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Sample records for aike maar lake

  1. Rock magnetic study and paleomagnetic reconstruction from the maar Lake Laguna Potrok Aike, southern Argentina: preliminary results from the PASADO-ICDP record

    NASA Astrophysics Data System (ADS)

    Lise-Pronovost, A.; St-Onge, G.; Gogorza, C. G.; Haberzettl, T.; PASADO Team

    2010-12-01

    In the framework of the International Continental scientific Drilling Program (ICDP), the Potrok Aike maar lake Sediment Archive Drilling prOject (PASADO) team drilled Laguna Potrok Aike (52°S, 70°W) in southern Argentina during austral spring 2008. A composite sedimentary sequence of 106 meters from the center of the lake was recovered. Here we present a high-resolution rock magnetic study and paleomagnetic reconstruction for the uppermost 50 m of the PASADO-ICDP composite profile. The natural remanent magnetization (NRM), the anhysteretic and two isothermal remanent magnetizations (ARM, IRM and SIRM) were measured at 1 cm intervals using a 2G u-channel cryogenic magnetometer. Hysteresis properties were measured at ca. 50 cm intervals using a Princeton Measurements Corporation alternating gradient force magnetometer. Temperature dependence of magnetic susceptibility was measured from 50°C to 700°C using a Bartington furnace and susceptibility meter system for all core catcher samples and low field volumetric magnetic susceptibility (kLF) was measured at 1 cm intervals using a multi sensor core logger (MSCL). Preliminary results indicate that the magnetic assemblage of the uppermost 50 m is dominated by low coercivity minerals such as magnetite with grains ranging from pseudo single to multi domain (PSD to MD). The magnetic assemblage of the uppermost ca. 8 meters is characterized by magnetic grains fining upward, as indicated by grain size ratios (kARM/kLF, MDFARM/MDFIRM, ARM/SIRM) and the coercivity ratio Hcr/Hc. These results are consistent with the mid-Holocene lake level rise at Laguna Potrok Aike inferred from geochemical and elemental proxies. Beyond the currently available chronology (ca. 19 m; 16 000 cal BP) and down to 50 m, magnetic grains are generally coarser and rapidly deposited layers become more numerous, most likely because of stronger winds at the end of the last glacial period. Rapidly deposited layers such as turbidites and reworked tephra

  2. Origin and evolution of the Laguna Potrok Aike maar (Patagonia, Argentina)

    NASA Astrophysics Data System (ADS)

    Gebhardt, A. C.; de Batist, M.; Niessen, F.; Anselmetti, F. S.; Ariztegui, D.; Ohlendorf, C.; Zolitschka, B.

    2009-04-01

    Laguna Potrok Aike, a maar lake in southern-most Patagonia, is located at about 110 m a.s.l. in the Pliocene to late Quaternary Pali Aike Volcanic Field (Santa Cruz, southern Patagonia, Argentina) at about 52°S and 70°W, some 20 km north of the Strait of Magellan and approximately 90 km west of the city of Rio Gallegos. The lake is almost circular and bowl-shaped with a 100 m deep, flat plain in its central part and an approximate diameter of 3.5 km. Steep slopes separate the central plain from the lake shoulder at about 35 m water depth. At present, strong winds permanently mix the entire water column. The closed lake basin contains a sub saline water body and has only episodic inflows with the most important episodic tributary situated on the western shore. Discharge is restricted to major snowmelt events. Laguna Potrok Aike is presently located at the boundary between the Southern Hemispheric Westerlies and the Antarctic Polar Front. The sedimentary regime is thus influenced by climatic and hydrologic conditions related to the Antarctic Circumpolar Current, the Southern Hemispheric Westerlies and sporadic outbreaks of Antarctic polar air masses. Previous studies demonstrated that closed lakes in southern South America are sensitive to variations in the evaporation/precipitation ratio and have experienced drastic lake level changes in the past causing for example the desiccation of the 75 m deep Lago Cardiel during the Late Glacial. Multiproxy environmental reconstruction of the last 16 ka documents that Laguna Potrok Aike is highly sensitive to climate change. Based on an Ar/Ar age determination, the phreatomagmatic tephra that is assumed to relate to the Potrok Aike maar eruption was formed around 770 ka. Thus Laguna Potrok Aike sediments contain almost 0.8 million years of climate history spanning several past glacial-interglacial cycles making it a unique archive for non-tropical and non-polar regions of the Southern Hemisphere. In particular, variations of

  3. Origin and evolution of the Laguna Potrok Aike maar (Patagonia, Argentina)

    NASA Astrophysics Data System (ADS)

    Gebhardt, A. C.; de Batist, M.; Niessen, F.; Anselmetti, F. S.; Ariztegui, D.; Ohlendorf, C.; Zolitschka, B.

    2009-04-01

    Laguna Potrok Aike, a maar lake in southern-most Patagonia, is located at about 110 m a.s.l. in the Pliocene to late Quaternary Pali Aike Volcanic Field (Santa Cruz, southern Patagonia, Argentina) at about 52°S and 70°W, some 20 km north of the Strait of Magellan and approximately 90 km west of the city of Rio Gallegos. The lake is almost circular and bowl-shaped with a 100 m deep, flat plain in its central part and an approximate diameter of 3.5 km. Steep slopes separate the central plain from the lake shoulder at about 35 m water depth. At present, strong winds permanently mix the entire water column. The closed lake basin contains a sub saline water body and has only episodic inflows with the most important episodic tributary situated on the western shore. Discharge is restricted to major snowmelt events. Laguna Potrok Aike is presently located at the boundary between the Southern Hemispheric Westerlies and the Antarctic Polar Front. The sedimentary regime is thus influenced by climatic and hydrologic conditions related to the Antarctic Circumpolar Current, the Southern Hemispheric Westerlies and sporadic outbreaks of Antarctic polar air masses. Previous studies demonstrated that closed lakes in southern South America are sensitive to variations in the evaporation/precipitation ratio and have experienced drastic lake level changes in the past causing for example the desiccation of the 75 m deep Lago Cardiel during the Late Glacial. Multiproxy environmental reconstruction of the last 16 ka documents that Laguna Potrok Aike is highly sensitive to climate change. Based on an Ar/Ar age determination, the phreatomagmatic tephra that is assumed to relate to the Potrok Aike maar eruption was formed around 770 ka. Thus Laguna Potrok Aike sediments contain almost 0.8 million years of climate history spanning several past glacial-interglacial cycles making it a unique archive for non-tropical and non-polar regions of the Southern Hemisphere. In particular, variations of

  4. Origin and evolution of the Laguna Potrok Aike maar (Southern Patagonia, Argentina) as revealed by seismic data

    NASA Astrophysics Data System (ADS)

    Gebhardt, C.; de Batist, M. A.; Niessen, F.; Anselmetti, F.; Ariztegui, D.; Haberzettl, T.; Ohlendorf, C.; Zolitschka, B.

    2009-12-01

    Seismic reflection and refraction data provide insights into the sedimentary infill and the underlying volcanic structure of Laguna Potrok Aike, a maar lake situated in the Pali Aike Volcanic Field, Southern Patagonia. The lake has a diameter of ~3.5 km, a maximum water depth of ~100 m and a presumed age of ~770 ka. Its sedimentary regime is influenced by climatic and hydrologic conditions related to the Antarctic Circumpolar Current, the Southern Hemispheric Westerlies and sporadic outbreaks of Antarctic polar air masses. Multiproxy environmental reconstructions of the last 16 ka document that this terminal lake is highly sensitive to climate change. Laguna Potrok Aike has recently become a major focus of the International Continental Scientific Drilling Program and was drilled down to 100 m below lake floor in late 2008 within the PASADO project. The sediments are likely to contain a continental record spanning the last ca. 80 kyrs unique in the South American realm. Seismic reflection data show relatively undisturbed, stratified lacustrine sediments at least in the upper ~100 m of the sedimentary infill but are obscured possibly by gas and/or coarser material in larger areas. A model calculated from seismic refraction data reveals a funnel-shaped structure embedded in the sandstone rocks of the surrounding Santa Cruz Formation. This funnel structure is filled by lacustrine sediments of up to 370 m in thickness. These can be separated into two distinct subunits with low acoustic velocities of 1500-1800 m s-1 in the upper subunit pointing at unconsolidated lacustrine muds, and enhanced velocities of 2000-2350 m s-1 in the lower subunit. Below these lacustrine sediments, a unit of probably volcanoclastic origin is observed (>2400 m s-1). This sedimentary succession is well comparable to other well-studied sequences (e.g. Messel and Baruth maars, Germany), confirming phreatomagmatic maar explosions as the origin of Laguna Potrok Aike.

  5. Investigating the deep cool lacustrine biosphere: Lake Potrok Aike, Patagonia, Argentina

    NASA Astrophysics Data System (ADS)

    Vuillemin, A.; Ariztegui, D.; Pawlowski, J.; Templer, S. P.

    2009-12-01

    Microbial activity on recent sediments is fully recognized as a major player in lithification processes. These omnipresent organisms have the capacity of catalyzing and enhancing diagenetic reactions even in extreme environments from the very surface of the sediments to as deep as 4.5 km below the water column. Living bacterial communities have been tracked down into deep sediments and even into the deeper basaltic sub-seafloors. Although the distribution and diversity of microbes in marine sediments through depth have been studied for some years already, there is a lack of these investigations in the lacustrine realm. Furthermore, geomicrobiology studies in modern lakes allow taking a closer look into early diagenetic processes linked to microbial activity in subrecent sediments. The foci of most of these studies, however, have been either very shallow sediments and/or the water column. More than 500 meters of sedimentary cores were retrieved from Lake Portok Aike, a crater lake located in Southern Patagonia within the framework of the ICDP-sponsored PASADO project (Potrok Aike Maar Lake Sediment Archive Drilling Project). A 100 meters long core was dedicated to geomicrobiology sampling, allowing the inspection of undisturbed deep lacustrine sediments. Special windows were cut in the liners for direct sampling under the most sterile conditions possible immediately after core recovery. In situ ATP measurements are used as indication of living organisms within the sediments. Various samples were chemically fixed and/or frozen for methane determination, bacterial cell counting, DGGE (molecular fingerprinting technique) and cell cultivation. In situ ATP data reveal a constant low microbial activity below 40 m sediment depth whereas three main peaks appear at 37, 10 and 5 meters respectively. Studying the microbial community based on 16S rDNA, we identified a broad, but conserved diversity pattern in the older sediments. In contrast, the diversity seems to decrease and

  6. Origin and age of the Lake Nyos maar, Cameroon

    USGS Publications Warehouse

    Lockwood, J.P.; Rubin, M.

    1989-01-01

    Lake Nyos occupies a young maar crater in the Precambrian granitic terrane of northwest Cameroon. The lake is partly surrounded by poorly consolidated, ultramafic nodule-bearing pyroclastic surge deposits that were explosively ejected from the Nyos crater at the time of its formation. Radiocarbon dates show that the maar probably formed about 400 years ago. Field evidence suggests that carbon dioxide could have been the principal volatile involved in the formation of the Nyos maar, and that the role of water may have been minor. The formation of the Nyos maar was preceded by a brief period of effusive basaltic volcanism, but the maar itself may have largely formed by cold, 'dry' explosive processes. Carbon dioxide may still be trapped interstitially in a diatreme inferred to underlie Lake Nyos; its gradual release into the waters of Lake Nyos may have set the stage for the tragic gas-release event of August 21, 1986. Only young maar lakes such as Nyos may pose a danger of future lethal gas releases. ?? 1989.

  7. Magnitude, geomorphologic response and climate links of lake level oscillations at Laguna Potrok Aike, Patagonian steppe (Argentina)

    NASA Astrophysics Data System (ADS)

    PASADO science Team Kliem, P.; Buylaert, J. P.; Hahn, A.; Mayr, C.; Murray, A. S.; Ohlendorf, C.; Veres, D.; Wastegård, S.; Zolitschka, B.

    2013-07-01

    Laguna Potrok Aike is a large maar lake located in the semiarid steppe of southern Patagonia known for its Lateglacial and Holocene lake level fluctuations. Based on sedimentary, seismic and geomorphological evidences, the lake level curve is updated and extended into the Last Glacial period and the geomorphological development of the lake basin and its catchment area is interpreted.Abrasion and lake level oscillations since at least ˜50 ka caused concentric erosion of the surrounding soft rocks of the Miocene Santa Cruz Formation and expanded the basin diameter by approximately 1 km. A high lake level and overflow conditions of the lake were dated by luminescence methods and tephra correlation to the early Lateglacial as well as to ˜45 ka. The lowest lake level of record occurred during the mid-Holocene. A further lake level drop was probably prevented by groundwater supply. This low lake level eroded a distinct terrace into lacustrine sediments. Collapse of these terraces probably caused mass movement deposits in the profundal zone of the lake. After the mid-Holocene lake level low stand a general and successive transgression occurred until the Little Ice Age maximum; i.e. ca 40 m above the local groundwater table. Frequent lake level oscillations caused deflation of emerged terraces only along the eastern shoreline due to prevailing westerly winds. Preservation of eolian deposits might be linked to relatively moist climate conditions during the past 2.5 ka.Precisely dated lake level reconstructions in the rain-shadow of the Andes document high Last Glacial and low Holocene lake levels that could suggest increased precipitation during the Last Glacial period. As permafrost in semiarid Patagonia is documented and dated to the Last Glacial period we argue that the frozen ground might have increased surficial runoff from the catchment and thus influenced the water balance of the lake. This is important for investigating the glacial to Holocene latitudinal shift

  8. Magnitude, geomorphologic response and climate links of lake level oscillations at Laguna Potrok Aike, Patagonian steppe (Argentina)

    NASA Astrophysics Data System (ADS)

    Kliem, P.; Buylaert, J. P.; Hahn, A.; Mayr, C.; Murray, A. S.; Ohlendorf, C.; Veres, D.; Wastegård, S.; Zolitschka, B.; The Pasado Science Team

    2013-07-01

    Laguna Potrok Aike is a large maar lake located in the semiarid steppe of southern Patagonia known for its Lateglacial and Holocene lake level fluctuations. Based on sedimentary, seismic and geomorphological evidences, the lake level curve is updated and extended into the Last Glacial period and the geomorphological development of the lake basin and its catchment area is interpreted. Abrasion and lake level oscillations since at least ˜50 ka caused concentric erosion of the surrounding soft rocks of the Miocene Santa Cruz Formation and expanded the basin diameter by approximately 1 km. A high lake level and overflow conditions of the lake were dated by luminescence methods and tephra correlation to the early Lateglacial as well as to ˜45 ka. The lowest lake level of record occurred during the mid-Holocene. A further lake level drop was probably prevented by groundwater supply. This low lake level eroded a distinct terrace into lacustrine sediments. Collapse of these terraces probably caused mass movement deposits in the profundal zone of the lake. After the mid-Holocene lake level low stand a general and successive transgression occurred until the Little Ice Age maximum; i.e. ca 40 m above the local groundwater table. Frequent lake level oscillations caused deflation of emerged terraces only along the eastern shoreline due to prevailing westerly winds. Preservation of eolian deposits might be linked to relatively moist climate conditions during the past 2.5 ka. Precisely dated lake level reconstructions in the rain-shadow of the Andes document high Last Glacial and low Holocene lake levels that could suggest increased precipitation during the Last Glacial period. As permafrost in semiarid Patagonia is documented and dated to the Last Glacial period we argue that the frozen ground might have increased surficial runoff from the catchment and thus influenced the water balance of the lake. This is important for investigating the glacial to Holocene latitudinal shift

  9. Multi-proxy dating of Holocene maar lakes and Pleistocene dry maar sediments in the Eifel, Germany

    NASA Astrophysics Data System (ADS)

    Sirocko, Frank; Dietrich, Stephan; Veres, Daniel; Grootes, Pieter M.; Schaber-Mohr, Katja; Seelos, Klemens; Nadeau, Marie-Josée; Kromer, Bernd; Rothacker, Leo; Röhner, Marieke; Krbetschek, Matthias; Appleby, Peter; Hambach, Ulrich; Rolf, Christian; Sudo, Masafumi; Grim, Stephanie

    2013-02-01

    During the last twelve years the ELSA Project (Eifel Laminated Sediment Archive) at Mainz University has drilled a total of about 52 cores from 27 maar lakes and filled-in maar basins in the Eifel/Germany. Dating has been completed for the Holocene cores using 6 different methods (210Pb and 137Cs activities, palynostratigraphy, event markers, varve counting, 14C). In general, the different methods consistently complement one another within error margins. Event correlation was used for relating typical lithological changes with historically known events such as the two major Holocene flood events at 1342 AD and ca 800 BC. Dating of MIS2-MIS3 core sections is based on greyscale tuning, radiocarbon and OSL dating, magnetostratigraphy and tephrochronology. The lithological changes in the sediment cores demonstrate a sequence of events similar to the North Atlantic rapid climate variability of the Last Glacial Cycle. The warmest of the MIS3 interstadials was GI14, when a forest with abundant spruce covered the Eifel area from 55 to 48 ka BP, i.e. during a time when also other climate archives in Europe suggested very warm conditions. The forest of this "Early Stage 3 warm phase" developed subsequently into a steppe with scattered birch and pine, and finally into a glacial desert at around 25 ka BP. Evidence for Mono Lake and Laschamp geomagnetic excursions is found in two long cores. Several large eruptions during Middle and Late Pleistocene (Ulmener Maar - 11,000 varve years BP, Laacher See - 12,900 varve years BP, Mosenberg volcanoes/Meerfelder Maar 41-45 cal ka BP, Dümpel Maar 116 ka BP, Glees Maar - 151 ka BP) produced distinct ash-layers crucial for inter-core and inter-site correlations. The oldest investigated maar of the Eifel is 40Ar/39Ar dated to the time older than 520 ka BP.

  10. Holocene flood stack from three Eifel maar lakes

    NASA Astrophysics Data System (ADS)

    Brunck, Heiko; Sirocko, Frank

    2015-04-01

    Lacustrine sediments are very sensitive to natural and anthropogenically enviromental changes. Thus, lake sediments are excellent climate archives and can be used for reconstructions of past precipitation and flood events. However, we extend our flood record for MIS 2/3 to the entire Holocene up to recent years to get a complete flood stack for the last 60 000 years. The present study reconstructs paleo floods from event layers in the sediment, of Schalkenmehren Maar (SM3), Ulmen Maar (UM1) and Holzmaar (HM1) combined with recent gauge time-series. All three maar lakes has an inflow by a local stream. Accordingly the sedimentation rate is directly linked to runoff activity and the bioturbation was low so that event layers become visible, but varves are only preserved in lake Holzmaar. The maar sites are situated in the Eifel near to the town of Daun and were drilled in the ELSA (Eifel Laminated Sediment archive) project. The Eifel area is well suited to approximate Central European weather, because modern water level gauge data from Eifel rivers correlate with respective data from the Rhine (Wernli and Pfahl, 2009). Combined sedimentological, paleobotanical and geochemical data received from SM3, UM1 and HM1 builds the foundation of the 14C based chronology. The synchronisation of the record is controlled by tephra time markers and pollen. Both are used to align the main cores of the ELSA project and construct an integrated age model for the last 220 000 years [b2k] (Förster and Sirocko, 2014). For the extension of our MIS 2/3 flood stack we used the Laacher See Tephra (10 900 BC) as marker for the correlation with the Holocene cores. To study the flood events in detail, 10 cm long thin sections were used to distinguish flood layers from distal turbidites. Turbidites have a continuous grain size gradation; the grains size profile of flood events is in contrast characterized by several grain size maxima over the entire layer thickness. A flood event over several

  11. Varved Sediments of Maar Lake Ranu Klindungan, East Java

    NASA Astrophysics Data System (ADS)

    Pirrung, M.; Buechel, G.; Scharf, B.; Treutler, H.; Witkowski, A.

    2001-05-01

    Ranu Klindungan (7.725° S, 113.02° E, 10 m a.s.l.) is a maar lake 1550 m in diameter in the coastal lowlands at the northern foot of the Tengger Caldera in East Java, Indonesia. The southern half of the lake is surrounded by a tephra wall up to 50 m high, whereas towards the north topography rises only some meters above lake level. Fresh maar tephra consist of ash and lapilli layers with cauliflower-bombs and -lapilli. The lake has no permanent inflow but 4 effluents with a total discharge of 450 L/s which underlines the importance of groundwater access on subaquatic slopes. Echolot profiles reveal a flat central area 750 m in diameter at 126 m depth and on the steep slopes several slides are visible. The eutrophic, oligomictic lake has an epilimnion in the uppermost 5 m and an anoxic hypolimnion below 20 m. Profundal sediments are composed of diatom gyttja with frequent turbidites. In thin sections, light-dark alternation in slack water deposits reflects 1-6 mm thick cycles that have a lower, light biogenous part of intact planktonic diatom valves with an upwards increasing amount of carbonate crystals, ending with an almost pure carbonate layer, and an upper, dark terrigenous part of mineral grains and plant debris with some carbonate crystals and fragmented littoral diatom valves. These cycles are interpreted as annual varves: layers of diatoms and carbonate crystals are sedimented during the dry season June-October and terrigenous layers during the monsoon-rain season November-May. This is confirmed by 210Pb-excess ages determined after the constant initial concentration method. Distal turbidites contribute about half of the sediment thickness. This points to turbidity currents as major relief-forming process. Magnetic volume specific susceptibility is very high (maximum 1.4*10-2 SI) and clearly bound to fresh terrigenous material in turbidites. Variation of sedimentation rates and terrigenous input during the last 40 years will be discussed.

  12. The origin of a large (> 3 km) maar volcano by coalescence of multiple shallow craters: Lake Purrumbete maar, southeastern Australia

    NASA Astrophysics Data System (ADS)

    Jordan, S. C.; Cas, R. A. F.; Hayman, P. C.

    2013-03-01

    Lake Purrumbete maar is located in the intraplate, monogenetic Newer Volcanics Province in southeastern Australia. The extremely large crater of 3000 m in diameter formed on an intersection of two fault lines and comprises at least three coalesced vents. The evolution of these vents is controlled by the interaction of the tectonic setting and the properties of both hard and soft rock aquifers. Lithics in the maar deposits originate from country rock formations less than 300 m deep, indicating that the large size of the crater cannot only be the result of the downwards migration of the explosion foci in a single vent. Vertical crater walls and primary inward dipping beds evidence that the original size of the crater has been largely preserved. Detailed mapping of the facies distributions, the direction of transport of base surges and pyroclastic flows, and the distribution of ballistic block fields, form the basis for the reconstruction of the complex eruption history,which is characterised by alternations of the eruption style between relatively dry and wet phreatomagmatic conditions, and migration of the vent location along tectonic structures. Three temporally separated eruption phases are recognised, each starting at the same crater located directly at the intersection of two local fault lines. Activity then moved quickly to different locations. A significant volcanic hiatus between two of the three phases shows that the magmatic system was reactivated. The enlargement of especially the main crater by both lateral and vertical growth led to the interception of the individual craters and the formation of the large circular crater. Lake Purrumbete maar is an excellent example of how complicated the evolution of large, seemingly simple, circular maar volcanoes can be, and raises the question if these systems are actually monogenetic.

  13. Volcanology, history and myths of the Lake Albano maar (Colli Albani volcano, Italy)

    NASA Astrophysics Data System (ADS)

    De Benedetti, A. A.; Funiciello, R.; Giordano, G.; Diano, G.; Caprilli, E.; Paterne, M.

    2008-10-01

    The polygenetic Albano maar is the most recent centre of the Colli Albani volcano, located just few kilometres to the south-east of Roma. Presently the maar hosts a 167.5 m deep crater lake, the deepest in Europe. The maar is to be considered quiescent, as phreatic activity is documented throughout the Holocene. This paper illustrates the close relationships between the activity of the maar and the history of settlement in the Roman region as recorded in the geology, archaeology, history and legends of the area. Severe fluctuations of the groundwater table and catastrophic overflows of the Lake Albano from the maar rim had occurred prior to and after the early prehistoric settlements dated in the maar area at the Eneolithic times (ca. III millennium B.C.). Repeated lahars occurred along the northwestern slope of the maar filling in the paleodrainage network and forming a vast plain. Paleohydraulic analyses on fluvial and lahar deposits originated from the Holocene phreatic activity of the Albano maar indicate sediment-water flows in excess of hundreds of cubic metres per second. Absolute age determinations of the paleosoil underlying one of the most recent deposits of the lahar succession at 5800 ± 100 yr B.P. ( 14C CAL) are in perfect agreement with the age of the overlying Eneolithic age settlements. The last catastrophic overflow is described in the Roman literature as a consequence of the anger of Poseidon against the Romans in 398 B.C. for their war against the Etruscans. In 394 B.C. the Romans decided to prevent the repetition of such events by the excavation through the maar crater wall of a 1.5 km long drain tunnel, which is still operational, keeping the lake 70 m below the lowest point of the maar rim. This tunnel drain may be regarded as the first prevention device for volcanic hazard in history and shows an unprecedented development of the engineering technology under the pressure of hazard perception. The surprising and still largely unknown results

  14. Multidisciplinary characterisation of sedimentary processes in a recent maar lake (Lake Pavin, French Massif Central) and implication for natural hazards

    NASA Astrophysics Data System (ADS)

    Chapron, E.; Albéric, P.; Jézéquel, D.; Versteeg, W.; Bourdier, J.-L.; Sitbon, J.

    2010-09-01

    Sedimentation processes occurring in the most recent maar lake of the French Massif Central (Lake Pavin) are documented for the first time based on high resolution seismic reflection and multibeam bathymetric surveys and by piston coring and radiocarbon dating on a sediment depocentre developed on a narrow sub aquatic plateau. This new data set confirms the mid Holocene age of maar lake Pavin formation at 6970±60 yrs cal BP and highlights a wide range of gravity reworking phenomena affecting the basin. In particular, a slump deposit dated between AD 580-640 remoulded both mid-Holocene lacustrine sediments, terrestrial plant debris and some volcanic material from the northern crater inner walls. Between AD 1200 and AD 1300, a large slide scar mapped at 50 m depth also affected the southern edge of the sub aquatic plateau, suggesting that these gas-rich biogenic sediments (laminated diatomite) are poorly stable. Although several triggering mechanisms can be proposed for these prehistoric sub-aquatic mass wasting deposits in Lake Pavin, we argue that such large remobilisation of gas-rich sediments may affect the gas stability in deep waters of meromictic maar lakes. This study highlights the need to further document mass wasting processes in maar lakes and their impacts on the generation of waves, favouring the development of dangerous (and potentially deadly) limnic eruptions.

  15. Climatic change evidence and lacustrine waves from maar lakes, Germany

    SciTech Connect

    Zolitschka, B.

    1992-01-01

    Annually laminated, non-glacial lake sediments from Lake Holzmaar (Eifel, western Germany) were investigated using large {open_quotes}Merkt{close_quotes} thin sections. The absolute age of varve intervals with variations in thickness and composition were correlated to climatic changes recorded by glacier fluctuations in the Alps. Back to 8800 years VT (vuarve time = varve years before 1950) glacier advances coincide with sedimentation rate minima; prior to 8800 years VT they coincide with sedimentation rate maxima. The early and middle Holocene sediments suggest a periodicity of about 1000 years for cold/warm cycles. A sequence of 512 varve-thickness measurements was subjected to spectral analysis. These provide apparent evidence for a 11-year sun-spot cycle. 30 refs., 3 fig.

  16. The potential for catastrophic dam failure at Lake Nyos maar, Cameroon

    NASA Astrophysics Data System (ADS)

    Lockwood, J. P.; Costa, J. E.; Tuttle, M. L.; Nni, J.; Tebor, S. G.

    1988-09-01

    The upper 40 m of Lake Nyos is bounded on the north by a narrow dam of poorly consolidated pyroclastic rocks, emplaced during the eruptive formation of the Lake Nyos maar a few hundred years ago. This 50-m-wide natural dam is structurally weak and is being eroded at an uncertain, but geologically alarming, rate. The eventual failure of the dam could cause a major flood (estimated peak discharge, 17000 m3/s) that would have a tragic impact on downstream areas as far as Nigeria, 108 km away. This serious hazard could be eliminated by lowering the lake level, either by controlled removal of the dam or by construction of a 680-m-long drainage tunnel about 65 m below the present lake surface. Either strategy would also lessen the lethal effects of future massive CO2 gas releases, such as the one that occurred in August 1986.

  17. The potential for catastrophic dam failure at Lake Nyos maar, Cameroon

    USGS Publications Warehouse

    Lockwood, J.P.; Costa, J.E.; Tuttle, M.L.; Nni, J.; Tebor, S.G.

    1988-01-01

    The upper 40 m of Lake Nyos is bounded on the north by a narrow dam of poorly consolidated pyroclastic rocks, emplaced during the eruptive formation of the Lake Nyos maar a few hundred years ago. This 50-m-wide natural dam is structurally weak and is being eroded at an uncertain, but geologically alarming, rate. The eventual failure of the dam could cause a major flood (estimated peak discharge, 17000 m3/s) that would have a tragic impact on downstream areas as far as Nigeria, 108 km away. This serious hazard could be eliminated by lowering the lake level, either by controlled removal of the dam or by construction of a 680-m-long drainage tunnel about 65 m below the present lake surface. Either strategy would also lessen the lethal effects of future massive CO2 gas releases, such as the one that occurred in August 1986. ?? 1988 Springer-Verlag.

  18. Climate history of the Southern Hemisphere Westerlies belt during the last glacial-interglacial transition revealed from lake water oxygen isotope reconstruction of Laguna Potrok Aike (52° S, Argentina)

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Lücke, A.; Wissel, H.; Mayr, C.; Enters, D.; Kim, K. Ja; Ohlendorf, C.; Schäbitz, F.; Zolitschka, B.

    2014-12-01

    The Southern Hemisphere Westerlies (SHW) play a crucial role in large-scale ocean circulation and global carbon cycling. Accordingly, the reconstruction of how the latitudinal position and intensity of the SHW belt changed during the last glacial termination is essential for understanding global climatic fluctuations. The southernmost part of the South American continent is the only continental mass intersecting a large part of the SHW belt. However, due to the scarcity of suitable palaeoclimate archives continuous proxy records back to the last glacial are rare in southern Patagonia. Here, we show an oxygen isotope record from cellulose and purified bulk organic matter of submerged aquatic moss shoots from Laguna Potrok Aike (52° S, 70° W), a deep maar lake located in semi-arid, extra-Andean Patagonia, covering the last glacial-interglacial transition (26 000 to 8500 cal BP). Based on the highly significant correlation between oxygen isotope values of modern aquatic mosses and their host waters and abundant well-preserved moss remains in the sediment record a high-resolution reconstruction of the lake water oxygen isotope (δ18Olw-corr) composition is presented. The reconstructed δ18Olw-corr values for the last glacial are ca. 3‰ lower than modern values, which can best be explained by generally cooler air temperatures and changes in the moisture source area, together with the occurrence of permafrost leading to a prolonged lake water residence time. Thus, the overall glacial δ18Olw-corr level until 21 000 cal BP is consistent with a scenario of weakened or absent SHW at 52° S compared to the present. During the last deglaciation, reconstructed δ18Olw-corr values reveal a significant two-step rise describing the detailed response of the lake's hydrological balance to this fundamental climatic shift. Rapid warming is seen as the cause of the first rise of ca. 2&permil, in δ18Olw-corr during the first two millennia of deglaciation (17 600 to 15 600 cal BP

  19. Subsurface structure of a large basaltic maar volcano examined using geologically constrained potential field modelling, Lake Purrumbete Maar, Newer Volcanics Province, southeastern Australia

    NASA Astrophysics Data System (ADS)

    van den Hove, Jackson C.; Ailleres, Laurent; Betts, Peter G.; Cas, Ray A. F.

    2015-10-01

    Lake Purrumbete Maar (LPM) is situated in the Late Cenozoic intraplate, basaltic Newer Volcanics Province, southeastern Australia. It is one of the largest maar volcanoes in the world with a near circular crater that is up to 2800 m in diameter containing a 45 m deep lake. Gellibrand Marl accidental lithics, which occurs to a maximum depth of 250 m below LPM, represent the deepest excavated host rock unit present in the volcanic succession. Irregular clast shapes and peperitic textures observed in marl lithics suggest the host rock was poorly consolidated during the eruption. High-resolution lake- and land-based gravity and magnetic data were collected to conduct forward and inverse modelling of the subsurface architecture of the maar. This is done to test the assumption, based on lithics, that the diatreme is limited to 250 m depth and identify the reasons behind LPM's large size. The collection of gravity data presented a unique challenge due to the nature of measuring small changes in gravitational forces (< 1 mGal) associated with the maar, on an inherently unstable water body. The magnetic anomaly over LPM shows several irregularly shaped high magnetic anomalies. Four 2.5-D forward models transecting LPM were constructed based on the observed potential field data. Five coalesced vents forming an undulating shallow bowl-shaped diatreme contained within the Gellibrand Marl (240 m depth) were modelled to satisfy the observed magnetic response, while a large sill body at 350 m depth is modelled to satisfy the observed gravity response. A second forward model, completed to satisfy the observed magnetic response, also includes coalesced shallow bowl-shaped diatremes within the Gellibrand Maar, which then taper down to become thin and steep sided and extend down to the basement (1,050 m depth). Three-dimensional property and geometry inversions suggest the diatreme most likely extends to a greater depth than the initial maximum depth of 240 m. This suggests the

  20. Biogeochemical Response to the Holocence Monsoon Climate in a Maar Lake, south China

    NASA Astrophysics Data System (ADS)

    Jia, G.; Bai, Y.; Xie, L.; Wei, G.; Yang, X.; Chu, G.

    2013-12-01

    A continuous, high-resolution record from a lacustrine sediment core (Maar Lake Huguangyan) at the southern tropical China is provided in this presentation. Multi-proxies including TOC, TN, δ13CTOC, δ15N, leaf wax n-alkane δ13C (δ13Calkane) and magnetic susceptibility are used to reconstruct the paleoenvironment and monsoon variations in the Holocene. Record of δ13Calkane suggested higher contribution of C4 plants in the terrestrial ecosystem during the earliest Holocene (11.2-9.5 kaBP) and latest Holocene (after 1.8 kaBP). Variation of δ13CTOC paralleled that of δ13Calkane during the two intervals, but terrestrial contribution to TOC is likely insignificant due to relatively low TOC/TN ratios (<12). Between the two intervals was a stable, long-term C3-predominated ecosystem, but δ13CTOC show large variations (>6‰), exhibiting a decreasing trend from 7.2 to 2.0 kaBP. Therefore, variations of δ13CTOC are interpreted as (i) changes in the terrestrial dissolved carbon supply that had been imprinted with regional C3/C4 variations during the earliest and latest Holocene, respectively, when the lake water would be shallower, and (ii) the dominant processes in the lake, i.e. epilimnetic primary productivity, between 9.5 and 2.0 kaBP., when the lake water would be deeper. During the deeper water period, highest TOC and δ13CTOC occurred in the first half interval (9.5-6 kaBP) with markedly low δ15N values (0.4-2.2‰), suggesting a deep, warm, and stratified water column favoring N2 fixation due, perhaps, to the declining nitrogen availability resulting from terrestrial C and N sequestration. The second half interval (6-2 kaBP) was characterized by decreasing TOC and δ13CTOC and relatively stable δ15N (4.1×0.5‰), indicating lowering lake water and/or the wind-induced lake overturn that is unfavorable for N2 fixation. The above paleolimnetic records enable us to deduce summer monsoon-induced effective moisture changes in the Holocene in the tropical China

  1. Extreme events in the sedimentary record of maar Lake Pavin: Implications for natural hazards assessment in the French Massif Central

    NASA Astrophysics Data System (ADS)

    Chassiot, Léo; Chapron, Emmanuel; Di Giovanni, Christian; Albéric, Patrick; Lajeunesse, Patrick; Lehours, Anne-Catherine; Meybeck, Michel

    2016-06-01

    A set of sedimentary cores, high resolution swath bathymetry and subbottom profiler data provides new insights on sedimentary processes in meromictic maar Lake Pavin, France. Three sedimentary environments (i.e., littoral, plateau and basin) have been identified in the lake from sediment composition using bulk organic geochemistry and the analysis of hydroacoustic images. Various forms of rapidly deposited layers (RDLs) have been identified and radiocarbon dated. An up to date stratigraphy of sedimentary events matching coeval RDLs across the lake is presented and illustrates a wide range of natural hazards linked to Lake Pavin during the last 2000 years. In AD 600, a sudden lake outburst triggered a slump deposit along with a 9 m lake-level drop that drove shifts in sedimentary organic matter composition. Outside the lake, outburst flood deposits have been described downstream and provide sedimentary evidence for this event. The lake-level drop also favored the generation of gravity reworking processes, as shown by (1) a regional earthquake-triggered large slope failure on the plateau connected to a mass-wasting deposit in the basin dated to AD 1300, and (2) a succession of turbidites in AD 1825 and AD 1860 contemporaneous to two historic earthquakes, suggesting that this lake is sensitive to earthquakes with a minimum epicentral intensity of V. Finally, past observations of lake water color changes in AD 1783 and AD 1936, similar to reports in other meromictic lakes, match iron-rich deposits identified in maar lake sediments and suggest that Lake Pavin could have undergone limnic eruptions.

  2. The Albano Maar Lake high resolution bathymetry and dissolved CO 2 budget (Colli Albani volcano, Italy): Constrains to hazard evaluation

    NASA Astrophysics Data System (ADS)

    Anzidei, Marco; Carapezza, Maria Luisa; Esposito, Alessandra; Giordano, Guido; Lelli, Matteo; Tarchini, Luca

    2008-04-01

    The Albano Lake is the deepest volcanic lake in Italy (- 167 m) and fills the youngest maar of the quiescent Colli Albani volcano. The lake has undergone significant level changes and lahar generating overflows occurred about 5800 yrs B.P. and likely in 398 b.C., when Romans excavated a tunnel drain through the maar wall. Hazardous lake rollovers and CO 2 release are still possible because the Albano volcano shows active ground deformation, gas emission and periodic seismic swarms. On November 2005, the first high resolution bathymetric survey of the Albano Lake was performed. Here we present the results provided by a Digital Elevation Model and 2-D and 3-D images of the crater lake floor, which is made by coalescent and partly overlapping craters and wide flat surfaces separated by some evident scarps. Submerged shorelines are identified at depths between - 20 m and - 41 m and indicate the occurrence of significant lake level changes, likely between 7.1 and 4.1 ka. The current lake volume is ~ 447.5 × 10 6 m 3 and the total quantity of dissolved CO 2 is 6850 t estimated by chemical analyses of samples collected on May 2006. A decrease of nearly one order of magnitude of the CO 2 dissolved in the lake water below - 120 m, observed from December 1997 to May 2006 (from 4190 to 465 t respectively), has been attributed to lake water overturn. The observed oscillations of the dissolved CO 2 concentrations justify the efforts of monitoring the chemical and physical characteristics of the lake. At present the quantity of dissolved CO 2 is very far from saturation and Nyos-type events cannot presently occur.

  3. Origin of temporal - compositional variations during the eruption of Lake Purrumbete Maar, Newer Volcanics Province, southeastern Australia

    NASA Astrophysics Data System (ADS)

    Jordan, S. C.; Jowitt, S. M.; Cas, R. A. F.

    2015-01-01

    The Pleistocene Lake Purrumbete maar eruption sequence of the Newer Volcanics Province of southeastern Australia records stratigraphic, temporal and geochemical variations that cannot be explained by crustal processes, such as fractional crystallisation and crustal contamination. Samples from the Lake Purrumbete maar have distinct trace element trends that correlate with stratigraphic height, with decreasing incompatible element concentrations from the bottom of the sequence to the top, indicating that the most enriched melts were ejected during the earliest eruption stages, with the least enriched melts erupted in the final stages. Variations in rare earth element ratios indicate that these melts were formed by dynamic melting of garnet lherzolite mantle material, consistent with other volcanic centres within the basaltic cones subprovince of the Newer Volcanics Province. The geochemistry of the erupted units at Lake Purrumbete also record minor differentiation of the melts by olivine fractionation, although these processes alone cannot explain the observed geochemical variations in the eruption sequence. Further differentiation of the melts by different processes such as deep clinopyroxene fractionation or assimilation of metasomatised lithosphere may be responsible for the observed geochemical trends at Lake Purrumbete. This shows the complexity of the plumbing system of monogenetic volcanoes, but also shows the opportunities that these volcanoes provide to study these processes in detail, as the geochemical variations that are preserved in this type of volcanism by fast magma ascent through the crust, as evidenced by the presence of fresh mantle xenoliths, predominantly reflect processes that occurred in the mantle rather than in the crust.

  4. High-resolution Late Pleistocene paleomagnetic secular variation record from Laguna Potrok Aike, Southern Patagonia (Argentina): preliminary results from the ICDP-PASADO drilling

    NASA Astrophysics Data System (ADS)

    Lisé-Pronovost, Agathe; St-Onge, Guillaume; Haberzettl, Torsten; Pasado Science Team

    2010-05-01

    High-resolution paleomagnetic reconstructions from sedimentary sequences are scarce in the Southern Hemisphere. Therefore, the millennial- to centennial-scale variability of the geomagnetic field is under-represented in the Southern Hemisphere relative to the Northern Hemisphere and the possible global nature of that variability cannot be assessed. Here we present the first high-resolution Late Pleistocene paleomagnetic secular variation (PSV) reconstruction from the continental archive Laguna Potrok Aike south of 42°S in South America. Laguna Potrok Aike (51°58'S, 70°23'W) is a maar lake located in the Pali Aike Volcanic Field in southern Patagonia (Argentina). Previous studies revealed very high Holocene sedimentation rates (> 100 cm/ka) in the center of the lake. During the austral spring 2008, the multi-national Potrok Aike maar lake Sediment Archive Drilling prOject (PASADO) science team drilled two ~100 m holes under the framework of the International Continental scientific Drilling Program (ICDP). A preliminary Holocene age model based on comparison of magnetic susceptibility data from the PASADO core with the well-dated (radiocarbon- and tephra-based chronology) core located nearby in the center of the lake (PTA03-12) indicates a continuous deposition of ~19 m of lacustrine sediments since the last 16 ka cal. BP. Hysteresis measurements using an alternating gradient force magnetometer indicate a magnetic assemblage dominated by magnetite grains in the pseudo-single domain range. Principal component analysis (PCA) inclination and declination profiles were constructed from the stepwise alternating field demagnetization of the natural remanent magnetization (NRM) measured on u-channels at 1 cm intervals using a 2G Enterprises cryogenic magnetometer. The PCA inclinations vary around the expected geocentric axial dipole (GAD) inclination for the latitude of the coring site and the maximum angular deviation (MAD) values are generally lower than 5°, indicating

  5. Vegetation history in southern Patagonia: first palynological results of the ICDP lake drilling project at Laguna Potrok Aike, Argentina

    NASA Astrophysics Data System (ADS)

    Schäbitz, Frank; Michael, Wille

    2010-05-01

    Laguna Potrok Aike located in southern Argentina is one of the very few locations that are suited to reconstruct the paleoenvironmental and climatic history of southern Patagonia. In the framework of the multinational ICDP deep drilling project PASADO several long sediment cores to a composite depth of more than 100 m were obtained. Here we present first results of pollen analyses from sediment material of the core catcher. Absolute time control is not yet available. Pollen spectra with a spatial resolution of three meters show that Laguna Potrok Aike was always surrounded by Patagonian Steppe vegetation. However, the species composition underwent some marked proportional changes through time. The uppermost pollen spectra show a high contribution of Andean forest and charcoal particles as it can be expected for Holocene times and the ending last glacial. The middle part shows no forest and relatively high amounts of pollen from steppe plants indicating cold and dry full glacial conditions. The lowermost samples are characterized by a significantly different species composition as steppe plants like Asteraceae, Caryophyllaceae, Ericaceae and Ephedra became more frequent. In combination with higher charcoal amounts and an algal species composition comparable to Holocene times we suggest that conditions during the formation of sediments at the base of the record were more humid and/or warmer causing a higher fuel availability for charcoal production compared to full glacial times.

  6. Rock-magnetic signature of precipitation and extreme runoff events in south-eastern Patagonia since 51,200 cal BP from the sediments of Laguna Potrok Aike

    NASA Astrophysics Data System (ADS)

    Lisé-Pronovost, A.; St-Onge, G.; Gogorza, C.; Jouve, G.; Francus, P.; Zolitschka, B.

    2014-08-01

    A 106-m long sediment sequence from the maar lake Laguna Potrok Aike in southern Patagonia was recovered in the framework of the International Continental Scientific Drilling Program (ICDP) Potrok Aike maar lake Sediment Archive Drilling prOject (PASADO). About half of the sedimentary sequence is composed of mass movement deposits (MMDs) and the event-corrected record reaches back to 51,200 cal BP. Here we present a high-resolution rock-magnetic study revealing two sedimentary facies associated with MMDs and characterized by two different types of spurious gyroremanent magnetization (GRM) acquired during static alternating field demagnetization. The first rock-magnetic signature is detected in MMDs composed of reworked sand and tephra material. The signature consists of GRM acquired during demagnetization of the natural remanent magnetization (NRM) and other rock-magnetic properties typical of iron sulfides such as greigite. We interpret these intervals as authigenic formation of iron sulfides in suboxic conditions within the MMD. The second rock-magnetic signature consists of a series of 10 short intervals located on the top of MMDs characterized by GRM acquisition during demagnetization of the isothermal remanent magnetization (IRM). Based on geological, limnological, stratigraphic and climatic evidence these layers are interpreted as reflecting pedogenic hematite and/or goethite brought to the lake by runoff events related to precipitation and permafrost melt. The pedogenic iron minerals mobilized from the catchment most likely settled out of suspension on top of MMDs after a rapid remobilization event. The series of runoff events corresponds to periods of increased lacustrine productivity in Laguna Potrok Aike and are coeval within the limit of the chronology to warm periods of the Last Glacial as recorded in Antarctica, the deglaciation in the mid-latitudes of the Southern Hemisphere and enhanced precipitation during the Early Holocene in southeastern

  7. 40Ar/39Ar laser probe evidence concerning the age and associated hazards of the Lake Nyos Maar, Cameroon

    USGS Publications Warehouse

    Dalrymple, G.B.; Lockwood, J.P.

    1990-01-01

    The waters of Lake Nyos are impounded by a fragile natural dam composed of pyroclastic rocks ejected during the formation of the lake crater (maar). Lateral erosion of this dam has reduced its width from over 500 m to only 45 m. Published whole-rock K-Ar ages of about 100 ka on juvenile basalt from the dam suggests that erosion has been slow and that the dam poses no imminent threat. New apparent 40Ar/39Ar ages of 1.4 to 232 Ma on xenocrystic K-feldspar contained in the basalt show that the xenocrysts, whose source is the 528-Ma crystalline basement, are carriers of inherited radiogenic 40Ar and would cause the whole-rock K-Ar ages to be too old. The best estimate for the age of the maar is provided by a 14C age of 400 ?? 100 yr BP on charcoal from the base of the dam. This young age indicates that the dam is eroding at a relatively rapid rate; its failure, perhaps within a few decades, would result in a major flood and imperil thousands of people living downstream in Cameroon and eastern Nigeria. ?? 1990 Kluwer Academic Publishers.

  8. Origin and transport of CH4 in two maar lakes fed by mantle-derived volatiles (Mt. Vulture volcano, Italy)

    NASA Astrophysics Data System (ADS)

    Caracausi, Antonio; Cosenza, Paolo; Favara, Rocco; Foresta Martin, Luigi; Galli, Nunzio; Grassa, Fausto; Nuccio, Pasquale Mario; Paternoster, Michele; Riccobono, Giuseppe

    2014-05-01

    It has been assessed that lakes contribute 6 to 16% to global CH4 emission in atmosphere. Accumulation of CH4 in the water is strongly dependent on the input of gas and the dynamic of the lake's water. Lakes located on tectonically and volcanically active areas (e.g., Kivu, Nyos) generally contain relevant amount of mantle-derived volatiles. This generated an open debate on the origin of CO2 and CH4 in volcanic lakes because the complex bio-geological cycling of these two gases. This study is a part of larger investigation carried out on two maar lakes (LPM and LGM) formed about 140.000 years ago during the last eruption of Mt. Vulture (Italy). In spite of it generally is considered to be extinct, both lakes are characterized by an active inflow of mantle-derived fluids (Caracausi et al., 2013). Although the two lakes are only 150 m apart, their respective dynamics are different being LPM a meromictic lake, while LGM a monomictic one (Caracausi et al., 2013). The stagnant waters of LPM are enriched in CO2 and CH4 but the total gas pressure is below the hydrostatic pressure, so that the transfer of gas towards the surface doesn't occur via bubbles. Vertical profiles at LPM reveal a marked decrease of the dissolved CH4 content in the shallower layers due to aerated water. The amount of CH4 dissolved in LGM water column shows seasonal variations: in autumn it is comparable to that of LPM at the same depth; in winter CH4 is fully released into atmosphere through overturn of waters. C and H isotopes of CH4 clearly indicate in both lakes an active production both by acetoclastic methanogenesis and by CO2 reduction although with different proportions. Historical reports describe intense episodic releases of gases from both lakes occurred up to about 200 years ago. Caracausi et al. (2013) highlight that these events could be caused by a release of mantle-derived CO2 accumulated in the crust or directly linked to magma degassing. In the present study the knowledge gained

  9. A late quaternary record of eolian silt deposition in a maar lake, St. Michael Island, western Alaska

    USGS Publications Warehouse

    Muhs, D.R.; Ager, T.A.; Been, J.; Bradbury, J.P.; Dean, W.E.

    2003-01-01

    Recent stratigraphic studies in central Alaska have yielded the unexpected finding that there is little evidence for full-glacial (late Wisconsin) loess deposition. Because the loess record of western Alaska is poorly exposed and not well known, we analyzed a core from Zagoskin Lake, a maar lake on St. Michael Island, to determine if a full-glacial eolian record could be found in that region. Particle size and geochemical data indicate that the mineral fraction of the lake sediments is not derived from the local basalt and is probably eolian. Silt deposition took place from at least the latter part of the mid-Wisconsin interstadial period through the Holocene, based on radiocarbon dating. Based on the locations of likely loess sources, eolian silt in western Alaska was probably deflated by northeasterly winds from glaciofluvial sediments. If last-glacial winds that deposited loess were indeed from the northeast, this reconstruction is in conflict with a model-derived reconstruction of paleowinds in Alaska. Mass accumulation rates in Zagoskin Lake were higher during the Pleistocene than during the Holocene. In addition, more eolian sediment is recorded in the lake sediments than as loess on the adjacent landscape. The thinner loess record on land may be due to the sparse, herb tundra vegetation that dominated the landscape in full-glacial time. Herb tundra would have been an inefficient loess trap compared to forest or even shrub tundra due to its low roughness height. The lack of abundant, full-glacial, eolian silt deposition in the loess stratigraphic record of central Alaska may be due, therefore, to a mimimal ability of the landscape to trap loess, rather than a lack of available eolian sediment. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

  10. Microsedimentological investigations in lacustrine sediments from a maar lake: implications for palaeoenvironmental reconstructions

    NASA Astrophysics Data System (ADS)

    Jouve, Guillaume; Francus, Pierre; De Coninck, Arnaud; Bouchard, Frédéric

    2013-04-01

    Twenty two thin sections from Laguna Potrok Aike (Santa Cruz province, Patagonia, Argentina) sediments were analyzed in high resolution using μ-XRF, SEM-EDS and grain size determination using image analysis, focusing on an interval spanning the last Glacial interval. The aim of this work was to improve our understanding and identification of all sedimentary facies and their geochemical signature in order to strengthen the paleoenvironmental reconstruction made from this record. High Ca, Ca/Ti and Ca/Si values are revealing coarse sediments during the Last Glacial. Previous studies showed that these ratios were also related to (1) the occurrence of a calcitic lorica green algae Phacotus lenticularis during the Late Glacial and (2) autochthonous calcite precipitations during the Holocene. Potassium revealed clays or turbidites. High Fe content pointed to high (1) clay, or (2) silt, or (3) vivianite content, or (4) to low micropumices content. Peaks of Fe/Ti were rather related to (1) high clay content (2) high micropumices content and (3) sand events. Concomitant Fe, Mn, Mn/Ti and Fe/Ti peaks revealed (1) dissolution of volcanic rocks, (2) vivianite concretions, (3) redox mobilization in sediments, or (4) redeposited layers. Finally, Si and Ti revealed sand and silt respectively, but only if sediments are not rich in micropumices. Consequently, identical geochemical signatures are indicative of many different sedimentary facies in this sedimentary sequence, so that the use of proxies for the whole sedimentary sequence is virtually impossible. This work cautions against the use of many μ-XRF proxies for an entire long lacustrine sedimentary sequence, and obviously warns about their use from one site to another.

  11. A 1000-yr record of environmental change in NE China indicated by diatom assemblages from maar lake Erlongwan

    NASA Astrophysics Data System (ADS)

    Wang, Luo; Rioual, Patrick; Panizzo, Virginia N.; Lu, Houyuan; Gu, Zhaoyan; Chu, Guoqiang; Yang, Deguang; Han, Jingtai; Liu, Jiaqi; Mackay, Anson W.

    2012-07-01

    Past environmental changes based on diatom relative abundances have been inferred from the maar Lake Erlongwan in northeast China. The limnology of Lake Erlongwan is affected by the strongly seasonal regional climate. The composition of diatom assemblages, in turn, responds to changes in the seasonal duration of ice cover in winter, water-column turnover in spring and autumn, and thermal stratification in summer. Statistical analysis of the sedimentary diatom assemblages reveals three significant stratigraphic zones over the past 1000 yr. The highest abundance of the planktonic species Discostella species occurs between AD 1050 and 1400 and suggests an annual ice-free period of long duration and well-developed summer stratification of the water column. This planktonic diatom peak between ca. AD 1150 and 1200 suggests that this period was the warmest over the past 1000 yr. The interval between AD 1400 and 1800 is marked by a decline in planktonic diatoms and suggests shorter duration of the ice-free season, weaker water stratification and possibly generally cold conditions. After AD 1800 relative abundances of planktonic diatoms, including Puncticulata praetermissa and Asterionella formosa, increase again, which indicates lengthening of the duration of the annual ice-free period and a stronger overturn of the water column. All these data imply that the pattern of the seasons is different between the MWP and the 20th century.

  12. U-series dating of Lake Nyos maar basalts, Cameroon (West Africa): Implications for potential hazards on the Lake Nyos dam

    NASA Astrophysics Data System (ADS)

    Aka, Festus T.; Yokoyama, Tetsuya; Kusakabe, Minoru; Nakamura, Eizo; Tanyileke, Gregory; Ateba, Bekoa; Ngako, Vincent; Nnange, Joseph; Hell, Joseph

    2008-09-01

    From previously published 14C and K-Ar data, the age of formation of Lake Nyos maar in Cameroon is still in dispute. Lake Nyos exploded in 1986, releasing CO 2 that killed 1750 people and over 3000 cattle. Here we report results of the first measurements of major elements, trace elements and U-series disequilibria in ten basanites/trachy-basalts and two olivine tholeiites from Lake Nyos. It is the first time tholeiites are described in Lake Nyos. But for the tholeiites which are in 238U- 230Th equilibrium, all the other samples possess 238U- 230Th disequilibrium with 15 to 28% enrichment of 230Th over 238U. The ( 226Ra/ 230Th) activity ratios of these samples indicate small (2 to 4%) but significant 226Ra excesses. U-Th systematics and evidence from oxygen isotopes of the basalts and Lake Nyos granitic quartz separates show that the U-series disequilibria in these samples are source-based and not due to crustal contamination or post-eruptive alteration. Enrichment of 230Th is strong prima facie evidence that Lake Nyos is younger than 350 ka. The 230Th- 226Ra age of Nyos samples calculated with the ( 226Ra/ 230Th) ratio for zero-age Mt. Cameroon samples is 3.7 ± 0.5 ka, although this is a lower limit as the actual age is estimated to be older than 5 ka, based on the measured mean 230Th/ 238U activity ratio. The general stability of the Lake Nyos pyroclastic dam is a cause for concern, but judging from its 230Th- 226Ra formation age, we do not think that in the absence of a big rock fall or landslide into the lake, a big earthquake or volcanic eruption close to the lake, collapse of the dam from erosion alone is as imminent and alarming as has been suggested.

  13. Laguna Potrok Aike, Argentina: the first non-tropical environmental record in South America extending far beyond the Late-Glacial - a progress report

    NASA Astrophysics Data System (ADS)

    Zolitschka, B.; Anselmetti, F.; Ariztegui, D.; Corbella, H.; Francus, P.; Gebhardt, C.; Lücke, A.; Ohlendorf, C.; Schäbitz, F.; Pasado Science Team

    2009-04-01

    Within the framework of the ICDP-funded "Potrok Aike maar lake sediment archive drilling project" (PASADO) an international team of scientists carried out interdisciplinary research at the unique mid-Pleistocene (770 ka) maar lake of Laguna Potrok Aike in southern Patagonia (Province of Santa Cruz, Argentina). This lake is very sensitive to variations in southern hemispheric wind and pressure systems and thus holds a unique and continuous lacustrine record of climatic and ecological variability of global significance. Moreover, Southern Patagonia with its many active volcanoes is an ideal location to better understand the regional history of volcanism. These are two challenging geo-scientific themes that need to be tackled, especially as both of them have an increasing socio-economic relevance. Three months of drilling activities that finished last November 2008 were carried out by DOSECC from the drilling platform R/V "Kerry Kelts". More than 500 m of lacustrine sediments were recovered. This sedimentary archive will provide (1) new insights into the processes of regional back arc volcanism within the Pali Aike Volcanic Field itself as well as the more distant explosive volcanism of the Andean mountain chains; and, (2) high-resolution (decadal) quantitative climate and environmental reconstructions supported by multiple dating and stratigraphic correlations. Marine - ice core - terrestrial linkages will be emphasized as well as the incorporation of results from global climate modelling simulations for the last ca. 100 ka. The two drilled sites in the central deep basin of Laguna Potrok Aike have been selected based on four seismic surveys carried out between 2003 and 2005. Sediments were recovered at both drilled sites down to a subbottom depth of slightly more than 100 m using the GLAD800 drill rig with the hydraulic piston corer tool (HPC) at water depths varying between 95 and 100 m. The total core recovery is 94%. On-site core logging with the multi sensor

  14. New palynology-based astronomical and revised 40Ar/39Ar ages for the Eocene maar lake of Messel (Germany)

    NASA Astrophysics Data System (ADS)

    Lenz, Olaf K.; Wilde, Volker; Mertz, Dieter F.; Riegel, Walter

    2015-04-01

    The annually laminated oil shale from the Eocene maar lake at Messel (Federal State of Hessen, Germany) provides unique paleoenvironmental data for a time interval of ~640 ka during the Paleogene greenhouse phase. As a consequence of orbitally controlled changes in the vegetation in the vicinity of the lake, the lacustrine laminites can now be astronomically tuned. Dating is based on the short eccentricity amplitude modulations of the regional pollen rain and their correlation to the astronomical La2010a/La2010d solutions in combination with a revised 40Ar/39Ar age of a basalt fragment from a lapilli tuff section below the first lacustrine sediments. Depending on different newly suggested ages for the Fish Canyon sanidine used as monitor for neutron irradiation, the age for the eruption at Messel is between 48.27 ± 0.22 and 48.11 ± 0.22 Ma. This allows for the first time the exact correlation of a Paleogene lacustrine sequence to the marine record in Central Europe. The Messel oil shale becomes now slightly older than previously assumed and includes the Ypresian/Lutetian boundary that moves the base of the European Land Mammal Age Geiseltalian (MP 11) into the Lower Eocene. This opens a window for establishing an independent chronostratigraphic framework for Paleogene terrestrial records and their correlation to the marine realm. Furthermore, the study reveals that higher amounts of pollen from "wet" and thermophilous plants indicate less seasonal and more balanced precipitation and slightly higher temperatures during a well-expressed eccentricity minimum.

  15. PASADO - ICDP Deep Drilling at Laguna Potrok Aike (Argentina): A 50 ka Record of Increasing Environmental Dynamics

    NASA Astrophysics Data System (ADS)

    Zolitschka, Bernd; Anselmetti, Flavio; Ariztegui, Daniel; Francus, Pierre; Gebhardt, Catalina; Kliem, Annette Hahn Pierre; Lücke, Andreas; Ohlendorf, Christian; Schäbitz, Frank; Wastegard, Stefan

    2010-05-01

    Laguna Potrok Aike, located in the South-Patagonian province of Santa Cruz (52°58'S, 70°23'W), was formed by a volcanic (maar) eruption in the late Quaternary Pali Aike Volcanic Field several hundred thousand years ago. This archive holds a unique record of paleoclimatic and paleoecological variability from a region sensitive to variations in southern hemispheric wind and pressure systems, which provide a significant cornerstone for the understanding of the entire global climate system. Moreover, Laguna Potrok Aike is close to many active volcanoes allowing a better understanding of the history of volcanism in the Pali Aike Volcanic Field as well as in the Andean mountain chain, the latter located in a distance of less than 150 km to the west. Finally, Patagonia is the source region of eolian dust blown from the South American continent into the South Atlantic and onto the Antarctic ice sheet. The currently ongoing global climate change, the thread of volcanic hazards as well as of regional dust storms are of increasing socio-economic relevance and thus challenging scientific themes that are tackled for southernmost South America with an interdisciplinary research approach in the framework of the ICDP-funded "Potrok Aike Maar Lake Sediment Archive Drilling Project" (PASADO). Using the GLAD800 drilling platform seven holes were drilled in the southern spring of 2008. A total of 510 m of lacustrine sediments were recovered by an international scientific team from the central 100 m deep basin with an excellent core recovery rate of 94.4%. The reference profile with a composite depth of 106 m consists of undisturbed laminated and sand-layered lacustrine silts with an increasing number of coarse gravel layers, turbidites and homogenites with depth. Below 80 m composite depth two mass-movement deposits (10 m and 5 m in thickness) are recorded. These deposits show tilted and distorted layers as well as nodules of fine-grained sediments and randomly distributed gravel

  16. Facies changes and high calorific peat formation in a quaternary maar lake, central Anatolia, Turkey: the possible role of geothermal processes in a closed lacustrine basin

    NASA Astrophysics Data System (ADS)

    Kazanci, Nizamettin; Gevrek, Aliİhsan; Varol, Baki

    1995-01-01

    The sedimentary infill of the Acigöl maar lake, one of the volcanic centres in the Cappadocia district of Anatolia, contains unusual, high-calorific sub-Recent peat deposits, of which the origin is attributed to geothermal processes. The sedimentary facies record is analyzed to reconstruct the lake's depositional history and to disentangle the combined signal of climatic and geothermal factors. The facies succession comprises: a lake-fringe clastic apron shed from the maar walls; early-stage, coarse-grained tuffaceous deposits of the lake proper, intercalated with brecciated mudstones and limestones; and final-stage, fine-grained tuffaceous deposits of the lake proper, intercalated with peats and plant-bearing clastics and with some terminal travertines. The closed lake was highly dependent on climate, particularly precipitation, and the depositional conditions were further controlled by a connective hydrothermal system which itself was driven by the input of meteoric water. The associated heat flow played an important role by creating a microclimatic niche, where even the impoverished late-Quaternary (cold regional climate) vegetation could flourish and form substantial peats. The varying hydrological budget of the lake was the main "switching" mechanism for the peat-forming conditions, with two water-depth thresholds involved. If the lake level rose too high, the low vegetation was drowned and hemipelagic clastic sedimentation prevailed. If the lake level fell too low, the vegetation was killed and formation of travertine took place. The heat flow through the pore water and clastic sediments was crucial to the high maturation of the peat deposits.

  17. Maar Lake Sediments in the Mediterranean: High-Resolution Archives for Tephra Recording and Paleoenvironmental Reconstruction - a Case Study From Lago Grande di Monticchio (Southern Italy)

    NASA Astrophysics Data System (ADS)

    Negendank, J. F.; Wulf, S.; Brauer, A.; Mingram, J.

    2001-12-01

    Maar lake deposits with sedimentation rates of one or two order of magnitude higher than marine records are excellent archives for the preservation of annual laminations (varves) and thus make available information of the past with a high temporal resolution. In the Mediterranean, such archives are known from maar and crater lakes situated within Quaternary volcanic fields of the Italian Peninsula. Because of the vicinity to high-explosive volcanoes - most of them characterised by numerous tephra producing events during the Late Quaternary - sediments of these sites additionally provide considerable potential for tephrochronological and tephrostratigraphical studies. The maar lake Lago Grande di Monticchio (Mt. Vulture, Basilicata) has turned out to be one of the most suitable sites in Europe. On the one hand, intensive sedimentological, geochemical, palynological and palaeomagnetic studies on numerous laminated sediment cores spanning the last 101 kyr have demonstrated the great potential for palaeoenvironmental reconstruction. The results of these studies indicate a highly variable environment during the last glacial / interglacial cycle with numerous short and abrupt changes, that can be correlated to rapid climate changes recognized in ice-core and deep-sea records. For such comparisons independent chronologies are required. Regarding the sediment record of Lago Grande di Monticchio a varve-supported sedimentation rate chronology has been established based on the counting of annual laminations and interpolation of sedimentation rates for non-varved sections. This chronology has been confirmed by a high-resolution tephrochronology, numerous radiocarbon datings and three 40Ar/39Ar datings on prominent tephra layers. In addition to its value as a high-resolution palaeoclimatic archive, the Monticchio record has become a key position for inter-site correlation in the eastern Mediterranean. This is mainly due to the large number of intercalated tephra layers (n=344

  18. Diagenetic effects on magnetic minerals in a Holocene lacustrine sediment core from Huguangyan maar lake, southeast China

    NASA Astrophysics Data System (ADS)

    Wu, Xudong; Wang, Yong; Bian, Liu; Shen, Ji

    2016-06-01

    Post-depositional reductive diagenesis usually results in partial or entire cleansing of the pristine palaeomagnetic signal, therefore, its intensity is important to be assessed for sediments that are in the purpose of retrieving palaeomagnetic information. Grain size, rock magnetic and geochemical studies on the entire core, along with scanning electron microscope (SEM) observations and X-ray diffraction (XRD) analyses for representative samples were carried out on a Holocene sediment core retrieved from the deep water part of Huguangyan maar lake (HGY), southeast China. The pristine magnetic mineral assemblage of the studied core is domianted by superparamagnetic (SP) and stable single domain (SSD) titanomagnetite, and high coercivity minerals are not detectable. Based on down-core variations of the average grain size (MZ), total organic carbon (TOC), detrital elements (Al, Ti, Fe and Mn), and the concentration and mineralogy of magnetic minerals, the studied core could be divided into three subsections. The uppermost subsection is the least affected by diagenesis, with detrital titanomagnetite as the dominant magnetic mineral. This is owing to low TOC contents, but high detrital input generated by weak Asian summer monsoon intensity during the late Holocene. The intermediate subsection shows down-core progressively enhanced dissolution of detrital titanomagnetite, and concomitant formation of authigenic pyrite and siderite, which indicates down-core progressively enhanced diagenesis generated by down-core progressive increasing TOC content, but decreasing detrital input as the result of down-core progressively strengthened Asian summer monsoon intensity. The pristine magnetic mineral assemblage has been profoundly modified in the lowermost subsection. At certain positions of the lowermost subsection, detrital titanomagnetite has been even completely dissolved via diagenesis, giving place to authigenic pyrite and siderite. High TOC content, but low detrital input

  19. Core scanning procedures and first characterisation of the 106 m long lacustrine sediment record of Laguna Potrok Aike, Argentina (ICDP-project PASADO)

    NASA Astrophysics Data System (ADS)

    Ohlendorf, Christian; Enters, Dirk; Gebhardt, Catalina; Hahn, Annette; Kliem, Pierre; Zolitschka, Bernd; Pasado Science Team

    2010-05-01

    Drilling operations for the southernmost ICDP project dedicated to terrestrial paleoclimatic reconstruction, the "Potrok Aike Maar Lake Sediment Archive Drilling Project" (PASADO), were completed in late November 2008. In the maar lake Laguna Potrok Aike (52°S, 70°W; 116 m asl.; diameter: 3.5 km, water depth: 100 m) in southern Patagonia, Argentina in total 510 m of lacustrine sediments have been recoverd using the GLAD800 platform equipped with a CS-1500 drill rig. Quadruplicate and triplicate cores down to a maximum depth of 101.5 m below lake floor have been taken using mainly the hydraulic piston coring tool. Total core recovery was 94,4 % from two drillsites located 700 m apart from each other in the central profundal plane of the lake. In 2009 all cores from Site 2 (southern basin plane) and most cores from Site 1 (central basin plane) were opened, described, documented by digital high resolution photography and scanned with different non-destructive techniques. A 106.08 m long composite profile was constructed for Site 2 based on visual core correlation and was then subsampled completely in consecutive 2 cm thick intervalls. Core scanning was performed in 5 mm steps for all parameters and involved the following techniques: 1) color scanning with a handheld X-rite spectrometer, 2) magnetic susceptibility scanning with a Bartington MS2F-sensor, 3) XRF scanning and X-radiography with an ITRAX core scanner (COX analytical systems) and 4) p-wave velocity/transmission seismograms and gamma ray absorption with a modified Geotek MSCL tool. According to the preliminary age model, the sedimentary record from Laguna Potrok Aike reaches back to OIS 3 and exhibits contrasting lithologies downcore especially in the Pleistocene part of the record. Moreover, first estimates indicate that up to 50% of the record consist of redeposited sediments. To account for these pronounced downcore lithological changes it was necessary to adjust the XRF-scanning parameters (i.e. X

  20. Holocene vegetation and climate dynamics of NE China based on the pollen record from Sihailongwan Maar Lake

    NASA Astrophysics Data System (ADS)

    Stebich, Martina; Rehfeld, Kira; Schlütz, Frank; Tarasov, Pavel E.; Liu, Jiaqi; Mingram, Jens

    2015-09-01

    High-resolution palynological analysis on annually laminated sediments of Sihailongwan Maar Lake (SHL) provides new insights into the Holocene vegetation and climate dynamics of NE China. The robust chronology of the presented record is based on varve counting and AMS radiocarbon dates from terrestrial plant macro-remains. In addition to the qualitative interpretation of the pollen data, we provide quantitative reconstructions of vegetation and climate based on the method of biomization and weighted averaging partial least squares regression (WA-PLS) technique, respectively. Power spectra were computed to investigate the frequency domain distribution of proxy signals and potential natural periodicities. Pollen assemblages, pollen-derived biome scores and climate variables as well as the cyclicity pattern indicate that NE China experienced significant changes in temperature and moisture conditions during the Holocene. Within the earliest phase of the Holocene, a large-scale reorganization of vegetation occurred, reflecting the reconstructed shift towards higher temperatures and precipitation values and the initial Holocene strengthening and northward expansion of the East Asian summer monsoon (EASM). Afterwards, summer temperatures remain at a high level, whereas the reconstructed precipitation shows an increasing trend until approximately 4000 cal. yr BP. Since 3500 cal. yr BP, temperature and precipitation values decline, indicating moderate cooling and weakening of the EASM. A distinct periodicity of 550-600 years and evidence of a Mid-Holocene transition from a temperature-triggered to a predominantly moisture-triggered climate regime are derived from the power spectra analysis. The results obtained from SHL are largely consistent with other palaeoenvironmental records from NE China, substantiating the regional nature of the reconstructed vegetation and climate patterns. However, the reconstructed climate changes contrast with the moisture evolution recorded in

  1. Geochemical insight into differences in the physical structures and dynamics of two adjacent maar lakes at Mt. Vulture volcano (southern Italy)

    NASA Astrophysics Data System (ADS)

    Caracausi, A.; Nicolosi, M.; Nuccio, P. M.; Favara, R.; Paternoster, M.; Rosciglione, A.

    2013-05-01

    report on the first geochemical investigation of the Monticchio maar lakes (Mt. Vulture volcano, southern Italy) covering an annual cycle that aimed at understanding the characteristic features of the physical structures and dynamics of the two lakes. We provide the first detailed description of the lakes based on high-resolution conductivity-temperature-depth (CTD) profiles, chemical and isotopic (H and O) compositions of the water, and the amounts of dissolved gases (e.g., He, Ar, CH4, and CO2). The combined data set reveals that the two lakes, which are separated by less than 200 m, exhibit different dynamics: one is a meromictic lake, where the waters are rich in biogenic and mantle-derived gases, while the other is a monomictic lake, which exhibits complete turnover of the water in winter and the release of dissolved gases. Our data strongly suggest that the differences in the dynamics of the two lakes are due to different density profiles affected by dissolved solutes, mainly Fe, which is strongly enriched in the deep water of the meromictic lake. A conceptual model of water balance was constructed based on the correlation between the chemical composition of the water and the hydrogen isotopic signature. Gas-rich groundwaters that feed both of the lakes and evaporation processes subsequently modify the water chemistry of the lakes. Our data highlight that no further potential hazardous accumulation of lethal gases is expected at the Monticchio lakes. Nevertheless, geochemical monitoring is needed to prevent the possibility of vigorous gas releases that have previously occurred in historical time.

  2. Changements climatiques et variations du champ magnetique terrestre dans le sud de la Patagonie (Argentine) depuis 51 200 ans reconstitues a partir des proprietes magnetiques des sediments du lac Laguna Potrok Aike

    NASA Astrophysics Data System (ADS)

    Lise-Pronovost, Agathe

    Rock magnetism is influenced by climate and by the Earth's magnetic field. The goal of this thesis is to use the rock magnetic properties of the long sedimentary sequence from the lake Laguna Potrok Aike (106 m, 51200 cal BP) to derive paleomagnetic and paleoclimatic records in a key area of the Southern Hemisphere that is poorly documented. Laguna Potrok Aike (52°S, 70°W) is located in southeastern Patagonia (Argentina) in the path of the strong Southern Hemisphere westerly winds and in the source area of the dust deposited in Antarctica during Glacial periods. The lake geographical location is therefore ideal to reconstruct past changes in aeolian activity and climate changes in Patagonia. It is also a key location to reconstruct past changes of the geomagnetic field because the Southern Hemisphere is significantly under-documented relative to the Northern Hemisphere. In addition, the proximity of the South Atlantic Anomaly (SAA) as well as the Southern Hemisphere high flux lobes could allow identifying differences in the paleomagnetic field evolution in southern South America relative to the much more documented Northern Hemisphere. For his strong potential to provide high-resolution climatic, aeolian and paleomagnetic records beyond the last climatic transition, the maar lake Laguna Potrok Aike was drilled in the framework of the International scientific Continental Drilling Program (ICDP) for the Potrok Aike maar lake Sediment Archive Drilling prOject (PASADO). In this thesis, high-resolution rock-magnetic and physical properties are used in order to reconstruct paleoclimate and paleomagnetic records from the southernmost part of South America. In the first chapter, the full-vector paleomagnetic record (inclination, declination and relative paleointensity) derived from the sediments of Laguna Potrok Aike. A grain size influence on the relative paleointensity record (NRM/ARM) was corrected using the median destructive field of the natural remanent

  3. Rock-magnetic proxies of wind intensity and dust since 51,200 cal BP from lacustrine sediments of Laguna Potrok Aike, southeastern Patagonia

    NASA Astrophysics Data System (ADS)

    Lisé-Pronovost, Agathe; St-Onge, Guillaume; Gogorza, Claudia; Haberzettl, Torsten; Jouve, Guillaume; Francus, Pierre; Ohlendorf, Christian; Gebhardt, Catalina; Zolitschka, Bernd

    2015-02-01

    The sedimentary archive from Laguna Potrok Aike is the only continuous record reaching back to the last Glacial period in continental southeastern Patagonia. Located in the path of the Southern Hemisphere westerly winds and in the source region of dust deposited in Antarctica during Glacial periods, southern Patagonia is a vantage point to reconstruct past changes in aeolian activity. Here we use high-resolution rock-magnetic and physical grain size data from site 2 of the International Continental scientific Drilling Program (ICDP) Potrok Aike maar lake Sediment Archive Drilling prOject (PASADO) in order to develop magnetic proxies of dust and wind intensity at 52°S since 51,200 cal BP. Rock-magnetic analysis indicates the magnetic mineral assemblage is dominated by detrital magnetite. Based on the estimated flux of magnetite to the lake and comparison with distal dust records from the Southern Ocean and Antarctica, kLF is interpreted as a dust indicator in the dust source of southern Patagonia at the millennial time scale, when ferrimagnetic grain size and coercivity influence are minimal. Comparison to physical grain-size data indicates that the median destructive field of isothermal remanent magnetization (MDFIRM) mostly reflects medium to coarse magnetite bearing silts typically transported by winds for short-term suspension. Comparison with wind-intensity proxies from the Southern Hemisphere during the last Glacial period and with regional records from Patagonia since the last deglaciation including marine, lacustrine and peat bog sediments as well as speleothems reveals similar variability with MDFIRM up to the centennial time scale. MDFIRM is interpreted as a wind-intensity proxy independent of moisture changes for southeastern Patagonia, with stronger winds capable of transporting coarser magnetite bearing silts to the lake.

  4. Deep Drilling at Laguna Potrok Aike, Argentina: Recovery of a Paleoclimate Record for the Last Glacial from the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Zolitschka, B.; Anselmetti, F.; Ariztegui, D.; Corbella, H.; Francus, P.; Gebhardt, C.; Hahn, A.; Kliem, P.; Lücke, A.; Ohlendorf, C.; Schäbitz, F.

    2009-12-01

    Laguna Potrok Aike, located in the South-Patagonian province of Santa Cruz (52°58’S, 70°23’W), was formed 770 ka ago by a volcanic (maar) eruption. Within the framework of the ICDP-funded project PASADO two sites were drilled from September to November 2008 using the GLAD800 drilling platform. A total of 513 m of lacustrine sediments were recovered from the central deep basin by an international team. The sediments hold a unique record of paleoclimatic and paleoecological variability from a region sensitive to variations in southern hemispheric wind and pressure systems and thus significant for the understanding of the global climate system. Moreover, Laguna Potrok Aike is close to many active volcanoes allowing a better understanding of the history of volcanism in the Pali Aike Volcanic Field and in the nearby Andean mountain chain. These challenging scientific themes need to be tackled in a global context as both are of increasing socio-economic relevance. On-site core logging based on magnetic susceptibility data documents an excellent correlation between the quadruplicate holes drilled at Site 1 and between the triplicate holes recovered from Site 2. Also, correlation between both sites located 700 m apart from each other is feasible. After splitting the cores in the lab, a reference profile was established down to a composite depth of 107 m for the replicate cores from Site 2. Sediments consist of laminated and sand-layered lacustrine silts with an increasing number of turbidites and homogenites with depth. Below 80 m composite depth two mass movement deposits (10 m and 5 m in thickness) are recorded. These deposits show tilted and distorted layers as well as nodules of fine grained sediments and randomly distributed gravel. Such features indicate an increased slump activity probably related to lake level fluctuations or seismicity. Also with depth coarse gravel layers are present and point to changes in hydrological conditions in the catchment area

  5. Carbon sources and biogeochemical processes in Monticchio maar lakes, Mt Vulture volcano (southern Italy): New geochemical constrains of active degassing of mantle derived fluids

    NASA Astrophysics Data System (ADS)

    Caracausi, A.; Nuccio, P. M.; Favara, R.; Grassa, F.

    2012-04-01

    Since the catastrophic releases of carbon dioxide from the African volcanic lakes Nyos and Monoun in the 1980s, the scientific community draw attention towards all those crater lakes able to accumulate massive amount of CO2, which could be catastrophically released following overturn of their deep waters. This implies a quantification of the gas accumulation rate into the lakes and the knowledge of recharge processes and their evolution in time. In fact the gaseous recharge in a lake occurs at alarming rates, when an active degassing of hazardous nature volatiles occurs into the lakes and the structure and dynamic of the lake permit the accumulation of gases into the water. The Monticchio lakes, LPM and LGM, occupies two maar craters formed during the last volcanic activity of Mt. Vulture occurred ˜ 140 000 years ago. LPM is a permanently stratified lake, with a thick deep volume of stagnant water and a shallower layer affected by seasonal overturn. On the contrary LGM is a monomittic lake with a complete overturn of the water during winter time. The major dissolved volatiles are methane and CO2. Dissolved helium is in trace amounts and its isotopic signature ranges between 6.1 and 5.3 Ra (Ra is the atmospheric 3He/4He isotopic ratio). These values are within the range of those measured in the olivine fluid inclusions (both of mantle xenoliths and dispersed in the pyroclastics) of LPM maar ejecta. During three years of investigations we observed that dissolved methane in the deep waters of LGM drastically decreases in wintertime as consequence of the complete overturn of the water. The isotopic signature of methane in the deepest portions of LGM (both sediment and water) is quite stable with time and highlights a biogenic origin, being produced both by acetate fermentation and by CO2-reduction in variable proportions. In contrast, a higher contribution of methane produced via CO2 reduction characterizes sediments at shallower depths. At LPM, there is a great

  6. A multi-proxy intercomparison of environmental change in two maar lake records from central Turkey during the last 14 ka

    NASA Astrophysics Data System (ADS)

    Roberts, C. Neil; Allcock, Samantha L.; Arnaud, Fabien; Dean, Jonathan R.; Eastwood, Warren J.; Jones, Matthew D.; Leng, Melanie J.; Metcalfe, Sarah E.; Malet, Emmanuel; Woodbridge, Jessie; Yiǧitbaşıoǧlu, Hakan

    2016-04-01

    Individual palaeoenvironmental records are a combination of regional-scale (e.g. climatic) and local factors. In order to separate these signals, we compare multiple proxies from two nearby maar lake records, on the assumption that common signals are due to regional-scale forcing. On the other side, we infer that residual signals are likely to be local and site-specific, rather than reflecting regional climate changes. A new core sequence from Nar lake has been dated by varve counting and U-Th as covering the last 13,800 years (Dean et al., 2015; Roberts et al., 2016). Periods of marked dryness are associated with peaks in Mg/dolomite, elevated Diatom-Inferred Electrical Conductivity, an absence of laminated sediments, and low Quercus/chenopod ratios. These conditions occurred during the Late-Glacial stadial, at 4.3-3.7 and 3.2-2.6 ka BP. Wet phases occurred during the early Holocene and again 1.5-0.6 ka, characterised by negative δ18O values, calcite precipitation, high Ca/Sr ratios, a high % of planktonic diatoms, laminated sediments, and high Quercus/chenopod ratios. Comparison with the independently dated record from Eski Acıgöl (Roberts et al., 2001) shows good correspondence for many proxies, especially for δ18O. A ranking of multiple proxies shows the worst correspondence is for clastic lithogenic elements (e.g. Ti flux). Differences between the two lake records are caused by basin infilling at Eski Acıgöl, which fails to register climatic changes during the last 2 ka, and to catchment erosion and increased flux of lithogenic elements into Nar lake; this is catchment-specific and primarily anthropogenic rather than climatic in origin. In separating a regional signal from site-specific "noise", two lakes may therefore be better than one. Dean, J.R. et al. 2015 Eastern Mediterranean hydroclimate over the late glacial and Holocene, reconstructed from the sediments of Nar lake, central Turkey, using stable isotopes and carbonate mineralogy. Quaternary

  7. Atmospheric production signal in 10Be from varved sediments of Lake Meerfelder Maar during the late glacial-early Holocene transition

    NASA Astrophysics Data System (ADS)

    Czymzik, Markus; Adolphi, Florian; Muscheler, Raimund; Brauer, Achim; Mekhaldi, Florian; Martin-Puertas, Celia; Tjallingii, Rik; Aldahan, Ala; Possnert, Göran

    2016-04-01

    Beryllium 10 concentrations (10Becon) were measured at 20-year resolution in annually laminated (varved) sediments of Lake Meerfelder Maar (western Germany) covering the late glacial-early Holocene transition 11310-13130 varve years before present. Comparing the 10Becon record to environmental proxy records from the same archive indicates that varying sediment accumulation and composition only slightly modify trends, but do not substantially influence multi-decadal to centennial 10Becon excursions. Corrected for potential environmental biases using multiple-regression analysis, the resulting 10Beatmosphere time-series likely represents an alternative mid-latitude 10Be production record, exhibiting broad similarities but also some differences to radionuclide records as 14C in tree rings and 10Be in polar ice cores. The preservation of the globally common atmospheric production signal in 10Be from varved lake sediments indicates the, to date, largely unexplored potential of these archives for the synchronization to other radionuclide records around the globe, complementing existing solar activity reconstructions and Sun-climate studies.

  8. Modern and subrecent spatial distribution and characteristics of sediment infill controlled by internal depositional dynamics, Laguna Potrok Aike (southern Patagonia, Argentina)

    NASA Astrophysics Data System (ADS)

    Kastner, S.; Ohlendorf, C.; Haberzettl, T.; Lücke, A.; Maidana, N. I.; Mayr, C.; Schäbitz, F.; Zolitschka, B.

    2009-04-01

    Situated in the dry steppe environment of south-eastern Patagonia the 100 m deep and max. 770 ka old maar lake Laguna Potrok Aike (51°58'S, 70°23'W) has a high potential as a palaeolimnological key site for the reconstruction of terrestrial palaeoclimate conditions. As this area is sensitive to variations in southern hemispheric wind and pressure systems the lake holds a unique lacustrine record of palaeoclimatic and palaeoecological variability. Depositional changes inferred from the lacustrine sediment sequence as well as subaerial and subaquatic lake level terraces provide detailed information about the water budget of the lake related to the variability of the Southern Hemispheric Westerlies. For this reason the lake was chosen as an ICDP drilling site in 2008 within the "Potrok Aike maar lake sediment archive drilling project" (PASADO). Based on high resolution multi-proxy investigations of the last 16,000 years carried out on a 18.9 m long sediment record (Haberzettl et al., 2007; Mayr et al., 2009; Wille et al., 2007) this study focuses on the understanding of internal depositional dynamics which control the characteristics and spatial distribution of the sediment infill of this lake. Furthermore, it provides information improving the accuracy of the interpretation of the long sediment record recovered within the PASADO project. A survey of the spatial sediment distribution was carried out in 2005 using 46 gravity cores of up to 49 cm length covering a range of water depths from 9 to 100 m. All 46 cores were scanned with X-ray fluorescence technique and for magnetic susceptibility with up to 1 mm spatial resolution. Using Ca and Ti as well as magnetic susceptibility data the cores were correlated and linked to the established age model (Haberzettl et al., 2005). As these parameters vary considerably and not consistently within the suite of littoral cores, a correlation prior to the 2005 sediment surface is solely based on cores from water depths exceeding

  9. Developments in the use of high-resolution X-Ray fluorescence core scanning data of varved sediments for paleoclimate studies: an example of Lake Meerfelder Maar, Germany.

    NASA Astrophysics Data System (ADS)

    Martin-Puertas, Celia; Tjallingii, Rik; Bloemsma, Menno; Brauer, Achim

    2015-04-01

    The annually laminated record of the Lake Meerfelder Maar (Germany) is one of the most significant paleoclimatic archives in central Europe because of i) its robust chronology based on varve counting and tephrochronology, and ii) its very high sensitivity to the North Atlantic climate variability. In this study, varve thickness and micro X-ray fluorescence (XRF) data are combined with the published decadal to centennial resolved pollen assemblage between 11,700 to 9,000 yr BP. This period covers two major biostratigraphic stages in Europe, i.e. the Preboreal and the Boreal climatic periods. We focus on the timing and duration of the Preboreal-Boreal climatic transition, as well as short-lived cooling events in the North Atlantic region such as the Preboreal Oscillation (PBO). Due to the predominantly basaltic composition of the MFM catchment, we use normalized Titanium (Ti) intensities as a proxy for detrital influx. This is in close agreement with changes in varve thickness indicating that the lake variability is mainly driven by the annual detrital discharge into the lake. Statistical clustering of the XRF data reveals six chemo-stratigraphic units coinciding with major changes in local vegetation. The stratigraphical boundary coinciding with the Preboreal-Boreal transition is dated at 10,690 varve yr BP. This is characterized by an abrupt increase in detrital material, likely because of a change to wetter conditions in the central Europe. Although the PBO is not clearly identified in the MFM pollen record, a individual cluster from 11,230 to 11,020 varve yr BP broadly coincides with the timing of the PBO in the North Atlantic region, suggesting this cool event lasted ca 200 years in central Europe. The most significant change in the lake occurred between 9,655 and 10,530 varve yr BP, when detrital influx nearly completely ceased and varves were poorly preserved. However, this interval within the Boreal period has no counterpart in the pollen record and

  10. Paleoclimate Records from New Zealand Maar Lakes, Insights into ENSO Teleconnections and Climatic Events in the South (West) Pacific.

    NASA Astrophysics Data System (ADS)

    Shulmeister, J.; Nobes, D. C.; Striewski, B.

    2008-05-01

    The maar craters of the New Zealand Auckland Volcanic Field (36.5°S, 174.5°E) contain some of the highest resolution late-Quaternary paleoclimate records in the Southern Hemisphere. Here we integrate laminae count results from recent drilling in the Hopua Crater with existing records from the nearby Onepoto Crater (Pepper et al., 2004). In total these records cover many thousands of years between the onset of the last glaciation maximum and the early mid-Holocene. The cores are strongly laminated. Individual laminae in both craters are very fine (sub-mm to mm scale) and form couplets which comprise a darker mineralogenic rich layer and a lighter diatomaceous layer. In places these couplets are annual, and may reflect seasonal algal blooms, but in other sections of the record, notably through the late-Glacial and Holocene, the couplets are deposited at inter-annual time scales. Spectral analyses of couplet thickness counts using a fast Fourier transform (FFT) with 64 to 256-year running windows, and a 50 per cent overlap indicate strong spectral power during the LGM and markedly weaker power during both the deglaciation and early Holocene. In fact there is no spectral strength for most of these periods. Three brief (centennial duration) events punctuate this extended period of low spectral power. These occur at c. 16 ka, c. 14.8 ka and during the early Holocene. They display spectral power in the 5-7yr ENSO window and also at longer time intervals that may be consistent with the Pacific Decadal Oscillation. We infer the local switching on (or up) of ENSO and PDO teleconnections and suspect these are embedded in circum-polar circulation changes. In addition to these spectral power episodes, there is a general increase in the number of couplet cycles per century between the deglaciation and the early mid-Holocene. This matches observations from Equador and Peru and suggests that trans-Pacific ENSO responses are in phase between western tropical South America and New

  11. Rock-magnetic signatures of aeolian activity, precipitation and extreme runoff events from the sediments of Laguna Potrok Aike (southern Patagonia) since 51,200 cal BP

    NASA Astrophysics Data System (ADS)

    St-Onge, G.; Lisé-Pronovost, A.; Gogorza, C. S. G.; Haberzettl, T.; Jouve, G.; Francus, P.; Ohlendorf, C.; Gebhardt, C.; Zolitschka, B.

    2014-12-01

    The sedimentary archive from Laguna Potrok Aike is the only continuous record reaching back to the last Glacial period in continental southeastern Patagonia. Here we use high-resolution u-channel, as well as discrete rock-magnetic and physical grain size data from the 106 m long core (~51,200 cal BP) of site 2 of the ICDP Potrok Aike maar lake Sediment Archive Drilling project (PASADO) in order to develop magnetic proxies of dust and wind intensity, as well as precipitation and extreme runoff events. Rock-magnetic analyses indicate the magnetic mineral assemblage is dominated by detrital magnetite and that low field magnetic susceptibility (kLF) can be interpreted as a dust indicator in the dust source of southern Patagonia at the millennial time scale. On shorter time scales however, kLF variability is correlated to ferrimagnetic grain size and coercivity. Comparison to physical grain-size data indicates that the median destructive field of the isothermal remanent magnetisation (MDFIRM) mostly reflects medium to coarse magnetite bearing silts typically transported by winds for short-term suspension and that MDFIRM can be interpreted as a wind-intensity proxy, with stronger winds capable of transporting coarser silts to the lake. In addition, about half of the sedimentary sequence is composed of mass movement deposits (MMDs). Within these MMDs, two distinct sedimentary facies can easily be identified. The first rock-magnetic signature is detected in MMDs composed of reworked sand and tephra material. The signature consists of a gyroremanent magnetisation (GRM) acquired during demagnetisation of the natural remanent magnetisation (NRM) and other rock-magnetic properties typical of iron sulfides such as greigite. We interpret these intervals as authigenic formation of iron sulfides in suboxic conditions within the MMD. The second rock-magnetic signature consists of 10 short intervals located on the top of MMDs characterized by GRM acquisition during demagnetisation

  12. The Late Quaternary tephrostratigraphy of annually laminated sediments from Meerfelder Maar, Germany

    NASA Astrophysics Data System (ADS)

    Lane, Christine S.; Brauer, Achim; Martín-Puertas, Celia; Blockley, Simon P. E.; Smith, Victoria C.; Tomlinson, Emma L.

    2015-08-01

    The record of Late Quaternary environmental change within the sediments of Meerfelder Maar in the Eifel region of Germany is renowned for its high precision chronology, which is annually laminated throughout the Last Glacial to Interglacial transition (LGIT) and most of the Holocene. Two visible tephra layers are prominent within the floating varve chronology of Meerfelder Maar. An Early Holocene tephra layer, the Ulmener Maar Tephra (∼11,000 varve years BP), provides a tie-line of the Meerfelder Maar record to the varved Holocene record of nearby Lake Holzmaar. The Laacher See Tephra provides another prominent time marker for the late Allerød, ∼200 varve years before the transition into the Younger Dryas at 12,680 varve years BP. Further investigation has now shown that there are also 15 cryptotephra layers within the Meerfelder Maar LGIT-Holocene stratigraphy and these layers hold the potential to make direct comparisons between the Meerfelder Maar record and other palaeoenvironmental archives from across Europe and the North Atlantic. Most notable is the presence of the Vedde Ash, the most widespread Icelandic eruption known from the Late Quaternary, which occurred midway through the Younger Dryas. The Vedde Ash has also been found in the Greenland ice cores and can be used as an isochron around which the GICC05 and Meerfelder Maar annual chronologies can be compared. Near the base of the annual laminations in Meerfelder Maar a cryptotephra is found that correlates to the Neapolitan Yellow Tuff, erupted from Campi Flegrei in southern Italy, 1200 km away. This is the furthest north that the Neapolitan Yellow Tuff has been found, highlighting its importance in the construction of a European-wide tephrostratigraphic framework. The co-location of cryptotephra layers from Italian, Icelandic and Eifel volcanic sources, within such a precise chronological record, makes Meerfelder Maar one of the most important tephrostratotype records for continental Europe

  13. Structure of the Pliocene Camp dels Ninots maar-diatreme (Catalan Volcanic Zone, NE Spain)

    NASA Astrophysics Data System (ADS)

    Oms, O.; Bolós, X.; Barde-Cabusson, S.; Martí, J.; Casas, A.; Lovera, R.; Himi, M.; Gómez de Soler, B.; Campeny Vall-Llosera, G.; Pedrazzi, D.; Agustí, J.

    2015-11-01

    Maar volcanoes expose shallower or deeper levels of their internal structure as a function of the degree of erosion. In El Camp dels Ninots maar-diatreme (Catalan Volcanic Zone, Spain), the tephra ring has been largely eroded, and the remaining volcanic deposits infilling the diatreme are hidden under a lacustrine sedimentary infill of the crater. The volcano shows hardly any exposure, so its study needs the application of direct (e.g., boreholes) and indirect (shallow geophysics) subsurface exploration techniques. Additionally, this maar-diatreme was built astride two different substrates (i.e., mixed setting) as a result of its location in a normal fault separating Neogene sediments from Paleozoic granites. In order to characterize the internal structure and post-eruption stratigraphy of the maar-diatreme, we did geological studies (mapping, continuous core logging, and description of the tephra ring outcrops) and near-surface geophysics, including nine transects of electric resistivity tomography and a gravity survey. Results show that the deeper part of the diatreme is excavated into granites and is relatively steep and symmetrical. The uppermost diatreme is asymmetrical because of mechanical contrast between granites and Pliocene sands. The maar crater contained a lake permanently isolated from the surrounding relief and was deep enough to host anoxic bottom waters while its margins had shallower waters. These lake conditions preserved the remarkable Pliocene fossil record found in the lacustrine sediments.

  14. Carbon and nitrogen isotope composition of core catcher samples from the ICDP deep drilling at Laguna Potrok Aike (Patagonia, Argentina)

    NASA Astrophysics Data System (ADS)

    Luecke, Andreas; Wissel, Holger; Mayr*, Christoph; Oehlerich, Markus; Ohlendorf, Christian; Zolitschka, Bernd; Pasado Science Team

    2010-05-01

    The ICDP project PASADO aims to develop a detailed paleoclimatic record for the southern part of the South American continent from sediments of Laguna Potrok Aike (51°58'S, 70°23'W), situated in the Patagonian steppe east of the Andean cordillera and north of the Street of Magellan. The precursor project SALSA recovered the Holocene and Late Glacial sediment infill of Laguna Potrok Aike and developed the environmental history of the semi-arid Patagonian steppe by a consequent interdisciplinary multi-proxy approach (e.g. Haberzettl et al., 2007). From September to November 2008 the ICDP deep drilling took place and successfully recovered in total 510 m of sediments from two sites resulting in a composite depth of 106 m for the selected main study Site 2. A preliminary age model places the record within the last 50.000 years. During the drilling campaign, the core catcher content of each drilled core run (3 m) was taken as separate sample to be shared and distributed between involved laboratories long before the main sampling party. A total of 70 core catcher samples describe the sediments of Site 2 and will form the base for more detailed investigations on the palaeoclimatic history of Patagonia. We here report on the organic carbon and nitrogen isotope composition of bulk sediment and plant debris of the core catcher samples. Similar investigations were performed for Holocene and Late Glacial sediments of Laguna Potrok Aike revealing insights into the organic matter dynamics of the lake and its catchment as well as into climatically induced hydrological variations with related lake level fluctuations (Mayr et al., 2009). The carbon and nitrogen content of the core catcher fine sediment fraction (<200 µm) is low to very low (around 1 % and 0.1 %, respectively) and requires particular attention in isotope analysis. The carbon isotope composition shows comparably little variation around a value of -26.0 per mil. The positive values of the Holocene and the Late

  15. The formation and evolution of Hule and Río Cuarto maars, Costa Rica

    NASA Astrophysics Data System (ADS)

    Alvarado, Guillermo E.; Soto, Gerardo J.; Salani, Flavia M.; Ruiz, Pablo; de Mendoza, Luis Hurtado

    2011-04-01

    to be 4.4 × 10 7 m 3, of which 0.008 m 3 correspond to DRE magma. The Hule and Río Cuarto maars are occupied by lakes and, in the last decades, several lake-overturn events have taken place, with a repeat cycle of six to seven years. The main outcome of these events has been the mass death of fish accompanied by changes in the lake color. In these systems, the hazard related to the possible occurrence of Nyos-type gas eruptions can be considered negligible or very local, but significant for tourists who camp by the lakes.

  16. Authigenic, detrital and diagenetic minerals in the Laguna Potrok Aike sediment sequence

    NASA Astrophysics Data System (ADS)

    Nuttin, L.; Francus, P.; Preda, M.; Ghaleb, B.; Hillaire-Marcel, C.

    2013-07-01

    The ˜100 m-long Laguna Potrok Aike sediment sequence yielded a record spanning the Last Glacial period to the Holocene. This paper presents and discusses two aspects of the mineralogy of the lake. The first aspect is based on a semi-quantitative X-ray diffraction analysis of bulk and clay mineralogical assemblages. Minor mineralogical changes are observed throughout the glacial section suggesting relatively uniform sediment sources. The transition into the Holocene is characterized by increasing fluxes of endogenic calcite thought to relate to lower lake levels. The second aspect is based on analysis of uranium-series disequilibria in diagenetic vivianite from the glacial section. U-series ages were expected to yield minimum ages for the host-sediment. Unfortunately, very little authigenic U is present in vivianite grains. The low primary productivity of the lake and thus low organic carbon fluxes might have prevented the development of strong redox gradients at the water-sediment interface and thus reduced diagenetic U-uptake into the sediment. One vivianite sample, at a 56.9 m composite depth, yielded enough authigenic uranium to calculate a 230Th-age of 29.4 ± 5.9 ka (±2σ). This age is younger than the one indicated by the radiocarbon chronology. It is thus concluded that a relatively late diagenetic evolution of the U-Th system characterizes the recovered vivianite minerals. The authigenic U displays a very high excess in 234U (over 238U) with an activity ratio of 4.58 ± 0.58 (±2σ). It suggests that it originates from the transfer of highly fractionated U from surrounding detrital minerals through very low U-content pore waters.

  17. The Randeck Maar: Facies development and habitat differentiation of a Miocene lacustrine system

    NASA Astrophysics Data System (ADS)

    Rasser, Michael W.; Kern, Andrea K.

    2015-04-01

    The Randeck Maar in S Germany is a well-known fossil lagerstätte (Early/Middle Miocene, MN5) with exceptionally preserved fossils. Although it is a locally restricted succession of lake sediments with a diameter of only 1200 m and less than 60 m of preserved sediments, it appears to comprise a complex structure with a high scientific potential on a global scale, because the lake sediments and their fossils can provide evidence for the impact of the Mid-Miocene Climatic Optimum (MMCO) on the environment and its organisms as well as the ecological interactions between animals and/or plants during that interval. No other European locality provides such a rich insight into an ecosystem that existed during the MMCO. Excavations of Staatliches Museum für Naturkunde Stuttgart provided new insights into the facies types of this maar lake. They showed that a high variety of facies types existed beside the traditional separation into a basal tuffitic development, followed by calcareous and bituminous ('dysodil') laminates, and terminal massive freshwater limestones. Palaeoenvironmental reconstructions are based on the mentioned excavations and re-evaluations of collection material. They show that the Randeck Maar was a typical maar lake with a rich flora and fauna. Based on all plant remains, the IPR vegetational analysis points towards subhumid sclerophyllous forests, suggesting seasonal drought. 380 taxa in all are known thus far, which are dominated by plants (168) and insects (79). The taxonomic re-evaluation combined with palaeoecological considerations allows for the reconstruction of a palaeoenvironmental model. In brief, three main sections can be differentiated for the habitats of the Randeck Maar lake system: (1) Deep- and open-water lake habitats with local and short-termed mass occurrences of insect larvae, amphibians, and/or gastropods, while fish are particularly scarce. The interpretation of the water chemistry is problematic because palaeoenvironmental

  18. Lateglacial and Holocene climatic changes in south-eastern Patagonia inferred from carbonate isotope records of Laguna Potrok Aike (Argentina)

    NASA Astrophysics Data System (ADS)

    Oehlerich, M.; Mayr, C.; Gussone, N.; Hahn, A.; Hölzl, S.; Lücke, A.; Ohlendorf, C.; Rummel, S.; Teichert, B. M. A.; Zolitschka, B.

    2015-04-01

    First results of strontium, calcium, carbon and oxygen isotope analyses of bulk carbonates from a 106 m long sediment record of Laguna Potrok Aike, located in southern Patagonia are presented. Morphological and isotopic investigations of μm-sized carbonate crystals in the sediment reveal an endogenic origin for the entire Holocene. During this time period the calcium carbonate record of Laguna Potrok Aike turned out to be most likely ikaite-derived. As ikaite precipitation in nature has only been observed in a narrow temperature window between 0 and 7 °C, the respective carbonate oxygen isotope ratios serve as a proxy of hydrological variations rather than of palaeotemperatures. We suggest that oxygen isotope ratios are sensitive to changes of the lake water balance induced by intensity variations of the Southern Hemisphere Westerlies and discuss the role of this wind belt as a driver for climate change in southern South America. In combination with other proxy records the evolution of westerly wind intensities is reconstructed. Our data suggest that weak SHW prevailed during the Lateglacial and the early Holocene, interrupted by an interval with strengthened Westerlies between 13.4 and 11.3 ka cal BP. Wind strength increased at 9.2 ka cal BP and significantly intensified until 7.0 ka cal BP. Subsequently, the wind intensity diminished and stabilised to conditions similar to present day after a period of reduced evaporation during the "Little Ice Age". Strontium isotopes (87Sr/86Sr ratio) were identified as a potential lake-level indicator and point to a lowering from overflow conditions during the Glacial (∼17 ka cal BP) to lowest lake levels around 8 ka cal BP. Thereafter the strontium isotope curve resembles the lake-level curve which is stepwise rising until the "Little Ice Age". The variability of the Ca isotope composition of the sediment reflects changes in the Ca budget of the lake, indicating higher degrees of Ca utilisation during the period with

  19. [Expression, purification of recombinant cationic peptide AIK in Escherichia coli and its antitumor activity].

    PubMed

    Fan, Fangfang; Sun, Huiying; Xu, Hui; Liu, Jiawei; Zhang, Haiyuan; Li, Yilan; Ning, Xuelian; Sun, Yue; Bai, Jing; Fu, Songbin; Zhou, Chunshui

    2015-12-01

    AIK is a novel cationic peptide with potential antitumor activity. In order to construct the AIK expression vector by Gateway technology, and establish an optimal expression and purification method for recombinant AIK, a set of primers containing AttB sites were designed and used to create the AttB-TEV-FLAG-AIR fusion gene by overlapping PCR. The resulting fusion gene was cloned into the donor vector pDONR223 by attB and attP mediated recombination (BP reaction), then, transferred into the destination vector pDESTl 5 by attL and attR mediated recombination (LR reaction). All the cloning was verified by both colony PCR and DNA sequencing. The BL21 F. coli transformed by the GST-AIR expression plasmid was used to express the GST-AIK fusion protein with IPTG induction and the induction conditions were optimized. GST-AIR fusion protein was purified by glutathione magnetic beads, followed by rTEV cleavage to remove GST tag and MTS assay to test the growth inhibition activity of the recombinant AIR on human leukemia HL-60 cells. We found that a high level of soluble expression of GST-AIK protein (more than 30% out of the total bacterial proteins) was achieved upon 0.1 mmol/L ITPG induction for 4 h at 37 °C in the transformed BL21 F. coli with starting OD₆₀₀ at 1.0. Through GST affinity purification and rTEV cleavage, the purity of the resulting recombinant AIK was greater than 95%. And the MTS assays on HL-60 cells confirmed that the recombinant AIK retains an antitumor activity at a level similar to the chemically synthesized AIK. Taken together, we have established a method for expression and purification of recombinant AIK with a potent activity against tumor cells, which will be beneficial for the large-scale production and application of recombinant AIK in the future. PMID:27093838

  20. OSL dating of a Pleistocene maar: Birket Ram, the Golan heights

    USGS Publications Warehouse

    Shaanan, U.; Porat, N.; Navon, O.; Weinberger, R.; Calvert, A.; Weinstein, Y.

    2011-01-01

    Direct dating of maars and their phreatomagmatic deposits is difficult due to the dominance of lithic (host rock) fragments and glassy particles of the juvenile magma. In this paper we demonstrate that optically stimulated luminescence (OSL) dating can be successfully used for age determination of phreatomagmatic deposits. We studied the tuff deposit of Birket Ram, a basanitic maar located at the northern edge of the Golan heights on the western Arabian plate. The maar is underlain by a thick section of Pleistocene basalts, and currently hosts a small lake. It is filled by approximately 90m of lacustrine sediments with radiocarbon ages extrapolated to 108ka at the base. OSL was applied to quartz grains extracted from tuffs and paleosols in order to set the time frame of the phreatomagmatism at the site. A maximum age constraint of 179??13ka was determined for a paleosol that underlies the maar ejecta. Quartz grains from two layers in the tuff section yielded a direct age of 129??6ka for the phreatomagmatic eruption. A younger age of 104??7ka, which was determined for a tuff layer underlying a basaltic flow, was attributed to thermal resetting during the lava emplacement. This was confirmed by an 40Ar/39Ar age of 101??3ka determined on the overlying basalt. The internal consistency of the OSL ages and the agreement with the 40Ar/39Ar age determination as well as with previous estimates demonstrates the potential of OSL for maar dating. ?? 2010 Elsevier B.V.

  1. Linking microbial assemblages to paleoenvironmental conditions from the Holocene and Last Glacial Maximum times in Laguna Potrok Aike sediments, Argentina

    NASA Astrophysics Data System (ADS)

    Vuillemin, Aurele; Ariztegui, Daniel; Leavitt, Peter R.; Bunting, Lynda

    2014-05-01

    Laguna Potrok Aike is a closed basin located in the southern hemisphere's mid-latitudes (52°S) where paleoenvironmental conditions were recorded as temporal sedimentary sequences resulting from variations in the regional hydrological regime and geology of the catchment. The interpretation of the limnogeological multiproxy record developed during the ICDP-PASADO project allowed the identification of contrasting time windows associated with the fluctuations of Southern Westerly Winds. In the framework of this project, a 100-m-long core was also dedicated to a detailed geomicrobiological study which aimed at a thorough investigation of the lacustrine subsurface biosphere. Indeed, aquatic sediments do not only record past climatic conditions, but also provide a wide range of ecological niches for microbes. In this context, the influence of environmental features upon microbial development and survival remained still unexplored for the deep lacustrine realm. Therefore, we investigated living microbes throughout the sedimentary sequence using in situ ATP assays and DAPI cell count. These results, compiled with pore water analysis, SEM microscopy of authigenic concretions and methane and fatty acid biogeochemistry, provided evidence for a sustained microbial activity in deep sediments and pinpointed the substantial role of microbial processes in modifying initial organic and mineral fractions. Finally, because the genetic material associated with microorganisms can be preserved in sediments over millennia, we extracted environmental DNA from Laguna Potrok Aike sediments and established 16S rRNA bacterial and archaeal clone libraries to better define the use of DNA-based techniques in reconstructing past environments. We focused on two sedimentary horizons both displaying in situ microbial activity, respectively corresponding to the Holocene and Last Glacial Maximum periods. Sequences recovered from the productive Holocene record revealed a microbial community adapted to

  2. The Maars of the Tuxtla Volcanic Field: the Example of 'laguna Pizatal'

    NASA Astrophysics Data System (ADS)

    Espindola, J.; Zamora-Camacho, A.; Hernandez-Cardona, A.; Alvarez del Castillo, E.; Godinez, M.

    2013-12-01

    Los Tuxtlas Volcanic Field (TVF), also known as Los Tuxtlas massif, is a structure of volcanic rocks rising conspicuously in the south-central part of the coastal plains of eastern Mexico. The TVF seems related to the upper cretaceous magmatism of the NW part of the Gulf's margin (e.g. San Carlos and Sierra de Tamaulipas alkaline complexes) rather than to the nearby Mexican Volcanic Belt. The volcanism in this field began in late Miocene and has continued in historical times, The TVF is composed of 4 large volcanoes (San Martin Tuxtla, San Martin Pajapan, Santa Marta, Cerro El Vigia), at least 365 volcanic cones and 43 maars. In this poster we present the distribution of the maars, their size and depths. These maars span from a few hundred km to almost 1 km in average diameter, and a few meters to several tens of meters in depth; most of them filled with lakes. As an example on the nature of these structures we present our results of the ongoing study of 'Laguna Pizatal or Pisatal' (18° 33'N, 95° 16.4'W, 428 masl) located some 3 km from the village of Reforma, on the western side of San Martin Tuxtla volcano. Laguna Pisatal is a maar some 500 meters in radius and a depth about 40 meters from the surrounding ground level. It is covered by a lake 200 m2 in extent fed by a spring discharging on its western side. We examined a succession of 15 layers on the margins of the maar, these layers are blast deposits of different sizes interbedded by surge deposits. Most of the contacts between layers are irregular; which suggests scouring during deposition of the upper beds. This in turn suggests that the layers were deposited in a rapid series of explosions, which mixed juvenile material with fragments of the preexisting bedrock. We were unable to find the extent of these deposits since the surrounding areas are nowadays sugar cane plantations and the lake has overspilled in several occassions.

  3. Tephra ring interpretation in light of evolving maar-diatreme concepts: Stracciacappa maar (central Italy)

    NASA Astrophysics Data System (ADS)

    Valentine, Greg A.; Sottili, Gianluca; Palladino, Danilo M.; Taddeucci, Jacopo

    2015-12-01

    Maar-diatreme volcanoes in their simplest form are thought to result primarily from discrete, subsurface phreatomagmatic explosions. Tephra ring deposits around maar craters are commonly interpreted in terms of a framework wherein explosions begin at shallow levels and migrate downward, ejecting progressively deeper-seated lithic clasts that contribute to the tephra rings. Additionally, variations in grain size of the deposits are sometimes inferred to record different degrees of fragmentation, which are in turn related to variations in magma-water ratios at the explosion sites. Recent detailed studies of diatremes and of maar tephra rings suggest a different conceptual model wherein explosions can happen at various vertical and lateral locations within a diatreme during its eruptive lifetime, rather than being limited to simple downward migration. Experiments, numerical modeling, and field data indicate that most explosions deeper than about 200-250 m will not vent to the surface, but instead contribute to mixing within the diatremes. Arrival of deep-seated lithics at the surface is related to this mixing process. Experiments also indicate that explosion phenomena can result in a range of emplacement mechanisms and grain sizes in tephra rings, even in the absence of variations in explosion mechanisms (fragmentation efficiency). Here we document the tephra ring of Stracciacappa maar (central Italy), and interpret its eruption and emplacement history in terms of evolving conceptual models along with a comparison to more traditional interpretations. Because most elements of both conceptual models are viable, the work points to an important need to develop criteria to distinguish between the various inferred mechanisms.

  4. Qal'eh Hasan Ali maars, central Iran.

    USGS Publications Warehouse

    Milton, D.J.

    1976-01-01

    This group of some 15 Late Quaternary explosion craters are typical maars, with rims of bedded pyroclastics. In all but the largest crater, the deposits consist entirely of clasts of country rock (granodiorite and Eocene volcanics). The maars were formed by phreatomagmatic explosions, possibly caused by groundwater originating from a major river. The deposits of the largest maar contain up to 20% juvenile fragments of two types. Tephrite clasts have phenocrysts of phlogopite, clinopyroxene, olivine and anorthoclase; the presence of hauyne as a groundmass phase is notable. Cumulate blocks of phlogopite-clinopyroxene rock also occur. The maar field is part of a distinct province of Quaternary alkaline volcanism, related to a major crustal fracture - the N-S-trending Nayband fault.-R.J.S.

  5. Magnetic parameters and their palaeoclimatic implications—the sediment record of the last 15 500 cal. BP from Laguna Potrok Aike (Argentina)

    NASA Astrophysics Data System (ADS)

    Irurzun, M. A.; Orgeira, M. J.; Gogorza, C. S. G.; Sinito, A. M.; Compagnucci, R.; Zolitschka, B.

    2014-08-01

    Lake sediments are excellent sources of palaeoenvironmental and palaeoclimatic information because they provide continuous and high-resolution records. South America is of particular interest because it is the only landmass that stretches southward into the Pacific and Atlantic Oceans towards Antarctica. The aim of this study is to explore the relationship of magnetic parameters with elemental and palaeobiological data of Laguna Potrok Aike to develop a model of lake-level changes and related hydrological and climatic fluctuations. Magnetic measurements were performed on subsamples from 15 500 cal. BP to the present, and associated rock magnetic parameters were calculated to infer magnetic mineralogy, concentration and grain size. According to the model, parameters dependent on magnetic concentration and grain size are directly related to lake-level changes. During dry periods, the remanent coercivity displays high values, whereas the proportion of magnetite is relatively low. Low percentages of greigite are observed, indicating that the water of the lake was stratified at least four times during the studied period, at approximately 10 300, 8900, 8500 and 8300 cal. BP. The preservation of greigite by inhibiting its complete transformation into pyrite is associated with a rapid burial that occurs with high sedimentation rates. Thermal stratification could be caused by a slight cooling in the area triggered by a weakening of the Westerlies and/or low activity of the sun, sum to the effect of a flood of melt water in the North Atlantic.

  6. Recording of climate and diagenesis through fossil pigments and sedimentary DNA at Laguna Potrok Aike, Argentina

    NASA Astrophysics Data System (ADS)

    Vuillemin, A.; Ariztegui, D.; Leavitt, P. R.; Bunting, L.; Pasado Science Team

    2015-11-01

    Aquatic sediments record past climatic conditions while providing a wide range of ecological niches for microorganisms. Although marine sedimentary microbial assemblages are often defined by their surrounding geochemical conditions, the influence of environmental features upon microbial development and post-depositional survival remains largely unknown in the lacustrine realm. Due to long-term microbial activity, the composition of environmental DNA can be expected to evolve with sediment depth and over time and therefore should reflect both ancient and extant microbial populations, but this hypothesis has rarely been tested using a multiproxy approach. Here geomicrobiological and phylogenetic analyses of a Patagonian maar lake were used to indicate that the different sedimentary microbial assemblages derive from specific lacustrine regimes during defined climatic periods. Two well defined climatic intervals whose sediments harboured active microbial populations and measurable ATP were sampled for a comparative environmental study based on fossil pigments and 16S rRNA gene sequences. Bacterial and archaeal 16S rRNA gene sequences recovered from the Holocene record revealed a microbial community adapted to subsaline conditions actively producing methane during organic matter degradation. These characteristics were associated with sediments resulting from endorheic lake conditions with high evaporative stress and concomitant high algal productivity. Moreover, archaeal clone libraries established throughout the Holocene record indicate an age-related stratification of these populations, consistent with a gradual use of organic substrates after deposition. In contrast, sulphate-reducing bacteria and lithotrophic Archaea were predominant in sediments dated from the Last Glacial Maximum, in which pelagic clays alternated with fine volcanic material characteristic of a lake level highstand and freshwater conditions, but reduced water column productivity. These patterns

  7. Recording of climate and diagenesis through sedimentary DNA and fossil pigments at Laguna Potrok Aike, Argentina

    NASA Astrophysics Data System (ADS)

    Vuillemin, Aurèle; Ariztegui, Daniel; Leavitt, Peter R.; Bunting, Lynda; The Pasado Science Team

    2016-04-01

    Aquatic sediments record past climatic conditions while providing a wide range of ecological niches for microorganisms. In theory, benthic microbial community composition should depend on environmental features and geochemical conditions of surrounding sediments, as well as ontogeny of the subsurface environment as sediment degraded. In principle, DNA in sediments should be composed of ancient and extant microbial elements persisting at different degrees of preservation, although to date few studies have quantified the relative influence of each factor in regulating final composition of total sedimentary DNA assemblage. Here geomicrobiological and phylogenetic analyses of a Patagonian maar lake were used to indicate that the different sedimentary microbial assemblages derive from specific lacustrine regimes during defined climatic periods. Two climatic intervals (Mid-Holocene, 5 ka BP; Last Glacial Maximum, 25 ka BP) whose sediments harbored active microbial populations were sampled for a comparative environmental study based on fossil pigments and 16S rRNA gene sequences. The genetic assemblage recovered from the Holocene record revealed a microbial community displaying metabolic complementarities that allowed prolonged degradation of organic matter to methane. The series of Archaea identified throughout the Holocene record indicated an age-related stratification of these populations brought on by environmental selection during early diagenesis. These characteristics were associated with sediments resulting from endorheic lake conditions and stable pelagic regime, high evaporative stress and concomitant high algal productivity. In contrast, sulphate-reducing bacteria and lithotrophic Archaea were predominant in sediments dated from the Last Glacial Maximum, in which pelagic clays alternated with fine volcanic material characteristic of a lake level highstand and freshwater conditions, but reduced water column productivity. Comparison of sedimentary DNA composition

  8. The ELSA - Flood - Stack: A reconstruction from the laminated sediments of Eifel Maar structures during the last 60 000 years

    NASA Astrophysics Data System (ADS)

    Brunck, Heiko; Sirocko, Frank; Albert, Johannes

    2016-04-01

    Lake sediments are excellent climate archives and can be used for reconstructions of past precipitation and flood events. However, until now, there is no continous flood record for the entire last 60 000 years for Central Europe. This study reconstructs the history of the main flood events in central Europe from event layers in sediment cores from Holocene Eifel maar lakes and Pleistocene dry maar structures. The cores were drilled in the Eifel region of western Germany. All maars have an inflow by a local stream and the largest flood events and associated suspension injections are nicely visible in the sediment. The specific sedimentation conditions explain the unique possibility to detect all 18 Greenland Interstadials in the total carbon concentration of the analysed maars. The allocation of the core material to all Greenland Interstadials and Stadials enables the exact climatic interpretation of the flood frequency. The stratigraphical concept leads to a classification of Landscape Evolution Zones in the Eifel region, which reconstruct the vegetation and the climate change (Sirocko et al., 2015). This classification is used to discuss the flood event succession concerning environmental changes. To study the past flood events in detail, 10 cm long thin sections were sedimentological and geochemical analysed to distinguish flood layers from turbidites and slumps. Turbidites have a continuous grain size gradation; the grains size profile of flood events is in contrast characterized by several grain size maxima over the entire layer thickness. A flood event over several days shows numerous peaks of intense discharge, which lead to a discontinuous grain size gradient. As a consequence, 233 flood layers over 7.5 mm thickness were detected. The main flood stages are from: 0 - 4000, 11 500 - 17 500, 23 000 - 24 000, 29 000 - 35 000 and 44 000 - 44 500 b2k (Brunck et al., 2015). Our time-series from the Eifel represents the first highly-resolved chronology for flood

  9. 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…

  10. The ELSA-Flood-Stack: A reconstruction from the laminated sediments of Eifel maar structures during the last 60 000 years

    NASA Astrophysics Data System (ADS)

    Brunck, H.; Sirocko, F.; Albert, J.

    2016-07-01

    This study reconstructs the main flood phases in central Europe from event layers in sediment cores from Holocene Eifel maar lakes and Pleistocene dry maar structures. These reconstructions are combined with recent gauge time-series to cover the entire precipitation extremes of the last 60 000 years. In general, Eifel maar sediments are perfectly suited for the preservation of event layers since the deep water in the maar lakes is seasonal anoxic and therefore, bioturbation is low. However, the preservation of annual lamination is only preserved in Holzmaar and Ulmener Maar; the other cores are dated by 14C, magnetostratigraphy, tephra markers and ice core tuning. The cores were drilled in the Eifel region of central western Germany, which represents a climatic homogenous region from Belgium to Poland and all across Central Europe. A total of 233 flood layers over 7.5 mm were detected in all analysed cores. The stratigraphic classification of the flood events follows the newly defined Landscape Evolution Zones (LEZ). The strongest events in the Holocene have occurred during LEZ 1 (0-6000 b2k) in the years 658, 2800 and 4100 b2k. Flood layers in the LEZ 2 (6000-10 500 b2k) are not as frequent as during the LEZ 1, nevertheless, the floods cluster between 6000 and 6500 b2k. Twenty flood layers are found in the LEZ 3 (10 500-14 700 b2k); 11 in LEZ 4 (14 700-21 000 b2k); 15 in LEZ 5 (21 000-28 500 b2k); 34 in LEZ 6 (28 500-36 500 b2k); 8 in LEZ 7 (36 500-49 000 b2k); zero in LEZ 8 (49 000-55 000 b2k) and LEZ 9 (55 000-60 000 b2k). The maximum flood phases during the Pleistocene are at 11 500-17 500 (late glacial and Younger Dryas), 23 000-24 000 (before Greenland Interstadial (GI) 2), 29 000-35 000 (especially between GI 5 and 4) and 44 000-44 500 b2k (transition from GI 12 to 11). The variations in flood dynamics are climatically driven and mainly associated with climate transitions and colder periods, combined with light vegetation. It turns out that low vegetation

  11. Late Glacial vegetation reconstruction based on leaf waxes from the Gemündener Maar, Germany

    NASA Astrophysics Data System (ADS)

    Wüthrich, Lorenz; Lutz, Selina; Zech, Michael; Hepp, Johannes; Sirocko, Frank; Zech, Roland

    2015-04-01

    Lake sediments are valuable archives for the reconstruction of past changes in climate and vegetation. In the present study, we analyse samples from the Gemündener Maar, a lake situated in the western Eiffel, Germany, for their leaf wax composition: In the bottom part of the core, corresponding to the Oldest Dryas (i.e. older than ~15 ka), n-alkanes have a high average chain length (ACL), which points to a vegetation dominated by grass. During the Bölling/Alleröd, a decrease of the ACL can be interpreted as signal of more deciduous trees. During the Younger Dryas (~12.8 to 11.5 ka), the ACL increases again. Trees probably became again less abundant, before finally, the ACL records the return of deciduous trees during the early Holocene. In general, the total concentrations of both, n-alkanes and sugar biomarkers are high enough to measure compound-specific isotopes on n-alkanes (deuterium) and sugars (18-O). Combined, these two isotopes might help to obtain more information about the relative humidity and mean air temperature during the late glacial.

  12. Recombinant Measles AIK-C Vaccine Strain Expressing the prM-E Antigen of Japanese Encephalitis Virus

    PubMed Central

    Higuchi, Akira; Toriniwa, Hiroko; Komiya, Tomoyoshi; Nakayama, Tetsuo

    2016-01-01

    An inactivated Japanese encephalitis virus (JEV) vaccine, which induces neutralizing antibodies, has been used for many years in Japan. In the present study, the JEV prM-E protein gene was cloned, inserted at the P/M junction of measles AIK-C cDNA, and an infectious virus was recovered. The JEV E protein was expressed in B95a cells infected with the recombinant virus. Cotton rats were inoculated with recombinant virus. Measles PA antibodies were detected three weeks after immunization. Neutralizing antibodies against JEV developed one week after inoculation, and EIA antibodies were detected three weeks after immunization. The measles AIK-C-based recombinant virus simultaneously induced measles and JEV immune responses, and may be a candidate for infant vaccines. Therefore, the present strategy of recombinant viruses based on a measles vaccine vector would be applicable to the platform for vaccine development. PMID:26930411

  13. High level triggers for explosive mafic volcanism: Albano Maar, Italy

    NASA Astrophysics Data System (ADS)

    Cross, J. K.; Tomlinson, E. L.; Giordano, G.; Smith, V. C.; De Benedetti, A. A.; Roberge, J.; Manning, C. J.; Wulf, S.; Menzies, M. A.

    2014-03-01

    Colli Albani is a quiescent caldera complex located within the Roman Magmatic Province (RMP), Italy. The recent Via dei Laghi phreatomagmatic eruptions led to the formation of nested maars. Albano Maar is the largest and has erupted seven times between ca 69-33 ka. The highly explosive nature of the Albano Maar eruptions is at odds with the predominant relatively mafic (SiO2 = 48-52 wt.%) foiditic (K2O = 9 wt.%) composition of the magma. The deposits have been previously interpreted as phreatomagmatic, however they contain large amounts (up to 30%vol) of deep seated xenoliths, skarns and all pre-volcanic subsurface units. All of the xenoliths have been excavated from depths of up to 6 km, rather than being limited to the depth at which magma and water interaction is likely to have occurred, suggesting an alternative trigger for eruption. High precision geochemical glass and mineral data of fresh juvenile (magmatic) clasts from the small volume explosive deposits indicate that the magmas have evolved along one of two evolutionary paths towards foidite or phonolite. The foiditic melts record ca. 50% mixing between the most primitive magma and Ca-rich melt, late stage prior to eruption. A major result of our study is finding that the generation of Ca-rich melts via assimilation of limestone, may provide storage for significant amounts of CO2 that can be released during a mixing event with silicate magma. Differences in melt evolution are inferred as having been controlled by variations in storage conditions: residence time and magma volume.

  14. Precipitation origin and evaporation of lakes in semi-arid Patagonia (Argentina) inferred from stable isotopes ( δ18O, δ2H)

    NASA Astrophysics Data System (ADS)

    Mayr, Christoph; Lücke, Andreas; Stichler, Willibald; Trimborn, Peter; Ercolano, Bettina; Oliva, Gabriel; Ohlendorf, Christian; Soto, Julio; Fey, Michael; Haberzettl, Torsten; Janssen, Stephanie; Schäbitz, Frank; Schleser, Gerhard H.; Wille, Michael; Zolitschka, Bernd

    2007-02-01

    Stable isotope approaches are often used for estimating water balances of lakes. Such studies require regional background information about hydrogen and oxygen isotope variability of lakes and their potential inflows. Here, a stable isotope database ( δ2H and δ18O) is presented for estimating evaporation to inflow ratios ( E/ I) of lakes in semi-arid southern Patagonia. Water samples of 23 lakes and ponds located in the Patagonian steppe at about 52°S were sampled during three subsequent austral summers. Two deep crater lakes, Laguna Azul and Laguna Potrok Aike, were studied in more detail during a two-years monitoring. Furthermore, precipitation, groundwater and atmospheric water vapor were sampled for isotope analyses. Presented data imply that the isotopic composition of rainfall in southeastern Patagonia is predominantly determined by precipitation amount and moisture source area. For the investigated area, the first meteoric water and evaporation lines in δ2H vs. δ18O space are presented. The database was further used to estimate the water balances of the two crater lakes, Laguna Azul and Laguna Potrok Aike, which are in the focus of recent paleoclimatic investigations. According to that approach about 50% and 60%, respectively, of the water entering Laguna Azul and Laguna Potrok Aike via surface and subsurface inflow evaporates. These results testify a considerable flow of lake waters into the groundwater.

  15. Alberca De Guadalupe Maar Crater, Zacapu Basin : A Rare Type of Volcano within the Michoacán-Guanajuato Volcanic Field, México

    NASA Astrophysics Data System (ADS)

    Kshirsagar, P. V.; Siebe, C.; Guilbaud, M. N.; Salinas, S.

    2014-12-01

    Phreato-magmatic vents (esp. maar craters) are rare in the ~40,000 Km2 Plio-Quaternary monogenetic Michoacán-Guanajuato Volcanic Field (MGVF) located in the central part of the Mexican Volcanic Belt. In contrast to >1000 scoria cones, only 2 dozen phreato-magmatic monogenetic vents (e.g. tuff cones, tuff rings, and maars) have been identified. About half of these form a cluster near Valle de Santiago in the Lerma river valley at the northern margin of the MGVF, while the others occur in a rather scattered fashion. Here we discuss the origin of Alberca de Guadalupe maar crater, one of the three phreato-magmatic vents (in addition to El Caracol and Alberca de Los Espinos) that occur within the boundaries of the inter-montane lacustrine Zacapu basin, a tectonic graben bound by an ENE-WSW normal fault system. The maar crater came into existence between 20,000 and 23,000 y BP, forming a 140 m deep hole in the otherwise planar surrounding ground of theearly Pleistocene lava flows of Cerro Pelón.The maar crater has a diameter of ~1 Km and bears a 9 m deep lake. Eruptive products include typical surge deposits that are best exposed around the rim and inner crater walls. They are poorly sorted (Mdø= -1.56 to -3.75, ø= 1.43 to 3.23), rich in accidental lithics (angular andesitic lava and ignimbrite clasts) constituting 51-88% of the deposit with few juveniles (basaltic andesite with phenocrysts of plagioclase, olivine, and pyroxene in a quenched glassy matrix; SiO2=54-58 wt. %). Dry surge units are friable and clast-supported, in contrast the wet surge units are fairly indurated and bear accretionary lapilli. Bedding is frequently distorted by ballistic impact-sag structures. The entire construct is disrupted by an E-W trending regional fault, downthrowing the northern part by ~30 m.The unusual formation of this maar crater in the semi-arid highlands of Zacapu was favored by the local hydrological and topographical conditions. Such conditions still prevail in several

  16. Late Pleistocene Alberca de Guadalupe maar volcano (Zacapu basin, Michoacán): Stratigraphy, tectonic setting, and paleo-hydrogeological environment

    NASA Astrophysics Data System (ADS)

    Kshirsagar, Pooja; Siebe, Claus; Guilbaud, Marie Noëlle; Salinas, Sergio; Layer, Paul W.

    2015-10-01

    The Late Pleistocene (~ 21,000 yr BP) Alberca de Guadalupe maar is one of the few phreatomagmatic volcanoes occurring within the scoria-cone dominated Plio-Quaternary Michoacán-Guanajuato Volcanic Field. The scarcity of this type of volcano implies that conditions favoring their formation are rarely met in this region. We identify these factors by implementing current methods of investigation with emphasis on hydrogeological conditions. We present the stratigraphy (including a set of 40Ar/39Ar and 14C dates) of the SE margin of the Zacapu intermontane tectonic basin, where the maar just forms a hole (~ 1 km in diameter, ~ 150 m deep, bearing a ~ 9 m deep lake) in the otherwise planar topography of the underlying early Pleistocene lava flows of the Cerro Pelón scoria cone. The maar is composed of typical phreatomagmatic surge deposits that are poorly sorted and rich in accidental lithics (> 60 wt.% of the deposit) with few juveniles (basaltic andesite, SiO2 = 54-58 wt.%). The entire structure is cut by an ENE-WSW trending normal fault and is underlain by andesite lavas and silicic ignimbrites (partly inferred from xenoliths encountered in the maar deposits) that are Miocene to Early Pleistocene in age. The crater is at the center of a N-S elongated drainage basin surrounded by topographic highlands that channel water with high hydraulic pressure from most directions towards the location of the maar. This geometric configuration was already in existence at the time of the maar-forming eruption, but the climate was different. Colder and more humid conditions during the Last Glacial Maximum (Cw2-climate type, annual precipitation of > 1000 mm) favored the saturation of the fractured shallow aquifer system (hydraulic conductivity of 10- 8 to 10- 7 m/s) that supplied sufficient groundwater at a high flow rate directed towards the center of the basin. Upon contact near surface (< 200 m) with the rising dike of basaltic andesite magma, the continuous supply of both dike

  17. Towards the reconstruction of the shallow plumbing system of the Barombi Mbo Maar (Cameroon) Implications for diatreme growth processes of a polygenetic maar volcano

    NASA Astrophysics Data System (ADS)

    Chako Tchamabé, Boris; Ohba, Takeshi; Kereszturi, Gabor; Németh, Karoly; Aka, Festus Tongwa; Youmen, Dieudonné; Issa; Miyabuchi, Yasuo; Ooki, Seigo; Tanyileke, Gregory; Hell, Joseph Victor

    2015-08-01

    Understanding the mechanisms involved in the formation of maars and their diatreme growth processes has been a subject of contention. While there is no direct evidence of the presence of diatremes beneath most of the young maars, their existence is inferred based on the amount and type of country rocks excavated at different depths and deposited as pyroclastic ejecta around their craters. Properly tracing fragmented country rocks in ejecta to interpret their depths of origin and thus the depths of phreatomagmatic explosions require good and detailed information on the substrate geology that is generally lacking at many maars. As an alternative, this paper explores the role of juvenile components in deposits of a maar for understanding the cratering and growth of diatremes during maar-forming eruptions. Based on field investigations, pyroclast distribution, componentry and grain morphology examinations this study reports on the eruptive mechanisms that led to the formation of the Barombi Mbo Maar (BMM), a polygenetic maar volcano in Cameroon. The BMM consists of three diatremes that formed during distinct eruptive events and coalesced to produce an "amalgamated maar-diatreme". Two end-member types of eruption styles from the "dry" magmatic to the "wet" phreatomagmatic explosions governed the formation of the maar. In total, a minimum of ~ 0.0658 km3 of magma (Dense Rock Equivalent corrected) was ejected based on calculation by applying interpolation techniques on digital elevation models obtained from SRTM30m data corrected by rock textural data collected from the field. The distribution of juvenile clasts throughout the stratigraphic sequence suggests a complex subsurface eruptive process, which originated probably within the uppermost part of the diatreme. From the distribution and morphology of juvenile clasts in the deposits, it is inferred that cratering and country rock excavation during the growth of each of the small diatremes developed mainly from shallow

  18. Assessment of local seismic response of the Stracciacappa maar (Central Italy)

    NASA Astrophysics Data System (ADS)

    Moscatelli, Massimiliano; Simionato, Maurizio; Gaudiosi, Iolanda; Sottili, Gianluca; Pagliaroli, Alessandro; Sirianni, Pietro; Pileggi, Domenico; Avalle, Alessandra; Giallini, Silvia; Razzano, Roberto; Mancini, Marco; Vignaroli, Gianluca; Piscitelli, Sabatino; Bellanova, Jessica; Calamita, Giuseppe; Perrone, Angela; Lanzo, Giuseppe

    2016-04-01

    In this work, we face the definition of a subsoil model aimed at the local seismic response assessment of the Stracciacappa maar (Sabatini Volcanic District, central Italy) (e.g., De Rita and Zanetti, 1986; Marra et al., 2014). The pyroclastic succession of Stracciacappa records two main hydromagmatic eruptive phases ended about 0.09 Ma ago (e.g., Sottili et al., 2010). The preserved crater, with a diameter of about 1500 meters and a crater floor of about 30-40 m, hosted a lake until it was drained in AD 1834. In the framework of the cooperation between CNR IGAG and Italian Department of Civil Protection (DPC) of the Presidency of Council of Ministers (DPC funds 2014), a multidisciplinary approach including detailed stratigraphic and geophysical study has been carried out in the Stracciacappa maar and surrounding areas. New geological map and cross sections illustrate the complex geometric relationships between the thick pyroclastic surge succession, showing diffuse sandwave structures, and even meter-sized lava ballistic. A composite interdigitation between lacustrine and epiclastic debris sediments fills the crater floor. A continuous coring borehole was drilled inside the crater, 45 meters deep from the wellhead, with sampling of undisturbed samples. In addition, four MASW and one SCPTU test were carried out, in order to define the velocity profile of the s-waves within the lacustrine deposits. This Vs profile was then extended at higher depths by using the results of four 2D seismic passive arrays. Moreover, in order to define the resonance frequency of sedimentary covers via the HVSR technique, twenty-eight measurements were carried out with digital sensor Tromino® and seven measurements were performed with a Lennartz® Le-3D/5s sensor with Lennartz Marslite® digitizer. Finally, three electrical resistivity tomography tests, with a total length of about 3500 meters, were carried out with the purpose of constraining the subsoil model. Regarding the non linear

  19. ELSA flood stack for MIS 2-3 from dry maar lakestructure Auel (Eifel/Germany)

    NASA Astrophysics Data System (ADS)

    Brunck, Heiko; Sirocko, Frank

    2015-04-01

    Lacustrine sediments are very sensitive to natural and anthropogenically enviromental changes. Thus, lake sediments are excellent climate archives and can be used for reconstructions of past precipitation and flood events. However, until now, there is no continous flood record for the entire last 60 000 years for Central Europe. The present study reconstructs paleo floods from event layers in the sediment, of dry maar lakestructure Auel (Eifel). This silted up basin has an inflow by a local stream. Accordingly the sedimentation rate is directly linked to runoff activity. The bioturbation was low so that event layers become visible, but varves are not preserved. The maar site is near to the town of Gerolstein in the Eifel; the core AU2 was drilled in the ELSA (Eifel Laminated Sediment archive) project and is 123m long. AU2 has the highest sedimentation rate of all ELSA cores, due to abundant fluvial input. The Eifel area is well suited to approximate Central European weather, because modern water level gauge data from Eifel rivers correlate with respective data from the Rhine (Wernli and Pfahl, 2009). Due to the high inflow into the maar, Auel has the highest number of botanical macro remains of all ELSA cores. These specific conditions explain why only in AU2 all 21 Greenland interstadials can be observed in the abundance of wood remains and the organic carbon concentration. In a final stratigraphic step the time series of Corg was tuned to the Greenland ice core chronology to link the central European landscape evolution directly to the Greenland climate curve (Svensson et al., 2008). Combined sedimentological, paleobotanical and geochemical data received from AU2 builds the foundation of the 14C based chronology. The synchronisation of the record with other cores is controlled by tephra time markers and pollen. Both are used to align the main cores of the ELSA project and construct an integrated age model for the last 220 000 years [b2k] (Förster and Sirocko

  20. Maars to calderas: end-members on a spectrum of explosive volcanic depressions

    NASA Astrophysics Data System (ADS)

    Palladino, Danilo; Valentine, Greg; Sottili, Gianluca; Taddeucci, Jacopo

    2015-07-01

    We discuss maar-diatremes and calderas as end-members on a spectrum of negative volcanic landforms (depressions) produced by explosive eruptions (note - we focus on calderas formed during explosive eruptions, recognizing that some caldera types are not related to such activity). The former are dominated by ejection of material during numerous discrete phreatomagmatic explosions, brecciation, and subsidence of diatreme fill, while the latter are dominated by subsidence over a partly evacuated magma chamber during sustained, magmatic volatile-driven discharge. Many examples share characteristics of both, including landforms that are identified as maars but preserve deposits from non-phreatomagmatic explosive activity, and ambiguous structures that appear to be coalesced maars but that also produced sustained explosive eruptions with likely magma reservoir subsidence. A convergence of research directions on issues related to magma-water interaction and shallow reservoir mechanics is an important avenue toward developing a unified picture of the maar-diatreme-caldera spectrum.

  1. Eifel maars: Quantitative shape characterization of juvenile ash particles (Eifel Volcanic Field, Germany)

    NASA Astrophysics Data System (ADS)

    Rausch, Juanita; Grobéty, Bernard; Vonlanthen, Pierre

    2015-01-01

    The Eifel region in western central Germany is the type locality for maar volcanism, which is classically interpreted to be the result of explosive eruptions due to shallow interaction between magma and external water (i.e. phreatomagmatic eruptions). Sedimentary structures, deposit features and particle morphology found in many maar deposits of the West Eifel Volcanic Field (WEVF), in contrast to deposits in the East Eifel Volcanic Field (EEVF), lack the diagnostic criteria of typical phreatomagmatic deposits. The aim of this study was to determine quantitatively the shape of WEVF and EEVF maar ash particles in order to infer the governing eruption style in Eifel maar volcanoes. The quantitative shape characterization was done by analyzing fractal dimensions of particle contours (125-250 μm sieve fraction) obtained from Scanning electron microscopy (SEM) and SEM micro-computed tomography (SEM micro-CT) images. The fractal analysis (dilation method) and the fractal spectrum technique confirmed that the WEVF and EEVF maar particles have contrasting multifractal shapes. Whereas the low small-scale dimensions of EEVF particles (Eppelsberg Green Unit) coincide with previously published values for phreatomagmatic particles, the WEVF particles (Meerfelder Maar, Pulvermaar and Ulmener Maar) have larger values indicating more complex small-scale features, which are characteristic for magmatic particles. These quantitative results are strengthening the qualitative microscopic observations, that the studied WEVF maar eruptions are rather dominated by magmatic processes. The different eruption styles in the two volcanic fields can be explained by the different geological and hydrological settings found in both regions and the different chemical compositions of the magmas.

  2. Modern stromatolites in a saline maar in the Western District of Victoria, Australia: a possible analogue for Precambrian marine carbonates

    NASA Astrophysics Data System (ADS)

    Lynch, J. E.; Wallace, M. W.

    2011-12-01

    Stromatolites and thrombolites are microbially-mediated, sedimentary structures of various size and morphology, found throughout the rock record. Although they do not always contain fossils of microbial cells, ancient stromatolitic structures are considered biogenic in origin and, therefore, evidence of early life. Modern, living stromatolites are found in lacustrine and marine environments and can provide a window in which to observe some of Earth's earliest biological processes. However, secular variation in marine chemistry over geological time means that modern marine settings are not always the best analogues for ancient carbonates. This study describes the occurrence of modern stromatolites in a saline, alkaline maar in Victoria, Australia. Dolomite is a principle carbonate mineral precipitating from this lake, an unusual and poorly understood occurrence in modern environments, but one that was common in the Precambrian. The peculiar lacustrine chemistry in this volcanic region may, therefore, provide a better analogue for Precambrian marine carbonates than modern marine environments. Several types of stromatolites/thrombolites are observed occurring around this maar. Living thrombolites grow just below the shoreline to ~60 cm below the surface of the water. They are nucleating on the cemented surfaces of older lake carbonates, as well as cattle skulls and fence wires that have become submerged. Distinct microbial mats are observed, the uppermost being cyanobacteria, followed by purple sulfur bacteria, and underlain by sulfate reducing bacteria. Older exposed stromatolites are more consolidated and have a more clearly defined laminated and columnar morphology. The thickness ranges from a few to 15 cm and each column is up to a centimeter in diameter. Together these give the surface of the rock a "bubbly" appearance. Along the shore, a sandy-gravel composed of stromatolite remnants has formed, indicating that wind-generated surface waves of substantial

  3. Proceedings of the 2nd Columbia River Basalt Symposium: Maar volcanoes

    NASA Technical Reports Server (NTRS)

    Waters, A. C.; Fisher, R. V.

    1971-01-01

    Examination of maar-type volcanic cones, including tuff rings, from more than 40 localities in western North America indicates that water had access to volcano orifices during their activity. The most convincing evidence is the abundance of sideromelane (chilled basaltic glass) or its palagonitic decomposition products in the ejecta. Moreover, the volcanoes which were examined erupted in basins that either contained surface water, or else they grew above highly permeable aquifers at shallow dept. Characteristic features of maar ejecta are continuous thin beds, undulations and antidunes characteristic of base surge stratification, abundant accretionary lapilli or mud-armored rock particles, bedding sags that show soft sediment deformation, and in the subaqueous parts of the maar ramparts, great piles of subtly graded thin lenses of hyaloclastic debris.

  4. Stable hydrogen isotope ratios of methoxyl groups in Eifel (Germany) maar deposits: a potential palaeotemperature proxy

    NASA Astrophysics Data System (ADS)

    Anhäuser, Tobias; Sirocko, Frank; Greule, Markus; Esper, Jan; Keppler, Frank

    2014-05-01

    Stable hydrogen isotope ratios (δD values) of methoxyl groups in a variety of plant types from different locations have been shown to record δD values of precipitation, with a mean uniform isotopic fractionation. Since δD in precipitation is mainly influenced by climatic conditions, including temperature, evaporation and precipitation amount, methoxyl groups of organic matter have been proposed as a potential palaeoclimate proxy. We measured the δD values of the methoxyl groups in bulk sediment and oospores (algal spores from charophytes) from Eifel maar sediment core samples. The sediment cores cover the entire Holocene and part of the Late Glacial (9640 BC to ~12,000 BC). The methodology employed was precise with mean standard deviations of δD values of 3.3‰ (n = 12) and 1.3‰ (n = 3) for methoxyl groups of bulk sediment and oospore samples, respectively. Based on our measurements palaeoclimatic interpretations were made. Along a North-South transect of Europe δD values of precipitation and lake water are both strikingly correlated with the mean annual air temperature (R² = 0.99 and R² = 0.93, respectively), leading to a temperature gradient of 4-6‰ per 1° C. We used this gradient to calculate changes in temperature over the past ~14,000 years as indicated by changes in the δD values of the bulk sediment and oospores. Whereas the mean temperature variation within the Holocene was found to be consistently less than 2° C, the covered Late Glacial period indicates colder temperatures, by as much as 5° C, both with respect to the average Holocene temperature. The observed long term temperature trend is broadly in line with that reported from the NGRIP ice core for the same time period. δD values of methoxyl groups of bulk sediment are also consistent with those obtained from oospores. We suggest that the δD values of methoxyl groups from well-characterized organic material, especially in the case of oospores, have great potential to assist

  5. An investigation of volcanic depressions. Part 3: Maars, tuff-rings, tuff-cones, and diatremes

    NASA Technical Reports Server (NTRS)

    Lorenz, V.; Mcbirney, A. R.; Williams, H.

    1970-01-01

    A classification of maars, tuff-rings, tuff-cones, and diatremes is given along with a summary of their lithologic and structural characteristics at the surface and at depth, and their probable manner of formation. Particular emphasis is placed on the roles of fluidization and groundwater.

  6. Miocene honey bees from the Randeck Maar of southwestern Germany (Hymenoptera, Apidae)

    PubMed Central

    Kotthoff, Ulrich; Wappler, Torsten; Engel, Michael S.

    2011-01-01

    Abstract The Miocene Randeck Maar (southwestern Germany) is one of the only sites with abundant material of fossil honey bees. The fauna has been the focus of much scrutiny by early authors who recognized multiple species or subspecies within the fauna. The history of work on the Randeck Maar is briefly reviewed and these fossils placed into context with other Tertiary and living species of the genus Apis Linnaeus (Apinae: Apini). Previously unrecorded specimens from Randeck Maar were compared with earlier series in an attempt to evaluate the observed variation. A morphometric analysis of forewing venation angles across representative Recent and Tertiary species of Apis as well as various non-Apini controls was undertaken to evaluate the distribution of variation in fossil honey bees. The resulting dendrogram shows considerable variation concerning the wing venation of Miocene Apini, but intergradation of other morphological characters reveals no clear pattern of separate species. This suggests that a single, highly variable species was present in Europe during the Miocene. The pattern also supports the notion that the multiple species and subspecies proposed by earlier authors for the Randeck Maar honey bee fauna are not valid, and all are accordingly recognized as Apis armbrusteri Zeuner. PMID:21594072

  7. Eruptive history of the Barombi Mbo Maar, Cameroon Volcanic Line, Central Africa: Constraints from volcanic facies analysis

    NASA Astrophysics Data System (ADS)

    Tchamabé, Boris Chako; Youmen, Dieudonné; Owona, Sébastien; Issa; Ohba, Takeshi; Németh, Károly; Ngapna, Moussa Nsangou; Asaah, Asobo N. E.; Aka, Festus T.; Tanyileke, Gregory; Hell, Joseph V.

    2013-12-01

    his study presents the first and detail field investigations of exposed deposits at proximal sections of the Barombi Mbo Maar (BMM), NE Mt Cameroon, with the aim of documenting its past activity, providing insight on the stratigraphic distribution, depositional process, and evolution of the eruptive sequences during its formation. Field evidence reveals that the BMM deposit is about 126m thick, of which about 20m is buried lowermost under the lake level and covered by vegetation. Based on variation in pyroclastic facies within the deposit, it can be divided into three main stratigraphic units: U1, U2 and U3. Interpretation of these features indicates that U1 consists of alternating lapilli-ash-lapilli beds series, in which fallout derived individual lapilli-rich beds are demarcated by surges deposits made up of thin, fine-grained and consolidated ash-beds that are well-defined, well-sorted and laterally continuous in outcrop scale. U2, a pyroclastic fall-derived unit, shows crudely lenticular stratified scoriaceous layers, in which many fluidal and spindle bombs-rich lapilli-beds are separated by very thin, coarse-vesiculatedash-beds, overlain by a mantle xenolith- and accidental lithic-rich explosive breccia, and massive lapilli tuff and lapillistone. U3 displays a series of surges and pyroclastic fall layers. Emplacement processes were largely controlled by fallout deposition and turbulent diluted pyroclastic density currents under "dry" and "wet" conditions. The eruptive activity evolved in a series of initial phreatic eruptions, which gradually became phreatomagmatic, followed by a phreato-Strombolian and a violent phreatomagmatic fragmentation. A relatively long-time break, demonstrated by a paleosol between U2 and U3, would have permitted the feeding of the root zone or the prominent crater by the water that sustained the next eruptive episode, dominated by subsequent phreatomagmatic eruptions. These preliminary results require complementary studies, such as

  8. The ˜ 1245 yr BP Asososca maar: New advances on recent volcanic stratigraphy of Managua (Nicaragua) and hazard implications

    NASA Astrophysics Data System (ADS)

    Pardo, Natalia; Avellán, Denis Ramón; Macías, José Luis; Scolamacchia, Teresa; Rodríguez, Dionisio

    2008-10-01

    Asososca maar is located at the western outskirts of Managua, Nicaragua, in the central part of the active, N-S trending and right-lateral Nejapa-Miraflores fault that marks an offset of the Middle America Volcanic Arc. It constitutes one of the ˜ 21 vents aligned along the fault, between the Chiltepe Volcanic Complex to the North and Ticomo vents to the South. Asososca consists of an East-West elongated crater filled by a lake, which is currently used for supplying part of Managua with drinking water (10% of the capital city demand). The crater excavated the previous topography, allowing the observation of a detailed Holocene stratigraphic record that should be taken into account for future hazard analyses. We present a geological map together with the detailed stratigraphy exposed inside and around Asososca crater aided by radiocarbon dating of paleosols. The pre-existing volcanic sequence excavated by Asososca is younger than 12,730 + 255/- 250 yr BP and is capped by the phreato-plinian Masaya Tuff (< 2000 yr BP). The pyroclastic deposits produced by Asososca maar (Asososca Tephra, in this work) display an asymmetric distribution around the crater and overlie the Masaya Tuff. The bulk of the Asososca Tephra is made of several bedsets consisting of massive to crudely stratified beds of blocks and lapilli at the base, and superimposed thinly stratified ash and lapilli beds with dune structures and impact sags. Coarser size-fractions (>- 2 ϕ) are dominated by accidental clasts, including basaltic to basaltic-andesitic, olivine-bearing scoriae lapilli, porphyritic and hypocrystalline andesite blocks and lapilli, altered pumice lapilli and ash, and ignimbrite fragments. Juvenile fragments were only identified in size-fractions smaller than - 1 ϕ in proportions lower than 25%, and consist of black moss-like, fused-shape, and poorly vesiculated, fresh glass fragments of basaltic composition (SiO 2 ˜ 48%). The Asososca Tephra is interpreted as due to the emplacement

  9. The ELSA-Vegetation-Stack: Reconstruction of Landscape Evolution Zones (LEZ) from laminated Eifel maar sediments of the last 60,000 years

    NASA Astrophysics Data System (ADS)

    Sirocko, F.; Knapp, H.; Dreher, F.; Förster, M. W.; Albert, J.; Brunck, H.; Veres, D.; Dietrich, S.; Zech, M.; Hambach, U.; Röhner, M.; Rudert, S.; Schwibus, K.; Adams, C.; Sigl, P.

    2016-07-01

    Laminated sediment records from several maar lakes and dry maar lakes of the Eifel (Germany) reveal the history of climate, weather, environment, vegetation, and land use in central Europe during the last 60,000 years. The time series of the last 30,000 years is based on a continuous varve counted chronology, the MIS3 section is tuned to the Greenland ice - both with independent age control from 14C dates. Total carbon, pollen and plant macrofossils are used to synthesize a vegetation-stack, which is used together with the stacks from seasonal varve formation, flood layers, eolian dust content and volcanic tephra layers to define Landscape Evolution Zones (LEZ). LEZ 1 encompasses the landscape dynamics of the last 6000 years with widespread human influence. The natural oak and hazel forests of the early Holocene back to 10,500 b2k define LEZ 2. LEZ 3, the late glacial between 10,500 and 14,700 b2k, shows the development of a boreal forest with abundant grass and shallow water biomass in the lakes. The maximum of the last glaciation (LEZ 4: 14,700-23,000 b2k) was characterized by sparse vegetation of moss and characeae. These sediments are generally devoid of clay and sand and reveal no indication of snow-meltwater events. Accordingly, the Last Glacial Maximum (LGM) must have been extremely arid in central Europe. The sediments of the subsequent LEZ 5 from 23,000-28,500 b2k preserve distinct layers of clay and coarse sand, which indicates running water with clay in suspension and ephemeral coarse-grained fluvial sediment discharge. Abundant Ranunculaceae macroremains (used for 14C dating), insects, moss and fungi sclerotia reflect a tundra environment during a time of frequent strong snowmelt events. Total carbon content, Betula-Pinus pollen and diatoms reach increased concentrations during Marine Isotope Stage (MIS) 3 interstadials that occurred between 28,500 and 36,500 b2k (LEZ 6). The entire MIS3 interstadials are well documented in the organic carbon record

  10. The Chon Aike province of Patagonia and related rocks in West Antarctica: A silicic large igneous province

    NASA Astrophysics Data System (ADS)

    Pankhurst, R. J.; Leat, P. T.; Sruoga, P.; Rapela, C. W.; Márquez, M.; Storey, B. C.; Riley, T. R.

    1998-04-01

    The field occurrence, age, classification and geochemistry of the Mesozoic volcanic rocks of Patagonia and West Antarctica are reviewed, using published and new information. Dominated by rhyolitic ignimbrites, which form a bimodal association with minor mafic and intermediate lavas, these constitute one of the largest silicic igneous provinces known, equivalent in size to many mafic LIPs. Diachronism is recognized between the Early-Middle Jurassic volcanism of eastern Patagonia (Marifil and Chon Aike formations) and the Middle Jurassic-earliest Cretaceous volcanism of the Andean Cordillera (El Quemado, Ibañez and Tobı´fera formations). This is accompanied by a change in geochemical characteristics, from relatively high-Zr and -Nb types in the east to subalkaline arc-related rocks in the west, although the predominance of rhyolites remains a constant factor. All of the associated mafic rocks are well fractionated compared to direct mantle derivatives. Petrogenetic models favour partial melting of immature lower crust as a result of the intrusion of basaltic magmas, possibly with some hybridisation of the liquids and subsequent fractionation by crystal settling or solidification and remelting. The formation of large amounts of intracrustal silicic melt acted as a density barrier against the further rise of mafic magmas, which are thus rare in the province.

  11. The effects of the host-substrate properties on maar-diatreme volcanoes: experimental evidence

    NASA Astrophysics Data System (ADS)

    Macorps, Élodie; Graettinger, Alison H.; Valentine, Greg A.; Ross, Pierre-Simon; White, James D. L.; Sonder, Ingo

    2016-04-01

    While the relationship between the host-substrate properties and the formation of maar-diatreme volcanoes have been investigated in the past, it remains poorly understood. In order to establish the effects of the qualitative host-substrate properties on crater depth, diameter, morphological features, and sub-surface structures, we present a comparison of four campaigns of experiments that used small chemical explosives buried in various geological media to simulate the formation of maar-diatremes. Previous results from these experiments have shown that primary variations in craters and sub-surface structures are related to the scaled depth (physical depth divided by cube root of blast energy). Our study reveals that single explosions at optimal scaled depths in stronger host materials create the largest and deepest craters with steep walls and the highest crater rims. For single explosions at deeper than optimal scaled depths, the influence of material strength is less obvious and non-linear for crater depth, and non-existent for crater diameter, within the range of the experiments. For secondary and tertiary blasts, there are no apparent relationships between the material properties and the crater parameters. Instead, the presence of pre-existing craters influences the crater evolution. A general weakening of the materials after successive explosions can be observed, suggesting a possible decrease in the host-substrate influence even at optimal scaled depth. The results suggest that the influence of the host-substrate properties is important only in the early stage of a maar-diatreme (neglecting post-eruptive slumping into the open crater) and decreases as explosion numbers increase. Since maar-diatremes reflect eruptive histories that involve tens to hundreds of individual explosions, the influence of initial substrate properties on initial crater processes could potentially be completely lost in a natural system.

  12. A geophysical comparison of the diatremes of simple and complex maar volcanoes, Newer Volcanics Province, south-eastern Australia

    NASA Astrophysics Data System (ADS)

    Blaikie, T. N.; Ailleres, L.; Betts, P. G.; Cas, R. A. F.

    2014-04-01

    Geophysical modelling techniques are applied to examine and compare the subsurface morphology of maar volcanoes within the Newer Volcanics Province to better understand their eruptive histories and the hazards associated with future eruptions within the province. The maar volcanoes under investigation include the Ecklin and Anakie maars, and the Red Rock and Mount Leura Volcanic Complexes, which vary in their complexity, morphology, eruptive styles and host rock type. The Ecklin and Anakie maars display relatively simple geophysical signatures. Long wavelength gravity lows with corresponding magnetic highs are observed across the craters and were reproduced' during modelling with the presence of a shallow maar-diatreme at Anakie and two coalesced diatremes containing denser central vents at Ecklin. Red Rock and Mount Leura have more complex geophysical signatures, consisting of short wavelength gravity and magnetic highs superimposed on longer wavelength gravity lows. These anomalies are reproduced during modelling with coalesced ‘bowl shaped' diatremes containing dykes and magma ponds. The complex diatreme geometries revealed from forward and inverse modelling suggest that the eruption histories of these volcanoes are more complex than their morphology would suggest. Multiple coalesced diatreme structures indicate an eruption involving vent migration, while preserved dykes within the diatreme suggest short-lived fluctuations between phreatomagmatic and magmatic eruption styles. The geometry of the diatremes is consistent with maars hosted in a soft-substrate, which likely contributed to the migration of vents observed at Ecklin, Red Rock, and Mt Leura. The shallow diatreme observed within the Anakie maar is attributed to a short-lived eruption and low water content within the granitic host rock.

  13. Base surge deposits, eruption history, and depositional processes of a wet phreatomagmatic volcano in Central Anatolia (Cora Maar)

    NASA Astrophysics Data System (ADS)

    Gençalioğlu-Kuşcu, Gonca; Atilla, Cüneyt; Cas, Ray A. F.; Kuşcu, İlkay

    2007-01-01

    Cora Maar is a Quaternary volcano located to the 20 km northwest of Mount Erciyes, the largest of the 19 polygenetic volcanic complexes of the Cappadocian Volcanic Province in central Anatolia. Cora Maar is a typical example of a maar-diatreme volcano with a nearly circular crater with a mean diameter of c.1.2 km, and a well-bedded base surge-dominated maar rim tephra sequence up to 40 m in thickness. Having a diameter/depth ratio ( D/ d) of 12, Cora is a relatively "mature" maar compared to recent maar craters in the world. Cora crater is excavated within the andesitic lava flows of Quaternary age. The tephra sequence is not indurated, and consists of juvenile clasts up to 70 cm, non-juvenile clasts up to 130 cm, accretionary lapilli up to 1.2 cm in diameter, and ash to lapilli-sized tephra. Base surge layers display well-developed antidune structures indicating the direction of the transport. Both progressive and regressive dune structures are present within the tephra sequence. Wavelength values increase with increasing wave height, and with large wavelength and height values. Cora tephra display similarities to Taal and Laacher See base surge deposits. Impact sags and small channel structures are also common. Lateral and vertical facies changes are observed for the dune bedded and planar bedsets. According to granulometric analyses, Cora Maar tephra samples display a bimodal distribution with a wide range of Md φ values, characteristic for the surge deposits. Very poorly sorted, bimodal ash deposits generally vary from coarse tail to fine tail grading depending on the grain size distribution while very poorly sorted lapilli and block-rich deposits display a positive skewness due to fine tail grading.

  14. Heavy metals in eight edible fish species from two polluted tributaries (Aik and Palkhu) of the River Chenab, Pakistan.

    PubMed

    Qadir, Abdul; Malik, Riffat Naseem

    2011-12-01

    Concentration of heavy metals (lead (Pb), cadmium (Cd), chromium (Cr), and copper (Cu)) was determined in the liver, gills, kidneys, and muscles of eight edible fish species (Channa punctata, Cirrhinus reba, Labeo rohita, Heteropneustes fossilis, Mystus cavasius, Oreochromis niloticus, Puntius sophore, and Wallago attu) from upstream and downstream zones of the Nullah Aik and Palkhu tributaries of the River Chenab located in the Sialkot district known for its tanning industries worldwide. The pattern of metal accumulation in studied organs was in the order: Cr > Pb > Cu > Cd. Liver showed greater metal accumulation, followed by gills, kidneys, and muscles. Accumulation of Pb and Cr was significantly different in organs between upstream and downstream zones. Accumulation was greater in fish species dwelling downstream, indicating impairment of ambient stream water due to untreated discharge of industrial and municipal effluents into studied streams. Highest concentration of Pb and Cr and lowest of Cd was detected in H. fossilis whereas Cu showed higher concentration and Cr lowest concentration in P. sophore. In contrast, lower concentration of Pb and Cu was recorded in M. cavasius, O. niloticus, and W. attu. Mean concentrations of Cd, Cr, and Cu were higher in pre-monsoon compared to post-monsoon season. Measured concentrations of Pb, Cd, and Cr in muscles of species such as C. punctata, W. attu, L. rohita, P. sophore, and O. niloticus were above permissible limits of heavy metals for human consumption, indicating potential health risks. Therefore, these fish species from studied locations should be avoided for human diet. PMID:21424780

  15. Titanium and oxygen isotope diffusion in quartz-phenocrysts from a Jurassic rhyolite, Chon Aike Province (Fitz Roy, Patagonia)

    NASA Astrophysics Data System (ADS)

    Seitz, S.; Putlitz, B.; Baumgartner, L. P.; Escrig, S.; Meibom, A.; Leresche, S.; Vennemann, T. W.

    2014-12-01

    The volcanic El Quemado Complex was deposited during the breakup of Gondwana during the Middle and Late Jurassic. It is part of a large silicic igneous province, which includes the Chon Aike Province in Southern Patagonia and related rocks from the Antarctic Peninsula [1]. The Complex consists of rhyolitic and dacitic ignimbrites and air-fall tuffs, intercalated with andesitic to rhyolitic lava flows. New LA-ICPMS U/Pb-dates of zircons from the Fitz Roy area yield ages between 148 and 153Ma. No inherited zircons were found, suggesting that the temperature of 850°C calculated from zircon saturation is a minimum temperature. Lava flows are typically rich in quartz phenocrysts, which preserved magmatic trace element zoning, as revealed by cathodoluminescence (CL): light cores are surrounded by several darker and lighter zones towards the rim. The δ18O-values for quartz of between 11 to 14 ‰ are compatible with a crustal source for the magma and the SIMS analyses of phenocrysts reveal no zoning in O-isotope compositions. High-resolution Ti-profiles were obtained by NanoSIMS with a beam size of ~200 nm and a minimum step size of ~120 nm. Several lines perpendicular to the magmatic zoning of the quartz-phenocrysts were measured. The profiles show sharp changes in the 48Ti/29Si-ratio over a distance of 5 μm, which correlate with CL-intensity changes. The profiles can be used for diffusion chronometry. The distances obtained from NanoSIMS profiles were used to calculate maximum diffusional relaxation times. Assuming a step function as initial condition and extrusion temperatures from zircon saturation of 850°C, we obtain a maximum residence time for the quartz-phenocrysts of 3.5 years. [1] Pankhurst R.J., Riley T.R., Fanning C.M., Kelley S.P., 2000. J. Pet., 41, 605-625.

  16. Reconstruction of Landscape Evolution Zones (LEZ) from laminated Eifel maar sediments of the last 60 000 years

    NASA Astrophysics Data System (ADS)

    Sirocko, Frank

    2016-04-01

    Tephra, eolian dust, organic carbon, pollen and botanical macroremains from the dry maar lake structures auf Auel and Dehner are used to synthesize and define Landscape Evolution Zones (LEZ) for the Eifel during the last 60 000 years. LEZ 1-3 reiterate the established succession of vegetation during the Holocene and late glacial. The maximum of the last glaciation (LEZ 4: 14 700 - 23 000 b2k) was characterized by extremely sparse vegetation of some moss and characeae, however, characterized by annual activity of eolian dust. These sediments are generally devoid of clay and sand and reveal no indication of snow-meltwater events; accordingly, the Last Glacial Maximum (LGM) must have been extremely arid in central Europe. The sediments of the subsequent LEZ 5 from 23 000 ‒ 28 500 b2k preserve however distinct layers of clay and coarse sand, which indicates running water with clay in suspension and ephemeral coarse grained fluvial sediment discharge; abundant Ranunculaceae macroremains (used for 14C dating), insects, moss and fungi sclerotia reflect a tundra environment during a time of frequent strong snow melt events. Total carbon content and Betula-Pinus pollen reach increased concentrations during all MIS 3 interstadials that occurred between 28 500 - 36 500 b2k (LEZ 6). Grass pollen and heliophytes indicate a steppe environment with scattered/patchy trees during the interstadials. The stadial phases of LEZ 6 reveal first activity of eolian dust deflation. The opening of the early MIS 3 forested landscape to a steppe occurred with the LEZ 7 - LEZ 6 transition at 36 500 b2k. This is the time when modern man arrived in central Europe; possibly because the vegetation change must have favoured the spread of horse, which was the favoured hunting prey of the modern humans. Accordingly, we postulate that the migration of the modern humans into central Europe could have been mainly driven by climate and vegetation change. The LEZ 7 encompassing the time interval from 36

  17. Hydrovolcanic evolution of the Joya Prieta maar, San Luis Potosí, northeast Mexico

    NASA Astrophysics Data System (ADS)

    Davila-Harris, P.; Aranda-Gomez, J. J.; Carrasco, G.

    2013-05-01

    The Joya Prieta is a Quaternary maar volcano emplaced at the western sector of the Sierra Madre Oriental fold and thrust belt. The crater is located at the axis of an open Laramide fold with a N20°W axis trend. It is the most easterly structure of the Santo Domingo Group, a cluster of intraplate maars and tuff-rings northeast of San Luis Potosí. A characteristic feature of these maars is that they are emplaced in close relationship with anticlines, exposing impressive inner crater walls of folded strata. In the Joya Prieta maar, the calcareous basement rocks are clearly exposed and unconformably overlain by the volcanic succession. A generalized stratigraphic sequence registers, from base to top, olivine-bearing basalt lava resting unconformably atop El Abra Formation limestone. The lava is overlain by thick and oxidized scoria and spatter agglomerate that grades into a moderately sorted spatter-fall layer with pervasive palagonite alteration. In direct contact with no evidence of reworking, pedogenesis or remobilization, the maar-forming sequence starts with parallel-stratified fall layers of altered basaltic pumice and scoria, with lava and limestone lithic clasts. This fall deposit marks the influx of xenocrystals and xenoliths, widely documented in previous works; they comprise mainly kaersutite mega crystals and spinel lherzolite respectively. The proximal fall deposit is divided into two thick layers by an indurated ash-tuff bed with pellets and single-rimmed accretionary lapilli. The upper layer of this fall deposit passes gradually onto an alternation of lapilli-sized layers with parallel ash-tuff horizons until it grades into cross-stratified, lithic-rich lapilli-tuff. The heterolithologic lapilli tuff is cemented on a fine ash matrix with palagonized juvenile clasts and abundant lava, shale and limestone lithics exhibiting a plethora of lithofacies in the like of parallel-bedded tuff, low-angle cross-bedded tuff and massive strata. This passes gradually

  18. A new ELSA time series of tephra layers and paleobotanical evidence from laminated Eifel maar sediments covering the entire last 120,000 years

    NASA Astrophysics Data System (ADS)

    Sirocko, Frank; Knapp, Hannes; Klee, Marlies; Rothacker, Leo; Kromer, Bernd

    2014-05-01

    The ELSA Project has drilled a total of 50 sediment cores (2000 m of laminated lake sediment) from Eifel maar lakes and dry maar structures during the last 15 years. These records have been dated using 7 different methods, including 370 14C dates. Ten records reveal the established palynological succession of trees during the Holocene down to the Laacher See Tephra, which is used for synchronization with seven more recently drilled laminated sediment cores, which all are 14C-dated too and analyzed for tephra, pollen and paleobotanical macroremains. The seven newly established records reveal a continuous MIS2 section with mosses, ostracods and characea oogonia. They show that the 28.000 - 40.000 BP has witnessed an open landscape dominated by grass, but with rhythmic spread of conifer trees following the Greenland interstadial/succession. Seeds of Ranunculae provide excellent material for 14C dating. Even deciduous trees are present in small amounts until 28.000 BP. The time from 48.000 to 40.000 BP is characterized by a pronounced transition from the open landscape to an early MIS3 spruce (Picea) dominated forest during Greenland Interstadial GI17-14. Modern man apparently arrived at the end of this principal vegetation change near 40,000 BP. Volcanic activity in the Eifel had a stable and pronounced recurrence from 55,000 - 30,000 BP every 4000 years, but commenced with the beginning of MIS2. This landscape evolution with a forested early MIS3 is quite different to peat and sediment records from Netherlands/ Northern Germany/Scandinavia/ Poland, but is similar to conditions in parts of Switzerland. We address the early MIS3 forest to the nearby continuously moist soils and warm conditions in the nearby Mosel valley, i.e. on those stands where wine is growing today, and which most likely had served as a local refugia even for deciduous trees during MIS4 and MIS3. The MIS5 sections of the presented ELSA records reach down at least to the beginning of MIS5d near 118

  19. Physical experiments of land subsidence within a maar crater: insights for porosity variations and fracture localization

    NASA Astrophysics Data System (ADS)

    Cerca, M.; Rocha, L.; Carreón-Freyre, D.; Aranda, J.

    2015-11-01

    We present the results of a series of physical models aiming to reproduce rapid subsidence (at least 25 m in 30 years) observed in the sediments of a maar crater caused by extraction of groundwater in the interconnected adjacent aquifer. The model considered plausible variations in the geometry of the crater basement and the measured rate of groundwater extraction (1 m per year in the time interval from 2005 to 2011) in 15 wells located around the structure. The experiments were built within a rigid plastic bowl in which the sediments and rocks of the maar sequence were modeled using different materials: (a) plasticine for the rigid country rock, (b) gravel for the fractured country rock forming the diatreme fill and, (c) water saturated hollow glass microbeads for the lacustrine sedimentary fill of the crater. Water table was maintained initially at the surface of the sediments and then was allowed to flow through a hole made at the base of the rigid bowl. Water extraction provoked a sequence of gentle deformation, fracturing, and faulting of the surface in all the experiments. Vertical as well as lateral displacements were observed in the surface of the experiments. We discuss the results of 2 representative models. The model results reproduced the main geometry of the ring faults affecting the crater sediments and helps to explain the diversity of structures observed in relation with the diatreme geometry. The surface of the models was monitored continuously with an optical interferometric technique called structured light projection. Images collected at nearly constant time intervals were analyzed using the ZEBRA software and the obtained interferometric pairs permitted to analyze the full field subsidence in the model (submilimetric vertical displacements). The experiments were conducted at a continuous flow rate extraction and show a also a linear subsidence rate. Comparison among the results of the physical models and the fault system associated to

  20. Shallow plumbing systems for small-volume basaltic volcanoes, 2: Evidence from crustal xenoliths at scoria cones and maars

    NASA Astrophysics Data System (ADS)

    Valentine, Greg A.

    2012-04-01

    Monogenetic basaltic volcanoes record complex eruption processes and the relationships between those processes and shallow plumbing are poorly understood. This paper explores these relationships, building upon earlier studies of exposed shallow plumbing (in the upper hundreds of meters of crust) beneath volcanoes produced by magmatic eruption processes and those produced by phreatomagmatic processes, such as scoria cones and maars, respectively. Eruptive facies and xenolith abundances are described at three scoria cones and at tephra rings around two maars in the San Francisco Volcanic Field (Arizona, USA). Well-constrained subvolcanic sedimentary stratigraphy provides constraints on the depths of origin of xenoliths of different types. Sedimentary xenolith contents at scoria cones are < 10- 3 and commonly < 10- 4 (volume fraction of xenoliths) and are composed almost entirely of fragments from the uppermost sedimentary formation (Kaibab Formation, depth interval ~ 50-200 m). These xenolith contents are consistent with conduits or dikes that widen mainly in the uppermost tens of meters of the crust, as observed at exposed plumbing systems of eroded scoria cones. Sedimentary xenolith contents in tephra ring deposits at one of the studied maar volcanoes also are typically < 10- 3 (volume fraction) and the remaining fraction is dominated by clasts of pre-maar volcanic rocks that formed an ~ 50 thick surface layer over the sedimentary formations; the second studied maar has much higher xenolith contents but this also appears to be dominated by the shallowest unit. The maars' tephra ring deposits contain xenoliths from all of the major sedimentary units beneath the volcanoes (to depths of ~ 1200 m) but the abundances and proportions of xenoliths are not consistent with the volumes of sub-volcanic units that would be disrupted assuming dimensions that are commonly observed in exposed maar plumbing systems (diatremes). These differences illustrate the different mechanisms

  1. Diffuse gas emissions at the Ukinrek Maars, Alaska: Implications for magmatic degassing and volcanic monitoring

    USGS Publications Warehouse

    Evans, William C.; Bergfeld, D.; McGimsey, R.G.; Hunt, A.G.

    2009-01-01

    Diffuse CO2 efflux near the Ukinrek Maars, two small volcanic craters that formed in 1977 in a remote part of the Alaska Peninsula, was investigated using accumulation chamber measurements. High CO2 efflux, in many places exceeding 1000 g m-2 d-1, was found in conspicuous zones of plant damage or kill that cover 30,000-50,000 m2 in area. Total diffuse CO2 emission was estimated at 21-44 t d-1. Gas vents 3-km away at The Gas Rocks produce 0.5 t d-1 of CO2 that probably derives from the Ukinrek Maars basalt based on similar ??13C values (???-6???), 3He/4He ratios (5.9-7.2 RA), and CO2/3He ratios (1-2 ?? 109) in the two areas. A lower 3He/4He ratio (2.7 RA) and much higher CO2/3He ratio (9 ?? 1010) in gas from the nearest arc-front volcanic center (Mount Peulik/Ugashik) provide a useful comparison. The large diffuse CO2 emission at Ukinrek has important implications for magmatic degassing, subsurface gas transport, and local toxicity hazards. Gas-water-rock interactions play a major role in the location, magnitude and chemistry of the emissions.

  2. Temperature variability at Dürres Maar, Germany during the Migration Period and at High Medieval Times, inferred from stable carbon isotopes of Sphagnum cellulose

    NASA Astrophysics Data System (ADS)

    Moschen, R.; Kühl, N.; Peters, S.; Vos, H.; Lücke, A.

    2011-09-01

    This paper presents a high resolution reconstruction of local growing season temperature (GST) anomalies at Dürres Maar, Germany, spanning the last two millennia. The GST anomalies were derived from a stable carbon isotope time series of cellulose chemically extracted from Sphagnum leaves (δ13Ccellulose) separated from a kettle-hole peat deposit of several metres thickness. The temperature reconstruction is based on the Sphagnum δ13Ccellulose/temperature dependency observed in calibration studies. Reconstructed GST anomalies show considerable centennial and decadal scale variability. A cold and presumably wet phase with below-average temperature is reconstructed between the 4th and 7th century AD which is in accordance with the so called European Migration Period, marking the transition from the Late Roman Period to the Early Middle Ages. At High Medieval Times, the amplitude in the reconstructed temperature variability is most likely overestimated; nevertheless, above-average temperatures are obvious during this time span, which are followed by a temperature decrease. On the contrary, a pronounced Late Roman Climate Optimum, often described as similarly warm or even warmer as medieval times, could not be detected. The temperature signal of the Little Ice Age (LIA) is not preserved in Dürres Maar due to considerable peat cutting that takes place in the first half of the 19th century. The local GST anomalies show a remarkable agreement to northern hemispheric temperature reconstructions based on tree-ring datasets and are also in accordance with climate reconstructions on the basis of lake sediments, glacier advances and retreats, and historical datasets. Most notably, e.g., during the Early Middle Ages and at High Medieval Times, temperatures were neither low nor high in general. Rather high frequency temperature variability with multiple narrow intervals of below- and above-average temperatures at maximum lasting a few decades are reconstructed. Especially the

  3. Temperature variability at Dürres Maar, Germany during the migration period and at high medieval times, inferred from stable carbon isotopes of Sphagnum cellulose

    NASA Astrophysics Data System (ADS)

    Moschen, R.; Kühl, N.; Peters, S.; Vos, H.; Lücke, A.

    2011-02-01

    This paper presents a high resolution reconstruction of local growing season temperature (GST) anomalies at Dürres Maar, Germany, spanning the last two millennia. The GST anomalies were derived from a stable carbon isotope time series of cellulose chemically extracted from Sphagnum leaves (δ13Ccellulose) separated from a kettle-hole peat deposit of several metres thickness. The temperature reconstruction is based on the Sphagnum δ13Ccellulose /temperature dependency observed in calibration studies. Reconstructed GST anomalies show considerable centennial and decadal scale variability. A cold and presumably also wet phase with below-average temperature is reconstructed between the 4th and 7th century AD which is in accordance with the so called European Migration Period marking the transition from the Late Roman Period to the Early Middle Ages. At High Medieval Times above-average temperatures are obvious followed by a temperature decrease. On the contrary, a pronounced Late Roman Climate Optimum, often described as similar warm or even warmer as medieval times, could not be detected. The temperature signal of the Little Ice Age (LIA) is not preserved in Dürres Maar due to considerable peat cutting that takes place in the first half of the 19th century. The local GST anomalies show a remarkable agreement to northern hemispheric temperature reconstructions based on tree-ring data sets and are also in accordance with climate reconstructions on the basis of lake sediments, glacier advances and retreats, and historical data sets. Most notably, e.g. during the Early Middle Ages and at High Medieval Times, temperatures were not low or high in general. Rather high frequency temperature variability with multiple narrow intervals of below- and above-average temperatures at maximum lasting a few decades are reconstructed. Especially the agreements between our estimated GST anomalies and the NH temperature reconstructions derived from tree-ring chronologies indicate the

  4. High-resolution past environmental reconstruction in East Asia using annually laminated lake sediments of Lake Megata in northeastern Japan

    NASA Astrophysics Data System (ADS)

    Yamada, K.; Gotanda, K.; Yonenobu, H.; Shinozuka, Y.; Kitagawa, J.; Makohonienko, M.; Schwab, M.; Haraguchi, T.; Yasuda, Y.

    2007-12-01

    37 m-long non-glacial varved sequences were taken from Ichi-no-Megata maar in Oga Peninsula, Akita, northern part of Japan. Ichi-no-Megata maar occupies 0.25 km2 with a maximum water depth of ca. 45.1 m. The shape of lake is a kettle-type basin and the deepest bottom basin is very flat. We took core samples (named IMG06 core) at the center of the lake in November to December in 2006. In order to take completely continuous maar sediment, we drilled three holes and take every sample from each hole which apart only few meters. In this drilling campaign, we can 37 m-long continuous maar sediment except thick volcanic deposits from 26.5 to 31.7m in core. The sedimentological feature of IMG06 core is dominated by thin lamination clay/silt from most top part up to 37 m with turbidites characterized upward fining structure. The SEM image observation of lamination reveals that sponge-like lamina consists of diatom assemblage against dark colored lamina consists of mixture of detritus minerals, clay minerals, and diatom. It means sponge-like lamina deposits during spring season, and later one deposits during another three seasons, and then these thin lamination of IMG06 core could be identified as annual lamination (varves). This interpretation is supported by the correlation of historic event as earthquake and tunnel construction. In this IMG06 core, six volcanic ashes are found and we have also analyzed radiocarbon dating from 38 horizons of the core to use leaf and seeds inter-bedded varves. As the results, the IMG06 core covers from 25,000 to 4,000 14C yr BP with stable sedimentation rates (0.71mm/year).

  5. Unconventional maar diatreme and associated intrusions in the soft sediment-hosted Mardoux structure (Gergovie, France)

    NASA Astrophysics Data System (ADS)

    Valentine, Greg A.; van Wyk de Vries, Benjamin

    2014-03-01

    A Miocene age volcanic-hypabyssal structure comprising volcaniclastic deposits and mafic intrusions is exposed with vertical relief of ˜110 m on the side of Gergovie Plateau (Auvergne, France). Three main volcaniclastic facies are: (1) Fluidal tuff breccia composed of juvenile basalt and sediment clasts with dominantly fluidal shapes, with several combinations of basalt and sediment within individual clasts. (2) Thickly bedded lapilli tuff composed of varying proportions of fine-grained sediment derived from Oligocene-Miocene lacustrine marls and mudstones and basaltic lapilli, blocks, and bombs. (3) Planar-bedded tuff forming thin beds of fine to coarse ash-size sedimentary material and basalt clasts. Intrusive bodies in the thickly bedded lapilli tuff range from irregularly shaped and anastomosing dikes and sills of meters to tens of meters in length, to a main feeder dike that is up to ˜20 m wide, and that flares into a spoon-shaped sill at ˜100 m in diameter and 10-20 m thick in the eastern part of the structure. Volcaniclastic deposits and structural features suggest that ascending magma entrained soft, saturated sediment host material into the feeder dike and erupted fluidal magma and wet sediment via weak, Strombolian-like explosions. Host sediment and erupted material subsided to replace the extracted sediments, producing the growth subsidence structure that is similar to upper diatreme facies in typical maar diatremes but lacks evidence for explosive disruption of diatreme fill. Irregularly shaped small intrusions extended from the main feeder dike into the diatreme, and many were disaggregated due to shifting and subsidence of diatreme fill and recycled via eruption. The Mardoux structure is an "unconventional" maar diatreme in that it was produced mainly by weak explosive activity rather than by violent phreatomagmatic explosions and is an example of complex coupling between soft sediment and ascending magma.

  6. Microbial abundance in lacustrine sediments: a case study from Lake Van, Turkey

    NASA Astrophysics Data System (ADS)

    Kallmeyer, Jens; Grewe, Sina; Glombitza, Clemens; Kitte, J. Axel

    2015-09-01

    The ICDP "PaleoVan" drilling campaign at Lake Van, Turkey, provided a long (>100 m) record of lacustrine subsurface sedimentary microbial cell abundance. After the ICDP campaign at Potrok Aike, Argentina, this is only the second time deep lacustrine cell counts have been documented. Two sites were cored and revealed a strikingly similar cell distribution despite differences in organic matter content and microbial activity. Although shifted towards higher values, cell counts from Lake Potrok Aike, Argentina, reveal very similar distribution patterns with depth. The lacustrine cell count data are significantly different from published marine records; the most probable cause is differences in sedimentary organic matter composition with marine sediments containing a higher fraction of labile organic matter. Previous studies showed that microbial activity and abundance increase centimetres to metres around geologic interfaces. The finely laminated Lake Van sediment allowed studying this phenomenon on the microscale. We sampled at the scale of individual laminae, and in some depth intervals, we found large differences in microbial abundance between the different laminae. This small-scale heterogeneity is normally overlooked due to much larger sampling intervals that integrate over several centimetres. However, not all laminated intervals exhibit such large differences in microbial abundance, and some non-laminated horizons show large variability on the millimetre scale as well. The reasons for such contrasting observations remain elusive, but indicate that heterogeneity of microbial abundance in subsurface sediments has not been taken into account sufficiently. These findings have implications not just for microbiological studies but for geochemistry as well, as the large differences in microbial abundance clearly show that there are distinct microhabitats that deviate considerably from the surrounding layers.

  7. The potential of Pleistocene volcanism for constraining the palaeo-environmental history of the Arabian peninsula: 40Ar/39Ar dating of Al Wahbah maar crater, Harrat Kishb, Saudi Arabia.

    NASA Astrophysics Data System (ADS)

    Abdel Wahab, Antar; Stuart, Finlay M.; Abul Maaty, Mostafa; Awad, Hesham; Kafafy, Aziz

    2013-04-01

    The Arabian peninsula is a critical region for early human migration out of Africa. Pleistocene climatic conditions have fluctuated between wet and dry extremes several times and have had a profound effect on environment and, likely, the development of human populations in the region. However, absolute chronological constraints on regional environmental and climatic changes are poor. The western margin of the Arabian peninsula is covered by 180,000 km2 of Cenozoic to Recent lava flows and related volcanic rocks that record palaeo-climatic conditions. Precise dating of these volcanic rocks has the potential to refine the climatic- environmental evolution of the region. We report a detailed geological and geochronological study of Al Wahbah maar crater (~2.2 km diameter, ~250 m deep) in Harrat Kishb, Saudi Arabia. It formed during a phreatomagmatic explosion that dissected a scoria cone on the northern wall of the crater that exposes a dolerite plug that was intruded immediately prior to crater formation. Pillow lavas at the base of the cone demonstrate that the phreatomagmatic eruption occurred during interaction between magma and a shallow lake or river, rather than groundwater. The 40Ar/39Ar age of dolerite plug (1.147 ± 0.004 Ma) reflects the time that Al Wahbah maar crater formed. More importantly it puts a firm date on the presence of abundant surface water. This study provides constraints on the timing of humid climatic conditions in the region and suggests that the Quaternary basaltic volcanism that stretches the length of the western side of the Arabian peninsula may prove to be useful for establishing the timing of palaeoclimatic changes.

  8. 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)…

  9. Preliminary results on the oxygen isotopic composition of the lower crust, Kilbourne Hole Maar, New Mexico

    NASA Astrophysics Data System (ADS)

    James, David E.; Padovani, Elaine R.; Hart, Stanley R.

    1980-05-01

    18O/16O ratios measured in deep crustal xenoliths from Kilbourne Hole maar, New Mexico show that the oxygen isotopic composition of the lower crust of that region is grossly heterogeneous. Xenoliths derived from similar crustal depths vary in δ18O by nearly 6‰, although the xenoliths are individually in internal oxygen isotopic equilibrium. Mafic granulites (including charnockite), probably of mantle origin, have δ18O of about 6.2 to 6.3‰ and correspondingly low 87Sr/86Sr ratios (0.703 to 0.707). Garnet granulites, apparently the residue of partial fusion of pelitic sedimentary rock, have δ18O ranging from about 9‰ to 12‰ and correspondingly high 87Sr/86Sr ratios (0.71 to 0.78). No evidence is found for extensive oxygen exchange over large distances in the anhydrous lower crust beneath Kilbourne Hole. Absence of regional isotopic equilibrium indicates that even at melting or near melting temperatures the oxygen isotopic identity of the protolith can be preserved over long periods of time. We conclude that there is little reason to postulate that massive oxygen exchange with a mantle-like reservoir is a general phenomenon of the lower crust.

  10. Identification of maars and similar volcanic landforms in the West Eifel Volcanic Field through image processing of DTM data: efficiency of different methods depending on preservation state

    NASA Astrophysics Data System (ADS)

    Seib, Nadine; Kley, Jonas; Büchel, Georg

    2013-04-01

    The West Eifel Volcanic Field comprises 98 maars, tuff rings, and scoria rings of volcanoes younger than 700 ka. Digital Terrain Models (DTMs) allow to automatically measure morphologic parameters of volcanic edifices such as slope angles, diameters, elevations, floor, and slope surface areas. Based on their morphological characteristics, we subdivided the West Eifel volcanoes into five morphometric groups which reflect different stages of erosion. Group I, II, and IV comprise clear ring-shaped structures. The difference between these groups is that a tephra ring is well preserved in Group I, partially preserved in Group II and absent in Group IV. The original shapes of Group III maars have been lost more substantially than in Groups I, II, or IV, but they nevertheless retain a negative shape (a depression) and have characteristic channel systems, which can be used as search criteria. Maar-diatremes of Group V are eroded down to their feeder pipes and form hills. In order to locate potential volcanic depressions that are likely to be maar volcanoes, we defined common search criteria such as circular negative landforms or particular drainage system patterns for all groups except the least well-preserved Group V. These criteria were taken as the basis for further processing of the DTM data. The first processing step consisted of constructing a residual relief calculated as the difference between a filtered (smoothed) topographic surface and the original DTM data. This identifies local topographic features. We propose a method for regulating the degree of smoothing which is based on filtering of local maxima according to their distance from a surface constructed from local minima. The previously defined search criteria for Groups I to IV such as specific ranges of curvature, slope, circularity, density of the drainage network were then applied to the residual relief in order to extract maar shapes. Not all criteria work equally well for all morphological groups

  11. Integrated geophysical and geological methods to investigate the inner and outer structures of the Quaternary Mýtina maar (W-Bohemia, Czech Republic)

    NASA Astrophysics Data System (ADS)

    Flechsig, Christina; Heinicke, Jens; Mrlina, Jan; Kämpf, Horst; Nickschick, Tobias; Schmidt, Alina; Bayer, Tomáš; Günther, Thomas; Rücker, Carsten; Seidel, Elisabeth; Seidl, Michal

    2015-11-01

    The Mýtina maar is the first known Quaternary maar in the Bohemian Massif. Based on the results of Mrlina et al. (J Volcanol Geother Res 182:97-112, 2009), a multiparametric geophysical (electrical resistivity tomography, gravimetry, magnetometry, seismics) and geological/petrochemical research study had been carried out. The interpretation of the data has provided new information about the inner structure of the volcanic complex: (1) specification of the depth of post-volcanic sedimentary fill (up to ~100 m) and (2) magnetic and resistivity signs of one (or two) hidden volcanic structures interpreted as intrusions or remains of a scoria cone. The findings at the outer structure of the maar incorporate the (1) evidence of circular fracture zones outside the maar, (2) detection and distribution of volcanic ejecta and tephra-fall deposits at the surface, and (3) indications from electrical resistivity tomography and gravity data in the area between the Mýtina maar and Železná hůrka scoria cone, interpreted as a palaeovalley, filled by volcaniclastic rocks, and aligned along the strike line (NW-SE) of the Tachov fault zone. These findings are valuable contributions to extend the knowledge about structure of maar volcanoes in general. Because of ongoing active magmatic processes in the north-east part of the Cheb Basin (ca. 15-30 km north of the investigation area), the Mýtina maar-diatreme volcano and surroundings is a suitable key area for research directed to reconstruction of the palaeovolcanic evolution and assessment of possible future hazard potential in the Bohemian Massif.

  12. Basaltic maar-diatreme volcanism in the Lower Carboniferous of the Limerick Basin (SW Ireland)

    NASA Astrophysics Data System (ADS)

    Elliott, H. A. L.; Gernon, T. M.; Roberts, S.; Hewson, C.

    2015-05-01

    Lead-zinc exploration drilling within the Limerick Basin (SW Ireland) has revealed the deep internal architecture and extra-crater deposits of five alkali-basaltic maar-diatremes. These were emplaced as part of a regional north-east south-west tectonomagmatic trend during the Lower Carboniferous Period. Field relationships and textural observations suggest that the diatremes erupted into a shallow submarine environment. Limerick trace element data indicates a genetic relationship between the diatremes and extra-crater successions of the Knockroe Formation, which records multiple diatreme filling and emptying cycles. Deposition was controlled largely by bathymetry defined by the surrounding Waulsortian carbonate mounds. An initial non-diatreme forming eruption stage occurred at the water-sediment interface, with magma-water interaction prevented by high magma ascent rates. This was followed by seawater incursion and the onset of phreatomagmatic activity. Magma-water interaction generated poorly vesicular blocky clasts, although the co-occurrence of plastically deformed and highly vesicular clasts indicate that phreatomagmatic and magmatic processes were not mutually exclusive. At a later stage, the diatreme filled with a slurry of juvenile lapilli and country rock lithic clasts, homogenised by the action of debris jets. The resulting extra-crater deposits eventually emerged above sea level, so that water ingress significantly declined, and late-stage magmatic processes became dominant. These deposits, largely confined to the deep vents, incorporate high concentrations of partially sintered globular and large `raggy' lapilli showing evidence for heat retention. Our study provides new insights into the dynamics and evolution of basaltic diatremes erupting into a shallow water (20-120 m) submarine environment.

  13. Late-stage magmatic processes at Albano Maar, Colli Albani, Italy: insights from FTIR analysis of leucites

    NASA Astrophysics Data System (ADS)

    Cross, J. K.; Roberge, J.; Smith, V.; Giordano, G.; Tomlinson, E.; Menzies, M. A.

    2011-12-01

    The recently erupted Albano Maar, one of the Via dei Laghi phreatomagmatic eruptions of Colli Albani, Italy have eruptive deposits that are K-foiditic (9wt% K2O) and silica under-saturated (48-52wt% SiO2). These compositions suggest the melts are low viscosity [1, 2], but they fuelled very explosive eruptions, namely the widespread large Peperino ignimbrite (phreato-Plinian) deposits. Therefore a question asked by researchers is how could these melts explode and would they, if they had not interacted with groundwater? Experimental work has shown that the melt chemistries at Colli Albani require a volatile saturated system [3]. Consequently the CO2 and H2O content of the melts are critical to understanding the petrogenetic processes at Albano Maar. Since the juvenile tephra clasts exhibit extensive late stage micro-crystallization (mainly leucite), analysis of glass is difficult and not representative as the majority of the volatile components may have exsolved from the melt. Melt inclusions are also commonly recrystallized and often leaky so here we unravel the complex volatile histories of the melts using the abundant leucite crystals, which have been shown to contain magmatic water in recent studies [4]. FTIR analysis of leucite phenocrysts and microcrysts within juvenile tephra clasts (syn-eruptive) of all the erupted units at Albano Maar provide an interesting insight into volatile variations and record a late stage CO2 fluxing event, which would have contributed to the explosive nature of the eruptions. This study has also allowed for an increased understanding of the nominally anhydrous minerals (NAMs) that crucially record volatile speciation and fluxing in high level magmatic systems. [1] Freda et al., 2006, Bul Vol, 68, pp567-591 [2] Cross et al., 2011 IUGG abs [3] Freda et al., 2008, Lithos, pp397-415 [4] Ventura et al., 2008, Am Min, 93, pp1538-1544

  14. Characterization of potential sources of magnetic anomalies within the crust in a tectonically active region: Amphibolites and migmatites from Potrillo Maar, New Mexico

    NASA Technical Reports Server (NTRS)

    Spear, F. S.; Padovanni, E.

    1985-01-01

    The purpose was to characterize the oxide mineralogy and petrology of samples collected from Potrillo Maar, New Mexico with the goal of explaining the magnetic anamoly that is observed over this region from remote sensing. Potrillo Maar is a diatreme that has brought rocks from all depths in the crust to the surface almost instantaneously. The samples are therefore thought to be representative of the crust as it exists today below this portion of the Rio Grande Rift. It is generally believed that oxide minerals (magnetite, hematite, etc.) are responsible for the magnetic signature of the crust. The samples from Portillo Maar therefore offer a unique opportunity to examine the magnetic mineralogy of the entire crust. The results indicate that the magnetic anamoly observed over Rio Grande Rift may be consequence of the tectonic activity that caused mylonitization of the rocks and allowed the infiltration of oxidizing fluids.

  15. Early volcanological research in the Vulkaneifel, Germany, the classic region of maar-diatreme volcanoes: the years 1774-1865

    NASA Astrophysics Data System (ADS)

    Lutz, Herbert; Lorenz, Volker

    2013-08-01

    The Vulkaneifel (Volcanic West Eifel) in the western part of the Rhenish Slate Mountains, Germany, played a major role in the early history of volcanology in general and especially so with respect to the recognition and volcanology of maar-diatreme volcanoes. In 1819, the volcano term "maar" was introduced into the scientific literature by Johann Steininger, a teacher from Trier (Treves) who established the Vulkaneifel as the type region for this kind of volcano. At that time, only a few pioneers—in the earliest days practically all of them were amateurs—had visited this part of western Central Europe in the late eighteenth and earliest nineteenth century. Despite many making important contributions to knowledge of volcanoes, not all were appreciated. In consequence, only in the second half of the twentieth century did new ideas and concepts concerning volcanism in general and phreatomagmatic activity in particular arise that were not previously presented by these pioneers. Their pathbreaking ideas have so far been mostly ignored, we feel, because of the old literature's limited availability. This paper tries to shed new light on these trailblazers. A selection of early geological maps of the Vulkaneifel and its neighbouring regions demonstrates the enormous advancements that had been achieved during those early days, to a large extent, in this part of Western Europe.

  16. The Prodigies of The Albano Lake During Roman Age and Natural Hazard Assessment At Roma, Italy.

    NASA Astrophysics Data System (ADS)

    Funiciello, R.; Giordano, G.; de Rita, D.

    Roma is built just 20 km to the northwest of the Pleistocene Colli Albani volcano, but is believed not exposed to relevant natural hazards, except for the Tiber river flood- ings, and local amplification of seismic waves from distal earthquakes. This belief has generally induced modern historians and geologists to discard as SmythologicalT the & cedil;many references to natural prodigies that are reported by many Roman-age historians. Recent studies have demonstrated that the Albano maar, the youngest volcanic cen- tre of the Colli Albani volcano and presently filled by a 175 m deep lake, protracted its activity to the Holocene triggering several catastrophic lahar events, likely related to lake withdrawal, the deposits of which are exposed to the southwest of Roma and reach its periphery. This finding youngs the history of the volcano and makes it rele- vant to pre-historic settlements, which ScarefullyT avoided the Albano maar slopes up & cedil;to the Bronze age. What is still unknown, though, is whether the lake experienced such fluctuations and overspills during historic times. Several Roman authors such as Ti- tus Livius, Dionigi d'Alicarnasso, Plutarco, Germanico, and many others wrote about the then well known 398 BC prodigious event, when, during the war between Roma and the Etruscan city of Veio, the gods anger caused the sudden rise and overspill of the Albano lake, reported as unrelated to climatic events, and the destructive flooding of the countryside. After that event Romans actually built a tunnel-drain which still operates regulating the lake level at 293 m a.s.l., 70 m below the maar rim elevation. Should those chronicles be truthful, we can join the geologic observation of Holocene lahar deposits from lake withdrawal with historical lake withdrawals, reassessing the natural hazard for the city of Roma under a point of view never explored before. This paper carefully explores the historical credibility of the 398 BC lake overspill event and its

  17. A first Late Glacial and Early Holocene coupled 18O and 2H biomarker isotope record from Gemuendener Maar, Germany

    NASA Astrophysics Data System (ADS)

    Zech, Michael; Bromm, Tobias; Hepp, Johannes; Benesch, Marianne; Sirocko, Frank; Glaser, Bruno; Zech, Roland

    2015-04-01

    During the last years, we developed a method for compound-specific d18O analyses of hemicellulose-derived sugars from plants, soils and sediment archives (Zech and Glaser, 2009; Zech et al., 2014). The coupling of respective d18O sugar results with d2H alkane results from paleosol and sediment climate archives proved to be a valuable innovative approach towards quantitative paleoclimate reconstruction (Hepp et al., 2014; Zech et al., 2013). Here we present a first coupled d18O sugar and d2H alkane biomarker record obtained for Late Glacial and Early Holocene sediments from the Gemuendener Maar in the Eifel, Germany. The d18O sugar biomarker record resembles the d18O ice core records of Greenland. The coupling with the d2H alkane biomarker results allows drawing further more quantitative paleocimate information in terms of (i) paleohumidity and (ii) d18O of paleoprecipitation.

  18. Lake Powell

    Atmospheric Science Data Center

    2014-05-15

    article title:  Lake Powell     View Larger Image ... (14.42 mb)   This true-color image over Lake Powell was acquired by Multi-angle Imaging SpectroRadiometer (MISR) in late March 2000. Lake Powell was formed with the construction of the Glen Canyon Dam in 1963, on the ...

  19. CONNECTICUT LAKES

    EPA Science Inventory

    This is a 1:24,000-scale datalayer of named lakes in Connecticut. It is a polygon Shapefile that includes all lakes that are named on the U.S. Geologicial Survey (USGS) 7½ minute topographic quadrangle maps that cover the State of Connecticut, plus other officially named lakes i...

  20. 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. ... the effect of sunglint at the nadir camera view angle. Dry, salt encrusted parts of the lake appear bright white or gray. Purple areas have ...

  1. Geoheritage values of one of the largest maar craters in the Arabian Peninsula: the Al Wahbah Crater and other volcanoes (Harrat Kishb, Saudi Arabia)

    NASA Astrophysics Data System (ADS)

    Moufti, Mohammed; Németh, Károly; El-Masry, Nabil; Qaddah, Atef

    2013-06-01

    Al Wahbah Crater is one of the largest and deepest Quaternary maar craters in the Arabian Peninsula. It is NW-SE-elongated, ˜2.3 km wide, ˜250 m deep and surrounded by an irregular near-perpendicular crater wall cut deeply into the Proterozoic diorite basement. Very few scientific studies have been conducted on this unique site, especially in respect to understanding the associated volcanic eruption processes. Al Wahbah and adjacent large explosion craters are currently a research subject in an international project, Volcanic Risk in Saudi Arabia (VORiSA). The focus of VORiSA is to characterise the volcanic hazards and eruption mechanisms of the vast volcanic fields in Western Saudi Arabia, while also defining the unique volcanic features of this region for use in future geoconservation, geoeducation and geotourism projects. Al Wahbah is inferred to be a maar crater that formed due to an explosive interaction of magma and water. The crater is surrounded by a tephra ring that consists predominantly of base surge deposits accumulated over a pre-maar scoria cone and underlying multiple lava flow units. The tephra ring acted as an obstacle against younger lava flows that were diverted along the margin of the tephra ring creating unique lava flow surface textures that recorded inflation and deflation processes along the margin of the post-maar lava flow. Al Wahbah is a unique geological feature that is not only a dramatic landform but also a site that can promote our understanding of complex phreatomagmatic monogenetic volcanism. The complex geological features perfectly preserved at Al Wahbah makes this site as an excellent geotope and a potential centre of geoeducation programs that could lead to the establishment of a geopark in the broader area at the Kishb Volcanic Field.

  2. The Alleret Maar lacustrine sequence (French Massif Central): a 150 ka long early-middle Pleistocene continental paleoenvironmental record.

    NASA Astrophysics Data System (ADS)

    Nomade, S.; Pastre, J.; Guillou, H.; Gauthier, A.; Scaillet, S.

    2008-12-01

    Lacustrine maar sequences of the French Massif Central are of great interest for paleoclimatic and paleoenvironmental reconstructions of mid-latitudes Quaternary continental environments. In particular, the western Velay region yields exceptional sequences spanning the last 450 ka (Reille et al., J. Quat. Sci. 2000). However, older sequences remain largely unknown despite the presence of interbedded alkaline tephras allowing precise absolute radiochronological control of many lacustrine squences. The Alleret maar is a 1500 m wide phreatomagmatic crater that provides a long lacustrine sequence (41 m). The upper part of this sequence (AL2 core, 14.6 m) was studied between 2005 and 2006 (Pastre et al., C. R. Acad Sci, 2007). A 39Ar/40Ar date (557 ± 5ka) obtained from an interbedded tephra layer located at 7m as well as the associated pollen data attribute the beginning of this sequence to the MIS 15. Thanks to the AL3 core recovered in 2005 (40.6 m, CNRS Meudon) several new tephra layers were discovered in the bottom part of this lacustrine sequence. Three new 39Ar/40Ar ages (single crystal analyses) from trachytic tephra layers were obtained at the LSCE Argon Laboratory (France). These layers are located at -30.2, -36.2 and -39.2m. Ages obtained relative to the ACR-2 flux standard (1,201Ma, Kuiper et al., Science, 2008) range from 692 ± 6 ka (MSWD: 2.3, n=18) for the youngest (-30.2m) to 726 ± 9Ka Ka (MSWD: 2.2, n=12) for the lowest tephra located at -39.2m. These new dates indicate a relatively homogeneous deposition rate of 3.5cm/ka and that the last 10 meters cover the MIS 17-MIS18 period. According to these current radiochronological data the complete lacustrine sequence last more than 150ka. Ongoing sedimentary and pollen studies will allow to extend the paleoenvironmental and paleoclimatic records of the French Massif Central towards the beginning of the early middle Pleistocene.

  3. Lake Constance

    Atmospheric Science Data Center

    2013-04-17

    ... Swiss shores of Lake Constance at the town of Rorschach. Eutrophication, or the process of nutrient enrichment, is rapidly accelerated ... of the value of Lake Constance, efforts to mitigate eutrophication were initiated in the 1970's. MISR was built and is managed ...

  4. 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...

  5. Eruptive conditions and depositional processes of Narbona Pass Maar volcano, Navajo volcanic field, Navajo Nation, New Mexico (USA)

    NASA Astrophysics Data System (ADS)

    Brand, Brittany D.; Clarke, Amanda B.; Semken, Steven

    2009-01-01

    Phreatomagmatic deposits at Narbona Pass, a mid-Tertiary maar in the Navajo volcanic field (NVF), New Mexico (USA), were characterized in order to reconstruct the evolution and dynamic conditions of the eruption. Our findings shed light on the temporal evolution of the eruption, dominant depositional mechanisms, influence of liquid water on deposit characteristics, geometry and evolution of the vent, efficiency of fragmentation, and the relative importance of magmatic and external volatiles. The basal deposits form a thick (5-20 m), massive lapilli tuff to tuff-breccia deposit. This is overlain by alternating bedded sequences of symmetrical to antidune cross-stratified tuff and lapilli tuff; and diffusely-stratified, clast-supported, reversely-graded lapilli tuffs that pinch and swell laterally. This sequence is interpreted to reflect an initial vent-clearing phase that produced concentrated pyroclastic density currents, followed by a pulsating eruption that produced multiple density currents with varying particle concentrations and flow conditions to yield the well-stratified deposits. Only minor localized soft-sediment deformation was observed, no accretionary lapilli were found, and grain accretion occurs on the lee side of dunes. This suggests that little to no liquid water existed in the density currents during deposition. Juvenile material is dominantly present as blocky fine ash and finely vesiculated fine to coarse lapilli pumice. This indicates that phreatomagmatic fragmentation was predominant, but also that the magma was volatile-rich and vesiculating at the time of eruption. This is the first study to document a significant magmatic volatile component in an NVF maar-diatreme eruption. The top of the phreatomagmatic sequence abruptly contacts the overlying minette lava flows, indicating no gradual drying-out period between the explosive and effusive phases. The lithology of the accidental clasts is consistent throughout the vertical pyroclastic

  6. Cretaceous basaltic phreatomagmatic volcanism in West Texas: Maar complex at Peña Mountain, Big Bend National Park

    NASA Astrophysics Data System (ADS)

    Befus, K. S.; Hanson, R. E.; Lehman, T. M.; Griffin, W. R.

    2008-06-01

    A structurally complex succession of basaltic pyroclastic deposits produced from overlapping phreatomagmatic volcanoes occurs within Upper Cretaceous floodplain deposits in the Aguja Formation in Big Bend National Park, West Texas. Together with similar basaltic deposits recently documented elsewhere in the Aguja Formation, these rocks provide evidence for an episode of phreatomagmatic volcanism that predates onset of arc magmatism in the region in the Paleogene. At Peña Mountain, the pyroclastic deposits are ≥ 70 m thick and consist dominantly of tabular beds of lapillistone and lapilli tuff containing angular to fluidal pyroclasts of altered sideromelane intermixed with abundant accidental terrigenous detritus derived from underlying Aguja sediments. Tephra characteristics indicate derivation from phreatomagmatic explosions involving fine-scale interaction between magma and sediment in the shallow subsurface. Deposition occurred by pyroclastic fall and base-surge processes in near-vent settings; most base-surge deposits lack tractional sedimentary structures and are inferred to have formed by suspension sedimentation from rapidly decelerating surges. Complexly deformed pyroclastic strata beneath a distinct truncation surface within the succession record construction and collapse of an initial volcano, followed by a shift in the location of the conduit and excavation of another maar crater into Aguja strata nearby. Preserved portions of the margin of this second crater are defined by a zone of intense soft-sediment disruption of pyroclastic and nonvolcanic strata. U-Pb isotopic analyses of zircon grains from three basaltic bombs in the succession reveal the presence of abundant xenocrysts, in some cases with ages > 1.0 Ga. The youngest concordant analyses for all three samples yield a weighted mean age of 76.9 ± 1.2 Ma, consistent with the presence of Late Campanian vertebrate fossils in the upper Aguja Formation. We infer that the volcanism is related to the

  7. Geochemical characterization of a Quaternary monogenetic volcano in Erciyes Volcanic Complex: Cora Maar (Central Anatolian Volcanic Province, Turkey)

    NASA Astrophysics Data System (ADS)

    Gencalioglu-Kuscu, Gonca

    2011-11-01

    Central Anatolian Volcanic Province (CAVP) is a fine example of Neogene-Quaternary post-collisional volcanism in the Alpine-Mediterranean region. Volcanism in the Alpine-Mediterranean region comprises tholeiitic, transitional, calc-alkaline, and shoshonitic types with an "orogenic" fingerprint. Following the orogenic volcanism, subordinate, within-plate alkali basalts ( sl) showing little or no orogenic signature are generally reported in the region. CAVP is mainly characterized by widespread calc-alkaline andesitic-dacitic volcanism with orogenic trace element signature, reflecting enrichment of their source regions by subduction-related fluids. Cora Maar (CM) located within the Erciyes pull-apart basin, is an example to numerous Quaternary monogenetic volcanoes of the CAVP, generally considered to be alkaline. Major and trace element geochemical and geochronological data for the CM are presented in comparison with other CAVP monogenetic volcanoes. CM scoria is basaltic andesitic, transitional-calc-alkaline in nature, and characterized by negative Nb-Ta, Ba, P and Ti anomalies in mantle-normalized patterns. Unlike the "alkaline" basalts of the Mediterranean region, other late-stage basalts from the CAVP monogenetic volcanoes are classified as tholeiitic, transitional and mildly alkaline. They display the same negative anomalies and incompatible element ratios as CM samples. In this respect, CM is comparable to other CAVP monogenetic basalts ( sl), but different from the Meditterranean intraplate alkali basalts. Several lines of evidence suggest derivation of CM and other CAVP monogenetic basalts from shallow depths within the lithospheric mantle, that is from a garnet-free source. In a wider regional context, CAVP basalts ( sl) are comparable to Apuseni (Romania) and Big Pine (Western Great Basin, USA) volcanics, except the former have depleted Ba contents. This is a common feature for the CAVP volcanics and might be related to crustal contamination or source

  8. Transport and mixing dynamics from explosions in debris-filled volcanic conduits: Numerical results and implications for maar-diatreme volcanoes

    NASA Astrophysics Data System (ADS)

    Sweeney, Matthew R.; Valentine, Greg A.

    2015-09-01

    Most volcanoes experience some degree of phreatomagmatism during their lifetime. However, the current understanding of such processes remains limited relative to their magmatic counterparts. Maar-diatremes are a common volcano type that form primarily from phreatomagmatic explosions and are an ideal candidate to further our knowledge of deposits and processes resulting from explosive magma-water interaction due to their abundance as well as their variable levels of field exposure, which allows for detailed mapping and componentry. Two conceptual models of maar-diatreme volcanoes explain the growth and evolution of the crater (maar) and subsurface vent (diatreme) through repeated explosions caused by the interaction of magma and groundwater. One model predicts progressively deepening explosions as water is used up by phreatomagmatic explosions while the other allows for explosions at any level in the diatreme, provided adequate hydrologic conditions are present. In the former, deep-seated lithics in the diatreme are directly ejected and their presence in tephra rings is often taken as a proxy for the depth at which that particular explosion occurred. In the latter, deep-seated lithics are incrementally transported toward the surface via upward directed debris jets. Here we present a novel application of multiphase numerical modeling to assess the controls on length scales of debris jets and their role in upward transport of intra-diatreme material to determine the validity of the two models. The volume of gas generated during a phreatomagmatic explosion is a first order control on the vertical distance a debris jet travels. Unless extremely large amounts of magma and water are involved, it is unlikely that most explosions deeper than ∼ 250 m breach the surface. Other factors such as pressure and temperature have lesser effects on the length scales assuming they are within realistic ranges. Redistribution of material within a diatreme is primarily driven by

  9. Petrochemistry of ultrapotassic tephrites and associated cognate plutonic xenoliths with carbonatite affinities from the late Quaternary Qa’le Hasan Ali maars, central Iran

    NASA Astrophysics Data System (ADS)

    Saadat, S.; Stern, C. R.; Moradian, A.

    2014-08-01

    The Quaternary Qa’le Hasan Ali (QHA) maars in central Iran occur at the intersection of the north-south Nayband fault, which defines the western boundary of the Lut micro-continental block, and a system of northwest-southeast faults, subparallel to the Zagros suture zone, that formed during the Arabian-Eurasian collision. These post-collisional maars intrude Eocene volcanic rocks of the Urumieh-Dokhtar magmatic belt, which was generated by the subduction of Neotethys oceanic lithosphere below Iran. The highly potassic, Ti-phlogopite + Mg-rich (Fo89-92) olivine + diopside-augite + aegirine-augite basanite tephrites forming the tuff rims of the QHA maars contain tephrite-coated plutonic xenoliths, some of which are interpreted as co-genetic with the tephrites based on their similar mineralogy and Sr isotopic composition (87Sr/86Sr = 0.70590). Cognate plutonic xenoliths have up to ∼20 vol% calcite, considered to be magmatic calcite because of (1) its grain size, which is similar to feldspars and aegirine-augite pyroxenes in these rocks, (2) the occurrence of fine-grained inclusions of pyroxene and apatite within these calcite grains, and (3) the similarity of the Sr-isotopic composition of this calcite with the other minerals in these rocks. The fact that the magmatic calcite has remained intact and did not volatilize during the transport of these xenoliths to the surface in the hot tephrite magma implies a short transit time, indicating that they are samples of a shallow plutonic complex, as does the presence of anorthoclase in these plutonic xenoliths. Their high modal proportion of magmatic calcite suggests that this shallow plutonic complex has affinities with carbonatites. The magmatic calcite-bearing plutonic xenoliths have high LREE/HREE ratios and contain REE-rich allanite (with up to ∼20 wt% LREE) and britholite (∼60 wt% LREE) that make up ∼3 modal percent of the most calcite-rich samples. Similar to many post-collisional highly potassic rocks

  10. Deglacial and postglacial evolution of the Pingualuit Crater Lake basin, northern Québec (Canada)

    NASA Astrophysics Data System (ADS)

    Desiage, Pierre-Arnaud; Lajeunesse, Patrick; St-Onge, Guillaume; Normandeau, Alexandre; Ledoux, Grégoire; Guyard, Hervé; Pienitz, Reinhard

    2015-11-01

    The Pingualuit Crater, located in the Ungava Peninsula (northern Québec, Canada) is a 1.4-Ma-old impact crater hosting a ~ 245-m-deep lake. The lake has a great potential to preserve unique paleoclimatic and paleoecological sedimentary records of the last glacial/interglacial cycles in the terrestrial Canadian Arctic. In order to investigate the stratigraphy in the lake and the late Quaternary glacial history of the Pingualuit Crater, this study compiles data from three expeditions carried out in May 2007 (~ 9-m-long sediment core), in August 2010 (~ 50 km of seismic lines), and in September 2012 (high-resolution terrestrial LiDAR topography of the inner slopes). Despite the weak penetration (~ 10 m) of the 3.5-kHz subbottom profiling caused by the presence of boulders in the sedimentary column, seismic data coupled with the stratigraphy established from the sediment core enabled the identification of two glaciolacustrine units deposited during the final stages of the Laurentide Ice Sheet (LIS) retreat in the crater. Two episodes of postglacial mass wasting events were also identified on the slopes and in the deep basin of the crater. The high-resolution topography of the internal slopes of the crater generated from the LiDAR data permitted the confirmation of a paleolake level at 545 m and determination of the elevation of drainage outlets. Together with the mapping of glacial and deglacial landforms from air photographs, the LiDAR data allowed the development of a new deglaciation and drainage scenario for the Pingualuit Crater Lake and surrounding area. The model proposes three main phases of lake drainage, based on the activation of seven outlets following the retreat of the LIS front toward the southwest. Finally, as opposed to other high-latitude crater lake basins such as Lake El'gygytgyn or Laguna Potrok Aike where high-resolution paleoclimatic records were obtained owing to high sediment accumulation rates, the seismic data from the Pingualuit Crater Lake

  11. Tracking the hydro-climatic signal from lake to sediment: A field study from central Turkey

    NASA Astrophysics Data System (ADS)

    Dean, Jonathan R.; Eastwood, Warren J.; Roberts, Neil; Jones, Matthew D.; Yiğitbaşıoğlu, Hakan; Allcock, Samantha L.; Woodbridge, Jessie; Metcalfe, Sarah E.; Leng, Melanie J.

    2015-10-01

    Palaeo-hydrological interpretations of lake sediment proxies can benefit from a robust understanding of the modern lake environment. In this study, we use Nar Gölü, a non-outlet, monomictic maar lake in central Turkey, as a field site for a natural experiment using observations and measurements over a 17-year monitoring period (1997-2014). We compare lake water and sediment trap data to isotopic, chemical and biotic proxies preserved in its varved sediments. Nar Gölü underwent a 3 m lake-level fall between 2000 and 2010. δ18Olakewater is correlated with this lake-level fall, responding to the change in water balance. Endogenic carbonate is shown to precipitate in isotopic equilibrium with lake water and there is a strong relationship between δ18Olakewater and δ18Ocarbonate, which suggests the water balance signal is accurately recorded in the sediment isotope record. Over the same period, sedimentary diatom assemblages also responded, and conductivity inferred from diatoms showed a rise. Shifts in carbonate mineralogy and elemental chemistry in the sediment record through this decade were also recorded. Intra-annual changes in δ18Olakewater and lake water chemistry are used to demonstrate the seasonal variability of the system and the influence this may have on the interpretation of δ18Ocarbonate. We use these relationships to help interpret the sedimentary record of changing lake hydrology over the last 1725 years. Nar Gölü has provided an opportunity to test critically the chain of connection from present to past, and its sedimentary record offers an archive of decadal- to centennial-scale hydro-climatic change.

  12. 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.

  13. Geosphere-Biosphere Interactions in Bio-Activity Volcanic Lakes: Evidences from Hule and Rìo Cuarto (Costa Rica)

    PubMed Central

    Cabassi, Jacopo; Tassi, Franco; Mapelli, Francesca; Borin, Sara; Calabrese, Sergio; Rouwet, Dmitri; Chiodini, Giovanni; Marasco, Ramona; Chouaia, Bessem; Avino, Rosario; Vaselli, Orlando; Pecoraino, Giovannella; Capecchiacci, Francesco; Bicocchi, Gabriele; Caliro, Stefano; Ramirez, Carlos; Mora-Amador, Raul

    2014-01-01

    Hule and Río Cuarto are maar lakes located 11 and 18 km N of Poás volcano along a 27 km long fracture zone, in the Central Volcanic Range of Costa Rica. Both lakes are characterized by a stable thermic and chemical stratification and recently they were affected by fish killing events likely related to the uprising of deep anoxic waters to the surface caused by rollover phenomena. The vertical profiles of temperature, pH, redox potential, chemical and isotopic compositions of water and dissolved gases, as well as prokaryotic diversity estimated by DNA fingerprinting and massive 16S rRNA pyrosequencing along the water column of the two lakes, have highlighted that different bio-geochemical processes occur in these meromictic lakes. Although the two lakes host different bacterial and archaeal phylogenetic groups, water and gas chemistry in both lakes is controlled by the same prokaryotic functions, especially regarding the CO2-CH4 cycle. Addition of hydrothermal CO2 through the bottom of the lakes plays a fundamental priming role in developing a stable water stratification and fuelling anoxic bacterial and archaeal populations. Methanogens and methane oxidizers as well as autotrophic and heterotrophic aerobic bacteria responsible of organic carbon recycling resulted to be stratified with depth and strictly related to the chemical-physical conditions and availability of free oxygen, affecting both the CO2 and CH4 chemical concentrations and their isotopic compositions along the water column. Hule and Río Cuarto lakes were demonstrated to contain a CO2 (CH4, N2)-rich gas reservoir mainly controlled by the interactions occurring between geosphere and biosphere. Thus, we introduced the term of bio-activity volcanic lakes to distinguish these lakes, which have analogues worldwide (e.g. Kivu: D.R.C.-Rwanda; Albano, Monticchio and Averno: Italy; Pavin: France) from volcanic lakes only characterized by geogenic CO2 reservoir such as Nyos and Monoun (Cameroon). PMID

  14. Geosphere-biosphere interactions in bio-activity volcanic lakes: evidences from Hule and Rìo Cuarto (Costa Rica).

    PubMed

    Cabassi, Jacopo; Tassi, Franco; Mapelli, Francesca; Borin, Sara; Calabrese, Sergio; Rouwet, Dmitri; Chiodini, Giovanni; Marasco, Ramona; Chouaia, Bessem; Avino, Rosario; Vaselli, Orlando; Pecoraino, Giovannella; Capecchiacci, Francesco; Bicocchi, Gabriele; Caliro, Stefano; Ramirez, Carlos; Mora-Amador, Raul

    2014-01-01

    Hule and Río Cuarto are maar lakes located 11 and 18 km N of Poás volcano along a 27 km long fracture zone, in the Central Volcanic Range of Costa Rica. Both lakes are characterized by a stable thermic and chemical stratification and recently they were affected by fish killing events likely related to the uprising of deep anoxic waters to the surface caused by rollover phenomena. The vertical profiles of temperature, pH, redox potential, chemical and isotopic compositions of water and dissolved gases, as well as prokaryotic diversity estimated by DNA fingerprinting and massive 16S rRNA pyrosequencing along the water column of the two lakes, have highlighted that different bio-geochemical processes occur in these meromictic lakes. Although the two lakes host different bacterial and archaeal phylogenetic groups, water and gas chemistry in both lakes is controlled by the same prokaryotic functions, especially regarding the CO2-CH4 cycle. Addition of hydrothermal CO2 through the bottom of the lakes plays a fundamental priming role in developing a stable water stratification and fuelling anoxic bacterial and archaeal populations. Methanogens and methane oxidizers as well as autotrophic and heterotrophic aerobic bacteria responsible of organic carbon recycling resulted to be stratified with depth and strictly related to the chemical-physical conditions and availability of free oxygen, affecting both the CO2 and CH4 chemical concentrations and their isotopic compositions along the water column. Hule and Río Cuarto lakes were demonstrated to contain a CO2 (CH4, N2)-rich gas reservoir mainly controlled by the interactions occurring between geosphere and biosphere. Thus, we introduced the term of bio-activity volcanic lakes to distinguish these lakes, which have analogues worldwide (e.g. Kivu: D.R.C.-Rwanda; Albano, Monticchio and Averno: Italy; Pavin: France) from volcanic lakes only characterized by geogenic CO2 reservoir such as Nyos and Monoun (Cameroon). PMID

  15. Lake ecosystem response to rapid lateglacial climate changes in lake sediments from northern Poland

    NASA Astrophysics Data System (ADS)

    Słowiński, Michał; Zawiska, Izabela; Ott, Florian; Noryśkiewicz, Agnieszka M.; Apolinarska, Karina; Lutyńska, Monika; Michczyńska, Danuta J.; Brauer, Achim; Wulf, Sabine; Skubała, Piotr; Błaszkiewicz, Mirosław

    2013-04-01

    During the Late Glacial Period environment changes were triggered by climatic oscillations which in turn controlled processes like, for example, permafrost thawing, vegetation development and ground water circulation. These environmental changes are ideally recorded in lake sediments and thus can be reconstructed applying a multi-poxy approach. Here, we present the results from the Trzechowskie paleolake, located in the northern Polish lowlands (eastern part of the Pomeranian Lakeland). The site is situated on the outwash plain of the Wda River, which was formed during the Pomeranian phase of the Vistulian glaciation ca 16,000 14C yrs BP. The depression of the Trzechowskie lake basin formed after melting of a buried ice block during the Allerød (13903±170 cal yrs BP). We reconstructed environmental changes in the Trzechowskie paleolake and its catchment using biotic proxies (macrofossils, pollen, cladocera, diatoms, oribatidae mite) and geochemical proxies (δ18O, δ13C, loss-on-ignition (LOI), CaCO3 content). In addition, we carried out µ-XRF element core scanning. The chronology has been established by means of biostratigraphyAMS14C dating on plant macro remains, varve counting in laminated intervals and the late Allerød Laacher See Tephra isochrone. Our results showed that biogenic accumulation in the lake started during the Bølling. Development of coniferous forest during the Allerød with dominance of Pinus sylvestris lead to leaching of carbonates in the catchment due to low pH increasing the flux of Ca ions into the lake. In consequence calcite precipitating in the lake increased as evidences by increasing CaCO3 contents. Both biotic and physical proxies clearly reflect the rapid decrease in productivity at the onset of the Younger Dryas. We compare the data from the Trzechowskie paleolake with the Meerfelder Maar and Rehwiese lake records based on tephrochronological synchronization using the Laacher See Tephra. This study is a contribution to the

  16. Holocene climatic and hydrological changes in Big Soda Lake, Nevada

    NASA Astrophysics Data System (ADS)

    Rosen, M. R.; Reidy, L. M.; Starratt, S.; Byrne, R.

    2014-12-01

    It is important to separate the role of hydrology from climate change when assessing the Holocene history of lake sediments. Big Soda Lake is a Holocene maar lake in the Great Basin of Nevada with a 9 m sediment record that covers the Holocene. The mm-scale laminations, diatoms, and δ18O and δ13C from bulk calcite in the core are consistent with a saline, closed-basin lake down to approximately 4.3 m below the sediment water interface. The top 7 cm of the core show the influence of human hydrologic modifications to the area. Below that, stable isotope data shows variable groundwater input that is mostly consistent with climate variation from other records in the western USA. Below 4.3 m depth, the laminations abruptly end and are replaced by unlaminated massive mud, sand, and gravel to the bottom. The isotopic composition of the calcite abruptly changes from covarying, to inversely varying compositions below this break. This break occurred at about 5,600 cal yr BP. In addition, the diatom assemblage below 4.3 m is similar to that found in modern Walker Lake; whereas the diatom assemblage above 4.3 m is similar to modern Mono Lake. The δ18O isotopic composition of the calcite is on average 6 ‰ more negative below 4.3 m than above the change, indicating that the lake contained fresher water before 5,600 cal yr BP ago. The cause for the abrupt change cannot be explained through climate shifts because climate in the Great Basin has been shown to be more arid between 8,000 and 5,000 cal yr BP. It has been hypothesized that the Walker River flowed to the Carson River Basin between about 14,000 and 5,000 cal yr BP, and this added water may have raised the groundwater table sufficiently in the Carson Basin to freshen Big Soda Lake. Once the Walker River diverted back to the Walker Basin, more saline conditions prevailed reflecting changes in climate and human influence at the top of the core.

  17. Subsurface structure of a maar-diatreme and associated tuff ring from a high-resolution geophysical survey, Rattlesnake Crater, Arizona

    NASA Astrophysics Data System (ADS)

    Marshall, Anita; Connor, Charles; Kruse, Sarah; Malservisi, Rocco; Richardson, Jacob; Courtland, Leah; Connor, Laura; Wilson, James; Karegar, Makan A.

    2015-10-01

    Geophysical survey techniques including gravity, magnetics, and ground penetrating radar were utilized to study the diatreme and tuff ring at Rattlesnake Crater, a maar in the San Francisco Volcanic Field of northern Arizona. Significant magnetic anomalies (+ 1600 nT) and a positive gravity anomaly (+ 1.4 mGal) are associated with the maar. Joint modeling of magnetic and gravity data indicate that the diatreme that underlies Rattlesnake Crater has volume of 0.8-1 km3, and extends to at least 800 m depth. The modeled diatreme comprises at least two zones of variable density and magnetization, including a low density, highly magnetized unit near the center of the diatreme, interpreted to be a pyroclastic unit emplaced at sufficiently high temperature and containing sufficient juvenile fraction to acquire thermal remanent magnetization. Magnetic anomalies and ground penetrating radar (GPR) imaging demonstrate that the bedded pyroclastic deposits of the tuff ring also carry high magnetization, likely produced by energetic emplacement of hot pyroclastic density currents. GPR profiles on the tuff ring reveal long (~ 100 m) wavelength undulations in bedding planes. Elsewhere, comparable bedforms have been interpreted as base surge deposits inflated by air entrainment from eruption column collapse. Interpretation of these geophysical data suggests that Rattlesnake Crater produced highly energetic phreatomagmatic activity that gave way to less explosive activity as the eruption progressed. The positive gravity anomaly associated with the maar crater is interpreted to be caused by coherent bodies within the diatreme and possibly lava ponding on the crater floor. These dense magnetized bodies have excess mass of 2-4 × 1010 kg, and occupy approximately 5% of the diatreme by volume. Magnetic anomalies on the crater floor are elongate NW-SE, suggesting that the eruption may have been triggered by the interaction of ascending magma with water in fractures of this orientation

  18. Drill Core Mineral Analysis by Means of the Hyperspectral Imaging Spectrometer HySpex, XRD and Asd in Proximity of the MÝTINA Maar, Czech Republic

    NASA Astrophysics Data System (ADS)

    Koerting, F.; Rogass, C.; Kaempf, H.; Lubitz, C.; Harms, U.; Schudack, M.; Kokaly, R.; Mielke, C.; Boesche, N.; Altenberger, U.

    2015-12-01

    Imaging spectroscopy is increasingly used for surface mapping. Therefore different expert systems are being utilized to identify surface cover materials. Those expert systems mainly rely on the spectral comparison between unknown and library spectra, but their performances were only limited qualified. This study aims on the comparative analysis of drill core samples from the recently discovered maar system in the Czech Republic. Drill core samples from the surrounding area of the Mýtina maar were analyzed by X-Ray diffraction (XRD) and the hyperspectral spectrometer HySpex. Additionally, soil samples were measured in-situ by the ASD FieldSpec4 and in the laboratory by the HySpex VNIR/SWIR spectrometer system. The data was then analyzed by the MICA-algorithm and the results were compared to the results of the XRD -analysis. The XRD-analysis served here as validation basis. The results of the hyperspectral and the XRD analyses were used to densify a volcanic map that also integrates in-situ soil measurements in the surrounding area of Mýtina. The comparison of the XRD- and solaroptical remote sensing results showed a good correlation of qualified minerals if the soil organic carbon content was significantly low. Contrary to XRD, smectites and muscovites were also straightforward identified that underlines the overall performance of the approach to identify minerals. Basically, in this work an operable approach is proposed that enables the fast, repeatable and detailed analysis of drill cores, drill core samples and soil samples and, hence, provides a higher performance than state-of-the-art XRD-analyses.

  19. Trace Element Geochemistry of Basaltic Tephra in Maar Cores; Implications for Centre Correlation, Field Evolution, and Mantle Source Characteristics of the Auckland Volcanic Field, New Zealand

    NASA Astrophysics Data System (ADS)

    Hopkins, J. L.; Leonard, G.; Timm, C.; Wilson, C. J. N.; Neil, H.; Millet, M. A.

    2014-12-01

    Establishing volcanic hazard and risk management strategies hinges on a detailed understanding of the type, timing and tephra dispersal of past eruptions. In order to unravel the pyroclastic eruption history of a volcanic field, genetic links between the deposits and eruption source centre need to be established. The Auckland Volcanic Field (AVF; New Zealand) has been active for ca. 200 kyr and comprises ca. 53 individual centres covering an area of ca. 360km2. These centres show a range of sizes and eruptive styles from maar craters and tuff rings, to scoria cones and lava flows consistent with both phreatomagmatic and magmatic eruptions. Superimposition of the metropolitan area of Auckland (ca. 1.4 million inhabitants) on the volcanic field makes it critically important to assess the characteristics of the volcanic activity, on which to base assessment and management of the consequent hazards. Here we present a geochemical approach for correlating tephra deposits to their source centres. To acquire the most complete stratigraphic record of pyroclastic events, maar crater cores from different locations, covering various depths and thus ages across the field were selected. Magnetic susceptibility and x-ray density scanning of the cores was used to identify the basaltic tephra horizons, which were sampled and in-situ analysis of individual shards undertaken for major and trace elements using EPMA and LA-ICP-MS techniques, respectively. Our results show that tephra shard trace element ratios are comparable and complementary to the AVF whole rock database. The use of specific trace element ratios (e.g. Gd/Yb vs. Zr/Yb) allows us to fingerprint and cross correlate tephra horizons between cores and, when coupled with newly acquired 40Ar-39Ar age dating and eruption size estimates, correlate horizons to their source centres. This integrated style of study can provide valuable information to help volcanic hazard management and forecasting, and mitigation of related risks.

  20. High-resolution paleomagnetic secular variations and relative paleointensity since the Late Pleistocene in southern South America

    NASA Astrophysics Data System (ADS)

    Lisé-Pronovost, Agathe; St-Onge, Guillaume; Gogorza, Claudia; Haberzettl, Torsten; Preda, Michel; Kliem, Pierre; Francus, Pierre; Zolitschka, Bernd; Pasado Science Team

    2013-07-01

    Paleomagnetic inclination, declination and relative paleointensity were reconstructed from the sediments of Laguna Potrok Aike in the framework of the International Continental scientific Drilling Program (ICDP) Potrok Aike maar lake Sediment Archive Drilling prOject (PASADO). Here we present the u-channel-based full vector paleomagnetic field reconstruction since 51.2 ka cal BP. The relative paleointensity proxy (RPI) was built by normalising the natural remanent magnetisation with the anhysteretic remanent magnetisation using the average ratio at 4 demagnetisation steps part of the ChRM interval (NRM/ARM10-40 mT). A grain size influence on the RPI was removed using a correction based on the linear relationship between the RPI and the median destructive field of the natural remanent magnetisation (MDFNRM). The new record is compared with other lacustrine and marine records and stacks from the mid- to high-latitudes of the Southern Hemisphere, revealing consistent millennial-scale variability, the identification of the Laschamp and possibly the Mono Lake geomagnetic excursions, and a direction swing possibly associated to the Hilina Pali excursion at 20 ka cal BP. Nonetheless, a global-scale comparison with other high-resolution records located on the opposite side of the Earth and with various dipole field references hint at a different behaviour of the geomagnetic field around southern South America at 46 ka cal BP.

  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. 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

  3. The Last Glacial Maximum in the Northern European loess belt: Correlations between loess-paleosol sequences and the Dehner Maar core (Eifel Mountains)

    NASA Astrophysics Data System (ADS)

    Zens, Joerg; Krauß, Lydia; Römer, Wolfgang; Klasen, Nicole; Pirson, Stéphane; Schulte, Philipp; Zeeden, Christian; Sirocko, Frank; Lehmkuhl, Frank

    2016-04-01

    The D1 project of the CRC 806 "Our way to Europe" focusses on Central Europe as a destination of modern human dispersal out of Africa. The paleo-environmental conditions along the migration areas are reconstructed by loess-paleosol sequences and lacustrine sediments. Stratigraphy and luminescence dating provide the chronological framework for the correlation of grain size and geochemical data to large-scale climate proxies like isotope ratios and dust content of Greenland ice cores. The reliability of correlations is improved by the development of precise age models of specific marker beds. In this study, we focus on the (terrestrial) Last Glacial Maximum of the Weichselian Upper Pleniglacial which is supposed to be dominated by high wind speeds and an increasing aridity. Especially in the Lower Rhine Embayment (LRE), this period is linked to an extensive erosion event. The disconformity is followed by an intensive cryosol formation. In order to support the stratigraphical observations from the field, luminescence dating and grain size analysis were applied on three loess-paleosol sequences along the northern European loess belt to develop a more reliable chronology and to reconstruct paleo-environmental dynamics. The loess sections were compared to newest results from heavy mineral and grain size analysis from the Dehner Maar core (Eifel Mountains) and correlated to NGRIP records. Volcanic minerals can be found in the Dehner Maar core from a visible tephra layer at 27.8 ka up to ~25 ka. They can be correlated to the Eltville Tephra found in loess section. New quartz luminescence ages from Romont (Belgium) surrounding the tephra dated the deposition between 25.0 + 2.3 ka and 25.8 + 2.4 ka. In the following, heavy minerals show an increasing importance of strong easterly winds during the second Greenland dust peak (~24 ka b2k) correlating with an extensive erosion event in the LRE. Luminescence dating on quartz bracketing the following soil formation yielded ages of

  4. The Middle-Pleistocene (~300 ka) Rodderberg maar-scoria cone volcanic complex (Bonn, Germany): eruptive history, geochemistry, and thermoluminescence dating

    NASA Astrophysics Data System (ADS)

    Paulick, H.; Ewen, C.; Blanchard, H.; Zöller, L.

    2009-12-01

    The Rodderberg volcanic complex (RVC) is located within the city limits of Bonn (Germany) approximately 20 km to the north of the Quaternary East Eifel Volcanic Field (EEVF). It is the product of intense phreatomagmatic volcanism forming a 90 m deep maar crater and strombolian eruptions. Deposit features indicate that the location of the vent(s) shifted from N to S during the strombolian phase. The erupted leucite-nephelinite magma (on the order of ca. 1 × 10-2 km3) was largely homogenous with minor, stratigraphically controlled, variation in olivine and clinopyroxene microphenocryst content. Stratigraphic evidence and thermoluminescence dating indicate that the RVC erupted during the glacial MIS 8 at around 300 ka. During this time, the EEVF experienced a transitional stage between two major phases of volcanic activity involving a change in magma sources. This is consistent with the RVC geochemical data which show affinities to both the older EEVF leucite-nephelinite association (430-380 ka) and the younger basanite association (<215 ka). In the Eifel, magma ascent through the upper crust is apparently linked to tectonic fractures. It may be speculated that a tectonically controlled diking event channeled magma to the north of the main EEVF and that the RVC represents an exceptional surficial expression of a significantly larger subsurface intrusion. This scenario would be consistent with recent observations of diking-related volcanism in the East African Rift zone and previously inferred models for magma ascent in similar intraplate volcanic fields.

  5. 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

  6. 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 ...

  7. 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 ...

  8. Lake trout rehabilitation in Lake Ontario

    USGS Publications Warehouse

    Elrod, Joseph H.; O'Gorman, Robert; Schneider, Clifford P.; Eckert, Thomas H.; Schaner, Ted; Bowlby, James N.; Schleen, Larry P.

    1995-01-01

    Attempts to maintain the native lake trout (Salvelinus namaycush) population in Lake Ontario by stocking fry failed and the species was extirpated by the 1950s. Hatchery fish stocked in the 1960s did not live to maturity because of sea lamprey (Petromyzon marinus) predation and incidental commercial harvest. Suppression of sea lampreys began with larvicide treatments of Lake Ontario tributaries in 1971 and was enhanced when the tributaries of Oneida Lake and Lake Erie were treated in the 1980s. Annual stocking of hatchery fish was resumed with the 1972 year class and peaked at about 1.8 million yearlings and 0.3 million fingerlings from the 1985–1990 year classes. Survival of stocked yearlings declined over 50% in the 1980 s and was negatively correlated with the abundance of lake trout > 550 mm long (r = −0.91, P < 0.01, n = 12). A slot length limit imposed by the State of New York for the 1988 fishing season reduced angler harvest. Angler harvest in Canadian waters was 3 times higher in eastern Lake Ontario than in western Lake Ontario. For the 1977–1984 year classes, mean annual survival rate of lake trout age 6 and older was 0.45 (range: 0.35–0.56). In U.S. waters during 1985–1992, the total number of lake trout harvested by anglers was about 2.4 times greater than that killed by sea lampreys. The number of unmarked lake trout < 250 mm long in trawl catches in 1978–1992 was not different from that expected due to loss of marks and failure to apply marks at the hatchery, and suggested that recruitment of naturally-produced fish was nil. However, many of the obstacles which may have impeded lake trout rehabilitation in Lake Ontario during the 1980s are slowly being removed, and there are signs of a general ecosystem recovery. Significant recruitment of naturally produced lake trout by the year 2000, one interim objective of the rehabilitation plan for the Lake, may be achieved.

  9. 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…

  10. 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)

  11. 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…

  12. 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.…

  13. Lake Effects: The Lake Superior Curriculum Guide.

    ERIC Educational Resources Information Center

    Beery, Tom; And Others

    This curriculum guide was launched in response to a need for Lake Superior-specific educational materials and contains lessons and activities that can be used to teach about Lake Superior. The lessons in this book are divided into four sections. Each of the first three sections has a background section that provides basic information about Lake…

  14. 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

  15. Late Pleistocene aeolian dust provenances and wind direction changes reconstructed by heavy mineral analysis of the sediments of the Dehner dry maar (Eifel Mountains, Germany)

    NASA Astrophysics Data System (ADS)

    Lehmkuhl, Frank; Römer, Wolfgang; Sirocko, Frank

    2016-04-01

    The study presents the results of a heavy mineral analysis from a 38 m long record of aeolian sediments from a core section of the Dehner dry maar (Eifel Mountains, Germany). The record encompasses the period from 30 to about 12.5 ka. Heavy-mineral analysis of the silt fraction has been performed at a sampling interval of 1 m. Statistical analyses enabled the distinction of local and regional source areas of aeolian material and revealed pronounced changes in the amounts of different heavy mineral species and corresponding changes in the grain size index (GSI). The results indicate that during the early stages of MIS 2 (40 to 30m depth) aeolian sediments were supplied mostly from local sources. This period is characterized by a low GSI ratio resulting from a reduced mobility of material due to a vegetation cover. The climax of the LGM is characterized by a higher supply of heavy minerals from regional and more distant sources. Changes in the provenance areas are indicated in inverse relationships between zircon, rutile, tourmaline (ZRT) and carbonate particles. Shifts in the wind direction are documented in pronounced peaks of carbonate particles indicating easterly winds that have crossed the limestone basins in the Eifeler North South Zone. ZRT-group minerals on the other hand suggest a westerly source area and a supply from areas consisting of Paleozoic clastic sedimentary rocks. In the periods following the LGM the analyses indicate an increasing degree of mixing of heavy minerals from various provinces. This suggests the existence of a presumably incomplete, thin cover of deflatable loessic sediments that has been repeatedly reworked on the elevated surfaces of the Eifel.

  16. Water quality of Lake Austin and Town Lake, Austin, Texas

    SciTech Connect

    Andrews, F.L.; Wells, F.C.; Shelby, W.J.; McPherson, E.M.

    1988-01-01

    Lake Austin and Town Lake are impoundments on the Colorado River in Travis County, central Texas, and are a source of water for municipal industrial water supplies, electrical-power generation, and recreation for more than 500,000 people in the Austin metropolitan area. Small vertical temperature variations in both lakes were attributed to shallow depths in the lakes and short retention times of water in the lakes during the summer months. The largest areal variations in dissolved oxygen generally occur in Lake Austin during the summer as a result of releases of water from below the thermocline in Lake Travis. Except for iron, manganese, and mercury, dissolved concentrations of trace elements in water collected from Lake Austin and Town Lake did not exceed the primary or secondary drinking water standards set by the US Environmental Protection Agency. Little or no effect of stormwater runoff on temperature, dissolved oxygen, or minor elements could be detected in either Lake Austin or Town Lake. Little seasonal or areal variation was noted in nitrogen concentrations in Lake Austin or Town lake. Total phosphorus concentrations generally were small in both lakes. Increased concentrations of nitrogen and phosphorus were detected after storm runoff inflow in Town Lake, but not in Lake Austin; densities of fecal-coliform bacteria increased in Lake Austin and Town Lake, but were substantially greater in Town Lake than in Lake Austin. 18 refs., 38 figs., 59 tabs.

  17. Lake trout rehabilitation in Lake Huron

    USGS Publications Warehouse

    Eshenroder, Randy L.; Payne, N. Robert; Johnson, James E.; Bowen, Charles, II; Ebener, Mark P.

    1995-01-01

    Efforts to restore lake trout (Salvelinus namaycush) in Lake Huron after their collapse in the 1940s were underway in the early 1970s with completion of the first round of lampricide applications in tributary streams and the stocking of several genotypes. We assess results of rehabilitation and establish a historical basis for comparison by quantifying the catch of spawning lake trout from Michigan waters in 1929-1932. Sixty-eight percent of this catch occurred in northern waters (MH-1) and most of the rest (15%) was from remote reefs in the middle of the main basin. Sea lampreys (Petromyzon marinus) increased in the early 1980s in the main basin and depressed spawning populations of lake trout. This increase was especially severe in northern waters and appeared to be associated with untreated populations in the St. Marys River. Excessive commercial fishing stemming from unresolved treaty rights also contributed to loss of spawning fish in northern Michigan waters. Seneca-strain lake trout did not appear to be attacked by sea lampreys until they reached a size > 532 mm. At sizes > 632 mm, Seneca trout were 40-fold more abundant than the Marquette strain in matched-planting experiments. Natural reproduction past the fry stage has occurred in Thunder Bay and South Bay, but prospects for self-sustaining populations of lake trout in the main basin are poor because sea lampreys are too abundant, only one side of the basin is stocked, and stocking is deferred to allow commercial gillnetting in areas where most of the spawning occurred historically. Backcross lake trout, a lake trout x splake (s. Fontinalis x s. Namaycush) hybrid, did not reproduce in Georgian Bay, but this genotype is being replaced with pure-strain lake trout, whose early performance appears promising.

  18. The enigmatic Zerelia twin-lakes (Thessaly, Central Greece): two potential meteorite impact Craters

    NASA Astrophysics Data System (ADS)

    Dietrich, V. J.; Lagios, E.; Reusser, E.; Sakkas, V.; Gartzos, E.; Kyriakopoulos, K.

    2013-09-01

    Two circular permanent lakes of 150 and 250 m diameter and 6-8 m depth to an unconsolidated muddy bottom occur 250 m apart from each other in the agricultural fields SW of the town of Almiros (Thessaly, central Greece). The age of the lakes is assumed to be Late Pliocene to Early Holocene with a minimum age of approx. 7000 yr BP. The abundant polymict, quartz-rich carbonate breccia and clasts with a clay rich matrix in the shallow embankments of the lakes show weak stratification but no volcanic structures. The carbonate clasts and particles often display spheroidal shapes and consist of calcite aggregates with feathery, arborescent, variolitic to micro-sparitic textures and spheroidal fabrics, recrystallized and deformed glass-shaped fragments, calcite globules in quartz; thus indications of possible carbonate melting, quenching and devitrification. The carbonatic matrix includes small xenomorphic phases, such as chromspinel, zircon with blurred granular and skeletal textures, skeletal rutile and ilmenite, which are interpreted as relicts of partial melting and quenching under high temperatures of 1240-1800 °C. Only a few quartz fragments exhibit indistinct planar fractures. In several cases they include exotic Al-Si- and sulfur bearing Fe-phases, < 1-10 μm as globules. The modeled "Residual Gravity" profiles through the lakes indicate negative gravity anomalies of bowl-type structures down to 150 m for the eastern lake and down to 250 m for the larger western lake. Several hypotheses can be drawn upon to explain the origin of these enigmatic twin-lakes: (a) Maar-type volcanic craters; (b) hydrothermal or CO2/hydrocarbon gas explosion craters; (c) and (d) doline holes due to karstification; or (e) small meteorite impact craters, the latter being a plausible explanation due to geologic, petrologic, and geophysical evidence. The morphology and dimensions of the lakes as well as the density contrast tomography of the bedrock favor a meteorite impact hypothesis of a

  19. View of Lake Sabrina Dam and Lake Sabrina from east ...

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

    View of Lake Sabrina Dam and Lake Sabrina from east ridge showing spillway at photo center, view southwest - Bishop Creek Hydroelectric System, Plant 2, Lake Sabrina Dam, Bishop Creek, Bishop, Inyo County, CA

  20. Origins of rainbow smelt in Lake Ontario

    USGS Publications Warehouse

    Bergstedt, Roger A.

    1983-01-01

    The first rainbow smelt (Osmerus mordax) to enter Lake Ontario were probably migrants from an anadromous strain introduced into New York's Finger Lakes. Since the upper Great Lakes were originally stocked with a landlocked strain from Green Lake, Maine, subsequent migration to Lake Ontario from Lake Erie makes Lake Ontario unique among the Great Lakes in probably having received introductions from two distinct populations.

  1. David Morrison on Lake Vostok

    NASA Video Gallery

    Dr. David Morrison discusses the implications of research possibilities at Lake Vostok, one of the largest subglacial lakes located over two miles beneath the ice in Antarctica. The lake has been c...

  2. Lake Mead, NV

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Lake Mead, Nevada, (36.0N, 114.5E) where the water from the Colorado River empties after it's 273 mile journey through the Grand Canyon of Arizona is the subject of this photo. Other features of interest are Hoover Dam on the south shore of Lake Mead where cheap hydroelectric power is secondary to the water resources made available in this northern desert region and the resort city of Las Vegas, just to the west of Lake Mead.

  3. 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.

  4. Petrology and geochemistry of primary magmas trapped in melt inclusions in scoria of Beaunit Maar (Chaîne des Puys, Massif Central, France)

    NASA Astrophysics Data System (ADS)

    Jannot, S.; Schiano, P.; Boivin, P.; Clocchiatti, R.; Chazot, G.

    2003-04-01

    The Massif Central area, characterized by a typical intraplate alkaline serie, is the largest magmatic province of the West-European Rift system. Although it has been the subject of several studies, the nature of Massif Central sources is still a matter of debate and many hypotheses are proposed, including deep-rooted continental hotspot, metasomatised spinel lherzolites and an asthenospheric flow linked to the lithospheric root of the Alpine chain. The Chaîne des Puys is the last magmatic province of the French Massif Central and is composed of hundred young well-preserved volcanoes. The present work aims to supply information on the nature and the origin of the source chemistry of alkaline serie from the Chaîne des Puys, by characterizing the trace and major element composition of minute melts preserved as quenched glass inclusions inside olivines phenocrysts in scoria from the Beaunit Maar. Heating stage experiments performed at ambient pressure on partially crystallised primary melt inclusions suggest CO_2 oversaturation of the trapped melt, and an entrapment temperature around 1200^oC±10^oC. Daughter minerals analyses point to a Ti-and Ca-rich basaltic paragenesis, in good agreement with that of erupted basalts from the Chaîne des Puys. Major element compositions show that melts trapped in inclusions evolve by limited fractional crystallization. Inclusions trapped in the more primitive olivine phenocrysts (Fo85) have alkali-basalt compositions that fall on the primitive end of the compositional trend define by the lavas of the Chaîne des Puys. Their major element chemistry rules out the hypothesis of a mantle source in the spinel stability field and requires a garnet-bearing mantle source. Analyzed for trace-element composition by LA-ICP-MS, they display homogeneous, enriched patterns, similar to those characterizing oceanic island and continental basalts. They have high concentration of LILE and LREE/HREE ratios. Such trace-element feature are typical of

  5. Tectonically controlled vent migration during maar-diatreme formation: An example from a Miocene half-graben basin in SE Korea

    NASA Astrophysics Data System (ADS)

    Son, Moon; Kim, Jong Sun; Jung, Soohwan; Ki, Jin Seok; Kim, Min-Cheol; Sohn, Young Kwan

    2012-04-01

    Understanding the roles of external controls, such as hydrology and tectonics, is crucial for interpreting the evolution of a phreatomagmatic volcano and its subsurface structure called the diatreme. The Yangpori diatreme in a Miocene terrestrial half-graben basin of Korea provides an opportunity to assess the roles of synvolcanic fault movement in forming a maar-diatreme volcano. The exposed part of the diatreme fill consists of two offset-stacked sequences with contrasting lithofacies characteristics: a lower sequence (early diatreme fill) of locally stratified or bedded basaltic lapilli tuff and tuff in the northeastern part and an upper sequence (later diatreme fill) of dacite-clast-rich and disorganized tuff breccia in the southwestern part. The boundary between these sequences is abrupt, suggesting eruption of the volcano in two distinct phases. The first phase of eruption was driven by phreatomagmatic explosions mainly within the basin fill. Some of the diatreme fill was deposited in a local pond by debris flows and suspension settling of fines whereas the rest by fallout from eruption plumes and jets. The second phase of eruption was driven by phreatomagmatic explosions at a fracture aquifer within the basement, accompanying sudden lowering of the explosion locus. The later diatreme fill therefore contains abundant basement-derived dacite clasts. Its deposition was accomplished by en masse fallout of volcanic debris from dense collapsing columns. A number of faults and shear fractures were generated within and in the vicinity of the diatreme together with penecontemporaneous basaltic intrusions. Structural and geochemical analyses show that many of these structures are genetically related with the formation of the diatreme. The early diatreme fill was also tilted toward the southwest, suggesting southwestward shift of the locus of explosion and diatreme excavation. The explosion locus of the Yangpori volcano is therefore interpreted to have migrated both

  6. Lakes, Lagerstaetten, and Evolution

    NASA Astrophysics Data System (ADS)

    Kordesch, E. G.; Park, L. E.

    2001-12-01

    The diversity of terrestrial systems is estimated to be greater than in the marine realm. However no hard data yet exists to substantiate this claim. Ancient lacustrine deposits may preserve an exceptionally diverse fossil fauna and aid in determining continental faunal diversities. Fossils preserved in lake deposits, especially those with exceptional preservation (i.e. Konservat Lagerstaetten), may represent a dependable method for determining species diversity changes in the terrestrial environment because of their faunal completeness. Important Konservat Lagerstaetten, such as the Green River Formation (US) and Messel (Germany), both Eocene in age, are found in lake sediments and show a remarkable faunal diversity for both vertebrates and invertebrates. To date information from nearly 25 lake lagerstaetten derived from different types of lake basins from the Carboniferous to the Miocene have been collected and described. Carboniferous sites derive from the cyclothems of Midcontinent of the US while many Cenozoic sites have been described from North and South America as well as Europe and Australia. Asian sites contain fossils from the Mesozoic and Cenozoic. With this data, insight into the evolutionary processes associated with lake systems can be examined. Do lakes act as unique evolutionary crucibles in contrast to marine systems? The speciation of cichlid fishes in present-day African lakes appears to be very high and is attributed to the diversity of environments found in large rift lakes. Is this true of all ancient lakes or just large rift lakes? The longevity of a lake system may be an important factor in allowing speciation and evolutionary processes to occur; marine systems are limited only in the existence of environments as controlled by tectonics and sea level changes, on the order of tens of millions of years. Rift lakes are normally the longest lived in the millions of years. Perhaps there are only certain types of lakes in which speciation of

  7. 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)

  8. 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…

  9. Venezuela: Lake Maracaibo

    Atmospheric Science Data Center

    2013-04-18

    article title:  Oil Slicks on Lake Maracaibo, Venezuela     View Larger Image Several oil slicks occurred on Lake Maracaibo in northwestern Venezuela between ... wave facets divert reflected rays into many directions. An oil film dampens the presence of small wind-driven "capillary" waves, resulting ...

  10. 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

  11. GREAT LAKES LIMNOLOGY MONITORING

    EPA Science Inventory

    The Great Lakes National Program Office (GLNPO) of the United States Environmental Protection Agency (USEPA) has primary responsibility within the U.S. for conducting surveillance monitoring of the offshore waters of the Great Lakes. This monitoring is intended to fulfill provis...

  12. 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…

  13. 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.

  14. 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…

  15. Lake trophic applications: Wisconsin

    NASA Technical Reports Server (NTRS)

    Scarpace, F.

    1981-01-01

    Efforts to classify the water quality characteristics of lakes using LANDSAT imagery are reported. Image processing and registration techniques are described. A lake classification scheme which involves the assignment of a trophic class number was used in the data analysis. The resulting values were compared to the corresponding rank assignment derived from field measurements.

  16. 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…

  17. Lakes and reservoirs

    SciTech Connect

    Taub, F.B.

    1984-01-01

    This volume in the Ecosystems of the World series studies lakes and reservoirs. The book opens with a discussion of the ecosystem processes that are common to all lakes and reservoirs and then proceeds to a description of mathematical models of these processes. The chapters concentrate on lakes and reservoirs in different parts of the world, ranging from polar to tropical lakes, and in many of the chapters the effects of human activities such as dam construction, increased nutrient inputs, toxic contaminants and fish introduction, are also considered. The book concludes with a summary of the efforts at lake restoration that are being undertaken in many communities in an attempt to undo the damage that has resulted from some of these activities.

  18. Lake trout in northern Lake Huron spawn on submerged drumlins

    USGS Publications Warehouse

    Riley, Stephen C.; 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.

  19. Spatial patterns in PCB concentrations of Lake Michigan lake trout

    USGS Publications Warehouse

    Madenjian, Charles P.; DeSorcie, Timothy J.; Stedman, Ralph M.; Brown, Edward H., Jr.; Eck, Gary W.; Schmidt, Larry J.; Hesselberg, Robert J.; Chernyak, Sergei M.; Passino-Reader, Dora R.

    1999-01-01

    Most of the PCB body burden in lake trout (Salvelinus namaycush) of the Great Lakes is from their food. PCB concentrations were determined in lake trout from three different locations in Lake Michigan during 1994–1995, and lake trout diets were analyzed at all three locations. The PCB concentrations were also determined in alewife (Alosa pseudoharengus), rainbow smelt (Osmerus mordax), bloater (Coregonus hoyi), slimy sculpin (Cottus cognatus), and deepwater sculpin (Myoxocephalus thompsoni), five species of prey fish eaten by lake trout in Lake Michigan, at three nearshore sites in the lake. Despite the lack of significant differences in the PCB concentrations of alewife, rainbow smelt, bloater, slimy sculpin, and deepwater sculpin from the southeastern nearshore site near Saugatuck (Michigan) compared with the corresponding PCB concentrations from the northwestern nearshore site near Sturgeon Bay (Wisconsin), PCB concentrations in lake trout at Saugatuck were significantly higher than those at Sturgeon Bay. The difference in the lake trout PCB concentrations between Saugatuck and Sturgeon Bay could be explained by diet differences. The diet of lake trout at Saugatuck was more concentrated in PCBs than the diet of Sturgeon Bay lake trout, and therefore lake trout at Saugatuck were more contaminated in PCBs than Sturgeon Bay lake trout. These findings were useful in interpreting the long-term monitoring series for contaminants in lake trout at both Saugatuck and the Wisconsin side of the lake.

  20. 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.

  1. Lake whitefish and lake herring population structure and niche in ten south-central Ontario lakes

    USGS Publications Warehouse

    Carl, Leon M.; McGuiness, Fiona

    2006-01-01

    This study compares simple fish communities of ten oligotrophic lakes in south-central Ontario. Species densities and population size structure vary significantly among these lake communities depending on fish species present beyond the littoral zone. Lake whitefish are fewer and larger in the presence of lake herring than in their absence. Diet analysis indicates that lake whitefish shift from feeding on both plankton and benthic prey when lake herring are absent to a primarily benthic feeding niche in the presence of lake herring. When benthic round whitefish are present, lake whitefish size and density decline and they move lower in the lake compared to round whitefish. Burbot are also fewer and larger in lakes with lake herring than in lakes without herring. Burbot, in turn, appear to influence the population structure of benthic coregonine species. Lower densities of benthic lake whitefish and round whitefish are found in lakes containing large benthic burbot than in lakes with either small burbot or where burbot are absent. Predation on the pelagic larvae of burbot and lake whitefish by planktivorous lake herring alters the size and age structure of these populations. As life history theory predicts, those species with poor larval survival appear to adopt a bet-hedging life history strategy of long-lived individuals as a reproductive reserve.

  2. Lake sturgeon population characteristics in Rainy Lake, Minnesota and Ontario

    USGS Publications Warehouse

    Adams, W.E., Jr.; Kallemeyn, L.W.; Willis, D.W.

    2006-01-01

    Rainy Lake contains a native population of lake sturgeon Acipenser fulvescens that has been largely unstudied. The aims of this study were to document the population characteristics of lake sturgeon in Rainy Lake and to relate environmental factors to year-class strength for this population. Gill-netting efforts throughout the study resulted in the capture of 322 lake sturgeon, including 50 recaptures. Lake sturgeon in Rainy Lake was relatively plump and fast growing compared with a 32-population summary. Population samples were dominated by lake sturgeon between 110 and 150 cm total length. Age–structure analysis of the samples indicated few younger (<10 years) lake sturgeon, but the smallest gill net mesh size used for sampling was 102 mm (bar measure) and would not retain small sturgeon. Few lake sturgeon older than age 50 years were captured, and maximum age of sampled fish was 59 years. Few correlations existed between lake sturgeon year-class indices and both annual and monthly climate variables, except that mean June air temperature was positively correlated with year-class strength. Analysis of Rainy Lake water elevation and resulting lake sturgeon year-class strength indices across years yielded consistent but weak negative correlations between late April and early June, when spawning of lake sturgeon occurs. The baseline data collected in this study should allow Rainy Lake biologists to establish more specific research questions in the future.

  3. 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

  4. 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

  5. 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....

  6. Lake Mead, NV

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Lake Mead, Nevada, (36.0N, 114.5E) where the water from the Colorado River empties after it's 273 mile journey through the Grand Canyon of Arizona is the subject of this photo. Other features of interest are Hoover Dam on the south shore of Lake Mead where cheap hydroelectric power is secondary to the water resources made available in this northern desert region and the resort city of Las Vegas, just to the west of Lake Mead. In this harsh desert environment, color infrared photography readily penetrates haze, detects and portrays vegetation as shades of red.

  7. Dating Taal Lake sediment of Philippines by using the bomb radiocarbon curve

    NASA Astrophysics Data System (ADS)

    Li, H.; Xu, X.

    2008-12-01

    Taal Lake is located in Batangas Province of central Philippines (14° 00.1'N, 120° 59.1'E), with a surface area of 267 km2, a maximum depth of 176 m and an elevation of 3 m above sea level. The lake occupies the famous Taal Volcano system which consists of a 15 × 22 km prehistoric caldera. The 5 km wide Taal Volcano Island which has 47 craters and 4 maars, lies in the north central Taal Lake. With 34 recorded eruptions, Taal Volcano is considered one of the most active volcanic centers in the Philippines and is one of the 16 monitored volcanoes by the Global Volcanism Network. In order to investigate specifically geochemical and isotopic proxies which have paleo-eruption and paleoclimate significances in the sediment cores, we had retrieved two gravity cores from the lake in 2007: TLS1 with 90cm length from a water depth of 100m, and TLS2 with 120cm length from a water depth of 15m. Core TLS2 contains plant remains at 16 horizons which were selected for AMS 14C dating at UCI. Only one of the sixteen plant samples has a δ13C value of -16.4 per mil, whereas the rest samples have the δ13C values ranging from -24.2 to -30.1 per mil. The δ13C values indicate that the plant remains are mainly terrestrial C3 plants. The comparisons of Acid-Base-Acid (ABA) treated samples with non-ABA treated samples show the same results within uncertainty. Except for the sample at 16.7cm, the Δ14C of samples from 0 to 95cm are 51.9~401.9 per mil peaked at 79cm depth, matching very well with the bomb 14C curve determined in tree rings. The distribution of the bomb 14C profile allows us to establish the chronology of Core TLS2, which yields a constant sedimentation rate of 2.04cm/year. Based on this chronology, living plants around Taal Lake may have a lower initial Δ14C (-30 per mil) compared to the Modern Standard. Core TLS1 contains much less plant remains. Three samples from depths of 1.2, 38.5 and 72 cm have Δ14C values of -32.9, 9.9 and -141.8 per mil, respectively. This

  8. Can lake sensitivity to desiccation be predicted from lake geometry?

    NASA Astrophysics Data System (ADS)

    Torabi Haghighi, Ali; Menberu, Meseret Walle; Aminnezhad, Mousa; Marttila, Hannu; Kløve, Bjørn

    2016-08-01

    Declining lake levels (Aral Sea syndrome) can be caused by changes in climate, increased water use or changed regulation patterns. This paper introduces a novel lake geometry index (LGI) to quantify lake hydrological characteristics. The index was developed using a large representative dataset of lake hypsographic characteristics from 152 lakes and man-made reservoirs. Using the LGI index, lakes can be classified into five groups: groups 1-4 when LGI is 0.5-2.5, 2.5-4.5, 4.5-6.5 and 6.5-8.5, respectively, and group 5 when LGI is >8.5. Naturally shallow and vast lakes and wetlands fall into the first group and deep man-made reservoirs in narrow valleys are in group 5. The response of three different lake systems (LGI 0.75, 2.75 and 6.5) to different water flow scenarios was then simulated using the water balance equation. From this, the index 'potential lake area' (Apot) was developed to show lake responses to changed hydro-climatological conditions. Apot and LGI can be used to classify lakes into open or closed systems. Simulations showed that lakes with low LGI have a shorter response time to flow and climate changes. As a result, the impact of water balance restoration is faster for lakes with low LGI than for lakes with high LGI. The latter are also more vulnerable to climate variation and change.

  9. GREAT LAKES PLANKTON PROGRAM

    EPA Science Inventory

    Phytoplankton, which have short carbon turnover rates, are sensitive to water quality conditions and grazing by zooplankton, and thus respond rapidly to perturbations of the lake ecosystem. The determination of phytoplankton abundance and species composition is one method to tra...

  10. 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

  11. 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.

  12. Lake Chad, Chad, Africa

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The fluctuating water levels of Lake Chad, (13.0N, 15.0E) at the intersection of the borders of Chad, Niger and Cameroon in the Sahara Desert, is an index of the drought in Africa. The lake level continues to decrease as indicated by the growing number and extent of emerging islands as previously submerged ancient sand dunes become visible. The water impounded between the dunes is probably because of local rainfall rather than a reversal of desertification.

  13. WHISKER LAKE WILDERNESS, WISCONSIN.

    USGS Publications Warehouse

    Schulz, Klaus J.

    1984-01-01

    The mineral-resource potential of the Whisker Lake Wilderness in northeastern Wisconsin was evaluated. Only a strip along the southwest corner of the wilderness is assessed as having probable mineral-resource potential. If mineral deposits exist, they probably are of the massive sulfide type. The geologic terrain precludes the presence of fossil fuel resources. Sand and gravel and peat in swampy lowlands are the only resources of the Whisker lake Wilderness.

  14. 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

  15. 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

  16. 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

  17. Availability of lake trout reproductive habitat in the Great Lakes

    USGS Publications Warehouse

    Edsall, Thomas A.; Kennedy, Gregory W.

    1995-01-01

    A decades-long program to reestablish self-sustaining stocks of lake trout (Salvelinus namaycush) in the four lower Great Lakes produced excellent fisheries supported by stocked fish. These fish spawned widely and small numbers of their offspring were collected intermittently from Lakes Michigan, Huron, and Ontario, but no self-sustaining stocks were established. Irt this paper we address habitat sufficiency as a factor in the failure of stocked lake trout to established self-sustaining populations in the four lower Great Lakes. We present the previously unpublished results of lake trout spawning habitat surveys conducted at seven sites in the Great Lakes since 1987 and we compare them with the published results of similar surveys conducted at 24 other sites in the four lower lakes since 1981. Our evaluation indicates all but two of these sites can support the production of viable fry from spawnings by the shallow-water strains of lake trout that are stocked in the Great Lakes. However, some of the best spawning, egg, and fry habitat in the lower Great Lakes seems to be at deeper offshore sites that may be unattractive to these shallow-water strains. Thus, we suggest also stocking the lower four lakes with strains from Lake Superior that might more fully exploit the best spawning habitat at these deeper, offshore sites.

  18. Contaminants in American alligator eggs from Lake Apopka, Lake Griffin, and Lake Okeechobee, Florida

    USGS Publications Warehouse

    Heinz, G.H.; Percival, H.F.; Jennings, Michael L.

    1991-01-01

    Residues of organochlorine pesticides, polychlorinated biphenyls (PCBs), and 16 elements were measured in American alligator (Alligator mississippiensis) eggs collected in 1984 from Lakes Apopka, Griffin, and Okeechobee in central and south Florida. Organochlorine pesticides were highest in eggs from Lake Apopka. None of the elements appeared to be present at harmful concentrations in eggs from any of the lakes. A larger sample of eggs was collected in 1985, but only from Lakes Griffin, a lake where eggs were relatively clean, and Apopka, where eggs were most contaminated. In 1985, hatching success of artificially incubated eggs was lower for Lake Apopka, and several organochlorine pesticides were higher than in eggs from Lake Griffin. However, within Lake Apopka, higher levels of pesticides in chemically analyzed eggs were not associated with reduced hatching success of the remaining eggs in the clutch. Therefore, it did not appear that any of the pesticides we measured were responsible for the reduced hatching of Lake Apopka eggs.

  19. Big lake records preserved in a little lake's sediment: An example from Silver Lake, Michigan, USA

    USGS Publications Warehouse

    Fisher, T.G.; Loope, W.L.; Pierce, W.; Jol, H.M.

    2007-01-01

    We reconstruct postglacial lake-level history within the Lake Michigan basin using soil stratigraphy, ground-penetrating radar (GPR), sedimentology and 14C data from the Silver Lake basin, which lies adjacent to Lake Michigan. Stratigraphy in nine vibracores recovered from the floor of Silver Lake appears to reflect fluctuation of water levels in the Lake Michigan basin. Aeolian activity within the study area from 3,000 years (cal yr. B.P.) to the present was inferred from analysis of buried soils, an aerial photograph sequence, and GPR. Sediments in and around Silver Lake appear to contain a paleoenvironmental record that spans the entire post-glacial history of the Lake Michigan basin. We suggest that (1) a pre-Nipissing rather than a Nipissing barrier separated Silver Lake basin from the Lake Michigan basin, (2) that the Nipissing transgression elevated the water table in the Silver Lake basin about 6,500 cal yr. B.P., resulting in reestablishment of a lake within the basin, and (3) that recent dune migration into Silver Lake is associated with levels of Lake Michigan.

  20. Evidence of Lake Trout reproduction at Lake Michigan's mid-lake reef complex

    USGS Publications Warehouse

    Janssen, J.; Jude, D.J.; Edsall, T.A.; Paddock, R.W.; Wattrus, N.; Toneys, M.; McKee, P.

    2006-01-01

    The Mid-Lake Reef Complex (MLRC), a large area of deep (> 40 m) reefs, was a major site where indigenous lake trout (Salvelinus namaycush) in Lake Michigan aggregated during spawning. As part of an effort to restore Lake Michigan's lake trout, which were extirpated in the 1950s, yearling lake trout have been released over the MLRC since the mid-1980s and fall gill net censuses began to show large numbers of lake trout in spawning condition beginning about 1999. We report the first evidence of viable egg deposition and successful lake trout fry production at these deep reefs. Because the area's existing bathymetry and habitat were too poorly known for a priori selection of sampling sites, we used hydroacoustics to locate concentrations of large fish in the fall; fish were congregating around slopes and ridges. Subsequent observations via unmanned submersible confirmed the large fish to be lake trout. Our technological objectives were driven by biological objectives of locating where lake trout spawn, where lake trout fry were produced, and what fishes ate lake trout eggs and fry. The unmanned submersibles were equipped with a suction sampler and electroshocker to sample eggs deposited on the reef, draw out and occasionally catch emergent fry, and collect egg predators (slimy sculpin Cottus cognatus). We observed slimy sculpin to eat unusually high numbers of lake trout eggs. Our qualitative approaches are a first step toward quantitative assessments of the importance of lake trout spawning on the MLRC.

  1. Winter Lake Breezes near the Great Salt Lake

    NASA Astrophysics Data System (ADS)

    Crosman, Erik T.; Horel, John D.

    2016-05-01

    Case studies of lake breezes during wintertime cold air pools in Utah's Salt Lake Valley are examined. While summer breezes originating from the Great Salt Lake are typically deeper, of longer duration, and have higher wind speeds than winter breezes, the rate of inland penetration and cross-frontal temperature differences can be higher during the winter. The characteristics of winter breezes and the forcing mechanisms controlling them (e.g., snow cover, background flow, vertical stability profile, clouds, lake temperature, lake sheltering, and drainage pooling) are more complex and variable than those evident in summer. During the afternoon in the Salt Lake Valley, these lake breezes can lead to elevated pollution levels due to the transport of fine particle pollutants from over the Great Salt Lake, decreased vertical mixing depth, and increased vertical stability.

  2. 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.

  3. The Wandering Lake

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In the area at the very far eastern corner of China's Taklimakan Desert, Lop Nor Lake was located up until some years ago. Lop Nor, also called the 'the heart of the heart' of Asia, was the place where the waters of the largest inner basin (i.e., not flowing into the sea) of the world-including the Tarim and Kum-daria Rivers-were collected. Depending on the balance between rainfall water yield and evaporation, both position and size of the lake were strongly variable, thus giving rise to the legend of the Wandering Lake. 'Lop City' was the place where Marco Polo took his last rest before facing the one-year long crossing of the Gobi Desert. Starting from the end of the 19th century, several explorers tried to find the legendary place. One such explorer was Sven Hedin, who was commissioned by the Governor of Nanjing to lead an expedition to find the lake. In 1937, the Swedish explorer published his book entitled The Wandering Lake. Comparing this very precise map from Sven Hedin's book with the above Moderate-resolution Imaging Spectroradiometer (MODIS) false-color image (acquired on October 28, 2001), one can find a faint sign on the soil where the Lop Nor was located. This image, derived using a combination of MODIS' near-infrared and red channels (vegetation in red), shows where the Tarim River waters currently end their flow. The Wandering Lake does not exist anymore. The combination of climate change and human exploitation of water resources for agriculture caused the disappearance of the lake. This image was processed by Telespazio, Earth Observation division, new products development facility in Rome, Italy. The MODIS sensor flies aboard NASA's Terra spacecraft, launched in December 1999. Caption and image courtesy Luca Pietranera, Telespazio, Rome, Italy, based on data from the MODIS Science Team

  4. Lake Sarez, Tajikistan

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Lake Sarez (top), deep in the Pamir mountains of Tajikistan, was created 90 years ago when a strong earthquake triggered a massive landslide that, in turn, became a huge dam along the Murghob River, now called the Usoi Dam. The resulting lake is perched above surrounding drainages at an elevation greater than 3000m, and is part of the watershed that drains the towering Akademi Nauk Range (see the regional image, lower). The lake is 61 km long and as deep as 500 m, and holds an estimated 17 cubic km of water. The area experiences considerable seismic activity, and scientists fear that part of the right bank may slump into the lake, creating a huge wave that will top over and possibly breach the natural dam. Such a wave would create a catastrophic flood downstream along the Bartang, Panj and Amu Darya Rivers, perhaps reaching all the way to the Aral Sea. Currently, central Asian governments, as well as the World Bank and the UN are monitoring the dam closely, and have proposed gradually lowering the lake level as a preventive measure. More information about the lake is available at the following web sites: Lake Sarez Study group, UN Report, Reliefweb Digital photograph numbers ISS002-E-7771 and ISS002-E-7479 were taken in the spring of 2001 from Space Station Alpha and are provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

  5. Examining indirect effects of lake trout recovery

    EPA Science Inventory

    With the recovery of lake trout populations in Lake Superior, there are indications of decreased forage fish abundance and density-dependence in lake trout. In Lake Superior, lean lake trout historically occupied depths < 60 m, and siscowet lake trout occupied depths > 60 m...

  6. View of Lake Sabrina Dam and dry Lake Sabrina Basin ...

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

    View of Lake Sabrina Dam and dry Lake Sabrina Basin with the upstream side of the outlet structure visible at photo center, view to north-northwest - Bishop Creek Hydroelectric System, Plant 2, Lake Sabrina Dam, Bishop Creek, Bishop, Inyo County, CA

  7. 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

  8. Lake Michigan lake trout PCB model forecast post audit

    EPA Science Inventory

    Scenario forecasts for total PCBs in Lake Michigan (LM) lake trout were conducted using the linked LM2-Toxics and LM Food Chain models, supported by a suite of additional LM models. Efforts were conducted under the Lake Michigan Mass Balance Study and the post audit represents th...

  9. Mono Lake Excursion Reviewed

    NASA Astrophysics Data System (ADS)

    Liddicoat, J. C.; Coe, R. S.

    2007-05-01

    The Mono Lake Excursion as recorded in the Mono Basin, CA, has an older part that is about negative 30 degrees inclination and about 300 degrees declination during low relative field intensity. Those paleomagnetic directions are closely followed by greater than 80 degrees positive inclination and east declination of about 100 degrees during higher relative field intensity. A path of the Virtual Geomagnetic Poles (VGPs) for the older part followed from old to young forms a large clockwise loop that reaches 35 degrees N latitude and is centered at about 35 degrees E longitude. That loop is followed by a smaller one that is counterclockwise and centered at about 70 degrees N latitude and 270 degrees E longitude (Denham & Cox, 1971; Denham, 1974; Liddicoat & Coe, 1979). The Mono Lake Excursion outside the Mono Basin in western North America is recorded as nearly the full excursion at Summer Lake, OR (Negrini et al., 1984), and as the younger portion of steep positive inclination/east declination in the Lahontan Basin, NV. The overall relative field intensity during the Mono Lake Excursion in the Lahontan Basin mirrors very closely the relative field intensity in the Mono Basin (Liddicoat, 1992, 1996; Coe & Liddicoat, 1994). Using 14C and 40Ar/39Ar dates (Kent et al., 2002) and paleoclimate and relative paleointensity records (Zimmerman et al., 2006) for the Mono Lake Excursion in the Mono Basin, it has been proposed that the Mono Lake Excursion might be older than originally believed and instead be the Laschamp Excursion at about 40,000 yrs B.P. (Guillou et al., 2004). On the contrary, we favor a younger age for the Mono Lake Excursion, about 32,000 yrs B.P., using the relative paleointensity in the Mono Basin and Lahontan Basin and 14C dates from the Lahontan Basin (Benson et al., 2002). The age of about 32,000 yrs B.P. is also in accord with the age (32,000- 34,000 yrs B.P.) reported by Channell (2006) for the Mono Lake Excursion at ODP Site 919 in the Irminger Basin

  10. Microplastic pollution in lakes and lake shoreline sediments - A case study on Lake Bolsena and Lake Chiusi (central Italy).

    PubMed

    Fischer, Elke Kerstin; Paglialonga, Lisa; Czech, Elisa; Tamminga, Matthias

    2016-06-01

    Rivers and effluents have been identified as major pathways for microplastics of terrestrial sources. Moreover, lakes of different dimensions and even in remote locations contain microplastics in striking abundances. This study investigates concentrations of microplastic particles at two lakes in central Italy (Lake Bolsena, Lake Chiusi). A total number of six Manta Trawls have been carried out, two of them one day after heavy winds occurred on Lake Bolsena showing effects on particle distribution of fragments and fibers of varying size categories. Additionally, 36 sediment samples from lakeshores were analyzed for microplastic content. In the surface waters 2.68 to 3.36 particles/m(3) (Lake Chiusi) and 0.82 to 4.42 particles/m(3) (Lake Bolsena) were detected, respectively. Main differences between the lakes are attributed to lake characteristics such as surface and catchment area, depth and the presence of local wind patterns and tide range at Lake Bolsena. An event of heavy winds and moderate rainfall prior to one sampling led to an increase of concentrations at Lake Bolsena which is most probable related to lateral land-based and sewage effluent inputs. The abundances of microplastic particles in sediments vary from mean values of 112 (Lake Bolsena) to 234 particles/kg dry weight (Lake Chiusi). Lake Chiusi results reveal elevated fiber concentrations compared to those of Lake Bolsena what might be a result of higher organic content and a shift in grain size distribution towards the silt and clay fraction at the shallow and highly eutrophic Lake Chiusi. The distribution of particles along different beach levels revealed no significant differences. PMID:27104923

  11. Michigan: The Great Lakes State

    ERIC Educational Resources Information Center

    McKay, Sandra Lee; La Luzerne-Oi, Sally

    2009-01-01

    Although Michigan is often called the "Wolverine State," its more common nickname is the "Great Lakes State." This name comes from the fact that Michigan is the only state in the United States that borders four of the five Great Lakes. Also referred to as the "Water Wonderland," Michigan has 11,000 additional lakes, 36,000 miles of streams, and…

  12. Viruses in Antarctic lakes

    NASA Technical Reports Server (NTRS)

    Kepner, R. L. Jr; Wharton, R. A. Jr; Suttle, C. A.; Wharton RA, J. r. (Principal Investigator)

    1998-01-01

    Water samples collected from four perennially ice-covered Antarctic lakes during the austral summer of 1996-1997 contained high densities of extracellular viruses. Many of these viruses were found to be morphologically similar to double-stranded DNA viruses that are known to infect algae and protozoa. These constitute the first observations of viruses in perennially ice-covered polar lakes. The abundance of planktonic viruses and data suggesting substantial production potential (relative to bacteria] secondary and photosynthetic primary production) indicate that viral lysis may be a major factor in the regulation of microbial populations in these extreme environments. Furthermore, we suggest that Antarctic lakes may be a reservoir of previously undescribed viruses that possess novel biological and biochemical characteristics.

  13. Transient Tsunamis in Lakes

    NASA Astrophysics Data System (ADS)

    Couston, L.; Mei, C.; Alam, M.

    2013-12-01

    A large number of lakes are surrounded by steep and unstable mountains with slopes prone to failure. As a result, landslides are likely to occur and impact water sitting in closed reservoirs. These rare geological phenomena pose serious threats to dam reservoirs and nearshore facilities because they can generate unexpectedly large tsunami waves. In fact, the tallest wave experienced by contemporary humans occurred because of a landslide in the narrow bay of Lituya in 1958, and five years later, a deadly landslide tsunami overtopped Lake Vajont's dam, flooding and damaging villages along the lakefront and in the Piave valley. If unstable slopes and potential slides are detected ahead of time, inundation maps can be drawn to help people know the risks, and mitigate the destructive power of the ensuing waves. These maps give the maximum wave runup height along the lake's vertical and sloping boundaries, and can be obtained by numerical simulations. Keeping track of the moving shorelines along beaches is challenging in classical Eulerian formulations because the horizontal extent of the fluid domain can change over time. As a result, assuming a solid slide and nonbreaking waves, here we develop a nonlinear shallow-water model equation in the Lagrangian framework to address the problem of transient landslide-tsunamis. In this manner, the shorelines' three-dimensional motion is part of the solution. The model equation is hyperbolic and can be solved numerically by finite differences. Here, a 4th order Runge-Kutta method and a compact finite-difference scheme are implemented to integrate in time and spatially discretize the forced shallow-water equation in Lagrangian coordinates. The formulation is applied to different lake and slide geometries to better understand the effects of the lake's finite lengths and slide's forcing mechanism on the generated wavefield. Specifically, for a slide moving down a plane beach, we show that edge-waves trapped by the shoreline and free

  14. Reevaluation of lake trout and lake whitefish bioenergetics models

    USGS Publications Warehouse

    Madenjian, Charles P.; Pothoven, Steve A.; Kao, Yu-Chun

    2013-01-01

    Using a corrected algorithm for balancing the energy budget, we reevaluated the Wisconsin bioenergetics model for lake trout (Salvelinus namaycush) in the laboratory and for lake whitefish (Coregonus clupeaformis) in the laboratory and in the field. For lake trout, results showed that the bioenergetics model slightly overestimated food consumption by the lake trout when they were fed low and intermediate rations, whereas the model predicted food consumption by lake trout fed ad libitum without any detectable bias. The slight bias in model predictions for lake trout on restricted rations may have been an artifact of the feeding schedule for these fish, and we would therefore recommend application of the Wisconsin lake trout bioenergetics model to lake trout populations in the field without any revisions to the model. Use of the Wisconsin bioenergetics model for coregonids resulted in overestimation of food consumption by lake whitefish both in the laboratory and in the field by between 20 and 30%, on average. This overestimation of food consumption was most likely due to overestimation of respiration rate. We therefore adjusted the respiration component of the bioenergetics model to obtain a good fit to the observed consumption in our laboratory tanks. The adjusted model predicted the consumption in the laboratory and the field without any detectable bias. Until a detailed lake whitefish respiration study can be conducted, we recommend application of our adjusted version of the Wisconsin generalized coregonid bioenergetics model to lake whitefish populations in the field.

  15. Maturity schedules of lake trout in Lake Michigan

    USGS Publications Warehouse

    Madenjian, Charles P.; DeSorcie, Timothy J.; Stedman, Ralph M.

    1998-01-01

    We determined maturity schedules of male and female lake trout (Salvelinus namaycush) in Lake Michigan from nearshore populations and from an offshore population on Sheboygan Reef, which is located in midlake. Gill nets and bottom trawls were used to catch lake trout in fall 1994 and 1995 from two nearshore sites and Sheboygan Reef. Each lake trout was judged immature or mature, based on visual examination of gonads. Probit analysis, coupled with relative potency testing, revealed that age-at-maturity and length-at-maturity were similar at the two nearshore sites, but that lake trout from the nearshore sites matured at a significantly earlier age than lake trout from Sheboygan Reef. However, length at maturity for the nearshore populations was nearly identical to that for the offshore population, suggesting that rate of lake trout maturation in Lake Michigan was governed by growth rather than age. Half of the lake trout males reached maturity at a total length of 580 mm, whereas half of the females were mature at a length of 640 mm. Over half of nearshore males were mature by age 5, and over half the nearshore females matured by age 6. Due to a slower growth rate, maturity was delayed by 2 years on Sheboygan Reef compared with the nearshore populations. Documentation of this delay in maturation may be useful in deciding stocking allocations for lake trout rehabilitation in Lake Michigan.

  16. Gas exchange on Mono Lake and Crowley Lake, California

    NASA Technical Reports Server (NTRS)

    Wanninkhof, Rik; Ledwell, James R.; Broecker, Wallace S.

    1987-01-01

    Gas exchange coefficients (k) have been determined for freshwater Crowley Lake and saline Mono Lake through the use of a man-made purposefully injected gas, SF6. The concentration decreased from an initial value of 40 to 4 pmol/L for Mono Lake and from 20 to 1 pmol/L for Crowley lake over a period of 6 wks. Wind-speed (u) records from anemometers on the shore of each lake made it possible to determine the relationship between k and u. The average u and k values for the experiment were identical for the two lakes, despite the large chemical differences. It is estimated that, for the u values observed over Mono Lake from July to December 1984, the exchange of CO2 occurred 2.5 times faster than without chemical enhancement. This is a factor of 4 lower than needed to explain the high invasion rate of C-14 produced by nuclear bomb tests.

  17. Lake whitefish diet, condition, and energy density in Lake Champlain and the lower four Great Lakes following dreissenid invasions

    USGS Publications Warehouse

    Herbst, Seth J.; Marsden, J. Ellen; Lantry, Brian F.

    2013-01-01

    Lake Whitefish Coregonus clupeaformis support some of the most valuable commercial freshwater fisheries in North America. Recent growth and condition decreases in Lake Whitefish populations in the Great Lakes have been attributed to the invasion of the dreissenid mussels, zebra mussels Dreissena polymorpha and quagga mussels D. bugensis, and the subsequent collapse of the amphipod, Diporeia, a once-abundant high energy prey source. Since 1993, Lake Champlain has also experienced the invasion and proliferation of zebra mussels, but in contrast to the Great Lakes, Diporeia were not historically abundant. We compared the diet, condition, and energy density of Lake Whitefish from Lake Champlain after the dreissenid mussel invasion to values for those of Lake Whitefish from Lakes Michigan, Huron, Erie, and Ontario. Lake Whitefish were collected using gill nets and bottom trawls, and their diets were quantified seasonally. Condition was estimated using Fulton's condition factor (K) and by determining energy density. In contrast to Lake Whitefish from some of the Great Lakes, those from Lake Champlain Lake Whitefish did not show a dietary shift towards dreissenid mussels, but instead fed primarily on fish eggs in spring, Mysis diluviana in summer, and gastropods and sphaeriids in fall and winter. Along with these dietary differences, the condition and energy density of Lake Whitefish from Lake Champlain were high compared with those of Lake Whitefish from Lakes Michigan, Huron, and Ontario after the dreissenid invasion, and were similar to Lake Whitefish from Lake Erie; fish from Lakes Michigan, Huron, and Ontario consumed dreissenids, whereas fish from Lake Erie did not. Our comparisons of Lake Whitefish populations in Lake Champlain to those in the Great Lakes indicate that diet and condition of Lake Champlain Lake Whitefish were not negatively affected by the dreissenid mussel invasion.

  18. Temperature Trends in Montane Lakes

    NASA Astrophysics Data System (ADS)

    Melack, J. M.; Sadro, S.; Jellison, R.

    2014-12-01

    Long-term temperature trends in lakes integrate hydrological and meteorological factors. We examine temperature trends in a small montane lake with prolonged ice-cover and large seasonal snowfall and in a large saline lake. Emerald Lake, located in the Sierra Nevada (California), is representative of high-elevation lakes throughout the region. No significant trend in outflow temperature was apparent from 1991to 2012. Snowfall in the watershed accounted for 93% of the variability in average summer lake temperatures. Mono Lake (California) lies in a closed, montane basin and is hypersaline and monomictic or meromictic. Temperature profiles have been collected from 1982 to 2010. In the upper water column, the July-August-September water temperatures increased 0.8-1.0°C over the 29 years. This rate of warming is less than published estimates based on satellite-derived skin temperatures and will discussed in the context of general limnological interpretation of temperature trends.

  19. Institutional aspects of lake management

    NASA Astrophysics Data System (ADS)

    Born, Stephen M.; Rumery, Carolyn

    1989-01-01

    The major barriers to successful lake management are institutional. However, in contrast to the technical and limnological dimensions of lake management, the institutional aspects of managing lakes have received little attention. The institutional factors that are important for successful lake management outcomes are: overlapping areal jurisdiction among governmental units, fragmented functional program responsibilities, ineffective coordination, limited authority, financial constraints, private sector roles, and inadequate public awareness and consensus. The range of typical institutional problems confronting lake management are well illustrated through experiences from the state of Wisconsin, USA. Because lake management programs with institutional shortcomings rarely realize their goals, it is critical to assimilate, evaluate, and apply our experience to date with the institutional arrangements necessary to effectively manage lake resources.

  20. CONTOURITES IN LAKE SUPERIOR

    EPA Science Inventory

    Contour currents influence sedimentation in an area 15 km wide and 65 km long at the base of the slope off the Keweenaw Peninsula in Lake Superior, northwestern Michigan. Seismic-reflection profiles (3.5 kHz) from this area show distinct wavy reflectors in a scoured trough at a d...

  1. Utah: Salt Lake City

    Atmospheric Science Data Center

    2014-05-15

    ... mountains surrounding Salt Lake City are renowned for the dry, powdery snow that results from the arid climate and location at the ... should be used with the red filter placed over your left eye. The canyons and peaks of the Uinta and Wasatch Mountains are ...

  2. Quebec: Lake Manicouagan

    Atmospheric Science Data Center

    2013-04-17

    ... and other erosional processes have reduced the extent of the crater, with the original diameter estimated at about 100 kilometers. This ... metamorphic effects are abundant in the target rocks of the crater floor. Today Lake Manicouagan serves as a reservoir and is one of ...

  3. The People's Lake

    ERIC Educational Resources Information Center

    Carlson, Karen Townsend

    1975-01-01

    Citizen action to stop the disposal of taconite tailings into Lake Superior was unsuccessful when the courts settled in the favor of industry. Although citizen research revealed a form of asbestos, as well as other toxic chemicals in the discharged wastes, company representatives stated that there were no health hazards. (MA)

  4. Great Minds? Great Lakes!

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Chicago, IL. Great Lakes National Program Office.

    This booklet introduces an environmental curriculum for use in a variety of elementary subjects. The lesson plans provide an integrated approach to incorporating Great Lakes environmental issues into the subjects of history, social studies, and environmental sciences. Each of these sections contains background information, discussion points, and a…

  5. Echoes of Bark Lake.

    ERIC Educational Resources Information Center

    Duenkel, Nicky; Hemstreet, Jeff

    1997-01-01

    Two former staff members reflect on their feelings about the August 1995 closing of Bark Lake Leadership Centre (Ontario, Canada), which for 49 years had offered outdoor adventure and environmental education courses to youth and adults. They discuss their experiences as both students and teachers at the center, which helped shape their careers in…

  6. Upwellings in Lake Baikal

    NASA Astrophysics Data System (ADS)

    Shimaraev, M. N.; Troitskaya, E. S.; Blinov, V. V.; Ivanov, V. G.; Gnatovskii, R. Yu.

    2012-02-01

    Based on shipboard and satellite observations, the characteristics of upwelling in Lake Baikal in the period of direct temperature stratification have been determined for the first time. Coastal upwellings appear annually under the effect of run-down and alongshore winds and are traced along the coast to a distance of up to 60-100 km and up to 250 km in North Baikal. Analogous to the way it occurs in seas, water rises from the depths of 100-200 m (350 m as a maximum) at the velocity of 0.1 × 10-2-6.5 × 10-2 cm/s. Divergence in the field of intràbasin cyclonic macrovortices produces upwelling in the Baikal pelagic zone and downwelling in the vicinity of shores; this lasts from 7 to 88 days and covers the depth interval of 80-300 m in August and up to 400-800 m in early-mid November. The area of upwellings occupies up to 20-60% of the separate basins of the lake. Vertical circulation of water in the field of pelagic upwellings leads to intensification of coastal currents and to formation of the thermobar with a heat inert zone in the central part of the lake in November, and this thermobar is not observed in other lakes, at that.

  7. LAKE TAHOE VISIBILITY STUDY

    EPA Science Inventory

    Visibility monitoring and airborne particulate sampling in the Lake Tahoe Basin were used to document visual air quality levels and to assess the relative impacts of major contributing emission source categories. Visibility data were obtained by long path contrast and particle sc...

  8. Lake Ontario: Nearshore Variability

    EPA Science Inventory

    We conducted a high-resolution survey with towed electronic instrumentation along the Lake Ontario nearshore (720 km) at a 20 meter contour. The survey was conducted September 6-10, 2008 with a shorter 300 km survey conducted August 14-15 for comparing of temporal variability. ...

  9. Lake Michigan: Nearshore Variability

    EPA Science Inventory

    We conducted a high-resolution survey in the nearshore of Lake Michigan at a 20 meter contour using towed electronic instrumentation. The nearly 1200 km survey was conducted Sep 8-15, 2010. We also conducted six cross-contour tows. Along the survey tracks we sampled fixed stat...

  10. Lead and Lags of Lake System Responses to Late Allerød and Early Younger Dryas Climatic Fluctuation - an Example from Varved Lake Sediments from Northern Poland (Central Europe)

    NASA Astrophysics Data System (ADS)

    Slowinski, M. M.; Zawiska, I.; Ott, F.; Noryśkiewicz, A. M.; Plessen, B.; Apolinarska, K.; Lutyńska, M.; Michczynska, D. J.; Wulf, S.; Skubała, P.; Błaszkiewicz, M.; Brauer, A.

    2014-12-01

    The transition from the warmer Allerød to the cooler Younger Dryas period is well understood to represent sudden and extreme climate changes during the end of the last glaciation. Thus, lake sediment studies within paleoclimatic and paleoecological research on this transition are ideal to enhance the knowledge about "lead and lags" of lake system responses to abrupt climate changes through applying multi-proxy sediment analyses. In this study, we present the results of high-resolution studies on varved late glacial sediments from the Trzechowskie paleolake, located in the northern Poland (center Europe). High-resolution bio-proxies (pollen, macrofossils, Cladocera and diatoms), geochemical analyses (µ-XRF data, TOC, C/N ratios, δ18Ocarb and δ13Corg stable isotopes) and a robust chronology based on varve counting, AMS 14C dating and tephrochronology were used to reconstruct the lake system responses to rapid climatic and environmental changes of Trzechowskie paleolake during the late Allerød - Younger Dryas transition. Paleoecological and geochemical analyses, which were carried out in a 4 to 16 years temporal sample resolution, allowed to defining short-termed shifts of the ecosystem that were triggered by abrupt climate changes. The rapid and pronounced cooling at the beginning of the Younger Dryas had a major impact on the lake and its catchment as clearly reflected by not synchronous changes of both, biotic and geochemical proxies. The results of high-resolution analysis indicate (a) an increased precipitation during the Allerød-YD transition, which is responsible for an increase of soil erosion in the catchment during this period, (b) a delayed response of the vegetation compared to the lake depositional system at the YD onset of 20 years, and (c) a non-synchronicity of vegetation responses between Western (Lake Meerfelder Maar) and Eastern European sites (Trzechowskie palaeolake) at the YD onset. This study is a contribution to the Virtual Institute

  11. Lake level variability in Silver Lake, Michigan: a response to fluctuations in lake levels of Lake Michigan

    USGS Publications Warehouse

    Fisher, Timothy G.; Loope, Walter L.

    2004-01-01

    Sediment from Silver Lake, Michigan, can be used to constrain the timing and elevation of Lake Michigan during the Nipissing transgression. Silver Lake is separated from Lake Michigan by a barrier/dune complex and the Nipissing, Calumet, and Glenwood shorelines of Lake Michigan are expressed landward of this barrier. Two Vibracores were taken from the lake in February 2000 and contain pebbly sand, sand, buried soils, marl, peat, and sandy muck. It is suggested here that fluctuations in the level of Lake Michigan are reflected in Silver Lake since the Chippewa low phase, and possibly at the end of the Algonquin phase. An age of 12,490 B.P. (10,460±50 14C yrs B.P.) on wood from a buried Entisol may record the falling Algonquin phase as the North Bay outlet opened. A local perched water table is indicated by marl deposited before 7,800 B.P. and peat between 7,760-7,000 B.P. when Lake Michigan was at the low elevation Chippewa phase. Continued deepening of the lake is recorded by the transition from peat to sandy muck at 7,000 B.P. in the deeper core, and with the drowning of an Inceptisol nearly 3 m higher at 6,410 B.P. in the shallower core. A rising groundwater table responding to a rising Lake Michigan base level during the Nipissing transgression, rather than a response to mid-Holocene climate change, explains deepening of Silver Lake. Sandy muck was deposited continually in Silver Lake between Nipissing and modern time. Sand lenses within the muck are presumed to be eolian in origin, derived from sand dunes advancing into the lake on the western side of the basin.

  12. Temperate Lakes Discovered on Titan

    NASA Astrophysics Data System (ADS)

    Vixie, Graham; Barnes, Jason W.; Jackson, Brian; Wilson, Paul

    2012-04-01

    We have discovered two temperate lakes on Titan using Cassini's Visual and Infrared Mapping Spectrometer (VIMS). Three key features help to identify these surface features as lakes: morphology, albedo, and specular reflection. The presence of lakes at the mid-latitudes mean liquid can accumulate and remain stable outside of the poles. We first identify a lake surface by looking for possible shorelines with a lacustrine morphology. Then, we apply a simple atmospheric correction that produces an approximate surface albedo. Next, we prepare cylindrical projection maps of the brightness of the sky as seen from any points on the surface to identify specular reflections. Our techniques can then be applied to other areas, such as Arrakis Planitia, to test for liquid. Currently, all the known lakes on Titan are concentrated at the poles. Lakes have been suggested in the tropic zone by Griffith et al. Our discovery of non-transient, temperate lakes has important implications for Titan's hydrologic cycle. Clouds have been recorded accumulating in the mid-latitudes and areas have been darkened by rainfall but later brightened after evaporation (Turtle et al. 2011). Stable temperate lakes would affect total rainfall, liquid accumulation, evaporation rates, and infiltration. Polaznik Macula (Figure 1) is a great candidate for lake filling, evaporation rates, and stability. References: Griffith, C., et al.: "Evidence for Lakes on Titan's Tropical Surface". AAS/Division for Planetary Sciences Meeting Abstracts #42, Vol. 42, pp. 1077, 2010. Turtle, E. P., et al.: "Rapid and Extensive Surface Changes Near Titan's Equator: Evidence of April Showers". Science, Vol. 331, pp. 1414-, 2011. Figure 1: Polaznik Macula is the large, dark area central to the figure. The encircled dark blue areas represent positively identified lake regions in the T66 flyby. The light blue areas represent lake candidates still under analysis. The green circle marks a non-lake surface feature enclosed by a

  13. 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

  14. Lake trout rehabilitation in Lake Erie: a case history

    USGS Publications Warehouse

    Cornelius, Floyd C.; Muth, Kenneth M.; Kenyon, Roger

    1995-01-01

    Native lake trout (Salvelinus namaycush) once thrived in the deep waters of eastern Lake Erie. The impact of nearly 70 years of unregulated exploitation and over 100 years of progressively severe cultural eutrophication resulted in the elimination of lake trout stocks by 1950. Early attempts to restore lake trout by stocking were unsuccessful in establishing a self-sustaining population. In the early 1980s, New York's Department of Environmental Conservation, Pennsylvania's Fish and Boat Commission, and the U.S. Fish and Wildlife Service entered into a cooperative program to rehabilitate lake trout in the eastern basin of Lake Erie. After 11 years of stocking selected strains of lake trout in U.S. waters, followed by effective sea lamprey control, lake trout appear to be successfully recolonizing their native habitat. Adult stocks have built up significantly and are expanding their range in the lake. Preliminary investigations suggest that lake trout reproductive habitat is still adequate for natural reproduction, but natural recruitment has not been documented. Future assessments will be directed toward evaluation of spawning success and tracking age-class cohorts as they move through the fishery.

  15. Gold deposition by sulfidation of ferrous Fe in the lacustrine sediments of the Pueblo Viejo district (Dominican Republic): The effect of Fe-C-S diagenesis on later hydrothermal mineralization in a Maar-Diatreme complex

    USGS Publications Warehouse

    Kettler, R.M.; Rye, R.O.; Kesler, S.E.; Meyers, P.A.; Polanco, J.; Russell, N.

    1992-01-01

    The Pueblo Viejo district, located in the Cordillera Central of the Dominican Republic, contains large Au-Ag deposits associated with acid-sulfate alteration within spilites, conglomerates and carbonaceous sedimentary rocks that were deposited in a maar-diatreme complex. Much of the Au mineralization occurs in pyritic, carbonaceous siltstones of the Pueblo Viejo Maar-Diatreme Member of the Cretaceous Los Ranchos Formation. Pyrite is the only Fe-bearing phase in mineralized rock, whereas siderite is the dominant Fe-bearing phase in siltstones distal to mineralization. Disseminated pyrite occurs as framboids, cubes, pyritohedra, concretions and cement. Early framboids occur throughout the district. Au occurs as inclusions in later non-framboid disseminated pyrite (NFDP); an occurrence that is interpreted to be indicative of contemporaneous deposition. Pyrite framboids exhibit a wide range of ??34Scdt-values (-17.5 to +4.8???) and are interpreted to have formed during biogenic reduction of pore-water sulfate. The NFDP yield restricted ??34Scdt-values ( x ?? = -5.2???, s = ??2.4???, n = 43) similar to those obtained from later vein pyrite ( x ?? = -6.4???, s = ??1.5???, n = 12). Alunite and barite have ??34S-values ranging from +18.8 to +21.6???. The interpretation that the NFDP, vein pyrite, alunite and barite, and possibly even the framboidal pyrite share a common source of igneous sulfur is supported by the ??34S data. Siderite occurs as concretions and cement, contains abundant Mg (Fe0.75Mg0.19Mn0.03Ca0.02CO3) and has ??13Cpdb- and ??18Osmow-values ranging from -2.5 to +1.1%. and +14.6 to +19.5???, respectively. These data are consistent with the interpretation that the siderite formed in lacustrine sediments and that the carbonate in the siderite is probably methanogenic, although contributions from oxidation of organic matter during biogenic sulfate reduction, thermal decarboxylation of organic matter, or magmatic vapor cannot be ruled out. Disseminated Au

  16. Potential strategies for recovery of lake whitefish and lake herring stocks in eastern Lake Erie

    USGS Publications Warehouse

    Oldenburg, K.; Stapanian, M.A.; Ryan, P.A.; Holm, E.

    2007-01-01

    Lake Erie sustained large populations of ciscoes (Salmonidae: Coregoninae) 120 years ago. By the end of the 19th century, abundance of lake whitefish (Coregonus clupeaformis) had declined drastically. By 1925, the lake herring (a cisco) population (Coregonus artedii) had collapsed, although a limited lake herring fishery persisted in the eastern basin until the 1950s. In the latter part of the 20th century, the composition of the fish community changed as oligotrophication proceeded. Since 1984, a limited recovery of lake whitefish has occurred, however no recovery was evident for lake herring. Current ecological conditions in Lake Erie probably will not inhibit recovery of the coregonine species. Recovery of walleye (Sander vitreus) and efforts to rehabilitate the native lake trout (Salvelinus namaycush) in Lake Erie will probably assist recovery because these piscivores reduce populations of alewife (Alosa psuedoharengus) and rainbow smelt (Osmerus mordax), which inhibit reproductive success of coregonines. Although there are considerable spawning substrates available to coregonine species in eastern Lake Erie, eggs and fry would probably be displaced by storm surge from most shoals. Site selection for stocking or seeding of eggs should consider the reproductive life cycle of the stocked fish and suitable protection from storm events. Two potential sites in the eastern basin have been identified. Recommended management procedures, including commercial fisheries, are suggested to assist in recovery. Stocking in the eastern basin of Lake Erie is recommended for both species, as conditions are adequate and the native spawning population in the eastern basin is low. For lake herring, consideration should be given to match ecophenotypes as much as possible. Egg seeding is recommended. Egg seeding of lake whitefish should be considered initially, with fingerling or yearling stocking suggested if unsuccessful. Spawning stocks of whitefish in the western basin of Lake

  17. Predicting Maximum Lake Depth from Surrounding Topography

    EPA Science Inventory

    Lake volume aids understanding of the physical and ecological dynamics of lakes, yet is often not readily available. The data needed to calculate lake volume (i.e. bathymetry) are usually only collected on a lake by lake basis and are difficult to obtain across broad regions. ...

  18. Lake Mead--clear and vital

    USGS Publications Warehouse

    Wessells, Stephen M.; Rosen, Michael

    2013-01-01

    Lake Mead – Clear and Vital” is a 13 minute documentary relating the crucial role of science in maintaining high water quality in Lake Mead. The program was produced coincident with release of the Lakes Mead and Mohave Circular a USGS publication covering past and on-going research in the lakes and tributaries of the Lake Mead National Recreation Area.

  19. Lake Erie...Take a Bow.

    ERIC Educational Resources Information Center

    Canning, Maureen; Dunlevy, Margie

    This elementary school teaching unit was developed as a part of a series of teaching units that deal with Lake Erie. This unit was developed to enable children to: (1) identify the Great Lakes and pick out Lake Erie on a map; (2) demonstrate knowledge of Lake Erie's origin and geography; (3) list some uses of Lake Erie; and (4) give examples of…

  20. Fecundity of hatchery lake trout in Lake Ontario

    USGS Publications Warehouse

    Fitzsimons, John D.; O'Gorman, Robert

    1996-01-01

    Fecundity (egg number) was determined from 26 stocked (617-800 mm, total length) lake trout (Salvelinus namaycush) collected in western Lake Ontario during September 1992. Previous to this study, fecundity was evaluated only once in Lake Ontario using native stocks in 1927. The following relationships between fecundity and total length (TL) and weight (W) were obtained. Fecundity = -12,492 + 25.87 TL(mm) and Fecundity = -1,010 + 1,307 W(kg). Relative fecundity (number of eggs per kg of body weight) was unrelated to body weight and averaged 1,592 eggs kg-1. Fecundity of contemporary lake trout based on length was significantly lower than that of historic native stocks, but was similar to contemporary stocked lake trout in Lake Superior.

  1. Lake Garda, Italy

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This ASTER image was acquired on July 29, 2000 and covers an area of 30 by 57 km in northern Italy. Lake Garda was formed by glaciers during the last Ice Age, and is Italy's largest lake. Lago di Garda lies in the provinces of Verona, Brescia, and Trento, and is 51 kilometers (32 miles) long and from 3 to 18 kilometers (2 to 11 miles) wide. The Sarca is its chief affluent, and the lake is drained southward by the Mincio, which discharges into the Po River. Many villas are situated on its shores. On the peninsula of Sirmione, at the southern end of the lake, are the ruins of a Roman villa and a castle of the Scaligers, an Italian family of the 16th century. The RIGHT image has the land area masked out, and a harsh stretch was applied to the lake values to display variations in sediment load. Also visible are hundreds of boats and their wakes, criss-crossing the lake.

    The image is centered at 45.6 degrees north latitude, 10.6 degrees east longitude.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (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 International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for

  2. Future volcanic lake research: revealing secrets from poorly studied lakes

    NASA Astrophysics Data System (ADS)

    Rouwet, D.; Tassi, F.; Mora-Amador, R. A.

    2012-04-01

    Volcanic lake research boosted after the 1986 Lake Nyos lethal gas burst, a limnic rather than volcanic event. This led to the formation of the IAVCEI-Commission on Volcanic Lakes, which grew out into a multi-disciplinary scientific community since the 1990's. At Lake Nyos, a degassing pipe is functional since 2001, and two additional pipes were added in 2011, aimed to prevent further limnic eruption events. There are between 150 and 200 volcanic lakes on Earth. Some acidic crater lakes topping active magmatic-hydrothermal systems are monitored continuously or discontinuously. Such detailed studies have shown their usefulness in volcanic surveillance (e.g. Ruapehu, Yugama-Kusatsu-Shiran, Poás). Others are "Nyos-type" lakes, with possible gas accumulation in bottom waters and thus potentially hazardous. "Nyos-type" lakes tend to remain stably stratified in tropical and sub-tropical climates (meromictic), leading to long-term gas build-up and thus higher potential risk. In temperate climates, such lakes tend to turn over in winter (monomictic), and thus liberating its gas charge yearly. We line out research strategies for the different types of lakes. We believe a complementary, multi-disciplinary approach (geochemistry, geophysics, limnology, biology, statistics, etc.) will lead to new insights and ideas, which can be the base for future following-up and monitoring. After 25 years of pioneering studies on rather few lakes, the scientific community should be challenged to study the many poorly studied volcanic lakes, in order to better constrain the related hazard, based on probabilistic approaches.

  3. Genetic diversity of Diporeia in the Great Lakes: comparison of Lake Superior to the other Great Lakes

    EPA Science Inventory

    Abundances of Diporeia have dropped drastically in the Great Lakes, except in Lake Superior, where data suggest that population counts actually have risen. Various ecological, environmental, or geographic hypotheses have been proposed to explain the greater abundance of Lake Supe...

  4. Aeolian sand preserved in Silver Lake: a new signal of Holocene high stands of Lake Michigan

    USGS Publications Warehouse

    Fisher, Timothy G.; Loope, Walter L.

    2005-01-01

    Aeolian sand within lake sediment from Silver Lake, Michigan can be used as a proxy for the timing of high lake levels of Lake Michigan.We demonstrate that the sand record from Silver Lake plotted as percent weight is in-phase with the elevation curve of Lake Michigan since the mid-Holocene Nipissing Phase. Because fluctuations in Lake Michigan's lake level are recorded in beach ridges, and are a response to climate change, the aeolian sand record within Silver Lake is also a proxy for climate change. It appears that increases in dune activity and lake sand are controlled by similar climatic shifts that drive fluctuations in lake level of Lake Michigan. High lake levels destabilize coastal bluffs that drive dune sand instability, and along with greater wintertime storminess, increase niveo-aeolian transport of sand across lake ice. The sand is introduced into the lake each spring as the ice cover melts.

  5. Life history of lake herring in Lake Superior

    USGS Publications Warehouse

    Dryer, William R.; Beil, Joseph

    1964-01-01

    The average annual commercial catch of lake herring (Coregonus artedi) in U.S. waters of Lake Superior was nearly 12 million pounds in 1929-61. This production contributed 62.4 percent of the total U.S. take of lake herring for the Great Lakes. About 90 percent of the annual catch is taken from small-mesh gill nets during the November-December spawning season. The life-history studies were based on 12,187 fish collected in 1950-62; past growth was computed for 3,779 specimens collected from commercial landings at: Duluth, Minn.; Bayfield, Wis.; and Portage Entry and Marquette, Mich.

  6. Hydrology of Lake County, Florida

    USGS Publications Warehouse

    Knochenmus, Darwin D.; Hughes, G.H.

    1976-01-01

    Lake County includes a 1,150 square-mile area consisting of ridges, uplands, and valleys in central-peninsular Florida. About 32 percent of the county is covered by lakes, swamps, and marshes. Water requirements in 1970 averaged about 54 million gallons per day. About 85 percent of the water was obtained from wells; about 15 percent from lakes. The Floridan aquifer supplies almost all the ground water used in Lake County. Annual recharge to the Floridan aquifer averages about 7 inches over the county; runoff average 8.5 inches. The quality of ground and surface water in Lake County is in general good enough for most uses; however, the poor quality of Floridan-aquifer water in the St. John River Valley probably results from the upward movement of saline water along a fault zone. Surface water in Lake County is usually less mineralized than ground water but is more turbid and colored. (Woodard-USGS)

  7. Not so Great Lakes?

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    In 1965, Frank Sinatra won the Grammy Award for his album, "September of My Years;" "Early Bird," the first commercial communications satellite, was launched; and Dr. Martin Luther King, Jr. was arrested in Selma, Alabama, during demonstrations against voter-registration rules.The year 1965 was also the last time water levels in the U.S. Great Lakes were as low as they are now.

  8. Not so Great Lakes?

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    In 1965, Frank Sinatra won the Grammy Award for his album, “September of My Years” “Early Bird,” the first commercial communications satellite, was launched; and Dr. Martin Luther King, Jr. was arrested in Selma, Alabama, during demonstrations against voter-registration rules.The year 1965 was also the last time water levels in the U.S. Great Lakes were as low as they are now.

  9. Archaea in Yellowstone Lake

    PubMed Central

    Kan, Jinjun; Clingenpeel, Scott; Macur, Richard E; Inskeep, William P; Lovalvo, Dave; Varley, John; Gorby, Yuri; McDermott, Timothy R; Nealson, Kenneth

    2011-01-01

    The Yellowstone geothermal complex has yielded foundational discoveries that have significantly enhanced our understanding of the Archaea. This study continues on this theme, examining Yellowstone Lake and its lake floor hydrothermal vents. Significant Archaea novelty and diversity were found associated with two near-surface photic zone environments and two vents that varied in their depth, temperature and geochemical profile. Phylogenetic diversity was assessed using 454-FLX sequencing (∼51 000 pyrosequencing reads; V1 and V2 regions) and Sanger sequencing of 200 near-full-length polymerase chain reaction (PCR) clones. Automated classifiers (Ribosomal Database Project (RDP) and Greengenes) were problematic for the 454-FLX reads (wrong domain or phylum), although BLAST analysis of the 454-FLX reads against the phylogenetically placed full-length Sanger sequenced PCR clones proved reliable. Most of the archaeal diversity was associated with vents, and as expected there were differences between the vents and the near-surface photic zone samples. Thaumarchaeota dominated all samples: vent-associated organisms corresponded to the largely uncharacterized Marine Group I, and in surface waters, ∼69–84% of the 454-FLX reads matched archaeal clones representing organisms that are Nitrosopumilus maritimus-like (96–97% identity). Importance of the lake nitrogen cycling was also suggested by >5% of the alkaline vent phylotypes being closely related to the nitrifier Candidatus Nitrosocaldus yellowstonii. The Euryarchaeota were primarily related to the uncharacterized environmental clones that make up the Deep Sea Euryarchaeal Group or Deep Sea Hydrothermal Vent Group-6. The phylogenetic parallels of Yellowstone Lake archaea to marine microorganisms provide opportunities to examine interesting evolutionary tracks between freshwater and marine lineages. PMID:21544103

  10. Great Lakes Energy Institute

    SciTech Connect

    Alexander, J. Iwan

    2012-11-18

    The vision of the Great Lakes Energy Institute is to enable the transition to advanced, sustainable energy generation, storage, distribution and utilization through coordinated research, development, and education. The Institute will place emphasis on translating leading edge research into next generation energy technology. The Institute’s research thrusts focus on coordinated research in decentralized power generation devices (e.g. fuel cells, wind turbines, solar photovoltaic devices), management of electrical power transmission and distribution, energy storage, and energy efficiency.

  11. 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.

  12. Method for lake restoration

    DOEpatents

    Dawson, Gaynor W.; Mercer, Basil W.

    1979-01-01

    A process for removing pollutants or minerals from lake, river or ocean sediments or from mine tailings is disclosed. Magnetically attractable collection units containing an ion exchange or sorbent media with an affinity for a chosen target substance are distributed in the sediments or tailings. After a period of time has passed sufficient for the particles to bind up the target substances, a magnet drawn through the sediments or across the tailings retrieves the units along with the target substance.

  13. 27 CFR 9.184 - Trinity Lakes.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    .... Provisional Edition 1982. (c) Boundary. The Trinity Lakes viticultural area is located in Trinity County in northern California. The boundary encompasses Trinity Lake and Lewiston Lake, both within the Trinity...

  14. 27 CFR 9.184 - Trinity Lakes.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    .... Provisional Edition 1982. (c) Boundary. The Trinity Lakes viticultural area is located in Trinity County in northern California. The boundary encompasses Trinity Lake and Lewiston Lake, both within the Trinity...

  15. 27 CFR 9.184 - Trinity Lakes.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    .... Provisional Edition 1982. (c) Boundary. The Trinity Lakes viticultural area is located in Trinity County in northern California. The boundary encompasses Trinity Lake and Lewiston Lake, both within the Trinity...

  16. 27 CFR 9.184 - Trinity Lakes.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    .... Provisional Edition 1982. (c) Boundary. The Trinity Lakes viticultural area is located in Trinity County in northern California. The boundary encompasses Trinity Lake and Lewiston Lake, both within the Trinity...

  17. 27 CFR 9.184 - Trinity Lakes.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    .... Provisional Edition 1982. (c) Boundary. The Trinity Lakes viticultural area is located in Trinity County in northern California. The boundary encompasses Trinity Lake and Lewiston Lake, both within the Trinity...

  18. Landsat analysis of lake quality

    NASA Technical Reports Server (NTRS)

    Scarpace, F. L.; Fisher, L. T.; Holmquist, K. W.

    1979-01-01

    The trophic status of a number of inland lakes in Wisconsin has been assessed. The feasibility of using both photographic and digital representations of Landsat imagery was investigated during the lake classification project. The result of the investigation has been a semi-automatic data acquisition and handling system which, in conjunction with an analytical categorization scheme, can be used to classify all the significant lakes in the state.

  19. Crater Lake: blue through time

    USGS Publications Warehouse

    Larson, Gary L.; Buktenica, Mark; Collier, Robert

    2003-01-01

    Blue is the color of constancy, hence the term true blue. The unearthly blueness of Crater Lake reflects its pristine character and gives scientists a focal point for studying human impacts on aquatic environments over long periods of time. Scientists with the U.S. Geological Survey (USGS), National Park Service, and Oregon State University have systematically studied the lake for the last two decades. Long-term monitoring of this lake is a priority of Crater Lake National Park and will continue far into the future.

  20. Progress toward lake trout restoration in Lake Michigan

    USGS Publications Warehouse

    Holey, Mark E.; Rybicki, Ronald W.; Eck, Gary W.; Brown, Edward H., Jr.; Marsden, J. Ellen; Lavis, Dennis S.; Toneys, Michael L.; Trudeau, Tom N.; Horrall, Ross M.

    1995-01-01

    Progress toward lake trout restoration in Lake Michigan is described through 1993. Extinction of the native lake trout fishery by sea lamprey predation, augmented by exploitation and habitat destruction, resulted in an extensive stocking program of hatchery-reared lake trout that began in 1965. Sea lamprey abundance was effectively controlled using selective chemical toxicants. The initial stocking produced a measurable wild year class of lake trout by 1976 in Grand Traverse Bay, but failed to continue probably due to excessive exploitation. The overall lack of successful reproduction lakewide by the late 1970s led to the development and implementation in 1985 of a focused inter-agency lakewide restoration plan by a technical committee created through the Lake Committee structure of the Great Lakes Fishery Commission. Strategies implemented in 1985 by the plan included setting a 40% total mortality goal lakewide, creating two large refuges designed to encompass historically the most productive spawning habitat and protect trout stocked over their home range, evaluating several lake trout strains, and setting stocking priorities throughout the lake. Target levels for stocking in the 1985 Plan have never been reached, and are much less than the estimated lakewide recruitment of yearlings by the native lake trout stocks. Since 1985, over 90% of the available lake trout have been stocked over the best spawning habitat, and colonization of the historically productive offshore reefs has occurred. Concentrations of spawning lake trout large enough for successful reproduction, based on observations of successful hatchery and wild stocks, have developed at specific reefs. Continued lack of recruitment at these specific sites suggests that something other than stotk abundance has limited success. Poor survival of lake trout eggs, assumed to be related to contaminant burden, occurred in the late 1970s and early 1980s, but survival has since increased to equal survival in the

  1. Glacioisostasy and Lake-Level Change at Moosehead Lake, Maine

    USGS Publications Warehouse

    Balco, G.; Belknap, D.F.; Kelley, J.T.

    1998-01-01

    Reconstructions of glacioisostatic rebound based on relative sea level in Maine and adjacent Canada do not agree well with existing geophysical models. In order to understand these discrepancies better, we investigated the lake-level history of 40-km-long Moosehead Lake in northwestern Maine. Glacioisostasy has affected the level of Moosehead Lake since deglaciation ca. 12,500 14C yr B.P. Lowstand features at the southeastern end and an abandoned outlet at the northwestern end of the lake indicate that the lake basin was tilted down to the northwest, toward the retreating ice sheet, by 0.7 m/km at 10,000 14C yr B.P. Water level then rose rapidly in the southeastern end of the lake, and the northwestern outlet was abandoned, indicating rapid relaxation of landscape tilt. Lowstand features at the northwestern end of the lake suggest that the lake basin was tilted to the southeast at ca. 8750 14C yr B.P., possibly as the result of a migrating isostatic forebulge. After 8000 14C yr B.P., water level at the southeastern end was again below present lake level and rose gradually thereafter. We found no evidence suggesting that postglacial climate change significantly affected lake level. The rebound history inferred from lake-level data is consistent with previous interpretations of nearby relative sealevel data, which indicate a significantly steeper and faster-moving ice-proximal depression and ice-distal forebulge than geophysical models predict. ?? 1998 University of Washington.

  2. Lake Charles CCS Project

    SciTech Connect

    Leib, Thomas; Cole, Dan

    2015-06-30

    In late September 2014 development of the Lake Charles Clean Energy (LCCE) Plant was abandoned resulting in termination of Lake Charles Carbon Capture and Sequestration (CCS) Project which was a subset the LCCE Plant. As a result, the project was only funded through Phase 2A (Design) and did not enter Phase 2B (Construction) or Phase 2C (Operations). This report was prepared relying on information prepared and provided by engineering companies which were engaged by Leucadia Energy, LLC to prepare or review Front End Engineering and Design (FEED) for the Lake Charles Clean Energy Project, which includes the Carbon Capture and Sequestration (CCS) Project in Lake Charles, Louisiana. The Lake Charles Carbon Capture and Sequestration (CCS) Project was to be a large-scale industrial CCS project intended to demonstrate advanced technologies that capture and sequester carbon dioxide (CO2) emissions from industrial sources into underground formations. The Scope of work was divided into two discrete sections; 1) Capture and Compression prepared by the Recipient Leucadia Energy, LLC, and 2) Transport and Sequestration prepared by sub-Recipient Denbury Onshore, LLC. Capture and Compression-The Lake Charles CCS Project Final Technical Report describes the systems and equipment that would be necessary to capture CO2 generated in a large industrial gasification process and sequester the CO2 into underground formations. The purpose of each system is defined along with a description of its equipment and operation. Criteria for selection of major equipment are provided and ancillary utilities necessary for safe and reliable operation in compliance with environmental regulations are described. Construction considerations are described including a general arrangement of the CCS process units within the overall gasification project. A cost estimate is provided, delineated by system area with cost breakdown showing equipment, piping and materials

  3. Grand Canyon, Lake Powell, and Lake Mead

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A snowfall in the American West provides contrast to the landscape's muted earth tones and indicates changes in topography and elevation across (clockwise from top left) Nevada, Utah, Colorado, New Mexico, Arizona, and California. In Utah, the southern ranges of the Wasatch Mountains are covered in snow, and the Colorado River etches a dark ribbon across the red rock of the Colorado Plateau. In the center of the image is the reservoir created by the Glen Canyon Dam. To the east are the gray-colored slopes of Navaho Mountain, and to the southeast, dusted with snow is the region called Black Mesa. Southwest of Glen Canyon, the Colorado enters the Grand Canyon, which cuts westward through Arizona. At a deep bend in the river, the higher elevations of the Keibab Plateau have held onto snow. At the end of the Grand Canyon lies another large reservoir, Lake Mead, which is formed by the Hoover Dam. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  4. Holocene lake-level fluctuations of Lake Aricota, Southern Peru

    USGS Publications Warehouse

    Placzek, C.; Quade, Jay; Betancourt, J.L.

    2001-01-01

    Lacustrine deposits exposed around Lake Aricota, Peru (17?? 22???S), a 7.5-km2 lake dammed by debris flows, provide a middle to late Holocene record of lake-level fluctuations. Chronological context for shoreline deposits was obtained from radiocarbon dating of vascular plant remains and other datable material with minimal 14C reservoir effects (<350 yr). Diatomites associated with highstands several meters above the modern lake level indicate wet episodes. Maximum Holocene lake level was attained before 6100 14C yr B.P. and ended ???2700 14C yr B.P. Moderately high lake levels occurred at 1700 and 1300 14C yr B.P. The highstand at Lake Aricota during the middle Holocene is coeval with a major lowstand at Lake Titicaca (16?? S), which is only 130 km to the northeast and shares a similar climatology. Comparisons with other marine and terrestrial records highlight emerging contradictions over the nature of mid-Holocene climate in the central Andes. ?? 2001 University of Washington.

  5. The near extinction of lake trout in Lake Michigan

    USGS Publications Warehouse

    Eschmeyer, Paul H.

    1957-01-01

    Comparisons in 1949 and 1950 of numbers of legal-sized lake trout caught in large-mesh nets with numbers of small fish taken in chub nets showed that both large and small lake trout declined over the same period, and that by these years the decline may have been greater among small than among legal-sized fish.

  6. ARE LAKES GETTING WARMER? REMOTE SENSING OF LARGE LAKE TEMPERATURES

    EPA Science Inventory

    Recent studies (Levitus et al., 2000) suggest a warning of the world ocean over the past 50 years. Freshwater lakes could also be getting warmer but thermal measurements to determine this are lacking. Large lake temperatures are vertically and horizontally heterogeneous and vary ...

  7. Geographical distributions of lake trout strains stocked in Lake Ontario

    USGS Publications Warehouse

    Elrod, Joseph H.; O'Gorman, Robert; Schneider, Clifford P.; Schaner, Ted

    1996-01-01

    Geographical distributions of lake trout (Salvelinus namaycush) stocked at seven locations in U.S. waters and at four locations in Canadian waters of Lake Ontario were determined from fish caught with gill nets in September in 17 areas of U.S. waters and at 10 fixed locations in Canadian waters in 1986-95. For fish of a given strain stocked at a given location, geographical distributions were not different for immature males and immature females or for mature males and mature females. The proportion of total catch at the three locations nearest the stocking location was higher for mature fish than for immature fish in all 24 available comparisons (sexes combined) and was greater for fish stocked as yearlings than for those stocked as fingerlings in all eight comparisons. Mature fish were relatively widely dispersed from stocking locations indicating that their tendency to return to stocking locations for spawning was weak, and there was no appreciable difference in this tendency among strains. Mature lake trout were uniformly distributed among sampling locations, and the strain composition at stocking locations generally reflected the stocking history 5 to 6 years earlier. Few lake trout moved across Lake Ontario between the north and south shores or between the eastern outlet basin and the main lake basin. Limited dispersal from stocking sites supports the concept of stocking different genetic strains in various parts of the lake with the attributes of each strain selected to match environmental conditions in the portion of the lake where it is stocked.

  8. Biology of young lake trout (Salvelinus namaycush) in Lake Michigan

    USGS Publications Warehouse

    Van Oosten, John; Eschmeyer, Paul H.

    1956-01-01

    Experimental fishing with gill nets of 5 mesh sizes (2 3/8 to 3 inches) in Lake Michigan in 1930-32 yielded more than 16,000 young lake trout. Data are presented here on age, growth, length-weight relationship, abundance, geographical and bathymetric distribution, and other details of their biology.

  9. The Lake Ohrid SCOPSCO project

    NASA Astrophysics Data System (ADS)

    Wagner, Bernd; Wilke, Thomas; Krastel, Sebastian; Zanchetta, Giovanni; Sulpizio, Roberto; Leng, Melanie J.; Francke, Alexander; Baumgarten, Henrike; Cvetkoska, Aleksandra; Giacco, Biagio; Lacey, Jack H.; Leicher, Niklas; Levkov, Zlatko; Lindhorst, Katja; Reed, Jane M.; Zhang, Xiaosen; Sadori, Laura; Vogel, Hendrik; Wagner-Cremer, Friederike; Wonik, Thomas

    2015-04-01

    The ICDP SCOPSCO project at Lake Ohrid in Macedonia and Albania was one of the most successful lake drilling campaigns worldwide. Drilling took place from April to June 2013 and yielded more than 2000 m of sediments from four different sites in the lake. The maximum penetration was 569 m below lake floor and the overall recovery at all drill sites was > 95 %. Almost two years after the drilling operation, core opening and processing as well as biological and geological analyses are still ongoing. However, most of the cores from the main drill site, the so-called DEEP site in the centre of the lake, are meanwhile opened and reveal a unique record of lake history. The extraordinary quality of seismic, borehole logging and core data allows us to achieve the major goals of the SCOPSCO project. Seismic data, diatoms and coarse-grained sediments in the basal cores indicate that Lake Ohrid had no marine origin, as it was speculated in the past. The data show that Lake Ohrid established in a highly dynamic pull-apart basin with varying fluvial and shallow water conditions. On top of these basal sediments, borehole logging data, XRF scanning data, carbonate, and the amount of organic matter indicate a complete and high resolution succession of glacial / interglacial cycles and interspersed stadials and interstadials. This allows us to determine the establishment of Lake Ohrid by means of chronostratigraphic tuning to about 1.3 to 1.5 Ma ago. Additional, independent age control is given by paleomagnetic data and by numerous tephra layers, which can be correlated with well-dated proximal tephra deposits in Italy. The uppermost 350 m of the sediment record contain more than 30 tephras, which makes the Lake Ohrid record to the rosetta stone of distal Italian tephra deposits in the Balkan region. The unique sediment record of Lake Ohrid is fundamental to obtain crucial information on the overall goal of the SCOPSCO project, i.e. to clarify why Lake Ohrid has one of highest

  10. Feeding competition between larval lake whitefish and lake herring

    USGS Publications Warehouse

    Savino, Jacqueline F.; Hudson, Patrick L.

    1995-01-01

    The potential for competition for food between larval lake whitefish (Coregonus clupeaformis) and lake herring (C. artedi) 1- to 8-wk of age was explored in a series of 1-h laboratory feeding studies. Feeding started at 2-wk post-hatch. Learning and fish size appear to be more important than prey density at the onset of feeding. Species differed in their feeding behavior and consumption noticeably by 5-wk and substantially by 8-wk. Lake whitefish generally were more aggressive foragers than lake herring, attacking and capturing more prey. At high plankton density at 8-wk, lake herring feeding was depressed in mixed-fish treatments. This difference in competitive food consumption between the two coregonids occurs at a critical life stage, and when combined with other biotic and abiotic factors, may have a significant impact on recruitment.

  11. Forecasting Lake-Effect Snow in the Great Lakes Using NASA Satllite Data

    NASA Technical Reports Server (NTRS)

    Cipullo, Michelle; Molthan, Andrew; Shafer, Jackie; Case, Jonathan; Jedlovec, Gary

    2011-01-01

    This slide presentation reviews the forecast of the lake effect snow in the Great Lakes region using models and infrared estimates of Great Lake Surface Temperatures (GLSTs) from the MModerate Resolution Imaging Spectroradiometer (MODIS) instrument on Terra and Aqua satellites, and other satellite data. This study analyzes Lake Erie and Lake Ontario which produce storm total snowfall ranged from 8-18 inches off of Lake Ontario and 10-12 inches off of Lake Erie for the areas downwind.

  12. An urban lake remediation experiment

    SciTech Connect

    Castelli, S.E.; Gardner, K.H.; Jennings, A.A.

    1998-07-01

    Circumstances provided the opportunity to study a small urban lake as the surrounding municipalities attempted to improve its aesthetic quality by dredging. This manuscript focuses primarily on the sediments in the system: accumulation rates, the expected dynamics of the lake bed drying process, and the influence of the sediments on water quality.

  13. The Great Lakes Food Web.

    ERIC Educational Resources Information Center

    Baker, Marjane L.

    1997-01-01

    Presents a play for students in grades four to nine that incorporates the scientific names, physical characteristics, feeding habits, interactions, and interdependence of the plants and animals that make up the Great Lakes food web to facilitate the learning of this complex system. Includes a Great Lakes food web chart. (AIM)

  14. NATIONAL LAKE ASSESSMENT MONITORING DESIGN

    EPA Science Inventory

    The USEPA designed the National Lake Assessment in 2005-6 with field sampling being completed in 2007. The objective of the assessment is to estimate the ecological condition of lakes and reservoirs nationally. The objective of this paper is to describe the national survey desi...

  15. New England Lakes & Ponds Project

    EPA Science Inventory

    The New England Lakes and Ponds Project provides a consistent and first time comprehensive assessment of the ecological and water quality condition of lakes and ponds across the New England region. The project is being conducted by EPA along with the New England Interstate Water...

  16. PYRAMID LAKE RENEWEABLE ENERGY PLAN

    SciTech Connect

    HIGH DESERT GEOCULTURE, LLC

    2009-06-06

    The Pyramid Lake Renewable Energy Plan covers these areas: energy potential (primarily focusing on geothermal resource potential, but also more generally addressing wind energy potential); renewable energy market potential; transmission system development; geothermal direct use potential; and business structures to accomplish the development objectives of the Pyramid Lake Paiute Tribe.

  17. Planktonic diatoms of Lake Ontario

    USGS Publications Warehouse

    Reinwand, Jerry F.

    1969-01-01

    The major species of diatoms in surface collections from Lake Ontario in September 1964 were Asterionella formosa, Fragilaria crotonensis, and Tabellaris fenestrata. Dominant species in the deep-water samples were Stephanodiscus astraea, S. astraea var. mintula, and F. crotonensis. The diatom flora in surface collections varied among several stations in the eastern end of the lake.

  18. GREAT LAKES CONTAMINATED SEDIMENTS PROGRAM

    EPA Science Inventory

    Contaminated sediments are a significant problem in the Great Lakes basin. Although discharges of toxic substances to the Great Lakes have been reduced in the last 20 years, persistent high concentrations of contaminants in the bottom sediments of rivers and harbors have raised...

  19. Venous lakes of the hands

    SciTech Connect

    Levy, J.M.; Hessel, S.J.; Joseph, R.B.; Bodell, L.S.

    1985-09-01

    Following pharmacologic vasodilation, multiple vascular lakes were observed on angiograms of the hand in 55 patients. Most had no history of vascular anomalies or disease. The authors believe that these lakes are venous structures and that their filling is a physiologic phenomenon.

  20. Stream, Lake, and Reservoir Management.

    PubMed

    Mei, Ying; Chang, Chein-Chi; Dong, Zhanfeng; Wei, Li

    2016-10-01

    This review on stream, lake, and reservoir management covers selected 2015 publications on the focus of the following sections: • Biota • Climate effect • Models • Remediation and restoration • Reservoir operations • Stream, Lake, and Reservoir Management • Water quality. PMID:27620102

  1. Pyramid Lake Renewable Energy Project

    SciTech Connect

    John Jackson

    2008-03-14

    The Pyramid Lake Paiute Tribe is a federally recognized Tribe residing on the Pyramid Lake Reservation in western Nevada. The funding for this project was used to identify blind geothermal systems disconnected from geothermal sacred sites and develop a Tribal energy corporation for evaluating potential economic development for profit.

  2. "Lake Woebegone," Twenty Years Later

    ERIC Educational Resources Information Center

    Cannell, John Jacob

    2006-01-01

    Almost 20 years ago, the author wrote--and then privately published--the two "Lake Woebegone" reports, named after Garrison Keillor's mythical Minnesota town where "all the women are strong, all the men are good-looking, and all the children are above average." The first "Lake Woebegone" report documented that all 50 states were testing above the…

  3. Europa's Great Lakes

    NASA Astrophysics Data System (ADS)

    Schmidt, B. E.; Blankenship, D. D.; Patterson, G. W.; Schenk, P. M.

    2012-04-01

    Unique to the surface of Europa, chaos terrain is diagnostic of the properties and dynamics of its icy shell. While models have suggested that partial melt within a thick shell or melt-through of a thin shell may form chaos, neither model has been able to definitively explain all observations of chaos terrain. However, we present a new model that suggests large melt lenses form within the shell and that water-ice interactions above and within these lenses drive the production of chaos. Our analysis of the geomorphology of Conamara Chaos and Thera Macula, was used to infer and test a four-stage lens-collapse chaos formation model: 1) Thermal plumes of warm, pure ice ascend through the shell melting the impure brittle ice above, producing a lake of briny water and surface down draw due to volume reduction. 2) Surface deflection and driving force from the plume below hydraulically seals the water in place. 3) Extension of the brittle ice lid generates fractures from below, allowing brines to enter and fluidize the ice matrix. 4) As the lens and now brash matrix refreeze, thermal expansion creates domes and raises the chaos feature above the background terrain. This new "lense-collapse" model indicates that chaos features form in the presence of a great deal of liquid water, and that large liquid water bodies exist within 3km of Europa's surface comparable in volume to the North American Great Lakes. The detection of shallow subsurface "lakes" implies that the ice shell is recycling rapidly and that Europa may be currently active. In this presentation, we will explore environments on Europa and their analogs on Earth, from collapsing Antarctic ice shelves to to subglacial volcanos in Iceland. I will present these new analyses, and describe how this new perspective informs the debate about Europa's habitability and future exploration.

  4. Lava Lakes on Io?

    NASA Astrophysics Data System (ADS)

    Lopes, R. M. C.; Kamp, L. W.; Smythe, W. D.; Howell, R.; Mouginis-Mark, P.; Kargel, J. S.; Radebaugh, J.; Turtle, E. P.; Perry, J.; Williams, D. A.; Carlson, R. W.; Doute, S.; Galileo NIMS Team

    2003-05-01

    At least 152 active volcanic centers have been identified on Jupiter's moon Io [Lopes et al., 2003, submitted to Icarus]. Eruptions at these centers include lava flows (``Promethean" type eruptions), explosive ``Pillanian" eruptions [Keszthelyi et al., 2001, JGR 106, 33,025-52] and volcanism confined within patera walls (``Lokian", Lopes et al., 2003). Understanding the Lokian eruption mechanism is particularly important because paterae are the most ubiquitous volcanic constructs on Io's surface [Radebaugh et al. 2001, JGR, 106, 33,005-33,020] and patera volcanism is the most common eruption type on Io. We use observations from Galileo's Near-Infrared Mapping Spectrometer (NIMS) and compare them with images from Galileo's Solid State Imaging system (SSI) to map the distribution of thermal emission at several Ionian paterae. This allows us to examine how thermal emission correlates with visible features, and to investigate how thermal emission varies with time. Galileo's close fly-bys of Io from 1999 to 2001 allowed NIMS to observe the volcanoes at relatively high spatial resolution (1-30 km pixel). At these scales, observations of the several paterae reveal that the greatest thermal emission occurs at the edges. This can be explained as the crust of a lava lake breaking up against the base of the patera (caldera) walls, similar to what has been observed at lava lakes on Earth. Comparison with terrestrial analogs shows that several Ionian active paterae, such as Loki, Tupan, and Emakong, have thermal properties consistent with relatively inactive lava lakes on Earth. We discuss these results and their implications for eruption styles and resurfacing on Io. This work was supported in part by NASA's Planetary Geology and Geophysics Program.

  5. Lake-floor sediment texture and composition of a hydrothermally-active, volcanic lake, Lake Rotomahana

    NASA Astrophysics Data System (ADS)

    Pittari, A.; Muir, S. L.; Hendy, C. H.

    2016-03-01

    Young volcanic lakes undergo a transition from rapid, post-eruptive accumulation of volcaniclastic sediment to slower pelagic settling under stable lake conditions, and may also be influenced by sublacustrine hydrothermal systems. Lake Rotomahana is a young (129 year-old), hydrothermally-active, volcanic lake formed after the 1886 Tarawera eruption, and provides a unique insight into the early evolution of volcanic lake systems. Lake-bottom sediment cores, 20-46 cm in length, were taken along a transect across the lake and characterised with respect to stratigraphy, facies characteristics (i.e., grain size, componentry) and pore water silica concentrations. The sediments generally comprise two widespread facies: (i) a lower facies of light grey to grey, very fine lacustrine silt derived from the unconsolidated pyroclastic deposits that mantled the catchment area immediately after the eruption, which were rapidly reworked and redeposited into the lake basin; and (ii) an upper facies of dark, fine-sandy diatomaceous silt, that settled from the pelagic zone of the physically stable lake. Adjacent to sublacustrine hydrothermal vents, the upper dark facies is absent, and the upper part of the light grey to grey silt is replaced by a third localised facies comprised of hydrothermally altered pale yellow to yellowish brown, laminated silt with surface iron-rich encrustations. Microspheres, which are thought to be composed of amorphous silica, although some may be halloysite, have precipitated from pore water onto sediment grains, and are associated with a decrease in pore water silicon concentration. Lake Rotomahana is an example of a recently-stabilised volcanic lake, with respect to sedimentation, that shows signs of early sediment silicification in the presence of hydrothermal activity.

  6. Choking Lake Winnipeg

    NASA Astrophysics Data System (ADS)

    Byrne, J. M.; Little, L. J.; Dodgson, K. A.; MacDonald, R. J.; Graham, J.

    2009-12-01

    The problems of waterway eutrophication and coastal zone hypoxia are reaching epidemic proportions. Fresh water and coastal marine environments around the world are suffering unprecedented pollution loadings. We are developing an education program to address the dramatic need for public, community and K-12 education about the harsh impacts of elevated nutrient loads on fresh and marine water environments. The Lake Winnipeg watershed is adopted as the poster child of fresh water eutrophication in western North America. The watershed, one of the largest on the continent, is in rapid decline due to pollution, population pressures and water diversion. A concerted education program is needed to change personal and society actions that negatively impact the Winnipeg watershed; and the confluence of the watershed - Lake Winnipeg. But the education program goes beyond Lake Winnipeg. Negative impacts of nutrient loads are adversely affecting environments right to the oceans. Major dead zones that are expanding on our continental shelves due to nutrient overloading threaten to coalesce into extensive regions of marine life die-off. This presentation outlines the documentary education production process under development. We are building a series of Public Service Announcements (PSAs) for national television networks. The PSAs will direct educators, stakeholders and citizens to an associated website with educational video clips detailing the issues of eutrophication and hypoxia. The video clips or webisodes, present interviews with leading scientists. The discussions address the causes of the problems, and presents workable solutions to nutrient overloads from a variety of sources. The webisodes are accompanied by notes and advice to teachers on ways and means to use the webisodes in classrooms. The project is fully funed by a group of Canadian Community Foundations, with the understanding the work wil be available free to educators anywhere in the world. Our education

  7. L-Lake macroinvertebrate community

    SciTech Connect

    Specht, W.L.

    1996-06-01

    To characterize the present benthic macroinvertebrate community of L-Lake, Regions 5 and 7 of the reservoir were sampled in September 1995 at the same locations sampled in 1988 and 1989 during the L-Lake monitoring program. The macroinvertebrate community of 1995 is compared to that of 1988 and 1989. The species composition of L-Lake`s macroinvertebrate community has changed considerably since 1988-1989, due primarily to maturation of the reservoir ecosystem. L-Lake contains a reasonably diverse macroinvertebrate community that is capable of supporting higher trophic levels, including a diverse assemblage of fish species. The L-Lake macroinvertebrate community is similar to those of many other southeastern reservoirs, and there is no indication that the macroinvertebrate community is perturbed by chemical or physical stressors.

  8. New insights into the Glacial to Holocene climatic evolution of Southern Patagonia from lacustrine lipid biomarker isotope records

    NASA Astrophysics Data System (ADS)

    Hockun, K.; Mollenhauer, G.; Sachse, D.; Schefuß, E.

    2015-12-01

    Southern Patagonia is a key region for paleoclimatic reconstructions in the Southern Hemisphere as it is the only landmass located in the Southern Hemisphere westerly wind (SHW) belt. Within the framework of the ICDP drilling campaign PASADO ("Potrok Aike Maar Lake Sediment Archive Drilling Project"), a high resolution sediment record was recovered from Laguna Potrok Aike (LPTA, 51°58´S, 70°23´W). In order to identify the sources of organic matter contributions to the sedimentary archive, we investigated long-chain n-alkanes as tracers for terrestrial and aquatic plants. We analysed n-alkane distributions and their compound-specific hydrogen (δD) and stable carbon (δ13C) isotopic composition in various sample types such as soils, dust, aquatic and terrestrial plants and lake surface sediments. Based on two different model approaches, one using the n-alkane distributions and the other the compound-specific isotope values, we traced the origin of mid- (n-C23) and long- (n-C29) chain n-alkanes into modern lake sediments. Both models yield similar results: around 70% of the n-C23 originates from aquatic plants and more than 80% of the n-C29 is delivered from dust and terrestrial plants to the sediment. These results provide the basis for a robust paleo-environmental reconstruction of the lipid biomarker isotope records from LPTA. Compound-specific δD and δ13C records for the last 55,000 years from the PASADO core are interpreted in the framework of these findings. Here, δD of the n-C23 alkane serves as proxy for lake water isotopic changes driven by the precipitation-evaporation balance, moisture sources and water column stratification. In contrast, we interpret changes in δD of the n-C29 alkane to reflect dust source area changes and therefore, the intensity of the SHW. A 50‰ shift in the δD record of the n-C23 alkane between 10.000 to 8.000 years age indicates a major hydrological change affecting the lake level while isotopic changes in the n-C29 alkane

  9. Testing the sensitivity of stable carbon isotopes of sub-fossil Sphagnum cellulose to past climate variability: a two millennia high resolution stable carbon isotope time series from the peat deposit "Dürres Maar", Germany

    NASA Astrophysics Data System (ADS)

    Moschen, Robert; Kühl, Norbert; Peters, Sabrina; Vos, Heinz; Lücke, Andreas

    2010-05-01

    Peat deposits are terrestrial archives of environmental changes and climate dynamics over time. They are widely distributed and cover a large part of the earth's land surface often within human habitat and, thus, form an excellent basis for evaluating ecosystem and climate dynamics by multiple geochemical and biological methods. Records of the stable carbon composition of cellulose separately extracted from selected Sphagnum plant components (δ13CSphagnum) from the kettle-hole type peat deposit of 'Dürres Maar' are presented. Manually separated Sphagnum stems, branches and the small leaves covering Sphagnum branches were used for cellulose extraction and subsequent isotope measurements, because intra-plant δ13CSphagnum variability between different physical components of individual modern plants has been described (Loader et al. 2007). We observed the same isotopic offset between single plant components of sub-fossil Sphagnum plant components which is statistically highly significant and observable down-core (Moschen et al. 2009). Using the size fraction of 355-630 μm, which almost exclusively consists of single Sphagnum leaves, allows to derive environmental and climate signals based on a plant response to external controls, presumably including temperature and relative humidity. Because down-core changes in the ratio of different plant components in the peat profile seem probable, erroneous interpretations of isotope records are likely if no differentiation into single Sphagnum plant components is possible. A high resolution time series of δ13CSphagnum is presented covering the last two millennia, tracing decadal to sub-decadal past environmental and climate dynamics. The thickness of the water film surrounding the chloroplasts of Sphagnum plants has been suggested as the most important factor influencing δ13CSphagnum. This points to bog surface wetness which is primarily driven by precipitation and evaporation temperature as the major control of δ13

  10. 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

  11. 33 CFR 110.127 - Lake Mohave and Lake Mead, Nevada and Arizona.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lake Mohave and Lake Mead, Nevada... HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Special Anchorage Areas § 110.127 Lake Mohave and Lake Mead, Nevada and Arizona. (a) Willow Beach, Ariz. That portion of Lake Mohave enclosed by the shore...

  12. 33 CFR 110.127 - Lake Mohave and Lake Mead, Nevada and Arizona.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Lake Mohave and Lake Mead, Nevada... HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Special Anchorage Areas § 110.127 Lake Mohave and Lake Mead, Nevada and Arizona. (a) Willow Beach, Ariz. That portion of Lake Mohave enclosed by the shore...

  13. 78 FR 17097 - Safety Zone; Lake Havasu Triathlon; Lake Havasu City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-20

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Lake Havasu Triathlon; Lake Havasu City, AZ... temporary safety zone within the navigable waters of Lake Havasu and the London Bridge Channel for the Lake... Triathlon will consist of 600 participants. The waterside swim course consists of 1500 meters in Lake...

  14. 77 FR 33309 - Safety Zone; Race on the Lake, Onondaga Lake, Syracuse, NY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-06

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Race on the Lake, Onondaga Lake, Syracuse... temporary safety zone on Onondaga Lake, Syracuse, NY. This safety zone is intended to restrict vessels from a portion of Onondaga Lake during the Race on the Lake powerboat races. This temporary safety...

  15. 76 FR 2579 - Safety Zone; Lake Mead Intake Construction, Lake Mead, Boulder City, NV

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-14

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Lake Mead Intake Construction, Lake Mead... establishing a safety zone on the navigable waters of Lake Mead in support of the construction project for Lake... blasting operations for the placement of a water intake pipe in Lake Mead during the first 6 months of...

  16. 75 FR 20920 - Safety Zone; Lake Havasu Grand Prix, Lake Havasu, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-22

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Lake Havasu Grand Prix, Lake Havasu, AZ... temporary safety zone upon the navigable waters of Lake Havasu on the Colorado River in Lake Havasu City, Arizona for the Lake Havasu Grand Prix. This temporary safety zone is necessary to provide for the...

  17. 77 FR 9652 - Proposed CERCLA Administrative Cost Recovery Settlement; Lake Linden Superfund Site in Lake...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-17

    ... AGENCY Proposed CERCLA Administrative Cost Recovery Settlement; Lake Linden Superfund Site in Lake Linden... administrative settlement for recovery of past response costs concerning the Lake Linden Superfund Site in Lake..., Chicago, Illinois, C-14J, 60604, (312) 886-6609. Comments should reference the Lake Linden Superfund...

  18. 75 FR 13232 - Safety Zone; Lake Mead Intake Construction, Lake Mead, Boulder City, NV

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-19

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Lake Mead Intake Construction, Lake Mead... establishing a safety zone on the navigable waters of Lake Mead in support of the construction project for Lake... Pipe from Lake Mead throughout 2010. This safety zone is necessary to ensure non-authorized...

  19. A Compilation of Gas Emission-Rate Data from Volcanoes of Cook Inlet (Spurr, Crater Peak, Redoubt, Iliamna, and Augustine) and Alaska Peninsula (Douglas, Fourpeaked, Griggs, Mageik, Martin, Peulik, Ukinrek Maars, and Veniaminof), Alaska, from 1995-2006

    USGS Publications Warehouse

    Doukas, Michael P.; McGee, Kenneth A.

    2007-01-01

    INTRODUCTION This report presents gas emission rates from data collected during numerous airborne plume-measurement flights at Alaskan volcanoes since 1995. These flights began in about 1990 as means to establish baseline values of volcanic gas emissions during periods of quiescence and to identify anomalous levels of degassing that might signal the beginning of unrest. The primary goal was to make systematic measurements at the major volcanic centers around the Cook Inlet on at least an annual basis, and more frequently during periods of unrest and eruption. A secondary goal was to measure emissions at selected volcanoes on the Alaska Peninsula. While the goals were not necessarily met in all cases due to weather, funding, or the availability of suitable aircraft, a rich dataset of quality measurements is the legacy of this continuing effort. An earlier report (Doukas, 1995) presented data for the period from 1990 through 1994 and the current report provides data through 2006. This report contains all of the available measurements for SO2, CO2, and H2S emission rates in Alaska determined by the U. S. Geological Survey from 1995 through 2006; airborne measurements for H2S began in Alaska in 2001. The results presented here are from Cook Inlet volcanoes at Spurr, Crater Peak, Redoubt, Iliamna, and Augustine and cover periods of unrest at Iliamna (1996) and Spurr (2004-2006) as well as the 2006 eruption of Augustine. Additional sporadic measurements at volcanoes on the Alaska Peninsula (Douglas, Martin, Mageik, Griggs, Veniaminof, Ukinrek Maars, Peulik, and Fourpeaked during its 2006 unrest) are also reported here.

  20. LAKE MICHIGAN MASS BALANCE ATRAZINE DATA

    EPA Science Inventory

    The Lake Michigan Mass Balance Study measured PCBs, mercury, trans-nonachlor, and atrazine in rivers, the atmosphere, sediments, lake water, and the food chain. A mathematical model will predict what effect reducing pollution will have on the lake, and its large fish (lake trout ...

  1. LAKE MICHIGAN MASS BALANCE: MODELING PROCESS

    EPA Science Inventory

    The Lake Michigan Mass Balance Study measured PCBs, mercury, trans-nonachlor, and atrazine in rivers, the atmosphere, sediments, lake water, and the food chain. A mathematical model will predict what effect reducing pollution will have on the lake, and its large fish (lake trout ...

  2. LAKE MICHIGAN MASS BALANCE PCB DATA

    EPA Science Inventory

    The Lake Michigan Mass Balance Study measured PCBs, mercury, trans-nonachlor, and atrazine in rivers, the atmosphere, sediments, lake water, and the food chain. A mathematical model will predict what effect reducing pollution will have on the lake, and its large fish (lake trout ...

  3. 27 CFR 9.127 - Cayuga Lake.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Cayuga Lake. 9.127 Section... Lake. (a) Name. The name of the viticultural area described in this section is “Cayuga Lake.” (b) Approved maps. The appropriate map for determining the boundaries of the Cayuga Lake viticultural area...

  4. 27 CFR 9.99 - Clear Lake.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) Boundaries. The Clear Lake viticultural area is located in southwestern Lake County, California. The... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Clear Lake. 9.99 Section 9... TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.99 Clear Lake....

  5. 27 CFR 9.127 - Cayuga Lake.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Cayuga Lake. 9.127 Section... Lake. (a) Name. The name of the viticultural area described in this section is “Cayuga Lake.” (b) Approved maps. The appropriate map for determining the boundaries of the Cayuga Lake viticultural area...

  6. 27 CFR 9.99 - Clear Lake.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) Boundaries. The Clear Lake viticultural area is located in southwestern Lake County, California. The... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Clear Lake. 9.99 Section 9... TREASURY ALCOHOL AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.99 Clear Lake....

  7. 27 CFR 9.127 - Cayuga Lake.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Cayuga Lake. 9.127 Section... Lake. (a) Name. The name of the viticultural area described in this section is “Cayuga Lake.” (b) Approved maps. The appropriate map for determining the boundaries of the Cayuga Lake viticultural area...

  8. 27 CFR 9.127 - Cayuga Lake.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Cayuga Lake. 9.127 Section... Lake. (a) Name. The name of the viticultural area described in this section is “Cayuga Lake.” (b) Approved maps. The appropriate map for determining the boundaries of the Cayuga Lake viticultural area...

  9. 27 CFR 9.99 - Clear Lake.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) Boundaries. The Clear Lake viticultural area is located in southwestern Lake County, California. The... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Clear Lake. 9.99 Section 9... TREASURY ALCOHOL AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.99 Clear Lake....

  10. 27 CFR 9.127 - Cayuga Lake.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Cayuga Lake. 9.127 Section... Lake. (a) Name. The name of the viticultural area described in this section is “Cayuga Lake.” (b) Approved maps. The appropriate map for determining the boundaries of the Cayuga Lake viticultural area...

  11. 27 CFR 9.99 - Clear Lake.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) Boundaries. The Clear Lake viticultural area is located in southwestern Lake County, California. The... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Clear Lake. 9.99 Section 9... TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.99 Clear Lake....

  12. 27 CFR 9.99 - Clear Lake.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) Boundaries. The Clear Lake viticultural area is located in southwestern Lake County, California. The... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Clear Lake. 9.99 Section 9... TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.99 Clear Lake....

  13. Estimating the volume of Alpine glacial lakes

    NASA Astrophysics Data System (ADS)

    Cook, S. J.; Quincey, D. J.

    2015-09-01

    Supraglacial, moraine-dammed and ice-dammed lakes represent a potential glacial lake outburst flood (GLOF) threat to downstream communities in many mountain regions. This has motivated the development of empirical relationships to predict lake volume given a measurement of lake surface area obtained from satellite imagery. Such relationships are based on the notion that lake depth, area and volume scale predictably. We critically evaluate the performance of these existing empirical relationships by examining a global database of measured glacial lake depths, areas and volumes. Results show that lake area and depth are not always well correlated (r2 = 0.38), and that although lake volume and area are well correlated (r2 = 0.91), there are distinct outliers in the dataset. These outliers represent situations where it may not be appropriate to apply existing empirical relationships to predict lake volume, and include growing supraglacial lakes, glaciers that recede into basins with complex overdeepened morphologies or that have been deepened by intense erosion, and lakes formed where glaciers advance across and block a main trunk valley. We use the compiled dataset to develop a conceptual model of how the volumes of supraglacial ponds and lakes, moraine-dammed lakes and ice-dammed lakes should be expected to evolve with increasing area. Although a large amount of bathymetric data exist for moraine-dammed and ice-dammed lakes, we suggest that further measurements of growing supraglacial ponds and lakes are needed to better understand their development.

  14. 33 CFR 125.08 - Great Lakes.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Great Lakes. 125.08 Section 125... VESSELS § 125.08 Great Lakes. The term Great Lakes as used in the regulations in this subchapter shall include the Great Lakes and their connecting and tributary waters....

  15. EPA Research Strengthens Great Lakes Restoration Initiative

    EPA Science Inventory

    As the largest group of freshwater lakes on Earth, the Great Lakes (Lakes Erie, Huron, Michigan, Ontario and Superior) are a source of economic prosperity, recreation and raw materials. Human activity, however, has resulted in pollution and other stressors. The Great Lakes curren...

  16. 33 CFR 125.08 - Great Lakes.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Great Lakes. 125.08 Section 125... VESSELS § 125.08 Great Lakes. The term Great Lakes as used in the regulations in this subchapter shall include the Great Lakes and their connecting and tributary waters....

  17. TOXAPHENE IN THE GREAT LAKES. (R825246)

    EPA Science Inventory

    This paper presents the most current data for toxaphene in the water, sediments, and biota of the Laurentian Great Lakes of North America. Concentrations in water range from 1.1 ng/L in Lake Superior to 0.17 ng/L in Lake Ontario. Lake Superior has the highest water concentrati...

  18. The Great Lakes' regional climate regimes

    NASA Astrophysics Data System (ADS)

    Sugiyama, Noriyuki

    For the last couple of decades, the Great Lakes have undergone rapid surface warming. In particular, the magnitude of the summer surface-warming trends of the Great Lakes have been much greater than those of surrounding land (Austin and Colman, 2007). Among the Great Lakes, the deepest Lake Superior exhibited the strongest warming trend in its annual, as well as summer surface water temperature. We find that many aspects of this behavior can be explained in terms of the tendency of deep lakes to exhibit multiple regimes characterized, under the same seasonally varying forcing, by the warmer and colder seasonal cycles exhibiting different amounts of wintertime lake-ice cover and corresponding changes in the summertime lake-surface temperatures. In this thesis, we address the problem of the Great Lakes' warming using one-dimensional lake modeling to interpret diverse observations of the recent lake behavior. (Abstract shortened by ProQuest.).

  19. Possible temperate lakes on Titan

    NASA Astrophysics Data System (ADS)

    Vixie, Graham; Barnes, Jason W.; Jackson, Brian; Rodriguez, Sébastien; Le Mouélic, Stéphane; Sotin, Christophe; MacKenzie, Shannon; Wilson, Paul

    2015-09-01

    We analyze southern mid-latitude albedo-dark features on Titan observed by Cassini's Visual and Infrared Mapping Spectrometer (VIMS). In exploring the nature of these features we consider their morphology, albedo, and specular reflectivity. We suggest that they represent candidates for potential temperate lakes. The presence of lakes at the mid-latitudes would indicate that surface liquid can accumulate and remain stable away from Titan's poles. Candidate lakes were identified by looking for possible shorelines with lacustrine morphology. Then, we applied an atmospheric correction that empirically solved for their surface albedo. Finally, we looked for a specular reflection of the sky in the identified candidates. Using this prescription, we find two candidates that remain as potential temperature lakes. If candidate features do represent temperate lakes on Titan, they have implications for formation mechanisms such as clouds and rainfall or, in low elevation areas, percolation and subsurface flow. Clouds were observed near candidate lake locations on the T66 flyby and this latitude band showed many clouds during southern summer. Our techniques can be applied to areas of Titan that lack RADAR coverage to search for mid- and low-latitude lakes in the future.

  20. Rehabilitation of Delavan Lake, Wisconsin

    USGS Publications Warehouse

    Robertson, Dale M.; Goddard, Gerald L.; Helsel, D.R.; MacKinnon, Kevin L.

    2009-01-01

    A comprehensive rehabilitation plan was developed and implemented to shift Delavan Lake, Wisconsin, from a hypereutrophic to a mesotrophic condition. The plan was threefold: (1) reduce external phosphorus (P) loading by applying Best Management Practices in the watershed, enhance an existing wetland, and short-circuit the inflows through the lake, (2) reduce internal P loading by treating the sediments with alum and removing carp, and (3) rehabilitate the fishery by removing carp and bigmouth buffalo and adding piscivores (biomanipulation). The first and second parts of the plan met with only limited success. With only minor reductions in internal and external P loading, P concentrations in the lake returned to near pre-treatment concentrations. The intensive biomanipulation and resulting trophic cascade (increased piscivores, decreased planktivores, increased large zooplankton populations, and reduced phytoplankton populations) eliminated most of the original problems in the lake (blue-green algal blooms and limited water clarity). However, now there is extensive macrophyte growth and abundant filamentous algae. Without significantly reducing the sources of the problems (high P loading) in Delavan Lake, the increased water clarity may not last. With an improved understanding of the individual components of this rehabilitation program, better future management plans can be developed for Delavan Lake and other lakes and reservoirs with similar eutrophication problems.

  1. The Stability of Lava Lakes

    NASA Astrophysics Data System (ADS)

    Witham, F.; Llewellin, E. W.; Woods, A. W.; Gladstone, C.

    2007-12-01

    Lava lakes may exhibit complex cycles of filling and draining on time-scales of hours to weeks. Such activity is recorded at Pu`u `O`o, Hawai`i. Other examples, e.g. Erta Ale in Ethiopia, do not display these draining episodes; instead an 'equilibrium' system is observed in which the lake may persist for years. We present the results of a theoretical and experimental investigation of lava lakes and identify behavioural regimes distinguished by system geometry and gas content. Laboratory analogue modelling shows that even a simple conduit-lake system, driven by a constant gas flux, can display steady-state equilibrium or cyclic behaviour, depending on the rate of gas flux. A theoretical approach to the same system captures this range of behaviour. By testing the stability of an 'equilibrium' lake to small perturbations, we show that the degree of stability is controlled by the ratio of conduit to lake areas, and the gas volume fraction at the top of the conduit. Despite the simplicity of the modelled system, a rich spectrum of behaviour is found. The model predicts that a stable system must drain over time. This implies that lakes which exhibit ongoing degassing for years or decades (e.g. Erta Ale) either must have an exogenous supply of gas bubbles from depth, or an effective conduit convection mechanism must exist.

  2. 33 CFR 162.220 - Hoover Dam, Lake Mead, and Lake Mohave (Colorado River), Ariz.-Nev.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Hoover Dam, Lake Mead, and Lake... REGULATIONS § 162.220 Hoover Dam, Lake Mead, and Lake Mohave (Colorado River), Ariz.-Nev. (a) Lake Mead and Lake Mohave; restricted areas—(1) The areas. That portion of Lake Mead extending 700 feet upstream...

  3. 33 CFR 162.220 - Hoover Dam, Lake Mead, and Lake Mohave (Colorado River), Ariz.-Nev.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Hoover Dam, Lake Mead, and Lake... REGULATIONS § 162.220 Hoover Dam, Lake Mead, and Lake Mohave (Colorado River), Ariz.-Nev. (a) Lake Mead and Lake Mohave; restricted areas—(1) The areas. That portion of Lake Mead extending 700 feet upstream...

  4. Microplastics in Taihu Lake, China.

    PubMed

    Su, Lei; Xue, Yingang; Li, Lingyun; Yang, Dongqi; Kolandhasamy, Prabhu; Li, Daoji; Shi, Huahong

    2016-09-01

    In comparison with marine environments, the occurrence of microplastics in freshwater environments is less understood. In the present study, we investigated microplastic pollution levels during 2015 in Taihu Lake, the third largest Chinese lake located in one of the most developed areas of China. The abundance of microplastics reached 0.01 × 10(6)-6.8 × 10(6) items/km(2) in plankton net samples, 3.4-25.8 items/L in surface water, 11.0-234.6 items/kg dw in sediments and 0.2-12.5 items/g ww in Asian clams (Corbicula fluminea). The average abundance of microplastics was the highest in plankton net samples from the southeast area of the lake and in the sediments from the northwest area of the lake. The northwest area of the lake was the most heavily contaminated area of the lake, as indicated by chlorophyll-α and total phosphorus. The microplastics were dominated by fiber, 100-1000 μm in size and cellophane in composition. To our best knowledge, the microplastic levels measured in plankton net samples collected from Taihu Lake were the highest found in freshwater lakes worldwide. The ratio of the microplastics in clams to each sediment sample ranged from 38 to 3810 and was negatively correlated to the microplastic level in sediments. In brief, our results strongly suggest that high levels of microplastics occurred not only in water but also in organisms in Taihu Lake. PMID:27381875

  5. Mid-Wisconsin to Holocene permafrost and landscape dynamics based on a drained lake basin core from the northern Seward Peninsula, northwest Alaska

    USGS Publications Warehouse

    Lenz, Josefine; Grosse, Guido; Jones, Benjamin M.; Anthony, Katey M. Walter; Bobrov, Anatoly; Wulf, Sabine; Wetterich, Sebastian

    2016-01-01

    Permafrost-related processes drive regional landscape dynamics in the Arctic terrestrial system. A better understanding of past periods indicative of permafrost degradation and aggradation is important for predicting the future response of Arctic landscapes to climate change. Here, we used a multi-proxy approach to analyse a ~ 4 m long sediment core from a drained thermokarst lake basin on the northern Seward Peninsula in western Arctic Alaska (USA). Sedimentological, biogeochemical, geochronological, micropalaeontological (ostracoda, testate amoebae) and tephra analyses were used to determine the long-term environmental Early-Wisconsin to Holocene history preserved in our core for central Beringia. Yedoma accumulation dominated throughout the Early to Late-Wisconsin but was interrupted by wetland formation from 44.5 to 41.5 ka BP. The latter was terminated by the deposition of 1 m of volcanic tephra, most likely originating from the South Killeak Maar eruption at about 42 ka BP. Yedoma deposition continued until 22.5 ka BP and was followed by a depositional hiatus in the sediment core between 22.5 and 0.23 ka BP. We interpret this hiatus as due to intense thermokarst activity in the areas surrounding the site, which served as a sediment source during the Late-Wisconsin to Holocene climate transition. The lake forming the modern basin on the upland initiated around 0.23 ka BP and drained catastrophically in spring 2005. The present study emphasises that Arctic lake systems and periglacial landscapes are highly dynamic and that permafrost formation as well as degradation in central Beringia was controlled by regional to global climate patterns as well as by local disturbances.

  6. Tracking the impact of mid- to late Holocene climate change and anthropogenic activities on Lake Holzmaar using an updated Holocene chronology

    NASA Astrophysics Data System (ADS)

    Prasad, Sushma; Baier, Janina

    2014-11-01

    The mid- to late Holocene interval is characterised by a highly variable climate in response to a gradual change in orbital insolation. The seasonal impact of these changes on the Eifel Maar region is not yet well documented largely due to uncertainties about the completeness of this archive ("missing varves" in the well known Lake Holzmaar) and a limited understanding of the factors (e.g. temperature, precipitation) influencing the seasonality archived within the lamination/varves. In this study we approach these challenges from a different perspective. Using detailed microfacies investigations we: (1) demonstrate that the ambiguity about the "missing varves" is related to the climate induced complex biotic and abiotic laminations that led to mis-identification of varves; (2) use a combination of detailed microfacies investigations (varve structure, seasonality of biotic and abiotic signals), lamination quality, varve counts on multiple cores, published and new radiocarbon dates to develop a continuous master chronology based on the Bayesian modelling approach. The dates of major climate, volcanic, and archaeological event(s) determined using our model are in good agreement with the independently determined ages of the same events from other archives, confirming the accuracy of our age model; (3) test the sensitivity of the seasonal proxies to the available data on mid-Holocene changes in temperature and precipitation; (4) demonstrate that the changes in lake eutrophicity are correlative with temperature changes in NW Europe and probably triggered by solar variability; and (5) show that the early Iron Age onset of eutrophication in Lake Holzmaar was climate induced and began several decades before the impact of anthropogenic activity was seen in the form of intensified detrital erosion in the catchment area. Our work has implications for understanding the impact of climate change and anthropogenic activities on limnological systems.

  7. Monitoring Change in Great Salt Lake

    NASA Astrophysics Data System (ADS)

    Naftz, David; Angeroth, Cory; Freeman, Michael; Rowland, Ryan; Carling, Gregory

    2013-08-01

    Great Salt Lake is the largest hypersaline lake in the Western Hemisphere and the fourth largest terminal lake in the world (Figure 1). The open water and adjacent wetlands of the Great Salt Lake ecosystem support millions of migratory waterfowl and shorebirds from throughout the Western Hemisphere [Aldrich and Paul, 2002]. In addition, the area is of important economic value: Brine shrimp (Artemia franciscana) residing in Great Salt Lake support an aquaculture shrimp cyst industry with annual revenues as high as $60 million.

  8. Early eutrophication in the lower great lakes:.

    PubMed

    Schelske, C L; Stoermer, E F; Conley, D J; Robbins, J A; Glover, R M

    1983-10-21

    New Evidence from Biogenic Silica in Sediments New evidence from studies of biogenic silica and diatoms in sediment cores indicates that eutrophication in the lower Great Lakes resulted from nutrient enrichment associated with early settlement and forest clearance. Diatom production peaked from 1820 to 1850 in Lake Ontario, at about 1880 in Lake Erie, but not until 1970 in Lake Michigan. This is the first reported sediment record of the silica-depletion sequence for the Great Lakes. PMID:17734831

  9. Lake trout in the Great Lakes: Basin-wide stock collapse and binational restoration

    USGS Publications Warehouse

    Hansen, Michael J.

    1999-01-01

    The lake trout (Salvelinus namaycush) was important to the human settlement of each of the Great Lakes, and underwent catastrophic collapses in each lake in the nineteenth and twentieth centuries. The timing of lake trout stock collapses were different in each lake, as were the causes of the collapses, and have been the subject of much scientific inquiry and debate. The purpose of this chapter is to summarize and review pertinent information relating historical changes in Great Lakes lake trout stocks, binational efforts to restore those stocks, and progress toward stock restoration. This presentation attempts to generalize patterns across the Great Lakes, rather than to focus within each lake. Lake specific analyses have been used to understand lake specific causes and effects, but there is continuing debate about some of these causes and effects. A basinwide review may suggest mechanisms for observed changes that are not evident by lake specific analysis.

  10. LIMNOLOGICAL COMPARISON OF CULTURALLY EUTROPHIC SHAGAWA LAKE AND ADJACENT OLIGOTROPHIC BURNTSIDE LAKE, MINNESOTA

    EPA Science Inventory

    Limnological characteristics for 1971-1972 of culturally eutrophic Shagawa Lake, Minnesota, were compared to those of the immediately upstream, oligotrophic Burntside Lake to evaluate the effects of domestic waste-water discharge to Shagawa Lake. Typical characteristics of Shagaw...

  11. Predicting Maximum Lake Depth from Surrounding Topography

    PubMed Central

    Hollister, Jeffrey W.; Milstead, W. Bryan; Urrutia, M. Andrea

    2011-01-01

    Information about lake morphometry (e.g., depth, volume, size, etc.) aids understanding of the physical and ecological dynamics of lakes, yet is often not readily available. The data needed to calculate measures of lake morphometry, particularly lake depth, are usually collected on a lake-by-lake basis and are difficult to obtain across broad regions. To span the gap between studies of individual lakes where detailed data exist and regional studies where access to useful data on lake depth is unavailable, we developed a method to predict maximum lake depth from the slope of the topography surrounding a lake. We use the National Elevation Dataset and the National Hydrography Dataset – Plus to estimate the percent slope of surrounding lakes and use this information to predict maximum lake depth. We also use field measured maximum lake depths from the US EPA's National Lakes Assessment to empirically adjust and cross-validate our predictions. We were able to predict maximum depth for ∼28,000 lakes in the Northeastern United States with an average cross-validated RMSE of 5.95 m and 5.09 m and average correlation of 0.82 and 0.69 for Hydrological Unit Code Regions 01 and 02, respectively. The depth predictions and the scripts are openly available as supplements to this manuscript. PMID:21984945

  12. Linking hydro-climate to the sediment archive: a combined monitoring and calibration study from a varved lake in central Turkey

    NASA Astrophysics Data System (ADS)

    Roberts, C. Neil; Dean, Jonathan R.; Eastwood, Warren J.; Jones, Matthew D.; Allcock, Samantha L.; Leng, Melanie J.; Metcalfe, Sarah E.; Woodbridge, Jessie; Yiǧitbaşıoǧlu, Hakan

    2016-04-01

    Hydro-climatic reconstructions from lake sediment proxies require an understanding of modern formation processes and calibration over multiple years. Here we use Nar Gölü, a non-outlet, monomictic maar lake in central Turkey, as a field site for such a natural experiment. Fieldwork since 1997 has included observations and measurements of lake water and sediment trap samples, and automated data logging (Jones et al., 2005; Woodbridge and Roberts, 2010; Dean et al., 2015). We compare these data to isotopic, chemical and biotic proxies preserved in the lake's annually-varved sediments. Nar Gölü underwent a 3 m lake-level fall between 2000 and 2010, and δ18O in both water and carbonates is correlated with this lake-level fall, responding to the change in water balance. Over the same period, sedimentary diatom assemblages responded via changes in habitat availability and mixing regime, while conductivity inferred from diatoms showed a rise in inferred salinity, although with a non-linear response to hydro-climatic forcing. There were also non-linear shifts in carbonate mineralogy and elemental chemistry. Building on the relationship between lake water balance and the sediment isotope record, we calibrated sedimentary δ18O against local meteorological records to derive a P/E drought index for central Anatolia. Application to of this to the longer sediment core isotope record from Nar Gölü (Jones et al. 2006) highlights major drought events over the last 600 years (Yiǧitbaşıoǧlu et al., 2015). Although this lacustrine record offers an archive of annually-dated, decadally-averaged hydro-climatic change, there were also times of non-linear lake response to climate. Robust reconstruction therefore requires understanding of physical processes as well as application of statistical correlations. Dean, J.R., Eastwood, W.J., Roberts, N., Jones, M.D., Yiǧitbaşıoǧlu, H., Allcock, S.L., Woodbridge, J., Metcalfe, S.E. and Leng, M.J. (2015) Tracking the hydro

  13. Characterization of Lake Michigan coastal lakes using zooplankton assemblages

    USGS Publications Warehouse

    Whitman, Richard L.; Nevers, Meredith B.; Goodrich, Maria L.; Murphy, Paul C.; Davis, Bruce M.

    2004-01-01

    Zooplankton assemblages and water quality were examined bi-weekly from 17 April to 19 October 1998 in 11 northeastern Lake Michigan coastal lakes of similar origin but varied in trophic status and limnological condition. All lakes were within or adjacent to Sleeping Bear Dunes National Lakeshore, Michigan. Zooplankton (principally microcrustaceans and rotifers) from triplicate Wisconsin net (80 I?m) vertical tows taken at each lake's deepest location were analyzed. Oxygen-temperature-pH-specific conductivity profiles and surface water quality were concurrently measured. Bray-Curtis similarity analysis showed small variations among sample replicates but large temporal differences. The potential use of zooplankton communities for environmental lake comparisons was evaluated by means of BIOENV (Primer 5.1) and principal component analyses. Zooplankton analyzed at the lowest identified taxonomic level yielded greatest sensitivity to limnological variation. Taxonomic and ecological aggregations of zooplankton data performed comparably, but less well than the finest taxonomic analysis. Secchi depth, chlorophyll a, and sulfate concentrations combined to give the best correlation with patterns of variation in the zooplankton data set. Principal component analysis of these variables revealed trophic status as the most influential major limnological gradient among the study lakes. Overall, zooplankton abundance was an excellent indicator of variation in trophic status.

  14. Lake restoration technology transfer assessment

    SciTech Connect

    Daschbach, M.H.; Roe, E.M.; Sharpe, W.E.

    1982-06-01

    Based upon a review of the eutrophication problem and its impact on lake restoration (LR) programs, treatment of the relatively new problem of acid deposition and its impact on LR activities, consideration of the LR programs of the Environmental Protection Agency and several states, and a review of individual LR technology transfer publications, it is recommended that new LR technology transfer programs be given a low priority until more new information is available on the restoration of acidified lakes. Both primary and secondary users of LR research, technology transfer documents, and public awareness documents were considered in this assessment. Primary users included the general public and recreationists, lakeshore property owners, lake/homeowner associations, lake/sanitary districts, and research and environmental organizations; secondary users included state/county/local officials who administer/manage water-related regulations/activities. 4 tables.

  15. LAKE WATER TEMPERATURE SIMULATION MODEL

    EPA Science Inventory

    Functional relationships to describe surface wind mixing, vertical turbulent diffusion, convective heat transfer, and radiation penetration based on data from lakes in Minnesota have been developed. hese relationships have been introduced by regressing model parameters found eith...

  16. Spatial variation among lakes within landscapes: Ecological organization along lake chains

    USGS Publications Warehouse

    Soranno, Patricia A.; Webster, Katherine E.; Riera, Joan L.; Kratz, Timothy K.; Baron, Jill S.; Bukaveckas, Paul A.; Kling, George; White, David S.; Caine, Nel; Lathrop, Richard C; Leavitt, Peter R.

    1999-01-01

    Although limnologists have long been interested in regional patterns in lake attributes, only recently have they considered lakes connected and organized across the landscape, rather than as spatially independent entities. Here we explore the spatial organization of lake districts through the concept of landscape position, a concept that considers lakes longitudinally along gradients of geomorphology and hydrology. We analyzed long-term chemical and biological data from nine lake chains (lakes in a series connected through surface or groundwater flow) from seven lake districts of diverse hydrologic and geomorphic settings across North America. Spatial patterns in lake variables driven by landscape position were surprisingly common across lake districts and across a wide range of variables. On the other hand, temporal patterns of lake variables, quantified using synchrony, the degree to which pairs of lakes exhibit similar dynamics through time, related to landscape position only for lake chains with lake water residence times that spanned a wide range and were generally long (close to or greater than 1 year). Highest synchrony of lakes within a lake chain occurred when lakes had short water residence times. Our results from both the spatial and temporal analyses suggest that certain features of the landscape position concept are robust enough to span a wide range of seemingly disparate lake types. The strong spatial patterns observed in this analysis, and some unexplained patterns, suggest the need to further study these scales and to continue to view lake ecosystems spatially, longitudinally, and broadly across the landscape.

  17. Lake County renewable energy plan

    SciTech Connect

    Not Available

    1984-10-01

    This report documents the preparation of a renewable energy plan for Lake County, Oregon. It is the County's intention to adopt this plan as a supporting document to its Comprehensive Plan and implementing ordinances. The consideration of renewable energy in its land-use planning program is a statutory requirement for Lake County, and under the provisions of the Pacific Northwest Electric Power Planning and Conservation Act such renewable resource planning also fulfills regional energy objectives on a local level.

  18. Burrowing saves Lake Erie clams

    USGS Publications Warehouse

    Nichols, S. Jerrine; Wilcox, Douglas A.

    1997-01-01

    Freshwater unionid clams in North America have been virtually eliminated from waters that are colonized by zebra mussels. Near total mortality has been reported in western Lake Erie, but we have discovered a large population of native clams in a Lake Erie wetland that shows little sign of infestation. Field observations and laboratory experiments show that warm summer water temperatures and soft, silt-clay sediments trigger burowing by clams. This discourages infestation and physically removes any attached zebra mussels.

  19. Global lake surface water temperatures from ATSR

    NASA Astrophysics Data System (ADS)

    MacCallum, Stuart; Merchant, Christopher J.; Layden, Aisling

    2013-04-01

    The ATSR Reprocessing for Climate - Lake (ARC-Lake) project applies optimal estimation (OE) retrievals and probabilistic cloud screening methods to provide lake surface water temperature (LSWT) estimates from the series of (Advanced) Along-Track Scanning Radiometers. This methodology is generic (i.e. applicable to all lakes) as variations in physical properties such as elevation, salinity, and atmospheric conditions are accounted for through the forward modelling of observed radiances. In the initial phases of ARC-Lake, LSWTs were obtained for 258 of Earth's largest lakes. In the final phase of the project, the dataset is extended by applying the OE methodology to smaller lakes, providing LSWT data from 1991 to 2012 for approximately 1000 lakes. In this presentation we will provide an overview of the ARC-Lake project, its publically available data products and some applications of these products.

  20. Mitigation alternatives for L Lake

    SciTech Connect

    Moore, D.B.

    1988-11-03

    The current condition of L Lake/Steel Creek was summarized in a report to SCDHEC in June 1988 which reported that the L Lake and Steel Creek ecosystems were adequately developing towards balanced biological communities. If mitigation for L Lake inputs, specifically temperature and nutrients, are required, several viable alternatives are available. A report prepared by Spencer in 1986 discusses the various options available for cooling L-Reactor discharges. In effect, a small cooling tower is the only realistic solution to reducing effluent temperatures. Nutrient mitigation can take several approaches including upstream sewage treatment, hypolimnetic withdrawal, dilution of input water by Par Pond water, precipitation of nutrients, and sediment oxidation. None of these systems would influence the thermal regime, but would significantly reduce nutrient input into the system. One beneficial use of L-Lake thermal effluents is algaculture, the production of useful algae. A document prepared in 1988 concludes that algaculture is a technically and economically feasible mitigation alternative for L Lake and could allow L Lake to be handled under Section 318 of the Clean Water Act.

  1. The size-distribution of Earth's lakes.

    PubMed

    Cael, B B; Seekell, D A

    2016-01-01

    Globally, there are millions of small lakes, but a small number of large lakes. Most key ecosystem patterns and processes scale with lake size, thus this asymmetry between area and abundance is a fundamental constraint on broad-scale patterns in lake ecology. Nonetheless, descriptions of lake size-distributions are scarce and empirical distributions are rarely evaluated relative to theoretical predictions. Here we develop expectations for Earth's lake area-distribution based on percolation theory and evaluate these expectations with data from a global lake census. Lake surface areas ≥8.5 km(2) are power-law distributed with a tail exponent (τ = 1.97) and fractal dimension (d = 1.38), similar to theoretical expectations (τ = 2.05; d = 4/3). Lakes <8.5 km(2) are not power-law distributed. An independently developed regional lake census exhibits a similar transition and consistency with theoretical predictions. Small lakes deviate from the power-law distribution because smaller lakes are more susceptible to dynamical change and topographic behavior at sub-kilometer scales is not self-similar. Our results provide a robust characterization and theoretical explanation for the lake size-abundance relationship, and form a fundamental basis for understanding and predicting patterns in lake ecology at broad scales. PMID:27388607

  2. 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

  3. 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

  4. Hydrogeology of the Lake Miona area, northeast Sumter County, Florida

    USGS Publications Warehouse

    Bradner, L.A.

    1986-01-01

    The Lake Miona area, in northeast Sumter County, is characterized by karstic depressions that contain lakes, ponds, and marshes that drain vertically to the upper Floridan aquifer. Lake Miona, Black Lake, and Cherry Lake are the prominent water features of the area. When the lake levels are lowest, the lakes are not connected, but at higher levels, they become connected and water flows eastward from Lake Miona through Black Lake to Cherry Lake. The chemical and biological conditions in the lakes are such that, although they support a large population of submerged aquatic plants, no problem with algae blooms was observed. (USGS)

  5. Lake water quality mapping from LANDSAT

    NASA Technical Reports Server (NTRS)

    Scherz, J. P.

    1977-01-01

    The lakes in three LANDSAT scenes were mapped by the Bendix MDAS multispectral analysis system. Field checking the maps by three separate individuals revealed approximately 90-95% correct classification for the lake categories selected. Variations between observers was about 5%. From the MDAS color coded maps the lake with the worst algae problem was easily located. This lake was closely checked and a pollution source of 100 cows was found in the springs which fed this lake. The theory, lab work and field work which made it possible for this demonstration project to be a practical lake classification procedure are presented.

  6. Lake water quality mapping from Landsat

    NASA Technical Reports Server (NTRS)

    Scherz, J. P.

    1977-01-01

    In the project described remote sensing was used to check the quality of lake waters. The lakes of three Landsat scenes were mapped with the Bendix MDAS multispectral analysis system. From the MDAS color coded maps, the lake with the worst algae problem was easily located. The lake was closely checked, and the presence of 100 cows in the springs which fed the lake could be identified as the pollution source. The laboratory and field work involved in the lake classification project is described.

  7. Investigation of the dramatic changes in lake level of the Bosten Lake in northwestern China

    NASA Astrophysics Data System (ADS)

    Guo, Mengjing; Wu, Wei; Zhou, Xiaode; Chen, Yongmin; Li, Jing

    2015-01-01

    Bosten Lake, located in the arid region of northwest China, is the largest inland freshwater lake in China. Water resources in Bosten Lake are of great importance for the regional drinking water supply, agricultural irrigation, and economic development of Xinjiang province. In this study, the dynamics of the lake level in Bosten Lake were investigated from 1956 to 2010. We found that the lake level experienced three different periods of change due to the combined influences of climate variation and human activities. Generally, the lake level has shown a significant downward trend since the first observation started in 1956 and dropped to its lowest level in 1987. Thereafter, the lake level presented a continuous upward trend and rose to its highest value in 2002. Then, the level decreased dramatically from 2002 to 2010. A water balance model and the climate elasticity method were used to estimate the reasons for the lake level changes of Bosten Lake. The results showed that an increase in lake evaporation led to the continuous decrease in lake level from 1958 to 1987. Then, human-controlled lake outflow and increasing lake inflow together led to the increase in lake level from 1988 to 2002. During 2003 to 2010, the emergency project of transferring water to Tarim River led to the increase in lake outflow, while the lake inflow obviously decreased because of a decrease in precipitation. These factors resulted in a sharp decrease in the lake level from 2003 to 2010. The changes in lake level indicate changes in available water resources from Bosten Lake. This reason for the analysis of the change in lake level in this study is to support the water resources management of Bosten Lake.

  8. Salt Lake City, Utah

    NASA Technical Reports Server (NTRS)

    2001-01-01

    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 simulated natural color image presents a late spring view of north central Utah that includes all of the Olympic sites. The image extends from Ogden in the north, to Provo in the south; and includes the snow-capped Wasatch Mountains and the eastern part of the Great Salt Lake.

    This image was acquired on May 28, 2000 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. 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. ASTER is the only high resolution imaging sensor on Terra. 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.

    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

  9. Lakes in Valles Marineris

    NASA Astrophysics Data System (ADS)

    Lucchitta, Baerbel K.

    2010-10-01

    The paper reviews the evolution of hypotheses of lakes in Valles Marineris through observations made from the time of Mariner and continuing through the Viking, MGS, MO, MEx, and MRO missions. Several pertinent findings from these missions are addressed, including: The morphology and composition of the interior layered deposits (ILD); the question whether ILD are deposited inside the troughs or exhumed from the walls; the possible existence of ancestral basins; the derivation of water; arguments for an origin as aqueous, eolian, or pyroclastic sediments, or sub/ice volcanoes; origin of inclined layers, mounds and moats; and age relations of features within and peripheral to the troughs. A possible scenario begins with the collapse of ice-charged ground into ancestral basins along structural planes of weakness due to Tharsis stresses, about 3.5 Ga ago. The basins rapidly filled with water from ground ice, subterranean aquifers, or nearby valley networks. The water spilled out of the peripheral troughs and flowed across high plateaus into early outflow channels. The ancestral basins then filled with sediments derived from valley networks or from trapped eolian or pyroclastic deposits. Alternatively, volcanoes rose under the water or ice to form tuyas. The water was highly acidic, and sediments may have been deposited directly as evaporites or were later altered to evaporites by the brines or by hydrothermal activity. Percolating fluids produced iron oxide concretions. Similar alteration would have affected the putative volcanoes. Most of the ILD were emplaced early in the troughs' history. Shortly thereafter, more water erupted from the peripheral troughs and formed additional chaos and outflow channels. The ancestral basins were breached by erosion and tectonism, and the through-going Coprates/Ius graben system developed. Major lakes within the Valles Marineris dried up and vigorous wind erosion reduced the friable, evaporite-rich sediments to isolated mounds

  10. 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

  11. Hydrology of Central Florida Lakes - A Primer

    USGS Publications Warehouse

    Schiffer, Donna M.

    1998-01-01

    INTRODUCTION Lakes are among the most valued natural resources of central Florida. The landscape of central Florida is riddled with lakeswhen viewed from the air, it almost seems there is more water than land. Florida has more naturally formed lakes than other southeastern States, where many lakes are created by building dams across streams. The abundance of lakes on the Florida peninsula is a result of the geology and geologic history of the State. An estimated 7,800 lakes in Florida are greater than 1 acre in surface area. Of these, 35 percent are located in just four counties (fig. 1): Lake, Orange, Osceola, and Polk (Hughes, 1974b). Lakes add to the aesthetic and commercial value of the area and are used by many residents and visitors for fishing, boating, swimming, and other types of outdoor recreation. Lakes also are used for other purposes such as irrigation, flood control, water supply, and navigation. Residents and visitors commonly ask questions such as Whyare there so many lakes here?, Why is my lake drying up (or flooding)?, or Is my lake spring-fed? These questions indicate that the basic hydrology of lakes and the interaction of lakes with ground water and surface water are not well understood by the general population. Because of the importance of lakes to residents of central Florida and the many questions and misconceptions about lakes, this primer was prepared by the U.S. Geological Survey (USGS) in cooperation with the St. Johns River Water Management District and the South Florida Water Management District. The USGS has been collecting hydrologic data in central Florida since the 1920s, obtaining valuable information that has been used to better understand the hydrology of the water resources of central Florida, including lakes. In addition to data collection, as of 1994, the USGS had published 66 reports and maps on central Florida lakes (Garcia and Hoy, 1995). The main purpose of this primer is to describe the hydrology of lakes in central

  12. Numerical simulations of Lake Vostok

    NASA Astrophysics Data System (ADS)

    Curchitser, E.; Tremblay, B.

    2003-04-01

    Numerical simulations of Lake Vostok We present a systematic approach towards a realistic hydrodynamic model of lake Vostok. The lake is characterized by the unusual combination of size (permitting significant geostrophic motion) and an overlying ice sheet several kilometers thick. A priori estimates of the circulation in the deep lake predict a mostly geostrophic circulation driven by horizontal temperature gradients produced by the pressure-dependent freezing point at the base of the (non-uniform) ice sheet. Further preliminary (remote) research has revealed the steep topography and the elliptical geometry of the lake. A three dimensional, primitive equation, free surface, model is used as a starting point for the Lake configuration. We show how the surface pressure gradient forces are modified to permit a simulation that includes the hydrostatic effects of the overlying ice sheet. A thermodynamic ice model is coupled with the circulation component to simulate the ice accretion/melting at the base of the ice sheet. A stretching of the terrain following vertical coordinate is used to resolve the boundary layer in the ice/water interface. Furthermore, the terrain-following coordinate evolves in time, and is used to track the evolution of the ice sheet due to ice accretion/melting. Both idealized and realistic ice sheet bottom topographies (from remote radar data) are used to drive the simulations. Steady state and time evolving simulations (i.e., constant and evolving ice sheet geometry) will be descirbed, as well as a comparison to an idealized box model (Tremblay, Clarke, and Hohman). The coastline and lake bathymetry used in the simulation are derived from radar data and are accurately represented in our model.

  13. Eutrophication of the St. Lawrence Great Lakes

    USGS Publications Warehouse

    Beeton, Alfred M.

    1965-01-01

    Lakes Huron, Michigan, and Superior are classified as oligotrophic lakes on the basis of their biological, chemical, and physical characteristics. Lake Ontario, although rich in nutrients, is morphometrically oligotrophic or mesotrophic because of its large area of deep water. Lake Erie, the most productive of the lakes and the shallowest, is eutrophic. Several changes commonly associated with eutrophication in small lakes have been observed in the Great Lakes. These changes apparently reflect accelerated eutrophication in the Great Lakes due to man's activity. Chemical data compiled from a number of sources, dating as early as 1854, indicate a progressive increase in the concentrations of various major ions and total dissolved solids in all of the lakes except Lake Superior. The plankton has changed somewhat in Lake Michigan and the plankton, benthos, and fish populations of Lake Erie are greatly different today from those of the past. An extensive area of hypolimnetic water of Lake Erie has developed low dissolved oxygen concentrations in late summer within recent years.

  14. Lake and reservoir restoration guidance manual: first edition

    SciTech Connect

    Moore, L.; Thornton, K.

    1988-02-01

    This manual provides guidance to lake managers, homeowners, lake associations, and laypersons on lake and reservoir restoration, management and protection. It also provides information on how to identify lake problems, evaluate practices for restoring and protection lakes, watershed management, and creating a lake-management plan.

  15. 1. GENERAL VIEW OF THE LOWER END OF TWIN LAKES ...

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

    1. GENERAL VIEW OF THE LOWER END OF TWIN LAKES SHOWING THE HISTORIC OUTLET WORKS AT THE EDGE OF THE WATER NEAR CENTER OF THE PHOTO WITH THE NEW TWIN LAKES DAM JUST BEHIND. VIEW LOOKING SOUTHEAST. - Twin Lakes Dam & Outlet Works, Beneath Twin Lakes Reservoir, T11S, R80W, S22, Twin Lakes, Lake County, CO

  16. 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.

  17. Exploring trends, causes, and consequences of declining lipids in Lake Superior lake trout

    EPA Science Inventory

    The ability of lake trout to forage in deepwater habitats is facilitated by high lipid content, which affords buoyancy. In Lake Superior, lean lake trout historically occupied depths < 80 m, and siscowet lake trout occupied depths > 80 m. Siscowets have been known f...

  18. What can the National Lake Assessment Tell Us about Ecosystem Service Benefits in Lakes

    EPA Science Inventory

    The condition of lakes, ponds, and reservoirs is often viewed as existing along a continuum from pristine to impacted. The 2007 National Lake Survey was conducted to assess the condition of the nation’s lakes. Over 1,000 lakes were surveyed and detailed physical and chemical da...

  19. Estimate of net trophic transfer efficiency of PCBs to Lake Michigan lake trout from their prey

    USGS Publications Warehouse

    Madenjian, Charles P.; Hesselberg, Robert J.; DeSorcie, Timothy J.; Schmidt, Larry J.; Stedman, Ralph M.; Quintal, Richard T.; Begnoche, Linda J.; Passino-Reader, Dora R.

    1998-01-01

    Most of the polychlorinated biphenyl (PCB) body burden accumulated by lake trout (Salvelinus namaycush) from the Laurentian Great Lakes is from their food. We used diet information, PCB determinations in both lake trout and their prey, and bioenergetics modeling to estimate the efficiency with which Lake Michigan lake trout retain PCBs from their food. Our estimates were the most reliable estimates to date because (a) the lake trout and prey fish sampled during our study were all from the same vicinity of the lake, (b) detailed measurements were made on the PCB concentrations of both lake trout and prey fish over wide ranges in fish size, and (c) lake trout diet was analyzed in detail over a wide range of lake trout size. Our estimates of net trophic transfer efficiency of PCBs to lake trout from their prey averaged from 0.73 to 0.89 for lake trout between the ages of 5 and 10 years old. There was no evidence of an upward or downward trend in our estimates of net trophic transfer efficiency for lake trout between the ages of 5 and 10 years old, and therefore this efficiency appeared to be constant over the duration of the lake trout's adult life in the lake. On the basis of our estimtes, lake trout retained 80% of the PCBs that are contained within their food.

  20. 33 CFR 162.140 - Connecting waters from Lake Huron to Lake Erie; miscellaneous rules.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Connecting waters from Lake Huron to Lake Erie; miscellaneous rules. 162.140 Section 162.140 Navigation and Navigable Waters COAST... NAVIGATION REGULATIONS § 162.140 Connecting waters from Lake Huron to Lake Erie; miscellaneous rules....

  1. 33 CFR 162.130 - Connecting waters from Lake Huron to Lake Erie; general rules.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Connecting waters from Lake Huron to Lake Erie; general rules. 162.130 Section 162.130 Navigation and Navigable Waters COAST GUARD... REGULATIONS § 162.130 Connecting waters from Lake Huron to Lake Erie; general rules. (a) Purpose....

  2. 33 CFR 162.132 - Connecting waters from Lake Huron to Lake Erie; communications rules.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Connecting waters from Lake Huron to Lake Erie; communications rules. 162.132 Section 162.132 Navigation and Navigable Waters COAST... NAVIGATION REGULATIONS § 162.132 Connecting waters from Lake Huron to Lake Erie; communications rules....

  3. 14 CFR 93.69 - Special requirements, Lake Campbell and Sixmile Lake Airports.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Special requirements, Lake Campbell and Sixmile Lake Airports. 93.69 Section 93.69 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... Anchorage, Alaska, Terminal Area § 93.69 Special requirements, Lake Campbell and Sixmile Lake Airports....

  4. 33 CFR 162.134 - Connecting waters from Lake Huron to Lake Erie; traffic rules.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Connecting waters from Lake Huron to Lake Erie; traffic rules. 162.134 Section 162.134 Navigation and Navigable Waters COAST GUARD... REGULATIONS § 162.134 Connecting waters from Lake Huron to Lake Erie; traffic rules. (a) Detroit River....

  5. Energy density of lake whitefish Coregonus clupeaformis in Lakes Huron and Michigan

    USGS Publications Warehouse

    Pothoven, S.A.; Nalepa, T.F.; Madenjian, C.P.; Rediske, R.R.; Schneeberger, P.J.; He, J.X.

    2006-01-01

    We collected lake whitefish Coregonus clupeaformis off Alpena and Tawas City, Michigan, USA in Lake Huron and off Muskegon, Michigan USA in Lake Michigan during 2002–2004. We determined energy density and percent dry weight for lake whitefish from both lakes and lipid content for Lake Michigan fish. Energy density increased with increasing fish weight up to 800 g, and then remained relatively constant with further increases in fish weight. Energy density, adjusted for weight, was lower in Lake Huron than in Lake Michigan for both small (≤800 g) and large fish (>800 g). Energy density did not differ seasonally for small or large lake whitefish or between adult male and female fish. Energy density was strongly correlated with percent dry weight and percent lipid content. Based on data from commercially caught lake whitefish, body condition was lower in Lake Huron than Lake Michigan during 1981–2003, indicating that the dissimilarity in body condition between the lakes could be long standing. Energy density and lipid content in 2002–2004 in Lake Michigan were lower than data for comparable sized fish collected in 1969–1971. Differences in energy density between lakes were attributed to variation in diet and prey energy content as well as factors that affect feeding rates such as lake whitefish density and prey abundance.

  6. 33 CFR 162.130 - Connecting waters from Lake Huron to Lake Erie; general rules.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Connecting waters from Lake Huron to Lake Erie; general rules. 162.130 Section 162.130 Navigation and Navigable Waters COAST GUARD... REGULATIONS § 162.130 Connecting waters from Lake Huron to Lake Erie; general rules. (a) Purpose....

  7. 33 CFR 162.132 - Connecting waters from Lake Huron to Lake Erie; communications rules.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Connecting waters from Lake Huron to Lake Erie; communications rules. 162.132 Section 162.132 Navigation and Navigable Waters COAST... NAVIGATION REGULATIONS § 162.132 Connecting waters from Lake Huron to Lake Erie; communications rules....

  8. 14 CFR 93.69 - Special requirements, Lake Campbell and Sixmile Lake Airports.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Special requirements, Lake Campbell and Sixmile Lake Airports. 93.69 Section 93.69 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... Anchorage, Alaska, Terminal Area § 93.69 Special requirements, Lake Campbell and Sixmile Lake Airports....

  9. 33 CFR 162.140 - Connecting waters from Lake Huron to Lake Erie; miscellaneous rules.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Connecting waters from Lake Huron to Lake Erie; miscellaneous rules. 162.140 Section 162.140 Navigation and Navigable Waters COAST... NAVIGATION REGULATIONS § 162.140 Connecting waters from Lake Huron to Lake Erie; miscellaneous rules....

  10. Competition between larval lake herring (Coregonus artedi) and lake whitefish (Coregonus clupeaformis) for zooplankton

    USGS Publications Warehouse

    Davis, Bruce M.; Todd, Thomas N.

    1998-01-01

    Diet and growth of larval lake herring (Coregonus artedi) and lake whitefish (Coregonus clupeaformis) were compared in mesocosm experiments in a small mesotrophic lake in southeastern Michigan. Fish were sampled from single-species and mixed assemblages in 2-m3 cages for 8 weeks during April and May. Both species initially ate mostly cyclopoid copepodites and small cladocerans (Bosmia spp.). Schoener's index of diet overlap showed considerable overlap (70-90%). Lake whitefish ate Daphnia spp. and adult copepods about 2 weeks earlier than did lake herring, perhaps related to their larger mean mouth gape. Lake whitefish were consistently larger than lake herring until the eighth week, especially in the sympatric treatments. Lake whitefish appeared to have a negative effect on the growth of lake herring, as lake herring in mixed-species treatments were smaller and weighed less than lake herring reared in single-species treatments. The diet similarities of lake whitefish and lake herring larvae could make them competitors for food in the Great Lakes. The greater initial size of lake whitefish could allow them to eat larger prey earlier and thereby limit availability of these prey to lake herring at a crucial period of development.

  11. 33 CFR 110.127 - Lake Mohave and Lake Mead, Nevada and Arizona.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Lake Mohave and Lake Mead, Nevada and Arizona. 110.127 Section 110.127 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Special Anchorage Areas § 110.127 Lake Mohave and Lake Mead, Nevada and Arizona. (a) Willow...

  12. 78 FR 17869 - Safety Zone; Desert Storm Shootout; Lake Havasu, Lake Havasu City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-25

    ... FR Federal Register NPRM Notice of Proposed Rulemaking A. Regulatory History and Information The... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Desert Storm Shootout; Lake Havasu, Lake... establishing a temporary safety zone on the navigable waters of the Colorado River in Lake Havasu, Lake...

  13. Glacial-Lake Outburst Erosion of the Grand Valley, Michigan, and Impacts on Glacial Lakes in the Lake Michigan Basin

    NASA Astrophysics Data System (ADS)

    Kehew, Alan E.

    1993-01-01

    Geomorphic and sedimentologic evidence in the Grand Valley, which drained the retreating Saginaw Lobe of the Laurentide Ice Sheet and later acted as a spillway between lakes in the Huron and Erie basins and in the Michigan basin, suggests that at least one drainage event from glacial Lake Saginaw to glacial Lake Chicago was a catastrophic outburst that deeply incised the valley. Analysis of shoreline and outlet geomorphology at the Chicago outlet supports J H Bretz's hypothesis of episodic incision and lake-level change. Shoreline features of each lake level converge to separate outlet sills that decrease in elevation from the oldest to youngest lake phases. This evidence, coupled with the presence of boulder lags and other features consistent with outburst origin, suggests that the outlets were deepened by catastrophic outbursts at least twice. The first incision event is correlated with a linked series of floods that progressed from Huron and Erie basin lakes to glacial Lake Saginaw to glacial Lake Chicago and then to the Mississippi. The second downcutting event occurred after the Two Rivers Advance of the Lake Michigan Lobe. Outbursts from the eastern outlets of glacial Lake Agassiz to glacial Lake Algonquin are a possible cause for this period of downcutting at the Chicago outlets.

  14. Episodic acidification of Adirondack lakes during snowmelt

    SciTech Connect

    Schaefer, D.A.; Driscoll, C.T.; Van Dreason, R.; Yatsko, C.P.

    1990-07-01

    Maximum values of acid neutralizing capacity (ANC) in Adirondack, New York lake outlets generally occur during summer and autumn. During spring snowmelt, transport of acidic water through acid-sensitive watersheds causes depression of upper lake water ANC. In some systems lake outlet ANC reaches negative values. The authors examined outlet water chemistry from II Adirondack lakes during 1986 and 1987 snowmelts. In these lakes, SO concentrations were diluted during snowmelt and did not depress ANC. For lakes with high baseline ANC values, springtime ANC depressions were primarily accompanied by basic cation dilution. For lakes with low baseline ANC, No increases dominated ANC depressions. Lakes with intermediate baseline ANC were affected by both processes and exhibited larger ANC depressions. Ammonium dilution only affected wetland systems. A model predicting a linear relationship between outlet water ANC minima and autumn ANC was inappropriate. To assess watershed response to episodic acidification, hydrologic flow paths must be considered. (Copyright (c) 1990 by the American Geophysical Union.)

  15. 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

  16. Neoichnology at lake margins: Implications for paleo-lake systems

    NASA Astrophysics Data System (ADS)

    Hamer, Jessica M. M.; Sheldon, Nathan D.

    2010-07-01

    Neoichnological studies provide significant information that can aid in the interpretation of ancient ichnological assemblages. Here we examine, for the first time, the pattern in both vertebrate and invertebrate trace distribution and abundance that can be seen in two geographically separate, but broadly analogous, contemporary semi-arid climate lake margin settings in an effort to describe taphonomic processes relevant to paleo-lake systems. Lake margin to supralittoral zone transects were made at Ruby Reservoir, Montana (USA) and La Sotonera, Spain and vegetation cover, trace cover %, trace diversity, and substrate characteristics were recorded. Similar patterns in trace distribution were seen through the eulittoral to supralittoral zones, with the majority of traces identified within a single transect present at both sites. However, a few traces attributed to larger organisms were found to be unique to each and in some instances, could to be assigned to a specific trace maker. The eulittoral zone was considered to have characteristics attributable to the Scoyenia ichnofacies, however, analysis of the supralittoral zone shows some characteristics of both the Coprinisphaera and the Mermia ichnofacies. In addition, a transitional zone between a Scoyenia-like ichnofacies and a fully terrestrial assemblage was found, which may enable continental ichnofacies to be further refined for application to paleo-lake systems. Study of the distribution of traces with distance along the transects also suggests taphonomic biases against the preservation of certain types of traces (e.g., avian) due to seasonal fluctuations of the lake level and the subsequent reduced preservation potential for lake-proximal traces.

  17. Lake evaporation estimates in tropical Africa (Lake Ziway, Ethiopia)

    NASA Astrophysics Data System (ADS)

    Vallet-Coulomb, Christine; Legesse, Dagnachew; Gasse, Françoise; Travi, Yves; Chernet, Tesfaye

    2001-05-01

    Estimates of evaporation from an open shallow lake in tropical Africa (Lake Ziway, Main Ethiopian Rift) are made by using monthly hydrometeorological data available for the past three decades. On the one hand, annual average estimates are inferred from three climatic approaches, which can be applied in areas with limited meteorological data. The lake energy balance yields an evaporation rate of 1780 mm yr -1, assuming a Bowen ratio of 0.15 (that of Lake Victoria). The Penman method gives an annual evaporation rate of 1870 mm. The complementary relationship lake evaporation model (CRLE) applied on monthly averaged values of air temperature, air humidity and sunshine duration gives 1730 mm yr -1. The sensitivity of each method to changes in input variables is analyzed in order to test the stability of the resulting estimates. This helps discuss uncertainties and possible inter-annual variations of the evaporation rate. On the other hand, the monthly lake level records together with precipitation and river discharge data between 1969 and 1990, allow us to estimate the water balance, providing an annual rate of 1937 mm for the combined evaporation and groundwater losses. The chloride budget is used to discriminate the groundwater from the evaporation loss. It gives us an annual evaporation rate of 1740 mm and a corresponding groundwater loss of 200 mm yr -1. The groundwater loss estimate is of the same order of magnitude as the surface outflow, but the associated error in the former is significant because the result is sensitive to the poorly known chloride content of river inflows. Our results can be used to forecast the impact of increased water consumption in the basin.

  18. Periodic floods from glacial Lake Missoula into the Sanpoil arm of glacial Lake Columbia, northeastern Washington

    NASA Astrophysics Data System (ADS)

    Atwater, Brian F.

    1984-08-01

    At least 15 floods ascended the Sanpoil arm of glacial Lake Columbia during a single glaciation. Varves between 14 of the flood beds indicate one backflooding every 35 to 55 yr. This regularity suggests that the floods came from an ice-dammed lake that was self-dumping. Probably the self-dumping lake was glacial Lake Missoula, Montana, because the floods accord with inferred emptyings of that lake in frequency and number, apparently entered Lake Columbia from the east, and produced beds resembling backflood deposits of Lake Missoula floods in southern Washington.

  19. Estimating the volume of Alpine glacial lakes

    NASA Astrophysics Data System (ADS)

    Cook, S. J.; Quincey, D. J.

    2015-12-01

    Supraglacial, moraine-dammed and ice-dammed lakes represent a potential glacial lake outburst flood (GLOF) threat to downstream communities in many mountain regions. This has motivated the development of empirical relationships to predict lake volume given a measurement of lake surface area obtained from satellite imagery. Such relationships are based on the notion that lake depth, area and volume scale predictably. We critically evaluate the performance of these existing empirical relationships by examining a global database of glacial lake depths, areas and volumes. Results show that lake area and depth are not always well correlated (r2 = 0.38) and that although lake volume and area are well correlated (r2 = 0.91), and indeed are auto-correlated, there are distinct outliers in the data set. These outliers represent situations where it may not be appropriate to apply existing empirical relationships to predict lake volume and include growing supraglacial lakes, glaciers that recede into basins with complex overdeepened morphologies or that have been deepened by intense erosion and lakes formed where glaciers advance across and block a main trunk valley. We use the compiled data set to develop a conceptual model of how the volumes of supraglacial ponds and lakes, moraine-dammed lakes and ice-dammed lakes should be expected to evolve with increasing area. Although a large amount of bathymetric data exist for moraine-dammed and ice-dammed lakes, we suggest that further measurements of growing supraglacial ponds and lakes are needed to better understand their development.

  20. Bathythermal habitat use by strains of Great Lakes- and Finger Lakes-origin lake trout in Lake Huron after a change in prey fish abundance and composition

    USGS Publications Warehouse

    Bergstedt, Roger A.; Argyle, Ray L.; Krueger, Charles C.; Taylor, William W.

    2012-01-01

    A study conducted in Lake Huron during October 1998–June 2001 found that strains of Great Lakes-origin (GLO) lake trout Salvelinus namaycush occupied significantly higher temperatures than did Finger Lakes-origin (FLO; New York) lake trout based on data from archival (or data storage) telemetry tags that recorded only temperature. During 2002 and 2003, we implanted archival tags that recorded depth as well as temperature in GLO and FLO lake trout in Lake Huron. Data subsequently recorded by those tags spanned 2002–2005. Based on those data, we examined whether temperatures and depths occupied by GLO and FLO lake trout differed during 2002–2005. Temperatures occupied during those years were also compared with occupied temperatures reported for 1998–2001, before a substantial decline in prey fish biomass. Temperatures occupied by GLO lake trout were again significantly higher than those occupied by FLO lake trout. This result supports the conclusion of the previous study. The GLO lake trout also occupied significantly shallower depths than FLO lake trout. In 2002–2005, both GLO and FLO lake trout occupied significantly lower temperatures than they did in 1998–2001. Aside from the sharp decline in prey fish biomass between study periods, the formerly abundant pelagic alewife Alosa pseudoharengus virtually disappeared and the demersal round goby Neogobius melanostomus invaded the lake and became locally abundant. The lower temperatures occupied by lake trout in Lake Huron during 2002–2005 may be attributable to changes in the composition of the prey fish community, food scarcity (i.e., a retreat to cooler water could increase conversion efficiency), or both.

  1. Monitoring change in Great Salt Lake

    USGS Publications Warehouse

    Naftz, David L.; Angeroth, Cory E.; Freeman, Michael L.; Rowland, Ryan C.; Carling, Gregory

    2013-01-01

    Despite the ecological and economic importance of Great Salt Lake, only limited water quality monitoring has occurred historically. To change this, new monitoring stations and networks—gauges of lake level height and rate of inflow, moored buoys, and multiple lake-bottom sensors—will provide important information that can be used to make informed decisions regarding future management of the Great Salt Lake ecosystem.

  2. Teshekpuk Lake, Alaska

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This ASTER image of Teshekpuk Lake on Alaska's North Slope, within the National Petroleum Reserve, was acquired on August 15, 2000. It covers an area of 58.7 x 89.9 km, and is centered near 70.4 degrees north latitude, 153 degrees west longitude.

    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 images Earth 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 provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of 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.

    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.

    Size: 58.7 by 89.9 kilometers (36.4 by 55.7 miles) Location: 70.4 degrees North latitude, 153 degrees West longitude Orientation: North at top Image Data: ASTER Bands 3, 2, and 1 Original Data Resolution: ASTER 30 meters (98.4 feet) Dates Acquired: August 15, 2000

  3. Ancient lakes on Mars?

    NASA Technical Reports Server (NTRS)

    Goldspiel, J. M.; Squyres, S. W.

    1989-01-01

    The valley systems in Mars' ancient cratered terrain provide strong evidence for a warmer and wetter climate very early in planetary history. The valley systems in some instances debouch into closed depressions that could have acted as local ponding basins for the flow. A survey of the Martian equatorial region shows that numerous local depressions at the confluence of valley systems exist. These depressions (approximately 100 km) typically are characterized by many valleys flowing into them and few or none flowing out. If ponding did take place, these basin would have contained lakes for some period during Mars' early warmer epoch. Although the collection basins are numerous, location of ones that have not suffered significant subsequent geologic modification is difficult. Some morphologic features suggest that volcanic lavas may have filled them subsequent to any early fluvial activity. Two detailed maps of valley systems and local ponding basins in USGC 1:2,000,000 subquadrangles were completed and a third is in progress. The completed regions are in Mare Tyrrhenum (MC-22 SW) and Margarifter Sinus (MC-19 SE), and the region in progress is in Iapygia (MC-21 NW). On the maps, the valley systems and interpreted margins of ponding basins are indicated. The depressions are of interest for two reasons. First, the depressions were surely the sites in which the materials eroded from the valleys were deposited. Such sediments could preserve important information about the physical conditions at the time of deposition. Second, the sediments could preserve evidence of water-atmosphere interactions during the early period of the Martian climate. Atmospheric carbon dioxide would dissolve in water, and solid carbonate minerals would tend to precipitate out to form carbonate sedimentary deposits. Formation of carbonates in this manner might account for some of the CO2 lost from the early more dense atmosphere.

  4. First evidence of successful natural reproduction by planted lake trout in Lake Huron

    USGS Publications Warehouse

    Nester, Robert T.; Poe, Thomas P.

    1984-01-01

    Twenty-two lake trout (Salvelinus namaycush) swim-up fry, 24-27 mm long, were captured with emergent fry traps and a tow net in northwestern Lake Huron on a small nearshore reef off Alpena, Michigan, between May 10 and June 1, 1982. These catches represent the first evidence of successful production of swim-up fry by planted, hatchery-reared lake trout in Lake Huron since the lake trout rehabilitation program began in 1973.

  5. EPISODIC ACIDIFICATION OF ADIRONDACK LAKES DURING SNOWMELT

    EPA Science Inventory

    Maximum values of acid neutralizing capacity (ANC) in Adirondack, New York lake outlets generally occur during summer and autumn. During spring snowmelt, transport of acidic water through acid-sensitive watersheds causes depression of upper lake water ANC. n some systems lake out...

  6. 27 CFR 9.177 - Alexandria Lakes.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... and Lake Darling at benchmark (BM) 1366, which is an unmarked bridge on County Road 11, known as the... road known as County Road 62; then (5) North along County Road 62 on to the Lake Miltona, East, Minn...; then (10) South along County Road 34 until the point where County Road 34 runs parallel to Lake...

  7. 27 CFR 9.128 - Seneca Lake.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Cross Road, which changes to Cretsley Road, to its intersection with Mud Lake Road (County Road 23) on... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Seneca Lake. 9.128 Section... Lake. (a) Name. The name of the viticultural area described in this section is “Seneca Lake”....

  8. 27 CFR 9.146 - Lake Wisconsin.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ..., Columbia County, where Spring Creek enters Lake Wisconsin; (2) From the point of beginning, follow the... Bay, Sauk County, where the Wisconsin River becomes Lake Wisconsin again on the map; (4) Then... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Lake Wisconsin....

  9. 27 CFR 9.177 - Alexandria Lakes.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... and Lake Darling at benchmark (BM) 1366, which is an unmarked bridge on County Road 11, known as the... road known as County Road 62; then (5) North along County Road 62 on to the Lake Miltona, East, Minn...; then (10) South along County Road 34 until the point where County Road 34 runs parallel to Lake...

  10. 27 CFR 9.177 - Alexandria Lakes.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... and Lake Darling at benchmark (BM) 1366, which is an unmarked bridge on County Road 11, known as the... road known as County Road 62; then (5) North along County Road 62 on to the Lake Miltona, East, Minn...; then (10) South along County Road 34 until the point where County Road 34 runs parallel to Lake...

  11. 27 CFR 9.128 - Seneca Lake.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Cross Road, which changes to Cretsley Road, to its intersection with Mud Lake Road (County Road 23) on... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Seneca Lake. 9.128 Section... Lake. (a) Name. The name of the viticultural area described in this section is “Seneca Lake”....

  12. 27 CFR 9.128 - Seneca Lake.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Cross Road, which changes to Cretsley Road, to its intersection with Mud Lake Road (County Road 23) on... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Seneca Lake. 9.128 Section... Lake. (a) Name. The name of the viticultural area described in this section is “Seneca Lake”....

  13. 27 CFR 9.146 - Lake Wisconsin.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., Columbia County, where Spring Creek enters Lake Wisconsin; (2) From the point of beginning, follow the... Bay, Sauk County, where the Wisconsin River becomes Lake Wisconsin again on the map; (4) Then... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Lake Wisconsin....

  14. 27 CFR 9.177 - Alexandria Lakes.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... and Lake Darling at benchmark (BM) 1366, which is an unmarked bridge on County Road 11, known as the... road known as County Road 62; then (5) North along County Road 62 on to the Lake Miltona, East, Minn...; then (10) South along County Road 34 until the point where County Road 34 runs parallel to Lake...

  15. 27 CFR 9.128 - Seneca Lake.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Cross Road, which changes to Cretsley Road, to its intersection with Mud Lake Road (County Road 23) on... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Seneca Lake. 9.128 Section... Lake. (a) Name. The name of the viticultural area described in this section is “Seneca Lake”....

  16. 27 CFR 9.177 - Alexandria Lakes.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... and Lake Darling at benchmark (BM) 1366, which is an unmarked bridge on County Road 11, known as the... road known as County Road 62; then (5) North along County Road 62 on to the Lake Miltona, East, Minn...; then (10) South along County Road 34 until the point where County Road 34 runs parallel to Lake...

  17. 27 CFR 9.146 - Lake Wisconsin.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., Columbia County, where Spring Creek enters Lake Wisconsin; (2) From the point of beginning, follow the... Bay, Sauk County, where the Wisconsin River becomes Lake Wisconsin again on the map; (4) Then... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Lake Wisconsin....

  18. 27 CFR 9.146 - Lake Wisconsin.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ..., Columbia County, where Spring Creek enters Lake Wisconsin; (2) From the point of beginning, follow the... Bay, Sauk County, where the Wisconsin River becomes Lake Wisconsin again on the map; (4) Then... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Lake Wisconsin....

  19. 27 CFR 9.146 - Lake Wisconsin.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., Columbia County, where Spring Creek enters Lake Wisconsin; (2) From the point of beginning, follow the... Bay, Sauk County, where the Wisconsin River becomes Lake Wisconsin again on the map; (4) Then... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Lake Wisconsin....

  20. 27 CFR 9.128 - Seneca Lake.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Cross Road, which changes to Cretsley Road, to its intersection with Mud Lake Road (County Road 23) on... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Seneca Lake. 9.128 Section... Lake. (a) Name. The name of the viticultural area described in this section is “Seneca Lake”....

  1. Hydrology of Lake Butler, Orange County, Florida

    USGS Publications Warehouse

    Smoot, James L.; Schiffer, Donna M.

    1984-01-01

    Lake Butler is one of the lakes that collectively make up the Butler chain of lakes in the headwaters of the Kissimmee River, Florida. The bottom configuration of the lake is typical of relict karst features formed during lower stages in sea level. The top of the Floridan aquifer is 50 to 100 feet below the land surface. The drainage area of Lake Butler is approximately 14.5 sq mi and is comprised of sub-basins of other lakes in the vicinity. Surface outflow from Lake Butler is generally southward to Cypress Creek, a tributary of the Kissimmee River. The extremes in lake stage for the period 1933-81 are 94.67 ft on June 23, 1981 and 101.78 ft on September 13, 1960. The median lake stage for this period was 99.28 ft above sea level. The quality of water in Lake Butler is excellent, based on studies of physical, chemical, and biological conditions by the Orange County Pollution Control Department. The lake water is slightly acidic and soft (48 mg/L hardness as calcium carbonate). Pesticides in water were below detection levels at two sites sampled in the lake, but were detected in the bottom sediments. (USGS)

  2. 27 CFR 9.83 - Lake Erie.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Lake Erie. 9.83 Section 9... TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.83 Lake Erie. (a) Name. The name of the viticultural area described in this section is “Lake Erie.” (b) Approved...

  3. 33 CFR 117.797 - Lake Champlain.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lake Champlain. 117.797 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New York § 117.797 Lake Champlain. (a) The drawspan... United States. (b) The draw of the US2 Bridge, mile 91.8, over Lake Champlain, between South Hero...

  4. 33 CFR 117.993 - Lake Champlain.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lake Champlain. 117.993 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Vermont § 117.993 Lake Champlain. (a) The drawspan for... vessels of the United States. (b) The draw of the US2 Bridge, mile 91.8, over Lake Champlain,...

  5. 36 CFR 13.1208 - Lake Camp.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Lake Camp. 13.1208 Section 13... § 13.1208 Lake Camp. Leaving a boat, trailer, or vehicle unattended for more than 72 hours at the facilities associated with the Lake Camp launching ramp is prohibited without authorization from...

  6. Great Lakes Education Booklet, 1990-1991.

    ERIC Educational Resources Information Center

    Michigan State Dept. of Natural Resources, Lansing.

    This booklet integrates science, history, and environmental education to help students acquire a basic understanding of the importance of the Great Lakes located in the United States. The packet also contains a Great Lakes Basin resource map and a sand dune poster. These materials introduce students to a brief history of the lakes, the diversity…

  7. A reactive nitrogen budget for Lake Michigan

    EPA Science Inventory

    The reactive nitrogen budget for Lake Michigan was reviewed and updated, making use of recent estimates of watershed and atmospheric nitrogen loads. The updated total N load to Lake Michigan was approximately double the previous estimate from the Lake Michigan Mass Balance study ...

  8. 36 CFR 13.1208 - Lake Camp.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Lake Camp. 13.1208 Section 13... § 13.1208 Lake Camp. Leaving a boat, trailer, or vehicle unattended for more than 72 hours at the facilities associated with the Lake Camp launching ramp is prohibited without authorization from...

  9. 33 CFR 117.993 - Lake Champlain.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Lake Champlain. 117.993 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Vermont § 117.993 Lake Champlain. (a) The drawspan for... vessels of the United States. (b) The draw of the US2 Bridge, mile 91.8, over Lake Champlain,...

  10. 27 CFR 9.83 - Lake Erie.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Lake Erie. 9.83 Section 9... TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.83 Lake Erie. (a) Name. The name of the viticultural area described in this section is “Lake Erie.” (b) Approved...

  11. Lake Okeechobee seepage monitoring network

    USGS Publications Warehouse

    McKenzie, Donald J.

    1973-01-01

    This report summarizes the data collected at the five original monitoring sites along the south shore of Lake Okeechobee from January 29, 1970 to June 28, 1972. In order to use the hydrographs in this report to full advantage, they should be studied in conjunction with Meyer's graphs and text (1971). During steady-state conditions, water seeps from the lake through the filtercake and through the aquifers beneath the dike. At those sites where the filtercake is missing, or has about the same permeability as the aquifers, the seepage from the lake is about equivalent to the flow through the aquifers. Present data are insufficient to determine whether or not filtercake buildup has reduced seepage. No appreciable change in drainage occurred during the observed period.

  12. Lake sensitivity to acid rain

    SciTech Connect

    Shurkin, J.; Goldstein, R.

    1985-06-01

    Research in the Adirondacks suggests that watershed dynamics are the key to a lake's vulnerability to acidification. The Electric Power Research Institute's Integrated Lake-Watershed Acidification Study (ILWAS) produced a computer model that successfully integrated the physical and chemical factors that determine these dynamics. The research required an unprecedented level of awareness of how watersheds work and how rain, soil, forests, and rocks interact. One outcome of the field and laboratory studies was the finding that some soils act as buffers, taking certain ions out of the water, while some added ions. While the ability of the watershed as a whole to neutralize acid is the main determinant of a lake's vulnerability, seasonal changes demonstrate that time is a factor. The model is in demand to test water in other locations and to explore buffering agents. 2 figures.

  13. Lake Volume Monitoring from Space

    NASA Astrophysics Data System (ADS)

    Crétaux, J.-F.; Abarca-del-Río, R.; Bergé-Nguyen, M.; Arsen, A.; Drolon, V.; Clos, G.; Maisongrande, P.

    2016-03-01

    Lakes are integrators of environmental change occurring at both the regional and global scale. They present a wide range of behavior on a variety of timescales (cyclic and secular) depending on their morphology and climate conditions. Lakes play a crucial role in retaining and stocking water, and because of the significant global environmental changes occurring at several anthropocentric levels, the necessity to monitor all morphodynamic characteristics [e.g., water level, surface (water contour) and volume] has increased substantially. Satellite altimetry and imagery are now widely used together to calculate lake and reservoir water storage changes worldwide. However, strategies and algorithms to calculate these characteristics are not straightforward, and specific approaches need to be developed. We present a review of some of these methodologies by using lakes over the Tibetan Plateau to illustrate some critical aspects and issues (technical and scientific) linked to the observation of climate change impact on surface waters from remote sensing data. Many authors have measured water variation using the limited remote sensing measurements available over short time periods, even though the time series are probably too short to directly link these results with climate change. Indeed, there are many processes and factors, like the influence of lake morphology, that are beyond observation and are still uncertain. The time response for lakes to reach a new state of equilibrium is a key aspect that is often neglected in current literature. Observations over a long period of time, including maintaining a constellation of comprehensive and complementary satellite missions with service continuity over decades, are therefore necessary especially when the ground gauge network is too limited. In addition, the design of future satellite missions with new instrumental concepts (e.g., SAR, SARin, Ka band altimetry, Ka interferometry) will also be suitable for complete

  14. The High-Lakes Project

    NASA Astrophysics Data System (ADS)

    Cabrol, Nathalie A.; Grin, Edmond A.; Chong, Guillermo; Minkley, Edwin; Hock, Andrew N.; Yu, Youngseob; Bebout, Leslie; Fleming, Erich; Häder, Donat P.; Demergasso, Cecilia; Gibson, John; Escudero, Lorena; Dorador, Cristina; Lim, Darlene; Woosley, Clayton; Morris, Robert L.; Tambley, Cristian; Gaete, Victor; Galvez, Matthieu E.; Smith, Eric; Uskin-Peate, Ingrid; Salazar, Carlos; Dawidowicz, G.; Majerowicz, J.

    2009-06-01

    The High Lakes Project is a multidisciplinary astrobiological investigation studying high-altitude lakes between 4200 m and 6000 m elevation in the Central Andes of Bolivia and Chile. Its primary objective is to understand the impact of increased environmental stress on the modification of lake habitability potential during rapid climate change as an analogy to early Mars. Their unique geophysical environment and mostly uncharted ecosystems have added new objectives to the project, including the assessment of the impact of low-ozone/high solar irradiance in nonpolar aquatic environments, the documentation of poorly known ecosystems, and the quantification of the impact of climate change on lake environment and ecosystem. Data from 2003 to 2007 show that UV flux is 165% that of sea level with maximum averaged UVB reaching 4 W/m2. Short UV wavelengths (260-270 nm) were recorded and peaked at 14.6 mW/m2. High solar irradiance occurs in an atmosphere permanently depleted in ozone falling below ozone hole definition for 33-36 days and between 30 and 35% depletion the rest of the year. The impact of strong UVB and UV erythemally weighted daily dose on life is compounded by broad daily temperature variations with sudden and sharp fluctuations. Lake habitat chemistry is highly dynamical with notable changes in yearly ion concentrations and pH resulting from low and variable yearly precipitation. The year-round combination of environmental variables define these lakes as end-members. In such an environment, they host ecosystems that include a significant fraction of previously undescribed species of zooplankton, cyanobacterial, and bacterial populations.

  15. Fertilization of eggs of Lake Michigan lake trout Salvelinus namaycush in lake water: Effect of PCBs (Aroclor 1254)

    USGS Publications Warehouse

    Foster, N.R.; Berlin, W.H.

    1997-01-01

    Various studies indicate that PCBs appear to have an adverse effect on the viability of fertilized eggs and subsequent early life stages of lake trout and related species. Our tests detected no impairment of fertilization of lake trout eggs in PCB-dosed lake water. The concentration of PCBs in the fertilization medium that we used was more than 20 times as high as estimated ambient levels in southeastern Lake Michigan and it appears unlikley that ambient levels of PCBs in the water at fertilization would contribute significantly to the apparent widespread reproductive failure of lake trout there.

  16. Lava Lakes in Io's Paterae

    NASA Astrophysics Data System (ADS)

    Radebaugh, J.; McEwen, A. S.; Milazzo, M.; Davies, A. G.; Keszthelyi, L. P.; Geissler, P.

    2002-05-01

    New Galileo images and Galileo and Cassini temperature data lend credence to previous proposals that some of the paterae on Io contain lava lakes, similar in some ways to those observed on Earth. Galileo's October 2001 I32 flyby produced spectacular new high resolution observations of Io's paterae, their margins, and floors. Images reveal where lavas have filled Emakong Patera and overtopped its margins. Landslides from the peaks of Tohil Mons are not present on the adjacent floor of a dark patera, perhaps because they have slumped into a molten lava pit. Dark lavas have filled and drained back from colorful Tupan Patera, leaving a ring of material on its walls. This patera also shows evidence of interaction between molten sulfur and silicate lavas, a relationship observed at the terrestrial Poas Volcano (Francis et al., 1980, Nature 283, 754-756; Oppenheimer and Stevenson, 1990, La Recherche 21,1088-1090). The extremely uniformly dark materials in many other paterae could also be lava lakes. Pele Volcano on Io, in particular, has previously been considered a lava lake based on several characteristics (Davies et al., 2001, JGR 106,33,079-33,103). Recent analyses of eclipse images of Pele from Cassini reveal average temperatures of 1375 K, with variations on short (~10 minute) timescales, consistent with active fountaining in a lava lake. Similar oscillations around high temperatures over these time scales are seen in terrestrial lava lakes, such as at Kupaianaha (Flynn et al., GRL, 19,6461-6476, 1993) and Erta Ale (Bessard, Caillet and others, in progress). Nightside high resolution (60 m/pixel) images from Galileo I32 reveal a region of overturning and convection, with some areas reaching in excess of 1800 K, verifying very high-temperature components identified in high-resolution NIMS data (Lopes et al., 2001, JGR, 106, 33,053-33,078). This region is ringed with small hotspots, comparable to locations of breakup and fountaining at the margins of many terrestrial

  17. Remote sensing and lake eutrophication

    NASA Technical Reports Server (NTRS)

    Wrigley, R. C.; Horne, A. J.

    1974-01-01

    An infrared photograph of part of Clear Lake, Cal., shows complex patterns of blue-green algal blooms which were not observed by conventional limnological techniques. Repeated observations of patterns such as these can be used to chart the surface movement of these buoyant algae and can also be used to help control algal scums in eutrophic lakes. Although it is believed that most of the observed patterns resulted from Aphanizomenon (a few were also observed which resulted from suspended sediment), spectral signatures of the algal patterns varied.

  18. Crustal structure between Lake Mead, Nevada, and Mono Lake, California

    USGS Publications Warehouse

    Johnson, Lane R.

    1964-01-01

    Interpretation of a reversed seismic-refraction profile between Lake Mead, Nevada, and Mono Lake, California, indicates velocities of 6.15 km/sec for the upper layer of the crust, 7.10 km/sec for an intermediate layer, and 7.80 km/sec for the uppermost mantle. Phases interpreted to be reflections from the top of the intermediate layer and the Mohorovicic discontinuity were used with the refraction data to calculate depths. The depth to the Moho increases from about 30 km near Lake Mead to about 40 km near Mono Lake. Variations in arrival times provide evidence for fairly sharp flexures in the Moho. Offsets in the Moho of 4 km at one point and 2 1/2 km at another correspond to large faults at the surface, and it is suggested that fracture zones in the upper crust may displace the Moho and extend into the upper mantle. The phase P appears to be an extension of the reflection from the top of the intermediate layer beyond the critical angle. Bouguer gravity, computed for the seismic model of the crust, is in good agreement with the measured Bouguer gravity. Thus a model of the crustal structure is presented which is consistent with three semi-independent sources of geophysical data: seismic-refraction, seismic-reflection, and gravity.

  19. Urban lake sediment chemistry: Lake design, runoff, and watershed impact

    SciTech Connect

    Amalfi, F.A.

    1988-01-01

    Sediments of twenty-two urban lakes and stormwater discharge into five of the impoundments were analyzed for the presence of selected metallic priority pollutants, total petroleum hydrocarbons, and volatile and extractable organic compounds. The concentration (mg/kg dry weight) ranges of metals in lake sediments were: arsenic 7-29, cadmium < 0.5-0.5, chromium 14-55, lead <1-138, selenium <0.01-1.1, silver 0.2-2.1, copper 25-2760, nickel 5-40, and zinc 33.9-239. Concentrations of total petroleum hydrocarbons ranged from 30 to 4400 mg/kg (wet weight). Organic priority pollutants detected in the urban lake impoundments included tetrachlorethylene, 1,1,2-trichloroethane, trichlorofluoromethane, phthalate esters, chloroform, and dichlorobromomethane. Stormwater runoff contained measurable quantities of arsenic, chromium, lead, selenium, copper, nickel, zinc, and petroleum hydrocarbons; whereas organic priority pollutants were not detected. Stormwater runoff pollutant loads indicated that runoff provides a significant contribution of metals and petroleum hydrocarbons to lake sediments.

  20. Post Audit of Lake Michigan Lake Trout PCB Model Forecasts

    EPA Science Inventory

    The Lake Michigan (LM) Mass Balance Study was conducted to measure and model polychlorinated biphenyls (PCBs) and other anthropogenic substances to gain a better understanding of the transport, fate, and effects of these substances within the system and to aid managers in the env...

  1. Feeding ecology of lake whitefish larvae in eastern Lake Ontario

    USGS Publications Warehouse

    Johnson, James H.; McKenna, James E.; Chalupnicki, Marc A.; Wallbridge, Tim; Chiavelli, Rich

    2009-01-01

    We examined the feeding ecology of larval lake whitefish (Coregonus clupeaformis) in Chaumont Bay, Lake Ontario, during April and May 2004-2006. Larvae were collected with towed ichthyoplankton nets offshore and with larval seines along the shoreline. Larval feeding periodicity was examined from collections made at 4-h intervals over one 24-h period in 2005. Inter-annual variation in diet composition (% dry weight) was low, as was spatial variation among collection sites within the bay. Copepods (81.4%), primarily cyclopoids (59.1%), were the primary prey of larvae over the 3-year period. Cladocerans (8.1%; mainly daphnids, 6.7%) and chironomids (7.3%) were the other major prey consumed. Larvae did not exhibit a preference for any specific prey taxa. Food consumption of lake whitefish larvae was significantly lower at night (i.e., 2400 and 0400 h). Substantial variation in diet composition occurred over the 24-h diel study. For the 24-h period, copepods were the major prey consumed (50.4%) and their contribution in the diet ranged from 29.3% (0400 h) to 85.9% (1200 h). Chironomids made up 33.4% of the diel diet, ranging from 8.0% (0800 h) to 69.9% (0400 h). Diel variation in the diet composition of lake whitefish larvae may require samples taken at several intervals over a 24-h period to gain adequate representation of their feeding ecology.

  2. Low deuterium content of Lake Vanda, Antarctica

    USGS Publications Warehouse

    Ragotzkie, R.A.; Friedman, I.

    1965-01-01

    Lake Vanda in Victoria Land, Antarctica, is permanently ice-covered and permanently stratified, with warm, salty water near the bottom. Deuterium analyses of lake water from several levels indicate that the lake has a low deuterium content, and that it is stratified with respect to this isotope. This low deuterium content supports the evidence from the lake's ionic content that the saline layer is not of marine origin, and it indicates that evaporation from the ice surface has taken place. The stratification of the lake with respect to deuterium suggests that the upper and lower layers of water were formed at different times from different sources of glacial melt water.

  3. Common plankton of Twin Lakes, Colorado

    SciTech Connect

    Lieberman, D.M.

    1983-02-01

    A series of studies is being performed to evaluate the effects of the Mt. Elbert Pumped-Storage Powerplant on the ecology of Twin Lakes. Twin Lakes are a pair of connected dimictic lakes, formed as the result of glacial action on alluvial deposits. This report presents a taxonomic species study of the common plankton collected since 1974 from Twin Lakes. A total of 11 zooplankters and 14 phytoplankters were identified from the limnetic zone of Twin Lakes and the associated Mt. Elbert Forebay. The four divisions of zooplankton included four species of Rotifera (rotifer), three species of Copepoda (copepod), three species of Cladocera (cladoceran), and one species of Mysidacea (opossum shrimp).

  4. Tapping rocks for Terror Lake hydro project

    SciTech Connect

    Sieber, O.V.

    1983-12-01

    The Terror Lake hydro project in Alaska is described. Terror Lake is a small alpine lake surrounded by barren glacier-scoured, rocky mountain tops and plateaus that do not retain moisture. The method for obtaining more water for the hydro project in Kodiak is unique. The basic program was to dam up the outlet of Terror Lake and raise the water level 170 ft. from approximately 1250 ft. above sea level to 1420 ft. Although the megawatt output of the project is small, the concept of the Terror Lake Project has an epic scale to it.

  5. Evaluation of offshore stocking of Lake Trout in Lake Ontario

    USGS Publications Warehouse

    Lantry, B.F.; O'Gorman, R.; Strang, T.G.; Lantry, J.R.; Connerton, M.J.; Schanger, T.

    2011-01-01

    Restoration stocking of hatchery-reared lake trout Salvelinus namaycush has occurred in Lake Ontario since 1973. In U.S. waters, fish stocked through 1990 survived well and built a large adult population. Survival of yearlings stocked from shore declined during 1990–1995, and adult numbers fell during 1998–2005. Offshore stocking of lake trout was initiated in the late 1990s in response to its successful mitigation of predation losses to double-crested cormorants Phalacrocorax auritus and the results of earlier studies that suggested it would enhance survival in some cases. The current study was designed to test the relative effectiveness of three stocking methods at a time when poststocking survival for lake trout was quite low and losses due to fish predators was a suspected factor. The stocking methods tested during 2000–2002 included May offshore, May onshore, and June onshore. Visual observations during nearshore stockings and hydroacoustic observations of offshore stockings indicated that release methods were not a direct cause of fish mortality. Experimental stockings were replicated for 3 years at one site in the southwest and for 2 years at one site in the southeast. Offshore releases used a landing craft to transport hatchery trucks from 3 to 6 km offshore out to 55–60-m-deep water. For the southwest site, offshore stocking significantly enhanced poststocking survival. Among the three methods, survival ratios were 1.74 : 1.00 : 1.02 (May offshore : May onshore : June onshore). Although not statistically significant owing to the small samples, the trends were similar for the southeast site, with survival ratios of 1.67 : 1.00 : 0.72. Consistent trends across years and sites indicated that offshore stocking of yearling lake trout during 2000–2002 provided nearly a twofold enhancement in survival; however, this increase does not appear to be great enough to achieve the 12-fold enhancement necessary to return population abundance to restoration

  6. 12. Photographic copy of copy of Twin Lakes Outlet Works ...

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

    12. Photographic copy of copy of Twin Lakes Outlet Works construction drawing dated January 15, 1951. Drawn by W.A. Doe for the Twin Lakes Reservoir and Canal Co. (copy in possession of Bureau of Reclamation, location of original unknown) 'AS CONSTRUCTED' PLANS OF 1949-50, REHABILITATION OF TWIN LAKES RESERVOIR OUTLET WORKS, DETAILS OF DISCHARGE BASIN. - Twin Lakes Dam & Outlet Works, Beneath Twin Lakes Reservoir, T11S, R80W, S22, Twin Lakes, Lake County, CO

  7. 11. Photographic copy of copy of Twin Lakes Outlet Works ...

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

    11. Photographic copy of copy of Twin Lakes Outlet Works construction drawing dated January 15, 1951. Drawn by W.A. Doe for the Twin Lakes Reservoir and Canal Co. (copy in possession of Bureau of Reclamation, location of original unknown) 'AS CONSTRUCTED' PLANS OF 1949-1950, REHABILITATION OF TWIN LAKES RESERVOIR OUTLET WORKS, DETAILS OF UPSTREAM WING WALLS. - Twin Lakes Dam & Outlet Works, Beneath Twin Lakes Reservoir, T11S, R80W, S22, Twin Lakes, Lake County, CO

  8. Hydrology of Lake Carroll, Hillsborough County, Florida

    USGS Publications Warehouse

    Henderson, S.E.; Hayes, R.D.; Stoker, Y.E.

    1985-01-01

    Lakeshore property around Lake Carroll has undergone extensive residential development since 1960. This development increased the lake shoreline, altered surface water flow to and from the lake, and may have affected lake-stage characteristics. Some areas of the lake were dredged to provide fill material for lakefront property. Water-balance analyses for 1952-60, a predevelopment period, and 1961-80, a period of residential development, indicate that both net surface water flow to the lake and downward leakage from the lake to the Floridan aquifer were greater after 1960. These changes were due more to changes in the regional climate and related changes in ground-water levels than to changes associated with residential development. Results of water quality analyses in 1980-81 are within State limits for surface waters used for recreation and wildlife propagation. (USGS)

  9. Geographic Analysis of Alaska Lake Districts

    NASA Astrophysics Data System (ADS)

    Arp, C. D.; Jones, B. M.; Zimmerman, C. E.

    2007-12-01

    The state of Alaska has over 400,000 lakes greater than 0.01 km2 in surface area covering approximately 3.3% of the landscape. As in most lake-rich regions, these lakes are unevenly distributed on the landscape. So in order to better understand how lakes are organized on the landscape and relate this geographic organization to other climatologic, geologic, and biogeographic characteristics, we analyzed the spatial distribution of Alaska lakes. Using a combination of numerical abundance and surface-area extent of lakes, we selected lake density thresholds to identify and delineate 22 lake districts in Alaska. The total area of these 22 lakes districts occupy 16% of Alaska, yet encompass 64% of lakes and 76% of lake surface-area. The three largest lake districts are associated with the Yukon-Kuskokwin Delta, the Northern Arctic Coastal Plain, and the mountain front of the Alaskan Range on the Alaska Peninsula. Interestingly, these largest lake districts are covered by >17% lakes, while most of the smaller lake districts we identified have <10% lake cover. Of the remaining smaller lake districts, 9 are associated with mountain fronts or intermountain basins, 4 are associated with coastal plains, 3 are associated with floodplains and deltas, and 3 occur in high-elevation or mountain terrain. The highest numerical lake densities occur at deltas, while relatively lower densities occur in mountainous areas where individual lakes are often larger in surface area and likely volume. Comparison of these lake districts were made to permafrost distribution, glacial history, lithology, watershed position, and regional hydrologic budgets and regimes to better understand where lake-rich regions occur, why, and how they might change in the future. Ten of the 22 lake districts occur in areas dominated by continuous permafrost, 6 occur in areas of discontinuous or sporadic permafrost, and the other 6 occur in regions without perennially frozen soils. The majority of lake districts

  10. Seasonal Reversals of Groundwater Flow Around Lakes and the Relevance to Stagnation Points and Lake Budgets

    NASA Astrophysics Data System (ADS)

    Anderson, Mary P.; Munter, James A.

    1981-08-01

    Several researchers have observed seasonal reversals in the direction of groundwater flow around lakes. If these reversals are prolonged and are accompanied by the formation of a stagnation point, they may have a significant effect on a lake's water and nutrient budgets. The formation of a stagnation point at a flow-through lake (i.e., a lake that receives groundwater through part of the lake basin and recharges the groundwater system over the rest of the lake basin) is accomplished by the formation of a groundwater mound on the downgradient side of the lake. In this paper the seasonal formation of a stagnation point at Snake Lake, Wisconsin, is investigated with the aid of two-dimensional transient computer models applied in cross section and areally. The analysis demonstrates the potential for the seasonal formation of a stagnation point at a flow-through lake and provides some insight into the transient development of the stagnation point.

  11. INTERACTIVE PIT LAKES 2004 CONFERENCE

    EPA Science Inventory

    This CD and the workshop provide a pit lakes forum for the exchange of scientific information on current domestic and international approaches, including arid and wet regions throughout the world. These approaches include characterization, modeling/monitoring, and treatment and r...

  12. Eutrophication of lakes and rivers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Eutrophication is an ecological process, akin to aging, in which a water body is increasingly enriched with organic matter. While the most obvious signs of eutrophication in lakes and rivers involve algal blooms and fish kills, the systemic of eutrophication, although profound, are often not as noti...

  13. LAKE PONTCHARTRAIN ESTUARY CONSERVATION PLAN

    EPA Science Inventory

    The Nature Conservancy will conduct a series of a least four science expert workshops to develop a Site Conservation Plan for the Lake Pontchartrain Estuary and adjacent wetlands. The objective of the Site Conservation Plan is to identify conservation targets, threats or stresse...

  14. The Source of Lake Wobegon

    ERIC Educational Resources Information Center

    Phelps, Richard P.

    2005-01-01

    John J. Cannell's late 1980s "Lake Wobegon" reports suggested widespread deliberate educator manipulation of norm-referenced standardized test (NRT) administrations and results, resulting in artificial test score gains. The Cannell studies have been referenced in education research since, but as evidence that high stakes (and not cheating or lax…

  15. Multiple Waterspouts at Lake Tahoe.

    NASA Astrophysics Data System (ADS)

    Grotjahn, Richard

    2000-04-01

    At least six waterspouts occurred at a large alpine lake in the western United States over several hours during 26 September 1998. Photographs showing the conditions as well as representative examples of this extremely rare event are presented. Some mechanisms are discussed that may explain the persistence of the convection and the low-level vorticity that gave rise to the waterspouts.

  16. CHED Events: Salt Lake City

    NASA Astrophysics Data System (ADS)

    Wink, Donald J.

    2009-03-01

    The Division of Chemical Education (CHED) Committee meetings planned for the Spring 2009 ACS Meeting in Salt Lake City will be in the Marriott City Center Hotel. Check the location of other CHED events, the CHED Social Event, the Undergraduate Program, Sci-Mix, etc. because many will be in the Salt Palace Convention Center.

  17. Alternative attractors of shallow lakes.

    PubMed

    Scheffer, M

    2001-07-17

    Ponds and shallow lakes can be very clear with abundant submerged plants, or very turbid due to a high concentration of phytoplankton and suspended sediment particles. These strongly contrasting ecosystem states have been found to represent alternative attractors with distinct stabilizing feedback mechanisms. In the turbid state, the development of submerged vegetation is prevented by low underwater light levels. The unprotected sediment frequently is resuspended by wave action and by fish searching for food causing a further decrease of transparency. Since there are no plants that could serve as refuges, zooplankton is grazed down by fish to densities insufficient to control algal blooms. In contrast, the clear state in eutrophic shallow lakes is dominated by aquatic macrophytes. The submerged macrophytes prevent sediment resuspension, take up nutrients from the water, and provide a refuge for zooplankton against fish predation. These processes buffer the impacts of increased nutrient loads until they become too high. Consequently, the response of shallow lakes to eutrophication tends to be catastrophic rather than smooth, and various lakes switch back and forth abruptly between a clear and a turbid state repeatedly without obvious external forcing. Importantly, a switch from a turbid to a stable clear state often can be invoked by means of biomanipulation in the form of a temporary reduction of the fish stock. PMID:12806081

  18. BACTERIAL INHIBITORS IN LAKE WATER

    EPA Science Inventory

    The populations of six bacterial genera fell rapidly after their addition to sterile lake water but not after their addition to buffer. The decline in numbers of two species that were studied further, Klebsiella pneumoniae and Micrococcus flavus, occurred even when the buffer was...

  19. The Taos Blue Lake Ceremony.

    ERIC Educational Resources Information Center

    Bodine, John J.

    1988-01-01

    Describes the Blue Lake Ceremony of the Taos Pueblo Indians of New Mexico. Reproduces the 1906 account of the ceremony by anthropologist Matilda Coxe Stevenson and notes modern verification and change. Discusses the importance of this annual August pilgrimage and initiation rite to the preservation of Taos culture. (SV)

  20. Dinkey Lakes Roadless Area, California

    SciTech Connect

    Dodge, F.C.W.; Federspiel, F.E.

    1984-01-01

    The results of a mineral survey conducted in 1980, show that parts of the Dinkey Lakes Roadless Area have substantiated resource potential for tungsten and marble and probable resource potential for quartz crystal gemstones. A probable resource potential for geothermal energy exists in one small area. No potential for other metallic mineral or energy resources was identified in this study.

  1. Thermal springs in Lake Baikal

    SciTech Connect

    Shanks, W.C. III; Callender, E. )

    1992-06-01

    Pore waters extracted from sediment cores were analyzed for their oxygen and hydrogen isotopic compositions and major ion chemistry to determine the source of water from a vent area for diffuse lake-bottom thermal springs or seeps in Frolikha Bay, northeastern Lake Baikal. The {delta}{sup 18}O values of pore waters range from {minus}15.2{per thousand} to {minus}16.7{per thousand}, and {delta}D values range from {minus}119{per thousand} to {minus}126{per thousand} (both isotopes determined relative to standard mean ocean water (SMOW)). Bottom water in Lake Baikal has a {delta}{sup 18}O value of {minus}5.6{per thousand} and a {delta}D values of {minus}120{per thousand}. Pore waters in the vent area are significantly enriched in Mg, K, Ca, and especially Na and have the lowest {delta}D and {delta}{sup 18}O values; these pore waters are isotopically and chemically distinct from pore waters in other, more typical parts of the lake. The pore-water isotopic data fall on a local meteoric water line, and covariations in water isotopes and chemistry are not consistent with evaporation or hydrothermal water-rock interaction. The thermal springs represent discharging meteoric waters that have been gently heated during subsurface circulation and are largely unaltered isotopically. Chemical variations are most likely due to dissolution of subsurface evaporites.

  2. The Lava sequence of the East African Rift escarpment in the Oldoinyo Lengai - Lake Natron sector, Tanzania

    NASA Astrophysics Data System (ADS)

    Neukirchen, Florian; Finkenbein, Thomas; Keller, Jörg

    2010-12-01

    A 500 m sequence of horizontal lava flows forms the Gregory rift escarpment of the western rift shoulder between Lake Natron and Oldoinyo Lengai. A detailed volcanic stratigraphy of this >1.2 Ma evolution of the EAR in Northern Tanzania is presented. The sequence is formed by several distinct rock suites, with increasing alkalinity from base to top. Alkali olivine basalts of the Waterfall Sequence at the base are followed by a basanite series, and by a range of evolved nephelinites forming the upper part of the escarpment. Numerous dykes and Strombolian scoria deposits indicate local fissure eruptions as opposed to or in addition to more distant sources. Primitive compositions within each of the series indicate variable candidates for primary magmas. The composition of the basanite suite ranges from primitive mantle melts (high Mg#, Cr, Ni) to more evolved rocks, in particular hawaiites, generated by fractionation of olivine, pyroxene and magnetite. Inter-bedded within the basanite suite, one single olivine melilitite flow with high Mg# and abundant olivine and pyroxene megacrysts is the only primitive candidate for the nephelinite suite. However, in view of the large compositional gap and marked differences in incompatible element ratios, a relation between this flow and the nephelinites remains hypothetical. The variation within the evolved nephelinite series can be partly explained by fractionation of pyroxene, apatite, perovskite (and some nepheline), while magma mixing is indicated by zonation patterns of pyroxene. The most evolved nephelinite, however, differs significantly from all other nephelinites in major and trace elements. Thus the entire sequence is petrologically not a coherent evolution, rather the result of different mantle melts fractionating under variable conditions. Carved into the rift scarp of the study area west of Engare Sero is a young explosion crater, the Sekenge Crater. Sekenge Tuffs are olivine melilitites, similar to other craters and

  3. Stable isotope composition of Earth's large lakes

    NASA Astrophysics Data System (ADS)

    Jasechko, S.; Gibson, J. J.; YI, Y.; Birks, S. J.; Sharp, Z. D.

    2011-12-01

    Lakes cover about three percent of Earth's continental area. Large lakes can significantly influence lake shore and regional climates by increasing specific humidity during evaporation and by moderating air temperatures. Stable isotopes of oxygen and hydrogen can be used to quantify lake evaporation, providing a supplementary and often cost-advantageous alternative to conventional hydrologic approaches that require over lake monitoring. Further, stable isotopes in lake sediments are an established tool in paleolimnology; however, interpreting changes to a lake's past isotope composition requires a comprehensive understanding of contemporary controls. Here, δ18O and δ2H values of water in modern lakes exceeding roughly five hundred square kilometres are compiled (n > 35). Voluminous and seasonally mixed lakes - such as the North American Great Lakes - have the most homogenous stable isotope compositions, while perennially-stratified and shallow lakes show greater variability. A rudimentary stable isotope mass balance is used to assess evaporation fluxes from large lakes on Earth. The approach taken simultaneously constrains evaporation outputs for both oxygen and hydrogen stable isotopes by accounting for lake effects on the overlying atmosphere. Model development highlights important considerations such as isotopic stratification (Tanganyika), disequilibrium isotopic mass balances (Baikal), and non-steady hydrologic balances. Further, the isotope composition of Earth's continental surface water reservoir is calculated. This value - weighted to volume - is δ18O = -7.5±1.7 per mille relative to standard mean ocean water. The compiled data may be a useful tracer of continental evaporate in global atmospheric water cycle studies and could be coupled to climate models capable of incorporating oxygen-18 and deuterium tracers to improve or validate calculations of lake effects on regional water cycling.

  4. Contaminant Monitoring Strategy for Henrys Lake, Idaho

    SciTech Connect

    John S. Irving; R. P. Breckenridge

    1992-12-01

    Henrys Lake, located in southeastern Idaho, is a large, shallow lake (6,600 acres, {approx} 17.1 feet maximum depth) located at 6,472 feet elevation in Fremont Co., Idaho at the headwaters of the Henrys Fork of the Snake River. The upper watershed is comprised of high mountains of the Targhee National Forest and the lakeshore is surrounded by extensive flats and wetlands, which are mostly privately owned. The lake has been dammed since 1922, and the upper 12 feet of the lake waters are allocated for downriver use. Henrys Lake is a naturally productive lake supporting a nationally recognized ''Blue Ribbon'' trout fishery. There is concern that increasing housing development and cattle grazing may accelerate eutrophication and result in winter and early spring fish kills. There has not been a recent thorough assessment of lake water quality. However, the Department of Environmental Quality (DEQ) is currently conducting a study of water quality on Henrys Lake and tributary streams. Septic systems and lawn runoff from housing developments on the north, west, and southwest shores could potentially contribute to the nutrient enrichment of the lake. Many houses are on steep hillsides where runoff from lawns, driveways, etc. drain into wetland flats along the lake or directly into the lake. In addition, seepage from septic systems (drainfields) drain directly into the wetlands enter groundwater areas that seep into the lake. Cattle grazing along the lake margin, riparian areas, and uplands is likely accelerating erosion and nutrient enrichment. Also, cattle grazing along riparian areas likely adds to nutrient enrichment of the lake through subsurface flow and direct runoff. Stream bank and lakeshore erosion may also accelerate eutrophication by increasing the sedimentation of the lake. Approximately nine streams feed the lake (see map), but flows are often severely reduced or completely eliminated due to irrigation diversion. In addition, subsurface flows can occur as a

  5. Acoustic estimates of abundance and distribution of spawning lake trout on Sheboygan Reef in Lake Michigan

    USGS Publications Warehouse

    Warner, D.M.; Claramunt, R.M.; Janssen, J.; Jude, D.J.; Wattrus, N.

    2009-01-01

    Efforts to restore self-sustaining lake trout (Salvelinus namaycush) populations in the Laurentian Great Lakes have had widespread success in Lake Superior; but in other Great Lakes, populations of lake trout are maintained by stocking. Recruitment bottlenecks may be present at a number of stages of the reproduction process. To study eggs and fry, it is necessary to identify spawning locations, which is difficult in deep water. Acoustic sampling can be used to rapidly locate aggregations of fish (like spawning lake trout), describe their distribution, and estimate their abundance. To assess these capabilities for application to lake trout, we conducted an acoustic survey covering 22 km2 at Sheboygan Reef, a deep reef (<40 m summit) in southern Lake Michigan during fall 2005. Data collected with remotely operated vehicles (ROV) confirmed that fish were large lake trout, that lake trout were 1–2 m above bottom, and that spawning took place over specific habitat. Lake trout density exhibited a high degree of spatial structure (autocorrelation) up to a range of ~190 m, and highest lake trout and egg densities occurred over rough substrates (rubble and cobble) at the shallowest depths sampled (36–42 m). Mean lake trout density in the area surveyed (~2190 ha) was 5.8 fish/ha and the area surveyed contained an estimated 9500–16,000 large lake trout. Spatial aggregation in lake trout densities, similarity of depths and substrates at which high lake trout and egg densities occurred, and relatively low uncertainty in the lake trout density estimate indicate that acoustic sampling can be a useful complement to other sampling tools used in lake trout restoration research.

  6. Lake volume monitoring from space

    NASA Astrophysics Data System (ADS)

    Crétaux, Jean-Francois; Abarca Del Rio, Rodrigo; Berge-Nguyen, Muriel; Arsen, Adalbert; Drolon, Vanessa; Maisongrande, Philippe

    2016-04-01

    Lakes are integrator of environmental changes occurring at regional to global scale and present a high variety of behaviors on a variety of time scales (cyclic and secular) depending on the climate conditions and their morphology. In addition their crucial importance as water stocks and retaining, given the significant environment changes occurring worldwide at many anthropocentric levels, has increased the necessity of monitoring all its morphodynamics characteristics, say water level, surface (water contour) and volume. The satellite altimetry and satellite imagery together are now widely used for the calculation of lakes and reservoirs water storage changes worldwide. However strategies and algorithms to calculate these characteristics are not straightforward and need development of specific approaches. We intend to present a review of some of these methodologies by using the lakes over the Tibetan Plateau to illustrate some critical aspects and issues (technical and scientific) linked with the survey of climate changes impacts on surface waters from remote sensing data. Many authors have measured water variations using the short period of remote sensing measurements available, although time series are probably too short to lead to definitive conclusions to link these results directly with the framework of climate changes. Indeed, many processes beyond the observations are still uncertain, for example the influence of morphology of the lakes. The time response for a lake to reach new state of equilibrium is one of the key aspects often neglected in the current literature. Observations over long period of time, therein maintaining a constellation of comprehensive and complementary satellite missions with a continuity of services over decades, especially when ground gauges network is too limited is therefore a necessity. In addition, the design of future satellite missions with new instrumental concepts (e.g. SAR, SARin, Ka band altimetry, Ka interferometry) is

  7. Spatial and temporal genetic diversity of lake whitefish (Coregonus clupeaformis (Mitchill)) from Lake Huron and Lake Erie

    USGS Publications Warehouse

    Stott, Wendylee; Ebener, Mark P.; Mohr, Lloyd; Hartman, Travis; Johnson, Jim; Roseman, Edward F.

    2013-01-01

    Lake whitefish (Coregonus clupeaformis (Mitchill)) are important commercially, culturally, and ecologically in the Laurentian Great Lakes. Stocks of lake whitefish in the Great Lakes have recovered from low levels of abundance in the 1960s. Reductions in abundance, loss of habitat and environmental degradation can be accompanied by losses of genetic diversity and overall fitness that may persist even as populations recover demographically. Therefore, it is important to be able to identify stocks that have reduced levels of genetic diversity. In this study, we investigated patterns of genetic diversity at microsatellite DNA loci in lake whitefish collected between 1927 and 1929 (historical period) and between 1997 and 2005 (contemporary period) from Lake Huron and Lake Erie. Genetic analysis of lake whitefish from Lakes Huron and Erie shows that the amount of population structuring varies from lake to lake. Greater genetic divergences among collections from Lake Huron may be the result of sampling scale, migration patterns and demographic processes. Fluctuations in abundance of lake whitefish populations may have resulted in periods of increased genetic drift that have resulted in changes in allele frequencies over time, but periodic genetic drift was not severe enough to result in a significant loss of genetic diversity. Migration among stocks may have decreased levels of genetic differentiation while not completely obscuring stock boundaries. Recent changes in spatial boundaries to stocks, the number of stocks and life history characteristics of stocks further demonstrate the potential of coregonids for a swift and varied response to environmental change and emphasise the importance of incorporating both spatial and temporal considerations into management plans to ensure that diversity is preserved.

  8. Remote sensing of algal blooms by aircraft and satellite in Lake Erie and Utah Lake

    NASA Technical Reports Server (NTRS)

    Strong, A. E.

    1974-01-01

    During late summer, when the surface waters of Lake Erie reach their maximum temperature, an algal bloom is likely to develop. Such phenomena, which characterize eutrophic conditions, have been noticed on other shallow lakes using the Earth Resources Technology Satellite (ERTS-1). The concentration of the algae into long streamers provides additional information on surface circulations. To augment the ERTS Multispectral Scanner Subsystem data of Lake Erie, an aircraft was used to obtain correlative thermal-IR and additional multiband photographs. A large bloom of Aphanizomenon flos-aquae observed in Utah Lake together with recent bloom history in Lake Erie is used to verify the Great Lakes bloom.

  9. Life history of lake herring of Green Bay, Lake Michigan

    USGS Publications Warehouse

    Smith, Stanford H.

    1956-01-01

    Although the lake herring has been an important contributor to the commercial fish production of Green Bay, little has been known about it. This study is based on field observations and data from about 6,500 lake herring collected over the period 1948 to 1952. Relatively nonselective commercial pound nets were a primary source of material for the study of age and growth. Commercial and experimental gill nets were used to obtain data on gear selectivity and vertical distribution. Scales were employed to investigate age and growth. Age group IV normally dominated commercial catches during the first half of the calendar year and age group III the last half. At these ages the fish averaged about 10.5 inches in length. The season's growth started in May, was most rapid in July, and terminated near the end of October. The sexes grew at the same rate. Selectivity of fishing gear was found to influence the estimation of growth. Geographical and annual differences in growth are shown. Factors that might contribute to discrepancies in calculated growth are evaluated. Possible real and apparent causes of growth compensation are given. The relation between length and weight is shown to vary with sex, season, year, and method of capture. Females were relatively more plentiful in commercial catches in February than in May through December. The percentage of females decreased with increase in age in pound-net catches but increased with age in gill-net samples. Within a year class the percentage of females decreased with increase in age. Most Green Bay lake herring mature during their second or third year of life. They are pelagic spawners with most intensive spawning over shallow areas. Spawning takes place between mid-November and mid-December, and eggs hatch in April and May. Lake herring ovaries contained from 3,500 to 11,200 eggs (averaged 6,375). Progress of spawning by age, sex, and length is given. Lake herring were distributed at all depths in Green Bay in early May, were

  10. 77 FR 41686 - Safety Zone; Sheffield Lake Fireworks, Lake Erie, Sheffield Lake, OH

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-16

    ... DHS Department of Homeland Security FR Federal Register NPRM Notice of Proposed Rulemaking A... Management, U.S. Coast Guard Sector Buffalo; telephone 716- 843-9343, email SectorBuffaloMarineSafety@uscg... Lake, OH. The Captain of the Port Buffalo has determined that fireworks launched proximate to...

  11. EFFECTS OF COMPLEX LAKE EFFLUENTS ON PHOTOSYNTHESIS IN LAKE ERIE AND LAKE HURON

    EPA Science Inventory

    Phytoplankton are the base of the food chain in most large lake ecosystems; if affected by environmental pollutants, significant ecosystem changes can result with potential impact on higher trophic levels. his research determined the effects of a complex effluent discharge from t...

  12. Patterns in benthic biodiversity link lake trophic status to structure and potential function of three large, deep lakes.

    PubMed

    Hayford, Barbara L; Caires, Andrea M; Chandra, Sudeep; Girdner, Scott F

    2015-01-01

    Relative to their scarcity, large, deep lakes support a large proportion of the world's freshwater species. This biodiversity is threatened by human development and is in need of conservation. Direct comparison of biodiversity is the basis of biological monitoring for conservation but is difficult to conduct between large, insular ecosystems. The objective of our study was to conduct such a comparison of benthic biodiversity between three of the world's largest lakes: Lake Tahoe, USA; Lake Hövsgöl, Mongolia; and Crater Lake, USA. We examined biodiversity of common benthic organism, the non-biting midges (Chironomidae) and determined lake trophic status using chironomid-based lake typology, tested whether community structure was similar between the three lakes despite geographic distance; and tested whether chironomid diversity would show significant variation within and between lakes. Typology analysis indicated that Lake Hövsgöl was ultra-oligotrophic, Crater Lake was oligotrophic, and Lake Tahoe was borderline oligotrophic/mesotrophic. These results were similar to traditional pelagic measures of lake trophic status for Lake Hövsgöl and Crater Lake but differed for Lake Tahoe, which has been designated as ultra-oligotrophic by traditional pelagic measures such as transparency found in the literature. Analysis of similarity showed that Lake Tahoe and Lake Hövsgöl chironomid communities were more similar to each other than either was to Crater Lake communities. Diversity varied between the three lakes and spatially within each lake. This research shows that chironomid communities from these large lakes were sensitive to trophic conditions. Chironomid communities were similar between the deep environments of Lake Hövsgöl and Lake Tahoe, indicating that chironomid communities from these lakes may be useful in comparing trophic state changes in large lakes. Spatial variation in Lake Tahoe's diversity is indicative of differential response of chironomid

  13. Monitoring Land Cover Change in the Lake Superior Basin

    EPA Science Inventory

    Lake Superior is the largest freshwater lake in the world by area and the third largest by volume. It is also the most pristine of the Great Lakes (Lake Superior Lakewide Management Plan 2006). Even still, Lake Superior is not without its threats ranging from chemical contamina...

  14. 250 NORTH & MAIN STREET (PARK 83, SALT LAKE CITY ...

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

    250 NORTH & MAIN STREET (PARK 8-3, SALT LAKE CITY CEMETERY LOCATER), SALT LAKE CITY, UT. VIEW LOOKING NORTH - REPHOTOGRAPH OF HISTORIC SHIPLER PHOTO # 18271, UTAH STATE HISTORICAL SOCIETY COLLECTION. - Salt Lake City Cemetery, 200 N Street, Salt Lake City, Salt Lake County, UT

  15. 40 CFR 35.1605-3 - Publicly owned freshwater lake.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 1 2013-07-01 2013-07-01 false Publicly owned freshwater lake. 35.1605... Owned Freshwater Lakes § 35.1605-3 Publicly owned freshwater lake. A freshwater lake that offers public... maintaining the public access and recreational facilities of this lake or other publicly owned...

  16. 40 CFR 35.1605-3 - Publicly owned freshwater lake.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Publicly owned freshwater lake. 35.1605... Owned Freshwater Lakes § 35.1605-3 Publicly owned freshwater lake. A freshwater lake that offers public... maintaining the public access and recreational facilities of this lake or other publicly owned...

  17. 40 CFR 35.1605-3 - Publicly owned freshwater lake.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 1 2014-07-01 2014-07-01 false Publicly owned freshwater lake. 35.1605... Owned Freshwater Lakes § 35.1605-3 Publicly owned freshwater lake. A freshwater lake that offers public... maintaining the public access and recreational facilities of this lake or other publicly owned...

  18. 40 CFR 35.1605-3 - Publicly owned freshwater lake.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 1 2012-07-01 2012-07-01 false Publicly owned freshwater lake. 35.1605... Owned Freshwater Lakes § 35.1605-3 Publicly owned freshwater lake. A freshwater lake that offers public... maintaining the public access and recreational facilities of this lake or other publicly owned...

  19. 40 CFR 35.1605-3 - Publicly owned freshwater lake.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 1 2011-07-01 2011-07-01 false Publicly owned freshwater lake. 35.1605... Owned Freshwater Lakes § 35.1605-3 Publicly owned freshwater lake. A freshwater lake that offers public... maintaining the public access and recreational facilities of this lake or other publicly owned...

  20. Lake Michigan wetlands: classification, concerns, and management opportunities

    USGS Publications Warehouse

    Wilcox, Douglas A.

    2005-01-01

    The wetlands that border Lake Michigan are an extremely important component of the lake ecosystem. In this paper, I will review the status of wetland classifications used for Lake Michigan and the other Great Lakes, as well as the major management concerns and opportunities presented by Lake Michigan wetlands.

  1. Potential flood volume of Himalayan glacial lakes

    NASA Astrophysics Data System (ADS)

    Fujita, K.; Sakai, A.; Takenaka, S.; Nuimura, T.; Surazakov, A. B.; Sawagaki, T.; Yamanokuchi, T.

    2013-01-01

    Glacial lakes are potentially dangerous sources of glacial lake outburst floods (GLOFs), and represent a serious natural hazard in Himalayan countries. Despite the development of various indices aimed at determining the risk of such flooding, an objective evaluation of the thousands of Himalayan glacial lakes has yet to be completed. In this study we propose a single index, based on the depression angle from the lakeshore, which allows the lakes to be assessed using remotely sensed digital elevation models (DEMs). We test our approach on five lakes in Nepal, Bhutan, and Tibet using images taken by the declassified Hexagon KH-9 satellite before these lakes flooded. All five lakes had a steep lakefront area (SLA), on which a depression angle was steeper than our proposed threshold of 10° before the GLOF event, but the SLA was no longer evident after the events. We further calculated the potential flood volume (PFV); i.e. the maximum volume of floodwater that could be released if the lake surface was lowered sufficiently to eradicate the SLA. This approach guarantees repeatability because it requires no particular expertise to carry out. We calculated PFVs for more than 2000 Himalayan glacial lakes using the ASTER data. The distribution follows a power-law function, and we identified 49 lakes with PFVs of over 10 million m3 that require further detailed field investigations.

  2. Urmia Lake (Northwest Iran): a brief review

    PubMed Central

    Eimanifar, Amin; Mohebbi, Feridon

    2007-01-01

    Lake Urmia (or Ormiyeh) is one of the largest hypersaline lakes in the world and the habitat of a unique bisexual Artemia species (A. urmiana). Despite this, and several other values of the lake, little literature on it has been published. The present paper is an attempt to provide a brief review on various aspects of the lake. Urmia Lake, located in northwestern Iran, is an oligotrophic lake of thalassohaline origin with a total surface area between 4750 and 6100 km2 and a maximum depth of 16 m at an altitude of 1250 m. The lake is divided into north and south parts separated by a causeway in which a 1500-m gap provides little exchange of water between the two parts. Due to drought and increased demands for agricultural water in the lake's basin, the salinity of the lake has risen to more than 300 g/L during recent years, and large areas of the lake bed have been desiccated. Therefore, management and conservation of this incomparable ecosystem should be considered to improve the current condition by fisheries research institutes. PMID:17506897

  3. Ground water recharge from Lake Chad

    SciTech Connect

    Isiorho, S.; Matisoff, G.; McCall, P.L.

    1985-01-01

    Lake Chad is a shallow, closed basin lake located in Sub-Sharan Africa. It has the largest drainage basin of any lake in the world, and is also very old, being formed by tectonic processes during the Cretaceous. These features should combine to form a saline lake, but the open waters of Lake Chad are reasonably fresh, having a total dissolved solids concentration of about 320 mg/1. This apparent discrepancy can be explained by noting that recharge of the unconfined aquifer to the SW in Nigeria by ground water infiltration through the lakebed can remove significant quantities of water and dissolved solutes from the lake. The authors have measured and calculated ground water infiltration and velocities by several techniques. Direct, volumetric measurements of ground water recharge seepage give velocities on the order of .28-8.8 x 10/sup -3/ m/day. Tracer monitoring in a borehole dilution test yielded ground water velocities of 3.6 m/day to the SW (away from the lake). Hydraulic conductivities approx. .004-.6 m/day were determined by falling head measurements. Finally, using static water levels, the potentiometric surface within approx. 80 km of the southwest portion of Lake Chad yields water table gradients of 1.0-1.7 x 10/sup -4/ away from the lake. These results confirm that surface water and solute inflow to Lake Chad is removed by recharge to the unconfined aquifer in Nigeria.

  4. Lake ice cover and its influence on lake ecology in a Finnish lake district

    NASA Astrophysics Data System (ADS)

    Leppäranta, Matti; Arvola, Lauri

    2014-05-01

    A wintertime research program on the physics and biology of lakes in Häme lake district in Finland has been performed in the last five years. The set of study lakes contains a wide spectrum in size, depth and trophic status. In this region the lakes freeze over annually for 4-6 months and the mean ice thickness is around 0.5 m. The ice sheet consists of congelation ice and snow-ice. The snow-ice fraction ranges from 0 to 90 per cent depending on the snow fall history and its magnitude makes a major contribution to the ice properties and conditions in the water body beneath the ice, in particular the mechanical strength and optical thickness are much less than for congelation ice. The e-folding depth of light intensity was 50-100 cm for congelation ice and 5-10 cm for snow. A numerical model has been developed to simulate the annual cycle of ice stratigraphy, temperature and thickness. The water bodies had a 1-4 m thick upper mixed layer thick thermocline, and in deeper lakes a lower homogeneous layer. Fall cooling process was crucial to determine the temperature of the lower layer at freeze-up, anything within 0-4°C. Oxygen concentration decreased in winter, especially close to the bottom sediments, and carbon dioxide concentration increased due to respiration activity. Phytoplankton production and biomass level were low or very low and, therefore, heterotrophic and mixotrophic species were abundant. Oxygen depletion in the hypolimnium had several chemical and ecological consequences, such as release of phosphorus from the bottom sediments. In spring, just before the ice-out, photosynthesis was at a high level beneath the ice due to improved light conditions and started to elevate the oxygen concentration in the topmost water layer. Primary production under the ice is limited or prohibited by low level of available light.

  5. Water quality of selected lakes in Mount Rainier National Park, Washington, with respect to lake acidification

    SciTech Connect

    Turney, G.L.; Dion, N.P.; Sumioka, S.S.

    1986-01-01

    Thirteen lakes in Mount Rainier National park were evaluated for general chemical characteristics, sensitivity to acidification by acidic precipitation, and degree of existing acidification. The lakes studies were Allen, one of the Chenuis group, Crescent, Crystal, Eleanor, Fan, one of the Golfen group, Marsh, Mowich, Mystic, Shriner, and two unnamed lakes. The lakes were sampled in August 1983. The major cations were calcium and sodium, and the major anion was bicarbonate. Alkalinity concentrations ranged from 2.1 to 9.0 mg/L in 12 of the lakes. Allen Lake was the exception, having an alkalinity concentration of 27 mg/L. The pH values for all of the lakes ranged from 5.8 to 6.5. In most of the lakes, vertical profiles of temperature, dissolved oxygen, pH, and specific conductance were relatively uniform. Exceptions to general water quality patterns were observed in three lakes. Allen Lake had a specific conductance value of 58 Microsiemens/cm. The lake of the Golfen group was anaerobic at the bottom and had relatively high concentrations of dissolved organic carbon and dissolved metals, and a lower light transmission than the other lakes studied. One of the unnamed lakes had relatively high concentrations of phytoplankton and dissolved organic carbon and relatively low levels of light transmission. Comparisons of lake data to acid-sensitivity thresholds for specific conductance and alkalinity indicated that all of the lakes except Allen would be sensitive to acidic precipitation. The small sizes of the lakes, and their locations in basins of high precipitation and weathering-resistant rock types, enhance their sensitivity. None of the lakes in this study appeared to be presently acidified.

  6. Seasonal thermal ecology of adult walleye (Sander vitreus) in Lake Huron and Lake Erie.

    PubMed

    Peat, Tyler B; Hayden, Todd A; Gutowsky, Lee F G; Vandergoot, Christopher S; Fielder, David G; Madenjian, Charles P; Murchie, Karen J; Dettmers, John M; Krueger, Charles C; Cooke, Steven J

    2015-10-01

    The purpose of this study was to characterize thermal patterns and generate occupancy models for adult walleye from lakes Erie and Huron with internally implanted biologgers coupled with a telemetry study to assess the effects of sex, fish size, diel periods, and lake. Sex, size, and diel periods had no effect on thermal occupancy of adult walleye in either lake. Thermal occupancy differed between lakes and seasons. Walleye from Lake Erie generally experienced higher temperatures throughout the spring and summer months than did walleye in Lake Huron, due to limnological differences between the lakes. Tagged walleye that remained in Saginaw Bay, Lake Huron (i.e., adjacent to the release location), as opposed to those migrating to the main basin of Lake Huron, experienced higher temperatures, and thus accumulated more thermal units (the amount of temperature units amassed over time) throughout the year. Walleye that migrated toward the southern end of Lake Huron occupied higher temperatures than those that moved toward the north. Consequently, walleye that emigrated from Saginaw Bay experienced thermal environments that were more favorable for growth as they spent more time within their thermal optimas than those that remained in Saginaw Bay. Results presented in this paper provide information on the thermal experience of wild fish in a large lake, and could be used to refine sex- and lake-specific bioenergetics models of walleye in the Great Lakes to enable the testing of ecological hypotheses. PMID:26590461

  7. Fat content of the flesh of siscowets and lake trout from Lake Superior

    USGS Publications Warehouse

    Eschmeyer, Paul H.; Phillips, Arthur M., Jr.

    1965-01-01

    Samples of flesh were excised from the middorsal region of 67 siscowets (Salvelinus namaycush siscowet) and 46 lake trout (Salvelinus n. namaycush) collected from Lake Superior. Chemical analysis of the samples revealed a range in fat content (dry weight) of 32.5 to 88.8 per cent in siscowets and 6.6 to 52.3 per cent in lake trout. Percentage fat increased progressively with increase in length of fish in both forms, but the average rate of increase was far greater for siscowets than for lake trout at lengths between 12 and 20 inches. Despite substantial individual variation, the percentage fat in the two forms was widely different and without overlap at all comparable lengths. The range in iodine number of the fat was 100 to 160 for siscowets and 103 to 161 for lake trout; average values were generally lower for siscowets than for lake trout among fish of comparable length. Percentage fat and relative weight were not correlated significantly in either subspecies. The fat content of flesh samples from a distinctive subpopulation of Lake Superior lake trout known as 'humpers' was more closely similar to that of typical lean lake trout than to siscowets, but the rate of increase in fat with increasing length was greater than for lean lake trout. Flesh samples from hatchery-reared stocks of lake trout, hybrid lake trout X siscowets, and siscowets tended to support the view that the wide difference in fat content between siscowets and lake trout is genetically determined.

  8. Eutrophication of Typical Chinese Shallow Lakes as affected by Hydrologic Characteristics and Lake-Basin Morphology

    NASA Astrophysics Data System (ADS)

    Huang, J.; Xu, Q.; Xi, B.; Wang, X.; Li, W.; Ji, D.; Jiang, T.

    2013-12-01

    The region below midstream of the Yangtze River is one of the areas in China that have a highest density of lakes, in particular shallow lakes. It has five nationally well-known freshwater lakes with largest sizes, namely the Poyang Lake, Doingting Lake, Taihu Lake, Chaohu Lake, and Hongze Lake. This region has 138 lakes with a water surface area of 10 km2 or larger. However, approximately 70% of the large- to medium-sized lakes in the eastern plains of China have been altered from pristine into reservoir-like conditions. Previous studies indicate that hydrologic characteristics and lake-basin morphology likely have important effects on the water quality (or eutrophication) of shallow lakes. However, little is known about quantitative relations among lake water quality, lake-basin morphology, and hydrologic characteristics. The objective of this study was to determine such quantitative relations using data on water quality, water ecology, hydrology, and basin morphology. The data were collected from 2008 to 2011 for ninety shallow lakes in the eastern plains of China. The results indicate that total nitrogen (TN), total phosphorus (TP), chlorophyll-a (Chl-a) concentrations decreased with increase of water depth. TN and TP concentrations in the lakes with a water depth of greater than 2m were less than those in the lakes with a water depth less than 2m. In addition, Chl-a concentration in the lakes with a surface area less than 25 km2 increased with the increase of relative water depth (Zr), whereas Chl-a concentration in the lakes with a surface area greater than 25 km2 decreased with the increase of Zr. Further, as influenced by hydrologic characteristics, the lakes in the upper reaches of the Yangtze River tended to have a better water quality than the lakes in the lower reaches, while the lakes that are hydraulically connected with the Yangtze River tended to have a better water quality than the lakes that are hydraulically disconnected from the river.

  9. Genetic structure of lake whitefish (Coregonus clupeaformis) in Lake Michigan

    USGS Publications Warehouse

    VanDeHey, J.A.; Sloss, Brian L.; Peeters, Paul J.; Sutton, T.M.

    2009-01-01

    Genetic relationships among lake whitefish (Coregonus clupeaformis) spawning aggregates in Lake Michigan were assessed and used to predict a stock or management unit (MU) model for the resource. We hypothesized that distinct spawning aggregates represented potential MUs and that differences at molecular markers underlie population differentiation. Genetic stock identification using 11 microsatellite loci indicated the presence of six genetic MUs. Resolved MUs corresponded to geographically proximate spawning aggregates clustering into genetic groups. Within MUs, analyses suggested that all but one delineated MU was a stable grouping (i.e., no between-population differences), with the exception being the Hog Island - Traverse Bay grouping. Elk Rapids was the most genetically divergent population within Lake Michigan. However, low F st values suggested that moderate to high levels of gene flow occur or have occurred in the past between MUs. Significant tests of isolation by distance and low pairwise Fst values potentially led to conflicting results between traditional analyses and a Bayesian approach. This data set could provide baseline data from which a comprehensive mixed-stock analysis could be performed, allowing for more efficient and effective management of this economically and socially important resource.

  10. 78 FR 60686 - Establishment of the Big Valley District-Lake County and Kelsey Bench-Lake County Viticultural...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-02

    ... on April 5, 2013 (78 FR 20544), proposing to establish the Big Valley District-Lake County and Kelsey... District-Lake County and Kelsey Bench-Lake County Viticultural Areas and Modification of the Red Hills Lake... approximately 11,000-acre ``Big Valley District-Lake County'' viticultural area and the approximately...

  11. Geological nature of subglacial Lake Vostok

    NASA Astrophysics Data System (ADS)

    Leitchenkov, G. L.; Masolov, V. N.; Lukin, V. V.; Bulat, S. A.; Kurinin, R. G.; Lipenkov, V. Ya.

    2003-04-01

    Lake Vostok is located at the edge of vast upland of East Antarctic (Precambrian) Crystalline Shield and represents a typical extensionally-induced intracontinental rift zone. Type indicators of rift nature are: width (60-80 km) and length (about 300 km) of the lake depression; several (3-5) kilometers of sediments (modeled from gravity data) infilling the lake graben, considerable amplitudes of faults bounding the lake (up to 2 km in bedrock relief and in excess of 5 km in basement topography), half-graben-like structures (rotated crustal blocks) at flanks of the lake traceable to crustal extension; along-strike segmentation of the depression (the presence of two isolated basins, recognized from seismic and gravity data); knee-shaped spatial configuration of the lake and existence of diagonal fractures (displayed in bedrock topography) normally nascent in conditions of tensional stress. The rift graben of Lake Vostok is considered to be a part (branch) of more spacious rift system, main arm of which stretched from the Prydz Bay trough the Lambert Glacier and the eastern foot of Gamburtsev Mts. to, at least, 110E. This rift system is a result of large-scale extensional event, which occurred in East Antarctica in Late Jurassic - Early Cretaceous prior to East Gondwana break-up. Sedimentary infill of this age is proposed to dominate in Vostok Lake, although postrift, preglacial (Cretaceous - Paleogene) strata can also forms significant part of depositional section. Helium isotopes data give evidence that the Lake Vostok rift is not active. On the other hand, thermophilic bacteria found in accretion ice suggest the possibility of hydrothermal activity in lake bottom. The conduits for warm underwater can be provided by deep crustal faults bordering rift graben. Microseismicity recorded in the area of Lake Vostok suggests the possibility of crustal deformations (likely during more dramatic earthquakes) providing a necessary fault permeability for water seepage from

  12. Expanding models of lake trophic state to predict cyanobacteria in lakes

    EPA Science Inventory

    Background/Question/Methods: Cyanobacteria are a primary taxonomic group associated with harmful algal blooms in lakes. Understanding the drivers of cyanobacteria presence has important implications for lake management and for the protection of human and ecosystem health. Chlor...

  13. Helminths in an intensively stocked population of lake trout, Salvelinus namaycush, from Lake Huron

    USGS Publications Warehouse

    Muzzall, Patrick M.; Bowen, Charles A., II

    2000-01-01

    Eighty stocked lake trout Salvelinus namaycush (Salmonidae), collected from 2 locations in Lake Huron in May 1995, were examined for parasites. The parasite fauna of this top predator in Lake Huron was characterized by only 6 helminth species. Echinorhynchus salmonis infected all lake trout with a mean intensity of 163.9. The intensity of this acanthocephalan species significantly increased with host length and weight. Eubothrium salvelini infected 78 lake trout with a maximum number of 81 scoleces counted. Diplostomum sp., Cyathocephalus truncatus, Capillaria salvelini, and Neoechinorhynchus sp. infrequently infected lake trout. The low parasite species richness in these lake trout is believed to be due to their large size at stocking and to the loss of historical enzootic host-parasite relationships that followed the absence of this fish species in Lake Huron for 26 yr.

  14. HYDROGEOMORPHIC PATTERNS IN COASTAL WETLANDS OF LAKE SUPERIOR: RELATIVE ROLE OF LAKE AND TRIBUTARY

    EPA Science Inventory

    Despite the documented importance of hydrodynamics in influencing the structure and fundtion of Great Lakes coastal wetlands, systematic assessments of the hydrology of coastal wetlands are lacking. This paper addresses this gap by describing patterns in lake and tributary inputs...

  15. Record of glacial Lake Missoula floods in glacial Lake Columbia, Washington

    NASA Astrophysics Data System (ADS)

    Hanson, Michelle A.; Clague, John J.

    2016-02-01

    During the last glaciation (marine oxygen isotope stage 2), outburst floods from glacial Lake Missoula deposited diagnostic sediments within glacial Lake Columbia. Two dominant outburst flood lithofacies are present within glacial Lake Columbia deposits: a flood expansion bar facies and a finer-grained hyperpycnite facies. We conclude that the flood sediments have a glacial Lake Missoula source because: (1) current indicators indicate westward flow through the lake, and upvalley flow followed by downvalley flow in tributary valleys; (2) no flood sediments are found north of a certain point; (3) there is a dominance of Belt-Purcell Supergroup clasts in a flood expansion bar; and (4) some of the finer-grained beds have a pink colour, reflective of glacial Lake Missoula lake-bottom sediments. A new radiocarbon age of 13,400 ± 100 14C BP on plant detritus found below 37 flood beds helps constrain the timing of outburst flooding from glacial Lake Missoula.

  16. Expanding Models of Lake Trophic State to Predict Cyanobacteria in Lakes: A Data Mining Approach

    EPA Science Inventory

    Background/Question/Methods: Cyanobacteria are a primary taxonomic group associated with harmful algal blooms in lakes. Understanding the drivers of cyanobacteria presence has important implications for lake management and for the protection of human and ecosystem health. Chloro...

  17. Lake trout spawning habitat in the Six Fathom Bank-Yankee Reef lake trout sanctuary, Lake Huron

    USGS Publications Warehouse

    Edsall, Thomas A.; Brown, Charles L.; Kennedy, Gregory W.; Poe, Thomas P.

    1992-01-01

    Attempts to reestablish self-sustaining stocks of lake trout (Salvelinus namaycush) in the lower four Great Lakes, where the species was extinguished in the 1950s and 1960s, have been largely unsuccessful. To avoid many of the problems believed to be contributing to this failure, the fishery management community recently established several sanctuaries in the offshore waters of the Great Lakes where the development and protection of self-sustaining stocks of lake trout would be a primary management objective. One of these, the Six Fathom Bank-Yankee Reef sanctuary, was created in the south-central portion of Lake Huron. This sanctuary covers 168,000 ha and includes the shallower portions of the Six Fathom and Ipperwash scarps, which are major bathymetric features in the southern half of the lake. Historical accounts describe Six Fathom Bank as the most important lake trout spawning ground in the lake. Here we present the results of lake bed surveys conducted in the sanctuary with side-scan sonar, underwater videocamera systems, and a small research submarine. Our observations of the lake bed are consistent with what is known of the bedrock stratigraphy, glacial history, and karst geomorphology of the Lake Huron basin. Most of the loose rock we found seemed to be derived from local carbonate bedrock formations, although non-carbonate rock probably from Precambrian sources to the north was also present in some areas. Much of the bedrock and loose rock displayed karst solution features described for the Bruce Peninsula on the Ontario shoreline. Our surveys revealed substantial areas of lake bed at water depths of 20–36 m that resembled suitable spawning and fry production habitat for the shallow-water strains of lake trout that are the focus of the rehabilitation effort. Low mid-lake nutrient levels documented recently by others and the extremely high abundance of Mysis relicta (an important item in the diet of young lake trout) that we documented on Yankee Reef

  18. Great Lakes Steel -- PCI facility

    SciTech Connect

    Eichinger, F.T.; Dake, S.H.; Wagner, E.D.; Brown, G.S.

    1997-12-31

    This paper discusses the planning, design, and start-up of the 90 tph PCI facility for National Steel`s Great Lakes Steel Division in River Rouge, MI. This project is owned and operated by Edison Energy Services, and was implemented on a fast-track basis by Raytheon Engineers and Constructors, Babcock Material Handling, and Babcock and Wilcox. This paper presents important process issues, basic design criteria, an the challenges of engineering and building a state-of-the-art PCI facility in two existing plants. Pulverized coal is prepared at the River Rouge Power Plant of Detroit Edison, is pneumatically conveyed 6,000 feet to a storage silo at Great Lakes Steel, and is injected into three blast furnaces.

  19. Water quality in Lake Lanier

    SciTech Connect

    Callaham, M.A. )

    1991-04-01

    Thirteen water quality tests measuring five categories of pollution were conducted twice monthly from May, 1987 to April, 1990 at eight locations on Lake Sidney Lanier to establish baseline data and detect trends. Additionally, sediment and water samples were analyzed for ten toxic metals. Sampling stations were located at or near the point of entry of streams into the Lake. Oxygen demanding pollutants were highest in urban streams and phosphorus and nitrogen concentrations were highest in streams having poultry processing operations within their watersheds. Indicators of siltation increased coincidentally with highway construction in one watershed. Fecal coliform bacteria counts decreased at Flat Creek and increased in the Chattahoochee River. Zinc and copper occurred in water samples at levels of detectability. Sediment samples from several locations contained metal concentrations which warrant further study.

  20. Hydrologic description of Lake Jackson, Sebring, Florida

    USGS Publications Warehouse

    Hammett, K.M.

    1981-01-01

    Available data were evaluated to document hydrologic conditions in the Lake Jackson basin, Florida. Bathymetric data indicate numerous dredged holes around the perimeter of the lake. Away from the dredged holes, a firm sand bottom slopes gradually from the shore to a maximum depth of 22 feet. Lake Jackson 's stage declined 3 feet from 1970 to 1973 and has remained below normal since that time. Rainfall was below average from 1970 to 1973, but the lake-level decline did not result solely from deficient precipitation. A water-budget analysis of the lake indicates that channelization downstream and groundwater withdrawals contributed significantly to the decline. Lake Jackson is used extensively for recreation. Available water-quality data indicate suitable conditions for recreation and the propagation and management of fish and wildlife. (USGS)

  1. A blood chemistry profile for lake trout

    USGS Publications Warehouse

    Edsall, Carol Cotant

    1999-01-01

    A blood chemistry profile for lake trout Salvelinus namaycush was developed by establishing baseline ranges for several clinical chemistry tests (glucose, total protein, amylase, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, creatine kinase, calcium, and magnesium). Measurements were made accurately and rapidly with a Kodak Ektachem DT60 Analyzer and the Ektachem DTSC Module. Blood serum was collected from both laboratory-reared lake trout (1978 and 1986 year-classes) and feral spawning trout from Lake Michigan and then analyzed in the laboratory. No clinically significant differences were found between samples analyzed fresh and those frozen for 1 or 6 weeks. The ranges in chemistry variables for feral lake trout were generally wider than those for laboratory-reared lake trout, and significant differences existed between male and female feral lake trout for several tests. Blood chemistry profiles also varied seasonally on fish sampled repeatedly.

  2. Monitoring and Modelling Lakes and Coastal Environments

    NASA Astrophysics Data System (ADS)

    Odada, Eric

    2009-01-01

    The monitoring and modeling of lakes and coastal environments is becoming ever more important, particularly because these environments bear heavy loads in terms of human population, and their resources are critical to the livelihoods and well-being of coastal inhabitants and ecosystems. Monitoring and Modelling Lakes and Coastal Environments is a collection of 18 papers arising from the Lake 2004 International Conference on Conservation, Restoration and Management of Lakes and Coastal Wetlands, held in Bhubaneswar, Orissa, India, 9-13 December 2004. Consequently, 15 of the papers are concerned with studies on the Indian subcontinent, and many of the papers focus on India's Lake Chilika, the site of a special session during the conference. Two papers concern Japan, and one focuses on North America's Great Lakes region. Although the book has a regional bias, the replication of best practices that can be drawn from these studies may be useful for an international audience.

  3. Greenland subglacial lakes detected by radar

    NASA Astrophysics Data System (ADS)

    Palmer, Steven J.; Dowdeswell, Julian A.; Christoffersen, Poul; Young, Duncan A.; Blankenship, Donald D.; Greenbaum, Jamin S.; Benham, Toby; Bamber, Jonathan; Siegert, Martin J.

    2013-12-01

    lakes are an established and important component of the basal hydrological system of the Antarctic ice sheets, but none have been reported from Greenland. Here we present airborne radio echo sounder (RES) measurements that provide the first clear evidence for the existence of subglacial lakes in Greenland. Two lakes, with areas ~8 and ~10 km2, are found in the northwest sector of the ice sheet, ~40 km from the ice margin, and below 757 and 809 m of ice, respectively. The setting of the Greenland lakes differs from those of Antarctic subglacial lakes, being beneath relatively thin and cold ice, pointing to a fundamental difference in their nature and genesis. Possibilities that the lakes consist of either ancient saline water in a closed system or are part of a fresh, modern open hydrological system are discussed, with the latter interpretation considered more likely.

  4. Top consumer abundance influences lake methane efflux

    PubMed Central

    Devlin, Shawn P.; Saarenheimo, Jatta; Syväranta, Jari; Jones, Roger I.

    2015-01-01

    Lakes are important habitats for biogeochemical cycling of carbon. The organization and structure of aquatic communities influences the biogeochemical interactions between lakes and the atmosphere. Understanding how trophic structure regulates ecosystem functions and influences greenhouse gas efflux from lakes is critical to understanding global carbon cycling and climate change. With a whole-lake experiment in which a previously fishless lake was divided into two treatment basins where fish abundance was manipulated, we show how a trophic cascade from fish to microbes affects methane efflux to the atmosphere. Here, fish exert high grazing pressure and remove nearly all zooplankton. This reduction in zooplankton density increases the abundance of methanotrophic bacteria, which in turn reduce CH4 efflux rates by roughly 10 times. Given that globally there are millions of lakes emitting methane, an important greenhouse gas, our findings that aquatic trophic interactions significantly influence the biogeochemical cycle of methane has important implications. PMID:26531291

  5. Top consumer abundance influences lake methane efflux.

    PubMed

    Devlin, Shawn P; Saarenheimo, Jatta; Syväranta, Jari; Jones, Roger I

    2015-01-01

    Lakes are important habitats for biogeochemical cycling of carbon. The organization and structure of aquatic communities influences the biogeochemical interactions between lakes and the atmosphere. Understanding how trophic structure regulates ecosystem functions and influences greenhouse gas efflux from lakes is critical to understanding global carbon cycling and climate change. With a whole-lake experiment in which a previously fishless lake was divided into two treatment basins where fish abundance was manipulated, we show how a trophic cascade from fish to microbes affects methane efflux to the atmosphere. Here, fish exert high grazing pressure and remove nearly all zooplankton. This reduction in zooplankton density increases the abundance of methanotrophic bacteria, which in turn reduce CH4 efflux rates by roughly 10 times. Given that globally there are millions of lakes emitting methane, an important greenhouse gas, our findings that aquatic trophic interactions significantly influence the biogeochemical cycle of methane has important implications. PMID:26531291

  6. Comparative hatching success of lake trout eggs in Lake Michigan water and well water

    USGS Publications Warehouse

    Edsall, Carol C.; Mac, Michael J.

    1982-01-01

    A study was undertaken to examine the influence of water from southern Lake Michigan on the survival of lake trout (Salvelinus namaycush) eggs by comparing the hatching success of eggs from the same source incubated in water from Lake Michigan, or from the laboratory well. It is concluded that the observed differences in hatching are probably attributable to chemical constituents of water from the lake (eg, chlorinated hydrocarbons, metals and other industrial and agricultural chemicals).

  7. Assessment of lake trout spawning habitat quality in central Lake Huron by submarine

    USGS Publications Warehouse

    Manny, Bruce A.; Edsall, Thomas A.

    1989-01-01

    Interstitial water quality was measured using a submersible at seven locations on Six Fathom Bank. Historically, the bank was an important lake trout spawning ground. It is currently the focus of coordinated, interagency efforts to rehabilitate lake trout in Lake Huron. Water quality, evaluated from measurements of biochemical oxygen demand, dissolved oxygen, ammonia, and hydrogen sulfide among the rocks, would not prevent lake trout eggs from hatching successfully on the bank.

  8. Physical drivers of lake evaporation across a gradient of climate and lake types

    NASA Astrophysics Data System (ADS)

    Lenters, J. D.; Blanken, P.; Healey, N. C.; Hinkel, K. M.; Ong, J.; Peake, C.; Potter, B. L.; Riveros-Iregui, D. A.; Spence, C.; Van Cleave, K.; Zlotnik, V. A.

    2014-12-01

    Inland waters exchange sensible and latent heat with the overlying atmosphere in ways that are very different from the surrounding terrestrial landscape. Depending on the regional climate and lake characteristics, open-water evaporation from lakes can vary out of phase with terrestrial evapotranspiration within the watershed, and key atmospheric drivers are often different as well. Lake evaporation is a complex process that interacts with many aspects of a lake ecosystem, including water temperature, vertical mixing, lake chemistry, stratification, ice cover, and water levels. Although driven primarily by vapor pressure gradient and wind speed, evaporation is also an energy-consuming process. This leads not only to significant roles from net radiation, sensible heat flux, and other components of the surface energy budget, but it also results in important feedbacks on lake temperature, ice cover, and other evaporation-mediating processes. As such, defining the climatic variables that "drive" lake evaporation is far from straightforward and often depends on timescale, lake depth, and characteristics of the regional climate. In this study, we provide some insight into the problem by examining the energy budget of a variety of lakes across a range of climatic gradients and lake types. This includes shallow Arctic lakes, deep temperate lakes, and a hypersaline lake in a semi-arid climate. Our results reveal a wide range of evaporative response to climatic forcing, including some lakes that show counterintuitive effects or even opposite responses to those of other lakes. Although process-based, mechanistic models should be able to account for such complexities, these findings highlight the need for caution when interpreting climatic drivers of lake evaporation. It is not likely, for example, that models of a solely empirical or statistical nature would be sufficient to fully capture the physics and dynamics of evaporation, particularly in an ever-changing climate.

  9. Carbon cycling in Lake Superior

    NASA Astrophysics Data System (ADS)

    Urban, N. R.; Auer, M. T.; Green, S. A.; Lu, X.; Apul, D. S.; Powell, K. D.; Bub, L.

    2005-06-01

    Carbon (C) cycling in Lake Superior was studied within the Keweenaw Interdisciplinary Transport Experiment in Superior (KITES) project to assess (1) whether the lake is net heterotrophic, (2) sources, sinks and residence time for dissolved organic carbon (DOC), (3) importance of terrigenous organic C subsidies, and (4) factors limiting C flow through bacteria. During 3 years of fieldwork, measurements were made of spatial and temporal distributions of C pools and rates of photosynthesis, community respiration, and bacterial production. Measurements were made of the composition of dissolved organic matter (DOM), rates of DOM photolysis, lability of DOM toward microbial consumption, and river inputs of DOM. All measurements suggest the lake is net heterotrophic. The C:N ratios of DOM suggest that it is primarily of terrigenous origin, but other characteristics (size distribution, UV absorption) point to the presence of autochthonous DOM and to alteration of terrigenous material. The lake mass balance indicates that the residence time (˜8 years) of the DOC pool (17 Tg) is short relative to the hydrologic residence time (170 years). The known flux of terrigenous DOC (˜1 Tg/yr) is too low to support annual bacterial carbon demand (6-38 Tg/yr), but microbial respiration is the major sink for terrigenous DOC. A rapidly cycling, autochthonous DOC pool must exist. Microbial activity was correlated with temperature, phosphorus availability, and DOC concentration but not with photosynthesis rates. Measurements of respiration (˜40 Tg/yr), photosynthesis (2-7 Tg/yr), and bacterial production (0.5-2 Tg/yr) are not all mutually compatible and result in a discrepancy in the organic carbon budget.

  10. CLEAR LAKE BASIN 2000 PROJECT

    SciTech Connect

    LAKE COUNTY SANITATION DISTRICT

    2003-03-31

    The following is a final report for the Clear Lake Basin 2000 project. All of the major project construction work was complete and this phase generally included final details and testing. Most of the work was electrical. Erosion control activities were underway to prepare for the rainy season. System testing including pump stations, electrical and computer control systems was conducted. Most of the project focus from November onward was completing punch list items.

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. View of upstream face of Lake Sabrina Dam showing the ...

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

    View of upstream face of Lake Sabrina Dam showing the redwood planks and base of dam from Lake Sabrina Basin, view north - Bishop Creek Hydroelectric System, Plant 2, Lake Sabrina Dam, Bishop Creek, Bishop, Inyo County, CA

  18. View of upstream face of Lake Sabrina Dam showing redwood ...

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

    View of upstream face of Lake Sabrina Dam showing redwood planks and boulders in Lake Sabrina Basin, view north - Bishop Creek Hydroelectric System, Plant 2, Lake Sabrina Dam, Bishop Creek, Bishop, Inyo County, CA

  19. BIOLOGICAL INDICATOR DEVELOPMENT AND CLASSIFICATION FOR GREAT LAKES COASTAL WETLANDS

    EPA Science Inventory

    Great Lakes coastal wetlands are a valued aquatic resource that provide important ecological functions for the Great Lakes including serving as fish habitat, aquatic food web support, and nutrient and sediment retention from watersheds. Great Lakes resource managers need assessme...

  20. 40 CFR 35.1630 - State lake classification surveys.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Freshwater Lakes § 35.1630 State lake classification surveys. States that wish to participate in the clean... trophic condition, of their publicly owned freshwater lakes that are in need of restoration or...