Bioremediation in Fractured Rock: 2. Mobilization of Chloroethene Compounds from the Rock Matrix          下载免费PDF全文

Allen M. Shapiro  Claire R. Tiedeman  Thomas E. Imbrigiotta  Daniel J. Goode  Paul A. Hsieh  Pierre J. Lacombe  Mary F. DeFlaun  Scott R. Drew  Gary P. Curtis 《Ground water》2018,56(2):317-336

  相似文献   

Positional Accuracy of TIGER 2000 and 2009 Road Networks   总被引：1，自引：0，他引：1  

Paul A. Zandbergen  Drew A. Ignizio  Kathryn E. Lenzer 《Transactions in GIS》2011,15(4):495-519

The Topologically Integrated Geographic Encoding and Referencing (TIGER) data are an essential part of the US Census and represent a critical element in the nation's spatial data infrastructure. TIGER data for the year 2000, however, are of limited positional accuracy and were deemed of insufficient quality to support the 2010 Census. In response the US Census Bureau embarked on the MAF/TIGER Accuracy Improvement Project (MTAIP) in an effort to improve the positional accuracy of the database, modernize the data processing environment and improve cooperation with partner agencies. Improved TIGER data were released for the entire US just before the 2010 Census. The current study characterizes the positional accuracy of the TIGER 2009 data compared with the TIGER 2000 data based on selected road intersections. Three US counties were identified as study areas and in each county 100 urban and 100 rural sample locations were selected. Features in the TIGER 2000 and 2009 data were compared with reference locations derived from high resolution natural color orthoimagery. Results indicate that TIGER 2009 data are much improved in terms of positional accuracy compared with the TIGER 2000 data, by at least one order of magnitude across urban and rural areas in all three counties for most accuracy metrics. TIGER 2009 is consistently more accurate in urban areas compared with rural areas, by a factor of at least two for most accuracy metrics. Despite the substantial improvement in positional accuracy, large positional errors of greater than 10 m are relatively common in the TIGER 2009 data, in most cases representing remnant segments of minor roads from older versions of the TIGER data. As a result, based on the US Census Bureau's suggested accuracy metric, the TIGER 2009 data meet the accuracy expectation of 7.6 m for two of the three urban areas but for none of the three rural areas. The suggested metric is based on the National Standard for Spatial Data Accuracy (NSSDA) protocol and was found to be very sensitive to the presence of a small number of very large errors. This presents challenges during attempts to characterize the accuracy of TIGER data or other spatial data using this protocol.  相似文献   

The shaping of planetary nebula Sh 2−188 through interactionwith the interstellar medium     

C. J. Wareing  T. J. O'Brien  Albert A. Zijlstra  K. B. Kwitter  J. Irwin  N. Wright  R. Greimel  J. E. Drew 《Monthly notices of the Royal Astronomical Society》2006,366(2):387-396

  相似文献   

The component star masses in RW Tri     

T. Poole  K. O. Mason  G. Ramsay  J. E. Drew  R. C. Smith 《Monthly notices of the Royal Astronomical Society》2003,340(2):499-508

  相似文献   

The INT Photometric Hα Survey of the Northern Galactic Plane (IPHAS)     

Janet E. Drew  R. Greimel  M. J. Irwin  A. Aungwerojwit  M. J. Barlow  R. L. M. Corradi  J. J. Drake  B. T. Gänsicke  P. Groot  A. Hales  E. C. Hopewell  J. Irwin  C. Knigge  P. Leisy  D. J. Lennon  A. Mampaso  M. R. W. Masheder  M. Matsuura  L. Morales-Rueda  R. A. H. Morris  Q. A. Parker  S. Phillipps  P. Rodriguez-Gil  G. Roelofs  I. Skillen  J. L. Sokoloski  D. Steeghs  Y. C. Unruh  K. Viironen  J. S. Vink  N. A. Walton  A. Witham  N. Wright  A. A. Zijlstra  A. Zurita 《Monthly notices of the Royal Astronomical Society》2005,362(3):753-776

  相似文献   

The link between volcanism and plutonism in epizonal magma systems; high-precision U–Pb zircon geochronology from the Organ Mountains caldera and batholith,New Mexico     

Matthew Rioux  G. Lang Farmer  Samuel A. Bowring  Kathleen M. Wooton  Jeffrey M. Amato  Drew S. Coleman  Philip L. Verplanck 《Contributions to Mineralogy and Petrology》2016,171(2):13

  相似文献   

Impacts of Oyster Reef Restoration on Primary Productivity and Nutrient Dynamics in Tidal Creeks of the North Central Gulf of Mexico     

Rochelle Plutchak  Kelly Major  Just Cebrian  C. Drew Foster  Mary-Elizabeth C. Miller  Andrea Anton  Kate L. Sheehan  Kenneth L. HeckJr.  Sean P. Powers 《Estuaries and Coasts》2010,33(6):1355-1364

The ability of oysters to remove large quantities of particulates from the water column, thereby potentially improving water quality, has been cited as one of the reasons for oyster reef restoration. However, this ability has not yet been effectively demonstrated in the field. As part of the Alabama Oyster Reef Restoration Project, this study was designed to assess impacts of restored eastern oyster (Crassostrea virginica) reefs on primary production, nutrient dynamics, and water quality in shallow tidal creeks. Using a Before–After-Control–Impact (BACI) design, we monitored tidal creeks around Dauphin Island, AL, for changes induced by the introduction of oyster reefs. Reef placement resulted in increased ammonium (NH₄⁺) in two of the three experimental creeks. Interestingly, oyster reefs did not seem to reduce water column particulates or have an impact on phytoplankton or microphytobenthic biomass or productivity. We do not believe that our data discount the importance and/or usefulness of oysters in modifying the water column. Rather, we acknowledge that it is difficult to detect these impacts/environmental services in this type of system (i.e., a tidal creek system), because they seem to be very localized and short-lived (i.e., not ecologically relevant on a creek-wide scale). This study highlights the need to consider location and habitat in planning oyster restoration projects. Also, it demonstrates that the types, magnitudes, and spatial extent of changes in ecosystem services that should be expected after reef restoration might need to be re-evaluated.  相似文献   

The Potential Influence of ClO·O2 on Stratospheric Ozone Depletion Chemistry     

Drew T. Shindell 《Journal of Atmospheric Chemistry》1997,26(3):323-335

The inability to explain the observedoxygen suppression of chlorine photosensitized ozoneloss remains a gap in our understanding of thephotochemistry responsible for depletion of thestratospheric ozone layer. It has been suggested thatthe presence of a weakly bound ClO·O₂complexcould explain this effect. The existence of thiscomplex would alter the chlorine budget of thestratosphere, perhaps reducing the chlorine availablefor catalytic ozone destruction. On the other hand,the chemistry of ClO·O₂ provides two newpathwaysfor ClO dimer formation, which could increase the rateof catalytic ozone loss. In this paper, we constrainthe kinetic rate system of ClO·O₂ tomatch themeasured Cl_y budget. It is shown thatClO·O₂cannot be both fairly stable and rapidly form the ClOdimer, or the resulting partitioning of chlorinebecomes incompatible with observations of both ClO andtotal available chlorine. These constraints allow thateither: (1) the ClO·O₂ is fairly stable,but doesnot significantly enhance ClO dimer formation andtherefore has a negligible effect on ozone loss rates,or (2) the ClO·O₂ complex is only veryweaklystable, but does rapidly form the ClO dimer, andtherefore can influence stratospheric ozone depletion.Even at the ClO·O₂ mixing ratios allowedunderthe assumption of weak stability, 0.1 to 0.2 ppbv,significant ozone loss rate enhancements werecalculated. Of course, the chlorine budget constraintalso allows for a thirdpossibility; that ClO·O₂ is neither verystablenor forms Cl₂O₂ very rapidly. Measuredlimits on the reaction rates for ClO·O₂to form the ClO dimer would greatly aid the resolution of thisissue. Since the uncertainties aboutClO·O₂chemistry are so large, a potential role forClO·O₂ in stratospheric ozone loss cannotbe ruled out at this time.  相似文献   

Physiology of Laminaria   总被引：1，自引：0，他引：1  

Nichola J.  Conolly Edward A.  Drew 《Marine Ecology》1985,6(4):299-320

Abstract. Sporophytes of Laminaria digitata and L. saccharina were collected from the shore at different times of year. Intact sporophytes of both species, and discs cut from L. digitata lamina tissue were maintained for several weeks in laboratory cultures under various nitrate, phosphate, temperature and daylength regimes. Substrate-saturated uptake rates of approximately 24 μgN g dry weight^-1 h^-1 from 20 μM nitrate and 8 μgP g dry weight^-1 h^-1 from 10 μM phosphate were more than sufficient to account for internal nitrogen and phosphorus accumulation. Other nitrogen sources - nitrite, ammonium and urea - were also taken up, independently of each other, and supported growth. During the late spring decline of ambient nutrient levels, when growth rates on the shore also decline markedly, enrichment with nitrate (15 μM) and phosphate (3μ) together prevented this decline and also maintained peak photosynthetic rates (net photosynthesis = 10.4 μlO₂ cm^-2 h^-1) which otherwise dropped to 4.5 μO₂ cm^-2 h^-1 over 47 days at ambient nutrient levels (0.5 μM nitrate and phosphate). Slow summer growth rates in June/July were enhanced to greater than spring peak values by combined nitrate (7.5 μM) and phosphate (1.8 μM) enrichment; neither was sufficient alone, although the individual nutrients were accumulated internally. A lesser, but significant enhancement was also achieved in September. In midwinter, nutrient enhancement itself (10.5 μM nitrate and 3.0 μM phosphate) had a small effect on growth rates only if summer water temperature (15°C) was used, but the dramatic effect of an increased photoperiod (7.5 to 17.5 h) was in excess of that expected for the increased radiant energy available. This was found to be due, at least in L. digitaia discs, to the re-establishment of a surface meristoderm in the dormant winter tissue; this was particularly active with high phosphate supply. Growth of the new lamina in January on the shore was much reduced if the old lamina was removed, although the time of initiation of new growth remained unchanged. In the laboratory, the old lamina was found to be a source of nitrogen for new lamina but not of fixed carbon or phosphorus. New lamina photosynthesis, manifest as mannitol accumulation, was directly proportional to phosphate supply up to at least 7.5 μM phosphate. Mannitol accumulation was then suppressed by a nitrate supply above 12 um, presumably by diversion of fixed carbon to other biosynthetic pathways.  相似文献   

Spectroscopic investigation of U(VI) sorption at the calcite-water interface     

Evert J. Elzinga  C. Drew Tait  Kirk D. Rector  David E. Morris 《Geochimica et cosmochimica acta》2004,68(11):2437-2448

  相似文献