Extremely alkaline (pH > 12) ground water hosts diverse microbial community     

Roadcap GS  Sanford RA  Jin Q  Pardinas JR  Bethke CM 《Ground water》2006,44(4):511-517

Chemically unusual ground water can provide an environment for novel communities of bacteria to develop. Here, we describe a diverse microbial community that inhabits extremely alkaline (pH > 12) ground water from the Lake Calumet area of Chicago, Illinois, where historic dumping of steel slag has filled in a wetland. Using microbial 16S ribosomal ribonucleic acid gene sequencing and microcosm experiments, we confirmed the presence and growth of a variety of alkaliphilic beta-Proteobacteria, Bacillus, and Clostridium species at pH up to 13.2. Many of the bacterial sequences most closely matched those of other alkaliphiles found in more moderately alkaline water around the world. Oxidation of dihydrogen produced by reaction of water with steel slag is likely a primary energy source to the community. The widespread occurrence of iron-oxidizing bacteria suggests that reduced iron serves as an additional energy source. These results extend upward the known range of pH tolerance for a microbial community by as much as 2 pH units. The community may provide a source of novel microbes and enzymes that can be exploited under alkaline conditions.  相似文献   

The significance of dilution in evaluating possible impacts of wastewater discharges from large cruise ships   总被引：1，自引：0，他引：1  

Loehr LC  Beegle-Krause CJ  George K  McGee CD  Mearns AJ  Atkinson MJ 《Marine pollution bulletin》2006,52(6):681-688

In response to public concerns about discharges from large cruise ships, Alaska's Department of Environmental Conservation (ADEC) sampled numerous effluents in the summer of 2000. The data showed that basic marine sanitation device (MSD) technology for black water (sewage) was not performing as expected. Untreated gray water had high levels of conventional pollutants and surprisingly high levels of bacteria. Both black water and gray water discharges sometimes exceeded state water quality standards for toxicants. The state convened a Science Advisory Panel (the Panel) to evaluate impacts associated with cruise ship wastewater discharges. The effluent data received wide media coverage and increased public concerns. Consequently, legislative decisions were made at the State and Federal level, and regulations were imposed before the Panel completed its evaluation. The Panel demonstrated that following the rapid dilution from moving cruise ships, the effluent data from the Summer of 2000 would not have exceeded water quality standards, and environmental effects were not expected.  相似文献   

Determination of particulate organic carbon (POC) in seawater: The relative methodological importance of artificial gains and losses in two glass-fiber-filter-based techniques   总被引：1，自引：0，他引：1  

Robert Turnewitsch  Barbara M. Springer  Konstadinos Kiriakoulakis  Juan Carlos Vilas  Javier Arístegui  George Wolff  Florian Peine  Stephan Werk  Gerhard Graf  Joanna J. Waniek 《Marine Chemistry》2007,105(3-4):208-228

Particulate matter in aquatic systems is an important vehicle for the transport of particulate organic carbon (POC). Its accurate measurement is of central importance for the understanding of marine carbon cycling. Previous work has shown that GF/F-filter-based bottle-sample-derived concentration estimates of POC are generally close to or higher than large-volume in-situ-pump-derived values (and in some rare cases in subzero waters are up to two orders of magnitude higher). To further investigate this phenomenon, water samples from the surface and mid-water Northeast Atlantic and the Baltic Sea were analyzed. Our data support a bias of POC concentration estimates caused by adsorption of nitrogen-rich dissolved organic material onto GF/F filters. For surface-ocean samples the mass per unit area of exposed filter and composition of adsorbed material depended on the filtered volume. Amounts of adsorbed OC were enhanced in the surface ocean (typically 0.5 μmol cm^− 2 of exposed filter) as compared to the deep ocean (typically 0.2 μmol cm^− 2 of exposed filter). These dependencies should be taken into account for future POC methodologies. Bottle/pump differences of samples that were not corrected for adsorption were higher in the deep ocean than in the surface ocean. This discrepancy increased in summer. It is shown that POC concentration estimates that were not corrected for adsorption depend not only on the filtered volume, true POC concentration and mass of adsorbed OC, but also on the filter area. However, in all cases we studied, correction for adsorption was important, but not sufficient, to explain bottle/pump differences. Artificial formation of filterable particles and/or processes leading to filterable material being lost from and/or missed by sample-processing procedures must be considered. It can be deduced that the maximum amounts of POC and particulate organic nitrogen (PON) that can be artificially formed per liter of filtered ocean water are  3–4 μM OC (5–10% of dissolved OC) and  0.2–0.5 μM ON (2–10% of dissolved ON), respectively. The relative sensitivities of bottle and pump procedures, and of surface- and deep-ocean material, to artificial particle formation and the missing/losing of material are evaluated. As present procedures do not exist to correct for all possible biasing effects due to artificial particle formation and/or miss/loss of filterable material, uncertainties of filtration-based estimates of POC concentrations need further testing. The challenge now is to further constrain the magnitude of the biasing effects that add to the adsorption effect to reduce the uncertainties of estimates of POC concentrations, inventories and fluxes in the ocean.  相似文献   

Implementation of the ground level enhancement alert software at NMDB database     

Helen Mavromichalaki  George Souvatzoglou  Christos Sarlanis  George Mariatos  Athanasios Papaioannou  Anatoly Belov  Eugenia Eroshenko  Victor Yanke 《New Astronomy》2010,15(8):744-748

The European Commission is supporting the real-time database for high-resolution neutron monitor measurements (NMDB) as an e-Infrastructures project in the Seventh Framework Programme in the Capacities section. The realization of the NMDB will provide the opportunity for several applications most of which will be implemented in real-time. An important application will be the establishment of an Alert signal when dangerous solar particle events are heading to the Earth, resulting into a ground level enhancement (GLE) registered by neutron monitors (NMs). The cosmic ray community has been occupied with the question of establishing such an Alert for many years and recently several groups succeeded in creating a proper algorithm capable of detecting space weather threats in an off-line mode. A lot of original work has been done to this direction and every group working in this field performed routine runs for all GLE cases, resulting into statistical analyses of GLE events. The next step was to make this algorithm as accurate as possible and most importantly, working in real-time. This was achieved when, during the last GLE observed so far, a real-time GLE Alert signal was produced. In this work, the steps of this procedure as well as the functionality of this algorithm for both the scientific community and users are being discussed. Nevertheless, the transition of the Alert algorithm to the NMDB is also being discussed.  相似文献   

Interaction between groundwater, the hyporheic zone and a Chalk stream: a case study from the River Lambourn, UK     

David J. Allen  W. George Darling  Daren C. Gooddy  Daniel J. Lapworth  Andrew J. Newell  Ann T. Williams  Debbie Allen  Corinna Abesser 《Hydrogeology Journal》2010,18(5):1125-1141

Understanding the processes controlling groundwater/surface-water interaction is essential for effective resource management and for protecting sensitive ecosystems. Through intensive monitoring of Chalk groundwater, shallow gravel groundwater and surface water in the River Lambourn, UK, using a combination of hydrochemical and hydrophysical techniques, a complex pattern of interactions has been elucidated. The river is broadly in hydraulic contact with the streambed sediments and adjacent gravels and sands, but these deposits are mainly hydraulically separate from the underlying Chalk at the site. The hydraulic relationship between the river and underlying alluvium is variable, involving components of groundwater flow both parallel and transverse to the river and with both effluent and influent behaviour seen. While the gravel aquifer is significant in controlling groundwater/surface-water interaction, its importance as a route for flow down the catchment is likely to be modest compared with river discharge. The hydrological complexity revealed in a geological setting typical of lowland UK Chalk streams has implications both for investigation methods and for management such as in the setting of environmental objectives in the European Water Framework Directive.  相似文献   

The Spectral Irradiance Monitor (SIM): Early Observations     

Gary Rottman  Jerald Harder  Juan Fontenla  Thomas Woods  Oran R. White  George M. Lawrence 《Solar physics》2005,230(1-2):205-224

This paper presents and interprets observations obtained by the Spectral Irradiance Monitor (SIM) on the Solar Radiation and Climate Experiment (SORCE) over a time period of several solar rotations during the declining phase of solar cycle 23. The time series of visible and infrared (IR) bands clearly show significant wavelength dependence of these variations. At some wavelengths the SIM measurements are qualitatively similar to the Mg II core-to-wing ratio, but in the visible and IR they show character similar to the Total Solar Irradiance (TSI) variations. Despite this overall similarity, different amplitudes, phases, and temporal features are observed at various wavelengths. The TSI can be explained as a complex sum of the various wavelength components. The SIM observations are interpreted with the aid of solar images that exhibit a mixture of solar activity features. Qualitative analysis shows how the sunspots, faculae, plage, and active network provide distinct contributions to the spectral irradiance at different wavelengths, and ultimately, how these features combine to produce the observed TSI variations. Most of the observed variability appears to be qualitatively explained by solar surface features related directly to the magnetic activity.  相似文献   

Storm runoff and sediment losses from forest clearcutting and stand re‐establishment with best management practices in East Texas,USA     

Matthew W. McBroom  R. Scott Beasley  Mingteh Chang  George G. Ice 《水文研究》2008,22(10):1509-1522

Nine small (2·5 ha) and four large (70–135 ha) watersheds were instrumented in 1999 to evaluate the effects of intensive silvicultural practices with best management practices (BMPs) on runoff and stream water quality in the Western Gulf Coastal Plain of East Texas, USA. Two treatments were implemented in 2002: a conventional treatment with clearcutting and herbicide site preparation, and an intensive treatment that added subsoiling, fertilization and a release herbicide application. Watershed effects were compared with results from a previously conducted study on the same watersheds in 1981, in which two combinations of harvesting and mechanical site preparation without BMPs were evaluated. Due to the reduction in evapotranspirational demand, total storm runoff increased on all six treated small watersheds following harvest by 0·94 to 13·73 cm in 2003. Runoff increases were not statistically significant on the treated large watersheds. Total first‐year sediment loss was significantly greater on two of the conventional and one of the intensive small watersheds. The greatest first‐year increase was 540·1 kg ha^?1, only one‐fifth of that observed on these watersheds from shearing and windrowing without BMPs in 1981. First‐year sediment loss was significantly greater on the intensive large watershed following harvest, but not on the conventional large watershed. These data suggest that BMPs are very effective in reducing potential water quality impacts from intensive silvicultural practices. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

The Spectral Irradiance Monitor: Measurement Equations and Calibration   总被引：2，自引：0，他引：2  

Jerald W. Harder  Juan Fontenla  George Lawrence  Thomas Woods  Gary Rottman 《Solar physics》2005,230(1-2):169-204

The Spectral Irradiance Monitor (SIM) is a satellite-borne spectrometer aboard the Solar Radiation and Climate Experiment (SORCE) that measures solar irradiance between 200 and 2700 nm. This instrument employs a Fèry prism as a dispersing element, an electrical substitution radiometer (ESR) as the primary detector, and four additional photodiode detectors for spectral scanning. Assembling unit level calibrations of critical components and expressing the sensitivity in terms of interrelated measurement equations supplies the instrument's radiant response. The calibration and analysis of the spectrometer's dispersive and transmissive properties, light aperture metrology, and detector characteristics provide the basis for these measurement equations. The values of critical calibration parameters, such as prism and detector response degradation, are re-measured throughout the mission to correct the ground-based calibration.  相似文献   

The 2dF Galaxy Redshift Survey: correlation with the ROSAT-ESO flux-limited X-ray galaxy cluster survey     

Matt Hilton  Chris Collins  Roberto De Propris  Ivan K. Baldry  Carlton M. Baugh  Joss Bland-Hawthorn  Terry Bridges  Russell Cannon  Shaun Cole  Matthew Colless  Warrick J. Couch  Gavin B. Dalton  Simon P. Driver  George Efstathiou  Richard S. Ellis  Carlos S. Frenk  Karl Glazebrook  Carole A. Jackson  Ofer Lahav  Ian Lewis  Stuart Lumsden  Steve J. Maddox  Darren Madgwick  Peder Norberg  John A. Peacock  Bruce A. Peterson  Will Sutherland  Keith Taylor 《Monthly notices of the Royal Astronomical Society》2005,363(2):661-674

  相似文献   

Boltzmann Equilibrium of Endothermic Heavy Nuclear Synthesis in the Universe and a Quark Relation to the Magic Numbers     

Heinrich Hora  George H. Miley  Frederick Osman 《Astrophysics and Space Science》2005,298(1-2):247-253

As laser–plasma interactions access ever-increasing ranges of plasma temperatures and densities, it is interesting to consider whether they will some day shed light on questions concerning nuclear synthesis. One such open question is the process of endothermic nuclear synthesis for elements with A > 60, thought to have taken place at a point in time during the big bang, or currently in supernovae. We present an explanation based on a Boltzmann equilibrium condition, in combination with the change of the Fermi-statistics from the relativistic branch for hadrons from higher than nuclear densities to the lower density subrelativistic branch. The Debye length confinement of nuclei breaks down at the relativistic change, thus leading to the impossibility of nucleation of the quark-gluon state at higher than nuclear densities. Taking the increment for the proton number Z as Z′ = 10 of the measured standard abundance distribution (SAD) of the elements for a Boltzmann probability for heavy element synthesis, a sequence 3 ⁿ was found with the exponent n for the sequence of the magic numbers. The jump between the magic numbers 20 and 28 does not need then the usual spin-orbit explanation.  相似文献