MbrGDGTs), and best subsets regression (BSR) of the fractional abundances of the nine most common brGDGTs. However, these calibrations have rarely been applied to lake sediment cores to reconstruct temperatures and test the applicability of this proxy as a paleothermometer. We present an expanded East African lakes surface sediment brGDGT dataset based upon 111 lakes and examine three methods of calibrating brGDGTs to MAAT. These methods include recalculations of the East African lake MBT/CBT calibration and MbrGDGTs calibrations, as well as a new stepwise forward selection (SFS) calibration that uses the four combined brGDGTs that explain the most variance in temperature in our calibration set. We apply these new calibrations as well as five previously published lacustrine brGDGT calibrations to the brGDGT distributions of our surface sediment dataset and a 48 kyr sediment core from Sacred Lake, Mt. Kenya, producing the first brGDGT temperature reconstruction available from a small tropical lake. We compare the reconstructed temperatures to previously published paleotemperature records from East Africa to help us assess the performance of the brGDGT calibrations. We find that the SFS calibration has a consistently low root mean squared error of prediction (RMSEP) over the entire range of MAAT, while the MBT/CBT and MbrGDGT calibrations have relatively large RMSEPs, particularly between lakes with similar temperatures but variable pH. This suggests that these techniques do not properly deconvolve the temperature and pH signals recorded in the distributions of the brGDGTs. We further find that only the SFS calibration produces a credible reconstructed temperature history from Sacred Lake when compared to other last glacial maximum paleotemperature estimates from East Africa. Thus, we advocate for the use of the SFS calibration when reconstructing paleotemperatures from brGDGTs in East Africa.

  4. Improving historical precipitation estimates over the Lake Superior basin

    E-print Network

    Wisconsin at Madison, University of

    ,100 km2 (only Lakes Baikal and Tanganyika have larger volumes). Consequently, understandingImproving historical precipitation estimates over the Lake Superior basin K. D. Holman,1,2 A 2012; published 9 February 2012. [1] Lake Superior, the northern-most of the Laurentian Great Lakes

  5. Exposure and effects of perfluoroalkyl compounds on tree swallows nesting at Lake Johanna in east central Minnesota, USA

    USGS Publications Warehouse

    Custer, Christine M.; Custer, Thomas W.; Schoenfuss, Heiko L.; Poganski, Beth H.; Solem, Laura

    2012-01-01

    Tree swallow (Tachycineta bicolor) samples were collected at a reference lake and a nearby lake (Lake Johanna) in east central Minnesota, USA contaminated with perfluorinated carboxylic and sulfonic acids. Tissues were analyzed for a suite of 13 perfluoroalkyl compounds (PFCs) to quantify exposure and to determine if there was an association between egg concentrations of PFCs and reproductive success of tree swallows. Concentrations of perfluoroocatane sulfonate (PFOS) were elevated in all tree swallow tissues from Lake Johanna compared to tissues collected at the reference lake. Other PFCs, except for two, were elevated in blood plasma at Lake Johanna compared to the reference lake. PFOS was the dominant PFC (>75%) at Lake Johanna, but accounted for <50% of total PFCs at the reference lake. There was a negative association between concentrations of PFOS in eggs and hatching success. Reduced hatching success was associated with PFOS levels as low as 150 ng/g wet weight.

  6. Latitudinal Hydrologic Variability Along the East African Rift, Over the Past 200 Kyr

    NASA Astrophysics Data System (ADS)

    Scholz, C. A.

    2014-12-01

    Within the deep sediments of the large lakes of Africa's Great Rift Valley are continuous environmental records of remarkable antiquity and fidelity. Not only do stratigraphic sections from these basins extend back millions of years, many of the intervals represented contain high-resolution material of decadal resolution or better. East African lake basins remain sparsely sampled however, with only a few long and continuous records available. Our ability to image the lakes using seismic reflection methods greatly exceeds our opportunities for coring and drilling however; assessing stratal relationships observed in the geophysical data permits powerful inferences about past hydrologic changes. With intensive hydrocarbon exploration work underway in East Africa, industry well data can also help constrain and ground truth basin histories. Substantial spatio-temporal hydrologic variability is observed in East African basins over the past 200 kyr. Paleohydrological changes in the late Pleistocene and early Holocene are now well constrained in the northern hemisphere East African topics, with widespread aridity and in some cases lake desiccation observed during Heinrich Event 1. A climate recovery followed in the northern hemisphere East African tropics, with the early Holocene African Humid Period a time of positive water balance across most of the rift valley. The paleohydrology of southern hemisphere tropical East Africa is more equivocal, for instance with negligible draw-down of Lake Malawi at HE1. Whereas these late Pleistocene events represent substantial climate reorganizations, severe droughts during the middle-late Pleistocene (150-65 kyr BP) were far more intense, and produced much more severe drawdowns of Lakes Malawi and Tanganyika. Scientific drill cores, kullenberg cores, and extensive seismic reflection data sets from Lakes Malawi and Tanganyika provide indisputable evidence for lowstands of -500m and -600 m respectively. Climate changes that lowered the levels of the large lakes several hundred meters, or desiccated them completely, were regional in extent and would have undoubtedly impacted our early ancestors and early modern humans, as well as drowning and burying ancient sites of early modern human occupation.

  7. Molecular genetic analyses of historical lake sediments from the East African Rift Valley

    NASA Astrophysics Data System (ADS)

    Epp, L. S.; Stoof, K.; Trauth, M. H.; Tiedemann, R.

    2009-04-01

    Ancient DNA research, especially that of environmental samples, has to date focussed mainly on samples obtained from colder regions, owing to better DNA preservation. We explored the potential of using ancient DNA from sediments and sediment cores of shallow lakes in Kenya. These lakes, located in the eastern branch of the East African Rift Valley, are in close proximity, yet display strikingly different hydrological and geological features. Present day lakes range in alkalinity from pH 11 (Lake Elmenteita) to pH 8 (Lake Naivasha), and in depth from less than one meter to 15 meters. Historically they have undergone a number of drastic changes in lake level and environmental conditions, both on geological timescales and during the last centuries. Within this setting we employed molecular genetic methods to study DNA from recent and historic lake sediments, focussing on rotifers and diatoms. We analyzed population and species succession in the alkaline-saline crater lake Sonachi since the beginning of the 19th century, as well as distributions in recent and historic sediments of other lakes of the East African Rift System. To specifically detect diatoms, we developed a protocol using taxon-specific polymerase chain reactions and separation of products by denaturing high performance liquid chromatography (DHPLC). Employing this protocol we retrieved "ancient" DNA from a number of taxonomically diverse organisms, but found diatoms only in sediments younger than approximately 90 years. Using higly specific reactions for rotifers of the genus Brachionus, we tracked species and population succession in Lake Sonachi during the last 200 years. Populations were dominated by a single mitochondrial haplotype for a period of 150 years, and two putatively intraspecific turnovers in dominance occurred. They were both correlated to major environmental changes documented by profound visible changes in sediment composition of the core: the deposition of a volcanic ash and a historical lake level lowstand. The study of historical dynamics within single species is a very promising approach to reveal biotic responses to environmental pressures at a fine, intraspecific scale, and can be carried out using sediment cores as records of continous stratified genetic data.

  8. Littoral sedimentation of rift lakes: an illustrated overview from the modern to Pliocene Lake Turkana (East African Rift System, Kenya)

    NASA Astrophysics Data System (ADS)

    Schuster, Mathieu; Nutz, Alexis

    2015-04-01

    Existing depositional models for rift lakes can be summarized as clastics transported by axial and lateral rivers, then distributed by fan-deltas and/or deltas into a standing water body which is dominated by settling of fine particles, and experiencing occasional coarser underflows. Even if known from paleolakes and modern lakes, reworking of clastics by alongshore drift, waves and storms are rarely considered in depositional models. However, if we consider the lake Turkana Basin (East African Rift System, Kenya) it is obvious that this vision is incomplete. Three representative time slices are considered here: the modern Lake Turkana, the Megalake Turkana which developed thanks to the African Humid Period (Holocene), and the Plio-Pleistocene highstand episodes of paleolake Turkana (Nachukui, Shungura and Koobi Fora Formations, Omo Group). First, remarkable clastic morphosedimentary structures such as beach ridges, spits, washover fans, lagoons, or wave-dominated deltas are very well developed along the shoreline of modern lake Turkana, suggesting strong hydrodynamics responsible for a major reworking of the fluvial-derived clastics all along the littoral zone (longshore and cross-shore transport) of the lake. Similarly, past hydrodynamics are recorded from prominent raised beach ridges and spits, well-preserved all around the lake, above its present water-level (~360 m asl) and up to ~455 m. These large-scale clastic morphosedimentary structures also record the maximum extent of Megalake Turkana during the African Humid Period, as well as its subsequent regression forced by the end of the Holocene climatic optimum. Several hundreds of meters of fluvial-deltaic-lacustrine deposits spanning the Pliocene-Pleistocene are exposed in the Turkana basin thanks to tectonic faulting. These deposits are world famous for their paleontological and archeological content that documents the very early story of Mankind. They also preserve several paleolake highstand episodes with typical sedimentary facies and structures/bodies reflecting important littoral hydrodynamics distributed from the backshore up to the lower shoreface zones. As a consequence, this preliminary overview from the Lake Turkana Basin, suggests that littoral hydrodynamics are important processes of erosion, transport an redeposition of clastics in rift lakes, and should thus be considered in the next generation of depositional models.

  9. VIEW OFPASSAIC FALLS by W. H. Bartlett, 1840 FOSSIL GREAT LAKES

    E-print Network

    Olsen, Paul E.

    the same dimensions as Lake Tanganyika or Lake Baikal; that is, about 32,500 km. While the lake may haveVIEW OFPASSAIC FALLS by W. H. Bartlett, 1840 FOSSIL GREAT LAKES OF THE NEWARK SUPERGROUP IN NEW LAKES OF THE NEWARK SUPERGROUP IN NEW JERSEY PAUL E. OLSEN Bingham Laboratories, Department of Biology

  10. Temporal trends of pollution Pb and other metals in east-central Baffin Island inferred from lake sediment geochemistry

    E-print Network

    Briner, Jason P.

    Temporal trends of pollution Pb and other metals in east-central Baffin Island inferred from lake pollution Lead stable isotopes Paleolimnology Arctic lakes Sediment geochemistry Atmospheric deposition of anthropogenic Pb pollution in the Clyde River region of Baffin Island, Arctic Canada. Surface sediments from

  11. Temporal trends of pollution Pb and other metals in east-central Baf n Island inferred from lake sediment geochemistry

    E-print Network

    Wolfe, Alexander P.

    Temporal trends of pollution Pb and other metals in east-central Baf n Island inferred from lake pollution Lead stable isotopes Paleolimnology Arctic lakes Sediment geochemistry Atmospheric deposition of anthropogenic Pb pollution in the Clyde River region of Baf n Island, Arctic Canada. Surface sediments from

  12. Distribution and ecological risk assessment of organochlorine pesticides in surface sediments from the East Lake, China.

    PubMed

    Yun, Xiaoyan; Yang, Yuyi; Liu, Minxia; Wang, Jun

    2014-09-01

    Organochlorine pesticides (OCPs) are ubiquitous pollutants, and their presence in urban lakes is a concern for human and ecological health. Surface sediments in the East Lake, China, were collected in winter 2012 and summer 2013 to investigate concentrations, distribution patterns, possible sources, and potential ecological risks of OCPs in this area. The total concentrations of 14 OCPs ranged from 6.3 to 400 ng g(-1) dry weight (dw) with an average concentration of 79 ng g(-1) dw. The mean values of hexachlorocyclohexanes (HCHs) (?-, ?-, ?-, and ?-HCH) and dichlorodiphenyltrichloroethanes (DDTs) (p,p'-DDE, p,p'-DDD, and p,p'-DDT) were 36 and 7.6 ng g(-1) dw, accounting for 45 and 10 % of the total OCPs, respectively. The concentrations of OCPs in sediment samples collected in winter were significantly higher than those in summer, especially the HCHs, of which in winter were two times greater than summer. Composition analyses indicated that DDTs and endosulfan were mainly from historical contribution. Historical use of technical HCH and new input of lindane were probably the source of HCHs in the East Lake. Most sampling sites of HCHs and DDTs were found to have the potential ecological risk based on levels specified in the sediment quality standards. PMID:24756687

  13. Sunspots, El Niño, and the levels of Lake Victoria, East Africa

    NASA Astrophysics Data System (ADS)

    Stager, J. Curt; Ruzmaikin, Alexander; Conway, Declan; Verburg, Piet; Mason, Peter J.

    2007-08-01

    An association of high sunspot numbers with rises in the level of Lake Victoria, East Africa, has been the focus of many investigations and vigorous debate during the last century. In this paper, we show that peaks in the ~11-year sunspot cycle were accompanied by Victoria level maxima throughout the 20th century, due to the occurrence of positive rainfall anomalies ~1 year before solar maxima. Similar patterns also occurred in at least five other East African lakes, which indicates that these sunspot-rainfall relationships were broadly regional in scale. Although irradiance fluctuations associated with the sunspot cycle are weak, their effects on tropical rainfall could be amplified through interactions with sea surface temperatures and atmospheric circulation systems, including ENSO. If this Sun-rainfall relationship persists in the future, then sunspot cycles can be used for long-term prediction of precipitation anomalies and associated outbreaks of insect-borne disease in much of East Africa. In that case, unusually wet rainy seasons and Rift Valley Fever epidemics should occur a year or so before the next solar maximum, which is expected to occur in 2011-2012 AD.

  14. Regional nitrogen budget of the Lake Victoria Basin, East Africa: syntheses, uncertainties and perspectives

    NASA Astrophysics Data System (ADS)

    Zhou, Minghua; Brandt, Patric; Pelster, David; Rufino, Mariana C.; Robinson, Timothy; Butterbach-Bahl, Klaus

    2014-10-01

    Using the net anthropogenic nitrogen input (NANI) approach we estimated the N budget for the Lake Victoria Basin in East Africa. The NANI of the basin ranged from 887 to 3008 kg N km-2 yr-1 (mean: 1827 kg N km-2 yr-1) for the period 1995-2000. The net nitrogen release at basin level is due primarily to livestock and human consumption of feed and foods, contributing between 69% and 85%. Atmospheric oxidized N deposition contributed approximately 14% to the NANI of the Lake Victoria Basin, while either synthetic N fertilizer imports or biological N fixations only contributed less than 6% to the regional NANI. Due to the low N imports of feed and food products (<20 kg N km-2 yr-1), nitrogen release to the watershed must be derived from the mining of soil N stocks. The fraction of riverine N export to Lake Victoria accounted for 16%, which is much lower than for watersheds located in Europe and USA (25%). A significant reduction of the uncertainty of our N budget estimate for Lake Victoria Basin would be possible if better data on livestock systems and riverine N export were available. Our study indicates that at present soil N mining is the main source of nitrogen in the Lake Victoria Basin. Thus, sustainable N management requires increasing agricultural N inputs to guarantee food security and rehabilitation and protection of soils to minimize environmental costs. Moreover, to reduce N pollution of the lake, improving management of human and animal wastes needs to be carefully considered in future.

  15. Continuous seismic-reflection survey of the Great Salt Lake, Utah- east of Antelope and Fremont Islands

    USGS Publications Warehouse

    Lambert, P.M.; West, J.C.

    1989-01-01

    A continuous seismic-reflection survey of the Great Salt Lake, Utah, was conducted east of Fremont and Antelope Islands in 1984 by the U.S. Geological Survey in cooperation with the Utah Department of Natural Resources and produced data along approximately 80 miles of seismic lines. The survey was conducted to determine depth to consolidated rock, and definition and continuity of overlying basin fill under the lake. Interpretation of the data indicates the presence of faulted rock dipping away from Fremont and Antelope Islands. A north-south-trending consolidated-rock ridge is identified 200 ft below lake bottom, 275 miles east of Fremont Island. Shallow rock is also inferred 380 ft below lake bottom, near Hooper Hot Springs, and 520 ft below lake bottom approximately 4 miles east of the south end of Antelope Island. Interpretation of reflections from overlying basin fill indicates fine-grained, thinly-bedded deposits that become coarser with depth. Strong reflectors in the basin fill can be correlated with water-bearing strata penetrated by wells near the north end of Antelope Island and along the east shore of the lake. Many continuous, high-amplitude reflections can be identified in data from basin fill and may represent sedimentary sections or aquifer boundaries but cannot be defined because of a lack of subsurface control in the area. (USGS)

  16. Sedimentology and geochemistry of a perennially ice-covered epishelf lake in Bunger Hills Oasis, East Antarctica

    NASA Technical Reports Server (NTRS)

    Doran, P. T.; Wharton, R. A. Jr; Lyons, W. B.; Des Marais, D. J.; Andersen, D. T.; Wharton RA, J. r. (Principal Investigator)

    2000-01-01

    A process-oriented study was carried out in White Smoke lake, Bunger Hills, East Antarctica, a perennially ice-covered (1.8 to 2.8 m thick) epishelf (tidally-forced) lake. The lake water has a low conductivity and is relatively well mixed. Sediments are transferred from the adjacent glacier to the lake when glacier ice surrounding the sediment is sublimated at the surface and replaced by accumulating ice from below. The lake bottom at the west end of the lake is mostly rocky with a scant sediment cover. The east end contains a thick sediment profile. Grain size and delta 13C increase with sediment depth, indicating a more proximal glacier in the past. Sedimentary 210Pb and 137Cs signals are exceptionally strong, probably a result of the focusing effect of the large glacial catchment area. The post-bomb and pre-bomb radiocarbon reservoirs are c. 725 14C yr and c. 1950 14C yr, respectively. Radiocarbon dating indicates that the east end of the lake is >3 ka BP, while photographic evidence and the absence of sediment cover indicate that the west end has formed only over the last century. Our results indicate that the southern ice edge of Bunger Hills has been relatively stable with only minor fluctuations (on the scale of hundreds of metres) over the last 3000 years.

  17. Sedimentology and geochemistry of a perennially ice-covered epishelf lake in Bunger Hills Oasis, East Antarctica.

    PubMed

    Doran, P T; Wharton, R A; Lyons, W B; Des Marais, D J; Andersen, D T

    2000-01-01

    A process-oriented study was carried out in White Smoke lake, Bunger Hills, East Antarctica, a perennially ice-covered (1.8 to 2.8 m thick) epishelf (tidally-forced) lake. The lake water has a low conductivity and is relatively well mixed. Sediments are transferred from the adjacent glacier to the lake when glacier ice surrounding the sediment is sublimated at the surface and replaced by accumulating ice from below. The lake bottom at the west end of the lake is mostly rocky with a scant sediment cover. The east end contains a thick sediment profile. Grain size and delta 13C increase with sediment depth, indicating a more proximal glacier in the past. Sedimentary 210Pb and 137Cs signals are exceptionally strong, probably a result of the focusing effect of the large glacial catchment area. The post-bomb and pre-bomb radiocarbon reservoirs are c. 725 14C yr and c. 1950 14C yr, respectively. Radiocarbon dating indicates that the east end of the lake is >3 ka BP, while photographic evidence and the absence of sediment cover indicate that the west end has formed only over the last century. Our results indicate that the southern ice edge of Bunger Hills has been relatively stable with only minor fluctuations (on the scale of hundreds of metres) over the last 3000 years. PMID:11543521

  18. Effects of artificial destratification on water quality at East Sidney Lake, New York. Final report

    SciTech Connect

    Ashby, S.L.; Kennedy, R.H.

    1993-09-01

    Artificial destratification has been applied at East Sidney Lake to enhance water quality of the reservoir and tailwater. Operation of the destratification system during the growing season maintained near-isothermal temperatures in the reservoir, thereby maintaining oxygenated conditions in the bottom waters via atmospheric exchange during mixing. Maintenance of aerobic bottom waters decreased solubilization of sedimentary metals, decreased internal loading of sedimentary phosphorus, increased available habitat for aquatic organisms, and improved discharge quality. Populations of algal species excessive levels in late summer, even with decreased internal phosphorus loading and disruption of thermal gradients. Consequently, improvements in water clarity were not observed. Algal control, Internal loading, Artificial destratification, Reservoirs, Eutrophication, Water quality enhancement.

  19. Methanotrophy within the water column of a large meromictic tropical lake (Lake Kivu, East Africa)

    NASA Astrophysics Data System (ADS)

    Morana, C.; Borges, A. V.; Roland, F. A. E.; Darchambeau, F.; Descy, J.-P.; Bouillon, S.

    2014-11-01

    The permanently stratified Lake Kivu is one of the largest freshwater reservoirs of dissolved methane (CH4) on Earth. Yet CH4 emissions from its surface to the atmosphere has been estimated to be 2 orders of magnitude lower than the CH4 upward flux to the mixed layer, showing that microbial CH4 oxidation is an important process within the water column. A combination of natural abundance carbon stable isotope analysis (?13C) of several inorganic and organic carbon pools and 13CH4-labelling experiments was carried out during rainy and dry season to quantify (i) the contribution of CH4-derived carbon to the biomass, (ii) methanotrophic bacterial production (MBP), and (iii) methanotrophic bacterial growth efficiency (MBGE), defined as the ratio between MBP and gross CH4 oxidation. We also investigated the distribution and the ?13C of specific phospholipid fatty acids (PLFA), used as biomarkers for aerobic methanotrophs. Data revealed that methanotrophic organisms oxidized within the water column most of the upward flux of CH4 to the mixed layer and a significant amount of CH4-derived carbon was incorporated into the microbial biomass in the oxycline. Maximal MBP rates were measured in the oxycline, suggesting that CH4 oxidation was mainly driven by oxic processes. The MBGE was variable (2-50%) and negatively related to CH4 : O2 molar ratios. Thus, a comparatively smaller fraction of CH4-derived carbon was incorporated into the cellular biomass in deeper waters, at the bottom of the oxycline where oxygen was scarce. The aerobic methanotrophic community was clearly dominated by type I methanotrophs and no evidence was found for an active involvement of type II methanotrophs in CH4 oxidation in Lake Kivu. Vertically integrated over the water column, the MBP was equivalent to 16-58% of the average phytoplankton primary production. This relatively high magnitude of MBP, and the substantial contribution of CH4-derived carbon to the overall biomass in the oxycline, suggest that methanotrophic bacteria could potentially sustain a significant fraction of the pelagic food-web in the deep oligotrophic Lake Kivu.

  20. Methanotrophy within the water column of a large meromictic tropical lake (Lake Kivu, East Africa)

    NASA Astrophysics Data System (ADS)

    Morana, C.; Borges, A. V.; Roland, F. A. E.; Darchambeau, F.; Descy, J.-P.; Bouillon, S.

    2015-04-01

    The permanently stratified Lake Kivu is one of the largest freshwater reservoirs of dissolved methane (CH4) on Earth. Yet CH4 emissions from its surface to the atmosphere have been estimated to be 2 orders of magnitude lower than the CH4 upward flux to the mixed layer, suggesting that microbial CH4 oxidation is an important process within the water column. A combination of natural abundance stable carbon isotope analysis (?13C) of several carbon pools and 13CH4-labelling experiments was carried out during the rainy and dry season to quantify (i) the contribution of CH4-derived carbon to the biomass, (ii) methanotrophic bacterial production (MBP), and (iii) methanotrophic bacterial growth efficiency (MBGE), defined as the ratio between MBP and gross CH4 oxidation. We also investigated the distribution and the ?13C of specific phospholipid fatty acids (PLFAs), used as biomarkers for aerobic methanotrophs. Maximal MBP rates were measured in the oxycline, suggesting that CH4 oxidation was mainly driven by oxic processes. Moreover, our data revealed that methanotrophic organisms in the water column oxidized most of the upward flux of CH4, and that a significant amount of CH4-derived carbon was incorporated into the microbial biomass in the oxycline. The MBGE was variable (2-50%) and negatively related to CH4 : O2 molar ratios. Thus, a comparatively smaller fraction of CH4-derived carbon was incorporated into the cellular biomass in deeper waters, at the bottom of the oxycline where oxygen was scarce. The aerobic methanotrophic community was clearly dominated by type I methanotrophs and no evidence was found for an active involvement of type II methanotrophs in CH4 oxidation in Lake Kivu, based on fatty acids analyses. Vertically integrated over the water column, the MBP was equivalent to 16-60% of the average phytoplankton particulate primary production. This relatively high magnitude of MBP, and the substantial contribution of CH4-derived carbon to the overall biomass in the oxycline, suggest that methanotrophic bacteria could potentially sustain a significant fraction of the pelagic food web in the deep, meromictic Lake Kivu.

  1. Exploring Subglacial Lake Connectivity via Groundwater Aquifers in the Dome C Region, East Antarctica

    NASA Astrophysics Data System (ADS)

    Gooch, B. T.; Carter, S. P.; Blankenship, D. D.

    2011-12-01

    Subglacial lakes lying under the Antarctic Ice Sheet form part of a dynamic, interconnected hydraulic system. Most research exploring the nature of this system has focused on flow along the ice-bed interface, neglecting the effects of groundwater transport, as such systems are thought to lack the transmissivity necessary to accommodate the inferred meltwater volume. In the Dome C region of East Antarctica, however, inferred melt water volumes are relatively low due to proximity to the ice divide and hydraulic gradients are relatively high due to steep subglacial bedrock topography, such that groundwater flow might be viable as a dominant means of water transport. This region contains many small subglacial lakes residing in bedrock depressions of steep basal topography. Preliminary analysis of radar sounding data does not always reveal an obvious hydraulic connection between these lakes despite readily apparent sources of melt feeding these bodies. Here we test several simple models for groundwater flow, including both fractured rock and porous media systems using ice-surface and bedrock geometry inferred from radio-echo sounding data and a published map of melt rates, with the purpose of defining a region in which a groundwater system can account for the majority of the water budget. We then compare these results against maps of basal reflectivity and subglacial lake distribution, as determined from radar sounding data. Areas in which groundwater flow is the dominant process will lack basal lubrication and demonstrate low basal reflectivities, but could still contain small subglacial lakes. While not spatially extensive with respect to the ice sheet, these groundwater-dominated areas could occupy the headwaters of most glacial catchments representing a unique and relatively stable subglacial environment.

  2. Functional coupling constrains craniofacial diversification in Lake Tanganyika cichlids.

    PubMed

    Tsuboi, Masahito; Gonzalez-Voyer, Alejandro; Kolm, Niclas

    2015-05-01

    Functional coupling, where a single morphological trait performs multiple functions, is a universal feature of organismal design. Theory suggests that functional coupling may constrain the rate of phenotypic evolution, yet empirical tests of this hypothesis are rare. In fish, the evolutionary transition from guarding the eggs on a sandy/rocky substrate (i.e. substrate guarding) to mouthbrooding introduces a novel function to the craniofacial system and offers an ideal opportunity to test the functional coupling hypothesis. Using a combination of geometric morphometrics and a recently developed phylogenetic comparative method, we found that head morphology evolution was 43% faster in substrate guarding species than in mouthbrooding species. Furthermore, for species in which females were solely responsible for mouthbrooding the males had a higher rate of head morphology evolution than in those with bi-parental mouthbrooding. Our results support the hypothesis that adaptations resulting in functional coupling constrain phenotypic evolution. PMID:25948565

  3. Functional coupling constrains craniofacial diversification in Lake Tanganyika cichlids

    PubMed Central

    Tsuboi, Masahito; Gonzalez-Voyer, Alejandro; Kolm, Niclas

    2015-01-01

    Functional coupling, where a single morphological trait performs multiple functions, is a universal feature of organismal design. Theory suggests that functional coupling may constrain the rate of phenotypic evolution, yet empirical tests of this hypothesis are rare. In fish, the evolutionary transition from guarding the eggs on a sandy/rocky substrate (i.e. substrate guarding) to mouthbrooding introduces a novel function to the craniofacial system and offers an ideal opportunity to test the functional coupling hypothesis. Using a combination of geometric morphometrics and a recently developed phylogenetic comparative method, we found that head morphology evolution was 43% faster in substrate guarding species than in mouthbrooding species. Furthermore, for species in which females were solely responsible for mouthbrooding the males had a higher rate of head morphology evolution than in those with bi-parental mouthbrooding. Our results support the hypothesis that adaptations resulting in functional coupling constrain phenotypic evolution. PMID:25948565

  4. Atlanta's Successful Charles R. Drew Charter School: The Cornerstone of East Lake's Community Transformation. The Abell Report. Volume 27, No.1

    ERIC Educational Resources Information Center

    Eberhart, Linda; Barnes, Tara

    2014-01-01

    The community of East Lake, home to Charles R. Drew Charter School (Drew), is 6 miles from downtown Atlanta. In 1995, crime in East Lake was 19 times higher than the national average. Now, violent crime is down 95 percent. In 1995, 88 percent of residents were unemployed. Now, only 5 percent receive welfare. In 1995, just 5 percent of fifth…

  5. Coupling 2H and 18O biomarker results provides new insight into palaeohumidity changes in East Africa during the last glacial

    NASA Astrophysics Data System (ADS)

    Hepp, Johannes; Zech, Roland; Tuthorn, Mario; Glaser, Bruno; Rozanski, Kazimierz; Zech, Wolfgang; Zech, Michael

    2015-04-01

    We couple compound-specific ?2H results of leaf wax-derived n-alkanes with compound-specific ?18O results of hemicellulose-derived sugars extracted from the loess-paleosol-sequence Maundi (3° 10'27.5'S, 37° 31'05.8'E) located on the south-eastern slopes of Mt. Kilimanjaro at ~ 2780 m above sea level. This coupled biomarker approach allows inter alia establishing a ca. 100 ka record of the isotopic composition of leaf water. Accordingly, the deuterium-excess of leaf water may serve as a proxy for palaeohumidity. Furthermore, the coupled biomarker approach allows reconstructing the isotopic composition of palaeoprecipitation (by using the slope the local evaporation line derived from a simple Craig-Gordon model). Our results suggest that sedimentary ?2Hleaf-wax records should not be interpreted directly in terms of reflecting ?2Hprec because variable leaf water evaporative enrichment can strongly overprint the ?2Hprec signal. The Maundi ?2Hn-alkane record can be compared with ?2Hwax records from Lake Challa, Lake Tanganyika and Lake Malawi. Accordingly, the Maundi ?2Hn-alkane record is generally in good agreement with the Lake Challa and the Lake Tanganyika ?2Hwax records. However, a clear altitude effect can be seen in the ?2H records (Maundi: 2780 m a.s.l.; Lake Challa: 880 m a.s.l.; Lake Tanganyika: 773 m a.s.l.; Lake Malawi: 474 m a.s.l.). Moreover, the Maundi ?2Hn-alkane record reveals a clear smaller range compared to the other ?2Hwax records. Finally, especially the Lake Malawi ?2Hwax record reveals also clearly different features than the other available ?2Hwax records. These differences resulted in different interpretations of the ?2Hwax records (amount effect vs. source effect). Our coupled ?18Osugar and ?2Hn-alkane approach sheds new light into this discussion. In brief, reconstructed low deuterium-excessleaf-water values during the African Humid Period (AHP) indicate humid climatic conditions. By contrast, higher deuterium-excessleaf-water values indicate that arid climatic conditions prevailed during the Younger Dryas (YD), the Last Glacial Maximum (LGM) and during a mega drought period (MD) having occurred ~ 70-60 ka BP. Including the Maundi precipitation record in a circum pacific comparison may help to identify the drivers of past isotopic composition on east equatorial African precipitation.

  6. Holocene precipitation and thermal coherence at Lakes Albert and Victoria, East Africa

    NASA Astrophysics Data System (ADS)

    Berke, M. A.; Johnson, T. C.; Werne, J. P.; Grice, K.; Schouten, S.; Sinninghe Damsté, J. S.

    2011-12-01

    New molecular proxy records of temperature and rainfall from lacustrine sedimentary archives are helping to constrain the tropical response to global climate change and elucidate possible forcing mechanisms during the latest Pleistocene and Holocene in East Africa. It is often noted that tropical ecosystems are more sensitive to perturbations in rainfall than in temperature, due to the limited thermal range of tropical climate, however coincident shifts would likely enhance climate response to regional variability. Furthermore, on shorter time scales, patterns of moisture balance and temperature are often linked in East Africa. Here we present new records of rainfall from Lakes Albert and Victoria, using compound specific ?D from terrestrial leaf waxes, and compare these trends to TEX86 paleotemperature records in order to assess the coherence between tropical precipitation and temperature. Our results indicate generally synchronous shifts at these sites, roughly in-phase with regional climate behavior during this interval. A high resolution climate history at Lake Albert highlights a significant multi-stage cool and arid excursion characteristic of the last deglaciation, beginning ~13.8 ka and ending rapidly at ~11.5 ka and marked by a ~55% D-enrichment and 3°C cooling, linking this tropical region to high latitude climate events. The molecular perspective on the climate surrounding Lake Victoria indicates a warm, humid interval peaking at 10-9 ka, and subsequent gradual cooling and drying over the remainder of the Holocene, exhibiting shifts of ~40% in ?D and ~5°C, and thus showing a strong correlation to summer insolation. Palynological and ?13C biomarker evidence from these sites indicate significant, but not coinciding, shifts in aspects of the terrestrial vegetation ecosystem that are not well understood. Both regions support a linkage between high latitude and equatorial African climate systems, with likely teleconnections to the Indian monsoon system.

  7. Geothermal Flux, Basal Melt Rates, and Subglacial Lakes in Central East Antarctica

    NASA Astrophysics Data System (ADS)

    Carter, S. P.; Blankenship, D. D.; Morse, D. L.

    2002-12-01

    The lakes beneath the East Antarctic ice sheet represent a unique environment on Earth, entirely untouched by human interference. Life forms which survive in this cold, lightless, high pressure environment may resemble the life forms which survived through "snowball earth" and evolved into the life forms we know today (Kirchvink, 2000). Recent airborne radar surveys over Dome C and the South Pole regions allow us to assess where these lakes are most likely to exist and infer melting and freezing rates at base of the ice sheet. Lakes appear as strong, flat basal reflectors in airborne radar sounding data. In order to determine the absolute strength of the reflector it is important to accurately estimate signal loss due to absorption by the ice. As this quantity is temperature sensitive, especially in regions where liquid water is likely to exist, we have developed a one dimensional heat transfer model, incorporating surface temperature, accumulation, ice sheet thickness, and geothermal flux. Of the four quantities used for our temperature model, geothermal flux has usually proven to be the most difficult to asses, due to logistical difficulties. A technique developed by Fahnestock et al 2001 is showing promise for inferring geothermal flux, with airborne radar data. This technique assumes that internal reflectors, which result from varying electrical properties within the ice column, can be approximated as constant time horizons. Using ice core data from our study area, we can place dates upon these internal layers and develop an age versus depth relationship for the surveyed region, with margin of error of +- 50 m for each selected layer. Knowing this relationship allows us to infer the vertical strain response of the ice to the stress of vertical loading by snow accumulation. When ice is frozen to the bed the deeper ice will accommodate the increased stress of by deforming and thinning (Patterson 1994). This thinning of deeper layers occurs throughout most of our study area. However, analysis of dated internal layers over several bright, flat, "lake-like" reflectors reveals a very different age versus depth relationship in which deeper layers actually thicken with depth. This thickening of deep layers results from ice flowing in from the sides to accommodate significant liquid water production at the base of the ice sheet. This melt is occurring today and can be quantified. With our knowledge of melt rates we can begin to estimate inputs and assess hydrologic parameters for the subglacial lake systems of East Antarctica.

  8. Deltas of the Lake Malawi rift, east Africa: Seismic expression and exploration implications

    SciTech Connect

    Scholz, C.A.

    1995-11-01

    High-resolution, air-gun-sourced seismic reflection surveys over the offshore regions of five river deltas in Lake Malawi in the East African rift system reveal considerable variability in acoustic facies and stratigraphic architecture. This variability can largely be attributed to the influences of different structural settings, and to a lesser degree to high-amplitude (100-400 m) and high-frequency (1000 to 100,000 yr) fluctuations in lake level. Deltas on flexural and axial margins in the rift lake show well-developed progradational geometries. In contrast, a delta on a steep, accommodation zone margin distributes coarse sediments over a broad depositional apron, rather than concentrating sediment in discrete progradational lobes as on the other deltas. A large border fault margin river delta displays the most complex tectonic and stratigraphic architecture of all the deltas studied. It contains several delta-associated facies, including prograding clinoform packages, fan deltas stacked against a boundary fault, and extensive subaqueous fans. Flexural margin lowstand deltas may be the most prospective for hydrocarbon exploration due to their large, internally well-organized, progradational lobes and their close proximity to deep-water, high total organic carbon lacustrine source facies.

  9. Deliberations on Microbial Life in the Subglacial Lake Vostok, East Antarctica

    NASA Astrophysics Data System (ADS)

    Bulat, S.; Alekhina, I.; Lipenkov, V.; Lukin, V.; Marie, D.; Petit, J.

    2004-12-01

    The objective was to estimate microbial contents of accretion (lake originating) ice from the Lake Vostok buried beneath 4-km thick East Antarctic ice sheet with the ultimate goal to discover microbial life in this extreme icy environment featured by no light, close to freezing point temperature, ultra-low DOC contents, and an excess of oxygen. The PCR based bacterial and archaeal 16S ribosomal RNA gene sequencing constrained by Forensic Biology and Ancient DNA research criteria was used as a main approach. Epifluorescent and confocal microscopies as well as flow cytometry were implemented. DNA study showed that the accretion ice is essentially bacteria- and archaea-free. Up to now, the only accretion ice type 1 featured by mica-clay sediments presence and namely one horizon of four studied (3607m) allowed the recovery a few bacterial phylotypes. This unexpectedly included the chemolithoautotrophic thermophile Hydrogenophilus thermoluteolus and two more unclassified phylotypes all passing numerous contaminant controls. In contrast, the deeper and cleaner accretion ice 2 (three cores) with no sediments presence and near detection limit gas contents gave no reliable signals. The microbes detected in accretion ice 1 are unbelievable to resist an excess of oxygen in the lake water body (700 - 1300 mg O2/l). They are supposed to be thriving in rather warm anoxic sediments in deep faults at the lake bottom and sporadically flushing out along with sediments to the lake veins in a shallow depth bay due to a seismotectonic activity likely operating in the lake environment. A few geophysical and geological evidences support this scenario. In the bay the presence of mica-clay sediments, higher accretion rate due to relief rise and likely oxygen-depleted upper layer of water can provide microbes with a chance to escape the high oxygen tension by the rapid entrapment into accretion ice 1. Sediment-free accretion ice 2, which forms above a deeper part of the lake, shows no evidence for reasonable source for microbe contribution given highly oxygenated lake water environment. Microscopy and flow cytometry trials on strictly decontaminated ice samples gave supporting results. While microscopy failed to reveal cells because the local concentrations were below the detection limit, the flow cytometry succeeded in a preliminary estimate of 9 and 24 cells/ml for accretion 1 (3561m) and control glacial (2054m) ice samples, respectively. However, given the ratio contaminants to indigenous cells is about 10:1 (from PCR results), the genuine microbial contents for both accretion and glacial ice samples is expected to be as low as 1 cell/ml what practically means "sterile" conditions. Thus, the accretion ice from Lake Vostok contains the very low unevenly distributed biomass indicating that the water body (at least upper layer) should also be hosting a highly sparse life, if any. By this, the Lake Vostok for the first time could present the big natural "sterile" water body on Earth providing a unique test area for searching for life on icy moons and planets. The search for life in Lake Vostok is constrained by a high chance of forward-contamination which can be minimized by using of stringent decontamination procedures and comprehensive biological controls.

  10. Comparison of the Microbial Diversity and Abundance Between the Freshwater Land-Locked Lakes of Schirmacher Oasis and the Perennially Ice-Covered Lake Untersee in East Antarctica

    NASA Technical Reports Server (NTRS)

    Huang, Jonathan; Hoover, Richard B.; Swain, Ashit; Murdock, Chris; Bej, Asim K.

    2010-01-01

    Extreme conditions such as low temperature, dryness, and constant UV-radiation in terrestrial Antarctica are limiting factors of the survival of microbial populations. The objective of this study was to investigate the microbial diversity and enumeration between the open water lakes of Schirmacher Oasis and the permanently ice-covered Lake Untersee. The lakes in Schirmacher Oasis possessed abundant and diverse group of microorganisms compared to the Lake Untersee. Furthermore, the microbial diversity between two lakes in Schirmacher Oasis (Lake L27C and L47) was compared by culture-based molecular approach. It was determined that L27Chad a richer microbial diversity representing 5 different phyla and 7 different genera. In contrast L47 consisted of 4 different phyla and 6 different genera. The difference in microbial community could be due to the wide range of pH between L27C (pH 9.1) and L47 (pH 5.7). Most of the microbes isolated from these lakes consisted of adaptive biological pigmentation. Characterization of the microbial community found in the freshwater lakes of East Antarctica is important because it gives a further glimpse into the adaptation and survival strategies found in extreme conditions.

  11. Methanotrophy and chemoautotrophy within the redox gradient of a large and deep tropical lake (Lake Kivu, East Africa)

    NASA Astrophysics Data System (ADS)

    Morana, Cedric; Borges, Alberto V.; Darchambeau, François; Roland, Fleur; Montante, Laetitia; Descy, Jean-Pierre; Bouillon, Steven

    2014-05-01

    Lake Kivu (East Africa) is a large (2370 km2) and deep (maximum depth of 485 m) meromictic lake. Its vertical structure consists of an oxic and nutrient-poor mixed layer down to 70 m maximum, and a permanently anoxic monimolimnion rich in dissolved gases (methane and carbon dioxide) and inorganic nutrients. Seasonal variation of the vertical position of the oxic-anoxic interface is driven by contrasting precipitation and wind speed regimes between rainy (October-May) and dry (June-September) season, the latter being characterized by a deepening of the oxic zone, and an increased input of dissolved gases and inorganic nutrients. Our work aimed at quantifying methanotrophic and chemoautotrophic production within the redox gradient of Lake Kivu and identifying the micro-organisms involved in these processes using phospholipid-derived fatty acid markers and their carbon stable isotope composition. Our approach combined both natural stable isotope abundance analysis and 13C-labelling (13C-DIC ; 13C-CH4) experiments. Sampling was carried out at two stations in Lake Kivu during rainy (February 2012) and dry (September 2012) season conditions. Methanotrophic bacterial production rates were highly variable (from 0.1 to 7.0 ?mol C L-1 d-1), but maximum values were always observed at the oxic-anoxic interface when the CH4:O2 ratio varied between 0.1 and 10, suggesting that the majority of methane was oxidized aerobically. Furthermore, strong stable isotope labelling of monounsaturated C16 fatty acids indicate that active methane oxidizers were related to the group of type I aerobic methanotrophs (gammaproteobacteria). Despite the dominance of aerobic methane oxidation, significant methanotrophic bacterial production rates were found below the oxic-anoxic interface during the rainy season, indicating that at least a fraction of the upcoming methane may be oxidized anaerobically. This observation was further confirmed by the strong labelling at these depths of the 10Me16:0 fatty acid, biomarker for sulphate-reducing bacteria, the syntrophic partners of anaerobic methane-oxidizing archaea. The methanotrophic bacterial growth efficiency (MBGE) was variable (2-50%), and inversely related to methane concentration. Maximum chemoautotrophic bacterial production rates were recorded well below the oxycline, in sulfidic waters. However, during the rainy season, significant dark C fixation rates were measured near the oxic-anoxic interface, in a nitracline where sulphide was absent, suggesting that another energy source was involved. Incorporation of labelled carbon in the 16:1?9c ; 16:1?7c and 18:1?7 fatty acids suggest that the active chemoautotrophic organisms belong to the phylum proteobacteria. Together, the vertically integrated methanotrophic and chemoautotrophic production rates were 31 mmol m-2 d-1 and 41 mmol-2 d-1 during the rainy and dry season, respectively. These values are comparable to the net phytoplanktonic production rates in Lake Kivu ranging between 12 and 160 mmol m-2 d-1 (on average 52 mmol m-2 d-1). Our results indicate that methanotrophs and chemoautotrophs contribute substantially to the carbon cycle in Lake Kivu.

  12. Drying out the Nile? Regional Climate Change and Water Resources in East Africa with a focus on Lake Victoria and Lake Tana

    NASA Astrophysics Data System (ADS)

    Mottram, Ruth; Fox Maule, Cathrine; Thejll, Peter; Stendel, Martin; Drews, Martin; Davies, Sarah; Lamb, Henry

    2014-05-01

    The East African lakes Victoria and Tana are important local water resources for agriculture, fisheries and hydropower; they are also the main sources of the Nile. In this study we focus on the evaporative and evapotranspirative regimes of the hydrological basins for Lakes Tana and Victoria to determine how regional climate change under the A1B scenario is likely to affect the local and regional hydrology. We show results from a very high resolution (10km) simulation, where the state-of-the-art regional climate model (RCM) HIRHAM5 was driven by the global circulation model (GCM) ECHAM5 under the A1B scenario. Three time-slices have been investigated for present day (1980-1999), mid-century (2046-2065) and end of the 21st century (2080-2099) periods. Our analysis includes a comparison with a coarser 0.44o (~50 km) resolution run which demonstrates the importance of using high resolution (10km or higher) in RCM studies of this type to correctly simulate the seasonal and geographical characteristics of the present day east African monsoon system. The projections also indicate that climate change under the intermediate SRES A1B scenario is expected to cause more frequent failures of the East African rains with important consequences for the region and for the hydrology of the East African Lakes. This work introduces the proposed DACEA (Drivers of Aridity Change in East Africa) project which aims to investigate regional and global teleconnections that affect aridity in East Africa. Future work will combine climate palaeoproxies from Lake Tana and Lake Victoria with model experiments carried out with the EC-Earth coupled Ocean-Atmosphere General Circulation Model and downscaled to very high resolution with the RCM HIRHAM5 to determine regional and global scale influences on the African monsoon system. The HIRHAM5 simulations will be dynamically coupled to a regional hydrological model based on MIKE SHE, to evaluate the consequences and the feedback from the regional hydrology of the lake basins in terms of the East African rains.

  13. Post-Depositional Behavior of Cu in a Metal-Mining Polishing Pond (East Lake, Canada)

    USGS Publications Warehouse

    Martin, A.J.; Jambor, J.L.; Pedersen, Thomas F.; Crusius, J.

    2003-01-01

    The post-depositional behavior of Cu in a gold-mining polishing pond (East Lake, Canada) was assessed after mine closure by examination of porewater chemistry and mineralogy. The near-surface (upper 1.5 cm) sediments are enriched in Cu, with values ranging from 0.4 to 2 wt %. Mineralogical examination revealed that the bulk of the Cu inventory is present as authigenic copper sulfides. Optical microscopy, energy-dispersion spectra, and X-ray data indicate that the main Cu sulfide is covellite (CuS). The formation of authigenic Cu-S phases is supported by the porewater data, which demonstrate that the sediments are serving as a sink for dissolved Cu below sub-bottom depths of 1-2 cm. The zone of Cu removal is consistent with the occurrence of detectable sulfide and the consumption of sulfate. The sediments can be viewed as a passive bioreactor that permanently removes Cu as insoluble copper sulfides. This process is not unlike that which occurs in other forms of bioremediation, such as wetlands and permeable reactive barriers. Above the zone of Cu removal, dissolved Cu maxima in the interfacial porewaters range from 150 to 450 ??g L-1 and reflect the dissolution of a Cu-bearing phase in the surface sediments. The reactive phase is thought to be a component of treatment sludges delivered to the lake as part of cyanide treatment. Flux calculations indicate that the efflux of dissolved Cu from the sediments to the water column (14-51 ??g cm-2 yr-1) can account for the elevated levels of dissolved Cu in lake waters (???50 ??g L-1). Implications for lake recovery are discussed.

  14. The impact of the African Great Lakes on the regional climate in a dynamically downscaled CORDEX simulation

    NASA Astrophysics Data System (ADS)

    Thiery, Wim; Panitz, Hans-Jürgen; Davin, Edouard; van Lipzig, Nicole

    2014-05-01

    Owing to the strong contrast in albedo, roughness and heat capacity between land and water, lakes significantly influence the exchange of moisture, heat and momentum between the surface and the boundary layer. To investigate this two-way interaction, a correct representation of lakes within regional climate models is essential. To this end, the one-dimensional lake parameterisation scheme FLake was recently coupled to the regional climate model COSMO-CLM (CCLM). One region where lakes constitute a key component of the climate system is the African Great Lakes region. In this study, the CCLM CORDEX-Africa evaluation simulation is dynamically downscaled from 0.44° (50 km) to 0.0625° (7 km) over East-Africa, an unprecedented resolution for this region. The performance of different CCLM configurations are compared for the period 1999-2008: in particular, CCLM is tested for its sensitivity to the choice of the lake surface temperature description (SST, FLake, an improved version of FLake and Hostetler) and the land surface model (Terra and Community Land Model). Model results are evaluated in a three-step procedure. First, the atmospheric state variables near-surface temperature, precipitation, surface energy fluxes, fractional cloud cover and column precipitable water are evaluated using in-situ based and satellite-derived products. Second, a comprehensive set of in-situ water temperature profile observations serves to evaluate the temporal evolution of water temperatures at three sites: Lake Kivu (Ishungu), Lake Tanganyika's northern basin (Kigoma) and southern basin (Mpulungu). Finally, spatial variability of surface temperatures in Lake Kivu and Lake Tanganyika are evaluated on the basis of satellite-derived lake surface temperatures. Subsequently, the preferred model configuration is used to quantify and understand effects by lakes reported for other regions in the world, such as a dampened diurnal temperature range, enhanced evaporation, modified surface layer stability, increased downwind precipitation, stronger winds, and the formation of local circulation patterns. Particular attention is payed to the impact of lakes on extreme night-time convection over Lake Victoria. This is achieved through comparison to a model integration excluding lake effects.

  15. A review of mercury in Lake Victoria, East Africa: implications for human and ecosystem health.

    PubMed

    Campbell, Linda; Dixon, D G; Hecky, R E

    2003-01-01

    Lake Victoria, East Africa, has been the site of many recent studies measuring mercury (Hg) concentrations in water, fish, sediment, soil, and humans. Most of these studies were motivated by concerns about Hg contamination from processing of gold ore on the southern shores. Total Hg (THg) concentrations in fish were usually below permissible World Health Organization (WHO) concentrations and international marketing limits and do not threaten the lucrative export industry. Nile perch 3-10 kg and most >10 kg had THg concentrations above the WHO threshold concentrations for at-risk groups (200 ng/g). Elevated THg concentrations in large Nile perch are not of major concern because Nile perch are rarely consumed by the people living on Lake Victoria and very large Nile perch are becoming increasingly rare in catches. Water THg concentrations were below Canadian drinking water guidelines but were elevated relative to those in the northern Great Lakes. Sediment and soil THg concentrations were within inter-national guidelines and are comparable to those in northern latitudes but are lower than those in the Amazon basin. Biomass burning and soil erosion are estimated to be the major sources of THg for the lake and probably constitute a larger source of THg than gold mining in Tanzania.THg concentrations in urine and hair from human volunteers indicate that while gold miners and frequent skin-bleaching cream users are at risk of inorganic mercury poisoning, the rest of the population, including fishermen, is not. Human exposure assessments demonstrated that fish consumption and soil geophagy constitute major sources of THg for humans, but the total estimated daily intake of THg was below the Health Canada tolerable daily intake (TDI) limits. The use of beauty creams containing high inorganic Hg concentrations, however, caused the estimated THg exposure to exceed the TDI. The high THg content in the hair of regular cream users supports this assessment. The nutritional benefits of fish and soil geophagy outweigh the risk of THg poisoning. Still, due to the importance of those natural items as a THg source to humans, as well as the changing nature of Lake Victoria, regular monitoring and risk assessments need to be carried out in the Lake Victoria catchment. PMID:12775518

  16. Palynological evidence of climate change and land degradation in the Lake Baringo area, Kenya, East Africa, since AD 1650

    E-print Network

    Liu, Kam-biu

    , reveal a largely dry environment in the East African region since AD 1650. The dry environment is punctuated by a succession of centennial- to decadal-scale wet and dry episodes, disjointed by sharp transitions, including two intense dry episodes that led to drying of the lake at ca. AD 1650 and AD 1720

  17. A comparative study of the macroinvertebrate communities in three oxbow lakes and the Brazos River in East Central Texas 

    E-print Network

    Lanza, Shirley Anne

    2003-01-01

    Macroinvertebrate communities of the Brazos River and three of its oxbow lakes, in East Central Texas, were sampled from the summer of 1994 to the spring of 1996. The floodplain for this area is predominantly nutrient-rich forested and agricultural...

  18. 33 CFR 165.T09-0452 - Safety Zone; Festivals & Fireworks Celebration, East Moran Bay, Lake Huron, St. Ignace, MI.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 CFR 165.7(a). The primary method of notification, however, will be through Broadcast Notice to... & Fireworks Celebration, East Moran Bay, Lake Huron, St. Ignace, MI. 165.T09-0452 Section 165.T09-0452... Limited Access Areas Ninth Coast Guard District § 165.T09-0452 Safety Zone; Festivals &...

  19. Ecosystem responses during Late Glacial period recorded in the sediments of Lake ?ukie (East Poland)

    NASA Astrophysics Data System (ADS)

    Zawiska, Izabela; S?owi?ski, Micha?; Correa-Metrio, Alex; Obremska, Milena; Luoto, Tomi; Nevalainen, Liisa; Woszczyk, Micha?; Milecka, Krystyna

    2014-05-01

    The main objectives of this study was to reconstruct climate impact on the functioning of Lake ?ukie and its catchment (??czna W?odawa Lake District, East European Plain) during Late Glacial period. In order to reconstruct climatic fluctuations and corresponding ecosystem responses, we analysed lake sediments for pollen, subfossil Cladocera, plant macrofossils and chemical composition of the sediment. Of these, plant macrofossils and Cladocera were used to infer minimum and mean July temperatures and ordination analysis was used to examine biotic community shifts. Multiproxy analyses of late-glacial sediments of Lake ?ukie clearly show that the main driver of aquatic and terrestrial ecosystems as well as geomorphological processes in the catchment was climate variation. The history of the lake initiated during the Older Dryas. In that period, ??czna W?odawa Lake District was covered by open habitats dominated by grasses (Poaceae), humid sites were occupied by tundra plant communities with less clubmoss (Selaginella selaginoides), dry sites by dominated by steppe-like vegetation with light-demanding species such as Helianthemum, Artemisia, Chenopodiaceae, and juniper bushes (Juniperus). Cold climate limited the growth and development of organisms in the lake, Cladocera community species composition was poor, with only few species present there all the time. During this time period, permafrost was still present in the ground limiting infiltration of rainwater and causing high erosion in the catchment area. Surface runoff is confirmed by the presence of sclerotia of Cenococcum geophilum and high terrigenous silica content. The warming of the early Allerød caused a remarkable change in the natural environment of this area. This is in accordance with the temperature rise reconstructed with the use of plant macrofossils though the Cladocera reconstruction did not recorded the rise than. This temperature increase resulted in turnover of vegetation in the catchment of Lake ?ukie, pioneer birch-pine forests dominated, later replaced by pine-birch forests. Consequently this limited the erosion. The results of all proxy suggest the water-lever rise in lake ?ukie. The Younger Dryas cooling in the region began about 12 630 14C years BP and recorded in significant drop in temperature reconstructed with plant macrofossils and Cladocera. The cooling resulted in a decline of forest communities and development of open habitats with grasses (Poaceae), Artemisia, and Chenopodiaceae), as well as juniper thickets (Juniperus) At the end of the Younger Dryas, plant communities changed, the non-arborescent pollen declined, while pollen of trees (especially Pinus) became more abundant. This change was more abruptly reflected in Cladocera and aquatic pollen results and is probably related to gradual climate warming. This study is a contribution to the Virtual Institute ICLEA (Integrated Climate and Landscape Evolution Analysis) funded by the Helmholtz Association, projects UMO-2011/01/B/ST10/07367 and N N306 036436 founded by National Science Center, Poland.

  20. A BAC library of the East African haplochromine cichlid fish Astatotilapia burtoni.

    PubMed

    Lang, Michael; Miyake, Tsutomu; Braasch, Ingo; Tinnemore, Deborah; Siegel, Nicol; Salzburger, Walter; Amemiya, Chris T; Meyer, Axel

    2006-01-15

    A BAC library was constructed from Astatotilapia burtoni, a haplochromine cichlid that is found in Lake Tanganyika, East Africa, and its surrounding rivers. The library was generated from genomic DNA of blood cells and comprises 96,768 individual clones. Its median insert size is 150 kb and the coverage is expected to represent about 14 genome equivalents. The coverage evaluation was based on genome size estimates that were obtained by flow cytometry. In addition, hybridization screens with five probes largely corroborate the above coverage estimate, although the number of clones ranged from 5 to 22 authenticated clones per single copy probe. The BAC library described here is expected to be useful to the scientific community interested in cichlid genomics as an important resource to gain new insights into the rapid evolution of the great species diversity of haplochromine cichlid fishes. PMID:16254984

  1. Mosaic maternal ancestry in the Great Lakes region of East Africa.

    PubMed

    Gomes, Verónica; Pala, Maria; Salas, Antonio; Álvarez-Iglesias, Vanesa; Amorim, António; Gómez-Carballa, Alberto; Carracedo, Ángel; Clarke, Douglas J; Hill, Catherine; Mormina, Maru; Shaw, Marie-Anne; Dunne, David W; Pereira, Rui; Pereira, Vânia; Prata, Maria João; Sánchez-Diz, Paula; Rito, Teresa; Soares, Pedro; Gusmão, Leonor; Richards, Martin B

    2015-09-01

    The Great Lakes lie within a region of East Africa with very high human genetic diversity, home of many ethno-linguistic groups usually assumed to be the product of a small number of major dispersals. However, our knowledge of these dispersals relies primarily on the inferences of historical, linguistics and oral traditions, with attempts to match up the archaeological evidence where possible. This is an obvious area to which archaeogenetics can contribute, yet Uganda, at the heart of these developments, has not been studied for mitochondrial DNA (mtDNA) variation. Here, we compare mtDNA lineages at this putative genetic crossroads across 409 representatives of the major language groups: Bantu speakers and Eastern and Western Nilotic speakers. We show that Uganda harbours one of the highest mtDNA diversities within and between linguistic groups, with the various groups significantly differentiated from each other. Despite an inferred linguistic origin in South Sudan, the data from the two Nilotic-speaking groups point to a much more complex history, involving not only possible dispersals from Sudan and the Horn but also large-scale assimilation of autochthonous lineages within East Africa and even Uganda itself. The Eastern Nilotic group also carries signals characteristic of West-Central Africa, primarily due to Bantu influence, whereas a much stronger signal in the Western Nilotic group suggests direct West-Central African ancestry. Bantu speakers share lineages with both Nilotic groups, and also harbour East African lineages not found in Western Nilotic speakers, likely due to assimilating indigenous populations since arriving in the region ~3000 years ago. PMID:26188410

  2. Regional assessment of lake ecological states using Landsat: A classification scheme for alkaline-saline, flamingo lakes in the East African Rift Valley

    NASA Astrophysics Data System (ADS)

    Tebbs, E. J.; Remedios, J. J.; Avery, S. T.; Rowland, C. S.; Harper, D. M.

    2015-08-01

    In situ reflectance measurements and Landsat satellite imagery were combined to develop an optical classification scheme for alkaline-saline lakes in the Eastern Rift Valley. The classification allows the ecological state and consequent value, in this case to Lesser Flamingos, to be determined using Landsat satellite imagery. Lesser Flamingos depend on a network of 15 alkaline-saline lakes in East African Rift Valley, where they feed by filtering cyanobacteria and benthic diatoms from the lakes' waters. The classification developed here was based on a decision tree which used the reflectance in Landsat ETM+ bands 2-4 to assign one of six classes: low phytoplankton biomass; suspended sediment-dominated; microphytobenthos; high cyanobacterial biomass; cyanobacterial scum and bleached cyanobacterial scum. The classification accuracy was 77% when verified against in situ measurements. Classified imagery and timeseries were produced for selected lakes, which show the different ecological behaviours of these complex systems. The results have highlighted the importance to flamingos of the food resources offered by the extremely remote Lake Logipi. This study has demonstrated the potential of high spatial resolution, low spectral resolution sensors for providing ecologically valuable information at a regional scale, for alkaline-saline lakes and similar hypereutrophic inland waters.

  3. Geomagnetic polarity epochs: new data from Olduvai Gorge, Tanganyika

    USGS Publications Warehouse

    Gromme, C.S.; Hay, R.L.

    1967-01-01

    The lower lava flow of Bed I in Olduvai Gorge, Tanganyika, carries natural remanent magnetization (NRM) having normal polarity. Thermal demagnetization experiments demonstrate the stability of this NRM. Thus the Olduvai geomagnetic polarity event, which was originally named from the upper lava flow in Bed I, is represented in its type locality by two normally magnetized lavas. These lavas have been shown to be 1.9 m.y. old, and although they are distinct from each other in composition and surface structure, their eruptions appear to have been closely spaced in time. ?? 1967.

  4. Bacterial diversity of the rock-water interface in an East Antarctic freshwater ecosystem, Lake Tawani(P)†

    PubMed Central

    2013-01-01

    Schirmacher Oasis is one of the few ice-free plateaus in East Antarctica that maintains a unique distribution of over 120 microbial-rich, dynamic freshwater lakes, most of which are unexplored. In this study, we describe the bacterial diversity of the rock-water interface in Lake Tawani(P) using culture-independent Bacterial Tag Encoded FLX Amplicon Pyrosequencing (bTEFAP), clone library construction, and culture-based analysis targeting the eubacterial 16S rRNA gene. Lake Tawani(P)was formed in a fossil valley by the accumulation of snow and glacial melt through surface channels into a low-catchment depression. Overall this lake exhibited thirteen bacterial phyla and one-hundred and twelve genera. The Qiime bioinformatics analysis on the bTEFAP alone exhibited higher coverage of the bacterial composition in Lake Tawani(P) than the clone library construction or culture-based methodology. Particularly due to the higher sensitivity of the bTEFAP approach, we detected and differentiated members of the phyla: Chloroflexi, Gemmatimonadetes, Planctomycetes, Nitrospira, and Candidate Division TM7 that other methods were unable to reveal. Nevertheless we found that the use of multiple approaches identified a more complete bacterial community than by using any single approach. Investigating the bacterial diversity of the Schirmacher Oasis lakes, especially those connected through surface channels and encompassed by valleys, will help unravel the dynamic nature of these unique seasonal, freshwater lakes, which potentially harbors highly adapted bacterial taxa with defined ecological functions. PMID:23369372

  5. Ontogenetic changes in isotopic signatures of an omnivorous fish Cultrichthys erythropterus in East Lake Taihu, China

    NASA Astrophysics Data System (ADS)

    Li, Yunkai; Zhang, Miao

    2015-05-01

    The relationship between body size and stable isotopic signatures of the omnivorous Redfin Culter ( Cultrichthys erythropterus), commonly found in East Lake Taihu, was investigated. Previous analyses of C. erythropterus stomach contents have shown that this species undergoes a diet switch from being predominantly zooplanktivorous to piscivorous during its life history. This was confirmed by stable carbon isotopic signature (?13C) in this study, in which ?13C was positively correlated with both standard length and weight. The importance of littoral-benthic resources in supporting C. erythropterus during its lifespan was also demonstrated using a two-source mixing model, the results of which showed a significant increasing trend in the contribution of littoral-benthic energy. However, the stable nitrogen isotopic signature (?15N) exhibited an unusual pattern compared with previous studies. The ?15N of C. erythropterus showed no relationship with body size, even though dietary changes were observed. This indicated that ?15N alone cannot fully reflect a diet shift in a species and possible variability in isotopic signatures over its life history. This should be considered when using stable isotopic signatures to investigate intra-specific variations and the timing of life-history events, such as estimating the trophic positions of fish species.

  6. Study of the Microbial Diversity of a Newly Discovered East Antarctic Freshwater Lake, L27C, and of a Perennially Ice-Covered Lake Untersee

    NASA Technical Reports Server (NTRS)

    Huang, Jonathan P.; Hoover, Richard B.; Andersen, Dale; Bej, Asim K.

    2010-01-01

    The microbial communities that reside within freshwater lakes of Schirmacher and Untersee Oases in East Antarctica must cope with extreme conditions that may include cold temperature, annual freeze-thaw cycles, exposure to UV radiation, especially during the austral summer months, low light beneath thick ice-cover, followed by seasonal darkness. The objective of this study was to assess the microbial biodiversity and distribution from samples taken from two freshwater lakes (L27C and Lake Untersee) that were collected during the Tawani 2008 International Antarctic Expedition that conducted research in this region of Antarctica. L27C is a small, previously unreported lake residing 2 km WNW of Maitri Station at Schirmacher Oasis. Biodiversity and distribution of microorganisms within the lake were studied using both culture-independent and culture-dependent methodologies based upon the analysis of eubacterial 16S rRNA gene sequences. Lake Untersee, a perennially ice-covered, ultra-oligotrophic, lake in the Otto-von-Gruber-Gebirge (Gruber Mountains) of central Dronning Maud Land was also sampled and the microbial diversity was analyzed by eubacterial 16S rRNA gene sequences derived from pure cultures. Direct culturing of water samples from each lake on separate R2A growth medium exhibited a variety of microorganisms including: Janthinobacterium, Hymenobacter, Sphingamonas, Subtercola, Deinococcus, Arthrobacter, Flavobacterium, Polaromonas, Rhodoferax and Duganella. The evaluation of samples from L27C through culture-independent methodology identified a rich microbial diversity consisting of six different phyla of bacteria. The culture-independent analysis also displayed the majority of bacteria (56%) belonged to the Class gamma-proteobacteria within the phylum Proteobacteria. Within the Class gamma-proteobacteria, Acinetobacter dominated (48%) the total microbial load. Overall, L27C exhibited 7 different phyla of bacteria and 20 different genera. Statistical analysis (Shannon-Weaver Diversity Index and Simpson Diversity Index) of the biodiversity of L27C displayed a moderately rich and diverse community. Investigations of the biodiversity and distribution of microorganisms in these lakes will help further our understanding of how the physical environment impact the structure and function within these microbially dominated ecosystems.

  7. Fish-community composition in Ouleout Creek, in the vicinity of East Sidney Lake, Delaware County, New York, 2000

    USGS Publications Warehouse

    Brightbill, R.A.; Bilger, M.D.

    2001-01-01

    The U.S. Army Corps of Engineers, Baltimore District, has been conducting biological surveys of the inflow and outflow streams of East Sidney Lake since the early 1980?s. These surveys are made to identify possible detrimental effects as well as benefits of the lake and to better understand the aquatic communities in the vicinity of the lake at the present and over time. The U.S. Army Corps of Engineers and the U.S. Geological Survey jointly conducted a survey of the fish communities upstream and downstream of the reservoir in Ouleout Creek in September 2000. The fish communities upstream and downstream were compared and any differences or similarities seen in the fish communities were noted. This study found the fish communities upstream and downstream of East Sidney Lake to be in good condition, with Index of Biotic Integrity (IBI) scores 4.5 upstream and 4.3 downstream. The habitat conditions of both reaches were of optimal quality, with a score of 18 upstream and 17 downstream as determined by use of the U.S. Environmental Protection Agency?s Rapid Bioassessment Protocols, and are capable of supporting fish communities. The Shannon Index was 2.95 upstream and 2.61 downstream of the lake, indicating that both reaches are slightly impacted by species richness and individual evenness among the species. Downstream, the dominant taxa was twice that of the co-dominant taxa. The Jaccards Coefficient and the Index of Similarity statistically shows these communities are similar, with scores of 0.76 and 0.86, respectively. Of the 19 species captured downstream, 16 of those also were captured upstream.

  8. Amplification of Warming at Tropical High Altitudes: Synthesis of East African Lacustrine and Moraine Archives with Paleoclimate Model Data

    NASA Astrophysics Data System (ADS)

    Loomis, S. E.; Russell, J. M.; Morrill, C.

    2014-12-01

    The amplitude of tropical paleotemperature variability on glacial/interglacial time scales has been hotly debated for decades, as sea surface temperature (SST) reconstructions from the tropics have repeatedly shown less warming than reconstructions from high elevations from the Last Glacial Maximum (LGM) to present. This debate is complicated by the fact that SST and high elevation reconstructions rely on different proxies, which inherently contain different errors and assumptions. Here we present a new equatorial paleotemperature record from Lake Rutundu, Mt. Kenya (3081 m above sea level) based on branched glycerol dialkyl glycerol tetraethers (GDGTs) and compare it to previously published East African GDGT temperature reconstructions at different elevations to assess the timing and amplitude of temperature changes with altitude. We find that the overall amplitude of warming in the Lake Rutundu record is 6.8±1.0°C from the LGM to the present, with mid-Holocene temperatures 1.6±0.9°C warmer than modern.By combining our Lake Rutundu record with three previously published GDGT temperature records from different elevations in East Africa (Sacred Lake, Lake Tanganyika, and Lake Malawi), we can calculate changes in lapse rates and freezing level heights (FLHs) through time. We find that lapse rates were steeper at the LGM (-7.4ºC/km) compared to the modern (-6.1ºC/km), likely due to widespread regional aridity at the LGM. FLHs were nearly 1000 m lower than they are today, which is supported by regional equilibrium line altitude (ELA) reconstructions from East African moraines. Patterns of altitudinal temperature variability and lapse rate changes reflect those from the TraCE-21 paleoclimate model, but amplitudes of model data variability are much smaller.

  9. Organic and mineral imprints in fossil photosynthetic mats of an East Antarctic lake.

    PubMed

    Lepot, K; Compère, P; Gérard, E; Namsaraev, Z; Verleyen, E; Tavernier, I; Hodgson, D A; Vyverman, W; Gilbert, B; Wilmotte, A; Javaux, E J

    2014-09-01

    Lacustrine microbial mats in Antarctic ice-free oases are considered modern analogues of early microbial ecosystems as their primary production is generally dominated by cyanobacteria, the heterotrophic food chain typically truncated due to extreme environmental conditions, and they are geographically isolated. To better understand early fossilization and mineralization processes in this context, we studied the microstructure and chemistry of organo-mineral associations in a suite of sediments 50-4530 cal. years old from a lake in Skarvsnes, Lützow Holm Bay, East Antarctica. First, we report an exceptional preservation of fossil autotrophs and their biomolecules on millennial timescales. The pigment scytonemin is preserved inside cyanobacterial sheaths. As non-pigmented sheaths are also preserved, scytonemin likely played little role in the preservation of sheath polysaccharides, which have been cross-linked by ether bonds. Coccoids preserved thylakoids and autofluorescence of pigments such as carotenoids. This exceptional preservation of autotrophs in the fossil mats argues for limited biodegradation during and after deposition. Moreover, cell-shaped aggregates preserved sulfur-rich nanoglobules, supporting fossilization of instable intracellular byproducts of chemotrophic or phototrophic S-oxidizers. Second, we report a diversity of micro- to nanostructured CaCO3 precipitates intimately associated with extracellular polymeric substances, cyanobacteria, and/or other prokaryotes. Micro-peloids Type 1 display features that distinguish them from known carbonates crystallized in inorganic conditions: (i) Type 1A are often filled with globular nanocarbonates and/or surrounded by a fibrous fringe, (ii) Type 1B are empty and display ovoid to wrinkled fringes of nanocrystallites that can be radially oriented (fibrous or triangular) or multilayered, and (iii) all show small-size variations. Type 2 rounded carbonates 1-2 ?m in diameter occurring inside autofluorescent spheres interpreted as coccoidal bacteria may represent fossils of intracellular calcification. These organo-mineral associations support organically driven nanocarbonate crystallization and stabilization, hence providing potential markers for microbial calcification in ancient rocks. PMID:25039968

  10. Environmental imbalance in salt lake Urmia, NW Iran: Anthropogenic and climate impact on the largest lake in the Middle East

    NASA Astrophysics Data System (ADS)

    Sharifi, A.; Pourmand, A.; Peterson, L. C.; Haeri-Ardakani, O.; Pourkerman, M.; Lahijani, H. A.

    2013-12-01

    Lake Urmia is located at the lowest area of a closed-continental drainage basin in NW Iran. At an elevation of 1267m (amsl), it is the third largest saline lake on earth. The geological setting of the lake is quite diverse and its drainage basin is comprised of a variety of rock formations with different ages, ranging from Precambrian metamorphic complexes to Holocene mud deposits. Since 1995, onsite measurements and satellite altimetry have shown that the mean annual lake level has progressively dropped by as much as nine meters. Although most of the water loss has been attributed to the imbalance in the net annual flux from seven tributaries that drain to the lake, the primary cause(s) of such a drastic change in lake level in a relatively short period remains a matter of considerable debate. While naturally occurring imbalances that cause abrupt climate change are favored by local authorities, poor water management regulations and excessive damming throughout the drainage basin seem to have played a significant role in the lake's drastic loss of water over the last few decades. Instrumental climate data from the past 60 years, which show 9-year cyclicity in regional mean air temperature, does not correspond with the drastic drop in the lake's water level. In addition, a recent study of shoreline changes over 50 years shows several major episodes of reduced lake surface area in years with the highest number of rainy days since 1995. These observations suggest that the progressive imbalance in water availability to the lake is more likely caused by anthropogenic activities, rather than regional climate variability. The human impact on the Lake Urmia environment is not limited to reduced water input; imbalance in evaporation and sedimentation patterns quickly followed construction of a dike-type causeway across Lake Urmia in the early 1980s. In order to study the long-term impact of potential forcing factor(s), we have generated a high-resolution, multi proxy record from a sediment core in the fringe of Lake Urmia that spans the last 9000 years. Variations in the relative abundances of conservative lithogenic elements, such as Al, Si and Ti measured by an Avaatech XRF core scanner reveal several high and low-frequency periodicities during most of the Holocene. While the low-frequency variations (1800- and 2800-year cycles) are indicative of potential solar and climate feedback controls, high-frequency variations, specifically at 11- and 22-years cyclicity over the last century, are consistent with changes in solar sunspot activity. These co-variations may indicate the potential influence of solar insolation on the regional climatic condition through relatively fast feedbacks. We do not, however, find any evidence of co-variation between sunspot activity and lake level fluctuations after 1995.

  11. East African megadroughts between 135 and 75 thousand years ago and bearing on early-modern human origins

    PubMed Central

    Scholz, Christopher A.; Johnson, Thomas C.; Cohen, Andrew S.; King, John W.; Peck, John A.; Overpeck, Jonathan T.; Talbot, Michael R.; Brown, Erik T.; Kalindekafe, Leonard; Amoako, Philip Y. O.; Lyons, Robert P.; Shanahan, Timothy M.; Castañeda, Isla S.; Heil, Clifford W.; Forman, Steven L.; McHargue, Lanny R.; Beuning, Kristina R.; Gomez, Jeanette; Pierson, James

    2007-01-01

    The environmental backdrop to the evolution and spread of early Homo sapiens in East Africa is known mainly from isolated outcrops and distant marine sediment cores. Here we present results from new scientific drill cores from Lake Malawi, the first long and continuous, high-fidelity records of tropical climate change from the continent itself. Our record shows periods of severe aridity between 135 and 75 thousand years (kyr) ago, when the lake's water volume was reduced by at least 95%. Surprisingly, these intervals of pronounced tropical African aridity in the early late-Pleistocene were much more severe than the Last Glacial Maximum (LGM), the period previously recognized as one of the most arid of the Quaternary. From these cores and from records from Lakes Tanganyika (East Africa) and Bosumtwi (West Africa), we document a major rise in water levels and a shift to more humid conditions over much of tropical Africa after ?70 kyr ago. This transition to wetter, more stable conditions coincides with diminished orbital eccentricity, and a reduction in precession-dominated climatic extremes. The observed climate mode switch to decreased environmental variability is consistent with terrestrial and marine records from in and around tropical Africa, but our records provide evidence for dramatically wetter conditions after 70 kyr ago. Such climate change may have stimulated the expansion and migrations of early modern human populations. PMID:17785420

  12. Distribution of Glycerol Diakyl Glycerol Tetraethers in Surface Soil and Crater Lake Sediments from Mount Kenya, East Africa

    NASA Astrophysics Data System (ADS)

    Omuombo, C.; Huguet, A.; Olago, D.; Williamson, D.

    2013-12-01

    Glycerol diakyl glycerol tetraethers (GDGTs), a palaeoclimate proxy based on the relative abundance of lipids produced by archaea and bacteria, is gaining wide acceptance for the determination of past temperature and pH conditions. This study looks at the spatial distribution and abundance of GDGTs in soil and sediment samples along an altitudinal transect from 3 crater lakes of Mt. Kenya (Lake Nkunga, Sacred Lake and Lake Rutundu) ranging in elevation from 1700m - 3080m above sea level. GDGTs were extracted with solvents and then analysed using high performance liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (HPLC/APCI-MS). Mean annual air temperature and pH were estimated based on the relative abundance of the different branched GDGTs, i.e. on the MBT (Methylation index of Branched Tetraethers) and CBT (Cyclization ratio of Branched Tetraethers) indices. Substantial amount of GDGTs were detected in both soil and sediment samples. In addition, branched GDGT distribution was observed to vary with altitude. These results highlight the importance of quantifying the branched GDGTs to understand the environmental parameters controlling the distribution of these lipids. The MBT/CBT proxy is a promising tool to infer palaeotemperatures and characterize the climate events of the past millennia in equatorial east Africa.

  13. Preliminary Results of a Multi-Proxy Lake Sediment Core Study in East-Central France

    NASA Astrophysics Data System (ADS)

    Misner, T.; Meyers, S.; Rosenmeier, M.; Strano, S.; Straffin, E.

    2008-12-01

    This paper presents the preliminary results of a multi-proxy study of natural and human-induced changes in the Burgundian environment, as recorded in the sediment geochemistry of three small freshwater basins within the Arroux River Valley, east-central France. Accelerator mass spectrometry radiocarbon dates constrain the age of core material collected from the basins, and indicate that these mill and farm ponds were constructed by at least 1200 A.D. The pond sediments are predominantly massive, organic-rich muds that contain discrete sand and gravel lenses likely related to episodic flooding and/or basin drainage. In this study, continuous X-ray fluorescence (XRF) scanning is used to quantify bulk geochemical variability throughout the lake sediment cores, and to investigate specific elemental proxies for paleoenvironmental change (detrital flux, biogenic flux, and redox state). The high-resolution XRF data are supplemented by sediment magnetic susceptibility measurements, and organic matter concentration as determined by loss on ignition. These records demonstrate a general increase in detrital sediment input from 1200 to 1300 A.D., during a period of known regional agricultural expansion. We infer these changes to be the consequence of increased catchment soil erosion and material flux to the water bodies. The data also suggest changes in mill and farm pond primary productivity, also related to soil erosion and changing transport of soil nutrients to the basins. Near the onset of the Little Ice Age (ca. 1500 A.D.) pond productivity reductions are apparent, likely indicating colder climates. These mill and farm pond sedimentary archives, in conjunction with historic records, can be used to better understand past land management strategies. Furthermore, historically documented landscape changes can be examined within the context of prevailing climatic conditions over the last ~800 years in an effort to establish future best management practices and the most sustainable land uses under future climate change scenarios. This has broad implications not only for local research, but also for the global community of researchers interested in understanding how the sediment record from freshwater basins can be used to interpret past (and predict future) human and environmental impacts on the landscape.

  14. Post-glacial paleoenvironments of the Lake Winnebago basin, east central Wisconsin, based on ostracodes

    SciTech Connect

    Fielder, R.F.; Smith, G.L.; Fitzgerald, T.M. . Dept. of Geology)

    1994-04-01

    Ostracodes were used to determine post-glacial paleoenvironments of the Lake Winnebago Basin. Following the retreat of the Wisconsinian Green Bay Lobe, Glacial Lake Oshkosh was dammed behind the ice sheet. As the modern Fox River was established, Glacial Lake Oshkosh shrank to form modern Lake Winnebago. Ostracodes were sampled from four vibracores in attempts to correlate sedimentary units and determine paleoenvironments. The oldest unit identified in their vibracores is grayish red clay that is thought to be reworked glacial till that was deposited in a lacustrine setting. This clay is dominated by Candona rawsoni, an ostracod species that prefers cold and deep water. The broken and eroded carapaces of the C. rawsoni in the greyish-red clay suggest reworking and transport, perhaps from the Lake Superior Basin. The contact between the clay and overlying sediments is an erosional unconformity, overlain in some places by gravel. The clay is overlain by coarsening-upward from sandy-silt to medium-grained sand, suggesting a decrease in lake levels and water depths. Raised shorelines 20 and 60 ft above present lake level constitute the geomorphic evidence for higher lake levels. Offshore, at depths of ten to twenty feet, the sediment type above is an olive black organic-rich mud where juveniles of C. rawsoni are the dominant species.

  15. Food web structure and mercury transfer in two contrasting Ugandan highland crater lakes (East Africa)

    E-print Network

    Dhindsa, Rajinder

    Africa) L. Campbell1 *, R. E. Hecky2 , D. G. Dixon2 and L. J. Chapman3,4 1 School of Environmental, and the mesotrophic Lake Nkuruba that is still sur- rounded by intact forest. The food web structures in these two are abbreviated, with only one to two trophic levels from primary consumers. The Lake Saka biota had distinctively

  16. Large subglacial lakes in East Antarctica at the onset of fast-flowing ice streams

    E-print Network

    Rempel, Alan W.

    98105-6698, USA. 500 1000 1,000 1,000 1500 1,500 1,500 1,500 1,500 2,000 2,000 2,000 2,000 2,500 2,500 2 lakes1 and rapidly drains, causing catastrophic floods2 . The exact mechanisms by which subglacial lakes

  17. Concentrations and risk assessment of polychlorinated biphenyls and polybrominated diphenyl ethers in surface sediments from the East Lake, China.

    PubMed

    Yun, Xiaoyan; Yang, Yuyi; Liu, Minxia; Wang, Jun

    2015-01-01

    The concentrations of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in surface sediment samples collected from the East Lake, China in winter 2012 and summer 2013 were analyzed in this study. The total PCB and PBDE concentrations ranged from not detected to 107.1 ng g(-1) dw and from 9.7 to 151.3 ng g(-1) dw, respectively. PCB-28, 101 and 180 were dominant congeners in both winter and summer. BDE-28 (44 %) was the dominant congener in winter and summer, followed by BDE-99 (28 %) and BDE-47 (26 %). The concentrations of PCBs in the sediment samples collected in summer were higher than those in winter, while the concentrations of PBDEs did not show much seasonal variations. Source analysis showed that the PCBs probably originated from urban runoff, industrial pollution and atmospheric deposition, and the PBDEs probably originated from historical usage of penta-BDE mixtures. Potential eco-toxicological risks caused by PCBs were found in about 5 % of the sampling sites; PBDEs had moderate eco-toxicological risk in 80 % sampling sites in the East Lake, China. PMID:25336043

  18. Distal tephras of the eastern Lake Victoria basin, equatorial East Africa: correlations, chronology and a context for early modern humans

    NASA Astrophysics Data System (ADS)

    Blegen, Nick; Tryon, Christian A.; Faith, J. Tyler; Peppe, Daniel J.; Beverly, Emily J.; Li, Bo; Jacobs, Zenobia

    2015-08-01

    The tephrostratigraphic framework for Pliocene and Early Pleistocene paleoanthropological sites in East Africa has been well established through nearly 50 years of research, but a similarly comprehensive framework is lacking for the Middle and particularly the Late Pleistocene. We provide the first detailed regional record of Late Pleistocene tephra deposits associated with artifacts or fossils from the Lake Victoria basin of western Kenya. Correlations of Late Pleistocene distal tephra deposits from the Wasiriya beds on Rusinga Island, the Waware beds on Mfangano Island and deposits near Karungu, mainland Kenya, are based on field stratigraphy coupled with 916 electron microprobe analyses of eleven major and minor element oxides from 50 samples. At least eight distinct distal tephra deposits are distinguished, four of which are found at multiple localities spanning >60 km over an approximately north to south transect. New optically stimulated luminescence dates help to constrain the Late Pleistocene depositional ages of these deposits. Our correlation and characterization of volcaniclastic deposits expand and refine the current stratigraphy of the eastern Lake Victoria basin. This provides the basis for relating fossil- and artifact-bearing sediments and a framework for ongoing geological, archaeological and paleontological studies of Late Pleistocene East Africa, a crucial time period for human evolution and dispersal within and out of Africa.

  19. Analogy between natural gas found in lakes of rift valley system of east Africa and its allied gas in Japan

    SciTech Connect

    Fukuta, O.

    1984-09-01

    The Afar triangle in northeastern Ethiopia is where the Red Sea rift, the Carlsberg Ridge of the Indian Ocean, and the Rift Valley system of east Africa meet. In 1979, J. Welhan and H. Craig reported that hydrothermal vents at 21/sup 0/N, on the East Pacific Rise, are discharging turbid waters. Mixtures of the plumes with ambient seawater contain significant amounts of dissolved H/sub 2/ and CH/sub 4/ as well as mantel-derived /sup 3/He-rich helium. The /sup 3/He//sup 4/He ratios of rock samples obtained earlier by J. Lupton and H. Craig from the Mid-Oceanic Ridge, including the Mid-Atlantic Ridge and the east Pacific Rise, are extremely high at an almost constant value of (1.3 +/- 0.2) x 10/sup -5/, which they defined as the MOR-type helium. However, the deep brines of the Red Sea contain about 1,000 times more methane than normal seawater does, according to Gold and Soter in 1980. Much evidence leads us to believe that large amounts of /sup 3/He-rich helium-bearing natural gas have been gushing out in many places of the Rift Valley of east Africa for a long time. In 1980, Gold and Soter stated that Lake Kivu, which occupies part of the East African rift valley, contains 50 million tons of dissolved methane for which there is no adequate microbial source. The Japanese Islands began to separate from the Asian continent during the early Miocene. The early Miocene was characterized by intensive volcanic activity that produced large amounts of pyroclastics and other volcanic rocks, generally called green tuff in Japan. It has been suggested that oil and gas in green tuff is derived from the upper mantle.

  20. Characterisation of the Subaquatic Groundwater Discharge That Maintains the Permanent Stratification within Lake Kivu; East Africa

    PubMed Central

    Ross, Kelly Ann; Gashugi, Elisée; Gafasi, Augustin; Wüest, Alfred; Schmid, Martin

    2015-01-01

    Warm and cold subaquatic groundwater discharge into Lake Kivu forms the large-scale density gradients presently observed in the lake. This structure is pertinent to maintaining the stratification that locks the high volume of gases in the deepwater. Our research presents the first characterisation of these inflows. Temperature and conductivity profiling was conducted from January 2010 to March 2013 to map the locations of groundwater discharge. Water samples were obtained within the lake at the locations of the greatest temperature anomalies observed from the background lake-profile. The isotopic and chemical signatures of the groundwater were applied to assess how these inflows contribute to the overall stratification. It is inferred that Lake Kivu’s deepwater has not been completely recharged by the groundwater inflows since its turnover that is speculated to have occurred within the last ~1000 yrs. Given a recent salinity increase in the lake constrained to within months of seismic activity measured beneath the basin, it is plausible that increased hydrothermal-groundwater inflows into the deep basin are correlated with episodic geologic events. These results invalidate the simple two-component end-member mixing regime that has been postulated up to now, and indicate the importance of monitoring this potentially explosive lake. PMID:25799098

  1. Ash from the Toba supereruption in Lake Malawi shows no volcanic winter in East Africa at 75 ka

    PubMed Central

    Lane, Christine S.; Chorn, Ben T.; Johnson, Thomas C.

    2013-01-01

    The most explosive volcanic event of the Quaternary was the eruption of Mt. Toba, Sumatra, 75,000 y ago, which produced voluminous ash deposits found across much of the Indian Ocean, Indian Peninsula, and South China Sea. A major climatic downturn observed within the Greenland ice cores has been attributed to the cooling effects of the ash and aerosols ejected during the eruption of the Youngest Toba Tuff (YTT). These events coincided roughly with a hypothesized human genetic bottleneck, when the number of our species in Africa may have been reduced to near extinction. Some have speculated that the demise of early modern humans at that time was due in part to a dramatic climate shift triggered by the supereruption. Others have argued that environmental conditions would not have been so severe to have such an impact on our ancestors, and furthermore, that modern humans may have already expanded beyond Africa by this time. We report an observation of the YTT in Africa, recovered as a cryptotephra layer in Lake Malawi sediments, >7,000 km west of the source volcano. The YTT isochron provides an accurate and precise age estimate for the Lake Malawi paleoclimate record, which revises the chronology of past climatic events in East Africa. The YTT in Lake Malawi is not accompanied by a major change in sediment composition or evidence for substantial temperature change, implying that the eruption did not significantly impact the climate of East Africa and was not the cause of a human genetic bottleneck at that time. PMID:23630269

  2. Provenance, age, and environment of mid-Wisconsinan slackwater lake sediment in the St. Louis Metro East area, USA

    USGS Publications Warehouse

    Curry, B. Brandon; Grimley, D.A.

    2006-01-01

    Valleys tributary to the Mississippi River contain fossiliferous slackwater lake sediment (Equality Formation) deposited in response to aggradation of the Mississippi River valley during the last glaciation. In the St. Louis Metro East area, the lower part of the Equality Formation is primarily laminated, fossiliferous silt and clay deposited from about 44,150 to 24,310 14C yr B.P. The upper Equality Formation is primarily very fine sand to silt deposited from about 21,200 to 17,000 14C yr B.P. Among the four cores that sample this succession in the St. Louis Metro East area, core MNK-3 (38.64EN, 90.01EW) was selected for detailed study. Three sources are distinguished by the following characteristics: (1) gray smectite-quartz-Se-rich, feldspar-poor material of the Des Moines, Wadena, and James lobes; (2) reddish brown kaolinite-Cu-Fe-rich sediment of the Superior and Rainy lobes; and (3) brown illite-dolomite-Sr-rich sediment of the Lake Michigan and Green Bay lobes. The earliest sediments (44,150 to 41,700 14C yr B.P.) were derived from the central and western provenances and are chronocorrelative with the lower Roxana Silt. A hiatus occurred from about 41,700 to 29,030 14C yr B.P. when much of the middle Roxana Silt (Meadow Member) was deposited on adjacent uplands. The youngest sediment includes evidence of heightened activity of the Superior Lobe at about 29,000 14C yr B.P., the Lake Michigan and Green Bay lobes from about 25,000 to 24,000 14C yr B.P., and the Wadena-Des Moines-James lobes at about 21,000 14C yr B.P. ?? 2005 Society. Published by University of Washington. All rights reserved.

  3. Molecular records of climate variability and vegetation response since the Late Pleistocene in the Lake Victoria basin, East Africa

    NASA Astrophysics Data System (ADS)

    Berke, Melissa A.; Johnson, Thomas C.; Werne, Josef P.; Grice, Kliti; Schouten, Stefan; Sinninghe Damsté, Jaap S.

    2012-11-01

    New molecular proxies of temperature and hydrology are helping to constrain tropical climate change and elucidate possible forcing mechanisms during the Holocene. Here, we examine a ˜14,000 year record of climate variability from Lake Victoria, East Africa, the world's second largest freshwater lake by surface area. We determined variations in local hydroclimate using compound specific ?D of terrestrial leaf waxes, and compared these results to a new record of temperature utilizing the TEX86 paleotemperature proxy, based on aquatic Thaumarchaeotal membrane lipids. In order to assess the impact of changing climate on the terrestrial environment, we generated a record of compound specific ?13C from terrestrial leaf waxes, a proxy for ecosystem-level C3/C4 plant abundances, and compared the results to previously published pollen-inferred regional vegetation shifts. We observe a general coherence between temperature and rainfall, with a warm, wet interval peaking ˜10-9 ka and subsequent gradual cooling and drying over the remainder of the Holocene. These results, particularly those of rainfall, are in general agreement with other tropical African climate records, indicating a somewhat consistent view of climate over a wide region of tropical East Africa. The ?13C record from Lake Victoria leaf waxes does not appear to reflect changes in regional climate or vegetation. However, palynological analyses document an abrupt shift from a Poaceae (grasses)-dominated ecosystem during the cooler, arid late Pleistocene to a Moraceae-dominated (trees/shrubs) landscape during the warm, wet early Holocene. We theorize that these proxies are reflecting vegetation in different locations around Lake Victoria. Our results suggest a predominantly insolation-forced climate, with warm, wet conditions peaking at the maximum interhemispheric seasonal insolation contrast, likely intensifying monsoonal precipitation, while maximum aridity coincides with the rainy season insolation and the interhemispheric contrast gradient minima. We interpret a shift in conditions at the Younger Dryas to indicate a limited switch in insolation-dominated control on climate of the Lake Victoria region, to remote teleconnections with the coupled Atlantic and Pacific climate system.

  4. Seasonal variations in geochemistry of the hyperacidic Ijen Crater Lake, East Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Sumarti, S.; Sumarti, S.; van Bergen, M. J.; Takano, B.; Sukarnen, S.

    2001-12-01

    Kawah Ijen is a typical crater lake in a tropical climate where there is a balance between the volume of atmospheric precipitation and the level of water in the lake. The crater lake has a regular oval form (600 x 1000 m2), is 180 m deep, and contains about 36 million m3 of turquoise-green colored water (pH ~ 0.2). The water contains extremely high Cl, SO4, F concentrations, the maximum values being about 2,500 mg/kg, 80,000 mg/kg and 1,300 mg/kg respectively. Twenty-four samples of lake water taken during August 1996 (dry season) show most major elements to be homogeneously distributed throughout the lake at this time to a depth of 165 m within a standard deviation of less than 10 %. Homogeneity is most likely due to thorough mixing driven by thermal convection. However, iron and sulphur do not behave in the same way showing variations up to 14 % variation. Monthly monitoring of surface water (1997-2001) shows temporal fluctuations in acidity (pH 0 ~ 0.6) and water level, concentrations of major elements, temperature (20 ~ 45° C). Between 1976-1996, the water level varied by ~ 15 m; and from 1997-2001 by ~ 10 m. The onset of the wet season may coincide with an episodical decrease, a spike, in major element concentrations up to 70 % of their dry season value. This spike occurs annually at the lowest temperature and highest degree of dilution, indicates of the influence of rainfall. However, volcanic gases entering beneath the lake bottom may have added to these temporal changes in the lake especially during phreatic eruptions. Shallow earthquake records do not indicate correlations between seismic activity and chemical changes in the lake. Temporal variations of lake surface temperature show good agreement with major element variations in surface water. Crater lake surface water collected at three points on August 1996, March 2001, May 2001 revealed that the surface water was homogenous in the dry and rainy season within a standard deviation below 7 %. The geochemical and seasonal variations in the lake are important in assessing the environmental impact of acidic water that drains in to the Banyupahit-Banyuputih River, particularly in the Asembagus area (40 km from the lake) where the water is used for irrigation. The fluoride level in the 55 well water samples was high. In 50 % of the samples it was above the 1.5 mg/kg limit recommended by the World Health Organization (WHO). Ratios of B/F, B\\Cl, B/SO4 as conservative elements indicate that Banyuputih River contaminates the groundwater.

  5. Biogeochemistry of a large and deep tropical lake (Lake Kivu, East Africa: insights from a stable isotope study covering an annual cycle

    NASA Astrophysics Data System (ADS)

    Morana, C.; Darchambeau, F.; Roland, F. A. E.; Borges, A. V.; Muvundja, F.; Kelemen, Z.; Masilya, P.; Descy, J.-P.; Bouillon, S.

    2015-08-01

    During this study, we investigated the seasonal variability of the concentration and the stable isotope composition of several inorganic and organic matter (OM) reservoirs in the large, oligotrophic and deep tropical Lake Kivu (East Africa). Data were acquired over 1 year at a fortnightly temporal resolution. The ?13C signature of the dissolved inorganic carbon (DIC) increased linearly with time during the rainy season, then suddenly decreased during the dry season due to vertical mixing with 13C-depleted DIC waters. The ?13C signature of the particulate organic carbon pool (POC) revealed the presence of a consistently abundant methanotrophic biomass in the oxycline throughout the year. We also noticed a seasonal shift during the dry season toward higher values in the ?15N of particulate nitrogen (PN) in the mixed layer and ?15N-PN was significantly related to the contribution of cyanobacteria to the phytoplankton assemblage, suggesting that rainy season conditions could be more favourable to atmospheric nitrogen-fixing cyanobacteria. Finally, zooplankton were slightly enriched in 13C compared to the autochthonous POC pool, and the ?15N signature of zooplankton followed well the seasonal variability in ?15N-PN, consistently 3.0 ± 1.1 ‰ heavier than the PN pool. Together, ?13C and ?15N analysis suggests that zooplankton directly incorporate algal-derived OM in their biomass, and that they rely almost exclusively on this source of OM throughout the year in general agreement with the very low allochthonous OM inputs from rivers in Lake Kivu.

  6. Reproductive success of barn swallows nesting near a selenium-contaminated lake in east Texas, USA

    USGS Publications Warehouse

    King, K.A.; Custer, T.W.; Weaver, D.A.

    1994-01-01

    Reproductive success and contaminant levels in 1986 and 1987 were compared between Barn Swallows nesting at selenium-contaminated Martin Lake, Texas, USA, and swallows nesting at a reference site. Nests were initiated about the same time or earlier at Martin Lake than at the reference site and clutch size was similar between the two locations. Nest success was significantly higher a Martin Lake than at the reference site and no embryo or chick deformities were documented. Selenium concentrations in 14 of 20 eggs from Martin Lake were above background ( gt 3 ppm, dry weight); two of 20 eggs contained gt 5 ppm, a concentration associated with a 20% embryo mortality/deformity rate in some bird species. Selenium concentrations in the kidneys of adult swallows were higher at Martin Lake (mean = 14 ppm dry weight) than at the reference site (5.8 ppm). DDE, the only detected organochlorine compound, was in two of 10 eggs from Martin Lake; these concentrations were below those associated with chronic poisoning and reproductive problems. The maximum mercury concentration in livers of adult Barn Swallows (0.83 ppm, dry weight) was within the range for background levels ( lt 5 ppm).

  7. Reproductive success of barn swallows nesting near a selenium-contaminated lake in east Texas, USA

    USGS Publications Warehouse

    King, K.A.; Custer, T.W.; Weaver, D.A.

    1994-01-01

    Reproductive success and contaminant levels in 1986 and 1987 were compared between Barn Swallows nesting at selenium-contaminated Martin Lake, Texas, USA, and swallows nesting at a reference site. Nests were initiated about the same time or earlier at Martin Lake than at the reference site and clutch size was similar between the two locations. Nest success was significantly higher at Martin Lake than at the reference site and no embryo or chick deformities were documented. Selenium concentrations in 14 of 20 eggs from Martin Lake were above background (> 3 ppm, dry weight); two of 20 eggs contained > 5 ppm, a concentration associated with a 20% embryo mortality/deformity rate in some bird species. Selenium concentrations in the kidneys of adult swallows were higher at Martin Lake (mean = 14 ppm dry weight) than at the reference site (5.8 ppm). DDE, the only detected organochlorine compound, was in two of 10 eggs from Martin Lake; these concentrations were below those associated with chronic poisoning and reproductive problems. The maximum mercury concentration in livers of adult Barn Swallows (0.83 ppm, dry weight) was within the range for background levels (< 5 ppm).

  8. Biogeochemistry of a large and deep tropical lake (Lake Kivu, East Africa): insights from a stable isotope study covering an annual cycle

    NASA Astrophysics Data System (ADS)

    Morana, C.; Darchambeau, F.; Roland, F. A. E.; Borges, A. V.; Muvundja, F.; Kelemen, Z.; Masilya, P.; Descy, J.-P.; Bouillon, S.

    2014-12-01

    During this study, we investigated the seasonal variability of the concentration and the stable isotope composition of several inorganic and organic matter reservoirs in the large, oligotrophic and deep tropical Lake Kivu (East Africa). Data were acquired during one year at a fornightly temporal resolution. The ?13C signature of the dissolved inorganic carbon (DIC) increased linearly with time during the rainy season, then suddenly decreased during the dry season due to vertical mixing with ?13C-depleted DIC waters. This pattern reflects the net autotrophic status of the mixed layer of Lake Kivu, contrary to the common observation that oligotrophic aquatic ecosystems tend to be net heterotrophic. The ?13C signature of the particulate organic carbon pool (POC) revealed the presence of a consistently abundant methanotrophic biomass in the oxycline throughout the year. We also noticed a seasonal shift during the dry season toward higher values in the ?15N of particulate nitrogen (PN) in the mixed layer and ?15N-PN was significantly related to the contribution of cyanobacteria to the phytoplankton assemblage, suggesting that rainy season conditions could be more favourable to atmospheric nitrogen-fixing cyanobacteria. Finally, zooplankton were slightly enriched in ?13C compared to the autochtonous POC pool, and the ?15N signature of zooplankton followed well the seasonal variability in ?15N-PN, being consistently 3.0 ± 1.1‰ heavier than the PN pool. Together, ?13C and ?15N analysis suggests that zooplankton directly incorporate algal-derived organic matter in their biomass, and they would rely almost exclusively on this source of organic matter throughout the year in general agreement with the very low allochthonous organic matter inputs from rivers in Lake Kivu.

  9. High-latitude environmental change during MIS 9 and 11: biogeochemical evidence from Lake El'gygytgyn, Far East Russia

    NASA Astrophysics Data System (ADS)

    D'Anjou, R. M.; Wei, J. H.; Castañeda, I. S.; Brigham-Grette, J.; Petsch, S. T.; Finkelstein, D. B.

    2013-03-01

    Marine isotope stages (MIS) 11 has been proposed as an analog for the present interglacial; however, terrestrial records of this time period are rare. Sediments from Lake El'gygytgyn (67°30' N, 172°5' E) in Far East Russia contain a 3.56 Ma record of climate variability from the Arctic. Here, we present the first terrestrial Arctic reconstruction of environmental and climatic changes from MIS 8 through 12 (289 to 464 ka) using organic geochemical proxies. Terrestrial vegetation changes, as revealed by plant leaf wax (n-alkane) indices and concentrations of arborinol (a biomarker for trees), show increased tree cover around the lake during interglacial periods, with higher concentrations observed during MIS 11 as compared to MIS 9. A similar pattern is also observed in records of aquatic productivity revealed by molecular indicators from dinoflagellates (dinosterol), eustigmatophyte algae (long-chain (C28-C32) 1, 15 n-alkyl diols) in addition to short-chain n-alkanes, where aquatic productivity is highest during MIS 11. Changes recorded in these molecular proxies show a similar structure to relative temperature variability as recorded by the MBT/CBT (Methylation of Branched Tetraether/Cyclization of Branched Tetraether) paleothermometer, based on branched glycerol dialkyl glycerol tetraethers (GDGTs). Additionally, relative MBT/CBT temperature changes generally track pollen and diatom ?18O temperature estimates, compiled by other studies, which suggest glacial-interglacial temperature changes of ~ 9 to 12 °C. These records of environmental and climatic change indicate Arctic sensitivity to external forcings such as orbital variability and atmospheric greenhouse gas concentrations. Overall, this study indicates that organic geochemical analyses of the Lake El'gygytgyn sediment archive can provide critical insight into the response of lake ecosystems and their sensitivity in high latitude regions.

  10. High-latitude environmental change during MIS 8-12: biogeochemical evidence from Lake El'gygytgyn, Far East Russia

    NASA Astrophysics Data System (ADS)

    D'Anjou, R. M.; Wei, J. H.; Castañeda, I. S.; Brigham-Grette, J.; Petsch, S. T.; Finkelstein, D. B.

    2012-09-01

    Marine Isotope Stages (MIS) 11 has been proposed as an analog for the present interglacial; however, terrestrial records of this time period are rare. Sediments from Lake El'gygytgyn (67°30´ N, 172°5´ E) in Far East Russia contain a 3.56 Ma record of climate variability from the Arctic. Here, we present an organic geochemical reconstruction of environmental and climatic changes from MIS 8 through 12 (289 to 460 ka). Terrestrial vegetation changes, as revealed by plant leaf wax (n-alkane) indices and concentrations of arborinol (a biomarker for trees), show increased tree cover around the lake during interglacial periods, with higher concentrations observed during MIS 11 as compared to MIS 9. A similar pattern is also observed in records of aquatic productivity revealed by molecular indicators from dinoflagellates (dinosterol), eustigmatophyte algae (long-chain (C28-C32) 1,15 n-alkyl diols) in addition to short-chain nalkanes, where aquatic productivity is highest during MIS 11. Changes recorded in these molecular proxies track relative temperature variability as recorded by the MBT/CBT paleothermometer, based on branched glycerol dialkyl glycerol tetraethers (GDGTs). Additionally, relative MBT/CBT temperature changes generally track pollen and diatom ?18O temperature estimates, compiled by other studies, which suggest glacial-interglacial temperature changes of ~ 9-12 °C. These records of environmental and climatic change indicate Arctic sensitivity to external forcings such as orbital variability and atmospheric greenhouse gas concentrations. Overall, this study indicates that organic geochemical analyses of the Lake El'gygytgyn sediment archive can provide critical insight into the response of lake ecosystems and their sensitivity in high latitude regions.

  11. GENE EXPRESSION ALTERATIONS OBSERVED IN PRIMARY CULTURED RAT HEPATOCYTES AFTER TREATMENT WITH CHLORINATED OR CHLORINATED AND OZONATED DRINKING WATER FROM EAST FORK LAKE, OHIO

    EPA Science Inventory

    Drinking water from East Fork Lake was spiked with iodide and bromide, disinfected with chlorine or ozone + chlorine, concentrated ~100-fold using reverse osmosis, and volatile disinfection by-products (DBPs) added back. Primary rat hepatocytes were exposed to full-strength, 1:10...

  12. Distribution of Cr, Pb, Cd, Zn, Fe and Mn in Lake Victoria sediments, East Africa

    SciTech Connect

    Onyari, J.M.; Wandiga, S.O. )

    1989-06-01

    The presence of many metals at trace or ultra-trace levels in the human environment has received increased global attention. Sediments as a sink for pollutants are widely recognized pollution sources and diagenesis and biochemical transformations within the sediment may mobilize pollutants posing a threat to a wider biological community. The natural (background) concentrations of heavy metals in lake sediments can be estimated either by analysis of surface sediments in non-polluted regions or by analysis of core samples antedating modern pollution. The distribution pattern of heavy metals in tropical freshwater systems has been little studied. The authors found increased concentrations of lead and other trace metals in Lake Victoria. Thus this study was initiated in order to further investigate the distribution patterns of lead and other metals in Lake Victoria.

  13. Holistic view to integrated climate change assessment and extreme weather adaptation in the Lake Victoria Basin East Africa

    NASA Astrophysics Data System (ADS)

    Mutua, F.; Koike, T.

    2013-12-01

    Extreme weather events have been the leading cause of disasters and damage all over the world.The primary ingredient to these disasters especially floods is rainfall which over the years, despite advances in modeling, computing power and use of new data and technologies, has proven to be difficult to predict. Also, recent climate projections showed a pattern consistent with increase in the intensity and frequency of extreme events in the East African region.We propose a holistic integrated approach to climate change assessment and extreme event adaptation through coupling of analysis techniques, tools and data. The Lake Victoria Basin (LVB) in East Africa supports over three million livelihoods and is a valuable resource to five East African countries as a source of water and means of transport. However, with a Mesoscale weather regime driven by land and lake dynamics,extreme Mesoscale events have been prevalent and the region has been on the receiving end during anomalously wet years in the region. This has resulted in loss of lives, displacements, and food insecurity. In the LVB, the effects of climate change are increasingly being recognized as a significant contributor to poverty, by its linkage to agriculture, food security and water resources. Of particular importance are the likely impacts of climate change in frequency and intensity of extreme events. To tackle this aspect, this study adopted an integrated regional, mesoscale and basin scale approach to climate change assessment. We investigated the projected changes in mean climate over East Africa, diagnosed the signals of climate change in the atmosphere, and transferred this understanding to mesoscale and basin scale. Changes in rainfall were analyzed and similar to the IPCC AR4 report; the selected three General Circulation Models (GCMs) project a wetter East Africa with intermittent dry periods in June-August. Extreme events in the region are projected to increase; with the number of wet days exceeding the 90% percentile of 1981-2000 likely to increase by 20-40% in the whole region. We also focused on short-term weather forecasting as a step towards adapting to a changing climate. This involved dynamic downscaling of global weather forecasts to high resolution with a special focus on extreme events. By utilizing complex model dynamics, the system was able to reproduce the Mesoscale dynamics well, simulated the land/lake breeze and diurnal pattern but was inadequate in some aspects. The quantitative prediction of rainfall was inaccurate with overestimation and misplacement but with reasonable occurrence. To address these shortcomings we investigated the value added by assimilating Advanced Microwave Scanning Radiometer (AMSR-E) brightness temperature during the event. By assimilating 23GHz (sensitive to water) and 89GHz (sensitive to cloud) frequency brightness temperature; the predictability of an extreme rain weather event was investigated. The assimilation through a Cloud Microphysics Data Assimilation (CMDAS) into the weather prediction model considerably improved the spatial distribution of this event.

  14. Geochemistry of Archean alkalic volcanic rocks from the Crystal Lake area, east of Kirkland Lake, Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Ujike, Osamu

    1985-05-01

    Twelve samples of Timiskaming volcanics from the Crystal Lake area were analyzed for major and trace elements (Ta, Th, Zr, Hf, V, Cr, Sc, rare earth elements (REE), Y, etc.) by X-ray fluorescence and instrumental neutron activation analysis techniques. The samples, which include mafic trachytes, trachytes and leucite trachytes, represent several batches of Archean alkalic magmas differentiated at shallow depths. The Cr/Sc sbnd Cr systematics and REE, Zr sbnd Th and Zr sbnd Y characteristics show, however, that their primary magmas generated at great depths in the "enriched" mantle where garnet remained in the refractory residue of partial melt. The chemical similarity between the Timiskaming samples and modern alkalic rocks in mature volcanic arcs strongly implies that the Timiskaming volcanism represents the last stage of a late Archean island arc volcanism present in the southwestern Abitibi Belt, Superior Province. The occurrence of Timiskaming-type alkalic rocks is not rare in Archean greenstone belts, thereby suggesting that a tectonic setting similar to modern volcanic arc system might have been common in late Archean time.

  15. Lake

    ERIC Educational Resources Information Center

    Wien, Carol Anne

    2008-01-01

    The lake is blue black and deep. It is a glaciated finger lake, clawed out of rock when ice retracted across Nova Scotia in a northerly direction during the last ice age. The lake is narrow, a little over a mile long, and deep, 90 to 190 feet in places according to local lore, off the charts in others. The author loves to swim there, with a sense…

  16. The case study of drillbit and borehole frozen water of the subglacial Lake Vostok, East Antarctica for microbial content

    NASA Astrophysics Data System (ADS)

    Bulat, Sergey; Doronin, Maxim; Dominique, Marie; Lipenkov, Vladimir; Lukin, Valery; Karlov, Denis; Demchenko, Leonid; Khilchenko, Margarita

    The objective was to estimate microbial content and diversity in the subglacial Lake Vostok (buried beneath 4-km thick East Antarctic ice sheet) by studying the uppermost water layer which entered the borehole upon lake entry (February 5, 2012) and then shortly frozen within. The samples of so-called drillbit water frozen on a drill bit upon lake enter (RAE57) along with re-drilled so-called borehole-frozen water (RAE58) were provided for the study with the ultimate goal to discover the life in this extreme icy environment. The comprehensive analyses (constrained by Ancient DNA research criteria) of the first lake water samples - drillbit- (one sample) and borehole-frozen (3 different depths 5G-2N-3425, 3429 et 3450m), are nearly got finished. If the drillbit water sample was heavily polluted with drill fluid (at ratio 1:1), re-drilled borehole-frozen samples were proved to be rather clean but still strongly smelling kerosene and containing numerous micro-droplets of drill fluid making the ice non-transparent. The cell concentrations measured by flow cytofluorometry showed 167 cells per ml in the drillbit water sample while in borehole-frozen samples ranged from 5.5 (full-cylinder 3429m deep frozen water ice core) to 38 cells per ml (freeze-centre of 3450m deep moon-shape ice core). DNA analyses came up with total 44 bacterial phylotypes discovered by sequencing of different regions (v3-v5, v4-v8, v4-v6 et full-gene) of 16S rRNA genes. Amongst them all but two were considered to be contaminants (were present in our contaminant library, including drill fluid findings). The 1st remaining phylotype successfully passing all contamination criteria proved to be hitherto-unknown type of bacterium (group of clones, 3 allelic variants) showing less than 86% similarity with known taxa. Its phylogenetic assignment to bacterial divisions or lineages was also unsuccessful despite of the RDP has classified it belonging to OD1 uncultured Candidate Division. The 2nd phylotype was less remarkable and still dubious in terms of contamination. It was presented by just one clone and showed 93% similarity with Janthinobacterium sp of Oxalobacteraceae (Beta-Proteobacteria) - well-known ‘water-loving’ bacteria. No archaea were detected in lake water frozen samples. Thus, the unidentified and unclassified bacterial w123-10 phylotype for the first time discovered in the uppermost water layer in subglacial Lake Vostok might represent ingenious cell populations in the lake, making the life in the lake less elusive. The proof may come (as well as novel phylotype discoveries) with farther analyses (e.g., sample screening with w123-10-specific primers, 16S rRNA v4 region amplicon sequencing) of existing and newly requested moon-shape samples of borehole-frozen water which are on a way to laboratories. We are deeply grateful to Jean Robert Petit and Jean Martins, UJF-CNRS, Grenoble (France) for assistance in conducting some analyses.

  17. Hydrology of the Wolf Branch sinkhole basin, Lake County, east-central Florida

    USGS Publications Warehouse

    Schiffer, D.M.

    1996-01-01

    A 4-year study of the hydrology of the Wolf Branch sinkhole basin in Lake County, Florida, was conducted from 1991-95 by the U.S. Geological Survey to provide information about the hydrologic characteristics of the drainage basin in the vicinity of Wolf Sink. Wolf Branch drains a 4.94 square mile area and directly recharges the Upper Floridan aquifer through Wolf Sink. Because of the direct connection of the sinkhole with the aquifer, a contaminant spill in the basin could pose a threat to the aquifer. The Wolf Branch drainage basin varies in hydrologic characteristics from its headwaters to its terminus at Wolf Sink. Ground- water seepage provides baseflow to the stream north of Wolf Branch Road, but the stream south of State Road 46 is intermittent and the stream can remain dry for months. A single culvert under a railroad crossing conducts flow from wetlands just south of State Road 46 to a well-defined channel which leads to Wolf Sink. The basin morphology is characterized by karst terrain, with many closed depressions which can provide intermittent surface-water storage. Wetlands in the lower third of the basin (south of State Road 46) also provide surface water storage. The presence of numerous water-control structures (impoundments, canals, and culverts), and the surface-water storage capacity throughout the basin affects the flow characteristics of Wolf Branch. Streamflow records for two stations (one above and one below major wetlands in the basin) indicate the flow about State Road 46 is characterized by rapid runoff and continuous baseflow, whereas below State Road 46, peak discharges are much lower but of longer duration than at the upstream station. Rainfall, discharge, ground-water level, and surface-water level data were collected at selected sites in the basin. Hydrologic conditions during the study ranged from long dry periods when there was no inflow to Wolf Sink, to very wet periods, as when nearly 7 inches of rain fell in a 2-day period in November 1994, following an extended wet season. A comparison to long-term rainfall record (40 years) indicates that this range in hydrologic conditions during the 4-year study is representative of the range of conditions expected during a much longer time period. Two dye-trace studies conducted during the study indicated no direct connections between the sink and local wells. The path of a constituent entering the aquifer through Wolf Sink generally would be to the east, following the gradient of the regional ground-water flow system. The conductance of Wolf Sink (the rate at which the sink conducts water to the underlying aquifer) was estimated from streamflow data, ground-water levels, and water levels in Wolf Sink. The range of hydrologic conditions during the study provided a basis for the determination of a representative conductance value. The regression of streamflow as a function of head difference between the sink water level and the potentiometric surface at an observation well (an approximation of the potentiometric level beneath Wolf Sink) resulted in a significant relation r2=0.91, mean square error = 1.60 cubic feet per second); and the slope of the regression line, representing sink conductance, was 1.48 cubic feet per second per foot of head difference. Flow and storm-volume frequency curves for selected time periods (1-day, 7-days, 14-days, 21-days, and 30-days) were generated based on streamflow data from January 10, 1992, to September 30, 1995. These curves indicate that, based on the available record, the volume of water that would have to be stored (in the event that streamflow had to be diverted from Wolf Sink) during a 30-day period would be equal to or less than about 11 acre-fee 30 percent of the time and 161 acre-feet 80 percent of the time. The maximum volume that would be generated during a 30-day period, based on this study, would be about 570 acre-feet.

  18. Genomic islands of speciation separate cichlid ecomorphs in an East African crater lake.

    PubMed

    Malinsky, Milan; Challis, Richard J; Tyers, Alexandra M; Schiffels, Stephan; Terai, Yohey; Ngatunga, Benjamin P; Miska, Eric A; Durbin, Richard; Genner, Martin J; Turner, George F

    2015-12-18

    The genomic causes and effects of divergent ecological selection during speciation are still poorly understood. Here we report the discovery and detailed characterization of early-stage adaptive divergence of two cichlid fish ecomorphs in a small (700 meters in diameter) isolated crater lake in Tanzania. The ecomorphs differ in depth preference, male breeding color, body shape, diet, and trophic morphology. With whole-genome sequences of 146 fish, we identified 98 clearly demarcated genomic "islands" of high differentiation and demonstrated the association of genotypes across these islands with divergent mate preferences. The islands contain candidate adaptive genes enriched for functions in sensory perception (including rhodopsin and other twilight-vision-associated genes), hormone signaling, and morphogenesis. Our study suggests mechanisms and genomic regions that may play a role in the closely related mega-radiation of Lake Malawi. PMID:26680190

  19. Ecology of Baskandi anua, an oxbow lake of South Assam, North East India.

    PubMed

    Gupta, Susmita; Devi, S Sushila

    2014-11-01

    A study was made on the physico-chemical properties of water and phyto and zooplankton communities of Baskandi anua, an oxbow lake of South Assam during March to August, 2009. Analyses of water showed acidic to slightly alkaline pH (5.4-7.9) with dissolved oxygen ranging from 4.26 to 11.83 mgl(-1) and total alkalinity from 31.25 to 65 mg l(-1), indicating the productive nature of water. Free CO2 fluctuated from 2.93 to 15.04 mgl(-1). PO4 and NO3 concentration ranged from 0.15 to 1.4 mg l(-1) and 0.06 mg l(-1) to 4.94 mg l(-1), respectively. Conductivity, pH and free CO2 were found higher at the sites surrounded by paddy fields. Mean values of physico-chemical parameters significantly varied between the sites and were found to be influenced by one or more of the following factors viz. rainfall, depth and influx from adjacent paddy field. A total of 30 phytoplankton taxa and 12 zooplankton taxa with qualitative dominance of Chlorophyceae were recorded. The study revealed that water quality of the lake was good for aquaculture. Hence, the lake should be protected and best management practices should be implemented for sustainable production. PMID:25522512

  20. Modelling the impact of changing climate and forest cultivation on the water balance of a closed lake in North-east Germany

    NASA Astrophysics Data System (ADS)

    Natkhin, M.; Steidl, J.; Dietrich, O.

    2009-04-01

    Over the last 25 years declining water levels are observed in several lakes of forested catchments in North-east-Brandenburg (Germany). This region is located in the transition zone between maritime and continental climate. The annual lake evapotranspiration often exceeds the precipitation which annual average is below 600 mm year-1. So the groundwater recharge mainly controls the water supply of lakes. Changes of climate and forest cultivation can have highly influence on groundwater recharge. To identify and quantify the share of changes in climate and forest management in the decline of the lake water levels, the participating processes are separated and evaluated using water balance modelling in a small lowland catchment. The results and methods were used to predict the development of lake water levels in future. The lake Redernswalder See (0.5 km²) was chosen as subject of research. It has a forest dominated catchment (3.5 km²) and no outlet. Water gauge measurements over the last 25 years show a decline in lake water level by more than 3 m. Changes of climate and forest cultivation are actually observed and will alter the groundwater recharge in the catchment. Currently, the forest in the Redernswalder See catchment just as throughout North-East Brandenburg is dominated by pine monoculture. Depending on the climate conditions, groundwater recharge may be significantly lower under pine than under broad-leaved trees like beech or oak. Forestry plans to expand the share of beeches and oaks among mixed deciduous forest in future. The physically based distributed water balance model WaSiM-ETH is used to model groundwater recharge in the catchment and the lake water balance. The horizontal groundwater flow is handled by the built-in 2D groundwater model. This plays an important role as a connector between the lake and its catchment. To verify the hydrogeological conditions, a separate 3D groundwater model of this Late Pleistocene lowland catchment was built up. With an application of regionalised climate scenarios the lake water level will decrease further in future. This is affected mainly by an increasing lake evapotranspiration. Forest conversation can although increase the water supply and slow the water level decrease, but the influence of climate change can finally not be compensated.

  1. Carbon Cycling of Lake Kivu (East Africa): Net Autotrophy in the Epilimnion and Emission of CO2 to the Atmosphere Sustained by Geogenic Inputs

    PubMed Central

    Borges, Alberto V.; Morana, Cédric; Bouillon, Steven; Servais, Pierre; Descy, Jean-Pierre; Darchambeau, François

    2014-01-01

    We report organic and inorganic carbon distributions and fluxes in a large (>2000 km2) oligotrophic, tropical lake (Lake Kivu, East Africa), acquired during four field surveys, that captured the seasonal variations (March 2007–mid rainy season, September 2007–late dry season, June 2008–early dry season, and April 2009–late rainy season). The partial pressure of CO2 (pCO2) in surface waters of the main basin of Lake Kivu showed modest spatial (coefficient of variation between 3% and 6%), and seasonal variations with an amplitude of 163 ppm (between 579±23 ppm on average in March 2007 and 742±28 ppm on average in September 2007). The most prominent spatial feature of the pCO2 distribution was the very high pCO2 values in Kabuno Bay (a small sub-basin with little connection to the main lake) ranging between 11213 ppm and 14213 ppm (between 18 and 26 times higher than in the main basin). Surface waters of the main basin of Lake Kivu were a net source of CO2 to the atmosphere at an average rate of 10.8 mmol m?2 d?1, which is lower than the global average reported for freshwater, saline, and volcanic lakes. In Kabuno Bay, the CO2 emission to the atmosphere was on average 500.7 mmol m?2 d?1 (?46 times higher than in the main basin). Based on whole-lake mass balance of dissolved inorganic carbon (DIC) bulk concentrations and of its stable carbon isotope composition, we show that the epilimnion of Lake Kivu was net autotrophic. This is due to the modest river inputs of organic carbon owing to the small ratio of catchment area to lake surface area (2.15). The carbon budget implies that the CO2 emission to the atmosphere must be sustained by DIC inputs of geogenic origin from deep geothermal springs. PMID:25314144

  2. Carbon cycling of Lake Kivu (East Africa): net autotrophy in the epilimnion and emission of CO2 to the atmosphere sustained by geogenic inputs.

    PubMed

    Borges, Alberto V; Morana, Cédric; Bouillon, Steven; Servais, Pierre; Descy, Jean-Pierre; Darchambeau, François

    2014-01-01

    We report organic and inorganic carbon distributions and fluxes in a large (>2000 km2) oligotrophic, tropical lake (Lake Kivu, East Africa), acquired during four field surveys, that captured the seasonal variations (March 2007-mid rainy season, September 2007-late dry season, June 2008-early dry season, and April 2009-late rainy season). The partial pressure of CO2 (pCO2) in surface waters of the main basin of Lake Kivu showed modest spatial (coefficient of variation between 3% and 6%), and seasonal variations with an amplitude of 163 ppm (between 579±23 ppm on average in March 2007 and 742±28 ppm on average in September 2007). The most prominent spatial feature of the pCO2 distribution was the very high pCO2 values in Kabuno Bay (a small sub-basin with little connection to the main lake) ranging between 11,213 ppm and 14,213 ppm (between 18 and 26 times higher than in the main basin). Surface waters of the main basin of Lake Kivu were a net source of CO2 to the atmosphere at an average rate of 10.8 mmol m(-2) d(-1), which is lower than the global average reported for freshwater, saline, and volcanic lakes. In Kabuno Bay, the CO2 emission to the atmosphere was on average 500.7 mmol m(-2) d(-1) (?46 times higher than in the main basin). Based on whole-lake mass balance of dissolved inorganic carbon (DIC) bulk concentrations and of its stable carbon isotope composition, we show that the epilimnion of Lake Kivu was net autotrophic. This is due to the modest river inputs of organic carbon owing to the small ratio of catchment area to lake surface area (2.15). The carbon budget implies that the CO2 emission to the atmosphere must be sustained by DIC inputs of geogenic origin from deep geothermal springs. PMID:25314144

  3. Near east paleomagnetic secular variation recorded in sediments from the Sea of Galilee (Lake Kinneret)

    NASA Astrophysics Data System (ADS)

    Thompson, R.; Turner, G. M.; Stiller, M.; Kaufman, A.

    1985-03-01

    Paleomagnetic records of declination and inclination from sediments recovered from the bed of Lake Kinneret (32.4°N, 35.7°E) have been dated by radiocarbon techniques. The sediments span the last 5000 yr. The changes in inclination down the sediment cores are more pronounced than the declination fluctuations and are repeatable between the three coring sites, which are several kilometers apart. Magnetic susceptibility logs display 13 maxima in the 5-m-long sequences, with a pronounced susceptibility minimum about 1000 yr B.P. Many of the susceptibility maxima and minima can be easily correlated between coring sites and are shown to be dominantly related to changes in sediment carbonate content. The natural remanent magnetization intensity follows a similar pattern to that of susceptibility, and the natural remanence of the Kinneret sediments is presumed to reside in detrital magnetite grains carried into the lake by the river Jordan from the basalt-rich bedrock of the rift floor and the Golan Heights. The 14C chronology is strongly supported by a pollen study in which pronounced changes in the proportion of olive pollen were interpreted as being due to extensive cultivation of olives around Galilee in the Hellenistic and Byzantine periods. The Kinneret paleosecular variation records, if accurately dated, point to a complex spatial pattern of Holocene secular variation with significant variations over distances as small as 1000-2000 km.

  4. 8. EAST PORTAL AND DECK VIEW, FROM EAST, SHOWING PORTAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. EAST PORTAL AND DECK VIEW, FROM EAST, SHOWING PORTAL CONFIGURATION AND LATERAL BRACING, STEEL MESH FLOOR, METAL RAILINGS, AND PORTION OF EAST APPROACH - Glendale Road Bridge, Spanning Deep Creek Lake on Glendale Road, McHenry, Garrett County, MD

  5. Lake-level rise in the late Pleistocene and active subaquatic volcanism since the Holocene in Lake Kivu, East African Rift

    E-print Network

    Gilli, Adrian

    Lake-level rise in the late Pleistocene and active subaquatic volcanism since the Holocene in Lake and Oeschger Centre for Climate Change Research, University of Bern, Switzerland a b s t r a c ta r t i c l e i revealed that volcanic eruptions blocked the former outlet of the lake to the north in the late Pleistocene

  6. Legacy and currently used pesticides in the atmospheric environment of Lake Victoria, East Africa.

    PubMed

    Arinaitwe, Kenneth; Kiremire, Bernard T; Muir, Derek C G; Fellin, Phil; Li, Henrik; Teixeira, Camilla; Mubiru, Drake N

    2016-02-01

    The Lake Victoria watershed has extensive agricultural activity with a long history of pesticide use but there is limited information on historical use or on environmental levels. To address this data gap, high volume air samples were collected from two sites close to the northern shore of Lake Victoria; Kakira (KAK) and Entebbe (EBB). The samples, to be analyzed for pesticides, were collected over various periods between 1999 and 2004 inclusive (KAK 1999-2000, KAK 2003-2004, EBB 2003 and EBB 2004 sample sets) and from 2008 to 2010 inclusive (EBB 2008, EBB 2009 and EBB 2010 sample sets). The latter sample sets (which also included precipitation samples) were also analyzed for currently used pesticides (CUPs) including chlorpyrifos, chlorthalonil, metribuzin, trifluralin, malathion and dacthal. Chlorpyrifos was the predominant CUP in air samples with average concentrations of 93.5, 26.1 and 3.54ngm(-3) for the EBB 2008, 2009, 2010 sample sets, respectively. Average concentrations of total endosulfan (?Endo), total DDT related compounds (?DDTs) and hexachlorocyclohexanes (?HCHs) ranged from 12.3-282, 22.8-130 and 3.72-81.8pgm(-3), respectively, for all the sample sets. Atmospheric prevalence of residues of persistent organic pollutants (POPs) increased with fresh emissions of endosulfan, DDT and lindane. Hexachlorobenzene (HCB), pentachlorobenzene (PeCB) and dieldrin were also detected in air samples. Transformation products, pentachloroanisole, 3,4,5-trichloroveratrole and 3,4,5,6-tetrachloroveratrole, were also detected. The five most prevalent compounds in the precipitation samples were in the order chlorpyrifos>chlorothalonil>?Endo>?DDTs>?HCHs with average fluxes of 1123, 396, 130, 41.7 and 41.3ngm(-2)sample(-1), respectively. PeCB exceeded HCB in precipitation samples. The reverse was true for air samples. Backward air trajectories suggested transboundary and local emission sources of the analytes. The results underscore the need for a concerted regional vigilance in management of chemicals. PMID:26575633

  7. East Tibetan lakes harbour novel clusters of picocyanobacteria as inferred from the 16S-23S rRNA internal transcribed spacer sequences.

    PubMed

    Wu, Qinglong L; Xing, Peng; Liu, Wen-Tso

    2010-04-01

    Planktonic picocyanobacteria abundance and diversity were investigated in nine lakes on the East Tibetan Plateau spanning a salinity gradient of 0.4-22.6 g l(-1). The investigation was conducted using epifluorescence microscopy (EFM) and terminal restriction fragment polymorphism analysis of 16S-23S rRNA internal transcribed spacer (ITS) PCR amplicons followed by sequence analyses of large ITS clone libraries of seven selected samples. EFM showed that picocyanobacteria comprised 7-19% of the total prokaryotic cells found in surface water. Most of the clones were classified into six clusters and grouped within the "picocyanobacterial clade", which consists exclusively of freshwater Synechococcus. Four new phylogenetic clusters and one new subcluster of Synechococcus spp. were found, none of which are members of any known picocyanobacterial clusters. The new clusters and subcluster were the most abundant picocyanobacteria (about 96% of the sequences) in the samples collected. Sequence analyses indicated that members of the four new Synechococcus groups were only found in freshwater lakes (<1.0 g l(-1) of total dissolved solid), while members of the new subcluster were found in all the investigated Tibetan lakes, over a large salinity gradient of 0.4-22.6 g l( -1). This suggests that there is ecologically significant microdiversity within the observed Synechococcus group as defined by ITS sequences. Collectively our study demonstrated abundant and potentially novel Synechococcus in East Tibetan lakes that are likely the result of evolutionary adaptations to regional conditions. PMID:19904569

  8. Interglacial environments of coastal east Antarctica: comparison of MIS 1 (Holocene) and MIS 5e (Last Interglacial) lake-sediment records

    NASA Astrophysics Data System (ADS)

    Hodgson, Dominic A.; Verleyen, Elie; Squier, Angela H.; Sabbe, Koen; Keely, Brendan J.; Saunders, Krystyna M.; Vyverman, Wim

    2006-01-01

    We reconstruct terrestrial and freshwater environments of the last two Quaternary interglacials in coastal east Antarctica by examining multi-proxy evidence in a lake sediment core. The record, from Progress Lake in the Larsemann Hills consists of two discrete sediment units. The lower unit contains the first known evidence of Antarctic coastal environments during a previous interglacial, likely to be MIS5e. Biogeochemical, biological and sedimentological climate proxies revealed a productive biological community and an active hydrological regime, consistent with the warmer conditions detected in continental ice cores at this time. The diatom assemblage was similar to that currently found in the sub- and maritime-Antarctic biome and included some sub-Antarctic endemic taxa that have not previously been reported from east Antarctica. This suggests southward expansion of the sub-Antarctic diatom biome during MIS5e. Mosses were also present in the lake or the catchment but are rare in the region today. Two discrete periods of enhanced productivity show that the MIS5e environment was not stable. MIS5e ended abruptly with a rapid transition to glacial conditions, the lake was covered by a layer of firnified snow and ice, and phototrophic biological activity ceased for a period of c. 90,000 years. The upper unit was deposited in MIS1 after 3470-3687 cal yr BP after phototrophic biological production resumed. Lower species diversity, pigment production, an Antarctic continental diatom assemblage and an absence of moss layers suggest cooler conditions during MIS1.

  9. Vegetation responses to interglacial warming in the Arctic: examples from Lake El'gygytgyn, Far East Russian Arctic

    NASA Astrophysics Data System (ADS)

    Lozhkin, A. V.; Anderson, P. M.

    2013-06-01

    Preliminary analyses of Lake El'gygytgyn sediment indicate a wide range of ecosystem responses to warmer than present climates. While palynological work describing all interglacial vegetation is ongoing, sufficient data exist to compare recent warm events (the postglacial thermal maximum, PGTM, and marine isotope stage, MIS5) with "super" interglaciations (MIS11, MIS31). Palynological assemblages associated with these climatic optima suggest two types of vegetation responses: one dominated by deciduous taxa (PGTM, MIS5) and the second by evergreen conifers (MIS11, MIS31). MIS11 forests show a similarity to modern Picea-Larix-Betula-Alnus forests of Siberia. While dark coniferous forest also characterizes MIS31, the pollen taxa show an affinity to the boreal forest of the lower Amur valley (southern Russian Far East). Despite vegetation differences during these thermal maxima, all glacial-interglacial transitions are alike, being dominated by deciduous woody taxa. Initially Betula shrub tundra established and was replaced by tundra with tree-sized shrubs (PGTM), Betula woodland (MIS5), or Betula-Larix (MIS11, MIS31) forest. The consistent occurrence of deciduous forest and/or high shrub tundra before the incidence of maximum warmth underscores the importance of this biome for modeling efforts. The El'gygytgyn data also suggest a possible elimination or massive reduction of Arctic plant communities under extreme warm-earth scenarios.

  10. The subglacial Lake Vostok (East Antarctica) surface snow is Earth-bound DNA (and dust)-free

    NASA Astrophysics Data System (ADS)

    Bulat, S.; Marie, D.; Bulat, E.; Alekhina, I.; Petit, J.-R.

    2012-09-01

    The objective was to assess the microbial cell abundance in the surface snow in Central East Antarctica and the fate of microbial genomic DNA during summer short-time exposure to surface climatic (and radiation) conditions at Vostok using flow cytometry and DNA-based methods. The surface snow (until 4m deep) was collected as clean as possible in the vicinity of the Vostok station (3 sites - courtesy of A Ekaykin and ASC Lebedev Physical Iinstitute RAS) and towards the Progress station (4 more sites with one just 29km from the coast - courtesy of A Ekaykin and S Popov) in specially decontaminated plastic crates or containers of various volumes (up to 75 kg of snow). All subsequent snow treatment manipulations (melting, concentrating, genomic DNA extraction, primary PCR set up) were performed in clean room laboratory facilities (LGGE, UJF-CNRS, Grenoble, France). Cell concentrations were determined on meltwater aliquots prepared under clean room conditions using flow cytofluorometry (Biostation, Roscoff, France). The highly concentrated meltwater (until 10000 times down) was used to extract gDNA which were subjected to bacterial 16S rRNA genes amplification in PCR and sequencing. The gDNA of a complex mesophile microbial community for exposure trials were also prepared and put onto a filter under strict clean room conditions. The filters were got exposed open to solar radiation and surface temperature at Vostok during January for various time duration periods (from 25 to 1 day). As a result no microbial cells were confidently detected in surface snow samples differed by sampling sites and people asked to collect as well. Complementary the mineral dust particle abundance did not exceed 16 mkg per liter with the particle size mode about 2.5 mkm as shown using Coulter counter. Preliminary amongst the microparticles no unusual findings (e.g. spherules of cosmic origin) were observed by shape and element composition using electron scanning microscopy. The gDNA studies came up with only contaminant bacterial phylotypes (mostly of human source). The bioexposure trials showed that even in one day of open exposure the gDNA of rather complex microbial community composition was fatally damaged in terms of long-, mid-range and short-size amplicon generation in PCR. All this testify for very harsh conditions for life to survive the climate conditions of Central East Antarctica which could be considered as a presentday 'zone mortale' or 'polar desert' for known Earthbound microbial life forms. In addition this means that no life seeds are expected to reach subglacial lakes and water reservoirs and establish indigenous lake microbiota during their transit through the thick and aged Antarctic ice sheet upon its bottom melting. In general the subglacial Lake Vostok surface (ice sheet as well) environ represents the unique test area (sterile - in fact Earth-bound DNA-free and clean - in fact Earth-bound dust-free) for advancing extraterrestrial (ET) life detection technologies and searching for ET life indices in AMMs and IDPs.

  11. High-elevation amplification of warming since the Last Glacial Maximum in East Africa: New perspectives from biomarker paleotemperature reconstructions

    NASA Astrophysics Data System (ADS)

    Loomis, S. E.; Russell, J. M.; Kelly, M. A.; Eggermont, H.; Verschuren, D.

    2013-12-01

    Tropical lapse rate variability on glacial/interglacial time scales has been hotly debated since the publication of CLIMAP in 1976. Low-elevation paleotemperature reconstructions from the tropics have repeatedly shown less warming from the Last Glacial Maximum (LGM) to present than reconstructions from high elevations, leading to widespread difficulty in estimating the true LGM-present temperature change in the tropics. This debate is further complicated by the fact that most paleotemperature estimates from high elevations in the tropics are derived from pollen- and moraine-based reconstructions of altitudinal shifts in vegetation belts and glacial equilibrium line altitudes (ELAs). These traditional approaches rely on the assumption that lapse rates have remained constant through time. However, this assumption is problematic in the case of the LGM, when pervasive tropical aridity most likely led to substantial changes in lapse rates. Glycerol dialkyl glycerol tetraethers (GDGTs) can be used to reconstruct paleotemperatures independent of hydrological changes, making them the ideal proxy to reconstruct high elevation temperature change and assess lapse rate variability through time. Here we present two new equatorial paleotemperature records from high elevations in East Africa (Lake Rutundu, Mt. Kenya and Lake Mahoma, Rwenzori Mountains, Uganda) based on branched GDGTs. Our record from Lake Rutundu shows deglacial warming starting near 17 ka and a mid-Holocene thermal maximum near 5 ka. The overall amplitude of warming in the Lake Rutundu record is 6.8×1.0°C from the LGM to the present, with mid-Holocene temperatures 1.6×0.9°C warmer than modern. Our record from Lake Mahoma extends back to 7 ka and shows similar temperature trends to our record from Lake Rutundu, indicating similar temporal resolution of high-elevation temperature change throughout the region. Combining these new records with three previously published GDGT temperature records from different elevations in East Africa (Sacred Lake, Lake Tanganyika, and Lake Malawi), we are able to reconstruct a continuous record of lapse rates and freezing level heights (FLHs) back to the LGM. We find that tropical lapse rates have varied widely over the last 22 ky, with the largest (lowest) lapse rate (FLH) around the LGM, while the smallest (highest) lapse rate (FLH) occurs during the mid-Holocene, confirming the amplification of warming at high altitudes between the LGM and present. These lapse rate and FLH reconstructions match records of regional hydrological variability, confirming the importance of glacial/interglacial humidity variations on altitudinal temperature gradients in the tropics. Furthermore, the FLH record largely matches records of tropical glacier ELA changes, indicating that warming from LGM-present was likely amplified at high altitudes throughout the tropics.

  12. Sources of core and intact branched tetraether membrane lipids in the lacustrine environment: Anatomy of Lake Challa and its catchment, equatorial East Africa

    NASA Astrophysics Data System (ADS)

    Buckles, Laura K.; Weijers, Johan W. H.; Verschuren, Dirk; Sinninghe Damsté, Jaap S.

    2014-09-01

    The MBT/CBT palaeotemperature proxy uses the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs), membrane lipids that are supposed to derive from soil bacteria, to reconstruct mean annual air temperature (MAAT). Applied successfully in coastal marine sediments, its extension to lake-sediment records with potentially high time resolution would greatly expand its utility. Over the last years, however, studies have indicated the presence of additional sources of brGDGTs within lake systems. To constrain the factors influencing the MBT/CBT palaeotemperature proxy in lakes, detailed investigation of brGDGT fluxes in a modern lake system is necessary to identify their potential sources. This study concentrates on Lake Challa, a permanently stratified crater lake in equatorial East Africa with limited catchment area. An almost 3-year time series of approximately monthly samples of settling particles, supplemented with a depth profile of suspended particulate matter (SPM) and sets of profundal surface-sediment and catchment soil samples, were analysed for both the ‘living’ intact polar lipids (IPLs) and ‘fossil’ core lipids (CLs) of GDGTs. We found that brGDGTs are produced in oxic, suboxic and anoxic zones of the water column, and in substantial amounts compared to influxes from catchment soils. Additional in situ production within the lake sediments is most probable, but cannot be definitely confirmed at this time. These lacustrine brGDGTs display a different response to temperature variation than soil-derived brGDGTs, signifying either a different physiological adaptation to changing conditions within the water column and/or a different composition of the respective bacterial communities. Using this specific relationship with temperature, a local calibration based on brGDGT distributions in SPM generates relatively accurate water temperature estimates from settling particles but fails for surface sediments.

  13. Multiple Episodic Evolution Events in V1R Receptor Genes of East-African Cichlids

    PubMed Central

    Nikaido, Masato; Ota, Tomoki; Hirata, Tadashi; Suzuki, Hikoyu; Satta, Yoko; Aibara, Mitsuto; Mzighani, Semvua I.; Sturmbauer, Christian; Hagino-Yamagishi, Kimiko; Okada, Norihiro

    2014-01-01

    Fish use olfaction to detect a variety of nonvolatile chemical signals, and thus, this sense is key to survival and communication. However, the contribution of the olfactory sense to social—especially reproductive—interactions in cichlids is still controversial. To obtain insights into this issue, we investigated the genes encoding V1Rs—possible candidates for reproductive pheromone receptors—among East-African cichlids. Interestingly, we found an excess of nonsynonymous over synonymous substitutions in four of six V1R genes in multiple cichlid lineages. First, we found that highly dimorphic V1R2 allele groups were shared among the cichlids inhabiting all East-African Great Lakes emerged through the episodic accumulation of the nonsynonymous substitutions prior to the radiation of the Lake Tanganyika species flock. We further detected such episodic events in V1R1 of the tribe Tropheini, and in V1R3 and V1R6 of the tribe Trematocarini. The excess of nonsynonymous substitutions in these examples were indicated as dN/dS > 1, which were all statistically significant by Fisher’s exact test. Furthermore, we speculate that the amino acid changes in these episodic events are likely functional switch because they occurred in the putative ligand-binding pocket. Our finding of the occurrence of multiple episodic events and the unexpected gene diversity in one unique gene family is suggestive of the contribution of the V1R to the species diversification and the social interaction in cichlids. PMID:24803573

  14. 19. View west, foreground, north facade of Forest East Suites, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. View west, foreground, north facade of Forest East Suites, background north & east facades of Forest Hall. - Lake Placid Club, Forest Wing, East side of Mirror Lake Drive, North of State Route 86 & Main, North Elba, Essex County, NY

  15. 27. View east, foreground north facade of Forest Hall, background ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    27. View east, foreground north facade of Forest Hall, background north facade of Forest East Suites. - Lake Placid Club, Forest Wing, East side of Mirror Lake Drive, North of State Route 86 & Main, North Elba, Essex County, NY

  16. Paleoenvironmental context of the Middle Stone Age record from Karungu, Lake Victoria Basin, Kenya, and its implications for human and faunal dispersals in East Africa.

    PubMed

    Faith, J Tyler; Tryon, Christian A; Peppe, Daniel J; Beverly, Emily J; Blegen, Nick; Blumenthal, Scott; Chritz, Kendra L; Driese, Steven G; Patterson, David

    2015-06-01

    The opening and closing of the equatorial East African forest belt during the Quaternary is thought to have influenced the biogeographic histories of early modern humans and fauna, although precise details are scarce due to a lack of archaeological and paleontological records associated with paleoenvironmental data. With this in mind, we provide a description and paleoenvironmental reconstruction of the Late Pleistocene Middle Stone Age (MSA) artifact- and fossil-bearing sediments from Karungu, located along the shores of Lake Victoria in western Kenya. Artifacts recovered from surveys and controlled excavations are typologically MSA and include points, blades, and Levallois flakes and cores, as well as obsidian flakes similar in geochemical composition to documented sources near Lake Naivasha (250 km east). A combination of sedimentological, paleontological, and stable isotopic evidence indicates a semi-arid environment characterized by seasonal precipitation and the dominance of C4 grasslands, likely associated with a substantial reduction in Lake Victoria. The well-preserved fossil assemblage indicates that these conditions are associated with the convergence of historically allopatric ungulates from north and south of the equator, in agreement with predictions from genetic observations. Analysis of the East African MSA record reveals previously unrecognized north-south variation in assemblage composition that is consistent with episodes of population fragmentation during phases of limited dispersal potential. The grassland-associated MSA assemblages from Karungu and nearby Rusinga Island are characterized by a combination of artifact types that is more typical of northern sites. This may reflect the dispersal of behavioral repertoires-and perhaps human populations-during a paleoenvironmental phase dominated by grasslands. PMID:25883052

  17. Phytoliths Used to Investigate the Effects of the Indonesian Mount Toba Super-Eruption (~75 kyr) in East Africa: A Subdecadal Record from Lake Malawi

    NASA Astrophysics Data System (ADS)

    Yost, C. L.; Cohen, A. S.

    2014-12-01

    The recent discovery of cryptotephra visually and chemically matched to the Youngest Toba Tuff (YTT, 75.0 ± 0.9 kyr) in Lake Malawi drill core sediments has spurred renewed interest in this period of time in East Africa. The YTT is the most recent and largest of the four Mount Toba eruptions, and is the only super-eruption to have taken place during the Quaternary. The timing of the YTT approximately coincides with a hypothesized human genetic bottleneck. Several climate models have proposed an episode of global cooling following the YTT; however, the magnitude and duration of the cooling is much debated, ranging from just a few degrees of cooling to a state of volcanic winter. Cored sediments from Lake Malawi provide an excellent record of local variability in the lake's watershed that may be linked to specific climatic events. To investigate the possible effects of the YTT in East Africa, we continuously sampled Lake Malawi drill core 2A-10H-2 at 2-4 mm (~6 yr) intervals above and below the first occurrence of the YTT. Poaceae phytoliths were grouped into plant functional types (C3, C4, xerophytic, mesophytic, arboreal, etc.), revealing mostly subtle changes in terrestrial vegetation over the ~400 yr time period examined. Abrupt increases in concentration values for phytoliths derived from riverine Podostemaceae plants appear to signal increased discharge from rivers draining the surrounding uplands. Perhaps most significant is the increasing trend in burned phytoliths and decreasing trend in tree phytoliths post-YTT. Although there appears to be a very weak cooling signal synchronous with the YTT, the most abrupt terrestrial vegetation changes appear to be better correlated with the deposition of a slightly older cryptotephra horizon derived from the local Rungwe Volcanic Province. A potential complication with this record is the existence of a turbidite pre-YTT that encompasses the Rungwe horizon.

  18. Isotopic variability in the deepest Vostok (East Antarctica) ice core suggests not perfect mixing of Lake Vostok water

    NASA Astrophysics Data System (ADS)

    Ekaykin, A. A.; Lipenkov, V. Ya.

    2009-04-01

    One of the key questions about subglacial Antarctic Lake Vostok (LV) hydrological system is whether the water of the lake is well mixed or not. Not complete mixing of water from the sources feeding the lake (glacier melt and hydrothermal water) with the water of main lake body would have several important consequences: 1) lake ice retrieved from 5G-1 borehole at Vostok Station is likely formed from a water layer which is not fully representative for the entire lake; 2) effective residence time of water in the main lake body is likely significantly longer than that deduced from simple mass balance estimations; 3) and, likely most important, not perfect mixing of lake water would suggest the existence of ecological niches where micro-biota can hide from lethal influence of high oxygen concentration likely typical for the lake. A powerful and promising tool for studying hydrological regime of LV is analyses of lake ice isotope content variability. Up to now, isotopic data from the lake ice have been only used to roughly estimate the components of the lake's mass balance. However, closer view to the lake ice isotopic signal may provide with a range of valuable information about processes taking place just beneath the glacier sole. Here we present new isotopic data from the deepest part of Vostok ice core (3611-3650 m), as well as revisit the previously published data from the 3538-3611 m interval. It is shown that the lake ice isotope content experiences small-scale variability which is related to the changes of the isotopic composition of the freezing water. Since the time-scale of these oscillations is much less than the expected LV residence time, it suggests that lake water is not perfectly mixed. Most likely it is due to not complete mixing of melt water and/or hydrothermal water with lake resident water on their way to the freezing site. The work is carried out in frames of Project 4 of Russian Federal Targeted Program "Antarctica". We thank Russian Antarctic Expedition for logistical operations, St. Petersburg Mining Institute for providing with the high-quality ice core, Laboratoire des Sciences du Climat et l'Environnement (Saclay, France), Niels Bohr Institute (Copenhagen, Denmark) and St. Petersburg Geological Institute (VSEGEI, Russia) for the mass-spectrometric analyses.

  19. Palynology and Paleoecology of the Lake Somerville spillway section, Late Eocene Manning Formation (Jackson Group), east-central Texas 

    E-print Network

    Sancay, Recep Hayrettin

    2000-01-01

    Analysis of lignites, freshwater and marine siliciclastic sediments from the Lake Somerville spillway section (Late Eocene, Jackson Group, Manning Formation) yielded a diverse assemblage of terrestrial palynomorphs including ...

  20. A biomarker record of Lake El'gygytgyn, Far East Russian Arctic: investigating sources of organic matter and carbon cycling during marine isotope stages 1-3

    NASA Astrophysics Data System (ADS)

    Holland, A. R.; Petsch, S. T.; Castañeda, I. S.; Wilkie, K. M.; Burns, S. J.; Brigham-Grette, J.

    2013-01-01

    Arctic paleoenvironmental archives serve as sensitive recorders of past climate change. Lake El'gygytgyn (Far East Russian Arctic) is a high-latitude crater impact lake that contains a continuous sediment record influenced by neither glaciation nor glacial erosion since the time of impact 3.58 Ma ago. Prior research on sediments collected from Lake El'gygytgyn suggest times of permanent ice cover and anoxia corresponding to global glacial intervals, during which the sediments are laminated and are characterized by the co-occurrence of high total organic carbon, microscopic magnetite grains that show etching and dissolution, and negative excursions in bulk sediment organic matter carbon isotope (?13C) values. Here we investigate the abundance and carbon isotopic composition of lipid biomarkers recovered from Lake El'gygytgyn sediments spanning marine isotope stages 1-3 to identify key sources of organic matter (OM) to lake sediments, to establish which OM sources drive the negative ?13C excursion exhibited by bulk sediment OM, and to explore if there are molecular and isotopic signatures of anoxia in the lake during glaciation. We find that during marine isotope stages 1-3, direct evidence for water column anoxia is lacking. A ~4‰ negative excursion in bulk sediment ?13C values during the Local Last Glacial Maximum (LLGM) is accompanied by more protracted, higher magnitude negative excursions in n-alkanoic acid and n-alkanol ?13C values that begin 20 kyr in advance of the LLGM. In contrast, n-alkanes and the C30 n-alkanoic acid do not exhibit a negative ?13C excursion at this time. Our results indicate that the C24, C26 and C28 n-alkanoic acids do not derive entirely from terrestrial OM sources, while the C30 n-alkanoic acid at Lake El'gygytgyn is a robust indicator of terrestrial OM contributions. Overall, our results strongly support the presence of a nutrient-poor water column, which is mostly isolated from atmospheric carbon dioxide during glaciation at Lake El'gygytgyn.

  1. A biomarker record of Lake El'gygytgyn, far east Russian Arctic: investigating sources of organic matter and carbon cycling during marine isotope stages 1-3

    NASA Astrophysics Data System (ADS)

    Holland, A. R.; Petsch, S. T.; Castañeda, I. S.; Wilkie, K. M.; Burns, S. J.; Brigham-Grette, J.

    2012-09-01

    Paleoenvironmental archives in Arctic regions serve as sensitive recorders of past climate change where summer temperatures hover near freezing and small climate variations may exhibit strong threshold-crossing environment responses. Lake El'gygytgyn (Far East Russian Arctic) is a high-latitude crater impact lake that contains a continuous sediment record influenced by neither glaciation nor glacial erosion since the time of impact at 3.58 Ma. Prior research on sediments collected from Lake El'gygytygyn suggest times of permanent ice cover and anoxia corresponding to global glacial intervals, during which the sediments are laminated and are characterized by the co-occurrence of high total organic carbon, microscopic magnetite grains that show etching and dissolution, and negative excursions in bulk sediment organic matter carbon isotope (?13C) values. Here, we investigate the abundance and carbon isotopic characteristics of lipid biomarkers recovered from Lake El'gygytygn sediments spanning marine isotope stages 1-3, to identify key sources of organic matter (OM) to lake sediments, to establish which compounds and thus OM sources drive the negative ?13C excursion exhibited by bulk sediment OM, and to explore if there are molecular and isotopic signatures of anoxia in the lake during glaciation. We find that during marine isotope stages 1-3, direct evidence for water column anoxia is lacking. A ∼4‰ negative excursion in bulk sediment ?13C values during the local Last Glacial Maximum (LLGM) is accompanied by more protracted, higher magnitude negative excursions in n-alkanoic acid and n-alkanol ?13C values that begin 20 kyr in advance of the LLGM. In contrast, n-alkanes and the C30 n-alkanoic acid do not exhibit a negative ?13C excursion at this time. Our results indicate that the C24, C26 and C28 n-alkanoic acids do not derive entirely from terrestrial OM sources, while the C30 n-alkanoic acid at Lake El'gygytgyn is a robust indicator of terrestrial OM contributions. Overall, our results strongly support the presence of a nutrient-poor water column, which is mostly isolated from atmospheric carbon dioxide during glaciation at Lake El'gygytgyn.

  2. Historical deposition of persistent organic pollutants in Lake Victoria and two alpine equatorial lakes from East Africa: Insights into atmospheric deposition from sedimentation profiles.

    PubMed

    Arinaitwe, Kenneth; Rose, Neil L; Muir, Derek C G; Kiremire, Bernard T; Balirwa, John S; Teixeira, Camilla

    2016-02-01

    Information on historical deposition of persistent organic pollutants (POPs) for African lakes is very limited. We investigated historical deposition trends and sources of POPs in sediment cores from Lakes Victoria (SC1), Bujuku (Buju2) and Mahoma (Maho2). The latter two lakes are situated in the Rwenzori mountain range in western Uganda. SC1 was taken from a central depositional area within the Ugandan part of the lake. Profiles in Buju2 and Maho2 were used as a reference for historical atmospheric deposition. For the post-1940 sediment deposits in SC1, average focusing factor-adjusted fluxes (FFFs) of ?DDTs, polychlorinated biphenyls (?PCBs), hexachlorocyclohexanes (?HCHs) and chlordanes (?CHLs) were 390, 230, 210 and 120 ng m(-2) yr(-1). Higher fluxes of ?DDTs, ?PCBs, and ?CHLs were observed in Buju2 and Maho2. The average FFF of HCB in Buju2 was the highest while the values for Maho2 and SC1 were similar. The endosulfan FFFs in SC1 were lower than in the alpine lake cores. Generally, Buju2 was a better reference for historical atmospheric deposition of POPs than Maho2 probably due to distortion of the latter's profile by Lake Mahoma's forested catchment. Profiles of p,p'-DDE, ?CHLs and HCB in SC1 were consistent with atmospheric deposition while profiles of PCBs and HCHs were indicative of particle-bound loadings from additional sources. Profiles of endosulfans, DDTs, and chlordanes were consistent with influence of other factors such as anoxia, and dilution. Further studies of spatial resolution of historical deposition, especially in near-shore deposition areas of the lake are recommended. PMID:26539705

  3. The species flocks of East African cichlid fishes: recent advances in molecular phylogenetics and population genetics

    NASA Astrophysics Data System (ADS)

    Salzburger, Walter; Meyer, Axel

    With more than 3,000 species, the fish family Cichlidae is one of the most species-rich families of vertebrates. Cichlids occur in southern and central America, Africa, Madagascar, and India. The hotspot of their biodiversity is East Africa, where they form adaptive radiations composed of hundreds of endemic species in several lakes of various sizes and ages. The unparalleled species richness of East African cichlids has been something of a conundrum for evolutionary biologists and ecologists, since it has been in doubt whether these hundreds of species arose by allopatric speciation or whether it is necessary to invoke somewhat less traditional models of speciation, such as micro-allopatric, peripatric, or even sympatric speciation or evolution through sexual selection mediated by female choice. Ernst Mayr's analyses of these evolutionary uniquely diverse species assemblages have contributed to a more direct approach to this problem and have led to a deeper understanding of the patterns and processes that caused the formation of these huge groups of species. We review here recent molecular data on population differentiation and phylogenetics, which have helped to unravel, to some extent, the patterns and processes that led to the formation and ecological maintenance of cichlid species flocks. It is becoming apparent that sexually selected traits do play an important role in speciation in micro-allopatric or even sympatric settings. Species richness seems to be roughly correlated with the surface area, but not the age, of the lakes. We observe that the oldest lineages of a species flock of cichlids are often less species-rich and live in the open water or deepwater habitats. While the species flocks of the Lake Malawai and the Lake Victoria areas were shown to be monophyletic, the cichlid assemblage of Lake Tanganyika seems to consist of several independent species flocks. Cichlids emerge as an evolutionary model system in which many fundamental questions in evolution and ecology can be tested successfully, yet for other fish species flocks the relative importance of alternative mechanisms of speciation is likely to differ from that in cichlid fish.

  4. Sexual dimorphism and population divergence in the Lake Tanganyika cichlid fish genus Tropheus

    PubMed Central

    2010-01-01

    Background With about 120 colour morphs currently assigned to six nominal species, the genus Tropheus is an ideal model to study evolutionary divergence of populations in allopatry. The morphology of Tropheus has been described as relatively static, but reproductive constraints are sexually dimorphic due to mouthbrooding in females. We analysed phenotypic variation in six populations of T. moorii and one population of T. polli using geometric morphometrics to assess morphological differences among sexes in relation to the differentiation of populations and species. Results The mean shapes differed significantly between sexes, populations, and species even though within-sex variation exceeded the divergence among populations. The first principal component of Procrustes shape coordinates revealed differences between populations and species in mouth position and ventral head shape. The second principal component reflected sex-specific shape differences, mainly comprising a relatively larger female viscerocranium and, in particular, a larger buccal area. While shape variation between populations and between sexes was primarily located in the cranial region, within-sex variation was relatively uniform across all landmarks. Conclusions Deviations of the between-population and between-sex pattern of shape variation from that within sex indicate that the differences in head shape likely result from both adaptations to female mouthbrooding and population-specific foraging strategies. PMID:20205752

  5. Phylogenetic and antigenic characterization of reassortant H9N2 avian influenza viruses isolated from wild waterfowl in the East Dongting Lake wetland in 2011–2012

    PubMed Central

    2014-01-01

    Background Wild waterfowl are recognized as the natural reservoir for influenza A viruses. Two distinct lineages, the American and Eurasian lineages, have been identified in wild birds. Gene flow between the two lineages is limited. The H9N2 virus has become prevalent in poultry throughout Eurasia, and mainly circulates in wild ducks and shorebirds in North America. Methods In this study, 22 H9N2 avian influenza viruses were isolated from wild waterfowl feces in East Dongting Lake Nature Reserve in November 2011 and March 2012. The phylogenetic, molecular, and antigenic characteristics of these viruses were analyzed based on analyses of the whole genome sequence of each isolate. Results Phylogenetic analyses indicated that these H9N2 viruses were generated by reassortment events. The HA, NA, PA, and NS genes were derived from the American gene pool, and the other four genes were derived from the Eurasian gene pool. Antigenic analyses indicated that these viruses were significantly different from the Eurasian lineage viruses. Conclusions This study presents the isolation of novel intercontinental recombinant H9N2 viruses from wild waterfowl in the East Dongting Lake wetland. The novel genotype H9N2 virus has not been detected in poultry in the region yet, and may be transmitted to naïve birds in poultry farms. Therefore, our results highlight the need for ongoing surveillance of wild birds and poultry in this region. PMID:24779444

  6. NORTH GATE AT 11TH AVENUE (490 NORTH & 900 EAST), ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    NORTH GATE AT 11TH AVENUE (490 NORTH & 900 EAST), SALT LAKE CITY, UT. VIEW LOOKING SOUTH AT CEMETERY'S NORTH GATE (WPA PROJECT, 1938-1941). - Salt Lake City Cemetery, 200 N Street, Salt Lake City, Salt Lake County, UT

  7. WEST PIER OF NORTH GATE (490 NORTH & 900 EAST), ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    WEST PIER OF NORTH GATE (490 NORTH & 900 EAST), SALT LAKE CITY, UT. VIEW LOOKING SOUTH AT THE WEST PIER OF THE CEMETERY'S NORTH GATE. - Salt Lake City Cemetery, 200 N Street, Salt Lake City, Salt Lake County, UT

  8. Cascade Locks Wahtum LakeWahtum Lake

    E-print Network

    Stream Intermittent Stream Waterbodies Urban Area Highway Railroad FOCAL SPECIES BE = Bald Eagle NSOCascade Locks Wyeth Viento Hood River Wahtum LakeWahtum Lake H ood Rive r EagleCreek Lake Branch RudolphCreek East Fork Eagle Creek No Name Cree k Collin s Creek Bird ie Creek S um mit Cr eek S tarvation

  9. Levels and patterns of persistent organic pollutants (POPs) in tilapia (Oreochromis sp.) from four different lakes in Tanzania: geographical differences and implications for human health.

    PubMed

    Polder, A; Müller, M B; Lyche, J L; Mdegela, R H; Nonga, H E; Mabiki, F P; Mbise, T J; Skaare, J U; Sandvik, M; Skjerve, E; Lie, E

    2014-08-01

    In Tanzania fish is one of the most important protein sources for the rapidly increasing population. Wild fish is threatened by overfishing and pollution from agriculture, industries, mining, household effluents and vector control. To monitor possible implications for public health, the geographical differences of the occurrence and levels of persistent organic pollutants (POPs) in tilapia fish (Oreochromis sp.) from four different Tanzanian lakes were investigated in 2011. Concentrations of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyls (PBDEs) and hexabromocyclododecane (HBCDD) were determined in pooled samples of tilapia muscle from Lake (L) Victoria, L. Tanganyika, L. Nyasa (also called L. Malawi) and L. Babati in Tanzania in 2011. Levels of ?-DDTs (274 ng/g lipid weight (lw)) and sum of 7 indicator PCBs (?-7PCBs) (17 ng/g lw) were significantly higher in tilapia from L. Tanganyika compared to the other lakes. The highest levels of ?-endosulfan (94 ng/g lw) were detected in tilapia from L. Victoria. Toxaphenes were detected in low levels in fish from L. Tanganyika and L. Babati. Results revealed a geographic difference in the use of DDT and endosulfan between L. Victoria and L. Tanganyika. Low ratios of DDE/DDT in tilapia from L. Tanganyika indicated an on-going use of DDT in the area. Median levels of ?BDEs, including BDE-209, were highest in L. Victoria (19.4 ng/g lw) and BDE-209 was present in 68% of the samples from this lake. The presence of BDE-209 indicates increasing influence of imported products from heavy industrialized countries. The measured POP levels in the studied tilapia were all below MRLs of EU or were lower than recommended levels, and thus the fish is considered as safe for human consumption. They may, however, pose a risk to the fish species and threaten biodiversity. PMID:24836134

  10. Dynamic diatom response to changing climate 0-1.2 Ma at Lake El'gygytgyn, Far East Russian Arctic

    NASA Astrophysics Data System (ADS)

    Snyder, J. A.; Cherepanova, M. V.; Bryan, A.

    2013-06-01

    The Lake El'gygytgyn sediment record contains an abundant diatom flora through most intervals of the lake's history, providing a means to create and test hypotheses concerning the lake's response to changing climates. The 0-1.2 Ma core interval is characterized by shifts in the dominant planktonic genera and events of exceptional concentration and diversity. Warm interglacial intervals have enhanced concentration and diversity of the plankton. This response is most extreme during exceptional events corresponding to marine isotope stages (MIS) 11 and 31. Diatom concentration and diversity also increase during some cold intervals (e.g., MIS 2), suggesting conditions of lake circulation and nutrient cycling promoting diatom production during these events. Short intervals of low plankton concentration accompanied by shifts in the dominant genus of the lake suggest conditions during certain cold events generate a severe impact on plankton production. The absence of these events during extended intervals of low summer insolation variability suggests a muted cold-event response of the lake system linked to regional climate.

  11. Early- to Mid-Holocene hydroclimate shifts in tropical East Africa: the multi-proxy sediment record from Lake Rutundu, Kenya

    NASA Astrophysics Data System (ADS)

    De Cort, Gijs; Creutz, Mike; Barao, Lucia; Conley, Daniel; Haug, Gerald; Bodé, Samuel; Blaauw, Maarten; Engstrom, Dan; Verschuren, Dirk

    2015-04-01

    Following the generally arid conditions of the Last Glacial Maximum (LGM), a large part of the African continent experienced the Early to Mid-Holocene as a much more humid period than today. This so-called African Humid Period (AHP) coincided with high summertime insolation over the Northern Hemisphere subtropics, causing invigorated monsoons to create moist conditions over the northern parts of the continent. Similarly, equatorial and even low-latitude southeastern Africa experienced a wetter climate due to the post-glacial increase in atmospheric greenhouse gasses ultimately leading to altered Atlantic and Indian Ocean monsoon dynamics. The timing and abruptness of the onset and ending of the AHP in the different regions of the continent have been the subject of major discussion. On the other hand, shorter-lived climate fluctuations within the AHP have received much less attention, due to a scarcity of well-dated, high-resolution African paleoclimate records spanning the entire Holocene. In this study we used the sediment record of Lake Rutundu, a high-altitude crater lake on Mount Kenya, to document multidecadal to millennial-scale hydroclimate variability on the East African equator from the LGM to the present. A multiproxy approach combining core-surface scanning techniques (magnetic susceptibility, X-ray fluorescence) and close-interval bulk-sediment analyses (organic matter and biogenic Si content, grain size, organic ?15N and ?13C) resulted in a high-resolution record firmly anchored in time by an age model based on 210Pb dating and sixteen calibrated radiocarbon ages. This new Lake Rutundu hydroclimate record confirms that moister conditions following the LGM returned to East Africa ca.16 kyr BP, and it contains a perfectly timed Younger Dryas episode (12.8-11.5 kyr BP) of intermittent drought. We find that the Early- to Mid-Holocene period, which in African records is often described as uniformly wet, was in fact punctuated by three distinct, century-scale drought episodes. The first of these provides robust evidence that the 8.2 kyr cooling event, well-known from high northern latitudes, impacted tropical East Africa's moisture balance as well. The two other drought episodes, centered at c.6.5 and 5.5 kyr BP, punctuate the mid-Holocene drying which eventually ended the AHP in this region around 4 kyr BP.

  12. Evolution of the Lake Victoria basin in the context of coeval rift initiation in East Africa: a 3D numerical model approach

    NASA Astrophysics Data System (ADS)

    Wichura, Henry; Quinteros, Javier; Melnick, Daniel; Brune, Sascha; Schwanghart, Wolfgang; Strecker, Manfred R.

    2015-04-01

    Over the last four years sedimentologic and thermochronologic studies in the western and eastern branches of the Cenozoic East African Rift System (EARS) have supported the notion of a broadly contemporaneous onset of normal faulting and rift-basin formation in both segments. These studies support previous interpretations based on geophysical investigations from which an onset of rifting during the Paleogene had been postulated. In light of these studies we explore the evolution of the Lake Victoria basin, a shallow, unfaulted sedimentary basin centered between both branches of the EARS and located in the interior of the East African Plateau (EAP). We quantify the fluvial catchment evolution of the Lake Victoria basin and assess the topographic response of African crust to the onset of rifting in both branches. Furthermore, we evaluate and localize the nature of strain and flexural rift-flank uplift in both branches. We use a 3D numerical forward model that includes nonlinear temperature- and stress-dependent elasto-visco-plastic rheology. The model is able to reproduce the flexural response of variably thick lithosphere to rift-related deformation processes such as lithospheric thinning and asthenospheric upwelling. The model domain covers the entire EAP and integrates extensional processes in a heterogeneous, yet cold and thick cratonic block (Archean Tanzania craton), which is surrounded by mechanically weaker Proterozoic mobile belts, which are characterized by thinner lithosphere ("thin spots"). The lower limits of the craton (170 km) and the mobile belts (120 km) are simulated by different depths of the 1300 °C lithosphere-asthenosphere boundary. We assume a constant extension rate of 4 mm/a throughout the entire simulation of 30 Ma and neglect the effect of dynamic topography and magmatism. Even though the model setup is very simple and the resolution is not high enough to calculate realistic rift-flank uplift, it intriguingly reveals important topographic trends. The model shows that elevation differences of 120 to 180 m between the plateau interior and bordering rift shoulders are pronounced enough to form a closed basin after 6.5 Ma of extension. By that time the catchment area is already comparable to the present-day Lake Victoria catchment. Moreover, the final modeled topography, including 1000 m of dynamic and 500 m of pre-plume topography, yields a base basin elevation of 1110 m, which is also in good agreement with the present-day elevation of Lake Victoria. The combined effects of the formation of an extensive lacustrine depositional environment in the interior of the EAP after 6.5 Ma and rift-shoulder uplift may have forced far-reaching environmental impacts. These may have included the onset of the Lake Victoria microclimate, the influence of the basin and surrounding orographic barriers on precipitation patterns in East Africa, and the establishment of a unique flora and fauna.

  13. Presence of the 54-chromosome common vole (Mammalia) on Olkhon Island (Lake Baikal, East Siberia, Russia), and the occurrence of an unusual X-chromosome variant

    PubMed Central

    Pavlova, S.V.; Tchabovsky, A.V.

    2011-01-01

    Abstract We report a new finding of the 54-chromosome sibling species of the common vole in East Siberia - the first description from Olkhon Island (Lake Baikal). The karyotype of a male specimen revealed by routine staining and C-banding demonstrates the unambiguous presence of Microtus rossiaemeridionalis Ognev, 1924 (recently often regarded as as junior synonym of Microtus levis Miller, 1908). Comparison with conspecific specimens from the European part of the species range (from the left bank of the river Volga) shows that the vole of the island population has a smaller X-chromosome due to a reduced quantity of C-positive heterochromatin. This is just the third example of this type of X-chromosome variant with previous cases on an Arctic island (Svalbard) and the West Siberian lowland (Novosibirsk) and the only one on a lake island. Although Microtus rossiaemeridionalis is largely monomorphic in its karyotype, our data show that one specific type of X-chromosome variant is remarkably widespread, though rare. PMID:24260647

  14. A 350 ka record of climate change from Lake El'gygytgyn, Far East Russian Arctic: refining the pattern of climate modes by means of cluster analysis

    NASA Astrophysics Data System (ADS)

    Frank, U.; Nowaczyk, N. R.; Minyuk, P.; Vogel, H.; Rosén, P.; Melles, M.

    2013-07-01

    Rock magnetic, biochemical and inorganic records of the sediment cores PG1351 and Lz1024 from Lake El'gygytgyn, Chukotka peninsula, Far East Russian Arctic, were subject to a hierarchical agglomerative cluster analysis in order to refine and extend the pattern of climate modes as defined by Melles et al. (2007). Cluster analysis of the data obtained from both cores yielded similar results, differentiating clearly between the four climate modes warm, peak warm, cold and dry, and cold and moist. In addition, two transitional phases were identified, representing the early stages of a cold phase and slightly colder conditions during a warm phase. The statistical approach can thus be used to resolve gradual changes in the sedimentary units as an indicator of available oxygen in the hypolimnion in greater detail. Based upon cluster analyses on core Lz1024, the published succession of climate modes in core PG1351, covering the last 250 ka, was modified and extended back to 350 ka. Comparison to the marine oxygen isotope (?18O) stack LR04 (Lisiecki and Raymo, 2005) and the summer insolation at 67.5° N, with the extended Lake El'gygytgyn parameter records of magnetic susceptibility (?LF), total organic carbon content (TOC) and the chemical index of alteration (CIA; Minyuk et al., 2007), revealed that all stages back to marine isotope stage (MIS) 10 and most of the substages are clearly reflected in the pattern derived from the cluster analysis.

  15. Presence of the 54-chromosome common vole (Mammalia) on Olkhon Island (Lake Baikal, East Siberia, Russia), and the occurrence of an unusual X-chromosome variant.

    PubMed

    Pavlova, S V; Tchabovsky, A V

    2011-01-01

    We report a new finding of the 54-chromosome sibling species of the common vole in East Siberia - the first description from Olkhon Island (Lake Baikal). The karyotype of a male specimen revealed by routine staining and C-banding demonstrates the unambiguous presence of Microtus rossiaemeridionalis Ognev, 1924 (recently often regarded as as junior synonym of Microtus levis Miller, 1908). Comparison with conspecific specimens from the European part of the species range (from the left bank of the river Volga) shows that the vole of the island population has a smaller X-chromosome due to a reduced quantity of C-positive heterochromatin. This is just the third example of this type of X-chromosome variant with previous cases on an Arctic island (Svalbard) and the West Siberian lowland (Novosibirsk) and the only one on a lake island. Although Microtus rossiaemeridionalis is largely monomorphic in its karyotype, our data show that one specific type of X-chromosome variant is remarkably widespread, though rare. PMID:24260647

  16. Polybrominated diphenyl ethers and alternative flame retardants in air and precipitation samples from the northern Lake Victoria region, East Africa.

    PubMed

    Arinaitwe, Kenneth; Muir, Derek C G; Kiremire, Bernard T; Fellin, Phil; Li, Henrik; Teixeira, Camilla

    2014-01-01

    High volume air and precipitation samples were collected close to the shore of Lake Victoria at Entebbe, Uganda, between October 2008 and July 2010 inclusive. Polybrominated diphenyl ethers (PBDEs) and alternative flame retardants (AFRs) were analyzed by GC-MS. BDEs 47, 99, and 209 were the predominant PBDEs with mean concentrations (in air) of 9.84, 4.38, 8.27 pg m(-3) and mean fluxes in precipitation of 3.40, 6.23, and 7.82 ng m(-2) sample(-1), respectively. 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), and hexabromocyclododecane (HBCDD), anti- and syn-Dechlorane plus were detected at levels comparable with those of PBDEs. Both PBDEs and AFRs in air generally increased from 2008 to 2010. Elevated PBDE concentrations in air were associated with slow moving low altitude air masses from the region immediately adjacent to the lake, while low concentrations were mostly associated with fast moving westerly and southwesterly air masses. Analysis of the octa- and nona-BDE profiles suggested photolysis and pyrolytic debromination of BDE-209 in the air samples. The highly halogenated and most abundant PBDEs and AFRs in air also predominated in precipitation samples. This is the first study to report flame retardants in high volume air samples and precipitation in Equatorial Africa. PMID:24400732

  17. A preliminary study on the microzooplankton of Chilika Lake, a brackish water lagoon on the east coast of India.

    PubMed

    Sahu, Biraja Kumar; Srichandan, Suchismita; Panigrahy, R C

    2016-01-01

    Abundance and composition of microzooplankton in Chilika Lake were studied covering three seasons during 2012-2013. Ciliates (19 species), rotifers (13 species), crustacean larvae (2 taxa) and heterotrophic dinoflagellates (2 species) were the four major groups. Ciliates, however, have emerged as the most dominant group throughout the lake in all the seasons except in the freshwater-influenced areas. The average contribution of ciliates was highest (avg. 55.3?±?38.7 %) during the premonsoon season followed by post-monsoon (avg. 49.0?±?32.5 %) and monsoon (avg. 47.8?±?41.6 %) seasons. Crustacean larvae formed the second dominant group whose percentage contribution was marginally high in the premonsoon (avg. 41.2?±?38.8 %) followed by monsoon (avg. 29.1?±?27.0 %) and post-monsoon (avg. 28.7?±?23.4 %). Results of cluster analysis and multidimensional scaling on abundance of microzooplankton depicted well-defined clusters. The stations with high salinity formed a different group indicating seasonal variation in species composition and abundance of microzooplankton is primarily governed by salinity. PMID:26718950

  18. Monthly Weather Review Climatological Characteristics and Orographic Enhancement of Lake-Effect

    E-print Network

    Steenburgh, Jim

    Monthly Weather Review Climatological Characteristics and Orographic Enhancement of Lake-Effect Precipitation east of Lake Ontario and over the Tug Hill Plateau --Manuscript Draft-- Manuscript Number: Full Title: Climatological Characteristics and Orographic Enhancement of Lake-Effect Precipitation east

  19. Biogeochemical variability during the past 3.6 million years recorded by FTIR spectroscopy in the sediment record of Lake El'gygytgyn, Far East Russian Arctic

    NASA Astrophysics Data System (ADS)

    Meyer-Jacob, C.; Vogel, H.; Gebhardt, A. C.; Wennrich, V.; Melles, M.; Rosén, P.

    2014-01-01

    A number of studies have shown that Fourier transform infrared spectroscopy (FTIRS) can be applied to quantitatively assess lacustrine sediment constituents. In this study, we developed calibration models based on FTIRS for the quantitative determination of biogenic silica (BSi; n = 420; gradient: 0.9-56.5%), total organic carbon (TOC; n = 309; gradient: 0-2.9%), and total inorganic carbon (TIC; n= 152; gradient: 0-0.4%) in a 318 m-long sediment record with a basal age of 3.6 million years from Lake El'gygytgyn, Far East Russian Arctic. The developed partial least squares (PLS) regression models yield high cross-validated (CV) R2CV = 0.86-0.91 and low root mean square error of cross-validation (RMSECV) (3.1-7.0% of the gradient for the different properties). By applying these models to 6771 samples from the entire sediment record, we obtained detailed insight into bioproductivity variations in Lake El'gygytgyn throughout the middle to late Pliocene and Quaternary. High accumulation rates of BSi indicate a productivity maximum during the middle Pliocene (3.6-3.3 Ma), followed by gradually decreasing rates during the late Pliocene and Quaternary. The average BSi accumulation during the middle Pliocene was ~3 times higher than maximum accumulation rates during the past 1.5 million years. The indicated progressive deterioration of environmental and climatic conditions in the Siberian Arctic starting at ca. 3.3 Ma is consistent with the first occurrence of glacial periods and the finally complete establishment of glacial-interglacial cycles during the Quaternary.

  20. Regionalisation of the parameters of a conceptual water balance model for Lake Victoria basin in East Africa

    NASA Astrophysics Data System (ADS)

    Kizza, M.; Guerrero, J.; Rodhe, A.; Xu, C.

    2012-12-01

    Large parts of the globe are ungauged and even the numbers of gauged basins are declining very fast due to factors like insufficient funding, inadequate institutional frameworks, a lack of appreciation of the worth of long term data and, sometimes, political turmoil. The most common approach for predicting hydrological variables in ungauged basins is regionalisation whereby model parameters are transferred from gauged basins that are deemed similar to the target ungauged basin. In this study, WASMOD, a conceptual water balance model was applied to 9 gauged sub-basins in Lake Victoria basin in order to test the transferability of model parameters between the basins using three regionalisation approaches. The goal was to evaluate regionalisation methods that could be used for modelling catchment inflow into Lake Victoria. WASMOD model was calibrated within the GLUE framework for uncertainty assessment using Monte Carlo simulation with uniformly sampled parameter sets. Nash-Sutcliffe coefficients were used as the likelihoods. The analysis was carried out for the period 1967-2000. Parameter transferability was assessed by comparing the likelihood values of regionalised simulations with the values under calibration for each basin. The results showed that WASMOD performed well for all study sub-basins with NS values during calibration that ranged between 0.70 and 0.82. The transferability results were mixed. For the proxy-basin method, the best performing parameter donor basin was Mara with 4 proxy basins giving acceptable results. Sio, Sondu, Gucha and Duma also performed well. The global mean method gave acceptable performance for 7 of the 9 study basins. The ensemble regionalisation method provides the possibility to consider parameter uncertainty in the regionalisation. Ensemble regionalisation method performed best with an average departure of 40% from the observed mean annual flows compared to 48% and 60% for proxy-basin and global mean methods, respectively. The departure for calibrated mean monthly flow estimates was 26%.

  1. Diversity of the major capsid genes (g23) of T4-like bacteriophages in the eutrophic Lake Kotokel in East Siberia, Russia.

    PubMed

    Butina, Tatyana V; Belykh, Olga I; Potapov, Sergey A; Sorokovikova, Ekaterina G

    2013-07-01

    Numerous studies revealed high diversity of T4-like bacteriophages in various environments, but so far, little is known about T4-like virus diversity in freshwater bodies, particularly in eutrophic lakes. The present study was aimed at elucidating molecular diversity of T4-like bacteriophages in eutrophic Lake Kotokel located near Lake Baikal by partial sequencing of the major capsid genes (g23) of T4-like bacteriophages. The majority of g23 fragments from Lake Kotokel were most similar to those from freshwater lakes and paddy fields. Despite the proximity and direct water connection between Lake Kotokel and Lake Baikal, g23 sequence assemblages from two lakes were different. UniFrac analysis showed that uncultured T4-like viruses from Lake Kotokel tended to cluster with those from the distant lake of the same trophic status. This fact suggested that the trophic conditions affected the formation of viral populations, particularly of T4-like viruses, in freshwater environments. PMID:23539063

  2. The paleoenvironmental and climatic record of the Common Era in core sediments of Lake Abashiri in the east part of Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Seto, K.; Katsuki, K.; Yamada, K.; Sonoda, T.; Kawajiri, T.; Watanabe, T.

    2014-12-01

    In the coastal area of the Sea of Okhotsk in the east part of Hokkaido located to for subarctic zone, many brackish-water lakes are distributed. Lake Abashiri has a distinct halocline around 5m depths, and is divided into oligohaline epilimnion and polyhaline hypolimnion by its pycnocline. In this study, paleoenvironmental and climatic changes of the Common Era in Abashiri region is discussed by sedimentologic and geochemical high-resolution analysis of the sediment cores collected from the Lake Abashiri. The 13AB-B1 core collected from Lake Abashiri shows the length of 27m. This core is composed of muddy sediment with a distinct lamination up to 19.31m below surface. The Ta-a tephra (AD 1739), Ko-c2 tephra (AD 1694) and Ma-b tephra (10th century) are found at the horizon of 2.65m, 2.91m, and 6.19m below surface, respectively. Sedimentation rate based on these ages was 5.7mm/yr between Ko-c2 tephra and Ta-a tephra, and was 4.7mm/yr between Ma-b tephra and Ko-c2 tephra. The environment of bottom water indicates the anoxic and/or euxinic conditions during the Common Era. ?The result of observation used by Soft X-ray photograph, the lamina-set of high, low, intermediate density layers was observed. High-density layers have characteristics of low TOC, low SiO2, and high Al contents. This is suggested that high-density layer is formed by the supply of inorganic clastics. The lamina set of 44 was recognized between Ko-c2 tephra and Ta-a tephra in the 10AB-5C core. This is suggested that this set is annual lamina (varve). If its so, it is considered that high density layer indicate the high precipitation term of summer season judging from precipitation pattern in Abashiri Area during 100 years. Particularly, the year of flood events tend to show a thick and distinguished layer in lamina-set. The 13AB-B core is correlated with 10AB-5C core under the lamina level. The high-density lamina-set group is repeated with 20 to 30 year cycle. The horizon of high-density lamina-set group is correlated with the term showing several years continuously high precipitation. This lamina-set group is observed from 400 years ago, the climate system would have been continued. There seems to be high-low density cycle of some order before this time. It is consider that this cycle is related to the rainfall pattern over the medium to long term.

  3. Gas isotopic signatures (He, C, and Ar) in the Lake Kivu region (western branch of the East African rift system): Geodynamic and volcanological implications

    NASA Astrophysics Data System (ADS)

    Tedesco, D.; Tassi, F.; Vaselli, O.; Poreda, R. J.; Darrah, T.; Cuoco, E.; Yalire, M. M.

    2010-01-01

    On 17 January 2002, the city of Goma was partly destroyed by two of the several lava flows erupted from a roughly N-S oriented fracture system opened along the southern flank of Mount Nyiragongo (Democratic Republic of Congo), in the western branch of the East African rift system. A humanitarian and scientific response was promptly organized by international, governmental, and nongovernmental agencies coordinated by the United Nations and the European Union. Among the different scientific projects undertaken to study the mechanisms triggering this and possible future eruptions, we focused on the isotopic (He, C, and Ar) analysis of the magmatic-hydrothermal and cold gas discharges related to the Nyiragongo volcanic system, the Kivu and Virunga region. The studied area includes the Nyiragongo volcano, its surroundings, and peripheral areas inside and outside the rift. They have been subdivided into seven regions characterized by distinct 3He/4He (expressed as R/Rair) ratios and/or ?13C-CO2 values. The Nyiragongo summit crater fumaroles, whose R/Rair and ?13C-CO2 values are up to 8.73 and from -3.5‰ to -4.0‰ VPDB, respectively, show a clear mantle, mid-ocean ridge basalt (MORB)-like contribution. Similar mantle-like He isotopic values (6.5-8.3 R/Rair) are also found in CO2-rich gas emanations (mazukus) along the northern shoreline of Lake Kivu main basin, whereas the 13?C-CO2 values range from -5.3‰ to -6.8‰ VPDB. The mantle influence progressively decreases in (1) dissolved gases of Lake Kivu (2.6-5.5 R/Rair) and (2) the distal gas discharges within and outside the two sides of the rift (from 0.1 to 1.7 R/Rair). Similarly, ?13C-CO2 ratios of the peripheral gas emissions are lighter (from -5.9‰ to -11.6‰ VPDB) than those of the crater fumaroles. Therefore, the spatial distribution of He and C signatures in the Lake Kivu region is mainly produced by mixing of mantle-related (e.g., Nyiragongo crater fumaroles and/or mazukus gases) and crustal-related (e.g., gas discharges in the Archean craton) fluids. The CO2/3He ratio (up to 10 × 1010) is 1 order of magnitude higher than those found in MORB, and it is due to the increasing solubility of CO2 in the foiditic magma feeding the Nyiragongo volcano. However, the exceptionally high 40Ar*/4He ratio (up to 8.7) of the Nyiragongo crater fumaroles may be related to the difference between He and Ar solubility in the magmatic source. The results of the present investigation suggest that in this area the uprising of mantle-originated f luids seems strongly controlled by regional tectonics in relation to the geodynamic assessment of the rift. These fluids are mainly localized in a relatively small zone between Lake Kivu and Nyiragongo volcano, with important implications in terms of volcanic activity.

  4. GRACE water storage estimates for the Middle East and other regions with significant reservoir and lake storage

    NASA Astrophysics Data System (ADS)

    Longuevergne, L.; Wilson, C. R.; Scanlon, B. R.; Crétaux, J. F.

    2013-12-01

    While GRACE (Gravity Recovery and Climate Experiment) satellites are increasingly being used to monitor total water storage (TWS) changes globally, the impact of spatial distribution of water storage within a basin is generally ignored but may be substantial. In many basins, water is often stored in reservoirs or lakes, flooded areas, small aquifer systems, and other localized regions with areas typically below GRACE resolution (~200 000 km2). The objective of this study was to assess the impact of nonuniform water storage distribution on GRACE estimates of TWS changes as basin-wide averages, focusing on surface water reservoirs and using a priori information on reservoir storage from radar altimetry. Analysis included numerical experiments testing effects of location and areal extent of the localized mass (reservoirs) within a basin on basin-wide average water storage changes, and application to the lower Nile (Lake Nasser) and Tigris-Euphrates basins as examples. Numerical experiments show that by assuming uniform mass distribution, GRACE estimates may under- or overestimate basin-wide average water storage by up to a factor of ~2, depending on reservoir location and areal extent. Although reservoirs generally cover less than 1% of the basin area, and their spatial extent may be unresolved by GRACE, reservoir storage may dominate water storage changes in some basins. For example, reservoir storage accounts for ~95% of seasonal water storage changes in the lower Nile and 10% in the Tigris-Euphrates. Because reservoirs are used to mitigate droughts and buffer against climate extremes, their influence on interannual timescales can be large. For example, TWS decline during the 2007-2009 drought in the Tigris-Euphrates basin measured by GRACE was ~93 km3. Actual reservoir storage from satellite altimetry was limited to 27 km3, but their apparent impact on GRACE reached 45 km3, i.e., 50% of GRACE trend. Therefore, the actual impact of reservoirs would have been greatly underestimated (27 km3) if reservoir storage changes were assumed uniform in the basin. Consequently, estimated groundwater contribution from GRACE would have been largely overestimated in this region if the actual distribution of water was not explicitly taken into account. Effects of point masses on GRACE estimates are not easily accounted for via simple multiplicative scaling, but in many cases independent information may be available to improve estimates. Accurate estimation of the reservoir contribution is critical, especially when separating estimating groundwater storage changes from GRACE total water storage (TWS) changes. Because the influence of spatially concentrated water storage - and more generally water distribution - is significant, GRACE estimates will be improved by combining independent water mass spatial distribution information with GRACE observations, even when reservoir storage is not the dominant mechanism. In this regard, data from the upcoming Surface Water Ocean Topography (SWOT) satellite mission should be an especially important companion to GRACE-FO (Follow-On) observations.

  5. Distribution and exploitation of Nile perch Lates niloticus in relation to stratification in Lake Victoria, East Africa

    USGS Publications Warehouse

    Taabu-Munyaho, A.; Kayanda, Robert J.; Everson, Inigo; Grabowski, Timothy B.; Marteinsdóttir, Gudrún

    2013-01-01

    Stratification restricts habitable areas forcing fish to balance between favourable temperature and minimum dissolved oxygen requirements. Acoustic surveys conducted during the stratified and isothermal periods on tropical Lake Victoria indicated that stratification of temperature and dissolved oxygen (DO) affected vertical distribution of Nile perch. There was higher mean temperature (25.6 ± 0.5 °C) and lower DO (6.4 ± 1.8 mg/l) during stratified period compared to the isothermal period (mean temperature 24.9 ± 0.3 °C; mean DO 7.3 ± 0.6 mg/l). Higher mean densities of Nile perch were recorded in the coastal (0.44 ± 0.03) and deep (0.27 ± 0.02 g/m3) strata during the stratified compared to the isothermal season (coastal: 0.24 ± 0.01; deep: 0.12 ± 0.02 g/m3). In addition, Nile perch density in the upper 0–40 m depth layers in the coastal and deep strata increased by over 50% from the isothermal to the stratified season. Daily landings from 65 motorised fishing boats between October 2008 and September 2010 show higher mean catch (26.29 ± 0.17 kg/boat/day) during stratified compared to the isothermal (23.59 ± 0.15) season. Thermal stratification apparently compresses the habitat available to Nile perch and can potentially result in higher exploitation. Managers should evaluate the potential benefits of instituting closed seasons during the stratified period, and stock assessment models should take into account the seasonal niche compression.

  6. 42. Peaks of Otter, Abbott Lake. View across lake to ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    42. Peaks of Otter, Abbott Lake. View across lake to peaks of Outter Lodge, completed in 1964. Construction of the lake got underway in 1964. Looking east-northeast. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  7. 2. View west of spillway and abutment on Lake Whitney ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. View west of spillway and abutment on Lake Whitney Dam. - Lake Whitney Water Filtration Plant, Lake Whitney Dam, East side of Whitney Avenue near intersection with Armory Street, Hamden, New Haven County, CT

  8. 3. View north of spillway and abutment on Lake Whitney ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. View north of spillway and abutment on Lake Whitney Dam. - Lake Whitney Water Filtration Plant, Lake Whitney Dam, East side of Whitney Avenue near intersection with Armory Street, Hamden, New Haven County, CT

  9. 3. View northeast, west facade of Lake Forest (original Forest ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. View northeast, west facade of Lake Forest (original Forest Cottage structure incorporated into renamed structure) - Lake Placid Club, Forest Wing, East side of Mirror Lake Drive, North of State Route 86 & Main, North Elba, Essex County, NY

  10. 51. Third Floor, Lake Forest, west center room, looking west, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    51. Third Floor, Lake Forest, west center room, looking west, part of original Forest Cottage as of 1901. - Lake Placid Club, Forest Wing, East side of Mirror Lake Drive, North of State Route 86 & Main, North Elba, Essex County, NY

  11. 4. View southeast, west facade of Lake Forest (original Forest ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. View southeast, west facade of Lake Forest (original Forest Cottage structure incorporated into renamed structure) - Lake Placid Club, Forest Wing, East side of Mirror Lake Drive, North of State Route 86 & Main, North Elba, Essex County, NY

  12. 6. VIEW OF THREE BEARS LAKE, SHOWING WASHED UP 12' ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. VIEW OF THREE BEARS LAKE, SHOWING WASHED UP 12' x 12' DAM SUPPORT TIMBERS, LOOKING NORTHEAST FROM SOUTH SIDE OF LAKE - Three Bears Lake & Dams, North of Marias Pass, East Glacier Park, Glacier County, MT

  13. The Nyanza Project: Interdisciplinary Research Training In Tropical Lakes

    NASA Astrophysics Data System (ADS)

    Cohen, A. S.; Lezzar, K. E.; Michel, E.; O'Reilly, C. M.; Russell, J. M.; Nkotagu, H.; Kimirei, I.

    2005-12-01

    The Nyanza Project is a research training program for American and African students, run annually at Lake Tanganyika (LT), Tanzania. The Project`s objective is to provide undergraduates, graduate students and secondary school teachers with the skills to plan and conduct interdisciplinary research on various aspects of tropical lake studiees. At a time of rapid global change there is a pressing need for young scientists trained to investigate environmental processes in an interdisciplinary framework. Training students to understand long-term changes in water availability, water quality and the relationship of aquatic ecosystems to rapid climate change represents a critical element of this societal need. Waterbodies in the tropics are particularly useful proving grounds for training future researchers on the impacts of global change on natural waters, as they are very sensitive to environmental and climatic change. Moreover, they are likely to provide instructive bellwethers of changes to come in U.S. inland waters. Each year 17-22 undergraduates, 3-4 graduate students and one secondary school teacher are selected for the program from the US and Africa. To date (1998-2005), 89 undergraduate students, 24 graduate students, and 8 secondary school teachers from the US have participated through the Project`s NSF support and 58 African students (from Tanzania, Burundi, Zambia, Congo, Kenya, and Burkina Faso) have been funded to participate in the Nyanza Project through supporting grants from our non-NSF funding sources. The 7-week program comprises an initial two week intensive short course on all aspects of the LT system and project preparation period, followed by 5 weeks of directed research, written report preparation, and scientific meeting-styled presentations. Focal topics for Nyanza Project research include: 1) investigating East African paleoclimates using sediment cores and reflection seismic profiling, 2) mapping & interpreting the geologic structure and depositional processes on the lake`s floor and watersheds 3) studying the extremely diverse and largely endemic fish and invertebrate fauna found in the littoral zone of LT to understand species interactions, environmental controls on species distribution, and factors regulating species diversification, 4) understanding the linkages between short-term climate variability, internal circulation in the lake, nutrient availability, and productivity in the open water (pelagic) portion of LT, and 5) investigating the impacts of deforestation and soil erosion in the LT basin on lake and stream ecosystems. Given that the Nyanza Project primarily serves undergraduates it has been extremely productive in terms of research output, with 27 articles published/in press in peer reviewed journals/edited volumes, 73 presentations given at national or international scientific meetings (59% by student first authors) and 16 theses based on Nyanza work. Extended abstracts for all 100 student projects from 1998-2004 are available at our website. Alumni surveys indicate that the Nyanza Project has significantly changed past student`s approach to science and/or career directions.

  14. Planning applications in east central Florida. [resources management and planning, land use, and lake algal blooms in Brevard County from Skylab imagery

    NASA Technical Reports Server (NTRS)

    Hannah, J. W.; Thomas, G. L.; Esparza, F. (principal investigators)

    1973-01-01

    The author has identified the following significant results. Lake Apopka and three lakes downstream of it (Dora, Eustis, and Griffin) are in an advanced state of eutrophication with high algal concentrations. This feature has shown up consistently on ERTS-1 images in the form of a characteristic water color for those lakes. As expected, EREP photographs also show a characteristic color for those lakes. What was not expected is that Lake Griffin shows a clear pattern of this coloration. Personnel familiar with the lake believe that the photograph does, indeed, show an algal bloom. It is reported that the algal concentration is often significantly higher in the southern portion of the lake. What the photograph shows that was not otherwise known is the pattern of the algal bloom. A similar, but less pronounced, effect is seen in Lake Tohopekaliga. Personnel stationed at Kissimmee reported that there was an algal bloom on that lake at the time of the EREP pass and that its extent corresponded approximately to that shown on the photograph. Again, the EREP photograph gives information about the extent of the bloom that could not be obtained practically by sampling. ERTS-1 images give some indication of this algal distribution on Lake Griffin in some cases, but are inconclusive.

  15. Evolution of opercle shape in cichlid fishes from Lake Tanganyika - adaptive trait interactions in extant and extinct species flocks.

    PubMed

    Wilson, Laura A B; Colombo, Marco; Sánchez-Villagra, Marcelo R; Salzburger, Walter

    2015-01-01

    Phenotype-environment correlations and the evolution of trait interactions in adaptive radiations have been widely studied to gain insight into the dynamics underpinning rapid species diversification. In this study we explore the phenotype-environment correlation and evolution of operculum shape in cichlid fishes using an outline-based geometric morphometric approach combined with stable isotope indicators of macrohabitat and trophic niche. We then apply our method to a sample of extinct saurichthyid fishes, a highly diverse and near globally distributed group of actinopterygians occurring throughout the Triassic, to assess the utility of extant data to inform our understanding of ecomorphological evolution in extinct species flocks. A series of comparative methods were used to analyze shape data for 54 extant species of cichlids (N?=?416), and 6 extinct species of saurichthyids (N?=?44). Results provide evidence for a relationship between operculum shape and feeding ecology, a concentration in shape evolution towards present along with evidence for convergence in form, and significant correlation between the major axes of shape change and measures of gut length and body elongation. The operculum is one of few features that can be compared in extant and extinct groups, enabling reconstruction of phenotype-environment interactions and modes of evolutionary diversification in deep time. PMID:26584885

  16. Evolution of opercle shape in cichlid fishes from Lake Tanganyika - adaptive trait interactions in extant and extinct species flocks

    PubMed Central

    Wilson, Laura A. B.; Colombo, Marco; Sánchez-Villagra, Marcelo R.; Salzburger, Walter

    2015-01-01

    Phenotype-environment correlations and the evolution of trait interactions in adaptive radiations have been widely studied to gain insight into the dynamics underpinning rapid species diversification. In this study we explore the phenotype-environment correlation and evolution of operculum shape in cichlid fishes using an outline-based geometric morphometric approach combined with stable isotope indicators of macrohabitat and trophic niche. We then apply our method to a sample of extinct saurichthyid fishes, a highly diverse and near globally distributed group of actinopterygians occurring throughout the Triassic, to assess the utility of extant data to inform our understanding of ecomorphological evolution in extinct species flocks. A series of comparative methods were used to analyze shape data for 54 extant species of cichlids (N?=?416), and 6 extinct species of saurichthyids (N?=?44). Results provide evidence for a relationship between operculum shape and feeding ecology, a concentration in shape evolution towards present along with evidence for convergence in form, and significant correlation between the major axes of shape change and measures of gut length and body elongation. The operculum is one of few features that can be compared in extant and extinct groups, enabling reconstruction of phenotype-environment interactions and modes of evolutionary diversification in deep time. PMID:26584885

  17. View of building 11050, showing metal clad addition on east ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of building 11050, showing metal clad addition on east elevation, looking southwest. - Naval Ordnance Test Station Inyokern, China Lake Pilot Plant, Machine Shop, C Street, China Lake, Kern County, CA

  18. View of building 11050, showing two additions on east and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of building 11050, showing two additions on east and north side. Looking southwest. - Naval Ordnance Test Station Inyokern, China Lake Pilot Plant, Machine Shop, C Street, China Lake, Kern County, CA

  19. Oblique view of building 11050, showing east and south sides, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Oblique view of building 11050, showing east and south sides, looking northwest. - Naval Ordnance Test Station Inyokern, China Lake Pilot Plant, Fire Station & Marine Barracks, D Street, at corner of 4th Street, China Lake, Kern County, CA

  20. ARTICLE OPEN doi:10.1038/nature13726

    E-print Network

    ,4 & Federica Di Palma1,27 Cichlid fishes are famous for large, diverse and replicated adaptive radiations in the Great Lakes of East Africa. To under- stand themolecular mechanisms underlying cichlid: Neolamprologus brichardi/pulcher (older radiation, Lake Tanganyika), Metriaclima zebra(recentradiation,Lake

  1. Origin and palaeoenvironmental significance of C25 and C27n-alk-1-enes in a 25,000-year lake-sedimentary record from equatorial East Africa

    NASA Astrophysics Data System (ADS)

    van Bree, L. G. J.; Rijpstra, W. I. C.; Cocquyt, C.; Al-Dhabi, N. A.; Verschuren, D.; Sinninghe Damsté, J. S.; de Leeuw, J. W.

    2014-11-01

    We studied the distribution of long-chain alkenes (n-C23 to n-C31) in well-dated sediments from Lake Challa, a deep crater lake near Mt. Kilimanjaro in equatorial East Africa, to reveal signatures of palaeo-environmental and palaeo-climatic changes affecting the production of these compounds during the last 25 kyr. The apolar fractions of organic sediment extracts dated to the last 16 kyr showed an unusual dominance of ?13C-depleted n-C25:1 and n-C27:1 alk-1-enes. These alkenes were not detected in soil and litter from near the shoreline and from the inner rim of the crater, pointing to an autochthonous, aquatic source. Analysis of suspended particulate matter indicated that the n-alk-1-enes are produced in the well-oxygenated upper 30 m of the water column, indicating a phytoplanktonic origin. Sedimenting particles collected monthly from December 2006 to November 2007 showed increased fluxes of n-alk-1-enes following the locally prominent short rain season in November-December. Green algae and/or cyanobacteria were identified as candidate sources of these alkenes. Production of the n-C25:1 and n-C27:1 alkenes in Lake Challa was much reduced during the Last Glacial Maximum and early late-glacial period, suggesting a temperature or CO2 effect on habitat suitability. We explored the potential of n-alk-1-ene accumulation rates, and of a derived Alkene Index [n-C27:1]/([n-C25:1] + [n-C27:1]), to record longer-term climatic changes. The Alkene Index record of Lake Challa over the past 25 kyr shows clear periodicity with a dominant frequency of ?2.3 kyr, potentially indicative of monsoon variability directly or indirectly forced by variation in solar radiation.

  2. 5. EAST SPAN, FROM SOUTH, SHOWING STRUCTURAL CONFIGURATION, INCLUDING POLYGONAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. EAST SPAN, FROM SOUTH, SHOWING STRUCTURAL CONFIGURATION, INCLUDING POLYGONAL TOP CHORD, TRUSS PANELS, EAST ABUTMENT, AND CENTRAL PIER - Glendale Road Bridge, Spanning Deep Creek Lake on Glendale Road, McHenry, Garrett County, MD

  3. Causes of Late Pleistocene water level change in Lake Victoria, Equatorial East Africa, derived from clumped isotopes of land snails and fresh water mollusks. (Invited)

    NASA Astrophysics Data System (ADS)

    Zaarur, S.; Affek, H. P.; Tryon, C.; Peppe, D. J.; Faith, J.

    2013-12-01

    Carbonate clumped isotope thermometry is based on the dependence of 13C-18O bond abundance in the carbonate lattice (measured as ?47) on the carbonate formation temperature. Most marine and freshwater biogenic carbonates are found to be in agreement with the clumped isotopes - temperature calibration. Clumped isotope thermometry is particularly useful in terrestrial environments where the interpretation of carbonate ?18O is limited due to difficulty in estimating the paleo-water isotopic composition. Clumped isotope-derived temperatures from land snails are generally higher than the ambient environmental temperatures, but show no evidence for disequilibrium. We attribute these higher body temperatures to snail eco-physiological adaptations through shell color, morphology, and behavior. We use the clumped isotope-derived temperatures in combination with shell ?18O to calculate snail body water ?18O composition. This parameter is interpreted as a paleo-hydrological indicator that reflects the isotopic composition of local precipitation modified by local evaporation. Rusinga and Mfangano Islands in Lake Victoria provide a unique opportunity to compare extant species of modern and fossil freshwater mollusks and land snails from the same location to examine lake paleo-hydrology. This location is particularly interesting as Lake Victoria itself is the main source of rain-water in the region such that the isotopic composition of land snail body water can be related back to the source waters. We combine clumped isotope and oxygen isotope measurements of both freshwater mollusks and land snails to examine the water balance of the lake, testing hypotheses about the mechanism of a significant rise in lake level in Lake Victoria ~35 - 40 ka BP. Outcrops of paleo-beach deposits ~18 m above the modern day lake level indicate high water stands at ~35-40 ka BP. Based on water balance models for Lake Victoria, an increase in lake level of this magnitude could be driven by local mean annual precipitation that is significantly greater than modern. However, this is inconsistent with regional climate reconstructions. This suggests that either lake level was controlled by non-climatic factors, or that local climate in the Lake Victoria basin was different than regional patterns of climate across eastern Africa. We use oxygen and clumped isotopes of modern and fossil shells (Corbicula sp., Melanoides sp. and Bellamya unicolor) from this 18 m beach outcrop on Mfangano Island to (1) compare with modern lake water ?18O values and (2) calculate paleo-water compositions. We combine these results with calculated snail body water ?18O composition (using oxygen and clumped isotopes) of land snails (Limicoloria cf. martensiana) from Rusinga and Mfangano Islands, to study hydrological changes of Lake Victoria. We use these data to evaluate the relative importance of climate change and tectonics as mechanisms for the Late Pleistocene expansion of Lake Victoria.

  4. 2. DETAIL VIEW SHOWING WOODEN CRIBBING WITH LOWERED LAKE LEVEL, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. DETAIL VIEW SHOWING WOODEN CRIBBING WITH LOWERED LAKE LEVEL, EAST DAM, LOOKING NORTHEAST (View is middle of the perimeter showing in MT-88-A-1 above.) - Three Bears Lake & Dams, East Dam, North of Marias Pass, East Glacier Park, Glacier County, MT

  5. Holocene climate and environmental change in north-eastern Kamchatka (Russian Far East), inferred from a multi-proxy study of lake sediments

    NASA Astrophysics Data System (ADS)

    Andrén, Elinor; Klimaschewski, Andrea; Self, Angela E.; St. Amour, Natalie; Andreev, Andrei A.; Bennett, Keith D.; Conley, Daniel J.; Edwards, Thomas W. D.; Solovieva, Nadia; Hammarlund, Dan

    2015-11-01

    A sediment record from a small lake in the north-eastern part of the Kamchatka Peninsula has been investigated in a multi-proxy study to gain knowledge of Holocene climatic and environmental change. Pollen, diatoms, chironomids and selected geochemical parameters were analysed and the sediment record was dated with radiocarbon. The study shows Holocene changes in the terrestrial vegetation as well as responses of the lake ecosystem to catchment maturity and multiple stressors, such as climate change and volcanic eruptions. Climate change is the major driving force resulting in the recorded environmental changes in the lake, although recurrent tephra deposition events also contributed. The sediment record has an age at the base of about 10,000 cal yrs BP, and during the first 400 years the climate was cold and the lake exhibited extensive ice-cover during winter and relatively low primary production. Soils in the catchment were poor with shrub alder and birches dominating the vegetation surrounding the lake. At about 9600-8900 cal yrs BP the climate was cold and moist, and strong seasonal wind stress resulted in reduced ice-cover and increased primary production. After ca. 8900 cal yrs BP the forest density increased around the lake, runoff decreased in a generally drier climate resulting in decreased primary production in the lake until ca. 7000 cal yrs BP. This generally dry climate was interrupted by a brief climatic perturbation, possibly attributed to the 8.2 ka event, indicating increasingly windy conditions with thick snow cover, reduced ice-cover and slightly elevated primary production in the lake. The diatom record shows maximum thermal stratification at ca. 6300-5800 cal yrs BP and indicates together with the geochemical proxies a dry and slightly warmer climate resulting in a high productive lake. The most remarkably change in the catchment vegetation occurred at ca. 4200 cal yrs BP in the form of a conspicuous increase in Siberian dwarf pine (Pinus pumila), indicating a shift to a cooler climate with a thicker and more long-lasting snow cover. This vegetational change was accompanied by marked shifts in the diatom and chironomid stratigraphies, which are also indicative of colder climate and more extensive ice-cover.

  6. Development of an Assessment Tool for Agricultural Best Management Practice Implementation in the Great Lakes Restoration Initiative Priority Watersheds—Upper East River, Tributary to Green Bay, Wisconsin

    USGS Publications Warehouse

    Merriman, Katherine R.

    2015-01-01

    The Great Lakes face a number of serious challenges that cause damage to water quality, habitat, ecology, and coastal health. Excess nutrients from point and nonpoint sources have a history of causing harmful algal blooms (HABs); since the late 1990s, a resurgence of HABs have forced beach closures and resulted in water quality impairments across the Great Lakes. Studies increasingly point to phosphorus (P) runoff from agricultural lands as the cause of these HABs. In 2010, the Great Lakes Restoration Initiative (GLRI) was launched to revitalize the Great Lakes. The GLRI aims to address the challenges facing the Great Lakes and provide a framework for restoration and protection. As part of this effort, the Priority Watersheds Work Group (PWWG), cochaired by the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Agriculture-Natural Resources Conservation Service (USDA–NRCS), is targeting Priority Watersheds (PWs) to reduce the amount of P reaching the Great Lakes. Within the PWs, USDA–NRCS identifies small-scale subbasins with high concentrations of agriculture for coordinated nutrient reduction efforts and enhanced monitoring and modeling. The USDA–NRCS supplies financial and/or technical assistance to producers to install or implement best management practices (BMPs) to lessen the negative effects of agriculture to water quality; additional funding is provided by the GLRI through USDA–NRCS to saturate the small-scale subbasins with BMPs. The watershed modeling component, introduced in this fact sheet, assesses the effectiveness of USDA–NRCS funded BMPs, and nutrient reductions because of GLRI or other funding programs are differentiated. Modeling scenarios consider BMPs that have already been applied and those planned to be implemented across the small-scale subbasins.

  7. Preliminary analysis of the role of lake basin morphology on the modern diatom flora in the Ruby Mountains and East Humboldt Range, Nevada, USA

    USGS Publications Warehouse

    Starratt, Scott W.

    2014-01-01

    As paleolimnologists, we often look at the world through a 5-cm-diameter hole in the bottom of a lake, and although a number of studies have shown that a single core in the deepest part of a lake does not necessarily reflect the entire diatom flora, time and money often limit our ability to collect more than one core from a given site. This preliminary study is part of a multidisciplinary research project to understand Holocene climate variability in alpine regions of the Great Basin, and ultimately, to compare these high elevation records to the better studied pluvial records from adjacent valleys, in this case, the Ruby Valley.

  8. Biogeochemical properties and diagenetic changes during the past 3.6 Ma recorded by FTIR spectroscopy in the sediment record of Lake El'gygytgyn, Far East Russian Arctic

    NASA Astrophysics Data System (ADS)

    Meyer-Jacob, C.; Vogel, H.; Melles, M.; Rosén, P.

    2013-05-01

    A number of studies have shown that Fourier transform infrared spectroscopy (FTIRS) can be applied to quantitatively assess lacustrine sediment constituents. In this study, we developed calibration models based on FTIRS for the quantitative determination of biogenic silica (BSi; n = 420; gradient: 0.9-56.5%), total organic carbon (TOC; n = 309; gradient: 0.02-2.89%), and total inorganic carbon (TIC; n = 153; gradient: 0.01-1.46%) in a 318 m long sediment record with a basal age of 3.6 Ma from Lake El'gygytgyn, Far East Russian Arctic. The developed partial least squares regression (PLSR) models yield high cross-validated (CV) R2CV = 0.85-0.91 and low root mean square error of cross-validation (RMSECV) (2.1-4.3% of the gradient for the different properties). The FTIRS-inferred concentrations of BSi, TOC, and TIC provide an initial insight into the climatic and environmental evolution at Lake El'gygytgyn throughout the late Pliocene and Quaternary showing a considerably high bioproductivity in the lake ecosystem between ~ 3.27-3.54 Ma during the early Pliocene warm period. Moreover, we found that the recorded FTIR spectra contain information on sample burial depth as a result of diagenetic changes (dehydration/dehydroxilation) of certain mineral phases. Despite the indicated post-depositional processes, the calibration models yield good statistical performances showing that general FTIRS models can be developed for several hundred meters long records extending several million years back in time. Our results highlight FTIRS to be a rapid, cost-effective alternative to conventional methods for quantification of biogeochemical properties.

  9. 3. AERIAL VIEW OF THREE BEARS LAKE, SHOWING OUTLET STREAM, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. AERIAL VIEW OF THREE BEARS LAKE, SHOWING OUTLET STREAM, BURLINGTON NORTHERN TRACKS, AND U.S. HIGHWAY 2, LOOKING NORTHEAST - Three Bears Lake & Dams, North of Marias Pass, East Glacier Park, Glacier County, MT

  10. East Siberian Sea, Russia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The winter sea ice in the east Siberian Sea is looking a bit like a cracked windshield in these true-color Moderate Resolution Imaging Spectroradiometer (MODIS) images from June 16 and 23, 2002. North of the thawing tundra, the sea ice takes on its cracked, bright blue appearance as it thins, which allows the reflection of the water to show through. Numerous still-frozen lakes dot the tundra. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  11. Short-term variability in the sedimentary BIT index of Lake Challa, East Africa over the past 2200 years: validating the precipitation proxy

    NASA Astrophysics Data System (ADS)

    Buckles, L. K.; Weijers, J. W. H.; Verschuren, D.; Cocquyt, C.; Sinninghe Damsté, J. S.

    2015-04-01

    The branched vs. isoprenoid index of tetraethers (BIT index) in Lake Challa sediments has been applied as a monsoon precipitation proxy on the assumption that the primary source of branched tetraether lipids (brGDGTs) was soil washed in from the lake's catchment. However, water column production has since been identified as the primary source of brGDGTs in Lake Challa, meaning that there is no longer a clear mechanism linking BIT index variation and precipitation. Here we investigate BIT index variation and GDGT concentrations at a decadal resolution over the past 2200 years, in combination with GDGT data from profundal surface sediments and 45 months of sediment-trap deployment. The 2200 year record reveals high-frequency variability in GDGT concentrations, and therefore the BIT index. Also surface sediments collected in January 2010 show a distinct shift in GDGT composition relative to those collected in August 2007. Increased bulk flux of settling particles with high Ti / Al ratios during March-April 2008 reflect an event of high detrital input to Lake Challa, concurrent with intense precipitation at the onset of the principal rain season that year. Although brGDGT distributions in the settling material are initially unaffected, this soil erosion event is succeeded by a large diatom bloom in July-August 2008 and a concurrent increase in GDGT-0 fluxes. Near-zero crenarchaeol fluxes indicate that no thaumarchaeotal bloom developed during the subsequent austral summer season; instead a peak in brGDGT fluxes is observed in December 2008. We suggest that increased nutrient availability, derived from eroded soil washed into the lake, stimulated both diatom productivity and the GDGT-0 producing archaea which help decompose dead diatoms passing through the suboxic zone of the water column. This disadvantaged the Thaumarchaeota that normally prosper during the following austral summer. Instead, a bloom of supposedly heterotrophic brGDGT-producing bacteria occurred. Episodic recurrence of such high soil-erosion events, integrated over multi-decadal and longer timescales and possibly enhanced by other mechanisms generating low BIT index values in dry years, can explain the positive relationship between the sedimentary BIT index and monsoon precipitation at Lake Challa. However, application elsewhere requires ascertaining the local situation of lacustrine brGDGT production and of variables affecting the productivity of Thaumarchaeota.

  12. Evolution of Lacustrine Environments on Mars and Their Significance: The Case for the Brazos Lakes and East Terra Meridiani Basins as Landing Sites for Surveyor 2001

    NASA Technical Reports Server (NTRS)

    Cabrol, N. A.; Grin, E. A.

    1999-01-01

    Ancient Martian lacustrine environments must be considered as primary targets to explore on Mars. Terrestrial studies show that lakes are exceptional sites to keep the record of the evolution of climate, geology, water and life. Finding this record is also the principal objective of the Mars Surveyor Program. This record encompasses changes at local, regional and global scales. Lacustrine sediments provide critical information about all events occurring in the lake catchment area. They are also a locus of complex chemical processes, concentration for life and favorable sites for fossilization processes to take place. We proposed two candidate-sites in the Schiaparelli Crater region responding to this high-priority scientific objective at the June 1999 meeting in Buffalo, NY. The two sites are located in the Sinus Sabeus quadrangle, are well documented by MOC images, and are among the best evidence yet of a Martian past lacustrine activity. We develop their case as high-priority sites for the 01' mission.

  13. Origins of Shared Genetic Variation in African Cichlids Yong-Hwee E. Loh,1

    E-print Network

    Kocher, Thomas D.

    Aimee E. Howe,5 Federica Di Palma,5 Kerstin Lindblad-Toh,6 Jody Hey,8 Ole Seehausen,2,3 Walter diversity in the waters of East Africa. Within each of the Great Lakes Tanganyika, Malawi, and Victoria cichlid assemblages. A set of approximately 200 genic and nongenic SNPs was ascertained in five Lake

  14. Lake Life.

    ERIC Educational Resources Information Center

    Ohrn, Deborah Gore, Ed.

    1993-01-01

    This quarterly publication of the State Historical Society of Iowa features articles and activities for elementary school students. This summer issue focuses on the topic of lake life. The issue includes the following features: (1) "Where the Lakes Are Map"; (2) "Letter from the Lake"; (3) "Lake People"; (4) "Spirit Lake"; (5) "Lake Manawa"; (6)…

  15. Crater Lake revealed

    USGS Publications Warehouse

    Ramsey, David W.; Dartnell, Peter; Bacon, Charles R.; Robinson, Joel E.; Gardner, James V.

    2003-01-01

    Around 500,000 people each year visit Crater Lake National Park in the Cascade Range of southern Oregon. Volcanic peaks, evergreen forests, and Crater Lake’s incredibly blue water are the park’s main attractions. Crater Lake partially fills the caldera that formed approximately 7,700 years ago by the eruption and subsequent collapse of a 12,000-foot volcano called Mount Mazama. The caldera-forming or climactic eruption of Mount Mazama drastically changed the landscape all around the volcano and spread a blanket of volcanic ash at least as far away as southern Canada. Prior to the climactic event, Mount Mazama had a 400,000 year history of cone building activity like that of other Cascade volcanoes such as Mount Shasta. Since the climactic eruption, there have been several less violent, smaller postcaldera eruptions within the caldera itself. However, relatively little was known about the specifics of these eruptions because their products were obscured beneath Crater Lake’s surface. As the Crater Lake region is still potentially volcanically active, understanding past eruptive events is important to understanding future eruptions, which could threaten facilities and people at Crater Lake National Park and the major transportation corridor east of the Cascades. Recently, the lake bottom was mapped with a high-resolution multibeam echo sounder. The new bathymetric survey provides a 2m/pixel view of the lake floor from its deepest basins virtually to the shoreline. Using Geographic Information Systems (GIS) applications, the bathymetry data can be visualized and analyzed to shed light on the geology, geomorphology, and geologic history of Crater Lake.

  16. 24. LOGAN LOOP LOOKING EAST, NORTH SIDE (Buildings No. 13, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. LOGAN LOOP LOOKING EAST, NORTH SIDE (Buildings No. 13, 12, 11, 10) (Copy negative made from National Archives negative No. 92-F-61A-4) - Fort Sheridan, 25 miles Northeast of Chicago, on Lake Michigan, Lake Forest, Lake County, IL

  17. 16. LOGAN LOOP LOOKING EAST, NORTH AND SOUTH SIDES (Buildings ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. LOGAN LOOP LOOKING EAST, NORTH AND SOUTH SIDES (Buildings No. 13, 12, 11, 10, 3, 4, 5, 6) (Copy negative made from National Archives negative No. 92-F-61A-6) - Fort Sheridan, 25 miles Northeast of Chicago, on Lake Michigan, Lake Forest, Lake County, IL

  18. A pharyngeal jaw evolutionary innovation facilitated extinction in Lake Victoria cichlids.

    PubMed

    McGee, Matthew D; Borstein, Samuel R; Neches, Russell Y; Buescher, Heinz H; Seehausen, Ole; Wainwright, Peter C

    2015-11-27

    Evolutionary innovations, traits that give species access to previously unoccupied niches, may promote speciation and adaptive radiation. Here, we show that such innovations can also result in competitive inferiority and extinction. We present evidence that the modified pharyngeal jaws of cichlid fishes and several marine fish lineages, a classic example of evolutionary innovation, are not universally beneficial. A large-scale analysis of dietary evolution across marine fish lineages reveals that the innovation compromises access to energy-rich predator niches. We show that this competitive inferiority shaped the adaptive radiation of cichlids in Lake Tanganyika and played a pivotal and previously unrecognized role in the mass extinction of cichlid fishes in Lake Victoria after Nile perch invasion. PMID:26612951

  19. Insight into the geology of the East Antarctic hinterland: a study of sediment inclusions from ice cores of the Lake Vostok borehole

    USGS Publications Warehouse

    Leitchenkov, G.L.; Belyatsky, B.V.; Rodionov, N.V.; Sergeev, S.A.

    2007-01-01

    refrozen from the lake water. This ice layer contains random sediment inclusions, eight of which have been studied using state-of the-art analytical techniques. Six inclusions comprise soft aggregates consisting mainly of clay-mica minerals and micron-sized quartz grains while two others are solid clasts of fine-grained cemented rocks. The largest rock clast consists of poorly-rounded quartz and minor amounts of accessory minerals and is classified as quartzose siltstone. More than twenty grains of zircon and monazite have been identified in this siltstone and dated by SIMS SHRIMP-II. Two age clusters have been recognized for these detrital grains, in the ranges 0.8?1.2 Ga and 1.6?1.8 Ga. The compositions of the rock clasts suggest that the bedrock situated to the west of Lake Vostok is sedimentary. The age data on the detrital accessory minerals suggest that the provenance of these sedimentary rocks ? the Gamburtsev Mountains and Vostok Subglacial Highlands, is mainly represented by Paleoproterozoic and MesoproterozoicNeoproterozoic crustal provinces

  20. 6. VIEW OF NORTH END OF EAST DAM, LOOKING SOUTH. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. VIEW OF NORTH END OF EAST DAM, LOOKING SOUTH. (View is taken from lakeside with lowered water level. This view encompasses the same area as MT-88-A-5 above.) - Three Bears Lake & Dams, East Dam, North of Marias Pass, East Glacier Park, Glacier County, MT

  1. SHRIMP-RG U-Pb isotopic systematics of zircon from the Angel Lake orthogneiss, East Humboldt Range, Nevada: is this really Archean crust? REPLY

    USGS Publications Warehouse

    Premo, Wayne R.

    2010-01-01

    The comments from McGrew and Snoke are well received and their concerns for the interpretations in our paper (Premo et al., 2008), which questions the original contention that the Angel Lake orthogneiss is an Archean rock, are many and varied—all of which we will attempt to address. As they point out, this issue is an important one as this particular crustal exposure may delimit the southwestern extent of the Archean Wyoming province (Foster et al., 2006; Mueller and Frost, 2006), which has implications for the true crustal evolution of this region of the Great Basin and perhaps more importantly its relationship (if any) to the location of the world-class gold deposits of north-central Nevada (e.g., Howard, 2003).

  2. Water Hyacinth Eichhornia crassipes (Mart.) Solms-Laubach Dynamics and Succession in the Nyanza Gulf of Lake Victoria (East Africa): Implications for Water Quality and Biodiversity Conservation

    PubMed Central

    Gichuki, John; Omondi, Reuben; Boera, Priscillar; Okorut, Tom; Matano, Ally Said; Jembe, Tsuma; Ofulla, Ayub

    2012-01-01

    This study, conducted in Nyanza Gulf of Lake Victoria, assessed ecological succession and dynamic status of water hyacinth. Results show that water hyacinth is the genesis of macrophyte succession. On establishment, water hyacinth mats are first invaded by native emergent macrophytes, Ipomoea aquatica Forsk., and Enydra fluctuans Lour., during early stages of succession. This is followed by hippo grass Vossia cuspidata (Roxb.) Griff. in mid- and late stages whose population peaks during climax stages of succession with concomitant decrease in water hyacinth biomass. Hippo grass depends on water hyacinth for buoyancy, anchorage, and nutrients. The study concludes that macrophyte succession alters aquatic biodiversity and that, since water hyacinth infestation and attendant succession are a symptom of broader watershed management and pollution problems, aquatic macrophyte control should include reduction of nutrient loads and implementing multifaceted approach that incorporates biological agents, mechanical/manual control with utilization of harvested weed for cottage industry by local communities. PMID:22619574

  3. Complete genome sequence of the halophilic bacterium Spirochaeta africana type strain (Z-7692T) from the alkaline Lake Magadi in the East African Rift

    SciTech Connect

    Liolios, Konstantinos; Abt, Birte; Scheuner, Carmen; Teshima, Hazuki; Held, Brittany; Lapidus, Alla L.; Nolan, Matt; Lucas, Susan; Deshpande, Shweta; Cheng, Jan-Fang; Tapia, Roxanne; Goodwin, Lynne A.; Pitluck, Sam; Pagani, Ioanna; Ivanova, N; Mavromatis, K; Mikhailova, Natalia; Huntemann, Marcel; Pati, Amrita; Chen, Amy; Palaniappan, Krishna; Land, Miriam L; Rohde, Manfred; Tindall, Brian; Detter, J. Chris; Goker, Markus; Bristow, James; Eisen, Jonathan; Markowitz, Victor; Hugenholtz, Philip; Woyke, Tanja; Klenk, Hans-Peter; Kyrpides, Nikos C

    2013-01-01

    Spirochaeta africana Zhilina et al. 1996 is an anaerobic, aerotolerant, spiral-shaped bacte- rium that is motile via periplasmic flagella. The type strain of the species, Z-7692T, was iso- lated in 1993 or earlier from a bacterial bloom in the brine under the trona layer in a shallow lagoon of the alkaline equatorial Lake Magadi in Kenya. Here we describe the features of this organism, together with the complete genome sequence, and annotation. Considering the pending reclassification of S. caldaria to the genus Treponema, S. africana is only the second 'true' member of the genus Spirochaeta with a genome-sequenced type strain to be pub- lished. The 3,285,855 bp long genome of strain Z-7692T with its 2,817 protein-coding and 57 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

  4. View of the Salt Lake City, Utah area

    NASA Technical Reports Server (NTRS)

    1973-01-01

    An oblique view of the Salt Lake City, Utah area as photographed from Earth orbit by one of the six lenses of the Itek-furnished S190-A Multispectral Photographic Facility Experiment aboard the Skylab space station. Approximately two-thirds of the Great Salt Lake is in view. The smaller body of water south of Salt Lake City is Utah Lake. The Wasatch Range is on the east side of the Great Salt Lake.

  5. Digital data sets that describe aquifer characteristics of the alluvial and terrace deposits along the North Canadian River from Oklahoma City to Eufaula Lake in east-central Oklahoma

    USGS Publications Warehouse

    Adams, G.P.; Runkle, Donna; Rea, Alan; Becker, C.J.

    1997-01-01

    ARC/INFO export and nonproprietary format files This diskette contains digitized aquifer boundaries and maps of of hydraulic conductivity, recharge, and ground-water level elevation contours for the alluvial and terrace deposits along the North Canadian River from Oklahoma City to Eufaula Lake in east-central Oklahoma. Ground water in 710 square miles of Quaternary-age alluvial and terrace deposits along the North Canadian River is an important source of water for irrigation, industrial, municipal, stock, and domestic supplies. The aquifer, composed of alluvial and terrace deposits, consists of sand, silt, clay, and gravel. The aquifer is underlain and in hydraulic connection with the upper zone of the Permian-age Garber-Wellington aquifer and the Pennsylvanian-age Ada-Vamoosa aquifer. Most of the lines in the four digital data sets were digitized from a published ground-water modeling report but portions of the aquifer boundary data set was extracted from published digital geologic data sets. Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may produce similar results. Therefore, values of hydraulic conductivity and recharge used in the model and presented in this data set are not precise, but are within a reasonable range when compared to independently collected data.

  6. Microbiology of Lonar Lake and other soda lakes

    PubMed Central

    Paul Antony, Chakkiath; Kumaresan, Deepak; Hunger, Sindy; Drake, Harold L; Murrell, J Colin; Shouche, Yogesh S

    2013-01-01

    Soda lakes are saline and alkaline ecosystems that are believed to have existed throughout the geological record of Earth. They are widely distributed across the globe, but are highly abundant in terrestrial biomes such as deserts and steppes and in geologically interesting regions such as the East African Rift valley. The unusual geochemistry of these lakes supports the growth of an impressive array of microorganisms that are of ecological and economic importance. Haloalkaliphilic Bacteria and Archaea belonging to all major trophic groups have been described from many soda lakes, including lakes with exceptionally high levels of heavy metals. Lonar Lake is a soda lake that is centered at an unusual meteorite impact structure in the Deccan basalts in India and its key physicochemical and microbiological characteristics are highlighted in this article. The occurrence of diverse functional groups of microbes, such as methanogens, methanotrophs, phototrophs, denitrifiers, sulfur oxidizers, sulfate reducers and syntrophs in soda lakes, suggests that these habitats harbor complex microbial food webs that (a) interconnect various biological cycles via redox coupling and (b) impact on the production and consumption of greenhouse gases. Soda lake microorganisms harbor several biotechnologically relevant enzymes and biomolecules (for example, cellulases, amylases, ectoine) and there is the need to augment bioprospecting efforts in soda lake environments with new integrated approaches. Importantly, some saline and alkaline lake ecosystems around the world need to be protected from anthropogenic pressures that threaten their long-term existence. PMID:23178675

  7. Simulation of Heavy Lake-Effect Snowstorms across the Great Lakes Basin by RegCM4

    NASA Astrophysics Data System (ADS)

    Notaro, M.; Zarrin, A.; Vavrus, S. J.; Bennington, V.

    2013-12-01

    A historical simulation (1976-2002) of the Abdus Salam International Centre for Theoretical Physics Regional Climate Model Version 4 (ICTP RegCM4), coupled to a one-dimensional lake model, is validated against observed lake ice cover and snowfall across the Great Lakes Basin. The model reproduces the broad temporal and spatial features of both variables in terms of spatial distribution, seasonal cycle, and interannual variability, including climatological characteristics of lake-effect snowfall, although the simulated ice cover is overly extensive largely due to the absence of lake circulations. A definition is introduced for identifying heavy lake-effect snowstorms in regional climate model output for all grid cells in the Great Lakes Basin, using criteria based on location, wind direction, lake ice cover, and snowfall. Simulated heavy lake-effect snowstorms occur most frequently downwind of the Great Lakes, particularly to the east of Lake Ontario and to the east and south of Lake Superior, and are most frequent in December-January. The mechanism for these events is attributed to an anticyclone over the central United States and related cold air outbreak for areas downwind of Lakes Ontario and Erie, in contrast to a nearby cyclone over the Great Lakes Basin and associated cold front for areas downwind of Lakes Superior, Huron, and Michigan. Projections of mid- and late-21st century lake-effect snowstorms in the Great Lakes Basin will be summarized, based on dynamically downscaled CMIP5 (Coupled Model Intercomparison Project Phase Five) simulations.

  8. A 250 ka oxygen isotope record from diatoms and investigation of "super-interglacial" conditions during MIS 11 at Lake El'gygytgyn, Far East Russian Arctic

    NASA Astrophysics Data System (ADS)

    Chapligin, B.; Meyer, H.; Langer, M.; Hubberten, H. W.

    2012-12-01

    Continuous paleo-climate records dating back more than 125 ka in the arctic region are rare. Scientific deep drilling was performed in the El'gygytgyn Crater, far eastern Russia in winter 2008/2009 at ICDP site 5011-1. For the composite profile from this site the first 5.66 m of the composite depth were taken from pilot core Lz1024. From this core, biogenic silica (diatoms) samples taken from the first 13 m dating back to around 250 ka were used for oxygen isotope analyses (?18O) as no carbonates were preserved. The usefulness of ?18Odiatom as a proxy for reconstructing air temperature and the isotope composition of precipitation is underlined in several studies. Two diatom species prevail: Cyclotella ocellata which is present throughout the whole core and Pliocaenicus costatus mainly existing in the Holocene. The different species can be separated as they occur in different size fractions. No species-effect on the oxygen isotope composition could be detected. Downcore variations in ?18O values show that glacial-interglacial cycles are present throughout the core and ?18Odiatom values are mainly controlled by ?18Oprecipitation. The variations reflect the Holocene Thermal Maximum, the Last Glacial Maximum and the interglacial periods corresponding to MIS 3, MIS 5 and MIS 7 with a peak-to-peak amplitude of ?18O=5.3 ‰. Our record is the first continuous ?18Odiatom record from an Arctic lake sediment core directly responding to precipitation and dating back more than 250 ka. The record correlates well with the stacked marine ?18O LR04 (r =0.58) and the ?D EPICA Dome-C record (r =0.69). These results indicate strong links to both marine and ice-core records and a strong interhemispheric climate connectivity. Therefore, records from Lake El'gygytgyn can be used to further investigate the past natural climate variability and sensitivity of the Arctic climate to both past and future global climatic changes. Recent studies on the upper 135.2 m of the core composite from site 5011-1 representing 2.8 Ma showed extremely warm "super interglacial" conditions during the Quaternary (e.g. MIS 11c and MIS 31). At the time of this abstract submission around 50 purified diatom samples are in the process of being measured for the time period between 350-450 ka to provide a detailed overview of the oxygen isotope composition around the time corresponding to MIS 11. By the time of the conference we expect the MIS 11 to be analysed completely and to compare our record with the existing studies. Additionally, 20 more samples from 450 ka to 1.5 Ma will be analysed to gain first insights into the applicability of ?18O from diatoms for deep drilling records and to provide information about a potential diagenetic impact on the oxygen isotope composition for this time span.

  9. 33 CFR 165.1306 - Lake Union, Seattle, WA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Guard District § 165.1306 Lake Union, Seattle, WA. (a...All portions of the waters of Lake Union bounded by the following coordinates...boundaries of the safety zone. [Datum: NAD 1983] (b) Effective...the east and west shorelines of Lake Union and may allow...

  10. Salt Lake City, Utah

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Salt Lake City, Utah, will host the 2002 Winter Olympic Games. The city is located on the southeastern shore of the Great Salt Lake and sits to the west of the Wasatch Mountains, which rise more than 3,500 meters (10,000 feet) above sea level. The city was first settled in 1847 by pioneers seeking relief from religious persecution. Today Salt Lake City, the capital of Utah, is home to more than 170,000 residents. This true-color image of Salt Lake City was acquired by the Enhanced Thematic Mapper Plus (ETM+), flying aboard Landsat 7, on May 26, 2000. The southeastern tip of the Great Salt Lake is visible in the upper left of the image. The furrowed green and brown landscape running north-south is a portion of the Wasatch Mountains, some of which are snow-capped (white pixels). The greyish pixels in the center of the image show the developed areas of the city. A number of water reservoirs can be seen east of the mountain range. Salt Lake City International Airport is visible on the northwestern edge of the city. About 20 miles south of the airport is the Bingham Canyon Copper Mine (tan pixels), the world's largest open pit excavation. See also this MODIS image of Utah. Image courtesy NASA Landsat7 Science Team and USGS Eros Data Center

  11. SHRIMP-RG U-Pb isotopic systematics of zircon from the Angel Lake orthogneiss, East Humboldt Range, Nevada: Is this really archean crust?

    USGS Publications Warehouse

    Premo, Wayne R.; Castineiras, Pedro; Wooden, Joseph L.

    2008-01-01

    New SHRIMP-RG (sensitive high-resolution ion microprobe-reverse geometry) data confirm the existence of Archean components within zircon grains of a sample from the orthogneiss of Angel Lake, Nevada, United States, previously interpreted as a nappe of Archean crust. However, the combined evidence strongly suggests that this orthogneiss is a highly deformed, Late Cretaceous monzogranite derived from melting of a sedimentary source dominated by Archean detritus. Zircon grains from the same sample used previously for isotope dilution-thermal ionization mass spectrometry (ID-TIMS) isotopic work were analyzed using the SHRIMP-RG to better define the age and origin of the orthogneiss. Prior to analysis, imaging revealed a morphological variability and intragrain, polyphase nature of the zircon population. The SHRIMP-RG yielded 207Pb/206Pb ages between ca. 2430 and 2580 Ma (a best-fit mean 207Pb/206Pb age of 2531 ± 19 Ma; 95% confidence) from mostly rounded to subrounded zircons and zircon components (cores). In addition, several analyses from rounded to subrounded cores or grains yielded discordant 207Pb/206Pb ages between ca. 1460 and ca. 2170 Ma, consistent with known regional magmatic events. All cores of Proterozoic to latest Archean age were encased within clear, typically low Th/U (206Pb/238U ages between 72 and 91 Ma, consistent with magmatic ages from Lamoille Canyon to the south. An age of ca. 90 Ma is suggested, the younger 206Pb/238U ages resulting from Pb loss. The Cretaceous and Precambrian zircon components also have distinct trace element characteristics, indicating that these age groups are not related to the same igneous source. These results support recent geophysical interpretations and negate the contention that the Archean-Proterozoic boundary extends into the central Great Basin area. They further suggest that the world-class gold deposits along the Carlin Trend are not underlain by Archean cratonal crust, but rather by the Proterozoic Mojave province and Neoproterozoic and Paleozoic metasedimentary sequences dominated by detritus derived from Late Archean sources rather than Proterozoic sources, as is evident farther to the south in the Ruby Mountains.

  12. Is Lake Chabot Eutrophic?

    NASA Astrophysics Data System (ADS)

    Pellegrini, K.; Logan, J.; Esterlis, P.; Lew, A.; Nguyen, M.

    2013-12-01

    Introduction/Abstract: Lake Chabot is an integral part of the East Bay watershed that provides habitats for animals and recreation for humans year-round. Lake Chabot has been in danger of eutrophication due to excessive dumping of phosphorous and nitrogen into the water from the fertilizers of nearby golf courses and neighboring houses. If the lake turned out to be eutrophified, it could seriously impact what is currently the standby emergency water supply for many Castro Valley residents. Eutrophication is the excessive richness of nutrients such as nitrogen and phosphorus in a lake, usually as a result of runoff. This buildup of nutrients causes algal blooms. The algae uses up most of the oxygen in the water, and when it dies, it causes the lake to hypoxify. The fish in the lake can't breathe, and consequently suffocate. Other oxygen-dependant aquatic creatures die off as well. Needless to say, the eutrophication of a lake is bad news for the wildlife that lives in or around it. The level of eutrophication in our area in Northern California tends to increase during the late spring/early summer months, so our crew went out and took samples of Lake Chabot on June 2. We focused on the area of the lake where the water enters, known on the map as Honker Bay. We also took readings a ways down in deeper water for comparison's sake. Visually, the lake looked in bad shape. The water was a murky green that glimmered with particulate matter that swirled around the boat as we went by. In the Honker Bay region where we focused our testing, there were reeds bathed in algae that coated the surface of the lake in thick, swirling patterns. Surprisingly enough, however, our test results didn't reveal any extreme levels of phosphorous or nitrogen. They were slightly higher than usual, but not by any significant amount. The levels we found were high enough to stimulate plant and algae growth and promote eutrophication, but not enough to do any severe damage. After a briefing with a veteran member of the East Bay Regional Park District, Hal MacLean, we realized that almost every lake goes through periods of slight eutrophication. Actually, this phenomenon of waxing and waning of nutrient levels is something many species have grown accustomed too. It's just the extreme cases where the water is actively being polluted by a nearby point source that cause so much damage. Overall, despite outward appearances, the lake is relatively healthy. It boasts high biodiversity in and around the lake, housing such species as dragonflies, eucalyptus, bald eagles, halibut, bass, and even tiny silver goldfish. It fluctuates in oxygen and nutrient content just like any other lake, but for now, it isn't cause for too much concern. It's a beloved element of the Castro Valley community and we hope it will remain so for many generations to come.

  13. VIEW FACING EAST. ORE TRESTLE WINDS AROUND THE INGOT MOLD ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW FACING EAST. ORE TRESTLE WINDS AROUND THE INGOT MOLD CONDITIONING BUILDING IN FOREGROUND. PITTSBURGH & LAKE ERIE TRACKS WIND THROUGH TOWN TOWARDS PITTSBURGH AT RIGHT. - Pittsburgh Steel Company, Monessen Works, Donner Avenue, Monessen, Westmoreland County, PA

  14. 8. DETAIL VIEW OF INCLINED OUTLET GATE WHEEL, LOOKING EAST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. DETAIL VIEW OF INCLINED OUTLET GATE WHEEL, LOOKING EAST - High Mountain Dams in Upalco Unit, Kidney Lake Dam, Ashley National Forest, 4.7 miles North of Miners Gulch Campground, Mountain Home, Duchesne County, UT

  15. 3. OVERALL VIEW OF DAM, SHOWING UPSTREAM FACE, LOOKING EAST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. OVERALL VIEW OF DAM, SHOWING UPSTREAM FACE, LOOKING EAST - High Mountain Dams in Upalco Unit, Kidney Lake Dam, Ashley National Forest, 4.7 miles North of Miners Gulch Campground, Mountain Home, Duchesne County, UT

  16. 11. View of east entry to central corridor of filtration ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. View of east entry to central corridor of filtration bed building. - Lake Whitney Water Filtration Plant, Filtration Plant, South side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

  17. 39. View of valve handle in clear well house, east ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    39. View of valve handle in clear well house, east building. - Lake Whitney Water Filtration Plant, Filtration Plant, South side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

  18. 7. View east of southeast corner of filtration bed building. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. View east of southeast corner of filtration bed building. Laboratory building is at center left of photograph. - Lake Whitney Water Filtration Plant, Filtration Plant, South side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

  19. 32. Photocopied August 1978. SECTION II, LOOKING EAST, DERRICKS AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    32. Photocopied August 1978. SECTION II, LOOKING EAST, DERRICKS AND PILE DRIVERS, JUNE 30, 1901, PREPARING THE CANAL PRIMS FOR THE TIMBER LINING. (153) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  20. 6. Photocopy of photograph, circa 1906 VIEW WESTSOUTHWEST SHOWING EAST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Photocopy of photograph, circa 1906 VIEW WEST-SOUTHWEST SHOWING EAST ELEVATION AND SURROUNDING ENVIRONMENT (enlargement of 4' x 5' negative) - Gary Land Company Building, Gateway Park, Fourth Avenue & Penn Street (moved from Broadway), Gary, Lake County, IN

  1. 28. LOBBY, LOOKING EAST FROM THE THIRD FLOOR. THE OBELISK ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    28. LOBBY, LOOKING EAST FROM THE THIRD FLOOR. THE OBELISK SHAPED FIREPLACE IS FULLY VISIBLE AT THE RIGHT. - Old Faithful Inn, 900' northeast of Snowlodge & 1050' west of Old Faithful Lodge, Lake, Teton County, WY

  2. 95. BOUQUET RESERVOIR LOOKING UP VALLEY TO RESERVOIR LOOKING EAST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    95. BOUQUET RESERVOIR LOOKING UP VALLEY TO RESERVOIR LOOKING EAST - Los Angeles Aqueduct, From Lee Vining Intake (Mammoth Lakes) to Van Norman Reservoir Complex (San Fernando Valley), Los Angeles, Los Angeles County, CA

  3. 14. LOOKING WEST INTO THE EAST PURSUIT PLANE BAY OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. LOOKING WEST INTO THE EAST PURSUIT PLANE BAY OF AR-9. LOW WALLED CREW SHELTER AT RIGHT. - Edwards Air Force Base, South Base, Rammed Earth Aircraft Dispersal Revetments, Western Shore of Rogers Dry Lake, Boron, Kern County, CA

  4. Interior view to the east of an empty computer room ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior view to the east of an empty computer room - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Six Transmitter Building, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  5. 4. View north of Lake Whitney Dam. Wood shed at ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. View north of Lake Whitney Dam. Wood shed at center of photograph houses a turbine installed in 1932. Brick structure to the left of the turbine shed is a gate house which houses the main valves controlling flow of lake to water to the filter plant. - Lake Whitney Water Filtration Plant, Lake Whitney Dam, East side of Whitney Avenue near intersection with Armory Street, Hamden, New Haven County, CT

  6. Snow Clouds Stream off Lake Michigan

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This Sea-viewing Wide Field-of-view Sensor (SeaWiFS) true-color image of Lake Michigan shows a lake effect where clear dry air moves eastward from Wisconsin, picking up moisture as it traverses the lake and forming dense clouds by the time it reaches Lake Michigan's eastern shore. The scene was acquired on January 17, 2002. Note the newly-fallen snow that covers Wisconsin, Michigan, and northern Illinois. The southern edge of the snow line extends to just south of the Chicago area. Chicago sits on the southwestern shore of Lake Michigan. Except for cloudy areas in the west and east and around Lake Superior, the entire Canadian portion of the broader image can be seen to be snow covered as well. Lake Winnipeg (upper left) and James Bay (upper right of center) are frozen over. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  7. 17. ORE DOCK, LOOKING EAST FROM HULETT NO. 1. WHEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. ORE DOCK, LOOKING EAST FROM HULETT NO. 1. WHEN BUILT IN 1911-1912, THIS WAS THE LARGEST ORE-UNLOADING DOCK ON THE GREAT LAKES. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  8. Lake Constance

    Atmospheric Science Data Center

    2013-04-17

    ... of some fish species, and the multiplication of anaerobic bacteria. In recognition of the value of Lake Constance, efforts to mitigate ... gallery date:  Aug 14, 2000 Images:  Lake Constance location:  Europe ...

  9. Far East

    SciTech Connect

    Fletcher, G.L.

    1981-10-01

    Petroleum activity throughout the Far East region was on the upswing during 1980. In spite of increased interest in many parts of the Far East, no major new discoveries were reported. From India to Indonesia, old fields are being rehabilitated and previously uneconomic areas are being looked at again. Indonesia set a new record in 1980 for the number of exploratory wells drilled. Peninsular Malaysia set a record for oil production. Overall, however, 1980 was a banner year for petroleum exploration in the Far East. Sri Lanka saw its first foreign contractor interest in several years. India made major moves toward increasing exploration by offering offshore and onshore blocks to foreign contractors . Bangladesh and even Burma signed exploitation contracts with Japanese investors in order to increase production. Malaysia offered new acreage blocks for the first time in several years. Indonesia and the Philippines also actively encouraged exploration by offering new contract areas. One country in the Far East that did not participate in the 1980 oil boom was China. Taiwan also carried on, as in previous years with the Chinese Petroleum Corporation as the only operator. Japanese and South Korean activities were at approximately the same level as in previous years, although drilling did start in the joint development zone. Total production of the Far East reporting region declined slightly. One significant aspect of 1980 petroleum activities throughout the Far East region is the growing acceptance by various Far East countries of Asian investment for developing and exploring for hydrocarbons. Japan is the major investor, but South Korean interests and the Chinese Petroleum Corporation also began to invest in petroleum rights in other Asian countries. The main area for investment continued to be Indonesia. 39 figures, 9 tables.

  10. Laurance LakeLaurance Lake Lost LakeLost Lake

    E-print Network

    hm Hood River Subbasin 1:200,000 Zoning Designation Forest F-1 Primary Forest F-2 CRGNSA Forest Zones Commercial Industrial Airport Perennial Stream Intermittent Stream Waterbody Urban Area Highway Dam 0 1 2 3 4. Zoning Data Source: Hood River County #12;Hood River Odell Parkdale Laurance LakeLaurance Lake Lost Lake

  11. Asia Lakes

    Atmospheric Science Data Center

    2013-04-16

    ... The lakes are situated in a basin formed by tectonic and volcanic activities associated with the Central Asian rift system, and the water level of these saline lakes shows dramatic variation. Islands are exposed when water levels are low, and the lakes have been known to ...

  12. km on Lake Tanganyika (Fig. 2C). Single airguns or multigun arrays in the size range of40 to 140 cubic

    E-print Network

    Richardson, David

    , The Inland Watens of Tropical Afica (Longman, London, ed. 2, 1981). 6. B. R. Rosendahl, Annu. Rev. Earth (1987). 7. T. Specht and B. R. Rosendahl,J. Afr. Earth Sci., in press; J. Flannery, thesis, Duke of white diatom-rich layers 1 mm thick and dark layers consisting of diatoms, mineral grains, and organic

  13. Subglacial Lake Vostok not expected to discharge water

    NASA Astrophysics Data System (ADS)

    Richter, Andreas; Popov, Sergey V.; Schröder, Ludwig; Schwabe, Joachim; Ewert, Heiko; Scheinert, Mirko; Horwath, Martin; Dietrich, Reinhard

    2014-10-01

    The question whether Antarctica's largest lake, subglacial Lake Vostok, exchanges water is of interdisciplinary relevance but has been undecided so far. We present the potential pathway, outlet location, and threshold height of subglacial water discharge from this lake based on a quantitative evaluation of the fluid potential. If water left Lake Vostok, it would flow toward Ross Ice Shelf. Discharge would occur first to the east of the southern tip of the lake. At this location the bedrock threshold is 91 ± 23 m higher than the hydrostatic equipotential level of Lake Vostok. It is concluded that Lake Vostok is not likely to reach this level within climatic timescales and that no discharge of liquid water is to be expected. We show that in absence of the ice sheet the Lake Vostok depression would harbor a lake significantly deeper and larger than the present aquifer.

  14. 6. North wall and east end of air brake shop ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. North wall and east end of air brake shop section of roundhouse at center. East end of boiler shop section of roundhouse to the right of air brake shop. East end of blacksmith shop section of roundhouse at far right. View to southeast. - Duluth & Iron Range Rail Road Company Shops, Roundhouse, Southwest of downtown Two Harbors, northwest of Agate Bay, Two Harbors, Lake County, MN

  15. Fuzzy logic model of lake water level fluctuations in Lake Van, Turkey

    NASA Astrophysics Data System (ADS)

    Altunkaynak, A.; ?en, Z.

    2007-11-01

    Lake Van is one of the largest terminal lakes in the world. In recent years, significant lake level fluctuations have occurred and can be related to global climatic change. This fluctuation sometimes exhibits abrupt shifts. Floods originating from the lake can cause considerable damage and loss in agriculture and urban areas. Therefore, water level forecasting plays a significant role in planning and design. This study is aimed at predicting future lake levels from past rainfall amounts and water level records. A dynamical change of the lake level is evaluated by the fuzzy approach. The fuzzy inference system has the ability to use fuzzy membership functions that include the uncertainties of the concerned event. This method is applied for Lake Van, in east Turkey. Furthermore, model capabilities are compared with ARMAX model. It is shown that lower absolute errors are obtained with the Takagi-Sugeno fuzzy approach than with the ARMAX model.

  16. Recent Warming of Lake Kivu

    PubMed Central

    Katsev, Sergei; Aaberg, Arthur A.; Crowe, Sean A.; Hecky, Robert E.

    2014-01-01

    Lake Kivu in East Africa has gained notoriety for its prodigious amounts of dissolved methane and dangers of limnic eruption. Being meromictic, it is also expected to accumulate heat due to rising regional air temperatures. To investigate the warming trend and distinguish between atmospheric and geothermal heating sources, we compiled historical temperature data, performed measurements with logging instruments, and simulated heat propagation. We also performed isotopic analyses of water from the lake's main basin and isolated Kabuno Bay. The results reveal that the lake surface is warming at the rate of 0.12°C per decade, which matches the warming rates in other East African lakes. Temperatures increase throughout the entire water column. Though warming is strongest near the surface, warming rates in the deep waters cannot be accounted for solely by propagation of atmospheric heat at presently assumed rates of vertical mixing. Unless the transport rates are significantly higher than presently believed, this indicates significant contributions from subterranean heat sources. Temperature time series in the deep monimolimnion suggest evidence of convection. The progressive deepening of the depth of temperature minimum in the water column is expected to accelerate the warming in deeper waters. The warming trend, however, is unlikely to strongly affect the physical stability of the lake, which depends primarily on salinity gradient. PMID:25295730

  17. Recent warming of lake Kivu.

    PubMed

    Katsev, Sergei; Aaberg, Arthur A; Crowe, Sean A; Hecky, Robert E

    2014-01-01

    Lake Kivu in East Africa has gained notoriety for its prodigious amounts of dissolved methane and dangers of limnic eruption. Being meromictic, it is also expected to accumulate heat due to rising regional air temperatures. To investigate the warming trend and distinguish between atmospheric and geothermal heating sources, we compiled historical temperature data, performed measurements with logging instruments, and simulated heat propagation. We also performed isotopic analyses of water from the lake's main basin and isolated Kabuno Bay. The results reveal that the lake surface is warming at the rate of 0.12°C per decade, which matches the warming rates in other East African lakes. Temperatures increase throughout the entire water column. Though warming is strongest near the surface, warming rates in the deep waters cannot be accounted for solely by propagation of atmospheric heat at presently assumed rates of vertical mixing. Unless the transport rates are significantly higher than presently believed, this indicates significant contributions from subterranean heat sources. Temperature time series in the deep monimolimnion suggest evidence of convection. The progressive deepening of the depth of temperature minimum in the water column is expected to accelerate the warming in deeper waters. The warming trend, however, is unlikely to strongly affect the physical stability of the lake, which depends primarily on salinity gradient. PMID:25295730

  18. Investigating "mass hysteria" in early postcolonial Uganda: Benjamin H. Kagwa, East african psychiatry, and the Gisu.

    PubMed

    Pringle, Yolana

    2015-01-01

    In the early 1960s, medical officers and administrators began to receive reports of what was being described as "mass madness" and "mass hysteria" in Tanganyika (now Tanzania) and Uganda. Each epidemic reportedly affected between three hundred and six hundred people and, coming in the wake of independence from colonial rule, caused considerable concern. One of the practitioners sent to investigate was Benjamin H. Kagwa, a Ugandan-born psychiatrist whose report represents the first investigation by an African psychiatrist in East Africa. This article uses Kagwa's investigation to explore some of the difficulties facing East Africa's first generation of psychiatrists as they took over responsibility for psychiatry. During this period, psychiatrists worked in an intellectual climate that was both attempting to deal with the legacy of colonial racism, and which placed faith in African psychiatrists to reveal more culturally sensitive insights into African psychopathology. The epidemics were the first major challenge for psychiatrists such as Kagwa precisely because they appeared to confirm what colonial psychiatrists had been warning for years-that westernization would eventually result in mass mental instability. As this article argues, however, Kagwa was never fully able to free himself from the practices and assumptions that had pervaded his discipline under colonial rule. His analysis of the epidemics as a "mental conflict" fit into a much longer tradition of psychiatry in East Africa, and stood starkly against the explanations of the local community. PMID:24191308

  19. 78 FR 28892 - Hazardous Fire Risk Reduction, East Bay Hills, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-16

    ...Fire Risk Reduction, East Bay Hills, CA AGENCY: Federal...projects within the East Bay Hills area in Alameda and Contra Costa...Wildland-Urban Interface in the East Bay Hills running from Lake...activities on 105 project areas. Public Involvement...

  20. 32. Otter Lake Dam. View from downstream show how the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    32. Otter Lake Dam. View from downstream show how the dam blends into its environment. Looking east-northeast. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  1. View of the highway, approach to the Frozen Lake switchback ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of the highway, approach to the Frozen Lake switchback curve, looking east. Proposed realignment will shift the road slightly to the south (right) - Beartooth Highway, Red Lodge, Montana to Cooke City, Montana, Cody, Park County, WY

  2. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area... the U.S./Canadian border to the end of the road at East Landing. (3) Access and circulatory roads...

  3. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area... the U.S./Canadian border to the end of the road at East Landing. (3) Access and circulatory roads...

  4. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area... the U.S./Canadian border to the end of the road at East Landing. (3) Access and circulatory roads...

  5. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area... the U.S./Canadian border to the end of the road at East Landing. (3) Access and circulatory roads...

  6. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area... the U.S./Canadian border to the end of the road at East Landing. (3) Access and circulatory roads...

  7. Directions to the Biochemistry Department from the Salt Lake City Airport Take I-80 E toward OGDEN/PROVO

    E-print Network

    Hill, Chris

    Directions to the Biochemistry Department from the Salt Lake City Airport Take I-80 E toward OGDEN lights and stop signs until this road meets 1300 East at the top of a hill Take a left onto 1300 East

  8. LAKE AND RESERVOIR MANAGEMENT, 1990 6(2): 175-180 C 1990 North American Lake Management Society

    E-print Network

    (lavescens). The predominant aquatic plant was Charasp. 1currently at: Nebraska Game and Parks Commission, P.O. Box30370, Lincoln, Nebraska 68503 175 103-F #12;D. L. BAUER and D. W. WILLIS East Lake Eureka

  9. East Africa

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This image shows the East African nations of Ethiopia, Eritrea, and Somalia, as well as portions of Kenya, Sudan, Yemen, and Saudi Arabia. Dominating the scene are the green Ethiopian Highlands. With altitudes as high as 4,620 meters (15,157 feet), the highlands pull moisture from the arid air, resulting in relatively lush vegetation. In fact, coffee-one of the world's most prized crops-originated here. To the north (above) the highlands is Eritrea, which became independent in 1993. East (right) of Ethiopia is Somalia, jutting out into the Indian Ocean. The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) captured this true-color image on November 29, 2000. Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  10. Banff, Calgary, CANMORE, Emerald Lake & Lake Louise

    E-print Network

    Martin, Jeff

    Travel Banff, Calgary, CANMORE, Emerald Lake & Lake Louise The University of Winnipeg Day 1 Travel opportunity) Sulfur Mountain Gondola Ride Banff Hot Springs (optional) Day 4 Emerald Lake (sightseeing) Lake Gondola ride up the Canadian Rockies Trip to Lake Louise Trip to Emerald Lake Trip to Johnston Canyon

  11. A LINE POLE 1 IN FOREGROUND AND MYSTIC LAKE POWERHOUSE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    A LINE POLE 1 IN FOREGROUND AND MYSTIC LAKE POWERHOUSE IN BACKGROUND. A LINE POLE 1 IS A MODERN REPLACEMENT STRUCTURE WITH BROWN PORCELAIN SUSPENSION-TYPE INSULATORS. VIEW TO EAST. - Mystic Lake Hydroelectric Facility, Electric Transmission A Line, Along West Rosebud Creek, Fishtail, Stillwater County, MT

  12. 77 FR 62440 - Safety Zone; Wounded Warriors Benefit, Lake Erie, Huron, OH

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-15

    ...an air cannon into the lake in East Huron, OH. This...encompass all waters of Lake Erie within a 2500 ft...coordinates are North American Datum of 1983 (NAD 83). Entry...safety zone: all waters of Lake Erie within a 2500 ft...coordinates are North American Datum of 1983 (NAD...

  13. A test of fitness consequences of hybridization in sibling species of Lake Victoria cichlid fish

    E-print Network

    A test of fitness consequences of hybridization in sibling species of Lake Victoria cichlid fish I Introduction In East Africa's Lake Victoria several hundred species of endemic cichlid fish evolved from few 500 years (Beuning et al., 2002). Lake Victoria cichlids have become a major model system

  14. Lake Eyre

    Atmospheric Science Data Center

    2013-04-16

    ...   View Larger Image Lake Eyre is a large salt lake situated between two deserts in one of Australia's driest regions. ... for changes in angular reflectance, and indicate textural properties of the surface related to roughness and/or moisture content. Data ...

  15. LAKE FORK

    EPA Science Inventory

    The Lake Fork of the Arkansas River Watershed has been adversely affected through mining, water diversion and storage projects, grazing, logging, and other human influences over the past 120 years. It is the goals of the LFWWG to improve the health of Lake fork by addressing th...

  16. A post-Calumet shoreline along southern Lake Michigan

    USGS Publications Warehouse

    Capps, D.K.; Thompson, T.A.; Booth, R.K.

    2007-01-01

    The southern shore of Lake Michigan is the type area for many of ancestral Lake Michigan's late Pleistocene lake phases, but coastal deposits and features of the Algonquin phase of northern Lake Michigan, Lake Huron, and Lake Superior are not recognized in the area. Isostatic rebound models suggest that Algonquin phase deposits should be 100 m or more below modern lake level. A relict shoreline, however, exists along the lakeward margin of the Calumet Beach that was erosional west of Deep River and depositional east of the river. For this post-Calumet shoreline, the elevation of basal foreshore deposits east of Deep River and the base of the scarp west of Deep River indicate a slightly westward dipping water plane that is centered at ???184 m above mean sea level. Basal foreshore elevations also indicate that lake level fell ???2 m during the development of the shoreline. The pooled mean of radiocarbon dates from the surface of the peat below post-Calumet shoreline foreshore deposits indicate that the lake transgressed over the peat at 10,560 ?? 70 years B.P. Pollen assemblages from the peat are consistent with this age. The elevation and age of the post-Calumet shoreline are similar to the Main Algonquin phase of Lake Huron. Recent isostatic rebound models do not adequately address a high-elevation Algonquin-age shoreline along the southern shore of Lake Michigan, but the Goldthwait (1908) hinge-line model does. ?? 2006 Springer Science+Business Media B.V.

  17. Blanket of Snow Covers Salt Lake City

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On December 23, 2001, less than two months before the start of the 2002 Winter Olympics, snow blankets Salt Lake City and the surrounding area. The Great Salt Lake, on the left hand side of the image above, often contributes to the region's snowfall through the 'lake-effect.' As cold air passes over a large body of water it both warms and absorbs moisture. The warm air then rises (like a hot air balloon) and cools again. As it cools, the water vapor condenses out, resulting in snowfall. Just to the east (right) of the Great Salt Lake the mountains of the Wasatch Range lift air from the lake even higher, enhancing the lake-effect, resulting in an average snowfall of 64 inches a year in Salt Lake City and 140 inches in Park City, which is located at the foot of the Wasatch Front. For more information about the lake-effect, read Lake-Effect Snowfalls. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  18. 46 CFR 401.407 - Basic rates and charges on Lake Erie and the navigable waters from Southeast Shoal to Port Huron...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Lake Erie and the navigable waters from Southeast Shoal to Port...a) Area 4 (Undesignated Waters): Service Lake Erie (East of Southeast Shoal) Buffalo Six-hour Period $760... (b) Area 5 (Designated Waters): Any point on or in...

  19. 46 CFR 401.407 - Basic rates and charges on Lake Erie and the navigable waters from Southeast Shoal to Port Huron...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Lake Erie and the navigable waters from Southeast Shoal to Port...a) Area 4 (Undesignated Waters): Service Lake Erie (East of Southeast Shoal) Buffalo Six-hour period $791... (b) Area 5 (Designated Waters): Any point on or in...

  20. 46 CFR 401.407 - Basic rates and charges on Lake Erie and the navigable waters from Southeast Shoal to Port Huron...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Lake Erie and the navigable waters from Southeast Shoal to Port...a) Area 4 (Undesignated Waters): Service Lake Erie (East of Southeast Shoal) Buffalo 6-Hour Period $828... (b) Area 5 (Designated Waters): Any point on or in...

  1. 46 CFR 401.407 - Basic rates and charges on Lake Erie and the navigable waters from Southeast Shoal to Port Huron...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Lake Erie and the navigable waters from Southeast Shoal to Port...a) Area 4 (Undesignated Waters): Service Lake Erie (East of Southeast Shoal) Buffalo 6-hour Period $849... (b) Area 5 (Designated Waters): Any point on or in...

  2. Antioxidant Responses of Vallisneria asiatica to Eutrophic Sediments in Lake Taihu, China.

    PubMed

    Kang, Caixia; Kuba, Takahiro; Hao, Aimin; Iseri, Yasushi

    2015-08-01

    Three kinds of representative sediments were obtained from a macrophyte-dominated bay (East Lake Taihu) and two algae-dominated regions (Western Lake Taihu and Meiliang Bay). Physiological responses of Vallisneria asiatica to these sediments were compared. Results from 20 days exposures showed no obvious differences in malondialdehyde (MDA) in roots, while the MDA content in leaves of plants exposed to Western Lake Taihu sediment was significantly (p<0.05) higher than those exposed to the other two sediments. In comparison to the other two sediments, plants exposed to Western Lake Taihu sediment showed significantly lower (p<0.05) superoxide dismutase in roots and leaves on the 10th and 40th day. On the 40th day, root catalase (CAT) activities in V. asiatica from Western Lake Taihu and Meiliang Bay sediments were lower than that from East Lake Taihu sediment, while leaf CAT activity in V. asiatica from Western Lake Taihu sediment was higher than that from East Lake Taihu sediment (p<0.05). Western Lake Taihu sediment caused more serious oxidative stress in V. asiatica than East Lake Taihu sediment. Results indicated eutrophic sediment was a contributing factor in the disappearance of V. asiatica in Western Lake Taihu. PMID:26070371

  3. Changes in the dreissenid community in the lower Great Lakes with emphasis on southern Lake Ontario

    USGS Publications Warehouse

    Mills, Edward L.; Chrisman, Jana R.; Baldwin, Brad; Owens, Randall W.; O'Gorman, Robert; Howell, Todd; Roseman, Edward F.; Raths, Melinda K.

    1999-01-01

    A field study was conducted in the lower Great Lakes to assess changes in spatial distribution and population structure of dreissenid mussel populations. More specifically, the westward range expansion of quagga mussel into western Lake Erie and toward Lake Huron was investigated and the shell size, density, and biomass of zebra and quagga mussel with depth in southern Lake Ontario in 1992 and 1995 were compared. In Lake Erie, quagga mussel dominated the dreissenid community in the eastern basin and zebra mussel dominated in the western basin. In southern Lake Ontario, an east to west gradient was observed with the quagga mussel dominant at western sites and zebra mussel dominant at eastern locations. Mean shell size of quagga mussel was generally larger than that of zebra mussel except in western Lake Erie and one site in eastern Lake Erie. Although mean shell size and our index of numbers and biomass of both dreissenid species increased sharply in southern Lake Ontario between 1992 and 1995, the increase in density and biomass was much greater for quagga mussels over the 3-year period. In 1995, zebra mussels were most abundant at 15 to 25 m whereas the highest numbers and biomass of quagga mussel were at 35 to 45 m. The quagga mussel is now the most abundant dreissenid in areas of southern Lake Ontario where the zebra mussel was once the most abundant dreissenid; this trend parallels that observed for dreissenid populations in the Dneiper River basin in the Ukraine.

  4. Angora Fire, Lake Tahoe

    NASA Technical Reports Server (NTRS)

    2007-01-01

    On the weekend of June 23, 2007, a wildfire broke out south of Lake Tahoe, which stretches across the California-Nevada border. By June 28, the Angora Fire had burned more than 200 homes and forced some 2,000 residents to evacuate, according to The Seattle Times and the Central Valley Business Times. On June 27, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of the burn scar left by the Angora fire. The burn scar is dark gray, or charcoal. Water bodies, including the southern tip of Lake Tahoe and Fallen Leaf Lake, are pale silvery blue, the silver color a result of sunlight reflecting off the surface of the water. Vegetation ranges in color from dark to bright green. Streets are light gray, and the customary pattern of meandering residential streets and cul-de-sacs appears throughout the image, including the area that burned. The burn scar shows where the fire obliterated some of the residential areas just east of Fallen Leaf Lake. According to news reports, the U.S. Forest Service had expressed optimism about containing the fire within a week of the outbreak, but a few days after the fire started, it jumped a defense, forcing the evacuation of hundreds more residents. Strong winds that had been forecast for June 27, however, did not materialize, allowing firefighters to regain ground in controlling the blaze. On June 27, authorities hoped that the fire would be completely contained by July 3. According to estimates provided in the daily report from the National Interagency Fire Center, the fire had burned 3,100 acres (about 12.5 square kilometers) and was about 55 percent contained as of June 28. Some mandatory evacuations remained in effect. NASA image by Jesse Allen, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

  5. Pyramid Lake

    USGS Multimedia Gallery

    Pyramid Lake, Nevada, not only holds deep cultural connections for the Paiute Tribe and tribal member Dan Mosely (pictured), but also supports a tribal economy centered on fishing and recreational activities. ...

  6. Lake-level change and fan delta evolution of glacial lakes in North Patagonia

    NASA Astrophysics Data System (ADS)

    Aoki, T.; Hori, K.

    2009-12-01

    Large, cross-border glacial lakes, Lago General Carrea/Lago Buenos Aires (LGC/LBA) and Lago Cochrane/Lago Pueyrredon (LC/LP) occur on the east side of the northern Patagonian Icefield (NPI). Rivers emptying into the lakes have formed several fan deltas at their mouths in response to lake level changes. We examined the deltas around the both lakes based on field survey, aerial photograph interpretation, and analysis of digital elevation model (DEM). Two stepped fan deltas, named as fan deltas 1 and 2, except for the present one were observed widely at LGC/LBA. The features of fan delta deposits are similar to those of a Gilbert-type fan delta. The edges of these deltas were situated above 200 m and 100 m higher than the present lake level at a height of ca. 200 meters, suggesting that lake level fall with a magnitude of ~100 m occurred at least twice. The rate of each lake-level lowering would be very rapid, because the deltas have steep escarpments at the front and fluvial terraces cutting into the deltas are unclear along the rivers. The timings of emergence might be before 8.4 ka and soon after 6.2 ka based on the radiocarbon dates of the fan delta 1 and the existing numerical ages about the related landforms such as moraines and lacustrine deposits. Although there are also several, raised fan deltas at LC/LP, the altitudes of the deltas differ from those of LGC/LBA. Therefore both lakes were not merged even during the period of higher lake level after the Last Glacial Maximum. It is considered that outlet glaciers flowing toward the east from the NPI blocked the western end of the both lakes and separated them. Further study is required to clarify the relationship between behaviors of the glaciers and lake level fluctuations.

  7. Geographical ancestry of Lake Malawi's cichlid fish diversity.

    PubMed

    Genner, Martin J; Ngatunga, Benjamin P; Mzighani, Semvua; Smith, Alan; Turner, George F

    2015-06-01

    The Lake Malawi haplochromine cichlid flock is one of the largest vertebrate adaptive radiations. The geographical source of the radiation has been assumed to be rivers to the south and east of Lake Malawi, where extant representatives of the flock are now present. Here, we provide mitochondrial DNA evidence suggesting the sister taxon to the Lake Malawi radiation is within the Great Ruaha river in Tanzania, north of Lake Malawi. Estimates of the time of divergence between the Lake Malawi flock and this riverine sister taxon range from 2.13 to 6.76 Ma, prior to origins of the current radiation 1.20-4.06 Ma. These results are congruent with evaluations of 2-3.75 Ma fossil material that suggest past faunal connections between Lake Malawi and the Ruaha. We propose that ancestors of the Malawi radiation became isolated within the catchment during Pliocene rifting that formed both Lake Malawi and the Kipengere/Livingstone mountain range, before colonizing rivers to the south and east of the lake region and radiating within the lake basin. Identification of this sister taxon allows tests of whether standing genetic diversity has predisposed Lake Malawi cichlids to rapid speciation and adaptive radiation. PMID:26063752

  8. New explorations along the northern shores of Lake Bonneville

    USGS Publications Warehouse

    Oviatt, Charles G.; Miller, D.M.

    1997-01-01

    This field trip begins in Salt Lake City and makes a clockwise circuit of Great Salt Lake, with primary objectives to observe stratigraphie and geomorphic records of Lake Bonneville. Stops include Stansbury Island, Puddle Valley, gravel pits at Lakeside and the south end of the Hogup Mountains, several stops in Curlew Valley and Hansel Valley, and a final stop at the north end of Great Salt Lake east of the Promontory Mountains. Stratigraphie observations at gravel-pit and natural exposures will be linked to interpretations of lake-level change, which were caused by climate change. Evidence of paleoseismic and volcanic activity will be discussed at several sites, and will be tied to the lacustrine stratigraphic record. The trip provides an overview of the history of Lake Bonneville and introduces participants to some new localities with excellent examples of Lake Bonneville landforms and stratigraphy.

  9. 83. FIRST AND SECOND AQUEDUCTS LOOKING EAST/NORTHEAST Los Angeles ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    83. FIRST AND SECOND AQUEDUCTS LOOKING EAST/NORTHEAST - Los Angeles Aqueduct, From Lee Vining Intake (Mammoth Lakes) to Van Norman Reservoir Complex (San Fernando Valley), Los Angeles, Los Angeles County, CA

  10. East Candor Chasma

    NASA Technical Reports Server (NTRS)

    1997-01-01

    During its examination of Mars, the Viking 1 spacecraft returned images of Valles Marineris, a huge canyon system 5,000 km long, up to 240 km wide, and 6.5 km deep, whose connected chasma or valleys may have formed from a combination of erosional collapse and structural activity. The view shows east Candor Chasma, one of the connected valleys of Valles Marineris; north toward top of frame; for scale, the impact crater in upper right corner is 15 km (9 miles) wide. The image, centered at latitude 7.5 degrees S., longitude 67.5 degrees, is a composite of Viking 1 Orbiter high-resolution (about 80 m/pixel or picture element) images in black and white and low-resolution (about 250 m/pixel) images in color. The Viking 1 craft landed on Mars in July of 1976.

    East Candor Chasma occupies the eastern part of the large west-northwest-trending trough of Candor Chasma. This section is about 150 km wide. East Candor Chasma is bordered on the north and south by walled cliffs, most likely faults. The walls may have been dissected by landslides forming reentrants; one area on the north wall shows what appears to be landslide debris. Both walls show spur-and-gully morphology and smooth sections. In the lower part of the image northwest-trending, linear depressions on the plateau are younger graben or fault valleys that cut the south wall.

    Material central to the chasma shows layering in places and has been locally eroded by the wind to form flutes and ridges. These interior layered deposits have curvilinear reentrants carved into them, and in one locale a lobe flows away from the top of the interior deposit. The lobe may be mass-wasting deposits due to collapse of older interior deposits (Lucchitta, 1996, LPSC XXVII abs., p. 779- 780); this controversial idea requires that the older layered deposits were saturated with ice, perhaps from former lakes, and that young volcanism and/or tectonism melted the ice and made the material flow.

  11. Lena River Delta and East Siberian Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The winter sea ice in the east Siberian Sea is looking a bit like a cracked windshield in these true-color Moderate Resolution Imaging Spectroradiometer (MODIS) images from June 16 and 23, 2002. North of the thawing tundra, the sea ice takes on its cracked, bright blue appearance as it thins, which allows the reflection of the water to show through. Numerous still-frozen lakes dot the tundra. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  12. Lacustrine mollusc radiations in the Malawi Basin: experiments in a natural laboratory for evolution

    NASA Astrophysics Data System (ADS)

    Van Damme, D.; Gautier, A.

    2012-12-01

    In Terminal Pliocene-Early Pleistocene times, part of the Malawi Basin was occupied by palaeo-lake Chiwondo. Molluscan biostratigraphy situates this freshwater lake either in the East African wet phase between 2.7-2.4 Ma or that of 2.0-1.8 Ma. In-lake divergent evolution remained restricted to a few molluscan taxa and was very modest. The lacustrine Chiwondo fauna went extinct at the beginning of the Pleistocene. The Modern Lake Malawi malacofauna is poor and descends from ubiquistic South-East African taxa and some Malawi Basin endemics that invaded the present lake after the Late Pleistocene mega-droughts. The Pleistocene aridity crises caused dramatic changes, affecting the malacofauna of all East African lakes. All lacustrine endemic faunas that had evolved in the Pliocene rift lakes, such as palaeo-lake Chiwondo, became extinct. In Lake Tanganyika, the freshwater ecosystem did not crash as in other lakes, but the environmental changes were sufficiently important to trigger a vast radiation. All African endemic lacustrine molluscan clades that are the result of in-lake divergence are hence geologically young, including the vast Lavigeria clade in Lake Tanganyika (ca. 43 species).

  13. Weevils successfully destroy acres of lake-invading plant 

    E-print Network

    Wythe, Kathy

    2012-01-01

    stream_source_info Weevils successfully destroy acres of lake.pdf.txt stream_content_type text/plain stream_size 5911 Content-Encoding ISO-8859-1 stream_name Weevils successfully destroy acres of lake.pdf.txt Content-Type text....A. Steinhagen Lake near Woodville in East Texas this summer. Now a similar e?ort aims to recreate these successful results at Caddo Lake in northeast Texas. Researchers from U.S. Army Corps of Engineers, Texas Parks and Wildlife Department (TPWD), Texas A...

  14. Lake Powell

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The white ring around Lake Powell tells the story. The surface is down 98 feet. This is critical, because Powell, Lake Mead, and other lakes along the Colorado River provide water for millions of people in five states. We are in the eighth year of a drought on the Colorado River. This year was the driest year ever reported in Southern California, and there is a severe drought in Northern California, down to less than 30-percent of snow pack. This ASTER image of part of Lake Powell was acquired in 2001. The gray area depicts the shrunken, reduced 2007 lake extent compared to the extended, larger black area in 2001.

    The image covers an area of 24 x 30 km, and is centered near 37.1 degrees north latitude, 111.3 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  15. The biome reconstruction approach as a tool for interpretation of past vegetation and climate changes: application to modern and fossil pollen data from Lake El'gygytgyn, Far East Russian Arctic

    NASA Astrophysics Data System (ADS)

    Tarasov, P. E.; Andreev, A. A.; Anderson, P. M.; Lozhkin, A. V.; Haltia, E.; Nowaczyk, N. R.; Wennrich, V.; Brigham-Grette, J.; Melles, M.

    2013-06-01

    The modern and fossil pollen data obtained under the framework of the multi-disciplinary international "El'gygytgyn Drilling Project" represent a unique archive that allows the testing of a range of pollen-based reconstruction approaches and the deciphering of changes in the regional vegetation and climate since ~3.58 Ma. In the current study we provide details of the biome reconstruction method applied to the late Pliocene and Quaternary pollen records from Lake El'gygytgyn. All terrestrial pollen taxa identified in the spectra from Lake El'gygytgyn were assigned to major vegetation types (biomes), which today occur near the lake and in the broader region of eastern and northern Asia and, thus, could potentially have been present in this region during the past. When applied to the modern surface pollen spectra from the lake, the method shows a dominance of the tundra biome that currently characterizes the Lake El'gygytgyn area. When applied to the pollen spectra from the middle Pleistocene to present, the method suggests (1) a predominance of tundra during the Holocene, (2) a short interval during the marine isotope stage (MIS) 5.5 interglacial distinguished by cold deciduous forest, and (3) a long phase of taiga dominance during MIS 31 and, particularly, MIS 11.3. These two latter interglacials seem to be some of the longest and warmest intervals within the past million years. During the late Pliocene-early Pleistocene interval (i.e., ~3.562-2.200 Ma), there is good correspondence between the millennial-scale vegetation changes documented in the Lake El'gygytgyn record and the alternation of cold and warm marine isotope stages, which reflect changes in the global ice volume and sea level. The biome reconstruction demonstrates changes in the regional vegetation which suggest a step-like transition from generally warmer/wetter environments of the earlier (i.e., Pliocene) interval towards colder/drier environments of the Pleistocene. The reconstruction of most of the species-rich cool mixed and cool conifer forest biomes is particularly noticeable prior to MIS G16, whereas tundra becomes a prominent feature after MIS G6. These results consistently indicate that the study region supported significant tree populations during most of the interval prior to ~2.730 Ma. The biomization results also suggest that the transition from mostly forested to mostly open landscape was not gradual, but rather occurred in step-like fashion. Thus, the cold and drought tolerant steppe biome first appears in the reconstruction ca. 3.298 Ma during the tundra dominated MIS M2, whereas the tundra biome initially occurs between ~3.379 and ~3.378 Ma within MIS MG4. Prior to ~2.800 Ma, several other cold stages during this generally warm Pliocene interval experienced a dominance of tundra and a great reduction of tree populations in the regional vegetation.

  16. Influence of the African Great Lakes on the regional climate

    NASA Astrophysics Data System (ADS)

    Thiery, Wim; Davin, Edouard; Panitz, Hans-Jürgen; Demuzere, Matthias; Lhermitte, Stef; van Lipzig, Nicole

    2015-04-01

    Although the African Great Lakes are important regulators for the East-African climate, their influence on atmospheric dynamics and the regional hydrological cycle remains poorly understood. We aim to assess this impact by conducting a regional climate model simulation which resolves individual lakes and explicitly computes lake temperatures. The regional climate model COSMO-CLM, coupled to a state-of-the-art lake parameterization scheme and land surface model, is used to dynamically downscale the COSMO-CLM CORDEX-Africa evaluation simulation to 7 km grid spacing for the period 1999-2008. Evaluation of the model reveals good performance compared to both in-situ and satellite observations, especially for spatio-temporal variability of lake surface temperatures and precipitation. Model integrations indicate that the four major African Great Lakes almost double precipitation amounts over their surface relative to a simulation without lakes, but hardly exert any influence on precipitation beyond their shores. The largest lakes also cool their near-surface air, this time with pronounced downwind influence. The lake-induced cooling happens during daytime, when the lakes absorb incoming solar radiation and inhibit upward turbulent heat transport. At night, when this heat is released, the lakes warm the near-surface air. Furthermore, Lake Victoria has profound influence on atmospheric dynamics and stability as it induces cellular motion with over-lake convective inhibition during daytime, and the reversed pattern at night. Overall, this study shows the added value of resolving individual lakes and realistically representing lake surface temperatures for climate studies in this region. Thiery, W., Davin, E., Panitz, H.-J., Demuzere, M., Lhermitte, S., van Lipzig, N.P.M., The impact of the African Great Lakes on the regional climate, J. Climate (in review).

  17. Late Cenozoic Moisture History of East Africa

    NASA Astrophysics Data System (ADS)

    Trauth, M. H.; Maslin, M. A.; Deino, A.; Strecker, M. R.

    2004-12-01

    Evidence from fluvio-lacustrine sediments in ten separate basins in the Ethiopian and Kenya rifts suggests there were three protracted humid periods during the Late Cenozoic; at 2.7 - 2.5, 1.9 - 1.7, and 1.1 - 0.9 million years before present. These wet periods are coeval with known increases of aridity in parts of North West and North East Africa, indicating significant regional shifts in African climate. These three East African wet periods correspond to major global climatic changes as well as maxima in eccentricity and thus precession, suggesting a combined global and local causation. These climatic changes were important for the speciation and dispersal of mammals and hominids in East Africa as it implies that key steps in human evolution occurred during relatively humid periods in a region containing extensive deep lakes.

  18. 5. FLAME DEFLECTOR, COMPLETE X15 VEHICLE TEST STAND. Looking east. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. FLAME DEFLECTOR, COMPLETE X-15 VEHICLE TEST STAND. Looking east. - Edwards Air Force Base, X-15 Engine Test Complex, Rocket Engine & Complete X-15 Vehicle Test Stands, Rogers Dry Lake, east of runway between North Base & South Base, Boron, Kern County, CA

  19. Hydrologic reconnaissance of Tsala Apopka Lake, Citrus County, Florida

    USGS Publications Warehouse

    Rutledge, A.T.

    1977-01-01

    The swamps, marshes, and open waters of Tsala Apopka Lake, Florida, were mapped and the hydrologic connection between the lake and the Floridan limestone aquifer was studied from October 1975 to September 1976. Tsala Apopka Lake is a series of shallow , interconnected lakes, ponds, and marshes whose water surface slopes northward at 0.5 foot per mile. According to aerial photographs of December 1972, only 6 percent of the 103 square miles of study area is covered by open water. Open water is abundant along the western side of the lake, dense and sparse marshes occupy most of the lake area, and swamps occupy a thick zone around the Withlacoochee River which borders the lake to the east. Only a small fraction of the total surface flow occurs through the lake. The average lake outflow through S-351 canal is 23.6 cfs; while the average river flow at Holder is 714 cfs. Tsala Apopka Lake is hydraulically connected to the Floridan aquifer. At low flow, the major source of water in the river is ground water from the Floridan aquifer. The specific conductance of water in the Floridan aquifer averages 250-350 umho/cm (micromhos per centimeter) at 25C in this area. The specific conductance of water in the Withlacoochee River near Holder averages 268 umho/cm at 25C, while water in Tsala Apopka Lake at Hernando averages 139 umho/cm at 25C. (Woodard-USGS)

  20. Lake Colpitts 

    E-print Network

    Unknown

    2011-09-05

    Bateaux were a key utility craft in military operations in the colonies of North America. Their size, durability, and ease of construction made them ideal for moving troops and supplies over the lakes and rivers of New York, New England and New...

  1. Iceberg Lake

    USGS Multimedia Gallery

    On Iceberg Lake in Glacier National Park, ice from the glacier is breaking up and melting at a rapid rate.  Cold, glacier fed waters provide crucial habitat for native aquatic species such as trout, and as the ice is disappearing, so are the ideal habitats to sustain native ecosystems.  ...

  2. Geology of central Lake Michigan

    SciTech Connect

    Wold, R.J.; Paull, R.A.; Wolosin, C.A.; Friedel, R.J.

    1981-09-01

    The geology beneath Lake Michigan between 43/sup 0/00' and 44/sup 0/00'N and between 86/sup 0/30' and 87/sup 0/40' W is interpreted from a synthesis of 1,700 km of continuous seismic reflection profile data, bathymetry, grab samples, and onshore surface and subsurface information. The continuous seismic reflection profiles and bathymetry provided information for maps of unconsolidated sediment thickness and Paleozoic bedrock topography. Two structural-stratigraphic cross sections of the study area were constructed by utilizing a composite subsurface-surface section for eastern Wisconsin and two control wells in western Michigan. The cross sections, grab samples previously described in the literature, the bedrock topographic map, and published maps were used to construct a Paleozoic geologic map for central Lake Michigan. Rocks from Middle Silurian through Early Mississippian age form subcrops beneath the study area, whereas rocks of Early Silurian, Ordovician, and Late Cambrian age are present at greater depth. The Upper Cambrian rocks unconformably overlie Precambrian igneous and metamorphic rocks. The structural-stratigraphic cross sections also allow speculation about the petroleum potential beneath Lake Michigan. The possibility of oil occurrences within the Silurian is enhanced by major east-west facies changes, and other horizons with promise are present in Devonian and Ordovician rocks. Although Michigan and Wisconsin laws currently prohibit petroleum exploration in Lake Michigan, it is an area with future potential.

  3. Last glacial maximum and Holocene lake levels of Owens Lake, eastern California, USA

    USGS Publications Warehouse

    Bacon, S.N.; Burke, R.M.; Pezzopane, S.K.; Jayko, A.S.

    2006-01-01

    Stratigraphic investigations of fluvio-deltaic and lacustrine sediments exposed in stream cuts, quarry walls, and deep trenches east of the Sierra Nevada in Owens Valley near Lone Pine, California have enabled the reconstruction of pluvial Owens Lake level oscillations. Age control for these sediments is from 22 radiocarbon (14C) dates and the identification and stratigraphic correlation of a tephra, which when plotted as a function of age versus altitude, define numerous oscillations in the level of pluvial Owens Lake during the latest Pleistocene and early Holocene. We have constructed a lake-level altitude curve for the time interval ???27,000 cal yr BP to present that is based on the integration of this new stratigraphic analysis with published surface stratigraphic data and subsurface core data. Pluvial Owens Lake regressed from its latest Pleistocene highstands from ???27,000 to ???15,300 cal yr BP, as recorded by ???15 m of down cutting of the sill from the altitudes of ???1160 to 1145 m. By ???11,600 cal yr BP, the lake had dropped ???45 m from the 1145 m sill. This lowstand was followed by an early Holocene transgression that attained a highstand near 1135 m before dropping to 1120 m at 7860-7650 cal yr BP that had not been recognized in earlier studies. The lake then lowered another ???30 m to shallow and near desiccation levels between ???6850 and 4300 cal yr BP. Fluvial cut-and-fill relations north of Lone Pine and well-preserved shoreline features at ???1108 m indicate a minor lake-level rise after 4300 cal yr BP, followed by alkaline and shallow conditions during the latest Holocene. The new latest Quaternary lake-level record of pluvial Owens Lake offers insight to the hydrologic balance along the east side of the southern Sierra Nevada and will assist regional paleoclimatic models for the western Basin and Range. ?? 2005 Elsevier Ltd. All rights reserved.

  4. 39. HULETT ORE UNLOADER IN MOTION. VIEW LOOKING EAST. (Also ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    39. HULETT ORE UNLOADER IN MOTION. VIEW LOOKING EAST. (Also see OH-18-14, OH-18-38, and OH-18-40) - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  5. 40. HULETT ORE UNLOADER IN MOTION. VIEW LOOKING EAST. (Also ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    40. HULETT ORE UNLOADER IN MOTION. VIEW LOOKING EAST. (Also see OH-18-14, OH-18-38, and OH-18-39) - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  6. 9. View east at rear of Armory Street Pump House ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. View east at rear of Armory Street Pump House showing remains of original coal bunker. Area later was the location of an oil tank. - Lake Whitney Water Filtration Plant, Armory Street Pumphouse, North side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

  7. 38. View of valve handles in clear well house, east ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    38. View of valve handles in clear well house, east building. Note early model of sample jar in foreground. This was used to draw water samples from the clear well. - Lake Whitney Water Filtration Plant, Filtration Plant, South side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

  8. 2. View east of filtration bed building. Access bridge to ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. View east of filtration bed building. Access bridge to earth covering over reinforced concrete roof is at center right of photograph. - Lake Whitney Water Filtration Plant, Filtration Plant, South side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

  9. 10. View west of east entry to filtration beds. Note ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. View west of east entry to filtration beds. Note monitor roof and clerestory windows over central corridor. Laboratory building is sited over the center of the filtration bed building at extreme left center of photograph. - Lake Whitney Water Filtration Plant, Filtration Plant, South side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

  10. 9. View northwest of east entry to central corridor between ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. View northwest of east entry to central corridor between the filtration beds. Note square chimney at right center of photograph which is a part of the Armory Street Pumping Station. - Lake Whitney Water Filtration Plant, Filtration Plant, South side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

  11. 34. View east of clear well houses located north of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    34. View east of clear well houses located north of filtration building. Armory Street is at the left of the photograph. - Lake Whitney Water Filtration Plant, Filtration Plant, South side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

  12. 117. Photocopied August 1978. VIEW OF EAST FOREBAY SHOWING COMPLETED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    117. Photocopied August 1978. VIEW OF EAST FOREBAY SHOWING COMPLETED APRON. NOVEMBER 24, 1926. CLAY LEFT OVER FROM REFILLING THE AREA BETWEEN FOREBAY FLOOR SILLS IS SHOWN HEAPED AGAINST THE FOREBAY WALL TO PROVIDE AN EXTRA MEASURE OF PROTECTION. (1051) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  13. 16. Photocopied August 1978. CANAL SECTION I, LOOKING EAST, AUGUST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. Photocopied August 1978. CANAL SECTION I, LOOKING EAST, AUGUST 21, 1900. NOTE THE DUMP TRAIN ENGINES PUSHING THE TRAIN OF DUMP CARS AWAY FROM THE STEAM SHOVEL. (62) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  14. 62. Photocopied August 1978. 'CARBIDE' OR SECOND FLOOR LOOKING EAST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    62. Photocopied August 1978. 'CARBIDE' OR SECOND FLOOR LOOKING EAST FROM WEST END, OCTOBER 29, 1902. THE STAIRS TO THE POWER COMPANY'S SUPPLEMENTAL THIRD FLOOR APPEARS AT THE RIGHT; THE HOLLOW TILES WHICH FORMED THIS FLOOR AT THE TOP. (435) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  15. 19. Photocopied August 1978. CANAL SECTION I, LOOKING EAST, 1900, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. Photocopied August 1978. CANAL SECTION I, LOOKING EAST, 1900, WITH SEVERAL PARTIALLY SUBMERGED STEAM SHOVELS SHOWN IN THE FLOODED CANAL. ONE OF THE TEMPORARY BRIDGES CONSTRUCTED OVER THE CANAL RIGHT -OF-WAY IS VISIBLE IN THE BACKGROUND. (39) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  16. Department of Anthropology 270 S. 1400 East, Rm. 102

    E-print Network

    Tipple, Brett

    Department of Anthropology 270 S. 1400 East, Rm. 102 University of Utah Salt Lake City, Utah 84112 both pages of this application to: Linda Morgan UniversityofUtah DepartmentofAnthropology 270 S. 1400 subfield do you propose to specialize? Archaeology Biological Anthropology Cultural Anthropology

  17. 18. Photocopied August 1978. SECTIONS I AND II LOOKING EAST, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. Photocopied August 1978. SECTIONS I AND II LOOKING EAST, JUNE 20, 1901. THE TEMPORARY INCLINES USED TO TAKE DUMP TRAINS UP OUT OF THE CANAL CUT SHOW UP CLEARLY HERE, AS WELL AS THE RATHER HAZARDOUS NATURE OF THE BANKS. (150) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  18. 24. Photcopied August 1978. SECTION I LOOKING EAST, AUGUST 25, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. Photcopied August 1978. SECTION I LOOKING EAST, AUGUST 25, 1901. POWER COMPANY CREWS ARE AT WORK CONSTRUCTING A MASONRY WALL ON THE LEFT SIDE WHERE THE ROCK FALLS WELL BELOW THE PROJECTED WATER LINE. ALREADY COMPLETED MASONRY RETAINING WALLS ARE VISIBLE ALONG THE RIGHT BANK OF THE CANAL. (172) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  19. Modification of Lake Michigan Benthic Habitats by Zebra Mussels Primary Investigator: Stephen Lozano -NOAA GLERL

    E-print Network

    Lozano - NOAA GLERL Co-Investigators: Tom Nalepa (Emeritus) - NOAA GLERL, Greg Kennedy, Marc Blouin dreissenid population. Our summer cruises will include areas on both the east and west sides of Lake Michigan

  20. East Avenue Truck Inspection

    E-print Network

    Siefert, Chris

    7011 East Avenue Livermore, CA 94551 Tesla Road Interstate 580 - From Oakland/San Francisco Map National Laboratories 7011 East Avenue Livermore, CA 94551 Tesla Road Parking To Oakland/San Francisco Map

  1. Box model and 1D longitudinal model of flow and transport in Bosten Lake, China

    NASA Astrophysics Data System (ADS)

    Li, Ning; Kinzelbach, Wolfgang; Li, WenPeng; Dong, XinGuang

    2015-05-01

    Bosten Lake in the southeast of Yanqi Catchment, China, supports the downstream agricultural and natural environments. Over the last few decades the intensive agricultural activities in Yanqi Catchment resulted in decreased lake levels and deteriorated lake water quality. A two-box model is constructed to understand the evolution of lake level and salinity between 1958 and 2008. The two-box model of the lake indicates that the evaporation does have the same trend as the observed lake area and the annual average evaporation agrees with the value obtained from the Penman-Monteith approach. To achieve a correct salt balance, the ratio of outflow concentration and average lake concentration has to be around 0.7. This is due to the incomplete mixing of the lake caused by short-circuiting between tributary inflow and the main outflow via the pump stations abstracting water from the lake. This short-circuiting is investigated in more detail by a 1D numerical flow and transport model of the lake calibrated with observations of lake level and lake concentrations. The distributed model reproduces the correct time-varying outflow concentration. It is used for the assessment of two basic management options: increasing river discharge (by water saving irrigation, reduction of phreatic evaporation or reduction of agricultural area) and diverting saline drainage water to the desert. Increasing river discharge to the lake by 20% reduces the east basin salt concentration by 0.55 kg/m3, while capturing all the drainage water and discharging it to depressions instead of the lake reduces the east basin salt concentration by 0.63 kg/m3. A combination of increasing river inflow and decreasing drainage salt flux is sufficient to bring future lake TDS below the required 1 kg/m3, to keep a lake level that sustains the lake ecosystem, and to supply more water for downstream development and ecosystem rehabilitation.

  2. Assessing Human Impacts on the Water Balance of Lake Victoria Using GRACE and Altimeters.

    NASA Astrophysics Data System (ADS)

    Swenson, S. C.; Wahr, J. M.

    2008-12-01

    GRACE has provided global estimates of vertically integrated water storage anomalies at monthly intervals with a useful spatial resolution of 300-500 km. Water levels of large lakes are now routinely monitored by satellite altimeters. By combining these datasets, it may be possible to separate the effects of climate and human management on lake levels. During the period 2002-2006, the levels of Lake Victoria dropped about two meters. Water storage changes of Lake Victoria and other large lakes in the East African Rift Valley are compared, and the relative impacts of climate and human management are shown to be of similar magnitude.

  3. Introduction and spread of the threespine stickleback (Gasterosteus aculeatus) in Lakes Huron and Michigan

    USGS Publications Warehouse

    Stedman, Ralph M.; Bowen, Charles A., II

    1985-01-01

    The threespine stickleback (Gasterosteus aculeatus) was not known to occur in the Great Lakes above Niagara Falls until 1980, when it was collected in South Bay, Manitoulin Island, in the Lake Huron basin. By 1984 this species had been found in tributaries of Lakes Huron and Michigan, and in the open waters of both lakes. All specimens identified were the completely plated morph that is most prevalent in fresh water along the east coast of North America. The status of this species in Lakes Huron and Michigan appears to be 'Possibly Established.' If threespine stickleback increase in abundance they may eventually provide additional forage for large salmonids.

  4. Temporal evolution of (36)Cl abundances in the Great Lakes.

    PubMed

    Poghosyan, Armen; Sturchio, Neil C

    2015-06-01

    The observed (36)Cl isotopic abundance in Great Lakes water decreases from west to east, with the highest (36)Cl/Cl ratio of 1332 × 10(-15) in Lake Superior and the lowest (36)Cl/Cl ratio of 151 × 10(-15) in Lake Erie, whereas the (36)Cl concentration ((36)Cl atoms/L) is lowest in Lake Superior and higher in the other Great Lakes. The (36)Cl concentration in Lake Superior is much higher than expected from normal atmospheric deposition over the basin, consistent with deposition of nuclear bomb-produced (36)Cl during 1952-1964. A conservative mass-balance model constrained by hydrological parameters and available (36)Cl fluence measurements predicts the (36)Cl abundances in the Great Lakes from 1945 to 2015, in excellent agreement with available data for Lakes Superior, Michigan, and Huron, but the model underestimates (36)Cl abundances for Lakes Erie and Ontario. However, assuming that (36)Cl demonstrates non-conservative behavior and is significantly retained in the drainage basins, a model incorporating a delayed input parameter successfully predicts observed (36)Cl concentrations in all of the Great Lakes. PMID:25817926

  5. Hydrothermal vents of Yellowstone Lake, Yellowstone National Park, Wyoming

    SciTech Connect

    Kaplinski, M.A.; Morgan, P. . Geology Dept.)

    1993-04-01

    Hydrothermal vent systems within Yellowstone Lake are located within the Yellowstone caldera in the northeastern and West Thumb sections of the lake. The vent systems lie within areas of extremely high geothermal gradients (< 1,000 C/km) in the lake sediments and occur as clusters of individual vents that expel both hydrothermal fluids and gas. Regions surrounding the vents are colonized by unique, chemotropic biologic communities and suggest that hydrothermal input plays an important role in the nutrient dynamics of the lake's ecosystem. The main concentration of hydrothermal activity occurs in the northeast region of the main lake body in a number of locations including: (1) along the shoreline from the southern edge of Sedge Bay to the inlet of Pelican Creek; (2) the central portion of the partially submerged Mary Bay phreatic explosion crater, within deep (30--50 m) fissures; (3) along the top of a 3 km long, steep-sided ridge that extends from the southern border of Mary Bay, south-southeast into the main lake basin; and (4) east of Stevenson Island along the lower portion of the slope (50--107 m) into the lake basin, within an anastomosing series of north to northwest trending, narrow troughs or fissures. Hydrothermal vents were also located within, and surrounding the West Thumb of Yellowstone Lake, with the main concentration occurring the offshore of the West Thumb and Potts Geyser Basin. Hydrothermal vents in Yellowstone Lake occur along fractures that have penetrated the lake sediments or along the tops of ridges and near shore areas. Underneath the lake, rising hydrothermal fluids encounter a semi-permeable cap of lake sediments. Upwardly convecting hydrothermal fluid flow may be diverted by the impermeable lake sediments along the buried, pre-existing topography. These fluids may continue to rise along topography until fractures are encountered, or the lake sediment cover is thinned sufficiently to allow egress of the fluids.

  6. Hydrogeochemical features of Lake Ngozi (SW Tanzania)

    NASA Astrophysics Data System (ADS)

    Delalande-Le Mouëllic, Manuëlla; Gherardi, Fabrizio; Williamson, David; Kajula, Stephen; Kraml, Michael; Noret, Aurélie; Abdallah, Issah; Mwandapile, Ezekiel; Massault, Marc; Majule, Amos; Bergonzini, Laurent

    2015-03-01

    Located on the triple rift junction hosting the Karonga-Usungu depression in Tanzania, Lake Ngozi is the second largest crater lake of the East African Rift. The lake has a number of peculiar features: it has a near constant water level, no permanent surface inlets and outlets, it is vertically well-mixed, with homogeneous distribution of temperature and chemical composition, and it is characterised by near neutral to slightly acid Na-Cl waters of comparatively high salinity and high P-CO2. Based on the different chemical signature of surface and ground waters (low-Cl type) from lake waters, mass balance methods have been applied to investigate lake dynamics. Water enters the lake mainly by precipitation and groundwater inflow, and leaves by groundwater outflow and evaporation. A large groundwater outflow of 2.4 m yr-1 has been estimated. The high salinity, Na-Cl signature of Lake Ngozi waters, together with 3He/4He ratios measured on dissolved gases (between 7 and 8.3 Ra) and high-PCO2 values estimated all along the water vertical column indicate the inflow of deep-seated fluids, likely magmatic in origin, into the lake. The existence of a hydrothermal system possibly at 250 °C in the root of the volcanic edifice is also hypothesised on the basis of solute geothermometry. Despite the current lack of vertical stratification, the lake is suspected to act as condenser for CO2 and other gases of deep magmatic origin, and should be then further monitored for the risk of limnic eruptions as well as for environmental and climatic concerns.

  7. AFFILIATIONS: STEENBURGH AND ALCOTT--Department of Meteorology, University of Utah, Salt Lake City, Utah

    E-print Network

    Steenburgh, Jim

    AFFILIATIONS: STEENBURGH AND ALCOTT--Department of Meteorology, University of Utah, Salt Lake City, Utah CORRESPONDING AUTHOR: Dr. W. James Steenburgh, Department of Meteorology, University of Utah, 135 South 1460 East Room 819, Salt Lake City, UT 84112 E-mail: jim.steenburgh@utah.edu The abstract

  8. A SUSTAINABLE APPROACH TO PRESERVE THE CHOCTAWHATCHEE COASTAL DUNE LAKES OF FLORIDA

    EPA Science Inventory

    Scattered along a 30 mile coastline just east of Destin, Florida, lies a series of 18 named coastal dune lakes distributed between Walton and Bay County. The lakes are irregularly shaped, typically shallow (2-6 m deep), located within a mile inland from the coast. The water is...

  9. Coupling remote sensing with computational fluid dynamics modelling to estimate lake chlorophyll-a concentration

    E-print Network

    Coupling remote sensing with computational fluid dynamics modelling to estimate lake chlorophyll meso-eutrophic lake in Central East Scotland, UK, revealed a strong gradient in chlorophyll-a (chl. Keywords: Computational fluid dynamics; Phytoplankton; Chlorophyll index; Loch Leven 1. Introduction Remote

  10. Invited review A 600,000 year long continental pollen record from Lake Van, eastern

    E-print Network

    Gilli, Adrian

    Invited review A 600,000 year long continental pollen record from Lake Van, eastern Anatolia Keyword: Long continental pollen record Paleoclimate Near East a b s t r a c t Lake Van is the fourth m long continental pollen record presented here is based on a well-dated composite profile drilled

  11. Time Series Analysis of Lake Surface Water Temperatures in Perialpine Austrian Lakes

    NASA Astrophysics Data System (ADS)

    Dokulil, M.

    2014-12-01

    Long-term observations of surface water temperatures (SWT) collected by the Austrian Hydrographical Service are analysed for 24 Austrian lakes located in different climatic provinces. The lakes are situated north and south of the Alps, in the east bordering Hungary and in the west bordering Germany. All lakes are natural and are mainly embedded into calcareous rock formations at elevations between 100 and 900 m. Lakes largely vary in size, depth, retention time, flushing and mixing. Results indicate a rise in SWT parallel to air temperature (AT) since the mid-1960s. On an annual basis, changes in water temperature were the greatest in spring and summer. As a consequence of increasing water temperatures, the duration of thermal stratification expands, mixing and retention time are affected. Changes in the food web are expected to occur, but will strongly depend on local environmental conditions and will therefore be different for individual lakes. Trends in SWT are analysed in detail for four of the lakes having the longest data records (>100 years), representing different lake types and climate provinces.

  12. First record of Daphnia lumholtzi Sars in the Great Lakes

    USGS Publications Warehouse

    Muzinic, Christopher J.

    2000-01-01

    Adults of the cladoceran Daphnia lumholtzi, native to Australia, Africa, and parts of Asia, were first collected in August 1999 in Lake Erie. Individuals were collected near East Harbor State Park, Lakeside, Ohio from vertical plankton net tows. The average number of D. lumholtzi that were found (0.03/L) indicate that D. lumholtzi is beginning to establish itself in Lake Erie. The morphology of this Daphnia differs greatly from native species because of its elongated head and tail spine. This sighting is important because it acknowledges yet another exotic invader into the Great Lakes basin and it also shows that this, normally, warm water species continues to expand its range northward.

  13. Schlumberger soundings near Medicine Lake, California

    USGS Publications Warehouse

    Zohdy, A.A.R.; Bisdorf, R.J.

    1990-01-01

    The use of direct current resistivity soundings to explore the geothermal potential of the Medicine Lake area in northern California proved to be challenging because of high contact resistances and winding roads. Deep Schlumberger soundings were made by expanding current electrode spacings along the winding roads. Corrected sounding data were interpreted using an automatic interpretation method. Forty-two maps of interpreted resistivity were calculated for depths extending from 20 to 1000 m. Computer animation of these 42 maps revealed that: 1) certain subtle anomalies migrate laterallly with depth and can be traced to their origin, 2) an extensive volume of low-resistivity material underlies the survey area, and 3) the three areas (east of Bullseye Lake, southwest of Glass Mountain, and northwest of Medicine Lake) may be favorable geothermal targets. Six interpreted resistivity maps and three cross-sections illustrate the above findings. -from Authors

  14. Late Quaternary Lake-Catchment Processes in Hala Lake, Northern Tibetan Plateau, and Their Effects on Lake Evolution

    NASA Astrophysics Data System (ADS)

    Yan, D.; Wuennemann, B.; Stauch, G.; Zhang, Y.; E, C.; Chen, K.; Cao, G.; Wang, J.

    2014-12-01

    Hala Lake, a closed 65 m deep lake basin in the western Qilian Mountains, Qinghai Province, is a key-site to demonstrate various factors that influenced lake hydrology, sediment flux and lake-internal depositional conditions throughout the last 25 ka BP. Multi-proxy records from eight sediment cores and on-shore sections display heterogeneous sediment distribution patterns and local catchment influences on lake formation. Detrital flux, stable isotopes and geochemical parameters indicate variations in water discharge, attributed to local effects and regional climate influence. A mass flow is related to a local non-climatic event. Ostracod assemblages and algae formation in combination with geochemical and sediment properties indicate four phases of centennial-scale fluctuations in water and sediment supply. During the global LGM the lake experienced the lowest lake level under cold and dry climate conditions. The lake level rose after 14 ka due to climatic amelioration (phase 1). Strong fluctuations are recorded for the Early Holocene, indicating variable conditions and unstable summer monsoon influence (phase 2). Minor fluctuations occurred between 7.8 and 4.5 ka as a result on ongoing glacier melt and increased westerly influence (phase 3). An earthquake-induced mass flow layer occurred at ca. 7.0 ka. The abrupt change of detrital carbonate contribution at around 6 ka is attributed to the continued retreat of glaciers and fluvial erosion of limestone. Short-term changes in water balance and sediment fluxes after a lowstand at 4.1 ka can be attributed to the variable influence of westerly-driven moisture supply (phase 4). We can show that several events can be related to changes in the catchment configuration apart from climate influence. The hydrology was mainly controlled by meltwater discharges and westerly-driven air masses. The influence of the East Asian Summer Monsoon effective moisture supply remained on a very low level or was completely absent.

  15. The precipitation response to the desiccation of Lake Chad

    SciTech Connect

    Lauwaet D.; VanWeverberg K.; vanLipzig, N. P. M., Weverberg, K. V., Ridderb, K. D., and Goyens, C.

    2012-04-01

    Located in the semi-arid African Sahel, Lake Chad has shrunk from a surface area of 25000 km2 in 1960 to about 1350 km2 due to a series of droughts and anthropogenic influences. The disappearance of such a large open-water body can be expected to have a noticeable effect on the meteorology in the surroundings of the lake. The impact could extend even further to the west as westward propagating convective systems pass Lake Chad in the rainfall season. This study examines the sensitivity of the regional hydrology and convective processes to the desiccation of the lake using a regional atmospheric model. Three Lake Chad scenarios are applied reflecting the situation in 1960, the current situation and a potential future scenario in which the lake and the surrounding wetlands have disappeared. The model simulations span the months July-September in 2006, which includes the rainfall season in the Lake Chad area. Total precipitation amounts and the components of the hydrological cycle are found to be hardly affected by the existence of the lake. A filled Lake Chad does, however, increase the precipitation at the east side of the lake. The model results indicate that the boundary layer moisture and temperature are significantly altered downwind of the lake. By investigating a mesoscale convective system (MCS) case, this is found to affect the development and progress of the system. At first, the MCS is intensified by the more unstable boundary layer air but the persistence of the system is altered as the cold pool propagation becomes less effective. The proposed mechanism is able to explain the differences in the rainfall patterns nearby Lake Chad between the scenarios. This highlights the local sensitivity to the desiccation of Lake Chad whereas the large-scale atmospheric processes are not affected.

  16. Integrating physical and chemical characteristics of lakes into the glacially influenced landscape of the Northern Cascade Mountains, Washington State, USA

    USGS Publications Warehouse

    Larson, Gary L.; Lomnicky, G.A.; Liss, W.J.; Deimling, E.

    1999-01-01

    A basic knowledge of the physical and chemical characteristics of lakes is needed by management to make informed decisions to protect water resources. In this study we investigated some of the physical and chemical characteristics of 58 lakes in alpine, subalpine, and forest vegetation zones in a natural area (North Cascades National Park Service Complex) between 1989 and 1993. The objectives of the study were to: (1) document the time of ice-out relative to lake elevation; (2) determine how a sharp climate gradient west and east of the hydrologic divide affected the time of ice-out for subalpine lakes; and (3) assess how lake water quality was associated with lake elevation, lake depth, and basin geology. As expected, lake ice-out times occurred earlier with decreasing elevation. East-slope subalpine lakes iced-out earlier than did west-slope subalpine lakes because the east slope of the study area was drier and warmer than the west slope. On average, the lakes were relatively cold, neutral in pH, and low in dissolved substances and concentrations of nitrogen and phosphorus. Although some shallow lakes (depth ,10 m) exhibited the highest alkalinities, conductivities, and concentrations of phosphorus and nitrogen, most shallow lakes exhibited low values for these variables that were comparable to values observed in deep lakes. Geology did not play a major role in segregating the lakes based on water quality. Overall, lake temperature, pH, alkalinity, conductivity, and concentrations of total phosphorus and total Kjeldahl N increased with decreasing elevation. These changes in water quality with decreasing elevation in this temperate mountainous region corresponded with warmer air temperatures and increased vegetation biomass, soil depth and maturity, and dissolved substances and nutrients.

  17. Deep structure beneath Lake Ontario: crustal-scale Greeneville subdivisions

    USGS Publications Warehouse

    Forsyth, D. A.; Zelt, Colin A.; White, D. J.; Easton, R. M.; Hutchinson, Deborah R.

    1994-01-01

    Lake Ontario marine seismic data reveal major Grenville crustal subdivisions beneath central and southern Lake Ontario separated by interpreted shear zones that extend to the lower crust. A shear zone bounded transition between the Elzevir and Frontenac terranes exposed north of Lake Ontario is linked to a seismically defined shear zone beneath central Lake Ontario by prominent aeromagnetic and gravity anomalies, easterly dipping wide-angle reflections, and fractures in Paleozoic strata. We suggest the central Lake Ontario zone represents crustal-scale deformation along an Elzevir–Frontenac boundary zone that extends from outcrop to the south shore of Lake Ontario.Seismic images from Lake Ontario and the exposed western Central Metasedimentary Belt are dominated by crustal-scale shear zones and reflection geometries featuring arcuate reflections truncated at their bases by apparent east-dipping linear reflections. The images show that zones analogous to the interpreted Grenville Front Tectonic Zone are also present within the Central Metasedimentary Belt and support models of northwest-directed crustal shortening for Grenvillian deep crustal deformation beneath most of southeastern Ontario.A Precambrian basement high, the Iroquoian high, is defined by a thinning of generally horizontal Paleozoic strata over a crestal area above the basement shear zone beneath central Lake Ontario. The Iroquoian high helps explain the peninsular extension into Lake Ontario forming Prince Edward County, the occurrence of Precambrian inlier outcrops in Prince Edward County, and Paleozoic fractures forming the Clarendon–Linden structure in New York.

  18. Trace Elements concentration and distribution across the Lake Chad Basin

    NASA Astrophysics Data System (ADS)

    Ndunguru, G. G.; Goni, I. B.; Mulugeta, V.; Grindley, J.; Banks, M. L.; Lee, J.; Adegoke, J. O.

    2009-12-01

    The Lake Chad, which is the largest Lake in West Africa, is situated between the latitude 12 ½ and 14 ½ north and longitude 130 east of the Southern fringe of the Sahara Desert. About 25 % of the Lake Chad lies within Nigeria, while the Republic of Cameroon, Chad and Niger share the rest of it. Lake Chad is completely landlocked and has no outlets; therefore loss of water is mainly through high rates of evaporation unlike similar Lakes in other parts of the World. The Lake Chad waters are fresh and of good quality with very low salt content which makes it suitable for irrigated agriculture. This study was carried out from upper stream to lower stream leading from Kano to the Damaturu region which is one of several water bodies that supply Lake Chad. Soil samples were collected from over seventy five sites and analyzed for ten Trace Elements(Be, Cd, Co, Cu, Mn,Fe, Mo, Pb, Zn, and Cr) using the Inductively Coupled Plasma (ICP)-OES. Assessment and Monitoring of Trace Elements concentrations are vital because they impact environment and can affect the human healthy. Since little is known about the Trace Elements status in Lake Chad Basin. The result in this study provides baseline information on the distribution and concentration of Trace Elements along the Lake Chad Basin.

  19. East African climate pulses and early human evolution

    NASA Astrophysics Data System (ADS)

    Maslin, Mark A.; Brierley, Chris M.; Milner, Alice M.; Shultz, Susanne; Trauth, Martin H.; Wilson, Katy E.

    2014-10-01

    Current evidence suggests that all of the major events in hominin evolution have occurred in East Africa. Over the last two decades, there has been intensive work undertaken to understand African palaeoclimate and tectonics in order to put together a coherent picture of how the environment of East Africa has varied in the past. The landscape of East Africa has altered dramatically over the last 10 million years. It has changed from a relatively flat, homogenous region covered with mixed tropical forest, to a varied and heterogeneous environment, with mountains over 4 km high and vegetation ranging from desert to cloud forest. The progressive rifting of East Africa has also generated numerous lake basins, which are highly sensitive to changes in the local precipitation-evaporation regime. There is now evidence that the presence of precession-driven, ephemeral deep-water lakes in East Africa were concurrent with major events in hominin evolution. It seems the unusual geology and climate of East Africa created periods of highly variable local climate, which, it has been suggested could have driven hominin speciation, encephalisation and dispersal out of Africa. One example is the significant hominin speciation and brain expansion event at ˜1.8 Ma that seems to have been coeval with the occurrence of highly variable, extensive, deep-water lakes. This complex, climatically very variable setting inspired first the variability selection hypothesis, which was then the basis for the pulsed climate variability hypothesis. The newer of the two suggests that the long-term drying trend in East Africa was punctuated by episodes of short, alternating periods of extreme humidity and aridity. Both hypotheses, together with other key theories of climate-evolution linkages, are discussed in this paper. Though useful the actual evolution mechanisms, which led to early hominins are still unclear and continue to be debated. However, it is clear that an understanding of East African lakes and their palaeoclimate history is required to understand the context within which humans evolved and eventually left East Africa.

  20. Winter and Summer Views of the Salt Lake Region

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Magnificent views of the region surrounding Salt Lake City, Utah are captured in these winter and summer images from the Multi-angle Imaging SpectroRadiometer's vertical-viewing (nadir) camera. Salt Lake City, situated near the southeastern shore of the Great Salt Lake, is host to the 2002 Winter Olympic Games, which open Friday, February 8. Venues for five of the scheduled events are at city (indoor) locations, and five in mountain (outdoor) facilities. All ten can be found within the area contained in these images. Some of the outdoor events take place at Ogden, situated north of Salt Lake City and at Park City, located to the east. Salt Lake City is surrounded by mountains including the Wasatch Range to the east, and the temperature difference between the Great Salt Lake and the overlying atmosphere enhances the moisture content of winter storms. These factors, in combination with natural cloud seeding by salt crystals from the lake, are believed to result in greater snowfall in neighboring areas compared to more distant locales. In addition to the obvious difference in snow cover between the winter and summer views, water color changes in parts of the Great Salt Lake are apparent in these images. The distinctly different coloration between the northern and southern arms of the Great Salt Lake is the result of a rock-filled causeway built in 1953 to support a permanent railroad. The causeway has resulted in decreased circulation between the two arms and higher salinity on the northern side. The southern part of the lake includes the large Antelope Island, and at full resolution a bridge connecting it to the mainland can be discerned. These images are natural color views acquired on February 8, 2001 and June 16, 2001, respectively. Each image represents an area of about 220 kilometers x 285 kilometers. Image courtesy NASA/GSFC/LaRC/JPL, MISR Team.

  1. Longevity of Lake Superior lake trout

    USGS Publications Warehouse

    Schram, Stephen T.; Fabrizio, Mary C.

    1998-01-01

    The age structure of mature lake trout Salvelinus namaycush from the Wisconsin waters of Lake Superior increased following a population recovery that has taken place since the 1960s. As the population aged, it became apparent that scales were unreliable aging structures. Beginning in 1986, we examined both scale and sagittal otolith ages from tagged fish with a known period at liberty. We found large discrepancies in scale and sagittal otolith ages of mature fish, such that scale ages were biased low. We estimated lake trout living up to 42 years, which is greater than previously reported from Lake Superior. Investigators studying lake trout population dynamics in the Great Lakes should be aware that lake trout can live longer than previously thought.

  2. Pleistocene lake level changes in Western Mongolia

    NASA Astrophysics Data System (ADS)

    Borodavko, P. S.

    2009-04-01

    Global cooling in the Early Pleistocene caused extensive continental glaciation in the northern hemisphere including the arid areas of Central Asia. The reduction of temperatures (particularly summer temperatures) reduced evaporation and strengthened the importance of precipitation. The simultaneity of "lakes periods" (pluvials) and stages of glaciation is established experience confirmed by investigations in the west of North America and Russia. In the Mongolian Great Lakes Depression new evidence for similar conditions is found. The Great Lakes Depression is one of the largest in Central Asia, and is divided into 2 main Lakes basins: Hyargas Lake Basin and Uvs Lake Basin. The basin is 600-650 km in length with a width of 200-250 km in the north and 60-100 km in the south. Total catchment area is about 186600 km2. The elevation of the basin floor is from 1700 m a.s.l. to 760 m a.s.l., decreasing to the north and south-east. The depression extends south-north and is bounded by mountains: Tannu-Ola to the north, Hangai to the east; Gobi Altai to the south and Mongolian Altay to the west. The maximum elevation of the mountains is 4000 m a.s.l. There are some mountains with an elevation between 2000 and 3000 m a.s.l in the lake catchment. These mountains are not glaciated today. The geological record [1] suggests the Great Lakes Depression already existed in the Mesozoic, but assumed its modern form only during the Pliocene-Quaternary when tectonic movements caused the uplift of the surrounding mountains. A phase of tectonic stability occurred during the Late Quaternary. The depression is filled by Quaternary fluvial, aeolian and lacustrine deposits (e.g. sand, pebbles). The Neogene deposits are represented by coloured clay, marl, sand and sandstone [1]. Hyargas Lake is the end base level of erosion of the lake group consisting of the Hara-Us Nur, Dorgon, Hara Nur and Airag lakes. Hyargas is one of the largest lakes in Mongolia, with a water surface of 1,407 km2. The lake is 75 km long and 31 km wide. Its mean depth is 47 m, with the deepest point reaching 80 m, and its total water volume is 66,034 km3 and drainage basin 115,500 km2. The only water flowing into it is Galbiyn Hooloi. Hara-Us Nur Lake is a fresh-water (mineralization ca 107-348 mg/l, pH -7.8) basin situated in the Mongolian Great Lakes Depression [2]. Hara-Us Nur is fed by the Kobdo and Buyant rivers, which start in the Mongolian Altay, and outflows via the Chano-Hairkhan River into Hara-Us Nur Lake. Hara-Us Nur is divided by the Ak-Bashi Island into two subbasins. It has a water area of 1857 km2 with a length of 72.2 km and a maximum width of 27 km [4]. The maximum depth is 4 m and the average depth is ca 2 m [5,6]. The terraced lake shores are covered by steppe and desert vegetation. Pharagmites is abundant in the river deltas and close to the shore-line and the shallow-water littoral is covered by rich aquatic vegetation, including Myriophyllum verticulatum, Zannichelia pedunculata, Utricularia vulgaris [3]. Hara-Nur Lake is situated in the desert steppe subzone of the Mongolian Great Lakes Depression. The fresh-water Hara-Nur Lake receives inflow from Hara-Us Nur Lake via the Chano-Hairkhan River. There are two outflows from the lake one outflow is via a 10 km-long channel which flows to the Dzabhan River, which in turn flows into the closed Hyargas Lake. The other outflow is a small semi-permanent stream with flows southward into the closed brackish-water Dorgon Lake. Hara-Nur has a water area of 57,500 ha, with a length of 37 km and a maximum width of ca 24 km. The maximum depth is 7 m and the average depth is ca 4 m. The mean water mineralization is 260 mg/l and the pH is 8.0 [5]. The catchment area is ca 7,200,000 ha. Lake Ureg located in the Mongolian Altay at an altitude of 1425 m.a.s.1., this lake has an area 237.6 km2 and maximum depth of 48 m. Secchi disk transparency is to 8 m. Macrophyte beds cover up to 20 per cent of the lake area, with the common cane sedges and horsetails dominant. The benthic fauna is poor, and only single pecime

  3. Lake Volta, Ghana

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This true-color image of Lake Volta in Ghana was acquired March 31, 2002 by the Moderate Resolution Imaging Spectroradiometer (MODIS). Lake Volta is one of the world's largest artificially created lakes. Lake Volta is actually a reservoir formed from the damming of the Volta River, and extends 250 miles north of the Akosombo Dam. The lake covers an area of 8,482 square km. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  4. Texas' Natural Lake 

    E-print Network

    Wythe, Kathy

    2006-01-01

    recommendations for Caddo Lake. Environmental flows is the amount of water that needs to flow down the river to maintain the ecological system in the lake, river and flood plain. Dan Weber, the Conservancy?s northwest Louisiana program manager, said, ?We... will make recommendations for a watershed management plan that will advise agencies involved with water planning for Caddo Lake. Scientists identify Caddo Lake?s top research needs Hydrology: ? Develop correlation between Jefferson flow gauging...

  5. A Water Balance Model for assessing Hydro Climatic Variability in Tropical Lake Systems: Application to Lake Babati and Lake Emakat, Nothern Tanzania

    NASA Astrophysics Data System (ADS)

    Pericles Mbanguka, Rene; Girons Lopez, Marc; Jarsjö, Jerker

    2013-04-01

    A comprehensive understanding of lake hydrology is important to enhance the interpretation of information on past climatic variations retained in tropical lakes as well as to investigate the effect of future climate conditions on lake ecosystems. In this study, a lumped water balance model is developed to describe historical lake water levels and to investigate the impacts of hydro-climatological changes on Lake Emakat and Lake Babati, two closed tropical lakes in Northern Tanzania (East Africa). The model concept is based on maintaining the water mass balance of the lake system, which is simplified into three main modules: the lake, its catchment area and the connected groundwater reservoir. Water mass exchanges with the atmosphere occur through precipitation, the main input, and evaporation, calculated from meteorological variables using two different energy balance equations. The model also integrates lake and groundwater interaction, by letting the lake water surface balance with the water table in the surrounding groundwater reservoir after every time step. A FORTRAN code is used to solve the water balance equation on a year time step and give the lake volume change resulting from meteorological inputs. The associated lake surface area and lake level are then determined from a depth-volume-area relationship developed from a high resolution bathymetric and topographical maps of the lake and its catchment. The model parameters were calibrated using available meteorological data and corresponding lake level records. A sensitivity study to assess the relative importance of different hydro-meteorological parameters on the model response indicates that changes in cloud fraction have the largest impact on evaporation, the most important component of the water mass balance. This parameter, therefore, proved to be one of the ultimate control factors of the lakes water balance. The model application to Lake Emakat suggests that precipitation and cloud fraction changes are the only climate related factors that could justify the large volume change experienced by the Lake during a 200 year period, 10,000 years BP, as estimated by proxy data. On the other hand, the model was applied to establish the necessary ambient condition changes to produce a dry-out and an overflow condition of Lake Babati and to investigate the lake system response to future IPCC climate change projections in the study area. The model shows that a sustained temperature change of less than 3oC or a precipitation change of about 100 mm/year is sufficient to bring the lake from a dry-out to an overflow condition. Simulations of IPCC derived scenarios indicate a clear tendency of the lake to increase its volume and reach the overflow level in relatively short time (approximately 10 years). Despite the model uncertainties, mainly due to limited data, it provides a means for improved interpretation of proxy data of lake level and past climatic changes retrieved from lake sediments. Furthermore, the model ability to predict the lakes hydrological response to future variations in hydroclimatic conditions and catchment characteristics offers a valuable decision support tool for water resources management

  6. Integrating limnological characteristics of high mountain lakes into the landscape of a natural area

    USGS Publications Warehouse

    Larson, Gary L.; Wones, A.; McIntire, C.D.; Samora, B.

    1994-01-01

    A general conceptual watershed-lake model of the complex interactions among climatic conditions, watershed location and characteristics, lake morphology, and fish predation was used to evaluate limnological characteristics of high mountain lakes. Our main hypothesis was that decreasing elevation in mountainous terrain corresponds to an increase in diversity of watershed size and lake area, depth, temperature, nutrient concentrations, and productivity. A second hypothesis was that watershed location and aspect relative to climatic gradients within mountainous terrain influences the limnological characteristics of the lakes. We evaluated these hypotheses by examining watershed location, aspect and size; lake morphology; water quality; and phytoplankton and zooplankton community characteristics among high mountain forest and subalpine lakes in Mount Rainier National Park. Although many of the comparisons between all forest and subalpine lakes were statistically insignificant, the results revealed trends that were consistent with our hypotheses. The forest lake group included more lakes with larger watersheds, larger surface areas, greater depths, higher concentrations of nutrients, and higher algal biovolumes than did the group of subalpine lakes. Deep lakes, which were mostly of the forest lake type, exhibited thermal stratification and relatively high values of some of the water-quality variables near the lake bottoms. However, the highest near-surface water temperatures and phytoplankton densities and the taxonomic structures of the phytoplankton and zooplankton assemblages were more closely related to geographical location, which corresponded to a west-east climate gradient in the park, than to lake type. Some crustacean and rotifer taxa, however, were limited in distribution by lake type. Fish predation did not appear to play an important role in the structure of the crustacean zooplankton communities at the genus level with the exception of Mowich Lake, where crustacean taxa were absent from the zooplankton community. This was the only lake inhabited by a true zooplanktivourous species of fish.

  7. Lake Naivasha, Kenya

    NASA Technical Reports Server (NTRS)

    2008-01-01

    If you live in Europe and buy roses, there is a good chance that they were grown in Kenya specifically, in one of the colossal greenhouses that blot out the once wild shores of Lake Naivasha, 90km north-west of Nairobi. Some 25% of Europe's cut flowers come from Kenya. After a tentative start in the 1980s the industry is now the country's third-largest foreign-currency earner, bringing in $120m a year. But the recent violence in Kenya is having a major impact on the flower growers. A local trade union says 3,000 of the 30,000 workers employed in Naivasha's flower farms have abandoned their jobs. Kenya emerged as a flower power when Israel scaled down its own industry. It has since lost business to neighboring Ethiopia, which offers tax breaks and better security, but Naivasha's perfect intensity of sunlight and days of near-constant length should keep it on top.

    The ASTER image was acquired February 2, 2008, covers an area of 25 x 26.6 km, and is located near 0.8 degrees south latitude, 36.4 degrees east longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  8. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area. (a...to the end of the road at East Landing. (3) Access and circulatory roads in the Hozomeen developed area normally open to...

  9. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area. (a...to the end of the road at East Landing. (3) Access and circulatory roads in the Hozomeen developed area normally open to...

  10. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area. (a...to the end of the road at East Landing. (3) Access and circulatory roads in the Hozomeen developed area normally open to...

  11. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area. (a...to the end of the road at East Landing. (3) Access and circulatory roads in the Hozomeen developed area normally open to...

  12. 36 CFR 7.69 - Ross Lake National Recreation Area.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.69 Ross Lake National Recreation Area. (a...to the end of the road at East Landing. (3) Access and circulatory roads in the Hozomeen developed area normally open to...

  13. Spatial patterns of microbial community composition within Lake Erie sediments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lake Erie is a large freshwater ecosystem with three distinct basins that exhibit an east-west gradient of increasing productivity, as well as allochthonous inputs of nutrients and xenobiotics. To evaluate microbial community composition throughout this ecosystem, 435 16S rDNA environmental clones w...

  14. Exploring the Food Environment on the Spirit Lake Reservation

    ERIC Educational Resources Information Center

    Pattanaik, Swaha; Gold, Abby; McKay, Lacey; Azure, Lane; Larson, Mary

    2014-01-01

    The purpose of this research project was to understand the food environment of the Fort Totten community on the Spirit Lake reservation in east-central North Dakota, as perceived by tribal members and employees at Cankdeska Cikana Community College (CCCC). According to a 2010 report from the Center for Disease Control and Prevention, the food…

  15. 27 CFR 9.169 - Red Hills Lake County.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... intersection with the 1,400-foot contour line, section 3, T12N, R7W (Clearlake Highlands Quadrangle); then (2) Proceed east-southeasterly along the meandering 1,400-foot contour line onto the Lower Lake map south of Anderson Flat, then reverse direction with the contour line and continue westerly, leaving the Lower...

  16. 27 CFR 9.169 - Red Hills Lake County.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... intersection with the 1,400-foot contour line, section 3, T12N, R7W (Clearlake Highlands Quadrangle); then (2) Proceed east-southeasterly along the meandering 1,400-foot contour line onto the Lower Lake map south of Anderson Flat, then reverse direction with the contour line and continue westerly, leaving the Lower...

  17. 13. ORE DOCK, LOOKING EAST FROM HULETT NO. 1. WHEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. ORE DOCK, LOOKING EAST FROM HULETT NO. 1. WHEN BUILT IN 1911-1912, THIS WAS THE LARGEST ORE-UNLOADING DOCK ON THE GREAT LAKES. THE DOCK FEATURED FOUR HULETT UNLOADERS, EACH WITH A BUCKET CAPACITY OF 17 TONS; A 15-TON CAPACITY ORE STOCKING AND REHANDLING BRIDGE; AND A ONE-MILLION-TON CAPACITY ORE STORAGE YARD. THE WILLIAM-SEAVER-MORGAN COMPANY OF CLEVELAND BUILT THE DOCK EQUIPMENT. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  18. The genomic substrate for adaptive radiation in African cichlid fish.

    PubMed

    Brawand, David; Wagner, Catherine E; Li, Yang I; Malinsky, Milan; Keller, Irene; Fan, Shaohua; Simakov, Oleg; Ng, Alvin Y; Lim, Zhi Wei; Bezault, Etienne; Turner-Maier, Jason; Johnson, Jeremy; Alcazar, Rosa; Noh, Hyun Ji; Russell, Pamela; Aken, Bronwen; Alföldi, Jessica; Amemiya, Chris; Azzouzi, Naoual; Baroiller, Jean-François; Barloy-Hubler, Frederique; Berlin, Aaron; Bloomquist, Ryan; Carleton, Karen L; Conte, Matthew A; D'Cotta, Helena; Eshel, Orly; Gaffney, Leslie; Galibert, Francis; Gante, Hugo F; Gnerre, Sante; Greuter, Lucie; Guyon, Richard; Haddad, Natalie S; Haerty, Wilfried; Harris, Rayna M; Hofmann, Hans A; Hourlier, Thibaut; Hulata, Gideon; Jaffe, David B; Lara, Marcia; Lee, Alison P; MacCallum, Iain; Mwaiko, Salome; Nikaido, Masato; Nishihara, Hidenori; Ozouf-Costaz, Catherine; Penman, David J; Przybylski, Dariusz; Rakotomanga, Michaelle; Renn, Suzy C P; Ribeiro, Filipe J; Ron, Micha; Salzburger, Walter; Sanchez-Pulido, Luis; Santos, M Emilia; Searle, Steve; Sharpe, Ted; Swofford, Ross; Tan, Frederick J; Williams, Louise; Young, Sarah; Yin, Shuangye; Okada, Norihiro; Kocher, Thomas D; Miska, Eric A; Lander, Eric S; Venkatesh, Byrappa; Fernald, Russell D; Meyer, Axel; Ponting, Chris P; Streelman, J Todd; Lindblad-Toh, Kerstin; Seehausen, Ole; Di Palma, Federica

    2014-09-18

    Cichlid fishes are famous for large, diverse and replicated adaptive radiations in the Great Lakes of East Africa. To understand the molecular mechanisms underlying cichlid phenotypic diversity, we sequenced the genomes and transcriptomes of five lineages of African cichlids: the Nile tilapia (Oreochromis niloticus), an ancestral lineage with low diversity; and four members of the East African lineage: Neolamprologus brichardi/pulcher (older radiation, Lake Tanganyika), Metriaclima zebra (recent radiation, Lake Malawi), Pundamilia nyererei (very recent radiation, Lake Victoria), and Astatotilapia burtoni (riverine species around Lake Tanganyika). We found an excess of gene duplications in the East African lineage compared to tilapia and other teleosts, an abundance of non-coding element divergence, accelerated coding sequence evolution, expression divergence associated with transposable element insertions, and regulation by novel microRNAs. In addition, we analysed sequence data from sixty individuals representing six closely related species from Lake Victoria, and show genome-wide diversifying selection on coding and regulatory variants, some of which were recruited from ancient polymorphisms. We conclude that a number of molecular mechanisms shaped East African cichlid genomes, and that amassing of standing variation during periods of relaxed purifying selection may have been important in facilitating subsequent evolutionary diversification. PMID:25186727

  19. Poster #Poster # We sampled lake sediments collected from forearc lakes along a transect from just west of

    E-print Network

    Goldfinger, Chris

    using a modified Livingstone corer deployed from a small floating platform. The lakes are (west to east with offshore cores and find that the downcore variability in physical properties match the offshore cores equally well. Given the evidence for earthquake origin for the offshore cores, and the strong common

  20. Climatological characteristics and orographic enhancement of lake-effect precipitation over eastern Lake Ontario and the Tug Hill Plateau

    NASA Astrophysics Data System (ADS)

    Veals, Peter Gregory

    The Tug Hill Plateau of upstate New York rises approximately 500 m above Lake Ontario, observes frequent (often heavy) lake-effect snowfall, and is one of the snowiest regions in the eastern United States. This work presents a climatology of lake-effect precipitation created using data from the KTYX WSR-88D radar situated atop the plateau. Base reflectivity imagery was manually examined to identify lake-effect periods (LEPs) during each cool season (16 Sep--15 May) from 16 Sep 2001--15 May 2014. The most active months for lake effect in this region are December and January. There is a tendency for LEPs to begin within a few hours before and after sunset in the spring and fall, with no such diurnal signal observed in the winter. Correspondingly, lake effect is slightly more frequent at night than during the day. Overall, the diurnal variability is weaker than found over smaller bodies of water such as the Great Salt Lake of Utah. Classification of events by morphological type revealed that broad coverage and long-lake-axis-parallel (LLAP) account for ~72% and ~24% of lake-effect hours, respectively. The diurnal signal for broad coverage (LLAP) events was less (more) pronounced than for LEPs in general. The near-shore areas south and east of Lake Ontario receive the most frequent lake-effect precipitation. The Tug Hill Plateau produces a strong orographic signal, with an echo frequency maximum on the western (typically windward) slope. Data from cooperative observer (COOP) sites and the Snow Data Assimilation System (SNODAS) corroborate these radar-derived results. The `broadening' of high echo frequency over the Tug Hill Plateau, as well as the existence of the lake-orographic morphology, may point to inland/orographic intensification and generation of precipitation during some LEPs.

  1. EMERALD LAKE DAY HIKE Description

    E-print Network

    Lawrence, Rick L.

    EMERALD LAKE DAY HIKE Description Cost Equipment List Sign-Up Deadline You must be signed up by 5 of lodgepole pine, Engelmann spruce and subalpine r leading to Emerald Lake and Heather Lake. The lakes

  2. Radio-echo sounding of 'active' Antarctic subglacial lakes

    NASA Astrophysics Data System (ADS)

    Siegert, M. J.; Ross, N.; Blankenship, D. D.; Young, D. A.; Greenbaum, J. S.; Richter, T.; Rippin, D. M.; Le Brocq, A. M.; Wright, A.; Bingham, R.; Corr, H.; Ferraccioli, F.; Jordan, T. A.; Smith, B. E.; Payne, A. J.; Dowdeswell, J. A.; Bamber, J. L.

    2013-12-01

    Repeat-pass satellite altimetry has revealed 124 discrete surface height changes across the Antarctic Ice Sheet, interpreted to be caused by subglacial lake discharges (surface lowering) and inputs (surface uplift). Few of these active lakes have been confirmed by radio-echo sounding (RES) despite several attempts, however. Over the last 5 years, major geophysical campaigns have acquired RES data from several 'active' lake sites, including the US-UK-Australian ICECAP programme in East Antactica and the UK survey of the Institute Ice Stream in West Antarctica. In the latter case, a targeted RES survey of one 'active' lake was undertaken. RES evidence of the subglacial bed beneath 'active' lakes in both East and West Antarctica will be presented, and the evidence for pooled subglacial water from these data will be assessed. Based on this assessment, the nature of 'active' subglacial lakes, and their associated hydrology and relationship with surrounding topography will be discussed, as will the likelihood of further 'active' lakes in Antarctica. Hydraulic potential map of the Byrd Glacier catchment with contours at 5 MPa intervals. Predicted subglacial flowpaths are shown in blue. Subglacial lakes known from previous geophysical surveys are shown as black triangles while the newly discovered 'Three-tier lakes' are shown in dashed black outline. Surface height change features within the Byrd subglacial catchment are shown in outline and are shaded to indicate whether they were rising or falling during the ICESat campaign. Those features are labelled in-line with the numbering system of Smith et al. (J. Glac. 2009).

  3. Geologic map of Medicine Lake volcano, northern California

    USGS Publications Warehouse

    Donnelly-Nolan, Julie M.

    2011-01-01

    Medicine Lake volcano forms a broad, seemingly nondescript highland, as viewed from any angle on the ground. Seen from an airplane, however, treeless lava flows are scattered across the surface of this potentially active volcanic edifice. Lavas of Medicine Lake volcano, which range in composition from basalt through rhyolite, cover more than 2,000 km2 east of the main axis of the Cascade Range in northern California. Across the Cascade Range axis to the west-southwest is Mount Shasta, its towering volcanic neighbor, whose stratocone shape contrasts with the broad shield shape of Medicine Lake volcano. Hidden in the center of Medicine Lake volcano is a 7 km by 12 km summit caldera in which nestles its namesake, Medicine Lake. The flanks of Medicine Lake volcano, which are dotted with cinder cones, slope gently upward to the caldera rim, which reaches an elevation of nearly 8,000 ft (2,440 m). The maximum extent of lavas from this half-million-year-old volcano is about 80 km north-south by 45 km east-west. In postglacial time, 17 eruptions have added approximately 7.5 km3 to its total estimated volume of 600 km3, and it is considered to be the largest by volume among volcanoes of the Cascades arc. The volcano has erupted nine times in the past 5,200 years, a rate more frequent than has been documented at all other Cascades arc volcanoes except Mount St. Helens.

  4. Lake Nasser and Toshka Lakes, Egypt

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Lake Nasser (center) and the Toshka Lakes (center left) glow emerald green and black in this MODIS true-color image acquired March 8, 2002. Located on and near the border of Egypt and Norther Sudan, these lakes are an oasis of water in between the Nubian (lower right) and Libyan Deserts (upper left). Also visible are the Red Sea (in the upper right) and the Nile River (running north from Lake Nasser). Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  5. Hydrologic conditions and lake-level fluctuations at Long Lost Lake, 1939-2004, White Earth Indian Reservation, Clearwater County, Minnesota

    USGS Publications Warehouse

    Christensen, Victoria G.; Bergman, Andrea L.

    2005-01-01

    Long Lost Lake, a closed-basin lake in Clearwater County, Minnesota, has had a substantial rise in lake level since 1990. The increased level and surface area of the lake has led to the inundation of nearby homes and roads. The U.S. Geological Survey, in cooperation with the White Earth Band of Chippewa Indians, conducted a study to document the historical lake-level fluctuations, to investigate reasons for hydrologic change, and to develop a general understanding of the hydrology of lakes that have had rapid changes in lake level. Lake levels were recorded continuously from August 2003 through December 2004. The purpose was to establish a temporal, detailed record of lake levels and to connect this record to precipitation and ground-water-level data. A long-term record is critical to understanding the relation between surface water and ground water. This is especially true for closed-basin lakes. Between August 2003 and December 2004, the lake level generally declined. The highest lake altitude was 492.58 meters above NAVD 88 on August 5, 2003, and the low of 492.11 meters above NAVD 88 occurred on August 29, 2004. Results of water-level measurements in 5 observation wells and 14 wetlands and ponds show that the water-table level is substantially higher on the north side of the lake than the lake level, providing the head pressure necessary for ground-water discharge into Long Lost Lake. In contrast, on the south and east sides of the lake, water-table levels are similar to the lake level. This indicates a general north-northwest to south-southeast ground-water flow direction. Results of a synoptic survey of lake temperature and other measurements supported the direction of water inflow and outflow. Aerial photography and a geographic information system were used to construct a historical lake record from 1939 to 2001. Lake-level increases match similar increases in precipitation, indicating a strong link between the two. Results show that lake-level increases in Long Lost Lake appear to primarily be due to natural rather than anthropogenic effects.

  6. Dispersal of three strains of hatchery-reared lake trout in Lake Ontario

    USGS Publications Warehouse

    Elrod, Joseph H.

    1987-01-01

    Rates of dispersal and resultant geographical distributions were determined for three strains of hatchery-reared lake trout (Salvelinus namaycush) stocked at six sites in U.S. waters of Lake Ontario. The strains were Lake Superior (SUP); Clearwater Lake, Manitoba (CWL); and Seneca Lake, New York (SEN). The fish were recovered with bottom trawls fished during July and August 1980-1985 at 16 locations, extending from Toronto southward and eastward along the south shore to Dablon Point at the east end of the lake. For SUP fish stocked as spring yearlings, the mean distances from stocking site to capture location 2, 14, and 26 months after stocking were 12, 57, and 62 km, respectively, for fish released at four south-shore sites and 5, 34, and 38 km for fish released at two eastern outlet basin sites. Rates of dispersal for the CWL fish were similar to those of the SUP strain for fish stocked at the four south-shore sites, but were considerably less for fish stocked in the eastern outlet basin. The SEN strain was stocked only in the eastern outlet basin; their dispersal was similar to that of the SUP strain. For fish of the same age, SUP fish stocked as fall fingerlings became more widely dispersed than those stocked as spring yearlings. Movement of lake trout between the eastern outlet basin and the lake proper was limited. Large numbers of fish were captured on the Niagara Bar, but few moved past there into the west end of the lake. Movements of lake trout from stocking sites were generally with the prevailing currents. Differences between geographical distributions of the SUP and CWL strains were probably due to the influence of different current regimes at the depths they occupied. These results will be useful in selecting the best genetic strains of lake trout for rehabilitating the species in Lake Ontario, as well as for identifying the best stocking sizes and maximizing post-stocking survival of hatchery-reared fish.

  7. Cliffs of Diablo East

    USGS Multimedia Gallery

    Amistad National Recreation Area includes the Amistad Reservoir, a man-made lake along the Texas and Mexico border. It is fed by the Rio Grande, Devils River, and the Pecos River, among others.    ...

  8. 1. OVERVIEW OF EXTREME EAST END OF BIG CREEK TOWN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. OVERVIEW OF EXTREME EAST END OF BIG CREEK TOWN ACROSS POWERHOUSE NO. 2 FOREBAY (POWERHOUSE NO. 1 AFTERBAY). TOWER CARRYING TRANSMISSION LINES FROM POWERHOUSE NO. 1 IS AT PHOTO CENTER. BEHIND TOWER IS BUILDING 103. TO PHOTO LEFT OF BUILDING 103 IS BUILDING 105. VIEW TO NORTH. - Big Creek Hydroelectric System, Big Creek Town, Operator House, Orchard Avenue south of Huntington Lake Road, Big Creek, Fresno County, CA

  9. 88. Photocopied August 1978. STATION GENERATORS LOOKING EAST FROM THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    88. Photocopied August 1978. STATION GENERATORS LOOKING EAST FROM THE CENTRAL GALLERY, AUGUST 11, 1914. BY THIS DATE MICHIGAN NORTHERN HAD COMPLETED THE INSTALLATION OF GENERATORS IN THE EASTERN HALF OF THE POWER HOUSE AND HAD BEGUN WORK ON THE WEST. THE MOTOR-GENERATORS PURSHASED BY THE M.L.S.P.C. IN 1902 CAN BE SEEN ON THE LEFT BY THE LINE OF COLUMNS. (910) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  10. 79. Photocopied August 1978. ELECTRICAL INSTALLATION LOOKING EAST, JANUARY 1, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    79. Photocopied August 1978. ELECTRICAL INSTALLATION LOOKING EAST, JANUARY 1, 1903, SHOWING ONE OF THE STANLEY D.C. GENERATORS IN THE CENTER FOREGROUND, AND, IN THE BACKGROUND, A ROW OF STANLEY THREE-PHASE ALTERNATORS. THE SWITCHBOARD WAS LATER PLACED ON A GALLERY WHICH PROJECTED OVER THIS LINE OF GENERATORS. (449) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  11. Utah: Salt Lake Region

    Atmospheric Science Data Center

    2014-05-15

    article title:  Winter and Summer Views of the Salt Lake Region     View Larger Image Magnificent views of the region surrounding Salt Lake City, Utah are captured in these winter and summer images from the ...

  12. Cladophora Along Lake Michigan

    USGS Multimedia Gallery

    Large patches of Cladophora, a green algae, lining the shore of Lake Michigan. Accumulation of Cladophora in shoreline waters is believed to be linked to avian botulism outbreaks, which have recently increased in the Great Lakes. ...

  13. Lake Michigan Sand Waves

    USGS Multimedia Gallery

    Calm Lake Michigan morning while sampling dead and dying fish for viral hemorrhagic septicemia virus (VHSV). This virus has recently emerged in the Great Lakes and caused severe epidemics in many fish species....

  14. Lakes Ecosystem Services Online

    EPA Science Inventory

    Northeastern lakes provide valuable ecosystem services that benefit residents and visitors and are increasingly important for provisioning of recreational opportunities and amenities. Concurrently, however, population growth threatens lakes by, for instance, increasing nutrient ...

  15. Venezuela: Lake Maracaibo

    Atmospheric Science Data Center

    2013-04-18

    article title:  Oil Slicks on Lake Maracaibo, Venezuela     View Larger Image ... oil slicks occurred on Lake Maracaibo in northwestern Venezuela between December 2002 and January 2003, and were observed by various ...

  16. Quebec: Lake Manicouagan

    Atmospheric Science Data Center

    2013-04-17

    ... lake is bounded by erosion-resistant metamorphic and igneous rocks, and shock metamorphic effects are abundant in the target rocks of the crater floor. Today Lake Manicouagan serves as a reservoir and is ...

  17. Geology and geomorphology of Bear Lake Valley and upper Bear River, Utah and Idaho

    USGS Publications Warehouse

    Reheis, M.C.; Laabs, B.J.C.; Kaufman, D.S.

    2009-01-01

    Bear Lake, on the Idaho-Utah border, lies in a fault-bounded valley through which the Bear River flows en route to the Great Salt Lake. Surficial deposits in the Bear Lake drainage basin provide a geologic context for interpretation of cores from Bear Lake deposits. In addition to groundwater discharge, Bear Lake received water and sediment from its own small drainage basin and sometimes from the Bear River and its glaciated headwaters. The lake basin interacts with the river in complex ways that are modulated by climatically induced lake-level changes, by the distribution of active Quaternary faults, and by the migration of the river across its fluvial fan north of the present lake. The upper Bear River flows northward for ???150 km from its headwaters in the northwestern Uinta Mountains, generally following the strike of regional Laramide and late Cenozoic structures. These structures likely also control the flow paths of groundwater that feeds Bear Lake, and groundwater-fed streams are the largest source of water when the lake is isolated from the Bear River. The present configuration of the Bear River with respect to Bear Lake Valley may not have been established until the late Pliocene. The absence of Uinta Range-derived quartzites in fluvial gravel on the crest of the Bear Lake Plateau east of Bear Lake suggests that the present headwaters were not part of the drainage basin in the late Tertiary. Newly mapped glacial deposits in the Bear River Range west of Bear Lake indicate several advances of valley glaciers that were probably coeval with glaciations in the Uinta Mountains. Much of the meltwater from these glaciers may have reached Bear Lake via groundwater pathways through infiltration in the karst terrain of the Bear River Range. At times during the Pleistocene, the Bear River flowed into Bear Lake and water level rose to the valley threshold at Nounan narrows. This threshold has been modified by aggradation, downcutting, and tectonics. Maximum lake levels have decreased from as high as 1830 m to 1806 m above sea level since the early Pleistocene due to episodic downcutting by the Bear River. The oldest exposed lacustrine sediments in Bear Lake Valley are probably of Pliocene age. Several high-lake phases during the early and middle Pleistocene were separated by episodes of fluvial incision. Threshold incision was not constant, however, because lake highstands of as much as 8 m above bedrock threshold level resulted from aggradation and possibly landsliding at least twice during the late-middle and late Pleistocene. Abandoned stream channels within the low-lying, fault-bounded region between Bear Lake and the modern Bear River show that Bear River progressively shifted northward during the Holocene. Several factors including faulting, location of the fluvial fan, and channel migration across the fluvial fan probably interacted to produce these changes in channel position. Late Quaternary slip rates on the east Bear Lake fault zone are estimated by using the water-level history of Bear Lake, assuming little or no displacement on dated deposits on the west side of the valley. Uplifted lacustrine deposits representing Pliocene to middle Pleistocene highstands of Bear Lake on the footwall block of the east Bear Lake fault zone provide dramatic evidence of long-term slip. Slip rates during the late Pleistocene increased from north to south along the east Bear Lake fault zone, consistent with the tectonic geomorphology. In addition, slip rates on the southern section of the fault zone have apparently decreased over the past 50 k.y. Copyright ?? 2009 The Geological Society of America.

  18. Dongting Lake, China

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These images show dramatic change in the water at Dongting Lake in Hunan province, China. A flood crest surged down the Yangtze River in late August of this year, but the embankments made by residents there held. The left image was acquired on September 2, 2002 and shows the extent of the lake. The right image was obtained March 19, 2002 before the flooding began.

    These images were acquired on September 2, 2002 and March 19,2002 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. The Terra mission is part of NASA's Earth Science Enterprise, a long-term research and technology program designed to examine Earth's land, oceans, atmosphere, ice and life as a total integrated system.

    Size: 39.1 x 119.4 km (22.4 x 74.0 miles)Location: 30.1 deg. North lat., 112.9 deg. East long. Orientation: North at top Image Data: ASTER bands 1,2, and 3. Original Data Resolution: 15 mDates Acquired: September 2 and March 19, 2002

  19. 77 FR 41686 - Safety Zone; Sheffield Lake Fireworks, Lake Erie, Sheffield Lake, OH

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-16

    ...Fireworks, Lake Erie, Sheffield Lake, OH AGENCY: Coast Guard, DHS. ACTION: Temporary...safety zone on Lake Erie, Sheffield Lake, OH. This safety zone is intended to restrict...held on Lake Erie near Sheffield Lake, OH. The Captain of the Port Buffalo has...

  20. Revisiting the West Clearwater Lake Impact Structure, Canada

    NASA Technical Reports Server (NTRS)

    Osinski, G. R.; Brunner, A.; Collins, G.; Cohen, B. A.; Coulter, A.; Elphic, R.; Grieve, R. A. F.; Hodges, K.; Horne, A.; Kerrigan, M.

    2015-01-01

    The West and East Clearwater Lake impact structures are two of the most distinctive and recognizable impact structures on Earth. Known regionally as the "Clearwater Lake Complex", these structures are located in northern Quebec, Canada (56 deg 10 N, 74 deg 20 W) approximately 125 km east of Hudson Bay. The currently accepted diameters are 36 km and 26 km for the West and East structures, respectively. Long thought to represent a rare example of a double impact, recent age dating has called this into question with ages of approximately 286 Ma and approximately 460-470 Ma being proposed for the West and East structures, respectively. Relatively little is known about the East Clearwater Lake structure. There is no surface exposure and what information there is comes from geophysics and two drill cores obtained in the 1960s. In contrast, the West Clearwater Lake structure is relatively well preserved with large ring of islands in the approximately 30 km diameter lake. Much of the work done on West Clearwater stems from field investigations carried out in 1977 driven by the Apollo program, with a focus on the impact melt rocks and other impactites, which are well exposed on the ring of islands. To our knowledge, the Clearwater Lake impact structures have not been the focus of detailed impact geology field investigations since the 1977 expedition and the only geological map that exists is from the 1960s and is at the reconnaissance level. Our knowledge of impact cratering processes have increased substantially since this time, as have the analytical techniques available for samples. This provided the motivation for a joint Canadian-US-UK expedition to the West Clearwater Lake impact structure in August and September 2015, under the auspices of the FINESSE (Field Investigations to Enable Solar System Science and Exploration) project, part of NASA's Solar System Exploration Research Virtual Institute (SSERVI). We focus here on the impactites of the West Clearwater Lake impact structure. Other ongoing studies, also presented at this conference, focus on central uplift formation, the impact-generated hydrothermal system, xxxx and using WCIS as an analog test site for crew studies of sampling protocols].

  1. Great Minds? Great Lakes!

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Chicago, IL. Great Lakes National Program Office.

    This book contains lesson plans that provide an integrated approach to incorporating Great Lakes environmental issues into elementary subjects. The book is divided into three subject areas: (1) History, which includes the origins of the Great Lakes, Great Lakes people, and shipwrecks; (2) Social Studies, which covers government, acid rain as a…

  2. A Killer Lake

    ERIC Educational Resources Information Center

    Horvath, Thomas

    2005-01-01

    In 1986, Lake Nyos, a volcanic lake in Cameroon, released a huge amount of carbon dioxide gas, killing over 1,700 people in the surrounding area. This case study, developed for use in a limnology or aquatic biology course, explores that event, introducing students to concepts relating to lake formation, thermal stratification, and dissolved gases.…

  3. Exploding Lakes in Cameroon

    USGS Multimedia Gallery

    In 1986, Lake Nyos, in the volcanic region of Cameroon, released a cloud of CO2 into the atmosphere, killing 1,700 people and 3,500 livestock in nearby towns and villages. Since then, engineers have been artificially removing the gas from the lake through piping. A small CO2 cloud from Lake Monoun k...

  4. Exploding Lakes in Cameroon

    USGS Multimedia Gallery

    In 1986, Lake Nyos, in the volcanic region of Cameroon, released a cloud of CO2 into the atmosphere, killing 1,700 people and 3,500 livestock in nearby towns and villages. Since then, engineers have been artificially removing the gas from the lake through piping. This photo shows the Lake Nyos pipe ...

  5. MOUNTAIN LAKE USER HANDBOOK

    E-print Network

    Huang, Wei

    MOUNTAIN LAKE BIOLOGICAL STATION USER HANDBOOK Updated: 02 June 2015 #12;2 #12;3 Fundamental Code, and Purchases ------------------------------------------------------------ 14 The Mountain Lake Lodge;4 #12;5 Welcome Welcome to the Mountain Lake Biological Station! MLBS was established in 1929

  6. MOUNTAIN LAKE BIOLOGICAL STATION

    E-print Network

    McGlothlin, Joel W.

    MOUNTAIN LAKE BIOLOGICAL STATION USER HANDBOOK Updated: 07Mar2013 For the most, Accounts, and Purchases . . . 14 The Mountain Lake Hotel . . . 15 Calendar and Summer . . . . 23 Contact informa on . . . . 24 #12;4 #12;5 Welcome Welcome to the Mountain Lake

  7. Lake Layers: Stratification.

    ERIC Educational Resources Information Center

    Brothers, Chris; And Others

    This teacher guide and student workbook set contains two learning activities, designed for fifth through ninth grade students, that concentrate on lake stratification and water quality. In the activities students model the seasonal temperature changes that occur in temperate lakes and observe the resulting stratification of lake waters. Students…

  8. Great Lakes: Chemical Monitoring

    ERIC Educational Resources Information Center

    Delfino, Joseph J.

    1976-01-01

    The Tenth Great Lakes Regional Meeting of the American Chemical Society met to assess current Chemical Research activity in the Great Lakes Basin, and addressed to the various aspects of the theme, Chemistry of the Great Lakes. Research areas reviewed included watershed studies, atmospheric and aquatic studies, and sediment studies. (BT)

  9. 19. VIEW OF CRUDE ORE BINS FROM EAST. EAST CRUDE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. VIEW OF CRUDE ORE BINS FROM EAST. EAST CRUDE ORE BIN IN FOREGROUND WITH DISCHARGE TO GRIZZLY AT BOTTOM OF VIEW. CONCRETE RETAINING WALL TO LEFT (SOUTH) AND BOTTOM (EAST EDGE OF EAST BIN). - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

  10. Characteristics of water-quality data for Lake Houston, selected tributary inflows to Lake Houston, and the Trinity River near Lake Houston (a potential source of interbasin transfer), August 1983-September 1990

    USGS Publications Warehouse

    Liscum, Fred; Goss, R.L.; Rast, Walter

    1999-01-01

    Lake Houston, a reservoir completed in 1954 about 25 miles east-northeast of Houston, Texas, is a principal surface-water source for the city of Houston. The increase in water supply to meet future demands is expected to be accommodated by supplementing surface-water inflows to Lake Houston. The Trinity River is considered a potential source for interbasin transfer of water to Lake Houston. Before beginning to supplement inflows, the City needs to better understand the potential effects on Lake Houston water quality from streams that flow into or might contribute water to Lake Houston. During 1983?90, the USGS collected 3,727 water-quality samples from 27 sites in Lake Houston, 6 of the 7 main tributaries to the lake, and the Trinity River at Romayor. Longitudinal profiles of water temperature, dissolved oxygen, specific conductance, pH, and nutrients from the dam to the East and West Forks of Lake Houston constructed for a winter day and a summer day indicate that in general the lake water is mixed in the winter and stratified in the summer. The results of Mann-Whitney rank-sum tests to determine whether there were significant differences between summer and non-summer field measurements, 5-day biological oxygen demand, bacteria, physical and aesthetic properties, nutrients, organic carbon, chlorophyll a, and trace elements in the lake nearest the dam, the East Fork of the lake, and the West Fork of the lake at the same relative depth showed significant differences between summer and non-summer samples for at least one of the three locations at the same relative depth for all 15 properties and constituents tested except specific conductance. The test results indicate that in general Lake Houston is well mixed in the non-summer period and stratified with respect to selected properties and constituents in the summer. The results of rank-sum tests to determine whether there were significant differences between field measurements, 5-day biological oxygen demand, physical and aesthetic properties, nutrients, organic carbon, and chlorophyll a in the lake nearest the dam, the East Fork of the lake, and the West Fork of the lake for samples collected during the same season at the same relative depth showed that significant differences were common; generally, the West Fork had the largest median concentrations among the three locations. The tests comparing trace element concentrations between the lake nearest the dam and the East Fork showed mixed results?large median dissolved manganese concentrations in lake bottom samples in the summer and in East Fork near-surface samples in the non-summer period. The results of rank-sum tests comparing selected properties, 5-day biological oxygen demand, bacteria, nutrients, and total organic carbon in the eastern tributaries with those in the western tributaries, in the eastern tributaries with those in the Trinity River, and in the western tributaries with those in the Trinity River during the same season (summer or non-summer) at the same relative streamflow (low-medium or high) showed that significant differences were more common than not. In the comparisons of the eastern tributaries with the western tributaries that resulted in significant differences, medians of the western tributaries were larger for all properties and constituents except total organic carbon; in the comparisons of the eastern tributaries with the Trinity River that resulted in significant differences, medians were larger for the Trinity River in about 60 percent of the tests; and in the comparisons of the western tributaries with the Trinity River that resulted in significant differences, medians were larger for the western tributaries in about 60 percent of the tests. In the tests comparing trace elements between the eastern and western tributaries during the same season at the same relative streamflow, five of the eight tests showed no significant differences; between the eastern tributaries and the Trini

  11. Evaluating the Impact of Gilgel Gibe Dam on the Lake Turkana Water Levels: An Illustration from an Endorheic Lake in Africa

    NASA Astrophysics Data System (ADS)

    Velpuri, N.; Senay, G. B.

    2010-12-01

    Lake Turkana is one of the lakes in the Great Rift Valley, Africa. This lake has no outlet hence it is considered as closed or endorheic lake. To meet the demand of electricity in the east African region, Ethiopia is currently building Gilgel Gibe-III dam on the Omo River, which supplies up to 80% of the inflows to the Lake Turkana. On completion, this dam would be the tallest dam in Africa with a height of 241 m. As Lake Turkana is highly dependent on the inflows from the Omo River, the construction of this dam could potentially pose a threat to the downstream river valley and to Lake Turkana. This hydroelectric project is arguably one of the most controversial projects in the region. The impact of the dam on the lake is evaluated using Remote Sensing datasets and hydrologic modeling. First, lake water levels (1998-2007) were estimated using the Simplified Lake Water Balance (SLAB) approach which takes in satellite based rainfall estimates, modeled runoff and evapotranspiration data over the Turkana basin. Modeled lake levels were validated against TOPEX/POSIEDON/Jason-1 satellite altimeter data. Validation results showed that the model could capture observed trends and seasonal variations in lake levels. The fact that the lake is endorheic makes it easy to model the lake levels. Using satellite based estimates for the years 1998-2009, future scenarios for rainfall and evapotranspiration were generated using the Monte Carlo simulation approach and the impact of Gilgel Gibe-III dam on the Lake Turkana water levels is evaluated using SLAB approach. Preliminary results indicate that the impact of the dam on the lake would vary with the initial water level in the lake at the time of dam commissioning. It was found that during the initial period of dam/reservoir filling the lake level would drop up to 2-3 m (95% confidence interval). However, on average the lake would stabilize within 10 years from the date of commissioning. The variability within the lake levels due to reduced inflows after the dam commissioning were found to be within the natural variability of the lake (0-5 m). The use of cost free satellite based estimates for runoff and evapotranspiration modeling makes this approach consistent and credible. It is also easy to replicate on any other dam in the world. Results obtained from this approach are very valuable and would aid decision makers and environmentalists in proper decision making.

  12. Middle East activity abounds

    SciTech Connect

    Not Available

    1981-06-20

    Development and exploration activity in most of the countries in the Mid East has multiplied dramatically amidst overshadowing influences like war and regulations. This on-the-scene report examines their projects, progress.

  13. Food of lake trout in Lake Superior

    USGS Publications Warehouse

    Dryer, William R.; Erkkila, Leo F.; Tetzloff, Clifford L.

    1965-01-01

    Stomachs were examined from 1,492 lake trout and 83 siscowets collected from Lake Superior. Data are given on the food of lake trout of legal size (17 inches or longer) by year, season, and depth of water, and on the relation between food and size among smaller lake trout. Fish contributed 96.7 to 99.9 per cent of the total volume of food in the annual samples. Ciscoes (Coregonus spp.) were most common (52.2 to 87.5 per cent of the volume) in 1950 to 1953 and American smelt ranked first (65.6 per cent of the volume) in 1963. Cottids were in 8.9 to 12.3 per cent of the stomachs in 1950 to 1953 but in only 4.3 per cent in 1963. Insects ranked second to fish in occurrence (9.6 per cent for the combined samples) and crustaceans followed at 3.9 per cent. The greatest seasonal changes in the food of lake trout were among fish caught at 35 fathoms and shallower. The occurrence of Coregonus increased from 34.6 per cent in February-March to 71.1 per cent in October-December. Smelt were in 76.9 per cent of the stomachs in February-March but in only 2.2 per cent in October-December. Cottids, Mysis relicta, and insects were most common in the July-September collections. Lake trout taken at depths greater than 35 fathoms had eaten a higher percentage of Cottidae and Coregonus than had those captured in shallower water. Smelt, ninespine sticklebacks, Mysis, and insects were more frequent in stomachs of lake trout from less than 35 fathoms. Crustaceans comprised more than 70 per cent of the total volume of food for 4.0- to 7.9-inch lake trout but their importance decreased as the lake trout grew larger. Pontoporeia affinis was the most common in the stomachs of 4.0- to 6.9-inch lake trout and Mysis held first rank at 7.0 to 12.9 inches. Ostracods were important only to 4.0- to 4.9-inch lake trout. As the lake trout became larger, the importance of fish grew from 4.4-per cent occurrence at 5.0 to 5.9 inches to 93.9 per cent at 16.0 to 16.9 inches. Smelt were most commonly eaten by undersize (less than 17 inches) lake trout.

  14. A full lipid biomarker based record from Lake Challa, Tanzania

    NASA Astrophysics Data System (ADS)

    Blaga, C. I.; de Leeuw, J. W.; Verschuren, D.; Sinninghe Damsté1, J. S.

    2012-04-01

    The climate of the regions surrounding the Indian Ocean - East Africa, Arabian and Indian peninsulas - is strongly dominated by the dynamics of the seasonal monsoon. To understand the long and short term driving forces behind the natural climatic variability in this region it is highly important to reconstruct climatic changes in the past and, thereby, predict future changes taking into account also anthropogenic activities. Most low latitude locations lack continuous, highly resolved continental records with good age control. From the few existing records acquired from tropical glacier ice, cave stalagmites and fossil diatoms a thorough understanding of the climatic variations reflected (rainfall and drought or temperature and its effect on precipitation) is scanty. Chemically stratified crater lakes accumulate high-quality climate-proxy records as shown in very recent studies done on the continuous and finely laminated sediment record of Lake Challa situated on the lower East slope of Mt. Kilimanjaro (Verschuren et al. 2009; Wolff et al. 2011). The unique location of this lake in equatorial East Africa implies that the climate variability is influenced by the Indian Ocean and not by the Atlantic due to the Congo Air Boundary (Thierney et al. 2011). The objective of this study is to fully explore the biomarker content of the Lake Challa sedimentary record already characterized by an excellent time resolution and chronology. Various normal chain lipids (n-alkanes, n-fatty acids, n-alcohols), sterols, long-chain diols, triterpenoids and glycolipids in sedimentary organic matter, were determined in their solvent-extractable (free) and saponification-released forms (bound). The changing composition of organic matter content from the investigated lake is used as a framework to trace palaeo-humidity, terrestrial input, algal input, temperature in sediment traps and underlying sediments of Lake Challa to further our palaeo-environmental knowledge based on GDGT's and alkanes (Sinninghe Damsté et al. 2009, 2011).

  15. River-to-lake connectivities, water renewal, and aquatic habitat diversity in the Mackenzie River Delta

    NASA Astrophysics Data System (ADS)

    Lesack, Lance F. W.; Marsh, Philip

    2010-12-01

    Past and ongoing investigations have established that lakes in the Mackenzie River Delta collectively represent gradients in water transparency, nutrient regime, and biotic communities, each strongly linked to the sill elevations of the lakes. Analysis of 40 years of water levels in East Channel of the central delta, in combination with a floodplain geometry model to estimate river water volumes added to lake waters at the annual flood peak, permitted direct estimation of annual river-to-lake connection times, lake water renewal, and interannual variabilities in nine lakes spanning the full range of sill elevations in the delta. Results have revealed a broad range of river-to-lake connectivities and river water renewals that are temporally dynamic and vary considerably among the lakes of this river delta system. Lakes with short and variable connection times plus low and variable river water renewal yield groups of lakes with high degrees of individuality because they are strongly influenced by particular sequences of antecedent years (legacy effects) that may result in lakes simultaneously containing residual waters from multiple river inundation events separated by more than a decade. Lakes with long and less varying connection times plus high river water renewal with multiple possible river water resets per year yield lakes with high degrees of similarity. The full combination of lakes arranged in an intermittently connected continuum, creating variable connectivity for aquatic organisms and water intermixing, may be an important mechanism driving the collectively distinctive habitat productivity and biodiversity of aquatic communities in this system, relative to lakes on the surrounding landscape.

  16. 46 CFR 401.407 - Basic rates and charges on Lake Erie and the navigable waters from Southeast Shoal to Port Huron...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Erie and the navigable waters from Southeast Shoal to...Area 4 (Undesignated Waters): Service Lake Erie (East ofSoutheast Shoal) Buffalo Six-Hour Period ...b) Area 5 (Designated Waters): Any point on or...

  17. Physicochemical and Analytical Data for Tributary Water, Lake Water, and Lake Sediment, Lake Arrowhead, Clay and Archer Counties, Texas, 2006

    USGS Publications Warehouse

    Wilson, Jennifer T.; Musgrove, MaryLynn; Haynie, Monti M.; Van Metre, Peter C.

    2008-01-01

    Lake Arrowhead is a reservoir about 24 kilometers southeast of Wichita Falls, Texas, that provides drinking water for the city of Wichita Falls and surrounding areas. The U.S. Geological Survey, in cooperation with the City of Wichita Falls, did a study in 2006 to assess conditions contributing to elevated arsenic concentrations in Lake Arrowhead. This report describes the sampling and analytical methods, quality assurance, and physicochemical and analytical data. Physiochemical properties were measured in and water samples were collected from five tributaries to Lake Arrowhead (Little Wichita River, West Little Post Oak Creek, East Little Post Oak Creek, Deer Creek, and an unnamed tributary) immediately after storms. Lake water measuring and sampling were done approximately monthly from January through September 2006 at three deep-water sites and seasonally, in January and August 2006, at three shallow-water sites. Cores of lake bottom sediment were collected from five sites on August 30, 2006. Arsenic concentrations in tributary water samples ranged from 1.5 to 6.3 and 0.5 to 4.8 micrograms per liter for unfiltered and filtered samples, respectively. The highest arsenic concentrations were in samples collected from the West Little Post Oak Creek sampling site. Physicochemical properties in lake water varied with depth and season. Dissolved arsenite plus arsenate concentrations in lake water samples generally were between 3 and 5 micrograms per liter. Arsenite concentrations typically were below the laboratory reporting level of 0.6 microgram per liter. There were no detections of monomethylarsonate or dimethylarsinate. The concentration of arsenic in lake sediment samples ranged from 4.4 to 11.2 milligrams per kilogram, with a median of 6.4 milligrams per kilogram. The median arsenic concentration of the five top-interval sediment samples was 8.8 milligrams per kilogram, which generally is higher than the concentrations estimated to be on suspended sediment in the tributaries. Sediment concentrations of seven trace elements were compared to two consensus-based sediment quality guidelines for each: the threshold effect concentration and the probable effect concentration. Arsenic concentration exceeded the threshold effect concentration in one top-interval sediment sample.

  18. Monitoring drying up of Urmia lake with satellite altimetry

    NASA Astrophysics Data System (ADS)

    Roohi, Shirzad; Sneeuw, Nico

    2013-04-01

    Urmia lake is a UNESCO protected area with more than a hundred small rocky islands. It is home to several species of birds and animals. Located in northwestern Iran, it is the largest lake in the Middle East and the third largest salty water lake on earth. It has a surface area of approximately 5200 km², and an average depth of 16 m. Unfortunately during the recently years Urmia lake has been shrinking. If the drought process continues at the current rate it would be disappear in the near future. The main factors that speeds up the drought rate of the lake, are dam construction on the main rivers which feeds the lake, evaporation and lack of precipitation during recent years as well as irrigation. The construction of a causeway in the middle of the lake also affects the natural ecosystem of the lake. The case of Urmia lake and similar cases in other parts of the word emphasize the role of new technology such as satellite altimetry in better management of water resource and monitoring such critical situations. In this research we show the current situation and recent past of the lake from processing 10 years of Envisat satellite radar altimetry data. For internal validation of the result, water level time series were built from ascending and descending tracks separately and for external validation in-situ gauge measurements were used. Internal and external comparisons indicates the result are consistent, i.e there is no bias and systematic error in Envisat data. The RMSE between ascending and descending tracks is several centimeters and between satellite and gauge data is 1m. Water level time series analysis shows that there is a declining rate of 0.3 m/year in the water level but after 2005 it seems to have accelerated. This rate increases the salinity of lake and expands receding shoreline rapidly so the lake bed will reveal fast because the lake is shallow especially in the south part. Following this research we are investigating to find the best re-tracker in monitoring water level of the lake and validate it against in-situ gauge measurements to determine water level more precisely. Key words: Error estimates, re-tracking algorithm.

  19. MISR Views the Middle East

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This image, generated using 16 orbits of MISR data collected between August 16 and August 30, 2000, takes us to the cradle of many civilizations. The data are from the 60-degree aftward-viewing camera. Because the individual orbit swaths are only 400 kilometers wide, they were 'mosaiced' together to form this composite picture, which covers about 2700 kilometers from west to east and 1750 kilometers from north to south. A few discontinuities are present in the mosaic, particularly near clouds, due to changes in the scene which occurred between dates when the individual orbit data were acquired.

    At the northern tip of the Red Sea, the Gulf of Suez and the Gulf of Aqaba frame the sandy deserts and spectacular mountains of the Sinai Peninsula. The highest peaks are Gebel Katherina (Mountain of St. Catherine, 2637 meters) and Gebel Musa (Mountain of Moses, also known as Mount Sinai, 2285 meters). To the northeast, Israel and Jordan flank the Dead Sea, one of the saltiest inland water bodies in the world. At its northern edge is Qumran, where the ancient Scrolls were discovered; the city of Jerusalem lies about 30 kilometers to the west.

    Several large rivers are prominent. Flowing southeastward through Iraq are the Tigris and Euphrates. The dark area between the two rivers, northwest of the Persian Gulf, is a very fertile region where fishing and farming are prevalent. Wending its way through eastern Egypt is the Nile. In the south is Lake Nasser and the Aswan Dam; continuing northward the Nile passes the Temple of Luxor as it sharply loops to the east. It then turns west and northward, eventually passing the capital city of Cairo, and finally spreading into a prominent delta as it empties into the Mediterranean Sea. The bright dot just west of the apex of the delta marks the location of the great Pyramids and Sphinx complexes on the Giza Plateau. On the coast, west of the delta, is the ancient city of Alexandria, Egypt's main seaport.

    'MISR', as it turns out, is the transliteration of the Arabic name for Egypt.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

  20. SURFACE WATER AND GROUND WATER QUALITY MONITORING FOR RESTORATION OF URBAN LAKES IN GREATER HYDERABAD, INDIA

    NASA Astrophysics Data System (ADS)

    Mohanty, A. K.

    2009-12-01

    SURFACE WATER AND GROUND WATER QUALITY MONITORING FOR RESTORATION OF URBAN LAKES IN GREATER HYDERABAD, INDIA A.K. Mohanty, K. Mahesh Kumar, B. A. Prakash and V.V.S. Gurunadha Rao Ecology and Environment Group National Geophysical Research Institute, (CSIR) Hyderabad - 500 606, India E-mail:atulyakumarmohanty@yahoo.com Abstract: Hyderabad Metropolitan Development Authority has taken up restoration of urban lakes around Hyderabad city under Green Hyderabad Environment Program. Restoration of Mir Alam Tank, Durgamcheruvu, Patel cheruvu, Pedda Cheruvu and Nallacheruvu lakes have been taken up under the second phase. There are of six lakes viz., RKPuramcheruvu, Nadimicheruvu (Safilguda), Bandacheruvu Patelcheruvu, Peddacheruvu, Nallacheruvu, in North East Musi Basin covering 38 sq km. Bimonthly monitoring of lake water quality for BOD, COD, Total Nitrogen, Total phosphorous has been carried out for two hydrological cycles during October 2002- October 2004 in all the five lakes at inlet channels and outlets. The sediments in the lake have been also assessed for nutrient status. The nutrient parameters have been used to assess eutrophic condition through computation of Trophic Status Index, which has indicated that all the above lakes under study are under hyper-eutrophic condition. The hydrogeological, geophysical, water quality and groundwater data base collected in two watersheds covering 4 lakes has been used to construct groundwater flow and mass transport models. The interaction of lake-water with groundwater has been computed for assessing the lake water budget combining with inflow and outflow measurements on streams entering and leaving the lakes. Individual lake water budget has been used for design of appropriate capacity of Sewage Treatment Plants (STPs) on the inlet channels of the lakes for maintaining Full Tank Level (FTL) in each lake. STPs are designed for tertiary treatment i.e. removal of nutrient load viz., Phosphates and Nitrates. Phosphates are removed through addition of Alum to the influent stream to the STPs whereas Nitrates reduction is achieved by sending the treated wastewater from the STP through a wetland before entering the lake. STP Capacity ranging from 2-10 MLD have been recommended depending on lake water budget of individual lake and considering surrounding urbanization. Sediment nutrient data has helped for deciding the need for dredging of lake bed for removal of phosphates. Key Words: Lake water budget, Eutrophication, Trophic Status Index, Urban Lakes Restoration

  1. Interpreting Lake Data -Indiana Clean Lakes Program Indiana Clean Lakes Program

    E-print Network

    Serianni, Anthony S.

    information and education 2. Technical assistance 3. Volunteer lake monitoring 4. Lake water quality water quality assessment results for 1999-2003. Lake Water Quality Assessment The goals of the lake water quality assessment component include: (a) identifying water quality trends in individual lakes, (b

  2. Magnetic properties of Lake Qinghai Sediment

    NASA Astrophysics Data System (ADS)

    Ai, L.; Song, Y.; Sun, Y.; Qiang, X.; Deng, C.

    2008-12-01

    Lake Qinghai, the largest lake in China, locates at an elevation of 3196 m, covers an area of 4400 km2, with an average depth of 21 m and a drainage area of about 29,660 km2. It sits near the northeastern margin of the Tibetan Plateau and is positioned on the conjunction region where East Asian winter and summer monsoon, Indian Monsoon, and Westerlies interact. Lake Qinghai Drilling Project (LQDP) initiated by Institute of Earth Environment, Chinese Academy of Sciences had extracted a series of shallow cores from Lake Qinghai basin in the summer of 2005. Upper 6m of Core 1F (36°48'40.7"N, 110°08'13.5"E) contains a relatively uniformed greenish gray silty clay sediment with several darker layers and with a grayish brown section at 4.2-5m, preliminary chronology work (Zhou et al.,2008) indicate the upper 6m sediment spans to about 14ka. Some typical samples are selected for magnetic properties tests (K-T, J-T and Hysteresis loops), environmental magnetism parameters (magnetic susceptibility, ARM, SIRM, S-rations) are measured at 1cm intervals of core 1F. Rock magnetism tests identified that hematite and magnetite are dominant magnetic minerals below 5m, which may imply a detrital origin of magnetic properties related to terrestrial, especially eolian sources. In contrast paramagnetic iron sulfides e.g pyrites, normally formed in reduced condition are common in upper 5m. Magnetic susceptibility value varies between 4-8 10-8m3/kg below 5m, while that of the upper 5m are even lower (about 1-4 10-8m3/kg). Such magnetic susceptibility value change is attributed to changes of magnetic minerals and sedimentary conditions, such as oxidation-reduction alternation and carbonate dilution in the lake. Comparison with grain size and other climate proxies show that Lake Qinghai was generally in a drier environment before Holocene and became a deeper lake since Holocene. Key words: Lake Qinghai, magnetic minerals and magnetic susceptibility

  3. Middle East Composite

    Atmospheric Science Data Center

    2013-04-16

    ... large rivers are prominent. Flowing southeastward through Iraq are the Tigris and Euphrates. The dark area between the two rivers, ... Egypt is the Nile. In the south is Lake Nasser and the Aswan Dam; continuing northward the Nile passes the Temple of Luxor as it sharply ...

  4. GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY

    E-print Network

    GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY ANNUAL REPORT FY 1981 December 1981 Eugene J . Aubert and Development Environmental Research Laboratories Great Lakes Environmental Research Laboratory 2300 Washtenaw Research Laboratories publication. #12;PREFACE The Great Lakes Environmental Research Laboratory (GLERL

  5. United States East Coast

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Snowy to the north and west and cloudy to the east, this MODIS image from February 28, 2002, shows the eastern U.S. Piedmont, a region of relatively low-lying, rolling plateau that runs between New Jersey to the north and Alabama to the south. Bounded on the west by the Appalachians and on the east by the Atlantic Coastal Plain, the Piedmont is fertile agricultural land, and appears to be greening up in (from bottom left) Georgia, South Carolina, and parts of North Carolina, while winter has left its snowy mark on West Virginia (left of center), and to the northeast in Pennsylvania, New York, and New England.

  6. Late Cenozoic Moisture History of East Africa

    NASA Astrophysics Data System (ADS)

    Trauth, Martin H.; Maslin, Mark A.; Deino, Alan; Strecker, Manfred R.

    2005-09-01

    Lake sediments in 10 Ethiopian, Kenyan, and Tanzanian rift basins suggest that there were three humid periods at 2.7 to 2.5 million years ago (Ma), 1.9 to 1.7 Ma, and 1.1 to 0.9 Ma, superimposed on the longer-term aridification of East Africa. These humid periods correlate with increased aridity in northwest and northeast Africa and with substantial global climate transitions. These episodes could have had important impacts on the speciation and dispersal of mammals and hominins, because a number of key events, such as the origin of the genus Homo and the evolution of the species Homo erectus, took place in this region during that time.

  7. 11. OBLIQUE VIEW OF EAST TRUSS AND EAST SIDE OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. OBLIQUE VIEW OF EAST TRUSS AND EAST SIDE OF SOUTH ABUTMENT, SEEN FROM SOUTH BANK OF WINTER'S RUN. - Mitchell's Mill Bridge, Spanning Winter's Run on Carrs Mill Road, west of Bel Air, Bel Air, Harford County, MD

  8. INTERIOR VIEW OF EAST SIDE WALL AND DOOR, FACING EAST. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW OF EAST SIDE WALL AND DOOR, FACING EAST. - Douglas Aircraft Company Long Beach Plant, Aircraft Wing & Fuselage Assembly Building, 3855 Lakewood Boulevard, Long Beach, Los Angeles County, CA

  9. 3. East side, details of north half of east web; ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. East side, details of north half of east web; also details of roadway, railing and overhead bracing; looking northeast - Dodd Ford Bridge, County Road 147 Spanning Blue Earth River, Amboy, Blue Earth County, MN

  10. 89. East Haven Tunnel. East Haven, New Haven Co., CT. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    89. East Haven Tunnel. East Haven, New Haven Co., CT. Sec. 4209, MP 77.00. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  11. 90. East Haven Tunnel Shaft. East Haven, New Haven Co., ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    90. East Haven Tunnel Shaft. East Haven, New Haven Co., CT. Sec. 4209, MP 77.00 - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  12. Perspective view looking from the east to the east northeast ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Perspective view looking from the east to the east northeast facade, with Swiss Chalet in background, to replicate the view shown in MD-1109-J-18 - National Park Seminary, Japanese Pagoda, 2805 Linden Lane, Silver Spring, Montgomery County, MD

  13. 35. EAST FRONT OF POWERHOUSE AND CAR BARN: East front ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. EAST FRONT OF POWERHOUSE AND CAR BARN: East front of powerhouse and car barn. 'Annex' is right end of building. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco, San Francisco County, CA

  14. 10. BUILDING: SECOND FLOOR (East Section), VIEW SOUTH: EAST, SOUTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. BUILDING: SECOND FLOOR (East Section), VIEW SOUTH: EAST, SOUTH AND WEST WALLS OF COLD STORAGE, ALSO SHOWING REMNANTS OF COOLING PIPES - Boston Beer Company, 225-249 West Second Street, South Boston, Suffolk County, MA

  15. 29. SECOND FLOOR EAST SIDE APARTMENT EAST BEDROOM INTERIOR. ALUMINUMFRAME ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. SECOND FLOOR EAST SIDE APARTMENT EAST BEDROOM INTERIOR. ALUMINUM-FRAME SLIDING-GLASS WINDOWS ARE REPLACEMENTS. VIEW TO NORTHEAST. - Lee Vining Creek Hydroelectric System, Triplex Cottage, Lee Vining Creek, Lee Vining, Mono County, CA

  16. 3. EAST EXTERIOR CORNER SHOWING CATWALK. OPEN DOOR ON EAST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. EAST EXTERIOR CORNER SHOWING CATWALK. OPEN DOOR ON EAST SIDE OF THE HOUSE ENTERS INTO UTILITY ROOM. VIEW TO SOUTHWEST. - Big Creek Hydroelectric System, Powerhouse 8, Operator Cottage, Big Creek, Big Creek, Fresno County, CA

  17. Great Lakes Literacy Principles

    NASA Astrophysics Data System (ADS)

    Fortner, Rosanne W.; Manzo, Lyndsey

    2011-03-01

    Lakes Superior, Huron, Michigan, Ontario, and Erie together form North America's Great Lakes, a region that contains 20% of the world's fresh surface water and is home to roughly one quarter of the U.S. population (Figure 1). Supporting a $4 billion sport fishing industry, plus $16 billion annually in boating, 1.5 million U.S. jobs, and $62 billion in annual wages directly, the Great Lakes form the backbone of a regional economy that is vital to the United States as a whole (see http://www.miseagrant.umich.edu/downloads/economy/11-708-Great-Lakes-Jobs.pdf). Yet the grandeur and importance of this freshwater resource are little understood, not only by people in the rest of the country but also by many in the region itself. To help address this lack of knowledge, the Centers for Ocean Sciences Education Excellence (COSEE) Great Lakes, supported by the U.S. National Science Foundation and the National Oceanic and Atmospheric Administration, developed literacy principles for the Great Lakes to serve as a guide for education of students and the public. These “Great Lakes Literacy Principles” represent an understanding of the Great Lakes' influences on society and society's influences on the Great Lakes.

  18. A seismic survey of Pine Lake environmental center

    SciTech Connect

    Knezevic, J.J. . Dept. of Geology); Meltzer, A.S. . Dept. of Earth and Environmental Sciences)

    1993-03-01

    Pine Lake sits within a 900+ acre property owned by Hartwick College in West Davenport, NY. The property is an environmental center where biological and geochemical research is ongoing. Pine Lake itself is a 12 acre kettle hole lake created during the Woodfordian stage of the Wisconsonian glaciation. Bedrock is not exposed locally, but is buried beneath till. Preliminary geochemical analyses of the lake water suggest that the lake has a significant capacity to buffer the detrimental effects of acid precipitation (Adams, 1992). Water percolating through the glacial till on which the lake is situated is thought to play a major part in the introduction of buffering agents. The authors collected four refraction profiles adjacent to the lake to determine depth to bedrock and extent of glacial till. This will provide constraints for hydrologic models. Data was collected from two pairs of refraction lines. Two lines were placed on the north side of the lake and two on the east side. On each side of the lake, lines were oriented perpendicular to each other to constrain the dip of underlying bedrock. Data represent high resolution reversed refraction profiles and will allow the authors to constrain thickness of till and underlying bedrock geometry. Data was downloaded to a workstation, bandpass filtered from 5--280 Hz., scaled using a single window gain, and statically corrected. They see refracted arrivals from two interfaces. The upper interface is located at approximately 13 feet with a velocity of roughly 5,000 ft/sec and the lower interface at approximately 88 feet with a velocity of 12,000 ft/sec. These interfaces are essentially flat-lying and are most likely part of the Upper Devonian Unadilla Formation. The glacial till that blankets the area ranges in thickness from 13 feet to 71 feet.

  19. Allogenic sedimentary components of Bear Lake, Utah and Idaho

    USGS Publications Warehouse

    Rosenbaum, J.G.; Dean, W.E.; Reynolds, R.L.; Reheis, M.C.

    2009-01-01

    Bear Lake is a long-lived lake filling a tectonic depression between the Bear River Range to the west and the Bear River Plateau to the east, and straddling the border between Utah and Idaho. Mineralogy, elemental geochemistry, and magnetic properties provide information about variations in provenance of allogenic lithic material in last-glacial-age, quartz-rich sediment in Bear Lake. Grain-size data from the siliciclastic fraction of late-glacial to Holocene carbonate-rich sediments provide information about variations in lake level. For the quartz-rich lower unit, which was deposited while the Bear River fl owed into and out of the lake, four source areas are recognized on the basis of modern fluvial samples with contrasting properties that reflect differences in bedrock geology and in magnetite content from dust. One of these areas is underlain by hematite-rich Uinta Mountain Group rocks in the headwaters of the Bear River. Although Uinta Mountain Group rocks make up a small fraction of the catchment, hematite-rich material from this area is an important component of the lower unit. This material is interpreted to be glacial fl our. Variations in the input of glacial flour are interpreted as having caused quasi-cyclical variations in mineralogical and elemental concentrations, and in magnetic properties within the lower unit. The carbonate-rich younger unit was deposited under conditions similar to those of the modern lake, with the Bear River largely bypassing the lake. For two cores taken in more than 30 m of water, median grain sizes in this unit range from ???6 ??m to more than 30 ??m, with the coarsest grain sizes associated with beach or shallow-water deposits. Similar grain-size variations are observed as a function of water depth in the modern lake and provide the basis for interpreting the core grain-size data in terms of lake level. Copyright ?? 2009 The Geological Society of America.

  20. 13. View of south side of East Ward Street east ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. View of south side of East Ward Street east of Sibett Avenue, facing southwest. - Gaskin Avenue Neighborhood, Bounded by Dart Street to east, CSX Railroad to south, Pearl & Madison Avenues to west, & Wilson & Gordon Streets to north, Douglas, Coffee County, GA

  1. 2. View of north side of East Ward Street east ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. View of north side of East Ward Street east of North Coweta Avenue, facing northeast. - Gaskin Avenue Neighborhood, Bounded by Dart Street to east, CSX Railroad to south, Pearl & Madison Avenues to west, & Wilson & Gordon Streets to north, Douglas, Coffee County, GA

  2. 7. View of south side of East Ward Street east ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. View of south side of East Ward Street east of South Coweta Avenue, facing southwest. - Gaskin Avenue Neighborhood, Bounded by Dart Street to east, CSX Railroad to south, Pearl & Madison Avenues to west, & Wilson & Gordon Streets to north, Douglas, Coffee County, GA

  3. 17. View of north side of East Ward Street east ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. View of north side of East Ward Street east of North McDonald Avenue, facing northwest. - Gaskin Avenue Neighborhood, Bounded by Dart Street to east, CSX Railroad to south, Pearl & Madison Avenues to west, & Wilson & Gordon Streets to north, Douglas, Coffee County, GA

  4. 20. View of south side of East Ward Street east ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. View of south side of East Ward Street east of South McDonald Avenue, facing southeast. - Gaskin Avenue Neighborhood, Bounded by Dart Street to east, CSX Railroad to south, Pearl & Madison Avenues to west, & Wilson & Gordon Streets to north, Douglas, Coffee County, GA

  5. 4. Engine room, east end looking east toward engine #4 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. Engine room, east end looking east toward engine #4 (Enterprise Diesel; reduction gear in foreground; in left rear, two D.C. generators with Ames Ironworks horizontal engine and sturtevant vertical engine - East Boston Pumping Station, Chelsea Street at Chelsea Creek, Boston, Suffolk County, MA

  6. 10. VIEW OF BRIDGE, LOOKING EAST. THE EAST TOWER IS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. VIEW OF BRIDGE, LOOKING EAST. THE EAST TOWER IS SEEN AT THE CENTER OF THE PHOTOGRAPH ON THE SKYLINE, AND THE EAST WALKWAY ABUTMENT IS SEEN AT THE LEFT OF THE VIEW. THE VERTICAL CABLE RUNS FROM THE EYEBOLT TO THE MAIN SUSPENSION CABLE SPACER. February 1987 - Verde River Sheep Bridge, Spanning Verde River (Tonto National Forest), Cave Creek, Maricopa County, AZ

  7. Anaglyph, Salt Lake City, Utah

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The 2002 Winter Olympics are hosted by Salt Lake City at several venues within the city, in nearby cities, and within the adjacent Wasatch Mountains. This anaglyph image provides a stereoscopic map view of north central Utah that includes all of these Olympic sites. In the south, next to Utah Lake, Provo hosts the ice hockey competition. In the north, northeast of the Great Salt Lake, Ogden hosts curling and the nearby Snowbasin ski area hosts the downhill events. In between, southeast of the Great Salt Lake, Salt Lake City hosts the Olympic Village and the various skating events. Further east, across the Wasatch Mountains, the Park City ski resort hosts the bobsled, ski jumping, and snowboarding events. The Winter Olympics are always hosted in mountainous terrain. This view shows the dramatic landscape that makes the Salt Lake City region a world-class center for winter sports.

    The stereoscopic effect of this anaglyph was created by first draping a Landsat satellite image over a Shuttle Radar Topography Mission digital elevation model and then generating two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter.

    Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data matches the 30-meter (98-foot) resolution of most Landsat images and will substantially help in analyzing the large and growing Landsat image archive, managed by the U.S. Geological Survey (USGS).

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect 3-D measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter(approximately 200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between NASA, the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C.

    Size: 222 x 93.8 kilometers (138 x 58.2 miles) Location: 40.0 to 42.0 deg. North lat., 111.25 to 112.25.0 deg. West lon.(exactly) Orientation: North at top Image Data: Landsat Bands 3, 2, 1 as panchromatic grey. Original Data Resolution: SRTM 1 arcsecond (30 meters or 98 feet), Thematic Mapper 30 meters (98 feet) Date Acquired: February 2000 (SRTM), 1990s (Landsat 5 image mosaic)

  8. Lake level changes in Hala Lake(NW China) based on ostracodassemblages during the LGM and Post-LGM

    NASA Astrophysics Data System (ADS)

    Yan, D.; Wuennemann, B.

    2012-12-01

    The Hala Lake, located in the Qilian Mountains, Qinghai Province, China, at 4078 m a.s.l. may archive in its sediments hydrological and climate changes during the Late Quaternary time, as it is close to the area impacted by the East-Asian Summer monsoon and westerly-driven air masses. Based on the sediment core H7, which was taken in the center of the lake at 65m water depth,ostracod assemblages and stable isotopes from ostracode shells were investigated in details. Three main species were found, which are common species in high altitude saline lakes of the Tibetan Plateau: Leucocythere sp.,Limnocythereinopinata and Eucypris sp.They started to occur in deeper part of H7,indicating an early onset of favorable living conditions during the LGM and post-LGM periods. Besides, algae occurred between 25 and 32m water depth. According to the unevenly distributed amount of ostracods and oxygen isotope data, our results indicate important lake level changes during the global LGM and Lateglacial. The lake experienced lowest levels of 25-50 m below the present water line. Ostracods disappeared with the onset of the early Holocene.A stepwise refilling started already at ca. 16 kyr BP and reached -25 m level during the Bølling/Allerød warm phase at ca. 13.5 kyr BP.Latest at ca.7.6 kyr BP, the lake reached a stable highstand similar to the present level until ca.6 kyr BPas . The subsequent lake development remains unclear due to strong mismatches of the data but may indicate a general trend to deteriorating conditions and lake level lowstands at ca. 5.0-4.2, 2.0 and at around 0.5 kyr BP.; Ostracods Distribution in H2 ; Ostracods plate in Hala lake

  9. Middle East Respiratory Syndrome (MERS)

    MedlinePLUS

    ... Search The CDC Cancel Submit Search The CDC Middle East Respiratory Syndrome (MERS) Note: Javascript is disabled or ... CDC.gov . Recommend on Facebook Tweet Share Compartir Middle East Respiratory Syndrome (MERS) is a viral respiratory illness ...

  10. Reduced interannual rainfall variability in East Africa during the last ice age.

    PubMed

    Wolff, Christian; Haug, Gerald H; Timmermann, Axel; Sinninghe Damsté, Jaap S; Brauer, Achim; Sigman, Daniel M; Cane, Mark A; Verschuren, Dirk

    2011-08-01

    Interannual rainfall variations in equatorial East Africa are tightly linked to the El Niño Southern Oscillation (ENSO), with more rain and flooding during El Niño and droughts in La Niña years, both having severe impacts on human habitation and food security. Here we report evidence from an annually laminated lake sediment record from southeastern Kenya for interannual to centennial-scale changes in ENSO-related rainfall variability during the last three millennia and for reductions in both the mean rate and the variability of rainfall in East Africa during the Last Glacial period. Climate model simulations support forward extrapolation from these lake sediment data that future warming will intensify the interannual variability of East Africa's rainfall. PMID:21817050

  11. Understanding the Middle East.

    ERIC Educational Resources Information Center

    Owen, Evelyn C.

    This nine-week unit on the Middle East for sixth graders was developed as part of a series by the Public Education Religion Studies Center at Wright State University. A major objective is to help students understand and appreciate sacred times and sacred places within this cultural setting. They learn how beliefs and practices cause the people to…

  12. Test Well, East River

    USGS Multimedia Gallery

    USGS test well 10 34h363 in the East River, Brunswick, Ga. The U.S. Geological Survey drilled this test well in the early 1970's and at the time it was on the edge of the marsh at Andrews Island. It is now only accessible by boat or canoe at high tide. Despite being surrounded by saltwater the artes...

  13. East Texas Storytellers.

    ERIC Educational Resources Information Center

    Anderson, Brandi, Ed.

    1987-01-01

    Written and published by the students at Gary High School, Gary, Texas, "Loblolly Magazine" is published twice a year. Issues are frequently devoted to a distant theme. The theme of this issue, "East Texas Storytellers," attempts to capture some of the local color and regional history of eastern Texas. The first article, "Timothy Griffith, Master…

  14. East Alumni Ave. Horticulture

    E-print Network

    Vetter, Frederick J.

    Wolf Anatomy Laboratory 127 (A4) * Dining Services Distribution Center, purchasing 103 (A1) East Farm 41 (A6) * Fire Station 42 (B7) * Fogarty Health Science Building, pharmacy 43 (D5) Food Science (D6) Housing Maintenance 122 (B2) Housing Storage 123 (B2) ** Human Resource Administration 70 (C4

  15. Assessments East Carolina University

    E-print Network

    Gopalakrishnan, K.

    Approval Available Hours Follow-Ups Previous Audit plan Risk Assessment Process (Attch: 1) Self University How the Audit Plan is Developed #12;East Carolina University Risk Assessment Process Attch: 1 of Internal Audit Risk Assessment Preliminary Work Date: Name: Area of Responsibility: Prior to meeting

  16. Ober's Island, One of the Review Islands on Rainy Lake, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Ober's Island, One of the Review Islands on Rainy Lake, bounded on the south by The Hawk Island and on the north by The Crow Island. These islands are located seven miles east of Ranier, Minnesota, three miles west of Voyageur National Park, and one mile south of the international border of the United States of America and Canada. The legal description of Mallard Island is Lot 6, Section 19, T-17-N, R-22-W, Koochiching County, Minnesota, Ranier, Koochiching County, MN

  17. Winter and Summer Views of the Salt Lake Region

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Magnificent views of the region surrounding Salt Lake City, Utah are captured in these winter and summer images from the Multi-angle Imaging SpectroRadiometer's vertical-viewing (nadir) camera. Salt Lake City, situated near the southeastern shore of the Great Salt Lake, is host to the 2002 Winter Olympic Games, which open Friday, February 8. Venues for five of the scheduled events are at city (indoor) locations, and five in mountain (outdoor) facilities. All ten can be found within the area contained in these images. Some of the outdoor events take place at Ogden, situated north of Salt Lake City and at Park City, located to the east.

    Salt Lake City is surrounded by mountains including the Wasatch Range to the east, and the temperature difference between the Great Salt Lake and the overlying atmosphere enhances the moisture content of winter storms. These factors, in combination with natural cloud seeding by salt crystals from the lake, are believed to result in greater snowfall in neighboring areas compared to more distant locales.

    In addition to the obvious difference in snow cover between the winter and summer views, water color changes in parts of the Great Salt Lake are apparent in these images. The distinctly different coloration between the northern and southern arms of the Great Salt Lake is the result of a rock-filled causeway built in 1953 to support a permanent railroad. The causeway has resulted in decreased circulation between the two arms and higher salinity on the northern side. The southern part of the lake includes the large Antelope Island, and at full resolution a bridge connecting it to the mainland can be discerned.

    These images are natural color views acquired on February 8, 2001 and June 16, 2001, during Terra orbits 6093 and 7957, respectively. Each image represents an area of about 220 kilometers x 285 kilometers.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

  18. Lake Enriquillo Water Level History and Implications for future flooding in the Southwestern Dominican Republic

    NASA Astrophysics Data System (ADS)

    Wright, V. D.; Hornbach, M. J.; McHugh, C. M.; Asilis, Y.; Montes, M.

    2013-12-01

    Lake Enriquillo is currently located -41m below sea-level, and is the largest lake (~350 km2) in the Caribbean. Lake levels during the past eight years have risen to anomalous highs (from -51m BSL to -41m BSL), flooding villages and displacing their inhabitants. Both the cause of lake level rise and the anticipated future change in lake level remain unclear. Seismic images revealing erosional and depositional sedimentary boundaries in the lake, however, provide insight into historic lake level trends. Here, we integrate seismic images with sediment core samples, and historical photographs to constrain lake level history with time. We used ASTER global digital elevation models combined with single beam data to determine the lake's bathymetry, drainage and surrounding geomorphology. Additionally, we used NOAA and local weather station data to assess the potential role that weather and climate patterns play in lake levels. Although yearly weather conditions play a major role in lake levels, analysis of regional seismic data indicates that tectonics may also play an important role in longer term (century-scale) lake levels. The lake's areal extent and lake level elevation depend not only on the water supply, but also the lake's bathymetry and regional topography that is defined by the Enriquillo-Plantain Garden Fault--a strike-slip fault system that extends throughout the lake. The shallow bathymetry of much of the lake (~ 20%) implies that relatively small changes in the rain pattern cause significant (10 m) changes to lake depth. Over the past thirty years, variations in the lake's areal extent (between 160 km2 to 350km2) and elevation (between -52m BSL to -41m BSL) can be attributed to changes in weather patterns. Preliminary analysis of both core and seismic data confirm that the lake water levels generally mimic wet and dry periods in the region, consistent with recent observations, however, the longer term maximum and minimum extent of Lake Enriquillo water levels, and how these lake levels correlate with paleoclimatic studies remains poorly constrained. Since the lake is quite shallow (<2 m) over a large regional area (~20 %), only moderate (Mw. 7) earthquakes are necessary to change the lake bathymetry profile. Seismic images indicate that the Enriquillo-Plantain Garden fault (EPGF) system actively extends from east to west across the center of the lake. This fault system activates every few hundred years. Preliminary analysis of shallow lake bathymetry near the fault indicates that only slight changes in lake bathymetry via a moderate (Mw 7.0) earthquake along the EPGF may cause potentially significant changes to lake shape and regional bathymetry. Continuing analysis of seismic and coring data, additional up-coming research cruises on the lake next winter, and anticipated age-dates from sediment cores will provide additional insight into the link between lake level variability, climate, and regional tectonics with time.

  19. Lessons from a Lake.

    ERIC Educational Resources Information Center

    Goethals, Susan

    1997-01-01

    Describes a study that included classroom lessons on hydroelectric power, the history and construction of a nearby lake, data recording, the use of field guides, and methods of counting natural populations. The study culminated in a field trip to the lake. (JRH)

  20. The lakes of Titan

    USGS Publications Warehouse

    Stofan, E.R.; Elachi, C.; Lunine, J.I.; Lorenz, R.D.; Stiles, B.; Mitchell, K.L.; Ostro, S.; Soderblom, L.; Wood, C.; Zebker, H.; Wall, S.; Janssen, M.; Kirk, R.; Lopes, R.; Paganelli, F.; Radebaugh, J.; Wye, L.; Anderson, Y.; Allison, M.; Boehmer, R.; Callahan, P.; Encrenaz, P.; Flamini, E.; Francescetti, G.; Gim, Y.; Hamilton, G.; Hensley, S.; Johnson, W.T.K.; Kelleher, K.; Muhleman, D.; Paillou, P.; Picardi, G.; Posa, F.; Roth, L.; Seu, R.; Shaffer, S.; Vetrella, S.; West, R.

    2007-01-01

    The surface of Saturn's haze-shrouded moon Titan has long been proposed to have oceans or lakes, on the basis of the stability of liquid methane at the surface. Initial visible and radar imaging failed to find any evidence of an ocean, although abundant evidence was found that flowing liquids have existed on the surface. Here we provide definitive evidence for the presence of lakes on the surface of Titan, obtained during the Cassini Radar flyby of Titan on 22 July 2006 (T16). The radar imaging polewards of 70?? north shows more than 75 circular to irregular radar-dark patches, in a region where liquid methane and ethane are expected to be abundant and stable on the surface. The radar-dark patches are interpreted as lakes on the basis of their very low radar reflectivity and morphological similarities to lakes, including associated channels and location in topographic depressions. Some of the lakes do not completely fill the depressions in which they lie, and apparently dry depressions are present. We interpret this to indicate that lakes are present in a number of states, including partly dry and liquid-filled. These northern-hemisphere lakes constitute the strongest evidence yet that a condensable-liquid hydrological cycle is active in Titan's surface and atmosphere, in which the lakes are filled through rainfall and/or intersection with the subsurface 'liquid methane' table. ??2007 Nature Publishing Group.

  1. Lake Darling Comparison

    USGS Multimedia Gallery

    The photo on the left was taken on April 18, 1997 by a USGS Personnel, of the new gates at Lake Darling. The photo to the right was taken on June 13, 2011 by Nathan A. Stroh (USGS), of Lake Darling....

  2. Exploding Lakes in Cameroon

    USGS Multimedia Gallery

    In 1986, Lake Nyos, in the volcanic region of Cameroon, released a cloud of CO2 into the atmosphere, killing 1,700 people and 3,500 livestock in nearby towns and villages. Since then, engineers have been artificially removing the gas from the lake through piping. The gas burst in 1986 from the 200-m...

  3. Exploding Lakes in Cameroon

    USGS Multimedia Gallery

    In 1986, Lake Nyos, in the volcanic region of Cameroon, released a cloud of CO2 into the atmosphere, killing 1,700 people and 3,500 livestock in nearby towns and villages. Since then, engineers have been artificially removing the gas from the lake through piping. This photo shows a pipe top and raft...

  4. Great Lakes RESTORATION

    E-print Network

    precise simulations of possible climate change scenarios. - Educating Great Lakes decision Lakes Restoration Initiative (GLRI) has helped NOAA become a leader in climate change research, outreach decisions made as a result. - Monitoring and modeling climate variables to project future climate trends

  5. Great Lakes Beach Health

    USGS Multimedia Gallery

    As schools close for the year and summer weather beckons, many recreationalists head to the Great Lakes' public beaches. However, these coastal areas can become contaminated with disease-causing bacteria that threaten public health, disrupt water recreation, and pay a toll on the Great Lakes economi...

  6. Lake Wobegon Dice

    ERIC Educational Resources Information Center

    Moraleda, Jorge; Stork, David G.

    2012-01-01

    We introduce Lake Wobegon dice, where each die is "better than the set average." Specifically, these dice have the paradoxical property that on every roll, each die is more likely to roll greater than the set average on the roll, than less than this set average. We also show how to construct minimal optimal Lake Wobegon sets for all "n" [greater…

  7. Lake Effect Clouds

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The lake effect is particularly clear in this Sea-viewing Wide field-of-view Sensor (SeaWiFS) true-color image of the North American Great Lakes region, acquired December 5, 2000. Lakes Nipigon, Superior, and Michigan show striking contrasts between clear and cloudy air as the wind blows from the northwest across the lakes. As it flows across the relatively warm lakes, the cold dry air gathers heat and moisture from the surface. The warm moist air rises into the atmosphere and mixes vigorously with the cold dry air above. The layer of warm moist air deepens as it travels across the lake. Some of the evaporated water from the lake condenses into streamers of fog rising from the surface, while much of the moisture condenses to form a stratocumulus cloud in the upper half of the mixed layer. The cloud-forming water droplets may freeze into ice crystals and, due to accumulated water deposition over time, grow into snowflakes. This process can generate snowstorms that produce significant amounts of snowfall downwind. It is not uncommon for lake effect snowstorms to produce as much as two feet of snow within a 24-hour period in northwestern parts of New York and Pennsylvania. Image provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  8. The Great Lakes.

    ERIC Educational Resources Information Center

    Seasons, 1987

    1987-01-01

    The Great Lakes are one of the world's greatest reserviors of fresh water, the foundation of Ontario's economic development, a primary force in ecological systems, and a base for pleasure and recreation. These lakes and their relationship with people of Canada and the United States can be useful as a subject for teaching the impact of human…

  9. Great Lakes Teacher's Guide.

    ERIC Educational Resources Information Center

    Reid, Ron

    The Great Lakes are one of the world's greatest reservoirs of fresh water, the foundation of Ontario's economic development, a primary force in ecological systems, and a base for pleasure and recreation. They are also a magnificent resource for the teachers of Ontario. Study of the Great Lakes can bring to life the factors that shape the ecology…

  10. Great Lakes: Great Gardening.

    ERIC Educational Resources Information Center

    New York Sea Grant Inst., Albany, NY.

    This folder contains 12 fact sheets designed to improve the quality of gardens near the Great Lakes. The titles are: (1) "Your Garden and the Great Lakes"; (2) "Organic Gardening"; (3) "Fruit and Vegetable Gardening"; (4) "Composting Yard Wastes"; (5) "Herbicides and Water Quality"; (6) "Watering"; (7) "Soil Erosion by Water"; (8) "Soil…

  11. The lakes of Titan

    NASA Astrophysics Data System (ADS)

    Stofan, E. R.; Elachi, C.; Lunine, J. I.; Lorenz, R. D.; Stiles, B.; Mitchell, K. L.; Ostro, S.; Soderblom, L.; Wood, C.; Zebker, H.; Wall, S.; Janssen, M.; Kirk, R.; Lopes, R.; Paganelli, F.; Radebaugh, J.; Wye, L.; Anderson, Y.; Allison, M.; Boehmer, R.; Callahan, P.; Encrenaz, P.; Flamini, E.; Francescetti, G.; Gim, Y.; Hamilton, G.; Hensley, S.; Johnson, W. T. K.; Kelleher, K.; Muhleman, D.; Paillou, P.; Picardi, G.; Posa, F.; Roth, L.; Seu, R.; Shaffer, S.; Vetrella, S.; West, R.

    2007-01-01

    The surface of Saturn's haze-shrouded moon Titan has long been proposed to have oceans or lakes, on the basis of the stability of liquid methane at the surface. Initial visible and radar imaging failed to find any evidence of an ocean, although abundant evidence was found that flowing liquids have existed on the surface. Here we provide definitive evidence for the presence of lakes on the surface of Titan, obtained during the Cassini Radar flyby of Titan on 22 July 2006 (T16). The radar imaging polewards of 70° north shows more than 75 circular to irregular radar-dark patches, in a region where liquid methane and ethane are expected to be abundant and stable on the surface. The radar-dark patches are interpreted as lakes on the basis of their very low radar reflectivity and morphological similarities to lakes, including associated channels and location in topographic depressions. Some of the lakes do not completely fill the depressions in which they lie, and apparently dry depressions are present. We interpret this to indicate that lakes are present in a number of states, including partly dry and liquid-filled. These northern-hemisphere lakes constitute the strongest evidence yet that a condensable-liquid hydrological cycle is active in Titan's surface and atmosphere, in which the lakes are filled through rainfall and/or intersection with the subsurface `liquid methane' table.

  12. The late holocene palaeoenvironment in the Lake Njupi area, west Cameroon: implications regarding the history of Lake Nyos

    NASA Astrophysics Data System (ADS)

    Zogning, Appolinaire; Giresse, Pierre; Maley, Jean; Gadel, François

    1997-04-01

    Lake Njupi, 1 km east of Lake Nyos, on the Cameroon Volcanic Line, was formed by the damming of a local crustal depression. Two cores from Lake Nyos were analysed which penetrated sediments at the margin of the lake. The older deposits give an age of 3400 years BP and this date is proposed as a minimum age for Lake Njupi. Sedimentological, palynological and geochemical studies of a 2 m section provide an opportunity to reconstruct the Late Holocene environmental history. It is an organic-rich deposit (organic carbon up to 30%) with an abundant Silicospongia spicules fraction. An obvious sedimentary homogeneity is interrupted by 5 fine to coarse layers with sandy quartz and lignitic remains. Such inputs were denoted by carbohydrate maxima or sometimes by phenolic compounds. This study confirms the evidence of an arid period culminating between 2500 and 2000 yrs BP. This crisis began around 3000 yrs BP in the rain forest area of West Cameroon and also further to the south in Congo. Lake Njupi, situated today in a mostly grassland savanna environment known as the "Grass Fields", provides evidence for environmental changes from a mosaic of forest and savanna before 2500 years BP to a savanna characterised by high grass pollen contents (75 to 85%), with small islands of forest. The mountain vegetation characterised by Podocarpus and Olea capensis retreated around 2300 years BP at the time Elaeis guineensis (the Oil Palm) began its extension as a pioneer tree, later providing opportunities for its domestication by man.

  13. Crater Lake Revealed: Using GIS to Visualize and Analyze Postcaldera Volcanoes Beneath Crater Lake, Oregon

    NASA Astrophysics Data System (ADS)

    Ramsey, D. W.; Robinson, J. E.; Dartnell, P.; Bacon, C. R.; Gardner, J. V.; Mayer, L. A.; Buktenica, M. W.

    2001-12-01

    Crater Lake, Oregon, partially fills the caldera that formed ~7,700 years ago by the eruption of 50 km3 of mainly rhyodacitic magma and collapse of Mount Mazama. Prior to the climactic event, Mount Mazama had a 400,000-year eruptive history, much of which was like those of other Cascade volcanic centers such as Mount Shasta. Since the climactic eruption, there have been several less violent, smaller eruptions within the caldera itself. Until a recent bathymetric survey, relatively little was known about the character and timing of these eruptions because their products are obscured beneath Crater Lake's surface. In the summer of 2000, the lake bottom was mapped with a high-resolution multibeam echo sounder (Gardner et. al., 2001), providing a 2m/pixel view of the lake floor from its deepest basins virtually to the shoreline. Using Geographic Information Systems (GIS) applications, the bathymetric data has been visualized and analyzed (aided by images and samples obtained with the manned submersible Deep Rover, sediment cores and dredged rocks, and detailed geologic mapping of Mount Mazama) to determine a geologic map of the lake bottom, a history of lake filling (Nathenson et. al., 2001), and volumes, times, and rates of postcaldera eruptions. These calculations have been used to assemble a geologic history for Crater Lake from the time of caldera formation to present day. Postcaldera eruptions have been both subareal and subaqueous, and were well underway within about 90 years after the climactic eruption, beginning with andesitic lava flows from the Wizard Island and central platform volcanoes. The eruptive history of the Wizard Island volcano is divided into three periods defined by former shorelines where subaerial flows entered the lake, quenched rapidly, and fractured, forming lobate deltas and breccia slopes. The shorelines are visible in slope and shaded-relief images of the lake floor created with GIS. The lake filling model suggests that these shorelines formed at ~90, 250, and 480 years after the lake began to fill. Combining volume calculations determined with GIS and age information from the lake filling model, oldest to youngest Wizard Island minimum eruption rates are 8.4x106 m3/yr, 6.5x106 m3/yr, and 3.6x106 m3/yr. These are comparable to rates calculated for the central platform volcano using the same approach. The minimum eruption rate for the entire 4 km3 of postcaldera andesite erupted from ~90 to 480 years after caldera formation is 8.4x106 m3/yr, which is comparable to historic rates of lava effusion at arc volcanoes. The cessation of postcaldera volcanic activity at Crater Lake, ~4,900 years ago, is marked by subaqueous extrusion of a 0.074 km3 rhyodacite dome on the east flank of Wizard Island.\\J.V. Gardner et. al., 2001, USGS Water Resources Investigations Report 01-4046; http://walrus.wr.usgs.gov/pacmaps\\M. Nathenson et. al., 2001, Models for the Filling of Crater Lake, Oregon (this meeting)

  14. Lake trout in northern Lake Huron spawn on submerged drumlins

    USGS Publications Warehouse

    Riley, Stephen; Binder, Thomas; Wattrus, Nigel J.; Faust, Matthew D.; Janssen, John; Menzies, John; Marsden, J. Ellen; Ebener, Mark P.; Bronte, Charles R.; He, Ji X.; Tucker, Taaja R.; Hansen, Michael J.; Thompson, Henry T.; Muir, Andrew M.; Krueger, Charles C.

    2014-01-01

    Recent observations of spawning lake trout Salvelinus namaycush near Drummond Island in northern Lake Huron indicate that lake trout use drumlins, landforms created in subglacial environments by the action of ice sheets, as a primary spawning habitat. From these observations, we generated a hypothesis that may in part explain locations chosen by lake trout for spawning. Most salmonines spawn in streams where they rely on streamflows to sort and clean sediments to create good spawning habitat. Flows sufficient to sort larger sediment sizes are generally lacking in lakes, but some glacial bedforms contain large pockets of sorted sediments that can provide the interstitial spaces necessary for lake trout egg incubation, particularly if these bedforms are situated such that lake currents can penetrate these sediments. We hypothesize that sediment inclusions from glacial scavenging and sediment sorting that occurred during the creation of bedforms such as drumlins, end moraines, and eskers create suitable conditions for lake trout egg incubation, particularly where these bedforms interact with lake currents to remove fine sediments. Further, these bedforms may provide high-quality lake trout spawning habitat at many locations in the Great Lakes and may be especially important along the southern edge of the range of the species. A better understanding of the role of glacially-derived bedforms in the creation of lake trout spawning habitat may help develop powerful predictors of lake trout spawning locations, provide insight into the evolution of unique spawning behaviors by lake trout, and aid in lake trout restoration in the Great Lakes.

  15. Association between winter precipitation and water level fluctuations in the Great Lakes and atmospheric circulation patterns

    SciTech Connect

    Rodionov, S.N.

    1994-11-01

    Atmospheric precipitation in the Great Lakes basin, as a major mediating variable between atmospheric circulation and lake levels, is analyzed relative to both. The effect of cumulative winter precipitation on lake levels varies from lake to lake and depends on both the state of the lake level itself and air temperature. For periods with a quasi-stable temperature regime, the correlation coefficient between winter precipitation and changes in lake levels from November to spring months reaches 0.8. An analysis of composite maps of mean winter 700-mb heights and sea level pressure for the years with well-above and well-below normal precipitation in the lower Great Lakes basin (Lakes Michigan-Huron, St. Clair, Erie, and Ontario) has shown that changes in precipitation are associated with the wave train structure in the lower and midtroposphere that is similar to the Pacific/North American (PNA) teleconnection pattern. During the positive phase of the PNA-like pattern, when the upper-atmospheric ridge/trough system is amplified, cyclones passing over the Great Lakes basin are frequently of Alberta (Canada) origin and carry relatively small amounts of precipitation. As a result, lake levels tend to decline. On the contrary, during the negative phase of the pattern when the atmospheric circulation is more zonal, the main storm track is oriented from the southwest to the northeast and cyclones bring enough precipitation to induce a rise in lake levels. The effect of the position of the upper-atmospheric trough over the east coast of North America on the precipitation regime in the Great Lakes basin is also demonstrated. 42 refs., 11 figs., 4 tabs.

  16. Phylogenies of Microcystin-Producing Cyanobacteria in the Lower Laurentian Great Lakes Suggest Extensive Genetic Connectivity

    PubMed Central

    Davis, Timothy W.; Watson, Susan B.; Rozmarynowycz, Mark J.; Ciborowski, Jan J. H.; McKay, Robert Michael; Bullerjahn, George S.

    2014-01-01

    Lake St. Clair is the smallest lake in the Laurentian Great Lakes system. MODIS satellite imagery suggests that high algal biomass events have occurred annually along the southern shore during late summer. In this study, we evaluated these events and tested the hypothesis that summer bloom material derived from Lake St. Clair may enter Lake Erie via the Detroit River and represent an overlooked source of potentially toxic Microcystis biomass to the western basin of Lake Erie. We conducted a seasonally and spatially resolved study carried out in the summer of 2013. Our goals were to: 1) track the development of the 2013 summer south-east shore bloom 2) conduct a spatial survey to characterize the extent of toxicity, taxonomic diversity of the total phytoplankton population and the phylogenetic diversity of potential MC-producing cyanobacteria (Microcystis, Planktothrix and Anabaena) during a high biomass event, and 3) compare the strains of potential MC-producers in Lake St. Clair with strains from Lake Erie and Lake Ontario. Our results demonstrated a clear predominance of cyanobacteria during a late August bloom event, primarily dominated by Microcystis, which we traced along the Lake St. Clair coastline downstream to the Detroit River's outflow at Lake Erie. Microcystin levels exceeded the Province of Ontario Drinking Water Quality Standard (1.5 µg L?1) for safe drinking water at most sites, reaching up to five times this level in some areas. Microcystis was the predominant microcystin producer, and all toxic Microcystis strains found in Lake St. Clair were genetically similar to toxic Microcystis strains found in lakes Erie and Ontario. These findings suggest extensive genetic connectivity among the three systems. PMID:25207941

  17. Evidence of offshore lake trout reproduction in Lake Huron

    USGS Publications Warehouse

    DeSorcie, Timothy J.; Bowen, Charles A., II

    2003-01-01

    Six Fathom Bank-Yankee Reef, an offshore reef complex, was an historically important spawning area believed to represent some of the best habitat for the rehabilitation of lake trout Salvelinus namaycush in Lake Huron. Since 1986, lake trout have been stocked on these offshore reefs to reestablish self-sustaining populations. We sampled with beam trawls to determine the abundance of naturally reproduced age-0 lake trout on these offshore reefs during May-July in 1994-1998 and 2000-2002. In total, 123 naturally reproduced lake trout fry were caught at Six Fathom Bank, and 2 naturally reproduced lake trout fry were caught at nearby Yankee Reef. Our findings suggest that this region of Lake Huron contains suitable habitat for lake trout spawning and offers hope that lake trout rehabilitation can be achieved in the main basin of Lake Huron.

  18. Aquatic insect community of lake, Phulbari anua in Cachar, Assam.

    PubMed

    Gupta, Susmita; Narzary, Rupali

    2013-05-01

    An investigation on the water quality and aquatic insect community of an oxbow lake (Phulbari anua) of south Assam, North-East India was carried out during February to April, 2010. Aquatic insect community of the oxbow lake was represented by 9 species belonging to 9 families and 4 orders during the study period. Order Ephemeroptera and Hemiptera were found to be dominant. Record of 5 species and 5 families from the order Hemiptera showed that this is the largest order in terms of aquatic insect diversity of the lake. Computation of dominance status of different species of aquatic insects of the lake based on Engelmann's Scale revealed that Anisops lundbladiana and Cloeon sp. were eudominant in the system. The Shannon- Weiner's Diversity Index (H') and Shannon evenness values (J') were found to range from 0.3-0.69 and 0.53 -0.97, respectively indicating perturbation of the system. Again in terms of physico-chemical properties of water the lake is in a satisfactory condition where all the parameters are well within the range of IS 10500. The DO values were found to range from 6.8 to 14.8 mgl(-1). Free CO2 fluctuated from 1 to 4.98 mgl(-1) and nitrate in water ranged from 0.4 to 2.1 mgl(-1). Margalef's water quality index values of most of the samplings also indicated clean water condition of the lake. Correlation coefficient analyses of the environmental variables, aquatic insect diversity and density of the lake revealed that aquatic insect diversity of the lake is mainly governed by dissolved oxygen, nitrate, and free carbon dioxide. PMID:24617147

  19. Thermokarst Lake Gyre Flow Speed and Direction Derivation Using Image Matching from Sequential Satellite Images

    NASA Astrophysics Data System (ADS)

    Zhan, S.; Wang, S.; Beck, R. A.; Liu, H.; Hinkel, K. M.

    2014-12-01

    Thermokarst lakes on the Arctic Coastal Plain of northern Alaska are closely coupled with the regional climate through energy, water and carbon budgets. These lakes exhibit striking elongated shapes perpendicular to the prevailing wind direction. This has led to the hypothesis that the expansion of lakes is caused by thermomechanical processes induced by wind-driven water circulation. The predominant bimodal wind regime in the region (easterly and westerly wind) redistributes lake sediment towards the west and east shores to form protective littoral shelves while the north and south shores are preferentially eroded. Previous research on wind-driven circulation in thermokarst lakes was mainly based on in situ studies which can only collect sparse measurements and is time-consuming. Examination of satellite imagery clearly reveals the wide-spread presence of gyres in thermokarst lakes. It allows the study of gyres and other circulation patterns at both lake and regional scales. This study examines the movement (speed, direction) of a 10-km-wide gyre using a Landsat-7 and an ASTER scene taken about 40 minutes apart. These two images are matched using a robust image matching technique based on cross-correlation. Flow speed and direction for the gyre are extracted from the images and are compared with the in situ measurements collected during previous field work. This study provides insight into the evolution of thermokarst lakes and their interaction with the local climate by quantifying gyre circulation rates over entire lakes.

  20. East Gwillimbury Whitchurch-

    E-print Network

    Toronto, University of

    3000 3500 4000 76+66-7556-6546-5536-4526-3516-256-150-5 Municipality Age Cohort Numberof BY RESIDENTS OF EAST GWILLIMBURY Trip Purpose Category HB-W HB-S HB-D N-HB% of 24 hr.TripsTime Period 6 - 9 a Other% of 24 hr.TripsTime Period 6 - 9 a.m. 24 hours 4,100 13.1% 45% 24% 11% 21% 3,400 11.9% 41% 22% 12

  1. East Asian observations

    NASA Astrophysics Data System (ADS)

    Stephenson, F. R.

    East Asian observations are of established importance in Applied Historical Astronomy. The earliest astronomical records from this part of the world (China, Japan and Korea) originate from China. These observations, mainly of lunar eclipses, are recorded on oracle bones from the period ca. 1300 - 1050 BC. Virtually all later Chinese and other East Asian astronomical records now exist only in printed copies. The earliest surviving series of solar eclipse observations from any part of the world is contained in the Chunqiu (722 - 481 BC), a chronicle of the Chinese state of Lu. However, not until after 200 BC, with the establishment of a stable empire in China, do detailed astronomical records survive. These are mainly contained in specially compiled astrological treatises in the official dynastic histories. Such records, following the traditional style, extend down to the start of the present century. All classes of phenomena visible to the unaided eye are represented: solar and lunar eclipses, lunar and planetary movements among the constellations, comets, novae and supernovae, meteors, sunspots and the aurora borealis. Parallel, but independent series of observations are recorded in Japanese and Korean history, especially after about AD 800. Sources of Japanese records tend to be more diverse than their Chinese and Korean counterparts, but fortunately Kanda Shigeru (1935) and Ohsaki Shyoji (1994) have made extensive compilations of Japanese astronomical observations down to the 1860s. Throughout East Asia, dates were expressed in terms of a luni-solar calendar.

  2. Influenza in East Africa

    PubMed Central

    Montefiore, D.; Drozdov, S. G.; Kafuko, G. W.; Fayinka, O. A.; Soneji, A.

    1970-01-01

    Very little information is available concerning the frequency of influenza in East Africa. Following recent outbreaks of influenza in Uganda, that were due to the A2/Hong Kong/68 virus, it was considered useful to obtain information relating to the prevalence of infection due to this virus and to the current strain of influenza B virus, not only in Uganda but also in the neighbouring territories of Kenya and Tanzania. The results of serological testing of sera showed that widespread outbreaks of influenza A2/Hong Kong/68 infection had occurred recently in all three territories, while there was evidence of sporadic infection in all territories by the current influenza B strain. Despite the favourable climate of East Africa, it is evident that widespread outbreaks of influenza can occur, and these may arise during the period of the year when influenza is rare in countries with temperate climates. Influenza can easily spread to other countries via air travellers to and from East Africa. PMID:5312523

  3. Yellowstone lake nanoarchaeota.

    PubMed

    Clingenpeel, Scott; Kan, Jinjun; Macur, Richard E; Woyke, Tanja; Lovalvo, Dave; Varley, John; Inskeep, William P; Nealson, Kenneth; McDermott, Timothy R

    2013-01-01

    Considerable Nanoarchaeota novelty and diversity were encountered in Yellowstone Lake, Yellowstone National Park (YNP), where sampling targeted lake floor hydrothermal vent fluids, streamers and sediments associated with these vents, and in planktonic photic zones in three different regions of the lake. Significant homonucleotide repeats (HR) were observed in pyrosequence reads and in near full-length Sanger sequences, averaging 112 HR per 1349 bp clone and could confound diversity estimates derived from pyrosequencing, resulting in false nucleotide insertions or deletions (indels). However, Sanger sequencing of two different sets of PCR clones (110 bp, 1349 bp) demonstrated that at least some of these indels are real. The majority of the Nanoarchaeota PCR amplicons were vent associated; however, curiously, one relatively small Nanoarchaeota OTU (71 pyrosequencing reads) was only found in photic zone water samples obtained from a region of the lake furthest removed from the hydrothermal regions of the lake. Extensive pyrosequencing failed to demonstrate the presence of an Ignicoccus lineage in this lake, suggesting the Nanoarchaeota in this environment are associated with novel Archaea hosts. Defined phylogroups based on near full-length PCR clones document the significant Nanoarchaeota 16S rRNA gene diversity in this lake and firmly establish a terrestrial clade distinct from the marine Nanoarcheota as well as from other geographical locations. PMID:24062731

  4. Whiting in Lake Michigan

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Satellites provide a view from space of changes on the Earth's surface. This series of images from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) aboard the Orbview-2 satellite shows the dramatic change in the color of Lake Michigan during the summer. The bright color that appears in late summer is probably caused by calcium carbonate-chalk-in the water. Lake Michigan always has a lot of calcium carbonate in it because the floor of the lake is limestone. During most of the year the calcium carbonate remains dissolved in the cold water, but at the end of summer the lake warms up, lowering the solubility of calcium carbonate. As a result, the calcium carbonate precipitates out of the water, forming clouds of very small solid particles that appear as bright swirls from above. The phenomenon is appropriately called a whiting event. A similar event occured in 1999, but appears to have started later and subsided earlier. It is also possible that a bloom of the algae Microcystis is responsible for the color change, but unlikely because of Lake Michigan's depth and size. Microcystis blooms have occured in other lakes in the region, however. On the shore of the lake it is possible to see the cities of Chicago, Illinois, and Milwaukee, Wisconsin. Both appear as clusters of gray-brown pixels. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  5. Yellowstone Lake Nanoarchaeota

    PubMed Central

    Clingenpeel, Scott; Kan, Jinjun; Macur, Richard E.; Woyke, Tanja; Lovalvo, Dave; Varley, John; Inskeep, William P.; Nealson, Kenneth; McDermott, Timothy R.

    2013-01-01

    Considerable Nanoarchaeota novelty and diversity were encountered in Yellowstone Lake, Yellowstone National Park (YNP), where sampling targeted lake floor hydrothermal vent fluids, streamers and sediments associated with these vents, and in planktonic photic zones in three different regions of the lake. Significant homonucleotide repeats (HR) were observed in pyrosequence reads and in near full-length Sanger sequences, averaging 112 HR per 1349 bp clone and could confound diversity estimates derived from pyrosequencing, resulting in false nucleotide insertions or deletions (indels). However, Sanger sequencing of two different sets of PCR clones (110 bp, 1349 bp) demonstrated that at least some of these indels are real. The majority of the Nanoarchaeota PCR amplicons were vent associated; however, curiously, one relatively small Nanoarchaeota OTU (71 pyrosequencing reads) was only found in photic zone water samples obtained from a region of the lake furthest removed from the hydrothermal regions of the lake. Extensive pyrosequencing failed to demonstrate the presence of an Ignicoccus lineage in this lake, suggesting the Nanoarchaeota in this environment are associated with novel Archaea hosts. Defined phylogroups based on near full-length PCR clones document the significant Nanoarchaeota 16S rRNA gene diversity in this lake and firmly establish a terrestrial clade distinct from the marine Nanoarcheota as well as from other geographical locations. PMID:24062731

  6. LAKE RESTORATION BY DILUTION: MOSES LAKE, WASHINGTON

    EPA Science Inventory

    Dilution water, low in macronutrients, was added to Moses Lake on three occasions in 1977 and once in 1978 during the spring-summer period. The addition resulted in reducing the annual average inflow concentration of phosphorus from about 130-140 micrograms/l to 100 micrograms/l....

  7. Hydrological and chemical budgets in a volcanic caldera lake: Lake Kussharo, Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Chikita, Kazuhisa A.; Nishi, Masataka; Fukuyama, Ryuji; Hamahara, Kazuhiro

    2004-05-01

    The contribution of groundwater output and input to lake chemistry was examined by estimating the hydrological and chemical budgets of a volcanic caldera lake, Lake Kussharo, Hokkaido, Japan. The lake level, meteorology, river water discharge and water properties were measured in the ice-covered period of February-March and in the open-water period of June-October in 2000. The inorganic chemistry was then analyzed for sporadically sampled surface water and hot spring water. The chemistry of lake water at pH of 6.91-7.57 and EC25 (electric conductivity at 25 °C) of 29.2-32.7 mS/m appears to be controlled by the input of two types of hot spring water: the inflowing Yunokawa River (pH of 2.27-2.54 and EC25 of 197.8-258.0 mS/m) and groundwater discharging directly on the shore (pH of 7.13-8.32, water temperature of 35.0-46.5 °C and EC25 of 53.1-152.0 mS/m). Excluding the days with rainfall or a great change in lake level, the water budget in June-October gave a net groundwater input of -7.41 to 2.97 m 3/s. A combination of the water budget with the chemical budget of two solutes, Na + and Cl -, led to the best estimate of groundwater output, Gout, at 3.82±3.02 m 3/s, the total fresh groundwater input, ? Gfresh, at 2.14±1.00 m 3/s, and the total groundwater input of hot springs, ? Gspa, at 0.46±0.05 m 3/s. This is comparable to G out=3.87 m3/ s, ?G fresh=1.49 m3/ s and ?G spa=0.41 m3/ s during the ice-covered period. The chemical flux by the freshwater input plays an important role in the alkalinity of lake water, as does the chemical flux by the shoreline hot springs. The large groundwater output could occur by the leakage through the highly permeable, underground pumice, distributed from the east-to-south lake basin to southeast of the outlet.

  8. Elevation Changes Over Large Antarctic Subglacial Lakes From ICESat Repeat Altimetry 2003-2008

    NASA Astrophysics Data System (ADS)

    Shuman, C.; Studinger, M.; Bell, R. E.; Suchdeo, V. P.

    2008-12-01

    Antarctica's recently described Recovery Lakes group (Bell et al., 2007, lakes A-D, about 13,300 km2) and well-known Lake Vostok (15,690 km2) are crossed by numerous Ice, Cloud, and land Elevation Satellite (ICESat) altimetry profiles. Since those laser measurements began in 2003, more than 13 repeats of each profile have been completed, and preliminary elevation change results from ICESat are available. Because of Lake Vostok's overall size and the Recovery Lakes relationship to the acceleration of ice into East Antarctica's Recovery Ice Stream, analyses of lake levels have immediate relevance to broader ice sheet stability assessments. Our study uses ICESat crossovers to assess elevation changes across these two subglacial lake sites to compensate for inexact repeat profiles that cross the subglacial lake topography at varying locations and angles. Lake Vostok's relative stability, documented by a multi-year GPS network around Vostok Station (Richter et al., 2008), makes it an excellent target for assessing repeat altimetry accuracy; ICESat results are compatible with the GPS network results but reveal the difficulty in determining an elevation time series with cm-level accuracy. Recovery Lake A appears to be rising, about 5 cm over 2004-2007, whereas Lake B shows no clear pattern with respect to off lake elevations. Recovery Lakes C and D are also currently being evaluated in preparation for Norway-US IPY traverse and planned airborne geophysical surveys by British and US teams. Updated ICESat elevation time series results will be available prior to IPY fieldwork initiation. Bell, R.E., M. Studinger, C.A. Shuman, M.A. Fahnestock, and I. Joughin, (2007), Large subglacial lakes in East Antarctica at the onset of fast-flowing ice streams, Nature, vol. 445, pp. 904-907, doi:10.1038/nature05554 Richter, A., S. Popov, R. Dietrich, V. Lukin, M. Fritsche, V. Y. Lipenkov, A. Matveev, J. Wendt, A. Yuskevich, and V. Masolov (2008), Observational evidence on the stability of the hydro-glaciological regime of subglacial Lake Vostok, Geophysical Research Letters, doi:10.1029/2008GL033397

  9. Comparison of Offshore Turbidite records and Lake Disturbance Events at the Latitude of Seattle, Washington

    NASA Astrophysics Data System (ADS)

    Galer, S.; Goldfinger, C.; Morey, A. E.; Black, B.; Romsos, C.; Beeson, J. W.; Erhardt, M.

    2014-12-01

    We are investigating the paleoseismic history of northern Washington using offshore turbidite cores and lake sediments collected from forearc lakes along a transect from offshore to Seattle, Washington. Additional offshore cores, ash determinations and heavy mineral analysis flesh out the turbidite stratigraphy off northern Washington, and support 3-5 proximal turbidites in northern Washington canyons (see Adams, 1990) in addition to the 19 regionally correlated beds. Onshore, we have cored multiple lakes including (west to east) Beaver, Leland, Tarboo, Hall, Sawyer, and Wapato, east of the Cascades, and collected multibeam bathymetry, backscatter and chirp subbottom data. These lakes are small (2-113 ha), 6-18 m deep, and are all kettle lakes except Beaver Lake (landslide-dammed) and Wapato Lake, a glacial scour. These lakes were selected for their limited outside sediment sources and low sensitivity to ground shaking. The sedimentology is mostly organic-rich gyttja. All lakes contain the Mazama ash based on its similar depth occurrence in previously published cores and new EMP analysis. Computed Tomography (CT) density, gamma density, and magnetic susceptibility (ms) data show there is more stratigraphic variability than is visually apparent. Low-energy disturbance events are apparent in the stratigraphy of all lakes (except Hall) as increases in clastics, density, and ms. The number of post Mazama disturbance events is similar to the number of expected great earthquakes found offshore and onshore, though definition of the boundaries of the lake events is much less clear. Initial radiocarbon results and preliminary correlations along this 185 km transect show strong similarities in stratigraphic records between these cores over the past ~7600 years, anchored by the Mazama tephra. Preliminary comparisons with offshore cores show a striking similarity in downcore variability in physical properties. Given the evidence for earthquake origin for the offshore cores, and the strong common signal across the lake transect, we suggest that the lake disturbance events are likely of earthquake origin, representing turbidites generated internally within each lake. Analysis continues with the goal of estimating slope stability and minimum levels of ground shaking required to destabilize lake margins.

  10. Regional pattern of snow characteristics around Antarctic Lake Vostok

    NASA Astrophysics Data System (ADS)

    Vladimirova, Diana; Ekaykin, Alexey; Popov, Sergey; Shibaev, Yuriy; Kozachek, Anna; Lipenkov, Vladimir

    2015-04-01

    Since 1998 Russian Antarctic Expedition has organized several scientific traverses in the region of subglacial Lake Vostok mainly devoted to the radar echo and seismic sounding of the glacier and water (the results have been published elsewhere). Along with the geophysical studies, a number of glaciological investigations have been carried out: snow pit digging, installation of accumulation stakes, snow sampling to study the stable water isotope content. Here we for the first time present a synthesis of these works and demonstrate a series of maps that characterize the snow density, isotope content and accumulation rate the studied region. A general tendency of the snow accumulation rate and isotope content is a significant increase from south (south-west) to north (north-east) from 35 to 23 mm w.e. per year and from -53,3 ‰ to -57,3 ‰ for delta oxygen-18 respectively, which likely reflects the continental-scale pattern, i.e., increase from inland to the coast. Deuterium excess varies from 11,7 ‰ to 16,3 ‰ is negatively correlated with the isotope content, which is typical for central Antarctica. The snow density demonstrate different pattern: higher values offshore the lake (up to 0,356 g/cm^3), and lower values within the lake's shoreline (lower limit is 0,328 g/cm^3). We suggest that this is related to the katabatic wind activity: very flat nearly horizontal surface of the glacier above the lake is not favorable for the strong winds, which leads to lower surface snow density. Superimposed on the main trend is the regional pattern, namely, curved contour lines in the middle part of the lake. We suggest that it may be related to the local anomalies of the snow drift by wind. Indeed, on the satellite images of the lake one can easily see a snowdrift stretching from the lake's western shore downwind in the middle part of the lake. The isolines of delta oxygen-18 and deuterium excess become perpendicular to each other in the north part of the lake which also could be related to wind activity and different time of exposition snow on the surface which potentially leads to changing in d-excess and water isotopes ratio relation. Another interesting feature is the minimum values of snow accumulation rate and isotope content to the south-east from Vostok station. Before present, the Vostok's close vicinity was the record-holder, but now it is obvious that the pole of the lowest values of these parameters is somewhere else. This finding may be important in terms of the search of the oldest ice in frames of the IPICS "1.5Ma" project.

  11. Hydrogeologic setting east of a low-level radioactive-waste disposal site near Sheffield, Illinois

    USGS Publications Warehouse

    Foster, J.B.; Garklavs, George; Mackey, G.W.

    1984-01-01

    Core samples from 45 test wells and 4 borings were used to describe the glacial geology of the area east of the low-level radioactive-waste disposal site near Sheffield, Bureau County, Illinois. Previous work has shown that shallow ground water beneath the disposal site flows east through a pebbly-sand unit of the Toulon Member of the Glasford Formation. The pebbly sand was found in core samples from wells in an area extending northeast from the waste-disposal site to a strip-mine lake and east along the south side of the lake. Other stratigraphic units identified in the study area are correlated with units found on the disposal site. The pebbly-sand unit of the Toulon Member grades from a pebbly sand on site into a coarse gravel with sand and pebbles towards the lake. The Hulick Till Member, a key bed, underlies the Toulon Member throughout most of the study area. A narrow channel-like depression in the Hulick Till is filled with coarse gravelly sand of the Toulon Member. The filled depression extends eastward from near the northeast corner of the waste-disposal site to the strip-mine lake. (USGS)

  12. IONIC COMPOSITION OF ACID LAKES IN RELATION TO AIRBORNE INPUTS AND WATERSHED CHARACTERISTICS

    EPA Science Inventory

    Present acid forming emissions to the atmosphere have the potential to alter significantly the chemistry of rain, snow, and surface water of weakly buffered lakes in the Upper Midwest. Average precipitation pH from field measurements during 1979-1983 declined from west to east fr...

  13. 75 FR 66779 - Ruby Lake National Wildlife Refuge, Elko and White Pine Counties, NV; Comprehensive Conservation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-29

    ... along the Humboldt River to the Owens Valley, east to Utah's Great Salt Lake, northwest to the Klamath...,926-acre refuge. The marsh is surrounded by 22,926 acres of meadows, grasslands, alkali playa, and shrub-steppe uplands. Water elevations in some marsh units are controlled to provide nesting and...

  14. 75 FR 66779 - Ruby Lake National Wildlife Refuge, Elko and White Pine Counties, NV; Comprehensive Conservation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-29

    ...Elko and White Pine Counties of Nevada. We provide this notice in...60, Box 860, Ruby Valley, Nevada 89833-9802. In-Person...Owens Valley, east to Utah's Great Salt Lake, northwest to the Klamath Basin, and south to the...

  15. TRANSPORT STUDIES IN THE LOCK LAKE TIDAL MARSH OF SOUTHERN LONG ISLAND

    EPA Science Inventory

    Ground water discharges directly into the Great South Bay and also via a sideways route into the Lock Lake tidal marsh at East Patchogue, New York. Data collected from the site were used to assess the transport of ground water contaminants into the waters of the Bay and potentia...

  16. Paleomagnetism of Lake Sediments, Chew Bahir, Ethiopia

    NASA Astrophysics Data System (ADS)

    Frank, U.; Brown, M. C.; Foerster, V. E.; Schäbitz, F.

    2011-12-01

    Quasi-continuous variations of the Earth's magnetic field recorded in lake sediments can provide detailed time series describing the evolution of the geomagnetic field. To make robust conclusions about underlying geodynamo processes an improvement in the global coverage of recording sites is required. Current lake data for the late Brunhes are biased towards Europe and North America with only five studies reporting paleomagnetic results from equatorial Africa. We present inclination and relative paleointensity from Chew Bahir, southern Ethiopia; a saline mudflat located in the East African Ridge System, previously covered by a ~2000 km2 lake. Discrete measurements were made on two ten meter cores, which we continuously sub-sampled at 2 cm intervals. Calibrated AMS radiocarbon ages constrain the base of the cores to ~45 ka. NRM was demagnetized in ten steps up to 100 mT and well defined characteristic remanence directions, with MAD < 3°, were determined for the majority of specimens. Secondary components of magnetization were generally removed after alternating field demagnetization to 15 mT. Inclination is compared with previously obtained directional records from Lake Turkana, northern Kenya (~60 km to the southwest of Chew Bahir), and we discuss differences between these records. The ratio of NRM to ARM intensity at 20 mT was used as a proxy for relative paleointensity. Broad similarities in variations in relative paleointensity are seen between Chew Bahir and other globally distributed sites; most evidently through the Holocene. The magnetic mineralogy of the cores has been determined using a number of rock magnetic methods and has been used to assess the fidelity of the paleomagnetic records.

  17. Recent Changes in the Summer Precipitation Pattern in East China and the Background Circulation

    NASA Astrophysics Data System (ADS)

    Zhu, Y.; Wang, H.; Zhou, W.; Ma, J.

    2010-12-01

    This study documents the decadal changes of the summer precipitation in East China, with increased rainfall in the Huang-Huai River region (HR) and decreased in the Yangtze River region (YR) during 2000-2008 in comparison to 1979-1999. The main features of the atmospheric circulation related to the increased precipitation in the HR are the strengthened ascending motion and slightly increased air humidity, which is partly due to the weakened moisture transport out of the HR to the western tropical Pacific (associated with the weakened westerly over East Asia and the warming center over the Lake Baikal). The rainfall decrease in the YR is related to the weakened ascending motion and reduced water vapor content, which is mainly related to the weakened southwesterly moisture flux into the YR (associated with the eastward recession of the Western Pacific Subtropical High). The global sea surface temperature (SST) also shows significant changes during 2000-2008 relative to 1979-1999. The shift of the Pacific Decadal Oscillation (PDO) to a negative phase probably induces the warming over the Lake Baikal and the weakened westerly jet through the air-sea interaction in the Pacific, and thus changes the summer precipitation pattern in East China. Numerical experiments using an atmospheric general circulation model, with prescribed all-Pacific SST anomalies of 2000-2008 relative to 1979-1999, also lend support to the PDO’s contribution to the warming over the Lake Baikal and the weakened westerlies over East China.

  18. Recent changes in the summer precipitation pattern in East China and the background circulation

    NASA Astrophysics Data System (ADS)

    Zhu, Yali; Wang, Huijun; Zhou, Wen; Ma, Jiehua

    2011-04-01

    This study documents the decadal changes of the summer precipitation in East China, with increased rainfall in the Huang-Huai River region (HR) and decreased in the Yangtze River region (YR) during 2000-2008 in comparison to 1979-1999. The main features of the atmospheric circulation related to the increased precipitation in the HR are the strengthened ascending motion and slightly increased air humidity, which is partly due to the weakened moisture transport out of the HR to the western tropical Pacific (associated with the weakened westerly over East Asia and the warming center over the Lake Baikal). The rainfall decrease in the YR is related to the weakened ascending motion and reduced water vapor content, which is mainly related to the weakened southwesterly moisture flux into the YR (associated with the eastward recession of the Western Pacific Subtropical High). The global sea surface temperature (SST) also shows significant changes during 2000-2008 relative to 1979-1999. The shift of the Pacific decadal oscillation (PDO) to a negative phase probably induces the warming over the Lake Baikal and the weakened westerly jet through the air-sea interaction in the Pacific, and thus changes the summer precipitation pattern in East China. Numerical experiments using an atmospheric general circulation model, with prescribed all-Pacific SST anomalies of 2000-2008 relative to 1979-1999, also lend support to the PDO's contribution to the warming over the Lake Baikal and the weakened westerlies over East China.

  19. Glacial Lake Musselshell: Late Wisconsin slackwater on the Laurentide ice margin in central Montana, USA

    USGS Publications Warehouse

    Davis, N.K.; Locke, W. W., III; Pierce, K.L.; Finkel, R.C.

    2006-01-01

    Cosmogenic surface exposure ages of glacial boulders deposited in ice-marginal Lake Musselshell suggest that the lake existed between 20 and 11.5 ka during the Late Wisconsin glacial stage (MIS 2), rather than during the Late Illinoian stage (MIS 6) as traditionally thought. The altitude of the highest ice-rafted boulders and the lowest passes on the modern divide indicate that glacial lake water in the Musselshell River basin reached at least 920-930 m above sea level and generally remained below 940 m. Exposures of rhythmically bedded silt and fine sand indicate that Lake Musselshell is best described as a slackwater system, in which the ice-dammed Missouri and Musselshell Rivers rose and fell progressively throughout the existence of the lake rather than establishing a lake surface with a stable elevation. The absence of varves, deltas and shorelines also implies an unstable lake. The changing volume of the lake implies that the Laurentide ice sheet was not stable at its southernmost position in central Montana. A continuous sequence of alternating slackwater lake sediment and lacustrine sheetflood deposits indicates that at least three advances of the Laurentide ice sheet occurred in central Montana between 20 and 11.5 ka. Between each advance, it appears that Lake Musselshell drained to the north and formed two outlet channels that are now occupied by extremely underfit streams. A third outlet formed when the water in Lake Musselshell fully breached the Larb Hills, resulting in the final drainage of the lake. The channel through the Larb Hills is now occupied by the Missouri River, implying that the present Missouri River channel east of the Musselshell River confluence was not created until the Late Wisconsin, possibly as late as 11.5 ka. ?? 2005 Elsevier B.V. All rights reserved.

  20. Carbon accumulation and sequestration of lakes in China during the Holocene.

    PubMed

    Wang, Mei; Chen, Huai; Yu, Zicheng; Wu, Jianghua; Zhu, Qiu'an; Peng, Changhui; Wang, Yanfen; Qin, Boqiang

    2015-12-01

    Understanding the responses of lake systems to past climate change and human activity is critical for assessing and predicting the fate of lake carbon (C) in the future. In this study, we synthesized records of the sediment accumulation from 82 lakes and of C sequestration from 58 lakes with direct organic C measurements throughout China. We also identified the controlling factors of the long-term sediment and C accumulation dynamics in these lakes during the past 12 ka (1 ka = 1000 cal yr BP). Our results indicated an overall increasing trend of sediment and C accumulation since 12 ka, with an accumulation peak in the last couple of millennia for lakes in China, corresponding to terrestrial organic matter input due to land-use change. The Holocene lake sediment accumulation rate (SAR) and C accumulation rate (CAR) averaged (mean ± SE) 0.47 ± 0.05 mm yr(-1) and 7.7 ± 1.4 g C m(-2)  yr(-1) in China, respectively, comparable to the previous estimates for boreal and temperate regions. The SAR for lakes in the East Plain of subtropical China (1.05 ± 0.28 mm yr(-1) ) was higher than those in other regions (P < 0.05). However, CAR did not vary significantly among regions. Overall, the variability and history of climate and anthropogenic interference regulated the temporal and spatial dynamics of sediment and C sequestration for lakes in China. We estimated the total amount of C burial in lakes of China as 8.0 ± 1.0 Pg C. This first estimation of total C storage and dynamics in lakes of China confirms the importance of lakes in land C budget in monsoon-influenced regions. PMID:26220607

  1. Is Lake Tahoe Terminal?

    NASA Astrophysics Data System (ADS)

    Coats, R. N.; Reuter, J.; Heyvaert, A.; Lewis, J.; Sahoo, G. B.; Schladow, G.; Thorne, J. H.

    2014-12-01

    Lake Tahoe, an iconic ultra-oligotrophic lake in the central Sierra Nevada, has been studied intensively since 1968, with the goal of understanding and ultimately controlling its eutrophication and loss of clarity. Research on the lake has included a) periodic profiles of primary productivity, nutrients, temperature, and plankton; b) Secchi depth; c) nutrient limitation experiments; d) analysis of sediment cores; e) radiocarbon dating of underwater in-place tree stumps; g) analysis of long-term temperature trends. Work in its watershed has included a) monitoring of stream discharge, sediment and nutrients at up to 20 stream gaging stations; b) monitoring of urban runoff water quality at selected sites; c) development of a GIS data base, including soils, vegetation, and land use. Based on these studies, we know that a) primary productivity in the lake is limited by phosphorus, and continues to increase; b) the loss of clarity continues, but at a declining rate; c) the lake has been warming since 1970, and its resistance to deep mixing is increasing; d) historically the lake level drops below the outlet elevation about one year in seven; e) 6300 to 4300 yrs BP lake level was below the present outlet elevation long enough for large trees to grow; f) the date of the peak snowmelt runoff is shifting toward earlier dates; g) after accounting for annual runoff, loads of nutrients and suspended sediment have declined significantly in some basin streams since 1980. Downscaled outputs from GCM climatic models have recently been used to drive hydrologic models and a lake clarity model, projecting future trends in the lake and watersheds. Results show a) the temperature and thermal stability will likely continue to increase, with deep mixing shutting down in the latter half of this century; b) the lake may drop below the outlet for an extended period beginning about 2085; c) the annual snowpack will continue to decline, with earlier snowmelt and shift from snowfall to rain; d) the climatic water deficit will increase, especially at high elevations that will be most affected by the loss of snow, with likely consequences for existing vegetation and fire frequency. Hydrologically, Lake Tahoe is intermittently terminal; in a medical sense it is not yet terminal, but its condition—especially its valued clarity and deep blue color--is serious.

  2. Dragon Lake, Siberia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Nicknamed 'Dragon Lake,' this body of water is formed by the Bratskove Reservoir, built along the Angara river in southern Siberia, near the city of Bratsk. This image was acquired in winter, when the lake is frozen. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on December 19, 1999. This is a natural color composite image made using blue, green, and red wavelengths. Image provided by the USGS EROS Data Center Satellite Systems Branch

  3. Lake Superior, Duluth, MN

    NASA Technical Reports Server (NTRS)

    1973-01-01

    This view shows the west end of Lake Superior and Duluth, MN (47.0N, 91.0W). Portions of Minnesota, Michigan and Ontario, Canada are in the scene. The Duluth metropolitan area is at the west end of the lake. The discoloration plume in the water at Duluth is the result of tailings from the iron ore smelters that process the iron ore from the nearby open pit mines seen near the upper left corner of the photo.

  4. Style and dating of lacustrine sedimentation at Big Lake, Arkansas

    SciTech Connect

    Guccione, M.J.; Hehr, L.H. . Dept. of Geology)

    1993-03-01

    Sunklands of northeast Arkansas are lakes or swampy areas along streams with locally low gradients. They have been attributed to subsidence associated with the 1811--1812 New Madrid earthquakes. At the Big Lake sunkland the contact of underlying fluvial/backswamp sediment with organics and/or silty clay lacustrine sediment is abrupt in 19 of 20 cores and organics are present in 13 cores. A C[sup 14] age of wood at the contact is 160 [+-] 70 BP. Four additional dates [le]1 meter below the contact range from 200 to 440 radiocarbon years BP. The overlying lacustrine silty clay from 3 cores has been dated using Pb[sup 210] and has accumulated in the last 70 years. In the early 19th century the sedimentation pattern and rate in the Big Lake area abruptly changed. Earlier, sand was deposited by flowing water in anastomosing channels of the Little River and silt and clay were deposited in the surrounding backswamp. Approximately 1808 AD ([+-]70 years) mineral sedimentation slowed and organic mats and laminae accumulated as water velocity was reduced and vegetation drowned. Man's influence beginning in the early 20th century caused rapid influx of silty clay. Sediment initiation coincided with dredging a drainage ditch east of Big Lake and initiation of agriculture. Thus lacustrine accumulation of organics was the natural response to formation of Big Lake and its age is consistent with that of the New Madrid earthquakes. Subsequent rapid lacustrine accumulation of silt and clay is a human artifact.

  5. Dynamics of suspended sediment plumes in Lake Ontario

    NASA Technical Reports Server (NTRS)

    Pluhowski, E. J. (principal investigator)

    1974-01-01

    The author has identified the following significant results. Two unusual turbidity features were detected in imagery obtained over Lake Ontario on September 19, 1973. The location of a submerged sewer outfall was detected in frame 1423-15224-5 about 2 kilometers offshore opposite a treatment plant serving Rochester, New York. The other feature was a thermal heat plume made visible by an erosive eastward moving longshore current. The thermal plume, which extended about 3 kilometers into the lake, results from the discharge of cooling water from a nuclear power plant located 20 miles east of Rochester, New York. Under an offshore wind field, the outer edge of the Niagara River plume extended 30 kilometers into Lake Ontario on September 3, 1973. By way of contrast, a strong west-northwest wind on April 29, 1973, confined the plume to about 3 kilometers of the lake's south shore. The size of the Genesee River plume is largely dependent on discharge. During the spring high flow season, the plume extended over 22 square kilometers of the lake's surface on May 16, 1973. As runoff dwindled with the approach of summer, the plume contracted to less than 1 square kilometer in area by mid-July.

  6. The distribution of aromatic hydrocarbons in western Lake Erie

    SciTech Connect

    Metcalfe, C.D.; Metcalfe, T.L.; Koenig, B.G.; Haffner, G.D.

    1995-12-31

    In order to determine whether biota in western Lake Erie are exposed to elevated concentrations of aromatic hydrocarbons, the authors collected biota along a corridor extending from Peche Island in the Detroit River to Pelee Island in western Lake Erie and determined concentrations of polynuclear aromatic hydrocarbons (PAHs) in zebra mussels, and levels of fluorescent aromatic compounds (FACs) in the bile of freshwater drum and gizzard shad. In addition, they deployed semi-permeable membrane devices (SPMDs) at various locations along this corridor to monitor for PAHs in water. PAHs were elevated in SPMDs and zebra mussels from the Detroit River, and PAH concentrations declined from west to east in Lake Erie. There were elevated levels of bile FACs in drum and gizzard shad from highly contaminated regions of the Detroit River. These data are consistent with the Detroit River being a significant source of PAH contamination in western Lake Erie. Since the ratios of concentrations of PAHs and PCBs in zebra mussels did not vary throughout the study area, it appears that both classes of aromatic contaminants are distributed by similar mechanisms throughout western Lake Erie.

  7. East Asian Security in 2025 

    E-print Network

    Heavin, Reagan; Hudson, Adam; Krueger, Brandon; O'Neil, Sean; Rozell, Griffin; Suma, Matt

    2008-01-01

    Are • Reagan Heavin – Energy • Adam Hudson – State Capacity • Brandon Krueger – Military • Sean O’Neil – Demographics • Griffin Rozell – Balance of Power • Matt Suma – Economy East Asian Security in 2025 China: Competition, Cooperation, Plateau? Reagan Heavin... Adam Hudson Brandon Krueger Sean O’Neil Griffin Rozell Matt Suma 24 April 2008 East Asian Security in 2025 Agenda • Conclusions • Projections • Drivers • Four Outcomes • Questions East Asian Security in 2025 Conclusions • China will rise to great power...

  8. East African Rift Valley, Kenya

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This rare, cloud free view of the East African Rift Valley, Kenya (1.5N, 35.5E) shows a clear view of the Turkwell River Valley, an offshoot of the African REift System. The East African Rift is part of a vast plate fracture which extends from southern Turkey, through the Red Sea, East Africa and into Mozambique. Dark green patches of forests are seen along the rift margin and tea plantations occupy the cooler higher ground.

  9. The Lakes of Titan

    NASA Astrophysics Data System (ADS)

    Lunine, J.; Stofan, E.; Elachi, C.; Lorenz, R.; Stiles, B.; Mitchell, K. L.; Ostro, S.; Soderblom, L.; Wood, C.; Zebker, H.; Wall, S.; Janssen, M.; Kirk, R.; Lopes, R.; Paganelli, F.; Radebaugh, J.; Wye, L.; Callahan, P.; Anderson, Y.; Allison, M.; Boehmer, R.; Encrenaz, P.; Flamini, E.; Franceschetti, G.; Gim, Y.; Hamilton, G.; Hensely, S.; Johnson, W. T.; Kelleher, K.; Muhleman, D.; Paillou, P.; Picardi, G.; Posa, F.; Roth, L.; Seu, R.; Shaffer, S.; Vetrella, S.; West, R.; Orosei, R.

    2006-12-01

    The Cassini Radar flyby of Saturn's moon Titan on 22 July 2006 (T16) provides compelling evidence for the presence of liquid lakes on the surface of Titan. The radar images polewards of 70°N show over 75 circular to irregular radar dark patches from 3 km to over 170 km across, in a region where liquid methane and ethane are expected to be abundant and stable on the surface. Some patches are uniformly dark in appearance, with no measureable echo, while others vary in brightness. We interpret these as lakes based on their very low radar reflectivity and morphological similarities to lakes, including associated channels, location in topographic depressions and multiple shorelines. Lakes appear in a number of apparent states, including fully drained, partially dry and liquid-filled. These northern hemisphere lakes constitute the strongest evidence yet that a condensable-liquid hydrological cycle is active in Titan's surface and atmosphere, in which the lakes are filled through rainfall and/or intersection with the subsurface `liquid methane' table.

  10. East Africa continental margins

    SciTech Connect

    Bosellini, A.

    1986-01-01

    New well data from Somalia, together with the history of sea-floor spreading in the Indian Ocean derived from magnetic anomalies, show that the East African margins from latitude 15/sup 0/S into the Gulf of Aden comprise four distinct segments that formed successively by the southward drift of Madagascar from Somalia during the Middle to Late Jurassic and Early Cretaceous, by the northeastward drift of India along the Owen Transform during the Late Cretaceous and Paleocene, and by the opening of the Gulf of Aden during the Neogene.

  11. Recovery giant subglacial lakes: new assessments using IceGRAV airborne radar data

    NASA Astrophysics Data System (ADS)

    Matsuoka, K.; Forsberg, R.; Ferraccioli, F.; Jordan, T. A.; Kohler, J.; Corr, H. F. J.; Olesen, A. V.

    2014-12-01

    Recovery Glacier penetrates deep into the interior of East Antarctica. The subglacial hydraulic system beneath this glacier includes active lakes aligned along the glacier trunk and four giant lakes near the onset of the fast flow. The characteristics of this subglacial system and its impacts on ice flow are therefore central questions for the dynamics of the East Antarctic Ice Sheet. The existence of these lakes is hypothesized to explain satellite-measured ice-surface motion and smoothness. However, direct evidence of the existence of the giant Recovery lakes has until recently been limited to ground-based radar measurements during IPY, showing that the lakes A and B were not distinct lakes at the time of the measurement (January, 2009) and may have drained recently. In order to fill the significant data gap over the Recovery catchment identified by the BEDMAP2 project, over 29,000 line km of new radio-echo sounding, laser altimetry, gravity and magnetic data were acquired using a British Antarctic Survey Twin Otter during the IceGRAV 2012-13 field season. Here, we present a subset of this Recovery Frontier dataset in the vicinity of the giant Recovery lakes A and B to assess their current conditions. Bed reflectivity derived for a range of englacial attenuation rates indicates that the lake surface has larger reflectivity than the adjacent grounded areas, by more than 10 dB. Bed reflectivity varies little over short distances (< 1 km), both around the lakes and adjacent areas. Hydraulic potential varies little over the lakes as well as their downstream sides but increases in the upstream directions. These recent characteristics are clearly distinct from the previous ground-based measurements taken in 2009. We hypothesize that these differences indicate that lakes A and B may be filling. The existence of a major active hydrological system in the interior of the East Antarctic Ice Sheet could influence ice streaming also further downstream, where smaller-scale active lake systems have been inferred.

  12. Biogeochemistry and limnology in Antarctic subglacial weathering: molecular evidence of the linkage between subglacial silica input and primary producers in a perennially ice-covered lake

    NASA Astrophysics Data System (ADS)

    Takano, Yoshinori; Kojima, Hisaya; Takeda, Eriko; Yokoyama, Yusuke; Fukui, Manabu

    2015-12-01

    We report a 6,000 years record of subglacial weathering and biogeochemical processes in two perennially ice-covered glacial lakes at Rundvågshetta, on the Soya Coast of Lützow-Holm Bay, East Antarctica. The two lakes, Lake Maruwan Oike and Lake Maruwan-minami, are located in a channel that drains subglacial water from the base of the East Antarctic ice sheet. Greenish-grayish organic-rich laminations in sediment cores from the lakes indicate continuous primary production affected by the inflow of subglacial meltwater containing relict carbon, nitrogen, sulfur, and other essential nutrients. Biogenic silica, amorphous hydrated silica, and DNA-based molecular signatures of sedimentary facies indicate that diatom assemblages are the dominant primary producers, supported by the input of inorganic silicon (Si) from the subglacial inflow. This study highlights the significance of subglacial water-rock interactions during physical and chemical weathering processes and the importance of such interactions for the supply of bioavailable nutrients.

  13. TOXAPHENE STUDY OF GREAT LAKES TRIBUTARY SEDIMENTS

    EPA Science Inventory

    The Product is the paper "Pulp and Paper Mills as Sources of Toxaphene to Lake Superior and Northern Lake Michigan" published in the Journal of Great Lakes Research, 25(2):383-394 International Association of Great Lakes 1999.

  14. Phylogeography of the sponge Suberites diversicolor in Indonesia: insights into the evolution of marine lake populations.

    PubMed

    Becking, Leontine E; Erpenbeck, Dirk; Peijnenburg, Katja T C A; de Voogd, Nicole J

    2013-01-01

    The existence of multiple independently derived populations in landlocked marine lakes provides an opportunity for fundamental research into the role of isolation in population divergence and speciation in marine taxa. Marine lakes are landlocked water bodies that maintain a marine character through narrow submarine connections to the sea and could be regarded as the marine equivalents of terrestrial islands. The sponge Suberites diversicolor (Porifera: Demospongiae: Suberitidae) is typical of marine lake habitats in the Indo-Australian Archipelago. Four molecular markers (two mitochondrial and two nuclear) were employed to study genetic structure of populations within and between marine lakes in Indonesia and three coastal locations in Indonesia, Singapore and Australia. Within populations of S. diversicolor two strongly divergent lineages (A & B) (COI: p?=?0.4% and ITS: p?=?7.3%) were found, that may constitute cryptic species. Lineage A only occurred in Kakaban lake (East Kalimantan), while lineage B was present in all sampled populations. Within lineage B, we found low levels of genetic diversity in lakes, though there was spatial genetic population structuring. The Australian population is genetically differentiated from the Indonesian populations. Within Indonesia we did not record an East-West barrier, which has frequently been reported for other marine invertebrates. Kakaban lake is the largest and most isolated marine lake in Indonesia and contains the highest genetic diversity with genetic variants not observed elsewhere. Kakaban lake may be an area where multiple putative refugia populations have come into secondary contact, resulting in high levels of genetic diversity and a high number of endemic species. PMID:24098416

  15. The Wisconsin regional Integrated Lake-Watershed Acidification Study (RILWAS): 1981--1983

    SciTech Connect

    Knauer, D.; Brouwer, S.A.

    1989-01-01

    Round and East Eightmile lakes, small (14--15 ha) seepage lakes in thick (32--190 m) sandy outwash in northwestern Wisconsin, were studied from September 1981 through August 1983. Precipitation was 5 to 15 percent less than normal during the first year and 7 to 15 percent greater than normal during the second year. Snowfall accounted for 24 to 34 percent of the precipitation; however, all snowmelt infiltrated the highly permeable soils, and no spring depression in lake pH was observed. Chemistry of the precipitation was dominated by hydrogen ion, ammonium, and sulfate. Volume-weighted mean pH of bulk precipitation was 4.6 at both sites during the study, with hydrogen ion and ammonium contributing about 60 percent of the cations. Sulfate accounted for approximately 60 percent of the anions, annual sulfate fluxes ranged from 300 to 329 eq/ha. Dry deposition provided 7 to 36 percent of the total (wet plus dry) ion fluxes, except for magnesium (53 percent). Ion fluxes to the two lakes were similar. Volume-weighted mean lake pH's during the study were 6.4 at Round Lake and 6.9 at East Eightmile Lake. The two predominant forest canopies, mixed oak and jack pine, attenuated hydrogen ion; however, hydrogen-ion consumption by silicate hydrolysis exerted primary control on buffering capacity. Mineralogy of the very fine sand (100--50 ..mu..m) showed 46 to 55 percent weatherable minerals--orthoclase feldspar, plagioclase feldspar, mica, hornblende, olivine, and augite. Except for orthoclase, these minerals were depleted in the upper soil horizons, and all were undersaturated in soil solutions and ground water. The lakes contributed to the buffering capacity by producing alkalinity via surface reduction, primarily in epilimnetic lake sediment. 6 refs., 92 figs., 67 tabs.

  16. Phylogeography of the Sponge Suberites diversicolor in Indonesia: Insights into the Evolution of Marine Lake Populations

    PubMed Central

    Becking, Leontine E.; Erpenbeck, Dirk; Peijnenburg, Katja T. C. A.; de Voogd, Nicole J.

    2013-01-01

    The existence of multiple independently derived populations in landlocked marine lakes provides an opportunity for fundamental research into the role of isolation in population divergence and speciation in marine taxa. Marine lakes are landlocked water bodies that maintain a marine character through narrow submarine connections to the sea and could be regarded as the marine equivalents of terrestrial islands. The sponge Suberites diversicolor (Porifera: Demospongiae: Suberitidae) is typical of marine lake habitats in the Indo-Australian Archipelago. Four molecular markers (two mitochondrial and two nuclear) were employed to study genetic structure of populations within and between marine lakes in Indonesia and three coastal locations in Indonesia, Singapore and Australia. Within populations of S. diversicolor two strongly divergent lineages (A & B) (COI: p?=?0.4% and ITS: p?=?7.3%) were found, that may constitute cryptic species. Lineage A only occurred in Kakaban lake (East Kalimantan), while lineage B was present in all sampled populations. Within lineage B, we found low levels of genetic diversity in lakes, though there was spatial genetic population structuring. The Australian population is genetically differentiated from the Indonesian populations. Within Indonesia we did not record an East-West barrier, which has frequently been reported for other marine invertebrates. Kakaban lake is the largest and most isolated marine lake in Indonesia and contains the highest genetic diversity with genetic variants not observed elsewhere. Kakaban lake may be an area where multiple putative refugia populations have come into secondary contact, resulting in high levels of genetic diversity and a high number of endemic species. PMID:24098416

  17. Dating North America's oldest petroglyphs, Winnemucca Lake subbasin, Nevada

    USGS Publications Warehouse

    Benson, Larry V.; Hattori, E.M.; Southon, J.; Aleck, B.

    2013-01-01

    On the west side of the Winnemucca Lake subbasin, Nevada, distinctive deeply carved meter-scale petroglyphs are closely spaced, forming panels on boulder-sized surfaces of a partially collapsed tufa mound. The large, complex motifs at this side are formed by deeply carved lines and cupules. A carbonate crust deposited between 10 200 and 9800 calibrated years B.P. (ka) coats petroglyphs at the base of the mound between elevations of 1202 and 1206 m. Petroglyphs above the carbonate crust are carved into a branching form of carbonate that dates to 14.8 ka. Radiocarbon dates on a multiple-layered algal tufa on the east side of the basin, which formed at an elevation of 1205 m, as well as a sediment-core-based total inorganic carbon record for the period 17.0–9.5 ka indicate that water level in the Winnemucca Lake subbasin was constrained by spill over the Emerson Pass Sill (1207 m) for most of the time between 12.9 ± 0.3 and ?9.2 ka. These and other data indicate that the lake in the Winnemucca Lake subbasin fell beneath its spill point between 14.8 and 13.2 ka and also between 11.3 and 10.5 ka (or between 11.5 and 11.1 ka), exposing the base of the collapsed tufa mound to petroglyph carving. The tufa-based 14C record supports decreased lake levels between 14.8–13.2 ka and 11.3–10.5 ka. Native American artifacts found in the Lahontan Basin date to the latter time interval. This does not rule out the possibility that petroglyph carving occurred between 14.8 and 13.2 ka when Pyramid Lake was relatively shallow and Winnemucca Lake had desiccated.

  18. Middle East respiratory syndrome.

    PubMed

    Zumla, Alimuddin; Hui, David S; Perlman, Stanley

    2015-09-01

    Middle East respiratory syndrome (MERS) is a highly lethal respiratory disease caused by a novel single-stranded, positive-sense RNA betacoronavirus (MERS-CoV). Dromedary camels, hosts for MERS-CoV, are implicated in direct or indirect transmission to human beings, although the exact mode of transmission is unknown. The virus was first isolated from a patient who died from a severe respiratory illness in June, 2012, in Jeddah, Saudi Arabia. As of May 31, 2015, 1180 laboratory-confirmed cases (483 deaths; 40% mortality) have been reported to WHO. Both community-acquired and hospital-acquired cases have been reported with little human-to-human transmission reported in the community. Although most cases of MERS have occurred in Saudi Arabia and the United Arab Emirates, cases have been reported in Europe, the USA, and Asia in people who travelled from the Middle East or their contacts. Clinical features of MERS range from asymptomatic or mild disease to acute respiratory distress syndrome and multiorgan failure resulting in death, especially in individuals with underlying comorbidities. No specific drug treatment exists for MERS and infection prevention and control measures are crucial to prevent spread in health-care facilities. MERS-CoV continues to be an endemic, low-level public health threat. However, the virus could mutate to have increased interhuman transmissibility, increasing its pandemic potential. PMID:26049252

  19. 35. VIEW LOOKING EAST IN SOUTH END OF EAST BOILER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. VIEW LOOKING EAST IN SOUTH END OF EAST BOILER ROOM. CYLINDRICAL TANKS ARE WORTHINGTON DEAERATORS. THESE REMOVED AIR FROM BOILER FEED WATER TO MINIMIZE CORROSION AND PITTING OF THE BOILER TUBES. AIR REMOVAL ALSO HELPED AVOID THE FORMATION OF FOAM IN THE SYSTEM. - New York, New Haven & Hartford Railroad, Cos Cob Power Plant, Sound Shore Drive, Greenwich, Fairfield County, CT

  20. VIEW SOUTHWEST, NORTH AND EAST SIDE OF OFFICE BUILDING, EAST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW SOUTHWEST, NORTH AND EAST SIDE OF OFFICE BUILDING, EAST SIDE OF FOSTER HANGAR AND FRANCIS HANGAR, AND NORTH SIDE OF DAVIS HANGAR AND METAL STORAGE HANGAR - Capital City Airport, Francis Aviation, North side of Grand River Avenue, Lansing, Ingham County, MI