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Sample records for aecl chalk river

  1. Radiochemistry Lab Decommissioning and Dismantlement. AECL, Chalk River Labs, Ontario, Canada

    SciTech Connect

    Kenny, Stephen

    2008-01-15

    Atomic Energy of Canada (AECL) was originally founded in the mid 1940's to perform research in radiation and nuclear areas under the Canadian Defense Department. In the mid 50's The Canadian government embarked on several research and development programs for the development of the Candu Reactor. AECL was initially built as a temporary site and is now faced with many redundant buildings. Prior to 2004 small amounts of Decommissioning work was in progress. Many reasons for deferring decommissioning activities were used with the predominant ones being: 1. Reduction in radiation doses to workers during the final dismantlement, 2. Development of a long-term solution for the management of radioactive wastes in Canada, 3. Financial constraints presented by the number of facilities shutdown that would require decommissioning funds and the absence of an approved funding strategy. This has led to the development of a comprehensive decommissioning plan that is all inclusive of AECL's current and legacy liabilities. Canada does not have a long-term disposal site; therefore waste minimization becomes the driving factor behind decontamination for decommissioning before and during dismantlement. This decommissioning job was a great learning experience for decommissioning and the associated contractors who worked on this project. Throughout the life of the project there was a constant focus on waste minimization. This focus was constantly in conflict with regulatory compliance primarily with respect to fire regulations and protecting the facility along with adjacent facilities during the decommissioning activities. Discrepancies in historical documents forced the project to treat every space as a contaminated space until proven differently. Decommissioning and dismantlement within an operating site adds to the complexity of the tasks especially when it is being conducted in the heart of the plant. This project was very successful with no lost time accidents in over one hundred

  2. Widespread methanotrophic primary production in lowland chalk rivers.

    PubMed

    Shelley, Felicity; Grey, Jonathan; Trimmer, Mark

    2014-05-22

    Methane is oversaturated relative to the atmosphere in many rivers, yet its cycling and fate is poorly understood. While photosynthesis is the dominant source of autotrophic carbon to rivers, chemosynthesis and particularly methane oxidation could provide alternative sources of primary production where the riverbed is heavily shaded or at depth beneath the sediment surface. Here, we highlight geographically widespread methanotrophic carbon fixation within the gravel riverbeds of over 30 chalk rivers. In 15 of these, the potential for methane oxidation (methanotrophy) was also compared with photosynthesis. In addition, we performed detailed concurrent measurements of photosynthesis and methanotrophy in one large chalk river over a complete annual cycle, where we found methanotrophy to be active to at least 15 cm into the riverbed and to be strongly substrate limited. The seasonal trend in methanotrophic activity reflected that of the riverine methane concentrations, and thus the highest rates were measured in mid-summer. At the sediment surface, photosynthesis was limited by light for most of the year with heavy shading induced by dense beds of aquatic macrophytes. Across 15 rivers, in late summer, we conservatively calculated that net methanotrophy was equivalent to between 1% and 46% of benthic net photosynthetic production within the gravel riverbed, with a median value of 4%. Hence, riverbed chemosynthesis, coupled to the oxidation of methane, is widespread and significant in English chalk rivers. PMID:24695425

  3. Widespread methanotrophic primary production in lowland chalk rivers

    PubMed Central

    Shelley, Felicity; Grey, Jonathan; Trimmer, Mark

    2014-01-01

    Methane is oversaturated relative to the atmosphere in many rivers, yet its cycling and fate is poorly understood. While photosynthesis is the dominant source of autotrophic carbon to rivers, chemosynthesis and particularly methane oxidation could provide alternative sources of primary production where the riverbed is heavily shaded or at depth beneath the sediment surface. Here, we highlight geographically widespread methanotrophic carbon fixation within the gravel riverbeds of over 30 chalk rivers. In 15 of these, the potential for methane oxidation (methanotrophy) was also compared with photosynthesis. In addition, we performed detailed concurrent measurements of photosynthesis and methanotrophy in one large chalk river over a complete annual cycle, where we found methanotrophy to be active to at least 15 cm into the riverbed and to be strongly substrate limited. The seasonal trend in methanotrophic activity reflected that of the riverine methane concentrations, and thus the highest rates were measured in mid-summer. At the sediment surface, photosynthesis was limited by light for most of the year with heavy shading induced by dense beds of aquatic macrophytes. Across 15 rivers, in late summer, we conservatively calculated that net methanotrophy was equivalent to between 1% and 46% of benthic net photosynthetic production within the gravel riverbed, with a median value of 4%. Hence, riverbed chemosynthesis, coupled to the oxidation of methane, is widespread and significant in English chalk rivers. PMID:24695425

  4. Spatial analysis of Carbon-14 dynamics in a wetland ecosystem (Duke Swamp, Chalk River Laboratories, Canada).

    PubMed

    Yankovich, T L; King-Sharp, K J; Carr, J; Robertson, E; Killey, R W D; Beresford, N A; Wood, M D

    2014-11-01

    A detailed survey was conducted to quantify the spatial distribution of (14)C in Sphagnum moss and underlying soil collected in Duke Swamp. This wetland environment receives (14)C via groundwater pathways from a historic radioactive Waste Management Area (WMA) on Atomic Energy Canada Limited (AECL)'s Chalk River Laboratories (CRL) site. Trends in (14)C specific activities were evaluated with distance from the sampling location with the maximum (14)C specific activity (DSS-35), which was situated adjacent to the WMA and close to an area of groundwater discharge. Based on a spatial evaluation of the data, an east-to-west (14)C gradient was found, due to the influence of the WMA on (14)C specific activities in the swamp. In addition, it was possible to identify two groups of sites, each showing significant exponential declines with distance from the groundwater source area. One of the groups showed relatively more elevated (14)C specific activities at a given distance from source, likely due to their proximity to the WMA, the location of the sub-surface plume originating from the WMA, the presence of marsh and swamp habitat types, which facilitated (14)C transport to the atmosphere, and possibly, (14)C air dispersion patterns along the eastern edge of the swamp. The other group, which had lower (14)C specific activities at a given distance from the groundwater source area, included locations that were more distant from the WMA and the sub-surface plume, and contained fen habitat, which is known to act as barrier to groundwater flow. The findings suggest that proximity to source, groundwater flow patterns and habitat physical characteristics can play an important role in the dynamics of (14)C being carried by discharging groundwater into terrestrial and wetland environments. PMID:25086321

  5. Fifty years of accelerator based physics at Chalk River

    SciTech Connect

    McKay, John W.

    1999-04-26

    The Chalk River Laboratories of Atomic Energy of Canada Ltd. was a major centre for Accelerator based physics for the last fifty years. As early as 1946, nuclear structure studies were started on Cockroft-Walton accelerators. A series of accelerators followed, including the world's first Tandem, and the MP Tandem, Superconducting Cyclotron (TASCC) facility that was opened in 1986. The nuclear physics program was shut down in 1996. This paper will describe some of the highlights of the accelerators and the research of the laboratory.

  6. Isotope hydrology of the Chalk River Laboratories site, Ontario, Canada

    USGS Publications Warehouse

    Peterman, Zell; Neymark, Leonid; King-Sharp, K.J.; Gascoyne, Mel

    2016-01-01

    This paper presents results of hydrochemical and isotopic analyses of groundwater (fracture water) and porewater, and physical property and water content measurements of bedrock core at the Chalk River Laboratories (CRL) site in Ontario. Density and water contents were determined and water-loss porosity values were calculated for core samples. Average and standard deviations of density and water-loss porosity of 50 core samples from four boreholes are 2.73 ± 12 g/cc and 1.32 ± 1.24 percent. Respective median values are 2.68 and 0.83 indicating a positive skewness in the distributions. Groundwater samples from four deep boreholes were analyzed for strontium (87Sr/86Sr) and uranium (234U/238U) isotope ratios. Oxygen and hydrogen isotope analyses and selected solute concentrations determined by CRL are included for comparison. Groundwater from borehole CRG-1 in a zone between approximately +60 and −240 m elevation is relatively depleted in δ18O and δ2H perhaps reflecting a slug of water recharged during colder climatic conditions. Porewater was extracted from core samples by centrifugation and analyzed for major dissolved ions and for strontium and uranium isotopes. On average, the extracted water contains 15 times larger concentration of solutes than the groundwater. 234U/238U and correlation of 87Sr/86Sr with Rb/Sr values indicate that the porewater may be substantially older than the groundwater. Results of this study show that the Precambrian gneisses at Chalk River are similar in physical properties and hydrochemical aspects to crystalline rocks being considered for the construction of nuclear waste repositories in other regions.

  7. Development of an Integrated Waste Plan for Chalk River Laboratories - 13376

    SciTech Connect

    Jones, L.

    2013-07-01

    To further its Strategic Planning, the Atomic Energy of Canada Limited (AECL) required an effective approach to developing a fully integrated waste plan for its Chalk River Laboratories (CRL) site. Production of the first Integrated Waste Plan (IWP) for Chalk River was a substantial task involving representatives from each of the major internal stakeholders. Since then, a second revision has been produced and a third is underway. The IWP remains an Interim IWP until all gaps have been resolved and all pathways are at an acceptable level of detail. Full completion will involve a number of iterations, typically annually for up to six years. The end result of completing this process is a comprehensive document and supporting information that includes: - An Integrated Waste Plan document summarizing the entire waste management picture in one place; - Details of all the wastes required to be managed, including volume and timings by waste stream; - Detailed waste stream pathway maps for the whole life-cycle for each waste stream to be managed from pre-generation planning through to final disposition; and - Critical decision points, i.e. decisions that need to be made and timings by when they need to be made. A waste inventory has been constructed that serves as the master reference inventory of all waste that has been or is committed to be managed at CRL. In the past, only the waste that is in storage has been effectively captured, and future predictions of wastes requiring to be managed were not available in one place. The IWP has also provided a detailed baseline plan at the current level of refinement. Waste flow maps for all identified waste streams, for the full waste life cycle complete to disposition have been constructed. The maps identify areas requiring further development, and show the complexities and inter-relationships between waste streams. Knowledge of these inter-dependencies is necessary in order to perform effective options studies for enabling

  8. Progress in radiocarbon dating with the Chalk River MP tandem accelerator

    SciTech Connect

    Andrews, H.R.; Ball, G.C.; Brown, R.M.; Davies, W.G.; Imahori, Y.; Milton, J.C.D.

    1980-01-01

    The evolution of a tandem accelerator /sup 14/C dating system at Chalk River is recounted. Background problems and sources of instability are discussed and solutions are described. Details of sample chemistry and source preparation are presented.

  9. Development of Molten Corium Using An Exothermic Chemical Reaction for the Molten- Fuel Moderator-Interaction Studies at Chalk River Laboratories

    SciTech Connect

    Nitheanandan, T.; Sanderson, D.B.; Kyle, G.; Farmer, M.

    2004-07-01

    Atomic Energy of Canada Limited (AECL) has partnered with Argonne National Laboratory to develop a corium thermite prototypical of Candu material and test the concept of ejecting {approx}25 kg of the molten material from a pressure tube with a driving pressure of 10 MPa. This development program has been completed and the technology transferred to AECL. Preparation for the molten-fuel moderator-interaction tests at AECL's Chalk River Laboratories is well underway. A mixture of 0.582 U/0.077 U{sub 3}O{sub 8}/0.151 Zr/0.19 CrO{sub 3} (wt%) as reactant chemicals has been demonstrated to produce a corium consisting of 0.73 UO{sub 2}/0.11 Zr/0.06 ZrO{sub 2}/0.10 Cr (wt%) at {approx}2400 deg. C. This is comparable to the target Candu specific corium of 0.9 UO{sub 2}/0.1 Zr (wt%), with limited oxidation. The peak melt temperature was confirmed from small-scale thermitic reaction tests. Several small-scale tests were completed to qualify the thermite to ensure operational safety and a quantifiable experimental outcome. The proposed molten-fuel moderator-interaction experiments at Chalk River Laboratories will consist of heating the thermite mixture inside a 1.14-m long insulated pressure tube. Once the molten material has reached the desired temperature of {approx}2400 deg. C, the pressure inside the tube will be raised to about 10 MPa, and the pressure tube will fail at a pre-machined flaw, ejecting the molten material into the surrounding tank of water. The test apparatus, instrumentation, data acquisition and control systems have been assembled, and a series of successful commissioning tests have been completed. (authors)

  10. Foil changer for the Chalk River superconducting cyclotron

    SciTech Connect

    Hoffmann, C.R.; Kilborn, R.I.; Mouris, J.E.; Proulx, D.R.; Weaver, J.F.

    1985-10-01

    Capture of an injected beam in the Chalk River superconducting cyclotron requires that a carbon stripping foil be accurately placed in a dee to intercept the incoming beam. Foil radial position must be precisely adjustable and foils must be easily replaced. A foil changing apparatus has been designed, built and tested to meet these requirements. The main components are a supply magazine, a transport system, and unloading and loading mechanisms. The magazine is on top of the cyclotron. It holds 300 foils and can be isolated from machine vacuum for refilling. Each foil is mounted on a stainless steel frame. A stainless steel roller chain fitted with 33 copper sleeves (shrouds) carries foils, one per shroud, down a dee stem to the midplane. A 12-bit absolute optical shaft encoder senses foil position. To replace a foil a shroud is positioned at the top of the cyclotron, a foil is removed, and another is transferred from the magazine to the empty shroud. Three stepping motors and associated electronics provide mechanical drive and are interfaced with a CAMAC control system.

  11. Contaminated groundwater characterization at the Chalk River Laboratories, Ontario, Canada

    SciTech Connect

    Schilk, A.J.; Robertson, D.E.; Thomas, C.W.; Lepel, E.A.; Champ, D.R.; Killey, R.W.D.; Young, J.L.; Cooper, E.L.

    1993-03-01

    The licensing requirements for the disposal of low-level radioactive waste (10 CFR 61) specify the performance objectives and technical requisites for federal and commercial land disposal facilities, the ultimate goal of which is to contain the buried wastes so that the general population is adequately protected from harmful exposure to any released radioactive materials. A major concern in the operation of existing and projected waste disposal sites is subterranean radionuclide transport by saturated or unsaturated flow, which could lead to the contamination of groundwater systems as well as uptake by the surrounding biosphere, thereby directly exposing the general public to such materials. Radionuclide transport in groundwater has been observed at numerous commercial and federal waste disposal sites [including several locations within the waste management area of Chalk River Laboratories (CRL)], yet the physico-chemical processes that lead to such migration are still not completely understood. In an attempt to assist in the characterization of these processes, an intensive study was initiated at CRL to identify and quantify the mobile radionuclide species originating from three separate disposal sites: (a) the Chemical Pit, which has received aqueous wastes containing various radioisotopes, acids, alkalis, complexing agents and salts since 1956, (b) the Reactor Pit, which has received low-level aqueous wastes from a reactor rod storage bay since 1956, and (c) the Waste Management Area C, a thirty-year-old series of trenches that contains contaminated solid wastes from CRL and various regional medical facilities. Water samples were drawn downgradient from each of the above sites and passed through a series of filters and ion-exchange resins to retain any particulate and dissolved or colloidal radionuclide species, which were subsequently identified and quantified via radiochemical separations and gamma spectroscopy. These groundwaters were also analyzed for anions

  12. Evaluation of a commercial system for CAMAC-based control of the Chalk River Laboratories tandem-accelerator-superconducting-cyclotron complexcomplex

    SciTech Connect

    Greiner, B.F.; Caswell, D.J.; Slater, W.R. )

    1992-04-01

    This paper discusses the control system of the Tandem Accelerator Superconducting Cyclotron (TASCC) of AECL Research at its Chalk River Laboratories which is presently based on a PDP-11 computer and the IAS operating system. The estimated expense of a custom conversion of the system to a current, equivalent operating system is prohibitive. The authors have evaluated a commercial control package from VISTA Control Systems based on VAX microcomputers and the VMS operating system. Vsystem offers a modern, graphical operator interface, an extensive software toolkit for configuration of the system and a multi-feature data-logging capability, all of which far surpass the functionality of the present control system. However, the implementation of some familiar, practical features that TASCC operators find to be essential has proven to be challenging. The assessment of Vsystem, which is described in terms of presently perceived strengths and weaknesses, is, on balance, very positive.

  13. Management of Legacy Spent Nuclear Fuel Wastes at the Chalk River Laboratories: The Challenges and Innovative Solutions Implemented - 13301

    SciTech Connect

    Schruder, Kristan; Goodwin, Derek

    2013-07-01

    AECL's Fuel Packaging and Storage (FPS) Project was initiated in 2004 to retrieve, transfer, and stabilize an identified inventory of degraded research reactor fuel that had been emplaced within in-ground 'Tile Hole' structures in Chalk River Laboratories' Waste Management Area in the 1950's and 60's. Ongoing monitoring of the legacy fuel storage conditions had identified that moisture present in the storage structures had contributed to corrosion of both the fuel and the storage containers. This prompted the initiation of the FPS Project which has as its objective to design, construct, and commission equipment and systems that would allow for the ongoing safe storage of this fuel until a final long-term management, or disposition, pathway was available. The FPS Project provides systems and technologies to retrieve and transfer the fuel from the Waste Management Area to a new facility that will repackage, dry, safely store and monitor the fuel for a period of 50 years. All equipment and the new storage facility are designed and constructed to meet the requirements for Class 1 Nuclear Facilities in Canada. (authors)

  14. DEMONSTRATION SOLIDIFICATION TESTS CONDUCTED ON RADIOACTIVELY CONTAMINATED ORGANIC LIQUIDS AT THE AECL WHITESHELL LABORATORIES

    SciTech Connect

    Ryz, R. A.; Brunkow, W. G.; Govers, R.; Campbell, D.; Krause, D.

    2002-02-25

    The AECL, Whiteshell Laboratory (WL) near Pinawa Manitoba, Canada, was established in the early 1960's to carry out AECL research and development activities for higher temperature versions of the CANDU{reg_sign} reactor. The initial focus of the research program was the Whiteshell Reactor-1 (WR-1) Organic Cooled Reactor (OCR) that began operation in 1965. The OCR program was discontinued in the early 1970's in favor of the successful heavy-water-cooled CANDU system. WR-1 continued to operate until 1985 in support of AECL nuclear research programs. A consequence of the Federal government's recent program review process was AECL's business decision to discontinue research programs and operations at the Whiteshell Laboratories and to consolidate its' activities at the Chalk River Laboratories. As a result, AECL received government concurrence in 1998 to proceed to plan actions to achieve closure of WL. The planning actions now in progress address the need to safely and effectively transition the WL site from an operational state, in support of AECL's business, to a shutdown and decommissioned state that meets the regulatory requirements for a licensed nuclear site. The decommissioning program that will be required at WL is unique within AECL and Canada since it will need to address the entire research site rather than individual facilities declared redundant. Accordingly, the site nuclear facilities are being systematically placed in a safe shutdown state and planning for the decommissioning work to place the facilities in a secure monitoring and surveillance state is in progress. One aspect of the shutdown activities is to deal with the legacy of radioactively contaminated organic liquid wastes. Use of a polymer powder to solidify these organic wastes was identified as one possibility for improved interim storage of this material pending final disposition.

  15. Response of invertebrates from the hyporheic zone of chalk rivers to eutrophication and land use.

    PubMed

    Pacioglu, Octavian; Moldovan, Oana Teodora

    2016-03-01

    Whereas the response of lotic benthic macroinvertebrates to different environmental stressors is a widespread practice nowadays in assessing the water and habitat quality, the use of hyporheic zone invertebrates is still in its infancy. In this study, classification and regression trees analysis were employed in order to assess the ecological requirements and the potential as bioindicators for the hyporheic zone invertebrates inhabiting four lowland chalk rivers (south England) with contrasting eutrophication levels (based on surface nitrate concentrations) and magnitude of land use (based on percentage of fine sediments load and median interstitial space). Samples of fauna, water and sediment were sampled twice, during low (summer) and high (winter) groundwater level, at depths of 20 and 35 cm. Certain groups of invertebrates (Glossosomatidae and Psychomyiidae caddisflies, and riffle beetles) proved to be good indicators of rural catchments, moderately eutrophic and with high fine sediment load. A diverse community dominated by microcrustaceans (copepods and ostracods) were found as good indicators of highly eutrophic urban streams, with moderate-high fine sediment load. However, the use of other taxonomic groups (e.g. chironomids, oligochaetes, nematodes, water mites and the amphipod Gammarus pulex), very widespread in the hyporheic zone of all sampled rivers, is of limited use because of their high tolerance to the analysed stressors. We recommend the use of certain taxonomic groups (comprising both meiofauna and macroinvertebrates) dwelling in the chalk hyporheic zone as indicators of eutrophication and colmation and, along with routine benthic sampling protocols, for a more comprehensive water and habitat quality assessment of chalk rivers. PMID:26531711

  16. Risk-based Prioritization of Facility Decommissioning and Environmental Restoration Projects in the National Nuclear Legacy Liabilities Program at the Chalk River Laboratory - 13564

    SciTech Connect

    Nelson, Jerel G.; Kruzic, Michael; Castillo, Carlos; Pavey, Todd; Alexan, Tamer; Bainbridge, Ian

    2013-07-01

    Chalk River Laboratory (CRL), located in Ontario Canada, has a large number of remediation projects currently in the Nuclear Legacy Liabilities Program (NLLP), including hundreds of facility decommissioning projects and over one hundred environmental remediation projects, all to be executed over the next 70 years. Atomic Energy of Canada Limited (AECL) utilized WorleyParsons to prioritize the NLLP projects at the CRL through a risk-based prioritization and ranking process, using the WorleyParsons Sequencing Unit Prioritization and Estimating Risk Model (SUPERmodel). The prioritization project made use of the SUPERmodel which has been previously used for other large-scale site prioritization and sequencing of facilities at nuclear laboratories in the United States. The process included development and vetting of risk parameter matrices as well as confirmation/validation of project risks. Detailed sensitivity studies were also conducted to understand the impacts that risk parameter weighting and scoring had on prioritization. The repeatable prioritization process yielded an objective, risk-based and technically defendable process for prioritization that gained concurrence from all stakeholders, including Natural Resources Canada (NRCan) who is responsible for the oversight of the NLLP. (authors)

  17. Overview of the 1994 chronic HT release experiment at Chalk River

    SciTech Connect

    Davis, P.A.; Workman, W.J.G.; Amiro, B.D.; Spencer, F.S.; Noguchi, H.; Amano, H.; Ichimasa, Y.; Ichimasa, M.

    1995-10-01

    Trace amounts of tritiated hydrogen (HT) were released continuously to the atmosphere at Chalk River Laboratories over the 12-day period 1994 July 27 to August 8. Scientists from eight institutions in four countries took extensive air, soil and vegetation samples to study the dynamics of tritiated water (HTO) and organically-bound tritium (OBT) formation, and the environmental concentrations of these compounds at steady-state. The short-term HT air concentrations varied strongly in time and space over the test area, but the variation decreased rapidly as the averaging time increased. HTO concentrations in soil, vegetation and air built up gradually over time but they fluctuated substantially with ambient meteorological conditions, particularly rainfall. OBT concentrations in plants increased throughout the period. HTO concentrations were at or near steady-state at the end of the release, but OBT levels were continuing to rise. 8 refs., 2 figs., 1 tab.

  18. Simulating Heterogeneous Infiltration and Contaminant leaching Processes at Chalk River, Ontario

    NASA Astrophysics Data System (ADS)

    Ali, M. A.; Ireson, A. M.; Keim, D.

    2015-12-01

    A study is conducted at a waste management area in Chalk River, Ontario to characterize flow and contaminant transport with the aim of contributing to improved hydrogeological risk assessment in the context of waste management. Field monitoring has been performed to gain insights into the unsaturated zone characteristics, moisture dynamics, and contaminant transport rates. The objective is to provide quantitative estimates of surface fluxes (quantification of infiltration and evaporation) and investigations of unsaturated zone processes controlling water infiltration and spatial variability in head distributions and flow rates. One particular issue is to examine the effectiveness of the clayey soil cap installed to prevent infiltration of water into the waste repository and the top sand soil cover above the clayey layer to divert the infiltrated water laterally. The spatial variability in the unsaturated zone properties and associated effects on water flow and contaminant transport observed at the site, have led to a concerted effort to develop improved model of flow and transport based on stochastic concepts. Results obtained through the unsaturated zone model investigations are combined with the hydrogeological and geochemical components and develop predictive tools to assess the long term fate of the contaminants at the waste management site.

  19. Simulations of Two-Well Tracer Tests in Stratified Aquifers at the Chalk River and the Mobile Sites

    NASA Astrophysics Data System (ADS)

    Huyakorn, Peter S.; Andersen, Peter F.; Molz, Fred J.; Güven, Oktay; Melville, Joel G.

    1986-07-01

    A simulation study of two-well injection-withdrawal tracer tests in stratified granular aquifers at two widely separated sites is presented. The first site is located near the Chalk River Nuclear Laboratories in Canada, and the second site is located in Mobile, Alabama. Field data and test conditions at these sites are substantially different in terms of vertical distributions of hydraulic conductivity, well spacings, flow rates, test durations, and tracer travel distances. Furthermore, the test at the Chalk River site was conducted in a recirculating mode, whereas the test at the Mobile site was conducted in a nonrecirculating mode. Simulations of these tests were performed in three dimensions using the curvilinear finite element model developed in the previous paper of this series. The simulations incorporated measured vertical variations in relative hydraulic conductivity and local dispersivity values that are small fractions (between 1/1000 and 1/100) of the spacing between the injection and the withdrawal wells. The local dispersivities are used to account for local hydrodynamic dispersion and are chosen independently so that they are not affected by the scales of the tests. Simulation results obtained from the model are presented. Interpretation of these results is made in conjunction with measured breakthrough curves at the withdrawal well and multilevel observation wells. For the Chalk River site, predicted and measured breakthrough curves at the withdrawal well are in good agreement over the earlier part of the test duration. Deviation of the field data from the model prediction occurs over the second part, where the predicted breakthrough curves show a declining trend but the field data plot does not. For the Mobile site, predicted and measured breakthrough curves at the withdrawal well show similar trends throughout the entire test duration and are in good agreement overall. Model predictions of the effect of hydraulic conductivity stratification on

  20. Connecting large-scale atmospheric circulation, river flow and groundwater levels in a chalk catchment in southern England

    NASA Astrophysics Data System (ADS)

    Lavers, David A.; Hannah, David M.; Bradley, Chris

    2015-04-01

    Groundwater is an important water resource and globally it represents the largest distributed store of freshwater. In southern England, groundwater is a major source for public water supply, and many aquifers have recently experienced both extreme low and high groundwater levels. In this paper, we use observations of precipitation, river discharge and groundwater levels (1964-2010) and an atmospheric reanalysis to explore the large-scale climate patterns preceding the nine highest and lowest March river discharge and groundwater levels in the chalk catchment of the River Lambourn (Berkshire Downs, southern England). Peak monthly precipitation is shown to occur from October to January, while the highest river discharge and groundwater levels are found from February to April. For high discharge/groundwater levels, composite anomaly patterns of the mean sea level pressure show a stronger than average pressure gradient across the North Atlantic Ocean, with enhanced water vapour transport across southern England. For the lowest discharge/groundwater levels, a blocking high pressure system is found across the British Isles deflecting storms and precipitation to the north. Significantly, the intra-composite variability suggests that different sequences of atmospheric states may lead to high and low discharge/groundwater events.

  1. The implications of using large ensembles of climate scenarios for the management of river ecology in an English chalk stream

    NASA Astrophysics Data System (ADS)

    Fung, C. F.; Lopez, A.; New, M.

    2009-04-01

    Climate change is likely to impact on freshwater ecology, the delivery of regulatory commitments to ecological status and the management of water resources. It is becoming increasingly important for European environment agencies to use and develop methods to aid planning and abstraction licensing procedures and policies in the face of climate change and with the introduction of the Water Framework Directive. Studies have been carried out in the past to investigate the implications of climate change for biodiversity. However, predicting the future is fraught with uncertainty, an area which has not been dealt with in great depth in the past. This study has been undertaken to draw on the results of new methodologies to address the uncertainties inherent in modelling future climate and assess their usability for decision-making in water resources allocations specifically in considering interactions between flow and invertebrate communities The River Itchen was chosen as the case study catchment on the strength of having a long-term coupled ecological and flow dataset and having been an area of intensive study in the past. It is a chalk stream located in the south of England and a candidate Special Area of Conservation. It has also been designated a Special Site of Scientific Interest achieved due to the number of rare species, and the richness of the macro-invertebrate community in the river catchment. An ensemble of 246 transient simulations for future climate was obtained from ClimatePrediction.net which were then used to drive a rainfall-runoff model. In order to link the modelled river flow to ecology, the Lotic Invertebrate Flow Evaluation score has been used where the invertebrate community is linked to flow largely through sensitivity to water velocity and siltation, driven by flow variability at sites with fixed channel dimensions The large ensemble of climate scenarios and thereby flow and ecological indices allows the exploration of the risk of the river of

  2. Variability of dissolved CO2 in the Pang and Lambourn Chalk rivers

    NASA Astrophysics Data System (ADS)

    Griffiths, J.; Nutter, J.; Binley, A.; Crook, N.; Young, A.; Pates, J.

    2007-01-01

    This paper presents the results of a two-year field campaign to determine the spatial and temporal variability of groundwater interaction with surface waters in two Cretaceous Chalk catchments (the Pang and Lambourn) in the Upper Thames in Berkshire, UK, based on measurement of dissolved carbon dioxide (CO2). Average stream water concentrations of dissolved CO2 were up to 35 times the concentration at atmospheric equilibrium. Mean groundwater concentrations of 85 and 70 times the atmospheric equilibrium were determined from borehole water sampled in the Pang and Lambourn respectively. Diurnal and seasonal variation of in-stream concentration of dissolved CO2 is not significant enough to mask the signal from groundwater inputs.

  3. Dealing with Historical Discrepancies: The Recovery of National Research Experiment (NRX) Reactor Fuel Rods at Chalk River Laboratories (CRL) - 13324

    SciTech Connect

    Vickerd, Meggan

    2013-07-01

    Following the 1952 National Research Experiment (NRX) Reactor accident, fuel rods which had short irradiation histories were 'temporarily' buried in wooden boxes at the 'disposal grounds' during the cleanup effort. The Nuclear Legacy Liabilities Program (NLLP), funded by Natural Resources Canada (NRCan), strategically retrieves legacy waste and restores lands affected by Atomic Energy of Canada Limited (AECL) early operations. Thus under this program the recovery of still buried NRX reactor fuel rods and their relocation to modern fuel storage was identified as a priority. A suspect inventory of NRX fuels was compiled from historical records and various research activities. Site characterization in 2005 verified the physical location of the fuel rods and determined the wooden boxes they were buried in had degraded such that the fuel rods were in direct contact with the soil. The fuel rods were recovered and transferred to a modern fuel storage facility in 2007. Recovered identification tags and measured radiation fields were used to identify the inventory of these fuels. During the retrieval activity, a discrepancy was discovered between the anticipated number of fuel rods and the number found during the retrieval. A total of 32 fuel rods and cans of cut end pieces were recovered from the specified site, which was greater than the anticipated 19 fuel rods and cans. This discovery delayed the completion of the project, increased the associated costs, and required more than anticipated storage space in the modern fuel storage facility. A number of lessons learned were identified following completion of this project, the most significant of which was the potential for discrepancies within the historical records. Historical discrepancies are more likely to be resolved by comprehensive historical record searches and site characterizations. It was also recommended that a complete review of the wastes generated, and the total affected lands as a result of this historic

  4. Verification timer for AECL 780 Cobalt unit.

    PubMed

    Smathers, J B; Holly, F E

    1984-05-01

    To obtain verification of the proper time setting of the motorized run down timer for a AECL 780 Cobalt Unit, a digital timer is described, which can be added to the system for under $300. PMID:6735762

  5. The Results From the First High-Pressure Melt Ejection Test Completed in the Molten Fuel Moderator Interaction Facility at Chalk River Laboratories

    SciTech Connect

    Nitheanandan, T.; Kyle, G.; O'Connor, R.; Sanderson, DB.

    2006-07-01

    A high-pressure melt ejection test using prototypical corium was conducted at Atomic Energy of Canada Limited Chalk River Laboratories. This test was planned by the CANDU Owners Group to study the potential for an energetic interaction between molten fuel and water under postulated single-channel flow-blockage events. The experiments were designed to address regulator concerns surrounding this very low probability postulated accident events in CANDU Pressurized Heavy Water Reactors. The objective of the experimental program is to determine whether a highly energetic 'steam explosion' and associated high-pressure pulse, is possible when molten material is finely fragmented as it is ejected from a fuel channel into the heavy-water moderator. The finely fragmented melt particles would transfer energy to the moderator as it is dispersed, creating a modest pressure pulse in the calandria vessel. The high-pressure melt ejection test consisted of heating up a {approx} 5 kg thermite mixture of U, U{sub 3}O{sub 8}, Zr, and CrO{sub 3} inside a 1.14-m length of insulated pressure tube. When the molten material reached the desired temperature of {approx} 2400 deg C, the pressure inside the tube was raised to 11.6 MPa, failing the pressure tube at a pre-machined flaw, and releasing the molten material into the surrounding tank of 68 deg C water. The experiment investigated the dynamic pressure history, debris size, and the effects of the material interacting with tubes representing neighbouring fuel channels. The measured mean particle size was 0.686 mm and the peak dynamic pressures were between 2.54 and 4.36 MPa, indicating that an energetic interaction between the melt and the water did not occur in the test. (authors)

  6. An Investigation into the Transportation of Irradiated Uranium/Aluminum Targets from a Foreign Nuclear Reactor to the Chalk River Laboratories Site in Ontario, Canada - 12249

    SciTech Connect

    Clough, Malcolm; Jackson, Austin

    2012-07-01

    This investigation required the selection of a suitable cask and development of a device to hold and transport irradiated targets from a foreign nuclear reactor to the Chalk River Laboratories in Ontario, Canada. The main challenge was to design and validate a target holder to protect the irradiated HEU-Al target pencils during transit. Each of the targets was estimated to have an initial decay heat of 118 W prior to transit. As the targets have little thermal mass the potential for high temperature damage and possibly melting was high. Thus, the primary design objective was to conceive a target holder to dissipate heat from the targets. Other design requirements included securing the targets during transportation and providing a simple means to load and unload the targets while submerged five metres under water. A unique target holder (patent pending) was designed and manufactured together with special purpose experimental apparatus including a representative cask. Aluminum dummy targets were fabricated to accept cartridge heaters, to simulate decay heat. Thermocouples were used to measure the temperature of the test targets and selected areas within the target holder and test cask. After obtaining test results, calculations were performed to compensate for differences between experimental and real life conditions. Taking compensation into consideration the maximum target temperature reached was 231 deg. C which was below the designated maximum of 250 deg. C. The design of the aluminum target holder also allowed generous clearance to insert and unload the targets. This clearance was designed to close up as the target holder is placed into the cavity of the transport cask. Springs served to retain and restrain the targets from movement during transportation as well as to facilitate conductive heat transfer. The target holder met the design requirements and as such provided data supporting the feasibility of transporting targets over a relatively long period of time

  7. PAH occurrence in chalk river systems from the Jura region (France). Pertinence of suspended particulate matter and sediment as matrices for river quality monitoring.

    PubMed

    Chiffre, Axelle; Degiorgi, François; Morin-Crini, Nadia; Bolard, Audrey; Chanez, Etienne; Badot, Pierre-Marie

    2015-11-01

    This study investigates the variations of polycyclic aromatic hydrocarbon (PAH) levels in surface water, suspended particulate matter (SPM) and sediment upstream and downstream of the discharges of two wastewater treatment plant (WWTP) effluents. Relationships between the levels of PAHs in these different matrices were also investigated. The sum of 16 US EPA PAHs ranged from 73.5 to 728.0 ng L(-1) in surface water and from 85.4 to 313.1 ng L(-1) in effluent. In SPM and sediment, ∑16PAHs ranged from 749.6 to 2,463 μg kg(-1) and from 690.7 μg kg(-1) to 3,625.6 μg kg(-1), respectively. Investigations performed upstream and downstream of both studied WWTPs showed that WWTP discharges may contribute to the overall PAH contaminations in the Loue and the Doubs rivers. Comparison between gammarid populations upstream and downstream of WWTP discharge showed that biota was impacted by the WWTP effluents. When based only on surface water samples, the assessment of freshwater quality did not provide evidence for a marked PAH contamination in either of the rivers studied. However, using SPM and sediment samples, we found PAH contents exceeding sediment quality guidelines. We conclude that sediment and SPM are relevant matrices to assess overall PAH contamination in aquatic ecosystems. Furthermore, we found a positive linear correlation between PAH contents of SPM and sediment, showing that SPM represents an integrating matrix which is able to provide meaningful data about the overall contamination over a given time span. PMID:26139398

  8. Chalk Murals and Great Artists.

    ERIC Educational Resources Information Center

    Schweizer, Kay

    2000-01-01

    Discusses the Annual Chalk Mural project done by the members of the National Art Honor Society at the Sacramento County Day School. Discusses the tradition of the annual project and the planning and research involved. Focuses on the 7th Annual Chalk Mural featuring Wayne Thiebaud. (CMK)

  9. Controlled drill & blast excavation at AECL`s Underground Research Laboratory

    SciTech Connect

    Kuzyk, G.W.; Onagi, D.P.; Thompson, P.M.

    1996-12-01

    A controlled drill and blast method has been developed and used to excavate the Underground Research Laboratory, a geotechnical facility constructed by Atomic Energy of Canada Limited (AECL) in crystalline rock. It has been demonstrated that the method can effectively reduce the excavation disturbed zone (EDZ) and is suitable for the construction of a used fuel disposal vault in the plutonic rock of the Canadian Shield.

  10. Structural stratigraphy of Austin Chalk

    SciTech Connect

    Corbett, K.P.; Friedman, M.

    1983-03-01

    The mechanical behavior (structural stratigraphy) of the Upper Cretaceous Austin Chalk is established from the study of fracture intensity along its outcrop trend from Dallas to San Antonio and westward to Langtry, Texas, and in the subsurface from the study of core and/or fracture identification logs from 39 wells. Three mechanical-stratigraphic units are recognized as: (1) an upper, fractured massive chalk corresponding to the Bid House Chalk Member, (2) a middle, ductile chalk-marl corresponding to the Dessau Chalk and Burditt Marl Members, and (3) a lower, fractured massive chalk corresponding to the Atco Chalk Member. Representative samples from these units were experimentally shortened dry, at 10, 17 34, and 70-MPa confining pressure, 24/sup 0/C (75/sup 0/F), and at 2.5 x 10/sup -4/ s/sup -1/ to determine if the relative mechanical behavior observed at the surface could be extrapolated into the subsurface at different simulated depths of burial. The experimentally determined ductilities do parallel those determined from outcrop and subsurface studies. Through multiple linear regression analyses of strength versus intrinsic rock properties and environmental parameters, it appears that first porosity and then smectite-content are most strongly correlated with strength. For low-porosity specimens (9 to 13.5%) smectite present in amounts as little as 1% by volume has the highest correlation with strength accounting for 83% of its variability. SEM photomicrographs show that the clays are smeared-out along the induced shear fracture surfaces where they are greatly reduced in grain-size. These observations suggest that the smectite acts mechanically as a soft-inclusion, localizing shear failure and correspondingly weakening the material.

  11. Less chalk more action

    NASA Astrophysics Data System (ADS)

    Mitriceski Andelkovic, Bojana; Jovic, Sladjana

    2016-04-01

    Less chalk more action Education should not be a mechanical system that operates according to the principles of the orders and implementation. Education should respect the basic laws of the develop and progress. Curiosity is the engine of achievement and children spontaneously and happily learn only if they get interested, if teacher wake up and stimulate their creativity and individuality. We would like to present classes that are realized as thematic teaching with several subjects involved: chemistry, geography, math, art and biology. Classes were organized for students at age from 10 to 13 years, every month during autumn and winter 2015. Better students identified themselves as teachers and presented peer education .Teachers were monitoring the process of teaching and help to develop links between younger and older students, where older students were educators to younger students. Also one student with special needs was involved in this activities and was supported by other students during the workshops The benefit from this project will be represented with evaluation marks. Evaluation table shows that group of ten students(age 10 to13 years) which are selected in October as children with lack of motivation for learning, got better marks, at the end of January , then they had it in the beginning of the semester.

  12. 27 CFR 9.52 - Chalk Hill.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Chalk Hill. 9.52 Section 9... TREASURY ALCOHOL AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.52 Chalk Hill. (a) Name. The name of the viticultural area described in this section is “Chalk Hill.” (b) Approved...

  13. 27 CFR 9.52 - Chalk Hill.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Chalk Hill. 9.52 Section 9... TREASURY ALCOHOL AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.52 Chalk Hill. (a) Name. The name of the viticultural area described in this section is “Chalk Hill.” (b) Approved...

  14. 27 CFR 9.52 - Chalk Hill.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Chalk Hill. 9.52 Section 9... TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.52 Chalk Hill. (a) Name. The name of the viticultural area described in this section is “Chalk Hill.” (b) Approved...

  15. 27 CFR 9.52 - Chalk Hill.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Chalk Hill. 9.52 Section 9... TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.52 Chalk Hill. (a) Name. The name of the viticultural area described in this section is “Chalk Hill.” (b) Approved...

  16. 27 CFR 9.52 - Chalk Hill.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Chalk Hill. 9.52 Section 9... TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.52 Chalk Hill. (a) Name. The name of the viticultural area described in this section is “Chalk Hill.” (b) Approved...

  17. Austin Chalk trend, upper Gulf Coast, Texas

    SciTech Connect

    Holifield, R.

    1982-01-01

    The application of innovative geologic and geophysical interpretations and of carefully tailored well completion techniques has created the opportunity for profitable, low-risk drilling programs in the Austin Chalk Formation of S. Texas. This discussion focuses on selected information that should be beneficial for exploration and development activities in the Austin Chalk. The Giddings field is discussed in some detail, since this field is the center of the greatest activity in the Austin Chalk trend.

  18. A novel representation of chalk hydrology in a land surface model

    NASA Astrophysics Data System (ADS)

    Rahman, Mostaquimur; Rosolem, Rafael

    2016-04-01

    Unconfined chalk aquifers contain a significant portion of water in the United Kingdom. In order to optimize the assessment and management practices of water resources in the region, modelling and monitoring of soil moisture in the unsaturated zone of the chalk aquifers are of utmost importance. However, efficient simulation of soil moisture in such aquifers is difficult mainly due to the fractured nature of chalk, which creates high-velocity preferential flow paths in the unsaturated zone. In this study, the Joint UK Land Environment Simulator (JULES) is applied on a study area encompassing the Kennet catchment in Southern England. The fluxes and states of the coupled water and energy cycles are simulated for 10 consecutive years (2001-2010). We hypothesize that explicit representation for the soil-chalk layers and the inclusion of preferential flow in the fractured chalk aquifers improves the reproduction of the hydrological processes in JULES. In order to test this hypothesis, we propose a new parametrization for preferential flow in JULES. This parametrization explicitly describes the flow of water in soil matrices and preferential flow paths using a simplified approach which can be beneficial for large-scale hydrometeorological applications. We also define the overlaying soil properties obtained from the Harmonized World Soil Database (HWSD) in the model. Our simulation results are compared across spatial scales with measured soil moisture and river discharge, indicating the importance of accounting for the physical properties of the medium while simulating hydrological processes in the chalk aquifers.

  19. Controls on the discharge of Chalk streams of the Berkshire Downs, UK.

    PubMed

    Bradford, Richard B

    2002-01-23

    The water quality and biological functioning of major UK rivers draining permeable basins cannot be fully understood without knowledge of the spatial and temporal controls on the aquifer-river system. In this paper, hydrogeological features of Chalk streams feeding the Thames, the focus of this special issue, are described. Large-scale features, such as line sinks along the Thames and major tributaries such as the Kennet, tend to determine the regional groundwater flow patterns in the Chalk aquifer, whereas the complex characteristics of the Chalk dominate the local spatial and temporal patterns of groundwater discharge to the tributaries draining the dip slopes. These different controls are described and illustrated by particular reference to the Lambourn (a sub-catchment of the Kennet) and Pang catchments. Various issues requiring further investigation are also highlighted. PMID:11846087

  20. Pointing with Power or Creating with Chalk

    ERIC Educational Resources Information Center

    Rudow, Sasha R.; Finck, Joseph E.

    2015-01-01

    This study examines the attitudes of students on the use of PowerPoint and chalk/white boards in college science lecture classes. Students were asked to complete a survey regarding their experiences with PowerPoint and chalk/white boards in their science classes. Both multiple-choice and short answer questions were used. The multiple-choice…

  1. Cretaceous shelf-sea chalk deposits

    SciTech Connect

    Hattin, D.E.

    1988-01-01

    The word ''chalk'' is linked etymologically to the Cretaceous, but chalky facies neither dominate that system nor are confined to it. As used commonly, the term ''chalk'' refers to a variety of marine limestone that is white to light gray very fine grained, soft and friable, porous, and composed predominantly of calcitic skeletal remains, especially those derived from coccolithophores. No simple definition suffices to embrace all Cretaceous chalks, which include sandy, marly, shelly, phospatic, glauconitic, dolomitic, pyritic and organic-rich lithotypes. Most of the world's exposed Cretaceous chalk deposits were formed at shelf depths rather than in the deep sea. Cretaceous shelf-sea chalks are developed most extensively in northern Europe, the U.S. Gulf Coastal Plain and Western Interior, and the Middle East, with lesser occurrences alo in Australia. Most Cretaceous shelf-sea chalks formed in the temperature zones, and in relatively deep water. Cretaceous chalks deposited on well-oxygenated sea floors are bioturbated and massive where deficient in terrigenous detritus, or bioturbated and rhythmically interbedded with argillaceous units where influx of terrigenous detritus varied systematically with climate changes. Accumulation of sufficient pelagic mud to form vast deposits of Cretaceous shelf-sea chalk required (1) sustained high productivity of calareous plankton, (2) extensive development of stable shelf and continental platform environments, (3) highstands of seal level, (4) deficiency of aragonitic skeletal material in chalk-forming sediments, and (5) low rates of terrigenous detrital influx. These conditions were met at different times in different places, even within the same general region.

  2. Austin Chalk boundaries bigger than Texas

    SciTech Connect

    Calhoun, J.

    1980-11-01

    The Austin Chalk is a carbonate limestone which has major outcropping near Austin, Texas. Around Austin, San Antonio, and San Marcos it finds its major expression in the so-called Balcones Escarpment, a jutting limestone promontory that divides the Texas hill country from the Black Gumbo Farmland to the east, and forms one of the longest, most noticeable geologic features in the state. The Chalk is known to run through the entire Gulf Coast Littoral - Louisiana, Mississippi, and Alabama. A map shows the locations of the major uplifts, downwarps, fault zones, and tectonic belts in the Austin Chalk play.

  3. New frac treatment boosts Austin Chalk productivity

    SciTech Connect

    Hubbard, D.; Pierson, N.O.

    1986-09-01

    Wells drilled in the Central Texas Austin Chalk formation tend to deplete rapidly, with production rates declining to 10 bopd or less within months of completion. According to the authors, these wells can often be restored with a dendritic fracturing treatment. Production from 50 conventionally fraced chalk wells averaged only 6 bopd. After dendritic fracturing, average output increased to 61.2 bopd. Similar results were obtained from wells not previously treated.

  4. Nickel adsorption on chalk and calcite

    NASA Astrophysics Data System (ADS)

    Belova, D. A.; Lakshtanov, L. Z.; Carneiro, J. F.; Stipp, S. L. S.

    2014-12-01

    Nickel uptake from solution by two types of chalk and calcite was investigated in batch sorption studies. The goal was to understand the difference in sorption behavior between synthetic and biogenic calcite. Experiments at atmospheric partial pressure of CO2, in solutions equilibrated with calcite and chalk and pH ranging from 7.7 to 8.8, explored the influence of initial concentration and the amount and type of sorbent on Ni uptake. Adsorption increases with increased surface area and pH. A surface complexation model describes the data well. Stability constants for the Ni surface complex are log KNi = - 1.12 on calcite and log KNi = - 0.43 and - 0.50 on the two chalk samples. The study confirms that synthetic calcite and chalk both take up nickel, but Ni binds more strongly on the biogenic calcite than on inorganically precipitated, synthetic powder, because of the presence of trace amounts of polysaccharides and clay nanoparticles on the chalk surface.

  5. Nickel adsorption on chalk and calcite.

    PubMed

    Belova, D A; Lakshtanov, L Z; Carneiro, J F; Stipp, S L S

    2014-12-01

    Nickel uptake from solution by two types of chalk and calcite was investigated in batch sorption studies. The goal was to understand the difference in sorption behavior between synthetic and biogenic calcite. Experiments at atmospheric partial pressure of CO2, in solutions equilibrated with calcite and chalk and pH ranging from 7.7 to 8.8, explored the influence of initial concentration and the amount and type of sorbent on Ni uptake. Adsorption increases with increased surface area and pH. A surface complexation model describes the data well. Stability constants for the Ni surface complex are log KNi=-1.12 on calcite and log KNi=-0.43 and -0.50 on the two chalk samples. The study confirms that synthetic calcite and chalk both take up nickel, but Ni binds more strongly on the biogenic calcite than on inorganically precipitated, synthetic powder, because of the presence of trace amounts of polysaccharides and clay nanoparticles on the chalk surface. PMID:25300061

  6. Microdeformation and subcritical cracking in chalk

    NASA Astrophysics Data System (ADS)

    Bergsaker, Anne; Dysthe, Dag Kristian

    2016-04-01

    Deformation processes in chalks, both in relation to changing pore fluids and stress conditions has been of great interest as chalk is an important reservoir rock for both hydrocarbons and ground water. Lately it has also gained interest as a potential reservoir rock for captured CO2. Chalks are composed of large amounts of biogenic calcite grains, the skeletal debris of marine microorganisms. Its deformation is highly time and stress dependent, and governed by a transition from distributed to localized deformation at the onset of yield, affected by mechanisms such as subcritical crack growth and pore collapse. We present a microdeformation rig which makes use of thermal expansion as a means of subjecting small samples to strictly controlled tensile stresses. High resolution imaging provides resolutions down to 0.5 micrometers, enabling study of pore scale processes during slow deformation. Examples of localized and distributed deformation are presented.

  7. Favorable prices justify Austin Chalk plants

    SciTech Connect

    Mickey, V.

    1981-03-01

    The elements of economics required to justify new natural gas processing plants seem to come together in the Austin Chalk trend of south-central Texas. The Mapco pipeline which originates in the western overthrust belt and carries natural gas liquids to Mont Belvieu, Texas, provides a market for the liquids. With 110 rigs drilling in a 4-county area of the Chalk (Burleson, Lee, Fayette, and Brazos), natural gas reserves are being proven adequate to justify the many new plants being placed in the area. Natural gas liquids prices, which historically are closely correlated with crude oil prices, are reflecting the impact of partial decontrol of those prices. Improvements in natural gas processing technology allow for more energy-efficient plants with more control over the liquids products produced. The result is a hotbed of natural gas processing activity in the Austin Chalk trend.

  8. Surface production facilities in the Austin chalk

    SciTech Connect

    Vadala, C.; Dornak, H.; McDonald, P.

    1983-01-01

    Development drilling in the Austin chalk primarily is centered in a 5-county area between Giddings and Caldwell, Texas. Latest statistics indicate that 182 producers currently are operating in the area with a projected total production of approx. 125,000 bopd and 400 MMcfd. Cumulative oil production stands at nearly 75 million bbl. Surface production facilities include pumping units, production batteries, compressor stations, processing plants, and pipeline gathering systems for both oil and gas. An overview and a discussion of these facilities, as they pertain to the Giddings field and the Austin Chalk, are presented.

  9. Austin chalk stimulation techniques and design

    SciTech Connect

    Parker, C.D.; Weber, D.; Garza, D.; Swaner, S.

    1982-01-01

    This study presents design completion techniques being used to stimulate the Austin Chalk Formation in the Giddings field and Gonzales County, Texas. As background information, a history of the Giddings field and development of the Austin Chalk is discussed. The main purpose is to consider factors affecting fracture treatment design, including fracture height, pump rates, types of fracturing fluids, proppant concentrations, and leak-off controls. This is to insure effective and successful stimulation treatment. Possible alternative design considerations for future fracture treatments also are discussed.

  10. The End of "Chalk and Talk"

    ERIC Educational Resources Information Center

    Barlow, Tim

    2012-01-01

    "Chalk and talk" had been the staple pedagogical approach of my Science teaching practice since entering the profession. I felt that there was a great deal of information that I must impart to my students. My tried and tested way to deliver information to my students had always been simply to stand in front of them and tell it to them... So what…

  11. Austin chalk yields oil near basaltic cone

    SciTech Connect

    Not Available

    1990-09-03

    This paper reports on the completion of a Cretaceous Austin chalk horizontal oil well near a basaltic cone in the Uvalde volcanic field area of Dimmit County, Tex. The well is the HDP Inc. 1 autumn Unit, about 9 miles northeast to Carrizo Springs HDP, which stands for horizontal development and production, of Palo Alto, Calif., drilled the well on a farmout from American Exploration Co., Houston. It initially pumped and flowed 1,600 b/d of oil without stimulation from openhole. HDP drilled about 1,500 ft of horizontal and deviated hole in Austin chalk B-1, the producing horizon. Production in late August was about 500 b/d of oil, pending determination of proration unit size and allowable. The well, in the greater Pearsall field Austin chalk play along the Dimmit-Savala county line, is the first horizontal chalk producer in Elaine field. The field has produced mainly from Escondido sand, Olmos sand and Anacacho limestone, all in the Upper Cretaceous.

  12. Competitive sorption of organic contaminants in chalk

    NASA Astrophysics Data System (ADS)

    Graber, E. R.; Borisover, M.

    2003-12-01

    In the Negev desert, Israel, a chemical industrial complex is located over fractured Eocene chalk formations where transfer of water and solutes between fracture voids and matrix pores affects migration of contaminants in the fractures due to diffusion into the chalk matrix. This study tests sorption and sorption competition between contaminants in the chalk matrix to make it possible to evaluate the potential for contaminant attenuation during transport in fractures. Single solute sorption isotherms on chalk matrix material for five common contaminants ( m-xylene, ametryn, 1,2-dichloroethane, phenanthrene, and 2,4,6-tribromophenol) were found to be nonlinear, as confirmed in plots of Kd versus initial solution concentration. Over the studied concentration ranges, m-xylene Kd varied by more than a factor of 100, ametryn Kd by a factor of 4, 1,2-dichloroethane Kd by more than a factor of 3, phenanthrene Kd by about a factor of 2, and 2,4,6-tribromophenol Kd by a factor of 10. It was earlier found that sorption is to the organic matter component of the chalk matrix and not to the mineral phases (Chemosphere 44 (2001) 1121). Nonlinear sorption isotherms indicate that there is at least some finite sorption domain. Bi-solute competition experiments with 2,4,6-tribromophenol as the competitor were designed to explore the nature of the finite sorption domain. All of the isotherms in the bi-solute experiments are more linear than in the single solute experiments, as confirmed by smaller variations in Kd as a function of initial solution concentration. For both m-xylene and ametryn, there is a small nonlinear component or domain that was apparently not susceptible to competition by 2,4,6-tribromophenol. The nonlinear sorption domain(s) is best expressed at low solution concentrations. Inert-solvent-normalized single and bi-solute sorption isotherms demonstrate that ametryn undergoes specific force interactions with the chalk sorbent. The volume percent of phenanthrene

  13. Austin Chalk stimulations require thorough planning

    SciTech Connect

    Parker, C.D.; Garza, D.; Swaner, S.; Weber, D.

    1982-08-01

    Considers the influence of fracture height, well site position, pump rates, types of fracture fluids, proppant concentrations, and leak-off controls. Careful attention to each of these factors can result in successful stimulation treatment and optimum production rates. The Austin Chalk trend stretches along the entire Gulf Coast from Mexico into Louisiana. Well position relative to faults and natural fractures in the Austin Chalk is the single most critical factor directly affecting productivity. Observations include: cross-linked fluids are necessary in most cases to achieve desired proppant concentration and distribution; there appears to be a relationship between fracture height and pump time; accurate estimates of fracture height are necessary to develop the desired propped fracture length; and leak-off in natural fractures potentially compromises well productivity.

  14. Austin chalk maintains brisk drilling pace

    SciTech Connect

    Not Available

    1991-04-01

    Horizontal drilling in the Cretaceous Austin chalk trend of South Texas continues to set a fast pace. The Texas Railroad Commission has issued nearly 900 permits to drill horizontal wells in the Pearsall field area alone from 1984 through February 1991. TRC issued 1,485 permits for horizontal wells statewide during that period, including 1,285 since Jan. 1, 1990. Statewide, operators have reported completion of 685 horizontal wells. That includes 472 in Pearsall field, where TRC has issued 882 permits, and 121 in Giddings field, where 305 permits have been issued. Frio County, site of Pearsall field, led Texas counties with 494 permits and 278 horizontal completions. Oil drilling and reentry work is under way in many areas, and horizontal Austin chalk gas/condensate completions have been reported in Dimmit and Burleson counties.

  15. Giddings Austin chalk enters deep lean-gas phase

    SciTech Connect

    Moritis, G.

    1995-12-25

    Deep lean gas is the latest phase in the growth of the Giddings field Austin chalk play. The first phase involved drilling vertical oil and gas wells. Next came the horizontal well boom in the shallower Austin chalk area, which is still continuing. And now this third phase places horizontal laterals in the Austen chalk at about 14,000--15,000 ft to produce lean gas. The article describes the producing wells and gas gathering.

  16. Characterization of the Austin Chalk producing trend

    SciTech Connect

    Chen, H.Y.; Poston, S.W.; Wu, C.H.

    1986-01-01

    Fracture patterns and reservoir dual characteristics are presented for a portion of the fractured Austin Chalk producing trend. The production histories of 1,235 wells from Giddings Field covering portions of Lee, Burleson, Washington, and Fayette counties were analyzed by decline curve analysis. Production of the average Austin Chalk well is usually characterized by an early rapid decline and a later slow decline. The average initial effective decline rate is about 90% per year, and lasts about six months to one year. For the later, less dramatic decline, the average is about 35% per year. Statistical results of well performance indicate no difficulty in finding oil in the Austin Chalk producing trend. However, areas of high fracture density must be encountered for a well to be profitable. A contour map of the iso-reserves was prepared for a better understanding of the fracture system and reservoir characteristics. Besides the general northeast-southwest production trend, the map shows anomalies in the fracture system and reservoir characteristics. A simple, rapid technique to estimate reservoir parameters directly from the double-decline behavior of log (rate) versus time curves is given. Values of flow capacity, storage capacity, dimensionless fracture storage parameter (..omega..), and dimensionless interporosity flow parameter (lambda) can be estimated by this technique.

  17. The Beauty of the Beasts in Chalk Pastels

    ERIC Educational Resources Information Center

    Skophammer, Karen

    2010-01-01

    In this article, the author describes how her seventh-grade art students captured an image of a stuffed animal in the "whole-to-part" drawing technique using chalk pastels. Shading with chalk pastels can give a gradual change in value from dark to light. The shading and color changes the mood of the original drawing, and adds texture, too. Chalk…

  18. Horizontal drilling in the Austin Chalk: Stratigraphic factors

    SciTech Connect

    Durham, C.O. Jr. ); Bobigian, R.A. )

    1990-05-01

    Horizontal drilling has renewed interest in the Austin chalk in south-central Texas. Large fields on opposite sides of the San Marcos arch Giddings to the northeast and Pearsall to the southwest were active with vertical drilling 10 years ago. Giddings' 4,500 Austin wells produced 209 million BO and 934 bcfg of gas through 1988; Pearsall's 1,440 wells produced 57 million BO and 35 bcfg of gas. Most vertical wells were completed, 20% were economic successes, 40% were marginal, 40% were uneconomic due to uneven areal distribution of near-vertical fractures and small faults, which provide reservoirs in otherwise tight chalk. Horizontal drilling, led by Amoco in Giddings and Oryx in Pearsall, enhances the chances of encountering the fractures by drilling perpendicular to the fracture trend. Horizontal drilling requires preselection of the stratigraphic horizon to be penetrated. One must understand the variable Austin stratigraphy to choose the zone with the most brittle character and best matrix porosity, both reduced by increased clay content. Chalk 130 ft thick on the San Marcos arch thickens to 600 to 800 ft in central Giddings field where middle marl separates lower and upper chalk Northeastward only lower chalk is preserved beneath a post-Austin submarine channel. The Austin thickens to 300-500 ft in Pearsall field where middle member ash beds separate lower and upper chalk inhibiting vertical reservoir communication. Locally, on the Pearsall arch, ash is missing, lower chalk thickens, and upper chalk thins.

  19. Compaction of North-sea chalk

    NASA Astrophysics Data System (ADS)

    Keszthelyi, Dániel; Dysthe, Dag Kristian; Jamtveit, Bjørn

    2014-05-01

    The Ekofisk field is the largest petroleum field in the Norwegian North Sea territory where oil is produced from chalk formations. Early stage of oil production caused considerable changes in pore fluid pressure which led to a reservoir compaction. Pore collapse mechanism caused by the dramatic increase of effective stress, which in turn was caused by the pressure reduction by hydrocarbon depletion, was early identified as a principal reason for the reservoir compaction (Sulak et al. 1991). There have been several attempts to model this compaction. They performed with variable success on predicting the Ekofisk subsidence. However, the most of these models are based on empirical relations and do not investigate in detail the phenomena involved in the compaction. In sake of predicting the Ekofisk subsidence while using only independently measurable variables we used a chalk compaction model valid on geological time-scales (Japsen et al. 2011) assuming plastic pore-collapse mechanism at a threshold effective stress level. We identified the phenomena involved in the pore collapse. By putting them in a sequential order we created a simple statistical analytical model. We also investigated the time-dependence of the phenomena involved and by assuming that one of the phenomena is rate-limiting we could make estimations of the compaction rate at smaller length-scales. By carefully investigating the nature of pressure propagation we could upscale our model to reservoir scale. We found that the predicted compaction rates are close enough to the measured rates. We believe that we could further increase accuracy by refining our model. Sulak, R. M., Thomas, L. K., Boade R. R. (1991) 3D reservoir simulation of Ekofisk compaction drive. Journal of Petroleum Technology, 43(10):1272-1278, 1991. Japsen, P., Dysthe, D. K., Hartz, E. H., Stipp, S. L. S., Yarushina, V. M., Jamtveit. (2011) A compaction front in North Sea chalk. Journal of Geophysical Research: Solid Earth (1978

  20. Drilling and well completion of Austin Chalk

    SciTech Connect

    Coffman, C.A.

    1982-01-01

    This study describes U.S. Operating, Inc.'s experiences in drilling and well completion in the Austin Chalk zone of Lee County, Texas. This area's difficulties have included high pressure gas, lost circulation in low pressure zones, varying content of producing formations, varying grades and qualities of production in the same producing zones, and faulting. The potential for severe kicking is always present, and casing failures are common. Procedures for dealing with the expected kicks, lost circulation, difficult casing jobs, and variable production are described.

  1. Seismic and horizontal drilling unlock Austin Chalk

    SciTech Connect

    Kuich, N. )

    1990-09-01

    Giddings is a Texas field whose economic production is totally dependent on the development of natural fracture porosity. Matrix porosities and permeabilities in the Austin Chalk limestone, the primary objective, are incapable of maintaining commercial hydrocarbon production. This paper discusses how fracture identification from seismic data has been used as a successful prospecting tool in the area for over ten years. The advent of horizontal drilling technology now allows the development of multiple seismic fracture indicators in the same wellbore. These indicators often represent unique hydrocarbon accumulations.

  2. Chalk play tops Gulf Coast horizontal scene

    SciTech Connect

    Not Available

    1991-11-18

    This paper reports on horizontal drilling in the Cretaceous Austin chalk of Texas which dominates news of U.S. Gulf Coast horizontal action. In spite of a significant decline in horizontal drilling in Texas-the Texas Railroad Commission reported a 15 unit decline in the number of permits to drill horizontal wells during the third quarter-operators in East and South Texas continue to expand plays and develop new ones. The Cretaceous Bruda may be gaining some respect as a horizontal target in Texas. Elsewhere on the Gulf Coast, Mississippi soon will see more action on the horizontal drilling front.

  3. Stimulation techniques used in the Austin Chalk

    SciTech Connect

    Ely, J.; McDow, G. Turner, J.

    1982-01-01

    The object of this work is to discuss the most widely used stimulation techniques employed in the Austin Chalk formation in S. Texas. Although this trend has been explored for years and continues to be one of the most active in the country, there remains a difference of opinion over how to effectively stimulate this reservoir. Several schools of thought regarding types of fluids, additives, and general treating techniques are examined. The fracture geometry of various treatments as predicted by pre-treatment computer designs are compared to the parameters obtained from post-frac analysis.

  4. New understanding of the complexity of groundwater flow in Chalk catchments of the UK

    NASA Astrophysics Data System (ADS)

    Peach, D.; Shand, P.; Gooddy, D.; Abesser, C.; Bloomfield, J.; Mathias, S.; Butler, A.; Williams, A.; Binley, A.; Wheater, H.

    2006-12-01

    The Chalk is the largest aquifer in the UK accounting for more than half the groundwater used and nearly a quarter of the total public water supplied in England and Wales. Although the Chalk is a double porosity and permeability medium, transmission of water in the saturated zone depends largely on flow through fractures, the location and distribution of which are controlled by lithology and geological structure. These features operate on a number of spatial scales and so provide a range of flow pathways that can markedly affect both stream flow and water quality. In addition, overlying Palaeogene or superficial deposits can act as controls on recharge and zones of increased groundwater storage. As part of a major initiative on Lowland Catchment Research in the UK two Chalk sub-catchments, in the River Thames basin, the rivers Pang and Lambourn, have been the focus of an intensive set of studies. The catchments have been characterised using a multidisciplinary approach. This has resulted in an improved understanding of the way such catchments work and the mechanisms that control groundwater flow. The low fracture porosity gives rise to a low specific yield, which means that large fluctuations in water table elevation beneath the interfluves are not uncommon. Consequently, groundwater catchments differ from the topographic catchments and their size varies seasonally. This means, for example, that groundwater might be flowing to the River Pang in winter but to the River Thames in summer. It also means that various flow features in the catchment may be active at different locations and times during the year. Four flow systems have been identified, through a detailed analysis of the data; a shallow, but rapid flow system; a slower, deeper system; a very high velocity system developed in large diameter solution enhanced fractures and a system found in the river valley sediments. The interconnections between and within these systems can be poor and sometimes vary on a

  5. Typical well nonexistent in Austin Chalk

    SciTech Connect

    Mickey, V.

    1981-11-01

    Discoveries of localized large-capacity reservoirs capable of sustaining high-rate production distinguish the current Austin Chalk play from past booms in the S.E. Texas trend. The chalk gained its reputation for high initial potentials with quick decline rates in the area of the Pearsall field in Frio County; this is southwest of the current focus of play in Burleson, Lee, Fayette, Washington, and Gonzales Counties. In this portion of the vast producing trend a different kind of rock exists - one that is highly fractured and gives up large amounts of hydrocarbons for a sustained period. An example of high-rate sustained production is in the Birch Creek area near Lake Somerville in Burleson County. Projected reserves should average 100,000 to 125,000 bbl/well. With varying amounts of associated gas from 400 MMCF to one billion cubic feet. Initial production tests on these wells range from 200 to 500 bopd and 200 MCFD to 3 MMCFD. After several months of production, the wells indicate capacity to hold up to initial performance.

  6. Temporal variability of micro-organic contaminants in lowland chalk catchments: New insights into contaminant sources and hydrological processes.

    PubMed

    Manamsa, K; Lapworth, D J; Stuart, M E

    2016-10-15

    This paper explores the temporal variation of a broad suite of micro organic (MO) compounds within hydrologically linked compartments of a lowland Chalk catchment, the most important drinking water aquifer in the UK. It presents an assessment of results from relatively high frequency monitoring at a well-characterised site, including the type and concentrations of compounds detected and how they change under different hydrological conditions including exceptionally high groundwater levels and river flow conditions during 2014 and subsequent recovery. This study shows for the first time that within the Chalk groundwater there can be a greater diversity of the MOs compared to surface waters. Within the Chalk 26 different compounds were detected over the duration of the study compared to 17 in the surface water. Plasticisers (0.06-39μg/L) were found to dominate in the Chalk groundwater on 5 visits (38.4%) accounting for 14.5% of detections but contributing highest concentrations whilst other compounds dominated in the surface water. Trichloroethene and atrazine were among the most frequently detected compounds. The limit for the total pesticide concentration detected did not exceed EU/UK prescribed concentration values for drinking water. Emerging organic compounds such as caffeine, which currently do not have water quality limits, were also detected. The low numbers of compounds found within the hyporheic zone highlight the role of this transient interface in the attenuation and breakdown of the MOs, and provision of an important ecosystem service. PMID:26850859

  7. Austin Chalk (!) Petroleum System: Upper Cretaceous, Southeastern Texas

    SciTech Connect

    Dawson, W.C.; Katz, B.J.; Robison, V.D.

    1995-10-01

    The Austin Group (Coniacian-Santonian) is a sequence of interstratified chalk and marl deposited during a sea-level highstand as a transgressive unit. Austin Chalk deposition occurred on a southeastward-dipping carbonate ramp that exhibits distinctive onshore and offshore chalk lithofacies. Discrete intervals within offshore Austin lithofacies display good to excellent source rock potential. Organic carbon content ranges upward to 20.0 wt. % with generation potentials exceeding 45 mg HC/g of rock measured. Source potential increases basinward where offshore chalk units exhibit increases in both organic richness and net thickness. These organically rich units display an affinity for the Type II reference curve. Hydrogen index values typically exceed 300 mg HC/g TOC. Several geochemical indices suggest that the oil-window is located at relatively shallow depths (6,700 ft). Offshore chalks sourced onshore Austin reservoirs through lateral migration (along fractures and stylolites) which occurred during the middle Tertiary. Hydrocarbons may also have been sourced from the underlying Eagle Ford Shale (Turonian). Austin Shale reservoirs are characterized by low porosity/low permeability dual pore systems consisting of microporous matrix and fractures. Diagenesis (mechanical compaction, styloitization, and calcite cementation) has strongly modified Austin Chalk pore systems. Matrix porosity generally decreases with increasing depth because of progressive burial diagenesis. Austin reservoirs typically have two major sets of fractures; reservoir performance is related to fracture connectivity. Austin Chalk reservoirs are sealed by the overlying Taylor Marl (Campanian).

  8. Evaluation of Austin Chalk from cores

    SciTech Connect

    Craft, J.M.

    1982-01-01

    To evaluate the economic and producing capacity of the Austin Chalk it is necessary to recognize the existence of 2 types of reservoirs, the matrix and the fracture reservoir. These 2 reservoirs are vastly different in their ability to store and produce hydrocarbons. A detailed definition of each and an understanding of their interdependence and interaction is necessary for a successful evaluation. The fracture reservoir can, in its natural state, have a very high permeability and capacity to transmit liquids or gas. It can have significant storage capacity. Matrix porosity and oil saturation indicate zones of matrix hydrocarbon accumulation. The permeability present would not flow significant amounts of fluid without the presence of a fracture system, either natural or artificially induced. Fractures must have sufficient permeability to reduce pressure in the fracture approaching well-bore flowing pressure.

  9. Evidence of influence of regional and local heterogeneities within a chalk karst aquifer based on nitrates and chlorides analysis

    NASA Astrophysics Data System (ADS)

    El Janyani, S.; Dupont, J. P.; Massei, N.; Dörfliger, N.

    2012-04-01

    In Upper Normandy, a region located in the western Paris Basin, the main source of drinking water comes from the karst aquifer. Developing under the chalk plateaus, it is a covered aquifer overlaid by superficial formations of clay-with-flints and loess. Clay-with-flints result from chalk weathering whereas loess are wind periglacial deposits. The local geologic and hydrogelogic contexts are characterized by a mature development of sinkholes. The chalk karst is causing turbidity, often linked to the fast infiltration of surface water, carrying the products of river and slope erosion and associated contaminants into the aquifer through the sinkholes. Several authors have shown the potential of turbidity as a marker of suspended elements transport and karst conduits fast transport. In this study, we conducted monthly monitoring of 11 boreholes located in the upstream watershed near boreholes (surveyed by the French Geological Survey BRGM): Graveron-Semerville in the Southern department of Upper Normandy (Eure) and Rocquemont in the Norhtern department of Upper Normandy (Seine-Maritime). The monitoring carried out included water level and electrical conductivity (reflecting total water mineralization) measurements, and major elements analysis. In any case, the water levels are similar over time (in accordance with the reference borehole). High mineralizations are observed in the Eure boreholes with significant anomalies of nitrate (70 to 130 mg/l ) and chloride (35 to 90 mg/l). For the Seine Maritime boreholes, no anomalies in nitrates and chlorides were found. To explain such differences, the agricultural activities are not sufficiently different from the study site. The explanation would then come from different reservoirs involved in water storage: loessic formations, thicker and more spreaded in the Seine Maritime department and clay with flints, of significantly higher thickness on average in the Eure department. We also discuss the influence of the drainage

  10. Horizontal well drilled into deep, hot Austin chalk

    SciTech Connect

    Pearce, D.; Johnson, M.; Godfrey, B.

    1995-04-03

    Bent-housing steerable downhole motors helped maintain course for a deep, hot, horizontal well in the Austin chalk. The Navasota Unit No. 1 was planned as a B zone, single downdip lateral, Austin chalk horizontal well with a maximum departure from vertical of 3,767 ft and a planned total depth (TD) of 17,342 ft measured depth (MD)/14,172 ft TVD. The Austin chalk was found significantly deeper in this well than planned, which resulted in an actual TD of 17,899 ft MD/14,993 ft TVD, the deepest (TVD) horizontal well in the Austin chalk to date. The well was spudded on August 6, 1994, and took 52 days to reach TD. The static bottom hole temperature was almost 350 F. The paper describes the well plan, drilling results, and the lateral section.

  11. Experimental formation of chalk from calcareous ooze. Technical progress report

    SciTech Connect

    Seyfried, W.E.; Johnson, T.C.

    1981-02-15

    Samples of calcareous ooze collected from the tropical and equatorial Atlantic Ocean were subjected to hydrothermal alteration in order to simulate the diagenesis of chalk. Changes in mineralogy and morphology of enclosed microfossils were measured. (ACR)

  12. The invertebrate ecology of the Chalk aquifer in England (UK)

    NASA Astrophysics Data System (ADS)

    Maurice, L.; Robertson, A. R.; White, D.; Knight, L.; Johns, T.; Edwards, F.; Arietti, M.; Sorensen, J. P. R.; Weitowitz, D.; Marchant, B. P.; Bloomfield, J. P.

    2016-03-01

    The Chalk is an important water supply aquifer, yet ecosystems within it remain poorly understood. Boreholes (198) in seven areas of England (UK) were sampled to determine the importance of the Chalk aquifer as a habitat, and to improve understanding of how species are distributed. Stygobitic macro-invertebrates were remarkably common, and were recorded in 67 % of boreholes in unconcealed Chalk, although they were not recorded in Chalk that is concealed by low-permeability strata and thus likely to be confined. Most species were found in shallow boreholes (<21 m) and boreholes with deep (>50 m) water tables, indicating that the habitat is vertically extensive. Stygobites were present in more boreholes in southern England than northern England (77 % compared to 38 %). Only two species were found in northern England compared to six in southern England, but overall seven of the eight stygobitic macro-invertebrate species found in England were detected in the Chalk. Two species are common in southern England, but absent from northern England despite the presence of a continuous habitat prior to the Devensian glaciation. This suggests that either they did not survive glaciations in the north where glaciers were more extensive, or dispersal rates are slow and they have never colonised northern England. Subsurface ecosystems comprising aquatic macro-invertebrates and meiofauna, as well as the microbial organisms they interact with, are likely to be widespread in the Chalk aquifer. They represent an important contribution to biodiversity, and may influence biogeochemical cycles and provide other ecosystem services.

  13. Influence of lithofacies and diagensis on Norwegian North Sea chalk reservoirs

    SciTech Connect

    Brasher, J.E.; Vagle, K.R.

    1996-05-01

    The depositional mechanism of chalk is a key influence in the chalk`s ultimate reservoir quality. Classically, the depositional mechanism is interpreted from core descriptions. Where core data are lacking, dipmeter and borehole imagery logs have proven useful in making lithofacies assessments. Criteria for recognition of three chalk categories are established. Category III chalks correspond to those chalks that have been deposited by gravity flows or slumping and tend to have the best reservoir parameters. Category I chalks are most often affiliated with pelagic deposition and tend to have the poorest reservoir parameters. Category II chalks are intermediate between I and III. Anomalously high primary porosities have been maintained in Norwegian North Sea chalks where the effects of mechanical and chemical compaction have been limited. The diagenetic pathway of a chalk reflects changes brought about by mechanical and chemical compaction. Five factors most heavily influence the diagenetic pathway: (1) burial depth, (2) chalk type, (3) overpressuring, (4) presence of hydrocarbons, and (5) original grain size. Assessments of the sedimentological model, diagenetic pathway, and resultant reservoir quality are provided in case studies of Edda, Tor, and Eldfisk fields. Because the distribution of chalk is largely independent of existing structures, most fields have a component of stratigraphic/diagenetic trapping. Each case study shows unique examples of how petrophysical and reservoir engineering data can be incorporated in assessments of chalk type and the diagenetic pathway and how they may affect reservoir parameters and productivity.

  14. Understanding heterogeneity in UK Chalk catchments and its influence on groundwater flooding

    NASA Astrophysics Data System (ADS)

    Peach, D. W.; Vounaki, T.; Jackson, C. R.; Hughes, A. G.; Wheater, H. S.

    2008-12-01

    The numerical simulation of groundwater flooding is increasingly necessary as this problem is gaining recognition from government and regulators and climate change may bring more extreme events. The Natural Environment Research Council of the UK is funding the British Geological Survey, Imperial College, and the Centre for Ecology and Hydrology to examine the problem of groundwater flooding in the Cretaceous Chalk of Berkshire, 50 kilometres west of London. Typically regional resource issues can be examined using traditional groundwater models that do not consider in detail the influence of flow in the unsaturated zone, but the delays in recharge transmission through this zone to the water table may be very significant in terms of flood timing and prediction. The position of ground elevation relative to water table is clearly important but not often considered in groundwater resource modelling. Groundwater level and stream (and flood) flow responses are important data that may be hard to gather from typical groundwater monitoring systems. These problems have been examined in a Chalk catchment in Berkshire where good records of the 2000-1 and 2003 flooding events have been collected, including flooded extent, rainfall, groundwater levels, river and spring flows. From this analysis, it appears that two groundwater mounds develop in the upper part of the Pang and Lambourn catchments. These mounds intersect dry valleys, which flowed for several months, the consequent flooding causing considerably disruption. Modelling of these events is providing new insight into the heterogeneity of Chalk transmissivity and storage parameters, enhanced knowledge of its dual permeability and porosity and demonstrating the importance of understanding the post-depositional hydrogeological history of the aquifer.

  15. Homing in on sweet spots in Cretaceous Austin chalk

    SciTech Connect

    Thomas, G.E. ); Sonnenberg, F.P.

    1993-11-29

    In discussing the nature and causes of fracturing in the Cretaceous Austin chalk of south central Texas, many geologists and operators involved in horizontal drilling of the chalk consider regional rock stress as the probable main cause of the fractures. If Austin chalk fractures are mainly the result of regional extensional stress without localizing factors, then fractured sweet spots are randomly distributed and successful exploration is more or less a matter of luck, usually dependent upon the coincidental placement of a seismic line. But if local, deep-seated structure or basement topography are the main causes of sweet spots, then a successful exploration method would be to first delineate the basement paleo structure or topography and secondly, place a seismic line to confirm the delineated features. Finding localities of maximum fracturing and production would than be based on scientific logic rather than luck. It is the purpose of this article to present the results of an examination of these alternative causes for the Austin chalk fracturing in the hope of determining the most cost effective exploration method for the fractured chalk reservoir.

  16. Gas/oil capillary pressure at chalk at elevated pressures

    SciTech Connect

    Christoffersen, K.R.; Whitson, C.H.

    1995-09-01

    Accurate capillary pressure curves are essential for studying the recovery of oil by gas injection in naturally fractured chalk reservoirs. A simple and fast method to determine high-pressure drainage capillary pressure curves has been developed. The effect of gas/oil interfacial tension (IFT) on the capillary pressure of chalk cores has been determined for a methane/n-pentane system. Measurements on a 5-md outcrop chalk core were made at pressures of 70, 105, and 130 bar, with corresponding IFT`s of 6.3, 3.2, and 1.5 mN/m. The results were both accurate and reproducible. The measured capillary pressure curves were not a linear function of IFT when compared with low-pressure centrifuge data. Measured capillary pressures were considerably lower than IFT-scaled centrifuge data. It appears that the deviation starts at an IFT of about 5 mN/m. According to the results of this study, the recovery of oil by gravity drainage in naturally fractured chalk reservoirs may be significantly underestimated if standard laboratory capillary pressure curves are scaled by IFT only. However, general conclusions cannot be made on the basis on only this series of experiments on one chalk core.

  17. What are the governing processes during low-flows in a chalk catchment?

    NASA Astrophysics Data System (ADS)

    Lubega Musuuza, Jude; Coxon, Gemma; Hutton, Chris; Howden, Nicholas; Woods, Ross; Freer, Jim; Wagener, Thorsten

    2016-04-01

    Low flows are important because they lead to the prioritisation of different consumptive water usages, imposition of restrictions and bans, raising of water tariffs and higher production costs to industry. The partitioning of precipitation into evaporation, storage and runoff depends on the local variability in meteorological variables and site-specific characteristics e.g., topography, soils and vegetation. The response of chalk catchments to meteorological forcing especially precipitation is of particular interest because of the preferential flow through the weathered formation. This makes the observed stream discharge groundwater-dominated and hence, out of phase with precipitation. One relevant question is how sensitive the low flow characteristics of such a chalk catchment is to changes in climate and land use. It is thus important to understand all the factors that control low stream discharge periods. In this study we present the results from numerical sensitivity analysis experiments performed with a detailed physically-based model on the Kennet, a sub-catchment of the River Thames, in the UK during the historical drought years of the 1970's.

  18. Cyclic sedimentation, synsedimentary volcanism, microfabrics, and fracture intensity in the Austin Chalk, Texas

    SciTech Connect

    Hovorka, S.D. )

    1992-01-01

    Pelagic depositional environments of the Austin Chalk (Coniacian-Santonian) were influenced by sea-level variation, planktonic productivity, and allochthonous detrital input. Subtle differences in chalk facies influence fracture intensity, therefore imposing stratigraphic variability on hydrologic properties of the Austin Chalk. Variations in fracture intensity may affect ground-water flow through the Superconducting Super Collider (SSC) site south of Dallas in the same way that they influence hydrocarbon production in South Texas. The lower Austin Chalk was deposited during transgression. Glauconitic sandstone is overlain by cyclic chalk containing chalk-filled channels. Meter-thick chalk/marl cycles have frequencies in the Milankovitch spectrum. Marl accumulated during episodes of decreased planktonic productivity. Maximum flooding is indicated by organic-rich marls in the upper part of the Lower Austin Chalk. Shallowing during deposition of the middle and upper Austin Chalk is indicated by increasing abundance of winnowed lag deposits and firm grounds, resulting in increased faunal diversity. Authigenic clay, a product of alteration of volcanic ash codeposited with the chalk and marl, increases ductility in the middle Austin Chalk. The stratigraphic distribution of authigenic clay corresponds to disseminated biotite, quartz, and feldspar phenocrysts in most samples of the middle Austing Chalk. Authigenic clay decreases porosity, influences porosity-permeability relationships, and provides a regionally traceable low SP log response that correlates with low fracture intensity.

  19. Horizontal spacing, depletion, and infill potential in the Austin Chalk

    SciTech Connect

    Kyte, D.G.; Meehan, D.N.

    1996-12-31

    There have been more than 4500 laterals drilled in the Austin Chalk. This paper looks at estimated ultimate recoveries (EUR) on a barrels/acre basis for these Austin Chalk wells. Baffels/acre recoveries were computed by estimating ultimate per-well recoveries, drilled density and the impact of vertical production. The data were then analyzed for depletion and infill potential. Certain areas were selected for further study using an artificial neural network. The network was built and used to study the effects of parameters such as lateral length, first production date, structure of the Austin Chalk, etc. on these recoverable barrel/acre numbers. The methodology and regional results of the study are reviewed with detailed analyses shown in selected areas.

  20. Managing extremes in groundwater-dominated catchments: the Chalk of SE England (Invited)

    NASA Astrophysics Data System (ADS)

    Wheater, H. S.

    2009-12-01

    The Chalk aquifers of Southern and Eastern England are a dominant local and regional water resource, and rivers located on the Chalk outcrop have a characteristic behaviour and support valuable and protected aquatic ecosystems. In these catchments, typically less than 2% of rainfall is translated into stormflow response. Infiltration occurs into an unsaturated zone that varies in depth from zero at the stream to 100m at the interfluve. Seasonal groundwater recharge is translated into a seasonal river hydrograph, and the length of flowing river expands and contracts seasonally - so-called ‘bourne’ behaviour. Groundwater catchment areas also vary temporally, and stream-aquifer interactions can be complex. Extensive and long duration flooding in 2000/2001 highlighted the vulnerability of these systems to extremes of long duration rainfall (weeks and months). Source areas for runoff expand into dry valleys, springs break out in ‘new’ locations and given the normally low %runoff, highly non-linear flow response occurs. Conversely, droughts are also of major concern, particularly given scenarios of climate change for SE England. Water quality issues are also important, particularly nutrient pollution. These management concerns have focussed attention on the need for improved understanding, and for appropriate modelling tools for flood risk assessment and drought and water quality management. The paper addresses recent research into the historic behaviour of these systems under extremes, the relative roles of fracture and porous matrix flow in the unsaturated zone under extremes, and the nature of stream-aquifer interactions, including detailed experimental studies. Challenges for modelling are identified; for groundwater flooding conventional flood design approaches are inadequate, but groundwater models lack appropriate topographic constraints and the required spatial and temporal resolution; for drought, recharge estimation and diffuse pollution, better

  1. Human Geophagia, Calabash Chalk and Undongo: Mineral Element Nutritional Implications

    PubMed Central

    Abrahams, Peter W.; Davies, Theo C.; Solomon, Abiye O.; Trow, Amanda J.; Wragg, Joanna

    2013-01-01

    The prime aim of our work is to report and comment on the bioaccessible concentrations – i.e., the soluble content of chemical elements in the gastrointestinal environment that is available for absorption – of a number of essential mineral nutrients and potentially harmful elements (PHEs) associated with the deliberate ingestion of African geophagical materials, namely Calabash chalk and Undongo. The pseudo-total concentrations of 13 mineral nutrients/PHEs were quantified following a nitric-perchloric acid digestion of nine different Calabash chalk samples, and bioaccessible contents of eight of these chemical elements were determined in simulated saliva/gastric and intestinal solutions obtained via use of the Fed ORganic Estimation human Simulation Test (FOREhST) in vitro procedure. The Calabash chalk pseudo-total content of the chemical elements is often below what may be regarded as average for soils/shales, and no concentration is excessively high. The in vitro leachate solutions had concentrations that were often lower than those of the blanks used in our experimental procedure, indicative of effective adsorption: lead, a PHE about which concern has been previously raised in connection with the consumption of Calabash chalk, was one such chemical element where this was evident. However, some concentrations in the leachate solutions are suggestive that Calabash chalk can be a source of chemical elements to humans in bioaccessible form, although generally the materials appear to be only a modest supplier: this applies even to iron, a mineral nutrient that has often been linked to the benefits of geophagia in previous academic literature. Our investigations indicate that at the reported rates of ingestion, Calabash chalk on the whole is not an important source of mineral nutrients or PHEs to humans. Similarly, although Undongo contains elevated pseudo-total concentrations of chromium and nickel, this soil is not a significant source to humans for any of the

  2. Impact-assessment report: Chalk Point Steam Electric Station aquatic-monitoring program

    SciTech Connect

    Not Available

    1985-01-01

    The Chalk Point Steam Electric Station (SES), owned and operated by the Potomac Electric Power Company (PEPCO), is located in the estuarine portion of the Patuxent River just above the Benedict Bridge near Aquasco, Maryland. The plant's two coal-fired units use once-through cooling systems and pursuant to the Code of Maryland Regulations 10.50.01.13, which governs water-quality impact assessments for thermal discharges, PEPCO is required to: assess compliance with mixing-zone specifications that relate discharge flows and thermal-plume size to advective and diffusive properties of the receiving-water body; determine the magnitude and consequences of plant impacts on spawning and nursery areas for organisms that are representative of and important to the receiving body; and determine the magnitude and dollar value of impingement losses.

  3. Sediment transport and siltation of brown trout (Salmo trutta L.) spawning gravels in chalk streams

    NASA Astrophysics Data System (ADS)

    Acornley, R. M.; Sear, D. A.

    1999-02-01

    Deposition rates of fine sediment into brown trout spawning gravels were measured at monthly intervals for a period of one year in a small channel of the River Test, Hampshire. Data were also collected on stream discharge, water depth, flow velocity and suspended sediment concentrations. Deposition rates followed a seasonal pattern and were maximal during periods of high discharge in the late winter/early spring when suspended sediment concentrations were high. The material deposited in the spawning gravels included silts and fine sands (<250 m) that were transported in suspension and coarser fragments of low density tufa-like material that were transported as bed load. The ecological implications of fine sediment deposition for salmonid egg survival in chalk streams are considered.

  4. Completion techniques for horizontal wells in the Pearsall Austin Chalk

    SciTech Connect

    Pope, C.D.; Handren, P.J. )

    1992-05-01

    Oryx Energy Co. used three basic completion techniques and various combinations of them to complete 20 horizontal wells in the Pearsall Austin Chalk. The completion method selected is based on a general set of guidelines. In this paper additionally, equipment selection and various types of workover operations are reviewed.

  5. Why Chalk Breaks into Three Pieces When Dropped

    ERIC Educational Resources Information Center

    Cross, Rod

    2015-01-01

    It has been the author's experience over many years, no doubt shared by others, that a stick of chalk usually breaks into three pieces when accidentally dropped onto the floor. I rarely gave it any thought, apart from noting that the fundamental mode of vibration of a freely supported, rigid rod has two nodes at an equal distance from each…

  6. Chalk-microfluidic: flooding microsystems with reactive fluids

    NASA Astrophysics Data System (ADS)

    Neuville, Amélie; Dysthe, Dag Kristian; Li, Lei; Hiorth, Aksel

    2014-05-01

    Experiments on core scale and field tests that have been carried out the last decade have clearly shown that water chemistry affects the final oil recovery. However, there is generally no consensus in the scientific community of why additional oil is released. Part of the reason for this is that there are very few in-situ observations of how the water chemistry affects fluid distributions on the pore scale, and/or the pore surface characteristics. In this work, as a first step, our aim is to focus on in-situ observations of single phase flow and interactions at the pore scale. In order to work at this small scale, we first investigate how to control the flow location. We propose to use the same principle as "paper-microfluidic": some areas of the chalk are chemically treated so that no fluid flows inside while other areas let the fluids flow in the chalk pores. Since chalk and paper obviously has different mechanical behavior, we need to adapt this technique. Custom-made microsystems with chalk and calcite will be presented. We will then show experiments with reacting fluids in these microsystems. These experiments are observed using wide field fluorescence microscopy and white light vertical/phase shift interferometric microscopy.

  7. Polymer mud improves chalk gas production and profits

    SciTech Connect

    Cornett, J.E.

    1984-01-01

    A new polymer drilling fluid is being used successfully in the Austin Chalk area of Texas to improve wellbore stability, decrease formation damage and significantly increase production rates. This article discusses development of the fluid, laboratory test results, field performance and benefits to operators.

  8. Controls on fracture distribution in the Giddings Austin Chalk

    SciTech Connect

    Wagner, D.T. )

    1990-09-01

    Fracture distribution in the Giddings Austin Chalk is controlled by both structure and the stratigraphy of the Austin Group. Parameters that most affect reservoir performance include fracture width, height, and spacing, as well as the number of fracture sets and their orientations. Lateral variance of these parameters is a function of structural position, while vertical change is related to stratigraphy. The Austin Chalk productive trend is thought to coincide with the hingeline of the Gulf Coast basin, where extension has been concentrated during subsidence of the basin. Fracturing is attributed to a number of mechanisms including normal faulting, bending over buried structures, gravity creep, differential compaction, and aquathermal pressuring. A change in structural style from faulting to flexure takes place from west to east across the Giddings field, accompanied by a change in fracture distribution. In the west, fractures develop only in close proximity to faults whereas in the east they are more widely distributed over broad warps. Stratigraphic controls include lithology, porosity, bed thickness, and ductility contrast between adjacent beds. The Austin Chalk consists of sparse biomicrite interbedded with marls, shales, and clay seams. In general, thin beds are more highly fractured than thick beds, and clean limestone is more highly fractured than marl or shale. Where the more ductile marls and clays exceed a critical thickness, fractures tend to terminate within individual chalk beds, resulting in barriers to vertical flow within the reservoir.

  9. Nano sized clay detected on chalk particle surfaces

    NASA Astrophysics Data System (ADS)

    Skovbjerg, L. L.; Hassenkam, T.; Makovicky, E.; Hem, C. P.; Yang, M.; Bovet, N.; Stipp, S. L. S.

    2012-12-01

    Chalk is a sedimentary rock consisting mostly of micrometer sized particles of biogenic calcite (CaCO3). It forms the reservoirs for oil in the Danish part of the North Sea and important drinking water aquifers in northern Europe. The interaction between organic molecules and the particle surfaces has a strong influence on the migration of oil in the reservoirs. Adhesion of oil components to chalk particle surfaces is thought to significantly reduce production and efforts are being made to determine the mechanisms behind enhanced/improved oil recovery (EOR/IOR) during water flooding. Aquifers beneath industrial areas can be heavily polluted with organic compounds and similar adsorption mechanisms could influence the geographical extent of the contaminant plume. Chalk, as a sedimentary rock, has been studied extensively for many years but the properties of the particle surfaces, where adsorption takes place, are largely unknown. In this study, we have used atomic force microscopy (AFM) to show that the grain surfaces in offshore and onshore chalk are more heterogeneous than previously assumed. The particles are not simply calcite surfaces but are partially covered by clay that is only 1-4 nm thick. With chemical force mapping (CFM), we have probed the surface using a tip coated with organic molecules to represent a tiny, mono-functionalized oil droplet. The functional groups of the self assembled monolayer on the tip were either -CH3 or -COO-. From maps of adhesion, it is evident that in calcite saturated water, both the polar and the nonpolar functional groups adhere to the nano sized clay particles but not to calcite. This is fundamentally important information for the development of conceptual and chemical models to explain wettability alterations in chalk reservoirs.

  10. Redox conditions in the Late Cretaceous Chalk Sea: the possible use of cerium anomalies as palaeoredox indicators in the Cenomanian and Turonian Chalk of England

    NASA Astrophysics Data System (ADS)

    Jeans, Christopher V.; Wray, David S.; Williams, C. Terry

    2015-09-01

    The cerium anomalies preserved in the Chalk have been investigated as possible palaeoredox indicators of the Late Cretaceous Sea and its sediment. This has been based upon over a hundred new rare earth element analyses of selected samples and grain size fractions from the Chalk. Particular attention has been given to the methodology of differentiating between the cerium anomalies preserved in the bioclastic calcite and those in carbonate-fluorapatite preserved in the acetic acid insoluble residues of chalks. Variations in the cerium anomaly of different particle size fractions of uncemented chalks suggest that fractionation of rare earth elements between the Chalk's seawater and the various organisms that contributed skeletal material to the bioclastic calcite of the Chalk may have occurred. Post-depositional processes of calcite cementation and late diagenetic sulphidisation have had no apparent effect on the cerium anomaly of the acetic acid insoluble residues. The cerium anomalies associated with the acetic acid insoluble residues from (1) an alternating sequence of chalks and marls from Ballard Cliff (Dorset, UK) typical of Milankovitch cyclicity show a marked diagenetic pattern, whereas those from (2) non-volcanic and volcanic marls display a pattern that is best explained by the variations in the availability of phosphorus and the timing of argillisation of volcanic glass during diagenesis. The general conclusion is drawn that the cerium anomalies preserved in the Chalk can provide an insight into the changing palaeoredox conditions in the Late Cretaceous Sea as well as in the pore fluids of its sediments.

  11. Seismic geomorphology of the Danish Chalks, offshore, North Sea

    NASA Astrophysics Data System (ADS)

    Smit, Florian; van Buchem, Frans; Schmidt, Ingelise

    2014-05-01

    The Upper Cretaceous and Lowermost Paleocene chalk deposits of the North Sea Basin constitute a unique phase in the evolution of carbonate facies, through the rock-forming dominance of fine grained calcareous plankton, particularly coccolithophorids. These planktonic organisms were deposited over extensive areas and very often laid down as laterally extensive, regular dm-scale bedded packages, that locally may reach a thickness of up to 1250 m. In the Danish Graben, the depositional conditions for the chalk sedimentation changed dramatically during the middle of the Upper Cretaceous. At this time the basin topography was inverted, radically changing the position of the depocenters and the ocean floor morphology. In uplifted areas local erosion and long phases of non-deposition occurred, whereas in areas of subsidence thick packages of chalk accumulated. Along the newly created highs, mass waste deposition took place at the deca-kilometre scale. In this presentation we will document evidence for the tectonic inversion, and pay particular attention to the rich pallet of geomorphological features that characterise this tectonically active period. This study benefitted from a recently re-processed 3D seismic dataset (6000 km²), and a regional well-log and biostratigraphic dataset. In addition, the seismic interpretation applied advanced seismic interpretation software (PaleoScan™), which uses a patented model grid that links up seismic points and honours interpreted horizon constraints resulting in a seismic Relative Geological Time model. Standard seismic attributes, displayed upon horizons from a 3D RGT model of the chalk package, have shown to be very effective in the illustration and interpretation of complex chalk depositional features. Special attention has been focussed on mass waste deposits around inverted structures and salt diapirs. Several different mass waste complexes have been documented in 3D, illustrating a number of typical features such as

  12. Horizontal wells up odds for profit in Giddings Austin chalk

    SciTech Connect

    Maloy, W.T. )

    1992-02-17

    This paper reports on horizontal drilling in the Giddings field Austin chalk which has significantly improved average well recoveries and more than offset increased drilling costs. Although not the panacea originally promoted, horizontal drilling, in Giddings field, offers economic profits to the average investor. Economic analysis indicates that the typical investor is making money by earning returns in excess of market values. Field-wide development will, therefore, remain active unless oil prices or average well recoveries fall below $12/bbl or 112,000 bbl of oil equivalent (BOE), respectively. The application of technological innovation in the Giddings field may culminate in the drilling of over 2,000 horizontal Austin chalk wells, and has conceivably increased recoverable reserves by 400 million BOE.

  13. Monitoring compaction and compressibility changes in offshore chalk reservoirs

    SciTech Connect

    Dean, G.; Hardy, R. ); Eltvik, P. )

    1994-03-01

    Some of the North Sea's largest and most important oil fields are in chalk reservoirs. In these fields, it is important to measure reservoir compaction and compressibility because compaction can result in platform subsidence. Also, compaction drive is a main drive mechanism in these fields, so an accurate reserves estimate cannot be made without first measuring compressibility. Estimating compaction and reserves is difficult because compressibility changes throughout field life. Installing of accurate, permanent downhole pressure gauges on offshore chalk fields makes it possible to use a new method to monitor compressibility -- measurement of reservoir pressure changes caused by the tide. This tidal-monitoring technique is an in-situ method that can greatly increase compressibility information. It can be used to estimate compressibility and to measure compressibility variation over time. This paper concentrates on application of the tidal-monitoring technique to North Sea chalk reservoirs. However, the method is applicable for any tidal offshore area and can be applied whenever necessary to monitor in-situ rock compressibility. One such application would be if platform subsidence was expected.

  14. Why Chalk Breaks into Three Pieces When Dropped

    NASA Astrophysics Data System (ADS)

    Cross, Rod

    2015-01-01

    It has been the author's experience over many years, no doubt shared by others, that a stick of chalk usually breaks into three pieces when accidentally dropped onto the floor. I rarely gave it any thought, apart from noting that the fundamental mode of vibration of a freely supported, rigid rod has two nodes at an equal distance from each end. For example, a baseball bat has a node in the barrel (the sweet spot) about 15 cm from the end and another node in the handle. However, chalk is not expected to break at the node points, since maximum stress arises at the antinode in the middle of the chalk where bending is a maximum. Richard Feynman described a similar problem with long sticks of spaghetti.1 He found that they always break into three or more pieces when bent slowly beyond their breaking point, rather than simply breaking in half. He was unable to figure out why, although the problem was solved many years later2 and is nicely illustrated by Vollmer and Mollmann.3

  15. Maternal Geophagy of Calabash Chalk on Foetal Cerebral Cortex Histomorphology

    PubMed Central

    EKANEM, Theresa Bassey; EKONG, Moses Bassey; ELUWA, Mokutima Amarachi; IGIRI, Anozeng Oyono; OSIM, Eme Efiom

    2015-01-01

    Background: Calabash chalk, a kaolin-base substance is a common geophagic material mostly consumed by pregnant women. This study investigated its effect on the histomorphology of the foetal cerebral cortex. Methods: Twelve gestating Wistar rats were divided equally into groups 1 and 2. On pregnancy day seven (PD7), group 2 animals were administered 200 mg/kg body weight of calabash chalk suspension, while group 1 animals served as the control and received 1 ml of distilled water, by oral gavages and for 14 days (PD7-PD20). On PD21, the dams were sacrificed, and the foetuses removed, examined for gross malformations, weighed and culled to two foetuses per mother. Their whole brains were excised, weighed and preserved using 10% buffered formalin, and routinely processed by haematoxylin and eosin, and Luxol fast blue methods. Results: The foetuses showed no morphological change, but their mean body weights was higher (p=0.0001). Histomorphological sections of the cerebral cortex showed hypertrophy and hyperplasia of cells in all the cortical layers, with less demonstrated Nissl and higher (p=0.001) cellular population compared with the control group. Conclusion: Calabash chalk cause body weight increase and histomorphological changes in the cerebral cortex of foetuses. PMID:26715904

  16. Horizontal technology helps spark Louisiana`s Austin chalk trend

    SciTech Connect

    Koen, A.D.

    1996-04-29

    A handful of companies paced by some of the most active operators in the US are pressing the limits of horizontal technology to ramp up Cretaceous Austin chalk exploration and development (E and D) across Louisiana. Companies find applications in Louisiana for lessons learned drilling horizontal wells to produce chalk intervals in Texas in Giddings, Pearsall, and Brookeland fields. Continuing advances in horizontal well technology are helping operators deal with deeper, hotter reservoirs in more complex geological settings that typify the chalk in Louisiana. Better horizontal drilling, completion, formation evaluation, and stimulation techniques have enabled operators to produce oil and gas from formations previously thought to be uneconomical. Most of the improved capabilities stem from better horizontal tools. Horizontal drilling breakthroughs include dual powered mud motors and retrievable whipstocks, key links in the ability to drill wells with more than one horizontal lateral. Better geosteering tools have enabled operators to maintain horizontal wellbores in desired intervals by signaling bit positions downhole while drilling. This paper reviews the technology and provides a historical perspective on the various drilling programs which have been completed in this trend. It also makes predictions on future drilling successes.

  17. Fracture detection techniques in the Georgetown and Austin Chalk formations

    SciTech Connect

    Julian, P.J.

    1982-09-01

    This study relates the success of detecting and analyzing naturally fractured systems in the Austin Chalk and Georgetown Formations from log evaluations. The Austin Chalk is composed principally of calcareous unicellular algal remains called cocospheres and their disunited, gearshaped, skeletal remains called cocoliths. The Georgetown Formation is a hard, dense, and finely brittle limestone. Both formations contain matrix porosity, but are dependent on open fracture systems for economical hydrocarbon production. Hence, defining and evaluating the developed fracture systems before setting an expensive casing string is important. The Dual Induction Log and the Compensated Neutron-Formation Density Log offers an economical method of evaluating these fracture systems. Case studies in Robertson, Milam, and Burleson Counties, Texas have shown that fracture systems near the wellbore can be detected. Attempts to determine the existence of hydrocarbons in fracture systems using logs were successful in the Austin Chalk and Georgetown Formations. Full core analyses were also successful in determining the existence of these fracture systems. However, obtaining core samples on all wells as a method of determining fracture systems is not recommended due to the high cost of coring.

  18. Understanding groundwater, surface water, and hyporheic zone biogeochemical processes in a Chalk catchment using fluorescence properties of dissolved and colloidal organic matter

    NASA Astrophysics Data System (ADS)

    Lapworth, D. J.; Gooddy, D. C.; Allen, D.; Old, G. H.

    2009-09-01

    Understanding groundwater-surface water (GW-SW) interaction in Chalk catchments is complicated by the degree of geological heterogeneity. At this study site, in southern United Kingdom, alluvial deposits in the riparian zone can be considered as a patchwork of varying grades and types with an equally varied lateral connectivity. Some display good connection with the river system and others good connection with the groundwater system and, by definition, poorer connectivity with the surface water. By coupling tangential flow fractionation (TFF) with fluorescence analysis we were able to characterize the organic matter in the river and hyporheic zone. There is a significant proportion of particulate and colloidal fluorescent organic matter (FOM) within the river system and at depth within the gravels beneath the river channel. At depth in the hyporheic zone, the surface water inputs are dampened by mixing with deeper groundwater FOM. The shallow (0-0.5 m below river bed) hyporheic zone is highly dynamic as a result of changing surface water inputs from upstream processes. Labile C in the form of protein-like FOM appears to be attenuated preferentially compared to fulvic-like fluorescence in the hyporheic zone compared to the adjacent gravel and sand deposits. These preliminary findings have important implications for understanding nutrient and trace element mobility and attenuation within the groundwater, surface water, and hyporheic zone of permeable Chalk catchments. Fluorescence analysis of dissolved organic matter has been shown to be a useful environmental tracer that can be used in conjunction with other methods to understand GW-SW processes within a permeable Chalk catchment.

  19. Role of shale thickness on vertical connectivity of fractures: application of crack-bridging theory to the Austin Chalk, Texas

    NASA Astrophysics Data System (ADS)

    Rijken, Peggy; Cooke, Michele L.

    2001-07-01

    Contrasting material properties of alternating chalk and shale layers control vertical connectivity of fractures. Our field observations within the Austin Chalk, Texas indicate that: (1) the majority of vertical fractures occur in chalk layers and abut against contacts with shale layers, (2) thicker shale layers have greater resistance to fracture propagation than thinner shale layers. From these observations we hypothesize both the resistance of shale to fracturing and the thickness of shale layers may inhibit fracture propagation across the shale and into the next chalk layer. We model crack propagation within a three-layered system (brittle chalk:fracture resistant shale:brittle chalk). The modeled crack extends across the shale, but closing tractions applied to the crack segment within the shale layer simulate resistance of shale to fracturing. The crack-tip lies a short distance within the unfractured chalk layer simulating a coplanar flaw with potential to propagate. If the stress intensity factor at the flaw exceeds the chalk fracture toughness, the crack propagates, thereby bridging and eventually rupturing the shale layer. For any chalk thickness, there is a critical shale thickness above which fractures cross the shale layer and below which fractures arrest at shale. Finite Element Method (FEM) analysis evaluates the influence of shale ductility within the chalk: shale: chalk system. Although remote and fluid pressure driven fractures produce identical stress intensity factors in elastic chalk/shale systems, lower driving stresses are required to propagate fluid pressure driven fractures through a system ductile shale layers than fractures under remote tension.

  20. Fracture characterization of greater Ekofisk area chalks from core analysis

    SciTech Connect

    Farrell, H.E.

    1988-01-01

    Fracture characteristics are one of the input parameters for both waterflood design and subsidence analysis of the Ekofisk field. The fracture parameters of Maastrichtian age (Tor Formation) and Danian age (Ekofisk Formation) reservoir chalks have been determined from detailed description and analysis of 18 cores. Fracture pattern, mineralization, orientation, and intensity were all logged for the major groups of natural fractures. The fracture characteristics vary with chalf sedimentology. As a result, the fracturing in the Tor and Ekofisk Formation reservoirs shows some fundamental differences. The Tor Formation contains two fracture types. One set, stylolite-associated fractures, form an anastomosing network of nearly vertical extension fractures that extend between 5 and 20 cm from individual stylolites. These fractures occur predominantly in thin debris-flow facies chalks that are typical of the Tor Formation. Pilot waterflood results indicate that this fracture set imparts a permeability anisotropy to the Tor Formation reservoir in the pilot waterflood area. The second fracture set effects both Tor and Ekofisk Formation rocks. These tectonic fractures are conjugate, through-going, and planar, and they dip between 60/sup 0/ and 70/sup 0/. This group of fractures occurs predominantly in massive debris-flow facies chalks that are common in, but not restricted to, the Ekofisk Formation. Fracture orientation data indicate that a radial pattern of tectonic fractures may be present in this field. The field waterflood is being designed to accommodate this highly varied fracture pattern and analyses are under way to determine the possibility of fracture slip and closure during subsidence.

  1. Groundwater recharge dynamics in unsaturated fractured chalk: a case study

    NASA Astrophysics Data System (ADS)

    Cherubini, Claudia; Pastore, Nicola; Giasi, Concetta I.; Allegretti, Nicolaetta M.

    2016-04-01

    The heterogeneity of the unsaturated zone controls its hydraulic response to rainfall and the extent to which pollutants are delayed or attenuated before reaching groundwater. It plays therefore a very important role in the recharge of aquifers and the transfer of pollutants because of the presence of temporary storage zones and preferential flows. A better knowledge of the physical processes in the unsaturated zone would allow an improved assessment of the natural recharge in a heterogeneous aquifer and of its vulnerability to surface-applied pollution. The case study regards the role of the thick unsaturated zone of the Cretaceous chalk aquifer in Picardy (North of France) that controls the hydraulic response to rainfall. In the North Paris Basin, much of the recharge must pass through a regional chalk bed that is composed of a porous matrix with embedded fractures. Different types of conceptual models have been formulated to explain infiltration and recharge processes in the unsaturated fractured rock. The present study analyses the episodic recharge in fractured Chalk aquifer using the kinematic diffusion theory to predict water table fluctuation in response to rainfall. From an analysis of the data, there is the evidence of 1) a seasonal behavior characterized by a constant increase in the water level during the winter/spring period and a recession period, 2) a series of episodic behaviors during the summer/autumn. Kinematic diffusion models are useful for predict preferential fluxes and dynamic conditions. The presented approach conceptualizes the unsaturated flow as a combination of 1) diffusive flow refers to the idealized portion of the pore space of the medium within the flow rate is driven essentially by local gradient of potential; 2) preferential flow by which water moves across macroscopic distances through conduits of macropore length.

  2. Sulfur isotope patterns of iron sulfide and barite nodules in the Upper Cretaceous Chalk of England and their regional significance in the origin of coloured chalks

    NASA Astrophysics Data System (ADS)

    Jeans, Christopher V.; Turchyn, Alexandra V.; Hu, Xu-Fang

    2016-06-01

    The relationship between the development of iron sulfide and barite nodules in the Cenomanian Chalk of England and the presence of a red hematitic pigment has been investigated using sulfur isotopes. In southern England where red and pink chalks are absent, iron sulfide nodules are widespread. Two typical large iron sulfide nodules exhibit δ34S ranging from -48.6‰ at their core to -32.6‰ at their outer margins. In eastern England, where red and pink chalks occur in three main bands, there is an antipathetic relationship between the coloured chalks and the occurrence of iron sulfide or barite nodules. Here iron sulfide, or its oxidised remnants, are restricted to two situations: (1) in association with hard grounds that developed originally in chalks that contained the hematite pigment or its postulated precursor FeOH3, or (2) in regional sulfidization zones that cut across the stratigraphy. In the Cenomanian Chalk exposed in the cliffs at Speeton, Yorkshire, pyrite and marcasite (both iron sulfide) nodules range in δ34S from -34.7‰ to +40.0‰. In the lower part of the section δ34S vary from -34.8‰ to +7.8‰, a single barite nodule has δ34S between +26.9‰ and +29.9‰. In the middle part of the section δ34S ranges from +23.8‰ to +40.0‰. In the sulfidization zones that cut across the Cenomanian Chalk of Lincolnshire the iron sulfide nodules are typically heavily weathered but these may contain patches of unoxidised pyrite. In these zones, δ34S ranges from -32.9‰ to +7.9‰. The cross-cutting zones of sulfidization in eastern England are linked to three basement faults - the Flamborough Head Fault Zone, the Caistor Fault and the postulated Wash Line of Jeans (1980) - that have affected the deposition of the Chalk. It is argued that these faults have been both the conduits by which allochthonous fluids - rich in hydrogen sulfide/sulfate, hydrocarbons and possibly charged with sulfate-reducing bacteria - have penetrated the Cenomanian Chalk as

  3. Stimulation results in the Giddings (Austin Chalk) field

    SciTech Connect

    Meehan, D.N.

    1995-05-01

    So called ``water-fracs`` have obtained excellent results in the Austin Chalk formation of Giddings field. This inexpensive treatment uses high volumes of water but no proppant. The reasons the treatment is successful include imbibition, gravity drainage, skin damage removal, and repressurization of the reservoir to enhance recovery. Union Pacific Resources Co. (UPRC) has treated about 250 vertical and 150 horizontal wells with very high economic success rates. Incremental recoveries from horizontal well water fracs alone exceed 5 million bbl of oil equivalent (6 Mcf = 1 bbl).

  4. Formation evaluation in the Texas Cretaceous chalk trend

    SciTech Connect

    Frost, E. Jr.; Stedman, D.; Fertl, W.H.

    1982-06-01

    Skilled formation evaluation is essential to economic well completions in the Cretaceous carbonate trend of South and Central Texas. The Austin chalk and Buda lime wells within this trend are known for high initial production rates followed by rapid production decline probably due to completion in zones of insufficient porosity and permeability. Therefore, the proper use of geophysical wireline data to locate fractures and determine fracture quality and hydrocarbon potential prior to setting casing is an essential element in evaluating the economics of any given well. This work details current successful evaluation procedures utilized in the trend. 11 refs.

  5. A geological assessment: What`s ahead for Louisiana Austin chalk

    SciTech Connect

    Maloy, W.T.

    1997-06-02

    Both noteworthy and recent, the extension of the Austin chalk horizontal drilling play into Louisiana has been as closely watched as it has been controversial. The play has been controversial for the critics who claim the Louisiana chalk boom is simply the latest chapter in the chalk`s boom and bust history. The play is closely watched by chalk enthusiasts who have seen Louisiana horizontal wells yield as much as 80,000 bbl of oil and 250 MMcf of gas in a single month. Who is right? How will the play develop? This article presents a geological assessment of the play and offers some insights into the future of horizontal drilling in Louisiana.

  6. A unique Austin Chalk reservoir, Van field, Van Zandt County, Texas

    SciTech Connect

    Lowe, J.T. )

    1990-09-01

    Significant shallow oil production from the Austin Chalk was established in the Van field, Van Zandt County, in East Texas in the late 1980s. The Van field structure is a complexly faulted domal anticline created by salt intrusion. The Woodbine sands, which underlie the Austin Chalk, have been and continue to be the predominant reservoir rocks in the field. Evidence indicates that faults provided vertical conduits for migration of Woodbine oil into the Austin Chalk where it was trapped along the structural crest. The most prolific Austin Chalk production is on the upthrown side of the main field fault, as is the Woodbine. The Austin Chalk is a soft, white to light gray limestone composed mostly of coccoliths with some pelecypods. Unlike the Austin Chalk in the Giddings and Pearsall fields, the chalk at Van was not as deeply buried and therefore did not become brittle and susceptible to tensional or cryptic fracturing. The shallow burial in the Van field was also important in that it allowed the chalk to retain primary microporosity. The production comes entirely from this primary porosity. In addition to the structural position and underlying oil source from the Woodbine, the depositional environment and associated lithofacies are also keys to the reservoir quality in the Van field as demonstrated by cores from the upthrown and downthrown (less productive) sides of the main field fault. It appears that at the time of Austin Chalk deposition, the main field fault was active and caused the upthrown side to be a structural high and a more agreeable environment for benthonic organisms such as pelecypods and worms. The resulting bioturbation enhanced the reservoir's permeability enough to allow migration and entrapment of the oil. Future success in exploration for analogous Austin Chalk reservoirs will require the combination of a favorable environment of deposition, a nearby Woodbine oil source, and a faulted trap that will provide the conduit for migration.

  7. Horizontal gas-condensate find brightens Louisiana chalk outlook

    SciTech Connect

    Petzet, G.A.

    1994-12-19

    A ray of hope may have appeared in the Louisiana portion of the Cretaceous Austin chalk trend after several years of expensive disappointment. OXY USA Inc. plans to use dual leg horizontal wells to develop a fracture chalk reservoir named Masters Creek field in Rapides Parish. The state has approved four 1,920 acre spacing units, one of which contains OXY's A1 Monroe well. The A1 Monroe flowed 6.6 MMcfd of gas with 2,162 b/d of 48[degree] gravity condensate, not oil as previously reported, through a 26/64 in. choke with 6,196 psi flowing tubing pressure from a single southward 4,000 ft horizontal leg at 14,803 ft true vertical depth. Bottomhole pressure is 13,100 psi. OXY called A1 Monroe a significant discovery and said it has additional exploration acreage blocks along the trend. Louisiana exempts production from horizontal wells from state severance tax until all project costs are returned. The paper briefly discusses OXY's program.

  8. Fracture development and mechanical stratigraphy of Austin Chalk, Texas

    SciTech Connect

    Corbett, K.; Friedman, M.; Spang, J.

    1987-01-01

    The mechanical stratigraphy of the Upper Cretaceous Austin Chalk is established from study of fracture intensity along its outcrop trend from Dallas to San Antonio and westward to Langtry, Texas, and in the subsurface from study of cores and/or fracture identification logs from 30 wells. Three mechanical-stratigraphic units are recognized. Representative samples from the three mechanical-stratigraphic units were experimentally shortened, dry, at 10, 17, 34, and 70 MPa confining pressure, at 24/sup 0/C, and at a strain rate of 2.5 x 10/sup -4/ sec/sup -1/ to determine if the relative mechanical behavior observed at the surface could be extrapolated into the subsurface at different simulated burial depths. SEM photomicrographs of undeformed specimens show that smectite and other clays are distributed as large (30 ..mu..m), discrete, amorphous, concentrated masses throughout the chalk. They are comminuted along the induced fracture surfaces where their grain size is 0.5 ..mu..m or less. These observations suggest that smectite acts as a soft-inclusion, localizing shear failure and corresponding weakening the material. 9 figures, 5 tables.

  9. Assessment of groundwater usage at Chalk Point power plant. Final report

    SciTech Connect

    Not Available

    1982-07-01

    In order to quantify the usage of ground water in an operating electric power plant, a study was initiated in 1978 aimed at determining where in the energy conversion process ground water is used and to suggest, if possible, alternate means for providing this water and/or methods to reduce consumption. The Chalk Point Plant was selected for this study because of its difference in fuel source (coal and oil), and because of its high consumption of ground water (approximately 800,000 to 1,200,000 gallons per day). Located at the confluence of the Patuxent River and Swanson Creek in the southeast corner of Prince George's County, Maryland, it consists of three operating units, with a fourth unit under construction during the survey time. (unit 4 has recently become operational). With the cooperation of the Potomac Electric Power Company, the plant was selected for study and was instrumented with several flow meters. Over a two-year period, this plant has been monitored to provide the information needed to make an assessment of the rates, nature, and methods of water usage in an operating power plant.

  10. Application of thematic mapper imagery to oil exploration in Austin Chalk, central Gulf Coast basin, Texas

    SciTech Connect

    Reid, W.M.

    1988-02-01

    One of the newest major oil plays in the Gulf Coast basin, the Austin Chalk reportedly produces in three belts: an updip belt, where production is from fractured chalk in structurally high positions along faults above 7000 ft; a shallow downdip belt, where the chalk is uniformly saturated with oil from 7000 to 9000 ft; and a deeper downdip belt saturated with gas and condensate below 9000 ft. The updip fields usually occur on the southeastern, upthrown side of the Luling, Mexia, and Charlotte fault zones. Production is from fractures that connect the relatively sparse matrix pores with more permeable fracture systems. The fractures resulted from regional extensional stress during the opening of the Gulf Coast basin on the divergent margin of the North American plate during the Laramide orogeny. The fractures are more common in the more brittle chalk than in the overlying Navarro and underlying Eagle Ford shales, which are less brittle. The oil in the updip traps in the chalk may have been generated in place downdip, and migrated updip along the extension fractures into the updip traps during or after the Laramide orogeny. A fairway of previously unmapped updip faults and drag folds has been mapped using Thematic Mapper imagery and seismic, structural, and resistivity maps near the Nixon field, Burleson County, Texas. This fairway, prospective for oil from the Austin Chalk, contains wells reported to produce from the Austin Chalk which lie along lineaments and linear features on the Thematic Mapper imagery and faults in the seismic and structure maps.

  11. Laboratory determination of effective stress laws for deformation and permeability of chalk

    SciTech Connect

    Teufel, L W; Warpinski, N R

    1990-01-01

    Laboratory deformation and permeability measurements have been made on chalk samples from Ekofisk area fields as a function of confining stress and pore pressure to determine the effective stress laws for chalk. An understanding of the effective stress law is essential to obtain correct reservoir-property data from core analysis and is critical for reservoir management studies and reservoir compaction models. A powerful statistical technique known as the response surface method has been used to analyze our laboratory data determine the form of the effective stress law for deformation and permeability. Experiments were conducted on chalk samples that had a range of porosities from 15% to 36%, because porosity is the dominant intrinsic property that effects deformation and permeability behavior of chalk. Deformation of a 36% porosity chalk was highly nonlinear, but the effective stress law was linear, with {alpha} equal to about unity. Lower-porosity samples showed linear strain behavior and a linear effective stress law with {alpha} as low as 0.74. Analysis of the effective stress law for permeability is presented only for the lowest porosity chalk sample because changes in permeability in the higher-porosity chalk samples due to increasing confining stress or pore pressure were not were large enough, to deduce meaningful effective stress relationships. 15 refs., 8 figs., 2 tabs.

  12. The influence of water and supercritical CO2 on the failure behavior of chalk

    NASA Astrophysics Data System (ADS)

    Liteanu, E.; Spiers, C. J.; de Bresser, J. H. P.

    2013-06-01

    Reduction of compressive strength by injection of water into chalk is a well-known mechanism responsible for increased compaction in chalk reservoirs. This raises the question of whether such effects might be enhanced in the context of long-term storage of CO2 or of CO2 injection for enhanced oil and gas recovery (EOR/EGR) purposes. Therefore, data regarding the effect of supercritical CO2 on the mechanical behavior of chalk are needed. The effect of supercritical CO2 on the short-term failure behavior of wet chalk was accordingly investigated by means of conventional triaxial deformation experiments, performed on Maastrichtian chalk cores under dry conditions, in the presence of saturated chalk solution and using CO2-saturated solution at temperatures simulating reservoir conditions (20-80 °C) and effective confining pressures up to 7 MPa. Increasing temperature from 20 to 80 °C did not show any significant effects on the strength of the dry samples. Addition of aqueous solution to the samples led to drastic weakening of the chalk, the effect being more pronounced at high effective confining pressures (Peff > 3 MPa). Addition of 10 MPa supercritical CO2 to wet samples did not produce any significant additional effect in comparison with the wet samples. All samples showed a yield strength envelope characterized by shear failure at low effective mean stresses giving way to a compaction cap at high mean stresses. The weakening effect of aqueous solution was explained in terms of a reduction in frictional resistance of the material, due to water-enhanced grain-contact cracking, and perhaps pressure solution, with a possible contribution by disjoining pressure effects caused by water adsorption. While CO2 does not seem to reduce short-term failure strength of wet chalk, processes such as intergranular pressure solution have to be considered for assessing mechanical stability of chalk in the context of long-term CO2 storage or EOR/EGR operations.

  13. Seismic architecture of the Chalk Group from onshore reflection data in eastern Denmark

    NASA Astrophysics Data System (ADS)

    Moreau, Julien; Anderskouv, Kresten; Boldreel, Lars Ole; Boussaha, Myriam; Nielsen, Lars; Stemmerik, Lars; Surlyk, Finn; Thibault, Nicolas

    2013-04-01

    The Upper Cretaceous-Danian chalk is well exposed in the 14 km long coastal cliff of Stevns Klint (eastern Denmark). The cliff is a world renowned for its spectacular exposure of the Cretaceous-Palaeogene boundary. Based on regional geological knowledge of the field and cores, the characteristics of the Chalk Group have been well constrained. Distinct sedimentary facies have been encountered; the sedimentology, the biostratigraphy, the diagenesis and the reservoir properties have been thoroughly investigated and reported. Stimulated by the intensive geological research, the field studies have been completed with the acquisition of an extensive set of subsurface data. The data include high resolution 2D multichannel seismics onshore and offshore, a seismic refraction profile, two entirely cored boreholes including wireline logs, GPR cross-hole tomography, thermographic analysis, etc. We intend to compile and merge the geological and geophysical datasets to investigate the variation of the Chalk Group properties and their signature in the subsurface. In this communication, the seismic reflection data are being analysed. Very high resolution litho-, bio- and cyclostratigraphy can be correlated with the seismic stratigraphy. Several seismic facies are identified in the Chalk Group: the 'transparent' (white chalk), the stratified (marl-chalk alternations), the crudely stratified (flint-rich chalk) and the hummocky (bryozoan mounds). The units notably vary in thickness at a relatively small scale. The variations confirm the complex shelf organisation which was highly influenced by bottom currents. In addition to the stratigraphic observations, peculiar deformation structures can be recognised. The area has been supposedly tectonically stable since deposition as the coastal cliff lacks fault offset but the succession has been uplifted of c. 1 km. The main fracture patterns are associated with the recent unloading of the ice, opening shallow horizontal fractures

  14. Diffusive parameters of tritiated water and uranium in chalk

    SciTech Connect

    Descostes, M.; Pili, E.; Felix, O.; Frasca, B.; Radwan, J.; Juery, A.

    2012-07-15

    The Cretaceous Chalk of North-western Europe exhibits a double porosity (matrix and fracture) providing pathways for both slow and rapid flow of water. The present study aims at understanding and predicting the contaminant transfer properties through a significant section of this formation, with a particular emphasis on diffusion. This requires to study the nature of porosity and to perform diffusion experiments in representative samples using uranium and tritiated water (HTO), respectively taken as a reactive tracer and an inert one. The diffusive parameters, i.e. the accessible porosity and the effective diffusion coefficient were determined. Additional information was obtained with mercury porosimetry, gravimetric water content, textural and mineralogical characterization. The diffusion tests performed with HTO appear to be the best method to measure the total accessible porosity in any type of porous media, especially those having large pore size distributions. Our study demonstrates that classical gravimetric water content measurements are not sensitive to the reduction in pore size as opposed to HTO diffusion tests because capillary water is not extracted by conventional gravimetric method but can still be probed by diffusion experiments. We found effective diffusion coefficients D{sub e}(U(VI)) near 4 x 10{sup -10} m{sup 2}s{sup -1}). The slower migration of U(VI) compared to HTO indicates sorption, with R{sub d}(U(VI)) from 100 to 360 mL g{sup -1}. These values are one order of magnitude larger than other determinations of the U(VI) sorption coefficient because only the matrix porosity is concerned here. The migration of U(VI) in chalk is only limited by sorption on ancillary Fe-Pb-bearing minerals. Transport of HTO and U(VI) is independent of the porosity distribution. Uranium diffusion in the chalk matrix porosity is fast enough to allow the total invasion of the pore space within characteristic time scales of the order of 1000 years. This results in a

  15. How to drill and complete Austin chalk wells

    SciTech Connect

    Coffman, C.A.

    1982-07-01

    Problems in drilling and completing Texas wells with high-pressure gas and lower-pressure zones (where the mud system is lost into the pay zone) are described; wells that have a gas zone in the lower zone and oil zone in the upper; wells with an oil zone in upper and lower zones but with different gravity weight and color; and wells where high-pressure gas kicks are found in the upper zone and returns are lost in the lower. Topics include isolating the pay zone and cementing the liner. Whether to frac or acidize is determined by checking fractures, fluorescences, and gas shows. Goal is to reach the fault in the chalk.

  16. Austin Chalk: cross-link gel water, slick water fracs common in Giddings field

    SciTech Connect

    Mickey, V.

    1981-05-01

    Of the approx. 600 wells drilled in the Giddings field, Austin Chalk trend in the last year, most were probably completed by cross-link gel fracs or slick water fracs. Although open hole completions are not uncommon in the chalk, they are not really practical in most situations, given the 600 to 800 ft of gross pay usually encountered in the Austin Chalk trend. Most of the open hole completions occur when an operator takes a kick while drilling and decides to drop a mud pill over the zone, run casing above it, cement it in and produce the interval open hole. Chalk wells are subject to kick at any time during drilling because of natural fracturing systems throughout the trend. Mud weights are generally fairly light for faster drilling, approx. 9.4 to 9.8 lb, depending on the particular area.

  17. The Austin Chalk--Drilling and completion techniques-Marcelina Creek Field study

    SciTech Connect

    Betz, C.A.

    1982-09-01

    Exxon Company, U.S.A. has spent considerable time and effort learning how to minimize formation damage in the lost returns prone and clay sensitive Austin Chalk formation. To date, Exxon has successfully drilled 24 Austin Chalk wells in the Marcelina Creek Field in Wilson County, Texas, utilizing a variety of drilling and completion techniques in an effort to determine the optimum method of drilling and completing Austin Chalk wells. This paper describes these different techniques and reviews actual results. Although Exxon has not concluded which drilling and completion technique yields optimum Austin Chalk wells in this field, this paper attempts to develop a correlation between well productivity and the type of drilling and completion technique used.

  18. Trace fossils and paleoenvironments of lower and middle Austin Chalk (upper Cretaceous), north-central Texas

    SciTech Connect

    Dawson, W.C. ); Reaser, D.F. )

    1990-09-01

    Outcrops of lower and middle Austin Chalk in the vicinity of Cedar Hill and Waxahachie, Texas (designated site of the Superconducting Super Collider), are profusely bioturbated. The lower Austin (Coniacian) disconformably overlies the Eagle Ford Shale (Turonian) and consists of about 60 m of medium- to thick-bedded indurated chalk with thin intervening marls. The middle Austin (Santonian) is composed of about 65 m of thick-bedded marl containing thin beds of argillaceous chalk. Both chalk and marl units are moderately to intensely bioturbated. However, ichnofossils are more conspicuous in chalks where multiple episodes of burrowing are recognizable. Early formed burrows (indistinct mottles) represent the initial softground Austin substrate. Later generations of well-preserved burrows record a post-compaction (dewatered) firmground substrate. No hardgrounds have been recognized. The abundance and diversity of ichnofossils in Austin strata are in marked contrast to the paucity of other megafauna, except large inoceramids. Planolites, Teichichnus, Thalassinoides, and Chondrites are the predominant ichnogenera in the lower Austin; these forms are superimposed on a background of nondiagnostic, irregularly shaped mottles. Some strata contain well-preserved J-, S-, T-, U-, Y-, and X-shaped traces having menicus fillings. These subhorizontal, endogenic, full-relief burrows are typically infilled with dark gray (pyritic) chalk. Locally, pyrite or Fe-oxide-filled vertical tubes are preserved. Many traces have been deformed by compaction. The middle Austin contains Planolites, Chondrites, Thalassinoides, Pseudobilobites, and both small- and large-diameter, sinuous, horizontal burrows. These ichnofossils are infilled with chalk or comminuted shells and are more resistant to weathering than the surrounding middle Austin marl. Intensely burrowed horizons occur in association with distinctive Fe-stained chalk beds.

  19. The effect of chalk on the finger-hold friction coefficient in rock climbing.

    PubMed

    Amca, Arif Mithat; Vigouroux, Laurent; Aritan, Serdar; Berton, Eric

    2012-11-01

    The main purpose of this study was to examine the effect of chalk on the friction coefficient between climber's fingers and two different rock types (sandstone and limestone). The secondary purpose was to investigate the effects of humidity and temperature on the friction coefficient and on the influence of chalk. Eleven experienced climbers took part in this study and 42 test sessions were performed. Participants hung from holds which were fixed on a specially designed hang board. The inclination of the hang board was progressively increased until the climber's hand slipped from the holds. The angle of the hang board was simultaneously recorded by using a gyroscopic sensor and the friction coefficient was calculated at the moment of slip. The results showed that there was a significant positive effect of chalk on the coefficient of friction (+18.7% on limestone and +21.6% on sandstone). Moreover sandstone had a higher coefficient of friction than limestone (+15.6% without chalk, +18.4% with chalk). These results confirmed climbers' belief that chalk enhances friction. However, no correlation with humidity/temperature and friction coefficient was noted which suggested that additional parameters should be considered in order to understand the effects of climate on finger friction in rock climbing. PMID:23259237

  20. 3D characterization of the fracture network in a deformed chalk reservoir analogue: The Lagerdorf case

    SciTech Connect

    Koestler, A.G.; Reksten, K.

    1994-12-31

    Quantitative descriptions of the 3D fracture networks in terms of connectivity, fracture types, fracture surface roughness and flow characteristics are necessary for reservoir evaluation, management, and enhanced oil recovery programs of fractured reservoirs. For a period of 2 years, a research project focused on an analogue to fractured chalk reservoirs excellently exposed near Laegerdorf, NW Germany. Upper Cretaceous chalk has been uplifted and deformed by an underlying salt diapir, and is now exploited for the cement industry. In the production wall of a quarry, the fracture network of the deformed chalk was characterized and mapped at different scales. The wall was scraped off as chalk exploitation proceeded, continuously revealing new sections through the faulted and fractured chalk body. A 230 m long part of the 35m high production wall was investigated during its recess of 25m. The large amount of fracture data were analyzed with respect to parameters such as fracture density distribution, orientation- and length distribution, and in terms of the representativity of data sets collected from restricted rock volumes. This 3D description and analysis of a fracture network revealed quantitative generic parameters of importance for modeling chalk reservoirs with less data and lower data quality.

  1. Reactive transport modelling of groundwater chemistry in a chalk aquifer at the watershed scale.

    PubMed

    Mangeret, A; De Windt, L; Crançon, P

    2012-09-01

    This study investigates thermodynamics and kinetics of water-rock interactions in a carbonate aquifer at the watershed scale. A reactive transport model is applied to the unconfined chalk aquifer of the Champagne Mounts (France), by considering both the chalk matrix and the interconnected fracture network. Major element concentrations and main chemical parameters calculated in groundwater and their evolution along flow lines are in fair agreement with field data. A relative homogeneity of the aquifer baseline chemistry is rapidly reached in terms of pH, alkalinity and Ca concentration since calcite equilibrium is achieved over the first metres of the vadose zone. However, incongruent chalk dissolution slowly releases Ba, Mg and Sr in groundwater. Introducing dilution effect by rainwater infiltration and a local occurrence of dolomite improves the agreement between modelling and field data. The dissolution of illite and opal-CT, controlling K and SiO(2) concentrations in the model, can be approximately tackled by classical kinetic rate laws, but not the incongruent chalk dissolution. An apparent kinetic rate has therefore been fitted on field data by inverse modelling: 1.5×10(-5) mol(chalk)L (-1) water year (-1). Sensitivity analysis indicates that the CO(2) partial pressure of the unsaturated zone is a critical parameter for modelling the baseline chemistry over the whole chalk aquifer. PMID:22797192

  2. Trace elemental analysis of school chalk using energy dispersive X-ray florescence spectroscopy (ED-XRF)

    SciTech Connect

    Maruthi, Y. A.; Das, N. Lakshmana; Ramprasad, S.; Ram, S. S.; Sudarshan, M.

    2015-08-28

    The present studies focus the quantitative analysis of elements in school chalk to ensure the safety of its use. The elements like Calcium (Ca), Aluminum (Al), Iron (Fe), Silicon (Si) and Chromium (Cr) were analyzed from settled chalk dust samples collected from five classrooms (CD-1) and also from another set of unused chalk samples collected from local market (CD-2) using Energy Dispersive X-Ray florescence(ED-XRF) spectroscopy. Presence of these elements in significant concentrations in school chalk confirmed that, it is an irritant and occupational hazard. It is suggested to use protective equipments like filtered mask for mouth, nose and chalk holders. This study also suggested using the advanced mode of techniques like Digital boards, marker boards and power point presentations to mitigate the occupational hazard for classroom chalk.

  3. Trace elemental analysis of school chalk using energy dispersive X-ray florescence spectroscopy (ED-XRF)

    NASA Astrophysics Data System (ADS)

    Maruthi, Y. A.; Das, N. Lakshmana; Ramprasad, S.; Ram, S. S.; Sudarshan, M.

    2015-08-01

    The present studies focus the quantitative analysis of elements in school chalk to ensure the safety of its use. The elements like Calcium (Ca), Aluminum (Al), Iron (Fe), Silicon (Si) and Chromium (Cr) were analyzed from settled chalk dust samples collected from five classrooms (CD-1) and also from another set of unused chalk samples collected from local market (CD-2) using Energy Dispersive X-Ray florescence(ED-XRF) spectroscopy. Presence of these elements in significant concentrations in school chalk confirmed that, it is an irritant and occupational hazard. It is suggested to use protective equipments like filtered mask for mouth, nose and chalk holders. This study also suggested using the advanced mode of techniques like Digital boards, marker boards and power point presentations to mitigate the occupational hazard for classroom chalk

  4. Colloid facilitated transport of lanthanides through discrete fractures in chalk

    NASA Astrophysics Data System (ADS)

    Tran, Emily; Klein Ben-David, Ofra; Teutsch, Nadya; Weisbrod, Noam

    2015-04-01

    Geological disposal of high-level radioactive waste is the internationally agreed-upon, long term solution for the disposal of long lived radionuclides and spent fuel. Eventually, corrosion of the waste canisters may lead to leakage of their hazardous contents, and the radionuclides can ultimately make their way into groundwater and pose a threat to the biosphere. Engineered bentonite barriers placed around nuclear waste repositories are generally considered sufficient to impede the transport of radionuclides from their storage location to the groundwater. However, colloidal-sized mobile bentonite particles eroding from these barriers have come under investigation as a potential transport vector for radionuclides sorbed to them. In addition, the presence of organic matter in groundwater has been shown to additionally facilitate the uptake of radionuclides by the clay colloids. This study aims to evaluate the transport behaviors of radionuclides in colloid-facilitated transport through a fractured chalk matrix and under geochemical conditions representative of the Negev desert, Israel. Lanthanides are considered an acceptable substitute to actinides for research on radionuclide transportation due to their similar chemical behavior. In this study, the migration of Ce both with and without colloidal particles was explored and compared to the migration of a conservative tracer (bromide). Tracer solutions containing known concentrations of Ce, bentonite colloids, humic acid and bromide were prepared in a matrix solution containing salt concentrations representative of that of the average rain water found in the Negev. These solutions were then injected into a flow system constructed around a naturally fractured chalk core. Samples were analyzed for Ce and Br using ICP-MS, and colloid concentrations were determined using spectrophotographic analysis. Breakthrough curves comparing the rates of transportation of each tracer were obtained, allowing for comparison of

  5. Origin distribution and alteration of organic matter and generation and migration of hydrocarbons in Austin Chalk, Upper Cretaceous, Southeastern Texas

    NASA Astrophysics Data System (ADS)

    Grabowski, G. J., Jr.

    1981-08-01

    The Austin Chalk is an impure onshore chalk that was deposited on a ramp marginal to the Gulf of Mexico during the Late Cretaceous. Basinal chalks are organic rich, commonly containing 0.5-5.0% amorphous, sapropelic kerogen derived from marine organic matter with only trace amounts of terrestial kerogen. Less organic matter was deposited and perserved in oxygenated shallow water, and fresh-water diagenesis oxidized the organic matter on outcrop. In each sample, the kerogen is concentrated in microstylolites, with organic fluids segregated in micropores in the chalk.

  6. Current oil and gas production from North American Upper Cretaceous chalks

    USGS Publications Warehouse

    Scholle, Peter A.

    1977-01-01

    Production of oil and natural gas from North American chalks has increased significantly during the past five years, spurred by the prolific production from North Sea chalks, as well as by higher prices and improved production technology. Chalk reservoirs have been discovered in the Gulf Coast in the Austin Group, Saratoga and Annona Chalks, Ozan Formation, Selma Group, Monroe gas rock (an informal unit of Navarro age), and other Upper Cretaceous units. In the Western Interior, production has been obtained from the Cretaceous Niobrara and Greenhorn Formations. Significant, though subcommercial, discoveries of natural gas and gas condensate also have been made in the Upper Cretaceous Wyandot Formation on the Scotian Shelf of eastern Canada. All North American chalk units share a similar depositional and diagenetic history. The chalks consist primarily of whole and fragmented coccoliths with subordinate planktonic and benthonic Foraminifera, inoceramid prisms, oysters, and other skeletal grains. Most have between 10 and 35 percent HCl-insoluble residue, predominantly clay. Deposition was principally below wave base in tens to hundreds of meters of water. The diagenetic history of a chalk is critical in determining its reservoir potential. All chalk has a stable composition (low-Mg calcite) and very high primary porosity. With subsequent burial, mechanical and chemical (solution-transfer) compaction can reduce or completely eliminate pore space. The degree of loss of primary porosity in chalk sections is normally a direct function of the maximum depth to which it has been buried. Pore-water chemistry, pore-fluid pressures, and tectonic stresses also influence rates of cementation. Oil or gas reservoirs of North American chalk fall into three main groups: 1. Areas with thin overburden and significant primary porosity retention (for example, Niobrara Formation of Kansas and eastern Colorado). 2. Areas with thicker overburden but considerable fracturing. Here primary

  7. Effects of the restoration mortar on chalk stone buildings

    NASA Astrophysics Data System (ADS)

    Ion, R. M.; Teodorescu, S.; Ştirbescu, R. M.; Dulamă, I. D.; Şuică-Bunghez, I. R.; Bucurică, I. A.; Fierăscu, R. C.; Fierscu, I.; Ion, M. L.

    2016-06-01

    The monument buildings as components of cultural heritage are exposed to degradation of surfaces and chemical and mechanical degradation, often associated to soiling and irreversible deterioration of the building. In many conservative and restorative works, a cement-based mortar was used without knowing all the adverse effects of this material on the building. This paper deals with the study of the effects of natural cement used in restorative works in the particular case of the Basarabi-Murfatlar Churches Ensemble. Cement-based materials exposed to sulfate present in the chalk stone - gypsum (CaSO4.2H2O), can induce signs of deterioration, due to ettringite ([Ca3Al (OH)612H2O]2(SO4)32H2O) or thaumasite (Ca3[Si(OH)612H2O](CO3)SO4) formation. These phases contribute to strain within the material, inducing expansion, strength loss, spalling and severe degradation. Several combined techniques (XRD, EDXRF, ICP-AES, SEM, EDS, sulphates content, FT-IR and Raman analysis were carried out to put into evidence the effects of them on the building walls.

  8. Pressure build-up characteristics in Austin Chalk wells

    SciTech Connect

    Claycomb, E.

    1983-02-28

    Pressure build-up data collected from wells in the Giddings Austin Chalk field have been analyzed through use of techniques currently available to the petroleum industry. The slope of ..delta..T vs. ..delta..P, along with a Horner graph and knowledge of well history, should indicate which method of analysis is applicable. The operator should know what kind of stimulation, if any; was performed on the well and the degree of success. A Horner graph, along with a graph of ..delta..T vs. ..delta..P should be plotted as a matter of course. Information gained from proper analysis of build-up data may be used both in well diagnosis and in prediction of well performance. In well diagnosis, a pressure buildup-falloff test is one of the few means of analyzing a problem well. Properly analyzed build-up data will give estimates of average reservoir pressure, in situ permeability, and fracture length. These data will aid in fracture optimization, reserve prediction, and performance prediction.

  9. Absolute paleobathymetry of Upper Cretaceous chalks based on ostracodes - Evidence from the Demopolis Chalk (Campanian and Maastrichtian) of the northern Gulf Coastal Plain

    SciTech Connect

    Puckett, T.M. )

    1991-05-01

    The presence of abundant and diverse sighted ostracodes in chalk and marl of the Demopolis Chalk (Campanian and Maastrichtian) in Alabama and Mississippi strongly suggests that the Late Cretaceous sea floor was within the photic zone. The maximum depth of deposition is calculated from an equation based on eye morphology and efficiency and estimates of the vertical light attenuation. In this equation, K, the vertical light attenuation coefficient, is the most critical variable because it is the divisor for the rest of the equation. Rates of accumulation of coccoliths during the Cretaceous are estimated and are on the same order as those in modern areas of high phytoplankton production, suggesting similar pigment and coccolith concentrations in the water column. Values of K are known for a wide range of water masses and pigment concentrations, including areas of high phytoplankton production; thus light attenuation through the Cretaceous seas can be estimated reliably. Waters in which attenuation is due only to biogenic matter-conditions that result in deposition of relatively pure chalk-have values of K ranging between 0.2 and 0.3. Waters rich in phytoplankton and mud-conditions that result in deposition of marl-have K values as great as 0.5. Substituting these values for K results in depth range of 65 to 90 m for deposition of chalk and depth of 35 m for deposition of marl. These depth values suggest that deposition of many Cretaceous chalks and marls around the world were deposited under relatively shallow conditions.

  10. Improving UK Chalk hydrometeorology across spatial scales using a small hydrometeorological network

    NASA Astrophysics Data System (ADS)

    Rosolem, Rafael; Iwema, Joost; Rahman, Mostaquimur; Desilets, Darin; Koltermann da Silva, Juliana

    2016-04-01

    Chalk in the UK acts as a primary aquifer providing up to 80% of the public water supply locally. Chalk outcrops are located over most of southern and eastern England. Despite its importance, the characterization of Chalk in hydrometeorological models is still very limited. There is a need for a comprehensive and coherent integration of observations and modeling efforts across spatial scales for better understanding Chalk hydrometeorology. Here we introduce the "A MUlti-scale Soil moisture-Evapotranspiration Dynamics" (AMUSED) project. AMUSED goal is to better identify the key dominant processes controlling changes in soil moisture and surface fluxes (e.g., evapotranspiration) across spatial scales by combining ground-based observations with hydrometeorological models and satellite remote sensing products. The AMUSED observational platform consists of three sites located in Upper Chalk region of the Lambourn Catchment located in southern England covering approximately 2 square-km characterized by distinct combinations of soil and vegetation types. The network includes standard meteorological measurements, an eddy covariance system for turbulent fluxes and cosmic-ray neutron sensors for integrated soil moisture estimates at intermediate scales. Here we present our initial results from our three sites.

  11. Reactive transport modelling of groundwater chemistry in a chalk aquifer at the watershed scale

    NASA Astrophysics Data System (ADS)

    Mangeret, A.; De Windt, L.; Crançon, P.

    2012-09-01

    This study investigates thermodynamics and kinetics of water-rock interactions in a carbonate aquifer at the watershed scale. A reactive transport model is applied to the unconfined chalk aquifer of the Champagne Mounts (France), by considering both the chalk matrix and the interconnected fracture network. Major element concentrations and main chemical parameters calculated in groundwater and their evolution along flow lines are in fair agreement with field data. A relative homogeneity of the aquifer baseline chemistry is rapidly reached in terms of pH, alkalinity and Ca concentration since calcite equilibrium is achieved over the first metres of the vadose zone. However, incongruent chalk dissolution slowly releases Ba, Mg and Sr in groundwater. Introducing dilution effect by rainwater infiltration and a local occurrence of dolomite improves the agreement between modelling and field data. The dissolution of illite and opal-CT, controlling K and SiO2 concentrations in the model, can be approximately tackled by classical kinetic rate laws, but not the incongruent chalk dissolution. An apparent kinetic rate has therefore been fitted on field data by inverse modelling: 1.5 × 10- 5 molchalk L - 1water year - 1. Sensitivity analysis indicates that the CO2 partial pressure of the unsaturated zone is a critical parameter for modelling the baseline chemistry over the whole chalk aquifer.

  12. Mineralization of 2,4-D, mecoprop, isoproturon and terbuthylazine in a chalk aquifer.

    PubMed

    Kristensen, G B; Sørensen, S R; Aamand, J

    2001-06-01

    The potential to mineralize 2,4-dichlorophenoxyacetic acid (2,4-D), mecoprop, isoproturon and terbuthylazine was studied in soil and aquifer chalk sampled at an agricultural field near Aalborg, Denmark. Laboratory microcosms were incubated for 258 days under aerobic conditions at 10 degrees C with soil and chalk from 0.15-4.45 m below the surface. The [ring-U-14C]-labeled herbicides were added to obtain a concentration of 6 micrograms kg-1 and mineralization was measured as evolved [14C]carbon dioxide. The herbicides were readily mineralized in soil from the plough layer, except for terbuthylazine, which was mineralized only to a limited extent. In the chalk, lag periods of at least 40 days were observed, and a maximum of 51%, 33% and 6% of the added 2,4-D, mecoprop and isoproturon, respectively, were recovered as [14C]carbon dioxide. Large variations in both rate and extent of mineralization were observed within replicates in chalk. No mineralization of terbuthylazine in chalk was observed. As a measure of the general metabolic activity towards aromatic compounds, [ring-U-14C]-benzoic acid was included. It was readily mineralized at all depths. PMID:11407030

  13. Application of thematic mapper imagery to oil exploration in Austin Chalk, Central Gulf Coast basin, Texas

    SciTech Connect

    Reid, W.M.

    1988-01-01

    One of the newest major oil plays in the Gulf Coast basin, the Austin Chalk reportedly produces in three belts: an updip belt, where production is from fractured chalk in structurally high positions along faults above 7,000 ft; a shallow downdip belt, where the chalk is uniformly saturated with oil from 7,000 to 9,000 ft; and a deeper downdip belt saturated with gas and condensate below 9,000 ft. The updip fields usually occur on the southeastern, upthrown side of the Luling, Mexia, and Charlotte fault zones. Production is from fractures that connect the relatively sparse matrix pores with more permeable fracture systems. The fractures resulted from regional extensional stress during the opening of the Gulf Coast basin on the divergent margin of the North American plate during the Laramide orogeny. The fractures are more common in the more brittle chalk than in the overlying Navarro and underlying Eagle Ford shales, which are less brittle. The oil in the updip traps in the chalk may have been generated in place downdip, and migrated updip along the extension fractures into the updip traps during or after the Laramide orogeny.

  14. Decay-Series Disequilibria in a Chalk Aquifer : Characterisation of Water-Rock Interaction

    NASA Astrophysics Data System (ADS)

    Hubert, A.; Bourdon, B.; Pili, E.

    2003-12-01

    We have studied uranium-series disequilibria in a chalk aquifer and the unsaturated zone above it in order to characterise the time scales of radionuclide migration from the water recharge zone of the aquifer to the nearby river. Our field area is located in Champagne (France). The aquifer is characterized by a double porosity : matrix and fracture, providing both a fast and a slow pathways for water flow. We have collected both carbonate rocks and groundwater samples from boreholes and spring and river water from the same area. Rock/water interaction inside the aquifer induces dissolution and reprecipitation of carbonates, together with a mobilization of uranium, and (-recoil effect results in preferential mobilization of daughter nuclides. We have measured uranium and thorium isotopes for carbonates samples from the aquifer by TIMS and multi-collection ICP-MS. The fractionation of uranium and thorium isotopes is distinctive in the various parts of the aquifer. Rock samples from the saturated zone show a depletion in 234U with a (234U/238U) ratio ranging from 0.945 to 0.993 (ñ 0.005). This indicates that uranium 234U has been released by rock/water interaction over the last million year. Nevertheless, rock samples from the water table oscillation zone display a (234U/238U) activity ratio greater than 1 and range from 1.002 to 1.052 (ñ 0.005), suggesting uranium reprecipitation possibly by a redox front. (230Th/238U) ratios range from 1.25 to 1.59 (ñ 0.03) in both the saturated and vadose zone, whilst (230Th/232Th) ratios vary from 1.89 to 5.68 (ñ 0.05) with the highest values for the water table oscillation zone. The 238U-230Th system suggests the existence of a iron oxihydroxide and/or silicate phases which influence the redeposition and/or adsorption of elements inside the zone of water oscillation. Modelling is in progress in order to determine leaching rate of the radionuclides in the substratum together with the adsorption/desorption rate constants on

  15. Dynamic depositional and early diagenetic processes in a deep-water shelf setting, upper cretaceous Austin Chalk, North Texas

    SciTech Connect

    Hovorka, S.D.; Nance, H.S.

    1994-12-31

    The Austin Chalk of north Texas was deposited on a deep-water shelf north of the Sea Marcos Platform during a worldwide Coniacian and Santonian sea-level highstand. Transgressive (lowermost lower Austin Chalk), highstand (uppermost lower Austin Chalk), and regressive (middle and upper Austin Chalk) phases of cyclic chalk and marl sedimentation are recognized in excavations and tunnels created in Ellis County for the Superconducting Super Collider provide new evidence of sediment transport during Austin Chalk deposition. During transgression, bottom currents syndepositionally reworked nannoplankton oozes, incising channels as much as 120 ft across and 8 ft deep. Weakly burrowed channel fills having preservation of fine lamination document rapid infilling. Channel fills are composed of pyritized and carbonized wood and Inoceramus lag deposits, pellets, echinoderm fragments, and globigerinid grainstones, and coccolith ooze. During maximum highstand, bottom reworking was suppressed. Detrital content of highstand marls is low (>20 percent); organic content is high (1.4 to 3.5 percent). Coccolith preservation is excellent because of minimal diagenetic alteration. Regression is marked by resumed channel cutting and storm-bed winnowing in the middle and upper Austin Chalk. Suppressed resistivity log response and recessive weathering characteristics of the middle Austin Chalk are not primarily related to depositional environment but rather to increased input of volcanic ash during the accumulation of this interval. Early stabilization of ash produced clay-coated microfabrics in sediments that are otherwise similar to the transgressive deposits.

  16. Chalk, What Chalk?

    ERIC Educational Resources Information Center

    Butler, Loren L.

    2004-01-01

    When it comes to technological wizardry in the classroom, interactive whiteboards stand on the cutting edge of the future. Students seem innately able to manipulate any type of computerized equipment, and, more important, they are highly motivated to engage in "techno-discovery." It is the duty of every educator to facilitate further discovery and…

  17. The surface reactivity of chalk (biogenic calcite) with hydrophilic and hydrophobic functional groups

    NASA Astrophysics Data System (ADS)

    Okhrimenko, D. V.; Dalby, K. N.; Skovbjerg, L. L.; Bovet, N.; Christensen, J. H.; Stipp, S. L. S.

    2014-03-01

    The surface properties of calcium carbonate minerals play an important role in a number of industrial and biological processes. Properties such as wettability and adsorption control liquid-solid interface behaviour and thus have a strong influence on processes such as biomineralisation, remediation of aquifers and oil recovery. We investigated how two model molecules of different polarity, namely water and ethanol, interact with reservoir and outcrop chalk samples and we compared their behaviour with that of pure, inorganically precipitated calcite. Thermodynamic quantities, such as the work of wetting, surface energy and isosteric adsorption enthalpy, were determined from vapour adsorption isotherms. The chalks were studied fresh and after extraction of organic residues that were originally present in these samples. The work of wetting correlates with the amount of organic matter present in the chalk samples but we observed a fundamental difference between the adsorption properties of chalk and pure, inorganically precipitated calcite toward the less polar, ethanol molecule. Further analysis of the chemical composition of the organic matter extracted from the chalk samples was made by gas chromatography (GC-MS). Monitoring surface composition by X-ray photoelectron spectroscopy (XPS) before and after extraction of the organic material, and with atomic force microscopy (AFM), showed that nanometer sized clay crystals observed on the chalk particle surfaces could be an important part of the reason for the differences. Removal of the extractable portion of the hydrocarbons liberates adsorption sites that have different wetting properties than the rest of the chalk and these have an energy distribution that is similar to clays. Thus, the results exemplify the complexity of biogenic calcite adsorption behaviour and demonstrate that chalk wetting in drinking water aquifers as well as oil reservoirs is controlled partly by the nanoparticles of clay that have grown on the

  18. Authigenic kaolinite and associated pyrite in chalk of the Cretaceous Niobrara Formation, Eastern Colorado.

    USGS Publications Warehouse

    Pollastro, R.M.

    1981-01-01

    Cores from the Smoky Hill Chalk Member of the Cretaceous Niobrara Formation have several zones containing authigenic kaolinite as spherical, moldic, polycrystalline aggregates that occur within single or multichambered foraminiferal tests and are commonly associated with framboidal pyrite. Such kaolinite is inferred to result from volcanic ash deposited during chalk sedimentation. Shortly after burial, a colloidal aluminous gel or solution formed from the unstable ash and moved into organic-rich foraminiferal tests, where sulfate-reducing bacteria created a favorable microenvironment for the simultaneous crystallization of kaolinite and pyrite. -Author

  19. Effective-stress-law behavior of Austin chalk rocks for deformation and fracture conductivity

    SciTech Connect

    Warpinski, N.R.; Teufel, L.W.

    1994-08-01

    Austin chalk core has been tested to determine the effective law for deformation of the matrix material and the stress-sensitive conductivity of the natural fractures. For deformation behavior, two samples provided data on the variations of the poroelastic parameter, {alpha}, for Austin chalk, giving values around 0.4. The effective-stress-law behavior of a Saratoga limestone sample was also measured for the purpose of obtaining a comparison with a somewhat more porous carbonate rock. {alpha} for this rock was found to be near 0.9. The low {alpha} for the Austin chalk suggests that stresses in the reservoir, or around the wellbore, will not change much with changes in pore pressure, as the contribution of the fluid pressure is small. Three natural fractures from the Austin chalk were tested, but two of the fractures were very tight and probably do not contribute much to production. The third sample was highly conductive and showed some stress sensitivity with a factor of three reduction in conductivity over a net stress increase of 3000 psi. Natural fractures also showed a propensity for permanent damage when net stressed exceeded about 3000 psi. This damage was irreversible and significantly affected conductivity. {alpha} was difficult to determine and most tests were inconclusive, although the results from one sample suggested that {alpha} was near unity.

  20. Maastrichtian ammonites chiefly from the Prairie Bluff Chalk in Alabama and Mississippi

    USGS Publications Warehouse

    Cobban, W.A.; Kennedy, W.J.

    1995-01-01

    The Prairie Bluff Chalk of Alabama and Mississippi yields a diverse ammonite fauna of Maastrichtian age. Twenty-eight species, of which three are new, are recorded. The bulk of the fauna can be referred to a Discoscaphites conradi assemblage zone, but some elements in the fauna are significantly older. -Authors

  1. Reservoir fracture mapping using microearthquakes: Austin chalk, Giddings field, TX and 76 field, Clinton Co., KY

    SciTech Connect

    Phillips, W.S.; Rutledge, J.T.; Fairbanks, T.D.

    1996-12-31

    Patterns of microearthquakes detected downhole defined fracture orientation and extent in the Austin chalk, Giddings field, TX and the 76 field, Clinton Co., KY. We collected over 480 and 770 microearthquakes during hydraulic stimulation at two sites in the Austin chalk, and over 3200 during primary production in Clinton Co. Data were of high enough quality that 20%, 31% and 53% of the events could be located, respectively. Reflected waves constrained microearthquakes to the stimulated depths at the base of the Austin chalk. In plan view, microearthquakes defined elongate fracture zones extending from the stimulation wells parallel to the regional fracture trend. However, widths of the stimulated zones differed by a factor of live between the two Austin chalk sites, indicating a large difference in the population of ancillary fractures. Post-stimulation production was much higher from the wider zone. At Clinton Co., microearthquakes defined low-angle, reverse-fault fracture zones above and below a producing zone. Associations with depleted production intervals indicated the mapped fractures had been previously drained. Drilling showed that the fractures currently contain brine. The seismic behavior was consistent with poroelastic models that predicted slight increases in compressive stress above and below the drained volume.

  2. Reservoir fracture mapping using microearthquakes: Austin chalk, Giddings field, TX and 76 field, Clinton Co., KY

    SciTech Connect

    Phillips, W.S.; Rutledge, J.T.; Gardner, T.L.; Fairbanks, T.D.; Miller, M.E.; Schuessler, B.K.

    1996-11-01

    Patterns of microearthquakes detected downhole defined fracture orientation and extent in the Austin chalk, Giddings field, TX and the 76 field, Clinton Co., KY. We collected over 480 and 770 microearthquakes during hydraulic stimulation at two sites in the Austin chalk, and over 3200 during primary production in Clinton Co. Data were of high enough quality that 20%, 31% and 53% of the events could be located, respectively. Reflected waves constrained microearthquakes to the stimulated depths at the base of the Austin chalk. In plan view, microearthquakes defined elongate fracture zones extending from the stimulation wells parallel to the regional fracture trend. However, widths of the stimulated zones differed by a factor of five between the two Austin chalk sites, indicating a large difference in the population of ancillary fractures. Post-stimulation production was much higher from the wider zone. At Clinton Co., microearthquakes defined low-angle, reverse-fault fracture zones above and below a producing zone. Associations with depleted production intervals indicated the mapped fractures had been previously drained. Drilling showed that the fractures currently contain brine. The seismic behavior was consistent with poroelastic models that predicted slight increases in compressive stress above and below the drained volume.

  3. 24. ARAIII Reactor building ARA608 interior. Camera facing south. Chalk ...

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

    24. ARA-III Reactor building ARA-608 interior. Camera facing south. Chalk marks on wall indicate presence or absence of spot contamination. Ineel photo no. 3-2. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

  4. Drilling and production aspects of horizontal wells in the Austin Chalk

    SciTech Connect

    Sheikholeslami, B.A.; Scholhman, B.W.; Seidel, F.A.; Button, D.M. )

    1991-07-01

    This paper discusses testing of horizontal technology for use in the highly fractured Giddings oil field. Three short-and seven medium-radius wells were drilled successfully in the Austin Chalk formation. The paper discusses well plans, bottomhole assemblies, trajectory control, telemetry, mud systems, hydraulics, hole cleaning, casing design, cementing, problems encountered, formation evaluation, completions, and reservoir response.

  5. Assessment of fracture-induced anisotropy in the Austin Chalk Formation (Upper Cretaceous), central Texas

    SciTech Connect

    Edwards, D.A. )

    1990-05-01

    This study relates geophysical and geological data to the detection of fractures and their influence on the movement of fluid in the Atco Member of the Austin Chalk in central Texas. In areas of production, the Austin Chalk has very low matrix permeabilities, with hydrocarbons confined to zones of near-vertical, stress-aligned fractures. Horizontal drilling has been estimated to increase per well reserves in the Austin Chalk from 75,000 bbl and 82 mmcf to 500,000 bbl and 500 mmcf. The objective of deviated wells in the Austin Chalk is to intersect at right angles as many of the hydrocarbon-prone fracture zones as possible. Therefore, the detection and description of these fracture zones prior to drilling is critical. Fractures have been proven to influence the velocities of shear waves. To assess shear wave velocities in different directions, several shear wave refraction and three-component vertical seismic profiles have been acquired. These data provided a measure of the fracture-induced shear wave anisotropy and an indication of the dominant fracture trend. Other data, including azimuthal resistivity surveys, cores, and aerial photographs, provided additional control for evaluating the fractures. The final phase of the study compares the geophysical and geological interpretations to the result of shallow groundwater pumping tests. The pumping tests have been conducted in vertical boreholes and were designed to evaluate the influence of the fracturing on fluid movement.

  6. Ichnology and paleosubstrates of Austin Chalk (Cretaceous) outcrops: Southern Dallas and Ellis Counties, Texas

    SciTech Connect

    Dawson, W.C. ); Reaser, D.F. )

    1991-03-01

    Ichnofossils are abundant in outcrops of the Austin Chalk near Waxahachie, Texas (designated site of the Super-Conducting Super Collider). The abundance and diversity of ichnofossils in Austin strata contrast with the paucity of other macrofossils, except large inoceramids. The lower Austin Chalk (Coniacian) disconformably overlies the Eagle Ford Shale (Turonian). Planolites, Thalassinoides, and Chondrites are conspicuous in the lower Austin. Some lower Austin strata contain well-preserved burrows having menicus fillings. However, most lower Austin ichnofossils are poorly preserved and have compacted. The middle Austin Marl and upper Austin Chalk (Santonain) contain Planolites, Chondrites, Thalassinoides, and Pseudobilobites. Several thin, intensely burrowed, Fe-stained, horizons within the middle Austin represent omission surfaces having postomission Thalassinoides. The upper Austin disconformably underlies the Taylor Marl (Campanian). The Austin-Taylor contact is a Rhizocorallium-infested omission surface overlain by a condensed bed of phosphatic and pyritic bioclasts. Upper Austin occurrences of Rhizocorallium and Pseudobilobites are unique for North American Cretaceous chalks. Based on cross-cutting relationships and differences in morphology, diameter, and burrow-filling sediments, numerous ichnospecies of Thalassinoides are discernable throughout the Austin. Variations in preservation quality exhibited by successive generations of ichnofossils record progressive changes in substrate consistency. Earliest formed burrows have diffuse outlines representing an initial thixotropic (softground) Austin substrate. Subsequent generations of burrows have more distinct outlines recording a gradual increase in substrate firmness. Paleo-firmgrounds are common in Austin outcrops; evidence of hardgrounds is lacking. The Thalassinoides-dominated Austin ichnoassemblage represents an inner shelf paleoenvironment.

  7. The surface reactivity of chalk (biogenic calcite) with hydrophilic and hydrophobic functional groups

    NASA Astrophysics Data System (ADS)

    Okhrimenko, D. V.; Dalby, K. N.; Skovbjerg, L. L.; Bovet, N.; Christensen, J. H.; Stipp, S. L. S.

    2014-03-01

    The surface properties of calcium carbonate minerals play an important role in a number of industrial and biological processes. Properties such as wettability and adsorption control liquid-solid interface behaviour and thus have a strong influence on processes such as biomineralisation, remediation of aquifers and oil recovery. We investigated how two model molecules of different polarity, namely water and ethanol, interact with reservoir and outcrop chalk samples and we compared their behaviour with that of pure, inorganically precipitated calcite. Thermodynamic quantities, such as the work of wetting, surface energy and isosteric adsorption enthalpy, were determined from vapour adsorption isotherms. The chalks were studied fresh and after extraction of organic residues that were originally present in these samples. The work of wetting correlates with the amount of organic matter present in the chalk samples but we observed a fundamental difference between the adsorption properties of chalk and pure, inorganically precipitated calcite toward the less polar, ethanol molecule. Further analysis of the chemical composition of the organic matter extracted from the chalk samples was made by gas chromatography (GC-MS). Monitoring surface composition by X-ray photoelectron spectroscopy (XPS) before and after extraction of the organic material, and with atomic force microscopy (AFM), showed that nanometer sized clay crystals observed on the chalk particle surfaces could be an important part of the reason for the differences. Removal of the extractable portion of the hydrocarbons liberates adsorption sites that have different wetting properties than the rest of the chalk and these have an energy distribution that is similar to clays. Thus, the results exemplify the complexity of biogenic calcite adsorption behaviour and demonstrate that chalk wetting in drinking water aquifers as well as oil reservoirs is controlled partly by the nanoparticles of clay that have grown on the

  8. Full-waveform Inversion of Crosshole GPR Data Collected in Strongly Heterogeneous Chalk: Challenges and Pitfalls

    NASA Astrophysics Data System (ADS)

    Keskinen, Johanna; Looms, Majken C.; Nielsen, Lars; Klotzsche, Anja; van der Kruk, Jan; Moreau, Julien; Stemmerik, Lars; Holliger, Klaus

    2015-04-01

    Chalk is an important reservoir rock for hydrocarbons and for groundwater resources for many major cities. Therefore, this rock type has been extensively investigated using both geological and geophysical methods. Many applications of crosshole GPR tomography rely on the ray approximation and corresponding inversions of first break traveltimes and/or maximum first-cycle amplitudes. Due to the inherent limitations associated with such approaches, the resulting models tend to be overly smooth and cannot adequately capture the small-scale heterogeneities. In contrast, the full-waveform inversion uses all the information contained in the data and is able to provide significantly improved images. Here, we apply full-waveform inversion to crosshole GPR data to image strong heterogeneity of the chalk related to changes in lithology and porosity. We have collected a crosshole tomography dataset in an old chalk quarry in Eastern Denmark. Based on core data (including plug samples and televiewer logging data) collected in our four ~15-m-deep boreholes and results from previous related studies, it is apparent that the studied chalk is strongly heterogeneous. The upper ~7 m consist of variable coarse-grained chalk layers with numerous flint nodules. The lower half of the studied section appears to be finer-grained and contains less flint. However, still significant porosity variations are also detected in the lower half. In general, the water-saturated (watertable depth ~2 m) chalk is characterized by high porosities, and thus low velocities and high attenuation, while the flint is essentially non-porous and has correspondingly high velocities and low attenuation. Together these characteristics form a strongly heterogeneous medium, which is challenging for the full-waveform inversion to recover. Here, we address the importance of (i) adequate starting models, both in terms of the dielectric permittivity and the electrical conductivity, (ii) the estimation of the source wavelet

  9. Late Maastrichtian chalk mounds, Stevns Klint, Denmark — Combined physical and biogenic structures

    NASA Astrophysics Data System (ADS)

    Anderskouv, Kresten; Damholt, Tove; Surlyk, Finn

    2007-08-01

    Upper Maastrichtian chalk exposed at the Sigerslev quarry, Stevns Klint, Denmark is characterized by wavy and mound-like bedding geometries outlined by bands of black flint nodules. Four morphological elements are recognized, although bedding geometries are highly variable: southward migrating mounds, eastward migrating mounds, chalk waves and evenly bedded chalk. The mounds are interpreted as having been formed by currents carrying fine-grained suspended sediment which was primarily deposited on the up-current mound flanks. Bryozoans were prolific on the up-current flanks and mound summits, which stabilized the mounds, increased bed roughness and the overall accumulation rate. However, accumulation thicknesses do not correlate consistently with bryozoan density. The bryozoans were therefore important for the formation of the mounds, but the distribution of bryozoans did not solely determine depositional thickness across a mound and thus mound growth pattern. Relatively long wavelength wavy-bedded chalk show gentle convex-up geometries and would probably be described as sediment waves if recognized in seismic sections. The chalk waves were deposited under weaker current velocities than those active during mound formation. The exposed succession is topped by more evenly bedded chalk which was deposited by quiet pelagic fall-out of fine-grained material. The whole succession was deposited on the upper part of the northern flank of a large WNW-ESE trending 3 km wide depositional ridge with an amplitude of 35-40 m formed by contour-parallel WNW-ward flowing bottom currents. The mounds may have been deposited by regional bottom currents, or by spill-over currents from the valley south of the large ridge. The succession was deposited during varying bottom current intensities and the depositional architecture indicates a complex and dynamic environment. The depositional style seems to be controlled by the interplay and relative importance of two end-member processes

  10. Occurrence of oil in the Austin Chalk at Van field, Van Zandt County, Texas: A unique geologic setting

    SciTech Connect

    Lowe, J.T.; Carrington, D.B. )

    1990-09-01

    The Austin Chalk is buried to a depth of only 2,100-2,500 ft and has retained primary microporosity unlike the typical deep fractured chalk reservoirs. The Van structure is a complexly faulted domal anticline created by salt intrusion and is approximately 2,000 ft higher than surrounding structures in the area. A major northwest-dipping fault acts as the primary trapping mechanism. The field has produced 0.5 billion BO from thick Woodbine sands since its discovery in 1929. Occurrence of oil in the Austin Chalk has been known since the field discovery, but prior completions were low rate oil producers. Recent development of a large fracture stimulation technique has resulted in increased production rates of up to 300 BOPD. The Austin Chalk reservoir limits were determined by isopaching feet of minimum productive resistivity having porosity above a cutoff value. The resistivity/porosity isopach showed a direct correlation between Austin Chalk productivity and the Austin Chalk structure and faulting pattern. Structural evidence along with oil typing indicate that the oil in the Austin Chalk has migrated upward along fault planes and through fault juxtaposition from the Woodbine sands 200 ft below the Austin Chalk. Thin-section and scanning electron microscopy work performed on conventional cores showed that the Van Austin Chalk formation is a very fine grained limestone composed primarily of coccoliths. Various amounts of detrital illite clay are present in the coccolith matrix. All effective porosity is micro-intergranular and ranges from 15 to 35%. Based on the core analyses, the main porosity reducing agent and therefore control on reservoir quality is the amount of detrital clay present filling the micropores. Permeability is very low with values ranging from 0.01 to 1.5 md. There is no evidence of significant natural fractures in the core. Artificial fractures are therefore required to create the permeability needed to sustain commercial production rates.

  11. Laboratory measurements of the electrokinetic and electrochemical potential in chalk, with application to monitoring of saline intrusion in the UK chalk aquifer

    NASA Astrophysics Data System (ADS)

    MacAllister, D.; Jackson, M.; Butler, A. P.; Vinogradov, J.

    2012-12-01

    Saline intrusion is a global phenomenon affecting the availability of freshwater in coastal aquifers. The aim of this work is to investigate whether measurements of spontaneous potential (SP) can be used to monitor the intrusion of seawater into coastal aquifers, with specific application to the chalk aquifer near Brighton on the south coast of the UK. SP arises to maintain electrical neutrality when a separation of charge occurs due to gradients in pressure (electrokinetic or streaming potential), concentration (electrochemical potential) and temperature (thermoelectric potential). Concentration gradients are a characteristic feature of saline intrusion and may give rise to a measureable electrochemical potential (EC). In addition the electrokinetic potential (EK) will arise during abstraction and up-coning of the saline front. The intruding saline front could therefore be detected and monitored continuously, with SP measurements in boreholes and at the surface providing dense monitoring in space and time. To determine the likely magnitude of EK and EC signals during saline intrusion into the chalk aquifer, we measured EK and EC potentials in samples of Seaford chalk saturated with (i) natural, potable groundwater from the aquifer and (ii) seawater sampled from the English Channel. The EK coupling coefficient, which relates the gradient in voltage to the gradient in water pressure when the total current is zero, was found to be -60 mV/MPa in samples saturated with groundwater. In seawater saturated samples it was found to be only -1 mV/MPa. This result agrees with earlier work suggesting the EK potential is suppressed in high salinity environments due to a compressed electrical double layer. The EK coupling coefficient was negative in both cases, suggesting that the surface charge of Seaford chalk is negative when in contact with groundwater and seawater. The electrochemical experiments involved establishing a concentration gradient across the chalk samples

  12. Sequential vein growth with fault displacement: An example from the Austin Chalk Formation, Texas

    NASA Astrophysics Data System (ADS)

    Lee, Young-Joon; Wiltschko, David V.; Grossman, Ethan L.; Morse, John W.; Lamb, William M.

    1997-10-01

    To determine the opening and precipitation history and characteristics of vein-forming fluids, analyses of oxygen and carbon isotopes and trace elements were carried out on multilayered crack-seal calcite veins in the Austin Chalk Formation near San Antonio, Texas. The veins developed within the normal fault zones possessing unique chemical and textural characteristics which indicate sequential vein development. They are composed of alternating millimeter- to submillimeter-thick calcite veinlets and host lithons, occasionally crosscut by coarse, equant-grained secondary calcite veins. Regular changes in δ18O (e.g., -2.6 to -5.6‰, Pee Dee belemnite (PDB)) of the calcite veinlets along the length of veins suggest that the individual calcite veinlets were sequentially developed. A systematic δ18O decrease in the vein opening direction primarily resulted from a continuous increase in temperature of the ascending fluids delivered to the Austin Chalk. Relatively constant δ13C (approximately +1.4±0.4‰, PDB) for the multilayered veins and most secondary veins indicates that the composition of fluids from which the calcite veins precipitated was initially buffered by the bulk chalk. There is no spatial variation in trace element composition of the calcite veinlets along the length of veins. Low Sr concentrations in both calcite veinlets and secondary veins relative to those of the host chalk reflect a low partition coefficient of Sr in calcite during vein formation. Normal faults in the Cretaceous Austin Chalk were conduits to upwardly mobile vein-forming fluids.

  13. Validation of Non-Invasive Waste Assay System (Gamma Box Counter) Performance at AECL Whiteshell Laboratories - 13136

    SciTech Connect

    Attas, E.M.; Bialas, E.; Rhodes, M.J.

    2013-07-01

    Low-level radioactive waste (LLW) in solid form, resulting from decommissioning and operations activities at AECL's Whiteshell Laboratories (WL), is packaged in B-25 and B-1000 standard waste containers and characterized before it is shipped to an on-site interim storage facility, pending AECL decisions on long term management of its LLW. Assay of the waste packages before shipment contributes to an inventory of the interim storage facility and provides data to support acceptance at a future repository. A key characterization step is a gamma spectrometric measurement carried out under standard conditions using an automated, multi-detector Waste Assay System (WAS), purchased from Antech Corporation. A combination of ORTEC gamma acquisition software and custom software is used in this system to incorporate multiple measurements from two collimated high-resolution detectors. The software corrects the intensities of the gamma spectral lines for geometry and attenuation, and generates a table of calculated activities or limits of detection for a user-defined list of radioisotopes that may potentially be present. Validation of WAS performance was a prerequisite to routine operation. Documentation of the validation process provides assurance of the quality of the results produced, which may be needed one or two decades after they were generated. Aspects of the validation included setting up a quality control routine, measurements of standard point sources in reproducible positions, study of the gamma background, optimization of user-selectable software parameters, investigation of the effect of non-uniform distribution of materials and radionuclides, and comparison of results with measurements made using other gamma detector systems designed to assay bulk materials. The following key components of the validation process have been established. A daily quality control routine has been instituted, to verify stability of the gamma detector operation and the background levels

  14. Three-dimensional analytic model of the magnetic field for the Chalk River Superconducting Cyclotron

    SciTech Connect

    Davies, W.G.; Lee-Whiting, G.E.; Douglas, S.R.; Pusch, G.D.

    1994-07-01

    A three-dimensional analytic model of the magnetic field for the TASCC cyclotron that satisfies Maxwell`s equations exactly has been constructed for use with the new differential-algebra orbit-dynamics code. The model includes: (1) the superconducting coils; (2) the saturated iron poles; (3) the partially saturated yoke; (4) the saturated-iron trim rods. Lines of dipole density along the edges of the hills account for the non-uniformities and edge effects and along with three yoke constants constitute the only free parameters.

  15. Geological environment of karst within chalk using airborne time domain electromagnetic data cross-interpreted with boreholes

    NASA Astrophysics Data System (ADS)

    Reninger, P.-A.; Martelet, G.; Lasseur, E.; Beccaletto, L.; Deparis, J.; Perrin, J.; Chen, Y.

    2014-07-01

    The ability of airborne Time Domain ElectroMagnetic (TDEM) to image plurikilometric chalk heterogeneities and its implications for the development of a karstic system is addressed in this study. A heliborne TDEM survey was conducted around Courtenay (France) over the Paris Basin Upper Cretaceous chalk. This aquifer is known as a highly weathered and karstified horizon both strongly modify chalk petrophysical properties. Numerous boreholes and one recently reprocessed seismic line were used in order to strengthen TDEM interpretations. We performed cross statistics between boreholes and the resistivity model. This allowed defining empirical resistivity ranges corresponding to the main geological formations within the area. We were therefore able to map large scale heterogeneities in the chalk over the study area. First, the TDEM method highlighted probable weathering corridors in the chalk, related to the tectonic activity, consistent with faults previously interpreted in the seismics at deeper levels. Second, it was possible to image a large scale undulating geometry in the chalk with a SW-NE orientation, this direction is consistent throughout the Paris Basin, and well defined on the cliffs of Normandy (Channel coast, north of France). This geometry has revealed two separate chalk deposits C1 and C2 in Courtenay area: C1 is more resistive than C2. The resistivity model has then been compared to piezometric measurements acquired as part of previous hydrological studies. The karstic drainage appears to be developed within C1 chalk deposit and most of the piezometric domes seem to be associated to intermediate resistivity zones in C1, interpreted as weathered. According to the results obtained from this study, we were able to suggest a geological framework for the development of Courtenay karstic system.

  16. US DOE-AECL cooperative program for development of high-level radioactive waste container fabrication, closure, and inspection techniques

    SciTech Connect

    Russell, E.W.

    1990-06-01

    The US Department of Energy (DOE) and Atomic Energy of Canada Limited (AECL) plan to initiate a cooperative research program on development of manufacturing processes for high-level radioactive waste containers. This joint program will benefit both countries in the development of processes for the fabrication, final closure in a hot-cell, and certification of the containers. Program activity objectives can be summarized as follows: to support the selection of suitable container fabrication, final closure, and inspection techniques for the candidate materials and container designs that are under development or are being considered in the US and Canadian repository programs; and to investigate these techniques for alternate materials and/or container designs, to be determined in future optimization studies relating to long-term performance of the waste packages. The program participants will carry out this work in a conditional phased approach, and the scope of work for subsequent years will evolve subject to developments in earlier years. The overall term of this cooperative program is planned to run roughly three years. 5 refs., 2 tabs.

  17. NMR response of non-reservoir fluids in sandstone and chalk.

    PubMed

    van der Zwaag, C H; Stallmach, F; Skjetne, T; Veliyulin, E

    2001-01-01

    Transverse (T2) NMR relaxation time at 2 MHz proton resonance frequency was measured on core plug samples from two different lithologies, sandstone and chalk, before and after exposure to selected drilling fluids. The results show that NMR signal response was significantly altered after displacing 50% of the original pore fluids, crude oil and water, by drilling fluid filtrate. Relaxation spectra of the rock samples invaded by water-based filtrate shift to significantly shorter T2-values. This shift yields an underestimation of the free-fluid volumes when selecting cut-off values of 33 ms and 100 ms for sandstone and chalk, respectively. In opposite, rock samples affected by oil-based filtrate respond with a signal indicating significantly larger free-fluid volumes than present before exposure. NMR-permeability calculated based on the Timur-Coates Free Fluid model altered in some cases by one order of magnitude. PMID:11445352

  18. Results of blue crab studies at Chalk Point. Final report 1978-1979

    SciTech Connect

    Souza, P.A.; Polgar, T.T.; Miller, R.E.; Holland, A.F.

    1980-11-01

    This report summarizes the findings of two years of blue crab tagging studies conducted in the Patuxent estuary near the Chalk Point power plant. This report is organized in the following manner: An introduction and objectives section defines the objectives of the blue crab study, discusses the modes of interaction between blue crabs and power plant operations, and discusses the life history characteristics of blue crabs. A study methods section provides detailed information on tagging and capture operations and on analysis methods. A results section presents the major findings of the study. A discussion and conclusions section interprets and discusses major findings and defines the impacts of power plant operations at Chalk Point on blue crab populations in the Patuxent estuary. A list of references is included.

  19. Evaluation of auxiliary tempering pump effectiveness at Chalk Point Steam Electric Station

    SciTech Connect

    Wendling, L.C.; Holland, A.F.

    1989-08-01

    The effectiveness of auxiliary tempering pump operation at Chalk Point Steam Electric Station (SES) at reducing plant-induced mortality of aquatic biota was evaluated. Several Representative Important Species (RIS) and dominant benthic and zooplankton species were used in the evaluation as indicators of overall system-wide responses. Expected mortality with and without auxiliary pump operation was estimated using thermal tolerance data available from the scientific literature for blue crabs, white perch, striped bass, spot, Macoma balthica and Acartia tonsa. The evaluation led to the conclusion that the operation of auxiliary tempering pumps at Chalk Point SES increases plant-induced mortality of spot, white perch, striped bass, and zooplankton. Operation of the tempering pumps may reduce blue crab mortality slightly under certain circumstances, and Macoma balthica mortality is probably largely unaffected by their operation.

  20. Early Cretaceous chalks from the North Sea giving evidence for global change.

    PubMed

    Mutterlose, Jörg; Bottini, Cinzia

    2013-01-01

    Among calcareous nannofossils, important primary producers in Jurassic and Cretaceous oceans, nannoconids were carbonate rock-forming organisms. During the late Barremian and early Aptian (~126 to 122 million years ago), nannoconids went through a crisis culminating during the Oceanic Anoxic Event 1a. Here we present nannofossil and geochemical data from a section of early Barremian-early Aptian age from the North Sea, recording the earliest chalks ever known in the Boreal Realm. These middle-late Barremian chalks were generated by blooming of endemic nannoconids under relative warm and arid conditions. A subsequent decrease of nannoconids in the latest Barremian coincides with increased nutrient and clay input. This nannoconid decline, also detected at low latitudes, was associated with the Ontong Java Plateau emplacement. We conclude that nannoconids were rock forming also at high latitudes, under clear and oligotrophic waters. Their decline was related to increased continental runoff under reinforced greenhouse conditions. PMID:23575690

  1. Signal analysis of cyclicity in Maastrichtian pelagic chalks from the Danish North Sea

    NASA Astrophysics Data System (ADS)

    Stage, Morten

    1999-11-01

    Low field bulk magnetic susceptibility has been determined on Maastrichtian chalk samples from a drill core from the Dan Field in the Danish North Sea. Fast Fourier Transformations (FFT) have been used to detect possible cycles in the magnetic susceptibility data. Power spectra from the complete section and from sub-sections of the magnetic susceptibility reveal two cyclicities of ca. 0.4 cycles/m and ca. 1.7 cycles/m, which are present on a 90% confidence level. Signal analysis of natural gamma-ray wire-line log data supports these findings. Sedimentation rate estimates place the cycles in the Milankovitch frequency band. Artificial time series are used to study the applicability of the FFT to identifying cyclicity in chalks. Expected geological distortions (e.g., hiati and sedimentation rate variations) are introduced into the time series to investigate the response of the frequency spectra. Different methods of handling missing data intervals are also examined.

  2. Channels in resedimented chalks, Cretaceous Gulf Coastal province of Texas and Mexico

    SciTech Connect

    Lock, B.E.

    1984-09-01

    Extensive roadcuts on U.S. Highway 90 in the vicinity of Langtry in west Texas display superb exposures of well-bedded chalky limestones comprising the lowest 27 m (89 ft) of the Austin Chalk equivalent. The limestone occurs as highly persistent beds averaging about 40 cm (15 in.) thick and separated by shale partings averaging 2-3 cm (about 1 in.). Limestone-shale contacts are very sharp. Nannoplankton indicate a Turonian to Santonian age and an outer shelf source; sedimentary features suggest redeposition by moderately low-density turbidity currents in a midfan setting characterized by distinctive distributary channels with channel-mouth bars and levees. The informal term Langtry formation is applied to these strata, which flank shallower water platform facies to the east, north, and west (Austin Chalk and San Vicente Member of the Boquillas Formation), and pass into basinal limestones of the San Felipe Formation in the La Mula basin to the south.

  3. Drilling and production aspects of horizontal wells in the Austin Chalk

    SciTech Connect

    Sheikholeslami, B.A.; Schlottman, B.W.; Siedel, F.A.; Button, D.M. )

    1990-05-01

    Since 1984, Amoco has pursued horizontal completions within the Burleson, Lee, and Fayette county areas of the Austin Chalk trend in central Texas. To date, two different drilling methods have been based to drill ten horizontal wells, which have been successfully completed and are presently producing. With use of both the short- and medium-radius drilling methods, significant cost reductions were realized and well performance was defined and optimized during the program. The program's overall success was directly attributable to the cooperative efforts of a team of drillers, reservoir engineers, and geologists. The drilling methods used by Amoco and the results of horizontal drilling in the Austin Chalk give production data that compare horizontal well performance against offset vertical well performance, which in this program resulted in horizontal/vertical well production ratios of 2.5 to 7. In addition, a significant relationship between length of horizontal well bore and production ratios was observed.

  4. Intrinsic and Carrier Colloid-facilitated transport of lanthanides through discrete fractures in chalk

    NASA Astrophysics Data System (ADS)

    Weisbrod, N.; Tran, E. L.; Klein-BenDavid, O.; Teutsch, N.

    2015-12-01

    Geological disposal of high-level radioactive waste is the long term solution for the disposal of long lived radionuclides and spent fuel. However, some radionuclides might be released from these repositories into the subsurface as a result of leakage, which ultimately make their way into groundwater. Engineered bentonite barriers around nuclear waste repositories are generally considered sufficient to impede the transport of radionuclides from their source to the groundwater. However, colloidal-sized mobile bentonite particles ("carrier" colloids) originating from these barriers have come under investigation as a potential transport vector for radionuclides sorbed to them. As lanthanides are generally accepted to have the same chemical behaviors as their more toxic actinide counterparts, lanthanides are considered an acceptable substitute for research on radionuclide transportation. This study aims to evaluate the transport behaviors of lanthanides in colloid-facilitated transport through a fractured chalk matrix and under geochemical conditions representative the Negev desert, Israel. The migration of Ce both with and without colloidal particles was explored and compared to the migration of a conservative tracer (bromide) using a flow system constructed around a naturally fractured chalk core. Results suggest that mobility of Ce as a solute is negligible. In experiments conducted without bentonite colloids, the 1% of the Ce that was recovered migrated as "intrinsic" colloids in the form of carbonate precipitates. However, the total recovery of the Ce increased to 9% when it was injected into the core in the presence of bentonite colloids and 13% when both bentonite and precipitate colloids were injected. This indicates that lanthanides are essentially immobile in chalk as a solute but may be mobile as carbonate precipitates. Bentonite colloids, however, markedly increase the mobility of lanthanides through fractured chalk matrices.

  5. Waveform analysis of crosshole GPR data collected in heterogeneous chalk deposits

    NASA Astrophysics Data System (ADS)

    Keskinen, Johanna; Nielsen, Lars; Looms, Majken C.; Moreau, Julien; Stemmerik, Lars; Klotzsche, Anja; van der Kruk, Jan; Holliger, Klaus

    2014-05-01

    Chalks are important reservoirs for groundwater production onshore Denmark and for hydrocarbons in the North Sea Basin. Therefore this rock type is studied extensively with geological and geophysical methods. Ground-penetrating radar (GPR) tomography is used to characterize fine-scale reservoir properties, e.g. subtle changes in porosity. We have conducted a range of high-resolution GPR crosshole experiments in Boesdal quarry in Eastern Denmark. The objective is to investigate the impact of fine-scale heterogeneity on reservoir properties in chalk. The studied chalk interval is c.15 m thick. It can be divided into two main units based on the traveltime analysis and interpretation of the cored material from the boreholes. The lower unit consists mainly of porous calcareous mudstone with occasional occurrences of flint nodules. The upper succession is c. 8 m thick and is fairly heterogeneous with multiple beds of wackestones and packstones with abundant flint nodules or bands. The heterogeneity of the upper layer is expressed by more complex waveforms than the lower unit. Pronounced attenuation of the transmitted wave fields is observed in the highly porous lower unit. Full-waveform inversion methods are highly dependent on the quality of the starting models (usually obtained from ray-based tomography), as well as on the assumptions made regarding the source signal. Adequate estimation of starting models and source waveform is, however, a challenging task for the strongly heterogeneous chalk material. We highlight the critical aspects regarding these tasks for the two contrasting layers. Furthermore we demonstrate how different starting models and assumptions regarding the source signal estimation affect the waveform inversion results.

  6. Seismic characterization of fracture orientation in the Austin Chalk using azimuthal P-wave AVO

    NASA Astrophysics Data System (ADS)

    Al-Shuhail, Abdullatif Adulrahman

    The Austin Chalk is a naturally fractured reservoir. Horizontal drilling, to intersect more fractures, is the most efficient method to develop this reservoir. Information about the predominant fracture orientation in the subsurface is essential before horizontal drilling. This information may be provided by cores, well logs, outcrop, or seismic data. In this study, I apply the azimuthal P-wave AVO method suggested by Ruger and Tsvankin (1997) on 2-D P-wave seismic data in Gonzales County, Texas, in order to determine the fracture azimuth in the Austin Chalk. The data also include oil production from horizontal wells and various types of well logs from vertical wells in the study area. The raw seismic data was imaged through a processing sequence that preserved the relative changes of amplitudes with offset. The stacked sections of some seismic lines showed that the top of the Austin Chalk reflector is laterally inconsistent. This is interpreted as an indication of fractured zones in the subsurface. This interpretation was strengthened by well logs that indicated fracturing in nearby wells. The AVO gradient of every CDP in a seismic line was determined. The median AVO gradient of all the CDPs in a seismic line was chosen to represent the whole line. The median AVO gradients of the lines and their corresponding line azimuths were used repeatedly to solve the azimuthal AVO equation, of Ruger and Tsvankin (1997), for the fracture azimuth using a combination of three different lines every time. The resultant fracture-azimuth solutions clustered about two, nearly perpendicular, azimuths: N58E and S31E. To resolve the inherently ambiguous solutions, the results from the production and well log data were used. Since the production and well log data indicated the presence of NE-trending fractures, I chose the N58E direction as the fracture azimuth. This result agreed with the results of other studies in surrounding areas, using different methods, about the fracture azimuth

  7. Development and maintenance of a telescoping debris flow fan in response to human-induced fan surface channelization, Chalk Creek Valley Natural Debris Flow Laboratory, Colorado, USA

    NASA Astrophysics Data System (ADS)

    Wasklewicz, T.; Scheinert, C.

    2016-01-01

    Channel change has been a constant theme throughout William L. Graf's research career. Graf's work has examined channel changes in the context of natural environmental fluctuations, but more often has focused on quantifying channel change in the context of anthropogenic modifications. Here, we consider how channelization of a debris flows along a bajada has perpetuated and sustained the development of 'telescoping' alluvial fan. Two-dimensional debris-flow modeling shows the importance of the deeply entrenched channelized flow in the development of a telescoping alluvial fan. GIS analyses of repeat (five different debris flows), high-resolution (5 cm) digital elevation models (DEMs) generated from repeat terrestrial laser scanning (TLS) data elucidate sediment and topographic dynamics of the new telescoping portion of the alluvial fan (the embryonic fan). Flow constriction from channelization helps to perpetuate debris-flow runout and to maintain the embryonic fan and telescoping nature of the alluvial fan complex. Embryonic fan development, in response to five debris flows, proceeds with a major portion of the flows depositing on the southern portion of the embryonic fan. The third through the fifth debris flows also begin to shift some deposition to the northern portion of the embryonic. The transfer of sediment from a higher portion of the embryonic fan to a lower portion continues currently on the embryonic fan. While channelized flow has been shown to be critical to the maintenance of the telescoping fan, the flow constriction has led to higher than background levels of sediment deposition in Chalk Creek, a tributary of the Arkansas River. A majority of the sediment from each debris flow is incorporated into Chalk Creek as opposed to being stored on the embryonic fan.

  8. Horizontal exploitation of the Upper Cretaceous Austin Chalk of south Texas

    SciTech Connect

    Borkowski, R.; Hand, L.; Dickerson, D.; Bird, S. )

    1990-05-01

    Horizontal drilling in the fractured Austin Chalk of south Texas has proven to be a viable technology for exploiting reserve opportunities in mature trends as well as in frontier areas. To date, the results of an interdisciplinary approach to the regional analysis of structure and stress regimes combined with studies of the depositional characteristics of the Austin Chalk and Eagleford Shale have been a success. Productive characteristics of the Austin Chalk indicate the influence of regional fractures on the preferential flow direction and partitioning in the Pearsall field area of the trend. Well bore orientation and inclination are designed such that multiple fracture swarms at several stratigraphic horizons are intersected with a single horizontal well bore. As a result of the greater frequency of fracture contacts with the well bore, there is a significant increase in the ultimate recovery of hydrocarbons in place. Conventional vertical drilling techniques are frequently ineffective at encountering these laterally partitioned fracture sets, resulting in lower volumes of recoverable hydrocarbons. Additionally, horizontal well bores may increase ultimate recovery of hydrocarbons by lowering the pressure gradient to the well bore and maximizing the reservoir energy.

  9. Chemostratigraphy of Upper Cretaceous chalk sequences in Norwegian-Danish basin and North Sea Central Trough

    SciTech Connect

    Joergensen, N.O.

    1987-05-01

    Geochemical studies of subsurface sections and outcrops in the Upper Cretaceous chalk sequences from the Norwegian-Danish basin and the North Sea Central Trough have resulted in a detailed chemostratigraphy for these strata. The most applicable chemostratigraphic markers are based on the distribution of strontium, magnesium, manganese, the /sup 13/C//sup 12/C ratio, and the variations in the carbonate contents. It is demonstrated that the chemostratigraphic approach is valid at two levels: (1) a superior chemostratigraphy in which deep-sea cores from the Atlantic Ocean and sections from western Europe are correlated on the basis of significant geochemical anomalies and long-term variations most likely induced by oceanic geochemical cycles and sea level fluctuations; (2) a subordinate but detailed intrabasinal chemostratigraphic correlation which primarily reflects the physicochemical conditions in the depositional environment. The Upper Cretaceous chemostratigraphy established in the Danish area allows a detailed correlation between relatively continuous chalk sequences in the Norwegian-Danish basin and the rather condensed and hiati-influenced sections in the oil fields of the North Sea. The results emphasize the applicability of chemostratigraphy in the subsurface exploration for hydrocarbon reservoirs in chalk.

  10. Late Cretaceous (late Campanian-Maastrichtian) sea-surface temperature record of the Boreal Chalk Sea

    NASA Astrophysics Data System (ADS)

    Thibault, Nicolas; Harlou, Rikke; Schovsbo, Niels H.; Stemmerik, Lars; Surlyk, Finn

    2016-02-01

    The last 8 Myr of the Cretaceous greenhouse interval were characterized by a progressive global cooling with superimposed cool/warm fluctuations. The mechanisms responsible for these climatic fluctuations remain a source of debate that can only be resolved through multi-disciplinary studies and better time constraints. For the first time, we present a record of very high-resolution (ca. 4.5 kyr) sea-surface temperature (SST) changes from the Boreal epicontinental Chalk Sea (Stevns-1 core, Denmark), tied to an astronomical timescale of the late Campanian-Maastrichtian (74 to 66 Ma). Well-preserved bulk stable isotope trends and calcareous nannofossil palaeoecological patterns from the fully cored Stevns-1 borehole show marked changes in SSTs. These variations correlate with deep-water records of climate change from the tropical South Atlantic and Pacific oceans but differ greatly from the climate variations of the North Atlantic. We demonstrate that the onset and end of the early Maastrichtian cooling and of the large negative Campanian-Maastrichtian boundary carbon isotope excursion are coincident in the Chalk Sea. The direct link between SSTs and δ13C variations in the Chalk Sea reassesses long-term glacio-eustasy as the potential driver of carbon isotope and climatic variations in the Maastrichtian.

  11. Late Cretaceous (Late Campanian-Maastrichtian) sea surface temperature record of the Boreal Chalk Sea

    NASA Astrophysics Data System (ADS)

    Thibault, N.; Harlou, R.; Schovsbo, N. H.; Stemmerik, L.; Surlyk, F.

    2015-11-01

    The last 8 Myr of the Cretaceous greenhouse interval were characterized by a progressive global cooling with superimposed cool/warm fluctuations. The mechanisms responsible for these climatic fluctuations remain a source of debate that can only be resolved through multi-disciplinary studies and better time constraints. For the first time, we present a record of very high-resolution (ca. 4.5 kyr) sea-surface temperature (SST) changes from the Boreal epicontinental Chalk Sea (Stevns-1 core, Denmark), tied to an astronomical time scale of the late Campanian-Maastrichtian (74 to 66 Myr). Well-preserved bulk stable isotope trends and calcareous nannofossil palaeoecological patterns from the fully cored Stevns-1 borehole show marked changes in SSTs. These variations correlate with deep-water records of climate change from the tropical South Atlantic and Pacific oceans but differ greatly from the climate variations of the North Atlantic. We demonstrate that the onset and end of the early Maastrichtian cooling and of the large negative Campanian-Maastrichtian boundary carbon isotope excursion are coincident in the Chalk Sea. The direct link between SSTs and δ13C variations in the Chalk Sea reassesses long-term glacio-eustasy as the potential driver of carbon isotope and climatic variations in the Maastrichtian.

  12. Fracture-network 3D characterization in a deformed chalk reservoir analogue -- the Laegerdorf case

    SciTech Connect

    Koestler, A.G.; Reksten, K.

    1995-09-01

    Quantitative descriptions of 3D fracture networks in terms of fracture characteristics and connectivity are necessary for reservoir evaluation, management, and EOR programs of fractured reservoirs. The author`s research has focused on an analogue to North Sea fractured chalk reservoirs that is excellently exposed near Laegerdorf, northwest Germany. An underlying salt diapir uplifted and deformed Upper Cretaceous chalk; the cement industry now exploits it. The fracture network in the production wall of the quarry was characterized and mapped at different scales, and 12 profiles of the 230-m wide and 35-m high production wall were investigated as the wall receded 25 m. In addition, three wells were drilled into the chalk volume. The wells were cored and the wellbores were imaged with both the resistivity formation micro scanner (FMS) and the sonic circumferential borehole image logger (CBIL). The large amount of fracture data was analyzed with respect to parameters, such as fracture density distribution, orientation, and length distribution, and in terms of the representativity and predictability of data sets collected from restricted rock volumes.

  13. Diagenesis of the Machar Field (British North Sea) chalk: Evidence for decoupling of diagenesis in fractures and the host rock

    SciTech Connect

    Maliva, R.G.; Dickson, J.A.D.; Smalley, P.C.; Oxtoby, N.H.

    1995-01-02

    The Chalk Group (Cretaceous/Tertiary) in the Machar Field (British North Sea) contains both fracture-filling and microcrystalline calcite cements. Modeling of fluid-rock interaction using data on light stable isotopes obtained by whole rock analyses and laser ablation analyses of calcite cements reveal that the fracture and matrix diagenetic systems were largely decoupled. The calcium and carbonate of the fracture-filling calcite cements were derived largely from the adjacent chalk matrix. The fracture diagenetic system had a high water-rock ratio, which maintained a relatively stable water {delta}{sup 18}O ratio during calcite dissolution and precipitation. The chalk matrix, on the contrary, had a low molar water-rock ratio during recrystallization, which resulted in increases in the pore-water {delta}{sup 18}O value during recrystallization at elevated temperatures. This evolution of the pore-water {delta}{sup 18}O value is manifested by highly variable cement {delta}{sup 18}O values. The present-day formation waters of the Machar Field have {sup 87}Sr/{sup 86}Sr ratios significantly higher than the whole rock and fracture-filling cement calcite values, evidence that the chemical composition of the formation waters is not representative of that of the pore waters during chalk recrystallization. Little diagenesis is therefore now occurring in the Machar Field. The diagenetic systems of the chalk matrix and fractures both had a high degree of openness with respect to carbon, because of the introduction of organically derived bicarbonate rather than advection of water through the chalk. The bulk of calcite cementation in fractures and the recrystallization and cementation of the chalk matrix occurred at temperatures in the 80--100 C range, at or just below the present-day reservoir temperature of 97 C.

  14. Caoxite-hydroxyapatite composition as consolidating material for the chalk stone from Basarabi-Murfatlar churches ensemble

    NASA Astrophysics Data System (ADS)

    Ion, Rodica-Mariana; Turcanu-Caruţiu, Daniela; Fierăscu, Radu-Claudiu; Fierăscu, Irina; Bunghez, Ioana-Raluca; Ion, Mihaela-Lucia; Teodorescu, Sofia; Vasilievici, Gabriel; Rădiţoiu, Valentin

    2015-12-01

    The development of new composition for surface conservation of some architectural monuments represents now an important research topic. The Basarabi-Murfatlar Ensemble, recognized as the first religious monument from mediaeval Dobrogea (Romania) (from 9th to 11th century), is one of the most impressive archaeological sites of Europe. This ensemble is built from amorphous calcium carbonate, very sensitive to humidity, frost, salts, etc. The aim of this paper is to test on chalk stone samples a new consolidant - hydroxyapatite (HAp) mixed with calcium oxalate trihydrate (caoxite) (COT). Some specific techniques for evaluation its impact on chalk stone surface are used, as follows: petrographical and physical-chemical techniques: SEM, OM, ICP-AES, TGA, FTIR and Raman spectroscopy, chromatic parameters changes, the accelerated weathering tests: heating, freeze-thaw, and their effects on porosity and capillary water uptake by the chalk surface. All these have been evaluated before and after treatment with COT-HAp, putting into evidence the effect of the new composition on the chalk stone surface. HAp induces COT stabilization, and their joint composition can bind weathered stone blocks providing a substantial reinforcement of chalk surface.

  15. The Impact of Surface Charge on the Mechanical Behavior of High-Porosity Chalk

    NASA Astrophysics Data System (ADS)

    Megawati, M.; Hiorth, A.; Madland, M. V.

    2013-09-01

    We present rock mechanical test results and analytical calculations which demonstrate that a negative surface charge, resulting from sulfate adsorption from the pore water, impacts the rock mechanical behavior of high-porosity chalk. Na2SO4 brine flooded into chalk cores at 130 °C results in significantly reduced bulk modulus and yield point compared with that of NaCl brine at the same conditions. The experimental results have been interpreted using a surface complexation model combined with the Gouy-Chapman theory to describe the double layer. The calculated sulfate adsorption agrees well with the measured data. A sulfate adsorption of about 0.3 μmol/m2 and 0.7-1 μmol/m2 was measured at 50 and 130 °C, respectively. Relative to a total sites of 5 sites/nm2 these values correspond to an occupation of 4 % and 8-13 % which sufficiently explains the negative charging of the calcite surfaces. The interaction between charged surfaces specifically in the weak overlaps of electrical double layer gives rise to the total disjoining pressure in granular contacts. The net repulsive forces act as normal forces in the grains vicinity, counteracting the cohesive forces and enhance pore collapse failure during isotropic loading, which we argue to account for the reduced yield and bulk modulus of chalk cores. The effect of disjoining pressure is also assessed at different sulfate concentrations in aqueous solution, temperatures, as well as ionic strength of solution; all together remarkably reproduce similar trends as observed in the mechanical properties.

  16. Successional changes and diversity of soil macrofaunal communities on chalk grasslands in Upper-Normandy (France)

    NASA Astrophysics Data System (ADS)

    Dutoit, Thierry; Decaens, Thibaud; Alard, Didier

    A study of soil macrofaunal communities was made along a secondary plant succession following sheep grazing abandonment in some chalk grasslands of Upper-Normandy (France). 78 taxonomic units were identified. Taxonomic richness was highest in the recently abandoned grassland. Each plot was characterised by its own specific taxonomic groups. The environmental factors which explained the major contrasts between soil macrofaunal communities were the extent of tree colonisation and litter characteristics (C:N, biomass). Successional changes induced major changes in functional groups of soil macrofauna i. e. endogeic species dominated under herbaceous vegetation while epigeic species were more important in woody plots.

  17. Spatial heterogeneity of high-resolution Chalk groundwater geochemistry - Underground quarry at Saint Martin-le-Noeud, France

    NASA Astrophysics Data System (ADS)

    Barhoum, S.; Valdès, D.; Guérin, R.; Marlin, C.; Vitale, Q.; Benmamar, J.; Gombert, P.

    2014-11-01

    Chalk groundwater is an important aquifer resource in France because it accounts for a production of 12 million m3 y-1 with a large proportion reserved for drinking water. Processes occurring in the unsaturated zone (UZ) and the overlying superficial formations have a high impact on Chalk groundwater geochemistry and require better understanding. The study site is a former underground Chalk quarry located near Beauvais (France) that extends over 1200 m in length, at a depth ranging from 20 to 30 m. The water table intersects the cavity creating 15 underground “lake” that give access to the Chalk groundwater. Lakes geochemistry has been studied: water samples were collected in July 2013 and major ion concentrations were analyzed. UZ and clay-with-flints thickness above each lake were estimated qualitatively using an electromagnetic sensor (EM31) and Underground GPS. The results unexpectedly showed that groundwater quality varied widely in spatial terms for both allochthonous and autochthonous ions (e.g., HCO3- ranged from 2.03 to 4.43 meq L-1, NO3- ranged from 0.21 to 1.33 meq L-1). Principal component analysis indicated the impact of agricultural land use on water quality, with the intake of NO3- as well as SO42-, Cl- and Ca2+. Chalk groundwater geochemistry is compared with the nature and structure of the UZ. We highlight correlations (1) between thick clay-with-flints layers and the ions Mg2+ and K+, and (2) between UZ thickness and Na+. In conclusion, this paper identifies various ion sources (agriculture, clay-with-flints and Chalk) and demonstrates different processes in the UZ: dissolution, ionic exchange and solute storage.

  18. The flow mechanism in the Chalk based on radio-isotope analyses of groundwater in the London Basin

    USGS Publications Warehouse

    Downing, R.A.; Pearson, F.J.; Smith, D.B.

    1979-01-01

    14C analyses of groundwaters from the Chalk of the London Basin are re-interpreted and the age of the groundwater is revised. Radio-isotope analyses are used to examine the flow mechanism in the aquifer. The evidence supports the view that a network of micro-fissures and larger intergranular pores in the matrix provides a significant part of the water pumped from Chalk wells and the major fissures distribute the water to the wells. Most of the matrix is fine-grained and contains a very old water. This diffuses into the micro-fissures and larger pores and is carried to the wells by the major fissures. ?? 1979.

  19. Mechanical and chemical processes affecting the chalk during burial, insights from combined reflection seismics, well data and field work

    NASA Astrophysics Data System (ADS)

    Moreau, Julien; Boussaha, Myriam; Nielsen, Lars; Thibault, Nicolas; Stemmerik, Lars

    2014-05-01

    The chalk must undergo several phases of grain reorganisation and chemical reactions during its diagenetic evolution from a carbonaceous ooze to a sedimentary rock. Some of these transformations could be observed on structures from the kilometre- to the micrometre-scale with seismic reflection and cores analyses, respectively. However, few sites allow to combine all the different scale of observation for chalk diagenesis. Onshore and offshore high resolution seismics, two fully cored >350 m wells with wireline logging tools and very high quality exposures from a coastal cliff and a quarry form such an exceptional dataset in the Stevns peninsula area, eastern Danish Basin (Denmark). The studied chalk interval in the area is of Maastrichtian to Danian age. The chalk has been divided in 4 lithofacies, chalk-marl alternations, white chalk, white chalk with flint layers and bryozoan chalk. Advanced stratigraphic works have been performed with astronomical calibration based on stable isotope stratigraphy, wireline logs as well as several palaeontological proxies and detailed sedimentological analysis. Since a couple of decades, a specific kind of fractures has been described in the Chalk of Denmark, the so-called hairline fractures. They have recently been interpreted as compaction bands associated with the pore collapse of the chalk. We have observed these fractures on the field and on the cores in specific intervals. At depth, these fractures are in genetic relation with the formation of some stylolithes. The pressure-solution allows the formation of carbonate seams in the hairline fractures. At larger scale, on the field are observed faults which are sealed with flint precipitations. They slightly offset (<1 m) strata underlined by flint bands. On the onshore and offshore seismic reflection profiles, numerous strata-bound faults form noisy intervals as well as amplitude anomalies. Their normal offsets are less than 25 m. Their branching patterns, and their restriction

  20. Resolution dependence of petrophysical parameters derived from X-ray tomography of chalk

    SciTech Connect

    Müter, D.; Sørensen, H. O.; Jha, D.; Harti, R.; Dalby, K. N.; Stipp, S. L. S.; Suhonen, H.; Feidenhans'l, R.; Engstrøm, F.

    2014-07-28

    X-ray computed tomography data from chalk drill cuttings were taken over a series of voxel dimensions, ranging from 320 to 25 nm. From these data sets, standard petrophysical parameters (porosity, surface area, and permeability) were derived and we examined the effect of the voxel dimension (i.e., image resolution) on these properties. We found that for the higher voxel dimensions, they are severely over or underestimated, whereas for 50 and 25 nm voxel dimension, the resulting values (5%–30% porosity, 0.2–2 m{sup 2}/g specific surface area, and 0.06–0.34 mD permeability) are within the expected range for this type of rock. We compared our results to macroscopic measurements and in the case of surface area, also to measurements using the Brunauer-Emmett-Teller (BET) method and found that independent of the degree of compaction, the results from tomography amount to about 30% of the BET method. Finally, we concluded that at 25 nm voxel dimension, the essential features of the nanoscopic pore network in chalk are captured but better resolution is still needed to derive surface area.

  1. Chalk-calcite-microfluidic experiments: construction and flooding of microsystems with reactive fluids

    NASA Astrophysics Data System (ADS)

    Neuville, Amélie; Thuy Luu, Thi; Dysthe, Dag Kristian; Vinningland, Jan Ludvig; Hiorth, Aksel

    2015-04-01

    Direct in situ observation of the pore structure changes that occur when chalk is flooded with brines could resolve many of the open questions that remain about the interactions between mineralogical alterations and oil-liberating mechanisms. Experiments on core scale and field tests that have been carried out the last decade have clearly shown that water chemistry affects the final oil recovery. However, there is generally no consensus in the scientific community of why additional oil is released. In this work, our aim is to focus on in-situ observations of single phase flow and interactions at the pore scale. To do so, we create several types of custom-made microsystems with chalk and calcite crystals. We then do experiments with reacting fluids in these microsystems. During these experiments, we realize in-situ observations (geometrical characteristics, reaction rate) using microsopy techniques (white light vertical/phase shift interferometric microscopy, and classical microscopy), and show how they vary as function as the water chemistry. In simple systems made of calcite, we obtain reactive rates that are coherent with the litterature and with numerical simulations based on Lattice-Boltzmann methods.

  2. Hydrological role of karst in the Chalk aquifer of Upper Normandy, France

    NASA Astrophysics Data System (ADS)

    El Janyani, Sanae; Dupont, Jean-Paul; Massei, Nicolas; Slimani, Smail; Dörfliger, Nathalie

    2014-05-01

    The role of karst on large-scale groundwater flow is defined for the Chalk aquifer of Upper Normandy (western Paris Basin), France. In the regional context, chalk plateaus occupy the greater part of watersheds and are the main sites of groundwater recharge. Previous studies focused on karstic output systems in the valleys and less on water-level variations in the recharge zones upstream. This study assesses the relevant hydrogeological processes using time-series data (boreholes and springs) recorded along a down-gradient hydrologeological cross-section in two selected watersheds. These hydrological data are interpreted in the framework of previous descriptions of the morphological organization of the study area's karst network. The results highlight the hydrological role of (1) the input karst (vertical conduits) which drains recharging water, (2) the output karst (sub-horizontal conduits widely developed in the vicinity of valleys in the surface watersheds) which drains the output flows, and (3) the connections between these two (input and output) networks, which control the upstream water levels and allow quick transfer to springs, particularly after strong rainfall events. A conceptual model of the hydrological functioning of this covered karst aquifer is established, which should serve for the structuring and parameterization of a numerical model.

  3. Nanoscale Pore Imaging and Pore Scale Fluid Flow Modeling in Chalk

    SciTech Connect

    Tomutsa, Liviu; Silin, Dmitriy

    2004-08-19

    For many rocks of high economic interest such as chalk, diatomite, tight gas sands or coal, nanometer scale resolution is needed to resolve the 3D-pore structure, which controls the flow and trapping of fluids in the rocks. Such resolutions cannot be achieved with existing tomographic technologies. A new 3D imaging method, based on serial sectioning and using the Focused Ion Beam (FIB) technology has been developed. FIB allows for the milling of layers as thin as 10 nanometers by using accelerated Ga+ ions to sputter atoms from the sample surface. After each milling step, as a new surface is exposed, a 2D image of this surface is generated. Next, the 2D images are stacked to reconstruct the 3D pore or grain structure. Resolutions as high as 10 nm are achievable using such a technique. A new robust method of pore-scale fluid flow modeling has been developed and applied to sandstone and chalk samples. The method uses direct morphological analysis of the pore space to characterize the petrophysical properties of diverse formations. Not only petrophysical properties (porosity, permeability, relative permeability and capillary pressures) can be computed but also flow processes, such as those encountered in various IOR approaches, can be simulated. Petrophysical properties computed with the new method using the new FIB data will be presented. Present study is a part of the development of an Electronic Core Laboratory at LBNL/UCB.

  4. Hydrological responses of the chalk aquifer to the regional climatic signal

    NASA Astrophysics Data System (ADS)

    El Janyani, Sanae; Massei, Nicolas; Dupont, Jean-Paul; Fournier, Matthieu; Dörfliger, Nathalie

    2012-09-01

    SummaryPiezometric variability was investigated using monthly time series from 40 piezometers in different areas across the Upper Normandy region, over the 1968-2009 period. The piezometers were classified according to their hydrological behaviour. This paper aimed at characterising the dominant modes explaining piezometric variability and at investigating the causes of this variability. Significant components in the piezometric signals were identified: the annual cycle and an interannual mode (4-12 years) with different variances for each observation borehole group. The influence of the morphostructural organisation of the Upper Normandy chalk plateau on the modalities of the water level variability in the chalk aquifer was defined. The relative contributions and standard deviations of each component found in the signal time series of the groundwater level was estimated. The highest values were recorded in the Northern study area, and clay-with-flints and aquifer thicknesses influence the transfer on an annual scale, while the loess thickness influences the transfer on a multi-year scale.

  5. The stability of surficial fine sediment deposits in lowland chalk streams

    NASA Astrophysics Data System (ADS)

    Grabowski, Robert C.; Wotton, Roger; Droppo, Ian; Davies, Grieg; Wharton, Geraldene

    2010-05-01

    Lowland chalk streams in the UK are experiencing increased deposition of fine sediment due to changes in land-use practices, channel modifications, and groundwater abstraction. The fine sediment is linked to benthic habitat degradation, the obstruction of surface-groundwater flow, and the storage of contaminants, such as pesticides and heavy metals. While research has been conducted on the provenance, transport, deposition, and storage of fine sediment in chalk streams, none has expressly investigated erosion. Therefore a key step is missing in our understanding of sediment dynamics in these systems. A yearlong field survey was conducted in two reaches in the Frome-Piddle Catchment (Dorset, England) to quantify the stability of surficial fine sediment deposits. Sediment stability is dependent on both hydrodynamic conditions and sediment erodibility, so water flow velocities and in situ erodibility measurements were recorded. These measurements were paired with sediment cores for analysis of the physical, chemical and biological properties of the sediment. The results indicate that hydrodynamic conditions vary spatially and temporally as a result of the distinctive annual hydrograph and seasonal macrophyte growth. Sediment erodibility exhibits seasonal variations, with low thresholds for erosion in winter and high thresholds in spring and late summer. Consequently, the stability of fine sediment deposits varies substantially over space and time, which has important implications for sediment transport models.

  6. A model for the effect of pH on the growth of chalk yeasts.

    PubMed

    Dantigny, Philippe; Burgain, Anaïs; Deniel, Franck; Bensoussan, Maurice

    2014-09-01

    Hyphopichia burtonii, Pichia anomala, and Saccharomycopsis fibuligera were isolated from spoiled packaged sliced bread. These chalk yeasts were characterized by a wide range of pH for which growth was almost optimum. Thus, the curve growth vs pH exhibited plateau and sharp profiles close to the minimum and the maximum pH. This study described a chalk yeast model (CYM) for the effect of pH derived from a new germination model for fungi (Dantigny, P., Nanguy, S., P.-M., Judet-Correia, D., and Bensoussan, M. 2011, International Journal of Food Microbiology, 146, 176-181). The CYM is asymmetric, versatile, based on parameters with biological significance, and compatible with the gamma concept. The CYM was compared to the cardinal pH model (CPM) which is widely used to describe the effect of pH on microbial growth. The CYM exhibited RMSE values two fold less than those obtained with the CPM for H. burtonii, and S. fibuligera for which plateaus were clearly observed. For P. anomala, the plateau was less obvious, but the RMSE value obtained with the CYM was similar to that found with the CPM. The CYM could extend its use to represent the effect of pH on mold growth. PMID:24995847

  7. Induced microearthquake patterns and oil-producing fracture systems in the Austin chalk

    NASA Astrophysics Data System (ADS)

    Phillips, W. S.; Fairbanks, T. D.; Rutledge, J. T.; Anderson, D. W.

    1998-04-01

    Microearthquakes collected during hydraulic stimulation allowed us to study fracture zones in Austin chalk oil reservoirs at two sites in the Giddings field, Texas. We deployed three-component, downhole geophone tools in production wells at depths of 2100 m and greater, one near Cook's Point, and two on the Matcek lease near Caldwell. At Cook's Point, we collected 482 microseismic events during a 4000 m 3 (25,000 bbl) hydraulic stimulation in an offset well. We collected 770 events during a similar operation on the Matcek lease. Many seismograms contained reflected phases that constrained location depths to the production zone at the base of the Austin chalk. By restricting all microearthquake locations to production depths, we located 20% of the Cook's Point events and over 60% of the Matcek events. At both sites we observed only the fracture wing closest to the observation stations. Locations formed elongated patterns extending up to 1 km from the stimulation well and trending N60°E, parallel to the known, regional fracture trend. The Cook's Point seismic zone measured over 100 m in width, while long stretches of the Matcek seismic zone narrowed to 30 m or less. We believe that the width of the seismic zone reflected the density of conductive fractures and thus, the volume of the reservoir accessed by the stimulation. Indeed, production rates in the first year following stimulation were much higher at Cook's Point, where we observed the wider of the two seismic zones.

  8. Pressure solution and microfracturing in primary oil migration, Upper Cretaceous Austin Chalk, Texas Gulf Coast

    SciTech Connect

    Chanchani, J.; Berg, R.R.; Lee, C.I.

    1996-09-01

    The Upper Cretaceous Austin Chalk is a well known source rock and fractured reservoir in the Gulf Coast. Production is mainly from tectonic fractures, and the mechanism by which oil migrated from the matrix into the fractures is poorly understood. Microfracturing due to oil generation offers a possible explanation for the mechanism of the primary migration of oil in the Austin Chalk. Petrographic study shows that the major components of the primary migration system are the solution seams and the associated microfractures. Pressure solution is manifest as centimeter to millimeter-scale solution seams and smaller microseams. The solution seams are composites formed by the superposition of the smaller microseams. A significant amount of organic matter was concentrated in the seams along with other insoluble residue. Swarms of horizontal microfractures, many of them filled with calcite and other residue, are associated with the seams. Vertical, tectonic fractures that constitute the reservoir porosity, intersect the solution seams. Pressure solution concentrated organic matter within the solution seams and oil was generated there. It is postulated that the accompanying increase in fluid volume raised the pore pressures and fractured the rock. The newly created microfractures were avenues for migration of fluids from the seams, perhaps by microfracture propagation.

  9. The stability of chalk during flooding of carbonated sea water at reservoir in-situ conditions

    NASA Astrophysics Data System (ADS)

    Nermoen, Anders; Korsnes, Reidar I.; Madland, Merete V.

    2014-05-01

    Injection of CO2 into carbonate oil reservoirs has been proposed as a possible utilization of the captured CO2 due to its capability to enhance the oil recovery. For offshore reservoirs such as Ekofisk and Valhall it has been discussed to alternate the CO2 and sea water injection (WAG) to reduce costs and keep the beneficial effects of both sea water (SSW) and gas injection. Water and CO2 mix to form carbonic acids that enhance the solubility of carbonates, thus a serious concern has been raised upon the potential de-stabilization of the reservoirs during CO2 injection. In this study we focus on how carbonated sea water alters the mechanical integrity of carbonate rocks both to evaluate safety of carbon storage sites and in the planning of production strategies in producing oil fields since enhanced compaction may have both detrimental and beneficial effects. Here we will present results from long term experiments (approx. half year each) performed on Kansas outcrop chalk (38-41% porosity), which serves as model material to understand the physical and chemical interplaying processes taking place in chalk reservoirs. All tests are performed at uni-axial strain conditions, meaning that the confining radial stresses are automatically adjusted to ensure zero radial strain. The tests are performed at in-situ conditions and run through a series of stages that mimic the reservoir history at both Ekofisk and Valhall fields. We observe the strain response caused by the injected brine. The experimental stages are: (a) axial stress build-up by pore pressure depletion to stresses above yield with NaCl-brine which is inert to the chalk; (b) uni-axial creep at constant axial stresses with NaCl-brine; (c) sea water injection; and (d) injection of carbonated water (SSW+CO2) at various mixture concentrations. Two test series were performed in which the pore pressure was increased (re-pressurized) before stage (c) to explore the stress dependency of the fluid induced strain

  10. A multidisciplinary approach to reservoir subdivision of the Maastrichtian chalk in the Dan field, Danish North Sea

    SciTech Connect

    Kristensen, L.; Dons, T.; Schioler, P.

    1995-11-01

    Correlation of wireline log data from the North Sea chalk reservoirs is frequently hampered by rather subtle log patterns in the chalk section due to the apparent monotonous nature of the chalk sediments, which may lead to ambiguous correlations. This study deals with a correlation technique based on an integration of biostratigraphic data, seismic interpretation, and wireline log correlation; this technique aims at producing a consistent reservoir subdivision that honors both the well data and the seismic data. This multidisciplinary approach has been used to subdivide and correlate the Maastrichtian chalk in the Dan field. The biostratigraphic subdivision is based on a new detailed dinoflagellate study of core samples from eight wells. Integrating the biostratigraphic results with three-dimensional seismic data allows recognition of four stratigraphic units within the Maastrichtian, bounded by assumed chronostratigraphic horizons. This subdivision is further refined by adding a seismic horizon and four horizons from wireline log correlations, establishing a total of nine reservoir units. The approximate chronostratigraphic nature of these units provides an improved interpretation of the depositional and structural patterns in this area. The three upper reservoir units pinch out and disappear in a northeasterly direction across the field. We interpret this stratal pattern as reflecting a relative sea level fall or regional basinal subsidence during the latest Maastrichtian, possibly combined with local synsedimentary uplift due to salt tectonics. Isochore maps indicate that the underlying six non-wedging units are unaffected by salt tectonics.

  11. Dual FIB-SEM 3D imaging and lattice boltzmann modeling of porosimetry and multiphase flow in chalk.

    SciTech Connect

    Rinehart, Alex; Petrusak, Robin; Heath, Jason E.; Dewers, Thomas A.; Yoon, Hongkyu

    2010-12-01

    Mercury intrusion porosimetry (MIP) is an often-applied technique for determining pore throat distributions and seal analysis of fine-grained rocks. Due to closure effects, potential pore collapse, and complex pore network topologies, MIP data interpretation can be ambiguous, and often biased toward smaller pores in the distribution. We apply 3D imaging techniques and lattice-Boltzmann modeling in interpreting MIP data for samples of the Cretaceous Selma Group Chalk. In the Mississippi Interior Salt Basin, the Selma Chalk is the apparent seal for oil and gas fields in the underlying Eutaw Fm., and, where unfractured, the Selma Chalk is one of the regional-scale seals identified by the Southeast Regional Carbon Sequestration Partnership for CO2 injection sites. Dual focused ion - scanning electron beam and laser scanning confocal microscopy methods are used for 3D imaging of nanometer-to-micron scale microcrack and pore distributions in the Selma Chalk. A combination of image analysis software is used to obtain geometric pore body and throat distributions and other topological properties, which are compared to MIP results. 3D data sets of pore-microfracture networks are used in Lattice Boltzmann simulations of drainage (wetting fluid displaced by non-wetting fluid via the Shan-Chen algorithm), which in turn are used to model MIP procedures. Results are used in interpreting MIP results, understanding microfracture-matrix interaction during multiphase flow, and seal analysis for underground CO2 storage.

  12. Mineral, chemical and textural relationships in rhythmic-bedded, hydrocarbon-productive chalk of the Niobrara Formation, Denver Basin, Colorado ( USA).

    USGS Publications Warehouse

    Pollastro, R.M.; Martinez, C.J.

    1985-01-01

    The types of hydrocarbons produced from these chalks are determined by the level of thermal maturity associated with present-day burial or paleoburial conditions. Detailed analyses of deeply-buried chalk from core of the Smoky Hill Chalk Member of the Niobrara Formation in the Champlin Petroleum 2 Boxelder Farms well combined with core data from other Niobrara wells have helped identify many depositional and diagenetic relationships. Porosity of the chalk is proportional to maximum burial depth and inversely proportional to the amount of non-carbonate material (acid- insoluble residue content) in the chalk. Total organic carbon content in the chalk is proportional to the amount of acid-insoluble residue and relative abundance of pyrite in the acid-insoluble fraction. Quartz is inversely proportional to the amount of insoluble material, and the amount of clay tends to increase as insolubles increase, suggesting that detritus in these chalks is greatly influenced by reworked, altered, volcanic products rather than siliceous clastics.-from Authors

  13. Full waveform seismic modelling of Chalk Group rocks from the Danish North Sea - implications for velocity analysis

    NASA Astrophysics Data System (ADS)

    Montazeri, Mahboubeh; Moreau, Julien; Uldall, Anette; Nielsen, Lars

    2015-04-01

    This study aims at understanding seismic wave propagation in the fine-layered Chalk Group, which constitutes the main reservoir for oil and gas production in the Danish North Sea. The starting point of our analysis is the Nana-1XP exploration well, which shows strong seismic contrasts inside the Chalk Group. For the purposes of seismic waveform modelling, we here assume a one-dimensional model with homogeneous and isotropic layers designed to capture the main fluctuations in petrophysical properties observed in the well logs. The model is representative of the stratigraphic sequences of the area and it illustrates highly contrasting properties of the Chalk Group. Finite-difference (FD) full wave technique, both acoustic and elastic equations are applied to the model. Velocity analysis of seismic data is a crucial step for stacking, multiple suppression, migration, and depth conversion of the seismic record. Semblance analysis of the synthetic seismic records shows strong amplitude peaks outside the expected range for the time interval representing the Chalk Group, especially at the base. The various synthetic results illustrate the occurrence and the impact of different types of waves including multiples, converted waves and refracted waves. The interference of these different wave types with the primary reflections can explain the strong anomalous amplitudes in the semblance plot. In particular, the effect of strongly contrasting thin beds plays an important role in the generation of the high anomalous amplitude values. If these anomalous amplitudes are used to pick the velocities, it would impede proper stacking of the data and may result in sub-optimal migration and depth conversion. Consequently this may lead to erroneous or sub-optimal seismic images of the Chalk Group and the underlying layers. Our results highlight the importance of detailed velocity analysis and proper picking of velocity functions in the Chalk Group intervals. We show that application of

  14. Evaluation of calabash chalk effect on femur bone morphometry and mineralization in young wistar rats: A pilot study

    PubMed Central

    Ekong, Moses B; Ekanem, Theresa B; Sunday, Abraham O; Aquaisua, Aquaisua N; Akpanabiatu, Monday I

    2012-01-01

    Background: Calabash chalk, a popularly consumed geophagic material in Nigeria has been reported to contain lead, arsenic, alpha lindane, endrin, and endosulfan 11 among other pollutants. Aim: The continuous exposure of young children to this chalk necessitated this study on the bone morphometry and mineralization in young Wistar rats. Materials and Methods: Fourteen young (weanling) Wistar rats of both sexes weighing 54-72 g were assigned into two groups of seven animals each. Group I served as control, while group II was the test group (TG). 40 mg/ml of C. chalk was administered as suspension to the test animals in group II. Animals in the control group were orally treated with 1ml of distilled water. Administration of the C. chalk in the animals lasted for 28 days, and the animals were sacrificed on day 29, using chloroform anaesthesia. The femur bones were dissected out, cleaned of flesh and sun-dried. The lengths and weights of the femur bones were measured using graphite furnace atomic mass spectrophotometer. Results: Results showed 1.6% decrease in body weight change in the TG, insignificant decreases in the weights and lengths of both the right and left femur bones, and significant decreased (P < 0.0126) organ-somatic index, and femur bones concentrations (mg/l) of zinc, phosphate, carbonate, calcium, sodium, and potassium (P < 0.05). Conclusion: In conclusion, this study showed that C. chalk may alter growth rate, and cause de-mineralization in the femur bone, hence, it may be detrimental to bone growth. PMID:23776822

  15. Conference on the topic: {open_quotes}Exploration and production of petroleum and gas from chalk reservoirs worldwide{close_quotes}

    SciTech Connect

    Kuznetsov, V.G.

    1995-07-01

    More than 170 delegates from 14 countries in Europe, North America, Africa, and Asia took part in a conference on the topic: Exploration and Production of Petroleum and Gas from Chalk Reservoirs Worldwide. The conference was held in Copenhagen, Denmark in September,1994, and was a joint meeting of the American Association of Petroleum Geologists (AAPG), and the European Association of Petroleum Geoscientists and Engineers (EAPG). In addition to the opening remarks, 25 oral and nine poster reports were presented. The topics included chalk deposits as reservoir rocks, the occurrence of chalk deposits worldwide, the North Sea oil and gas fields, and other related topics.

  16. Recurrent recovery of Pseudomonas oryzihabitans strains in a karstified chalk aquifer.

    PubMed

    Dussart-Baptista, L; Bodilis, J; Barray, S; Frébourg, N; Fournier, M; Dupont, J-P; Jouenne, T

    2007-01-01

    Pseudomonas oryzihabitans is an uncommon pathogen that may cause catheter-associated infections, particularly in immunocompromised patients. Although it has been isolated from environment, the source of human infection is not well documented. In the present study, 14 isolates of P. oryzihabitans were recovered over a 28-month period from a karstified chalk aquifer, allowing to advance that distributed natural water could be a source of contamination. Microbiological analyses showed that the bacterium was mainly associated with suspended particulate matters. To investigate the clonality of P. oryzihabitans environmental isolates, 16S rRNA gene sequencing, antibiogram and randomly amplified polymorphic DNA (RAPD) typings were performed. Results demonstrated (i) the presence of at least three clones within the aquifer and (ii) that the presence of the bacterium in groundwater is not only the result of a biofilm bloom but also of an exogenous contamination. PMID:17097713

  17. Tracking selenium behaviour in chalk aquifer (northern France): Sr and 34S-sulphates isotopes constraints.

    NASA Astrophysics Data System (ADS)

    Cary, Lise; Benabderraziq, Hind; Elkhattabi, Jamal; Parmentier, Marc; Gourcy, Laurence; Négrel, Philippe

    2014-05-01

    Groundwaters in parts of the Paris Basin (France) are facing increasing selenium (Se) contents that can exceed the drinking water limit of 10 μg/L according to the European Framework Directive in the field of water policy (2000/60/EC). To better understand the groundwater origins and the selenium dynamics, the water chemistry of the Chalk aquifer supplying drinkable water to Lille city was studied. This area is submitted to quantitative and qualitative pressure from industrial, urban and agriculture origins. An integrated study was settled to determine the water sources and dynamics of elements, with a focus on Se. After a large chemical characterisation of the groundwater chemistry in the four field wells, a monthly monitoring was held in four wells and in the Deûle channel. Chemical analysis of major and trace elements, stable isotopes (δ18O, δ2H), strontium isotopes, and δ34S and δ18O of sulphates were realised. The chemical composition of solids sampled at various depths at vicinity of the four wells was also analysed. The specific geochemical signature of groundwater as revealed by Sr isotopes, in addition to element concentrations ratios like Mg/Sr and Se/Sr, highlighted mixture of three main groundwaters bodies: (1) the upstream groundwaters in the recharge area with the most radiogenic 87Sr/86Sr isotopic signature; (2) the confined groundwaters with high Sr concentrations due to water-rock interactions and the lowest 87Sr/86Sr isotopic signature close to the one of the chalk in Paris and London basins; (3) the Se-rich formations of Tertiary and Quaternary. The contents of Se, mainly present as SeV I (and locally as SeIV ), displayed spatial and temporal disparities that can be explained by geological and hydrogeological conditions. Se-rich clayed sediments originating from the dismantling of Se-rich tertiary formations (i.e. Ypresian) overlay the chalk formation and can be found in saturated conditions depending of the water table level. Oxidation of

  18. Campanian ammonites from the Upper Cretaceous Gober Chalk of Lamar County, Texas

    USGS Publications Warehouse

    Cobban, W.A.; Kennedy, W.J.

    1992-01-01

    The Roxton Limestone Member at the top of the Gober Chalk in northeast Texas yields a rich fauna, dominated by Baculites haresi Reeside, 1927, and Inoceramus balticus Boehm, 1909, with sparse occurrences of pachydiscus cf. P. paulsoni (Young, 1963), Anapachydiscus sp.juv., Placenticeras placenta (DeKay, 1828), Hoplitoplacenticeras aff. H. plasticum (Paulcke, 1907), Menabites (Delawarella) delawarensis (Morton, 1830), M.(D.) danei (Young, 1963), M.(D.) aff. M.(D.) vanuxemi (Morton, 1830), Submortoniceras vandalinaense Young, 1963, Submortoniceras sp., Eubostrychoceras sp., and Scaphites hippocrepis (DeKay, 1828) III. The presence of S. hippocrepis III suggests a late early Campanian age assignment for the fauna. The assemblage includes species known from the Western Interior, Gulf Coast, Atlantic seaboard, and western Europe. -Authors

  19. Water temperatures within spawning beds in two chalk streams and implications for salmonid egg development

    NASA Astrophysics Data System (ADS)

    Acornley, R. M.

    1999-02-01

    Water temperatures within brown trout (Salmo trutta L.) spawning gravels were measured in two Hampshire chalk streams from October 1995 to April 1996 inclusive. During the winter, mean intra-gravel water temperatures were higher than those in the stream, and increased with depth in the gravel bed. The amplitude of diel fluctuations in water temperature decreased with depth in the gravel bed, although diel fluctuations were still evident at a depth of 30 cm. Differences in intra-gravel temperature gradients between the two study sites were attributed to differences in the amplitude of stream water temperature fluctuations and there was no evidence that either of the study sites were located in zones of upwelling groundwater. Published equations are used to predict, from temperature, the timing of important stages in the development of brown trout embryos (eyeing, hatching and emergence) for eggs spawned in the autumn and winter and buried at different depths in the gravel bed.

  20. Fault and joint measurements in Austin Chalk, Superconducting Super Collider Site, Texas

    SciTech Connect

    Nance, H.S.; Laubach, S.E.; Dutton, A.R.

    1994-12-31

    Structure maps of 9.4 mi of nearly continuous tunnel excavations and more than 10 mi of other exposures and excavations in Austin Chalk at the Superconducting Super Collider (SSC) site in Ellis County, Texas, record normal-fault and joint populations in the subsurface within the northern segment of the Balcones Fault Zone with unmatched resolution for such a long traverse. Small faults (<10 ft throw) occur in clusters or swarms that have as many as 24 faults. Fault swarms are as much as 2,000 ft wide, and spacing between swarms ranges from 800 to 2,000 ft, averaging about 1,000 ft. Predominantly northeast-trending joints are in swarms spaced 500 to more than 21,000 ft apart.

  1. Expected returns on investment in the Giddings, Austin Chalk (gas) field

    SciTech Connect

    Reeve, R.P.; Peters, E.J.

    1982-01-01

    An economic evaluation has been performed to determine the expected returns on investment for a drilling program in the Giddings, Austin Chalk gas field. Using projected production schedules of selected well types from the encountered reserve distribution, computer based cashflow analyses were performed under 6 hypothesized future scenarios of varying hydrocarbon pricing, demand, taxation, and inflation. For the 6 future scenarios studied, the Giddings gas field drilling program was found to produce a positive, after tax net present value, using 15% as a discount factor. Furthermore, the returns on investment were higher for an independent than for a major producer. The results suggest a drilling program initiated in the near future will prove to be an attractive economic venture. 15 references.

  2. Expected returns on investment in the Giddings, Austin Chalk (Gas) Field. [Texas

    SciTech Connect

    Reeve, R.P.; Peters, E.J.; VanRensburg, W.C.J.

    1982-09-01

    An economic evaluation has been performed to determine the expected returns on investment for a drilling program in the Giddings, Austin Chalk Gas Field. Using projected production schedules of selected well types from the encountered reserve distribution, computer based cashflow analyses were performed under six hypothesized future scenarios of varying hydrocarbon pricing, demand, taxation, and inflation. For the six future scenarios studied, the Giddings Gas Field drilling program was found to produce a positive, after tax net present value, using 15% as a discount factor. Furthermore, the returns on investment were higher for an independent than for a major producer. Results suggest a drilling program initiated in the near future will prove to be an attractive economic venture.

  3. Multi isotopic tools to understand selenium origins in groundwaters of the Chalk aquifer in Northern France

    NASA Astrophysics Data System (ADS)

    Cary, Lise; Gourcy, Laurence; Benabderraziq, Hind; Elkhattabi, Jamal; Laurent, Alexandra; Négrel, Philippe

    2013-04-01

    Four field wells exploiting the Chalk aquifer supply Lille city in water. The little catchment area is submitted to quantitative and qualitative pressure from industrial, urban and agriculture origins. Selenium (Se) concentrations are often higher than EU standards (0.12 µmol.L-1) for potable drinking water and can reach 0.4 μmol.L-1 leading to exploitation restrictions. An integrated study was settled to determine the water sources and dynamics of elements, with a focus on Se, with the goal of managing both water quality and quantity. After a large chemical characterisation of the system, a monthly sampling campaign was held in 2012 in four wells and in the close Deûle channel. In situ physical and chemical parameters, chemical analysis of major and trace elements with a special focus on redox-sensitive elements including SeIV, SeVI, FeII, stable water isotopes (δ18O, δ2H) and δ34S and δ18O of sulphates measures were undertaken. The chemical composition of solids sampled at various depths at vicinity of the four wells was analysed. Se concentrations in groundwaters and in the solid phase vary significantly. In the northern part of the Ansereuilles north of the Deûle channel, where the highest Se concentrations in solids was found in a 13 m alluvial clay deposit above the chalk, a first main type of waters can be defined with the variable and locally highest Se concentrations (0.19 to 0.4 µmol.L-1), relatively high and stable sulphate concentrations (2.5 µmol/L), no nitrates, dissolved Fe and Mn, negative δ34S (around -20 ‰) and δ18O typical of evaporated waters. A second main type of waters can be described at Houplin, south of the Deûle channel, where the geological profile show less than 1 mg/kg of Se, with intermediate Se concentrations (0.1 to 0.2 µmol/L), variable nitrate concentrations (0.4 to 1.2 mmol/L), not quantified dissolved Fe and Mn, sulphate concentrations close to 1.5 mmol/L, variable negative δ34S (-8 to -24 ‰) and δ18O in the

  4. Diagenesis of silica-rich mound-bedded chalk, the Coniacian Arnager Limestone, Denmark

    NASA Astrophysics Data System (ADS)

    Madsen, H. B.; Stemmerik, L.; Surlyk, F.

    2010-01-01

    The Coniacian Arnager Limestone Formation is exposed on the Danish island of Bornholm in the Baltic Sea. It is composed of mound-bedded siliceous chalk, and X-ray diffraction and scanning electron microscopy indicate a content of 30-70% insoluble minerals, including authigenic opal-CT, quartz, clinoptilolite, feldspars, calcite, dolomite, and barite. Opal-CT and clinoptilolite are the most common and constitute 16-53% and 2-9%, respectively. The content of insoluble minerals varies laterally both within the mounds and in planar beds, and the opal-CT content varies by up to 10% vertically. The mounds consist of two microfacies, spiculitic wackestone and bioturbated spiculitic wackestone, containing 10-22% and 7-12% moulds after spicules, respectively. Subsequent to deposition and shallow burial, dissolution of siliceous sponge spicules increased the silica activity of the pore water and initiated precipitation of opal-CT. The opal-CT formed at temperatures around 17 °C, the precipitation lowered the silica activity and the Si/Al ratio of the pore water, resulting in precipitation of clinoptilolite, feldspar and smectite. Calcite formed synchronously with the latest clinoptilolite. Minor amounts of quartz precipitated in pore water with low silica activity during maximum burial, probably to depths of 200-250 m. The dissolution of sponge spicules and decomposition of the sponge tissue also resulted in the release of Ba 2+, Sr 2+, Mg 2+, Ca 2+ and CO 32-, facilitating precipitation of barite and dolomite. Precipitation of especially opal-CT reduced the porosity to an average of 40% and cemented the limestone. The study highlights the diagenetic pathways of bio-siliceous chalk and the effects on preservation of porosity and permeability.

  5. Austin Chalk fracture mapping using frequency data derived from seismic data

    NASA Astrophysics Data System (ADS)

    Najmuddin, Ilyas Juzer

    Frequency amplitude spectra derived from P-wave seismic data can be used to derive a fracture indicator. This fracture indicator can be used to delineate fracture zones in subsurface layers. Mapping fractures that have no vertical offset is difficult on seismic sections. Fracturing changes the rock properties and therefore the attributes of the seismic data reflecting off the fractured interface and data passing through the fractured layers. Fractures have a scattering effect on seismic energy reflected from the fractured layer. Fractures attenuate amplitudes of higher frequencies in seismic data preferentially than lower frequencies. The amplitude spectrum of the frequencies in the seismic data shifts towards lower frequencies when a spectrum from a time window above the fractured layer is compared with one below the fractured layer. This shift in amplitudes of frequency spectra can be derived from seismic data and used to indicate fracturing. A method is developed to calculate a parameter t* to measure this change in the frequency spectra for small time windows (100ms) above and below the fractured layer. The Austin Chalk in South Central Texas is a fractured layer, and it produces hydrocarbons from fracture zones with the layer (Sweet Spots). 2D and 3D P-wave seismic data are used from Burleson and Austin Counties in Texas to derive the t* parameter. Case studies are presented for 2D data from Burleson County and 3D data from Austin County. The t* parameter mapped on the 3D data shows a predominant fracture trend parallel to strike. The fracture zones have a good correlation with the faults interpreted on the top of Austin Chalk reflector. Production data in Burleson County (Giddings Field) is a proxy for fracturing. Values of t* mapped on the 2D data have a good correlation with the cumulative production map presented in this study.

  6. Anomalous magnetization in the Austin Chalk: implications for magnetic studies in rocks and sediments

    SciTech Connect

    Ellwood, B.B.; Balsam, W.L.

    1985-01-01

    Same day sampling and magnetic measurement of a one meter thick bed in a new road cut of the Upper Cretaceous Austin Chalk (northeastern Texas) has yielded a zone of anomalous magnetic behavior. Initial measurement of the anisotropy of magnetic susceptibility (AMS) indicated unusually high anisotropies and low bulk susceptibilities characteristic of a magnetocrystalline anisotropy which might be expected for the mineral siderite. Natural remanent magnetization (NRM) moments for these samples were low and directions were typical for samples which had acquired a normal geomagnetic field overprint at the site. Remeasurement of the NRM 3 days later yielded an increase in moment to >1 x 10/sup -3/ A/m for some samples and a direction parallel to the laboratory field. Isothermal remanent magnetization (IRM) of these samples indicates saturation at low induction values (<100 mT). AMS remeasurement over a period of weeks revealed a steady decrease in the anisotropy magnitudes and a change in direction. All of these results are consistent with the initial presence of siderite in the Austin Chalk samples. After sampling, exposure to the air, and subsequent oxidation in the laboratory, the siderite appears to have altered to ..gamma..Fe/sub 2/O/sub 3/ (maghemite), increasing the magnetic moment and changing NRM and AMS directions in these samples. It is predicted that changes will reflect the continued conversion from the less stable ..gamma..Fe/sub 2/O/sub 3/ to ..cap alpha..Fe/sub 2/O/sub 3/ (hematite). Evaluation of this possibility is currently in progress.

  7. Seawater chemistry, coccolithophore population growth, and the origin of Cretaceous chalk

    NASA Astrophysics Data System (ADS)

    Stanley, Steven M.; Ries, Justin B.; Hardie, Lawrence A.

    2005-07-01

    The magnesium/calcium ratio (Mg/Ca) and calcium (Ca) concentration of seawater have oscillated throughout geologic time; our experiments indicate that these variables have strongly influenced biomineralization and chalk production by coccolithophores. The high Mg/Ca ratio of modern seawater favors precipitation of high-Mg calcite and/or aragonite. In contrast, the low Mg/Ca ratio of imputed Cretaceous seawater favored precipitation of low-Mg calcite. We have discovered that some coccolithophore species today secrete skeletal elements of high-Mg calcite, rather than low-Mg calcite, as conventionally believed. These species incorporated less Mg when the ambient Mg/Ca ratio was lowered, secreting low-Mg calcite in imputed Cretaceous seawater. Calcification stimulates cocco lithophore population growth by contributing CO2 to photosynthesis. Three extant coc co lithophore species multiplied much faster as the composition of ambient seawater was shifted toward that estimated for Cretaceous seas. Two of these species secreted high-Mg calcite in ambient seawater having Mg/Ca > 1, and incorporation of Mg in a calcite crystal inhibits growth. Calcification of the third species, which secreted low-Mg calcite at all ambient Mg/Ca ratios, is hindered by the high Mg/Ca ratio and low absolute concentration of Ca of modern seawater. We conclude that the ionic composition of Cretaceous seawater enabled cocco lithophores to produce massive chalk deposits, and conversely, that the ionic composition of modern seawater inhibits population growth for most extant coccolitho phore species, which occupy nutrient-poor waters and fail to respond to fertilization by nitrate, phosphate, or iron.

  8. Increase of Coastal Cliff Rockfall Trigerred By Rainfall On The Chalk Coast of NW France During The Year 2001

    NASA Astrophysics Data System (ADS)

    Duperret, A.; Genter, A.; Daigneault, M.; Mortimore, R. N.

    Coastal chalk cliffs exposed on each part of the English Channel suffer numerous collapses, with mean volumes varying between 10 000 and 100 000 cubic meters. Between October 1998 and October 2001, a minimum of 52 collapses have been ob- served along 120 km of the French chalk coastline located in Upper-Normandy and Picardy. The chalk coastline has evidenced 4 collapses in 1999 and 6 collapses in 2000 (winter and spring), whereas 28 collapses with volume greater than 1000 m3 was recorded in 2001 (winter, spring and summer). The increase of large-scale collapses during 2001 is interpreted as an excess of rainfalls recorded previously. Most of these collapses extend all over the vertical cliff height and are mainly controlled by ground- water infiltration. The modality of water circulation through the chalk rock depends on the chalk lithology and the hydrogeological properties of pre-existing fractures. In the framework of the European scientific project named ROCC (Risk of Cliff Col- lapse), the chalk lithology and the pre-existing fracture pattern have been investigated in order to determine the response of the rock mass to subaerial and marine solicita- tions, including rainfall conditions. Such data have been reported in a GIS system in order to determine the degree of cliff sensibility to collapses. Some rainfall-triggered collapses will be presented to illustrate the diversity of the rock mass response to rain- fall excess, in terms of rock mass characteristics and time delay: (1) a collapse was witnessed at Puys, the 17th May 2000, after two periods of intense rainfall inducing floods, during the two previous months. The occurrence of impervious marl seams levels within the chalk and its low fracture content may have generated water over- pressure and consequently stress concentration on the marl seams, which conduct to the rupture. The delay between rainfall and the rupture may be explained by the low velocity of groundwater through a poorly fractured porous

  9. Integrating geophysical and hydrochemical borehole-log measurements to characterize the Chalk aquifer, Berkshire, United Kingdom

    NASA Astrophysics Data System (ADS)

    Schürch, Marc; Buckley, David

    2002-09-01

    Geophysical and hydrochemical borehole-logging techniques were integrated to characterize hydraulic and hydrogeochemical properties of the Chalk aquifer at boreholes in Berkshire, UK. The down-hole measurements were made to locate fissures in the chalk, their spatial extent between boreholes, and to determine the groundwater chemical quality of the water-bearing layers. The geophysical borehole logging methods used were caliper, focused resistivity, induction resistivity, gamma ray, fluid temperature, fluid electrical conductivity, impeller and heat-pulse flowmeter, together with borehole wall optical-imaging. A multiparameter data transmitter was used to measure groundwater temperature, electrical conductivity, dissolved oxygen, pH, and redox potential of the borehole fluid down-hole. High permeability developed at the Chalk Rock by groundwater circulation provides the major flow horizon at the Banterwick Barn study site and represents a conduit system that serves as an effective local hydraulic connection between the boreholes. The Chalk Rock includes several lithified solution-ridden layers, hardgrounds, which imply a gap in sedimentation possibly representing an unconformity. Lower groundwater temperature, high dissolved-oxygen content, and flowmeter evidence of preferential groundwater flow in the Chalk Rock indicated rapid groundwater circulation along this horizon. By repeating the logging at different times of the year under changing hydraulic conditions, other water-inflow horizons within the Chalk aquifer were recognized. Résumé. Des techniques géophysiques et hydrochimiques de diagraphies en forage ont été mises en oeuvre pour caractériser les propriétés hydrauliques et hydrogéochimiques de l'aquifère de la craie dans des forages du Berkshire (Grande-Bretagne). Les mesures en descente ont été faites pour localiser les fissures dans la craie et leur développement spatial entre forages, et pour déterminer la qualité de l'eau souterraine des

  10. Origin, distribution and alteration of organic matter and generation and migration of hydrocarbons in Austin Chalk, Upper Cretaceous, southeastern Texas. Final report, September 1, 1980-August 31, 1981

    SciTech Connect

    Grabowski, G.J. Jr.

    1981-01-01

    The kerogen and bitumen from samples of the Austin Chalk from the subsurface of southeastern Texas were analyzed to determine the origin of the organic matter and the alteration of the kerogen to form petroleum. The effects of mineral composition on the rate of alteration and on the composition of hydrocarbons generated was examined. The source-rock potential and the processes of migration and reservoiring in the chalk are considered.

  11. Palaeoclimatic changes during the Upper Cretaceous of eastern Denmark: a study based on the Stevns-2 chalk core

    NASA Astrophysics Data System (ADS)

    Boussaha, M.; Stemmerik, L.; Thibault, N.

    2013-12-01

    The Stevns-2 core located in eastern Denmark penetrated close to 350 m of upper Campanian-Maastrichtian sediments of the upper Chalk Group (Stemmerik et al., 2006). The calcareous nannofossil biozonation spans the time interval from the UC16aBP from the upper Campanian to the NNT1 in the lowermost Danian. Carbon and Oxygen isotopes trends records climatic events occurring in the upper Cretaceous: (1) the Late Campanian warm climatic optimum, (2) the early Maastrichtian cooling event, (3) the mid-Maastrichtian warming event, and (4) the late Maastrichtian cooling event, also observed in the nearby Stevns-1 core (Thibault et al., 2011) . These climatic variations match closely those observed in the nearby Stevns-1 core and in the Atlantic, Pacific and Tethyan realms (Thibault & GARDIN, 2006; Thibault et al., 2011). Changes occurring in the number of observed Inoceramids prisms per meter of core section, in the abundance of calcareous nannofossils and in the visible trace fossils abundances seem to be linked to climatic changes as expressed in the δ18O of the bulk sediment. In addition to the sedimentological data show that the distribution of facies through time from: (1) cyclic marl alternating with mudstone-wackestone chalk and conglomerates, to (2) bioturbated white mudstone and wackestone chalk, then to (3) flint alternating with mudstone and wackestone chalk, ending with (5) bryozoans wackestone and packstone, and the sedimentation rate changes varying from 1.4 cm/kyr to 13.4 cm/kyr. Here we show how changes in the sedimentology of the chalk and abundances of different fossil group are influenced by global and regional mechanisms. Isotopic results mainly reflect global paleoclimatic changes, whereas the sedimentological record is mostly influenced by (1) local variations in paleoproductivity, (2) deep-water paleocurrents influencing the chalk deposition and the shape of the sea-floor, (3) and (4) the geodynamic activity and paleotopography of the Late

  12. Fertility of holstein dairy heifers after synchronization of ovulation and timed AI or AI after removed tail chalk.

    PubMed

    Rivera, H; Lopez, H; Fricke, P M

    2004-07-01

    Nonlactating Holstein dairy heifers (n=352) 13 mo of age were managed using a 42-d artificial insemination (AI) breeding period in which they received AI after removed tail chalk evaluated once daily. At AI breeding period onset (d 0), heifers were randomly assigned to receive synchronization of ovulation (100 microg of GnRH, d 0; 25 mg of PGF2alpha, d 6; 100 microg of GnRH, d 8) and timed AI (TAI; d 8) and AI after removed tail chalk for the entire AI breeding period (GPG; n=175), or AI after removed tail chalk for the entire AI breeding period (TC; n=177). As expected, 17.7% (31/175) of GPG heifers received AI after removed tail chalk before scheduled TAI. Pregnancy rate per artificial insemination (PR/AI) at approximately 30 d after first AI tended to be greater for TC (46.5%) than for GPG (38.3%) heifers. No treatment x inseminator interaction was detected; however, overall PR/AI was low for heifers in both treatments due to variation among the 3 inseminators (24.8, 30.0, and 58.0%). Pregnancy loss from approximately 30 to approximately 75 d after first AI was 10% and did not differ between treatments. Based on survival analysis, days to first AI was greater for TC than for GPG heifers, whereas days to pregnancy across the 42-d AI breeding period did not differ between treatments. Overall, 81.2% of GPG heifers receiving TAI synchronized luteal regression and ovulated within 48 h after the second GnRH injection. We conclude that this synchronization protocol can yield acceptable fertility in dairy heifers if AI to estrus is conducted between treatment with GnRH and PGF2alpha and AI efficiency is optimized. PMID:15328217

  13. Dual FIB-SEM 3D Imaging and Lattice Boltzmann Modeling of Porosimetry and Multiphase Flow in Chalk

    NASA Astrophysics Data System (ADS)

    Rinehart, A. J.; Yoon, H.; Dewers, T. A.; Heath, J. E.; Petrusak, R.

    2010-12-01

    Mercury intrusion porosimetry (MIP) is an often-applied technique for determining pore throat distributions and seal analysis of fine-grained rocks. Due to closure effects, potential pore collapse, and complex pore network topologies, MIP data interpretation can be ambiguous, and often biased toward smaller pores in the distribution. We apply 3D imaging techniques and lattice-Boltzmann modeling in interpreting MIP data for samples of the Cretaceous Selma Group Chalk. In the Mississippi Interior Salt Basin, the Selma Chalk is the apparent seal for oil and gas fields in the underlying Eutaw Fm., and, where unfractured, the Selma Chalk is one of the regional-scale seals identified by the Southeast Regional Carbon Sequestration Partnership for CO2 injection sites. Dual focused ion - scanning electron beam and laser scanning confocal microscopy methods are used for 3D imaging of nanometer-to-micron scale microcrack and pore distributions in the Selma Chalk. A combination of image analysis software is used to obtain geometric pore body and throat distributions and other topological properties, which are compared to MIP results. 3D data sets of pore-microfracture networks are used in Lattice Boltzmann simulations of drainage (wetting fluid displaced by non-wetting fluid via the Shan-Chen algorithm), which in turn are used to model MIP procedures. Results are used in interpreting MIP results, understanding microfracture-matrix interaction during multiphase flow, and seal analysis for underground CO2 storage. This work was supported by the US Department of Energy, Office of Basic Energy Sciences as part of an Energy Frontier Research Center. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

  14. Style of faults and associated fractures in Austin Chalk: northern extension of balcones fault zone, central Texas

    SciTech Connect

    Reaser, D.F.; Collins, E.W.

    1988-09-01

    Distributions, geometries, and densities of faults and associated fractures in the Cretaceous Austin Chalk were studied in outcrop within the northernmost extension of the Balcones fault zone in Ellis and northern Hill Counties, Texas. Description of the fracture systems may be applicable to hydrocarbon exploration and production from this unit and to locating the proposed Dallas-Fort Worth Area Superconducting Super Collider site in Ellis County.

  15. Paleoceanographic changes during the Albian-Cenomanian in the Tethys and North Atlantic and the onset of the Cretaceous chalk

    NASA Astrophysics Data System (ADS)

    Giorgioni, Martino; Weissert, Helmut; Bernasconi, Stefano M.; Hochuli, Peter A.; Keller, Christina E.; Coccioni, Rodolfo; Petrizzo, Maria Rose; Lukeneder, Alexander; Garcia, Therese I.

    2015-03-01

    During the mid-Cretaceous the Earth was characterized by peculiar climatic and oceanographic features, such as very high temperatures, smooth thermal meridional gradient, long-term rising sea level, and formation of oceanic gateways and seaways. At that time widespread deposition of micritic pelagic limestones, generally called chalk, occurred in deep pelagic settings as well as in epeiric seas, both at tropical and at high latitudes. The origin of such extensive chalk deposition in the mid-Cretaceous is a complex and still controversial issue, which involves the interaction of several different factors. In this work we address this topic from the paleoceanographic perspective, by investigating the contribution of major oceanic circulation changes. We characterize several stratigraphic sections from the Tethys and North Atlantic with litho-, bio-, and carbon isotope stratigraphy. Our data show a change between two different oceanic circulation modes happening in the Late Albian. The first is an unstable mode, with oceanographic conditions fluctuating frequently in response to rapid environmental and climatic changes, such as those driven by orbital forcing. The second mode is more stable, with better connection between the different oceanic basins, a more stable thermocline, more persistent current flow, better defined upwelling and downwelling areas, and a more balanced oceanic carbon reservoir. We propose that under the mid-Cretaceous paleogeographic and paleoclimatic conditions this change in oceanic circulation mode favored the beginning of chalk sedimentation in deep-water settings.

  16. Mass-transport deposits and reservoir quality of Upper Cretaceous Chalk within the German Central Graben, North Sea

    NASA Astrophysics Data System (ADS)

    Arfai, Jashar; Lutz, Rüdiger; Franke, Dieter; Gaedicke, Christoph; Kley, Jonas

    2016-04-01

    The architecture of intra-chalk deposits in the `Entenschnabel' area of the German North Sea is studied based on 3D seismic data. Adapted from seismic reflection characteristics, four types of mass-transport deposits (MTDs) are distinguished, i.e. slumps, slides, channels and frontal splay deposits. The development of these systems can be linked to inversion tectonics and halotectonic movements of Zechstein salt. Tectonic uplift is interpreted to have caused repeated tilting of the sea floor. This triggered large-scale slump deposition during Turonian-Santonian times. Slump deposits are characterised by chaotic reflection patterns interpreted to result from significant stratal distortion. The south-eastern study area is characterised by a large-scale frontal splay complex. This comprises a network of shallow channel systems arranged in a distributive pattern. Several slide complexes are observed near the Top Chalk in Maastrichtian and Danian sediments. These slides are commonly associated with large incisions into the sediments below. Best reservoir properties with high producible porosities are found in the reworked chalk strata, e.g. Danish North Sea, therefore MTDs detected in the study area are regarded as potential hydrocarbon reservoirs and considered as exploration targets.

  17. Geologic models and evaluation of undiscovered conventional and continuous oil and gas resources: Upper Cretaceous Austin Chalk

    USGS Publications Warehouse

    Pearson, Krystal

    2012-01-01

    The Upper Cretaceous Austin Chalk forms a low-permeability, onshore Gulf of Mexico reservoir that produces oil and gas from major fractures oriented parallel to the underlying Lower Cretaceous shelf edge. Horizontal drilling links these fracture systems to create an interconnected network that drains the reservoir. Field and well locations along the production trend are controlled by fracture networks. Highly fractured chalk is present along both regional and local fault zones. Fractures are also genetically linked to movement of the underlying Jurassic Louann Salt with tensile fractures forming downdip of salt-related structures creating the most effective reservoirs. Undiscovered accumulations should also be associated with structure-controlled fracture systems because much of the Austin that overlies the Lower Cretaceous shelf edge remains unexplored. The Upper Cretaceous Eagle Ford Shale is the primary source rock for Austin Chalk hydrocarbons. This transgressive marine shale varies in thickness and lithology across the study area and contains both oil- and gas-prone kerogen. The Eagle Ford began generating oil and gas in the early Miocene, and vertical migration through fractures was sufficient to charge the Austin reservoirs.

  18. Characterization of Acid Mine Drainage Sources Using Stable and Radiogenic Isotopes, Chalk Creek, Colorado

    NASA Astrophysics Data System (ADS)

    Cordalis, D.; Michel, R.; Williams, M.; Wireman, M.

    2003-12-01

    Acid mine drainage (AMD) affects many streams throughout the western United States. Understanding flow dynamics and sources within a fractured rock setting is necessary in outlining a potential remediation strategy for AMD. Radiogenic and stable isotopes of water were used in the Mary Murphy Mine, Chalk Creek, Colorado, in order to characterize flowpaths and sourcewaters. By delineating the sources of the mine water, groundwater, and event water, we may be able to target remediation techniques for individual contamination sources. Moreover, results from this research provide insights into groundwater flow systems in mountain environments of the Colorado Rockies. Tritium, a cosmogenic isotope of hydrogen, has a half-life 12.43y and is useful for studying hydrologic processes at the decadal time scale and can be used as an effective tracer when traditional chemical tracers are non-conservative. Hydrometric information showed that discharge from the mine adit exhibited a hydrograph characteristic of snowmelt runoff. However, mixing models using stable water isotopes (D and 18O) found less than 7% of the mine's peak discharge was from snowmelt, suggesting a regional groundwater dominated system. Mine interior samples fell into two characteristic groupings: either from the extreme north side of the drift which contained most of the zinc contamination, and all other locations. The waters from the north drift, MVN-3 and MVN-4, had lower 18O values, -17.62 per mil and -17.17 per mil, respectively, than did any of the other locations, suggesting a seasonal snowmelt input. However, the tritium values associated with MVN-3 and MVN-4 suggest at least some mixing, with values of 13.4 TU and 12.5 TU, respectively. Surface water samples from Chalk Creek show average tritium values of 11.1 TU, and 18O values of -14.87 per mil. Groundwater samples were captured using monitoring wells, and plotted according to the depth of screening. Alluvial wells carried a seasonal signal similar

  19. Contribution of piezometric measurement to knowledge and management of low water levels: examples on the chalk aquifer in the Champagne Ardennes region

    NASA Astrophysics Data System (ADS)

    Stollsteiner, P.; Bessiere, H.; Nicolas, J.; Allier, D.; Berthet, O.

    2015-04-01

    This article is based on a BRGM study on piezometric indicators, threshold values of discharge and groundwater levels for the assessment of potentially-exploitable water resources of chalky watersheds. A method for estimating low water levels based on groundwater levels is presented from three examples representing chalk aquifers with different cycles: annual, combined and interannual. The first is located in Picardy and the two others in the Champagne-Ardennes region. Piezometers with annual cycles, used in these examples, are supposed to be representative of the aquifer hydro-dynamics. Except for multi-annual systems, the analysis between discharge measurements at a hydrometric station and groundwater levels measured at a piezometer representative of the main aquifer, leads to relatively precise and satisfactory relationships within a chalky context. These relationships may be useful for monitoring, validation, extension or reconstruction of the low water flow data. On the one hand, they allow definition of the piezometric levels corresponding to the different alert thresholds of river discharges. On the other hand, they clarify the proportions of low surface water flow from runoff or drainage of the aquifer. Finally, these correlations give an assessment of the minimum flow for the coming weeks. However, these correlations cannot be used to optimize the value of the exploitable water resource because it seems to be difficult to integrate the value of the effective rainfall that could occur during the draining period. Moreover, in the case of multi-annual systems, the solution is to attempt a comprehensive system modelling and, if it is satisfactory, using the simulated values to get rid of parasites or running the model for forecasting purposes.

  20. Temporal variability of local abundance, sex ratio and activity in the Sardinian chalk hill blue butterfly

    USGS Publications Warehouse

    Casula, P.; Nichols, J.D.

    2003-01-01

    When capturing and marking of individuals is possible, the application of newly developed capture-recapture models can remove several sources of bias in the estimation of population parameters such as local abundance and sex ratio. For example, observation of distorted sex ratios in counts or captures can reflect either different abundances of the sexes or different sex-specific capture probabilities, and capture-recapture models can help distinguish between these two possibilities. Robust design models and a model selection procedure based on information-theoretic methods were applied to study the local population structure of the endemic Sardinian chalk hill blue butterfly, Polyommatus coridon gennargenti. Seasonal variations of abundance, plus daily and weather-related variations of active populations of males and females were investigated. Evidence was found of protandry and male pioneering of the breeding space. Temporary emigration probability, which describes the proportion of the population not exposed to capture (e.g. absent from the study area) during the sampling process, was estimated, differed between sexes, and was related to temperature, a factor known to influence animal activity. The correlation between temporary emigration and average daily temperature suggested interpreting temporary emigration as inactivity of animals. Robust design models were used successfully to provide a detailed description of the population structure and activity in this butterfly and are recommended for studies of local abundance and animal activity in the field.

  1. Incrusting and boring bryozoans from the Dessau Chalk Formation (Cretaceous), Little Walnut Creek, Austin, Texas

    SciTech Connect

    Morris, P.A. )

    1990-09-01

    Four sections were measured along a 1/4 mi length of Little Walnut Creek. The first section was 165 ft north of the US. 290 bridge while the fourth was 1/4 mi upstream. Structurally, the stream follows the fault in this section. Small faults can be found perpendicular to the primary fault and apparently account not only for minor variation in local dip (8{degrees}SE, parallel to 5{degrees}NW) but also for the placement of at least one tributary. Megainvertebrate exoskeletons were found to have been inhabited by incrusting bryozoans, boring bryozoans, and sponges. These fossils were found on both interior and exterior surfaces of Exogyra laeviuscula E tigrina, and interior surfaces of Inoceramus. A low-energy environment allowed exposure of megainvertebrate exoskeletons after death but also prevented fracturing. Low siltation rates also extended exoskeleton availability after organismic death. The nonboring bryozoans are cheilostomes and at least one species, Pyripora, has been described from the Kansas Cretaceous as well as European Cretaceous sites. The boring bryozoans are primarily represented by Terebripora sp. In conclusion, this section of Dessau Chalk Formation, Upper Austin Group, was mostly a low-energy environment, shallow, limy mud platform. This substrate was probably not stable enough for bryozoan colonization as unattached colonies have not been found in sediments. Therefore, bryozoan substrates were limited to living and dead Exogyra sp. and dead Inoceramus sp. exoskeletons.

  2. Paleomagnetism of late Cretaceous and Eocene limestones and chalks from Haiti - tectonic interpretations

    NASA Astrophysics Data System (ADS)

    van Fossen, Mickey C.; Channell, James E. T.

    1988-06-01

    We have conducted a paleomagnetic study of limestones and chalks from Haiti which suggests that the island of Hispaniola is a composite of at least two tectonically independent blocks. Sampling sites are distributed among three widely separated localities, namely: Les Cayes (nine sites; 18.3°N. Latitude; 73.6°W. Longitude) and Beloc (five sites; 18.4°N. Latitude; 72.6°W. Longitude) which are located on the southern peninsula of Haiti, and a northern locality, Ennery (six sites; 19.5°N. Latitude; 72.5°W. Longitude). Stable magnetization components of dual polarity and moderately high blocking temperature were revealed through progressive thermal demagnetization of samples from all of the Beloc and Ennery sites, while seven of the nine Les Cayes sites possessed unstable magnetizations. Mean paleolatitudes calculated from Beloc and Ennery data show 8° of latitudinal separation that is of at least Eocene age. Pole positions (Beloc: 43.2°N. Latitude; 185.8°E. Longitude, α95=25.1° and Ennery: 66.1°N. Latitude; 31.3°E. Longitude, α95=19.7°) show both colatitudinal and angular discordance with the North American apparent polar wander path. Based on these disparities, we demonstrate that the implied tectonic displacements tend to support some aspects of previously published Caribbean plate tectonic models.

  3. Long-term reactive transport modelling of Berea and chalk core flood experiment

    NASA Astrophysics Data System (ADS)

    Souza, A. V.; Godoy, J.; Tonietto, G.

    2013-12-01

    Carbon sequestration in geological structures establishes a long-term chemical system between the dissolved gas, fluids and rocks from the injection site. Thus, the time scale used to assess the progress of chemical reactions is normally between tens and hundreds of years. Geochemical modeling is used in a variety of fields, including environmental protection and remediation, the petroleum industry, and economic geology and it is one of the best alternatives to evaluate the reactions with geochemical data possible injection sites. In this work we used data presented in a recent article (SPE165500) in different scenarios injection with three scales 50, 100, 250 and 1000 years. The experimental data used were from core flood experiment Berea and chalk in a condition similar to those found in the reservoirs of the North Sea. (340 bar and 130 C). The approach used to the lack of appropriate kinetic parameter in reservoir conditions, was the use of experimental data collected in two different conditions (340 bar and 130 C) and (2 Bar at room temperature) after the rocky core. The numerical simulations carried out using the same conditions with two different geochemical softwares PHREEQC and TOUGHREACTS. The results provide a detailed understanding of the system resulting rock-fluid-CO2 in the medium and long term. However, the accuracy of the models is strongly dependent on the mineral primary and secondary cores found in rocks.

  4. Estimating organic maturity from well logs, Upper Cretaceous Austin Chalk, Texas Gulf coast

    SciTech Connect

    Hines, G.A.; Berg, R.R. )

    1990-09-01

    The Austin Chalk is both a source rock for oil and a fractured reservoir, and the evaluation of its organic maturity from well logs could be an aid to exploration and production. Geochemical measurements have shown three zones of organic maturity for source materials: (1) an immature zone to depths of 6,000 ft, (2) a peak-generation and accumulation zone from 6,000 to 6,500 ft, and (3) a mature, expulsion and migration zone below 6,500 ft. The response of common well logs identifies these zones. True resistivity (R{sub t}) is low in the immature zone, increases to a maximum in the peak-generation zone, and decreases to intermediate values in the expulsion zone. Density and neutron porosities are different in the immature zone but are nearly equal in the peak generation and expulsion zones. Correlations with conventional core analyses indicate that R{sub t} values between 9 and 40 ohm-m in the expulsion zone reflect a moveable oil saturation of 10 to 20% in the rock matrix. The moveable saturation provides oil from the matrix to fractures and is essential for sustained oil production. Therefore, the evaluation of moveable oil from well logs could be important in exploration.

  5. SIMULATIONS OF TWO-WELL TRACER TESTS IN STRATIFIED AQUIFERS AT THE CHALK RIVER AND THE MOBILE SITES

    EPA Science Inventory

    A simulation of two-well injection-withdrawal tracer tests in stratified granular aquifers is presented for two widely separated sites substantially different in terms of vertical distributions of hydraulic conductivity, well spacings, flow rates, test durations and tracer travel...

  6. Draft Genome Sequence of a Thermophilic Cyanobacterium from the Family Oscillatoriales (Strain MTP1) from the Chalk River, Colorado

    PubMed Central

    Grogger, Melanie; Mraz, Megan; Veverka, Donald

    2016-01-01

    The draft genome (57.7% GC, 7,647,882 bp) of the novel thermophilic cyanobacterium MTP1 was determined by metagenomics of an enrichment culture. The genome shows that it is in the family Oscillatoriales and encodes multiple heavy metal resistances as well as the capacity to make exopolysaccharides. PMID:26893415

  7. Draft Genome Sequence of a Thermophilic Cyanobacterium from the Family Oscillatoriales (Strain MTP1) from the Chalk River, Colorado.

    PubMed

    Hallenbeck, Patrick C; Grogger, Melanie; Mraz, Megan; Veverka, Donald

    2016-01-01

    The draft genome (57.7% GC, 7,647,882 bp) of the novel thermophilic cyanobacterium MTP1 was determined by metagenomics of an enrichment culture. The genome shows that it is in the family Oscillatoriales and encodes multiple heavy metal resistances as well as the capacity to make exopolysaccharides. PMID:26893415

  8. Nitrate concentrations in river waters of the upper Thames and its tributaries.

    PubMed

    Neal, Colin; Jarvie, Helen P; Neal, Margaret; Hill, Linda; Wickham, Heather

    2006-07-15

    The spatial and temporal patterns of in-stream nitrate concentrations for the upper Thames and selected tributaries are described in relation to point and diffuse sources for these rural catchments. The rivers associated with catchments dominated by permeable (Cretaceous Chalk) bedrock show a smaller range in nitrate concentrations than those associated with clay and mixed sedimentary bedrock of lower permeability. The differences reflect the contrasting nature of water storage within the catchments and the influence of point and diffuse sources of nitrate. Nitrate concentrations often increase in a gradual way as a function of flow for the rivers draining the permeable catchments, although there is usually a minor dip in nitrate concentrations at low to intermediate flow due to (1) within-river uptake of nitrate during the spring and the summer when biological activity is particularly high and (2) a seasonal fall in the water table and a change in preferential flow-pathway in the Chalk. There is also a decrease in the average nitrate concentration downstream for the Kennet where average concentrations decrease from around 35 to 25 mg NO(3) l(-1). For the lower permeability catchments, when point source inputs are not of major significance, nitrate concentrations in the rivers increase strongly with increasing flow and level off and in some cases then decline at higher flows. When point source inputs are important, the initial increase in nitrate concentrations do not always occur and there can even be an initial dilution, since the dilution of point sources of nitrate will be lowest under low-flow conditions. For the only two tributaries of the Thames which we have monitored for over 5 years (the Pang and the Kennet), nitrate concentrations have increased over time. For the main stem of the Thames, which was also monitored for over 5 years, there is no clear increase over time. As the Pang and the Kennet river water is mainly supplied from the Chalk, the

  9. Characterising the vertical variations in hydraulic conductivity within the Chalk aquifer

    NASA Astrophysics Data System (ADS)

    Williams, A.; Bloomfield, J.; Griffiths, K.; Butler, A.

    2006-10-01

    SummaryVarious field methods have been used to examine and quantify the vertical variations in aquifer properties within the Chalk aquifer at a LOCAR site in Berkshire, UK. The site contains three 100 m open boreholes and three sets of two nested piezometers within an area of about 100 m 2. There is also an 86 m deep abstraction borehole about 40 m from the site. The techniques that have been used at the site include: geophysical logging, borehole imaging, packer testing, dilution testing and pumping tests. The packer test results show that the permeability of the aquifer varies by three orders of magnitude over the 70 m of tested material with a strongly non-linear decrease with depth below ground level. Comparison with the borehole images show that some of the highly permeable zones appear to be associated with obvious fractures. However, large fractures can be seen in zones which have much lower permeability while some highly permeable zones appear to be associated with poorly developed fractures. Single borehole dilution tests have shown that there are differences in flow velocity depth profiles over a few tens of meters across the site. These are inferred to be because the different boreholes, although of similar drilled depth and very close proximity, intersect slightly different parts of the fracture network and hence the groundwater flow system. In particular, a flowing feature at the base of one borehole is not intersected by the second, which is drilled from a slightly higher elevation. A dilution test carried out whilst the aquifer was being pumped shows that different fractures become active when the aquifer is stressed. This has implications for the interpretation of flow logs performed under pumping.

  10. Fractional flow in fractured chalk; a flow and tracer test revisited

    NASA Astrophysics Data System (ADS)

    Odling, N. E.; West, L. J.; Hartmann, S.; Kilpatrick, A.

    2013-04-01

    A multi-borehole pumping and tracer test in fractured chalk is revisited and reinterpreted in the light of fractional flow. Pumping test data analyzed using a fractional flow model gives sub-spherical flow dimensions of 2.2-2.4 which are interpreted as due to the partially penetrating nature of the pumped borehole. The fractional flow model offers greater versatility than classical methods for interpreting pumping tests in fractured aquifers but its use has been hampered because the hydraulic parameters derived are hard to interpret. A method is developed to convert apparent transmissivity and storativity (L4-n/T and S2-n) to conventional transmissivity and storativity (L2/T and dimensionless) for the case where flow dimension, 2 < n < 3. These parameters may then be used in further applications, facilitating application of the fractional flow model. In the case illustrated, improved fits to drawdown data are obtained and the resultant transmissivities and storativities are found to be lower by 30% and an order of magnitude respectively, than estimates from classical methods. The revised hydraulic parameters are used in a reinterpretation of a tracer test using an analytical dual porosity model of solute transport incorporating matrix diffusion and modified for fractional flow. Model results show smaller fracture apertures, spacings and dispersivities than those when 2D flow is assumed. The pumping and tracer test results and modeling presented illustrate the importance of recognizing the potential fractional nature of flow generated by partially penetrating boreholes in fractured aquifers in estimating aquifer properties and interpreting tracer breakthrough curves.

  11. Geostatistical analysis of fault and joint measurements in Austin Chalk, Superconducting Super Collider Site, Texas

    SciTech Connect

    Mace, R.E.; Nance, H.S.; Laubach, S.E.

    1995-06-01

    Faults and joints are conduits for ground-water flow and targets for horizontal drilling in the petroleum industry. Spacing and size distribution are rarely predicted accurately by current structural models or documented adequately by conventional borehole or outcrop samples. Tunnel excavations present opportunities to measure fracture attributes in continuous subsurface exposures. These fracture measurements ran be used to improve structural models, guide interpretation of conventional borehole and outcrop data, and geostatistically quantify spatial and spacing characteristics for comparison to outcrop data or for generating distributions of fracture for numerical flow and transport modeling. Structure maps of over 9 mi of nearly continuous tunnel excavations in Austin Chalk at the Superconducting Super Collider (SSC) site in Ellis County, Texas, provide a unique database of fault and joint populations for geostatistical analysis. Observationally, small faults (<10 ft. throw) occur in clusters or swarms that have as many as 24 faults, fault swarms are as much as 2,000 ft. wide and appear to be on average 1,000 ft. apart, and joints are in swarms spaced 500 to more than 2l,000 ft. apart. Semi-variograms show varying degrees of spatial correlation. These variograms have structured sills that correlate directly to highs and lows in fracture frequency observed in the tunnel. Semi-variograms generated with respect to fracture spacing and number also have structured sills, but tend to not show any near-field correlation. The distribution of fault spacing can be described with a negative exponential, which suggests a random distribution. However, there is clearly some structure and clustering in the spacing data as shown by running average and variograms, which implies that a number of different methods should be utilized to characterize fracture spacing.

  12. Compaction of North-sea chalk by pore-failure and pressure solution in a producing reservoir

    NASA Astrophysics Data System (ADS)

    Keszthelyi, Daniel; Dysthe, Dag; Jamtveit, Bjorn

    2016-02-01

    The Ekofisk field, Norwegian North sea,is an example of compacting chalk reservoir with considerable subsequent seafloor subsidence due to petroleum production. Previously, a number of models were created to predict the compaction using different phenomenological approaches. Here we present a different approach, we use a new creep model based on microscopic mechanisms with no fitting parameters to predict strain rate at core scale and at reservoir scale. The model is able to reproduce creep experiments and the magnitude of the observed subsidence making it the first microstructural model which can explain the Ekofisk compaction.

  13. Comment on: Lawrence, J.A., Mortimore, R.N., Stone, K.J., Busby, J.P., 2013. Sea saltwater weakening of chalk and the impact on cliff instability. Geomorphology 191, 14-22

    NASA Astrophysics Data System (ADS)

    Dornbusch, Uwe

    2015-02-01

    This comment relates to the conclusion of the recently published paper that "This work challenges the established view by identifying the role of salt from seawater in the degradation of porous rocks in coastal environments as a third and potentially the most important mechanism leading to chalk cliff collapse." (Lawrence et al., 2013: 15). The 'established view' relates to "Traditionally, the two main factors leading to cliff collapse have been considered to be (i) waves attacking and eroding the base of the cliff […] and (ii) water weakening as the chalk becomes saturated […]." (Lawrence et al., 2013: 14). The particular aspect of the paper of making surface weakening the primary process has been picked up more widely following publication under the headlines 'Salt causes chalk cliffs to collapse' in Jarlett (2013), 'Salt makes chalk cliffs collapse' in NERC (2013) and in the web resource 'How does salt make chalk cliffs collapse?' from Leeds University (2013).

  14. Distribution and degradation of diesel oil in the unsaturated zone following an oil spill on a chalk aquifer

    NASA Astrophysics Data System (ADS)

    Ashley, R. P.; Lerner, D. N.; Lloyd, J. W.

    1994-07-01

    In 1976, there occurred a substantial loss of diesel oil from a storage facility at Royston in eastern England. The site is on the outcrop of the important Chalk aquifer, which is protected by an unsaturated zone 24-30 m thick. In 1986, a cored borehole was drilled through the site of the spillage to investigate the fate of the contaminants. The core samples were analysed by physical and chemical methods to determine the physical structure of the rock, and the characteristics and distribution of the oil. The chemically analysed samples included pore water extracts, scrapings from fracture surfaces, and non-fracture (matrix) samples. The results indicate that oil accumulated within a few millimetres of major fissure surfaces, and entry into the rock matrix was limited by the small size of pores and the presence of water. Oil may also have migrated along microscopic channels away from the major fissures. There was no evidence of downward migration of oil since the initial phase of movement. The adoption of certain assumptions regarding degradation, evaporation and dissolution processes allows the estimation of oil depletion caused by these processes. Physical weathering and degradation were found to have been extensive, but highly variable. Both processes occurred on the major fissure surfaces but, in the matrix, degradation appears to have been restricted. The conclusions have implications for the investigation and remediation of fissured Chalk aquifers contaminated by oil.

  15. Monitoring debris flow induced channel morphodynamics with terrestrial laser scanning, Chalk Cliffs, CO (Invited)

    NASA Astrophysics Data System (ADS)

    Wasklewicz, T. A.; Staley, D. M.

    2010-12-01

    Debris flows are important geomorphic agents in alpine drainages. They have been linked with channel initiation in headwater streams, connectivity of organic material and sediment through drainage basins, and as hazards to human development in and adjacent to steep watersheds. Debris flows also significantly alter channel morphometry at a variety of spatial scales. Of particular interest are topographic changes associated with multiple surge fronts within a debris flow as well as between several debris flows. An unnamed tributary stream to Chalk Creek, CO has over the last decade experienced one to four debris flow events annually. Four field sampling campaigns were conducted in the summer and fall of 2009. A Leica ScanStation 2, in conjunction with a robust local control network, were used to capture channel morphodynamics along five stream reaches prior to the debris flow season and after three debris flows. Point cloud data from the scanner permit the generation of two centimeter planimetric resolution digital terrain models (DTM). DTM-of-difference analyses and measures of slope, roughness, sediment transport volumes and channel dimensions were employed to detect spatial and temporal morphometric changes. The first debris flow occurred on unsaturated bed material and resulted in aggradation along 3 of the 5 reaches. One reach, a bedrock step, remained relatively unchanged, while the final reach saw significant erosion along boulder steps in the channel and an associated mass failure adjacent to the stream bank through this section. The second debris flow resulted in net aggradation along all of the reaches. The third and largest debris flow took place on saturated bed materials. The flow produced net erosion along all reaches. Significant channel changes were associated with the headward erosion of debris flow snouts and bank failures associated with undercutting of angle-of-repose slopes during debris flow erosion. Analysis of the potential relationships

  16. Comparative estimates of transpiration of ash and beech forest at a chalk site in southern Britain

    NASA Astrophysics Data System (ADS)

    Roberts, John; Rosier, Paul T. W.

    1994-11-01

    (1) During the dry summer of 1989 stomatal conductance ( gs), boundary-layer conductance ( ga), leaf water and osmotic potentials ( ψ1, ψπ) and leaf area index ( L∗) measurements were made in mature ash and beech stands growing on shallow soil over chalk near Winchester, Hampshire, UK. In addition measurements of gs and L∗ were made in the understorey layer in the ash stand, comprised mainly of dog's mercury, hazel and bramble. Automatic weather stations located (i) above the beech stand and (ii) at the understorey level (within the ash stand) provided hourly averages of weather variables. Changes in soil moisture deficit in both stands were determined from regular measurements made with a neutron probe. (2) Maximum values of gs (up to 0.3 mol m -2 s -1) were found at the top of the ash and beech canopies at the start of the day, while at the canopy base gs was about half of these values. At all canopy levels the value of gs was more closely associated with specific humidity deficit (at the time of measurement) than with any other weather variable, and there was no relationship between gs and soil mositure deficit or leaf water status, described by ψ1 and ψπ on the day of measurement. (3) Values of gs of the understorey plants were only half those of the tree species and changed less during the day. However, seasonal changes in gs of dog's mercury did seem to be associated with increased soil moisture deficit. (4) Estimates of L∗ in the ash and beech stands were made from leaf litter collections and partitioned into canopy layers using ratios determined by destructive sampling. L∗ of the beech stand was 5.3 and for the ash stand 2.7. L∗ of the understorey varied seasonally and rose to a peak of 3 in June falling gradually for the remainder of the summer period. (5) Hourly values of gs and ga in each stand for each canopy layer were scaled up to the canopy by using L∗ of the individual canopy layers (including the understorey level in the ash stand

  17. Laboratory and field measurements of the self-potential (SP) in chalk, with application to monitoring of saline intrusion

    NASA Astrophysics Data System (ADS)

    MacAllister, D.; Jackson, M.; Butler, A. P.; Vinogradov, J.

    2013-12-01

    Saline intrusion is a global phenomenon, affecting the availability of freshwater in coastal aquifers. The aim of this work is to investigate whether measurements of self-potential (SP) can be used to monitor the intrusion of seawater into coastal aquifers, with specific application to the UK chalk aquifer in the vicinity of Brighton on the south coast of the UK. The SP arises to maintain electrical neutrality when a separation of charge occurs due to gradients in pressure (electrokinetic (EK) or streaming potential) and concentration (electrochemical (EC) potential). Concentration gradients are a characteristic feature of saline intrusion and may give rise to a measureable EC potential. In addition, an EK potential will arise during abstraction. Laboratory and field SP measurements are used to investigate the magnitude of the EK and EC potentials in the UK chalk aquifer during saline intrusion. Laboratory measurements yield an EK coupling coefficient, relating the gradient in voltage to the gradient in pressure when the total current is zero, of -60 mV/MPa in samples saturated with groundwater, and -1 mV/MPa in samples saturated with seawater. This result agrees with earlier work suggesting the EK potential is suppressed at high salinity due to a compressed electrical double layer. The EC coupling is dominated by diffusion potentials arising from the concentration gradient across the saline front. Field experiments suggest that the EK component of the SP in the chalk is very small under ambient conditions, even in freshwater zones, because gradients in hydraulic head are small owing to the high conductivity of the pervasive fracture networks. However, a pumping test conducted in the chalk aquifer at a field site in Berkshire induced a measureable EK response with a coupling coefficient of magnitude consistent with the freshwater EK coupling coefficient obtained in the laboratory. SP monitoring at an observation borehole near Brighton reveals semi-diurnal SP

  18. Chalk Is Cheap: Nurturing Teachers in a Famine Culture Professional Starvation Is Gnawing Away At Teacher Motivation. Here Are Some Ways For Principals To Provide Needed Nutrition.

    ERIC Educational Resources Information Center

    Schmidt, Laurel

    2005-01-01

    Scarcity has been such a constant in education for so long that self-sufficient teachers routinely purchase classroom supplies at their own expense. Sometimes desperate measures are needed to obtain even the most basic equipment. I heard of a teacher whose chalkboard was so slick from years of use that it had become chalk-proof. Her first graders…

  19. Assessment of undiscovered oil and gas resources of the Upper Cretaceous Austin Chalk and Tokio and Eutaw Formations, Gulf Coast, 2010

    USGS Publications Warehouse

    Pearson, Krystal; Dubiel, R.F.; Pearson, O.N.; Pitman, J.K.

    2011-01-01

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated means of 957 million barrels of undiscovered oil, 3.6 trillion cubic feet of undiscovered natural gas, and 363 million barrels of undiscovered natural gas liquids in the Austin Chalk and Tokio and Eutaw Formations in onshore lands and State waters of the Gulf Coast.

  20. High frequency seismic monitoring of debris flows at Chalk Cliffs (CO), USA

    NASA Astrophysics Data System (ADS)

    Coviello, Velio; Kean, Jason; Smith, Joel; Coe, Jeffrey; Arattano, Massimo; McCoy, Scott

    2015-04-01

    A growing number of studies adopt passive seismic monitoring techniques to investigate slope instabilities and landslide processes. These techniques are attractive and convenient because large areas can be monitored from a safe distance. This is particularly true when the phenomena under investigation are rapid and infrequent mass movements like debris flows. Different types of devices are used to monitor debris flow processes, but among them ground vibration detectors (GVDs) present several, specific advantages that encourage their use. These advantages include: (i) the possibility to be installed outside the channel bed, (ii) the high adaptability to different and harsh field conditions, and (iii) the capability to detect the debris flow front arrival tens of seconds earlier than contact and stage sensors. Ground vibration data can provide relevant information on the dynamics of debris flows such as timing and velocity of the main surges. However, the processing of the raw seismic signal is usually needed, both to obtain a more effective representation of waveforms and to decrease the amount of data that need to be recorded and analyzed. With this objective, the methods of Amplitude and Impulses are commonly adopted to transform the raw signal to a 1-Hz signal that allows for a more useful representation of the phenomenon. In that way, peaks and other features become more visible and comparable with data obtained from other monitoring devices. In this work, we present the first debris flows seismic recordings gathered in the Chalk Cliffs instrumented basin, central Colorado, USA. In May 2014, two 4.5-Hz, three-axial geophones were installed in the upper part of the catchment. Seismic data are sampled at 333 Hz and then recorded by a standalone recording unit. One geophone is directly installed on bedrock, the other one mounted on a 1-m boulder partially buried in colluvium. This latter sensor integrates a heavily instrumented cross-section consisting of a 225 cm2

  1. Porosity and permeability development in compacting chalks during flooding of nonequilibrium brines: Insights from long-term experiment

    NASA Astrophysics Data System (ADS)

    Nermoen, Anders; Korsnes, Reidar I.; Hiorth, Aksel; Madland, Merete V.

    2015-05-01

    We report the complete chemical alteration of a Liège outcrop chalk core resulting from a 1072 flow-through experiment performed during mechanical compaction at 130°C. Chemical rock-fluid interactions alter the volumetric strain, porosity, and permeability in a nontrivial way. The porosity reduced only from 41.32% to 40.14%, even though the plug compacted more than 25%. We present a novel analysis of the experimental data, which demonstrates that the geochemical alteration does not conserve the volume of the solids, and therefore, the strain is partitioned additively into a pore volume and solid volume component. At stresses beyond yield, the observed deformation can be explained by grain reorganization reducing the pore space between grains and solid volume changes from the rock-fluid interactions. The mechanical and chemical effects are discussed in relation to the observed permeability development.

  2. Case history of an opposed-bore, dual horizontal well in the Austin Chalk formation of south Texas

    SciTech Connect

    Cooney, M.F.; Rogers, C.T.; Stacey, E.S.; Stephens, R.N.

    1993-03-01

    Petro-Hunt Corp. used a unique horizontal-well design to optimize development of an irregularly shaped lease in the Austin chalk formation in Texas. Two medium-radius horizontal bores were drilled in opposite directions from one vertical hole to maximize horizontal displacement in the lease. Underbalanced drilling techniques were used to prevent formation damage. The well design resulted in a significant cost savings per horizontal foot compared with 24 offset wells that the operator drilled. This paper reviews well planning and drilling and emphasizes techniques used to intersect thin horizontal targets and to initiate the second horizontal bore. Production results and drilling economics are discussed briefly, and ideas on future dual-horizontal-well applications are presented.

  3. Mycorrhizal symbiosis effects on growth of chalk false-brome (Brachypodium pinnatum) are dependent on the environmental light regime.

    PubMed

    Füzy, Anna; Bothe, Hermann; Molnár, Edit; Biró, Borbála

    2014-03-01

    AMF (arbuscular mycorrhizal fungi) colonization of the grass chalk false-brome (Brachypodium pinnatum (L.) P. B.) was studied in selected habitats under spatially different light regimes: (a) shade condition under oak trees, (b) half shade in a shrubby area and (c) full-sun conditions on unshaded grassland. This study assessed the variations in AMF colonization of the grass dependent on the light supply in field habitats. Soil, root and shoot samples were collected four times during the vegetation period (in June, July, September and October). Root colonization, root and shoot biomass as well as soil water content were determined. The highest rate of AMF colonization was detected in June under half-sun and full-sun conditions, where about 50% of the roots were colonized. The average amount of arbuscules was less than 20% in the roots at the three sites, with the highest number of arbuscules in June, under half-sun and full-sun conditions, however, not under the trees. Overall, best mycorrhizal colonization occurred during summer, and its rate decreased in autumn. This tendency inversely correlated with the amount of precipitation, and thus with the water content of soils. The high colonization rate of the examined root samples, and also its seasonal fluctuation, might reflect the importance of the symbiosis where inorganic nutrients and water are the growth-limiting factors. The marginal AMF colonization of chalk false-brome under shade conditions indicates that plants do not use AMF under all stress conditions. When low light limits photosynthesis and thus growth of the plants, they dispense with the colonization of AMF in order to save the expenditure of organic carbon. PMID:24484951

  4. Amazon River

    Atmospheric Science Data Center

    2013-04-17

    article title:  Mouth of the Amazon River     View Larger Image ... over 6450 kilometers eastward across Brazil, the Amazon River originates in the Peruvian Andes as tiny mountain streams that eventually ...

  5. Nile River

    Atmospheric Science Data Center

    2013-04-15

    article title:  Nile River Fluctuations Near Khartoum, Sudan     ... history, the rising and falling waters of the mighty Nile River have directly impacted the lives of the people who live along its banks. ... the area around Sudan's capital city of Khartoum capture the river's dynamic nature. Acquired by the Multi-angle Imaging SpectroRadiometer ...

  6. Mississippi River

    Atmospheric Science Data Center

    2014-05-15

    article title:  Mississippi River Flooding during Spring 2001     ... South TIFF: 1024 x 724 The Mississippi River, from its source at Lake Itasca Minnesota to the Gulf of Mexico is ... 2348 miles long. Over the course of it's history, the mighty river has flooded many times. The largest flood recorded in the lower valley ...

  7. Niger River

    Atmospheric Science Data Center

    2013-04-15

    article title:  Niger River after the Rainy Season     View larger image The third largest river in Africa, the Niger, forms an inland delta in central Mali. This ... is situated near the top of the image, where the Niger River changes direction to flow more directly eastward. Six hundred years ago, ...

  8. Modeling of ground-water flow in subsurface Austin Chalk and Taylor marl in Ellis County, Texas, near the superconducting super collider site

    SciTech Connect

    Mace, R.E. . Bureau of Economic Geology)

    1993-02-01

    Numerical models are useful tools for developing an understanding of ground-water flow in sparsely characterized low-permeability aquifers. Finite-difference, cross-sectional models of Cretaceous chalk and marl formations near the Superconducting Super Collider (SSC) were constructed using MODFLOW to evaluate ground-water circulation paths and travel times. Weathered and fractured zones with enhanced permeability were included to assess the effect these features had on flow paths and times. Pump tests, slug tests, packer tests, core tests, and estimates were used to define hydraulic properties for model input. The model was calibrated with water-level data from monitor wells and from wire-line piezometers near a test shaft excavated by the SSC project. A ratio of vertical-to-horizontal permeability of 0.0085 was estimated through model calibration. A chalk-to-marl permeability ratio of 18 was needed to reproduce artesian head in a well completed in chalk beneath marl. Hydraulic head distributions and ground-water flow paths reflected local, intermediate, and regional flow systems with recharge beneath upland surface-water divides and discharge in valleys. Most of the flow (99%) occurred in the weathered zone, with average residence times of 5 to 10 years. Residence time in unweathered chalk bedrock was substantially longer, at an average of 1.7 Ma. As expected, the model demonstrated that deep and rapid ground-water circulation might occur in fracture zones. Particle paths calculated using MODPATH showed that ground-water travel times from recharge areas to the SSC subsurface facilities might be 20 to 60 years where flow is through fracture zones.

  9. Area balance and strain in an extensional fault system: Strategies for improved oil recovery in fractured chalk, Gilbertown Field, southwestern Alabama. Final report, March 1996--September 1998

    SciTech Connect

    Pashin, J.C.; Raymond, D.E.; Rindsberg, A.K.; Alabi, G.G.; Carroll, R.E.; Groshong, R.H.; Jin, G.

    1998-12-01

    This project was designed to analyze the structure of Mesozoic and Tertiary strata in Gilbertown Field and adjacent areas to suggest ways in which oil recovery can be improved. The Eutaw Formation comprises 7 major flow units and is dominated by low-resistivity, low-contrast play that is difficult to characterize quantitatively. Selma chalk produces strictly from fault-related fractures that were mineralized as warm fluid migrated from deep sources. Resistivity, dipmeter, and fracture identification logs corroborate that deformation is concentrated in the hanging-wall drag zones. New area balancing techniques were developed to characterize growth strata and confirm that strain is concentrated in hanging-wall drag zones. Curvature analysis indicates that the faults contain numerous fault bends that influence fracture distribution. Eutaw oil is produced strictly from footwall uplifts, whereas Selma oil is produced from fault-related fractures. Clay smear and mineralization may be significant trapping mechanisms in the Eutaw Formation. The critical seal for Selma reservoirs, by contrast, is where Tertiary clay in the hanging wall is juxtaposed with poorly fractured Selma chalk in the footwall. Gilbertown Field can be revitalized by infill drilling and recompletion of existing wells. Directional drilling may be a viable technique for recovering untapped oil from Selma chalk. Revitalization is now underway, and the first new production wells since 1985 are being drilled in the western part of the field.

  10. Sedimentology and carbon-isotope stratigraphy of the Late Cretaceous Chalk Group in the Höllviken-1 core (SW Sweden)

    NASA Astrophysics Data System (ADS)

    Bøttger, Dorthe; Thibault, Nicolas; Anderskouv, Kresten

    2016-04-01

    The Höllviken-1 borehole is situated on the Skåne peninsula (SW Sweden) which was part of the Danish Basin in the Late Cretaceous. 1415 meters have been cored among which ca. 1100 meters cover the complete Upper Cretaceous to lower Danian Chalk Group. Besides the publication of a synthetic log and detailed foraminifer biozonation, supplemented by a number of rare macrofossil findings and description of a number of foraminifer holotypes (Brötzen, 1944), very few studies of the core have actually been performed, since the mid 1940s. A new project has thus been undertaken aiming at improving the stratigraphy of the Chalk Group in the Höllviken-1 core. The data presented here comprise the description of the interval 837-489 m covering a large part of the Campanian and the lower Maastrichtian. Two intervals with the presence of sand are noted in the Campanian and two intervals showing possibly progradational sequences of arenaceous marls to sand are present in the Maastrichtian. The purpose of this new study is to revise the foraminifer biostratigraphy of Brötzen and complement it with high-resolution carbon-isotope stratigraphy in order to establish a new age-model for the core and better constrain the timing of siliciclastic input into the Danish Basin. In addition, high-resolution sedimentological data will be used as a preliminary test for cyclostratigraphy of the chalk-marl intervals.

  11. Copper cycling in the Patuxent River estuary and condenser micro-fouling studies

    SciTech Connect

    Eaton, A.; Chamberlain, C.

    1982-01-01

    This report describes the methods and results of a study of copper cycling in the Patuxent River estuary. The study focused on detailed sampling of the water column over a number of seasons to determine: (1) the amount of excess copper in the estuary which may be attributable to corrosion of condenser tubes at the Chalk Point Power Plant; (2) the geographic distribution of excess copper in the estuary, (3) the forms of excess copper, and (4) the fate of added copper. Extensive sampling was performed including sampling above and below the pycnocline, sampling in cross channel transects and resampling stations at different tidal stages to establish short term variability. Estimates for the amount of excess copper in the Patuxent are derived and the potential impact of that excess is assessed. This report also presents the results of studies of micro-fouling processes in power plant condensers employing once-through cooling. The studies entailed: (1) the isolation and characterization of 38 bacterial isolates from effluents and condenser tubes of the Crane Power Plant which is located on Saltpeter Creek, approximately ten miles northeast of Baltimore, Maryland and the Chalk Point Power Plant on the Patuxent River, (2) laboratory experiments on colonization rates using pure cultures at high nutrient levels, and (3) growth studies on the joint influence of copper and nutrient levels.

  12. AECL/US INERI - Development of Inert Matrix Fuels for Plutonium and Minor Actinide Management in Power Reactors -- Fuel Requirements and Down-Select Report

    SciTech Connect

    William Carmack; Randy D. Lee; Pavel Medvedev; Mitch Meyer; Michael Todosow; Holly B. Hamilton; Juan Nino; Simon Philpot; James Tulenko

    2005-06-01

    The U.S. Advanced Fuel Cycle Program and the Atomic Energy Canada Ltd (AECL) seek to develop and demonstrate the technologies needed to minimize the overall Pu and minor actinides present in the light water reactor (LWR) nuclear fuel cycles. It is proposed to reuse the Pu from LWR spent fuel both for the energy it contains and to decrease the hazard and proliferation impact resulting from storage of the Pu and minor actinides. The use of fuel compositions with a combination of U and Pu oxide (MOX) has been proposed as a way to recycle Pu and/or minor actinides in LWRs. It has also been proposed to replace the fertile U{sup 238} matrix of MOX with a fertile-free matrix (IMF) to reduce the production of Pu{sup 239} in the fuel system. It is important to demonstrate the performance of these fuels with the appropriate mixture of isotopes and determine what impact there might be from trace elements or contaminants. Previous work has already been done to look at weapons-grade (WG) Pu in the MOX configuration [1][2] and the reactor-grade (RG) Pu in a MOX configuration including small (4000 ppm additions of Neptunium). This program will add to the existing database by developing a wide variety of MOX fuel compositions along with new fuel compositions called inert-matrix fuel (IMF). The goal of this program is to determine the general fabrication and irradiation behavior of the proposed IMF fuel compositions. Successful performance of these compositions will lead to further selection and development of IMF for use in LWRs. This experiment will also test various inert matrix material compositions with and without quantities of the minor actinides Americium and Neptunium to determine feasibility of incorporation into the fuel matrices for destruction. There is interest in the U.S. and world-wide in the investigation of IMF (inert matrix fuels) for scenarios involving stabilization or burn down of plutonium in the fleet of existing commercial power reactors. IMF offer the

  13. Infiltration processes in karstic chalk investigated through a spatial analysis of the geochemical properties of the groundwater: The effect of the superficial layer of clay-with-flints

    NASA Astrophysics Data System (ADS)

    Valdes, Danièle; Dupont, Jean-Paul; Laignel, Benoît; Slimani, Smaïl; Delbart, Célestine

    2014-11-01

    In the Paris Basin in Upper Normandy (France), the chalk plateaus are covered with thick deposits of loess and clay-with-flints, from a few meters to approximately 40 m thick locally. A perched groundwater is sometimes observed in the superficial layers in which evapotranspiration processes seem to occur. This study's objective was to understand the effects of the thick clay-with-flints layers on the infiltration processes. To achieve this, we adopted a spatial approach comparing the maps of the geochemical properties of the Chalk groundwater and the maps of the thickness of clay-with-flints. The French national groundwater database, ADES (Accès aux Données des Eaux, BRGM), provided the mean geochemical properties in the Chalk aquifer of Upper Normandy. This database was used to prepare maps of the environmental tracers: Ca2+, HCO3-, Mg2+, Cl-, Na+, NO3-, and SO42. The data are spatially well organized. Using principal component analysis (PCA), these maps were compared with the maps of the thickness of clay-with-flints. A focus on the coastal basins (northern Upper Normandy) shows a very strong spatial correlation between the maps of clay-with-flints thickness and all of the maps of the major ions. The thickness of clay-with-flints is negatively correlated with the autochthonous ions (HCO3- and Ca2+) and is positively correlated with the allochthonous ions (Cl-, Na+, SO42-, and NO3-). These results highlight that the thickness of clay-with-flints controls recharge. Two types of infiltration processes are proposed: (1) Thicker clay-with-flints allows storage in the perched groundwater, which allows evapotranspiration, resulting in high concentrations of allochthonous ions and a decrease in the dissolution potential of water and low concentrations of autochthonous ions. The infiltration of the perched groundwater is thus delayed and concentrated. (2) Thinner clay-with-flints causes the infiltration to be more diffuse, with low evapotranspiration and thus low

  14. Observations of debris flows at Chalk Cliffs, Colorado, USA: Part 1, in-situ measurements of flow dynamics, tracer particle movement and video imagery from the summer of 2009

    USGS Publications Warehouse

    McCoy, Scott W.; Coe, Jeffrey A.; Kean, Jason W.; Tucker, Greg E.; Staley, Dennis M.; Wasklewicz, Thad A.

    2011-01-01

    Debris flows initiated by surface-water runoff during short duration, moderate- to high-intensity rainfall are common in steep, rocky, and sparsely vegetated terrain. Yet large uncertainties remain about the potential for a flow to grow through entrainment of loose debris, which make formulation of accurate mechanical models of debris-flow routing difficult. Using a combination of in situ measurements of debris flow dynamics, video imagery, tracer rocks implanted with passive integrated transponders (PIT) and pre- and post-flow 2-cm resolution digital terrain models (terrain data presented in a companion paper by STALEY et alii, 2011), we investigated the entrainment and transport response of debris flows at Chalk Cliffs, CO, USA. Four monitored events during the summer of 2009 all initiated from surface-water runoff, generally less than an hour after the first measurable rain. Despite reach-scale morphology that remained relatively constant, the four flow events displayed a range of responses, from long-runout flows that entrained significant amounts of channel sediment and dammed the main-stem river, to smaller, short-runout flows that were primarily depositional in the upper basin. Tracer-rock travel-distance distributions for these events were bimodal; particles either remained immobile or they travelled the entire length of the catchment. The long-runout, large-entrainment flow differed from the other smaller flows by the following controlling factors: peak 10-minute rain intensity; duration of significant flow in the channel; and to a lesser extent, peak surge depth and velocity. Our growing database of natural debris-flow events can be used to develop linkages between observed debris-flow transport and entrainment responses and the controlling rainstorm characteristics and flow properties.

  15. How spatial variations of chalk groundwater geochemistry are related to superficial formations and infiltration processes of unsaturated zone (quarry of Saint Martin le Noeud, France)

    NASA Astrophysics Data System (ADS)

    Barhoum, Sarah; Valdès-Lao, Danièle; Guérin, Roger; Gombert, Philippe

    2013-04-01

    Chalk is complex because of its dual porosity and because of superficial layers more or less thick and more or less permeable. Furthermore there is few knowledge in understanding of groundwater infiltration and dissolution processes in the chalk unsaturated zone (UZ). The role of superficial formations has to be studied especially. The experimental site is an ancient underground quarry of chalk which extends over 1200 m long and 150 m wide (30 m depth) in Saint Martin le Noeud, south of Beauvais, France. This quarry is particularly interesting to study infiltration and dissolution processes indeed this site allows to access to the interface between the unsaturated zone and the saturated zone. Water percolates from the top of the quarry more or less depending on the season. Water table outcrops in the cave and makes about 20 underground lakes. Above the quarry chalk is covered clay-with-flints (CWF) and loess, in surface there are cultivated crops fields. On the first year of the study, physicochemical parameters: temperature, depth, pH, conductivity were recorded in seven lakes with high frequency (every hour). During the same period we sampled the 20 lakes water every month to measure major ions. During this sampling period, percolation was not sufficient to collect percolated water. Results of underground GPS, electric resistivity tomography and observations of three borehole showed that thickness unsaturated zone and that the thicknesses of the superficial formations vary a lot spatially. Three interesting points (separated by less than 1 km) are presented: the above the Pedro lake (25 m of UZ, a few cm of CWF), above the Stalactites lake (30 m of UZ, more than 2.40 m of CWF); above the Blue lake (35 m depth, 60 cm of CWF). First results of chemistry showed that the temporal variation is very low during the first year but there spatial variation is very important at quarry scale. The geochemistry of the lakes are very different: HCO3- varies from 100 to 250mg

  16. Water quality along a river continuum subject to point and diffuse sources

    NASA Astrophysics Data System (ADS)

    Neal, Colin; Jarvie, Helen P.; Love, Alison; Neal, Margaret; Wickham, Heather; Harman, Sarah

    2008-02-01

    SummaryThe water quality along the River Kennet, in the Thames basin of southern England, was examined in terms of the influence of point- and diffuse-nutrient inputs. The river is supplied mainly from a Cretaceous Chalk aquifer and hence the waters are of a calcium bicarbonate type. The nitrate largely comes from agricultural sources, with concentrations decreasing downstream due to plant uptake and probable denitrification. In contrast, soluble reactive phosphorus (SRP) is largely associated with sewage inputs and concentrations increase downstream in line with effluents from major towns such as Newbury and Reading. Adjacent to the river in the lower half of the catchment is the Kennet and Avon Canal and the two are in places hydrologically connected. The canal inputs may influence calcium carbonate (calcite) precipitation and increase suspended sediment and particulate phosphorus concentrations in the river. Monitoring upstream and downstream of Marlborough sewage treatment works (STW) showed that SRP concentrations in the effluent were highly variable due to variable efficiency of P stripping and still sufficiently concentrated to dominate downstream river SRP with potential impacts on stream ecology. Biological recovery in this river following P stripping at STWs is complex and controlling those spikes in SRP that are above a threshold of 100 μg l -1 may be a critical requirement. More stringent effluent targets than are currently recommended may be needed (less than 800 μg RP l -1) to achieve good ecological status in this river depending on SRP concentrations upstream.

  17. Identification of a New Hesperornithiform from the Cretaceous Niobrara Chalk and Implications for Ecologic Diversity among Early Diving Birds

    PubMed Central

    Bell, Alyssa; Chiappe, Luis M.

    2015-01-01

    The Smoky Hill Member of the Niobrara Chalk in Kansas (USA) has yielded the remains of numerous members of the Hesperornithiformes, toothed diving birds from the late Early to Late Cretaceous. This study presents a new taxon of hesperornithiform from the Smoky Hill Member, Fumicollis hoffmani, the holotype of which is among the more complete hesperornithiform skeletons. Fumicollis has a unique combination of primitive (e.g. proximal and distal ends of femur not expanded, elongate pre-acetabular ilium, small and pyramidal patella) and derived (e.g. dorsal ridge on metatarsal IV, plantarly-projected curve in the distal shaft of phalanx III:1) hesperornithiform characters, suggesting it was more specialized than small hesperornithiforms like Baptornis advenus but not as highly derived as the larger Hesperornis regalis. The identification of Fumicollis highlights once again the significant diversity of hesperornithiforms that existed in the Late Cretaceous Western Interior Seaway. This diversity points to the existence of a complex ecosystem, perhaps with a high degree of niche partitioning, as indicated by the varying degrees of diving specializations among these birds. PMID:26580402

  18. Diagnosing hydrological limitations of a Land Surface Model: application of JULES to a deep-groundwater chalk basin

    NASA Astrophysics Data System (ADS)

    Le Vine, N.; Butler, A.; McIntyre, N.; Jackson, C.

    2015-08-01

    Land Surface Models (LSMs) are prospective starting points to develop a global hyper-resolution model of the terrestrial water, energy and biogeochemical cycles. However, there are some fundamental limitations of LSMs related to how meaningfully hydrological fluxes and stores are represented. A diagnostic approach to model evaluation is taken here that exploits hydrological expert knowledge to detect LSM inadequacies through consideration of the major behavioural functions of a hydrological system: overall water balance, vertical water redistribution in the unsaturated zone, temporal water redistribution and spatial water redistribution over the catchment's groundwater and surface water systems. Three types of information are utilised to improve the model's hydrology: (a) observations, (b) information about expected response from regionalised data, and (c) information from an independent physics-based model. The study considers the JULES (Joint UK Land Environmental Simulator) LSM applied to a deep-groundwater chalk catchment in the UK. The diagnosed hydrological limitations and the proposed ways to address them are indicative of the challenges faced while transitioning to a global high resolution model of the water cycle.

  19. Projecting impacts of climate change on hydrological conditions and biotic responses in a chalk valley riparian wetland

    NASA Astrophysics Data System (ADS)

    House, A. R.; Thompson, J. R.; Acreman, M. C.

    2016-03-01

    Projected changes in climate are likely to substantially impact wetland hydrological conditions that will in turn have implications for wetland ecology. Assessing ecohydrological impacts of climate change requires models that can accurately simulate water levels at the fine-scale resolution to which species and communities respond. Hydrological conditions within the Lambourn Observatory at Boxford, Berkshire, UK were simulated using the physically based, distributed model MIKE SHE, calibrated to contemporary surface and groundwater levels. The site is a 10 ha lowland riparian wetland where complex geological conditions and channel management exert strong influences on the hydrological regime. Projected changes in precipitation, potential evapotranspiration, channel discharge and groundwater level were derived from the UK Climate Projections 2009 ensemble of climate models for the 2080s under different scenarios. Hydrological impacts of climate change differ through the wetland over short distances depending on the degree of groundwater/surface-water interaction. Discrete areas of groundwater upwelling are associated with an exaggerated response of water levels to climate change compared to non-upwelling areas. These are coincident with regions where a weathered chalk layer, which otherwise separates two main aquifers, is absent. Simulated water levels were linked to requirements of the MG8 plant community and Desmoulin's whorl snail (Vertigo moulinsiana) for which the site is designated. Impacts on each are shown to differ spatially and in line with hydrological impacts. Differences in water level requirements for this vegetation community and single species highlight the need for separate management strategies in distinct areas of the wetland.

  20. Diagnosing hydrological limitations of a land surface model: application of JULES to a deep-groundwater chalk basin

    NASA Astrophysics Data System (ADS)

    Le Vine, N.; Butler, A.; McIntyre, N.; Jackson, C.

    2016-01-01

    Land surface models (LSMs) are prospective starting points to develop a global hyper-resolution model of the terrestrial water, energy, and biogeochemical cycles. However, there are some fundamental limitations of LSMs related to how meaningfully hydrological fluxes and stores are represented. A diagnostic approach to model evaluation and improvement is taken here that exploits hydrological expert knowledge to detect LSM inadequacies through consideration of the major behavioural functions of a hydrological system: overall water balance, vertical water redistribution in the unsaturated zone, temporal water redistribution, and spatial water redistribution over the catchment's groundwater and surface-water systems. Three types of information are utilized to improve the model's hydrology: (a) observations, (b) information about expected response from regionalized data, and (c) information from an independent physics-based model. The study considers the JULES (Joint UK Land Environmental Simulator) LSM applied to a deep-groundwater chalk catchment in the UK. The diagnosed hydrological limitations and the proposed ways to address them are indicative of the challenges faced while transitioning to a global high resolution model of the water cycle.

  1. Phosphorus dynamics and productivity in a sewage-impacted lowland chalk stream

    NASA Astrophysics Data System (ADS)

    Palmer-Felgate, Elizabeth J.; Jarvie, Helen P.; Williams, Richard J.; Mortimer, Robert J. G.; Loewenthal, Matthew; Neal, Colin

    2008-03-01

    SummaryHourly in situ phosphorus, conductivity, turbidity, dissolved oxygen, pH, and chlorophyll measurements were collected from January 2004 to November 2006 for the River Kennet, 2 km downstream of a sewage effluent inlet. Excess carbon dioxide pressure (EpCO 2) was calculated from continuous pH and spot alkalinity measurements. EpCO 2 and dissolved oxygen were used to estimate rates of photosynthesis and respiration. These parameters were examined alongside flow, water temperature and solar radiation to explore controls on phosphorus dynamics and in-stream productivity. Diurnal, event and seasonal patterns were observed in phosphorus concentrations. The diurnal and seasonal variations appeared to be related to the upstream sewage treatment works. The event patterns coincided with periods of high flow, and were attributed to diffuse sources. Chlorophyll behaved independently of phosphorus concentration and returned to baseline levels before photosynthesis rate. This indicated that, during the period of study, in-stream productivity was primarily controlled by aquatic plants other than phytoplankton.

  2. Amazon River

    Atmospheric Science Data Center

    2013-04-17

    ... the Rio Solimoes and the Rio Negro converge to form the Amazon River. This image from the Multi-angle Imaging SpectroRadiometer (MISR) ... date:  Jul 23, 2000 Images:  Amazon River location:  South America thumbnail:  ...

  3. Mississippi River

    Atmospheric Science Data Center

    2014-05-15

    ... View Larger Image The mighty Mississippi River, from its source at Lake Itasca, Minnesota to the Gulf of Mexico, is ... heavy rainfall on areas traversed by the upper Mississippi River. Each image in this pair covers an identical 195-kilometer x ...

  4. Origin of nickel in water solution of the chalk aquifer in the north of France and influence of geochemical factors

    NASA Astrophysics Data System (ADS)

    Bernard, Daniel; El Khattabi, Jamal; Lefevre, Emilie; Serhal, Hani; Bastin-Lacherez, Sabine; Shahrour, Isam

    2008-01-01

    In the north of France, high registers of nickel are sometimes recorded within the chalk aquifer. In a confined context, the presence of pyrite in the covering clays or in the marcasite nodules encrusted in the clay may constitute a natural source of trace metals. With an objective of sanitary control, the limits of chemical contents regulating the quality of water destined for human consumption have been lowered by the European Framework Directive in the field of water policy (2000/60/EC). As a result, nickel limits have been reduced from 50 to 20 μg/l. The analyses, carried out on three water catchment fields in our area of study, were centred on variable parameters (Eh, O2(d), pH, Conductivity, T°), major elements (SO4, NO3) and metals (Fe, Ni, Mn, Co). The acquired data enabled us to identify from one hand, the conditions which are presented within the site, special thanks to the evolution of nitrate and iron contents and on the other hand, the natural origin (geological) of nickel for two of the three sites studied based essentially on the evaluation of the Nickel/Cobalt ratio. Thus, on the first site, the evolution of nickel content and nitrate content showed the influence of the phenomenon of denitrification on the re-mobilisation of the nickel. Whereas on the second site, a high variation of total iron content and oxygen dissolved in solution highlighted a particular phenomenon of oxidation of the pyrite through molecular oxygen. Finally, the correlation with the sulphates clearly showed behaviour of the nickel, once released, that was entirely dependent on the phenomenon of adsorption on the iron and manganese hydroxides.

  5. PowerPoint or chalk and talk: Perceptions of medical students versus dental students in a medical college in India

    PubMed Central

    Seth, Vikas; Upadhyaya, Prerna; Ahmad, Mushtaq; Moghe, Vijay

    2010-01-01

    Purpose To assess students’ perceptions of the impact of PowerPoint (PPT) presentations in lectures in comparison to the traditional chalk and talk method and lectures using transparencies and overhead projector (TOHP). The study analyzes the preferences for teaching aids of medical students versus dental students. Methods Second year medical and dental undergraduates were asked to fill in a nine-item questionnaire about their perceptions of the three lecture delivery methods. Following analysis of the questionnaire the students were interviewed further. The results were analyzed separately for medical and dental students to see if there was any difference in their perceptions. Results The majority of the medical students (65.33%) preferred PPT presentations, while 15.16% of students preferred the lectures using chalkboard, and 19.51% preferred TOHP for teaching (P < 0.001). Of the dental students: 41.84% preferred chalkboard, 31.21% preferred TOHP, and 25.85% students preferred PPT presentations in the lectures (P < 0.05). Some important comments of the students were also recorded on interview which could be valuable for the medical teachers. Conclusion: The medical students clearly preferred the use of PPT presentations while the dental students did not. The study does not bring out evidence based superiority of any lecture delivery method. It appears that in the hands of a trained teacher any teaching aid would be appropriate and effective. This highlights the need for formal training in teaching technologies to develop good presentation skills and thus motivate the students. PMID:23745057

  6. Large scale hot water migration systems around salt diapirs in the Danish Central Trough and their impact on diagenesis of chalk reservoirs

    NASA Astrophysics Data System (ADS)

    Jensenius, Jørgen; Munksgaard, Niels C.

    1989-01-01

    Fracture filling calcite from the piercement fields of East Rosa, Skjold, Rolf, North Arne, Nils and Vagn (directly underlain by salt diapirs) and the dome field Dan (overlying a deep seated salt structure) have been studied by fluorescence and cathodoluminiscence microscopy, fluid inclusion microthermometry and carbon and oxygen isotopes. The carbon and oxygen isotope compositions of the reservoir matrix chalk have also been measured. The temperature estimates obtained from fluid inclusion data suggest that the fracture filling calcite of the piercement fields precipitated during hot water flushing of the reservoirs. The flushing system only existed around the salt diapirs and was probably related to expulsion of overpressured fluid from the surrounding sediments. The thermal anomaly and the faults associated with the diapirs probably were important factors in focusing the ascending water. By combining fluid inclusion thermometry with O isotope data for the fracture filling calcites ranges of O isotopic values of the flushing water are deduced: in Skjold, Rolf, North Arne, Nils and Vagn: δ18O = - 1 to + 7%. SMOW, values typical of sedimentary porewater of sea water origin; in East Rosa: δ18O = - 4 and + 4%. SMOW, which combined with data on fluid inclusion salinities suggest that the flushing waters were responsible for substantial salt dissolution. Lower δ18O values with shallower depth of burial suggest that the porosity of chalk in the shallower fields was more severely reduced by calcite cementation during the flushing event than in the deeper fields. In the case of North Arne, Nils, Vagn and Dan, δ 13C values of the fracture filling calcites are similar to those of normal chalk (0.5 to 3.5%.). However, calcites from Rolf, Skjold and East Rosa are depleted by - 1.8, - 6.2 and - 16.7%., respectively. Only in East Rosa is the matrix chalk itself depleted in 13C (range: - 2.0 to + 0.7%.). The low δ 13C values are interpreted as the result of biodegration

  7. River Times.

    ERIC Educational Resources Information Center

    Auldridge, Teresa; And Others

    The James River is one of the most precious resources of Virginia. It was the site of the first permanent English settlement in the New World; the power of the water at the Fall Zone was a major factor in the development of Richmond; and the river served as a primary transportation route to the West via the Kanawha Canal. Both the water itself and…

  8. Area balance and strain in an extensional fault system: Strategies for improved oil recovery in fractured chalk, Gilbertown Field, southwestern Alabama. Annual report, March 1996--March 1997

    SciTech Connect

    Pashin, J.C.; Raymond, D.E.; Rindsberg, A.K.; Alabi, G.G.; Groshong, R.H.

    1997-08-01

    Gilbertown Field is the oldest oil field in Alabama and produces oil from chalk of the Upper Cretaceous Selma Group and from sandstone of the Eutaw Formation along the southern margin of the Gilbertown fault system. Most of the field has been in primary recovery since establishment, but production has declined to marginally economic levels. This investigation applies advanced geologic concepts designed to aid implementation of improved recovery programs. The Gilbertown fault system is detached at the base of Jurassic salt. The fault system began forming as a half graben and evolved in to a full graben by the Late Cretaceous. Conventional trapping mechanisms are effective in Eutaw sandstone, whereas oil in Selma chalk is trapped in faults and fault-related fractures. Burial modeling establishes that the subsidence history of the Gilbertown area is typical of extensional basins and includes a major component of sediment loading and compaction. Surface mapping and fracture analysis indicate that faults offset strata as young as Miocene and that joints may be related to regional uplift postdating fault movement. Preliminary balanced structural models of the Gilbertown fault system indicate that synsedimentary growth factors need to be incorporated into the basic equations of area balance to model strain and predict fractures in Selma and Eutaw reservoirs.

  9. Observations and Experiments on Carbonate Secretion in "Calcite Seas": Why Massive Chalk Deposits Formed in Late Cretaceous Time

    NASA Astrophysics Data System (ADS)

    Stanley, S. M.; Ries, J. B.; Hardie, L. A.

    2003-12-01

    It is now well-established that oscillations in the Mg/Ca ratio of seawater, driven by changes in spreading rates along mid-ocean ridges, have determined the mineralogy of nonskeletal marine carbonate precipitation throughout earth history. Low-Mg calcite has formed at Mg/Ca ratios < 2 ("calcite seas"), and aragonite has formed at ratios > 2 ("aragonite seas"). High-Mg calcite (mole % Mg > 4) has formed by itself at Mg/Ca ratios of 1-2, and along with aragonite at ratios above 2. We report here on experiments rooted in the paleontological observation that the carbonate mineralogy of major reef-building and sediment-producing organisms has tended to correspond to that of nonskeletal precipitates throughout Phanerozoic time. Earlier experiments showed that, with changes in the Mg/Ca ratio of ambient seawater, the Mg content of calcite in coralline algae varies like that of nonskeletal calcite precipitates. New experiments reveal that many kinds of calcite-secreting marine animals exhibit similar mineralogical trends, but with varying partition coefficients. Other experiments address the effects of seawater chemistry on productivity. One can predict that secretion of calcium carbonate will facilitate growth of algae because it releases carbon dioxide that can be used in photosynthesis. Indeed, we found that Halimeda, a major producer of aragonite sediment in present-day aragonite seas, grows less rapidly when living at ambient Mg/Ca ratios below the modern marine level of 5.2. Conversely, calcareous nannoplankton, which secrete calcite, become much more productive when ambient Mg/Ca ratios are below unity and associated concentrations of Ca are high. Such conditons characterized the extreme calcite seas of Late Cretaceous time, when nannoplankton formed massive chalk deposits throughout the world. Thus, we attribute the formation of these deposits, which gave the Cretaceous Period its name, to seawater chemistry. Calcareous nannoplankton in modern seas are adapted to

  10. Mapping of groundwater potential zones in Salem Chalk Hills, Tamil Nadu, India, using remote sensing and GIS techniques.

    PubMed

    Thilagavathi, N; Subramani, T; Suresh, M; Karunanidhi, D

    2015-04-01

    This study proposes to introduce the remote sensing and geographic information system (GIS) techniques in mapping the groundwater potential zones. Remote sensing and GIS techniques have been used to map the groundwater potential zones in Salem Chalk Hills, Tamil Nadu, India. Charnockites and fissile hornblende biotite gneiss are the major rock types in this region. Dunites and peridodites are the ultramafic rocks which cut across the foliation planes of the gneisses and are highly weathered. It comprises magnesite and chromite deposits which are excavated by five mining companies by adopting bench mining. The thickness of weathered and fracture zone varies from 2.2 to 50 m in gneissic formation and 5.8 to 55 m in charnockite. At the contacts of gneiss and charnockite, the thickness ranges from 9.0 to 90.8 m favoring good groundwater potential. The mine lease area is underlined by fractured and sheared hornblende biotite gneiss where groundwater potential is good. Water catchment tanks in this area of 5 km radius are small to moderate in size and are only seasonal. They remain dry during summer seasons. As perennial water resources are remote, the domestic and agricultural activities in this region depend mainly upon the groundwater resources. The mines are located in gently slope area, and accumulation of water is not observed except in mine pits even during the monsoon period. Therefore, it is essential to map the groundwater potential zones for proper management of the aquifer system. Satellite imageries were also used to extract lineaments, hydrogeomorphic landforms, drainage patterns, and land use, which are the major controlling factors for the occurrence of groundwater. Various thematic layers pertaining to groundwater existence such as geology, geomorphology, land use/land cover, lineament, lineament density, drainage, drainage density, slope, and soil were generated using GIS tools. By integrating all the above thematic layers based on the ranks and

  11. Phosphorus concentrations in the River Dun, the Kennet and Avon Canal and the River Kennet, southern England.

    PubMed

    Neal, Colin; House, W Alan; Jarvie, Helen P; Neal, Margaret; Hill, Linda; Wickham, Heather

    2005-05-15

    Variations in phosphorus (P) concentrations in an agriculturally impacted river draining a Chalk aquifer and an associated canal in the west of the Thames Basin, southern England are examined and linked to agricultural and sewage sources and within river/canal process controls. The study area comprises the River Dun, the adjacent River Kennet and the Kennet and Avon (K&A) Canal. Large seasonal variations are observed for soluble reactive phosphorus (SRP) and dissolved silicon (Si) with low concentrations in the spring and summer times when biological activity is high. The K&A Canal shows the largest SRP and Si concentration declines. This reflects high biological activity coupled with higher temperatures and higher water residence times. The extent of SRP removal is examined in relation to organic (uptake/release with phytoplankton growth/decay) and, to a lesser extent, inorganic (SRP coprecipitation with calcite) mechanisms. Boron (B) is used as a tracer of sewage sources. Agricultural inputs of both dissolved and particulate P (PP) can be important particularly under conditions where the catchment is wet and near surface/overland flow is important: sewage treatment works effluent and septic tank discharges to groundwater also probably provide a major component of the SRP occurring within the water column. The canal, and to a lesser extent the river, acts as sink for P in sewage effluent sources due to the high biological activity especially during the spring and summer. The aquifer probably acts as a major sink for agricultural and septic tank inputs of P. PMID:15907513

  12. The water quality of the River Dun and the Kennet and Avon Canal

    NASA Astrophysics Data System (ADS)

    Neal, Colin; House, W. Alan; Jarvie, Helen P.; Neal, Margaret; Hill, Linda; Wickham, Heather

    2006-10-01

    SummaryThe water quality of the River Dun and associated surface waters (a reservoir, two tributaries of the Dun, the Kennet and Avon Canal and the River Kennet to which the Dun drains) is described for a wide range of major, minor and trace elements. The water quality is determined by inputs from: (a) geologic sources (Ca, Sr concentrations and alkalinity) and (b) contaminant inputs from farming and sewage (Na, Cl, B, soluble reactive phosphorus and nitrate). As river water is mainly supplied from the Chalk aquifer and riparian areas, the water quality variation is damped, but there are occasional storms, where near surface/surface runoff delivers higher nutrient and suspended sediment concentrations, but dilutes determinands derived predominantly from geologic and point sources. River and canal water quality is also modified by in-stream biological processes in spring and summer, which remove nutrients (N, P and Si) and CO 2 from the water, bringing about precipitation of calcium carbonate and thus reductions in Ca concentrations and alkalinity. The biological effects are particularly marked for the Kennet and Avon Canal. The River Dun and Kennet and Avon Canal have been subject to episodic fish-kills and concern has been expressed about the role of event-based resuspension of bed sediments and mobilisation of dredged sediments on dissolved oxygen levels within the river. Therefore, fluvarium experiments on sediment-water interactions were undertaken to examine the potential effects of bed sediment disturbance on dissolved oxygen levels. The results of the fluvarium experiments demonstrate an ecologically-significant 30% reduction in dissolved oxygen levels following bed sediment disturbance. This reduction in DO concentrations was greater than expected from calculations using the measured sediment-oxygen demand. However, it is not clear that the bed sediments are mobilized to sufficient extent in the field for deleterious loss of DO. Indeed, much of the

  13. Implementation of agronomical and geochemical modules into a 3D groundwater code for assessing nitrate storage and transport through unconfined Chalk aquifer

    NASA Astrophysics Data System (ADS)

    Picot-Colbeaux, Géraldine; Devau, Nicolas; Thiéry, Dominique; Pettenati, Marie; Surdyk, Nicolas; Parmentier, Marc; Amraoui, Nadia; Crastes de Paulet, François; André, Laurent

    2016-04-01

    Chalk aquifer is the main water resource for domestic water supply in many parts in northern France. In same basin, groundwater is frequently affected by quality problems concerning nitrates. Often close to or above the drinking water standards, nitrate concentration in groundwater is mainly due to historical agriculture practices, combined with leakage and aquifer recharge through the vadose zone. The complexity of processes occurring into such an environment leads to take into account a lot of knowledge on agronomy, geochemistry and hydrogeology in order to understand, model and predict the spatiotemporal evolution of nitrate content and provide a decision support tool for the water producers and stakeholders. To succeed in this challenge, conceptual and numerical models representing accurately the Chalk aquifer specificity need to be developed. A multidisciplinary approach is developed to simulate storage and transport from the ground surface until groundwater. This involves a new agronomic module "NITRATE" (NItrogen TRansfer for Arable soil to groundwaTEr), a soil-crop model allowing to calculate nitrogen mass balance in arable soil, and the "PHREEQC" numerical code for geochemical calculations, both coupled with the 3D transient groundwater numerical code "MARTHE". Otherwise, new development achieved on MARTHE code allows the use of dual porosity and permeability calculations needed in the fissured Chalk aquifer context. This method concerning the integration of existing multi-disciplinary tools is a real challenge to reduce the number of parameters by selecting the relevant equations and simplifying the equations without altering the signal. The robustness and the validity of these numerical developments are tested step by step with several simulations constrained by climate forcing, land use and nitrogen inputs over several decades. In the first time, simulations are performed in a 1D vertical unsaturated soil column for representing experimental nitrates

  14. Digital Chalk Dust.

    ERIC Educational Resources Information Center

    Thomas, Glenn

    2000-01-01

    Tallahassee's Florida State University School is a prototype teaching-learning center that maximizes utilization of technology, time, and space and expands the teacher's role. The new learning scenarios will be unrestricted by buildings, organizational charts, or schedules. Principals must bridge industrial-world artifacts and the emerging…

  15. 33 CFR 162.90 - White River, Arkansas Post Canal, Arkansas River, and Verdigris River between Mississippi River...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., Arkansas River, and Verdigris River between Mississippi River, Ark., and Catoosa, Okla.; use... White River, Arkansas Post Canal, Arkansas River, and Verdigris River between Mississippi River, Ark... apply to: (1) Waterways. White River between Mississippi River and Arkansas Post Canal, Ark.;...

  16. Nutrient dynamics as indicators of karst processes: Comparison of the Chalk aquifer (Normandy, France) and the Edwards aquifer (Texas, U.S.A.)

    USGS Publications Warehouse

    Mahler, B.J.; Valdes, D.; Musgrove, M.; Massei, N.

    2008-01-01

    Karst aquifers display a range of geologic and geomorphic characteristics in a wide range of climatic and land-use settings; identification of transport dynamics representative of karst aquifers in general could help advance our understanding of these complex systems. To this end, nutrient, turbidity, and major ion dynamics in response to storms were compared at multiple sites in two karst aquifers with contrasting characteristics and settings: the Chalk aquifer (Eure Department, Normandy, France) and the Barton Springs segment of the Edwards Aquifer (Texas, U.S.A.). The Chalk aquifer is typified by high matrix porosity, thick surficial deposits (up to 30??m thick), and agricultural land use; the Barton Springs segment is typified by low matrix porosity, outcropping limestone, and urban land use. Following one to three storms, from 5 to 16 samples from springs and wells were analyzed for major ions, and specific conductance and turbidity were monitored continuously. Comparison of the chemographs indicated some generalized responses, including an increase in turbidity and potassium concentrations and a decrease in major ion and nitrate concentrations with infiltrating storm runoff. Factor analysis of major ions and turbidity revealed strikingly similar behavior of the chemical variables for the two aquifers: The first two factors, explaining more than 75% of the variability, illustrate that dynamics of most major ions (including nitrate) are opposed to those of turbidity and of potassium. The results demonstrate that potassium and nitrate are effective tracers of infiltrating storm runoff and resident ground water, respectively, and the similar results for these two highly contrasting aquifers suggest that the dynamics identified might be applicable to karst systems in general. ?? 2008 Elsevier B.V. All rights reserved.

  17. 27 CFR 9.66 - Russian River Valley.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Section 21 and 22 and 27 and 28 and in a straight line to the peak of Chalk Hill on the Healdsburg map. (33) Proceed west from the peak of Chalk Hill in a straight line to the point where Brooks Creek...

  18. 27 CFR 9.66 - Russian River Valley.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Section 21 and 22 and 27 and 28 and in a straight line to the peak of Chalk Hill on the Healdsburg map. (33) Proceed west from the peak of Chalk Hill in a straight line to the point where Brooks Creek...

  19. 27 CFR 9.66 - Russian River Valley.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Section 21 and 22 and 27 and 28 and in a straight line to the peak of Chalk Hill on the Healdsburg map. (33) Proceed west from the peak of Chalk Hill in a straight line to the point where Brooks Creek...

  20. YELLOWSTONE RIVER WATCH (YRW)

    EPA Science Inventory

    Yellowstone River Watch seeks to expand its monitoring and education efforts throughout the Yellowstone River Basin by actively recruiting and training new teacher members. Yellowstone River Watch also seeks to advance existing school programs by offering quality assurance/quali...

  1. The water quality of the River Thame in the Thames Basin of south/south-eastern England.

    PubMed

    Neal, Colin; Neal, Margaret; Hill, Linda; Wickham, Heather

    2006-05-01

    The water quality of the River Thame, a tributary of the River Thames in the Thames basin, is described in relation to point and diffuse contaminant inputs and runoff from permeable and impermeable bedrock geology with their own characteristic water quality. The data is examined to see if the market town of Aylesbury in the upper part of the catchment influences water quality. Previous studies highlighted the influence of Aylesbury sewage treatment works (STW) on soluble reactive phosphorus (SRP) concentrations in the river before and after phosphorus (P) stripping at the STW. Variations in water quality along the river are described and the study indicates that, apart from SRP, water quality determinants seem to be relatively unaffected by Aylesbury. The Thame water quality is compared with other catchment typologies and it is very similar to that of the main stem of the Thames even though the Thames is mainly Chalk groundwater fed. Differences in water quality largely link to the amount of STW effluent within the rivers and to the endmember compositions of the groundwater and near surface water sources. PMID:16253309

  2. Reply to comment on: Lawrence, J.A., Mortimore, R.N., Stone, K.J., and Busby, J.P., 2013. Sea saltwater weakening of chalk and the impact on cliff instability. Geomorphology 191, 14-22

    NASA Astrophysics Data System (ADS)

    Lawrence, James A.; Mortimore, Rory N.

    2015-02-01

    We are grateful to Dornbusch (2014) for the opportunity to clarify the role we propose for salt water weakening of the chalk and its potential importance as a mechanism contributing to cliff instability. Dornbusch's argument is based largely on a single comment "This work challenges the established view by identifying the role of salt from seawater in the degradation of porous rocks in coastal environments as a third and potentially the most important mechanism leading to chalk cliff collapse" (Lawrence et al., 2013: 15). This was not intended as a "conclusion" as suggested by Dornbusch (2014) but is rather a qualitative introductory statement highlighting the potential importance of the salt water weakening process in coastal cliff instability. The actual conclusions of the work are not challenged by Dornbusch (2014).

  3. Productivity, facies and stable-isotope records of OAE2 (Cenomanian - Turonian) in the NW European epicontinental sea: from the English Chalk to North Sea black shales

    NASA Astrophysics Data System (ADS)

    Jarvis, Ian; Olde, Kate; Trabucho-Alexandre, João; Gröcke, Darren

    2013-04-01

    The Late Cretaceous (100.5 - 66.0 Ma) provides perhaps the best example of how the Earth System may function under long-term extreme greenhouse conditions. Rapidly rising global temperatures indicate that we are heading 'back to the Cretaceous' within a few hundred years, so a better understanding of this time interval is essential. The beginning of the Late Cretaceous was characterized by a period of rapidly rising eustatic sea level, the Cenomanian transgression, which flooded continental margins and established large areas of new epicontinental sea that accumulated thick sequences of pelagic and hemipelagic carbonate (chalk). Highest global temperatures were reached during the early part of the Turonian Stage (93.9 - 89.8 Ma). This period of dramatic palaeoenvironmental change was accompanied by one the largest perturbations of the global carbon cycle in the Mesozoic: Oceanic Anoxic Event 2 (OAE2), which was characterized by a 500 kyr episode of oceanic anoxia, widespread black shale deposition, biotic turnover, and a large global positive carbon stable-isotope excursion (2 - 6 ‰ ∂13C) recorded in marine carbonates and both marine and terrestrial organic matter. The Cenomanian-Turonian boundary interval exposed at Eastbourne, southern England, has become established as a European reference section for OAE2. Here, and elsewhere in Europe, the base of the ∂13C excursion is coincident with a marked facies change from rhythmically bedded grey chalks and marls, to a >8 m thick package of dark greenish-grey marl - the Plenus Marl. The termination of OAE2 occurs 6 m above, in a package of pale-yellow-weathering nodular chalks with prominent marl seams. Sediments are organic lean (<0.2 wt% TOC) and bioturbated throughout, and although a case can be made for periodic oxygen depletion in bottom waters, there is no evidence here of marine surface- or bottom-water anoxia. The Plenus Marl displays a distinctive succession of 8 beds that can be correlated throughout

  4. High concentrations of trace metals in oysters from the Patuxent River, Maryland

    SciTech Connect

    Riedel, G.; Sanders, J.; Abbe, G.

    1995-12-31

    Oyster (Crassostrea virginica) populations from the Patuxent River have been analyzed for trace metals by a number of organizations over at least the past 19 years. During that period, high concentrations of Cu (200--500 {micro}g/g dry weight), Cd (3--7 {micro}g/g) and Ag (2--8 /{micro}g/g) have been found in oysters from the oyster bars furthest up river. In particular, Cd values in oysters from this region have had concentrations approaching or exceeding current FDA warning levels throughout the period. In previous studies it was suggested that a coal-burning power plant located in that region, Chalk Point Steam Electric Station, was responsible for the copper enrichment due to the corrosion of Cu/Ni alloy condenser tubes. However, a monthly survey of trace elements in the nearby oyster populations from 1986 to the present showed only a small decline in copper concentrations after the plant switched from Cu/Ni to Ti alloy condenser tubes in 1987. Other potential sources for trace metals in the region include municipal and industrial discharges, atmospheric deposition, and biocides (anti-fouling paint in particular). The very rapid rise in trace element concentrations in oysters with position up river, and the lack of such a response by another local bivalve, the hooked mussel (Ischadium recurvum), suggests that a physiological effect of low salinity stress on oysters may be in part responsible for the high concentrations of trace metals in oysters in this region.

  5. Overview of the Government of Canada Nuclear Legacy Liabilities Program - 13551

    SciTech Connect

    Metcalfe, D.; McCauley, D.; Miller, J.; Brooks, S.

    2013-07-01

    Nuclear legacy liabilities have resulted from more than 60 years of nuclear research and development carried out on behalf of Canada. The liabilities are located at Atomic Energy of Canada Limited's (AECL) Chalk River Laboratories in Ontario and Whiteshell Laboratories in Manitoba, as well as three shutdown prototype reactors in Ontario and Quebec that are being maintained in a safe storage state. Estimated at about $7.4 billion (current day dollars), these liabilities consist of disused nuclear facilities and associated infrastructure, a wide variety of buried and stored waste, and contaminated lands. In 2006, the Government of Canada adopted a long-term strategy to deal with the nuclear legacy liabilities and initiated a five-year, $520 million start-up phase, thereby creating the Nuclear Legacy Liabilities Program (NLLP). The Government of Canada renewed the NLLP in 2011 with a $439-million three-year second phase that ends March 31, 2014. The projects and activities carried out under the Program focus on infrastructure decommissioning, environmental restoration, improving the management of legacy radioactive waste, and advancing the long-term strategy. The NLLP is being implemented through a Memorandum of Understanding between Natural Resources Canada (NRCan) and AECL whereby NRCan is responsible for policy direction and oversight, including control of funding, and AECL is responsible for implementing the program of work and holding and administering all licences, facilities and lands. (authors)

  6. Impacts of groundwater abstraction on the trout fishery of the River Piddle, Dorset; and an approach to their alleviation

    NASA Astrophysics Data System (ADS)

    Strevens, A. P.

    1999-02-01

    The River Piddle, a small chalk stream in Dorset, supports a valuable fishery for brown trout. It is also heavily utilised for water abstraction, with a licensed maximum daily quantity of 197 Ml/d, of which 43·5% can be taken from the groundwater. The largest licensed groundwater uses (by licensed volume) are public water supplies (PWS), of which there are four within the Piddle catchment.Investigations into the impacts of the largest PWS abstraction, at Briantspuddle, on the brown trout population and fisheries of the River Piddle demonstrated a spatial correlation between a zone of reduced river flow and an area of low juvenile trout abundance, and a reduction in the period during which good quality trout fishing was available.Trout habitat was quantified by applying the Physical Habitat Simulation System (PHABSIM) in conjunction with a groundwater model. The resultant habitat duration curves and habitat time-series corresponding with historical and naturalised (zero abstraction) flow, indicated large habitat losses for juvenile trout.Using discharge habitat relationships a preferred flow regime for the river at Briantspuddle, designed to satisfy both ecological and recreational needs, was identified. This flow regime, which will be maintained by stream support, includes a survival flow for juvenile trout during the critical summer low flow period.

  7. Observations of debris flows at Chalk Cliffs, Colorado, USA: Part 2, changes in surface morphometry from terrestrial laser scanning in the summer of 2009

    USGS Publications Warehouse

    Staley, Dennis M.; Wasklewicz, Thad A.; Coe, Jeffrey A.; Kean, Jason W.; McCoy, Scott W.; Tucker, Greg E.

    2011-01-01

    High resolution topographic data that quantify changes in channel form caused by sequential debris flows in natural channels are rare at the reach scale. Terrestrial laser scanning (TLS) techniques are utilized to capture morphological changes brought about by a high-frequency of debris-flow events at Chalk Cliffs, Colorado. The purpose of this paper is to compare and contrast the topographic response of a natural channel to the documented debris-flow events. TLS survey data allowed for the generation of high-resolution (2-cm) digital terrain models (DTM) of the channel. A robust network of twelve permanent control points permitted repeat scanning sessions that provided multiple DTM to evaluate fine-scale topographic change associated with three debris-flow events. Difference surfaces from the DTM permit the interpretations of spatial variations in channel morphometry and net volume of material deposited and eroded within and between a series of channel reaches. Each channel reach experienced erosion, deposition, and both net volumetric gains and losses were measured. Analysis of potential relationships between erosion and deposition magnitudes yielded no strong correlations with measures of channel-reach morphometry, suggesting that channel reach-specific predictions of potential erosion or deposition locations or rates cannot be adequately derived from statistical analyses of pre-event channel-reach morphometry.

  8. Brazil: Xingu River

    Atmospheric Science Data Center

    2013-04-18

    ... title:  Fire and Deforestation near the Xingu River     View Larger Image Numerous fires occurred near the headwaters of the Xingu River and the Xingu Indigenous Peoples' Reserve in Mato Grosso, Brazil, during ...

  9. Measuring River Pollution

    ERIC Educational Resources Information Center

    Ayyavoo, Gabriel

    2004-01-01

    The Don River watershed is located within Canada's most highly urbanized area--metropolitan Toronto. Many residential and commercial uses, including alterations to the river's course with bridges, have had a significant impact on the Don's fauna and flora. Pollutants have degraded the river's water quality, a situation exacerbated by the…

  10. Mathematics. Rivers Curriculum Guide.

    ERIC Educational Resources Information Center

    Brueggeman, Gail; Clendenin, Donna

    The Rivers Project at Southern Illinois University began in February, 1990 as a pilot program involving eight high schools along the Mississippi and lower Illinois River. The Rivers Project network has grown through the training of teachers from across the United States and Canada. With scientific literacy as the ultimate goal, students collect…

  11. Rethinking the River.

    ERIC Educational Resources Information Center

    Tenenbaum, David

    1994-01-01

    Examines the ecological impacts of the Mississippi River flood of 1993 and the rethinking of river management practices that has resulted. Provides a map of the flood area which shows the occurrence of rare wildlife found in or near the region's rivers. (LZ)

  12. Flowing with Rivers

    ERIC Educational Resources Information Center

    Anderson, Heather

    2004-01-01

    This article describes a lesson in which students compare how artists have depicted rivers in paintings, using different styles, compositions, subject matter, colors, and techniques. They create a watercolor landscape that includes a river. Students can learn about rivers by studying them on site, through environmental study, and through works of…

  13. Amu Darya River

    Atmospheric Science Data Center

    2013-04-16

    article title:  Amu Darya River     View Larger Image This false-color image of the Amu Darya River was acquired by the Multi-angle Imaging SpectroRadiometer (MISR) in late ... highly vegetated areas to appear red. The Amu Darya river forms a wide delta in the western deserts of Uzbekistan and northeastern ...

  14. Analysing the spatial patterns of erosion scars using point process theory at the coastal chalk cliff of Mesnil-Val, Normandy, northern France

    NASA Astrophysics Data System (ADS)

    Rohmer, J.; Dewez, T.

    2015-02-01

    Over the last decade, many cliff erosion studies have focused on frequency-size statistics using inventories of sea cliff retreat sizes. By comparison, only a few paid attention to quantifying the spatial and temporal organisation of erosion scars over a cliff face. Yet, this spatial organisation carries essential information about the external processes and the environmental conditions that promote or initiate sea-cliff instabilities. In this article, we use summary statistics of spatial point process theory as a tool to examine the spatial and temporal pattern of a rockfall inventory recorded with repeated terrestrial laser scanning surveys at the chalk coastal cliff site of Mesnil-Val (Normandy, France). Results show that: (1) the spatial density of erosion scars is specifically conditioned alongshore by the distance to an engineered concrete groyne, with an exponential-like decreasing trend, and vertically focused both at wave breaker height and on strong lithological contrasts; (2) small erosion scars (10-3 to 10-2 m3) aggregate in clusters within a radius of 5 to 10 m, which suggests some sort of attraction or focused causative process, and disperse above this critical distance; (3) on the contrary, larger erosion scars (10-2 to 101 m3) tend to disperse above a radius of 1 to 5 m, possibly due to the spreading of successive failures across the cliff face; (4) large scars significantly occur albeit moderately, where previous large rockfalls have occurred during preceding winter; (5) this temporal trend is not apparent for small events. In conclusion, this study shows, with a worked example, how spatial point process summary statistics are a tool to test and quantify the significance of geomorphological observation organisation.

  15. Geomorphology of the Trinity River floodplain in Dallas County, Texas

    NASA Astrophysics Data System (ADS)

    Haugen, B. D.; Roig-Silva, C.; Manning, A. R.; Harrelson, D. W.; Olsen, R. S.; Dunbar, J. P.; Pearson, M. L.

    2010-12-01

    Data from more than 1,800 geologic borings and over 500 cone penetrometer tests (CPTs) were used to characterize the geomorphology of the Trinity River floodplain in the Dallas Metropolitan Area. Historical maps, aerial photographs and other published information were used to prepare a preliminary geomorphic map. Boring logs and CPT data were then used to refine the preliminary map, produce a series of two-dimensional (2D) and three-dimensional (3D) cross sections, and interpret the recent geologic history of the area. Geomorphologic interpretations - most importantly the locations of paleo-channel deposits of sands and gravels - were used to identify reaches of the levees managed by the United States Army Corps of Engineers (USACE) and the City of Dallas that may be at significant risk for under-seepage. Boring logs and CPT data collected atop the levees were used to assess through-seepage risks. Local bedrock is comprised of cretaceous-age Eagle Ford Shale and Austin Chalk. Depth to bedrock in the study area averaged 14.6 m (47.8 ft). The uppermost surface of bedrock has been deeply incised by a meandering river. Vertical relief between the shallowest bedrock sections and deepest portion of the incised paleo-channel is more than 15 m (50 ft). In places the incised paleo-channel is more than 0.8 km (0.5 mi) wide. These data confirm the presence of an erosional unconformity between local bedrock and overlying quaternary floodplain deposits. The observed erosional unconformity is attributed to a higher-energy fluvial environment that occurred as a result of a drop in base level. Recent floodplain deposits consist of interlobate point bar, channel and overbank sediments that are generally distributed in a fining-upward sequence. Buried channel dimensions vary widely, but are more than 250 m (820 ft) in some areas - much larger than the current channel. A semi-continuous basal layer of quaternary sands and gravels approximately 2 to 5 m (7 to 16 ft) thick exists in

  16. 76 FR 51887 - Safety Zone; Patuxent River, Patuxent River, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-19

    ...) entitled ``Safety Zone; Patuxent River, Patuxent River, MD'' in the Federal Register (76 FR 36447). We... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Patuxent River, Patuxent River, MD AGENCY... safety zone during the ``NAS Patuxent River Air Expo '11,'' which consists of aerial...

  17. Application of {sup 87}Sr/{sup 86}Sr, {delta}{sup 18}O and {delta}{sup 13}C isotopes to diagenesis correlation and connectivity of a fractured chalk reservoir, the Sidi El Kilani field, Tunisia

    SciTech Connect

    Mearns, E.W.; McBride, J.J.; Bramwell, M.

    1996-12-31

    Oil is produced primarily from open fracture porosity in Upper Cretaceous chalk in the Sidi El Kilani oil field. Strontium Stratigraphy analyses of primary, unaltered matrix chalk has confirmed a Campanian to Maastrichtian age and has allowed dating of the reservoir with a resolution of {+-}1 Ma. This has facilitated reservoir correlation and has indicated where section is missing in certain wells due to faulting. {sup 87}Sr/{sup 86}Sr, {delta}{sup 18}O and {delta}{sup 13}C analyses suggest an early generation of fracture fill calcite cement may have formed by redistribution of CaCO{sub 3} from underlying carbonate sequences at temperatures in the region 35-55{degrees}C. Calcite cemented fractures tend to be healed and are not productive. Strontium Isotope Residual Salt Analyses (SrRSA) conducted on core, provide information on the formation water chemistry and reservoir connectivity at the time of oil filling. These data suggest that the NW-SE trending fault system that bisects the field is sealed across much of the fault plane. The main oil pool lies SW of the fault. A later generation of dolomite and barite cements, associated with productive open fractures, have Sr-O-C composition consistent with precipitation from fluids circulating at the time of hydrocarbon charge at temperatures close to current reservoir conditions of 70-75{degrees}C. Predicting the distribution of dolomite cemented open fractures has thus helped guide the development strategy of the field.

  18. Application of [sup 87]Sr/[sup 86]Sr, [delta][sup 18]O and [delta][sup 13]C isotopes to diagenesis correlation and connectivity of a fractured chalk reservoir, the Sidi El Kilani field, Tunisia

    SciTech Connect

    Mearns, E.W.; McBride, J.J. ); Bramwell, M.

    1996-01-01

    Oil is produced primarily from open fracture porosity in Upper Cretaceous chalk in the Sidi El Kilani oil field. Strontium Stratigraphy analyses of primary, unaltered matrix chalk has confirmed a Campanian to Maastrichtian age and has allowed dating of the reservoir with a resolution of [+-]1 Ma. This has facilitated reservoir correlation and has indicated where section is missing in certain wells due to faulting. [sup 87]Sr/[sup 86]Sr, [delta][sup 18]O and [delta][sup 13]C analyses suggest an early generation of fracture fill calcite cement may have formed by redistribution of CaCO[sub 3] from underlying carbonate sequences at temperatures in the region 35-55[degrees]C. Calcite cemented fractures tend to be healed and are not productive. Strontium Isotope Residual Salt Analyses (SrRSA) conducted on core, provide information on the formation water chemistry and reservoir connectivity at the time of oil filling. These data suggest that the NW-SE trending fault system that bisects the field is sealed across much of the fault plane. The main oil pool lies SW of the fault. A later generation of dolomite and barite cements, associated with productive open fractures, have Sr-O-C composition consistent with precipitation from fluids circulating at the time of hydrocarbon charge at temperatures close to current reservoir conditions of 70-75[degrees]C. Predicting the distribution of dolomite cemented open fractures has thus helped guide the development strategy of the field.

  19. Reconsidering Himalayan river anticlines

    NASA Astrophysics Data System (ADS)

    Montgomery, David R.; Stolar, Drew B.

    2006-12-01

    The observation that major Himalayan rivers flow parallel to and down the axis of anticlines oriented transverse to the primary structural grain of the range has puzzled geomorphologists for decades. Although there is a general consensus that the courses of trans-Himalayan rivers predate the Himalayan orogeny, the close association of rivers and structural highs would not be expected to result from the superposition of rivers onto pre-existing structures. Moreover, in the past several decades structural studies have shown that the development of river anticlines represents the most recent phase of deformation in the range. It is proposed that Himalayan river anticlines are the consequence of focused rock uplift in response to significant differences between net erosion along major rivers and surrounding regions. This hypothesis is supported by large gradients in observed and predicted erosion rates across major Himalayan rivers and by results from an isostasy-driven model, which requires relatively low flexural rigidities to match the wavelength of Himalayan river anticlines. Whether the amplitude of these structures is due to isostasy or also reflects active crustal channeling is not well-constrained, but given the uncertainty in the flexural rigidity and in the local and far-field erosion rates, both possibilities remain viable explanations. Given the observed correlation between the Arun River anticline and local rainfall maxima, it is proposed that Himalayan river anticlines are the expression of a relatively fine-scale linkage between tectonics, erosion and climate superimposed on the broader and older canvas of the Himalayan orogeny. Finally, it is suggested that the development of river anticlines represents one example along a continuum of features arising from different degrees of erosion-structure coupling in active orogens.

  20. Rivers: Nature's Wondrous Waterways.

    ERIC Educational Resources Information Center

    Harrison, David L.

    Rivers play a vital role in the life of the planet. They provide water for wildlife, plant life, and people, and they help to fertilize fields where corn and other crops grow. But how were these rivers made? This children's book takes readers/students on a journey down a river from its source at the top of a mountain to its mouth where it meets…

  1. Simulated maintenance a virtual reality

    SciTech Connect

    Lirvall, P.

    1995-10-01

    The article describes potential applications of personal computer-based virtual reality software. The applications are being investigated by Atomic Energy of Canada Limited`s (AECL) Chalk River Laboratories for the Canadian deuterium-uranium (Candu) reactor. Objectives include: (1) reduction of outage duration and improved safety, (2) cost-effective and safe maintenance of equipment, (3) reduction of exposure times and identification of overexposure situations, (4) cost-effective training in a virtual control room simulator, (5) human factors evaluation of design interface, and (6) visualization of conceptual and detailed designs of critical nuclear field environments. A demonstration model of a typical reactor control room, the use of virtual reality in outage planning, and safety issues are outlined.

  2. Discussing spent nuclear fuel in high school classrooms: addressing public fears through early education

    SciTech Connect

    Winkel, S.; Sullivan, J.; Jones, S.; Sullivan, K.; Hyland, B.; Pencer, J.; Colton, A.

    2013-07-01

    The Inreach program combines the Deep River Science Academy (DRSA) 'learning through research' approach with state of the art communication technology to bring scientific research to high school classrooms. The Inreach program follows the DRSA teaching model where a university student tutor works on a research project with scientific staff at AECL's Chalk River Laboratories. Participating high school classes are located across Canada. The high school students learn about the ongoing research activities via weekly web conferences. In order to engage the students and encourage participation in the conferences, themed exercises linked to the research project are provided to the students. The DRSA's Inreach program uses a cost-effective internet technology to reach a wide audience, in an interactive setting, without anyone leaving their desks or offices. An example Inreach research project is presented here: an investigation of the potential of the Canadian supercritical water cooled reactor (SCWR) concept to burn transuranic elements (Np, Pu, Am, Cm) to reduce the impact of used nuclear fuel. During this project a university student worked with AECL (Atomic Energy of Canada Limited) researchers on technical aspects of the project, and high school students followed their progress and learned about the composition, hazards, and disposition options for used nuclear fuel. Previous projects included the effects of tritium on cellular viability and neutron diffraction measurement of residual stresses in automobile engines.

  3. Student-Designed River Study.

    ERIC Educational Resources Information Center

    Turkall, Sheila Florian

    1996-01-01

    Describes an integrated student-designed investigation in which students explore different aspects of the Chagrin River including the river ecosystem, velocity and average depth, river flooding, water quality, and economic and political factors. (JRH)

  4. River and Stream Pollution

    MedlinePlus

    ... Pollution Dirt Dirt is a big cause of pollution in our rivers and streams. Rain washes dirt into streams and rivers. Dirt can smother fish and other animals that live in the water. If plants can't get enough sunlight because ...

  5. Hudson River School

    ERIC Educational Resources Information Center

    McCloskey, Patrick J.

    2004-01-01

    In this article, the author features the "Clearwater," a full-size working replica of a 19th century Hudson River cargo sloop. The "Clearwater" has been serving New York state students as a link to both local history and the environment, helping them to learn lessons about the history of the Hudson River and the environment, thereby supplementing…

  6. Mississippi River. [Lesson Plan].

    ERIC Educational Resources Information Center

    Buchberg, Wendy

    Based on novels and books about the Mississippi River, this lesson plan presents activities designed to help students understand that the Mississippi River has made its mark on America's geography, commerce, and literature; and that booktalks provide a summary, explains what kind of reader the book will appeal to, and may also contain a oral…

  7. Alaska Glaciers and Rivers

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image on October 7, 2007, showing the Alaska Mountains of south-central Alaska already coated with snow. Purple shadows hang in the lee of the peaks, giving the snow-clad land a crumpled appearance. White gives way to brown on the right side of the image where the mountains yield to the lower-elevation Susitna River Valley. The river itself cuts a silver, winding path through deep green forests and brown wetlands and tundra. Extending from the river valley, are smaller rivers that originated in the Alaska Mountains. The source of these rivers is evident in the image. Smooth white tongues of ice extend into the river valleys, the remnants of the glaciers that carved the valleys into the land. Most of the water flowing into the Gulf of Alaska from the Susitna River comes from these mountain glaciers. Glacier melt also feeds glacier lakes, only one of which is large enough to be visible in this image. Immediately left of the Kahiltna River, the aquamarine waters of Chelatna Lake stand out starkly against the brown and white landscape.

  8. One river, many stories

    EPA Science Inventory

    Interactive exhibition elements include opportunity to add stories, drawings, and place names to maps of the river; record & share your vision for the river with public television. The Duluth Art Institute will present the kick-off event for the month-long media focus around ...

  9. The Illinois Rivers Project.

    ERIC Educational Resources Information Center

    Williams, Robert A.; And Others

    The Illinois Rivers Project was developed as an integrated, multidimensional science/technology/society pilot project designed to introduce water quality dimensions into Illinois high schools. The project involved high school science, social science, and English teachers in an integrated study of their local river and community. Science students…

  10. 2. View of Tombigbee River Bridge facing southeast. River flow ...

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

    2. View of Tombigbee River Bridge facing southeast. River flow is to left. South Pony span in background is not clearly shown. North pony span is shown on the left of main span. - Tombigbee River Bridge, Spanning Tombigbee River at State Highway 182, Columbus, Lowndes County, MS

  11. 36 CFR 7.89 - New River Gorge National River.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... River Gorge National River? (i) In addition to the applicable provisions in 36 CFR part 4, all... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false New River Gorge National River. 7.89 Section 7.89 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF...

  12. 33 CFR 117.734 - Navesink River (Swimming River).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Navesink River (Swimming River... BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.734 Navesink River (Swimming River). The Oceanic Bridge, mile 4.5, shall open on signal; except that, from December 1...

  13. 33 CFR 117.734 - Navesink River (Swimming River).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Navesink River (Swimming River... BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.734 Navesink River (Swimming River). The Oceanic Bridge, mile 4.5, shall open on signal; except that, from December 1...

  14. 33 CFR 117.734 - Navesink River (Swimming River).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Navesink River (Swimming River... BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.734 Navesink River (Swimming River). The Oceanic Bridge, mile 4.5, shall open on signal; except that, from December 1...

  15. 33 CFR 117.734 - Navesink River (Swimming River).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Navesink River (Swimming River... BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.734 Navesink River (Swimming River). The Oceanic Bridge, mile 4.5, shall open on signal; except that, from December 1...

  16. 33 CFR 117.734 - Navesink River (Swimming River).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Navesink River (Swimming River... BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.734 Navesink River (Swimming River). The Oceanic Bridge, mile 4.5, shall open on signal; except that, from December 1...

  17. 36 CFR 7.89 - New River Gorge National River.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false New River Gorge National River. 7.89 Section 7.89 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.89 New River Gorge National River....

  18. Uranium in river water

    SciTech Connect

    Palmer, M.R. ); Edmond, J.M. )

    1993-10-01

    The concentration of dissolved uranium has been determined in over 250 river waters from the Orinoco, Amazon, and Ganges basins. Uranium concentrations are largely determined by dissolution of limestones, although weathering of black shales represents an important additional source in some basins. In shield terrains the level of dissolved U is transport limited. Data from the Amazon indicate that floodplains do not represent a significant source of U in river waters. In addition, the authors have determined dissolved U levels in forty rivers from around the world and coupled these data with previous measurements to obtain an estimate for the global flux of dissolved U to the oceans. The average concentration of U in river waters is 1.3 nmol/kg, but this value is biased by very high levels observed in the Ganges-Brahmaputra and Yellow rivers. When these river systems are excluded from the budget, the global average falls to 0.78 nmol/kg. The global riverine U flux lies in the range of 3-6 [times] 10[sup 7] mol/yr. The major uncertainty that restricts the accuracy of this estimate (and that of all other dissolved riverine fluxes) is the difficulty in obtaining representative samples from rivers which show large seasonal and annual variations in runoff and dissolved load.

  19. Modeling river delta formation.

    PubMed

    Seybold, Hansjörg; Andrade, José S; Herrmann, Hans J

    2007-10-23

    A model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/erosion law. Different delta types are reproduced by using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore, our model is capable of simulating the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi River. PMID:17940031

  20. Nile River Delta, Egypt

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The Nile River Delta of Egypt (30.0N, 31.0E) irrigated by the Nile River and its many distributaries, is some of the richest farm land in the world and home to some 45 million people, over half of Egypt's population. The capital city of Cairo is at the apex of the delta. Just across the river from Cairo can be seen the ancient three big pyramids and sphinx at Giza and the Suez Canal is just to the right of the delta.

  1. Modeling river delta formation

    PubMed Central

    Seybold, Hansjörg; Andrade, José S.; Herrmann, Hans J.

    2007-01-01

    A model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/erosion law. Different delta types are reproduced by using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore, our model is capable of simulating the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi River. PMID:17940031

  2. BELLE FOURCHE RIVER WATERSHED ASSESSMENT

    EPA Science Inventory

    The Belle Fourche River is a natural stream that drains portions of Butte, Lawrence, and Meade Counties in South Dakota and flows to the Cheyenne River in Meade County. The river receives runoff from agricultural operations and both the river and its tributaries have experienced...

  3. Area balance and strain in an extensional fault system: Strategies for improved oil recovery in fractured chalk, Gilbertown Field, southwestern Alabama -- Year 2. Annual report, March 1997--March 1998

    SciTech Connect

    Pashin, J.C.; Raymond, D.E.; Rindsberg, A.K.; Alabi, G.G.; Carroll, R.E.

    1998-09-01

    Gilbertown Field is the oldest oil field in Alabama and has produced oil from fractured chalk of the Cretaceous Selma Group and glauconitic sandstone of the Eutaw Formation. Nearly all of Gilbertown Field is still in primary recovery, although waterflooding has been attempted locally. The objective of this project is to analyze the geologic structure and burial history of Mesozoic and Tertiary strata in Gilbertown Field and adjacent areas in order to suggest ways in which oil recovery can be improved. Indeed, the decline of oil production to marginally economic levels in recent years has made this type of analysis timely and practical. Key technical advancements being sought include understanding the relationship of requisite strain to production in Gilbertown reservoirs, incorporation of synsedimentary growth factors into models of area balance, quantification of the relationship between requisite strain and bed curvature, determination of the timing of hydrocarbon generation, and identification of the avenues and mechanisms of fluid transport.

  4. River basin management

    SciTech Connect

    Newsome, D.H.; Edwards, A.M.C.

    1984-01-01

    The quality of water is of paramount importance in the management of water resources - including marine waters. A quantitative knowledge of water quality and the factors governing it is required to formulate and implement strategies requiring an inter-disciplinary approach. The overall purpose of this conference was to bring together the latest work on water quality aspects of river basin management. These proceedings are structured on the basis of five themes: problems in international river basins; the contribution of river systems to estuarial and marine pollution; the setting of standards; monitoring; and practical water quality management including use of mathematical models. They are followed by papers from the workshop on advances in the application of mathematical modelling to water quality management, which represent some of the current thinking on the problems and concepts of river basin management.

  5. Santa Cruz River Options

    EPA Science Inventory

    This presentation summarizes qualitative research insights gained during development of a nonmarket valuation survey for changes to the Santa Cruz River in Southern Arizona. Qualitative research provides an important avenue for understanding how the public interprets valuation s...

  6. Colorado River Delta

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Colorado River ends its 2330 km journey in the Gulf of Mexico in Baja California. The heavy use of the river as an irrigation source for the Imperial Valley has dessicated the lower course of the river in Mexico such that it no longer consistently reaches the sea. Prior to the mid 20th century, the Colorado River Delta provided a rich estuarine marshland that is now essentially desiccated, but nonetheless is an important ecological resource.

    The image was acquired May 29, 2006, covers an area of 44.3 x 57.5 km, and is located at 32.1 degrees north latitude, 115.1 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.

  7. River Meander Studies

    NASA Technical Reports Server (NTRS)

    Lingenfelter, R. E.

    1972-01-01

    The meander patterns of the Feather and Colorado rivers were studied in an attempt to correlate pattern changes and flood probability. Attempts were also made to correlate stream meander power spectrum and stream discharge frequency distribution.

  8. Mackenzie River Delta, Canada

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Mackenzie River in the Northwest Territories, Canada, with its headstreams the Peace and Finley, is the longest river in North America at 4241 km, and drains an area of 1,805,000 square km. The large marshy delta provides habitat for migrating Snow Geese, Tundra Swans, Brant, and other waterfowl. The estuary is a calving area for Beluga whales. The Mackenzie (previously the Disappointment River) was named after Alexander Mackenzie who travelled the river while trying to reach the Pacific in 1789.

    The image was acquired on August 4, 2005, covers an area of 55.8 x 55.8 km, and is located at 68.6 degrees north latitude, 134.7 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.

  9. Laminar laboratory rivers

    NASA Astrophysics Data System (ADS)

    Seizilles, Grégoire; Devauchelle, Olivier; Lajeunesse, Éric; Métivier, François

    2014-05-01

    A viscous fluid flowing over fine plastic grains spontaneously channelizes into a few centimeters-wide river. After reaching its equilibrium shape, this stable laboratory flume is able to carry a steady load of sediments, like many alluvial rivers. When the sediment discharge vanishes, the river size, shape and slope fit the threshold theory proposed by Glover and Florey (1951), which assumes that the Shields parameter is critical on the channel bed. As the sediment discharge is increased, the river widens and flattens. Surprisingly, the aspect ratio of its cross section depends on the sediment discharge only, regardless of the water discharge. We propose a theoretical interpretation of these findings based on the balance between gravity, which pulls particles towards the center of the channel, and the diffusion of bedload particles, which pushes them away from areas of intense bedload.

  10. THE GREAT RIVERS NEWSLETTER

    EPA Science Inventory

    The Great Rivers Newsletter is a periodic publication of the EPA's Mid-Continent Ecology Division. It is designed to disseminate timely information about the EMAP-GRE project among EPA investigators; state, federal, and tribal collaborators; and other stakeholders.

  11. Hood River Production Master Plan.

    SciTech Connect

    O'Toole, Patty

    1991-07-01

    The Northwest Power Planning Council's 1987 Columbia River Fish and Wildlife Program authorizes the development of artificial production facilities to raise chinook salmon and steelhead for enhancement in the Hood, Umatilla, Walla Walla, Grande Ronde and Imnaha rivers and elsewhere. On February 26, 1991 the Council agreed to disaggregate Hood River from the Northeast Oregon Hatchery Project, and instead, link the Hood River Master Plan (now the Hood River Production Plan) to the Pelton Ladder Project (Pelton Ladder Master Plan 1991).

  12. Connecticut River Hydrologic Observatory

    NASA Astrophysics Data System (ADS)

    Ballestero, T. P.

    2004-12-01

    The Connecticut River basin possesses some characteristics that make it unique for studying hydrologic issues that transcend scale. The watershed was first dramatically altered through natural processes (glaciation) and then heavily impacted by human stresses (dams, deforestation, acid precipitation/deposition), only to exhibit recent decades of return to a more natural state (reforestation, land conservation, stream restoration, pollution abatement, and dam removal). The watershed is sufficiently north to be classified as a cold region. More specifically to hydrology, the watershed exhibits the spectrum of flooding problems: ice dams, convective storms, hurricanes, rain on melting snow, and low pressure systems. The 28,000 square kilometer Connecticut River Watershed covers one third of the states of New Hampshire, Vermont, Massachusetts, and Connecticut. The >640-km long rivers' headwaters start on the Canadian border at the Fourth Connecticut Lake, and flows southward to discharge in Long Island sound. The lower 100 km of river are tidally influenced. The Connecticut River is responsible for 70 % of the freshwater inflow to Long Island Sound. The Connecticut River is a sixth order stream that exhibits a dendritic pattern in an elongated scheme. This setting therefore affords many first and second order streams in almost parallel fashion, flowing west or east towards the central Connecticut River spine. There are 38 major tributaries to the mainstem Connecticut River, and 26 of these tributaries drain greater than 250 square kilometers. There is in excess of 30,000 km of perennially flowing stream length in the watershed. For more information, see: http://www.unh.edu/erg/connho/

  13. The rivers of civilization

    NASA Astrophysics Data System (ADS)

    Macklin, Mark G.; Lewin, John

    2015-04-01

    The hydromorphic regimes that underpinned Old World river-based civilizations are reviewed in light of recent research. Notable Holocene climatic changes varied from region to region, whilst the dynamics of floodplain environments were equally diverse, with river channel changes significantly affecting human settlement. There were longer-term trends in Holocene hydroclimate and multi-centennial length 'flood-rich' and 'flood-poor' episodes. These impacted on five identified flooding and settlement scenarios: (i) alluvial fans and aprons; (ii) laterally mobile rivers; (iii) rivers with well-developed levees and flood basins; (iv) river systems characterised by avulsions and floodouts; and (v) large river-fed wetlands. This gave a range of changes that were either more or less regular or incremental from year-to-year (and thus potentially manageable) or catastrophic. The latter might be sudden during a flood event or a few seasons (acute), or over longer periods extending over many decades or even centuries (chronic). The geomorphic and environmental impacts of these events on riparian societies were very often irreversible. Contrasts are made between allogenic and autogenic mechanism for imposing environmental stress on riverine communities and a distinction is made between channel avulsion and contraction responses. Floods, droughts and river channel changes can precondition as well as trigger environmental crises and societal collapse. The Nile system currently offers the best set of independently dated Holocene fluvial and archaeological records, and the contrasted effects of changing hydromorphological regimes on floodwater farming are examined. The persistence of civilizations depended essentially on the societies that maintained them, but they were also understandably resilient in some environments (Pharaonic Egypt in the Egyptian Nile), appear to have had more limited windows of opportunity in others (the Kerma Kingdom in the Nubian Nile), or required

  14. Synthetic River Valleys

    NASA Astrophysics Data System (ADS)

    Brown, R.; Pasternack, G. B.

    2011-12-01

    The description of fluvial form has evolved from anecdotal descriptions to artistic renderings to 2D plots of cross section or longitudinal profiles and more recently 3D digital models. Synthetic river valleys, artificial 3D topographic models of river topography, have a plethora of potential applications in fluvial geomorphology, and the earth sciences in general, as well as in computer science and ecology. Synthetic river channels have existed implicitly since approximately the 1970s and can be simulated from a variety of approaches spanning the artistic and numerical. An objective method of synthesizing 3D stream topography based on reach scale attributes would be valuable for sizing 3D flumes in the physical and numerical realms, as initial input topography for morphodynamic models, stream restoration design, historical reconstruction, and mechanistic testing of interactions of channel geometric elements. Quite simply - simulation of synthetic channel geometry of prescribed conditions can allow systematic evaluation of the dominant relationships between river flow and geometry. A new model, the control curve method, is presented that uses hierarchically scaled parametric curves in over-lapping 2D planes to create synthetic river valleys. The approach is able to simulate 3D stream geometry from paired 2D descriptions and can allow experimental insight into form-process relationships in addition to visualizing past measurements of channel form that are limited to two dimension descriptions. Results are presented that illustrate the models ability to simulate fluvial topography representative of real world rivers as well as how channel geometric elements can be adjusted. The testing of synthetic river valleys would open up a wealth of knowledge as to why some 3D attributes of river channels are more prevalent than others as well as bridging the gap between the 2D descriptions that have dominated fluvial geomorphology the past century and modern, more complete, 3D

  15. Post-irradiation examination of prototype Al-64 wt% U{sub 3}Si{sub 2} fuel rods from NRU

    SciTech Connect

    Sears, D.F.; Primeau, M.F.; Buchanan, C.; Rose, D.

    1997-08-01

    Three prototype fuel rods containing Al-64 wt% U{sub 3}Si{sub 2} (3.15 gU/cm{sup 3}) have been irradiated to their design burnup in the NRU reactor without incident. The fuel was fabricated using production-scale equipment and processes previously developed for Al-U{sub 3}Si fuel fabrication at Chalk River Laboratories, and special equipment developed for U{sub 3}Si{sub 2} powder production and handling. The rods were irradiated in NRU up to 87 at% U-235 burnup under typical driver fuel conditions; i.e., nominal coolant inlet temperature 37{degrees}C, inlet pressure 654 kPa, mass flow 12.4 L/s, and element linear power ratings up to 73 kW/m. Post-irradiation examinations showed that the fuel elements survived the irradiation without defects. Fuel core diametral increases and volumetric swelling were significantly lower than that of Al-61 wt% U{sub 3}Si fuel irradiated under similar conditions. This irradiation demonstrated that the fabrication techniques are adequate for full-scale fuel manufacture, and qualified the fuel for use in AECL`s research reactors.

  16. Waste Management Improvement Initiatives at Atomic Energy of Canada Limited - 13091

    SciTech Connect

    Chan, Nicholas; Adams, Lynne; Wong, Pierre

    2013-07-01

    Atomic Energy of Canada Limited's (AECL) Chalk River Laboratories (CRL) has been in operation for over 60 years. Radioactive, mixed, hazardous and non-hazardous wastes have been and continue to be generated at CRL as a result of research and development, radioisotope production, reactor operation and facility decommissioning activities. AECL has implemented several improvement initiatives at CRL to simplify the interface between waste generators and waste receivers: - Introduction of trained Waste Officers representing their facilities or activities at CRL; - Establishment of a Waste Management Customer Support Service as a Single-Point of Contact to provide guidance to waste generators for all waste management processes; and - Implementation of a streamlined approach for waste identification with emphasis on early identification of waste types and potential disposition paths. As a result of implementing these improvement initiatives, improvements in waste management and waste transfer efficiencies have been realized at CRL. These included: 1) waste generators contacting the Customer Support Service for information or guidance instead of various waste receivers; 2) more clear and consistent guidance provided to waste generators for waste management through the Customer Support Service; 3) more consistent and correct waste information provided to waste receivers through Waste Officers, resulting in reduced time and resources required for waste management (i.e., overall cost); 4) improved waste minimization and segregation approaches, as identified by in-house Waste Officers; and 5) enhanced communication between waste generators and waste management groups. (authors)

  17. Multi-purpose hydrogen isotopes separation plant design

    SciTech Connect

    Boniface, H.A.; Gnanapragasam, N.V.; Ryland, D.K.; Suppiah, S.; Castillo, I.

    2015-03-15

    There is a potential interest at AECL's Chalk River Laboratories to remove tritium from moderately tritiated light water and to reclaim tritiated, downgraded heavy water. With only a few limitations, a single CECE (Combined Electrolysis and Catalytic Exchange) process configuration can be designed to remove tritium from heavy water or light water and upgrade heavy water. Such a design would have some restrictions on the nature of the feed-stock and tritium product, but could produce essentially tritium-free light or heavy water that is chemically pure. The extracted tritium is produced as a small quantity of tritiated heavy water. The overall plant capacity is fixed by the total amount of electrolysis and volume of catalyst. In this proposal, with 60 kA of electrolysis a throughput of 15 kg*h{sup -1} light water for detritiation, about 4 kg*h{sup -1} of heavy water for detritiation and about 27 kg*h{sup -1} of 98% heavy water for upgrading can be processed. Such a plant requires about 1,000 liters of AECL isotope exchange catalyst. The general design features and details of this multi-purpose CECE process are described in this paper, based on some practical choices of design criteria. In addition, we outline the small differences that must be accommodated and some compromises that must be made to make the plant capable of such flexible operation. (authors)

  18. The Nile River

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This image of the northern portion of the Nile River was captured by MISR's nadir camera on January 30, 2001 (Terra orbit 5956). The Nile is the longest river in the world, extending for about 6700 kilometers from its headwaters in the highlands of eastern Africa. At the apex of the fertile Nile River Delta is the Egyptian capital city of Cairo. To the west are the Great Pyramids of Giza. North of here the Nile branches into two distributaries, the Rosetta to the west and the Damietta to the east. Also visible in this image is the Suez Canal, a shipping waterway connecting Port Said on the Mediterranean Sea with the Gulf of Suez. The Gulf is an arm of the Red Sea, and is located on the righthand side of the picture. Image credit: NASA/GSFC/LaRC/JPL, MISR Team.

  19. Alaskan river environmental acoustics

    NASA Astrophysics Data System (ADS)

    Dahl, Peter H.; Pfisterer, Carl; Geiger, Harold J.

    2005-04-01

    Sonars are used by the Alaska Department of Fish and Game (ADF&G) to obtain daily and hourly estimates of at least four species of migratory salmon during their seasonal migration which lasts from June to beginning of September. Suspended sediments associated with a river's sediment load is an important issue for ADF&G's sonar operations. Acoustically, the suspended sediments are a source of both volume reverberation and excess attenuation beyond that expected in fresh water. Each can impact daily protocols for fish enumeration via sonar. In this talk, results from an environmental acoustic study conducted in the Kenai River (June 1999) using 420 kHz and 200 kHz side looking sonars, and in the Yukon River (July 2001) using a 120 kHz side looking sonar, are discussed. Estimates of the volume scattering coefficient and attenuation are related to total suspended sediments. The relative impact of bubble scattering and sediment scattering is also discussed.

  20. Rivers of Evidence

    PubMed Central

    Adams, Clive E

    2013-01-01

    There has been too much of a one-way flow drift down a river of evidence. Researchers from rich countries have produced the primary evidence which they proceed to summarise within reviews. These summaries have directed care worldwide. However, things are changing and the river of evidence can flow in the other direction. The care of women with eclampsia has been changed or refined throughout the world because of a large low and middle income country trial. The global care of people with heart disease has been greatly modified by studies originating in China. The care of people who are acutely aggressive because of psychosis has to be reconsidered in the light of the evidence coming from Brazil and India. Healthcare is an issue everywhere and evaluation of care is not the premise of any one culture—the evidence—river must run both ways. PMID:24596880

  1. 33 CFR 207.380 - Red Lake River, Minn.; logging regulations for portion of river above Thief River Falls.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Red Lake River, Minn.; logging... Red Lake River, Minn.; logging regulations for portion of river above Thief River Falls. (a) Parties wishing to run logs on Red Lake River must provide storage booms near the head of the river to take...

  2. 33 CFR 207.380 - Red Lake River, Minn.; logging regulations for portion of river above Thief River Falls.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Red Lake River, Minn.; logging... Red Lake River, Minn.; logging regulations for portion of river above Thief River Falls. (a) Parties wishing to run logs on Red Lake River must provide storage booms near the head of the river to take...

  3. 76 FR 36447 - Safety Zone; Patuxent River, Patuxent River, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-22

    ..., 2008, issue of the Federal Register (73 FR 3316). Public meeting We do not now plan to hold a public... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Patuxent River, Patuxent River, MD AGENCY... a temporary safety zone during the ``NAS Patuxent River Air Expo '11'', which consists of...

  4. Regional river sulfur runoff

    SciTech Connect

    Husar, R.B.; Husar, J.D.

    1985-01-20

    The water and sulfur runoff data for 54 large river basins were assembled, covering 65% of the nondesert land area of the world. The sulfur concentration ranges from 0.5 mg S/L for the West African rivers Niger and Volta to 100 mg S/L in the Colorado River; the world average is 3.2 mg S/L. The concentrations in central and eastern Europe as well as central and eastern North America exceed 8 mg S/L. The sulfur runoff density is also highest in the river basins over these industrialized regions, exceeding 2 g S/m/sup 2//yr. However, high sulfur runoff density in excess of 3 g S/m/sup 2//yr is also measured over the Pacific islands New Zealand and New Guinea and the archipelagos of Indonesia and the Philippines. The natural background sulfur runoff was estimated by assuming that South America, Africa, Australia, and the Pacific Islands are unperturbed by man and that the average river sulfur concentration is in the range 1--3 mg S/L. Taking these background concentration values, the man-induced sulfur runoff for Europe ranges between 2 and 8 times the natural flow, and over North America, man's contribution ranges between 1 and 5 times the natural runoff. The global sulfur flow from nondesert land to the oceans and the Caspian Sea is estimated as 131 Tg S/yr, of which 46--85 Tg S/yr is attributed to natural causes. The regional river sulfur runoff pattern discussed in this paper does not have enough spatial resolution to be directly applicable to studies of the environmental effects of man-induced sulfur flows. However, it points to the continental-size regions where those perturbations are most evident and to the magnitude of the perturbations as expressed in units of the natural flows.

  5. Regional river sulfur runoff

    NASA Astrophysics Data System (ADS)

    Husar, Rudolf B.; Husar, Janja Djukic

    1985-01-01

    The water and sulfur runoff data for 54 large river basins were assembled, covering 65% of the nondesert land area of the world. The sulfur concentration ranges from 0.5 mg S/L for the West African rivers Niger and Volta to 100 mg S/L in the Colorado River; the world average is 3.2 mg S/L. The concentrations in central and eastern Europe as well as central and eastern North America exceed 8 mg S/L. The sulfur runoff density is also highest in the river basins over these industrialized regions, exceeding 2 g S/m2/yr. However, high sulfur runoff density in excess of 3 g S/m2/yr is also measured over the Pacific islands New Zealand and New Guinea and the archipelagos of Indonesia and the Philippines. The natural background sulfur runoff was estimated by assuming that South America, Africa, Australia, and the Pacific Islands are unperturbed by man and that the average river sulfur concentration is in the range 1-3 mg S/L. Taking these background concentration values, the man-induced sulfur runoff for Europe ranges between 2 and 8 times the natural flow, and over North America, man's contribution ranges between 1 and 5 times the natural runoff. The global sulfur flow from nondesert land to the oceans and the Caspian Sea is estimated as 131 Tg S/yr, of which 46-85 Tg S/yr is attributed to natural causes. The regional river sulfur runoff pattern discussed in this paper does not have enough spatial resolution to be directly applicable to studies of the environmental effects of man-induced sulfur flows. However, it points to the continental-size regions where those perturbations are most evident and to the magnitude of the perturbations as expressed in units of the natural flows.

  6. Osmium in the rivers

    SciTech Connect

    Sharma, M. |; Wasserburg, G.J.

    1997-12-01

    There is a large uncertainty in our understanding of the behavior of osmium during weathering and transport into deep oceans and the osmium budget of the oceans. The problem stems chiefly from the lack of osmium data on the dissolved load in the rivers and in the estuaries. In this study, the concentration and isotopic composition of osmium have been determined in three North American rivers (the Mississippi, the Columbia, and the Connecticut) and one river draining central Europe and flowing into the Baltic Sea (the Vistula). Osmium concentration in the Mississippi and the Vistula is about 45 femto mol kg{sup -1}; it is about 14 and 15 femto mol kg{sup -1} for the Connecticut and the Columbia, respectively. The {sup 187}Os/{sup 186}Os ratios estimated for the Mississippi and the Vistula are 10.4 and 10.7, respectively. For the Connecticut and the Columbia {sup 187}Os/{sup 186}Os = 8.8 and 14.4, respectively. Of all the rivers examined, the Mississippi is by far the largest, supplying {approximately}1.6% of the total annual world river flow. Its osmium isotopic composition is identical to the upper Mississippi valley loesses indicating (1) congruent dissolution of the bedrock and (2) little or no impact of anthropogenic sources on the osmium isotopic composition of the dissolved load. The latter observation indicates that the upper limit of the anthropogenic input in the dissolved osmium load of the Mississippi outflow is about 250 g yr{sup -1}. While the osmium concentration of the Vistula is high the isotopic composition does not appear to have been affected by substantial pollution. The river data can be used to put limits on the mean residence time of osmium in the oceans ({bar {tau}}{sub Os}) and on the osmium budget of the oceans. 17 refs., 1 fig., 1 tab.

  7. River Pollution: Part I.

    ERIC Educational Resources Information Center

    Openshaw, Peter

    1983-01-01

    Describes a unit on river pollution and analytical methods to use in assessing temperature, pH, flow, calcium, chloride, dissolved oxygen, biochemical oxygen demand, dissolved nitrogen, detergents, heavy metals, sewage pollution, conductivity, and sediment cores. Suggests tests to be carried out and discusses significance of results. (JM)

  8. Savannah River Site Robotics

    ScienceCinema

    None

    2012-06-14

    Meet Sandmantis and Frankie, two advanced robotic devices that are key to cleanup at Savannah River Site. Sandmantis cleans hard, residual waste off huge underground storage tanks. Frankie is equipped with unique satellite capabilities and sensing abilties that can determine what chemicals still reside in the tanks in a cost effective manner.

  9. Ecological River Basin Management.

    ERIC Educational Resources Information Center

    Smith, Anthony Wayne

    Addressing the Seventh American Water Resources Conference, Washington, D. C., October, 1971, Anthony Wayne Smith, President, National Parks and Conservation Association, presents an expose on how rivers should be managed by methods which restores and preserve the natural life balances of the localities and regions through which they flow. The…

  10. Nissitissit River Investigation.

    ERIC Educational Resources Information Center

    Sweatman, Jon

    Prepared for the student participant, this manual guides a day's exploration of the Nissitissit River. The unit, one of several developed in conjunction with Project Exploration, has the broad goals of promoting--through experiential learning in a variety of environments outside the classroom--the student's self-confidence and ability to work…

  11. Colwater fish in rivers

    EPA Science Inventory

    A standard sampling protocol to assess the fish assemblages and abundances in large, coldwater rivers is most accurate and precise if consistent gears and levels of effort are used at each site. This requires thorough crew training, quality control audits, and replicate sampling...

  12. Discover the Nile River

    ERIC Educational Resources Information Center

    Project WET Foundation, 2009

    2009-01-01

    Bordering on the Fantastic. As the longest river on earth, the Nile passes through 10 countries. Presented through a wide range of activities and a winning array of games, it's also unsurpassed at taking young minds into exploring the world of water, as well as natural and man made wonders.

  13. River on Trial

    ERIC Educational Resources Information Center

    Carney, Thomas R.

    1972-01-01

    Presents controversy over damming of Wyoming's Upper Green River to supply water to the arid basins of eastern Wyoming. Possibilities of wildlife destruction, flooding of valley lands, and opposition to the construction of the Kendall Dam itself are enumerated together with legislative action to date. (BL)

  14. The River Rock School.

    ERIC Educational Resources Information Center

    Gereaux, Teresa Thomas

    1999-01-01

    In the early 1920s, the small Appalachian community of Damascus, Virginia, used private subscriptions and volunteer labor to build a 15-classroom school made of rocks from a nearby river and chestnut wood from nearby forests. The school building's history, uses for various community activities, and current condition are described. (SV)

  15. The Nation's Rivers

    ERIC Educational Resources Information Center

    Wolman, M. Gordon

    1971-01-01

    Illustrates difficulties in measuring long term changes in water temperature and content of dissolved oxygen, inorganic ions, radiation, pesticides, and trash and debris by reference to selected U. S. river systems. Concludes that observations to detect polluters may not provide data for assessing trends and trend reversals. (AL)

  16. Savannah River Site Robotics

    SciTech Connect

    2010-01-01

    Meet Sandmantis and Frankie, two advanced robotic devices that are key to cleanup at Savannah River Site. Sandmantis cleans hard, residual waste off huge underground storage tanks. Frankie is equipped with unique satellite capabilities and sensing abilties that can determine what chemicals still reside in the tanks in a cost effective manner.

  17. Long-term channel adjustment and geomorphic feature creation by vegetation in a lowland, low energy river

    NASA Astrophysics Data System (ADS)

    Grabowski, Robert; Gurnell, Angela

    2016-04-01

    Physical habitat restoration is increasingly being used to improve the ecological status of rivers. This is particularly true for lowland streams which are perceived to lack sufficient energy to create new features or to flush out fine sediment derived from agricultural and urban sources. However, this study has found that even in low-energy, base-flow dominated chalk streams, physical habitat improvement can happen naturally without direct human intervention. Furthermore this positive change is achieved by components of the river that are often regarded as management problems: in-stream macrophytes (i.e. weed), riparian trees, woody debris, and most importantly fine sediment. This project investigated the long-term changes in channel planform for the River Frome (Dorset, UK) over the last 120 years and the role of aquatic and riparian vegetation in driving this change. Agricultural census data, historical maps, recent aerial images and field observations were analysed within a process-based, hierarchical framework for hydromorphological assessment, developed in the EU FP7 REFORM project, to investigate the source and timing of fine sediment production in the catchment, to quantify the reach-scale geomorphic response, and to identify vegetation-related bedforms that could be responsible for the adjustment. The analysis reveals that the channel has narrowed and become more sinuous in the last 50-60 years. The timing of this planform adjustment correlates with substantial changes in land use and agricultural practices (post-World War II) that are known to increase soil erosion and sediment connectivity. The field observations and recent aerial images suggest that the increased delivery of fine sediment to the channel has been translated into geomorphic adjustment and diversification though the interactions between vegetation, water flow and sediment. Emergent aquatic macrophytes are retaining fine sediment, leading to the development of submerged shelves that aggrade

  18. Variation of dissolved organic carbon transported by two Chinese rivers: The Changjiang River and Yellow River.

    PubMed

    Liu, Dong; Pan, Delu; Bai, Yan; He, Xianqiang; Wang, Difeng; Zhang, Lin

    2015-11-15

    Real-time monitoring of riverine dissolved organic carbon (DOC) and the associated controlling factors is essential to coastal ocean management. This study was the first to simulate the monthly DOC concentrations at the Datong Hydrometric Station for the Changjiang River and at the Lijin Hydrometric Station for the Yellow River from 2000 to 2013 using a multilayer back-propagation neural network (MBPNN), along with basin remote-sensing products and river in situ data. The average absolute error between the modeled values and in situ values was 9.98% for the Changjiang River and 10.84% for the Yellow River. As an effect of water dilution, the variations of DOC concentrations in the two rivers were significantly negatively affected by discharge, with lower values reported during the wet season. Moreover, vegetation growth status and agricultural activities, represented by the gross primary product (GPP) and cropland area percent (CropPer) in the river basin, respectively, also significantly affected the DOC concentration in the Changjiang River, but not the Yellow River. The monthly riverine DOC flux was calculated using modeled DOC concentrations. In particular, the riverine DOC fluxes were affected by discharge, with 71.06% being reported for the Changjiang River and 90.71% for the Yellow River. Over the past decade, both DOC concentration and flux in the two rivers have not shown significant changes. PMID:26404069

  19. 3. ENVIRONMENT, FROM SOUTH, SHOWING RIVER ROAD RIDGE CARRYING CASSELMAN ...

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

    3. ENVIRONMENT, FROM SOUTH, SHOWING RIVER ROAD RIDGE CARRYING CASSELMAN RIVER ROAD OVER CASSELMAN RIVER - River Road Bridge, Crossing Casselman River on Casselman River Road, Grantsville, Garrett County, MD

  20. Hood River Passive House

    SciTech Connect

    Hales, D.

    2013-03-01

    The Hood River Passive Project was developed by Root Design Build of Hood River Oregon using the Passive House Planning Package (PHPP) to meet all of the requirements for certification under the European Passive House standards. The Passive House design approach has been gaining momentum among residential designers for custom homes and BEopt modeling indicates that these designs may actually exceed the goal of the U.S. Department of Energy's (DOE) Building America program to reduce home energy use by 30%-50% (compared to 2009 energy codes for new homes). This report documents the short term test results of the Shift House and compares the results of PHPP and BEopt modeling of the project.

  1. Chesapeake Bay, Potomac River

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The nation's capital lies astride the Potomac River (38.5N, 77.5W) at the head of the Potomac Estuary. Baltimore, MD, also in the scene, is connected to Washington by the Baltimore-Washington Parkway. The suburbs of both cities tend to cluster around the Washington and Baltimore Beltways. Most of the countryside in the eastern two-thirds of this scene is either heavily forested or is in farming, dairy operations or poultry production.

  2. Onilahy River, Madagascar

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Near the southern tip of Madagascar, the Onilahy River (23.5S, 44E) drains a near barren landscape, the result of rapid deforestation for quick profits from the lumber industry with no regard to the environmental impact. At the turn of the century, the island was a lush tropical paradise with about 90 percent of the surface forested. Now, at the close of the century, only about 10 percent of the forests remain in inaccessible rugged terrain.

  3. River networks as biodiversity hotlines.

    PubMed

    Décamps, Henri

    2011-05-01

    For several years, measures to insure healthy river functions and to protect biodiversity have focused on management at the scale of drainage basins. Indeed, rivers bear witness to the health of their drainage basins, which justifies integrated basin management. However, this vision should not mask two other aspects of the protection of aquatic and riparian biodiversity as well as services provided by rivers. First, although largely depending on the ecological properties of the surrounding terrestrial environment, rivers are ecological systems by themselves, characterized by their linearity: they are organized in connected networks, complex and ever changing, open to the sea. Second, the structure and functions of river networks respond to manipulations of their hydrology, and are particularly vulnerable to climatic variations. Whatever the scale considered, river networks represent "hotlines" for sharing water between ecological and societal systems, as well as for preserving both systems in the face of global change. River hotlines are characterized by spatial as well as temporal legacies: every human impact to a river network may be transmitted far downstream from its point of origin, and may produce effects only after a more or less prolonged latency period. Here, I review some of the current issues of river ecology in light of the linear character of river networks. PMID:21640951

  4. 77 FR 30589 - SteelRiver Infrastructure Partners LP, SteelRiver Infrastructure Associates LLC, SteelRiver...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-23

    ... Surface Transportation Board SteelRiver Infrastructure Partners LP, SteelRiver Infrastructure Associates LLC, SteelRiver Infrastructure Fund North America LP, and Patriot Funding LLC--Control Exemption--Patriot Rail Corp., et al. SteelRiver Infrastructure Partners LP (SRIP LP), SteelRiver...

  5. 50 CFR 226.205 - Critical habitat for Snake River sockeye salmon, Snake River fall chinook salmon, and Snake River...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of the USGS publication and maps may be... salmon, Snake River fall chinook salmon, and Snake River spring/summer chinook salmon. 226.205 Section... Snake River sockeye salmon, Snake River fall chinook salmon, and Snake River spring/summer...

  6. 50 CFR 226.205 - Critical habitat for Snake River sockeye salmon, Snake River fall chinook salmon, and Snake River...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of the USGS publication and maps may be... salmon, Snake River fall chinook salmon, and Snake River spring/summer chinook salmon. 226.205 Section... Snake River sockeye salmon, Snake River fall chinook salmon, and Snake River spring/summer...

  7. Flooding on Elbe River

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Heavy rains in Central Europe over the past few weeks have led to some of the worst flooding the region has witnessed in more than a century. The floods have killed more than 100 people in Germany, Russia, Austria, Hungary, and the Czech Republic and have led to as much as $20 billion in damage. This false-color image of the Elbe River and its tributaries was taken on August 20, 2002, by the Moderate Resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite. The floodwaters that inundated Dresden, Germany, earlier this week have moved north. As can be seen, the river resembles a fairly large lake in the center of the image just south of the town of Wittenberg. Flooding was also bad further downriver in the towns of Maqgdeburge and Hitzacker. Roughly 20,000 people were evacuated from their homes in northern Germany. Fifty thousand troops, border police, and technical assistance workers were called in to combat the floods along with 100,000 volunteers. The floodwaters are not expected to badly affect Hamburg, which sits on the mouth of the river on the North Sea. Credit:Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  8. Flooding along Danube River

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Heavy rains in Central and Eastern Europe over the past few weeks have led to some of the worst flooding the region has witnessed in over a century. The floods have killed more than 100 people in Germany, Russia, Austria, Hungary and the Czech Republic and have led to as much as $20 billion in damage. This false-color image of the Danube River and its tributaries was taken on August 19, 2002, by the Moderate Resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite. Budapest, the capital of Hungary, sits just south of the large bend in the river at the top of the image. Here the water reached levels not seen since 1965. Fortunately, the riverbanks are lined with 33-foot retainer walls throughout the city, so it did not face the same fate as Dresden or Prague along the Elbe River. But as one can see, the floodwaters hit many rural areas farther south. As last reported, the water was receding along the Danube. Credit: Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC.

  9. Tsunami Impacts in River Environments

    NASA Astrophysics Data System (ADS)

    Tolkova, E.; Tanaka, H.; Roh, M.

    2014-12-01

    The 2010 Chilean and the 2011 Tohoku tsunami events demonstrated the tsunami's ability to penetrate much farther along rivers than the ground inundation. At the same time, while tsunami impacts to the coastal areas have been subject to countless studies, little is known about tsunami propagation in rivers. Here we examine the field data and conduct numerical simulations to gain better understanding of the tsunami impacts in rivers.The evidence which motivated our study is comprised of water level measurements of the aforementioned tsunamis in multiple rivers in Japan, and the 2011 Tohoku and some other tsunamis in the Columbia River in the US. When the available tsunami observations in these very different rivers are brought together, they display remarkably similar patterns not observed on the open coast. Two phenomena were discovered in the field data. First, the phase of the river tide determines the tsunami penetration distance in a very specific way common to all rivers. Tsunami wave progressively disappears on receding tide, whereas high tide greatly facilitates the tsunami intrusion, as seen in the Figure. Second, a strong near-field tsunami causes substantial and prolonged water accumulation in lower river reaches. As the 2011 tsunami intruded rivers in Japan, the water level along rivers rose 1-2 m and stayed high for many hours, with the maximum rise occurring several km from the river mouth. The rise in the water level at some upstream gaging stations even exceeded the tsunami amplitude there.Using the numerical experiments, we attempt to identify the physics behind these effects. We will demonstrate that the nonlinear interactions among the flow components (tsunami, tide, and riverine flow) are an essential condition governing wave dynamics in tidal rivers. Understanding these interactions might explain some previous surprising observations of waves in river environments. Figure: Measurements of the 2010/02/27 tsunami along Naruse and Yoshida rivers

  10. Fluoride in UK rivers.

    PubMed

    Neal, Colin; Neal, Margaret; Davies, Helen; Smith, Jennifer

    2003-10-01

    Fluoride concentrations in eastern UK rivers (the Humber, Tweed, Wear, Great Ouse and Thames) are described based on information collected within the Land-Ocean Interaction Study (LOIS) and by the Environment Agency (EA) of England and Wales. The results show varied fluoride concentrations across the region, with a range from <0.01 to >10 mg l(-1); and mean, median and range in mean concentrations of 0.30, 0.21 and 0.05-3.38 mg l(-1) (excluding one outlier point), respectively. Within the main rivers and tributaries, the mean fluoride concentration varied from approximately 0.5 to over 2 mg l(-1) and the highest values occurred within the Don basin (Don, Dearne and Rother) and parts of the Trent basin (upper Tame and mid-upper Derbyshire Derwent) in highly industrialised and urbanised areas (Sheffield and Rotherham in the Don basin; Birmingham and Derby on the Trent). For localised inputs to the rivers, fluoride concentrations were slightly higher, and considerably higher in one outlier case. Correspondingly, the other rivers examined typically had mean fluoride concentrations between approximately 0.2 and 0.5 mg l(-1), but fluoride concentrations were lower in the headwater areas. As there is much less information on fluoride levels in upland areas, extensive data collected as part of an acid waters survey are used to show that fluoride concentrations are generally less than 0.1 mg l(-1) for the upland UK. The data are summarised in terms of both fluoride concentrations and flux, and the values are cross-referenced to other determinands collected within LOIS. The high positive correlation with boron and negative correlation with flow show the importance of point source (sewage) inputs of fluoride, while strong positive correlations between fluoride and barium indicate the relative importance of vein mineralisation in the bedrock in supplying fluoride to the waters of the Yorkshire Ouse and its tributaries. There seems to be some process that limits the fluoride

  11. 33 CFR 125.06 - Western rivers.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Western rivers. 125.06 Section... VESSELS § 125.06 Western rivers. The term western rivers as used in the regulations in this subchapter shall include only the Red River of the North, the Mississippi River and its tributaries above the...

  12. 33 CFR 125.06 - Western rivers.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Western rivers. 125.06 Section... VESSELS § 125.06 Western rivers. The term western rivers as used in the regulations in this subchapter shall include only the Red River of the North, the Mississippi River and its tributaries above the...

  13. 33 CFR 125.06 - Western rivers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Western rivers. 125.06 Section... VESSELS § 125.06 Western rivers. The term western rivers as used in the regulations in this subchapter shall include only the Red River of the North, the Mississippi River and its tributaries above the...

  14. 33 CFR 125.06 - Western rivers.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Western rivers. 125.06 Section... VESSELS § 125.06 Western rivers. The term western rivers as used in the regulations in this subchapter shall include only the Red River of the North, the Mississippi River and its tributaries above the...

  15. Rehabilitating China's largest inland river.

    PubMed

    Li, Yiqing; Chen, Yaning; Zhang, Yaoqi; Xia, Yang

    2009-06-01

    Wetlands are particularly important for conserving China's biodiversity but riparian wetlands in the Tarim River basin in western China have been reduced by 46% during the last 3 decades. The world's largest habitat for Populus euphratica, which is in the Tarim River basin, significantly shrank. To protect and restore the deteriorated ecosystems along the Tarim River and its associated wetlands, China's government initiated a multimillion dollar river restoration project to release water from upper dams to the dried-up lower reaches of the Tarim River starting in 2000. We monitored the responses of groundwater and vegetation to water recharge in the lower reaches of the river from 2000 to 2006 by establishing nine 1000-m-long transects perpendicular to the river at intervals of 20-45 km along the 320-km river course below the Daxihaizi Reservoir, the source of water conveyance, to Lake Taitema, the terminus of the Tarim River. Water recharges from the Daxihaizi Reservoir to the lower reaches of the Tarim River significantly increased groundwater levels and vegetation coverage at all monitoring sites along the river. The mean canopy size of the endangered plant species P. euphratica doubled after 6 years of water recharge. Some rare migrating birds returned to rest on the restored wetlands in summer along the lower reaches of the Tarim River. The biggest challenge facing decision makers, however, is to balance water allocation and water rights between agricultural and natural ecosystems in a sustainable way. A large number of inhabitants in the Tarim Basin depend on these limited water resources for a living. At the same time, the endangered ecosystems need to be protected. Given the ecological, socioeconomic, and sociopolitical realities in the Tarim Basin, adaptive water policies and strategies are needed for water allocation in these areas of limited water resources. PMID:22748091

  16. Organic Compounds in Truckee River Water Used for Public Supply near Reno, Nevada, 2002-05

    USGS Publications Warehouse

    Thomas, Karen A.

    2009-01-01

    Organic compounds studied in this U.S. Geological Survey (USGS) assessment generally are man-made, including, in part, pesticides, solvents, gasoline hydrocarbons, personal care and domestic-use products, and refrigerants and propellants. Of 258 compounds measured, 28 were detected in at least 1 source water sample collected approximately monthly during 2002-05 at the intake of the Chalk Bluff Treatment Plant, on the Truckee River upstream of Reno, Nevada. The diversity of compounds detected indicate various sources and uses (including wastewater discharge, industrial, agricultural, domestic, and others) and different pathways (including point sources from treated wastewater outfalls upstream of the sampling location, overland runoff, and groundwater discharge) to drinking-water supply intakes. Three compounds were detected in more than 20 percent of the source-water intake samples at low concentrations (less than 0.1 microgram per liter), including caffeine, p-cresol (a wood preservative), and toluene (a gasoline hydrocarbon). Sixteen of the 28 compounds detected in source water also were detected in finished water (after treatment, but prior to distribution; 2004-05). Additionally, two disinfection by-products not detected in source water, bromodichloromethane and dibromochloromethane, were detected in all finished water samples. Two detected compounds, cholesterol and 3-beta-coprostanol, are among five naturally occurring biochemicals analyzed in this study. Concentrations for all detected compounds in source and finished water generally were less than 0.1 microgram per liter and always less than human-health benchmarks, which are available for about one-half of the compounds. Seven compounds (toluene, chloroform, bromodichloromethane, dibromodichloromethane, bisphenol A, cholesterol, and 3-beta-coprostanol) were measured at concentrations greater than 0.1 microgram per liter. On the basis of this screening-level assessment, adverse effects to human health are

  17. Trinity river basin, Texas

    USGS Publications Warehouse

    Ulery, Randy L.; Van Metre, Peter C.; Crossfield, Allison S.

    1993-01-01

    In 1991 the Trinity River Basin National Water-Quality Assessment (NAWQA) will include assessments of surface-water and ground-water quality. Initial efforts have focused on identifying water-quality issues in the basin and on the environmental factors underlying those issues. Physical characteristics described include climate, geology, soils, vegetation, physiography, and hydrology. Cultural characteristics discussed include population distribution, land use and land cover, agricultural practices, water use, an reservoir operations. Major water-quality categories are identified and some of the implications of the environmental factors for water quality are presented.

  18. Methane Emission from Tropical Rivers

    NASA Astrophysics Data System (ADS)

    Sawakuchi, H. O.; Rasera, M. F. F. L.; Krusche, A. V.; Ballester, M. V. R.

    2012-04-01

    Inland water is already known as an important source of methane to atmosphere. Methane is produced in anaerobic environments usually find in lakes and floodplain bottom sediment. It is the main reason that almost all information regarding methane flux come from this environments. However, while floodplain dries during low water season reducing methanogenesis, rivers keep the capacity to emit methane throughout the year. Here we present preliminary results of CH4 flux measurements done in 6 large tropical rivers within the Amazon basin. We measured 17 areas using floating chamber during dry (low water) season, between September and November of 2011, in Amazon river mainstem, Araguaia, Xingu, Tapajós, Madeira, and Negro Rivers. Measured fluxes of all rivers ranged from 59.3 to 2974.4 mmol m-2 yr-1. Geomorphologic structure of channels is one important factor that contributes to this high heterogeneity due to development of low flow velocity depositional settings allowing formation of anoxic zones in rivers. Hydraulic and sediment barriers in the confluence of river channels promote the generation of natural dams which function as a trap for the suspension load favoring the deposition of organic rich muds. This kind of environment is very different from common river channels and has a stronger potential of methane emission. Average values of our flux measurements for this two river environments show that depositional areas can have much higher fluxes than the main channel, 1089.6 and 163.1 mmol m-2 yr-1, respectively. Hence, CH4 flux from these depositional zones is similar to some tropical floodplain lakes and reservoirs. Although the low flux from channel, the area covered by water is very large resulting in a significant contribution to the regional methane emission to the atmosphere. Moreover, mapping the area of these depositional river zones will give us a better idea of the magnitude of methane flux from tropical rivers.

  19. River Capture in Disequilibrium Landscapes

    NASA Astrophysics Data System (ADS)

    McCoy, S. W.; Perron, J.; Willett, S.; Goren, L.

    2013-12-01

    The process of river piracy or river capture has long drawn interest as a potential mechanism by which drainage basins large and small evolve towards an equilibrium state. River capture transfers both drainage area and drainage lines from one river basin to another, which can cause large, abrupt shifts in network topology, drainage divide positions, and river incision rates. Despite numerous case studies in which river capture has been proposed to have occurred, there is no general, mechanistic framework for understanding the controls on river capture, nor are there quantitative criteria for determining if capture has occurred. Here we use new metrics of landscape disequilibrium to first identify landscapes in which drainage reorganization is occurring. These metrics are based on a balance between an integral of the contributing drainage area and elevation. In an analysis of rivers in the Eastern United States we find that many rivers are in a state of disequilibrium and are experiencing recent or ongoing area exchange between basins. In these disequilibrium basins we find widespread evidence for network rearrangement via river capture at multiple scales. We then conduct numerical experiments with a 2-D landscape evolution model to explore the conditions in which area exchange among drainage basins is likely to occur as discrete capture events as opposed to continuous divide migration. These experiments indicate that: (1) capture activity increases with the degree of disequilibrium induced by persistent spatial gradients in tectonic forcing or by temporal changes in climate or tectonic forcing; (2) capture activity is strongly controlled by the initial planform drainage network geometry; and (3) capture activity scales with the fluvial incision rate constant in the river power erosion law.

  20. Application of {sup 87}Sr/{sup 86}Sr, {delta}{sup 18}O and {delta}{sup 13}C Isotopes to diagenesis, correlation and connectivity of a fractured chalk reservoir, the Sidi El Kilani Field Tunisia

    SciTech Connect

    Mearns, E.W.; Mcbride, J.J.; Bramwell, M.

    1995-08-01

    Strontium Stratigraphy Analysis of the primary matrix chalk of the Abiod Formation reservoir in the Sidi El Kilani Field indicate a Campanian to Maastrichtian age (Upper Cretaceous). A resolution of {+-}1Ma has been achieved and results suggest that there are no major stratigraphic breaks in the studied sequences. Sr-O-C isotope data from early fracture-filling calcite cements suggest they may have formed by the redistribution of CaCO{sub 3} from underlying carbonate sequences and may have precipitated at temperatures in the region of 35-55{degrees}C. The {sup 87}Sr/{sup 86}Sr isotope ratios of formation waters determined by residual salt analysis (SrRSA) suggest that the chemical evolution of waters during reservoir filling was controlled by the influx of basinal waters as opposed to in situ water-rock interaction. Late, fracture-filling dolomite and barite cements have Sr-O-C isotope characteristics consistent with precipitation from these migrating basinal fluids at temperatures similar to current reservoir conditions (70-75{degrees}C). Sr RSA results suggest that the reservoir section in two of the wells may have been in direct lateral communication at the time of oil emplacement. These wells however are separated by a strike-slip fault. The SrRSA results therefore suggest that the fault is a partial barrier which has restricted pressure equilibration in the relatively short timescale of oil production, but which may have allowed homogenization of Sr isotope ratios in formation water.

  1. 33 CFR 117.865 - Clatskanie River.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... after each day's authorized commercial fishing period established by the Columbia River Compact (Washington State Department of Fisheries and the Fish Commission of Oregon) for the Columbia River...

  2. 33 CFR 117.865 - Clatskanie River.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... after each day's authorized commercial fishing period established by the Columbia River Compact (Washington State Department of Fisheries and the Fish Commission of Oregon) for the Columbia River...

  3. 33 CFR 117.865 - Clatskanie River.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... after each day's authorized commercial fishing period established by the Columbia River Compact (Washington State Department of Fisheries and the Fish Commission of Oregon) for the Columbia River...

  4. 33 CFR 117.865 - Clatskanie River.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... after each day's authorized commercial fishing period established by the Columbia River Compact (Washington State Department of Fisheries and the Fish Commission of Oregon) for the Columbia River...

  5. Always a River. Activity Booklet.

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Cincinnati, OH.

    This activity booklet was designed to accompany a floating barge exhibition entitled "Always a River" that brought together the experiences of the past, the opportunities of the present, and the hopes of the future afforded by the Ohio River. The interdisciplinary activities in this booklet aim at enriching the lives of young people and making…

  6. INDIAN RIVER LAGOON IR, 2004

    EPA Science Inventory

    Since the Indian River Lagoon Program's last implementation review, the NEP through the local sponsorship of the St. Johns River Water Management District, has seen a three-fold increase in implementation funding from $6.7 million in 1999, to $21.3 million in FY 2003. This fundin...

  7. Treasure Along the Parker River.

    ERIC Educational Resources Information Center

    Fitzpatrick, Ann-Marie; And Others

    Designed so that 100 to 125 heterogeneously grouped 7th and 8th grade students and a team of 5 core teachers might experience and discover the natural and historical "treasure" in the Parker River area of Massachusetts, this interdisciplinary unit centers on a hike to Parker River (6.7 miles) and visits to a cemetery, a monument, and Old Town…

  8. Flooding on Russia's Lena River

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Nearly every year in the late spring, ice blocks the flow of water at the mouth of the Lena River in northeastern Russia and gives rise to floods across the Siberian plains. This year's floods can be seen in this image taken on June 2, 2002, by the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the Terra satellite. The river runs down the left side of the image, and its delta is shrouded in ice (red) at the top of the image. Normally, the river would resemble a thin black line in MODIS imagery. The river, which is Russia's longest, flows 2,641 miles (4,250 kilometers) south to north through Siberia and into the Laptev Sea. In the winter, the river becomes nearly frozen. In the spring, however, water upstream thaws earlier than water at the mouth of the river. As the southern end of the river begins to melt, blocks of ice travel downstream to the still frozen delta, pile up, and often obstruct the flow of water. Flooding doesn't always occur on the same parts of the river. The floods hit further south last year. If the flooding grows severe enough, explosive charges are typically used to break up the ice jams. In these false-color images land areas are a dull, light green or tan, and water is black. Clouds appear pink, and ice comes across as bright red. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  9. Hood River Passive House

    SciTech Connect

    Hales, D.

    2014-01-01

    The Hood River Passive Project was developed by Root Design Build of Hood River Oregon using the Passive House Planning Package (PHPP) to meet all of the requirements for certification under the European Passive House standards. The Passive House design approach has been gaining momentum among residential designers for custom homes and BEopt modeling indicates that these designs may actually exceed the goal of the U.S. Department of Energy's (DOE) Building America program to reduce home energy use by 30%-50% (compared to 2009 energy codes for new homes). This report documents the short term test results of the Shift House and compares the results of PHPP and BEopt modeling of the project. The design includes high R-Value assemblies, extremely tight construction, high performance doors and windows, solar thermal DHW, heat recovery ventilation, moveable external shutters and a high performance ductless mini-split heat pump. Cost analysis indicates that many of the measures implemented in this project did not meet the BA standard for cost neutrality. The ductless mini-split heat pump, lighting and advanced air leakage control were the most cost effective measures. The future challenge will be to value engineer the performance levels indicated here in modeling using production based practices at a significantly lower cost.

  10. Hood River Passive House

    SciTech Connect

    Hales, David

    2014-01-01

    The Hood River Passive Project was developed by Root Design Build of Hood River Oregon using the Passive House Planning Package (PHPP) to meet all of the requirements for certification under the European Passive House standards. The Passive House design approach has been gaining momentum among residential designers for custom homes and BEopt modeling indicates that these designs may actually exceed the goal of the U.S. Department of Energy's (DOE) Building America program to "reduce home energy use by 30%-50% (compared to 2009 energy codes for new homes). This report documents the short term test results of the Shift House and compares the results of PHPP and BEopt modeling of the project. The design includes high R-Value assemblies, extremely tight construction, high performance doors and windows, solar thermal DHW, heat recovery ventilation, moveable external shutters and a high performance ductless mini-split heat pump. Cost analysis indicates that many of the measures implemented in this project did not meet the BA standard for cost neutrality. The ductless mini-split heat pump, lighting and advanced air leakage control were the most cost effective measures. The future challenge will be to value engineer the performance levels indicated here in modeling using production based practices at a significantly lower cost.

  11. Geomorphology and River Dynamics of the Lower Copper River, Alaska

    USGS Publications Warehouse

    Brabets, Timothy P.; Conaway, Jeffrey S.

    2009-01-01

    Located in south-central Alaska, the Copper River drains an area of more than 24,000 square miles. The average annual flow of the river near its mouth is 63,600 cubic feet per second, but is highly variable between winter and summer. In the winter, flow averages approximately 11,700 cubic feet per second, and in the summer, due to snowmelt, rainfall, and glacial melt, flow averages approximately 113,000 cubic feet per second, an order of magnitude higher. About 15 miles upstream of its mouth, the Copper River flows past the face of Childs Glacier and enters a large, broad, delta. The Copper River Highway traverses this flood plain, and in 2008, 11 bridges were located along this section of the highway. The bridges cross several parts of the Copper River and in recent years, the changing course of the river has seriously damaged some of the bridges. Analysis of aerial photography from 1991, 1996, 2002, 2006, and 2007 indicates the eastward migration of a channel of the Copper River that has resulted in damage to the Copper River Highway near Mile 43.5. Migration of another channel in the flood plain has resulted in damage to the approach of Bridge 339. As a verification of channel change, flow measurements were made at bridges along the Copper River Highway in 2005-07. Analysis of the flow measurements indicate that the total flow of the Copper River has shifted from approximately 50 percent passing through the bridges at Mile 27, near the western edge of the flood plain, and 50 percent passing through the bridges at Mile 36-37 to approximately 5 percent passing through the bridges at Mile 27 and 95 percent through the bridges at Mile 36-37 during average flow periods. The U.S. Geological Survey's Multi-Dimensional Surface-Water Modeling System was used to simulate water-surface elevation and velocity, and to compute bed shear stress at two areas where the Copper River is affecting the Copper River Highway. After calibration, the model was used to examine the

  12. Indicators for transboundary river management.

    PubMed

    Lorenz, C M; Gilbert, A J; Cofino, W P

    2001-07-01

    The aim of this paper is to analyze the potential of indicators for integrated river basin management and to develop a set of indicators for the management of transboundary river basins. An indicator, comprising a variable or some aggregation of variables, describes a system or process such that it has significance beyond the face value of its components. Integrated river basin management takes into account policies and measures for the multifunctional use of rivers on a catchment scale and associated institutional changes. Indicators are useful instruments for this process for two reasons. Firstly, they meet the information need of policy- and decision-makers. Secondly, indicators can be used to structure the definition and description of information needs and collection of information between the different international, institutional, and sectoral management levels. The development of indicators involves a number of steps: definition of aim, construction of conceptual model, selection of variables, comparison with selection criteria, database assessment, and indicator selection. In this paper these steps are discussed and specified for integrated river basin management. This results in a set of indicators describing the pressure to the river, the state of the river ecosystem, the impact to goods and services provided by the river, and the societal response. The proposed set of indicators measured at a river basin scale provides integrated information on the use and supply of goods and services, underlying cause-effect relationships and possible trade-offs and their spatial distribution (e.g., upstream versus downstream). Furthermore, we propose a division of tasks and responsibilities for river basin management with regard to the development of indicators, data collection, and their application in decision-making. PMID:11436995

  13. 6. SANDY RIVER BRIDGE AT TROUTDALE, EAST ELEVATION, LOOKING 306 ...

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

    6. SANDY RIVER BRIDGE AT TROUTDALE, EAST ELEVATION, LOOKING 306 DEGREES NORTHWEST. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  14. 3. SANDY RIVER BRIDGE AT TROUTDALE, NORTH END, LOOKING 184 ...

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

    3. SANDY RIVER BRIDGE AT TROUTDALE, NORTH END, LOOKING 184 DEGREES SOUTH. SAME PHOTO AS OR-36-2. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  15. 7. SANDY RIVER BRIDGE AT TROUTDALE, PERSPECTIVE LOOKING EAST. ...

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

    7. SANDY RIVER BRIDGE AT TROUTDALE, PERSPECTIVE LOOKING EAST. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  16. 1. SANDY RIVER BRIDGE AT TROUTDALE, SOUTH END, LOOKING 18 ...

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

    1. SANDY RIVER BRIDGE AT TROUTDALE, SOUTH END, LOOKING 18 DEGREES NORTH. SAME PHOTO AS OR-36-1. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  17. 2. SANDY RIVER BRIDGE AT TROUTDALE, SOUTH END, LOOKING 20 ...

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

    2. SANDY RIVER BRIDGE AT TROUTDALE, SOUTH END, LOOKING 20 DEGREES NORTH. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  18. 5. SANDY RIVER BRIDGE AT TROUTDALE, EAST ELEVATION DETAIL, LOOKING ...

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

    5. SANDY RIVER BRIDGE AT TROUTDALE, EAST ELEVATION DETAIL, LOOKING 6 DEGREES NORTH. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  19. 4. SANDY RIVER BRIDGE AT TROUTDALE, NORTH END, LOOKING 224 ...

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

    4. SANDY RIVER BRIDGE AT TROUTDALE, NORTH END, LOOKING 224 DEGREES SOUTHWEST. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  20. River network routing in all rivers of the Texas Gulf

    NASA Astrophysics Data System (ADS)

    David, C. H.; Maidment, D. R.; Hong, S.; Niu, G.; Yang, Z.

    2009-12-01

    The mapped rivers and streams of the contiguous United States are available in a high resolution geographic information system (GIS) dataset called NHDPlus. This hydrographic dataset has about 3 million river and water body reaches along with information on how they are connected into networks. A river network model called RAPID is developed for the NHDPlus river network and applied to the 68,143 river reaches of the entire Texas Gulf, whose lateral inflow to the river network is calculated by a land surface model. RAPID allows for a matrix-based calculation of flow and volume of water in all reaches of a river network, with many thousands of reaches. Gages from the USGS National Water Information System are used to assess the quality of model calculations and to automatically determine optimal model parameters with about 1 gage available for each 160 reaches simulated. RAPID is adapted for parallel computing and has been tested on the Lonestar supercomputer (http://www.tacc.utexas.edu/resources/hpcsystems/) although challenges related to parallel computing are significant. The first author was awarded the 2008 Horton (Hydrology) Research Grant for this work.

  1. River-Based Experiential Learning: the Bear River Fellows Program

    NASA Astrophysics Data System (ADS)

    Rosenberg, D. E.; Shirley, B.; Roark, M. F.

    2012-12-01

    The Department of Civil and Environmental Engineering, Outdoor Recreation, and Parks and Recreation programs at Utah State University (USU) have partnered to offer a new, unique river-based experiential learning opportunity for undergraduates called the Bear River Fellows Program. The program allows incoming freshmen Fellows to experience a river first hand during a 5-day/4-night river trip on the nearby Bear River two weeks before the start of their first Fall semester. As part of the program, Fellows will navigate the Bear River in canoes, camp along the banks, interact with local water and environmental managers, collect channel cross section, stream flow, vegetation cover, and topological complexity data, meet other incoming freshmen, interact with faculty and graduate students, develop boating and leadership skills, problem solve, and participate as full members of the trip team. Subsequently, Fellows will get paid as undergraduate researchers during their Fall and Spring Freshman semesters to analyze, synthesize, and present the field data they collect. The program is a collaborative effort between two USU academic units and the (non-academic) division of Student Services and supports a larger National Science Foundation funded environmental modelling and management project for the lower Bear River, Utah watershed. We have advertised the program via Facebook and emails to incoming USU freshmen, received 35 applications (60% women), and accepted 5 Fellows into the program (3 female and 2 male). The river trip departs August 14, 2012. The poster will overview the Bear River Fellows Program and present qualitative and preliminary outcomes emerging from the trip and Fellows' work through the Fall semester with the field data they collect. We will also undertake more rigorous and longer longitudinal quantitative evaluation of Program outcomes (for example, in problem-solving and leadership) both in Spring 2013 and in subsequent 2013 and 2014 offerings of the

  2. Will the Atchafalaya River Capture the Lower Mississippi River?

    NASA Astrophysics Data System (ADS)

    Edmonds, D.

    2011-12-01

    The Old River Control Structure (ORCS) was built in the 1960s to prevent the Atchafalaya River from capturing the lower Mississippi River. The 2011 flood on the Mississippi River tested ORCS and renewed concerns about what would happen to the rivers if ORCS failed. Most consider capture a foregone conclusion if ORCS failed, but this hypothesis has never been tested. A viable alternative hypothesis is that the discharge distribution between the Atchafalaya and Mississippi would stabilize at the relative proportions predicted by recent theory such that both channels transmit water. To test these hypotheses I conducted numerical experiments of the Mississippi-Atchafalaya rivers in the absence of ORCS using Delft3D. All model runs have evolving beds and are depth-integrated. The grid is 2D in planform and follows the banks of each river. The channel walls are fixed, tributaries are not included, and there are no floodplains. At the upstream boundary I specify the water discharge and sediment fluxes. The incoming discharge carries two grain sizes, one noncohesive (200 microns) and one cohesive (15 microns). At the downstream boundaries water surface elevations are set to zero. The initial bed topography in each river comes from 2004 and 2006 hydrographic surveys of the Mississippi and Atchafalaya, respectively. I conducted 7 experiments where the discharge upstream of ORCS (Qup) is steady, but varies among experiments from 5000 m3 s-1 to 50000 m3 s-1. Results show that the response of the rivers depends strongly on Qup. When Qup > 15000 m3 s-1 there is net flow capture by the Atchafalaya, and the capture rate increases with increasing Qup. But when Qup < 15000 m3 s-1 there is net flow capture by the Mississippi. The rates of capture for different values of Qup can be used to calculate if capture would occur for a realistic, unsteady hydrograph.

  3. 33 CFR 207.380 - Red Lake River, Minn.; logging regulations for portion of river above Thief River Falls.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Red Lake River, Minn.; logging regulations for portion of river above Thief River Falls. 207.380 Section 207.380 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS § 207.380 Red Lake River, Minn.;...

  4. 33 CFR 207.380 - Red Lake River, Minn.; logging regulations for portion of river above Thief River Falls.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Red Lake River, Minn.; logging regulations for portion of river above Thief River Falls. 207.380 Section 207.380 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS § 207.380 Red Lake River, Minn.;...

  5. River history and tectonics.

    PubMed

    Vita-Finzi, C

    2012-05-13

    The analysis of crustal deformation by tectonic processes has gained much from the clues offered by drainage geometry and river behaviour, while the interpretation of channel patterns and sequences benefits from information on Earth movements before or during their development. The interplay between the two strands operates at many scales: themes which have already benefited from it include the possible role of mantle plumes in the breakup of Gondwana, the Cenozoic development of drainage systems in Africa and Australia, Himalayan uplift in response to erosion, alternating episodes of uplift and subsidence in the Mississippi delta, buckling of the Indian lithospheric plate, and changes in stream pattern and sinuosity along individual alluvial channels subject to localized deformation. Developments in remote sensing, isotopic dating and numerical modelling are starting to yield quantitative analyses of such effects, to the benefit of geodymamics as well as fluvial hydrology. PMID:22474680

  6. Lena River, Russia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This pair of true- and false-color images from the Moderate Resolution Imaging Spectroradiometer (MODIS) from June 28, 2002, shows numerous burn scars dotting the northern Siberian landscape along the Lena River. In the true-color image, the burn scars appear dark grayish-brown, while in the false-color image they appear red, as does the bare exposed soil of the Verkhoyansk Mountain Range to the east of the north-flowing Lena. A tinge of blue along the mountains in the false-color image means there is some lingering snow or ice, and that the bare soil is due to spring's late arrival there, and not to burn scars. At the top, sea ice still fills the Laptev Sea. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  7. Uplift histories from river profiles

    NASA Astrophysics Data System (ADS)

    Pritchard, D.; Roberts, G. G.; White, N. J.; Richardson, C. N.

    2009-12-01

    Longitudinal river profiles, where elevation of a river bed is plotted as a function of distance along the river bed, contain information about uplift rate. When a region adjacent to a reference level (e.g., sea level) is uplifted, a rapid change in gradient occurs near the river mouth. The erosional process causes this change in gradient to migrate upstream. Thus a river profile is effectively a ‘tape recording’ of the uplift rate history, provided that the erosional process can be adequately parameterized. Here, we use a non-linear equation to relate the shape of a river profile, z(x), to uplift rate history, U(t). If erosion is assumed to be dominated by knickpoint retreat, an inverse model can be formulated and used to calculate uplift rate histories. Our model builds upon standard stream profile analysis, which focuses on the relationship between profile slope and drainage area. We have applied this analytical approach to river profiles from the Bié Dome, Angola. Calculated uplift rate histories agree with independent geologic estimates.

  8. Development and Implementation of a Comprehensive Program to Deal with Canada's Nuclear Legacy Liabilities

    SciTech Connect

    Brown, Peter; Metcalfe, Douglas; Blanchette, Marcia; Dolinar, George; Halpenny, Steven; Purdy, Chris; Smith, David; Kupferschmidt, William

    2008-01-15

    The Government of Canada nuclear legacy liabilities have resulted from 60 years of nuclear research and development (R and D) carried out on behalf of Canada by the National Research Council (1944 to 1952) and Atomic Energy of Canada Limited (AECL, 1952 to present). These liabilities are largely located at AECL research sites, and consist of shutdown research buildings (including several prototype and research reactors), a wide variety of buried and stored wastes, and contaminated lands. The shutdown buildings and contaminated lands need to be safely decommissioned to meet federal regulatory requirements, and long-term solutions need to be developed and implemented for management of the wastes. More than half of the liabilities are the result of Cold War activities during the 1940's, 50's and early 60's. The remaining liabilities stem from R and D for medical isotopes and nuclear reactor technology, as well as national science programs. About 70 percent of the liabilities are located at AECL's Chalk River Laboratories (CRL) in Ontario, and a further 20 percent are located at AECL's shutdown Whiteshell Laboratories in Manitoba. The remaining 10 percent relate largely to three shutdown prototype reactors in Ontario and Quebec, which were key to the developmental stage of Canada's CANDU reactor technology. The inventory of legacy waste includes spent fuel, high-level, intermediate-level and low-level solid and liquid radioactive waste, and wastes (largely contaminated soils) from site clean-up work across Canada. Most of the wastes are in raw, unconditioned form, and limited characterization information is available for the wastes generated in past decades. In many cases unique and potentially costly solutions will be required to recover, handle and process the wastes. In conclusion: the Government of Canada has initiated a program to deal with nuclear legacy liabilities dating back to the Cold War and the birth of nuclear technologies and medicine in Canada. The 5

  9. Ice Jams the Ob River

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Russia's Ob River flows from south to north, and each summer, it thaws in the same direction. The result is that an ice jam sits downstream from thawed portions of the river, which is laden with heavy runoff from melted snow. On June 29, 2007, the Moderate Resolution Imaging Spectroradiometer (MODIS) flying on NASA's Terra satellite captured this image of the almost completely thawed Ob River. The scene is typical for early summer. South of the ice jam, the Gulf of Ob is swollen with pent-up run-off, and upstream from that, the river is widened as well. Unable to carve through frozen land, the river has little choice but to overflow its banks. For a comparison of early summer and autumn conditions, see Flooding on the Ob River in the Earth Observatory's Natural Hazards section. Besides the annual overflow, this image captures other circumstances of early summer. Sea ice is retreating from the Kara Sea. A lingering line of snow cover snakes its way along the Ob River, to the west. And while the land is lush and green in the south, it appears barren and brown in the north. Near the mouth of the river and the Kara Sea, the land is cold-adapted tundra, with diminutive plants and a short growing season. Just as the ice plugging the river had yet to thaw in the Far North's short summer, the tundra had not yet to greened up either. In this image it still appears lifeless beige. NASA image courtesy Jeff Schmaltz, MODIS Rapid Response Team, Goddard Space Flight Center

  10. PCBs in the Harlem River

    NASA Astrophysics Data System (ADS)

    Wang, J.

    2012-12-01

    Polychlorinated biphenyls (PCBs) are persistent, toxic and bioaccumulated contaminants of great environmental concern. PCB is a tracer of wastewater, stormwater and CSOs inputs; PCBs contamination of fish is a main environmental concern for the Harlem River. PCBs in the Harlem River are from combined sewer overflows (CSOs), stormwater runoff, wastewater, as well as upper Hudson GE (General Electric at Fort Edward)'s release. PCBs affect human health mostly from contaminated fish consumption. Many research focused on PCBs in the Hudson River and New York/New Jersey Harbor. However, PCBs source, transport and environmental impact in the Harlem River-a natural straight that connects the Hudson River and the East River, had not been well studied. In this research, water sample were collected from the Harlem River and analyzed PCBs by HR GC/MS (High resolution gas chromatography mass spectrophotometer). Preliminary results showed that certain PCBs congeners in the water column. Results also indicated that nutrients (phosphorus and ammonia) as well as bacteria levels exceeded EPA standards: Total phosphorus-10μg/L, total nitrogen-0.38mg/L; E.Coli-126 MPN/100ml, Enterococcus- 104MPN/100ml, Fecal Coliform-200 MPN/100ml. This research is under process, and more results could give further detail in near future. This research will help improve water quality of the Harlem River, improve environmental health and raise environmental awareness.SO tank Nutrient and bacterial levels of selected sites in the Harlem RiverCSO: Combined Sewer OverflowWWTP: Waste Water Treatment Plant

  11. Status of river herring stocks in large rivers

    USGS Publications Warehouse

    Schmidt, R.E.; Jessop, B.M.; Hightower, J.E.

    2003-01-01

    We examined long-term data sets from large rivers in the northern, central, and southern parts of the ranges of anadromous river herring (alewife Alosa pseudoharengus and blueback herring A. aestivalis) to assess the current status of these species and for evidence of fishery-induced effects on their demographic characteristics. Both species show signs of overexploitation in all rivers examined, such as reductions in mean age, decreases in percentage of returning spawners, and decreases in abundance. These two species should be managed separately since exploitation within a given river is often biased toward one or the other and there are enough differences in their biology so that a single management option will affect them differently. These species are not distinguished in commercial catches, which hinders understanding of their exploitation. ?? 2003 by the American Fisheries Society.

  12. Arctic River organic matter transport

    NASA Astrophysics Data System (ADS)

    Raymond, Peter; Gustafsson, Orjan; Vonk, Jorien; Spencer, Robert; McClelland, Jim

    2016-04-01

    Arctic Rivers have unique hydrology and biogeochemistry. They also have a large impact on the Arctic Ocean due to the large amount of riverine inflow and small ocean volume. With respect to organic matter, their influence is magnified by the large stores of soil carbon and distinct soil hydrology. Here we present a recap of what is known of Arctic River organic matter transport. We will present a summary of what is known of the ages and sources of Arctic River dissolved and particulate organic matter. We will also discuss the current status of what is known about changes in riverine organic matter export due to global change.

  13. Where rivers and oceans collide

    NASA Astrophysics Data System (ADS)

    Crockett, J. S.; Nittrouer, C. A.; Ogston, A. S.; Sternberg, R. W.; Driscoll, N. W.; Babcock, J.; Milliman, J. D.; Slingerland, R.; Naar, D. F.; Donahue, B.; Walsh, J. P.; Dietrich, W.; Parker, G.; Bera, M.; Davies, H.; Harris, P.; Goni, M.; Aller, R.; Aller, J.

    Fluvial sediment fills the coastal ocean, and sea level rise floods river valleys. This epic battle of terrestrial and marine processes occurs along all shorelines, and the complexities are especially well revealed in the Gulf of Papua, a foreland basin on the southern coast of New Guinea. Two hundred to four hundred million tons of sediment are supplied each year by the Fly and other rivers to a continental shelf that has been dissected by ancestors of these same rivers. The new sediment builds a large depositional feature known as a clinoform, which grows seaward and buries the record of earlier environments.

  14. [Characteristics of absorption and fluorescence spectra of dissolved organic matter from confluence of rivers: case study of Qujiang River-Jialing River and Fujiang River-Jialing River].

    PubMed

    Yan, Jin-Long; Jiang, Tao; Gao, Jie; Wei, Shi-Qiang; Lu, Song; Liu, Jiang

    2015-03-01

    Three-dimensional fluorescence spectroscopy combined with ultraviolet-visible (UV-Vis) absorption spectra was used to investigate the change characteristics of dissolved organic matter (DOM) in confluences water of Qujiang River-Jialing River and Fujiang River-Jialing River, respectively. The results suggested that DOM showed a significant terrestrial input signal in all the sampling sites, FI < 1.4, HIX > 0.8, possibly representing remarkable signals of humus resulted from humic-like component. Moreover, the mixing zone of this study showed a non-conservative mixed behavior, which had a limited contribution, and was not the dominant factor to interpret the change characteristics of DOM in confluences zones. Different land-use types along all the rivers had an obvious impact on DOM inputs. Results of cluster analysis showed that a higher degree of aromaticity and humification components was observed as the predominant contributor to DOM when the land-use type was forest and farmland ecosystem, for example the confluences of Qujiang River-Jialing River. On the other hand, high concentrations of DOM with relative simple structures were found in the water when the urban land-use type was predominant, for example the confluences of Fujiang River-Jialing River. Meanwhile, a new fluorescent signal of protein-like components (peak T) appeared, which manifested a significant effect on the water quality resulted from anthropogenic activities. PMID:25929053

  15. Useful characteristics of the Savannah River

    SciTech Connect

    Watts, J R

    1982-05-19

    The following information about the Savannah River is tabulated: significant activities and discharges along the Savannah River, river water temperature data near Jackson st Savannah River Plant, flow informatiom, and reservoir parameters for Clarks Hill, Richard B. Russell and Hartwell reservoirs.

  16. 29 CFR 1917.126 - River banks.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false River banks. 1917.126 Section 1917.126 Labor Regulations...) MARINE TERMINALS Terminal Facilities § 1917.126 River banks. (a) This section applies to temporary installations or temporary operations near a river bank. (b) Where working surfaces at river banks slope...

  17. 29 CFR 1917.126 - River banks.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false River banks. 1917.126 Section 1917.126 Labor Regulations...) MARINE TERMINALS Terminal Facilities § 1917.126 River banks. (a) This section applies to temporary installations or temporary operations near a river bank. (b) Where working surfaces at river banks slope...

  18. 27 CFR 9.164 - River Junction.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false River Junction. 9.164... River Junction. (a) Name. The name of the viticultural area described in this section is “River Junction.” (b) Approved maps. The appropriate maps for determining the boundaries of the River...

  19. 76 FR 23485 - Safety Zone; Red River

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-27

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Red River AGENCY: Coast Guard, DHS. ACTION... Red River in the State of North Dakota, including those portions of the river bordered by Richland... across latitude 46 20'00'' N, extending the entire width of the river. This safety zone is needed...

  20. 29 CFR 1917.126 - River banks.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false River banks. 1917.126 Section 1917.126 Labor Regulations...) MARINE TERMINALS Terminal Facilities § 1917.126 River banks. (a) This section applies to temporary installations or temporary operations near a river bank. (b) Where working surfaces at river banks slope...

  1. 33 CFR 117.237 - Christina River.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Christina River. 117.237 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Delaware § 117.237 Christina River. (a) The owners of... Bridge over Christina River at milepost 1.4 will be closing to river traffic.” Five short blasts of...

  2. 33 CFR 117.237 - Christina River.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Christina River. 117.237 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Delaware § 117.237 Christina River. (a) The owners of... Bridge over Christina River at milepost 1.4 will be closing to river traffic.” Five short blasts of...

  3. 27 CFR 9.164 - River Junction.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false River Junction. 9.164... River Junction. (a) Name. The name of the viticultural area described in this section is “River Junction.” (b) Approved maps. The appropriate maps for determining the boundaries of the River...

  4. 29 CFR 1917.126 - River banks.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false River banks. 1917.126 Section 1917.126 Labor Regulations...) MARINE TERMINALS Terminal Facilities § 1917.126 River banks. (a) This section applies to temporary installations or temporary operations near a river bank. (b) Where working surfaces at river banks slope...

  5. 29 CFR 1917.126 - River banks.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 7 2013-07-01 2013-07-01 false River banks. 1917.126 Section 1917.126 Labor Regulations...) MARINE TERMINALS Terminal Facilities § 1917.126 River banks. (a) This section applies to temporary installations or temporary operations near a river bank. (b) Where working surfaces at river banks slope...

  6. 33 CFR 117.237 - Christina River.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Christina River. 117.237 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Delaware § 117.237 Christina River. (a) The owners of... Bridge over Christina River at milepost 1.4 will be closing to river traffic.” Five short blasts of...

  7. 33 CFR 117.237 - Christina River.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Christina River. 117.237 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Delaware § 117.237 Christina River. (a) The owners of... Bridge over Christina River at milepost 1.4 will be closing to river traffic.” Five short blasts of...

  8. 33 CFR 117.237 - Christina River.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Christina River. 117.237 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Delaware § 117.237 Christina River. (a) The owners of... Bridge over Christina River at milepost 1.4 will be closing to river traffic.” Five short blasts of...

  9. 78 FR 22423 - Drawbridge Operation Regulations; Taunton River, Fall River and Somerset, MA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-16

    ... SECURITY Coast Guard 33 CFR Part 117 Drawbridge Operation Regulations; Taunton River, Fall River and... Brightman Street Bridge across the Taunton River, mile 1.8, between Fall River and Somerset, Massachusetts.... The Taunton River is a recreational waterway. The bridge rarely opens during the time period...

  10. Elwha River dam removal-Rebirth of a river

    USGS Publications Warehouse

    Duda, Jeffrey J.; Warrick, Jonathan A.; Magirl, Christopher S.

    2011-01-01

    After years of planning for the largest project of its kind, the Department of the Interior will begin removal of two dams on the Elwha River, Washington, in September 2011. For nearly 100 years, the Elwha and Glines Canyon Dams have disrupted natural processes, trapping sediment in the reservoirs and blocking fish migrations, which changed the ecology of the river downstream of the dams. All five Pacific salmon species and steelhead-historically present in large numbers-are locally extirpated or persist in critically low numbers. Upstream of the dams, more than 145 kilometers of pristine habitat, protected inside Olympic National Park, awaits the return of salmon populations. As the dams are removed during a 2-3 year project, some of the 19 million cubic meters of entrapped sediment will be carried downstream by the river in the largest controlled release of sediment into a river and marine waters in history. Understanding the changes to the river and coastal habitats, the fate of sediments, and the salmon recolonization of the Elwha River wilderness will provide useful information for society as future dam removals are considered.

  11. Flooding on California's Russian River: Role of atmospheric rivers

    USGS Publications Warehouse

    Ralph, F.M.; Neiman, P.J.; Wick, G.A.; Gutman, S.I.; Dettinger, M.D.; Cayan, D.R.; White, A.B.

    2006-01-01

    Experimental observations collected during meteorological field studies conducted by the National Oceanic and Atmospheric Administration near the Russian River of coastal northern California are combined with SSM/I satellite observations offshore to examine the role of landfalling atmospheric rivers in the creation of flooding. While recent studies have documented the characteristics and importance of narrow regions of strong meridional water vapor transport over the eastern Pacific Ocean (recently referred to as atmospheric rivers), this study describes their impact when they strike the U.S. West Coast. A detailed case study is presented, along with an assessment of all 7 floods on the Russian River since the experimental data were first available in October 1997. In all 7 floods, atmospheric river conditions were present and caused heavy rainfall through orographic precipitation. Not only do atmospheric rivers play a crucial role in the global water budget, they can also lead to heavy coastal rainfall and flooding, and thus represent a key phenomenon linkingweather and climate. Copyright 2006 by the American Geophysical Union.

  12. Quaternary Morphodynamics for two large rivers: the Fly River, PNG, and the Mekong River, Cambodia.

    NASA Astrophysics Data System (ADS)

    Aalto, R. E.; Lauer, J. W.; Darby, S. E.; Goni, M. A.; Dietrich, W. E.

    2014-12-01

    During glacial marine transgressions, sediment & carbon are deposited due to the infilling of lowland fluvial systems, material that is then largely removed during ensuing regressions. Measuring & modelling these processes would help quantify the amount, timing, & preservation of these materials, providing insight into the morphodynamics of lowland fluvial systems in response to sea level change. We investigated the infilling dynamics of the Fly and Strickland Rivers, Papua New Guinea. Field data include: 14C dated deep cores recording base level evolution over the Holocene, sonar imaging of floodbasin stratigraphy, and the observations of blocked valley lakes and weathered erosional remnants from LGM conditions. Similar research was conducted on the Mekong River, Cambodia, where we have imaged basin fill stratigraphy and recorded the extent of blocked valley lakes. Such field data provide tantalizing empirical glimpses into the landscapes & flux buffering exhibited by large tropical rivers during glacial-interglacial transitions. We upscale our observations by modelling river system evolution, employing a GpU Lowland Landscape Evolution Model (GULLEM) to predict the evolution of the entire basin. A novel & powerful (>10 Tflops on an inexpensive computer) simulator, GULLEM models morphodynamics and estimates the accommodation space subsequently infilled during marine transgressions by representing a range of geomorphic processes, including: river & tributary incision, non-linear diffusion, sea level and isostatic change, hydraulic geometry, tectonic deformation, sediment production, transport & deposition, & tracking of the resulting stratigraphy. GULLEM's vectorized approach allows for massively parallel operation on GPUs (Graphics Processing Unit), making it practical to model coupled fluvial-landscape evolution for complex lowland river systems over large temporal and spatial scales. Our combined approach affords estimates for the timing and budgets of sediment

  13. Remote sensing at Savannah River

    SciTech Connect

    Corey, J.C.

    1986-01-01

    The paper discusses remote sensing systems used at the Savannah River Plant. They include three ground-based systems: ground penetrating radar, sniffers, and lasers; and four airborne systems: multispectral photography, lasers, thermal imaging, and radar systems. (ACR)

  14. NEUSE RIVER WATER QUALITY DATABASE

    EPA Science Inventory

    The Neuse River water quality database is a Microsoft Access application that includes multiple data tables and some associated queries. The database was developed by Prof. Jim Bowen's research group.

  15. Manganese oxidation model for rivers

    USGS Publications Warehouse

    Hess, Glen W.; Kim, Byung R.; Roberts, Philip J.W.

    1989-01-01

    The presence of manganese in natural waters (>0.05 mg/L) degrades water-supply quality. A model was devised to predict the variation of manganese concentrations in river water released from an impoundment with the distance downstream. The model is one-dimensional and was calibrated using dissolved oxygen, biochemical oxygen demand, pH, manganese, and hydraulic data collected in the Duck River, Tennessee. The results indicated that the model can predict manganese levels under various conditions. The model was then applied to the Chattahoochee River, Georgia. Discrepancies between observed and predicted may be due to inadequate pH data, precipitation of sediment particles, unsteady flow conditions in the Chattahoochee River, inaccurate rate expressions for the low pH conditions, or their combinations.

  16. Humboldt River main stem, Nevada

    USGS Publications Warehouse

    Warmath, Eric; Medina, Rose L.

    2001-01-01

    This data set contains the main stem of the Humboldt River as defined by Humboldt Project personnel of the U.S. Geological Survey Nevada District, 2001. The data set was digitized on screen using digital orthophoto quadrangles from 1994.

  17. Mississippi River Delta

    NASA Technical Reports Server (NTRS)

    2002-01-01

    As the Mississippi River enters the Gulf of Mexico, it loses energy and dumps its load of sediment that it has carried on its journey through the mid continent. This pile of sediment, or mud, accumulates over the years building up the delta front. As one part of the delta becomes clogged with sediment, the delta front will migrate in search of new areas to grow. The area shown on this image is the currently active delta front of the Mississippi. The migratory nature of the delta forms natural traps for oil. Most of the land in the image consists of mud flats and marsh lands. There is little human settlement in this area due to the instability of the sediments. The main shipping channel of the Mississippi River is the broad stripe running northwest to southeast.

    This image was acquired on May 24, 2001 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. 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

  18. River patterns and their meaning

    NASA Astrophysics Data System (ADS)

    Twidale, C. R.

    2004-10-01

    Rivers are largely responsible for shaping the Earth's continental landscapes. River patterns, the spatial arrangements of channels in the landscape, are determined by slope and structure. At site and sector scale, channel morphology varies spatially and in time, but river patterns and drainage texture, or the frequency of stream lines per unit area, together determine the intricacy, or otherwise, of topography. Most river patterns evolve through natural selection. Slope induces the formation of such patterns as parallel, radial and distributary, while structure produces straight, angular, trellis and annular arrangements. Once established, patterns tend to persist. Nevertheless, at many sites the usual patterns have been disturbed and patterns that are anomalous in terms of slope and structure have been produced by diversion, tectonism, volcanism, glaciation, mass movements, and human activities; by antecedence, superimposition, inheritance or underprinting; by the persistence of deeply eroding rivers which encounter alien structures; and by climatic change. River patterns provide clues to underlying structure and to the chronology of events. They have also proved significant in the search for minerals.

  19. 76 FR 75543 - Missisquoi River Technologies; Missisquoi River Hydro LLC; Notice of Transfer of Exemption

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-02

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Missisquoi River Technologies; Missisquoi River Hydro LLC; Notice of Transfer of Exemption 1. By letter filed November 16, 2011, Missisquoi River Technologies informed...

  20. 77 FR 45653 - Yakima River Basin Conservation Advisory Group; Yakima River Basin Water Enhancement Project...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-01

    ... Bureau of Reclamation Yakima River Basin Conservation Advisory Group; Yakima River Basin Water... on the structure, implementation, and oversight of the Yakima River Basin Water Conservation Program... of the Water Conservation Program, including the applicable water conservation guidelines of...

  1. 76 FR 71342 - Proposed CERCLA Administrative Cost Recovery Settlement; River Forest Dry Cleaners Site, River...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-17

    ... AGENCY Proposed CERCLA Administrative Cost Recovery Settlement; River Forest Dry Cleaners Site, River Forest, Cook County, IL AGENCY: Environmental Protection Agency (EPA). ACTION: Notice; request for public... proposed administrative settlement for recovery of past response costs concerning the River Forest...

  2. Impacts of urbanization on river system structure: a case study on Qinhuai River Basin, Yangtze River Delta.

    PubMed

    Ji, Xiaomin; Xu, Youpeng; Han, Longfei; Yang, Liu

    2014-01-01

    Stream structure is usually dominated by various human activities over a short term. An analysis of variation in stream structure from 1979 to 2009 in the Qinhuai River Basin, China, was performed based on remote sensing images and topographic maps by using ArcGIS. A series of river parameters derived from river geomorphology are listed to describe the status of river structure in the past and present. Results showed that urbanization caused a huge increase in the impervious area. The number of rivers in the study area has decreased and length of rivers has shortened. Over the 30 years, there was a 41.03% decrease in river length. Complexity and stability of streams have also changed and consequently the storage capacities of river channels in intensively urbanized areas are much lower than in moderately urbanized areas, indicating a greater risk of floods. Therefore, more attention should be paid to the urban disturbance to rivers. PMID:25116497

  3. Ecosystem Services of Rivers: The Don River (Russian Federation) and the Roanoke River (USA)

    EPA Science Inventory

    The concept of ecosystem services recognizes the services, and benefits, provided to people by ecosystems. River systems provide many services to people, including freshwater provisioning, carbon storage, fisheries, recreation, transportation, and biodiversity. Here, we review th...

  4. Valley evolution by meandering rivers

    NASA Astrophysics Data System (ADS)

    Limaye, Ajay Brian Sanjay

    Fluvial systems form landscapes and sedimentary deposits with a rich hierarchy of structures that extend from grain- to valley scale. Large-scale pattern formation in fluvial systems is commonly attributed to forcing by external factors, including climate change, tectonic uplift, and sea-level change. Yet over geologic timescales, rivers may also develop large-scale erosional and depositional patterns that do not bear on environmental history. This dissertation uses a combination of numerical modeling and topographic analysis to identify and quantify patterns in river valleys that form as a consequence of river meandering alone, under constant external forcing. Chapter 2 identifies a numerical artifact in existing, grid-based models that represent the co-evolution of river channel migration and bank strength over geologic timescales. A new, vector-based technique for bank-material tracking is shown to improve predictions for the evolution of meander belts, floodplains, sedimentary deposits formed by aggrading channels, and bedrock river valleys, particularly when spatial contrasts in bank strength are strong. Chapters 3 and 4 apply this numerical technique to establishing valley topography formed by a vertically incising, meandering river subject to constant external forcing---which should serve as the null hypothesis for valley evolution. In Chapter 3, this scenario is shown to explain a variety of common bedrock river valley types and smaller-scale features within them---including entrenched channels, long-wavelength, arcuate scars in valley walls, and bedrock-cored river terraces. Chapter 4 describes the age and geometric statistics of river terraces formed by meandering with constant external forcing, and compares them to terraces in natural river valleys. The frequency of intrinsic terrace formation by meandering is shown to reflect a characteristic relief-generation timescale, and terrace length is identified as a key criterion for distinguishing these

  5. 11. OVERVIEW FROM WEST BANK OF SCHUYLKILL RIVER, LOOKING EAST. ...

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

    11. OVERVIEW FROM WEST BANK OF SCHUYLKILL RIVER, LOOKING EAST. - Philadelphia & Reading Railroad, Schuylkill River Viaduct, Spanning Schuylkill River, southeast of Roosevelt Boulevard Bridge, Philadelphia, Philadelphia County, PA

  6. 17. OVERVIEW FROM WEST BANK OF SCHUYLKILL RIVER, LOOKING EAST ...

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

    17. OVERVIEW FROM WEST BANK OF SCHUYLKILL RIVER, LOOKING EAST - Philadelphia & Reading Railroad, Schuylkill River Viaduct, Spanning Schuylkill River, southeast of Roosevelt Boulevard Bridge, Philadelphia, Philadelphia County, PA

  7. 9. LOOKING NW FROM EAST BANK OF SCHUYLKILL RIVER. ...

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

    9. LOOKING NW FROM EAST BANK OF SCHUYLKILL RIVER. - Philadelphia & Reading Railroad, Schuylkill River Viaduct, Spanning Schuylkill River, southeast of Roosevelt Boulevard Bridge, Philadelphia, Philadelphia County, PA

  8. VIEW OF APALACHICOLA RIVER BRIDGE WEST APPROACH (CALHOUN COUNTY SIDE), ...

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

    VIEW OF APALACHICOLA RIVER BRIDGE WEST APPROACH (CALHOUN COUNTY SIDE), SOUTH SIDE, FACING NORTHEAST - Apalachicola River Bridge, State Route 20 spanning the Apalachicola River, Blountstown, Calhoun County, FL

  9. Yazoo River Basin (Lower Mississippi River) Hydrologic Observatory

    NASA Astrophysics Data System (ADS)

    Cheng, A.; Davidson, G.; Altinakar, M.; Holt, R.

    2004-12-01

    The proposed Yazoo River Basin Hydrologic Observatory consists of the 34,000 square km Yazoo River watershed in northwestern Mississippi and a 320 km segment of the Mississippi River separated from the watershed by a manmade levee. Discharge from the basin flows from the Yazoo River into the Mississippi River north of Vicksburg, MS. Major streams within the basin include the Yazoo, Tallahatchie, Yalobusha, Coldwater, Yocona, and Big Sunflower Rivers. Four large flood control reservoirs (Arkabutla, Enid, Sardis, and Grenada) and two national forests (Delta and Holly Springs) are also located within the basin. The watershed is divided between upland forested hills and intensively cultivated lowlands. The lowland area, locally known as the "Delta", lies on the ancestral floodplain of the Mississippi River. Flooding by the Mississippi River was once a common event, but is now limited by the levee system. Abundant wetlands occupy abandoned stream channels throughout the Delta. The Yazoo River Basin has many unique features that make it an attractive site for an Hydrologic Observatory. Example features and issues of scientific interest include: 1) Extensive system of levees which have altered recharge to the regional aquifer, shifted population centers, and created backwater flooding areas. 2) Abundant wetlands with a century-long history of response to agricultural sediment and chemical fluxes. 3) Erosion of upland streams, and stream sediment loads that are the highest in the nation. 4) Groundwater mining in spite of abundant precipitation due to a regional surface clay layer that limits infiltration. 5) A history of agricultural Best Management Practices enabling evaluation of the effectiveness of such measures. 6) Large scale catfish farming with heavy reliance on groundwater. 7) Near enough to the Gulf coast to be impacted by hurricane events. 8) Already existing network of monitoring stations for stream flow, sediment-load, and weather, including complete coverage

  10. Dispersal scaling from the world's rivers

    USGS Publications Warehouse

    Warrick, J.A.; Fong, D.A.

    2004-01-01

    Although rivers provide important biogeochemical inputs to oceans, there are currently no descriptive or predictive relationships of the spatial scales of these river influences. Our combined satellite, laboratory, field and modeling results show that the coastal dispersal areas of small, mountainous rivers exhibit remarkable self-similar scaling relationships over many orders of magnitude. River plume areas scale with source drainage area to a power significantly less than one (average = 0.65), and this power relationship decreases significantly with distance offshore of the river mouth. Observations of plumes from large rivers reveal that this scaling continues over six orders of magnitude of river drainage basin areas. This suggests that the cumulative area of coastal influence for many of the smallest rivers of the world is greater than that of single rivers of equal watershed size. Copyright 2004 by the American Geophysical Union.

  11. Pecos River Water Management Project

    NASA Astrophysics Data System (ADS)

    Roberts, J. D.; James, S. C.

    2003-12-01

    Sandia National Laboratories is providing technical assistance to farmer members of the Carlsbad Irrigation District (CID) to better plan the storage, delivery, and application of water to the Carlsbad Project. The surface waters along the Pecos River are allocated by the State of New Mexico to three major entities: 1) The State of Texas - each year a percentage of water from the natural river flow must be delivered to Texas as governed by the Interstate Streams Commission; 2) CID farmer members - a fixed portion of water must be delivered to the farming members of the CID; and 3) wildlife - an amount of water must be allocated to support the wildlife habitat in the Pecos River, most notably, the endangered Pecos Bluntnose Shiner Minnow. The Pecos Bluntnose Shiner Minnow habitat preference is under investigation by other state and national agencies and preliminary work has established that water depth, water velocity, and sediment activity (dunes, ripples, etc.) are the key parameters influencing minnow habitat preference. The amount of water (river flow rate) necessary to maintain a preferable habitat to support this species has yet to be determined. With a limited amount of water in the Pecos River and its reservoirs, it is critical to allocate water efficiently such that habitat is maintained, the farmers of the CID are supported, and New Mexico meets its commitments to the State of Texas. This study investigates the relationship between flow rate in the river and water depth, water velocity, and sediment activity. The goal is to establish a predictive tool that supports informed decisions about water management practices along the Pecos River that will maximize water available for agriculture and the State of Texas while maintaining the aquatic habitat.

  12. Flood trends and river engineering on the Mississippi River system

    USGS Publications Warehouse

    Pinter, N.; Jemberie, A.A.; Remo, J.W.F.; Heine, R.A.; Ickes, B.S.

    2008-01-01

    Along >4000 km of the Mississippi River system, we document that climate, land-use change, and river engineering have contributed to statistically significant increases in flooding over the past 100-150 years. Trends were tested using a database of >8 million hydrological measurements. A geospatial database of historical engineering construction was used to quantify the response of flood levels to each unit of engineering infrastructure. Significant climate- and/or land use-driven increases in flow were detected, but the largest and most pervasive contributors to increased flooding on the Mississippi River system were wing dikes and related navigational structures, followed by progressive levee construction. In the area of the 2008 Upper Mississippi flood, for example, about 2 m of the flood crest is linked to navigational and flood-control engineering. Systemwide, large increases in flood levels were documented at locations and at times of wing-dike and levee construction. Copyright 2008 by the American Geophysical Union.

  13. Intermittent ephemeral river-breaching

    NASA Astrophysics Data System (ADS)

    Reniers, A. J.; MacMahan, J. H.; Gallagher, E. L.; Shanks, A.; Morgan, S.; Jarvis, M.; Thornton, E. B.; Brown, J.; Fujimura, A.

    2012-12-01

    In the summer of 2011 we performed a field experiment in Carmel River State Beach, CA, at a time when the intermittent natural breaching of the ephemeral Carmel River occurred due to an unusually rainy period prior to the experiment associated with El Nino. At this time the river would fill the lagoon over the period of a number of days after which a breach would occur. This allowed us to document a number of breaches with unique pre- and post-breach topographic surveys, accompanying ocean and lagoon water elevations as well as extremely high flow (4m/s) velocities in the river mouth during the breaching event. The topographic surveys were obtained with a GPS-equipped backpack mounted on a walking human and show the evolution of the river breaching with a gradually widening and deepening river channel that cuts through the pre-existing beach and berm. The beach face is qualified as a steep with an average beach slope of 1:10 with significant reflection of the incident waves (MacMahan et al., 2012). The wave directions are generally shore normal as the waves refract over the deep canyon that is located offshore of the beach. The tide is mixed semi-diurnal with a range on the order of one meter. Breaching typically occurred during the low-low tide. Grain size is highly variable along the beach with layers of alternating fine and coarse material that could clearly be observed as the river exit channel was cutting through the beach. Large rocky outcroppings buried under the beach sand are also present along certain stretches of the beach controlling the depth of the breaching channel. The changes in the water level measured within the lagoon and the ocean side allows for an estimate of the volume flux associated with the breach as function of morphology, tidal elevation and wave conditions as well as an assessment of the conditions and mechanisms of breach closure, which occurred on the time scale of O(0.5 days). Exploratory model simulations will be presented at the

  14. Tsunami Bores in Kitakami River

    NASA Astrophysics Data System (ADS)

    Tolkova, Elena; Tanaka, Hitoshi

    2016-07-01

    The 2011 Tohoku tsunami entered the Kitakami river and propagated there as a train of shock waves, recorded with a 1-min interval at water level stations at Fukuchi, Iino, and the weir 17.2 km from the mouth, where the bulk of the wave was reflected back. The records showed that each bore kept its shape and identity as it traveled a 10.9-km-path Fukuchi-Iino-weir-Iino. Shock handling based on the cross-river integrated classical shock conditions was applied to reconstruct the flow velocity time histories at the measurement sites, to estimate inflow into the river at each site, to evaluate the wave heights of incident and reflected tsunami bores near the weir, and to estimate propagation speed of the individual bores. Theoretical predictions are verified against the measurements. We discuss experiences of exercising the shock conditions with actual tsunami measurements in the Kitakami river, and test applicability of the shallow-water approximation for describing tsunami bores with heights ranging from 0.3 to 4 m in a river segment with a depth of 3-4 m.

  15. Morphodynamics: Rivers beyond steady state

    NASA Astrophysics Data System (ADS)

    Church, M.; Ferguson, R. I.

    2015-04-01

    The morphology of an alluvial river channel affects the movement of water and sediment along it, but in the longer run is shaped by those processes. This interplay has mostly been investigated empirically within the paradigm of Newtonian mechanics. In rivers, this has created an emphasis on equilibrium configurations with simple morphology and uniform steady flow. But transient adjustment, whether between equilibrium states or indefinitely, is to be expected in a world in which hydrology, sediment supply, and base level are not fixed. More fundamentally, water flows and all the phenomena that accompany them are inherently unsteady, and flows in natural channels are characteristically nonuniform. The morphodynamics of alluvial river channels is the striking consequence. In this paper, we develop the essential connection between the episodic nature of bed material transport and the production of river morphology, emphasizing the fundamental problems of sediment transport, the role of bar evolution in determining channel form, the role of riparian vegetation, and the wide range of time scales for change. As the key integrative exercise, we emphasize the importance of physics-based modeling of morphodynamics. We note consequences that can be of benefit to society if properly understood. These include the possibility to better be able to model how varying flows drive morphodynamic change, to understand the influence of the sediments themselves on morphodynamics, and to recognize the inherent necessity for rivers that transport bed material to deform laterally. We acknowledge pioneering contributions in WRR and elsewhere that have introduced some of these themes.

  16. Towards a sociogeomorphology of rivers

    NASA Astrophysics Data System (ADS)

    Ashmore, Peter

    2015-12-01

    While human impacts on rivers and other landforms have long been a component of geomorphic research, little of this work explicitly includes insights into human agency from social science or recognises that in many cases rivers can be considered to be hybrid co-productions or 'socio-natures'. A socio-geomorphic approach proposed here has parallels with some aspects of sociohydrology and can extend and enrich existing geomorphic explanations of the morphology of, for example, urban rivers by explicitly recognising and working with the co-evolution of the human and natural systems. Examples from recent literature illustrate ways in which these relationships can be understood and analyzed, showing a range of socio-natural influences in particular contexts that have material consequences for river morphology and recognising that events in the system have many forms. The approach recognises the importance of contingency in time and place together with the role and nature of both local and global knowledge. An important element of this approach is that it provides ways for understanding the nature, position and intention of geomorphic and other scientific interventions as part of the system, for example in the case of river restoration. This also leads to the need for reflexivity by geomorphologists and reconsideration of the nature of geomorphological knowledge by those involved in such work and with respect to sociogeomorphology as a whole.

  17. Colloids in the River Inn

    NASA Astrophysics Data System (ADS)

    Ueckert, Martina; Baumann, Thomas

    2014-05-01

    In the light of an increasing number of technical applications using nanoparticles and reports of adverse effects of engineered nanoparticles, research on the occurrence and stability of particles in all compartments has to be intensified. Colloids in river water represent the geologic setting, environmental conditions, and the anthropogenic use in its catchment. The river not only acts as a sink for nanoparticles but also as the source term due to exchange in the hyporheic zone and in bank filtration setups. The concentration, size distribution and elemental composition of particles in the River Inn were studied from the source in the Swiss Alps to the river mouth at Passau. Samples were collected after each tributary from a sub-catchment and filtered on-site. The elemental composition was determined after acid digestion with ICP/MS. SEM/EDX analyses provided morphological and elemental information for single particles. A complementary chemical analysis of the river water was performed to assess the geochemical stability of indvidual particles. Particles in the upper, rural parts mainly reveal changes in the geological setting of the tributary catchments. Not unexpectedly, particles originating from crystalline rocks, were more stable than particles originating from calcareous rocks. Anthropogenic and industrial influences increase in the lower parts. This went together with a change of the size distribution, an increase of the number of organic particles, and a decrease of the microfauna. Interestingly, specific leisure activities in a sub-catchment, like extensive downhill skiing, manifest itself in the particle composition.

  18. The economic value of Trinity River water

    USGS Publications Warehouse

    Douglas, A.J.; Taylor, J.G.

    1999-01-01

    The Trinity River, largest tributary of the Klamath River, has its head-waters in the Trinity Alps of north-central California. After the construction of Trinity Dam in 1963, 90% of the Trinity River flow at Lewiston was moved to the Sacramento River via the Clear Creek Tunnel, a manmade conduit. Hydropower is produced at four installations along the route of Trinity River water that is diverted to the Sacramento River, and power production at three of these installations would diminish if no Trinity River water were diverted to the Sacramento River. After Trinity River water reaches the Sacramento River, it flows toward the Sacramento-San Joaquin Delta and San Francisco Bay. Trinity River water is pumped via Bureau of Reclamation canals and pumps to the northern San Joaquin Valley, where it is used for irrigated agriculture. The social cost of putting more water down the Trinity River is the sum of the value of the foregone consumer surplus from hydropower production as well as the value of the foregone irrigation water. Sharply diminished instream flows have also severely affected the size and robustness of Trinity River salmon, steelhead, shad and sturgeon runs. Survey data were used to estimate the non-market benefits of augmenting Trinity River instream flows by letting more water flow down the Trinity and moving less water to the Sacramento River. Preservation benefits for Trinity River instream flows and fish runs are $803 million per annum for the scenario that returns the most water down the Trinity River, a value that greatly exceeds the social cost estimate.The Trinity River, largest tributary of the Klamath River, has its headwaters in the Trinity Alps of north-central California. After the construction of Trinity Dam in 1963, 90% of the Trinity River flow at Lewiston was moved to the Sacramento River via the Clear Creek Tunnel, a manmade conduit. Hydropower is produced at four installations along the route of Trinity River water that is diverted to the

  19. The River Danube: An Examination of Navigation on the River

    NASA Astrophysics Data System (ADS)

    Cooper, R. W.

    One of the definitions of Navigation that gets little attention in this Institute is (Oxford English Dictionary), and which our French friends call La Navigation. I have always found this subject fascinating, and have previously navigated the Rivers Mekong, Irrawaddy, Hooghly, Indus, Shatt-al-Arab, Savannah and RhMainKanal (RMDK) and the River Danube, a distance of approximately 4000 km. This voyage has only recently become possible with the opening of the connecting RMDK at the end of 1992, but has been made little use of because of the civil war in the former Yugoslavia.

  20. 1. SNAKE RIVER VALLEY IRRIGATION DISTRICT DAM, VIEW OF NORTH ...

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

    1. SNAKE RIVER VALLEY IRRIGATION DISTRICT DAM, VIEW OF NORTH ELEVATION OF INTAKE ON EAST SIDE OF DAM - Snake River Valley Irrigation District, East Side of Snake River (River Mile 796), Shelley, Bingham County, ID

  1. Sacramento River Water Treatment Plant Intake Pier & Access Bridge, ...

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

    Sacramento River Water Treatment Plant Intake Pier & Access Bridge, Spanning Sacramento River approximately 175 feet west of eastern levee on river; roughly .5 mile downstream from confluence of Sacramento & American Rivers, Sacramento, Sacramento County, CA

  2. 3. SANDY RIVER (STARK ST.) BRIDGE, SOUTH END, LOOKING 295 ...

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

    3. SANDY RIVER (STARK ST.) BRIDGE, SOUTH END, LOOKING 295 DEGREES WEST-SOUTHWEST. - Historic Columbia River Highway, Stark Street Bridge, Spanning Sandy River on Stark Street at Historic Columbia River Highway, Troutdale, Multnomah County, OR

  3. 1. SANDY RIVER (STARK ST.) BRIDGE, NORTH END, LOOKING 135 ...

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

    1. SANDY RIVER (STARK ST.) BRIDGE, NORTH END, LOOKING 135 DEGREES SOUTHEAST. - Historic Columbia River Highway, Stark Street Bridge, Spanning Sandy River on Stark Street at Historic Columbia River Highway, Troutdale, Multnomah County, OR

  4. 5. SANDY RIVER (STARK ST.) BRIDGE, EAST ELEVATION, LOOKING 194 ...

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

    5. SANDY RIVER (STARK ST.) BRIDGE, EAST ELEVATION, LOOKING 194 DEGREES SOUTH. - Historic Columbia River Highway, Stark Street Bridge, Spanning Sandy River on Stark Street at Historic Columbia River Highway, Troutdale, Multnomah County, OR

  5. 4. SANDY RIVER (STARK ST.) BRIDGE, WEST ELEVATION, LOOKING 118 ...

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

    4. SANDY RIVER (STARK ST.) BRIDGE, WEST ELEVATION, LOOKING 118 DEGREES EAST-SOUTHEAST. - Historic Columbia River Highway, Stark Street Bridge, Spanning Sandy River on Stark Street at Historic Columbia River Highway, Troutdale, Multnomah County, OR

  6. 2. SANDY RIVER (STARK ST.) BRIDGE, NORTH END, LOOKING 163 ...

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

    2. SANDY RIVER (STARK ST.) BRIDGE, NORTH END, LOOKING 163 DEGREES SOUTH. - Historic Columbia River Highway, Stark Street Bridge, Spanning Sandy River on Stark Street at Historic Columbia River Highway, Troutdale, Multnomah County, OR

  7. Past, present, and future concepts in large river ecology

    USGS Publications Warehouse

    Johnson, B.L.; Richardson, W.B.; Naimo, T.J.

    1995-01-01

    How rivers function and how human activities influence river processes. Many important questions are likely to require natural experiments or large-scale manipulations that compare rivers or river reaches.

  8. VIEW OF APALACHICOLA RIVER BRIDGE SPANS 2, 3, AND 4, ...

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

    VIEW OF APALACHICOLA RIVER BRIDGE SPANS 2, 3, AND 4, EAST SIDE, FROM CENTER OF RIVER, FACING WEST - Apalachicola River Bridge, State Route 20 spanning the Apalachicola River, Blountstown, Calhoun County, FL

  9. VIEW OF APALACHICOLA RIVER BRIDGE SPANS 2, 3, 4, AND ...

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

    VIEW OF APALACHICOLA RIVER BRIDGE SPANS 2, 3, 4, AND 5, EAST SIDE, FROM NORTH SHORE OF RIVER (CALHOUN COUNTY SIDE), FACING SOUTH - Apalachicola River Bridge, State Route 20 spanning the Apalachicola River, Blountstown, Calhoun County, FL

  10. VIEW OF APALACHICOLA RIVER BRIDGE SPANS 1, 2, 3, 4, ...

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

    VIEW OF APALACHICOLA RIVER BRIDGE SPANS 1, 2, 3, 4, AND 5, EAST SIDE, FROM SOUTH SHORE OF RIVER (LIBERTY COUNTY SIDE), FACING WEST - Apalachicola River Bridge, State Route 20 spanning the Apalachicola River, Blountstown, Calhoun County, FL

  11. VIEW OF APALACHICOLA RIVER BRIDGE PIER 3 SHOWING LOWER PEDESTAL ...

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

    VIEW OF APALACHICOLA RIVER BRIDGE PIER 3 SHOWING LOWER PEDESTAL AND FRAMING OF STEEL BRIDGE TRUSS, EAST SIDE, FROM RIVER, FACING WEST - Apalachicola River Bridge, State Route 20 spanning the Apalachicola River, Blountstown, Calhoun County, FL

  12. VIEW OF APALACHICOLA RIVER BRIDGE SPAN 3, SHOWING EAST SIDE ...

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

    VIEW OF APALACHICOLA RIVER BRIDGE SPAN 3, SHOWING EAST SIDE AND SUBSTRUCTURE, FROM CENTER OF RIVER, FACING SOUTHWEST - Apalachicola River Bridge, State Route 20 spanning the Apalachicola River, Blountstown, Calhoun County, FL

  13. VIEW OF APALACHICOLA RIVER BRIDGE SPANS 3, 4, AND 5, ...

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

    VIEW OF APALACHICOLA RIVER BRIDGE SPANS 3, 4, AND 5, WEST SIDE, FROM NORTH SHORE OF RIVER (CALHOUN COUNTY SIDE), FACING SOUTHEAST - Apalachicola River Bridge, State Route 20 spanning the Apalachicola River, Blountstown, Calhoun County, FL

  14. VIEW OF APALACHICOLA RIVER BRIDGE SPANS 2, 3, AND 4, ...

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

    VIEW OF APALACHICOLA RIVER BRIDGE SPANS 2, 3, AND 4, WEST SIDE, FROM CENTER OF RIVER, FACING EAST - Apalachicola River Bridge, State Route 20 spanning the Apalachicola River, Blountstown, Calhoun County, FL

  15. VIEW OF APALACHICOLA RIVER BRIDGE STEEL BRIDGE TRUSS AND ROADWAY ...

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

    VIEW OF APALACHICOLA RIVER BRIDGE STEEL BRIDGE TRUSS AND ROADWAY AT PIER 3, EAST SIDE, FROM RIVER, FACING WEST - Apalachicola River Bridge, State Route 20 spanning the Apalachicola River, Blountstown, Calhoun County, FL

  16. VIEW OF APALACHICOLA RIVER BRIDGE SPANS 1, 2, AND 3, ...

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

    VIEW OF APALACHICOLA RIVER BRIDGE SPANS 1, 2, AND 3, WEST SIDE, FROM SOUTH SHORE OF RIVER (LIBERTY COUNTY SIDE), FACING NORTH - Apalachicola River Bridge, State Route 20 spanning the Apalachicola River, Blountstown, Calhoun County, FL

  17. Radioactive effluents in Savannah River

    SciTech Connect

    Winn, W.G.

    1991-11-27

    During 1990, low-level radiometric studies of the Savannah River continued to distinguish between effluent contributions from Plant Vogtle and the Savannah River Site. Measurements of these radioactive effluents are of mutual interest to both institutions, as they can address disturbing trends before they become health and legal concerns. The Environmental Technology Section (ETS) has conducted radiometric studies of Plant Vogtle since late 1986, prior to its startup. The plant has two 1100 MWe pressurized water reactors developed by Westinghouse. Unit 1 started commercial operations in June 1987, and Unit 2 began in May 1989. During powered operations, ETS has routinely detected neutron-activated isotopes in controlled releases but all activities have been several orders of magnitude below the DOE guide values. In 1990, processing improvements for Vogtle effluents have yielded even lower activities in the river. The Vogtle release data and the ETS measurements have tracked well over the past four years.

  18. Nelson River and Hudson Bay

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Rivers that empty into large bodies of water can have a significant impact on the thawing of nearshore winter ice. This true-color Moderate Resolution Imaging Spectroradiometer (MODIS) image from May 18, 2001, shows the Nelson River emptying spring runoff from the Manitoba province to the south into the southwestern corner of Canada's Hudson Bay. The warmer waters from more southern latitudes hasten melting of ice near the shore, though some still remained, perhaps because in shallow coastal waters, the ice could have been anchored to the bottom. High volumes of sediment in the runoff turned the inflow brown, and the rim of the retreating ice has taken on a dirty appearance even far to the east of the river's entrance into the Bay. The sediment would have further hastened the melting of the ice because its darker color would have absorbed more solar radiation than cleaner, whiter ice. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  19. Grays River Watershed Geomorphic Analysis

    SciTech Connect

    Geist, David R

    2005-04-30

    This investigation, completed for the Pacific Northwest National Laboratory (PNNL), is part of the Grays River Watershed and Biological Assessment commissioned by Bonneville Power Administration under project number 2003-013-00 to assess impacts on salmon habitat in the upper Grays River watershed and present recommendations for habitat improvement. This report presents the findings of the geomorphic assessment and is intended to support the overall PNNL project by evaluating the following: The effects of historical and current land use practices on erosion and sedimentation within the channel network The ways in which these effects have influenced the sediment budget of the upper watershed The resulting responses in the main stem Grays River upstream of State Highway 4 The past and future implications for salmon habitat.

  20. Harlem River water quality improvement

    NASA Astrophysics Data System (ADS)

    Wang, J.

    2011-12-01

    Harlem River is a navigable tidal strait, which flows 8 miles connecting the Hudson River and the East River. In wet weather condition, there is untreated sewage mixed rainfall discharged to the river directly at CSO's discharge point. These raw sewer contain bacteria such as Fecal Coliform, E. Coli, Entercocci those can cause illness. There are total 37 CSOs dicharge point along the Harlem River. Water samples were collected from five sites and analyzed on a weekly basis in spring from March to May 2011, and on a monthly basis in July and August. Results showed that ammonia concentrations were ranged from 0.25 to 2.2 mg/L, and there was an increased pattern in summer when temperature increases; soluble reactive phosphorus (SRP) ranged from 0.04 to 0.2 mg/L; total P (TP) ranged from 0.03 to 0.7 mg/L; organic P (OP) ranged from 0.006 to 0.5 mg/L. In rain storm (wet weather condition), untreated sewer discharged into the river with distinguished higher nutrient concentrations (ammonia=2.9 mg/L, TP=3.1 mg/L, OP=2.9 mg/L) and extremely high bacteria levels (fecal coliform-millions, countless colonies; E. Coli-thousands). Results showed spatial variations among the five sites, seasonal variations from spring to summer, and variations under different weather conditions (temperature, storms). The raw sewer discharge during heavy rainstorms resulted in higher nutrients and bacteria levels, and the water quality was degraded.

  1. River Sinuosity Classification - The method

    NASA Astrophysics Data System (ADS)

    Petrovszki, J.; Székely, B.; Timár, G.

    2012-04-01

    We introduced a new evaluation method, the classification of multiple window-size based sinuosity spectrum. If the river is long enough for the analysis, the classification could be as useful, as the sinuosity spectrum, but sometimes it is more straightforward. Furthermore, for the classification, we did not need the main parameters of the river, e.g. the bankfull discharge. Each sinuosity calculation that was performed for a given window size, has been considered as one band (one channel) of a multichannel "image". Then, the sinuosity spectrums became multichannel images are of size 1 X N where N represents the length of the actual river in pixels. Using this multichannel input unsupervised ISOCLASS classification was carried out on these data, using ER Mapper software. The requested number of classes was set to 5. The results of the sinuosity calculations are scalars. Earlier, it was a subjective decision to divide the sinuosity values into the categories (low, medium-low, medium, medium-high, and high), while the new method provides integer numbers (1 to 5) itself. These numbers are calculated from the sinuosity values, but are not equal to them. Analysing the results of the classification, it is important to note that the method typically splits the river course into contiguous sections that belong to the same class. Boundaries of these classes can be considered as points of considerable change in the river course, because the method uses statistically relevant amount of data of the river course in a robust way to detect changes. Some specific classes or their boundaries seem to be correlated to tectonically active zones. The research is made in the frame of project OTKA-NK83400 (SourceSink Hungary). The European Union and the European Social Fund also have provided financial support to the project under the grant agreement no. TÁMOP 4.2.1./B-09/1/KMR-2010-0003.

  2. Chalk Dust & the Hands of Time

    ERIC Educational Resources Information Center

    Hanson, Chad

    2005-01-01

    It was Friday, right before Memorial Day weekend. The Social Science Division was quiet. The author was standing in his office when he realized he had finished his 10th year of teaching a week before. He pondered the milestone for a minute. Like most faculty, he has floor-to-ceiling bookshelves in his office. His favorite shelf sits at the top of…

  3. Substructure Main Bridge, River Piers A & V ...

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

    Substructure - Main Bridge, River Piers A & V - Huey P. Long Bridge, Spanning Mississippi River approximately midway between nine & twelve mile points upstream from & west of New Orleans, Jefferson, Jefferson Parish, LA

  4. Columbia River Impact Evaluation Plan

    SciTech Connect

    Weiss, S.G.

    1994-03-01

    A preliminary impact evaluation was conducted to assess the adequacy of existing data and proposed data collection programs for evaluating cumulative health and environmental impacts to the Columbia River due to past practices at the Hanford Site. The results of this evaluation were used to develop this plan to ensure collection of sufficient data for adequate characterization of the Columbia River along the 100 Area for CERCLA purposes. The evaluation used to develop the plan is not a risk assessment; the plan presented here is only a mechanism to collect additional data to support a future risk assessment.

  5. Arctic River Mobility: A Baseline Assessment

    NASA Astrophysics Data System (ADS)

    Rowland, J. C.; Wilson, C. J.; Brumby, S. P.; Pope, P. A.

    2009-12-01

    In many arctic river systems, permafrost and the presence of frozen floodplain materials provides a significant source of bank cohesion. Due to this cohesion, permafrost may play an important control of arctic river mobility and meandering dynamics. Whether changes in the rates of permafrost thawing has had or will have as significant a geomorphic impact on arctic river meandering as has already been observed for arctic coastline retreat, lake size and distribution, and hillslope stability is at present an unanswered question. The potential impact of climate driven changes in arctic river meandering has important implications for river planform morphology, floodplain dynamics, river ecology, and the export of carbon and nutrients to coastal oceans. We present results of remote sensing analysis of river mobility for the Yukon River in Alaska and sections of the Siberian Rivers including the Lena, the Kolyma and the Indigirka Rivers. Comparisons of river location at successive intervals in time were conducted using Landsat imagery archives and higher resolution aerial photographs and satellite imagery. Extraction of river channel locations was accomplished using the GeniePro automated feature extraction software. Over the period of Landsat coverage (mid-1980s to present) arctic rivers show limited to no movement at the resolution of the Landsat data (30 m per pixel). On the Yukon Flats regions of the Yukon River, the most mobile sections of the river have migration rates comparable to reach-average values reported for temperate rivers; given that large portions of the Yukon display no detectable movement, reach-averaged values are far less than observed in temperate systems. Field inspection of areas of high erosion along the Yukon River indicate that erosional processes associated with the thermal degradation of permafrost play a dominant role in many of these areas. Thermal niching and large scale bank collapse due to undercutting play a large role in bank erosion

  6. 33 CFR 117.911 - Atlantic Intracoastal Waterway, Little River to Savannah River.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., Little River to Savannah River. 117.911 Section 117.911 Navigation and Navigable Waters COAST GUARD... § 117.911 Atlantic Intracoastal Waterway, Little River to Savannah River. (a) General. Public vessels of... List of CFR Sections Affected, which appears in the Finding Aids section of the printed volume and...

  7. 33 CFR 117.911 - Atlantic Intracoastal Waterway, Little River to Savannah River.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., Little River to Savannah River. 117.911 Section 117.911 Navigation and Navigable Waters COAST GUARD... § 117.911 Atlantic Intracoastal Waterway, Little River to Savannah River. (a) General. Public vessels of... Register citations affecting § 117.911, see the List of CFR Sections Affected, which appears in the...

  8. 33 CFR 117.911 - Atlantic Intracoastal Waterway, Little River to Savannah River.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., Little River to Savannah River. 117.911 Section 117.911 Navigation and Navigable Waters COAST GUARD... § 117.911 Atlantic Intracoastal Waterway, Little River to Savannah River. (a) General. Public vessels of... Register citations affecting § 117.911, see the List of CFR Sections Affected, which appears in the...

  9. ALWAYS A RIVER - SUPPLEMENTAL ENVIRONMENTAL EDUCATION CURRICULUM ON THE OHIO RIVER AND WATER GRADES K - 12

    EPA Science Inventory

    This curriculum was developed as a significant component of the project, Always a River: The Ohio River and the American Experience, a six-state collaboration devoted to exploring the historical and cultural development of the Ohio River. The Always a River project is being joint...

  10. 76 FR 22033 - Safety Zone; Red River Safety Zone, Red River, MN

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-20

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AAOO Safety Zone; Red River Safety Zone, Red River, MN AGENCY... Safety Unit Duluth, MN is establishing a temporary safety zone on the Red River, MN. This safety zone is... entering all navigable waters of the Red River in the State of Minnesota north of a line drawn...

  11. 33 CFR 117.353 - Atlantic Intracoastal Waterway, Savannah River to St. Marys River.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., Savannah River to St. Marys River. 117.353 Section 117.353 Navigation and Navigable Waters COAST GUARD....353 Atlantic Intracoastal Waterway, Savannah River to St. Marys River. (a) General. Public vessels of... Friday, except Federal holidays the draw need open only at 7 a.m., 8 a.m. and 5:30 p.m. (c)...

  12. 33 CFR 117.353 - Atlantic Intracoastal Waterway, Savannah River to St. Marys River.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., Savannah River to St. Marys River. 117.353 Section 117.353 Navigation and Navigable Waters COAST GUARD....353 Atlantic Intracoastal Waterway, Savannah River to St. Marys River. (a) General. Public vessels of... Friday, except Federal holidays the draw need open only at 7 a.m., 8 a.m. and 5:30 p.m. (c)...

  13. Rivers Run Through It: Discovering the Interior Columbia River Basin.

    ERIC Educational Resources Information Center

    Davis, Shelley; Wojtanik, Brenda Lincoln; Rieben, Elizabeth

    1998-01-01

    Explores the Columbia River Basin, its ecosystems, and challenges faced by natural resource managers. By studying the basin's complexity, students can learn about common scientific concepts such as the power of water and effects of rain shadows. Students can also explore social-scientific issues such as conflicts between protecting salmon runs and…

  14. Home on the Big River: Great River Habitat Quality Indices

    EPA Science Inventory

    EPA’s Environmental Monitoring and Assessment Program sampled the Upper Mississippi, Missouri and Ohio Rivers from 2004 through 2006 as part of an integrated assessment of ecological condition. We developed fish habitat indices by dividing the components of habitat into four ca...

  15. Columbia River Component Data Evaluation Summary Report

    SciTech Connect

    C.S. Cearlock

    2006-08-02

    The purpose of the Columbia River Component Data Compilation and Evaluation task was to compile, review, and evaluate existing information for constituents that may have been released to the Columbia River due to Hanford Site operations. Through this effort an extensive compilation of information pertaining to Hanford Site-related contaminants released to the Columbia River has been completed for almost 965 km of the river.

  16. Nile River, Lake Nasser, Aswan Dam, Egypt

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Egypt's High Aswan Dam on the Nile River at the first cataracts, Nile River, (24.0N, 33.0E) was completed in 1971 to provide cheap hydroelectric power and to regulate the historically uneven flow of the Nile River. The contrast between the largely base rock desert east of the Nile versus the sand covered desert west of the river and the ancient irrigated floodplain downstream from the damsite is clearly shown.

  17. Floods in the Raccoon River basin, Iowa

    USGS Publications Warehouse

    Heinitz, Albert J.

    1980-01-01

    Evaluation of flood hazards, and the planning, design, and operation of various facilities on flood plains requires information on floods. This report provides information on flood stages and discharges, flood magnitude and frequency, bench mark data, and flood profiles for the Raccoon River and some of its tributaries. Ir covers the Raccoon River, the North Raccoon River to the northern boundary of Sac County and the lower reaches of the Middle and South Raccoon Rivers.

  18. RiverCare: towards self-sustaining multifunctional rivers

    NASA Astrophysics Data System (ADS)

    Augustijn, Denie; Schielen, Ralph; Hulscher, Suzanne

    2014-05-01

    Rivers are inherently dynamic water systems involving complex interactions among hydrodynamics, morphology and ecology. In many deltas around the world lowland rivers are intensively managed to meet objectives like safety, navigation, hydropower and water supply. With the increasing pressure of growing population and climate change it will become even more challenging to reach or maintain these objectives and probably also more demanding from a management point of view. In the meantime there is a growing awareness that rivers are natural systems and that, rather than further regulation works, the dynamic natural processes should be better utilized (or restored) to reach the multifunctional objectives. Currently many integrated river management projects are initiated all over the world, in large rivers as well as streams. Examples of large scale projects in the Netherlands are 'Room for the River' (Rhine), the 'Maaswerken' (Meuse), the Deltaprogramme and projects originating from the European Water Framework Directive (WFD). These projects include innovative measures executed never before on this scale and include for example longitudinal training dams, side channels, removal of bank protection, remeandering of streams, dredging/nourishment and floodplain rehabilitation. Although estimates have been made on the effects of these measures for many of the individual projects, the overall effects on the various management objectives remains uncertain, especially if all projects are considered in connection. For all stakeholders with vested interests in the river system it is important to know how that system evolves at intermediate and longer time scales (10 to 100 years) and what the consequences will be for the various river functions. If the total, integrated response of the system can be predicted, the system may be managed in a more effective way, making optimum use of natural processes. In this way, maintenance costs may be reduced, the system remains more natural

  19. 4. ENVIRONMENT, FROM NORTH, SHOWING RIVER ROAD BRIDGE CARRYING CASSELMAN ...

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

    4. ENVIRONMENT, FROM NORTH, SHOWING RIVER ROAD BRIDGE CARRYING CASSELMAN RIVER ROAD OVER CASSELMAN RIVER, WITH MARYLAND GEOLOGICAL SURVEY STREAM-GAUGING STATION AT NORTHEAST CORNER OF BRIDGE - River Road Bridge, Crossing Casselman River on Casselman River Road, Grantsville, Garrett County, MD

  20. Aerial view of the entire bridge crossing the Tennessee River ...

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

    Aerial view of the entire bridge crossing the Tennessee River looking up river. The swing bridge, when open, permits river navigational traffic to ply the river. Construction of a replacement bridge, to be located 93.27 feet down river, has now started. - Bridgeport Swing Span Bridge, Spanning Tennessee River, Bridgeport, Jackson County, AL