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Sample records for marine pore waters

  1. Development and application of a marine sediment pore-water toxicity test using Ulva fasciata zoospores

    USGS Publications Warehouse

    Hooten, Russell L.; Carr, R. Scott

    1998-01-01

    An acute (96 h) pore-water toxicity test protocol using germination and growth of Ulva fasciatazoospores as endpoints was developed to test the toxicity of marine and estuarine sediment pore-water samples. Tests with an organic toxicant (sodium dodecyl sulfate; SDS), three metals (Cd, Cu, and Zn), and ammonia (NH3) were conducted to determine zoospore sensitivity. Zoospore germination and gametophyte growth were as sensitive to SDS as sea urchin (Arbacia punctulata) fertilization and embryological development. Zoospore sensitivity to metals was greater than or comparable to that of adult macroalgae. Zoospores were less sensitive to NH3than were other commonly used toxicity test organisms. Test results using this algal assay with sediment pore-water samples with high NH3 concentrations were compared with results from sea urchin fertilization and embryological development tests for the same samples. Ulva fasciatazoospore germination was not affected by samples with high NH3 concentrations that were toxic in both sea urchin tests. Zoospore tolerance of NH3 and sensitivity to other contaminants indicate that their response may be useful in toxicity identification evaluation studies with pore-water samples that contain high concentrations of unionized NH3.

  2. Development and application of a marine sediment pore-water toxicity test using Ulva fasciata zoospores

    SciTech Connect

    Hooten, R.L.; Carr, R.S.

    1998-01-01

    An acute (96 h) pore-water toxicity test protocol using germination and growth of Ulva fasciata zoospores as endpoints was developed to test the toxicity of marine and estuarine sediment pore-water samples. Tests with an organic toxicant (sodium dodecyl sulfate; SDS), three metals (Cd, Cu, and Zn), and ammonia (NH{sub 3}) were conducted to determine zoospore sensitivity. Zoospore germination and gametophyte growth were as sensitive to SDS as sea urchin (Arbacia punctulata) fertilization and embryological development. Zoospore sensitivity to metals was greater than or comparable to that of adult macroalgae. Zoospores were less sensitive to NH{sub 3} than were other commonly used toxicity test organisms. Test results using this algal assay with sediment pore-water samples with high NH{sub 3} concentrations were compared with results from sea urchin fertilization and embryological development tests for the same samples. Ulva fasciata zoospore germination was not affected by samples with high NH{sub 3} concentrations that were toxic in both sea urchin tests. Zoospore tolerance of NH{sub 3} and sensitivity to other contaminants indicate that their response may be useful in toxicity identification evaluation studies with pore-water samples that contain high concentrations of unionized NH{sub 3}.

  3. Variations of marine pore water salinity and chlorinity in Gulf of Alaska sediments (IODP Expedition 341)

    NASA Astrophysics Data System (ADS)

    März, Christian; Mix, Alan C.; McClymont, Erin; Nakamura, Atsunori; Berbel, Glaucia; Gulick, Sean; Jaeger, John; Schneider (LeVay), Leah

    2014-05-01

    Pore waters of marine sediments usually have salinities and chlorinities similar to the overlying sea water, ranging around 34-35 psu (Practical Salinity Units) and around 550 mM Cl-, respectively. This is because these parameters are conservative in the sense that they do not significantly participate in biogeochemical cycles. However, pore water studies carried out in the frame of the International Ocean Discovery Program (IODP) and its predecessors have shown that salinities and chlorinities of marine pore waters can substantially deviate from the modern bottom water composition in a number of environmental settings, and various processes have been suggested to explain these phenomena. Also during the recent IODP Expedition 341 that drilled five sites in the Gulf of Alaska (Northeast Pacific Ocean) from the deep Surveyor Fan across the continental slope to the glaciomarine shelf deposits, several occurrences of pore waters with salinities and chlorinities significantly different from respective bottom waters were encountered during shipboard analyses. At the pelagic Sites U1417 and U1418 (~4,200 and ~3,700 m water depth, respectively), salinity and chlorinity maxima occur around 20-50 m sediment depth, but values gradually decrease with increasing drilling depths (down to 30 psu in ~600 m sediment depth). While the pore water freshening at depth is most likely an effect of clay mineral dehydration due to increasing burial depth, the shallow salinity and chlorinity maxima are interpreted as relicts of more saline bottom waters that existed in the North Pacific during the Last Glacial Maximum (Adkins et al., 2002). In contrast, the glaciomarine slope and shelf deposits at Site U1419 to U1421 (~200 to 1,000 m water depth) are characterised by unexpectedly low salinitiy and chlorinity values (as low as 16 psu and 295 mM Cl-, respectively) already in very shallow sediment depths (~10 m), and their records do not show systematic trends with sediment depth. Freshening

  4. Precipitation of ikaite crystals in Antarctic marine sediments: implications from pore water geochemistry

    NASA Astrophysics Data System (ADS)

    Lu, Z.; Kennedy, H.; Rickaby, R. E.; Georg, B.; Shaw, S.; Lennie, A.; Pancost, R. D.

    2008-12-01

    Ikaite is a calcium carbonate hexahydrate (CaCO3•6H20) considered to be stable only at low temperatures. It has been found in form of tufa tower at locations where alkaline water mixes with water masses enriched in calcium (e.g. Ikka Fjord, Mono Lake). Large euhedral single crystals of ikaite were also recovered in marine sediments, associated with organic matter degradation, anaerobic oxidation of methane (AOM) and sulfate reduction. The hydration water in the ikaite crystals were demonstrated to record the oxygen isotope composition of the water from which they precipitated. Such a characteristic may allow using ikaite to reconstruct the ice volume in the past. For this purpose, the controls on its precipitation in the sediment column need to be investigated which is the main goal of this study. U.S. Antarctica Program cruise NBP0703 collected two cores with ikaite crystals at Antarctica Peninsula (Bransfield Strait and Firth of Tay). We determined major cation/anion concentrations, dissolved inorganic carbon (DIC) and δ13C composition of DIC in the pore waters in these two cores. Strong organic matter degradation or AOM in both cores results in quick consumption of sulfate in shallow part of the cores (SMT at around 3m).Rapid build-up of DIC is accompanied by the sharp decrease of dissolved calcium in the top 5m. Large variations were observed in δ13CDIC values (-20‰ to +13‰). The δ13C of ikaite in two cores were distinctive from each other (-19‰ and +4‰) corresponding to the DIC pools at different depths. The down core saturation state of the ikaite was modeled in PHREEQC based on the pore water chemistry, and the results are consistent with carbon isotope data, suggesting that these large crystals very likely formed within a narrow depth interval and a short time period (given high sedimentation rates of 0.5-1 cm/yr in this area).

  5. Stable silicon isotope signatures of marine pore waters - Biogenic opal dissolution versus authigenic clay mineral formation

    NASA Astrophysics Data System (ADS)

    Ehlert, Claudia; Doering, Kristin; Wallmann, Klaus; Scholz, Florian; Sommer, Stefan; Grasse, Patricia; Geilert, Sonja; Frank, Martin

    2016-10-01

    Dissolved silicon isotope compositions have been analysed for the first time in pore waters (δ30SiPW) of three short sediment cores from the Peruvian margin upwelling region with distinctly different biogenic opal content in order to investigate silicon isotope fractionation behaviour during early diagenetic turnover of biogenic opal in marine sediments. The δ30SiPW varies between +1.1‰ and +1.9‰ with the highest values occurring in the uppermost part close to the sediment-water interface. These values are of the same order or higher than the δ30Si of the biogenic opal extracted from the same sediments (+0.3‰ to +1.2‰) and of the overlying bottom waters (+1.1‰ to +1.5‰). Together with dissolved silicic acid concentrations well below biogenic opal saturation, our collective observations are consistent with the formation of authigenic alumino-silicates from the dissolving biogenic opal. Using a numerical transport-reaction model we find that approximately 24% of the dissolving biogenic opal is re-precipitated in the sediments in the form of these authigenic phases at a relatively low precipitation rate of 56 μmol Si cm-2 yr-1. The fractionation factor between the precipitates and the pore waters is estimated at -2.0‰. Dissolved and solid cation concentrations further indicate that off Peru, where biogenic opal concentrations in the sediments are high, the availability of reactive terrigenous material is the limiting factor for the formation of authigenic alumino-silicate phases.

  6. The marine geochemistry of actinium-227: Evidence for its migration through sediment pore water

    SciTech Connect

    Nozaki, Yoshiyuki; Yamada, Masatoshi ); Nikaido, Hirofumi )

    1990-10-01

    {sup 227}Ac with a half life of 21.8 years has a potential utility as a tracer of deep water circulation and mixing studies on time scales less than 100 years. Here the authors present the first measurement of {sup 227}Ac profile in the pore water of Northwest Pacific deep-sea sediment and in the {approximately}10,000 m long water column of Izu-Ogasawara Trench. The results clearly show that {sup 227}Ac is supplied from the sediment to the overlying water through migration in the pore water. The model calculation indicates that the molecular diffusion alone through sediment porewater can support only a half of the standing crop of excess {sup 227}Ac in the water column and the enhanced supply of {sup 227}Ac by particle mixing is necessary to account for the remainder. Thus, bioturbation in the deep sea plays an important role in controlling the flux of some short-lived radionuclides such as {sup 227}Ac and {sup 228}Ra across the sediment-water interface.

  7. Vitamin B1 in marine sediments: pore water concentration gradient drives benthic flux with potential biological implications.

    PubMed

    Monteverde, Danielle R; Gómez-Consarnau, Laura; Cutter, Lynda; Chong, Lauren; Berelson, William; Sañudo-Wilhelmy, Sergio A

    2015-01-01

    Vitamin B1, or thiamin, can limit primary productivity in marine environments, however the major marine environmental sources of this essential coenzyme remain largely unknown. Vitamin B1 can only be produced by organisms that possess its complete synthesis pathway, while other organisms meet their cellular B1 quota by scavenging the coenzyme from exogenous sources. Due to high bacterial cell density and diversity, marine sediments could represent some of the highest concentrations of putative B1 producers, yet these environments have received little attention as a possible source of B1 to the overlying water column. Here we report the first dissolved pore water profiles of B1 measured in cores collected in two consecutive years from Santa Monica Basin, CA. Vitamin B1 concentrations were fairly consistent between the two years ranging from 30 pM up to 770 pM. A consistent maximum at ~5 cm sediment depth covaried with dissolved concentrations of iron. Pore water concentrations were higher than water column levels and represented some of the highest known environmental concentrations of B1 measured to date, (over two times higher than maximum water column concentrations) suggesting increased rates of cellular production and release within the sediments. A one dimensional diffusion-transport model applied to the B1 profile was used to estimate a diffusive benthic flux of ~0.7 nmol m(-2) d(-1). This is an estimated flux across the sediment-water interface in a deep sea basin; if similar magnitude B-vitamin fluxes occur in shallow coastal waters, benthic input could prove to be a significant B1-source to the water column and may play an important role in supplying this organic growth factor to auxotrophic primary producers.

  8. Vitamin B1 in marine sediments: pore water concentration gradient drives benthic flux with potential biological implications

    PubMed Central

    Monteverde, Danielle R.; Gómez-Consarnau, Laura; Cutter, Lynda; Chong, Lauren; Berelson, William; Sañudo-Wilhelmy, Sergio A.

    2015-01-01

    Vitamin B1, or thiamin, can limit primary productivity in marine environments, however the major marine environmental sources of this essential coenzyme remain largely unknown. Vitamin B1 can only be produced by organisms that possess its complete synthesis pathway, while other organisms meet their cellular B1 quota by scavenging the coenzyme from exogenous sources. Due to high bacterial cell density and diversity, marine sediments could represent some of the highest concentrations of putative B1 producers, yet these environments have received little attention as a possible source of B1 to the overlying water column. Here we report the first dissolved pore water profiles of B1 measured in cores collected in two consecutive years from Santa Monica Basin, CA. Vitamin B1 concentrations were fairly consistent between the two years ranging from 30 pM up to 770 pM. A consistent maximum at ~5 cm sediment depth covaried with dissolved concentrations of iron. Pore water concentrations were higher than water column levels and represented some of the highest known environmental concentrations of B1 measured to date, (over two times higher than maximum water column concentrations) suggesting increased rates of cellular production and release within the sediments. A one dimensional diffusion-transport model applied to the B1 profile was used to estimate a diffusive benthic flux of ~0.7 nmol m−2 d−1. This is an estimated flux across the sediment-water interface in a deep sea basin; if similar magnitude B-vitamin fluxes occur in shallow coastal waters, benthic input could prove to be a significant B1-source to the water column and may play an important role in supplying this organic growth factor to auxotrophic primary producers. PMID:26029181

  9. Dissolved N2/Ar Ratios in Sedimentary Pore Waters: A New Twist in Marine Nitrogen Cycle

    NASA Astrophysics Data System (ADS)

    Berelson, W.; Prokopenko, M. G.; Sigman, D. M.; Hammond, D.

    2008-12-01

    The nitrogen cycle is comprised predominantly of biologically mediated pathways, leading to a series of negative feedbacks that stabilize the cycle. Sedimentary denitrification, the major sink in the nitrogen budget, is regulated by the rate of organic carbon rain to the sea floor, as well as oxygen concentrations in overlying bottom waters. The sensitivity of sedimentary denitrification as a negative feedback can be expressed as a ratio between total denitrification (including nitrification sub-cycle) rates integrated over depth (fluxes) and fluxes of remineralized organic carbon out of the sediments, Ndenitr/Coxid_total. We have investigated benthic nitrogen cycling in three, semi-enclosed basins of the California Borderlands: Santa Monica, San Pedro and Santa Barbara located in the regime of seasonal coastal upwelling. Deep water in these basins is separated from the open ocean by sills of various depths, contributing to the low [O2], <1 to10 uM. In this study, we developed a method to sample pore waters for dissolved gas analysis. Ratios between O2, Ar and N2 were determined on extracted pore waters with 1) offline cryogenic extraction and subsequent analysis on Finnigan Delta Plus IRMS with 8 collectors; 2) Membrane Inlet Mass Spectrometery (MIMS). Vertical profiles of pore water N2/Ar in the three basins indicate N2 production at depth horizons which exceed by a factor of 5 to 20 the depth of nitrate penetration supported solely by diffusive flux. At depths of maximum subsurface N2 production, we discovered large pools of intracellular nitrate. The relationship between δ15N and δ18O of nitrate are consistent with the activity of a membrane-bound nitrate reductase affecting the measured isotopic composition of the nitrate pool (Granger et al., 2008, in press). In addition, increases in δ15N of pore water NH4 at this depth suggests that at least some of the nitrate might be used for anaerobic ammonium oxidation. Our model estimates up to 25 % of the measured

  10. Comparison of solid-phase and pore-water approaches for assessing the quality of marine and estuarine sediments

    USGS Publications Warehouse

    Carr, Robert Scott; Chapman, Duane C.

    1992-01-01

    As part of our continuing evaluation of the pore-water approach for assessing sediment quality, we made a series of side-by-side comparisons between the standard 10-day amphipod whole sediment test with the corophiid Grandidierella japonica and a suite of tests using pore water extracted from the same sediments. the pore-water tests evaluated were the sea urchin (Arbacia punctulata) sperm cell test and morphological development assay, the life-cycle test with the polychaete Dinophilus gyrociliatus, and acute exposures of red drum (Sciaenops ocellatus) embryo-larval stages. Sediment and surface microlayer samples were collected from contaminated sites. Whole-sediment, pore-water, and surface microlayer toxicity tests were performed. Pore-water toxicity tests were considerably more sensitive than the whole-sediment amphipod test, which is currently the most sensitive toxicity test now recommended for determining the acceptability of dredged material for open ocean disposal.

  11. Pore water distributions of dissolved copper and copper-complexing ligands in estuarine and coastal marine sediments

    SciTech Connect

    Skrabal, S.A.; Donat, J.R.; Burdige, D.J.

    2000-06-01

    The distributions and seasonal variability of total dissolved Cu (TDCu) and Cu-complexing ligands in sediment pore waters have been investigated at two contrasting sites in the Chesapeake Bay. Two ligand classes, which differ on the basis of the conditional stability constants (K{prime}{sub cond}) of their Cu complexes, were detected at all depths at both sites. For comparison, one pore water profile from a slope station off of the Chesapeake Bay also showed the presence of two ligand classes. Virtually all TDCu fluxing from these sediments is complexed during sediment-water exchange. A relatively small fraction of the TDCu is exchanged as inorganic species, which are widely regarded as the most bioavailable form of Cu. Total ligand concentrations are 15 to >100 times higher in the upper intervals of the pore waters relative to ligand concentrations in the bottom waters of the Chesapeake Bay (30--60 nM), consistent with previous observations of fluxes of these ligands from the sediments to overlying waters. These results suggest that sediments are potentially significant sources of Cu-complexing ligands to the overlying waters of the Chesapeake Bay, and perhaps, other shallow water estuarine and coastal environments. Copper-complexing ligands released from sediment pore waters may play an important role in influencing Cu speciation in overlying waters.

  12. Unraveling signatures of biogeochemical processes and the depositional setting in the molecular composition of pore water DOM across different marine environments

    NASA Astrophysics Data System (ADS)

    Schmidt, Frauke; Koch, Boris P.; Goldhammer, Tobias; Elvert, Marcus; Witt, Matthias; Lin, Yu-Shih; Wendt, Jenny; Zabel, Matthias; Heuer, Verena B.; Hinrichs, Kai-Uwe

    2017-06-01

    Dissolved organic matter (DOM) in marine sediment pore waters derives largely from decomposition of particulate organic matter and its composition is influenced by various biogeochemical and oceanographic processes in yet undetermined ways. Here, we determine the molecular inventory of pore water DOM in marine sediments of contrasting depositional regimes with ultrahigh-resolution mass spectrometry and complementary bulk chemical analyses in order to elucidate the factors that shape DOM composition. Our sample sets from the Mediterranean, Marmara and Black Seas covered different sediment depths, ages and a range of marine environments with different (i) organic matter sources, (ii) balances of organic matter production and preservation, and (iii) geochemical conditions in sediment and water column including anoxic, sulfidic and hypersaline conditions. Pore water DOM had a higher molecular formula richness than overlying water with up to 11,295 vs. 2114 different molecular formulas in the mass range of 299-600 Da and covered a broader range of element ratios (H/C = 0.35-2.19, O/C = 0.03-1.19 vs. H/C = 0.56-2.13, O/C = 0.15-1.14). Formula richness was independent of concentrations of DOC and TOC. Near-surface pore water DOM was more similar to water column DOM than to deep pore water DOM from the same core with respect to formula richness and the molecular composition, suggesting exchange at the sediment-water interface. The DOM composition in the deeper sediments was controlled by organic matter source, selective decomposition of specific DOM fractions and early diagenetic molecule transformations. Compounds in pelagic sediment pore waters were predominantly highly unsaturated and N-bearing formulas, whereas oxygen-rich CHO-formulas and aromatic compounds were more abundant in pore water DOM from terrigenous sediments. The increase of S-bearing molecular formulas in the water column and pore waters of the Black Sea and the Mediterranean Discovery Basin was

  13. Authigenic molybdenum formation in marine sediments: A link to pore water sulfide in the Santa Barbara Basin

    USGS Publications Warehouse

    Zheng, Yen; Anderson, Robert F.; VanGeen, A.; Kuwabara, J.

    2000-01-01

    Pore water and sediment Mo concentrations were measured in a suite of multicores collected at four sites along the northeastern flank of the Santa Barbara Basin to examine the connection between authigenic Mo formation and pore water sulfide concentration. Only at the deepest site (580 m), where pore water sulfide concentrations rise to >0.1 ??M right below the sediment water interface, was there active authigenic Mo formation. At shallower sites (550,430, and 340 m), where pore water sulfide concentrations were consistently <0.05 ??M, Mo precipitation was not occuring at the time of sampling. A sulfide concentration of ???0.1 ??M appears to be a threshold for the onset of Mo-Fe-S co-precipitation. A second threshold sulfide concentration of ???100 ??M is required for Mo precipitation without Fe, possibly as Mo-S or as particle-bound Mo. Mass budgets for Mo were constructed by combining pore water and sediment results for Mo with analyses of sediment trap material from Santa Barbara Basin as well as sediment accumulation rates derived from 210Pb. The calculations show that most of the authigenic Mo in the sediment at the deepest site is supplied by diffusion from overlying bottom waters. There is, however, a non-lithogenic particulate Mo associated with sinking particles that contributes ???15% to the total authigenic Mo accumulation. Analysis of sediment trap samples and supernant brine solutions indicates the presence of non-lithogenic particulate Mo, a large fraction of which is easily remobilized and, perhaps, associated with Mn-oxides. Our observations show that even with the very high flux of organic carbon reaching the sediment of Santa Barbara Basin, active formation of sedimentary authigenic Mo requires a bottom water oxygen concentration below 3 ??M. However, small but measurable rates of authigenic Mo accumulation were observed at sites where bottom water oxygen ranged between 5 and 23 ??M, indicating that the formation of authigenic Mo occured in the

  14. Biogeochemical Weathering Processes in a California Marine Chronosequence as Implicated by Pore-Water Major-Constituent Concentrations and Germanium-Silicon Fractionation

    NASA Astrophysics Data System (ADS)

    Vivit, D.; Schulz, M.; White, A.; Anderson, S.

    2002-12-01

    Silicate weathering processes dominate weathering rates from terraced grassland surfaces in the drainage basin of Wilder Creek (Wilder Ranch State Park, Santa Cruz County, California). This study uses Si, Na, and Ge concentrations from soil pore-water samples taken from a flight of five marine terrace locations in the watershed. A sample-concentration procedure preceded ICP-MS instrumental analysis in order to determine Ge at parts-per-trillion levels. At two sites (Terraces 3 and 4), higher Si and Na concentration levels at the surface or near-surface depths showed the effect of evapo-transpiration. Minimum levels of these two elements occurred from 15 cm to 90 cm deep, and for each the concentration increased gradually with depth. These increases showed that plagioclase dissolution controlled pore-water Si and Na deep in the respective soil profiles. Samples from both Terrace 3 (137 ka in age) and Terrace 4 (139 ka) had Ge/Si ratio values ranging from 0.3 x 10-6 to 5 x 10-6. For both terrace sites, larger ratios occurred in samples taken from shallower depths. The ratio values progressively decreased with increasing depth, down to about 1 to 2 meters below the surface. Larger Ge/Si values provided evidence of uptake and incorporation of Si into phytoliths in leaf structures by prevailing native grasses that depleted Si at shallower depths. As the end of the annual growth cycle for the grasses coincides with the onset of seasonal rains, the phytolithic Si becomes readily available for fluvial transport. These results have important ramifications in interpreting Si fluxes for the estimation of weathering rates in watersheds.

  15. Extending electromagnetic methods to map coastal pore water salinities

    USGS Publications Warehouse

    Greenwood, Wm. J.; Kruse, S.; Swarzenski, P.

    2006-01-01

    The feasibility of mapping pore water salinity based on surface electromagnetic (EM) methods over land and shallow marine water is examined in a coastal wetland on Tampa Bay, Florida. Forward models predict that useful information on seabed conductivity can be obtained through <1.5 m of saline water, using floating EM-31 and EM-34 instruments from Geonics Ltd. The EM-31 functioned as predicted when compared against resistivity soundings and pore water samples and proved valuable for profiling in otherwise inaccessible terrain due to its relatively small size. Experiments with the EM-34 in marine water, however, did not reproduce the theoretical instrument response. The most effective technique for predicting pore water conductivities based on EM data entailed (1) computing formation factors from resistivity surveys and pore water samples at representative sites and (2) combining these formation factors with onshore and offshore EM-31 readings for broader spatial coverage. This method proved successful for imaging zones of elevated pore water conductivities/ salinities associated with mangrove forests, presumably caused by salt water exclusion by mangrove roots. These zones extend 5 to 10 m seaward from mangrove trunks fringing Tampa Bay. Modeling indicates that EM-31 measurements lack the resolution necessary to image the subtle pore water conductivity variations expected in association with diffuse submarine ground water discharge of fresher water in the marine water of Tampa Bay. The technique has potential for locating high-contrast zones and other pore water salinity anomalies in areas not accessible to conventional marine- or land-based resistivity arrays and hence may be useful for studies of coastal-wetland ecosystems. Copyright ?? 2005 National Ground Water Association.

  16. Mangrove pore water exchange across a latitudinal gradient

    NASA Astrophysics Data System (ADS)

    Tait, Douglas R.; Maher, Damien T.; Macklin, Paul A.; Santos, Isaac R.

    2016-04-01

    We combined observations of the natural tracer radon (222Rn) with hydrodynamic models across a broad latitudinal gradient covering several climate zones to estimate pore water exchange rates in mangroves. Pore water exchange ranged from 2.1 to 35.5 cm d-1 from temperate to tropical regions and averaged 16.3 ± 5.1 cm d-1. If upscaled to the global weighted mangrove area, pore water exchange in mangroves would recirculate the entire volume of water overlying the continental shelf in less than 153 years. Although pore water exchange (recirculated seawater) and river discharge represent different pathways for water entering the coastal ocean, the estimated global mangrove pore water exchange would be equal to approximately one third of annual global river discharge to the ocean (3.84 × 1013 m3 yr-1). Because biogeochemical processes in mangroves are largely dependent on pore water exchange, these large exchange rates have major implications for coastal nutrient, carbon, and greenhouse gas cycling in tropical marine systems.

  17. Controls on the δ 13C of dissolved inorganic carbon in marine pore waters: An integrated case study of isotope exchange during syndepositional recrystallization of biogenic carbonate sediments (South Florida Platform, USA)

    NASA Astrophysics Data System (ADS)

    Walter, Lynn M.; Ku, Timothy C. W.; Muehlenbachs, Karlis; Patterson, William P.; Bonnell, Linda

    2007-06-01

    The carbon isotope systematics of marine carbonates, organic matter and dissolved inorganic carbon (DIC) play a critical role in quantifying carbonate dissolution fluxes from modern deep-ocean sediments to paleoocean-atmospheric modeling. However, there is a growing body of evidence that C mass and isotope balances in marine pore waters appear incompatible, suggesting that some processes other than mass transport, carbonate dissolution, and organic matter decomposition have significantly increased the value of δ 13C (DIC). We present a comprehensive data set of pore water and sediment geochemistries in biogenic carbonates from well-characterized depositional environments of the South Florida platform. Pore water elemental and δ 13C (DIC) values are integrated with δ 13C values of carbon sources (seawater, organic and inorganic carbon), sediment mixing rates ( 210Pb profiles), microbial sulfate reduction rates (SRR) (radiotracer 35SO 42-), and incubation experiments spiked with low δ 13C (DIC) to estimate the rate and extent of C isotope exchange. Together, these data indicate that biogenic carbonates undergo extensive syndepositional recrystallization at rates comparable to net dissolution rates, permitting significant exchange between isotopically depleted organic C and isotopically enriched inorganic C pools. Significant amounts of net carbonate dissolution are common in the pore waters of these low-Fe sediments, as manifested by Ca 2+/Cl - ratios increased by up to 25% relative to overlying seawater. Despite rapid microbial SRR, degrees of pore water SO 42- reduction usually are maintained below 5% by H 2S oxidation, the main acid source for dissolution. These processes increase pore water DIC concentrations by more than 6 mM, over a 5-fold increase relative to overlying seawater values. Pore water δ 13C (DIC) values are usually greater than -5‰, and sometimes as high as +2‰, despite decomposition of organic matter with low δ 13C values (-9‰ to -15

  18. Pore Water Pumping by Upside-Down Jellyfish

    NASA Astrophysics Data System (ADS)

    Gaddam, Manikantam; Santhanakrishnan, Arvind

    2016-11-01

    Patchy aggregations of Cassiopea medusae, commonly called upside-down jellyfish, are found in sheltered marine environments with low-speed ambient flows. These medusae exhibit a sessile, non-swimming lifestyle, and are oriented such that their bells are attached to the substrate and oral arms point towards sunlight. Pulsations of their bells are used to generate currents for suspension feeding. Their pulsations have also been proposed to generate forces that can release sediment locked nutrients into the surrounding water. The goal of this study is to examine pore water pumping by Cassiopea individuals in laboratory aquaria, as a model for understanding pore water pumping in unsteady flows. Planar laser-induced fluorescence (PLIF) measurements were conducted to visualize the release of pore water via bell motion, using fluorescent dye introduced underneath the substrate. 2D particle image velocimetry (PIV) measurements were conducted on the same individuals to correlate PLIF-based concentration profiles with the jets generated by pulsing of medusae. The effects of varying bell diameter on pore water release and pumping currents will be discussed.

  19. Determination of 1-chloro-4-[2,2,2-trichloro-1-(4-chlorophenyl)ethyl]benzene and related compounds in marine pore water by automated thermal desorption-gas chromatography/mass spectrometry using disposable optical fiber

    USGS Publications Warehouse

    Eganhouse, Robert P.; DiFilippo, Erica L

    2015-01-01

    A method is described for determination of ten DDT-related compounds in marine pore water based on equilibrium solid-phase microextraction (SPME) using commercial polydimethylsiloxane-coated optical fiber with analysis by automated thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS). Thermally cleaned fiber was directly exposed to sediments and allowed to reach equilibrium under static conditions at the in situ field temperature. Following removal, fibers were rinsed, dried and cut into appropriate lengths for storage in leak-tight containers at -20°C. Analysis by TD-GC/MS under full scan (FS) and selected ion monitoring (SIM) modes was then performed. Pore-water method detection limits in FS and SIM modes were estimated at 0.05-2.4ng/L and 0.7-16pg/L, respectively. Precision of the method, including contributions from fiber handling, was less than 10%. Analysis of independently prepared solutions containing eight DDT compounds yielded concentrations that were within 6.9±5.5% and 0.1±14% of the actual concentrations in FS and SIM modes, respectively. The use of optical fiber with automated analysis allows for studies at high temporal and/or spatial resolution as well as for monitoring programs over large spatial and/or long temporal scales with adequate sample replication. This greatly enhances the flexibility of the technique and improves the ability to meet quality control objectives at significantly lower cost.

  20. Improved Marine Waters Monitoring

    NASA Astrophysics Data System (ADS)

    Palazov, Atanas; Yakushev, Evgeniy; Milkova, Tanya; Slabakova, Violeta; Hristova, Ognyana

    2017-04-01

    IMAMO - Improved Marine Waters Monitoring is a project under the Programme BG02: Improved monitoring of marine waters, managed by Bulgarian Ministry of environment and waters and co-financed by the Financial Mechanism of the European Economic Area (EEA FM) 2009 - 2014. Project Beneficiary is the Institute of oceanology - Bulgarian Academy of Sciences with two partners: Norwegian Institute for Water Research and Bulgarian Black Sea Basin Directorate. The Project aims to improve the monitoring capacity and expertise of the organizations responsible for marine waters monitoring in Bulgaria to meet the requirements of EU and national legislation. The main outcomes are to fill the gaps in information from the Initial assessment of the marine environment and to collect data to assess the current ecological status of marine waters including information as a base for revision of ecological targets established by the monitoring programme prepared in 2014 under Art. 11 of MSFD. Project activities are targeted to ensure data for Descriptors 5, 8 and 9. IMAMO aims to increase the institutional capacity of the Bulgarian partners related to the monitoring and assessment of the Black Sea environment. The main outputs are: establishment of real time monitoring and set up of accredited laboratory facilities for marine waters and sediments chemical analysis to ensure the ability of Bulgarian partners to monitor progress of subsequent measures undertaken.

  1. Enhanced submarine ground water discharge form mixing of pore water and estuarine water

    USGS Publications Warehouse

    Martin, Jonathan B.; Cable, Jaye E.; Swarzenski, Peter W.; Lindenberg, Mary K.

    2004-01-01

    Submarine ground water discharge is suggested to be an important pathway for contaminants from continents to coastal zones, but its significance depends on the volume of water and concentrations of contaminants that originate in continental aquifers. Ground water discharge to the Banana River Lagoon, Florida, was estimated by analyzing the temporal and spatial variations of Cl− concentration profiles in the upper 230 cm of pore waters and was measured directly by seepage meters. Total submarine ground water discharge consists of slow discharge at depths > ∼70 cm below seafloor (cmbsf) of largely marine water combined with rapid discharge of mixed pore water and estuarine water above ∼70 cmbsf. Cl− profiles indicate average linear velocities of ∼0.014 cm/d at depths > ∼70 cmbsf. In contrast, seepage meters indicate water discharges across the sediment-water interface at rates between 3.6 and 6.9 cm/d. The discrepancy appears to be caused by mixing in the shallow sediment, which may result from a combination of bioirrigation, wave and tidal pumping, and convection. Wave and tidal pumping and convection would be minor because the tidal range is small, the short fetch of the lagoon limits wave heights, and large density contacts are lacking between lagoon and pore water. Mixing occurs to ∼70 cmbsf, which represents depths greater than previously reported. Mixing of oxygenated water to these depths could be important for remineralization of organic matter.

  2. Two-dimensional determination of dissolved iron and sulfur species in marine sediment pore-waters by thin-film based imaging. Thau lagoon (France)

    NASA Astrophysics Data System (ADS)

    Jézéquel, Didier; Brayner, Roberta; Metzger, Edouard; Viollier, Eric; Prévot, François; Fiévet, Fernand

    2007-04-01

    A device composed of a polyacrylamide gel thin-film (18 cm high, 5 cm wide and 0.4 mm thick) and a PVC (polyvinyl chloride) film was used as a sediment probe to obtain iron and S(-II) sulfur dissolved species' distributions in sediment pore waters. A porous protective membrane was set on top of hydrogel layer. Probes were deployed in May 2003 for 24-48 h in the superficial sediment of Thau lagoon (France), in a shellfish farming area. The polyacrylamide gel layer was used as a DET (Diffusive Equilibration in Thin-films) device for 2D Fe(II) concentration determination, and as the diffusive layer of a DGT-like (Diffusive Gradients in Thin-films) device for sulfur species study. The accumulation layer of the DGT device consisted in a PVC film layer underneath the polyacrylamide layer. Iron determinations were performed by colorimetric methods with Ferrozine and imaging technique. Image acquisitions were performed with a flatbed scanner. Fe(II) concentrations were deducted from densitometry analysis of the magenta zones (ImageJ software). The calibration curve was obtained by densitometry analysis of polyacrylamide gel pieces which were equilibrated in known iron (II) concentration solutions. ΣFe distribution was performed but not quantified. Analysis of gray zones on the PVC layer provided a qualitative distribution of unidentified S(-II) dissolved compounds, related to H 2S zone for which information is obtained by classical methods (peeper and colorimetric measurements). EDX (X-ray energy dispersive spectrometry) and GIXR (Grazing-Incidence X-ray Diffraction) analyses of gray zone of this PVC layer provide evidence for FeS 2 catalyzed precipitation onto this film. Dissolved Fe(II) was mainly located near the sediment-water interface (SWI), showing a nonhomogeneous layer about 10 mm thick. Small Fe rich domains appeared deeper in the sediment and likely confirm newest paradigms in the field of sediment biogeochemistry. S(-II) species are detected from 3 to 4 cm

  3. Displacement of soil pore water by trichloroethylene

    SciTech Connect

    Wershaw, R.L.; Aiken, G.R.; Imbrigiotta, T.E.

    1994-07-01

    Dense nonaqueous phase liquids (DNAPLS) are important pollutants because of their widespread use as chemical and industrial solvents. An example of the pollution caused by the discharge of DNAPLs is found at the Picatinny Arsenal, New Jersey, where trichloroethylene (TCE) has been discharged directly into the unsaturated zone. This discharge has resulted in the formation of a plume of TCE-contaminated water in the aquifer downgradient of the discharge. A zone of dark-colored groundwater containing a high dissolved organic C content has been found near the point of discharge of the TCE. The colored-water plume extends from the point of discharge at least 30 m (100 feet) downgradient. Fulvic acids isolated from the colored-waters plume, from water from a background well that has not been affected by the discharge of chlorinated solvents, and from soil pore water collected in a lysimeter installed at an uncontaminated site upgradient of the study area have been compared. Nuclear magnetic resonance spectra of the fulvic acids from the colored waters and from the lysimeter am very similar, but are markedly different from the nuclear magnetic resonance spectrum of the fulvic acid from the background well. The three-dimensional fluorescence spectrum and the DOC fractionation profile of the colored groundwater and the soil pore water are very similar to each other, but quite different from those of the background water. It is proposed from these observations that this colored water is soil pore water that has been displaced by a separate DNAPL liquid phase downward to the saturated zone. 15 refs., 6 figs., 4 tabs.

  4. Displacement of soil pore water by trichloroethylene

    USGS Publications Warehouse

    Wershaw, R. L.; Aiken, G.R.; Imbrigiotta, T.E.; Goldberg, M.C.

    1994-01-01

    Dense nonaqueous phase liquids (DNAPLS) are important pollutants because of their widespread use as chemical and industrial solvents. An example of the pollution caused by the discharge of DNAPLs is found at the Picatinny Arsenal, New Jersey, where trichloroethylene (TCE) has been discharged directly into the unsaturated zone. This discharge has resulted in the formation of a plume of TCE-contaminated water in the aquifer downgradient of the discharge. A zone of dark-colored groundwater containing a high dissolved organic C content has been found near the point of discharge of the TCE. The colored-water plume extends from the point of discharge at least 30 m (100 feet) downgradient. Fulvic acids isolated from the colored-waters plume, from water from a background well that has not been affected by the discharge of chlorinated solvents, and from soil pore water collected in a lysimeter installed at an uncontaminated site upgradient of the study area have been compared. Nuclear magnetic resonance spectra of the fulvic acids from the colored waters and from the lysimeter are very similar, but are markedly different from the nuclear magnetic resonance spectrum of the fulvic acid from the background well. The three-dimensional fluorescence spectrum and the DOC fractionation profile of the colored groundwater and the soil pore water are very similar to each other, but quite different from those of the background water. It is proposed from these observations that this colored water is soil pore water that has been displaced by a separate DNAPL liquid phase downward to the saturated zone.

  5. Pore networks in continental and marine mudstones: Characteristics and controls on sealing behavior

    USGS Publications Warehouse

    Heath, J.E.; Dewers, T.A.; McPherson, B.J.O.L.; Petrusak, R.; Chidsey, T.C.; Rinehart, A.J.; Mozley, P.S.

    2011-01-01

    Mudstone pore networks are strong modifiers of sedimentary basin fluid dynamics and have a critical role in the distribution of hydrocarbons and containment of injected fluids. Using core samples from continental and marine mudstones, we investigate properties of pore types and networks from a variety of geologic environments, together with estimates of capillary beam- scanning electron microscopy, suggest seven dominant mudstone pore types distinguished by geometry and connectivity. A dominant planar pore type occurs in all investigated mudstones and generally has high coordination numbers (i.e., number of neighboring connected pores). Connected networks of pores of this type contribute to high mercury capillary pressures due to small pore throats at the junctions of connected pores and likely control most matrix transport in these mudstones. Other pore types are related to authigenic (e.g., replacement or pore-lining precipitation) clay minerals and pyrite nodules; pores in clay packets adjacent to larger, more competent clastic grains; pores in organic phases; and stylolitic and microfracture-related pores. Pores within regions of authigenic clay minerals often form small isolated networks (<3 ??m). Pores in stringers of organic phases occur as tubular pores or slit- and/or sheet-like pores. These form short, connected lengths in 3D reconstructions, but appear to form networks no larger than a few microns in size. Sealing efficiency of the studied mudstones increases with greater distal depositional environments and greater maximum depth of burial. ?? 2011 Geological Society of America.

  6. Dissolved Organic Phosphorus In Shelf Sediment Pore-waters

    NASA Astrophysics Data System (ADS)

    Statham, P. J.; Homoky, W. B.

    2016-02-01

    Marine sediments are a major reservoir for the macronutrient phosphorus (P). The cycling, fate and form of P in pore-waters has focussed almost exclusively on the easy to measure soluble reactive (SRP) forms. There are, however, very few data available for the "dissolved organic" forms of P, i.e. the difference between the total dissolved P and SRP. Preliminary data on "DOP" and SRP forms of P in shelf sediments around the UK show that the organic fraction can be important (up to 30% of the size of the SRP pool), and the magnitude of this "organic" signal varies with season and delivery of post bloom organic matter to the sediment. A limited number of oceanic samples show a sequence of decreasing DOP concentrations in pore-waters on moving off shelf that decrease to undetectable levels in deep-water oxic sediments. Present budgets and diagenetic models ignore this "organic" pool that represents an important intermediary in the benthic cycling of P.

  7. Differences in soluble organic carbon chemistry in pore waters sampled from different pore size domains

    DOE PAGES

    Bailey, Vanessa L.; Smith, A. P.; Tfaily, Malak; ...

    2017-01-11

    Spatial isolation of soil organic carbon (SOC) in different sized pores may be a mechanism by which otherwise labile carbon (C) could be protected in soils. When soil water content increases, the hydrologic connectivity of soil pores also increases, allowing greater transport of SOC and other resources from protected locations, to microbially colonized locations more favorable to decomposition. The heterogeneous distribution of specialized decomposers, C, and other resources throughout the soil indicates that the metabolism or persistence of soil C compounds is highly dependent on short-distance transport processes. The objective of this research was to characterize the complexity of Cmore » in pore waters held at weak and strong water tensions (effectively soil solution held behind coarse- and fine-pore throats, respectively) and evaluate the microbial decomposability of these pore waters. We saturated intact soil cores and extracted pore waters with increasing suction pressures to sequentially sample pore waters from increasingly fine pore domains. Ultrahigh resolution mass spectrometry of the SOC was used to profile the major biochemical classes (i.e., lipids, proteins, lignin, carbohydrates, and condensed aromatics) of compounds present in the pore waters; some of these samples were then used as substrates for growth of Cellvibrio japonicus (DSMZ 16018), Streptomyces cellulosae (ATCC® 25439™), and Trichoderma reseei (QM6a) in 7 day incubations. The soluble C in finer pores was more complex than the soluble C in coarser pores, and the incubations revealed that the more complex C in these fine pores is not recalcitrant. The decomposition of this complex C led to greater losses of C through respiration than the simpler C from coarser pore waters. Our research suggests that soils that experience repeated cycles of drying and wetting may be accompanied by repeated cycles of increased CO2 fluxes that are driven by i) the transport of C from protected pools into

  8. Differences in soluble organic carbon chemistry in pore waters sampled from different pore size domains

    DOE PAGES

    Bailey, V. L.; Smith, A. P.; Tfaily, M.; ...

    2017-04-01

    Spatial isolation of soil organic carbon (SOC) in different sized pores may be a mechanism by which otherwise labile carbon (C) could be protected in soils. When soil water content increases, the hydrologic connectivity of soil pores also increases, allowing greater transport of SOC and other resources from protected locations, to microbially colonized locations more favorable to decomposition. The heterogeneous distribution of specialized decomposers, C, and other resources throughout the soil indicates that the metabolism or persistence of soil C compounds is highly dependent on short-distance transport processes. The objective of this research was to characterize the complexity of Cmore » in pore waters held at weak and strong water tensions (effectively soil solution held behind coarse- and fine-pore throats, respectively) and evaluate the microbial decomposability of these pore waters. We saturated intact soil cores and extracted pore waters with increasing suction pressures to sequentially sample pore waters from increasingly fine pore domains. Ultrahigh resolution mass spectrometry of the SOC was used to profile the major biochemical classes (i.e., lipids, proteins, lignin, carbohydrates, and condensed aromatics) of compounds present in the pore waters; some of these samples were then used as substrates for growth of Cellvibrio japonicus (DSMZ 16018), Streptomyces cellulosae (ATCC® 25439™), and Trichoderma reseei (QM6a) in 7 day incubations. The soluble C in finer pores was more complex than the soluble C in coarser pores, and the incubations revealed that the more complex C in these fine pores is not recalcitrant. The decomposition of this complex C led to greater losses of C through respiration than the simpler C from coarser pore waters. Our research suggests that soils that experience repeated cycles of drying and wetting may result in patterns of CO2 fluxes that are driven by i) the transport of C from protected pools into active, ii) the chemical

  9. Fouling Study of Silicon Oxide Pores Exposed to Tap Water

    SciTech Connect

    Nilsson, J.; Bourcier, W.L.; Lee, J.R.I.; Letant, S.E.; /LLNL, Livermore

    2007-07-12

    We report on the fouling of Focused Ion Beam (FIB)-fabricated silicon oxide nanopores after exposure to tap water for two weeks. Pore clogging was monitored by Scanning Electron Microscopy (SEM) on both bare silicon oxide and chemically functionalized nanopores. While fouling occurred on hydrophilic silicon oxide pore walls, the hydrophobic nature of alkane chains prevented clogging on the chemically functionalized pore walls. These results have implications for nanopore sensing platform design.

  10. Hydrochemical reactions and origin of offshore relatively fresh pore water from core samples in Hong Kong

    NASA Astrophysics Data System (ADS)

    Kwong, Hiu Tung; Jiao, Jiu Jimmy

    2016-06-01

    The existence of relatively fresh pore water offshore has been well recognised over the globe but studies on the chemistry of the pore water from offshore geological formations are extremely limited. This study aims to characterize the hydrochemistry of the submarine groundwater body in Hong Kong. It looks into the major ion concentrations and the stable isotopic compositions of pore water extracted from core samples from an offshore 42.30-m vibrocore in the southwestern Hong Kong waters. A minimum Cl- level of about one-third of that in typical seawater was noted in the terrestrial sediments, suggesting the presence of offshore relatively fresh water. Unexpectedly high NH4+ levels are attributed to organic matter decomposition in the terrestrial sediments. The leaching of shells due to exposure of marine sediments at sea-level low stands raises the Mg2+ and Ca2+ concentrations. Base Exchange Indices show weak cation exchange reactions in which Na+ and K+ are released while Mg2+ and Ca2+ are adsorbed. Isotopic compositions of pore water reveal that the low-salinity water is probably the relic water sequestered in fluvial systems during relative sea-level low stands. Cores properly stored in a freezer for a long time has been used to study the pore water chemistry. For the first time, this study introduces an approach to correct the measured data by considering the possible evaporation effect during the transportation and storage of the samples. Corrections for evaporation were applied to the major ion concentrations and the stable isotopic compositions of pore water measured. It is found that the corrections determined by the Cl- mass balance approach are more reliable. The corrected measurements give more reasonable observations and hence allow sensible conclusions on the hydrochemical reactions and the origin of pore water.

  11. The ability of rock physics models to infer marine in situ pore pressure

    NASA Astrophysics Data System (ADS)

    Hornbach, Matthew J.; Manga, Michael

    2014-12-01

    fluid pressure is an important parameter defining the mechanical strength of marine sediments. Obtaining high spatial resolution in situ pore pressure measurements in marine sediments, however, is a challenge, and as a result, only a handful of in situ pore pressure measurements exist at scientific drill sites. Integrating rock physics models with standard IODP/ODP measurements provides a potentially widely applicable approach for calculating in situ pore pressure. Here we use a rock physics approach to estimate in situ pore pressure at two Scientific Ocean Drill Sites where in situ pressure is well constrained: ODP Site 1173, used as reference for normal (hydrostatic) fluid pressures, and ODP Site 948, where previous studies infer high fluid pressures (λ* ˜ 0.45-0.95, where the pore pressure ratio λ* is defined as the pore pressure above hydrostatic divided by the difference between the largest principal stress and hydrostatic stress). Our analysis indicates that the rock physics method provides an accurate, low-precision method for estimating in situ pore pressure at these drill sites, and sensitivity analysis indicates this method can detect modestly high (λ* > 0.6) pore pressure at the 95% confidence level. This approach has broad applicability because it provides an inexpensive, high-resolution (meter-scale) method for retrospectively detecting and quantifying high pore pressure at any drill site where quality wireline logs and ocean drilling data exist.

  12. Effects of salinity variations on pore water flow in salt marshes

    NASA Astrophysics Data System (ADS)

    Shen, Chengji; Jin, Guangqiu; Xin, Pei; Kong, Jun; Li, Ling

    2015-06-01

    Spatial and temporal salinity variations in surface water and pore water commonly exist in salt marshes under the combined influence of tidal inundation, precipitation, evapotranspiration, and inland freshwater input. Laboratory experiments and numerical simulations were conducted to investigate how density gradients associated with salinity variations affect pore water flow in the salt marsh system. The results showed that upward salinity (density) gradients could lead to flow instability and the formation of salt fingers. These fingers, varying in size with the distance from the creek, modified significantly the pore water flow field, especially in the marsh interior. While the flow instability enhanced local salt transport and mixing considerably, the net effect was small, causing only a slight increase in the overall mass exchange across the marsh surface. In contrast, downward salinity gradients exerted less influence on the pore water flow in the marsh soil and slightly weakened the surface water and groundwater exchange across the marsh surface. Numerical simulations revealed similar density effects on pore water flow at the field scale under realistic conditions. These findings have important implications for studies of marsh soil conditions concerning plant growth as well as nutrient exchange between the marsh and coastal marine system.

  13. Tidally driven pore water exchange within offshore intertidal sandbanks: Part II numerical simulations

    NASA Astrophysics Data System (ADS)

    Gibbes, B.; Robinson, C.; Li, L.; Lockington, D.; Li, H.

    2008-12-01

    Field measurements presented by [Gibbes, B., Robinson, C., Li, L., Lockington, D.A., Carey, H., 2008. Tidally driven pore water exchange within offshore intertidal sandbanks: Part I Field measurements. Estuarine, Coastal and Shelf Science 79, pp. 121-132.] revealed a tidally driven pore water flow system within an offshore intertidal sandbank in Moreton Bay, Australia. The field data suggested that this flow system might be capable of delivering nutrients, and in particular bio-available iron, across the sediment-water interface. Bio-available iron has been implicated as a key nutrient in the growth of the toxic marine cyanobacteria Lyngbya majuscula and therefore this pore water exchange process is of interest at sites where L. majuscula blooms have been observed. In this study two-dimensional numerical simulations were used in conjunction with hydraulic data from field measurements to further investigate the tidally induced pore water flow patterns. Simulation results generally showed good agreement with the field data and revealed a more complex residual pore water flow system in the sandbank than shown by the field data. The flow system, strongly influenced by the geometry of the sandbank, was characterized by two circulation cells which resulted in pore water discharge at the bank edge and also to a permanently ponded area within the sandbank interior. Simulated discharge volumes in these two zones were in the order of 0.813 m 3 and 0.143 m 3 per meter width (along shore) of sandbank per tidal cycle at the bank edge and sandbank interior respectively. Transit times of pore water circulating through these cells were found to range from ≈ 17 days to > 60 years with an average time of 780 days. The results suggest that the tidally driven flow systems might provide a mechanism for transport of bio-available iron across the sediment-water interface. This flow could constitute a previously unrecognized source of bio-available iron for L. majuscula blooms in the

  14. Marine Biodiversity in Japanese Waters

    PubMed Central

    Fujikura, Katsunori; Lindsay, Dhugal; Kitazato, Hiroshi; Nishida, Shuhei; Shirayama, Yoshihisa

    2010-01-01

    To understand marine biodiversity in Japanese waters, we have compiled information on the marine biota in Japanese waters, including the number of described species (species richness), the history of marine biology research in Japan, the state of knowledge, the number of endemic species, the number of identified but undescribed species, the number of known introduced species, and the number of taxonomic experts and identification guides, with consideration of the general ocean environmental background, such as the physical and geological settings. A total of 33,629 species have been reported to occur in Japanese waters. The state of knowledge was extremely variable, with taxa containing many inconspicuous, smaller species tending to be less well known. The total number of identified but undescribed species was at least 121,913. The total number of described species combined with the number of identified but undescribed species reached 155,542. This is the best estimate of the total number of species in Japanese waters and indicates that more than 70% of Japan's marine biodiversity remains un-described. The number of species reported as introduced into Japanese waters was 39. This is the first attempt to estimate species richness for all marine species in Japanese waters. Although its marine biota can be considered relatively well known, at least within the Asian-Pacific region, considering the vast number of different marine environments such as coral reefs, ocean trenches, ice-bound waters, methane seeps, and hydrothermal vents, much work remains to be done. We expect global change to have a tremendous impact on marine biodiversity and ecosystems. Japan is in a particularly suitable geographic situation and has a lot of facilities for conducting marine science research. Japan has an important responsibility to contribute to our understanding of life in the oceans. PMID:20689840

  15. Deep Water, Shallow Water: Marine Animal Homes.

    ERIC Educational Resources Information Center

    Soltow, Willow

    1984-01-01

    Examines the diversity of life in the oceans and ways in which teachers can explore ocean habitats with their students without leaving the classroom. Topic areas considered include: restricted habitats, people and marine habitats, pollution, incidental kills, and the commercial and recreational uses of marine waters. (JN)

  16. Deep Water, Shallow Water: Marine Animal Homes.

    ERIC Educational Resources Information Center

    Soltow, Willow

    1984-01-01

    Examines the diversity of life in the oceans and ways in which teachers can explore ocean habitats with their students without leaving the classroom. Topic areas considered include: restricted habitats, people and marine habitats, pollution, incidental kills, and the commercial and recreational uses of marine waters. (JN)

  17. Pore Water Collection, Analysis and Evolution: The Need for Standardization.

    PubMed

    Gruzalski, Jacob G; Markwiese, James T; Carriker, Neil E; Rogers, William J; Vitale, Rock J; Thal, David I

    2016-01-01

    Investigating the ecological impacts of contaminants released into the environment requires integration of multiple lines of evidence. Collection and analysis of interstitial water is an often-used line of evidence for developing benthic exposure estimates in aquatic ecosystems. It is a well-established principle that chemical and toxicity data on interstitial water samples should represent in-situ conditions; i.e., sample integrity must be maintained throughout the sample collection process to avoid alteration of the in-situ geochemical conditions. Unfortunately, collection and processing of pore water is not standardized to address possible geochemical transformations introduced by atmospheric exposure. Furthermore, there are no suitable benchmarks (ecological or human health) against which to evaluate adverse effects from chemicals in pore water; i.e., empirical data is lacking on the toxicity of inorganic contaminants in sediment interstitial water. It is clear that pore water data is best evaluated by considering the bioavailability of trace elements and the partitioning of contaminants between the aqueous and solid phases. It is also evident that there is a need for sediment researchers and regulatory agencies to collaborate in developing a standardized approach for sediment/pore water collection and data evaluation. Without such guidelines, the number of different pore water collection and extraction techniques will continue to expand, and investigators will continue to evaluate potentially questionable data by comparison to inappropriate criteria.

  18. Pore Water Transport of Enterococci out of Beach Sediments

    PubMed Central

    Phillips, Matthew C.; Solo-Gabriele, Helena M.; Reniers, Adrianus J. H. M.; Wang, John D.; Kiger, Russell T.; Abdel-Mottaleb, Noha

    2011-01-01

    Enterococci are used to evaluate the safety of beach waters and studies have identified beach sands as a source of these bacteria. In order to study and quantify the release of microbes from beach sediments, flow column systems were built to evaluate flow of pore water out of beach sediments. Results show a peak in enterococci (average of 10% of the total microbes in core) released from the sand core within one pore water volume followed by a marked decline to below detection. These results indicate that few enterococci are easily removed and that factors other than simple pore water flow control the release of the majority of enterococci within beach sediments. A significantly larger quantity and release of enterococci were observed in cores collected after a significant rain event suggesting the influx of fresh water can alter the release pattern as compared to cores with no antecedent rainfall. PMID:21945015

  19. Theoretical modeling insights into elastic wave attenuation mechanisms in marine sediments with pore-filling methane hydrate

    NASA Astrophysics Data System (ADS)

    Marín-Moreno, H.; Sahoo, S. K.; Best, A. I.

    2017-03-01

    The majority of presently exploitable marine methane hydrate reservoirs are likely to host hydrate in disseminated form in coarse grain sediments. For hydrate concentrations below 25-40%, disseminated or pore-filling hydrate does not increase elastic frame moduli, thus making impotent traditional seismic velocity-based methods. Here, we present a theoretical model to calculate frequency-dependent P and S wave velocity and attenuation of an effective porous medium composed of solid mineral grains, methane hydrate, methane gas, and water. The model considers elastic wave energy losses caused by local viscous flow both (i) between fluid inclusions in hydrate and pores and (ii) between different aspect ratio pores (created when hydrate grows); the inertial motion of the frame with respect to the pore fluid (Biot's type fluid flow); and gas bubble damping. The sole presence of pore-filling hydrate in the sediment reduces the available porosity and intrinsic permeability of the sediment affecting Biot's type attenuation at high frequencies. Our model shows that attenuation maxima due to fluid inclusions in hydrate are possible over the entire frequency range of interest to exploration seismology (1-106 Hz), depending on the aspect ratio of the inclusions, whereas maxima due to different aspect ratio pores occur only at sonic to ultrasound frequencies (104-106 Hz). This frequency response imposes further constraints on possible hydrate saturations able to reproduce broadband elastic measurements of velocity and attenuation. Our results provide a physical basis for detecting the presence and amount of pore-filling hydrate in seafloor sediments using conventional seismic surveys.

  20. Benthic invertebrate bioassays with toxic sediment and pore water

    USGS Publications Warehouse

    Giesy, John P.; Rosiu, Cornell J.; Graney, Robert L.; Henry, Mary G.

    1990-01-01

    The relative sensitivities of bioassays to determine the toxicity of sediments were investigated and three methods of making the sample dilutions required to generate dose-response relationships were compared. The assays studied were: (a) Microtox®, a 15-min assay ofPhotobacterium phosphoreum bioluminescence inhibition by pore water; (b) 48-h Daphnia magnalethality test in pore water; (c) 10-d subchronic assay of lethality to and reduction of weight gain by Chironomus tentans performed in either whole sediment or pore water; (d) 168-h acute lethality assay of Hexagenia limbata in either whole sediment or pore water. The three methods of diluting sediments were: (a) extracting pore water from the toxic location and dilution with pore water from the control station; (b) diluting whole sediment from the toxic location with control whole sediment from a reference location, then extracting pore water; and (c) diluting toxic, whole sediment with whole sediment from a reference location, then using the whole sediment in bioassays. Based on lethality, H. limbata was the most sensitive organism to the toxicity of Detroit River sediment. Lethality of D. magna in pore water was similar to that of H. limbata in whole sediment and can be used to predict effects of whole sediment toxicity to H. limbata. The concentration required to cause a 50% reduction in C. tentans growth (10-d EC50) was approximately that which caused 50% lethality of D. magna (48-h LC50) and was similar to the toxicity that restricts benthic invertebrate colonization of contaminated sediments. While the three dilution techniques gave similar results with some assays, they gave very different results in other assays. The dose-response relationships determined by the three dilution techniques would be expected to vary with sediment, toxicant and bioassay type, and the dose-response relationship derived from each technique needs to be interpreted accordingly.

  1. Slow Desorption of Phenanthrene from Silica Particles: Influence of Pore Size, Pore Water, and Aging Time

    SciTech Connect

    Huesemann, Michael H.; Fortman, Timothy J.; Riley, Robert G.; Thompson, Christopher J.; Wang, Zheming; Truex, Michael J.; Peyton, Brent M.

    2006-01-16

    When micro-porous and meso-porous silica particles were exposed to aqueous phenanthrene solutions for various durations it was observed that sorbed-phase phenanthrene concentrations increased with aging time only for meso-porous but not micro-porous silicas. Desorption equilibrium was reached almost instantaneously for the micro-porous particles while both the rate and extent of desorption decreased with increasing aging time for the meso-porous silicas. These findings indicate that phenanthrene can be sequestered within the internal pore-space of meso-porous silicas while the internal surfaces of micro-porous silicas are not accessible to phenanthrene sorption, possibly due to the presence of physi- or chemi-sorbed water that may sterically hinder the diffusion of phenanthrene inside water-filled micro-pores. By contrast, the internal surfaces of these micro-porous silicas are accessible to phenanthrene when aging methods are employed which assure that pores are devoid of physi-sorbed water. Consequently, when phenanthrene was incorporated into these particles using either supercritical CO2 or via solvent soaking, the aqueous desorption kinetics were extremely slow indicating effective sequestration of phenanthrene inside micro-porous particles. Finally, a two-compartment conceptual model is used to interpret the experimental findings.

  2. Evaporation of Topopah Spring tuff pore water

    SciTech Connect

    Dibley, M J; Knauss, K G; Rosenberg, N D

    1999-09-10

    We report on the results to date for experiments on the evaporative chemical evolution of a CaSO, rich water representative of Topopah Spring Tuff porewater from Yucca Mountain. Data include anion and cation analysis and qualitative mineral identification for a series of open system experiments, with and without crushed tuff present, conducted at sub-boiling temperatures.

  3. Development and deployment of a deep-sea Raman probe for measurement of pore water geochemistry

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Walz, Peter M.; Kirkwood, William J.; Hester, Keith C.; Ussler, William; Peltzer, Edward T.; Brewer, Peter G.

    2010-02-01

    We have developed, deployed, and tested a novel probe for study of the geochemistry of sediment pore waters based upon Raman spectroscopy. The Raman technique has already been used successfully for in situ measurements of targets of scientific interest including gas and hydrothermal vents and complex gas hydrates, but sediment geochemistry has so far been an intractable problem since the sediments themselves are strongly fluorescent and typically only very small sample volumes are obtainable. The 35 cm long probe extracts pore fluids through a 10 μm sintered metallic frit and draws the sample through a 2 mm diameter channel into a sapphire windowed optical cell within which the laser beam is focused and the spectrum recorded. The dead volume of the system is ˜1 ml and the instrument is ROV deployable with activation of probe insertion and sample withdrawal under direct operator control. The unique features of this mode of detection include observation of the sulfate gradient in marine pore waters as an indicator of diagenesis, direct measurement of the dissolved sulfide species H 2S and HS -, and measurement of dissolved methane; all of which are of primary geochemical interest. Quantitative analysis is achieved by area ratio to known water peaks and from standard calibration curves with a precision of ±5%. We find only very small fluorescence from pore waters measured in situ, but observe rapid increases in fluorescence from cores returned to the surface and exposed to oxygen.

  4. Effects of Wood Pollution on Pore-Water Sulfide Levels and Eelgrass Germination

    NASA Astrophysics Data System (ADS)

    Ekelem, C.

    2016-02-01

    Historically, sawmills released wood waste onto coastal shorelines throughout the Pacific Northwest of the USA, enriching marine sediments with organic material. The increase in organic carbon boosts the bacterial reduction of sulfate and results in the production of a toxic metabolite, hydrogen sulfide. Hydrogen sulfide is a phytotoxin and can decrease the growth and survival of eelgrass. This is a critical issue since eelgrass, Zostera marina, forms habitat for many species, stabilizes sediment, and plays a role in nutrient cycling and sediment chemistry. The objective of our study was to determine the effects of wood debris on sediment pore-water hydrogen sulfide concentrations and eelgrass germination. To test the impact of wood inputs on sulfide production and seed germination, we conducted a laboratory mesocosm experiment, adding sawdust to marine sediments and measuring the sulfide levels weekly. We subsequently planted seeds in the mesocosms and measured germination rates. Higher concentrations of sawdust led to higher levels of pore-water hydrogen sulfide and drastically slower eelgrass germination rates. Treatments with greater than 10% wood enrichment developed free sulfide concentrations of 0.815 (± 0.427) mM after 118 days, suggesting sediments with greater than 10% wood pollution may have threateningly high pore-water hydrogen sulfide levels. These results can be used to set thresholds for remediation efforts and guide seed distribution in wood polluted areas.

  5. Unstable Pore-Water Flow in Intertidal Wetlands

    NASA Astrophysics Data System (ADS)

    Barry, D. A.; Shen, C.; Li, L.

    2014-12-01

    Salt marshes are important intertidal wetlands strongly influenced by interactions between surface water and groundwater. Bordered by coastal water, the marsh system undergoes cycles of inundation and exposure driven by the tide. This leads to dynamic, complex pore-water flow and solute transport in the marsh soil. Pore-water circulations occur over vastly different spatial and temporal scales with strong link to the marsh topography. These circulations control solute transport between the marsh soil and the tidal creek, and ultimately affect the overall nutrient exchange between the marsh and coastal water. The pore-water flows also dictate the soil condition, particularly aeration, which influences the marsh plant growth. Numerous studies have been carried out to examine the pore-water flow process in the marsh soil driven by tides, focusing on stable flow with the assumption of homogeneity in soil and fluid properties. This assumption, however, is questionable given the actual inhomogeneous conditions in the field. For example, the salinity of surface water in the tidal creek varies temporally and spatially due to the influence of rainfall and evapotranspiration as well as the freshwater input from upland areas to the estuary, creating density gradients across the marsh surface and within the marsh soil. Many marshes possess soil stratigraphy with low-permeability mud typically overlying high-permeability sandy deposits. Macropores such as crab burrows are commonly distributed in salt marsh sediments. All these conditions are prone to the development of non-uniform, unstable preferential pore-water flow in the marsh soil, for example, funnelling and fingering. Here we present results from laboratory experiments and numerical simulations to explore such unstable flow. In particular, the analysis aims to address how the unstable flow modifies patterns of local pore-water movement and solute transport, as well as the overall exchange between the marsh soil and

  6. Molecular characterization of dissolved organic matter in pore water of continental shelf sediments

    NASA Astrophysics Data System (ADS)

    Schmidt, Frauke; Elvert, Marcus; Koch, Boris P.; Witt, Matthias; Hinrichs, Kai-Uwe

    2009-06-01

    Dissolved organic matter (DOM) in sediment pore water is a complex molecular mixture reflecting various sources and biogeochemical processes. In order to constrain those sources and processes, molecular variations of pore water DOM in surface sediments from the NW Iberian shelf were analyzed by ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and compared to river and marine water column DOM. Weighted average molecular element ratios of oxygen to carbon ((O/C) wa) and hydrogen to carbon ((H/C) wa) provided general information about DOM sources. DOM in local rivers was more oxygenated ((O/C) wa 0.52) and contained less hydrogen ((H/C) wa 1.15) than marine pore water DOM (mean (O/C) wa 0.50, mean (H/C) wa 1.26). The relative abundance of specific compound groups, such as highly oxygenated aromatic compounds or nitrogen-bearing compounds with low H/C ratios, correspond to a high concentration of lignin phenols (160 μg/g sediment dry weight) and a high TOC/TN ratio (13.3) in the sedimentary organic matter and were therefore assigned to terrestrial sources. The lower degree of unsaturation and a higher relative abundance of nitrogen-bearing compounds in the pore water DOM reflected microbial activity within the sediment. One sampling site on the shelf with a high sediment accumulation, and a humic-rich river sample showed a wide range of sulfur compounds in the DOM, accompanied by a higher abundance of lipid biomarkers for sulfate-reducing bacteria, probably indicating early diagenetic sulfurization of organic matter.

  7. Carbon and nitrogen stoichiometry regulates the magnitude and temporal dynamics of nitrogenous nutrient regeneration in sandy beach pore water

    NASA Astrophysics Data System (ADS)

    Goodridge, B. M.; Melack, J. M.

    2013-12-01

    Sandy beaches are located at the interface of terrestrial and marine ecosystems, lining about 70% of the world's ice-free coastline. They can be conduits for fresh groundwater delivery of dissolved inorganic nitrogen (DIN), a vital and often limiting nutrient source, to oceans along coastlines where a hydrologic connection exists with shallow coastal aquifers. However, even along such coastlines, the majority of water within beach sands is recirculated seawater (i.e., pore water), and the regeneration of DIN from the mineralization of marine organic matter (OM) is considered the dominant source of DIN in beach pore water and flux to coastal oceans. The biogeochemical mechanisms regulating the magnitude of and temporal changes in DIN regeneration in saline beach pore water are therefore of prime importance in assessing the role of beaches in coastal marine nitrogen cycling. We assessed the potential stoichiometric control of resource carbon to nitrogen (C:N) on pore water DIN regeneration at four sandy beach study locations, and temporal evolution of pore water C:N at two of the four study locations, along the Santa Barbara, California coastline during synoptic sampling events over the course of a year. We identified pore water dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) as the resources most likely available to microbial heterotrophic metabolism (i.e., C:N), the dominant catalyst of DIN regeneration in marine sediments, finding a negative exponential correlation of DIN with DOC:TDN ratios (673 × 173 e-1.05 × 0.30(DOC:TDN); R2 = 0.55, n = 123). DOC:TDN ratios also demonstrated a negative exponential correlation with residence time (10.0 × 1.7 e-1.08 × 0.48(RT) + 1.61 × 0.54; R2 = 0.79, n = 46), estimated using radon-222 as a pore water residence time tracer. Using model-derived DOC:TDN ratios as the independent variable in the DIN vs. DOC:TDN relationship, we explored temporal changes in DIN regeneration. The modeled DIN vs. residence time

  8. Occurrence of arsenic in sediment pore waters in the central Kanto Plain, Japan

    NASA Astrophysics Data System (ADS)

    Hachinohe, Shoichi; Hamamoto, Hideki; Ishiyama, Takashi; Hossain, Sushmita; Oguchi, Chiaki T.

    2014-05-01

    The Kanto Plain is known as the largest plain in Japan, where marine sediments are widely developed because of cyclic iteration of global sea-level changes even 50 km or more inland from the present shoreline. In this area, dependence on groundwater for water requirements is relatively high; in particular, around 40 % of the municipal water supply is dependent on groundwater. Arsenic levels greater than that permitted by the environmental standards of Japan have been detected in groundwater in this area. Therefore, to evaluate occurrences of arsenic and other related elements in pore waters contained in natural sediment layers, we measured the levels of various inorganic chemical substances such as arsenic (As), iron (Fe), and sulfur (S) and major dissolved ions such as sulfate (SO42-), calcium (Ca2+), and sodium (Na+). Pore waters were collected from sediment samples that were obtained by a drilling from the river bottom down to 44 m depth; pore water samples were obtained immediately after extraction of sediments. The sedimentary facies in the vertical profile are continental, transitional, and marine, including two aquifers. The upper aquifer (15-20 m) contains fine to medium sand, whereas the lower aquifer (37-44 m) contains medium to coarse and gravelly sand. Arsenic and other inorganic elements were measured by an inductively coupled plasma mass spectrometer (ICP/MS) and an inductively coupled plasma atomic emission spectrometer (ICP/AES), and major dissolved ions were measured by an ion chromatograph analyzer. The total content of chemical elements was measured by X-ray fluorescence analysis using solid sediment samples. We obtained the following results. The arsenic concentrations in pore waters in marine silt and clay sediments (approximately 0.04 mg/L) were about five times higher than that in continental sediments (approximately 0.008 mg/L). The highest concentration of arsenic (0.074 mg/L) was detected at a depth of 13 m, which is immediately above the

  9. Impact of point and nonpoint source pollution on pore waters of two Chesapeake Bay tributaries.

    PubMed

    Karuppiah, M; Gupta, G

    1996-10-01

    Chesapeake Bay and its tributaries are contaminated by industrial and municipal point sources and agricultural nonpoint sources of pollution. The objective of this study was to compare the porewater characteristics of two Chesapeake Bay tributaries: Wicomico River (WR) contaminated by point source and Pocomoke River (PR) contaminated by both point and nonpoint sources of pollution. Four study sites (1 mile before, adjacent to, and 1 and 2 miles after the sewage treatment plant) were chosen to collect sediment samples in both the rivers. The sediment-pore waters were analyzed for toxicity using Microtox marine luminescent bacteria-Vibrio fischeri. USEPA toxicity identification evaluation tests on these pore waters confirmed that the contaminants (ammonia and heavy metals) in WR were from municipal point sources, whereas in PR the contamination (metals, pesticides, and PCBs) was from nonpoint sources (agriculture) of pollution. The toxicity (and the concentration of contaminants) decreased both upstream and downstream from the most polluted site in both the rivers.

  10. Pore connectivity, electrical conductivity, and partial water saturation: Network simulations

    NASA Astrophysics Data System (ADS)

    Li, M.; Tang, Y. B.; Bernabé, Y.; Zhao, J. Z.; Li, X. F.; Bai, X. Y.; Zhang, L. H.

    2015-06-01

    The electrical conductivity of brine-saturated rock is predominantly dependent on the geometry and topology of the pore space. When a resistive second phase (e.g., air in the vadose zone and oil/gas in hydrocarbon reservoirs) displaces the brine, the geometry and topology of the pore space occupied by the electrically conductive phase are changed. We investigated the effect of these changes on the electrical conductivity of rock partially saturated with brine. We simulated drainage and imbibition as invasion and bond percolation processes, respectively, in pipe networks assumed to be perfectly water-wet. The simulations included the formation of a water film in the pipes invaded by the nonwetting fluid. During simulated drainage/imbibition, we measured the changes in resistivity index as well as a number of relevant microstructural parameters describing the portion of the pore space saturated with water. Except Euler topological number, all quantities considered here showed a significant level of "universality," i.e., insensitivity to the type of lattice used (simple cubic, body-centered cubic, or face-centered cubic). Hence, the coordination number of the pore network appears to be a more effective measure of connectivity than Euler number. In general, the simulated resistivity index did not obey Archie's simple power law. In log-log scale, the resistivity index curves displayed a substantial downward or upward curvature depending on the presence or absence of a water film. Our network simulations compared relatively well with experimental data sets, which were obtained using experimental conditions and procedures consistent with the simulations. Finally, we verified that the connectivity/heterogeneity model proposed by Bernabé et al. (2011) could be extended to the partial brine saturation case when water films were not present.

  11. Hydrogeology and hydrodynamics of coral reef pore waters

    SciTech Connect

    Buddemeier, R.W.; Oberdorfer, J.A.

    1988-06-29

    A wide variety of forces can produce head gradients that drive the flow and advective mixing of internal coral reef pore waters. Oscillatory gradients that produce mixing result from wave and tide action. Sustained gradients result from wave and tide-induced setup and ponding, from currents impinging on the reef structure, from groundwater heads, and from density differenced (temperature or salinity gradients). These gradients and the permeabilities and porosities of reef sediments are such that most macropore environments are dominated by advection rather than diffusion. The various driving forces must be analyzed to determine the individual and combined magnitudes of their effects on a specific reef pore-water system. Pore-water movement controls sediment diagenesis, the exchange of nutrients between sediments and benthos, and coastal/island groundwater resources. Because of the complexity of forcing functions, their interactions with specific local reef environments, experimental studies require careful incorporation of these considerations into their design and interpretation. 8 refs., 3 figs., 1 tab.

  12. Toxicity of sediments and pore water from Brunswick Estuary, Georgia

    USGS Publications Warehouse

    Winger, Parley V.; Lasier, Peter J.; Geitner, Harvey

    1993-01-01

    A chlor-alkali plant in Brunswick, Georgia, USA, discharged >2 kg mercury/d into a tributary of the Turtle River-Brunswick Estuary from 1966 to 1971. Mercury concentrations in sediments collected in 1989 along the tributary near the chlor-alkali plant ranged from 1 to 27 μg/g (dry weight), with the highest concentrations found in surface (0–8 cm) sediments of subtidal zones in the vicinity of the discharge site. Toxicity screening in 1990 using Microtox® bioassays on pore water extracted on site from sediments collected at six stations distributed along the tributary indicated that pore water was highly toxic near the plant discharge. Ten-day toxicity tests on pore water from subsequent sediment samples collected near the plant discharge confirmed high toxicity to Hyalella azteca, and feeding activity was significantly reduced in whole-sediment tests. In addition to mercury in the sediments, other metals (chromium, lead, and zinc) exceeded 50 μg/g, and polychlorobiphenyl (PCB) concentrations ranged from 67 to 95 μg/g. On a molar basis, acid-volatile sulfide concentrations (20–45 μmol/g) in the sediments exceeded the metal concentrations. Because acid-volatile sulfides bind with cationic metals and form metal sulfides, which are generally not bioavailable, toxicities shown by these sediments were attributed to the high concentrations of PCBs and possibly methylmercury.

  13. Self-Healing Hydrogel Pore-Filled Water Filtration Membranes.

    PubMed

    Getachew, Bezawit A; Kim, Sang-Ryoung; Kim, Jae-Hong

    2017-01-17

    Damages to water filtration membranes during installation and operation are known to cause detrimental loss of the product water quality. Membranes that have the ability to self-heal would recover their original rejection levels autonomously, bypassing the need for costly integrity monitoring and membrane replacement practices. Herein, we fabricated hydrogel pore-filled membranes via in situ graft polymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) onto microporous poly(ether sulfone) (PES) substrates and successfully demonstrated their self-healing ability. Covalent attachment of the hydrogel to the substrate was essential for stable membrane performance. The membranes autonomously restore their particle rejection up to 99% from rejection levels as low as 30% after being physically damaged. We attribute the observed self-healing property to swelling of the pore-filling hydrogel into the damage site, strong hydrogen bonding, and molecular interdiffusion. The results of this study show that hydrogel pore-filled membranes are a promising new class of materials for fabricating self-healing membranes.

  14. Pore water colloid properties in argillaceous sedimentary rocks.

    PubMed

    Degueldre, Claude; Cloet, Veerle

    2016-11-01

    The focus of this work is to evaluate the colloid nature, concentration and size distribution in the pore water of Opalinus Clay and other sedimentary host rocks identified for a potential radioactive waste repository in Switzerland. Because colloids could not be measured in representative undisturbed porewater of these host rocks, predictive modelling based on data from field and laboratory studies is applied. This approach allowed estimating the nature, concentration and size distributions of the colloids in the pore water of these host rocks. As a result of field campaigns, groundwater colloid concentrations are investigated on the basis of their size distribution quantified experimentally using single particle counting techniques. The colloid properties are estimated considering data gained from analogue hydrogeochemical systems ranging from mylonite features in crystalline fissures to sedimentary formations. The colloid concentrations were analysed as a function of the alkaline and alkaline earth element concentrations. Laboratory batch results on clay colloid generation from compacted pellets in quasi-stagnant water are also reported. Experiments with colloids in batch containers indicate that the size distribution of a colloidal suspension evolves toward a common particle size distribution independently of initial conditions. The final suspension size distribution was found to be a function of the attachment factor of the colloids. Finally, calculations were performed using a novel colloid distribution model based on colloid generation, aggregation and sedimentation rates to predict under in-situ conditions what makes colloid concentrations and size distributions batch- or fracture-size dependent. The data presented so far are compared with the field and laboratory data. The colloid occurrence, stability and mobility have been evaluated for the water of the considered potential host rocks. In the pore water of the considered sedimentary host rocks, the clay

  15. Elucidating the controls on the Mg isotopic composition of marine pore fluids

    NASA Astrophysics Data System (ADS)

    Chanda, P.; Fantle, M.

    2013-12-01

    The Sr and Mg isotopic composition of pore fluids and carbonates from the Neogene section of Ocean Drilling Project Site 806B are reported (87Sr/86Sr and δ26Mg, measured using a Thermo Scientific Neptune Plus multi-collector ICP-MS). Site 806B, located on the northern margin of the Ontong Java Plateau, hosts a thick (776 m cored, depth to basement ~ 1200 m), relatively continuous, carbonate-rich section (between 83 and 96% CaCO3). Our goal in the current study is to use the Sr and Mg isotope data of pore fluids and carbonates to address open questions regarding (1) the extent to which the pore fluid chemistry is overprinted by calcite recrystallization, (2) the effects of diagenesis on bulk carbonate chemistry, and (3) the likelihood of preserving secular seawater δ26Mg trends in pore fluids. Accordingly, the current study compares and contrasts the isotopic and elemental data between adjacent ODP Sites 806B and 807A, which have similar depositional histories, carbonate contents, and pore fluid chemistries. The measured 87Sr/86Sr ratios of pore fluids at 806B range smoothly from 0.70914 at 4.45 mbsf to 0.70851 at 509.3 mbsf, similar (though offset relative) to the bulk carbonate trend (0.70918 to 0.70877 between 1.11 and 501.94 mbsf). The δ26MgDSM3 of 806B pore fluids generally increases from -0.86‰ at 4.45 mbsf to -0.17‰ at 679.0 mbsf. The overall trend is consistent with previously collected δ26Mg data at 807A [1]; there is, however, a significant difference in pore fluid δ26Mg between the two sites at depths of 300 to 600 mbsf. At these depths, 806B pore fluid δ26Mg values are +0.2 to 0.3‰ relative to 807A at similar depths [1]. The application of a depositional reactive transport model to the Sr isotope data suggests that bulk carbonate recrystallization rates at 806B are similar to those at 807A (<2%/Ma) [2]. An iterative model construct is employed to evaluate the dominant controls on the δ26Mg of marine pore fluids; specifically the relative

  16. The Water Retention Curves in THF Hydrate-Bearing Sediments - Experimental Measurement and Pore Scale Simulation

    NASA Astrophysics Data System (ADS)

    Mahabadi, N.; Zheng, X.; Dai, S.; Seol, Y.; Zapata, C.; Yun, T.; Jang, J.

    2015-12-01

    The water retention curve (WRC) of hydrate-bearing sediments is critically important to understand the behaviour of hydrate dissociation for gas production. Most gas hydrates in marine environment have been formed from an aqueous phase (gas-dissolved water). However, the gas hydrate formation from an aqueous phase in a laboratory requires long period due to low gas solubility in water and is also associated with many experimental difficulties such as hydrate dissolution, difficult hydrate saturation control, and dynamic hydrate dissolution and formation. In this study, tetrahydrofuran (THF) is chosen to form THF hydrate because the formation process is faster than gas hydrate formation and hydrate saturation is easy to control. THF hydrate is formed at water-excess condition. Therefore, there is only water in the pore space after a target THF hydrate saturation is obtained. The pore habit of THF hydrate is investigated by visual observation in a transparent micromodel and X-ray computed tomography images; and the water retention curves are obtained under different THF hydrate saturation conditions. Targeted THF hydrate saturations are Sh=0, 0.2, 0.4, 0.6 and 0.8. Results shown that at a given water saturation the capillary pressure increases as THF hydrate saturation increases. And the gas entry pressure increases with increasing hydrate saturation. The WRC obtained by experiments is also compared with the results of a pore-network model simulation and Lattice Boltzmann Method. The fitting parameters of van Genuchten equation for different hydrate saturation conditions are suggested for the use as input parameters of reservoir simulators.

  17. Pore-water pressure events during the in situ heat transfer experiment simulation: Piezometer probe technology

    SciTech Connect

    Bennett, R.H.; Burns, J.T.; Li, H.; Percival, C.M.; Lipkin, J.

    1987-01-01

    Single sensor piezometer probes, 8mm in diameter were developed and tested for deep-ocean geotechnical investigations in support of the Subseabed Disposal Program. Two probes were tested in a hyperbaric chamber pressurized to 55 MPa (8000 psi) during a scaled (0.28: 1) simulation experiment conducted at the David Taylor Naval Ship Research and Development Center (DTNSRDC) in Annapolis, Md. Testing was performed for 30 days with the probes inserted in reconstituted illitic marine sediment. Small differential pore-water pressures were generated in response to both mechanically and thermally generated forcing functions. The piezometers sensed very small (approximately 1.7 kPa (0.25 psi)) pore water pressure events during the process of carrying out other experimental objectives. The pressure sensors exhibited excellent sensitivity and stability during other deep-ocean simulated laboratory pressure tests for periods of up to 750 hours. In addition to the measurements of ambient and dynamic pore pressure response to environmental forces, the piezometer test data can be used to derive the in situ undrained shear strengths and permeabilities of seabed sediments. The piezometer probe technology is providing a quantitative means of assessing important geotechnical parameters of fine-grained seabed deposits. 22 refs., 28 figs., 10 tabs.

  18. A new collector for in situ pore water sampling in wetland sediment.

    PubMed

    Gao, Feng; Deng, Jiancai; Li, Qinqin; Hu, Liuming; Zhu, Jinge; Hang, Hongjuan; Hu, Weiping

    2012-01-01

    Currently available pore water samplers generally do not allow continuous monitoring of temporal variations in pore water composition. Therefore, a new type of pore water collector was designed and constructed. These collectors were constructed of polyvinyl chloride (PVC) materials, including PVC tubing with one end sealed and another end topped with a removable PVC screw-cap. A row of holes was drilled 10 cm from the sealed end of each collector. These new collectors were deployed in different layers of the sediment in a constructed wetland in Lake Taihu, China, to reveal variations in the nutrient composition of pore water with high spatial and temporal resolution. Specifically, the collectors were driven into the sediment, and the pore water flowed into the tubing via gravity. The pore water was then sampled from the PVC tubing using a portable vacuum pump, and then was taken to the lab within 20 min for analysis of the dissolved oxygen (DO) and nutrient concentration. The DO concentration of the pore water was below the detection limit for all samples, indicating that the pore water was probably not influenced by the air and that the water in the collector tube was representative of the pore water. These findings suggest that the collector is capable of measuring the temporal and spatial variations in the nutrient concentrations in pore water. Furthermore, the inexpensive material, ease of construction, minimal disturbance to the sediment and applicability for wetland sediments are advantages of the collector presented here compared with traditional pore water sampling techniques.

  19. Advection within shallow pore waters of a coastal lagoon, Florida

    USGS Publications Warehouse

    Cable, J.E.; Martin, Jonathan B.; Swarzenski, Peter W.; Lindenberg, Mary K.; Steward, Joel

    2004-01-01

    Ground water sources can be a significant portion of a local water budget in estuarine environments, particularly in areas with high recharge rates, transmissive aquifers, and permeable marine sediments. However, field measurements of ground water discharge are often incongruent with ground water flow modeling results, leaving many scientists unsure which estimates are accurate. In this study, we find that both measurements and model results are reasonable. The difference between estimates apparently results from the sources of water being measured and not the techniques themselves. In two locations in the Indian River Lagoon estuarine system, we found seepage meter rates similar to rates calculated from the geochemical tracers 222Rn and 226Ra. Ground water discharge rates ranged from 4 to 9 cm/d using seepage meters and 3 to 20 cm/d using 222Rn and 226Ra. In contrast, in comparisons to other studies where finite element ground water flow modeling was used, much lower ground water discharge rates of ∼0.05 to 0.15 cm/d were estimated. These low rates probably represent discharge of meteoric ground water from land-recharged aquifers, while the much higher rates measured with seepage meters, 222Rn, and 226Ra likely include an additional source of surface waters that regularly flush shallow (< 1 m depth) sediments. This resultant total flow of mixed land-recharged water and recirculated surface waters contributes to the total biogeochemical loading in this shallow estuarine environment.

  20. Processes in the pore waters of peat deposits

    SciTech Connect

    Levshenko, T.V.; Efremova, A.G.; Galkina, Z.M.; Surkova, T.E.; Tolstov, K.A.

    1983-01-01

    The composition of the waters of modern peat bogs that have developed in the intracontinental regions under the conditions of bogs of the high-moor, mixed, and lowmoor types have been investigated for the case of a number of peat deposits of the Smolensk, Volgorad, and Pskov provinces. During the work the pH of the deposits and the C1-, Alk, SO/sup 2/-, Ca/sup 2 +/, Mg/sup 2 +/, K- contents of the pore water of modern peat beds were studied. The thickness of the deposits studied amounted to 5-7 m. Samples were taken every 0.5 m in depth. The water was separated from the deposits by pressing out.

  1. Pore Water PAH Transport in Amended Sediment Caps

    NASA Astrophysics Data System (ADS)

    Gidley, P. T.; Kwon, S.; Ghosh, U.

    2009-05-01

    Capping is a common remediation strategy for contaminated sediments that creates a physical barrier between contaminated sediments and the water column. Diffusive flux of contaminants through a sediment cap is small. However, under certain hydrodynamic conditions such as groundwater potential and tidal pumping, groundwater advection can accelerate contaminant transport. Hydrophobic organic contaminants such as polycyclic aromatic hydrocarbons (PAHs) could be transported through the cap under advective conditions. To better understand PAH migration under these conditions, physical models of sediment caps were evaluated in the laboratory through direct measurement of pore water using solid phase micro-extraction with gas chromatography and mass spectrometry. Contaminated sediment and capping material was obtained from an existing Superfund site that was capped at Eagle Harbor, Washington. A PAH dissolution model linked to an advection-dispersion equation with retardation using published organic carbon-water partitioning coefficients (Koc) was compared to measured PAHs in the sediment and cap porewater of the physical model.

  2. Submarine weathering of silicate minerals and the extent of pore water freshening at active continental margins

    NASA Astrophysics Data System (ADS)

    Scholz, Florian; Hensen, Christian; Schmidt, Mark; Geersen, Jacob

    2013-01-01

    In order to investigate how submarine weathering processes may affect the water balance of sediments at convergent plate margins, six sediment cores were retrieved off Central Chile at water depth between ˜800 and 4000 m. The sediment solid phase was analyzed for its major element composition and the pore fluids were analyzed for dissolved sulfate, sulfide, total alkalinity, major cations, chloride, bromide, iodide, hydrocarbons as well as the carbon isotopic composition of methane. Because of negligible weathering on land, surface sediments off Central Chile are rich in reactive silicate minerals and have a bulk composition similar to volcanic rocks in the adjacent Andes. Deep-sourced fluxes of alkalinity, cations and chloride indicate that silicate minerals are subject to weathering in the forearc during burial. Comparison of deep-sourced signals with data from nearby Ocean Drilling Program Sites reveals two different types of weathering processes: In shallow (tens of meters), methanic sediments of slope basins with high organic carbon burial rates, reactive silicate minerals undergo incongruent dissolution through reaction with CO2 from methanogenesis. At greater burial depth (hundreds of meters), silicate weathering is dominated by authigenic smectite formation. This process is accompanied by uptake of water into the clay interlayers thus leading to elevated salinities in the surrounding pore water. Deep-seated smectite formation is more widespread than shallow silicate dissolution, as it is independent from the availability of CO2 from methanogenesis. Although solute transport is not focused enough to form cold seeps in the proper sense, tectonically induced, diffuse fluid flow transfers the deep-seated signal of smectite formation into the shallow sediments. The temperature-controlled conversion of smectite to illite is considered the most important dehydration process in marine forearc environments (depth of kilometers). However, in agreement with other

  3. Mechanics of water pore formation in lipid membrane under electric field

    NASA Astrophysics Data System (ADS)

    Bu, Bing; Li, Dechang; Diao, Jiajie; Ji, Baohua

    2017-02-01

    Transmembrane water pores are crucial for substance transport through cell membranes via membrane fusion, such as in neural communication. However, the molecular mechanism of water pore formation is not clear. In this study, we apply all-atom molecular dynamics and bias-exchange metadynamics simulations to study the process of water pore formation under an electric field. We show that water molecules can enter a membrane under an electric field and form a water pore of a few nanometers in diameter. These water molecules disturb the interactions between lipid head groups and the ordered arrangement of lipids. Following the movement of water molecules, the lipid head groups are rotated and driven into the hydrophobic region of the membrane. The reorientated lipid head groups inside the membrane form a hydrophilic surface of the water pore. This study reveals the atomic details of how an electric field influences the movement of water molecules and lipid head groups, resulting in water pore formation.

  4. Methods for pore water extraction from unsaturated zone tuff, Yucca Mountain, Nevada

    USGS Publications Warehouse

    Scofield, K.M.

    2006-01-01

    Assessing the performance of the proposed high-level radioactive waste repository at Yucca Mountain, Nevada, requires an understanding of the chemistry of the water that moves through the host rock. The uniaxial compression method used to extract pore water from samples of tuffaceous borehole core was successful only for nonwelded tuff. An ultracentrifugation method was adopted to extract pore water from samples of the densely welded tuff of the proposed repository horizon. Tests were performed using both methods to determine the efficiency of pore water extraction and the potential effects on pore water chemistry. Test results indicate that uniaxial compression is most efficient for extracting pore water from nonwelded tuff, while ultracentrifugation is more successful in extracting pore water from densely welded tuff. Pore water splits collected from a single nonwelded tuff core during uniaxial compression tests have shown changes in pore water chemistry with increasing pressure for calcium, chloride, sulfate, and nitrate. Pore water samples collected from the intermediate pressure ranges should prevent the influence of re-dissolved, evaporative salts and the addition of ion-deficient water from clays and zeolites. Chemistry of pore water splits from welded and nonwelded tuffs using ultracentrifugation indicates that there is no substantial fractionation of solutes.

  5. Effects of a nearshore wastewater discharge: Water column and sediment pore water toxicity

    SciTech Connect

    Krause, P.R.; Carr, R.S.

    1995-12-31

    The relationship between water column and sediment pore water toxicity was investigated near a municipal-industrial wastewater discharge in southern Texas. Toxicity associated with effluent distributions in the water column are known to vary in both time and space. Toxicity of sediment, however, is often more stable over time. Sediment can serve as a long-term integrator of toxicity in areas subject to chronic exposure of effluents. This study addressed the relationship between water column toxicity and that found in the sediments on both spatial and temporal scales. Four 2 Km transacts were established around a nearshore wastewater outfall. Eight stations along each transact were sampled for both surface waters and sediment pore water toxicity. Toxicity was determined using a modified sea urchin fertilization test. Surface waters were sampled and tested for eight consecutive months, while sediment pore waters were sampled on three occasions over the length of this study. Results have shown that toxicity in receiving waters was a good indicator to trace movements of the highly variable effluent plume. The distribution of effluent in the water column, and hence water column toxicity, was primarily driven by local wind conditions. Toxicity in sediment porewater was, much less variable and more evenly distributed over the study site. Sediment pore water toxicity was also a good predictor of the distribution of benthic infaunal invertebrates over much of the study site.

  6. The mineral dissolution rate conundrum: Insights from reactive transport modeling of U isotopes and pore fluid chemistry in marine sediments

    NASA Astrophysics Data System (ADS)

    Maher, Kate; Steefel, Carl I.; DePaolo, Donald J.; Viani, Brian E.

    2006-01-01

    Pore water chemistry and 234U/ 238U activity ratios from fine-grained sediment cored by the Ocean Drilling Project at Site 984 in the North Atlantic were used as constraints in modeling in situ rates of plagioclase dissolution with the multicomponent reactive transport code Crunch. The reactive transport model includes a solid-solution formulation to enable the use of the 234U/ 238U activity ratios in the solid and fluid as a tracer of mineral dissolution. The isotopic profiles are combined with profiles of the major element chemistry (especially alkalinity and calcium) to determine whether the apparent discrepancy between laboratory and field dissolution rates still exists when a mechanistic reactive transport model is used to interpret rates in a natural system. A suite of reactions, including sulfate reduction and methane production, anaerobic methane oxidation, CaCO 3 precipitation, dissolution of plagioclase, and precipitation of secondary clay minerals, along with diffusive transport and fluid and solid burial, control the pore fluid chemistry in Site 984 sediments. The surface area of plagioclase in intimate contact with the pore fluid is estimated to be 6.9 m 2/g based on both grain geometry and on the depletion of 234U/ 238U in the sediment via α-recoil loss. Various rate laws for plagioclase dissolution are considered in the modeling, including those based on (1) a linear transition state theory (TST) model, (2) a nonlinear dependence on the undersaturation of the pore water with respect to plagioclase, and (3) the effect of inhibition by dissolved aluminum. The major element and isotopic methods predict similar dissolution rate constants if additional lowering of the pore water 234U/ 238U activity ratio is attributed to isotopic exchange via recrystallization of marine calcite, which makes up about 10-20% of the Site 984 sediment. The calculated dissolution rate for plagioclase corresponds to a rate constant that is about 10 2 to 10 5 times smaller than

  7. Organic geochemistry and pore water chemistry of sediments from Mangrove Lake, Bermuda

    USGS Publications Warehouse

    Hatcher, P.G.; Simoneit, B.R.T.; MacKenzie, F.T.; Neumann, A.C.; Thorstenson, D.C.; Gerchakov, S.M.

    1982-01-01

    Mangrove Lake, Bermuda, is a small coastal, brackish-water lake that has accumulated 14 m of banded, gelatinous, sapropelic sediments in less than 104 yr. Stratigraphic evidence indicates that Mangrove Lake's sedimentary environment has undergone three major depositional changes (peat, freshwater gel, brackish-water gel) as a result of sea level changes. The deposits were examined geochemically in an effort to delineate sedimentological and diagenetic changes. Gas and pore water studies include measurements of sulfides, ammonia, methane, nitrogen gas, calcium, magnesium, chloride, alkalinity, and pH. Results indicate that sulfate reduction is complete, and some evidence is presented for bacterial denitrification and metal sulfide precipitation. The organic-rich sapropel is predominantly algal in origin, composed mostly of carbohydrates and insoluble macromolecular organic matter called humin with minor amounts of proteins, lipids, and humic acids. Carbohydrates and proteins undergo hydrolysis with depth in the marine sapropel but tend to be preserved in the freshwater sapropel. The humin, which has a predominantly aliphatic structure, increases linearly with depth and composes the greatest fraction of the organic matter. Humic acids are minor components and are more like polysaccharides than typical marine humic acids. Fatty acid distributions reveal that the lipids are of an algal and/or terrestrial plant source. Normal alkanes with a total concentration of 75 ppm exhibit two distribution maxima. One is centered about n-C22 with no odd/even predominance, suggestive of a degraded algal source. The other is centered at n-C31 with a distinct odd/even predominance indicative of a vascular plant origin. Stratigraphic changes in the sediment correlate to observed changes in the gas and pore water chemistry and the organic geochemistry. ?? 1982.

  8. Transient streaming potentials under varying pore-water ionic strength

    NASA Astrophysics Data System (ADS)

    Malama, B.

    2014-12-01

    Streaming potentials (SP) are generated when polar fluids such as groundwater flow through porous media that have charged mineral surfaces. This is due to the flow-shearing of the diffuse layer of the electric double layer (EDL), which is known to form in the fluid phase at the fluid-rock interface. Previous works have suggested that the EDL vanishes at high pore-fluid ionic strengths resulting in vanishing SP signals. However, recent observations in sea-water intrusion applications by Jackson and coworkers indicate that measurable SP signals are obtainable in flows of fluids with high ionic strengths through silica sand. We demonstrate the repeatability of these observations through a series of laboratory flow experiments performed on 98% silica sand in a falling-head permeameter with brines of concentrations ranging from 0.001M to about 5 M NaCl. The results of the experiments, which clearly show measurable SP signals even at the highest concentration of 5 M NaCl, are reported. They are also used to estimate the hydraulic conductivity and electrokinetic coupling coefficient. The linearity assumption for the relation between pressure and SP differentials is evaluated for high pore-water NaCl concentrations. Additionally, displacement of one brine by another of different NaCl concentration yields dramatic transient SP responses that may be harnessed in the development of early-detection/warning technologies for sea-water intrusion applications. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. This research is funded by WIPP programs administered by the Office of Environmental Management (EM) of the U.S Department of Energy.

  9. Toxicity of ammonia in pore-water and in the water column to freshwater benthic invertebrates

    SciTech Connect

    Whiteman, F.W.; Kahl, M.D.; Rau, D.M.; Balcer, M.D.; Ankley, G.T.

    1994-12-31

    Ammonia has been mentioned as both a primary toxicant and a factor that can produce false positive results in laboratory sediment tests using benthic invertebrates. This study developed a sediment dosing system that percolates an ammonia solution through sediment to achieve target porewater ammonia concentrations that remain stable over four and ten day spiked sediment tests. Ten day flow-through water-only tests and ten day spiked sediment tests were used to determine the toxicity of ammonia in the water column and in the sediment pore-water to the oligochaete Lumbriculus variegatus and the midge Chironomus tentans. Four-day tests were run with the amphipod Hyalella azteca. The relationship between water column ammonia toxicity and sediment pore-water ammonia toxicity is influenced by the organism`s association with the sediment. For Lumbriculus variegatus and Chironomus tentans that burrow into the sediment and are in direct contact with the porewater, the pore-water LC50 for ammonia is 30--40% higher than the water-only LC50 for each species. Hyalella azteca is epibenthic and avoids ammonia spiked sediment, thus ammonia in the water column is considerably more toxic than the pore-water ammonia with the porewater LC50 about 800% higher than the water only LC50.

  10. Effects of handling, temperature and storage time on sediment and pore-water chemistry and toxicity

    SciTech Connect

    Lasier, P.J.; Winger, P.V.; Jackson, B.P.

    1994-12-31

    Effects of sediment disturbance, storage temperature (230 C and 40 C) and storage time on chemistry and toxicity of sediment and pore water were evaluated using two sediments (sandy freshwater and organic estuarine) contaminated with metals. Solid-phase (10 d with water renewal) and pore-water (96-h static) toxicity tests with Hyalella azteca were conducted upon collection and at two week intervals for 8--10 weeks. Chemistries (redox, pH, conductivity, alkalinity, ammonia, trace metals, major cations and anions) were measured at each toxicity testing interval. Following extraction, pore-water chemistry changed significantly during the initial 96 h due to oxidation reactions and CO{sub 2} equilibration. Pore water collected in situ was slightly less toxic and had major differences in water chemistry compared to pore water extracted from homogenized sediment. Storage temperature and time significantly influenced pore-water toxicity and chemistry, but had minimal effect on solid-phase toxicity. After four weeks, the highly-toxic sandy sediment became slightly less toxic in solid-phase tests and Significantly less toxic in pore-water tests, coinciding with changes in trace-metal concentrations, activities, and speciation. The estuarine sediment became slightly more toxic in both solid-phase and pore-water tests after four weeks, but returned to original levels after six and eight weeks. Sediment disturbance, storage temperature, and storage time significantly influenced toxicity and pore-water chemistry.

  11. Clinically-Compatible MRI Strategies for Discriminating Bound and Pore Water in Cortical Bone

    PubMed Central

    Horch, R. Adam; Gochberg, Daniel F.; Nyman, Jeffry S.; Does, Mark D.

    2012-01-01

    Advances in modern MRI pulse sequences have enabled clinically-practical cortical bone imaging. Human cortical bone is known to contain a distribution of T1 and T2 components attributed to bound and pore water, although clinical imaging approaches have yet to discriminate bound from pore water on the basis of their relaxation properties. Herein, two clinically-compatible MRI strategies are proposed for selectively imaging either bound or pore water by utilizing differences in their T1s and T2s. The strategies are validated in a population of ex vivo human cortical bones, and estimates obtained for bound and pore water are compared to bone mechanical properties. Results show that the two MRI strategies provide good estimates of bound and pore water that correlate to bone mechanical properties. As such, the strategies for bound and pore water-discrimination shown herein should provide diagnostically useful tools for assessing bone fracture risk, once applied to clinical MRI. PMID:22294340

  12. Excess pore water pressure due to ground surface erosion

    NASA Astrophysics Data System (ADS)

    Llewellyn Smith, Stefan; Gagniere, Steven

    2015-11-01

    Erosional unloading is the process whereby surface rocks and soil are removed by external processes, resulting in changes to water pressure within the underlying aquifer. We consider a mathematical model of changes in excess pore water pressure as a result of erosional unloading. Neuzil and Pollock (1983) studied this process in the case where the water table initially coincides with the surface. In contrast, we analyze an ideal aquifer which is initially separated from the ground surface by an unsaturated zone. The model is solved using Laplace Transform methods in conjunction with a boost operator derived by King (1985). The boost operator is used to boost the solution (in the Laplace domain) to a frame of reference moving at constant velocity with respect to the original frame. We use our solution to analyze the evolution of the pressure during erosion of the aquifer itself for small and large erosion rates. We also examine the flux at the upper boundary as a function of time and present a quasi-steady approximation valid for very small erosion rates in the appendix.

  13. Influence of Water Table Depth on Pore Water Chemistry and Trihalomethane Formation Potential in Peatlands.

    PubMed

    Gough, Rachel; Holliman, Peter J; Fenner, Nathalie; Peacock, Mike; Freeman, Christopher

    2016-02-01

    Drained peatland catchments are reported to produce more colored, dissolved organic carbon (DOC)-rich water, presenting problems for potable water treatment. The blocking of peatland drainage ditches to restore the water table is increasingly being considered as a strategy to address this deterioration in water quality. However, the effect of ditch blocking on the potential of DOC to form trihalomethanes (THMs) has not been assessed. In this study, the effect of peat rewetting on pore water DOC concentration and characteristics (including THM formation potential [THMFP]) was assessed over 12 months using peat cores collected from two drained peatland sites. The data show little evidence of differences in DOC concentration or characteristics between the different treatments. The absence of any difference in the THMFP of pore water between treatments suggests that, in the short term at least, ditch blocking may not have an effect on the THMFP of waters draining peatland catchments.

  14. Water and Solute Transport Governed by Tunable Pore Size Distributions in Nanoporous Graphene Membranes.

    PubMed

    Jang, Doojoon; Idrobo, Juan-Carlos; Laoui, Tahar; Karnik, Rohit

    2017-10-10

    Nanoporous graphene has the potential to advance membrane separations by offering high selectivity with minimal resistance to flow, but how mass transport depends on the structure of pores in this atomically thin membrane is poorly understood. Here, we investigate the relationship between tunable pore creation using ion bombardment and oxygen plasma etching, the resulting pore size distributions, and the consequent water and solute transport. Through tuning of the pore creation process, we demonstrate nanofiltration membranes that reject small molecules but offer high permeance to water or monovalent ions. Theoretical multiscale modeling of transport across the membranes reveals a disproportionate contribution of large pores to osmotic water flux and diffusive solute transport and captures the observed trends in transport measurements except for the smallest pores. This work provides insights into the effects of graphene pore size distribution and support layer on transport and presents a framework for designing atomically thin membranes.

  15. Integrated landslide monitoring: rainfalls, pore water pressures and surface movements

    NASA Astrophysics Data System (ADS)

    Berti, M.; Casula, G.; Elmi, C.; Fabris, M.; Ghirotti, M.; Loddo, F.; Mora, P.; Pesci, A.; Simoni, A.

    2003-04-01

    Rainfall-induced landslides involving clay-rich soils are widely represented in the Apennines. They cover up to 30% of the slopes forming the relief constituted by chaotic clayey units and are typically subject to repeated reactivations of the movement which are often triggered by a series of discrete failures located in the upper part (headscarp). Failures and movement can then propagate downslope and reactivate the whole landslide deposit which displays a typical elongated body, limited depth and a fan-shaped toe as a result of successive slow earth-flow like movements. An experimental monitoring programme was designed and is currently operating on the Rocca Pitigliana landslide whose characteristics well represent the above described type of movements. Its last parossistic movement date back to 1999 and, since then, remedial works were realized on behalf of local authorities. They basically consist of surficial and deep drainage works located on the landslide body. Experimental activities focus on the main headscarp whose morphology and sub-surface water circulation scheme were unaffected by the interventions. The monitoring approach includes measuring rainfalls and pore-pressure responses in both saturated and unsaturated soils. Surficial movements are continuously measured by means of GPS permanent stations and by wire extensometers which allow real time control of headscarp activity. Main aim of the monitoring activities is to provide experimental data, which can be used to test various existing hydrologic models and to identify triggering conditions. Since the ‘70s, many hydrologic models have been proposed to describe the pore water pressure distribution within the soil and its response to precipitation. The topic has recently drawn growing attention because of the recognized importance in landslide triggering but still experimental data are very much needed in order to obtain and validate capable predicting tools. This is mostly due to the multiple and

  16. Linking basin-scale and pore-scale gas hydrate distribution patterns in diffusion-dominated marine hydrate systems

    NASA Astrophysics Data System (ADS)

    Nole, Michael; Daigle, Hugh; Cook, Ann E.; Hillman, Jess I. T.; Malinverno, Alberto

    2017-02-01

    The goal of this study is to computationally determine the potential distribution patterns of diffusion-driven methane hydrate accumulations in coarse-grained marine sediments. Diffusion of dissolved methane in marine gas hydrate systems has been proposed as a potential transport mechanism through which large concentrations of hydrate can preferentially accumulate in coarse-grained sediments over geologic time. Using one-dimensional compositional reservoir simulations, we examine hydrate distribution patterns at the scale of individual sand layers (1-20 m thick) that are deposited between microbially active fine-grained material buried through the gas hydrate stability zone (GHSZ). We then extrapolate to two-dimensional and basin-scale three-dimensional simulations, where we model dipping sands and multilayered systems. We find that properties of a sand layer including pore size distribution, layer thickness, dip, and proximity to other layers in multilayered systems all exert control on diffusive methane fluxes toward and within a sand, which in turn impact the distribution of hydrate throughout a sand unit. In all of these simulations, we incorporate data on physical properties and sand layer geometries from the Terrebonne Basin gas hydrate system in the Gulf of Mexico. We demonstrate that diffusion can generate high hydrate saturations (upward of 90%) at the edges of thin sands at shallow depths within the GHSZ, but that it is ineffective at producing high hydrate saturations throughout thick (greater than 10 m) sands buried deep within the GHSZ. Furthermore, we find that hydrate in fine-grained material can preserve high hydrate saturations in nearby thin sands with burial.Plain Language SummaryThis study combines one-, two-, and three-dimensional simulations to explore one potential process by which methane dissolved in <span class="hlt">water</span> beneath the seafloor can be converted into solid methane hydrate. This work specifically</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18589990','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18589990"><span>Sediment toxicity of a rapidly biodegrading nonionic surfactant: Comparing the equilibrium partitioning approach with measurements in <span class="hlt">pore</span> <span class="hlt">water</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Droge, Steven T J; Postma, Jaap F; Hermens, Joop L M</p> <p>2008-06-01</p> <p>The equilibrium partitioning theory (EqP) assumes that the toxicity of nonionic surfactants in sediment can be predicted from <span class="hlt">water</span>-only toxicity data as long as the effect concentrations are properly normalized for chemical activity. Therefore, in <span class="hlt">marine</span> sediment toxicity tests with the model alcohol ethoxylate (AE), C12EO8, freely dissolved concentrations were both measured via solid-phase microextraction and predicted using sorption coefficients. In fully equilibrated test systems (including the overlying <span class="hlt">water</span>), both methods showed that concentrations in the <span class="hlt">pore</span> <span class="hlt">water</span> of the spiked sediment layer causing 50% mortality (LC50) to the amphipod Corophium volutator were in the same range as LC50 values for amphipods exposed to AE in seawater only. In the sediment systems, AE concentrations in the <span class="hlt">pore</span> <span class="hlt">water</span> remained constant up to 15 days, while concentrations in the <span class="hlt">water</span> overlying the sediment decreased to less than 1% of initial concentrations within 6 days due to biodegradation. In such disequilibrated test systems, C. volutator survived <span class="hlt">pore</span> <span class="hlt">water</span> dissolved concentrations that were above the LC50. Apparently, this burrowing amphipod is able to exploit the low chemical activity in the overlying <span class="hlt">water</span> as a refuge from sediment exposure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/653994','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/653994"><span>The one-dimensional compression method for extraction of <span class="hlt">pore</span> <span class="hlt">water</span> from unsaturated tuff and effects on <span class="hlt">pore-water</span> chemistry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Higgins, J.D.; Burger, P.A.; Yang, L.C.</p> <p>1997-12-31</p> <p>Study of the hydrologic system at Yucca Mountain, Nevada, requires extraction of <span class="hlt">pore-water</span> samples from unsaturated tuff bedrock. Two generations of compression cells have been designed and tested for extracting representative, unaltered <span class="hlt">pore-water</span> samples from unsaturated tuff cores. The one-dimensional compression cell has a maximum compressive stress rating of 552 MPa. Results from 86 tests show that the minimum degree of saturation for successful extraction of <span class="hlt">pore</span> <span class="hlt">water</span> was about 14% for non welded tuff and about 61% for densely welded tuff. The high-pressure, one-dimensional compression cell has a maximum compressive stress rating of 827 MPa. Results from 109 tests show that the minimum degree of saturation for successful extraction of <span class="hlt">pore</span> <span class="hlt">water</span> was about 7.5% for non welded tuff and about 34% for densely welded tuff. Geochemical analyses show that, in general, there is a decrease in ion concentration of <span class="hlt">pore</span> <span class="hlt">waters</span> as extraction pressures increase. Only small changes in <span class="hlt">pore-water</span> composition occur during the one-dimensional extraction test.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol26/pdf/CFR-2012-title40-vol26-sec227-31.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol26/pdf/CFR-2012-title40-vol26-sec227-31.pdf"><span>40 CFR 227.31 - Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality... § 227.31 Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria. Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria means the criteria given for <span class="hlt">marine</span> <span class="hlt">waters</span> in the EPA publication “Quality Criteria for Water” as published in...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol24/pdf/CFR-2010-title40-vol24-sec227-31.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol24/pdf/CFR-2010-title40-vol24-sec227-31.pdf"><span>40 CFR 227.31 - Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality... § 227.31 Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria. Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria means the criteria given for <span class="hlt">marine</span> <span class="hlt">waters</span> in the EPA publication “Quality Criteria for Water” as published in...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_4 --> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol26/pdf/CFR-2013-title40-vol26-sec227-31.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol26/pdf/CFR-2013-title40-vol26-sec227-31.pdf"><span>40 CFR 227.31 - Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality... § 227.31 Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria. Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria means the criteria given for <span class="hlt">marine</span> <span class="hlt">waters</span> in the EPA publication “Quality Criteria for Water” as published in...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol25/pdf/CFR-2014-title40-vol25-sec227-31.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol25/pdf/CFR-2014-title40-vol25-sec227-31.pdf"><span>40 CFR 227.31 - Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality... § 227.31 Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria. Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria means the criteria given for <span class="hlt">marine</span> <span class="hlt">waters</span> in the EPA publication “Quality Criteria for Water” as published in...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol25/pdf/CFR-2011-title40-vol25-sec227-31.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol25/pdf/CFR-2011-title40-vol25-sec227-31.pdf"><span>40 CFR 227.31 - Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality... § 227.31 Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria. Applicable <span class="hlt">marine</span> <span class="hlt">water</span> quality criteria means the criteria given for <span class="hlt">marine</span> <span class="hlt">waters</span> in the EPA publication “Quality Criteria for Water” as published in...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19366586','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19366586"><span>Extrusion of transmitter, <span class="hlt">water</span> and ions generates forces to close fusion <span class="hlt">pore</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tajparast, M; Glavinović, M I</p> <p>2009-05-01</p> <p>During exocytosis the fusion <span class="hlt">pore</span> opens rapidly, then dilates gradually, and may subsequently close completely, but what controls its dynamics is not well understood. In this study we focus our attention on forces acting on the <span class="hlt">pore</span> wall, and which are generated solely by the passage of transmitter, ions and <span class="hlt">water</span> through the open fusion <span class="hlt">pore</span>. The transport through the charged cylindrical nano-size <span class="hlt">pore</span> is simulated using a coupled system of Poisson-Nernst-Planck and Navier-Stokes equations and the forces that act radially on the wall of the fusion <span class="hlt">pore</span> are then estimated. Four forces are considered: a) inertial force, b) pressure, c) viscotic force, and d) electrostatic force. The inertial and viscotic forces are small, but the electrostatic force and the pressure are typically significant. High vesicular pressure tends to open the fusion <span class="hlt">pore</span>, but the pressure induced by the transport of charged particles (glutamate, ions), which is predominant when the <span class="hlt">pore</span> wall charge density is high tends to close the <span class="hlt">pore</span>. The electrostatic force, which also depends on the charge density on the <span class="hlt">pore</span> wall, is weakly repulsive before the <span class="hlt">pore</span> dilates, but becomes attractive and pronounced as the <span class="hlt">pore</span> dilates. Given that the vesicular concentration of free transmitter can change rapidly due to the release, or owing to the dissociation from the gel matrix, we evaluated how much and how rapidly a change of the vesicular K(+)-glutamate(-) concentration affects the concentration of glutamate(-) and ions in the <span class="hlt">pore</span> and how such changes alter the radial force on the wall of the fusion <span class="hlt">pore</span>. A step-like rise of the vesicular K(+)-glutamate(-) concentration leads to a chain of events. <span class="hlt">Pore</span> concentration (and efflux) of both K(+) and glutamate(-) rise reaching their new steady-state values in less than 100 ns. Interestingly within a similar time interval the <span class="hlt">pore</span> concentration of Na(+) also rises, whereas that of Cl(-) diminishes, although their extra-cellular concentration does not</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70021540','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70021540"><span>Dissolved sulfide distributions in the <span class="hlt">water</span> column and sediment <span class="hlt">pore</span> <span class="hlt">waters</span> of the Santa Barbara Basin</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kuwabara, J.S.; VanGeen, A.; McCorkle, D.C.; Bernhard, J.M.</p> <p>1999-01-01</p> <p>Dissolved sulfide concentrations in the <span class="hlt">water</span> column and in sediment <span class="hlt">pore</span> <span class="hlt">waters</span> were measured by square-wave voltammetry (nanomolar detection limit) during three cruises to the Santa Barbara Basin in February 1995, November-December 1995, and April 1997. In the <span class="hlt">water</span> column, sulfide concentrations measured outside the basin averaged 3 ?? 1 nM (n = 28) in the 0 to 600 m depth range. Inside the basin, dissolved sulfides increased to reach values of up to 15 nM at depths >400 m. A suite of box cores and multicores collected at four sites along the northeastern flank of the basin showed considerable range in surficial (400 ??M at 10 cm. Decreases in <span class="hlt">water</span>-column nitrate below the sill depth indicate nitrate consumption (-55 to -137 ??mole m-2 h-1) similar to nearby Santa Monica Basin. Peaks in <span class="hlt">pore-water</span> iron concentrations were generally observed between 2 and 5 cm depth with shallowest peaks at the 590 m site. These observations, including observations of the benthic microfauna, suggest that the extent to which the sulfide flux, sustained by elevated <span class="hlt">pore-water</span> concentrations, reaches the <span class="hlt">water</span> column may be modulated by the abundance of sulfide-oxidizing bacteria in addition to iron redox and precipitation reactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70032871','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70032871"><span>Bottom sediments and <span class="hlt">pore</span> <span class="hlt">waters</span> near a hydrothermal vent in Lake Baikal (Frolikha Bay)</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Granina, L.Z.; Klerkx, J.; Callender, E.; Leermakers, M.; Golobokova, L.P.</p> <p>2007-01-01</p> <p>We discuss the redox environments and the compositions of bottom sediments and sedimentary <span class="hlt">pore</span> <span class="hlt">waters</span> in the region of a hydrothermal vent in Frolikha Bay, Lake Baikal. According to our results, the submarine vent and its companion nearby spring on land originate from a common source. The most convincing evidence for their relation comes from the proximity of stable oxygen and hydrogen isotope compositions in <span class="hlt">pore</span> <span class="hlt">waters</span> and in the spring <span class="hlt">water</span>. The isotope composition indicates a meteoric origin of <span class="hlt">pore</span> <span class="hlt">waters</span>, but their major- and minor-element chemistry bears imprint of deep <span class="hlt">water</span> which may seep through permeable faulted crust. Although <span class="hlt">pore</span> <span class="hlt">waters</span> near the submarine vent have a specific enrichment in major and minor constituents, hydrothermal discharge at the Baikal bottom causes a minor impact on the lake <span class="hlt">water</span> chemistry, unlike the case of freshwater geothermal lakes in the East-African Rift and North America. ?? 2007.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28365504','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28365504"><span>Metal(loid) speciation and size fractionation in sediment <span class="hlt">pore</span> <span class="hlt">water</span> depth profiles examined with a new meso profiling system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schroeder, Henning; Fabricius, Anne-Lena; Ecker, Dennis; Ternes, Thomas A; Duester, Lars</p> <p>2017-03-23</p> <p>In an exemplary incubation study with an anaerobic sediment sampled at an oxbow of the river Lahn in Germany (50°18'56.87″N; 7°37'41.25″E) and contaminated by former mining activity, a novel meso profiling and sampling system (messy) is presented. Messy enables a low invasive, automated sampling of <span class="hlt">pore</span> <span class="hlt">water</span> profiles across the sediment <span class="hlt">water</span> interface (SWI), down to ∼20 cm depth with a spacial resolution of 1 cm. In parallel to the <span class="hlt">pore</span> <span class="hlt">water</span> sampling it measures physicochemical sediment parameters such as redox potential and pH value. In an incubation experiment of 151 days the ability of the setup was proven to address several different aspects relevant for fresh <span class="hlt">water</span> and <span class="hlt">marine</span> sediment studies: (i) The influence of mechanical disturbance and oxygen induced acidification on the mobility of 13 metals and metalloids (Cd, Co, Cu, Fe, Mn, Mo, Ni, Sb, U, V, Zn) was quantified based on 11 profiles. The analytes were quantified by inductively coupled plasma-mass spectrometry. Three groups of elements were identified with respect to the release into the <span class="hlt">pore</span> <span class="hlt">water</span> and the overlying <span class="hlt">water</span> under different experimental conditions. (ii) The capability to investigate the impacts of changing physicochemical sediment properties on arsenic and antimony (III/V) speciation is shown. (iii) An approach to obtain information on size fractionation effects and to address the colloidal <span class="hlt">pore</span> <span class="hlt">water</span> fractions (0.45 μm-16 μm) was successfully conducted for the elements Ag, As, Cu, Fe and Mn.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6481585','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6481585"><span>Three-phase modeling of polycyclic aromatic hydrocarbon association with <span class="hlt">pore-water</span>-dissolved organic carbon</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mitra, S. ); Dickhut, R.M. )</p> <p>1999-06-01</p> <p>Log-log plots of measured organic carbon-normalized sediment <span class="hlt">pore-water</span> distribution coefficients (K[prime][sub OC]s) for several polycyclic aromatic hydrocarbons (PAHs) versus their octanol-<span class="hlt">water</span> partition coefficients (K[prime][sub OW]s) at two sites in the Elizabeth River, Virginia, show large deviations from linearity. Organic-carbon normalized distribution coefficients for these PAHs between sediments and <span class="hlt">pore</span> <span class="hlt">waters</span> decreased by more than two orders of magnitude with depth as well. To determine to what extent <span class="hlt">pore</span> <span class="hlt">water</span> dissolved and colloidal organic carbon (DOC) was responsible for the observed nonlinearity and decrease in K[prime][sub OC], a three-phase model was used to estimate <span class="hlt">pore-water</span> PAH-DOC binding coefficients (K[sub DOC]). Partitioning of PAHs to <span class="hlt">pore-water</span> DOC (i.e., K[sub DOC])enhances the observed dissolved phase PAH concentration, especially for high-K[sub OW] compounds, contributing to the nonlinearity in K[prime][sub OC]-K[sub OW] plots. However, the application of the three-phase partitioning model to these data indicate that, at most, <span class="hlt">pore-water</span> PAH-DOC binding accounts for one order of magnitude of the observed decrease in K[prime][sub OC] with depth in the sediment bed. The results of this study are consistent with three-phase partitioning theory for hydrophobic organic compounds between sediment organic matter, <span class="hlt">pore-water</span> DOC, and freely dissolved aqueous phases in natural systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26076248','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26076248"><span><span class="hlt">Pore</span>-size dependent THz absorption of nano-confined <span class="hlt">water</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sun, Chi-Kuang; You, Borwen; Huang, Yu-Ru; Liu, Kao-Hsiang; Sato, Shusaku; Irisawa, Akiyoshi; Imamura, Motoki; Mou, Chung-Yuan</p> <p>2015-06-15</p> <p>We performed a THz absorption spectroscopy study on liquid <span class="hlt">water</span> confined in mesoporous silica materials, MCM-41-S-18 and MCM-41-S-21, of two different <span class="hlt">pore</span> sizes at room temperatures. We found that stronger confinement with a smaller <span class="hlt">pore</span> size causes reduced THz absorption, indicating reduced <span class="hlt">water</span> mobility due to confinement. Combined with recent theoretical studies showing that the microscopic structure of <span class="hlt">water</span> inside the nanopores can be separated into a core <span class="hlt">water</span> region and an interfacial <span class="hlt">water</span> region, our spectroscopy analysis further reveals a bulk-<span class="hlt">water</span>-like THz absorption behavior in the core <span class="hlt">water</span> region and a solid-like THz absorption behavior in the interfacial <span class="hlt">water</span> region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/807903','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/807903"><span>Molecular simulation study of <span class="hlt">water</span>--methanol mixtures in activated carbon <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shevade, Abhijit V.; Jiang, Shaoyi; Gubbins, Keith E.</p> <p>2000-10-22</p> <p>We report a theoretical study of the adsorption behavior of <span class="hlt">water</span>--methanol mixtures in slit activated carbon micropores. The adsorption isotherms are obtained for a <span class="hlt">pore</span> of width 2 nm at a temperature of 298 K from grand canonical ensemble Monte Carlo simulations. The <span class="hlt">water</span> molecules are modeled using the four point transferable intermolecular potential functions (TIP4P) and methanol by the optimized potentials for liquid simulations (OPLS). Carboxyl (COOH) groups are used as active sites on a structured carbon surface. The effect of the relative contributions from dispersion and hydrogen bonding interactions of adsorbates, and of the chemical activation of adsorbents on adsorption behavior is investigated. The adsorption of the mixture components in activated carbon <span class="hlt">pores</span> occurs by continuous filling, without the sharp capillary condensation observed in graphite <span class="hlt">pores</span>. <span class="hlt">Water</span> is preferentially adsorbed over methanol in activated carbon <span class="hlt">pores</span> for a wide range of pressures, except at lower pressures. The hydrophilic nature of activated carbon <span class="hlt">pores</span> results in the complexation of both <span class="hlt">water</span> and methanol molecules with the active sites on the surfaces, leading to bulklike <span class="hlt">water</span> behavior over the entire <span class="hlt">pore</span> width. Solvation forces are also calculated as a function of <span class="hlt">pore</span> size. The negative values found for the solvation force for all <span class="hlt">pore</span> sizes reflect the hydrophilic interactions of the mixtures with the activated carbon surfaces. {copyright} 2000 American Institute of Physics [S0021-9606(00)51339-7</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMGC43E1200N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMGC43E1200N"><span>Chemical and Isotopic Characterization of Surface <span class="hlt">Water</span> and Active Layer <span class="hlt">Pore</span> <span class="hlt">Water</span> in a Tundra Landscape, Barrow, Alaska, USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Newman, B. D.; Heikoop, J. M.; Throckmorton, H.; Arendt, C. A.; Graham, D. E.; Wilson, C. J.; Wullschleger, S. D.</p> <p>2016-12-01</p> <p>Studies conducted in the Barrow Environmental Observatory as part of the Next Generation Ecosystem Experiment (NGEE) - Arctic have demonstrated significant chemical and isotopic variability in surface <span class="hlt">water</span> and active layer <span class="hlt">pore</span> <span class="hlt">water</span> of polygonal terrain located between drained thaw lake basins (DTLBs). In this study, we report on chemical and isotopic variation at the broader landscape scale that includes different age DTLBs and associated drainages, extant thaw lakes, and interlake regions. Fingerprint diagrams of major elements show a broader range of variation at the landscape scale relative to polygonal terrain. ANOVA analysis suggests that many of the polygonal and broader landscape scale sites have similar chemistry, suggesting a reasonably high degree of hydrologic connectivity. The most significant site-specific differences include higher d18O and d2H, indicative of evaporative conditions, of surface and active layer <span class="hlt">water</span> from an ancient (2000- 5500 BP) DTLB that comprises a shallow basin with no outlets. Significantly higher Cl, Ca, Fe, Mg, Na, As, Mn and Sr concentrations were also found in <span class="hlt">pore</span> <span class="hlt">waters</span> collected immediately above the frost table at two locations. The first location is a small drainage leading from an area of polygonal terrain into an adjacent slough, while the second is upgradient of the estuarine terminus of a drainage sourced from a medium-aged DTLB (50- 300 BP). Higher concentrations at the frost table suggests a mechanism related to periodic freezing and thawing of the transition zone above permafrost or permafrost degradation. Alternative conceptual models, including the presence of a <span class="hlt">marine</span> signal or the influence of cryopegs (brine layers within permafrost), will also be considered. Characterization of present day Arctic hydrology and chemistry at different scales is important for Earth Systems Models and for predicting hydrogeochemical change associated with landscape evolution due to future permafrost degradation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.springerlink.com/content/x8xwcnu1gux6e4pf/?p=9624ca7895ad465ab98960a32b52bcff&pi=1','USGSPUBS'); return false;" href="http://www.springerlink.com/content/x8xwcnu1gux6e4pf/?p=9624ca7895ad465ab98960a32b52bcff&pi=1"><span>The influence of extraction procedure on ion concentrations in sediment <span class="hlt">pore</span> <span class="hlt">water</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Winger, P.V.; Lasier, P.J.; Jackson, B.P.</p> <p>1998-01-01</p> <p>Sediment <span class="hlt">pore</span> <span class="hlt">water</span> has the potential to yield important information on sediment quality, but the influence of isolation procedures on the chemistry and toxicity are not completely known and consensus on methods used for the isolation from sediment has not been reached. To provide additional insight into the influence of collection procedures on <span class="hlt">pore</span> <span class="hlt">water</span> chemistry, anion (filtered only) and cation concentrations were measured in filtered and unfiltered <span class="hlt">pore</span> <span class="hlt">water</span> isolated from four sediments using three different procedures: dialysis, centrifugation and vacuum. Peepers were constructed using 24-cell culture plates and cellulose membranes, and vacuum extractors consisted of fused-glass air stones attached with airline tubing to 60cc syringes. Centrifugation was accomplished at two speeds (2,500 and 10,000 x g) for 30 min in a refrigerated centrifuge maintained at 4?C. Only minor differences in chemical characteristics and cation and anion concentrations were found among the different collecting methods with differences being sediment specific. Filtering of the <span class="hlt">pore</span> <span class="hlt">water</span> did not appreciably reduce major cation concentrations, but trace metals (Cu and Pb) were markedly reduced. Although the extraction methods evaluated produced <span class="hlt">pore</span> <span class="hlt">waters</span> of similar chemistries, the vacuum extractor provided the following advantages over the other methods: (1) ease of extraction, (2) volumes of <span class="hlt">pore</span> <span class="hlt">water</span> isolated, (3) minimal preparation time and (4) least time required for extraction of <span class="hlt">pore</span> <span class="hlt">water</span> from multiple samples at one time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18767670','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18767670"><span>Field deployment of polyethylene devices to measure PCB concentrations in <span class="hlt">pore</span> <span class="hlt">water</span> of contaminated sediment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tomaszewski, Jeanne E; Luthy, Richard G</p> <p>2008-08-15</p> <p>Sediment <span class="hlt">pore</span> <span class="hlt">water</span> concentrations of polychlorinated biphenyls (PCBs) in a contaminated mudflat in San Francisco Bay, CA were determined by field-deployed polyethylene devices (PEDs). Sequential sampling of PEDs deployed in the field showed large differences in uptake rates and time to equilibrium compared to PEDs mixed with field-collected sediment in the laboratory. We demonstrate a modeling approach that involves the use of impregnated performance reference compounds (PRCs) and interpretation of the data either by PCB molar volume adjustment or environmental adjustment factors to measure <span class="hlt">pore</span> <span class="hlt">water</span> concentrations of 118 PCB congeners. Both adjustment methods predicted comparable sampling rates, and PCB <span class="hlt">pore</span> <span class="hlt">water</span> concentrations estimated by use of the molar volume adjustment method were similar to values analytically measured in <span class="hlt">pore</span> <span class="hlt">waters</span> from the laboratory and field. The utility of PEDs for sampling <span class="hlt">pore</span> <span class="hlt">water</span> in the field was evaluated at a tidal mudflat amended with activated carbon to sequester PCBs. <span class="hlt">Pore</span> <span class="hlt">water</span> concentrations decreased up to 60% within 18 months after activated carbon amendment, as compared to a mechanical-mixed control plot Results of this study illustrate PEDs provide an inexpensive, in situ method to measure total PCB contamination in sediment <span class="hlt">pore</span> <span class="hlt">water</span> using a small set of PRCs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7163018','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7163018"><span>Aqueous-, <span class="hlt">pore-water</span>-, and sediment-phase cadmium: Toxicity relationships for a meiobenthic copepod</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Green, A.S.; Chandler, G.T.; Blood, E.R. . Dept. of Environmental Health Sciences)</p> <p>1993-08-01</p> <p>Comparative effects of aqueous-, <span class="hlt">pore-water</span>-, and sediment-phase cadmium on mortality of an infaunal laboratory-cultured copepod, Amphiascus tenuiremis, were determined using acute 96-h bioassays. Experimental design included five cadmium concentrations, three replicates per concentration, and 50 adult copepods per replicate for each of the exposure. Exposures included cadmium solubilized in seawater only, whole sediment, and <span class="hlt">pore</span> <span class="hlt">water</span> only. In addition, two whole-sediment bioassays were compared in which <span class="hlt">pore-water</span> cadmium concentrations were altered experimentally but sediment concentrations remained the same. Results of these experiments showed that for Amphiascus tenuiremis, cadmium is most toxic in the aqueous phase, less toxic in the <span class="hlt">pore-water</span> phase, and last toxic in the sediment-bound phase. The lowered toxicity of cadmium in the <span class="hlt">pore</span> <span class="hlt">water</span> was most likely due to complexation of cadmium with DOC, because concentrations of DOC were six times higher in the <span class="hlt">pore-water</span> phase than in the aqueous phase. In whole sediments, <span class="hlt">pore-water</span>-phase cadmium was the primary source of acute toxicity, as sediment-associated cadmium contributed negligible effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26897083','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26897083"><span>Behaviour of butyltin compounds in the sediment <span class="hlt">pore</span> <span class="hlt">waters</span> of a contaminated marina (Port Camargue, South of France).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Briant, Nicolas; Bancon-Montigny, Chrystelle; Freydier, Rémi; Delpoux, Sophie; Elbaz-Poulichet, Françoise</p> <p>2016-05-01</p> <p>Despite the ban on tributyltin (TBT) in <span class="hlt">marine</span> paints, harbour sediments are still highly contaminated by this antifouling agent. Concentrations of TBT and its dealkylated products dibutyltin (DBT) and monobutyltin (MBT) were determined in the <span class="hlt">pore</span> <span class="hlt">waters</span> of Port Camargue, a large marina located on the French Mediterranean coast. <span class="hlt">Pore</span> <span class="hlt">waters</span> were sampled in the field using peepers deployed in summer 2012 and 2013 and in winter 2012-2013. The winter surveys were characterized by the presence of sulphides in <span class="hlt">pore</span> <span class="hlt">waters</span> from a depth of 5 cm, which was not the case in winter. In summer 2013, TBT was shown to be released into <span class="hlt">pore</span> <span class="hlt">waters</span> below the sediment-<span class="hlt">water</span> interface (SWI) at concentrations of up to 70 ngSn L(-1). This release was also observed in sediment anaerobic incubations and was attributed to the mineralization of the sedimentary organic matter, possible stabilization of TBT by complexation with sulphides, and lower debutylation rates in anoxic than in oxic conditions. In summer 2012, a comparatively lower concentration of TBT (around 20 ngSn L(-1) below the SWI) was measured and the presence of methyltin species was detected. We hypothesize that the differences between the two surveys reflect different microbial activity. In winter 2012-2013, marked by Fe-reducing conditions in the sediments, TBT was released into solution at the SWI at concentrations of up to 40 ngSn L(-1). Sediments are thus a continuing source of TBT for the overlying <span class="hlt">waters</span> despite the ban on its use for boats in France. Copyright © 2016 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016WRR....52.1729M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016WRR....52.1729M"><span>Relating salt marsh <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry patterns to vegetation zones and hydrologic influences</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moffett, Kevan B.; Gorelick, Steven M.</p> <p>2016-03-01</p> <p>Physical, chemical, and biological factors influence vegetation zonation in salt marshes and other wetlands, but connections among these factors could be better understood. If salt marsh vegetation and marsh <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry coorganize, e.g., via continuous plant <span class="hlt">water</span> uptake and persistently unsaturated sediments controlling vegetation zone-specific <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry, this could complement known physical mechanisms of marsh self-organization. A high-resolution survey of <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry was conducted among five salt marsh vegetation zones at the same intertidal elevation. Sampling transects were arrayed both parallel and perpendicular to tidal channels. <span class="hlt">Pore</span> <span class="hlt">water</span> geochemistry patterns were both horizontally differentiated, corresponding to vegetation zonation, and vertically differentiated, relating to root influences. The geochemical patterns across the site were less broadly related to marsh hydrology than to vegetation zonation. Mechanisms contributing to geochemical differentiation included: root-induced oxidation and nutrient (P) depletion, surface and creek-bank sediment flushing by rainfall or tides, evapotranspiration creating aerated <span class="hlt">pore</span> space for partial sediment flushing in some areas while persistently saturated conditions hindered <span class="hlt">pore</span> <span class="hlt">water</span> renewal in others, and evapoconcentration of <span class="hlt">pore</span> <span class="hlt">water</span> solutes overall. The concentrated <span class="hlt">pore</span> <span class="hlt">waters</span> draining to the tidal creeks accounted for 41% of ebb tide solutes (median of 14 elements), including being a potentially toxic source of Ni but a slight sink for Zn, at least during the short, winter study period in southern San Francisco Bay. Heterogeneous vegetation effects on <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry are not only significant locally within the marsh but may broadly influence marsh-estuary solute exchange and ecology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhDT.......182C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhDT.......182C"><span><span class="hlt">Pore</span> <span class="hlt">Water</span> Pressure Response of a Soil Subjected to Traffic Loading under Saturated and Unsaturated Conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cary, Carlos</p> <p></p> <p>This study presents the results of one of the first attempts to characterize the <span class="hlt">pore</span> <span class="hlt">water</span> pressure response of soils subjected to traffic loading under saturated and unsaturated conditions. It is widely known that <span class="hlt">pore</span> <span class="hlt">water</span> pressure develops within the soil <span class="hlt">pores</span> as a response to external stimulus. Also, it has been recognized that the development of <span class="hlt">pores</span> <span class="hlt">water</span> pressure contributes to the degradation of the resilient modulus of unbound materials. In the last decades several efforts have been directed to model the effect of air and <span class="hlt">water</span> <span class="hlt">pore</span> pressures upon resilient modulus. However, none of them consider dynamic variations in pressures but rather are based on equilibrium values corresponding to initial conditions. The measurement of this response is challenging especially in soils under unsaturated conditions. Models are needed not only to overcome testing limitations but also to understand the dynamic behavior of internal <span class="hlt">pore</span> pressures that under critical conditions may even lead to failure. A testing program was conducted to characterize the <span class="hlt">pore</span> <span class="hlt">water</span> pressure response of a low plasticity fine clayey sand subjected to dynamic loading. The bulk stress, initial matric suction and dwelling time parameters were controlled and their effects were analyzed. The results were used to attempt models capable of predicting the accumulated excess <span class="hlt">pore</span> pressure at any given time during the traffic loading and unloading phases. Important findings regarding the influence of the controlled variables challenge common beliefs. The accumulated excess <span class="hlt">pore</span> <span class="hlt">water</span> pressure was found to be higher for unsaturated soil specimens than for saturated soil specimens. The maximum <span class="hlt">pore</span> <span class="hlt">water</span> pressure always increased when the high bulk stress level was applied. Higher dwelling time was found to decelerate the accumulation of <span class="hlt">pore</span> <span class="hlt">water</span> pressure. In addition, it was found that the higher the dwelling time, the lower the maximum <span class="hlt">pore</span> <span class="hlt">water</span> pressure. It was concluded that upon further</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987JAP....62.4682V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987JAP....62.4682V"><span>Strain and <span class="hlt">pore</span> pressure propagation in a <span class="hlt">water</span>-saturated porous medium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van der Grinten, Jos G. M.; van Dongen, Marinus E. H.; van der Kogel, Hans</p> <p>1987-12-01</p> <p>Wave propagation in a <span class="hlt">water</span>-saturated porous column consisting of fixed sand particles is studied by means of a shock tube technique. <span class="hlt">Pore</span> pressures and axial strains are recorded simultaneously. The measurements show a coincident compression of <span class="hlt">pore</span> fluid and porous column during the passage of the first wave. Due to the second wave the <span class="hlt">pore</span> fluid is compressed while the porous material expands. This observed behavior is in agreement with theoretical predictions. The introduction of a frequency-dependent permeability and an effective <span class="hlt">pore</span> radius based on a cylindrical duct model yields an improved description of the damping of the second wave.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23116121','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23116121"><span>Size effects of <span class="hlt">pore</span> density and solute size on <span class="hlt">water</span> osmosis through nanoporous membrane.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Kuiwen; Wu, Huiying</p> <p>2012-11-15</p> <p>Understanding the behavior of osmotic transport across nanoporous membranes at molecular level is critical to their design and applications, and it is also beneficial to the comprehension of the mechanism of biological transmembrane transport processes. <span class="hlt">Pore</span> density is an important parameter for nanoporous membranes. To better understand the influence of <span class="hlt">pore</span> density on osmotic transport, we have performed systematic molecular dynamics simulations on <span class="hlt">water</span> osmosis across nanoporous membranes with different <span class="hlt">pore</span> densities (i.e., number of <span class="hlt">pores</span> per unit area of membrane). The simulation results reveal that significant size effects occur when the <span class="hlt">pore</span> density is so high that the center-to-center distance between neighboring nanopores is comparable to the solute size. The size effects are independent of the <span class="hlt">pore</span> diameter and solute concentration. A simple quantitative correlation between <span class="hlt">pore</span> density, solute size, and osmotic flux has been established. The results are excellently consistent with the theoretical predictions. It is also shown that solute hydration plays an important role in real osmotic processes. Solute hydration strengthens the size effects of <span class="hlt">pore</span> density on osmotic processes due to the enlarged effective solute size induced by hydration. The influence of <span class="hlt">pore</span> density, solute size, and solute hydration on <span class="hlt">water</span> osmosis through nanoporous membranes can be introduced to eliminate the deviations of real osmotic processes from ideal behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvB..95s5414L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvB..95s5414L"><span>Insight into the wetting of a graphene-mica slit <span class="hlt">pore</span> with a monolayer of <span class="hlt">water</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, Hu; Schilo, Andre; Kamoka, A. Rauf; Severin, Nikolai; Sokolov, Igor M.; Rabe, Jürgen P.</p> <p>2017-05-01</p> <p>Scanning force microscopy (SFM) and Raman spectroscopy allow the unraveling of charge doping and strain effects upon wetting and dewetting of a graphene-mica slit <span class="hlt">pore</span> with <span class="hlt">water</span>. SFM reveals a wetting monolayer of <span class="hlt">water</span>, slightly thinner than a single layer of graphene. The Raman spectrum of the dry <span class="hlt">pore</span> exhibits the D' peak of graphene, which practically disappears upon wetting, and recurs when the <span class="hlt">water</span> layer dewets the <span class="hlt">pore</span>. Based on the 2 D - and G -peak positions, the corresponding peak intensities, and the widths, we conclude that graphene on dry mica is charge-doped and variably strained. A monolayer of <span class="hlt">water</span> in between graphene and mica removes the doping and reduces the strain. We attribute the D' peak to direct contact of the graphene with the ionic mica surface in dry conditions, and we conclude that a complete monolayer of <span class="hlt">water</span> wetting the slit <span class="hlt">pore</span> decouples the graphene from the mica substrate both mechanically and electronically.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.H21B1331B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.H21B1331B"><span><span class="hlt">Pore</span> <span class="hlt">Water</span> Circulation in Isolated Wetlands: Implications to Internal Nutrient Loading.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bhadha, J. H.; Perkins, D. B.; Jawitz, J. W.</p> <p>2005-12-01</p> <p>The potential of wetland soils to accumulate and release pollutants including nutrients has been the motivation for numerous studies related to measuring the concentration, fate, and transport mechanisms of these substances in soils. While external nutrient loading from anthropogenic sources such as agricultural and cattle areas can be addressed through the implementation of Best Management Practices (BMPs), and interception strategies such as construction of storm-<span class="hlt">water</span> treatment areas (STAs) in Florida, internal loading through shallow sediments has prevented the rapid improvement of <span class="hlt">water</span> quality in numerous watersheds in South Florida, including the Lake Okeechobee drainage basin. The internal release of nutrients can occur via two different yet equally important mechanisms: advection and diffusion. These processes may mix the <span class="hlt">pore</span> <span class="hlt">water</span> not only within the sediment but also with the overlying <span class="hlt">water</span> column over short periods of time (e.g., days or weeks). This provides sufficient time for diagenesis to alter the reactive chemical components of nutrients that may ultimately increase the nutrient fluxes to the overlying <span class="hlt">water</span> column. The objectives of this research are to present a plausible and testable technique to collect <span class="hlt">pore</span> <span class="hlt">water</span> samples from saturated wetland soils, and to evaluate the importance of <span class="hlt">pore</span> <span class="hlt">water</span> circulation as a mechanism for mobilizing nutrients into the <span class="hlt">water</span> column from within shallow sediments in isolated wetlands. <span class="hlt">Pore</span> <span class="hlt">water</span> sampling can be a difficult task to perform in low permeable wetland soils using standard sampling devices such as <span class="hlt">pore</span> <span class="hlt">water</span> equilibrators (peepers) and mechanical vises (Rheeburg squeezers). However, our attempt at using Multisamplers, which is in fact a multi-level piezometer capable of collecting up to ten <span class="hlt">pore</span> <span class="hlt">water</span> samples to a depth of 110 cm below the soil-<span class="hlt">water</span> interface in a single deployment, proved to be a success. The ability to collect samples from multiple depths from a single location is an important</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013CPL...582....1G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013CPL...582....1G"><span>Dynamics of <span class="hlt">water</span> in the amphiphilic <span class="hlt">pore</span> of amyloid β fibrils</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>GhattyVenkataKrishna, Pavan K.; Mostofian, Barmak</p> <p>2013-09-01</p> <p>Alzheimers disease related amyloid peptide, Aβ, forms a fibrillar structure through aggregation. The aggregate is stabilized by a salt bridge that is responsible for the formation of an amphiphilic <span class="hlt">pore</span> that can accommodate <span class="hlt">water</span> molecules. None of the reported structures of Aβ, however, contain <span class="hlt">water</span>. We present results from molecular dynamics simulations on dimeric Aβ fibrils solvated in <span class="hlt">water</span>. <span class="hlt">Water</span> penetrates and fills the amphiphilic <span class="hlt">pore</span> increasing its volume. We observe a thick wire of <span class="hlt">water</span> that is translationally and rotationally stiff in comparison to bulk <span class="hlt">water</span> and may be essential for the stabilization of the amyloid Aβ protein.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.H51C0898I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.H51C0898I"><span>Comparison of <span class="hlt">Pore</span> <span class="hlt">Water</span> Chemical Extracted by Different Forces with In-situ Properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ito, N.; Machida, I.; Marui, A.; Scheytt, T.; Hebig, K. H.</p> <p>2010-12-01</p> <p>Due to the difficulty involved for in-situ sampling of groundwater, <span class="hlt">pore</span> <span class="hlt">water</span> was extracted from rock core samples for chemical analysis. Available literature indicated that, the chemical constituents of <span class="hlt">pore</span> <span class="hlt">water</span> are affected by large extraction force. This study is therefore aimed at discussing the reason behind the change in <span class="hlt">pore</span> <span class="hlt">water</span> chemistry when samples are subjected to different extraction forces. The process involved extraction of <span class="hlt">pore</span> <span class="hlt">water</span> from sandstone core samples at different pF values by centrifuge method. The pF expresses the tension of <span class="hlt">water</span>, retained in soil. It is the base 10 logarithm of tension, which is measured as a head of <span class="hlt">water</span> head in centimeters. The samples of lengths 100 m each were obtained from three locations. Tracer test using Iodine was also conducted to remove <span class="hlt">pore</span> <span class="hlt">water</span> polluted by drilling <span class="hlt">water</span>. <span class="hlt">Pore</span> <span class="hlt">water</span> was extracted from a total of 63 samples at three different values of pF (low: up to pF 2.3, medium: pF 2.3 - 3.9, high: pF 3.9 - 4.3). For each pF range the <span class="hlt">pore</span> <span class="hlt">water</span> was analyzed for major anions and cations. Results showed variation of ionic concentrations with pF and depth. The average concentrations rose with increase of pF in all ions except for potassium. Based on the concentration distribution of Ca2+, three zones could be defined: (1) Ca2+ concentration, which does not depend on pF, (2) Ca2+ concentration, which increases with the value of pF and (3) Ca2+ showing the same value for medium and high pF values. It is thus concluded that, <span class="hlt">water</span> chemistry of deep <span class="hlt">pore</span> <span class="hlt">water</span> is likely to have reached equilibrium due to almost stagnant flow conditions, whereas shallow <span class="hlt">water</span> is likely to participate in chemical interactions due to the relatively high flow velocity. The depths of the interfaces of these three zones are almost consistent with geological boundaries of weathered and fine sandstone and there is evidence of a relationship between <span class="hlt">pore</span> <span class="hlt">water</span> chemistry and physical rock properties. Using this knowledge, we</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1063731','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1063731"><span><span class="hlt">Pore-Water</span> Extraction Scale-Up Study for the SX Tank Farm</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Truex, Michael J.; Oostrom, Martinus; Wietsma, Thomas W.; Last, George V.; Lanigan, David C.</p> <p>2013-01-15</p> <p>The phenomena related to <span class="hlt">pore-water</span> extraction from unsaturated sediments have been previously examined with limited laboratory experiments and numerical modeling. However, key scale-up issues have not yet been addressed. Laboratory experiments and numerical modeling were conducted to specifically examine <span class="hlt">pore-water</span> extraction for sediment conditions relevant to the vadose zone beneath the SX Tank Farm at Hanford Site in southeastern Washington State. Available SX Tank Farm data were evaluated to generate a conceptual model of the subsurface for a targeted <span class="hlt">pore-water</span> extraction application in areas with elevated moisture and Tc-99 concentration. The hydraulic properties of the types of porous media representative of the SX Tank Farm target application were determined using sediment mixtures prepared in the laboratory based on available borehole sediment particle size data. Numerical modeling was used as an evaluation tool for scale-up of <span class="hlt">pore-water</span> extraction for targeted field applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/5223368','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/5223368"><span>A vacuum-operated <span class="hlt">pore-water</span> extractor for estuarine and freshwater sediments</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Winger, Parley V.; Lasier, Peter J.</p> <p>1991-01-01</p> <p>A vacuum-operated <span class="hlt">pore-water</span> extractor for estuarine and freshwater sediments was developed and constructed from a fused-glass air stone attached with aquarium airline tubing to a 30 or 60 cc polypropylene syringe. <span class="hlt">Pore</span> <span class="hlt">water</span> is extracted by inserting the air stone into the sediment and creating a vacuum by retracting and bracing the syringe plunger. A hand-operated vacuum pump attached to a filtration flask was also evaluated as an alternative vacuum source. The volume and time to extract <span class="hlt">pore</span> <span class="hlt">water</span> varies with the number of devices and the sediment particle size. Extraction time is longer for fine sediments than for sandy sediments. Four liters of sediment generally yield between 500 and 1,500 mL of <span class="hlt">pore</span> <span class="hlt">water</span>. The sediment that surrounds and accumulates on the air stone acts as a filter, and, except for the first few milliliters, the collected <span class="hlt">pore</span> <span class="hlt">water</span> is clear. Because there is no exposure to air or avenue for escape, volatile compounds andin situ characteristics are retained in the extracted <span class="hlt">pore</span> <span class="hlt">water</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70014892','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014892"><span>Dissolved organic matter in anoxic <span class="hlt">pore</span> <span class="hlt">waters</span> from Mangrove Lake, Bermuda</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Orem, W.H.; Hatcher, P.G.; Spiker, E. C.; Szeverenyi, N.M.; Maciel, G.E.</p> <p>1986-01-01</p> <p>Dissolved organic matter and dissolved inorganic chemical species in anoxic <span class="hlt">pore</span> <span class="hlt">water</span> from Mangrove Lake, Bermuda sediments were studied to evaluate the role of <span class="hlt">pore</span> <span class="hlt">water</span> in the early diagenesis of organic matter. Dissolved sulphate, titration alkalinity, phosphate, and ammonia concentration versus depth profiles were typical of many nearshore clastic sediments and indicated sulphate reduction in the upper 100 cm of sediment. The dissolved organic matter in the <span class="hlt">pore</span> <span class="hlt">water</span> was made up predominantly of large molecules, was concentrated from large quantities of <span class="hlt">pore</span> <span class="hlt">water</span> by using ultrafiltration and was extensively tudied by using elemental and stable carbon isotope analysis and high-resolution, solid state 13C nuclear magnetic resonance and infrared spectroscopy. The results indicate that this material has a predominantly polysaccharide-like structure and in addition contains a large amount of oxygen-containing functional groups (e.g., carboxyl groups). The 13C nulcear magnetic resonance spectra of the high-molecular-weight dissolved organic matter resemble those of the organic matter in the surface sediments of Mangrove Lake. We propose that this high-molecular-weight organic matter in <span class="hlt">pore</span> <span class="hlt">waters</span> represents the partially degraded, labile organic components of the sedimentary organic matter and that <span class="hlt">pore</span> <span class="hlt">waters</span> serve as a conduit for removal of these labile organic components from the sediments. The more refractory components are, thus, selectively preserved in the sediments as humic substances (primarily humin). ?? 1986.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27711832','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27711832"><span>Transformation of chlorpyrifos and chlorpyrifos-methyl in prairie pothole <span class="hlt">pore</span> <span class="hlt">waters</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Adams, Rachel M; McAdams, Brandon C; Arnold, William A; Chin, Yu-Ping</p> <p>2016-11-09</p> <p>Non-point source pesticide pollution is a concern for wetlands in the prairie pothole region (PPR). Recent studies have demonstrated that reduced sulfur species (e.g., bisulfide and polysulfides) in PPR wetland <span class="hlt">pore</span> <span class="hlt">waters</span> directly undergo reactions with chloroacetanilide and dinitroaniline compounds. In this paper, the abiotic transformation of two organophosphate compounds, chlorpyrifos and chlorpyrifos-methyl, was studied in PPR wetland <span class="hlt">pore</span> <span class="hlt">waters</span>. Chlorpyrifos-methyl reacted significantly faster (up to 4 times) in <span class="hlt">pore</span> <span class="hlt">water</span> with reduced sulfur species relative to hydrolysis. No rate enhancement was observed in the transformation of chlorpyrifos in <span class="hlt">pore</span> <span class="hlt">water</span> with reduced sulfur species. The lack of reactivity was most likely caused by steric hindrance from the ethyl groups and partitioning to dissolved organic matter (DOM), thereby shielding chlorpyrifos from nucleophilic attack. Significant decreases in reaction rates were observed for chlorpyrifos in <span class="hlt">pore</span> <span class="hlt">water</span> with high concentrations of DOM. Rate enhancement due to other reactive species (e.g., organo-sulfur compounds) in <span class="hlt">pore</span> <span class="hlt">water</span> was minor for both compounds relative to the influence of bisulfide and DOM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1261452','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1261452"><span><span class="hlt">Pore</span>-size dependence and characteristics of <span class="hlt">water</span> diffusion in slitlike micropores</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Diallo, S. O.</p> <p>2015-07-16</p> <p>The temperature dependence of the dynamics of <span class="hlt">water</span> inside microporous activated carbon fibers (ACF) is investigated by means of incoherent elastic and quasielastic neutron-scattering techniques. The aim is to evaluate the effect of increasing <span class="hlt">pore</span> size on the <span class="hlt">water</span> dynamics in these primarily hydrophobic slit-shaped channels. Using two different micropore sizes (similar to 12 and 18 angstrom, denoted, respectively, ACF-10 and ACF-20), a clear suppression of the mobility of the <span class="hlt">water</span> molecules is observed as the <span class="hlt">pore</span> gap or temperature decreases. Suppression, we found, is accompanied by a systematic dependence of the average translational diffusion coefficient D-r and relaxation time [tau(0)] of the restricted <span class="hlt">water</span> on <span class="hlt">pore</span> size and temperature. We observed D-r values and tested against a proposed scaling law, in which the translational diffusion coefficient D-r of <span class="hlt">water</span> within a porous matrix was found to depend solely on two single parameters, a temperature-independent translational diffusion coefficient D-c associated with the <span class="hlt">water</span> bound to the <span class="hlt">pore</span> walls and the ratio theta of this strictly confined <span class="hlt">water</span> to the total <span class="hlt">water</span> inside the <span class="hlt">pore</span>, yielding unique characteristic parameters for <span class="hlt">water</span> transport in these carbon channels across the investigated temperature range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvE..92a2312D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvE..92a2312D"><span><span class="hlt">Pore</span>-size dependence and characteristics of <span class="hlt">water</span> diffusion in slitlike micropores</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Diallo, S. O.</p> <p>2015-07-01</p> <p>The temperature dependence of the dynamics of <span class="hlt">water</span> inside microporous activated carbon fibers (ACF) is investigated by means of incoherent elastic and quasielastic neutron-scattering techniques. The aim is to evaluate the effect of increasing <span class="hlt">pore</span> size on the <span class="hlt">water</span> dynamics in these primarily hydrophobic slit-shaped channels. Using two different micropore sizes (˜12 and 18 Å, denoted, respectively, ACF-10 and ACF-20), a clear suppression of the mobility of the <span class="hlt">water</span> molecules is observed as the <span class="hlt">pore</span> gap or temperature decreases. This suppression is accompanied by a systematic dependence of the average translational diffusion coefficient Dr and relaxation time <τ0> of the restricted <span class="hlt">water</span> on <span class="hlt">pore</span> size and temperature. The observed Dr values are tested against a proposed scaling law, in which the translational diffusion coefficient Dr of <span class="hlt">water</span> within a porous matrix was found to depend solely on two single parameters, a temperature-independent translational diffusion coefficient Dc associated with the <span class="hlt">water</span> bound to the <span class="hlt">pore</span> walls and the ratio θ of this strictly confined <span class="hlt">water</span> to the total <span class="hlt">water</span> inside the <span class="hlt">pore</span>, yielding unique characteristic parameters for <span class="hlt">water</span> transport in these carbon channels across the investigated temperature range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1261452-pore-size-dependence-characteristics-water-diffusion-slitlike-micropores','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1261452-pore-size-dependence-characteristics-water-diffusion-slitlike-micropores"><span><span class="hlt">Pore</span>-size dependence and characteristics of <span class="hlt">water</span> diffusion in slitlike micropores</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Diallo, S. O.</p> <p>2015-07-16</p> <p>The temperature dependence of the dynamics of <span class="hlt">water</span> inside microporous activated carbon fibers (ACF) is investigated by means of incoherent elastic and quasielastic neutron-scattering techniques. The aim is to evaluate the effect of increasing <span class="hlt">pore</span> size on the <span class="hlt">water</span> dynamics in these primarily hydrophobic slit-shaped channels. Using two different micropore sizes (similar to 12 and 18 angstrom, denoted, respectively, ACF-10 and ACF-20), a clear suppression of the mobility of the <span class="hlt">water</span> molecules is observed as the <span class="hlt">pore</span> gap or temperature decreases. Suppression, we found, is accompanied by a systematic dependence of the average translational diffusion coefficient D-r and relaxation timemore » [tau(0)] of the restricted <span class="hlt">water</span> on <span class="hlt">pore</span> size and temperature. We observed D-r values and tested against a proposed scaling law, in which the translational diffusion coefficient D-r of <span class="hlt">water</span> within a porous matrix was found to depend solely on two single parameters, a temperature-independent translational diffusion coefficient D-c associated with the <span class="hlt">water</span> bound to the <span class="hlt">pore</span> walls and the ratio theta of this strictly confined <span class="hlt">water</span> to the total <span class="hlt">water</span> inside the <span class="hlt">pore</span>, yielding unique characteristic parameters for <span class="hlt">water</span> transport in these carbon channels across the investigated temperature range.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26274167','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26274167"><span><span class="hlt">Pore</span>-size dependence and characteristics of <span class="hlt">water</span> diffusion in slitlike micropores.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Diallo, S O</p> <p>2015-07-01</p> <p>The temperature dependence of the dynamics of <span class="hlt">water</span> inside microporous activated carbon fibers (ACF) is investigated by means of incoherent elastic and quasielastic neutron-scattering techniques. The aim is to evaluate the effect of increasing <span class="hlt">pore</span> size on the <span class="hlt">water</span> dynamics in these primarily hydrophobic slit-shaped channels. Using two different micropore sizes (∼12 and 18 Å, denoted, respectively, ACF-10 and ACF-20), a clear suppression of the mobility of the <span class="hlt">water</span> molecules is observed as the <span class="hlt">pore</span> gap or temperature decreases. This suppression is accompanied by a systematic dependence of the average translational diffusion coefficient D(r) and relaxation time 〈τ(0)〉 of the restricted <span class="hlt">water</span> on <span class="hlt">pore</span> size and temperature. The observed D(r) values are tested against a proposed scaling law, in which the translational diffusion coefficient D(r) of <span class="hlt">water</span> within a porous matrix was found to depend solely on two single parameters, a temperature-independent translational diffusion coefficient D(c) associated with the <span class="hlt">water</span> bound to the <span class="hlt">pore</span> walls and the ratio θ of this strictly confined <span class="hlt">water</span> to the total <span class="hlt">water</span> inside the <span class="hlt">pore</span>, yielding unique characteristic parameters for <span class="hlt">water</span> transport in these carbon channels across the investigated temperature range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26527298','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26527298"><span>Evaluation of bound and <span class="hlt">pore</span> <span class="hlt">water</span> in cortical bone using ultrashort-TE MRI.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chen, Jun; Grogan, Shawn P; Shao, Hongda; D'Lima, Darryl; Bydder, Graeme M; Wu, Zhihong; Du, Jiang</p> <p>2015-12-01</p> <p>Bone <span class="hlt">water</span> exists in different states with the majority bound to the organic matrix and to mineral, and a smaller fraction in 'free' form in the <span class="hlt">pores</span> of cortical bone. In this study, we aimed to develop and evaluate ultrashort-TE (UTE) MRI techniques for the assessment of T2*, T1 and concentration of collagen-bound and <span class="hlt">pore</span> <span class="hlt">water</span> in cortical bone using a 3-T clinical whole-body scanner. UTE MRI, together with an isotope study using tritiated and distilled <span class="hlt">water</span> (THO-H2O) exchange, as well as gravimetric analysis, were performed on ten sectioned bovine bone samples. In addition, 32 human cortical bone samples were prepared for comparison between the <span class="hlt">pore</span> <span class="hlt">water</span> concentration measured with UTE MRI and the cortical porosity derived from micro-computed tomography (μCT). A short T2* of 0.27 ± 0.03 ms and T1 of 116 ± 6 ms were observed for collagen-bound <span class="hlt">water</span> in bovine bone. A longer T2* of 1.84 ± 0.52 ms and T1 of 527 ± 28 ms were observed for <span class="hlt">pore</span> <span class="hlt">water</span> in bovine bone. UTE MRI measurements showed a <span class="hlt">pore</span> <span class="hlt">water</span> concentration of 4.7-5.3% by volume and collagen-bound <span class="hlt">water</span> concentration of 15.7-17.9% in bovine bone. THO-H2O exchange studies showed a <span class="hlt">pore</span> <span class="hlt">water</span> concentration of 5.9 ± 0.6% and collagen-bound <span class="hlt">water</span> concentration of 18.1 ± 2.1% in bovine bone. Gravimetric analysis showed a <span class="hlt">pore</span> <span class="hlt">water</span> concentration of 6.3 ± 0.8% and collagen-bound <span class="hlt">water</span> concentration of 19.2 ± 3.6% in bovine bone. A mineral <span class="hlt">water</span> concentration of 9.5 ± 0.6% was derived in bovine bone with the THO-H2O exchange study. UTE-measured <span class="hlt">pore</span> <span class="hlt">water</span> concentration is highly correlated (R(2) = 0.72, p < 0.0001) with μCT porosity in the human cortical bone study. Both bovine and human bone studies suggest that UTE sequences could reliably measure collagen-bound and <span class="hlt">pore</span> <span class="hlt">water</span> concentration in cortical bone using a clinical scanner.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981Natur.290..243T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981Natur.290..243T"><span>Methylmercury production in the <span class="hlt">marine</span> <span class="hlt">water</span> column</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Topping, G.; Davies, I. M.</p> <p>1981-03-01</p> <p>Although the biosynthesis of methylmercury in sediments is well established1, this is not necessarily the exclusive natural source of methylmercury entering the <span class="hlt">marine</span> food chain, particularly commercial fish and shellfish species for human consumption. An examination of mercury levels in freshwater fish2, collected from a lake with a history of industrial mercury contamination, suggested that levels in fish are controlled in part by mercury in suspension and it followed that methylation should occur in the <span class="hlt">water</span> column. Although methylmercury is present in seawater in coastal areas receiving discharges of waste containing either inorganic mercury3 or methylmercury4 there is no evidence that methylmercury is actually formed in the <span class="hlt">water</span> column. We now present data which demonstrate that inorganic mercury can be methylated in the <span class="hlt">water</span> column and we compare this production with that known to occur in <span class="hlt">marine</span> sediments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6881071','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6881071"><span>Eutrophication in the northern Adriatic Sea: <span class="hlt">Pore</span> <span class="hlt">water</span> and sediment studies</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hammond, D.E.; Berelson, W.M. ); Giordani, P.; Langone, L.; Frignani, M.; Ravaioli, M. )</p> <p>1990-01-09</p> <p>The northern Adriatic Sea has been plagued by problems of eutrophication. This area is relatively shallow (maximum depth = 60m), becoming stratified during the summer months which inhibits oxygen transport to bottom <span class="hlt">waters</span>. Anthropogenic nutrient loading in rivers entering the northern Adriatic (Po River being the largest) has increased nutrient input to this system and stimulated algal growth. Cores were collected for studies of <span class="hlt">pore</span> <span class="hlt">water</span> and solid phase chemistry at 6 stations in this region. [sup 210]Pb was used to constrain sediment accumulation rates and a range of 0-0.5 cm/yr was determined at different stations. Excess [sup 234]Th was only found in the upper 1-2 cm, suggesting that bioturbation is largely restricted to shallow depths. <span class="hlt">Pore</span> <span class="hlt">water</span> profiles show evidence of irrigation, and mean diffusive fluxes for oxygen, silica phosphate and ammonia are generally 20-90% of the fluxes obtained from benthic chamber measurements. This is consistent with previous work in this area in which studies of radon fluxes indicated that irrigation plays an important role in sediment-<span class="hlt">water</span> exchange. <span class="hlt">Pore</span> <span class="hlt">water</span> profiles in the northern portion of the study area (near the Po River Delta) were markedly different than profiles in the south; sediments in the north are substantially more acidic and have high concentrations of dissolved iron and phosphate. From the alkalinity vs. TCO[sub 2] relationship in sediment <span class="hlt">pore</span> <span class="hlt">waters</span> it appears that differences in reactions involving the reduction of iron oxides and the exchange of magnesium for iron in clays are responsible for this regional difference in <span class="hlt">pore</span> <span class="hlt">water</span> properties. Sediments close to the Po apparently undergo more iron-magnesium exchange, while more distal sediments are limited in their ability to do so. Other <span class="hlt">pore</span> <span class="hlt">water</span> observations are limited in their ability to do so. Other <span class="hlt">pore</span> <span class="hlt">water</span> observations and trends regarding the shape of the silica profiles (which show shallow maxima) will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5533797','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5533797"><span>Inorganic and organic sulfur cycling in salt-marsh <span class="hlt">pore</span> <span class="hlt">waters</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Luther, G.W. III; Church, T.M.; Scudlark, J.R.; Cosman, M.</p> <p>1986-05-09</p> <p>Sulfur species in <span class="hlt">pore</span> <span class="hlt">waters</span> of the Great Marsh, Delaware, were analyzed seasonally by polarographic methods. The species determined (and their concentrations in micromoles per liter) included inorganic sulfides (less than or equal to3360), polysulfides (less than or equal to326), thiosulfate (less than or equal to104), tetrathionate (less than or equal to302), organic thiols (less than or equal to2411), and organic disulfides (less than or equal to139). Anticipated were bisulfide increases with depth due to sulfate reduction and subsurface sulfate excesses and pH minima, the result of a seasonal redox cycle. Unanticipated was the pervasive presence of thiols (for example, glutathione), particularly during periods of biological production. Salt marshes appear to be unique among <span class="hlt">marine</span> systems in producing high concentrations of thiols. Polysulfides, thiosulfate, and tetrathionate also exhibited seasonal subsurface maxima. These results suggest a dynamic seasonal cycling of sulfur in salt marshes involving abiological and biological reactions and dissolved and solid sulfur species. The chemosynthetic turnover of pyrite to organic sulfur is a likely pathway for this sulfur cycling. Thus, material, chemical, and energy cycles in wetlands appear to be optimally synergistic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24814907','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24814907"><span>Mechanisms of <span class="hlt">water</span> interaction with <span class="hlt">pore</span> systems of hydrochar and pyrochar from poplar forestry waste.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Conte, Pellegrino; Hanke, Ulrich M; Marsala, Valentina; Cimò, Giulia; Alonzo, Giuseppe; Glaser, Bruno</p> <p>2014-05-28</p> <p>The aim of this study was to understand the <span class="hlt">water</span>-surface interactions of two chars obtained by gasification (pyrochar) and hydrothermal carbonization (hydrochar) of a poplar biomass. The two samples revealed different chemical compositions as evidenced by solid state (13)C NMR spectroscopy. In fact, hydrochar resulted in a lignin-like material still containing oxygenated functionalities. Pyrochar was a polyaromatic system in which no heteronuclei were detected. After saturation with <span class="hlt">water</span>, hydrochar and pyrochar were analyzed by fast field cycling (FFC) NMR relaxometry. Results showed that <span class="hlt">water</span> movement in hydrochar was mainly confined in very small <span class="hlt">pores</span>. Conversely, <span class="hlt">water</span> movement in pyrochar led to the conclusion that a larger number of transitional and very large <span class="hlt">pores</span> were present. These results were confirmed by porosity evaluation derived from gas adsorption. Variable-temperature FFC NMR experiments confirmed a slow-motion regime due to a preferential diffusion of <span class="hlt">water</span> on the solid surface. Conversely, the higher number of large <span class="hlt">pores</span> in pyrochar allowed slow movement only up to 50 °C. As the temperature was raised to 80 °C, <span class="hlt">water</span> interactions with the <span class="hlt">pore</span> surface became weaker, thereby allowing a three-dimensional <span class="hlt">water</span> exchange with the bulk liquid. This paper has shown that <span class="hlt">pore</span> size distribution was more important than chemical composition in affecting <span class="hlt">water</span> movement in two chemically different charred systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18767050','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18767050"><span>Laser scanning confocal microscopy characterization of <span class="hlt">water</span> repellent distribution in a sandstone <span class="hlt">pore</span> network.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zoghlami, Karima; Gómez-Gras, David; Corbella, Mercè; Darragi, Fadila</p> <p>2008-11-01</p> <p>In the present work, we propose the use of the Laser Scanning Confocal Microscopy (LSCM) to determine the effect of <span class="hlt">water</span> repellents on rock's <span class="hlt">pore</span>-network configuration and interconnection. The rocks studied are sandstones of Miocene age, a building material that is commonly found in the architectural heritage of Tunisia. The porosity quantitative data of treated and untreated samples, obtained by mercury porosimetry tests, were compared. The results show a slight decrease in total porosity with the <span class="hlt">water</span> repellent treatment, which reduced both microporosity and macroporosity. This reduction produced a modification in <span class="hlt">pore</span> size distribution and a shift of the <span class="hlt">pore</span> access size mode interval toward smaller <span class="hlt">pore</span> diameters (from the 30-40 microm to the 20-30 microm intervals). The <span class="hlt">water</span> repellent was observed in SEM images as a continuous film coating grain surfaces; moreover, it was easily visualized in LSCM, by staining the <span class="hlt">water</span> repellent with Epodye fluorochrome, and the coating thickness was straightforwardly measured (1.5-2 microm). In fact, the combination of mercury intrusion porosimetry data and LSCM observations suggests that the porosity reduction and the shift of the <span class="hlt">pore</span> diameter mode were mainly due to the general reduction of <span class="hlt">pore</span> diameters, but also to the plugging of the smallest <span class="hlt">pores</span> (less than 3-4 microm in diameter) by the <span class="hlt">water</span> repellent film. Finally, the LSCM technique enabled the reconstruction of 3D views of the <span class="hlt">water</span> repellent coating film in the <span class="hlt">pore</span> network, indicating that its distribution was uniform and continuous over the 100 microm thick sample. The LSCM imaging facilitates the integration and interpretation of mercury porosimetry and SEM data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26799222','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26799222"><span>Adsorption of As(V) inside the <span class="hlt">pores</span> of porous hematite in <span class="hlt">water</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dai, Min; Xia, Ling; Song, Shaoxian; Peng, Changsheng; Lopez-Valdivieso, Alejandro</p> <p>2016-04-15</p> <p>As(V) adsorption inside the <span class="hlt">pores</span> of porous hematite in <span class="hlt">water</span> has been studied in this work. This study was performed on nonporous hematite and porous hematite prepared from the thermal decomposition of goethite and siderite through the measurements of adsorption isotherm, SEM-EDX, XRD and BET. The results demonstrated that the As(V) adsorption was difficult to be realized inside <span class="hlt">pores</span> if they were too small. This observation might be due to that the <span class="hlt">pore</span> entrances were blocked by the adsorbed ions and thus the inside surfaces became invalid for the adsorption. Only if the <span class="hlt">pore</span> size is large enough, the effective surface area inside <span class="hlt">pores</span> would be close to that on non-porous hematite for As(V) adsorption. In addition, it was found that siderite is better than goethite for preparing porous hematite with thermal decomposition as adsorbent for arsenic removal. Copyright © 2016 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70028771','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70028771"><span>Uranium distribution in the coastal <span class="hlt">waters</span> and <span class="hlt">pore</span> <span class="hlt">waters</span> of Tampa Bay, Florida</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Swarzenski, P.W.; Baskaran, M.</p> <p>2006-01-01</p> <p>The geochemical reactivity of uranium (238U) and dissolved organic carbon (DOC), Fe, Mn, Ba, and V was investigated in the <span class="hlt">water</span> column, <span class="hlt">pore</span> <span class="hlt">waters</span>, and across a river/estuarine mixing zone in Tampa Bay, Florida. This large estuary is impacted both by diverse anthropogenic activity and by extensive U-rich phosphatic deposits. Thus, the estuarine behavior of uranium may be examined relative to such known U enrichments and anthropogenic perturbations. Dissolved (< 0.45??m) uranium exhibited both removal and enrichment processes across the Alafia River/estuarine mixing zone relative to conservative mixing. Such non-conservative U behavior may be attributed to: i) physical mixing processes within the river; ii) U carrier phase reactivity; and/or iii) fluid exchange processes across sediment/<span class="hlt">water</span> interface. In the bay proper, U concentrations were ?????2 to 3 times greater than those reported for other estuarine systems and are likely a result of erosional inputs from the extensive, underlying U-rich phosphatic deposits. Whereas dissolved U concentrations generally did not approach seawater values (13.6??nM) along the Alafia River salinity transect, <span class="hlt">water</span> column U concentrations exceeded 16??nM in select regions of the bay. Within the hydrogeological framework of the bay, such enriched U may also be derived from advective fluid transport processes across the sediment/<span class="hlt">water</span> interface, such as submarine groundwater discharge (SGD) or hyporheic exchange within coastal rivers. <span class="hlt">Pore</span> <span class="hlt">water</span> profiles of U in Tampa Bay show both a flux into and out of bottom sediments, and average, diffusive U <span class="hlt">pore</span> <span class="hlt">water</span> fluxes (Jdiff) ranged from - 82.0 to 116.6??mol d- 1. It is likely that negative U fluxes imply seawater entrainment or infiltration (i.e., submarine groundwater recharge), which may contribute to the removal of <span class="hlt">water</span> column uranium. For comparison, a bay-wide, Ra-derived submarine groundwater discharge estimate for Tampa Bay (8??L m- 2 d- 1) yielded an average, advective</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/458312','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/458312"><span>Bioavailability of trace contaminants ({sup 241}Am, {sup 57}Co, {sup 137}Cs) to a benthic bivalve from <span class="hlt">pore</span> <span class="hlt">waters</span> and sediments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gagnon, C.; Stupakoff, I.; Fisher, N.S.</p> <p>1995-12-31</p> <p>Sediments are major repositories of contaminants in <span class="hlt">marine</span> ecosystems and can serve as a source of some contaminants for benthic organisms. The authors used the clam Macoma balthica, a species employed in monitoring coastal contamination, to compare experimentally three uptake sources: overlying <span class="hlt">water</span>, ingested surface sediment and anoxic <span class="hlt">pore</span> <span class="hlt">water</span>. They studied the bioavailability of selected radionuclides ({sup 241}Am, {sup 57}Co, {sup 137}Cs) representing a large range of particle reactivity. For comparison, the authors also used CH{sub 3} {sup 203}Hg, which is highly assimilated by <span class="hlt">marine</span> organisms. Clams were exposed separately to contaminated overlying <span class="hlt">water</span>, surface oxic sediment and anoxic sediment. Radioactivity in animals was determined at the end of the exposure period. {sup 137}CS, which is not particle reactive in seawater, was not bioaccumulated from any source. {sup 241}Am and {sup 57}Co concentration factors in clams obtained from overlying <span class="hlt">water</span> were approximately an order of magnitude lower than that of CH{sub 3} {sup 203}Hg. Ingested oxidized sediment particles do not appear to be a significant source for these radionuclides. {sup 241}Am, {sup 57}Co and CH{sub 3} {sup 203}Hg were bioconcentrated from anoxic <span class="hlt">pore</span> <span class="hlt">waters</span>, but the highly particle-reactive {sup 241}Am was mostly adsorbed onto the clam`s shell. The bioconcentration of CH{sub 3} {sup 203}Hg from <span class="hlt">pore</span> <span class="hlt">waters</span> was, however, only one tenth of that from overlying <span class="hlt">water</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9341E..0GC','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9341E..0GC"><span>Analysis of quasi-periodic <span class="hlt">pore</span>-network structure of centric <span class="hlt">marine</span> diatom frustules</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cohoon, Gregory A.; Alvarez, Christine E.; Meyers, Keith; Deheyn, Dimitri D.; Hildebrand, Mark; Kieu, Khanh; Norwood, Robert A.</p> <p>2015-03-01</p> <p>Diatoms are a common type of phytoplankton characterized by their silica exoskeleton known as a frustule. The diatom frustule is composed of two valves and a series of connecting girdle bands. Each diatom species has a unique frustule shape and valves in particular species display an intricate pattern of <span class="hlt">pores</span> resembling a photonic crystal structure. We used several numerical techniques to analyze the periodic and quasi-periodic valve <span class="hlt">pore</span>-network structure in diatoms of the Coscinodiscophyceae order. We quantitatively identify defect locations and <span class="hlt">pore</span> spacing in the valve and use this information to better understand the optical and biological properties of the diatom.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70014414','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014414"><span>The representativeness of <span class="hlt">pore</span> <span class="hlt">water</span> samples collected from the unsaturated zone using pressure-vacuum lysimeters</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Peters, C.A.; Healy, R.W.</p> <p>1988-01-01</p> <p>Studies have indicated that the chemistry of <span class="hlt">water</span> samples may be altered by the collection technique, creating concern about the representativeness of the <span class="hlt">pore</span> <span class="hlt">water</span> samples obtained. A study using soil <span class="hlt">water</span> pressure-vacuum lysimeters in outwash sand and glacial till deposits demonstrates that for non-dilute-solution samples the effect of pH of sampling with lysimeters is minimal, and that measured major cation and anion concentrations are representative of the natural <span class="hlt">pore</span> <span class="hlt">water</span>; trace-metal concentrations can be significantly altered by collection procedures at low concentrations. -from Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.H43A1433S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.H43A1433S"><span>Influences of Salinity Variations on <span class="hlt">Pore-water</span> Flow in Salt Marshes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shen, C.; Jin, G.; Xin, P.; Li, L.</p> <p>2013-12-01</p> <p>Salt marshes are important wetlands at the ocean-land interface with various ecological functions, serving as essential habitats for intertidal fauna, affecting the productivity of coastal <span class="hlt">waters</span> through nutrient exchange, moderating the greenhouse gas emission and global warming. They are influenced by various physical and biogeochemical processes, among which the <span class="hlt">pore-water</span> flow and associated solute transport processes play an important role in determining the material exchange between marsh soils and coastal <span class="hlt">water</span>. Previous studies have examined such processes under the solo or combined effects of tidal fluctuation, evapotranspiration, stratigraphy, inland freshwater input, and topography. However, these investigations have neglected the spatial and temporal salinity variations in surface <span class="hlt">water</span> and <span class="hlt">pore-water</span>, which commonly exist in salt marshes due to the impacts of tidal inundation, precipitation and evapotranspiration. The density contrast between the surface <span class="hlt">water</span> and <span class="hlt">pore-water</span> may lead to significant modifications of the <span class="hlt">pore-water</span> flow. Based on results from laboratory experiments and numerical simulations, we will demonstrate that: (1) under upward salinity gradients, flow instabilities in the form of fingers occur once the salinity contrast reaches a certain level, whereas under downward salinity gradients the system is stable; (2) because of the strong tidally-induced advective process occurring near the creek, both the number and size of fingers change gradually from the near-creek zone to the marsh interior; and (3) both upward and downward salinity gradients enhance the exchange between the surface <span class="hlt">water</span> and <span class="hlt">pore-water</span> in the marsh sediments. Keywords: Salt marshes; density effect; salinity gradient; <span class="hlt">pore-water</span> flow; fingers. Instabilities under upward salinity gradient Stable system under downward salinity gradient</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SuTMP...5a4003C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SuTMP...5a4003C"><span>A kinetic study of the spontaneous penetration of a <span class="hlt">water</span> drop into a hydrophobic <span class="hlt">pore</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Choi, Hyunho; Ma, Lian; Liang, Hong</p> <p>2017-03-01</p> <p>The spontaneous penetration of a <span class="hlt">water</span> drop into hydrophobic single-<span class="hlt">pored</span> samples of varying inside and outside diameters was studied. During penetration, the radius of the <span class="hlt">water</span> drop, its contact angle, the contact radius, and the penetration length inside the <span class="hlt">pore</span> were measured against time. Experimental results showed that a <span class="hlt">water</span> drop on the sample with the smaller <span class="hlt">pore</span> had a longer penetration time than a <span class="hlt">water</span> drop on the sample with the bigger <span class="hlt">pore</span>. A <span class="hlt">pored</span> sample with a small outside radius (thin tube) leads to a fast penetration rate presenting a parabolic trend in penetration versus time. The maximum penetration rate was observed when the contact angle was 90°. This is mainly due to the minimum radius of the drop at this angle as the drop radius directly relates to the Laplace pressure, which is the driving force in penetration. Two factors were identified as affecting penetration. The first is the receding contact angle leading to the stick-slip-like motion of a <span class="hlt">water</span> drop. The second is the outside radius of a <span class="hlt">pored</span> sample, which affects the penetration rate and trend. These factors were also correlated to the penetration process through theoretical analysis considering the geometry of the capillary system, volume conservation and momentum conservation. The initial contact angle and radius of a drop were determined by the outside radius of a <span class="hlt">pored</span> sample, which changed Laplace pressure with time, thus influencing the penetration trend and rate. This indicates that a thin tube promotes fast penetration, and the point of maximum penetration rate was shown to be later during the penetration. Understanding the effects of outside radius and receding contact angle in the kinetic aspect of drop penetration into a hydrophobic <span class="hlt">pore</span> is fundamentally important. This research is beneficial to the design of porous materials and in controlling the wetting and penetration process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24090882','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24090882"><span><span class="hlt">Marine</span> <span class="hlt">water</span> quality monitoring: a review.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Karydis, Michael; Kitsiou, Dimitra</p> <p>2013-12-15</p> <p><span class="hlt">Marine</span> <span class="hlt">water</span> quality monitoring is performed for compliance with regulatory issues, trend detection, model validation and assessment of the effectiveness of adopted policies. As the end users are managers and policy makers, the objectives should be of practical interest and the answers should reduce the uncertainty concerning environmental impact, supporting planning and decision making. Simple and clearcut answers on environmental issues require synthesis of the field information using statistics, simulation models and multiple criteria analysis (MCA). Statistics is easy to apply whereas simulation models enable researchers to forecast future trends as well as test different scenarios. MCA allows the co-estimation of socio-economic variables providing a compromise between scientists' and policy makers' priorities. In addition, stakeholders and the public have the right to know and participate. This article reviews <span class="hlt">marine</span> <span class="hlt">water</span> quality monitoring principles, design and data analysis procedures. A brief review of international conventions of regional seas is also included. Copyright © 2013 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002GeCoA..66.1311R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002GeCoA..66.1311R"><span>Solute transport in formations of very low permeability: profiles of stable isotope and dissolved noble gas contents of <span class="hlt">pore</span> <span class="hlt">water</span> in the Opalinus Clay, Mont Terri, Switzerland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rübel, André P.; Sonntag, Christian; Lippmann, Johanna; Pearson, F. J.; Gautschi, Andreas</p> <p>2002-04-01</p> <p><span class="hlt">Pore</span> <span class="hlt">water</span> profiles of <span class="hlt">water</span>, stable isotope, and dissolved noble gas content have been determined across the Opalinus Clay and adjacent formations at the rock laboratory at Mont Terri. We have found enhanced helium contents (up to [ 4He] = 1 × 10 -4 cubic centimeters at standard pressure and temperature per gram of <span class="hlt">pore</span> <span class="hlt">water</span>) and argon isotope ratios ( 40Ar/ 36Ar ratios up to 334) due to accumulation of 4He and 40Ar produced in situ. The helium profile was found to be in steady state with respect to in situ production and diffusive loss into the adjacent limestones where groundwater circulates. From this profile a representative mean value of the apparent diffusion coefficient for helium in the <span class="hlt">pore</span> <span class="hlt">water</span> of the whole formation was derived for the first time to be D a = 3.5 × 10 -11 m 2 · s -1, which is more than two orders of magnitude lower than the diffusion coefficient D 0 in free <span class="hlt">water</span>. The stable isotope profile, however, indicates a component of fossil <span class="hlt">marine</span> <span class="hlt">pore</span> <span class="hlt">water</span>, which has not yet been replaced by molecular diffusion of meteoric <span class="hlt">water</span> from the adjacent limestone and shale formations over the past 10 million years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoRL..41.4176D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoRL..41.4176D"><span><span class="hlt">Water</span> permeability in hydrate-bearing sediments: A <span class="hlt">pore</span>-scale study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dai, Sheng; Seol, Yongkoo</p> <p>2014-06-01</p> <p>Permeability is a critical parameter governing methane flux and fluid flow in hydrate-bearing sediments; however, limited valid data are available due to experimental challenges. Here we investigate the relationship between apparent <span class="hlt">water</span> permeability (k') and hydrate saturation (Sh), accounting for hydrate <span class="hlt">pore</span>-scale growth habit and meso-scale heterogeneity. Results from capillary tube models rely on cross-sectional tube shapes and hydrate <span class="hlt">pore</span> habits, thus are appropriate only for sediments with uniform hydrate distribution and known hydrate <span class="hlt">pore</span> character. Given our <span class="hlt">pore</span> network modeling results showing that accumulating hydrate in sediments decreases sediment porosity and increases hydraulic tortuosity, we propose a modified Kozeny-Carman model to characterize <span class="hlt">water</span> permeability in hydrate-bearing sediments. This model agrees well with experimental results and can be easily implemented in reservoir simulators with no empirical variables other than Sh. Results are also relevant to flow through other natural sediments that undergo diagenesis, salt precipitation, or bio-clogging.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1029434','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1029434"><span><span class="hlt">Pore-Water</span> Extraction Intermediate-Scale Laboratory Experiments and Numerical Simulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Oostrom, Martinus; Freedman, Vicky L.; Wietsma, Thomas W.; Truex, Michael J.</p> <p>2011-06-30</p> <p>A series of flow cell experiments was conducted to demonstrate the process of <span class="hlt">water</span> removal through <span class="hlt">pore-water</span> extraction in unsaturated systems. In this process, a vacuum (negative pressure) is applied at the extraction well establishing gas and <span class="hlt">water</span> pressure gradients towards the well. The gradient may force <span class="hlt">water</span> and dissolved contaminants, such as 99Tc, to move towards the well. The tested flow cell configurations consist of packings, with or without fine-grained well pack material, representing, in terms of particle size distribution, subsurface sediments at the SX tank farm. A <span class="hlt">pore</span> <span class="hlt">water</span> extraction process should not be considered to be equal to soil vapor extraction because during soil vapor extraction, the main goal may be to maximize gas removal. For <span class="hlt">pore</span> <span class="hlt">water</span> extraction systems, pressure gradients in both the gas and <span class="hlt">water</span> phases need to be considered while for soil vapor extraction purposes, gas phase flow is the only concern. In general, based on the limited set (six) of flow experiments that were conducted, it can be concluded that <span class="hlt">pore</span> <span class="hlt">water</span> extraction rates and cumulative outflow are related to <span class="hlt">water</span> content, the applied vacuum, and the dimensions of the sediment layer providing the extracted <span class="hlt">water</span>. In particular, it was observed that application of a 100-cm vacuum (negative pressure) in a controlled manner leads to <span class="hlt">pore-water</span> extraction until the <span class="hlt">water</span> pressure gradients towards the well approach zero. Increased cumulative outflow was obtained with an increase in initial <span class="hlt">water</span> content from 0.11 to 0.18, an increase in the applied vacuum to 200 cm, and when the <span class="hlt">water</span>-supplying sediment was not limited. The experimental matrix was not sufficiently large to come to conclusions regarding maximizing cumulative outflow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H31G1510Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H31G1510Z"><span>Dynamics of <span class="hlt">pore-water</span> and salt in estuarine marshes subjected to tide and evaporation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, C.; Shen, C.; Li, L.; Lockington, D. A.</p> <p>2015-12-01</p> <p>Salt dynamics in estuarine tidal marshes are strongly associated with their intrinsic hydrological processes and ecological behaviors, which are not well understood. Numerical simulations were carried out to investigate the transport and distribution of <span class="hlt">pore</span> <span class="hlt">water</span> and salt in a vertical cross section perpendicular to the tidal creek that subjects to spring-neap tide and evaporation. Vaporizing <span class="hlt">pore</span> <span class="hlt">water</span> from unsaturated soil surface with salt left in soils, the time-variant actual evaporation is affected by aerodynamic factors as well as soil conditions, including <span class="hlt">pore-water</span> saturation, solute concentration and the thickness of salt precipitation above the soil surface (efflorescence). Different simulation cases were performed by adjusting the tidal signal, marsh platform slope and soil properties. The simulation analysis indicates that, the tide-averaged soil salinity increases with the reduction of inundation period in a spring-neap tide cycle. As the salt accumulated by evaporation could leave soil from seepage back to seawater during ebbtide, the <span class="hlt">pore-water</span> salinity at the surface within the tidal range remains close to that of seawater. With the presence of hyper-saline soil and efflorescence, salt flat develops only in the area where capillary connection between evaporating surface and <span class="hlt">water</span>-saturated soil is maintained while tidal inundation absent. On the contrary, the sandy supratidal marsh where hydrological connections are disrupted keeps a relatively low soil salinity (40-60 ppt) and <span class="hlt">pore-water</span> saturation as evaporation remains low throughout the tidal cycles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22277549','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22277549"><span>Density profile of <span class="hlt">water</span> confined in cylindrical <span class="hlt">pores</span> in MCM-41 silica.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Soper, Alan K</p> <p>2012-02-15</p> <p>Recently, <span class="hlt">water</span> absorbed in the porous silica material MCM-41-S15 has been used to demonstrate an apparent fragile to strong dynamical crossover on cooling below ∼220 K, and also to claim that the density of confined <span class="hlt">water</span> reaches a minimum at a temperature around 200 K. Both of these behaviours are purported to arise from the crossing of a Widom line above a conjectured liquid-liquid critical point in bulk <span class="hlt">water</span>. Here it is shown that traditional estimates of the <span class="hlt">pore</span> diameter in this porous silica material (of order 15 Å) are too small to allow the amount of <span class="hlt">water</span> that is observed to be absorbed by these materials (around 0.5 g H(2)O/g substrate) to be absorbed only inside the <span class="hlt">pore</span>. Either the additional <span class="hlt">water</span> is absorbed on the surface of the silica particles and outside the <span class="hlt">pores</span>, or else the <span class="hlt">pores</span> are larger than the traditional estimates. In addition the low Q Bragg intensities from a sample of MCM-41-S15 porous silica under different dry and wet conditions and with different hydrogen isotopes are simulated using a simple model of the <span class="hlt">water</span> and silica density profile across the <span class="hlt">pore</span>. It is found the best agreement of these intensities with experimental data is shown by assuming the much larger <span class="hlt">pore</span> diameter of 25 Å (radius 12.5 Å). Qualitative agreement is found between these simulated density profiles and those found in recent empirical potential structure refinement simulations of the same data, even though the latter data did not specifically include the Bragg peaks in the structure refinement. It is shown that the change in the (100) peak intensity on cooling from 300 to 210 K, which previously has been ascribed to a change in density of the confined <span class="hlt">water</span> on cooling, can equally be ascribed to a change in density profile at constant average density. It is further pointed out that, independent of whether the <span class="hlt">pore</span> diameter really is as large as 25 Å or whether a significant amount of <span class="hlt">water</span> is absorbed outside the <span class="hlt">pore</span>, the earlier reports of a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20821486','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20821486"><span>Evaluation of hexavalent chromium in sediment <span class="hlt">pore</span> <span class="hlt">water</span> of the Hackensack River, New Jersey, USA.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Driscoll, Susan Kane; McArdle, Margaret E; Plumlee, Megan H; Proctor, Deborah</p> <p>2010-03-01</p> <p><span class="hlt">Pore</span> <span class="hlt">water</span> was collected from in situ passive samplers in Hackensack River sediments adjacent to a chromite ore processing residue site in Kearny, New Jersey. Although the sediments at this site contained more than 3,000 mg/kg of total chromium (Cr) and shallow groundwater adjacent to the shore contained more than 1,000 microg/L of hexavalent Cr [Cr(VI)], concentrations of dissolved total Cr and Cr(VI) in <span class="hlt">pore</span> <span class="hlt">water</span> (PW) samples were less than ambient <span class="hlt">water</span> quality criteria for Cr(VI) (50 microg/L). Concentrations of dissolved total Cr in <span class="hlt">pore</span> <span class="hlt">water</span> ranged from <2.0 to 5.3 microg/L, while Cr(VI) was not detected (<10 microg/L). These findings are consistent with previous studies, which demonstrated limited bioavailability and toxicity of Cr in sediment at this site and others with similar conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/136213','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/136213"><span>Mapping the fluid flow of the Mariana Mounds ridge flank hydrothermal system: <span class="hlt">Pore</span> <span class="hlt">water</span> chemical tracers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wheat, C.G.; McDuff, R.E.</p> <p>1995-05-10</p> <p>The authors present a conceptual model of fluid circulation in a ridge flank hydrothermal system, the Mariana Mounds. The model is based on chemical data from <span class="hlt">pore</span> <span class="hlt">waters</span> extracted from piston cores and from push cores collected by deep-sea research vessel Alvin in small, meter-sized mounds situated on a local topographic high. These mounds are located within a region of heat flow exceeding that calculated from a conductive model and are zones of strong <span class="hlt">pore</span> <span class="hlt">water</span> upflow. The authors have interpreted the chemical data with time-dependent transport-reaction models to estimate <span class="hlt">pore</span> <span class="hlt">water</span> velocities. In the mounds themselves <span class="hlt">pore</span> <span class="hlt">water</span> velocities reach several meters per year to kilometers per year. Within about 100 m from these zones of focused upflow velocities decrease to several centimeters per year up to tens of centimeters per year. A large area of low heat flow surrounds these heat flow and topographic highs, with upwelling <span class="hlt">pore</span> <span class="hlt">water</span> velocities less than 2 cm/yr. In some nearby cores, downwelling of bottom seawater is evident but at speeds less than 2 cm/yr. Downwelling through the sediments appears to be a minor source of seawater recharge to the basaltic basement. The authors conclude that the principal source of seawater recharge to basement is where basement outcrops exist, most likely a scarpt about 2-4 km to the east and southeast of the study area. 71 refs., 14 figs., 3 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017R%26QE...59..812B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017R%26QE...59..812B"><span>Dielectric Losses in Supercooled <span class="hlt">Pore</span> <span class="hlt">Water</span> at a Frequency of 34 GHz</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bordonsky, G. S.; Orlov, A. O.; Schegrina, K. A.</p> <p>2017-03-01</p> <p>We present the results of measuring the coefficient of specific attenuation in supercooled <span class="hlt">water</span> in the <span class="hlt">pores</span> of silica gel at a frequency of 34 GHz in the temperature range from +20°C to -190°C. It is shown that in moistened silica gel with nanosized <span class="hlt">pores</span>, noticeable radiation losses occur down to a temperature of about -100°C. This is due to the presence of a certain amount of liquid <span class="hlt">water</span> in the <span class="hlt">pore</span> space. Part of the <span class="hlt">water</span>, which is strongly bound with the surface of the <span class="hlt">pores</span>, does not freeze at temperatures down to -136°C, at which vitrification takes place. The properties of the other fraction, which is weakly bound with the surface are close to that for the volumetric <span class="hlt">water</span>, i.e., it crystallizes completely on being cooled down to the critical temperature -(38-45)°C, which is determined by the properties of the surrounding medium. Absorption of the electromagnetic radiation in supercooled <span class="hlt">water</span> captures in <span class="hlt">pores</span> should be allowed for, e.g., in the problems of radiation transfer in an atmospheric moistened aerosol, especially in the millimeter</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22416023','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22416023"><span>Effect of the hydroaffinity and topology of <span class="hlt">pore</span> walls on the structure and dynamics of confined <span class="hlt">water</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Harrach, Michael F. Klameth, Felix; Drossel, Barbara; Vogel, Michael</p> <p>2015-01-21</p> <p>We perform molecular dynamics simulations to observe the structure and dynamics of SPC/E <span class="hlt">water</span> in amorphous silica <span class="hlt">pores</span> and amorphous ice <span class="hlt">pores</span> with radii slightly larger than 10 Å. In addition to atomically rough <span class="hlt">pores</span>, we construct completely smooth <span class="hlt">pores</span> such that the potential felt at a given distance from the <span class="hlt">pore</span> wall is an averaged atomic potential. As compared to rough walls, smooth walls induce stronger distortions of <span class="hlt">water</span> structure for both silica and ice confinements. On the other hand, unlike the smooth <span class="hlt">pores</span>, the rough <span class="hlt">pores</span> strongly slow down <span class="hlt">water</span> dynamics at the <span class="hlt">pore</span> wall. The slowdown vanishes when reducing the atomic charges in the wall, i.e., when varying the hydroaffinity, while keeping the surface topology, indicating that it is not a geometric effect. Rather, it is due to the fact that the wall atoms provide a static energy landscape along the surface, e.g., fixed anchor-points for hydrogen bonds, to which the <span class="hlt">water</span> molecules need to adapt, blocking channels for structural rearrangement. In the smooth <span class="hlt">pores</span>, <span class="hlt">water</span> dynamics can be faster than in the bulk liquid not only at the <span class="hlt">pore</span> wall but also in the <span class="hlt">pore</span> center. Changes in the tetrahedral order rather than in the local density are identified as the main cause for this change of the dynamical behavior in the center of smooth <span class="hlt">pores</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25612721','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25612721"><span>Effect of the hydroaffinity and topology of <span class="hlt">pore</span> walls on the structure and dynamics of confined <span class="hlt">water</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Harrach, Michael F; Klameth, Felix; Drossel, Barbara; Vogel, Michael</p> <p>2015-01-21</p> <p>We perform molecular dynamics simulations to observe the structure and dynamics of SPC/E <span class="hlt">water</span> in amorphous silica <span class="hlt">pores</span> and amorphous ice <span class="hlt">pores</span> with radii slightly larger than 10 Å. In addition to atomically rough <span class="hlt">pores</span>, we construct completely smooth <span class="hlt">pores</span> such that the potential felt at a given distance from the <span class="hlt">pore</span> wall is an averaged atomic potential. As compared to rough walls, smooth walls induce stronger distortions of <span class="hlt">water</span> structure for both silica and ice confinements. On the other hand, unlike the smooth <span class="hlt">pores</span>, the rough <span class="hlt">pores</span> strongly slow down <span class="hlt">water</span> dynamics at the <span class="hlt">pore</span> wall. The slowdown vanishes when reducing the atomic charges in the wall, i.e., when varying the hydroaffinity, while keeping the surface topology, indicating that it is not a geometric effect. Rather, it is due to the fact that the wall atoms provide a static energy landscape along the surface, e.g., fixed anchor-points for hydrogen bonds, to which the <span class="hlt">water</span> molecules need to adapt, blocking channels for structural rearrangement. In the smooth <span class="hlt">pores</span>, <span class="hlt">water</span> dynamics can be faster than in the bulk liquid not only at the <span class="hlt">pore</span> wall but also in the <span class="hlt">pore</span> center. Changes in the tetrahedral order rather than in the local density are identified as the main cause for this change of the dynamical behavior in the center of smooth <span class="hlt">pores</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('//www.loc.gov/pictures/collection/hh/item/hi0798.photos.367395p/','SCIGOV-HHH'); return false;" href="//www.loc.gov/pictures/collection/hh/item/hi0798.photos.367395p/"><span>Overview of the <span class="hlt">Marine</span> Railway No. 2 from the <span class="hlt">water</span>'s ...</span></a></p> <p><a target="_blank" href="http://www.loc.gov/pictures/collection/hh/">Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey</a></p> <p></p> <p></p> <p>Overview of the <span class="hlt">Marine</span> Railway No. 2 from the <span class="hlt">water</span>'s edge to Facility 233 - U.S. Naval Base, Pearl Harbor, <span class="hlt">Marine</span> Railway No. 2, Near intersection of Avenue G & Third Street, Pearl City, Honolulu County, HI</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21812405','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21812405"><span>Effect of <span class="hlt">pore</span> size on the condensation/evaporation transition of confined <span class="hlt">water</span> in equilibrium with saturated bulk <span class="hlt">water</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brovchenko, Ivan; Oleinikova, Alla</p> <p>2011-08-25</p> <p>The effect of <span class="hlt">pore</span> size on the condensation/evaporation transition of confined <span class="hlt">water</span> upon varying the strength of the <span class="hlt">water</span>-surface interaction is studied under conditions of equilibrium with saturated bulk. Monte Carlo simulations in the grand canonical ensemble were used to determine <span class="hlt">water</span> density in spherical <span class="hlt">pores</span> of radius R(p) = 9, 12, 15, 20, and 25 Å in the temperature range from T = 270 K to the bulk critical temperature. The critical values of the well depth of the <span class="hlt">water</span>-surface interaction potential, which mark the limits of the metastability of vapor and liquid phases in <span class="hlt">pores</span> (U(0)(cond) and U(0)(evap), respectively), were determined. U(0)(cond) strongly depends on temperature, practically does not depend on the <span class="hlt">pore</span> size, and corresponds to some particular density of <span class="hlt">water</span> vapor near a surface. In contrast, U(0)(evap) only slightly depends on temperature, depends strongly on <span class="hlt">pore</span> size, and corresponds to the density in the <span class="hlt">pore</span> interior by about 2% below the bulk value. The critical <span class="hlt">water-pore</span> interaction U(0)(c), which separates regimes of capillary condensation and capillary evaporation, is found to be changed from -1.75 to -0.94 kcal/mol when the <span class="hlt">pore</span> radius R(p) increases from 9 to 25 Å. The size dependence of U(0)(c) is attributed to the change of the contact angle due to the line tension effect. Extrapolation of the dependence U(0)(c)(R(p)) to the flat surface gives the critical value U(0)(c)(∞) ≈ -0.61 kcal/mol. © 2011 American Chemical Society</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/419580','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/419580"><span>New in-situ procedures for measuring trace metals in <span class="hlt">pore</span> <span class="hlt">waters</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhang, H.; Davison, W.; Grime, G.W.</p> <p>1995-12-31</p> <p>The most mobile and biological and chemically active fractions of trace metals in sediments are the dissolved components present in <span class="hlt">pore</span> <span class="hlt">waters</span>. Measuring metals in <span class="hlt">pore</span> <span class="hlt">waters</span> is complicated by the requirement for anoxic handling procedures. Due to the dynamic nature of sediment, steep concentration gradients extending over as little as 1 mm may develop at the sediment-<span class="hlt">water</span> interface. New procedures for measuring metals in <span class="hlt">pore</span> <span class="hlt">waters</span> using polyacrylamide gels as in-situ probes are described. The gel can be used to establish a diffusive equilibration in a thin-film (DET). Because the film is typically less than 1 mm thick, equilibration is achieved within five minutes and insertion of the gel assembly causes minimal disturbance of sediment. An alternative procedure is to use a diffusive gradient in a thin-film (DGT), whereby a monolayer of chelating resin is incorporated at one side of the gel. Such a technique provides a kinetic measurement of labile species in solution. If the supply of metal from solid phase sediment to <span class="hlt">pore</span> <span class="hlt">waters</span> is fast enough, DGT provides a quantitative estimate of labile metal concentration. Alternatively, it measures directly the rate of supply of metal from solid phase to <span class="hlt">pore</span> <span class="hlt">waters</span>. As both DET and DGT are simple procedures capable of submillimeter spatial resolution, they provide previously unobtainable information on trace metal concentrations and fluxes. Furthermore, DGT has the potential to be used as a long-term monitor, providing mean concentrations of metals in sediment <span class="hlt">pore</span> <span class="hlt">waters</span> over periods of days, weeks, or even months.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5456140','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5456140"><span>Experimental Investigation on <span class="hlt">Pore</span> Structure Characterization of Concrete Exposed to <span class="hlt">Water</span> and Chlorides</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Liu, Jun; Tang, Kaifeng; Qiu, Qiwen; Pan, Dong; Lei, Zongru; Xing, Feng</p> <p>2014-01-01</p> <p>In this paper, the <span class="hlt">pore</span> structure characterization of concrete exposed to deionised <span class="hlt">water</span> and 5% NaCl solution was evaluated using mercury intrusion porosity (MIP), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of calcium leaching, fly ash incorporation, and chloride ions on the evolution of <span class="hlt">pore</span> structure characteristics were investigated. The results demonstrate that: (i) in ordinary concrete without any fly ash, the leaching effect of the cement products is more evident than the cement hydration effect. From the experimental data, Ca(OH)2 is leached considerably with the increase in immersion time. The <span class="hlt">pore</span> structure of concrete can also be affected by the formation of an oriented structure of <span class="hlt">water</span> in concrete materials; (ii) incorporation of fly ash makes a difference for the performance of concrete submersed in solutions as the total porosity and the <span class="hlt">pore</span> connectivity can be lower. Especially when the dosage of fly ash is up to 30%, the <span class="hlt">pores</span> with the diameter of larger than 100 nm show significant decrease. It demonstrates that the <span class="hlt">pore</span> properties are improved by fly ash, which enhances the resistance against the calcium leaching; (iii) chlorides have a significant impact on microstructure of concrete materials because of the chemical interactions between the chlorides and cement hydrates. PMID:28788204</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23484767','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23484767"><span>Hydrophobic <span class="hlt">pore</span> array surfaces: wetting and interaction forces in <span class="hlt">water</span>/ethanol mixtures.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hansson, Petra M; Hormozan, Yashar; Brandner, Birgit D; Linnros, Jan; Claesson, Per M; Swerin, Agne; Schoelkopf, Joachim; Gane, Patrick A C; Thormann, Esben</p> <p>2013-04-15</p> <p>Interactions between and wetting behavior of structured hydrophobic surfaces using different concentrations of <span class="hlt">water</span>/ethanol mixtures have been investigated. Silica surfaces consisting of <span class="hlt">pore</span> arrays with different <span class="hlt">pore</span> spacings and <span class="hlt">pore</span> depths were made hydrophobic by silanization. Their static and dynamic contact angles were found to be independent of the <span class="hlt">pore</span> depth while fewer <span class="hlt">pores</span> on the surface, i.e. a closer resemblance to a flat surface, gave a lower contact angle. As expected, a higher amount of ethanol facilitated wetting on all the surfaces tested. Confocal Raman microscopy measurements proved both <span class="hlt">water</span> and ethanol to penetrate into the <span class="hlt">pores</span>. AFM colloidal probe force measurements clearly showed that formation of air cavitation was hindered between the hydrophobic surfaces in presence of ethanol, and an increase in ethanol concentration was followed by a smaller jump-in distance and a weaker adhesion force. On separation, an immediate jump-out of contact occurred. The measured forces were interpreted as being due to capillary condensation of ethanol between the surfaces giving rise to very unstable cavities immediately rupturing on surface separation.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28788204','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28788204"><span>Experimental Investigation on <span class="hlt">Pore</span> Structure Characterization of Concrete Exposed to <span class="hlt">Water</span> and Chlorides.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Jun; Tang, Kaifeng; Qiu, Qiwen; Pan, Dong; Lei, Zongru; Xing, Feng</p> <p>2014-09-16</p> <p>In this paper, the <span class="hlt">pore</span> structure characterization of concrete exposed to deionised <span class="hlt">water</span> and 5% NaCl solution was evaluated using mercury intrusion porosity (MIP), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of calcium leaching, fly ash incorporation, and chloride ions on the evolution of <span class="hlt">pore</span> structure characteristics were investigated. The results demonstrate that: (i) in ordinary concrete without any fly ash, the leaching effect of the cement products is more evident than the cement hydration effect. From the experimental data, Ca(OH)₂ is leached considerably with the increase in immersion time. The <span class="hlt">pore</span> structure of concrete can also be affected by the formation of an oriented structure of <span class="hlt">water</span> in concrete materials; (ii) incorporation of fly ash makes a difference for the performance of concrete submersed in solutions as the total porosity and the <span class="hlt">pore</span> connectivity can be lower. Especially when the dosage of fly ash is up to 30%, the <span class="hlt">pores</span> with the diameter of larger than 100 nm show significant decrease. It demonstrates that the <span class="hlt">pore</span> properties are improved by fly ash, which enhances the resistance against the calcium leaching; (iii) chlorides have a significant impact on microstructure of concrete materials because of the chemical interactions between the chlorides and cement hydrates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22656651','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22656651"><span>Ion transport through dimethyl sulfoxide (DMSO) induced transient <span class="hlt">water</span> <span class="hlt">pores</span> in cell membranes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>He, Fei; Liu, Weirong; Zheng, Shengchao; Zhou, Li; Ye, Benlan; Qi, Zhi</p> <p>2012-01-01</p> <p>It is well known that dimethyl sulphoxide (DMSO) increases membrane permeability, which makes it widely used as a vehicle to facilitate drug delivery across biological membranes. However, the mechanism of how DMSO increases membrane permeability has not been well understood. Recently, molecular dynamics simulations have demonstrated that DMSO can induce <span class="hlt">water</span> <span class="hlt">pores</span> in biological membranes, but no direct experimental evidence is so far available to prove the simulation result. Using FluxOR Tl⁺ influx assay and intracellular Ca²⁺ imaging technique, we studied the effect of DMSO on Tl⁺ and Ca²⁺ permeation across cell membranes. Upon application of DMSO on CHO-K1 cell line, Tl⁺ influx was transiently increased in a dose-dependent manner. The increase in Tl⁺ permeability induced by DMSO was not changed in the presence of blockers for K⁺ channel and Na⁺-K⁺ ATPase, suggesting that Tl⁺ permeates through transient <span class="hlt">water</span> <span class="hlt">pores</span> induced by DMSO to enter into the cell. In addition, Ca²⁺ permeability was significantly increased upon application of DMSO, indicating that the transient <span class="hlt">water</span> <span class="hlt">pores</span> induced by DMSO were non-selective <span class="hlt">pores</span>. Furthermore, similar results could be obtained from RAW264.7 macrophage cell line. Therefore, this study provided experimental evidence to support the prediction that DMSO can induce transient <span class="hlt">water</span> <span class="hlt">pores</span> in cell membranes, which in turn facilitates the transport of active substances across membranes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70031526','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70031526"><span>A simple <span class="hlt">pore</span> <span class="hlt">water</span> hydrogen diffusion syringe sampler</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Vroblesky, D.A.; Chapelle, F.H.; Bradley, P.M.</p> <p>2007-01-01</p> <p>Molecular hydrogen (H2) is an important intermediate product and electron donor in microbial metabolism. Concentrations of dissolved H 2 are often diagnostic of the predominant terminal electron-accepting processes in ground <span class="hlt">water</span> systems or aquatic sediments. H2 concentrations are routinely measured in ground <span class="hlt">water</span> monitoring wells but are rarely measured in saturated aquatic sediments due to a lack of simple and practical sampling methods. This report describes the design and development (including laboratory and field testing) of a simple, syringe-based H 2 sampler in (1) saturated, riparian sediments, (2) surface <span class="hlt">water</span> bed sediments, and (3) packed intervals of a fractured bedrock borehole that are inaccessible by standard pumped methods. ?? 2007 National Ground <span class="hlt">Water</span> Association.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/141734','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/141734"><span>Characterizing <span class="hlt">pore</span> sizes and <span class="hlt">water</span> structure in stimuli-responsive hydrogels</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hoffman, A.S.; Antonsen, K.P.; Ashida, T.; Bohnert, J.L.; Dong, L.C.; Nabeshima, Y.; Nagamatsu, S.; Park, T.G.; Sheu, M.S.; Wu, X.S.; Yan, Q.</p> <p>1993-12-31</p> <p>Hydrogels have been extensively investigated as potential matrices for drug delivery. In particular, hydrogels responsive to pH and temperature changes have been of greatest interest most recently. Proteins and peptide drugs are especially relevant for delivery from such hydrogel matrices due to the relatively {open_quotes}passive{close_quotes} and biocompatible microenvironment which should exist within the hydrogel aqueous <span class="hlt">pores</span>. The large molecular size of many proteins requires an interconnected large <span class="hlt">pore</span> structure. Furthermore, the gel <span class="hlt">pore</span> {open_quotes}walls{close_quotes} should not provide hydrophobic sites for strong interactions with proteins. In the special case of ion exchange release the protein would be attracted by opposite charges on the polymer backbones. Therefore, it is important both to control and to characterize the <span class="hlt">pore</span> structure and the <span class="hlt">water</span> character within a hydrogel to be used or protein or peptide drug delivery. This talk will critically review techniques for estimating these two key parameters in hydrogels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AdWR...87...56X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AdWR...87...56X"><span>Effects of macro-<span class="hlt">pores</span> on <span class="hlt">water</span> flow in coastal subsurface drainage systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xin, Pei; Yu, Xiayang; Lu, Chunhui; Li, Ling</p> <p>2016-01-01</p> <p>Leaching through subsurface drainage systems has been widely adopted to ameliorate saline soils. The application of this method to remove salt from reclaimed lands in the coastal zone, however, may be impacted by macro-<span class="hlt">pores</span> such as crab burrows, which are commonly distributed in the soils. We developed a three-dimensional model to investigate <span class="hlt">water</span> flow in subsurface drainage systems affected by macro-<span class="hlt">pores</span> distributed deterministically and randomly through Monte Carlo simulations. The results showed that, for subsurface drainage systems under the condition of continuous surface ponding, macro-<span class="hlt">pores</span> increased the hydraulic head in the deep soil, which in turn reduced the hydraulic gradient between the surface and deep soil. As a consequence, <span class="hlt">water</span> infiltration across the soil surface was inhibited. Since salt transport in the soil is dominated by advection, the flow simulation results indicated that macro-<span class="hlt">pores</span> decreased the efficiency of salt leaching by one order of magnitude, in terms of both the elapsed time and the amount of <span class="hlt">water</span> required to remove salt over the designed soil leaching depth (0.6 m). The reduction of the leaching efficiency was even greater in drainage systems with a layered soil stratigraphy. Sensitivity analyses demonstrated that with an increased penetration depth or density of macro-<span class="hlt">pores</span>, the leaching efficiency decreased further. The revealed impact of macro-<span class="hlt">pores</span> on <span class="hlt">water</span> flow represents a significant shortcoming of the salt leaching technique when applied to coastal saline soils. Future designs of soil amelioration schemes in the coastal zone should consider and aim to minimize the bypassing effect caused by macro-<span class="hlt">pores</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016HydJ...24.1821B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016HydJ...24.1821B"><span>Prediction of <span class="hlt">pore-water</span> pressure response to rainfall using support vector regression</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Babangida, Nuraddeen Muhammad; Mustafa, Muhammad Raza Ul; Yusuf, Khamaruzaman Wan; Isa, Mohamed Hasnain</p> <p>2016-11-01</p> <p>Nonlinear complex behavior of <span class="hlt">pore-water</span> pressure responses to rainfall was modelled using support vector regression (SVR). <span class="hlt">Pore-water</span> pressure can rise to disturbing levels that may result in slope failure during or after rainfall. Traditionally, monitoring slope <span class="hlt">pore-water</span> pressure responses to rainfall is tedious and expensive, in that the slope must be instrumented with necessary monitors. Data on rainfall and corresponding responses of <span class="hlt">pore-water</span> pressure were collected from such a monitoring program at a slope site in Malaysia and used to develop SVR models to predict <span class="hlt">pore-water</span> pressure fluctuations. Three models, based on their different input configurations, were developed. SVR optimum meta-parameters were obtained using k-fold cross validation and a grid search. Model type 3 was adjudged the best among the models and was used to predict three other points on the slope. For each point, lag intervals of 30 min, 1 h and 2 h were used to make the predictions. The SVR model predictions were compared with predictions made by an artificial neural network model; overall, the SVR model showed slightly better results. Uncertainty quantification analysis was also performed for further model assessment. The uncertainty components were found to be low and tolerable, with d-factor of 0.14 and 74 % of observed data falling within the 95 % confidence bound. The study demonstrated that the SVR model is effective in providing an accurate and quick means of obtaining <span class="hlt">pore-water</span> pressure response, which may be vital in systems where response information is urgently needed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AdWR..108....1R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AdWR..108....1R"><span><span class="hlt">Pore</span>-scale modeling of capillary trapping in <span class="hlt">water</span>-wet porous media: A new cooperative <span class="hlt">pore</span>-body filling model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruspini, L. C.; Farokhpoor, R.; Øren, P. E.</p> <p>2017-10-01</p> <p>We present a <span class="hlt">pore</span>-network model study of capillary trapping in <span class="hlt">water</span>-wet porous media. The amount and distribution of trapped non-wetting phase is determined by the competition between two trapping mechanisms - snap-off and cooperative <span class="hlt">pore</span>-body filling. We develop a new model to describe the <span class="hlt">pore</span>-body filling mechanism in geologically realistic <span class="hlt">pore</span>-networks. The model accounts for the geometrical characteristics of the <span class="hlt">pore</span>, the spatial location of the connecting throats and the local fluid topology at the time of the displacement. We validate the model by comparing computed capillary trapping curves with published data for four different <span class="hlt">water</span>-wet rocks. Computations are performed on <span class="hlt">pore</span>-networks extracted from micro-CT images and process-based reconstructions of the actual rocks used in the experiments. Compared with commonly used stochastic models, the new model describes more accurately the experimental measurements, especially for well connected porous systems where trapping is controlled by subtleties of the <span class="hlt">pore</span> structure. The new model successfully predicts relative permeabilities and residual saturation for Bentheimer sandstone using in-situ measured contact angles as input to the simulations. The simulated trapped cluster size distributions are compared with predictions from percolation theory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000GeCoA..64.3995A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000GeCoA..64.3995A"><span>Geochemical dynamics of the Atlantis II Deep (Red Sea): II. Composition of metalliferous sediment <span class="hlt">pore</span> <span class="hlt">waters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anschutz, Pierre; Blanc, Gérard; Monnin, Christophe; Boulègue, Jacques</p> <p>2000-12-01</p> <p>The Atlantis II Deep is an axial depression of the Red Sea filled with highly saline brines and covered by layered metalliferous sediment. We report new data on the vertical distribution of major salts and trace metals dissolved in the <span class="hlt">pore</span> <span class="hlt">waters</span> of the metalliferous sediments. We have studied the chemical composition of interstitial <span class="hlt">waters</span> of two sediment cores of the western (core 684) and southwestern (core 683) basins. The major dissolved elements are Na and Cl. Their concentrations are close to those of the brine overlying the sediment. The <span class="hlt">pore</span> <span class="hlt">waters</span> are undersaturated with respect to halite at the in situ conditions (62°C, 220 bars), but are saturated at the shipboard conditions (10°C, 1 bar). The salt and <span class="hlt">water</span> contents of the bulk sediment show that core 683 contained halite in the solid fraction. A part of it precipitated after core collection, but most of it was present in situ. Thermodynamic calculations with a <span class="hlt">water</span>-rock interaction model based on Pitzer's ion interaction approach reveal that equilibrium between the <span class="hlt">pore</span> <span class="hlt">waters</span> and anhydrite is achieved in sediment layers for which observations report the presence of this mineral. We used a transport model, which shows that molecular diffusion can smooth the profile of dissolved salt and partly erase the <span class="hlt">pore</span> <span class="hlt">water</span> record of past variations of salinity in the lower brine. For example, we calculated that the <span class="hlt">pore</span> <span class="hlt">water</span> record of modern variation of brine salinity is rapidly smoothed by molecular diffusion. The dissolved transition metals show large variations with depth in the interstitial <span class="hlt">waters</span>. The profiles of core 683 reflect the possible advection of hydrothermal fluid within the sediment of the southwestern basin. The distribution of dissolved metals in core 684 is the result of diagenetic reactions, mainly the reduction of Mn-oxide with dissolved Fe(II), the recrystallization of primary oxide minerals, and the precipitation of authigenic Mn-carbonates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17973759','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17973759"><span>A simple <span class="hlt">pore</span> <span class="hlt">water</span> hydrogen diffusion syringe sampler.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vroblesky, Don A; Chapelle, Francis H; Bradley, Paul M</p> <p>2007-01-01</p> <p>Molecular hydrogen (H(2)) is an important intermediate product and electron donor in microbial metabolism. Concentrations of dissolved H(2) are often diagnostic of the predominant terminal electron-accepting processes in ground <span class="hlt">water</span> systems or aquatic sediments. H(2) concentrations are routinely measured in ground <span class="hlt">water</span> monitoring wells but are rarely measured in saturated aquatic sediments due to a lack of simple and practical sampling methods. This report describes the design and development (including laboratory and field testing) of a simple, syringe-based H(2) sampler in (1) saturated, riparian sediments, (2) surface <span class="hlt">water</span> bed sediments, and (3) packed intervals of a fractured bedrock borehole that are inaccessible by standard pumped methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1912644B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1912644B"><span><span class="hlt">Pore</span>-scale distribution of mucilage affecting <span class="hlt">water</span> repellency in the rhizosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Benard, Pascal; Zarebanadkouki, Mohsen; Hedwig, Clemens; Holz, Maire; Ahmed, Mutez; Carminati, Andrea</p> <p>2017-04-01</p> <p>The hydraulic properties of the rhizosphere are altered by plants, fungi and microorganism. Plant roots release different compounds into the soil. One of these substances is mucilage, a gel which turns <span class="hlt">water</span> repellent upon drying. We introduce a conceptual model of mucilage deposition during soil drying and its impact on the soil wettability. As the soil dries, <span class="hlt">water</span> menisci recede and draw mucilage towards the contact region between particles where it is deposited. At high mucilage content, mucilage deposits expand into the open <span class="hlt">pore</span> space and finally block <span class="hlt">water</span> infiltration when a critical fraction of the <span class="hlt">pore</span> space is blocked. To test this hypothesis, we mixed mucilage and particles of different grain size, we let them dry and measured the contact angle using the sessile drop method. Mucilage deposition was visualized by light microscopy imaging. Contact angle measurements showed a distinct threshold-like behavior with a sudden increase in apparent contact angle at high mucilage concentrations. Particle roughness induced a more uniform distribution of mucilage. The observed threshold corresponds to the concentration when mucilage deposition occupies a critical fraction of the <span class="hlt">pore</span> space, as visualized with the microscope images. In conclusion, <span class="hlt">water</span> repellency is critically affected by the distribution of mucilage on the <span class="hlt">pore</span>-scale. This microscopic heterogeneity has to be taken into account in the description of macroscopic processes, like <span class="hlt">water</span> infiltration or rewetting of <span class="hlt">water</span> repellent soil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvL.119e6002M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvL.119e6002M"><span>Nanoconfinement in Slit <span class="hlt">Pores</span> Enhances <span class="hlt">Water</span> Self-Dissociation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Muñoz-Santiburcio, Daniel; Marx, Dominik</p> <p>2017-08-01</p> <p>We investigate the self-dissociation of <span class="hlt">water</span> that is nanoconfined between the sheets of a realistic layered mineral, FeS mackinawite, as well as between Lennard-Jones walls via ab initio simulations. By comparing it with the same reaction in bulk <span class="hlt">water</span> under various thermodynamic conditions, we show that such strong two-dimensional confinement between hard surfaces greatly enhances the self-dissociation process of water—thus increasing its ionic product Kw due to nanoconfinement. In addition to providing free energies, we analyze in detail the underlying dielectric properties in terms of dipole moment distributions, and thus the polarity of the liquid, as well as local polarization fluctuations as quantified by dielectric tensor profiles perpendicular to the lamella.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19..567S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19..567S"><span>Sedimentary and <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry linked to deglaciation and postglacial development of Lake Vättern, Sweden</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Swärd, Henrik; O´Regan, Matt; Kylander, Malin; Greenwood, Sarah; Mörth, Magnus; Jakobsson, Martin</p> <p>2017-04-01</p> <p>Lake Vättern, in south central Sweden, underwent profound environmental changes during the Late Weichselian deglaciation of Fennoscandia. It evolved from (i) a sub/proglacial lake situated at the westernmost rim of the Baltic Ice Lake (BIL) into (ii) a brackish to <span class="hlt">marine</span> phase where the Vättern basin was a part of the Yoldia Sea connecting the North and Baltic Seas, and finally to (iii) a freshwater basin as isostatic rebound following deglaciation led to its isolation. The sedimentary and <span class="hlt">pore</span> <span class="hlt">water</span> geochemical signatures associated with these dramatic environmental changes were investigated in a 74 m composite sediment core from southern Lake Vättern. This was accomplished using high-resolution X-ray fluorescence measurements of elemental data along with discrete measurements of total organic carbon (TOC), δ13C, mineralogical composition (XRD) and <span class="hlt">pore</span> <span class="hlt">water</span> chemistry. Proglacial sediments in Lake Vättern are devoid of organic matter, and show cyclic trends in elemental data, grain size and mineralogy. These are interpreted as varved sediments whose thickness decreases upcore from decimeters to millimeters. The coarse grained varves are enriched in Ca, Si, Zr and Sr and contain calcite while the fine grained varves are enriched in K, Rb, Ti and Fe and lack calcite. Overall, the presence of calcite is limited to the proglacial sediments and reflected in the elemental data by an abrupt decrease of Ca at the (i)/(ii) transition. This suggests a glacial/glaciofluvial origin for the calcite, likely eroded from local limestones that borders the lake basin in the northeast. The saline incursion at the beginning of phase (ii) is evident in <span class="hlt">pore</span> <span class="hlt">water</span> chemistry by a significant increase of the major sea <span class="hlt">water</span> species (Cl, Na, Mg, K and Ca) but is not clearly seen in the sedimentary geochemistry. Increased biological production in and around the lake during stage (iii) is strongly reflected in sedimentary geochemistry showing decreasing detrital inputs, increasing TOC</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1170501','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1170501"><span>Field Test Design Simulations of <span class="hlt">Pore-Water</span> Extraction for the SX Tank Farm</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Truex, Michael J.; Oostrom, Martinus</p> <p>2013-09-01</p> <p>A proof of principle test of <span class="hlt">pore</span> <span class="hlt">water</span> extraction is being performed by Washington River Protection Solutions for the U.S. Department of Energy, Office of River Protection. This test is being conducted to meet the requirements of Hanford Federal Facility Agreement and Consent Order (HFFACO) (Ecology et al. 1989) Milestone M 045-20, and is described in RPP-PLAN-53808, 200 West Area Tank Farms Interim Measures Investigation Work Plan. To support design of this test, numerical simulations were conducted to help define equipment and operational parameters. The modeling effort builds from information collected in laboratory studies and from field characterization information collected at the test site near the Hanford Site 241-SX Tank Farm. Numerical simulations were used to evaluate <span class="hlt">pore-water</span> extraction performance as a function of the test site properties and for the type of extraction well configuration that can be constructed using the direct-push installation technique. Output of simulations included rates of <span class="hlt">water</span> and soil-gas production as a function of operational conditions for use in supporting field equipment design. The simulations also investigated the impact of subsurface heterogeneities in sediment properties and moisture distribution on <span class="hlt">pore-water</span> extraction performance. Phenomena near the extraction well were also investigated because of their importance for <span class="hlt">pore-water</span> extraction performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010GGG....11.1X09H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010GGG....11.1X09H"><span><span class="hlt">Pore</span> <span class="hlt">water</span> chemistry of the Mariana serpentinite mud volcanoes: A window to the seismogenic zone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hulme, Samuel M.; Wheat, C. Geoffery; Fryer, Patricia; Mottl, Michael J.</p> <p>2010-01-01</p> <p>In 2003, we conducted a survey of 11 serpentinite mud volcanoes in the Mariana fore arc. Here we report sediment <span class="hlt">pore</span> <span class="hlt">water</span> data from navigated gravity and piston cores and from push cores collected by the ROV system Jason2-Medea. Systematic variations in profiles of <span class="hlt">pore</span> <span class="hlt">water</span> chemical compositions from these mud volcanoes are consistent with models that include active upflow of <span class="hlt">pore</span> <span class="hlt">water</span> relative to the surrounding serpentinite matrix. The speed of upwelling, based on fits of an advection-diffusion model to observed data (K, Na, Rb, and Cs), reaches a maximum of 36 cm/yr at Big Blue Seamount. Results from these simulations constrain the <span class="hlt">pore</span> <span class="hlt">water</span> composition at depth and the degree of additional alteration as the <span class="hlt">pore</span> <span class="hlt">water</span> ascends through the sampled section. For example, the transition metals (e.g., Mn, Fe, Co, Ni, Cu, and Mo) are mobilized under conditions of low upwelling speeds and microbial activity. Similarly, the rare earth elements (REE) show evidence of near-surface alteration. In addition to these surficial reactions, distinctive <span class="hlt">pore</span> <span class="hlt">water</span> compositional patterns exist as a function of the distance from the trench axis, which is a proxy for the depths of <span class="hlt">water</span> generation from the downgoing plate below each seamount. Systematic trends in the chemical composition of these slab-sourced fluids are consistent with increasing temperature and pressure at depth west of the trench. These trends include an increase in K, sulfate, carbonate alkalinity, Na/Cl, B, Mn, Fe, Co, Rb, Cs, Gd/Tb, Eu, and light REE (LREE) and a decrease in Ca, Sr, and Y with increasing distance from the trench. Mg and U are universally depleted in the upwelling <span class="hlt">water</span>. We constrain the thermal conditions along the décollement using concentrations of fluid mobile elements (K, B, Cs, and Rb) and the mobilization of LREE relative to heavy REE (HREE). The 80°C isotherm is estimated at a depth of 15 km between Blue Moon Seamount and Cerulean Springs. At slab depths of 17 to 24 km, <span class="hlt">pore</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11257871','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11257871"><span><span class="hlt">Pore</span> distribution effect of activated carbon in adsorbing organic micropollutants from natural <span class="hlt">water</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ebie, K; Li, F; Azuma, Y; Yuasa, A; Hagishita, T</p> <p>2001-01-01</p> <p>Adsorption isotherms of organic micropollutants in coexistence with natural organic matter (NOM) were analyzed to evaluate the impacts of <span class="hlt">pore</span> size distribution of activated carbon (AC) on the competition effects of the NOM. Single solute adsorption experiments and simultaneous adsorption experiments with NOM contained in a coagulation-pretreated surface <span class="hlt">water</span> were performed for four agricultural chemicals and three coal-based activated carbons (ACs) having different <span class="hlt">pore</span> distributions. The results showed that, for all the carbons used, the adsorption capacity of the chemicals was reduced distinctly in the presence of NOM. Such a reduction was more apparent for AC with a larger portion of small <span class="hlt">pores</span> suitable for the adsorption of small organic molecules and for the agricultural chemicals with a more hydrophilic nature. Ideal adsorbed solution theory (IAST) incorporated with the Freundlich isotherm expression (IAST-Freundlich model) could not interpret the impact of NOM on the adsorption capacity of the chemicals unless a <span class="hlt">pore</span> blockage effect caused by the adsorption of NOM was also considered. By taking into account this effect, the adsorption isotherm of the chemicals in the presence of NOM was well described, and the capacity reduction caused by the NOM was quantitatively assessed from the viewpoints of the site competition and the <span class="hlt">pore</span> blockage. Analytical results clearly indicated that <span class="hlt">pore</span> blockage was an important competition mechanism that contributed to 10-99% of the total capacity reductions of the chemicals, the level depended greatly on the ACs, the chemicals and the equilibrium concentrations, and could possibly be alleviated by broadening the <span class="hlt">pore</span> size distributions of the ACs to provide a large volume percentage for <span class="hlt">pores</span> with sizes above 30 A.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12963306','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12963306"><span>Mercury in contaminated sediments and <span class="hlt">pore</span> <span class="hlt">waters</span> enriched in sulphate (Tagus Estuary, Portugal).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Canário, J; Vale, C; Caetano, M; Madureira, M J</p> <p>2003-01-01</p> <p>Three sediment cores, collected nearby the effluent of a chlor-alkali industry, were sliced in 0.5-cm layers and centrifuged for <span class="hlt">pore</span> <span class="hlt">water</span> extraction. Mercury, Fe and Mn were determined in the solids as total concentration, hydroxylamine extractable fraction and HCl extractable fraction. Sulphur was determined in the HCl extraction. Total and reactive mercury, chlorinity, S(2-), SO(4)(2-), total Fe, and total Mn were measured in <span class="hlt">pore</span> <span class="hlt">waters</span>. The solids contained 3.0-60 nmol g(-1) of total Hg and <span class="hlt">pore</span> <span class="hlt">waters</span> 70-5800 pM of total Hg and 1.8-76 pM of reactive mercury. <span class="hlt">Pore</span> <span class="hlt">waters</span> presented 2.3-94 times more sulphate than the overlying estuarine <span class="hlt">waters</span> due to the input from the industry. In layers where hydroxylamine extractable Fe exhibited a broad maximum (precipitation of Fe-oxides) sulphate was reduced to S(2-). The competition between the high content of SO(4)(2-) and Fe(III) as electron acceptors, in chemical reactions occurring in the upper sediments, may explain the co-existence of S(2-) and Fe-oxides in the same layers. Mercury was detected in the hydroxylamine extracts (20-29 nmolg(-1)) in the layers where Fe-oxides were formed, and reactive dissolved Hg showed minimum concentrations. The excess of sulphate in <span class="hlt">pore</span> <span class="hlt">waters</span> favoured the abundant Fe-oxides in the upper solid sediments, which appear to work as a barrier limiting the escape of mercury to the <span class="hlt">water</span> column.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....11169B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....11169B"><span>Distribution of dissolved silver in <span class="hlt">marine</span> <span class="hlt">waters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barriada, J. L.; Achterberg, E. P.; Tappin, A.; Truscott, J.</p> <p>2003-04-01</p> <p>Silver is one of the most toxic heavy metals, surpassed only by mercury [1-3]. Monitoring of dissolved silver concentrations in natural <span class="hlt">waters</span> is therefore of great importance. The determination of dissolved silver in <span class="hlt">waters</span> is not without challenges, because of its low (picomolar) concentrations. Consequently, there are only a few reported studies in <span class="hlt">marine</span> <span class="hlt">waters</span>, which have been performed in USA [4-6] and Japan [7]. The analytical techniques used in the reported studies for the determination of silver in seawater were Graphite Furnace Atomic Absorption Spectroscopy (GFAAS) after solvent extraction [2,4,5], and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) after solvent extraction or solid phase extraction [7,8]. In this contribution, we will present an optimised Magnetic Sector (MS) ICP-MS technique for the determination of dissolved silver in <span class="hlt">marine</span> <span class="hlt">waters</span>. The MS-ICP-MS method used anion exchange column to preconcentrate silver from saline <span class="hlt">waters</span>, and to remove the saline matrix. The ICP-MS method has been used successfully to determine total dissolved silver in estuarine and oceanic samples. Bibliography 1. H. T. Ratte, Environ. Toxicol. Chem. 1999, 18: p. 89-108. 2. R. T. Herrin, A. W. Andren and D. E. Armstrong, Environ. Sci. Technol. 2001, 35: 1953-1958. 3. D. E. Schildkraut, P. T. Dao, J. P. Twist, A. T. Davis and K. A. Robillard, Environ. Toxicol. Chem. 1998, 17: 642-649. 4. E. Breuer, S. A. Sanudo-Wilhelmy and R. C. Aller, Estuaries. 1999, 22:603-615. 5. A. R. Flegal, S. A. Sanudowilhelmy and G. M. Scelfo, Mar. Chem. 1995, 49: 315-320. 6. S. N. Luoma, Y. B. Ho and G. W. Bryan, Mar. Pollut. Bull. 1995, 31: 44-54. 7. Y. Zhang, H. Amakawa and Y. Nozaki, Mar. Chem. 2001, 75: 151-163. 8. L. Yang and R. E. Sturgeon, J. Anal. At. Spectrom. 2002, 17: 88-93.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA544835','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA544835"><span>Shallow <span class="hlt">Water</span> <span class="hlt">Marine</span> UXO Detection Survey, United States <span class="hlt">Marine</span> Corps Base, Camp Lejeune, North Carolina</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2011-04-01</p> <p>U.S. <span class="hlt">Marine</span> Corps Base, Camp Lejuene , North Carolina, ESTCP Project No. MM-200935, February. This page left blank intentionally. A-1...UXO Detection Survey United States <span class="hlt">Marine</span> Corps Base, Camp Lejeune, North Carolina April 2011 Report Documentation Page Form ApprovedOMB No. 0704...4. TITLE AND SUBTITLE Shallow <span class="hlt">Water</span> <span class="hlt">Marine</span> UXO Detection Survey United States <span class="hlt">Marine</span> Corps Base, Camp Lejeune, North Carolina 5a. CONTRACT NUMBER</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSCT44A0224W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSCT44A0224W"><span>Factors controlling concentration and decomposition of dissolved organic matter in <span class="hlt">pore</span> <span class="hlt">water</span> on the shelf of the East China Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Y.; Wang, X.; Ye, Q.; Liu, M. S.; Zhang, J.</p> <p>2016-02-01</p> <p>Understanding of microbial communities and carbon cycling in <span class="hlt">marine</span> sediment fills in the gap of biogeochemical cycle of carbon and nutrients in the largest carbon reservoir. Nevertheless, information on what factors controlling concentration and decomposition of dissolved organic matter (DOM) and their interaction with the nutrient cycles in shelf sediments is limited studied. Here, we determined variation of dissolved organic carbon (DOC) and nutrients and DOM quality by excitation-emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC) in two contrasting core sediments' <span class="hlt">pore</span> <span class="hlt">water</span> systems (C10 vs N6 station). By utilizing Miseq illumine sequencing V4-V5 regions of 16S rRNA gene, we found the distinct bacterial community structures between two core samples. C10 harbor abundant denitrifies, whereas bacterial groups participated in degrading high molecular weighted organic matters in N6. Our results show that the metabolic activity of the benthic community can be a significant factor controlling the dynamic of DOM and nutrients in the <span class="hlt">pore</span> <span class="hlt">water</span>. Furthermore, in the absence of nitrate, high DOM accelerated ammonium production and increased the recalcitrant nature of DOC accumulated in the core. In contrast, the co-occurrence of high nitrate concentrations and low bioavailability of DOM enhanced the denitrification process in C10 station. The optical properties of DOM, however, also changed successively along the increasing depth in N6 but limited variation in C10 core. Our results suggest that both original composition of DOM and microbial community are important drivers controlling DOM and nutrients dynamics in <span class="hlt">marine</span> sediment. The biogeochemical processes controlling the DOM composition are complex and merit further investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70026071','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70026071"><span>A multi-level <span class="hlt">pore-water</span> sampler for permeable sediments</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Martin, J.B.; Hartl, K.M.; Corbett, D.R.; Swarzenski, P.W.; Cable, J.E.</p> <p>2003-01-01</p> <p>The construction and operation of a multi-level piezometer (multisampler) designed to collect <span class="hlt">pore</span> <span class="hlt">water</span> from permeable sediments up to 230 cm below the sediment-<span class="hlt">water</span> interface is described. Multisamplers are constructed from 1 1/2 inch schedule 80 PVC pipe. One-quarter-inch flexible PVC tubing leads from eight ports at variable depths to a 1 1/2 inch tee fitting at the top of the PVC pipe. Multisamplers are driven into the sediments using standard fence-post drivers. <span class="hlt">Water</span> is pumped from the PVC tubing with a peristaltic pump. Field tests in Banana River Lagoon, Florida, demonstrate the utility of multisamplers. These tests include collection of multiple samples from the permeable sediments and reveal mixing between shallow <span class="hlt">pore</span> <span class="hlt">water</span> and overlying lagoon <span class="hlt">water</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26074669','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26074669"><span>Polymerization and Functionalization of Membrane <span class="hlt">Pores</span> for <span class="hlt">Water</span> Related Applications.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xiao, Li; Davenport, Douglas M; Ormsbee, Lindell; Bhattacharyya, Dibakar</p> <p>2015-04-29</p> <p>Poly(vinylidene fluoride) (PVDF) was modified by chemical treatments in order to create active double bonds to obtain covalent grafting of poly(acrylic acid) (PAA) on membrane. The attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectrum confirms the formation of conjugated C=C double bonds with surface dehydrofluorination. The membrane morphology was studied by scanning electron microscopy (SEM). The surface composition was characterized by X-ray photoelectron spectroscopy (XPS). The thermal stability of the dehydrofluorinated membrane (Def-PVDF) and functionalized membranes were investigated by differential scanning calorimetry (DSC) analysis. The influence of covalently attached PAA on Def-PVDF membrane has been investigated to determine its effect on the transport of <span class="hlt">water</span> and charged solute. Variations in the solution pH show an effect on both permeability and solute retention in a reversible fashion. Metal nanoparticles were also immobilized in the membrane for the degradation of toxic chlorinated organics from <span class="hlt">water</span>. In addition, PVDF membranes with an asymmetric and sponge-like morphology were developed by immersion-precipitation phase-inversion methods in both lab-scale and large-scale. The new type of spongy PVDF membrane shows high surface area with higher yield of PAA functionalization. The ion-capacity with Ca(2+) ions was also investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4461045','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4461045"><span>Polymerization and Functionalization of Membrane <span class="hlt">Pores</span> for <span class="hlt">Water</span> Related Applications</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2015-01-01</p> <p>Poly(vinylidene fluoride) (PVDF) was modified by chemical treatments in order to create active double bonds to obtain covalent grafting of poly(acrylic acid) (PAA) on membrane. The attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectrum confirms the formation of conjugated C=C double bonds with surface dehydrofluorination. The membrane morphology was studied by scanning electron microscopy (SEM). The surface composition was characterized by X-ray photoelectron spectroscopy (XPS). The thermal stability of the dehydrofluorinated membrane (Def-PVDF) and functionalized membranes were investigated by differential scanning calorimetry (DSC) analysis. The influence of covalently attached PAA on Def-PVDF membrane has been investigated to determine its effect on the transport of <span class="hlt">water</span> and charged solute. Variations in the solution pH show an effect on both permeability and solute retention in a reversible fashion. Metal nanoparticles were also immobilized in the membrane for the degradation of toxic chlorinated organics from <span class="hlt">water</span>. In addition, PVDF membranes with an asymmetric and sponge-like morphology were developed by immersion-precipitation phase-inversion methods in both lab-scale and large-scale. The new type of spongy PVDF membrane shows high surface area with higher yield of PAA functionalization. The ion-capacity with Ca2+ ions was also investigated. PMID:26074669</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMOS43B1403W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMOS43B1403W"><span>Development of an In Situ Raman Probe for <span class="hlt">Pore</span> <span class="hlt">Water</span> Geochemistry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walz, P. M.; Zhang, X.; Hester, K.; Kirkwood, W. J.; Ussler, W.; Peltzer, E. T.; Brewer, P. G.</p> <p>2009-12-01</p> <p>Scientists and engineers at the Monterey Bay Aquarium Research Institute have developed a ROV-deployable sampling probe utilizing laser Raman spectroscopy for study of sediment <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry. The Raman technique has already been used with deep sea ROV platforms successfully performing in situ measurement on targets of scientific interest including gas and hydrothermal vent fluids, and complex gas hydrates. However, in situ measurement of sediment <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry by laser Raman methods has so far been an intractable problem because sediment particles strongly fluorescence and insufficient amounts of <span class="hlt">pore</span> <span class="hlt">water</span> can be extracted before filters become occluded by sediment particles. Our design incorporates a series of novel elements into a slender 35-cm-long probe that can be inserted into sediment using an ROV manipulator to obtain concentration profiles. <span class="hlt">Pore</span> <span class="hlt">water</span> is drawn through a 10-μm stainless steel filter that forms the probe tip into a low volume sample chamber (0.1 mL) using a small hydraulic pump controlled by the ROV. The pump is also used for flushing and clearing filter surfaces. The sampling process is repeated as we proceed incrementally deeper into the sediment. Light (532 nm) from a Raman laser system mounted on the ROV is conveyed by a fiber optic cable to the probe head and focused within the center of the sample chamber through a sapphire-windowed optical cell. Control of the Raman system and spectra acquisition are performed onboard the ship via a laptop computer in the ROV control room. Advantages of this rapid mode of detection include measurement of sulfate gradients in near-seafloor sediments at a vertical scale not easily obtainable using traditional coring and extraction techniques, direct measurement of the dissolved sulfide species H2S and HS-, and measurement of dissolved methane without incurring substantial degassing during core recovery. The chemical measurements are made quantitative by calculating an intensity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1810516Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1810516Q"><span>Relating soil <span class="hlt">pore</span> geometry to soil <span class="hlt">water</span> content dynamics decomposed at multiple frequencies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qin, Mingming; Gimenez, Daniel; Cooper, Miguel</p> <p>2016-04-01</p> <p>Soil structure is a critical factor determining the response of soil <span class="hlt">water</span> content to meteorological inputs such as precipitation. Wavelet analysis can be used to filter a signal into several wavelet components, each characterizing a given frequency. The purpose of this research was to investigate relationships between the geometry of soil <span class="hlt">pore</span> systems and the various wavelet components derived from soil <span class="hlt">water</span> content dynamics. The two study sites investigated were located in the state of São Paulo, Brazil. Each site was comprised of five soil profiles, the first site was situated along a 300-meter transect with about 10% slope in a tropical semi-deciduous forest, while the second one spanned 230-meter over a Brazilian savanna with a slope of about 6%. For each profile, between two to four <span class="hlt">Water</span> Content Reflectometer CS615 (Campbell Scientific, Inc.) probes were installed according to horizonation at depths varying between 0.1 m and 2.3 m. Bulk soil, three soil cores, and one undisturbed soil block were sampled from selected horizons for determining particle size distributions, <span class="hlt">water</span> retention curves, and <span class="hlt">pore</span> geometry, respectively. <span class="hlt">Pore</span> shape and size were determined from binary images obtained from resin-impregnated blocks and used to characterize <span class="hlt">pore</span> geometry. Soil <span class="hlt">water</span> contents were recorded at a 20-minute interval over a 4-month period. The Mexican hat wavelet was used to decompose soil <span class="hlt">water</span> content measurements into wavelet components. The responses of wavelet components to wetting and drying cycles were characterized by the median height of the peaks in each wavelet component and were correlated with particular <span class="hlt">pore</span> shapes and sizes. For instance, large elongated and irregular <span class="hlt">pores</span>, largely responsible for the transmission of <span class="hlt">water</span>, were significantly correlated with wavelet components at high frequencies (40 minutes to 48 hours) while rounded <span class="hlt">pores</span>, typically associated to <span class="hlt">water</span> retention, were only significantly correlated to lower frequency ranges</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD0669506','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD0669506"><span>REPRODUCTIVE PERIODICITIES OF <span class="hlt">MARINE</span> ANIMALS OF TROPICAL MIDDLE EAST <span class="hlt">WATERS</span>.</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p></p> <p>AQUATIC ANIMALS, REPRODUCTION(PHYSIOLOGY), <span class="hlt">MARINE</span> BIOLOGY, BIOLOGICAL RHYTHMS, ECHINODERMATA , MOLLUSCA, CRUSTACEA, PERIODIC VARIATIONS, SEA <span class="hlt">WATER</span>, TEMPERATURE, INLAND WATERWAYS, RED SEA, MIDDLE EAST.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MS%26E...96a2011B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MS%26E...96a2011B"><span><span class="hlt">Pore</span> Distribution and <span class="hlt">Water</span> Uptake in a Cenosphere-Cement Paste Composite Material</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baronins, J.; Setina, J.; Sahmenko, G.; Lagzdina, S.; Shishkin, A.</p> <p>2015-11-01</p> <p>Alumina silicate cenospheres (CS) is a significant waste material from power plants that use a coal. Use CS as Portland cement replacement material gives opportunity to control physical and mechanical properties and makes a product lighter and more cost-effective. In the frame of this study, Portland cement paste samples were produced by adding CS in the concentration range from 0 to 40 volume %. <span class="hlt">Water</span> uptake of hardened samples was checked and <span class="hlt">pore</span> size distribution by using the mercury porosimetry was determined. In a cold climate where the temperature often falls below 0 °C, it is important to avoid the amount of micrometer sized <span class="hlt">pores</span> in the final structure and to decrease <span class="hlt">water</span> absorption capacity of material. In winter conditions, <span class="hlt">water</span> fills such <span class="hlt">pores</span> and causes additional stresses to their walls by expansion while freezing. It was found that generally <span class="hlt">water</span> uptake capacity for cement paste samples decreased up to 20% by increasing the concentration of CS up to 40 volume %, at the same time, the volume of micrometer sized opened <span class="hlt">pores</span> increases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAG...135..474P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAG...135..474P"><span>On the <span class="hlt">pore</span> <span class="hlt">water</span> chemistry effect on spectral induced polarization measurements in the presence of pyrite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Placencia-Gómez, Edmundo; Slater, Lee D.</p> <p>2016-12-01</p> <p>In order to expand the application of the induced polarization (IP) method as a technique for monitoring metallic mineral dissolution and precipitation mechanisms, we studied the effects of variations in <span class="hlt">pore</span> <span class="hlt">water</span> chemistry on the spectral induced polarization (SIP) response of a mixture of silica-sand and pyrite particles in the laboratory. We investigated the dependence of the SIP response on both <span class="hlt">pore</span> <span class="hlt">water</span> conductivity and pH for various chemical compositions: redox-passive (P) versus redox-active (A) ions, using CaCl2 as P-ions, and FeSO4 and FeCl3 as A-ion brines. The effect of <span class="hlt">pore</span> <span class="hlt">water</span> chemistry was evaluated by means of a recently proposed volumetric specific capacitance model. The SIP response (IP-effect) was primarily determined by the <span class="hlt">pore</span> <span class="hlt">water</span> conductivity and the specific capacitance was only weakly dependent on the chemical composition and pHw. We found that the specific capacitance varies to first order over a limited range and approximates a single value (≈ 302 F m- 3 in average). However, variations in the specific capacitance as a function of active versus inactive ion chemistry might be important to consider when using IP to monitor specific mineral dissolution and precipitation processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21570165','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21570165"><span>Field sampling of soil <span class="hlt">pore</span> <span class="hlt">water</span> to evaluate trace element mobility and associated environmental risk.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Moreno-Jiménez, Eduardo; Beesley, Luke; Lepp, Nicholas W; Dickinson, Nicholas M; Hartley, William; Clemente, Rafael</p> <p>2011-10-01</p> <p>Monitoring soil pollution is a key aspect in sustainable management of contaminated land but there is often debate over what should be monitored to assess ecological risk. Soil <span class="hlt">pore</span> <span class="hlt">water</span>, containing the most labile pollutant fraction in soils, can be easily collected in situ offering a routine way to monitor this risk. We present a compilation of data on concentration of trace elements (As, Cd, Cu, Pb, and Zn) in soil <span class="hlt">pore</span> <span class="hlt">water</span> collected in field conditions from a range of polluted and non-polluted soils in Spain and the UK during single and repeated monitoring, and propose a simple eco-toxicity test using this media. Sufficient <span class="hlt">pore</span> <span class="hlt">water</span> could be extracted for analysis both under semi-arid and temperate conditions, and eco-toxicity comparisons could be effectively made between polluted and non-polluted soils. We propose that in-situ <span class="hlt">pore</span> <span class="hlt">water</span> extraction could enhance the realism of risk assessment at some contaminated sites. Copyright © 2011 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27494311','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27494311"><span>Influence of silver nanoparticles on heavy metals of <span class="hlt">pore</span> <span class="hlt">water</span> in contaminated river sediments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tao, Wei; Chen, Guiqiu; Zeng, Guangming; Yan, Ming; Chen, Anwei; Guo, Zhi; Huang, Zhenzhen; He, Kai; Hu, Liang; Wang, Lichao</p> <p>2016-11-01</p> <p>Despite the increasing knowledge on the discharge of silver nanoparticles (AgNPs) into the environment and their potential toxicity to microorganisms, the interaction of AgNPs with heavy metals remains poorly understood. This study focused on the effect of AgNPs on heavy metal concentration and form in sediment contaminated with heavy metals from the Xiangjiang River. The results showed that the concentration of Cu, Zn, Pb and Cd decreased and then increased with a change in form. The changes in form and concentrations of heavy metals in <span class="hlt">pore</span> <span class="hlt">water</span> suggested that Cu and Zn were more likely to be affected compared to Pb and Cd. The concentrations of Hg in sediment <span class="hlt">pore</span> <span class="hlt">water</span> in three AgNPs-dosed containers, increased greatly until they reached their peaks at 4.468 ± 0.133, 4.589 ± 0.235, and 5.083 ± 0.084 μg L(-1) in Bare AgNPs, Citrate AgNPs and Tween 80 AgNPs, respectively. The measurements of Hg concentrations in the sediment <span class="hlt">pore</span> <span class="hlt">water</span>, combined with SEM and EDX analysis, demonstrated that added AgNPs stabilized in <span class="hlt">pore</span> <span class="hlt">water</span> and formed an amalgam with Hg(0), which can affect Hg transportation over long distance. Copyright © 2016 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=289056','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=289056"><span><span class="hlt">Pore-water</span> pressures associated with clogging of soil pipes: Numerical analysis of laboratory experiments</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Clogging of soil pipes due to excessive internal erosion has been hypothesized to cause extreme erosion events such as landslides, debris flows, and gullies, but confirmation of this phenomenon has been lacking. Laboratory and field measurements have failed to measure <span class="hlt">pore</span> <span class="hlt">water</span> pressures within pip...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26969061','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26969061"><span>Estimating the combined toxicity of flufenacet and imazaquin to sorghum with <span class="hlt">pore</span> <span class="hlt">water</span> herbicide concentration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Donghong; Zhang, Qian; Zheng, Yuan; Lin, Dunli; Yu, Yunlong</p> <p>2016-03-01</p> <p>Combined toxicity of herbicides to non-target crops is usually resulted from their successive application. The present study was conducted to assess the combined toxicity of flufenacet (FLU) and imazaquin (IMA) to sorghum with their concentration in soil <span class="hlt">pore</span> <span class="hlt">water</span>. The concentrations that inhibited growth by 50% (IC50) of FLU and IMA individually and their combination estimated from the herbicide concentrations in soil <span class="hlt">pore</span> <span class="hlt">water</span> notably differed from those based on the amended concentrations, due to the decline in bioavailability resulting from adsorption of the herbicides onto soil. According to the amended concentrations, the combined effect of FLU and IMA in soil on sorghum growth was identified as additive action. Based on the concentration in soil <span class="hlt">pore</span> <span class="hlt">water</span>, however, it was determined to be antagonism, which was identical to that observed in a test using culture solution. The results revealed that <span class="hlt">pore</span> <span class="hlt">water</span> herbicide concentration might be an effective tool to assess the combined toxicity of herbicides in soil to rotational crops. Copyright © 2015. Published by Elsevier B.V.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18302968','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18302968"><span>Mobility of trace metals in <span class="hlt">pore</span> <span class="hlt">waters</span> of two Central European peat bogs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Novak, Martin; Pacherova, Petra</p> <p>2008-05-15</p> <p>Vertical peat profiles can only be used as archives of past changes in pollution levels if atmogenic elements are immobile after their burial. For mobile elements, similar <span class="hlt">pore-water</span> concentrations can be expected at different peat depths. Concentrations of Pb, Cu, Zn, Cr, Mn, Fe, Co and Cd were determined in surface bog <span class="hlt">water</span> and bog <span class="hlt">pore</span> <span class="hlt">water</span> 40 cm below surface in two Sphagnum-dominated peat bogs in the Czech Republic. Velke jerabi jezero (VJJ) is an upland bog located in an industrial area, Cervene blato (CB) is a lowland bog located in a rural area. Metal concentrations were monitored seasonally over 3 years (2002--2005) at both sites. Higher concentrations of Pb, Cu, Zn, Cr and Cd and lower concentrations of Mn, Fe and Co were found at the less polluted CB compared to VJJ. No clear-cut seasonality was observed in metal concentrations in bog <span class="hlt">waters</span>, despite seasonal differences in industrial emission rates of pollutants (more coal burning in winter than in summer). This contrasts with an earlier observation of distinct seasonality in sulfate concentration and isotope composition in these stagnating bog <span class="hlt">waters</span>. Peat substrate 40 cm below current bog surface represented pre-industrial low-pollution environment, yet <span class="hlt">pore</span> <span class="hlt">waters</span> at such depths contained the same metal concentrations as surface <span class="hlt">waters</span>. The only exception was Pb, whose concentration in <span class="hlt">water</span> solutes increased with increasing depth. Lack of vertical stratification in <span class="hlt">pore-water</span> contents of Cu, Zn, Cr, Mn, Fe and Co indicated vertical mobility of these metals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014WRR....50.4760J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014WRR....50.4760J"><span>Hydrology and <span class="hlt">pore</span> <span class="hlt">water</span> chemistry in a permafrost wetland, Ilulissat, Greenland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jessen, Søren; Holmslykke, Hanne D.; Rasmussen, Kristine; Richardt, Niels; Holm, Peter E.</p> <p>2014-06-01</p> <p>Hydrological and geochemical processes controlling the <span class="hlt">pore</span> <span class="hlt">water</span> chemistry in a permafrost wetland, with loam overlain by sphagnum peat, were investigated. The vertical distributions of dissolved Cl, and of <span class="hlt">pore</span> <span class="hlt">water</span> δ18O, appeared unrelated to ion freeze-out and isotope ice-<span class="hlt">water</span> fractionation processes, respectively, dismissing solute freeze-out as a main control on the <span class="hlt">water</span> chemistry. However, concentrations of major ions, others than Cl, generally increased with depth into the active layer. A conceptual model for <span class="hlt">water</span> and solute movement in the active layer was derived. The model indicates upward diffusive transport of elements, released in the loam layer by mineral weathering, to the peat layer, in which lateral advective transport dominates. Active layer <span class="hlt">pore</span> <span class="hlt">water</span> and <span class="hlt">water</span> of melted core sections of permafrost were of Ca-Mg-HCO3 type (1:1:4 stoichiometry) and were subsaturated for calcite and dolomite. The results are consistent with an annual cycling of inorganic carbon species, Ca and Mg, via cryogenic carbonate precipitation during fall freeze-up and their redissolution following spring thaw. Similarly, elevated Fe2+ concentrations appear to be related to cryogenic siderite formation. <span class="hlt">Pore</span> <span class="hlt">water</span> in the active layer showed high partial pressures of CO2, indicating the feasibility of bubble ebullition as a greenhouse gas emission pathway from permafrost wetlands. Elevated concentrations of geogenic trace elements (Ni, Al, and As) were observed, and the controlling geochemical processes are discussed. The conceptual model for <span class="hlt">water</span> and solute movement was applied to quantify the contribution of released trace elements to a downstream lake in the permafrost catchment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1185491-water-desalination-using-nanoporous-single-layer-graphene-tunable-pore-size','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1185491-water-desalination-using-nanoporous-single-layer-graphene-tunable-pore-size"><span><span class="hlt">Water</span> Desalination Using Nanoporous Single-Layer Graphene with Tunable <span class="hlt">Pore</span> Size</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Surwade, Sumedh P.; Smirnov, Sergei N.; Vlassiouk, Ivan V.; ...</p> <p>2015-03-23</p> <p>Graphene has great potential to serve as a separation membrane due to its unique properties such as chemical and mechanical stability, flexibility and most importantly its one-atom thickness. In this study, we demonstrate first experimental evidence of the use of single-layer porous graphene as a desalination membrane. Nanometer-sized <span class="hlt">pores</span> are introduced into single layer graphene using a convenient oxygen plasma etching process that permits tuning of the <span class="hlt">pore</span> size. The resulting porous graphene membrane exhibited high rejection of salt ions and rapid <span class="hlt">water</span> transport, thus functioning as an efficient <span class="hlt">water</span> desalination membrane. Salt rejection selectivity of nearly 100% and exceptionallymore » high <span class="hlt">water</span> fluxes exceeding 105 g m-2 s-1 at 40 C were measured using saturated <span class="hlt">water</span> vapor as a driving force.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1185491','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1185491"><span><span class="hlt">Water</span> Desalination Using Nanoporous Single-Layer Graphene with Tunable <span class="hlt">Pore</span> Size</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Surwade, Sumedh P.; Smirnov, Sergei N.; Vlassiouk, Ivan V.; Unocic, Raymond R.; Veith, Gabriel M.; Dai, Sheng; Mahurin, Shannon Mark</p> <p>2015-03-23</p> <p>Graphene has great potential to serve as a separation membrane due to its unique properties such as chemical and mechanical stability, flexibility and most importantly its one-atom thickness. In this study, we demonstrate first experimental evidence of the use of single-layer porous graphene as a desalination membrane. Nanometer-sized <span class="hlt">pores</span> are introduced into single layer graphene using a convenient oxygen plasma etching process that permits tuning of the <span class="hlt">pore</span> size. The resulting porous graphene membrane exhibited high rejection of salt ions and rapid <span class="hlt">water</span> transport, thus functioning as an efficient <span class="hlt">water</span> desalination membrane. Salt rejection selectivity of nearly 100% and exceptionally high <span class="hlt">water</span> fluxes exceeding 105 g m-2 s-1 at 40 C were measured using saturated <span class="hlt">water</span> vapor as a driving force.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3887386','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3887386"><span>Paradoxical One-ion <span class="hlt">Pore</span> Behavior of the Long β-Helical Peptide of <span class="hlt">Marine</span> Cytotoxic Polytheonamide B</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Iwamoto, Masayuki; Matsunaga, Shigeki; Oiki, Shigetoshi</p> <p>2014-01-01</p> <p>The cytotoxic 48-mer peptide, polytheonamide B (pTB), from a <span class="hlt">marine</span> sponge forms a β6.3-helix with an inner diameter of 4 Å and a length of 45 Å, features that allow the selective permeation of monovalent cations across targeted cell membranes. To characterize this long, narrow <span class="hlt">pore</span>, electrophysiological examination using a planar lipid bilayer method was performed. The single-channel current amplitude exhibited saturation for concentrated Cs+ or K+ solution, and the reversal potential in mixed solutions did not exhibit any anomalous mole-fraction behavior. These results suggest the one-ion permeation mechanism. This is in contrast to the short (26 Å) β6.3-helical gramicidin channel, which holds two ions simultaneously. The paradoxical one-ion permeation through the long pTB channel was modeled with a discrete-state Markov model. Ions permeate through the channel by stepping between two binding sites in the <span class="hlt">pore</span>, but never occupy these sites simultaneously in either pure or mixed ion solution. PMID:24407373</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ECSS...62..233K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ECSS...62..233K"><span>Salt marsh <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry does not correlate with microbial community structure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koretsky, Carla M.; Van Cappellen, Philippe; DiChristina, Thomas J.; Kostka, Joel E.; Lowe, Kristi L.; Moore, Charles M.; Roychoudhury, Alakendra N.; Viollier, Eric</p> <p>2005-01-01</p> <p>Spatial and temporal trends in <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry and sediment microbial community structure are compared at three intertidal sites of a saltmarsh on Sapelo Island, GA. The sites include a heavily bioturbated, unvegetated creek bank, a levee with dense growth of Spartina alterniflora, and a more sparsely vegetated ponded marsh site. The redox chemistry of the <span class="hlt">pore</span> <span class="hlt">waters</span> ranges from sulfide-dominated at the ponded marsh site to suboxic at the creek bank site. At the three sites, the vertical redox stratification of the <span class="hlt">pore</span> <span class="hlt">waters</span> is more compressed in summer than in winter. The trends in redox chemistry reflect opposing effects of sediment respiration and <span class="hlt">pore</span> <span class="hlt">water</span> irrigation. Intense and deep burrowing activity by fiddler crabs at the creek bank site results in the efficient oxidation of reduced byproducts of microbial metabolism and, hence, the persistence of suboxic conditions to depths of 50 cm below the sediment surface. Increased supply of labile organic substrates at the vegetated sites promotes microbial degradation processes, leading to sharper redox gradients. At the levee site, this is partly offset by the higher density and deeper penetration of roots and macrofaunal burrows. Surprisingly, the microbial community structure shows little correlation with the variable vertical redox zonation of the <span class="hlt">pore</span> <span class="hlt">waters</span> across the saltmarsh. At the three sites, the highest population densities of aerobic microorganisms, iron- plus manganese-reducing bacteria, and sulfate reducers coexist within the upper 10 cm of sediment. The absence of a clear vertical separation of these microorganisms is ascribed to the high supply of labile organic matter and intense mixing of the topmost sediment via bioturbation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008ECSS...79...51G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008ECSS...79...51G"><span>A method for estimating <span class="hlt">pore</span> <span class="hlt">water</span> drainage from marsh soils using rainfall and well records</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gardner, Leonard Robert; Gaines, Emily F.</p> <p>2008-08-01</p> <p>Rainfall events during low tide exposure cause the <span class="hlt">water</span> table in marshes to rise. If one has long time series of both rain events and <span class="hlt">water</span> levels in wells along transects from creek bank to marsh interior, one can correlate well response with rain amount. In cases examined so far the well response is found to be a linear function of rain amount. As it is reasonable to assume that the amount of tidal infiltration required to restore the <span class="hlt">water</span> table to the elevation of the marsh surface is equal to the amount of rain that would be required to do so, one can estimate the annual drainage of <span class="hlt">pore</span> <span class="hlt">water</span> from a well site by dividing the mean drawdown of the <span class="hlt">water</span> table at low tide by the slope of the response versus rain regression and then multiplying the result by the number of tidal drawdowns in a year. Integration of such results along the transect then gives an estimate of the total annual drainage. An example of the use of this method is given for two well transects in a Typha and a Spartina marsh at the Plum Island Estuary Long Term Ecological Research (PIE-LTER) site in Massachusetts, USA. Both transects yielded <span class="hlt">pore</span> <span class="hlt">water</span> drainage rates of about 160 m 3 year -1 per meter of channel length. Although the annual volume of <span class="hlt">pore</span> <span class="hlt">water</span> drainage is small compared to the annual volume of the tidal prism, its impact on nutrient budgets in the estuary could be large because of the high concentrations of nutrients in marsh <span class="hlt">pore</span> <span class="hlt">waters</span>. We also discuss the possible effects of the capillary fringe, air entrapment and tidal forcing during rain events on these results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27267040','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27267040"><span>Wettability and spontaneous penetration of a <span class="hlt">water</span> drop into hydrophobic <span class="hlt">pores</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Choi, Hyunho; Liang, Hong</p> <p>2016-09-01</p> <p>The penetration of a <span class="hlt">water</span> drop into hydrophobic <span class="hlt">pores</span> reflects its instability on a porous surface. To understand the mechanism of penetration and to predict the behavior of such a drop, an investigation was conducted through experimental study combined theoretical analysis. <span class="hlt">Water</span> drops with volumes from 0.5 to 15μL were examined on Polydimethylsiloxane (PDMS) substrates containing <span class="hlt">pores</span> of 800μm and less in diameter. Results showed a critical condition at which a drop starts to penetrate into a certain sized <span class="hlt">pore</span>. The critical condition presents a parabolic relationship between the volume of a <span class="hlt">water</span> drop and the size of a hydrophobic <span class="hlt">pore</span>. This behavior was due to a net force resulting from Laplace pressure, and capillary pressure. This force was found to be affected by the porosity, wetting angle, and there after the critical condition. The finding of this research will be beneficial for future design of structured surfaces. Copyright © 2016 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JHyd..538..152Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JHyd..538..152Z"><span>A Lattice Boltzmann model for simulating <span class="hlt">water</span> flow at <span class="hlt">pore</span> scale in unsaturated soils</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Xiaoxian; Crawford, John W.; Young, Iain M.</p> <p>2016-07-01</p> <p>The Lattice Boltzmann (LB) method is an established prominent model for simulating <span class="hlt">water</span> flow at <span class="hlt">pore</span> scale in saturated porous media. However, its application in unsaturated soil is less satisfactory because of the difficulties associated with most two-phase LB models in simulating immiscible fluids, such as <span class="hlt">water</span> and air, which have contrasting densities and viscosities. While progress has been made in developing LB models for fluids with high density ratio, they are still prone to numerical instability and cannot accurately describe the interfacial friction on <span class="hlt">water</span>-air interface in unsaturated media. Considering that one important application of the LB model in porous materials is to calculate their hydraulic properties when flow is at steady state, we develop a simple LB model to simulate steady <span class="hlt">water</span> flow at <span class="hlt">pore</span> scale in unsaturated soils. The method consists of two steps. The first one is to determine <span class="hlt">water</span> distribution within the soil structure using a morphological model; once the <span class="hlt">water</span> distribution is known, its interfaces with air are fixed. The second step is to use a single-phase LB model to simulate <span class="hlt">water</span> flow by treating the <span class="hlt">water</span>-air interfaces as free-flow boundaries where the shear resistance of air to <span class="hlt">water</span> flow is assumed to be negligible. We propose a method to solve such free-flow boundaries, and validate the model against analytical solutions of flows of <span class="hlt">water</span> film over non-slip walls in both two and three dimensions. We then apply the model to calculate <span class="hlt">water</span> retention and hydraulic properties of a medium acquired using X-ray computed tomography at resolution of 6 μm. The model is quasi-static, similar to the porous network model, but is an improvement as it directly simulates <span class="hlt">water</span> flow in the <span class="hlt">pore</span> geometries acquired by tomography without making any further simplifications.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1163812','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1163812"><span><span class="hlt">Pore-Water</span> Extraction from Unsaturated Porous Media: Intermediate-Scale Laboratory</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Oostrom, Martinus; Truex, Michael J.; Wietsma, Thomas W.; Tartakovsky, Guzel D.</p> <p>2014-08-15</p> <p>As a remedial approach, vacuum-induced <span class="hlt">pore-water</span> extraction offers the possibility of contaminant and <span class="hlt">water</span> removal from the vadose zone, which may be beneficial in reducing the flux of vadose zone contaminants to groundwater. Vadose zone <span class="hlt">water</span> extraction is being considered at the Hanford Site in Washington State as a means to remove technetium-99 contamination from low permeability sediments with relatively high <span class="hlt">water</span> contents. A series of intermediate-scale laboratory experiments have been conducted to improve the fundamental understanding and limitations of the technique. Column experiments were designed to investigate the relations between imposed suctions, <span class="hlt">water</span> saturations, and <span class="hlt">water</span> production. Flow cell experiments were conducted to investigate the effects of high-permeability layers and near-well compaction on <span class="hlt">pore-water</span> extraction efficiency. Results show that <span class="hlt">water</span> extraction from unsaturated systems can be achieved in low permeability sediments, provided that the initial <span class="hlt">water</span> saturations are relatively high. The presence of a high-permeability layer decreased the yield, and compaction near the well screen had a limited effect on overall performance. In all experiments, large pressure gradients were observed near the extraction screen. Minimum requirements for <span class="hlt">water</span> extraction include an imposed vacuum-induced suction larger than the initial sediment capillary pressure, in combination with a fully saturated seepage-face boundary. A numerical multiphase simulator with a coupled seepage-face boundary conditions was used to simulate the experiments. Reasonable matches were obtained between measured and simulated results for both <span class="hlt">water</span> extraction and capillary pressures, suggesting that numerical simulations may be used as a design tool for field-scale applications of <span class="hlt">pore-water</span> extraction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014HESSD..1111203S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014HESSD..1111203S"><span>Estimating flow and transport parameters in the unsaturated zone with <span class="hlt">pore</span> <span class="hlt">water</span> stable isotopes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sprenger, M.; Volkmann, T. H. M.; Blume, T.; Weiler, M.</p> <p>2014-10-01</p> <p>Determining the soil hydraulic properties is a prerequisite to physically model transient <span class="hlt">water</span> flow and solute transport in the vadose zone. Estimating these properties by inverse modelling techniques has become more common within the last two decades. While these inverse approaches usually fit simulations to hydrometric data, we expanded the methodology by using independent information about the stable isotope composition of the soil <span class="hlt">pore</span> <span class="hlt">water</span> depth profile as a single or additional optimization target. To demonstrate the potential and limits of this approach, we compared the results of three inverse modelling strategies where the fitting targets were (a) <span class="hlt">pore</span> <span class="hlt">water</span> isotope concentrations, (b) a combination of <span class="hlt">pore</span> <span class="hlt">water</span> isotope concentrations and soil moisture time series, and (c) a two-step approach using first soil moisture data to determine <span class="hlt">water</span> flow parameters and then the <span class="hlt">pore</span> <span class="hlt">water</span> stable isotope concentrations to estimate the solute transport parameters. The analyses were conducted at three study sites with different soil properties and vegetation. The transient unsaturated <span class="hlt">water</span> flow was simulated by numerically solving the Richards equation with the finite-element code of Hydrus-1D. The transport of deuterium was simulated with the advection-dispersion equation, and the Hydrus code was modified to allow for deuterium loss during evaporation. The Mualem-van Genuchten and the longitudinal dispersivity parameters were determined for two major soil horizons at each site. The results show that approach (a) using only the <span class="hlt">pore</span> <span class="hlt">water</span> isotope content cannot substitute hydrometric information to derive parameter sets that reflect the observed soil moisture dynamics, but gives comparable results when the parameter space is constrained by pedotransfer functions. Approaches (b) and (c) using both, the isotope profiles and the soil moisture time series resulted in satisfying model performances and good parameter identifiability. However, approach (b) has the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/671925','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/671925"><span>Isotopic data of <span class="hlt">pore</span> <span class="hlt">water</span> extracted from unsaturated-zone cores at Yucca Mountain, Nevada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yang, I.C.</p> <p>1997-12-01</p> <p>Isotopic compositions of unsaturated-zone (UZ) ground <span class="hlt">water</span> ({delta}{sup 18}O, {delta}D, {delta}{sup 13}C and {sup 14}C) at Yucca Mountain, Nevada, the site of a potential permanent national nuclear waste repository, can be used to infer the origins of <span class="hlt">water</span>, residence times of the <span class="hlt">water</span>, <span class="hlt">water</span> flux, climatic and evaporative history of <span class="hlt">water</span>, flow paths and velocities. These data can also be used as indicators of transport properties or <span class="hlt">water</span>-rock interaction. The lack of long-term direct measurements of infiltration requires proxy indicators of <span class="hlt">water</span> movement through the unsaturated zone to extend the record into the past. This report will discuss {delta}D and {delta}{sup 18}O data obtained from <span class="hlt">pore</span> <span class="hlt">water</span>, along with the {delta}{sup 13}C and {sup 14}C data of gas and <span class="hlt">water</span> obtained from four boreholes dry-drilled through all UZ lithologic units to infer the existence of nonvertical flowpaths through the mountain and residence times of <span class="hlt">pore</span> <span class="hlt">water</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15836350','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15836350"><span>Thermodynamic functions of <span class="hlt">water</span> and ice confined to 2 nm radius <span class="hlt">pores</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tombari, E; Salvetti, G; Ferrari, C; Johari, G P</p> <p>2005-03-08</p> <p>The heat capacity C(p) of the liquid state of <span class="hlt">water</span> confined to 2 nm radius <span class="hlt">pores</span> in Vycor glass was measured by temperature modulation calorimetry in the temperature range of 253-360 K, with an accuracy of 0.5%. On nanoconfinement, C(p) of <span class="hlt">water</span> increases, and the broad minimum in the C(p) against T plot shifts to higher temperature. The increase in the C(p) of <span class="hlt">water</span> is attributed to an increase in the phonon and configurational contributions. The apparent heat capacity of the liquid and partially frozen state of confined <span class="hlt">water</span> was measured by temperature scanning calorimetry in the range of 240-280 K with an accuracy of 2%, both on cooling or heating at 6 K h(-1) rate. The enthalpy, entropy, and free energy of nanoconfined liquid <span class="hlt">water</span> have been determined. The apparent heat capacity remains higher than that of bulk ice at 240 K and it is concluded that freezing is incomplete at 240 K. This is attributed to the intergranular-<span class="hlt">water</span>-ice equilibrium in the <span class="hlt">pores</span>. The nanoconfined sample melts over a 240-268 K range. For 9.6 wt % nanoconfined <span class="hlt">water</span> concentration ( approximately 50% of the maximum filling) at 280 K, the enthalpy of <span class="hlt">water</span> is 81.6% of the bulk <span class="hlt">water</span> value and the entropy is 88.5%. For 21.1 wt % (100% filling) the corresponding values are 90.7% and 95.0%. The enthalpy decrease on nanoconfinement is a reflection of the change in the H-bonded structure of <span class="hlt">water</span>. The use of the Gibbs-Thomson equation for analyzing the data has been discussed and it is found that a distribution of <span class="hlt">pore</span> size does not entirely explain our results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3108135','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3108135"><span>Temporal and Spatial <span class="hlt">Pore</span> <span class="hlt">Water</span> Pressure Distribution Surrounding a Vertical Landfill Leachate Recirculation Well</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kadambala, Ravi; Townsend, Timothy G.; Jain, Pradeep; Singh, Karamjit</p> <p>2011-01-01</p> <p>Addition of liquids into landfilled waste can result in an increase in <span class="hlt">pore</span> <span class="hlt">water</span> pressure, and this in turn may increase concerns with respect to geotechnical stability of the landfilled waste mass. While the impact of vertical well leachate recirculation on landfill <span class="hlt">pore</span> <span class="hlt">water</span> pressures has been mathematically modeled, measurements of these systems in operating landfills have not been reported. Pressure readings from vibrating wire piezometers placed in the waste surrounding a liquids addition well at a full-scale operating landfill in Florida were recorded over a 2-year period. Prior to the addition of liquids, measured <span class="hlt">pore</span> pressures were found to increase with landfill depth, an indication of gas pressure increase and decreasing waste permeability with depth. When liquid addition commenced, piezometers located closer to either the leachate injection well or the landfill surface responded more rapidly to leachate addition relative to those far from the well and those at deeper locations. After liquid addition stopped, measured <span class="hlt">pore</span> pressures did not immediately drop, but slowly decreased with time. Despite the large pressures present at the bottom of the liquid addition well, much smaller pressures were measured in the surrounding waste. The spatial variation of the pressures recorded in this study suggests that waste permeability is anisotropic and decreases with depth. PMID:21655145</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21655145','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21655145"><span>Temporal and spatial <span class="hlt">pore</span> <span class="hlt">water</span> pressure distribution surrounding a vertical landfill leachate recirculation well.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kadambala, Ravi; Townsend, Timothy G; Jain, Pradeep; Singh, Karamjit</p> <p>2011-05-01</p> <p>Addition of liquids into landfilled waste can result in an increase in <span class="hlt">pore</span> <span class="hlt">water</span> pressure, and this in turn may increase concerns with respect to geotechnical stability of the landfilled waste mass. While the impact of vertical well leachate recirculation on landfill <span class="hlt">pore</span> <span class="hlt">water</span> pressures has been mathematically modeled, measurements of these systems in operating landfills have not been reported. Pressure readings from vibrating wire piezometers placed in the waste surrounding a liquids addition well at a full-scale operating landfill in Florida were recorded over a 2-year period. Prior to the addition of liquids, measured <span class="hlt">pore</span> pressures were found to increase with landfill depth, an indication of gas pressure increase and decreasing waste permeability with depth. When liquid addition commenced, piezometers located closer to either the leachate injection well or the landfill surface responded more rapidly to leachate addition relative to those far from the well and those at deeper locations. After liquid addition stopped, measured <span class="hlt">pore</span> pressures did not immediately drop, but slowly decreased with time. Despite the large pressures present at the bottom of the liquid addition well, much smaller pressures were measured in the surrounding waste. The spatial variation of the pressures recorded in this study suggests that waste permeability is anisotropic and decreases with depth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EPJWC...614003L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EPJWC...614003L"><span>Change of microstructure of clays due to the presence of heavy metal ions in <span class="hlt">pore</span> <span class="hlt">water</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, X.; Saiyouri, N.; Hicher, P. Y.</p> <p>2010-06-01</p> <p>The compressibility of engineered barrier clays is, to a large extent, controlled by microstructure change due to the presence of chemical ions in clay-<span class="hlt">water</span> system. This paper aims to investigate the change of microstructure of clays due to the presence of heavy metal ions in <span class="hlt">pore</span> <span class="hlt">water</span>. We use two pure clays (kaolinite and bentonite) in the study. One-dimensional consolidation tests were performed on reconstituted samples, which are prepared with distilled <span class="hlt">water</span> and three types of heavy metal solutions (Pb(NO3)2, Cu(NO3)2, Zn(NO3)2,). In order to better understand the impact of chemical <span class="hlt">pore</span> fluid on microstructure of the two clays, following the consolidation test, scanning electron microscope (SEM) observations and mercury intrusion <span class="hlt">pore</span> size distribution measurements (MIP) were conducted. Due to the measurement range of MIP, which is only allowed to measure the minimal <span class="hlt">pore</span> size 20 Å, BET method by gas sorption, whose measurement <span class="hlt">pore</span> size range is from 3.5 Å to 500 Å, is used to measure the micropore size distribution. By this method, specific surface area of the soils can be also determined. It can be employed to demonstrate the difference of creep performance between the soils. Furthermore, a series of batch equilibrium tests were conducted to better understand the physical-chemical interactions between the particles of soils and the heavy metal ions. With the further consideration of the interparticle electrical attractive and repulsive force, an attempt has been made to predict the creep behaviour by using the modified Gouy-Chapman double layer theory. The results of calculation were compared with that of tests. The comparison shows that the prediction of compressibility of the clays according to the modified double diffuse layer theory can be reasonably agreement with the experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26270848','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26270848"><span>Penetration Barrier of <span class="hlt">Water</span> through Graphynes' <span class="hlt">Pores</span>: First-Principles Predictions and Force Field Optimization.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bartolomei, Massimiliano; Carmona-Novillo, Estela; Hernández, Marta I; Campos-Martínez, José; Pirani, Fernando; Giorgi, Giacomo; Yamashita, Koichi</p> <p>2014-02-20</p> <p>Graphynes are novel two-dimensional carbon-based materials that have been proposed as molecular filters, especially for <span class="hlt">water</span> purification technologies. We carry out first-principles electronic structure calculations at the MP2C level of theory to assess the interaction between <span class="hlt">water</span> and graphyne, graphdiyne, and graphtriyne <span class="hlt">pores</span>. The computed penetration barriers suggest that <span class="hlt">water</span> transport is unfeasible through graphyne while being unimpeded for graphtriyne. For graphdiyne, with a <span class="hlt">pore</span> size almost matching that of <span class="hlt">water</span>, a low barrier is found that in turn disappears if an active hydrogen bond with an additional <span class="hlt">water</span> molecule on the opposite side of the opening is considered. Thus, in contrast with previous determinations, our results do not exclude graphdiyne as a promising membrane for <span class="hlt">water</span> filtration. In fact, present calculations lead to <span class="hlt">water</span> permeation probabilities that are 2 orders of magnitude larger than estimations based on common force fields. A new pair potential for the <span class="hlt">water</span>-carbon noncovalent component of the interaction is proposed for molecular dynamics simulations involving graphdiyne and <span class="hlt">water</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23542673','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23542673"><span>Small-scale variability in peatland <span class="hlt">pore-water</span> biogeochemistry, Hudson Bay Lowland, Canada.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ulanowski, T A; Branfireun, B A</p> <p>2013-06-01</p> <p>The Hudson Bay Lowland (HBL) of northern Ontario, Manitoba and Quebec, Canada is the second largest contiguous peatland complex in the world, currently containing more than half of Canada's soil carbon. Recent concerns about the ecohydrological impacts to these large northern peatlands resulting from climate change and resource extraction have catalyzed a resurgence in scientific research into this ecologically important region. However, the sheer size, heterogeneity and elaborate landscape arrangements of this ecosystem raise important questions concerning representative sampling of environmental media for chemical or physical characterization. To begin to quantify such variability, this study assessed the small-scale spatial (1m) and short temporal (21 day) variability of surface <span class="hlt">pore-water</span> biogeochemistry (pH, dissolved organic carbon, and major ions) in a Sphagnum spp.-dominated, ombrotrophic raised bog, and a Carex spp.-dominated intermediate fen in the HBL. In general, <span class="hlt">pore-water</span> pH and concentrations of dissolved solutes were similar to previously reported literature values from this region. However, systematic sampling revealed consistent statistically significant differences in <span class="hlt">pore-water</span> chemistries between the bog and fen peatland types, and large within-site spatiotemporal variability. We found that microtopography in the bog was associated with consistent differences in most biogeochemical variables. Temporal changes in dissolved solute chemistry, particularly base cations (Na(+), Ca(2+) and Mg(2+)), were statistically significant in the intermediate fen, likely a result of a dynamic connection between surficial <span class="hlt">waters</span> and mineral-rich deep groundwater. In both the bog and fen, concentrations of SO4(2-) showed considerable spatial variability, and a significant decrease in concentrations over the study period. The observed variability in peatland <span class="hlt">pore-water</span> biogeochemistry over such small spatial and temporal scales suggests that under-sampling in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19551886','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19551886"><span>Chloride ion conduction without <span class="hlt">water</span> coordination in the <span class="hlt">pore</span> of ClC protein.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ko, Youn Jo; Jo, Won Ho</p> <p>2010-02-01</p> <p>In the present work, we have found by an atomistic molecular dynamics simulation that hydrogen atoms originating from the residues of a prokaryotic ClC protein (EcClC) stabilize the chloride ion without <span class="hlt">water</span> molecules in the <span class="hlt">pore</span> of ClC protein. When the chloride ion conduction is simulated by pulling a chloride ion along the <span class="hlt">pore</span> axis, the free energy barrier for chloride ion conduction is calculated to be low (4 kcal/mol), although the chloride ion is stripped of its hydration shell as it passes through the dehydrated <span class="hlt">pore</span> region. The calculation of the number of hydrogen atoms surrounding the chloride ion reveals that <span class="hlt">water</span> molecules hydrating the chloride ion are replaced by polar and non-polar hydrogen atoms protruding from the protein residues. From the analysis of the pair interaction energy between the chloride ion and these hydrogen atoms, it is realized that the hydrogen atoms from the protein residues stabilize the chloride ion at the dehydrated region instead of <span class="hlt">water</span> molecules, by which the energetic penalty for detaching <span class="hlt">water</span> molecules from the permeating ion is compensated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15014099','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15014099"><span>Evaporative Evolution of Carbonate-Rich Brines from Synthetic Topopah Spring Tuff <span class="hlt">Pore</span> <span class="hlt">Water</span>, Yucca Mountain</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sutton, M; Alai, M; Carroll, S A</p> <p>2004-04-14</p> <p>The evaporation of a range of synthetic <span class="hlt">pore</span> <span class="hlt">water</span> solutions representative of the potential high-level-nuclear-waste repository at Yucca Mountain, NV is being investigated. The motivation of this work is to understand and predict the range of brine compositions that may contact the waste containers from evaporation of <span class="hlt">pore</span> <span class="hlt">waters</span>, because these brines could form corrosive thin films on the containers and impact their long-term integrity. A relatively complex synthetic Topopah Spring Tuff <span class="hlt">pore</span> <span class="hlt">water</span> was progressively concentrated by evaporation in a closed vessel, heated to 95 C in a series of sequential experiments. Periodic samples of the evaporating solution were taken to determine the evolving <span class="hlt">water</span> chemistry. According to chemical divide theory at 25 C and 95 C our starting solution should evolve towards a high pH carbonate brine. Results at 95 C show that this solution evolves towards a complex brine that contains about 99 mol% Na{sup +} for the cations, and 71 mol% Cl{sup -}, 18 mol% {Sigma}CO{sub 2}(aq), 9 mol%SO{sub 4}{sup 2-} for the anions. Initial modeling of the evaporating solution indicates precipitation of aragonite, halite, silica, sulfate and fluoride phases. The experiments have been used to benchmark the use of the EQ3/6 geochemical code in predicting the evolution of carbonate-rich brines during evaporation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70022821','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70022821"><span>Estimating methane production rates in bogs and landfills by deuterium enrichment of <span class="hlt">pore</span> <span class="hlt">water</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Siegel, D.I.; Chanton, J.P.; Glaser, P.H.; Chasar, L.S.; Rosenberry, D.O.</p> <p>2001-01-01</p> <p>Raised bogs and municipal waste landfills harbor large populations of methanogens within their domed deposits of anoxic organic matter. Although the methane emissions from these sites have been estimated by various methods, limited data exist on the activity of the methanogens at depth. We therefore analyzed the stable isotopic signature of the <span class="hlt">pore</span> <span class="hlt">waters</span> in two raised bogs from northern Minnesota to identify depth intervals in the peat profile where methanogenic metabolism occurs. Methanogenesis enriched the deuterium (2H) content of the deep peat <span class="hlt">pore</span> <span class="hlt">waters</span> by as much as +11% (Vienna Standard Mean Sea <span class="hlt">Water</span>), which compares to a much greater enrichment factor of +70% in leachate from New York City's Fresh Kills landfill. The bog <span class="hlt">pore</span> <span class="hlt">waters</span> were isotopically dated by tritium (3H) to be about 35 years old at 1.5 m depth, whereas the landfill leachate was estimated as ~ 17 years old from Darcy flow calculations. According to an isotopic mass balance the observed deuterium enrichment indicates that about 1.2 g of CH4m-3 d-1 were produced within the deeper peat, compared to about 2.8 g CH4 m-3 d-1 in the landfill. The values for methane production in the bog peat are substantially higher than the flux rates measured at the surface of the bogs or at the landfill, indicating that deeper methane production may be much higher than was previously assumed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/417922','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/417922"><span>Alkali-silica reaction and <span class="hlt">pore</span> solution composition in mortars in sea <span class="hlt">water</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kawamura, Mitsunori; Takeuchi, Katsunobu</p> <p>1996-12-01</p> <p>The promotion of expansion of mortars containing a reactive aggregate in 1N NaCl solution at 38 C was attributed to a rise of OH{sup {minus}} ion concentration in the <span class="hlt">pore</span> solution in the mortars. However, it is ambiguous whether the promotion of expansion of mortars in sea <span class="hlt">water</span> at a room temperature can be explained in the same way as in NaCl solution at an elevated temperature. This study aims at pursuing the expansion behavior of mortars containing a reactive aggregate relating it to their <span class="hlt">pore</span> solution composition and the extent of alkali-silica reaction occurring within reactive grains. The alkali-silica reaction in mortars in sea <span class="hlt">water</span> and 0.5 1N NaCl solution at 20 C appears to progress differently from that in mortars in 1N NaCl solution at an elevated temperature of 38 C. The promotion of expansion of mortars in sea <span class="hlt">water</span> at 20 C was found to be responsible for an effect of Cl{sup {minus}} ions in the alkali-silica reaction at early stages of immersion. Only when OH{sup {minus}} ion concentration in the <span class="hlt">pore</span> solution was relatively high, NaCl and sea <span class="hlt">water</span> could accelerate the alkali-silica reaction in mortars at 20 C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20063731','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20063731"><span>[Vegetation influence on nutrients distribution in <span class="hlt">pore</span> <span class="hlt">water</span> of salt marsh sediment].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Wei-Wei; Li, Dao-Ji; Gao, Lei</p> <p>2009-11-01</p> <p>The variations of nutrients in <span class="hlt">pore</span> <span class="hlt">water</span> of salt marsh sediment were surveyed in the middle intertidal zone of Chongming Dongtan during August 2007 to May 2008 to identify plant impact on nutrients distribution. The results show that NH4(+) -N and PO4(3-) -P concentrations are lower in <span class="hlt">pore</span> <span class="hlt">water</span> of Spartina alterniflora and Phragmites australis zones than in bare flat, and specially, NH4(+) -N concentrations in summer and autumn decrease by one more orders of magnitude. Compared to winter, nutrients concentrations are obviously higher during the period of plant growth, and plant biomass is clearly correlative to nitrogen and phosphorus. Vegetation growth influences nitrogen content intensively. NH4(-) -N concentrations in Spartina alterniflora and Phragmites australis zones are 44.21 and 74.38 micromol x L(-1) respectively, distinctly lower than that in bare flat and Scirpus mariquete zone (340.14 and 291.87 micromol x L(-1) respectively). Moreover, NO(x)(-) -N concentration is one to two order(s) of magnitude lower than NH4(+) -N, and its highest value exists in Phragmites australis zone (5.94 micromol x L(-1)). The results of molecule diffusive flux of nutrients in the surface sediment-overlying <span class="hlt">water</span> interface indicate that marsh sediment is the source for SiO3(2-) -Si, NH4(+) -N and PO4(3-) -P, and the rank for NO(x)(-) -N (NO3(-) -N + NO2(-) -N), and NO(x)(-) -N flux from overlying <span class="hlt">water</span> to sediment [16.23 micromol x (m2 x h)(-1)] is higher than NH4(+) -N flux from sediment to overlying <span class="hlt">water</span> [15.53 micromol x (m2 x h)(-1)]. Vegetation growth accommodates nutrient structure of the estuarine ecosystem by affecting sediment-<span class="hlt">water</span> interface mass flux and nutrient ratios in <span class="hlt">pore</span> <span class="hlt">water</span> and overlying <span class="hlt">water</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12463685','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12463685"><span>A <span class="hlt">marine</span> bioassay test set to assess <span class="hlt">marine</span> <span class="hlt">water</span> and sediment quality-its need, the approach and first results.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Peters, C; Becker, S; Noack, U; Pfitzner, S; Bülow, W; Barz, K; Ahlf, W; Berghahn, R</p> <p>2002-10-01</p> <p>There is a need for establishing a <span class="hlt">marine</span> bioassay test set to assess <span class="hlt">marine</span> <span class="hlt">water</span> and sediment samples in Germany. The selected <span class="hlt">marine</span> bioassay test set, two tests for the <span class="hlt">water</span> phase (with the luminescence bacteria Vibrio fischeri and the algae Phaeodactylum tricornutum Bohlin) and a whole sediment test with the <span class="hlt">marine</span> amphipod Corophium volutator (Pallas) is described and first results are shown.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2579537','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2579537"><span>Is hot <span class="hlt">water</span> immersion an effective treatment for <span class="hlt">marine</span> envenomation?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Atkinson, P R T; Boyle, A; Hartin, D; McAuley, D</p> <p>2006-01-01</p> <p>Envenomation by <span class="hlt">marine</span> creatures is common. As more people dive and snorkel for leisure, the incidence of envenomation injuries presenting to emergency departments has increased. Although most serious envenomations occur in the temperate or tropical <span class="hlt">waters</span> of the Indo‐Pacific region, North American and European <span class="hlt">waters</span> also provide a habitat for many stinging creatures. <span class="hlt">Marine</span> envenomations can be classified as either surface stings or puncture wounds. Antivenom is available for a limited number of specific <span class="hlt">marine</span> creatures. Various other treatments such as vinegar, fig juice, boiled cactus, heated stones, hot urine, hot <span class="hlt">water</span>, and ice have been proposed, although many have little scientific basis. The use of heat therapies, previously reserved for penetrating fish spine injuries, has been suggested as treatment for an increasing variety of <span class="hlt">marine</span> envenomation. This paper reviews the evidence for the effectiveness of hot <span class="hlt">water</span> immersion (HWI) and other heat therapies in the management of patients presenting with pain due to <span class="hlt">marine</span> envenomation. PMID:16794088</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16794088','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16794088"><span>Is hot <span class="hlt">water</span> immersion an effective treatment for <span class="hlt">marine</span> envenomation?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Atkinson, P R T; Boyle, A; Hartin, D; McAuley, D</p> <p>2006-07-01</p> <p>Envenomation by <span class="hlt">marine</span> creatures is common. As more people dive and snorkel for leisure, the incidence of envenomation injuries presenting to emergency departments has increased. Although most serious envenomations occur in the temperate or tropical <span class="hlt">waters</span> of the Indo-Pacific region, North American and European <span class="hlt">waters</span> also provide a habitat for many stinging creatures. <span class="hlt">Marine</span> envenomations can be classified as either surface stings or puncture wounds. Antivenom is available for a limited number of specific <span class="hlt">marine</span> creatures. Various other treatments such as vinegar, fig juice, boiled cactus, heated stones, hot urine, hot <span class="hlt">water</span>, and ice have been proposed, although many have little scientific basis. The use of heat therapies, previously reserved for penetrating fish spine injuries, has been suggested as treatment for an increasing variety of <span class="hlt">marine</span> envenomation. This paper reviews the evidence for the effectiveness of hot <span class="hlt">water</span> immersion (HWI) and other heat therapies in the management of patients presenting with pain due to <span class="hlt">marine</span> envenomation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24471470','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24471470"><span>Experimental and modeling studies of an unusual <span class="hlt">water</span>-filled <span class="hlt">pore</span> structure with possible mechanistic implications in family 48 cellulases.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chen, Mo; Kostylev, Maxim; Bomble, Yannick J; Crowley, Michael F; Himmel, Michael E; Wilson, David B; Brady, John W</p> <p>2014-03-06</p> <p>Molecular dynamics simulations were used to study the possible catalytic role of an unusual conserved <span class="hlt">water</span>-filled <span class="hlt">pore</span> structure in the family 48 cellulase enzyme Cel48A from Thermobifida fusca. It was hypothesized that this <span class="hlt">pore</span> serves as the pathway for the <span class="hlt">water</span> molecules consumed in the hydrolysis catalyzed by the enzyme to reach the active site in a continuous stream to participate in the processive reactions. Theoretical mutants of this enzyme were created in which all of the residues lining the <span class="hlt">pore</span> were made hydrophobic, which had the effect in molecular dynamics simulations of emptying the <span class="hlt">pore</span> of <span class="hlt">water</span> molecules and preventing any from passing through the <span class="hlt">pore</span> on the simulation time scale. Mutants with smaller numbers of substitutions of this nature, which could be created experimentally by site-directed mutagenesis, were also identified from simulations, and these proteins were subsequently produced in Escherichia coli, expressed and purified, but were found to not fold in a manner similar to the wild type protein, preventing the determination of the importance of the <span class="hlt">water</span> <span class="hlt">pore</span> for activity. It is possible that the presence of a small vacuum in the <span class="hlt">pore</span> was responsible for the instability of the mutants. In addition, alternate pathways were observed in the simulations that would allow <span class="hlt">water</span> molecules to reach the active site of the enzyme, suggesting that the hypothesis that the <span class="hlt">pore</span> has functional significance might be incorrect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70034971','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70034971"><span>Mercury cycling in stream ecosystems. 2. Benthic methylmercury production and bed sediment - <span class="hlt">Pore</span> <span class="hlt">water</span> partitioning</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Marvin-DiPasquale, M.; Lutz, M.A.; Brigham, M.E.; Krabbenhoft, D.P.; Aiken, G.R.; Orem, W.H.; Hall, B.D.</p> <p>2009-01-01</p> <p>Mercury speciation, controls on methylmercury (MeHg) production, and bed sediment - <span class="hlt">pore</span> <span class="hlt">water</span> partitioning of total Hg (THg) and MeHg were examined in bed sediment from eight geochemically diverse streams where atmospheric deposition was the predominant Hg input. Across all streams, sediment THg concentrations were best described as a combined function of sediment percent fines (%fines; particles < 63 ??m) and organic content. MeHg concentrations were best described as a combined function of organic content and the activity of the Hg(II)-methylating microbial community and were comparable to MeHg concentrations in streams with Hg inputs from industrial and mining sources. Whole sediment tin-reducible inorganic reactive Hg (Hg(II)R) was used as a proxy measure for the Hg(II) pool available for microbial methylation. In conjunction with radiotracer-derived rate constants of 203Hg(II) methylation, Hg(II)R was used to calculate MeHg production potential rates and to explain the spatial variability in MeHg concentration. The %Hg(II)R (of THg) was low (2.1 ?? 5.7%) and was inversely related to both microbial sulfate reduction rates and sediment total reduced sulfur concentration. While sediment THg concentrations were higher in urban streams, %MeHg and %Hg(II)R were higher in nonurban streams. Sediment <span class="hlt">pore</span> <span class="hlt">water</span> distribution coefficients (log Kd's) for both THg and MeHg were inversely related to the log-transformed ratio of <span class="hlt">pore</span> <span class="hlt">water</span> dissolved organic carbon (DOC) to bed sediment %fines. The stream with the highest drainage basin wetland density also had the highest <span class="hlt">pore</span> <span class="hlt">water</span> DOC ?? 2009 American Chemical Society.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1007760','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1007760"><span>Development of Layered Sediment Structure and its Effects on <span class="hlt">Pore</span> <span class="hlt">Water</span> Transport and Hyporheic Exchange</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Packman, Aaron I.; Marion, Andrea; Zaramella, Mattia; Chen, Cheng; Gaillard, Jean-François; Keane, Denis T.</p> <p>2008-04-15</p> <p>Hyporheic exchange is known to provide an important control on nutrient and contaminant fluxes across the stream-subsurface interface. Similar processes also mediate interfacial transport in other permeable sediments. Recent research has focused on understanding the mechanics of these exchange processes and improving estimation of exchange rates in natural systems. While the structure of sediment beds obviously influences <span class="hlt">pore</span> <span class="hlt">water</span> flow rates and patterns, little is known about the interplay of typical sedimentary structures, hyporheic exchange, and other transport processes in fluvial/alluvial sediments. Here we discuss several processes that contribute to local-scale sediment heterogeneity and present results that illustrate the interaction of overlying flow conditions, the development of sediment structure, <span class="hlt">pore</span> <span class="hlt">water</span> transport, and stream-subsurface exchange. Layered structures are shown to develop at several scales within sediment beds. Surface sampling is used to analyze the development of an armor layer in a sand-and-gravel bed, while innovative synchrotron-based X-ray microtomography is used to observe patterns of grain sorting within sand bedforms. We show that layered bed structures involving coarsening of the bed surface increase interfacial solute flux but produce an effective anisotropy that favors horizontal <span class="hlt">pore</span> <span class="hlt">water</span> transport while limiting vertical penetration.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70033063','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70033063"><span>Ecological impacts of lead mining on Ozark streams: Toxicity of sediment and <span class="hlt">pore</span> <span class="hlt">water</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Besser, J.M.; Brumbaugh, W.G.; Allert, A.L.; Poulton, B.C.; Schmitt, C.J.; Ingersoll, C.G.</p> <p>2009-01-01</p> <p>We studied the toxicity of sediments downstream of lead-zinc mining areas in southeast Missouri, using chronic sediment toxicity tests with the amphipod, Hyalella azteca, and <span class="hlt">pore-water</span> toxicity tests with the daphnid, Ceriodaphnia dubia. Tests conducted in 2002 documented reduced survival of amphipods in stream sediments collected near mining areas and reduced survival and reproduction of daphnids in most <span class="hlt">pore</span> <span class="hlt">waters</span> tested. Additional amphipod tests conducted in 2004 documented significant toxic effects of sediments from three streams downstream of mining areas: Strother Creek, West Fork Black River, and Bee Fork. Greatest toxicity occurred in sediments from a 6-km reach of upper Strother Creek, but significant toxic effects occurred in sediments collected at least 14 km downstream of mining in all three watersheds. Toxic effects were significantly correlated with metal concentrations (nickel, zinc, cadmium, and lead) in sediments and <span class="hlt">pore</span> <span class="hlt">waters</span> and were generally consistent with predictions of metal toxicity risks based on sediment quality guidelines, although ammonia and manganese may also have contributed to toxicity at a few sites. Responses of amphipods in sediment toxicity tests were significantly correlated with characteristics of benthic invertebrate communities in study streams. These results indicate that toxicity of metals associated with sediments contributes to adverse ecological effects in streams draining the Viburnum Trend mining district.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNH51D1932K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNH51D1932K"><span>Characteristics of fluoride in <span class="hlt">pore-water</span> at accidental hydrofluoric acid spillage site, Gumi, Korea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kwon, E. H.; Lee, H. A.; Lee, J.; Kim, D.; Lee, S.; Yoon, H. O.</p> <p>2015-12-01</p> <p>A leakage accident of hydrofluoric acid (HF) occurred in Gumi, South Korea at Sep. 2012. The study site is located in the borderline between a large-scale industrial complex and a rural area. The HF plume was made immediately, and moved toward the rural area through air. After the accident, 212 ha of farm land were influenced and most of crops were withered. To recover the soil, CaO was applied after six months. Although several studies have done to estimate the extension and movement of HF plume in the air and to assess the impact on human health or plant after the incident, the long-term fate of fluoride (F) in the affected soils is not identified clearly. Thus, this study aimed to understand the behavior of F in the soil after HF releasing from accident site through chemical analysis and geochemical modeling. Within the radius of 1 km of accident site, 16 <span class="hlt">pore-water</span> and soil samples were collected. The semi-quantitative soil composition (i.e., Al, Ca, Fe, K, Mg, Mn, Na, P, Si, Ti), total F, total P, OM contents in soil, and soil pH have already been measured, and <span class="hlt">pore-water</span> compositions are also identified. From these experimental and modeling data, we could be evaluate if impact of accident exists until now, and also could be select and identify existing form of fluoride in soil and <span class="hlt">pore-water</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70032530','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70032530"><span>Mapping of accumulated nitrogen in the sediment <span class="hlt">pore</span> <span class="hlt">water</span> of a eutrophic lake in Iowa, USA</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Iqbal, M.Z.; Fields, C.L.</p> <p>2009-01-01</p> <p>A large pool of nitrogen in the sediment <span class="hlt">pore</span> fluid of a eutrophic lake in Iowa, USA, was mapped in this study. Previously, the lake had supported fishing and boating, but today it no longer supports its designated uses as a recreational <span class="hlt">water</span> body. In the top 5 cm of the lake bottom, the <span class="hlt">pore</span> <span class="hlt">water</span> nitrogen ranges between 3.1 and 1,250 ??g/cm3 of sediments, with an average of 160.3 ??g/cm3. Vertically, nitrate concentrations were measured as 153 ??g/cm3 at 0-10 cm, 162 ??g/cm3 at 10-20 cm, and 32 ??g/cm3 at 20-30 cm. Nitrate mass distribution was quantified as 3.67 ?? 103 kg (65%) in the bottom sediments, 172 kg (3%) in suspended particulates, and 1.83 ?? 103 kg (32%) in the dissolved phase. Soil runoff nutrients arrive at the lake from the heavily fertilized lands in the watershed. Upon sedimentation, a large mass of nitrogen desorbs from mineral particles to the relatively immobile <span class="hlt">pore</span> fluid. Under favorable conditions, this nitrogen diffuses back into the <span class="hlt">water</span> column, thereby dramatically limiting the lake's capability to process incoming nutrients from farmlands. Consequently, a condition of oxygen deficiency disrupts the post-season biological activities in the lake. ?? 2008 Springer-Verlag.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/335351','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/335351"><span>Sulfide controls on mercury speciation and bioavailability to methylating bacteria in sediment <span class="hlt">pore</span> <span class="hlt">waters</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Benoit, J.M. |; Gilmour, C.C.; Heyes, A.; Mason, R.P.</p> <p>1999-03-15</p> <p>A chemical equilibrium model for Hg complexation in sediments with sulfidic <span class="hlt">pore</span> <span class="hlt">waters</span> is presented. The purpose of the model was to explain observed relationships between <span class="hlt">pore</span> <span class="hlt">water</span> sulfide, dissolved inorganic Hg (Hg{sub D}), and bulk methylmercury (MeHg) in surficial sediments of two biogeochemically different ecosystems, the Florida Everglades and Patuxent River, MD. The model was constructed to test the hypothesis that the availability of Hg for methylation in sediments is a function of the concentration of neutral dissolved Hg complexes rather than Hg{sup 2+} or total Hg{sub D}. The model included interaction of mercury with solids containing one or two sulfide groups, and it was able to reproduce observed Hg{sub D} and bulk MeHg trends in the two ecosystems. The model is consistent with HgS{sup 0} as the dominant neutral Hg complex and the form of Hg accumulated by methylating bacteria in sulfidic <span class="hlt">pore</span> <span class="hlt">waters</span>. The model-estimated decline in HgS{sup 0} with increasing sulfide was consistent with the observed decline in bulk sediments MeHg. Since bacterial Hg uptake rate is one of the factors affecting methylation rate, Hg complexation models such as the one presented are helpful in understanding the factors that control MeHg production and accumulation in aquatic ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1105044','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1105044"><span><span class="hlt">Pore</span> <span class="hlt">Water</span> Extraction Test Near 241-SX Tank Farm at the Hanford Site, Washington, USA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Eberlein, Susan J.; Parker, Danny L.; Tabor, Cynthia L.; Holm, Melissa J.</p> <p>2013-11-11</p> <p>A proof-of-principle test is underway near the Hanford Site 241-SX Tank Farm. The test will evaluate a potential remediation technology that will use tank farm-deployable equipment to remove contaminated <span class="hlt">pore</span> <span class="hlt">water</span> from vadose zone soils. The test system was designed and built to address the constraints of working within a tank farm. Due to radioactive soil contamination and limitations in drilling near tanks, small-diameter direct push drilling techniques applicable to tank farms are being utilized for well placement. To address space and weight limitations in working around tanks and obstacles within tank farms, the above ground portions of the test system have been constructed to allow deployment flexibility. The test system utilizes low vacuum over a sealed well screen to establish flow into an extraction well. Extracted <span class="hlt">pore</span> <span class="hlt">water</span> is collected in a well sump,and then pumped to the surface using a small-diameter bladder pump.If <span class="hlt">pore</span> <span class="hlt">water</span> extraction using this system can be successfully demonstrated, it may be possible to target local contamination in the vadose zone around underground storage tanks. It is anticipated that the results of this proof-of-principle test will support future decision making regarding interim and final actions for soil contamination within the tank farms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013HESSD..1013293V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013HESSD..1013293V"><span>Continual in-situ monitoring of <span class="hlt">pore</span> <span class="hlt">water</span> stable isotopes in the subsurface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Volkmann, T. H. M.; Weiler, M.</p> <p>2013-11-01</p> <p>The stable isotope signature of <span class="hlt">pore</span> <span class="hlt">water</span> provides an integral fingerprint of <span class="hlt">water</span> origin, flow path, transport processes, and residence times and can thus serve as a powerful tracer of hydrological processes in the unsaturated and saturated zone. However, the full potential of stable isotopes to quantitatively characterize subsurface <span class="hlt">water</span> dynamics is yet unfolded due to the difficulty in obtaining extensive detailed and continual measurements of spatiotemporally variable <span class="hlt">pore</span> <span class="hlt">water</span> signatures. With the development of field-deployable laser-based isotope analyzers, such measurements are now becoming feasible. This study presents the development and application of a functional, automatable, and cost-efficient system for non-destructive continual in-situ monitoring of <span class="hlt">pore</span> <span class="hlt">water</span> stable isotope signatures with high resolution. The monitoring system uses automatic-controllable valve arrays to continuously extract diluted soil air <span class="hlt">water</span> vapor via a branching network of multiple small microporous probes into a commercial isotope analyzer. Soil temperature observations are used to convert obtained vapor phase into liquid phase <span class="hlt">water</span> isotope signatures, but these can also be obtained based on vapor concentration measurements. In-situ sampling was conducted at six depths for each of three plots planted with varying vegetation on an experimental site in SW Germany. Two different methods based on advective and diffusive soil <span class="hlt">water</span> vapor probing were employed suitable under unsaturated and all (including saturated) moisture conditions, respectively. The advective sampling method was applied using multiple permanently installed probes (continual mode) and using a single probe subsequently inserted to sample the various locations (push-in mode), while the diffusive sampling method was applied in push-in mode only. Using a specific identical treatment onsite calibration approach along with basic corrections for instrument bias and temperature dependent free <span class="hlt">water</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26610961','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26610961"><span>The European <span class="hlt">Marine</span> Strategy: Noise Monitoring in European <span class="hlt">Marine</span> <span class="hlt">Waters</span> from 2014.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dekeling, René; Tasker, Mark; Ainslie, Michael; Andersson, Mathias; André, Michel; Borsani, Fabrizio; Brensing, Karsten; Castellote, Manuel; Dalen, John; Folegot, Thomas; van der Graaf, Sandra; Leaper, Russell; Liebschner, Alexander; Pajala, Jukka; Robinson, Stephen; Sigray, Peter; Sutton, Gerry; Thomsen, Frank; Werner, Stefanie; Wittekind, Dietrich; Young, John V</p> <p>2016-01-01</p> <p>The European <span class="hlt">Marine</span> Strategy Framework Directive requires European member states to develop strategies for their <span class="hlt">marine</span> <span class="hlt">waters</span> leading to programs of measures that achieve or maintain good environmental status (GES) in all European seas by 2020. An essential step toward reaching GES is the establishment of monitoring programs, enabling the state of <span class="hlt">marine</span> <span class="hlt">waters</span> to be assessed on a regular basis. A register for impulsive noise-generating activities would enable assessment of their cumulative impacts on wide temporal and spatial scales; monitoring of ambient noise would provide essential insight into current levels and any trend in European <span class="hlt">waters</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.9905O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.9905O"><span>Critical Evaluation of Soil <span class="hlt">Pore</span> <span class="hlt">Water</span> Extraction Methods on a Natural Soil</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Orlowski, Natalie; Pratt, Dyan; Breuer, Lutz; McDonnell, Jeffrey</p> <p>2017-04-01</p> <p>Soil <span class="hlt">pore</span> <span class="hlt">water</span> extraction is an important component in ecohydrological studies for the measurement of δ2H and δ18O. The effect of <span class="hlt">pore</span> <span class="hlt">water</span> extraction technique on resultant isotopic signature is poorly understood. Here we present results of an intercomparison of commonly applied lab-based soil <span class="hlt">water</span> extraction techniques on a natural soil: high pressure mechanical squeezing, centrifugation, direct vapor equilibration, microwave extraction, and two types of cryogenic extraction systems. We applied these extraction methods to a natural summer-dry (gravimetric <span class="hlt">water</span> contents ranging from 8% to 15%) glacio-lacustrine, moderately fine textured clayey soil; excavated in 10 cm sampling increments to a depth of 1 meter. Isotope results were analyzed via OA-ICOS and compared for each extraction technique that produced liquid <span class="hlt">water</span>. From our previous intercomparison study among the same extraction techniques but with standard soils, we discovered that extraction methods are not comparable. We therefore tested the null hypothesis that all extraction techniques would be able to replicate the natural evaporation front in a comparable manner occurring in a summer-dry soil. Our results showed that the extraction technique utilized had a significant effect on the soil <span class="hlt">water</span> isotopic composition. High pressure mechanical squeezing and vapor equilibration techniques produced similar results with similarly sloped evaporation lines. Due to the nature of soil properties and dryness, centrifugation was unsuccessful in obtaining <span class="hlt">pore</span> <span class="hlt">water</span> for isotopic analysis. Cryogenic extraction on both tested techniques produced similar results to each other on a similar sloping evaporation line, but dissimilar with depth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23534199','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23534199"><span>Metals in sediment/<span class="hlt">pore</span> <span class="hlt">water</span> in Chaohu Lake: distribution, trends and flux.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wen, Shengfang; Shan, Baoqing; Zhang, Hong</p> <p>2012-01-01</p> <p>Nine metals, Cd, Cu, Ni, Pb, As, Cr, Zn, Fe, and Mn in sediment and <span class="hlt">pore</span> <span class="hlt">water</span> from 57 sampling sites in Chaohu Lake (Anhui Province, China) were analyzed for spatial distribution, temporal trends and diffuse flux in 2010. Metals in the surface sediment were generally the highest in the western lake center and Nanfei-Dianbu River estuary, with another higher area of As, Fe, and Mn occurring in the Qiyang River estuary. Metal contamination assessment using the New York sediment screening criteria showed that the sediment was severely contaminated in 44% of the area with Mn, 20% with Zn, 16% with Fe, 14% with As, and 6% with Cr and Ni. An increasing trend of toxic metals (Cd, Cu, Ni, Pb, As, Cr, Zn) and Mn with depth was shown in the western lake. Compared with metal content data from the sediment survey conducted in 1980s, the metal content of surface sediment in 2010 was 2.0 times that in the 1980s for Cr, Cu, Zn, and As in the western lake, and less than 1.5 times higher for most of the metals in the eastern lake. Among the metals, only Mn and As had a widespread positive diffuse flux from the <span class="hlt">pore</span> <span class="hlt">water</span> to overlying <span class="hlt">water</span> across the whole lake. The estimated flux in the whole lake was on average 3.36 mg/(m2 x day) for Mn and 0.08 mg/(m2 x day) for As, which indicated a daily increase of 0.93 microg/L for Mn and 0.02 microg/L for As in surface <span class="hlt">water</span>. The increasing concentration of metals in the sediment and the flux of metals from <span class="hlt">pore</span> <span class="hlt">water</span> to overlying <span class="hlt">water</span> by diffusion and other physical processes should not be ignored for drinking-<span class="hlt">water</span> sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015HESS...19.2617S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015HESS...19.2617S"><span>Estimating flow and transport parameters in the unsaturated zone with <span class="hlt">pore</span> <span class="hlt">water</span> stable isotopes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sprenger, M.; Volkmann, T. H. M.; Blume, T.; Weiler, M.</p> <p>2015-06-01</p> <p>Determining the soil hydraulic properties is a prerequisite to physically model transient <span class="hlt">water</span> flow and solute transport in the vadose zone. Estimating these properties by inverse modelling techniques has become more common within the last 2 decades. While these inverse approaches usually fit simulations to hydrometric data, we expanded the methodology by using independent information about the stable isotope composition of the soil <span class="hlt">pore</span> <span class="hlt">water</span> depth profile as a single or additional optimization target. To demonstrate the potential and limits of this approach, we compared the results of three inverse modelling strategies where the fitting targets were (a) <span class="hlt">pore</span> <span class="hlt">water</span> isotope concentrations, (b) a combination of <span class="hlt">pore</span> <span class="hlt">water</span> isotope concentrations and soil moisture time series, and (c) a two-step approach using first soil moisture data to determine <span class="hlt">water</span> flow parameters and then the <span class="hlt">pore</span> <span class="hlt">water</span> stable isotope concentrations to estimate the solute transport parameters. The analyses were conducted at three study sites with different soil properties and vegetation. The transient unsaturated <span class="hlt">water</span> flow was simulated by solving the Richards equation numerically with the finite-element code of HYDRUS-1D. The transport of deuterium was simulated with the advection-dispersion equation, and a modified version of HYDRUS was used, allowing deuterium loss during evaporation. The Mualem-van Genuchten and the longitudinal dispersivity parameters were determined for two major soil horizons at each site. The results show that approach (a), using only the <span class="hlt">pore</span> <span class="hlt">water</span> isotope content, cannot substitute hydrometric information to derive parameter sets that reflect the observed soil moisture dynamics but gives comparable results when the parameter space is constrained by pedotransfer functions. Approaches (b) and (c), using both the isotope profiles and the soil moisture time series, resulted in good simulation results with regard to the Kling-Gupta efficiency and good parameter</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1343742-linking-basin-scale-pore-scale-gas-hydrate-distribution-patterns-diffusion-dominated-marine-hydrate-systems','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1343742-linking-basin-scale-pore-scale-gas-hydrate-distribution-patterns-diffusion-dominated-marine-hydrate-systems"><span>Linking basin-scale and <span class="hlt">pore</span>-scale gas hydrate distribution patterns in diffusion-dominated <span class="hlt">marine</span> hydrate systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Nole, Michael; Daigle, Hugh; Cook, Ann E.; ...</p> <p>2017-02-07</p> <p>The goal of this study is to computationally determine the potential distribution patterns of diffusion-driven methane hydrate accumulations in coarse-grained <span class="hlt">marine</span> sediments. Diffusion of dissolved methane in <span class="hlt">marine</span> gas hydrate systems has been proposed as a potential transport mechanism through which large concentrations of hydrate can preferentially accumulate in coarse-grained sediments over geologic time. Using one-dimensional compositional reservoir simulations, we examine hydrate distribution patterns at the scale of individual sand layers (1 to 20 m thick) that are deposited between microbially active fine-grained material buried through the gas hydrate stability zone (GHSZ). We then extrapolate to two- dimensional and basin-scalemore » three-dimensional simulations, where we model dipping sands and multilayered systems. We find that properties of a sand layer including <span class="hlt">pore</span> size distribution, layer thickness, dip, and proximity to other layers in multilayered systems all exert control on diffusive methane fluxes toward and within a sand, which in turn impact the distribution of hydrate throughout a sand unit. In all of these simulations, we incorporate data on physical properties and sand layer geometries from the Terrebonne Basin gas hydrate system in the Gulf of Mexico. We demonstrate that diffusion can generate high hydrate saturations (upward of 90%) at the edges of thin sands at shallow depths within the GHSZ, but that it is ineffective at producing high hydrate saturations throughout thick (greater than 10 m) sands buried deep within the GHSZ. As a result, we find that hydrate in fine-grained material can preserve high hydrate saturations in nearby thin sands with burial.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMNH31B1602B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMNH31B1602B"><span>Elucidating the mechanical effects of <span class="hlt">pore</span> <span class="hlt">water</span> pressure increase on the stability of unsaturated soil slopes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buscarnera, G.</p> <p>2012-12-01</p> <p>The increase of the <span class="hlt">pore</span> <span class="hlt">water</span> pressure due to rain infiltration can be a dominant component in the activation of slope failures. This paper shows an application of the theory of material stability to the triggering analysis of this important class of natural hazards. The goal is to identify the mechanisms through which the process of suction removal promotes the initiation of mechanical instabilities. The interplay between increase in <span class="hlt">pore</span> <span class="hlt">water</span> pressure, and failure mechanisms is investigated at material point level. In order to account for multiple failure mechanisms, the second-order work criterion is used and different stability indices are devised. The paper shows that the theory of material stability can assess the risk of shear failure and static liquefaction in both saturated and unsaturated contexts. It is shown that the combined use of an enhanced definition of second-order work for unsaturated porous media and a hydro-mechanical constitutive framework enables to retrieve bifurcation conditions for <span class="hlt">water</span>-infiltration processes in unsaturated deposits. This finding discloses the importance of the coupling terms that incorporate the interaction between the solid skeleton and the <span class="hlt">pore</span> fluids. As a consequence, these theoretical results suggest that some material properties that are not directly associated with the shearing resistance (e.g., the potential for wetting compaction) can play an important role in the initiation of slope failures. According to the proposed interpretation, the process of <span class="hlt">pore</span> pressure increase can be understood as a trigger of uncontrolled strains, which at material point level are reflected by the onset of bifurcation conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28297654','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28297654"><span>Role of <span class="hlt">Pore</span>-Lining Residues in Defining the Rate of <span class="hlt">Water</span> Conduction by Aquaporin-0.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Saboe, Patrick O; Rapisarda, Chiara; Kaptan, Shreyas; Hsiao, Yu-Shan; Summers, Samantha R; De Zorzi, Rita; Dukovski, Danijela; Yu, Jiaheng; de Groot, Bert L; Kumar, Manish; Walz, Thomas</p> <p>2017-03-14</p> <p>Compared to other aquaporins (AQPs), lens-specific AQP0 is a poor <span class="hlt">water</span> channel, and its permeability was reported to be pH-dependent. To date, most <span class="hlt">water</span> conduction studies on AQP0 were performed on protein expressed in Xenopus oocytes, and the results may therefore also reflect effects introduced by the oocytes themselves. Experiments with purified AQP0 reconstituted into liposomes are challenging because the <span class="hlt">water</span> permeability of AQP0 is only slightly higher than that of pure lipid bilayers. By reconstituting high amounts of AQP0 and using high concentrations of cholesterol to reduce the permeability of the lipid bilayer, we improved the signal-to-noise ratio of <span class="hlt">water</span> permeability measurements on AQP0 proteoliposomes. Our measurements show that mutation of two <span class="hlt">pore</span>-lining tyrosine residues, Tyr-23 and Tyr-149 in sheep AQP0, to the corresponding residues in the high-permeability <span class="hlt">water</span> channel AQP1 have additive effects and together increase the <span class="hlt">water</span> permeability of AQP0 40-fold to a level comparable to that of AQP1. Molecular dynamics simulations qualitatively support these experimental findings and suggest that mutation of Tyr-23 changes the <span class="hlt">pore</span> profile at the gate formed by residue Arg-187.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20871542','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20871542"><span>Inkbottle <span class="hlt">Pore</span>-Method: Prediction of hygroscopic <span class="hlt">water</span> content in hardened cement paste at variable climatic conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Espinosa, Rosa Maria . E-mail: espinosa@tuhh.de; Franke, Lutz</p> <p>2006-10-15</p> <p>The aim of this work is the development of a practicable method for the reliable prediction of the equilibrium hygroscopic <span class="hlt">water</span> content in hardened cement paste and cement mortars at changing climatic conditions. Sorption thermodynamics and multi-scale <span class="hlt">pore</span> structure of hardened cement paste build the basis of the new computation procedure. Drying and chemical aging lead to a formation of inkbottle <span class="hlt">pores</span>. Their influence on sorption behaviour will be considered in particular by including them into the <span class="hlt">pore</span> model. Experimental data of adsorption, desorption and scanning-isotherms verify the new computation method, which has been called 'IBP-Method' (inkbottle <span class="hlt">pores</span>)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/893390','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/893390"><span>Data Qualification Report: <span class="hlt">Pore</span> <span class="hlt">Water</span> Data for Use on the Yucca Mountain Project</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>H. Miller; R. Monks; C. Warren; W. Wowak</p> <p>2000-06-09</p> <p><span class="hlt">Pore</span> <span class="hlt">water</span> data associated with Data Tracking Number (DTN) No.LL990702804244.100 are referenced in the Analysis and Model Reports (AMRs) prepared to support the Site Recommendation in determining the suitability of the Yucca Mountain, Nevada as a repository for high-level nuclear waste. It has been determined, in accordance with procedure AP-3.15Q Rev. 1, ICN 1, ''Managing Technical Product Inputs'', Attachment 6 , that the DTN-referenced data are used in AMRs that provide a direct calculation of ''Principal Factors'' for the Post-closure Safety Case or Potentially Disruptive Processes or Events. Therefore, in accordance with the requirements of procedure AP-SIII.2Q, Rev 0, ICN 2, ''Qualification of Unqualified Data and the Documentation of Rationale for Accepted Data'', Section 5.3.1 .a, a Data Qualification Report has been prepared for submittal to the Assistant Manager, Office of Project Execution for concurrence. This report summarizes the findings of the Data Qualification Team assembled to evaluate unqualified ''<span class="hlt">pore</span> <span class="hlt">water</span> data'' represented by DTN No. LL990702804244.100. This DTN is currently used in the following AMRs: Drift-Scale Coupled Processes (DST and THC Seepage) Models (CRWMS M&O 2000a), Environment of the Surfaces of the Drip Shield and Waste Package Outer Barrier (CRWMS M&O 2000b), and Engineered Barrier System: Physical and Chemical Environment Model (CRWMS M&O 2000c). Mineral composition of <span class="hlt">pore</span> <span class="hlt">water</span> submitted to the Technical Data Management System (TDMS) using the subject DTN were acquired data from the analysis <span class="hlt">pore</span> <span class="hlt">water</span> samples sent to Lawrence Livermore National Laboratory's (LLNL) by UFA Ventures, Inc. and analyzed by LLNL's Analytical Sciences/Analytical and Nuclear Chemistry Division (ASD). The purpose and scope of the AMRs that reference the subject DTN and the potential application of <span class="hlt">pore</span> <span class="hlt">water</span> data is described below. These AMRs use only that data associated with the specific samples: ESF-HD-PERM-1, ESF-HD-PERM-2, and ESF-HD-PERM-3</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1226245','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1226245"><span>Surface and Active Layer <span class="hlt">Pore</span> <span class="hlt">Water</span> Chemistry from Ice Wedge Polygons, Barrow, Alaska, 2013-2014</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>David E. Graham; Baohua Gu; Elizabeth M. Herndon; Stan D. Wullschleger; Ziming Yang; Liyuan Liang</p> <p>2016-11-10</p> <p>This data set reports the results of spatial surveys of aqueous geochemistry conducted at Intensive Site 1 of the Barrow Environmental Observatory in 2013 and 2014 (Herndon et al., 2015). Surface <span class="hlt">water</span> and soil <span class="hlt">pore</span> <span class="hlt">water</span> samples were collected from multiple depths within the tundra active layer of different microtopographic features (troughs, ridges, center) of a low-centered polygon (area A), high-centered polygon (area B), flat-centered polygon (area C), and transitional polygon (area D). Reported analytes include dissolved organic and inorganic carbon, dissolved carbon dioxide and methane, major inorganic anions, and major and minor cations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28920165','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28920165"><span>Distinctive Patterns in the Taxonomical Resolution of Bacterioplankton in the Sediment and <span class="hlt">Pore</span> <span class="hlt">Waters</span> of Contrasted Freshwater Lakes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Keshri, J; Pradeep Ram, A S; Sime-Ngando, T</p> <p>2017-09-17</p> <p>Bacteria assemblages in lake sediments play a key role in various biogeochemical processes, yet their association with interstitial <span class="hlt">pore</span> <span class="hlt">waters</span> has been scarcely investigated. In this study, we utilized Illumina next-generation amplicon sequencing of the 16S rRNA gene to characterize the seasonal bacterial communities in the sediments and <span class="hlt">pore</span> <span class="hlt">waters</span> of three contrasted temperate freshwater lakes, namely Pavin, Aydat, and Grangent (French Massif Central). Despite occupying seemingly similar habitats, bacterial communities differed substantially between sediments and <span class="hlt">pore</span> <span class="hlt">waters</span> at all seasons with low sharing of operational taxonomic units (OTUs, 6.7 to 20.3%) between them. Sediment-associated bacteria were more rich and diverse than <span class="hlt">pore</span> <span class="hlt">water</span> bacteria, indicating a high heterogeneity in the sediment microhabitat. The changes in both sediment and <span class="hlt">pore</span> <span class="hlt">water</span> bacterial communities were lake and season specific. The bacterial community showed distinct differences between the lakes, with larger presence of strict anaerobes such as Syntrophus, Syntrophorhabdus, and Sulfuricurvum in the <span class="hlt">pore</span> <span class="hlt">water</span> and sediments of Pavin responsible for carbon and sulfur cycling. In both Aydat and Grangent, the hgcI_clade dominated throughout the study period in the <span class="hlt">pore</span> <span class="hlt">waters</span>. The higher representation of lesser-known transient members of lake communities such as Methylotenera in the <span class="hlt">pore</span> <span class="hlt">waters</span> of Aydat, and Clostridium and Sulfuricurvum in the <span class="hlt">pore</span> and sediments of Grangent, respectively, were observed during the period of temporary anoxia in summer caused by lake stratification. Our study revealed that in the investigated lakes, the prevailing environmental factors across time and space structured and influenced the adaptation of bacterial communities to specific ecological niches.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPhCS.618a2041S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPhCS.618a2041S"><span>Confined <span class="hlt">water</span> in controlled <span class="hlt">pore</span> glass CPG-10-120 studied by positron annihilation lifetime spectroscopy and differential scanning calorimetry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Šauša, O.; Mat'ko, I.; Illeková, E.; Macová, E.; Berek, D.</p> <p>2015-06-01</p> <p>The solidification and melting of <span class="hlt">water</span> confined in the controlled <span class="hlt">pore</span> glass (CPG) with average <span class="hlt">pore</span> size 12.6 nm has been studied by differential scanning calorimetry (DSC) and positron annihilation lifetime spectroscopy (PALS). The fully-filled sample of CPG by <span class="hlt">water</span> as well as the samples of CPG with different content of <span class="hlt">water</span> were used. The measurements show the presence of amorphous and crystalline phases of <span class="hlt">water</span> in this type and size of <span class="hlt">pores</span>, freezing point depression of a confined liquid and presence of certain transitions at lower temperatures, which could be detected only for cooling regime. The localization of confined <span class="hlt">water</span> in the partially filled <span class="hlt">pores</span> of CPG at room temperature was studied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1301716','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1301716"><span>Insertion and <span class="hlt">pore</span> formation driven by adsorption of proteins onto lipid bilayer membrane-<span class="hlt">water</span> interfaces.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zuckermann, M J; Heimburg, T</p> <p>2001-01-01</p> <p>We describe the binding of proteins to lipid bilayers in the case for which binding can occur either by adsorption to the lipid bilayer membrane-<span class="hlt">water</span> interface or by direct insertion into the bilayer itself. We examine in particular the case when the insertion and <span class="hlt">pore</span> formation are driven by the adsorption process using scaled particle theory. The adsorbed proteins form a two-dimensional "surface gas" at the lipid bilayer membrane-<span class="hlt">water</span> interface that exerts a lateral pressure on the lipid bilayer membrane. Under conditions of strong intrinsic binding and a high degree of interfacial converge, this pressure can become high enough to overcome the energy barrier for protein insertion. Under these conditions, a subtle equilibrium exists between the adsorbed and inserted proteins. We propose that this provides a control mechanism for reversible insertion and <span class="hlt">pore</span> formation of proteins such as melittin and magainin. Next, we discuss experimental data for the binding isotherms of cytochrome c to charged lipid membranes in the light of our theory and predict that cytochrome c inserts into charged lipid bilayers at low ionic strength. This prediction is supported by titration calorimetry results that are reported here. We were furthermore able to describe the observed binding isotherms of the <span class="hlt">pore</span>-forming peptides endotoxin (alpha 5-helix) and of pardaxin to zwitterionic vesicles from our theory by assuming adsorption/insertion equilibrium. PMID:11606262</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70046045','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70046045"><span>A USANS/SANS study of the accessibility of <span class="hlt">pores</span> in the Barnett Shale to methane and <span class="hlt">water</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ruppert, Leslie F.; Sakurovs, Richard; Blach, Tomasz P.; He, Lilin; Melnichenko, Yuri B.; Mildner, David F.; Alcantar-Lopez, Leo</p> <p>2013-01-01</p> <p>Shale is an increasingly important source of natural gas in the United States. The gas is held in fine <span class="hlt">pores</span> that need to be accessed by horizontal drilling and hydrofracturing techniques. Understanding the nature of the <span class="hlt">pores</span> may provide clues to making gas extraction more efficient. We have investigated two Mississippian Barnett Shale samples, combining small-angle neutron scattering (SANS) and ultrasmall-angle neutron scattering (USANS) to determine the <span class="hlt">pore</span> size distribution of the shale over the size range 10 nm to 10 μm. By adding deuterated methane (CD4) and, separately, deuterated <span class="hlt">water</span> (D2O) to the shale, we have identified the fraction of <span class="hlt">pores</span> that are accessible to these compounds over this size range. The total <span class="hlt">pore</span> size distribution is essentially identical for the two samples. At <span class="hlt">pore</span> sizes >250 nm, >85% of the <span class="hlt">pores</span> in both samples are accessible to both CD4 and D2O. However, differences in accessibility to CD4 are observed in the smaller <span class="hlt">pore</span> sizes (~25 nm). In one sample, CD4 penetrated the smallest <span class="hlt">pores</span> as effectively as it did the larger ones. In the other sample, less than 70% of the smallest <span class="hlt">pores</span> (4, but they were still largely penetrable by <span class="hlt">water</span>, suggesting that small-scale heterogeneities in methane accessibility occur in the shale samples even though the total porosity does not differ. An additional study investigating the dependence of scattered intensity with pressure of CD4 allows for an accurate estimation of the pressure at which the scattered intensity is at a minimum. This study provides information about the composition of the material immediately surrounding the <span class="hlt">pores</span>. Most of the accessible (open) <span class="hlt">pores</span> in the 25 nm size range can be associated with either mineral matter or high reflectance organic material. However, a complementary scanning electron microscopy investigation shows that most of the <span class="hlt">pores</span> in these shale samples are contained in the organic components. The neutron scattering results indicate that the <span class="hlt">pores</span> are</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S21B2691V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S21B2691V"><span>An experimental study of the influence of <span class="hlt">pore</span> <span class="hlt">water</span> on dynamic rupture processes.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Violay, M.; Acosta, M.; Passelegue, F. X.; Schubnel, A.</p> <p>2016-12-01</p> <p>Fluids play a fundamental role in controlling fault strength and earthquake nucleation, propagation and arrest (Sibson, 1973, 2000; Lachenbruch, 1980; Rice, 1992, 2006; Hickman et al., 1995). The understanding of how the presence of fluid in faults affects the seismic cycle in the upper continental crust remains poor, especially in the case of induced seismicity due to engineering applications (Hydraulic stimulations). To examine the influence of <span class="hlt">pore</span> <span class="hlt">water</span> on dynamic rupture processes in the context of deep geothermal reservoirs, we conducted stick slip experiments on thermally-treated, saw-cut westerly granite samples under triaxial loading (σ1>σ2=σ3) at confining pressures (σ3) ranging from 10 to 95 MPa and <span class="hlt">pore</span> <span class="hlt">water</span> pressures ranging from 0 to 94 MPa (Schubnel et al. 2011 and Passelègue et al. 2013, 2016). The samples were instrumented with four strain gages recorded at high frequencies and one thermocouple located close to the fault plane, that allowed measuring respectively dynamic shear stress drops and temperature elevation. The nucleation point of slip and rupture speeds were assessed during the experiments through an acoustic monitoring array. The method consists in recording particle motion at high-frequencies for each acoustic emission event and inversing the arrival times for each sensor of the array. We recorded more than 200 stick slip events. Preliminary results showed that at a given effective confining pressure (Pc-pf), the dynamic shear stress drops were about 20 to 30% higher and slip distances were about 30 to 40% longer in dry samples than in <span class="hlt">water</span> saturated samples. Following the same tendency, higher temperature elevations were recorded during nominally dry experiments. These results highlight the importance of <span class="hlt">pore</span> <span class="hlt">water</span> pressure in frictional processes, and suggest that <span class="hlt">water</span> might inhibit dynamic weakening and so, rupture propagation in granitic rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.3878U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.3878U"><span>Simulated Seismic Load Tests on Dam Core Material to Scrutinize <span class="hlt">Pore</span> <span class="hlt">Water</span> Pressure Development</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Umar Farooq, Qazi; Uchimura, Taro</p> <p>2010-05-01</p> <p>Dam Core is the back bone of the large earthen dam and primarily constructed with fine grained soils. In this research Cyclic tri-axial tests are used to simulate the effect of different earthquake intensities on medium to high confined Fujinomori clay (replicated dam core material). Seismic load intensity is reproduced in the laboratory by applying different cyclic stress amplitudes, while the numbers of cycles (N) were kept constant. Both isotropic and anisotropic conditions are included in the test plan. Key discussions are distresses generated by seismic loading such as <span class="hlt">pore</span> <span class="hlt">water</span> pressure (PWP), deformations, possibility of micro cracking, and effective strength reduction. With increase in cyclic stress amplitude, exponential increases in <span class="hlt">pore</span> pressure (PWP), sudden decrease in mean effective principal stress (P') which ultimately increases overall instability in dam core, large deformations, and generation of micro / macro cracking are primary conclusions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24437854','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24437854"><span><span class="hlt">Marine</span> mammal audibility of selected shallow-<span class="hlt">water</span> survey sources.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>MacGillivray, Alexander O; Racca, Roberto; Li, Zizheng</p> <p>2014-01-01</p> <p>Most attention about the acoustic effects of <span class="hlt">marine</span> survey sound sources on <span class="hlt">marine</span> mammals has focused on airgun arrays, with other common sources receiving less scrutiny. Sound levels above hearing threshold (sensation levels) were modeled for six <span class="hlt">marine</span> mammal species and seven different survey sources in shallow <span class="hlt">water</span>. The model indicated that odontocetes were most likely to hear sounds from mid-frequency sources (fishery, communication, and hydrographic systems), mysticetes from low-frequency sources (sub-bottom profiler and airguns), and pinnipeds from both mid- and low-frequency sources. High-frequency sources (side-scan and multibeam) generated the lowest estimated sensation levels for all <span class="hlt">marine</span> mammal species groups.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/860281','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/860281"><span>STRONTIUM ISOTOPE EVOLUTION OF <span class="hlt">PORE</span> <span class="hlt">WATER</span> AND CALCITE IN THE TOPOPAH SPRING TUFF, YUCCA MOUNTAIN , NEVADA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>B.D. Marshall; K. Futa</p> <p>2001-02-07</p> <p>Yucca Mountain, a ridge of Miocene volcanic rocks in southwest Nevada, is being characterized as a site for a potential high-level radioactive waste repository. One issue of concern for the future performance of the potential repository is the movement of <span class="hlt">water</span> in and around the potential repository horizon. Past <span class="hlt">water</span> movement in this unsaturated zone is indicated by fluid inclusions trapped in calcite coatings on fracture footwall surfaces and in some lithophysal cavities. Some of the fluid inclusions have homogenization temperatures above the present-day geotherm (J.F. Whelan, written communication), so determining the ages of the calcite associated with those fluid inclusions is important in understanding the thermal history of the potential repository site. Calcite ages have been constrained by uranium-lead dating of silica polymorphs (opal and chalcedony) that are present in most coatings. The opal and chalcedony ages indicate that deposition of the calcite and opal coatings in the welded part of the Topopah Spring Tuff (TSw hydrogeologic unit) spanned nearly the entire history of the 12.8-million-year-old rock mass at fairly uniform overall long-term rates of deposition (within a factor of five). Constraining the age of a layer of calcite associated with specific fluid inclusions is complicated. Calcite is commonly bladed with complex textural relations, and datable opal or chalcedony may be millions of years older or younger than the calcite layer or may be absent from the coating entirely. Therefore, a more direct method of dating the calcite is presented in this paper by developing a model for strontium evolution in <span class="hlt">pore</span> <span class="hlt">water</span> in the TSw as recorded by the strontium coprecipitated with calcium in the calcite. Although the <span class="hlt">water</span> that precipitated the calcite in fractures and cavities may not have been in local isotopic equilibrium with the <span class="hlt">pore</span> <span class="hlt">water</span>, the strontium isotope composition of all <span class="hlt">water</span> in the TSw is primarily controlled by <span class="hlt">water</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ApSS..283..941L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ApSS..283..941L"><span>Effects of residual <span class="hlt">water</span> in the <span class="hlt">pores</span> of aluminum anodic oxide layers prior to sealing on corrosion resistance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Junghoon; Jung, Uoochang; Kim, Wangryeol; Chung, Wonsub</p> <p>2013-10-01</p> <p>The effects of residual <span class="hlt">water</span> in the <span class="hlt">pores</span> of aluminum anodic oxide layers before the sealing process on corrosion resistance were studied. When residual <span class="hlt">water</span> was present in <span class="hlt">pores</span> before cold NiF2 sealing, corrosion resistance was dramatically increased especially in acid chloride electrolyte. It is considered that residual <span class="hlt">water</span> in <span class="hlt">pores</span> provides paths that allow sealing media to diffuse through the oxide layer, thereby sealing <span class="hlt">pores</span> up to inner side of porous layer nearby barrier layer. For hydrothermal sealing, corrosion resistance improvements by residual <span class="hlt">water</span> were also observed. However, improvements in corrosion resistance by cold NiF2 sealing were greater than those achieved by hydrothermal sealing, due to cracks formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22037694','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22037694"><span>Transgenic nematodes as biosensors for metal stress in soil <span class="hlt">pore</span> <span class="hlt">water</span> samples.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Anbalagan, Charumathi; Lafayette, Ivan; Antoniou-Kourounioti, Melissa; Haque, Mainul; King, John; Johnsen, Bob; Baillie, David; Gutierrez, Carmen; Martin, Jose A Rodriguez; de Pomerai, David</p> <p>2012-03-01</p> <p>Caenorhabditis elegans strains carrying stress-reporter green fluorescent protein transgenes were used to explore patterns of response to metals. Multiple stress pathways were induced at high doses by most metals tested, including members of the heat shock, oxidative stress, metallothionein (mtl) and xenobiotic response gene families. A mathematical model (to be published separately) of the gene regulatory circuit controlling mtl production predicted that chemically similar divalent metals (classic inducers) should show additive effects on mtl gene induction, whereas chemically dissimilar metals should show interference. These predictions were verified experimentally; thus cadmium and mercury showed additive effects, whereas ferric iron (a weak inducer) significantly reduced the effect of mercury. We applied a similar battery of tests to diluted samples of soil <span class="hlt">pore</span> <span class="hlt">water</span> extracted centrifugally after mixing 20% w/w ultrapure <span class="hlt">water</span> with air-dried soil from an abandoned lead/zinc mine in the Murcia region of Spain. In addition, metal contents of both soil and soil <span class="hlt">pore</span> <span class="hlt">water</span> were determined by ICP-MS, and simplified mixtures of soluble metal salts were tested at equivalent final concentrations. The effects of extracted soil <span class="hlt">pore</span> <span class="hlt">water</span> (after tenfold dilution) were closely mimicked by mixtures of its principal component ions, and even by the single most prevalent contaminant (zinc) alone, though other metals modulated its effects both positively and negatively. In general, mixtures containing similar (divalent) metal ions exhibited mainly additive effects, whereas admixture of dissimilar (e.g. trivalent) ions often resulted in interference, reducing overall levels of stress-gene induction. These findings were also consistent with model predictions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009PhRvE..79c1606M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009PhRvE..79c1606M"><span>Molecular dynamics simulations of supercritical <span class="hlt">water</span> confined within a carbon-slit <span class="hlt">pore</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martí, J.; Sala, J.; Guàrdia, E.; Gordillo, M. C.</p> <p>2009-03-01</p> <p>We report the results of a series of molecular dynamics simulations of <span class="hlt">water</span> inside a carbon-slit <span class="hlt">pore</span> at supercritical conditions. A range of densities corresponding from liquid (0.66gcm-3) to gas environments (0.08gcm-3) at the supercritical temperature of 673K were considered. Our findings are compared with previous studies of liquid <span class="hlt">water</span> confined in graphene nanochannels at ambient and high temperatures, and indicate that the microscopic structure of <span class="hlt">water</span> evolves from hydrogen bond networks characteristic of hot dense liquids to looser arrangements where the dominant units are <span class="hlt">water</span> monomers and dimers. <span class="hlt">Water</span> permittivity was found to be very small at low densities, with a tendency to grow with density and to reach typical values of unconfined supercritical <span class="hlt">water</span> at 0.66gcm-3) . In supercritical conditions, the residence time of <span class="hlt">water</span> at interfaces is roughly similar to that of <span class="hlt">water</span> in the central regions of the slabs, if the size of the considered region is taken into account. That time span is long enough to compute dynamical properties such as diffusion or spectral densities. <span class="hlt">Water</span> diffusion in supercritical states is much faster at low densities, and it is produced in such a way that, at interfaces, translational diffusion is mainly produced along planes parallel to the carbon walls. Spectral frequency shifts depend on several factors, being temperature and density effects the most relevant. However, we can observe corrections due to confinement, important both at the graphene interface and in the central region of the <span class="hlt">water</span> slab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/860271','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/860271"><span><span class="hlt">PORE-WATER</span> ISOTOPIC COMPOSITION AND UNSATURATED-ZONE FLOW, YUCCA MOUNTAIN, NEVADA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>C. Yang</p> <p>2000-10-23</p> <p>Site characterization at Yucca Mountain, Nevada, the site of a potential high-level radioactive waste repository, has included studies of recharge, flow paths, percolation flux, perched <span class="hlt">water</span> bodies, and chemical compositions of the <span class="hlt">water</span> in the thick unsaturated zone (UZ). Samples of <span class="hlt">pore</span> <span class="hlt">water</span> from cores of two recently drilled boreholes, USW SD-6 near the ridge top of Yucca Mountain and USW WT-24 north of Yucca mountain, were analyzed for isotopic compositions as part of a study by the US Geological Survey (USGS), in cooperation with the US Department of Energy, under Interagency Agreement DE-AI08-97NV12033. The purpose of this report is to interpret {sup 14}C, {delta}{sup 13}C, {sup 3}H, {delta}D and {delta}{sup 18}O isotopic compositions of <span class="hlt">pore</span> <span class="hlt">water</span> from the core of boreholes USW SD-6 and USW WT-24 in relation to sources of recharge and flow paths in the UZ at Yucca Mountain. Borehole designation USW SD-6 and USW WT-24 subsequently will be referred to as SD-6 and WT-24. The sources of recharge and flow paths are important parameters that can be used in a UZ flow model, total system performance assessment (TSPA), and the license application (LA) for the potential repository at Yucca Mountain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/160113','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/160113"><span>Use of radium isotopes to examine <span class="hlt">pore-water</span> exchange in an estuary</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Webster, I.T.; Hancock, G.J.; Murray, A.S.</p> <p>1994-12-01</p> <p>The measured distributions of four isotopes of Ra along the estuary of the Bega River are used to examine sediment-<span class="hlt">water</span> columns exchange. Ra is created in estuarine sediments by the radioactive decay of insoluble Th parents residing close to or on the surfaces of the sediment grains. Ra desorbed into the <span class="hlt">pore</span> <span class="hlt">water</span> is continuously lost to the <span class="hlt">water</span> column due to the cyclical draining and filling of the sediments by the tides. The distribution of Ra in the estuary is governed by its rate of loss from the sediments, its advection along the estuary resulting from river discharge into the estuary`s head, tidal mixing, and radioactive decay. These processes are all described in a model. Matching of model-predicted Ra concentrations with measurements allows an estimate of the effective depth in the sediments to which the <span class="hlt">pore</span> <span class="hlt">water</span> is exchanged every tidal cycle. This depth is large (15 cm), but it is shown to be reasonable for the Bega estuary. 19 refs., 11 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/90942','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/90942"><span>Meteoric-like fabrics forming in <span class="hlt">marine</span> <span class="hlt">waters</span>. Implications for the use of petrography to identify diagenetic environments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Melim, L.A.; Swart, P.K.; Maliva, R.G.</p> <p>1995-08-01</p> <p>Petrographic fabrics have long been used to identify meteoric diagnesis of carbonate sediments. However, on the basis of oxygen isotopic data, we document similar fabrics forming in <span class="hlt">marine</span> <span class="hlt">pore</span> fluids in the shallow subsurface of Great Bahama Bank. Therefore, petrographic fabrics alone are not reliable indicators of diagenetic environments, even for shallow-<span class="hlt">water</span> sediments. In our study, skeletal grainstones show two distinct diagenetic assemblages: either dissolution of aragonitic grains and minimal cementation (high-permeability intervals) or abundant blocky spar cement and neomorphism of aragonitic skeletal grains (low-permeability intervals). These <span class="hlt">marine</span>-burial fabrics are present as shallow as 110 m below sea level, well above the aragonite compensation depth, a feature that must be considered for models of diagenesis in ancient carbonate sediments. <span class="hlt">Marine</span>-burial diagenesis may be important in ancient carbonate sediments deposited in moderate <span class="hlt">water</span> depths or in shallow <span class="hlt">water</span> during rising sea level where meteoric diagenesis is suppressed. 17 refs., 5 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20062609','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20062609"><span>The radiocarbon age of calcite dissolving at the sea floor: Estimates from <span class="hlt">pore</span> <span class="hlt">water</span> data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Martin, W.R.; McNichol, A.P.; McCorkle, D.C.</p> <p>2000-04-01</p> <p>The authors measured the radiocarbon content and stable isotopic composition of <span class="hlt">pore</span> <span class="hlt">water</span> and bottom <span class="hlt">water</span> {Sigma}CO{sub 2}, sedimentary organic carbon, and CaCO{sub 3} at two sites on the Ceara Rise, one underlying bottom <span class="hlt">water</span> that is supersaturated with respect to calcite (Site B), the other underlying under saturated bottom <span class="hlt">water</span> (Site G). The results were combined with <span class="hlt">pore</span> <span class="hlt">water</span> O{sub 2}, {Sigma}CO{sub 2}, and Ca{sup 2+} profiles (Martin and Sayles, 1996) to estimate the radiocarbon content of the CaCO{sub 3} that is dissolving in the sediment mixed layer. At Site G, the CaCO{sub 3} that is dissolving in the upper 2 cm of the sediments is clearly younger (richer in {sup 14}C) than the bulk sedimentary CaCO{sub 3}, indicating that nonhomogeneous CaCO{sub 3} dissolution occurs there. The case for nonhomogeneous dissolution is much weaker at the site underlying supersaturated bottom <span class="hlt">water</span>. The results indicate that nonhomogeneous dissolution occurs in sediments underlying under saturated bottom <span class="hlt">water</span>, that the dissolution is rapid relative to the rate of homogenization of the CaCO{sub 3} in the mixed layer by bioturbation, and that the dissolution rate of CaCO{sub 3} decreases as it ages in the sediment mixed layer. The results support the hypothesis, based on solid phase analyses, that the preferential dissolution of young (i.e., radiocarbon-rich) CaCO{sub 3} leads to a pattern of increasing radiocarbon age of mixed-layer CaCO{sub 3} as the degree of under saturation of bottom <span class="hlt">water</span> increases (Keir, 1984; Broecker et al., 1991).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000GeCoA..64.1391M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000GeCoA..64.1391M"><span>The radiocarbon age of calcite dissolving at the sea floor: Estimates from <span class="hlt">pore</span> <span class="hlt">water</span> data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, W. R.; McNichol, A. P.; McCorkle, D. C.</p> <p>2000-04-01</p> <p>We measured the radiocarbon content and stable isotopic composition of <span class="hlt">pore</span> <span class="hlt">water</span> and bottom <span class="hlt">water</span> ΣCO 2, sedimentary organic carbon, and CaCO 3 at two sites on the Ceara Rise, one underlying bottom <span class="hlt">water</span> that is supersaturated with respect to calcite (Site B), the other underlying undersaturated bottom <span class="hlt">water</span> (Site G). The results were combined with <span class="hlt">pore</span> <span class="hlt">water</span> O 2, ΣCO 2, and Ca 2+ profiles (Martin and Sayles, 1996) to estimate the radiocarbon content of the CaCO 3 that is dissolving in the sediment mixed layer. At Site G, the CaCO 3 that is dissolving in the upper 2 cm of the sediments is clearly younger (richer in 14C) than the bulk sedimentary CaCO 3, indicating that nonhomogeneous CaCO 3 dissolution occurs there. The case for nonhomogeneous dissolution is much weaker at the site underlying supersaturated bottom <span class="hlt">water</span>. The results indicate that nonhomogeneous dissolution occurs in sediments underlying undersaturated bottom <span class="hlt">water</span>, that the dissolution is rapid relative to the rate of homogenization of the CaCO 3 in the mixed layer by bioturbation, and that the dissolution rate of CaCO 3 decreases as it ages in the sediment mixed layer. The results support the hypothesis, based on solid phase analyses, that the preferential dissolution of young (i.e., radiocarbon-rich) CaCO 3 leads to a pattern of increasing radiocarbon age of mixed-layer CaCO 3 as the degree of undersaturation of bottom <span class="hlt">water</span> increases (Keir, 1984; Broecker et al., 1991).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JOUC...13..911L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JOUC...13..911L"><span>An experimental study on the wave-induced <span class="hlt">pore</span> <span class="hlt">water</span> pressure change and relative influencing factors in the silty seabed</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Anlong; Luo, Xiaoqiao; Lin, Lin; Ye, Qing; Le, Chunyu</p> <p>2014-12-01</p> <p>In this study, a flume experiment was designed to investigate the characteristics of wave-induced <span class="hlt">pore</span> <span class="hlt">water</span> pressure in the soil of a silty seabed with different clay contents, soil layer buried depths and wave heights respectively. The study showed that <span class="hlt">water</span> waves propagating over silty seabed can induce significant change of <span class="hlt">pore</span> <span class="hlt">water</span> pressure, and the amplitude of <span class="hlt">pore</span> pressure depends on depth of buried soil layer, clay content and wave height, which are considered as the three influencing factors for <span class="hlt">pore</span> <span class="hlt">water</span> pressure change. The pressure will attenuate according to exponential law with increase of soil layer buried depth, and the attenuation being more rapid in those soil layers with higher clay content and greater wave height. The <span class="hlt">pore</span> pressure in silty seabed increases rapidly in the initial stage of wave action, then decreases gradually to a stable value, depending on the depth of buried soil layer, clay content and wave height. The peak value of <span class="hlt">pore</span> pressure will increase if clay content or depth of buried soil layer decreases, or wave height increases. The analysis indicated that these soils with 5% clay content and waves with higher wave height produce instability in bed easier, and that the wave energy is mostly dissipated near the surface of soils and 5% clay content in soils can prevent <span class="hlt">pore</span> pressure from dissipating immediately.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://sofia.usgs.gov/publications/ofr/97-454/','USGSPUBS'); return false;" href="http://sofia.usgs.gov/publications/ofr/97-454/"><span>Geochemistry of surface and <span class="hlt">pore</span> <span class="hlt">water</span> at USGS coring sites in wetlands of South Florida, 1994 and 1995</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Orem, William H.; Lerch, Harry E.; Rawlik, Peter</p> <p>2002-01-01</p> <p>In this report, we present preliminary data on surface and <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry from 22 sites in south Florida sampled during 1994 and 1995. These results are part of a larger study designed to evaluate the role of biogeochemical processes in sediments in the cycling of carbon, nitrogen, phosphorus, and sulfur in the south Florida ecosystem. The data are briefly discussed in regard to regional trends in the concentrations of chemical species, and general diagenetic processes in sediments. These results are part of a larger study designed to evaluate the role of biogeochemical processes in sediments in the cycling of carbon, nitrogen, phosphorus, and sulfur in the south Florida ecosystem. These elements play a crucial role in regulating organic sedimentation, nutrient dynamics, redox conditions, and the biogeochemistry of mercury in the threatened wetlands of south Florida. <span class="hlt">Pore</span> <span class="hlt">water</span> samples for chemical analyis were obtained using a piston corer/squeezer designed to avoid compression of the sediment and avoid oxidation and contamination of the <span class="hlt">pore</span> <span class="hlt">water</span> samples. Results show distinct regional trends in both surface <span class="hlt">water</span> and <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry. Most chemical species in surface and <span class="hlt">pore</span> <span class="hlt">water</span> show peak concentrations in <span class="hlt">Water</span> Conservation Area 2A, with diminishing concentrations to the south and west into <span class="hlt">Water</span> Conservation Area 3A, and Everglades National Park. The largest differences observed were for phosphate and sulfide, with concentrations in <span class="hlt">pore</span> <span class="hlt">waters</span> in <span class="hlt">Water</span> Conservation Area 2A up to 500x higher than concentrations observed in freshwater marsh areas of <span class="hlt">Water</span> Conservation Area 3A and Everglades National Park. Sites near the Hillsboro Canal in <span class="hlt">Water</span> Conservation Area 2A are heavily contaminated with both phosphorus and sulfur. <span class="hlt">Pore</span> <span class="hlt">water</span> profiles for dissolved reactive phosphate suggest that recycling of phosphorus at these contaminated sites occurs primarily in the upper 20 cm of sediment. High levels of sulfide in <span class="hlt">pore</span> <span class="hlt">water</span> in <span class="hlt">Water</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADD017854','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADD017854"><span>Compact <span class="hlt">Water</span> Jet Propulsion System for a <span class="hlt">Marine</span> Vehicle.</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p></p> <p>The invention is directed to an improved <span class="hlt">water</span> jet propulsion system for a <span class="hlt">marine</span> vehicle. The <span class="hlt">water</span> jet propulsion system of the present invention...the vehicle hull and extending internally thereof, a <span class="hlt">water</span> jet pump having an inlet end attached to the outlet end of the inlet duct, a motor for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011NatGe...4..298L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011NatGe...4..298L"><span>Methylation of inorganic mercury in polar <span class="hlt">marine</span> <span class="hlt">waters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lehnherr, Igor; St. Louis, Vincent L.; Hintelmann, Holger; Kirk, Jane L.</p> <p>2011-05-01</p> <p>Monomethylmercury is a neurotoxin that accumulates in <span class="hlt">marine</span> organisms, with serious implications for human health. The toxin is of particular concern to northern Inuit peoples, for example, whose traditional diets are composed primarily of <span class="hlt">marine</span> mammals and fish. The ultimate source of monomethylmercury to <span class="hlt">marine</span> organisms has remained uncertain, although various potential sources have been proposed, including export from coastal and deep-sea sediments and major river systems, atmospheric deposition and <span class="hlt">water</span>-column production. Here, we report results from incubation experiments in which we added isotopically labelled inorganic mercury and monomethylmercury to seawater samples collected from a range of sites in the Canadian Arctic Archipelago. Monomethylmercury formed from the methylation of inorganic mercury in all samples. Demethylation of monomethylmercury was also observed in <span class="hlt">water</span> from all sites. We determined steady-state concentrations of monomethylmercury in <span class="hlt">marine</span> <span class="hlt">waters</span> by incorporating the rate constants for monomethylmercury formation and degradation derived from these experiments into a numerical model. We estimate that the conversion of inorganic mercury to monomethylmercury in the <span class="hlt">water</span> column accounts for around 47% (+/-62%, standard deviation) of the monomethylmercury present in polar <span class="hlt">marine</span> <span class="hlt">waters</span>, with site-to-site differences in inorganic mercury and monomethylmercury levels accounting for most of the variability. We suggest that <span class="hlt">water</span>-column methylation of inorganic mercury is a significant source of monomethylmercury in pelagic <span class="hlt">marine</span> food webs in the Arctic, and possibly in the world's oceans in general.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.H21B0801F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.H21B0801F"><span>The Relationship of the Smectite-Illite Conversion to <span class="hlt">Pore</span> <span class="hlt">Water</span> Salinity Trends, Deep <span class="hlt">Water</span> Offshore Niger Delta</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fitts, T. G.; Summa, L. L.</p> <p>2002-12-01</p> <p>Petroleum exploration in the deepwater Niger Delta has produced an abundance of physical property data and geochemical information in the section from 500 to 4000m below the seafloor. These have improved our understanding of the links between diagenetic processes and changes in <span class="hlt">pore</span> fluid chemistry, and further suggest that smectite dehydration is not a major contributor to overpressure in the section. Literature data, coupled with new log, x-ray diffraction and surface area measurements, suggest that smectite and mixed-layer illite-smectite are major components of Miocene to Recent shales in key deep <span class="hlt">water</span> wells. The smectite-illite transformation is generally complete by 2000m bml, corresponding to 80-90 degrees C. Such high percentages of hydrated clays result in sediments with low shallow overburden stresses, permeabilities and thermal conductivities. Because of the large contribution of smectite interlayer <span class="hlt">water</span> to the total <span class="hlt">water</span> content, diagenetic alteration of smectite more strongly affects density and <span class="hlt">pore</span> fluid chemistry profiles here than in areas with less hydrated clay. Coincident with the conversion of smectite to illite, the total dissolved solids in the <span class="hlt">pore</span> <span class="hlt">waters</span> from several wells in the deepwater Niger Delta decrease from near seawater values at the sea floor to approximatly 10,000 ppm at 2000m bml. <span class="hlt">Pore</span> fluid composition estimates are derived primarily from log calculation of <span class="hlt">water</span> resistivity, with limited confirmation from pressure gradients in <span class="hlt">water</span> legs, and uncontaminated MDT fluid samples. There are two models that could account for the observed decrease in salinity with depth: freshwater incursion via long-distance lateral fluid flow through continuous aquifers, and release of interlayer <span class="hlt">water</span> from smectite during diagenesis. The available data suggest that release of interlayer <span class="hlt">water</span> is the most likely explanation for the salinity observations from deep <span class="hlt">water</span> Nigeria. Freshwater incursions are more likely on the shallow <span class="hlt">water</span> shelf</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17140624','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17140624"><span>Fluorescence and DOC contents of estuarine <span class="hlt">pore</span> <span class="hlt">waters</span> from colonized and non-colonized sediments: effects of sampling preservation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Otero, M; Mendonça, A; Válega, M; Santos, E B H; Pereira, E; Esteves, V I; Duarte, A</p> <p>2007-02-01</p> <p>The influence of the colonization of salt marsh sediments with Halimione portulacoides was evaluated by analysing the fluorescent dissolved organic matter (FDOM) in sediment <span class="hlt">pore</span> <span class="hlt">waters</span> from a salt marsh at different depths. Cores of sediments at colonized and non-colonized sites were collected from a coastal lagoon (Ria de Aveiro, Portugal). The DOC content of extracted <span class="hlt">pore</span> <span class="hlt">waters</span> was determined and characterized by synchronous molecular fluorescence (Deltalambda=60nm) and UV-visible spectroscopies. The common practice of freezing sediment cores for further and later chemical investigation was shown not to be an appropriate methodology of sample preservation. On the contrary, freezing of extracted and filtered <span class="hlt">pore</span> <span class="hlt">water</span> seemed not to affect either the DOC content or the fluorescence properties of <span class="hlt">pore</span> <span class="hlt">waters</span>. Two types of fluorescent substances were found in the <span class="hlt">pore</span> <span class="hlt">waters</span> spectra; one corresponding to humic-like substances and another one resembling proteins. However, major differences were found in the spectra of <span class="hlt">pore</span> <span class="hlt">waters</span> depending on both depth and the presence/absence of vegetation colonization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25965160','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25965160"><span>Soil-<span class="hlt">pore</span> <span class="hlt">water</span> distribution of silver and gold engineered nanoparticles in undisturbed soils under unsaturated conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tavares, D S; Rodrigues, S M; Cruz, N; Carvalho, C; Teixeira, T; Carvalho, L; Duarte, A C; Trindade, T; Pereira, E; Römkens, P F A M</p> <p>2015-10-01</p> <p>Release of engineered nanoparticles (ENPs) to soil is well documented but little is known on the subsequent soil-<span class="hlt">pore</span> <span class="hlt">water</span> distribution of ENPs once present in soil. In this study, the availability and mobility of silver (Ag) and gold (Au) ENPs added to agricultural soils were assessed in two separate pot experiments. <span class="hlt">Pore</span> <span class="hlt">water</span> samples collected from pots from day 1 to 45 using porous (<0.17 μm) membrane samplers suggest that both Ag and Au are retained almost completely within 24 h with less than 13% of the total added amount present in <span class="hlt">pore</span> <span class="hlt">water</span> on day 1. UV-Vis and TEM results showed that AuENPs in <span class="hlt">pore</span> <span class="hlt">water</span> were present as both homoaggregates and heteroaggregates until day 3 after which the concentration in <span class="hlt">pore</span> <span class="hlt">water</span> was too low to detect the presence of aggregates. A close relation between the concentration of Au and Fe in <span class="hlt">pore</span> <span class="hlt">water</span> suggests that the short term solubility of Au is partly controlled by natural soil colloids. Results suggest that under normal aerated soil conditions the actual availability of Ag and AuENPs is low which is relevant in view of risk assessment even though the impact of environmental conditions and soil properties on the reactivity of ENPs (and/or large ENPs aggregates) retained in the solid matrix need to be addressed further. Copyright © 2015 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-02-27/pdf/2012-4469.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-02-27/pdf/2012-4469.pdf"><span>77 FR 11401 - <span class="hlt">Marine</span> Sanitation Devices (MSDs): No Discharge Zone (NDZ) for California State <span class="hlt">Marine</span> <span class="hlt">Waters</span></span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-02-27</p> <p>...The U.S. Environmental Protection Agency (EPA) is establishing a No Discharge Zone (NDZ) for <span class="hlt">marine</span> <span class="hlt">waters</span> of the State of California for sewage discharges from: all large passenger vessels of 300 gross tons or greater; and from large oceangoing vessels of 300 gross tons or greater with available holding tank capacity or containing sewage generated while the vessel was outside of the <span class="hlt">marine</span> <span class="hlt">waters</span> of the State of California, pursuant to Section 312(f)(4)(A) of the Clean <span class="hlt">Water</span> Act (CWA), 33 U.S.C. 1322(f)(4)(A). This action is being taken in response to an April 5, 2006, application from the California State <span class="hlt">Water</span> Resources Control Board requesting establishment of this NDZ. Based on the State's application, EPA has determined that the protection and enhancement of the quality of California's <span class="hlt">marine</span> <span class="hlt">waters</span> requires the prohibition of sewage discharges from two classes of large vessels. For the purposes of today's rule, the <span class="hlt">marine</span> <span class="hlt">waters</span> of the State of California are defined as the territorial sea measured from the baseline, as determined in accordance with the Convention on the Territorial Sea and the Contiguous Zone, and extending seaward a distance of three miles and including all enclosed bays and estuaries subject to tidal influences from the Oregon border to the Mexican border. State <span class="hlt">marine</span> <span class="hlt">waters</span> extend three miles from State islands, including the Farallones and the Northern and Southern Channel Islands.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24360917','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24360917"><span>Polyethylene passive samplers to determine sediment-<span class="hlt">pore</span> <span class="hlt">water</span> distribution coefficients of persistent organic pollutants in five heavily contaminated dredged sediments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Charrasse, Benoit; Tixier, Céline; Hennebert, Pierre; Doumenq, Pierre</p> <p>2014-02-15</p> <p><span class="hlt">Pore</span> concentration and partition coefficients of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were determined in sediments from five distinct contaminated sites in France (<span class="hlt">marine</span> harbour, rivers canals and highway sedimentation tank). The assessment of the risk caused by such micropollutants requires, in most cases, the measurement of their availability. To assess this availability, low density polyethylene (LDPE) membrane samplers were exposed to these sediments under constant and low-level agitation over a period of 46 days. Freely dissolved <span class="hlt">pore</span> <span class="hlt">water</span> contaminant concentrations were estimated from the concentration at equilibrium in the LDPE membrane. The depletion of contaminants in the sediments was monitored by the use of performance reference compounds (PRCs). Marked differences in freely dissolved PAH and PCB concentrations and resulting sediment-<span class="hlt">pore</span> <span class="hlt">water</span> partition coefficients between these five sediments were observed. Data set was tested onto different empirical and mechanistic models. As final findings, triple domain sorption (a total organic carbon, black carbon and oil phase model) could model PCB data successfully whereas the best fitting for PAH partitioning was obtained by Raoult's Law model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.4449F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.4449F"><span>Functions of biological soil crusts on central European inland dunes: <span class="hlt">Water</span> repellency and <span class="hlt">pore</span> clogging influence <span class="hlt">water</span> infiltration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fischer, Thomas; Spröte, Roland; Veste, Maik; Wiehe, Wolfgang; Lange, Philipp; Bens, Oliver; Raab, Thomas; Hüttl, Reinhard F.</p> <p>2010-05-01</p> <p>Biological soil crusts play a key role for hydrological processes in many open landscapes. They seal and stabilize the topsoil and promote surface run-off. Three crust types were identified on two inland dunes in Brandenburg, North-East Germany: A natural, active dune, located in a former military training area near Lieberose, and an artificial dune, which was constructed in 2001 and which serves as a study area for geo-ecological monitoring of flora and fauna from the forefield of an opencast-mine ("Neuer Lugteich"). Both dunes consisted of Quarternary, carbonate-free, siliceous sandy substrate. Utilization of the mineral substrate at early stages of microbiotic crust development was assessed using chlorophyll concentrations, scanning electron (SEM) and optical microscopy. <span class="hlt">Water</span> repellency indices, which are an indication of surface polarity and wettability, were measured using the ethanol/<span class="hlt">water</span> microinfiltrometer method, and steady state <span class="hlt">water</span> flow was determined on the dry crusts and after 0, 300, 600, 1200 and 1800 seconds of wetting, thus allowing to follow <span class="hlt">pore</span> clogging through swelling of extracellular polymeric substances (EPS). Chlorophyll concentrations indicated early stages of crust development at both sites. In crust type 1, dominating sand grains were physically stabilized in their contact zones by accumulated organic matter and by few filamentous cyanobacteria and filamentous green algae. The <span class="hlt">pore</span> space was defined by the mineral matrix only. In crust type 2, filamentous cyanobacteria and algae partially filled in the matrix <span class="hlt">pores</span> and enmeshed sand grains. In the dry sample, the <span class="hlt">pore</span> space was dominated by crust organisms but still micropore channels, which are known to increase <span class="hlt">water</span> infiltration, were left. Crust type 3 was characterized by intense growth of filamentous and coccoid algae and cyanobacteria, and by few mosses, which covered less than 5% of the surface. Crust organisms completely utilized the substrate and clogged the <span class="hlt">pores</span> between</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GGG....17.2054P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GGG....17.2054P"><span><span class="hlt">Pore</span> <span class="hlt">water</span> chemistry reveals gradients in mineral transformation across a model basaltic hillslope</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pohlmann, Michael; Dontsova, Katerina; Root, Robert; Ruiz, Joaquin; Troch, Peter; Chorover, Jon</p> <p>2016-06-01</p> <p>The extent of weathering incongruency during soil formation from rock controls local carbon and nutrient cycling in ecosystems, as well as the evolution of hydrologic flow paths. Prior studies of basalt weathering, including those that have quantified the dynamics of well-mixed, bench-scale laboratory reactors or characterized the structure and integrated response of field systems, indicate a strong influence of system scale on weathering rate and trajectory. For example, integrated catchment response tends to produce lower weathering rates than do well mixed reactors, but the mechanisms underlying these disparities remain unclear. Here we present <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry and physical sensor data gathered during two controlled rainfall-runoff events on a large-scale convergent model hillslope mantled with 1 m uniform depth of granular basaltic porous media. The dense sampler and sensor array (1488 samplers and sensors embedded in 330 m3 of basalt) showed that rainfall-induced dissolution of basaltic glass produced supersaturation of <span class="hlt">pore</span> <span class="hlt">waters</span> with respect to multiple secondary solids including allophane, gibbsite, ferrihydrite, birnessite and calcite. The spatial distribution of saturation state was heterogeneous, suggesting an accumulation of solutes leading to precipitation of secondary solids along hydrologic flow paths. Rapid dissolution of primary silicates was widespread throughout the entire hillslope, irrespective of up-gradient flowpath length. However, coherent spatial variations in solution chemistry and saturation indices were observed in depth profiles and between distinct topographic regions of the hillslope. Colloids (110-2000 nm) enriched in iron (Fe), aluminum (Al), and phosphorus (P) were mobile in soil <span class="hlt">pore</span> <span class="hlt">waters</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.H51B1442M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.H51B1442M"><span><span class="hlt">Pore</span>-scale structure of a NAPL front during invasion into strongly and weakly <span class="hlt">water</span>-wetting sands</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Molnar, I. L.; Willson, C. S.; O'Carroll, D. M.; Gerhard, J.</p> <p>2016-12-01</p> <p>An improved understanding of the mechanisms governing Non-Aqueous Phase Liquid (NAPL) transport through porous media is critical to solving a number of important environmental problems (e.g., transport and remediation of chlorinated solvents to carbon sequestration in deep brine aquifers for long-term storage). The <span class="hlt">pore</span>-scale distribution of NAPL governs the efficiency of remedial activities and trapping processes. Understanding the <span class="hlt">pore</span>-scale distribution of NAPL during <span class="hlt">water</span> drainage and imbibition is vital to improving continuum-scale models. While these models may reasonably predict NAPL saturation, they may rely on potentially incorrect assumptions of <span class="hlt">pore</span>-scale NAPL distribution to assess relative permeability or dissolution rates. Until recently, most <span class="hlt">pore</span>-scale studies have focused on residual NAPL following <span class="hlt">water</span> imbibition with little emphasis on examining <span class="hlt">pore</span>-scale behaviour during <span class="hlt">water</span> drainage. As a result, the <span class="hlt">pore</span>-scale structure of the drainage front remains poorly understood. In addition, almost no studies have examined how wettability, a major factor impacting <span class="hlt">pore</span>-scale NAPL distribution, influences the <span class="hlt">pore</span>-scale structure of the drainage front. This study examines the <span class="hlt">pore</span>-scale distribution of a tetrachloroethylene/surfactant mixture during <span class="hlt">water</span> drainage in strongly (iron oxide) and weakly <span class="hlt">water</span>-wetting (quartz) sands. Dodecylamine was used to render quartz media weakly <span class="hlt">water</span> wetting while keeping iron oxide strongly <span class="hlt">water</span> wetting. SXCMT was employed to image the length of the front during drainage. Absorption-edge imaging was employed to segment the grain, <span class="hlt">water</span> and NAPL phases followed by extensive characterization of the segmented <span class="hlt">pore</span> network and fluid distributions. Comparing and contrasting the high resolution quartz and iron oxide datasets highlights the wettability mechanisms responsible for changes in continuum-scale flow and dissolution relationships. Specific attention was placed on examining capillary pressure as a function of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4898891','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4898891"><span>Evaluation of Bound and <span class="hlt">Pore</span> <span class="hlt">Water</span> in Cortical Bone Using Ultrashort Echo Time (UTE) Magnetic Resonance Imaging</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shao, Hongda; D'Lima, Darryl; Bydder, Graeme M; Wu, Zhihong; Du, Jiang</p> <p>2015-01-01</p> <p>Bone <span class="hlt">water</span> exists in different states with the majority bound to the organic matrix and to mineral, and a smaller fraction in ‘free’ form in the <span class="hlt">pores</span> of cortical bone. In this study we aimed to develop and evaluate ultrashort echo time (UTE) magnetic resonance imaging (MRI) techniques for assessment of T2*, T1 and concentration of collagen-bound and <span class="hlt">pore</span> <span class="hlt">water</span> in cortical bone using a 3T clinical whole-body scanner. UTE MRI together with an isotope study using tritiated and distilled <span class="hlt">water</span> (THO-H2O) exchange as well as gravimetrical analysis were performed on ten sectioned bovine bone samples. In addition, 32 human cortical bone samples were prepared for comparison between <span class="hlt">pore</span> <span class="hlt">water</span> concentration measured with UTE MRI and cortical porosity derived from micro computed tomography (μCT). A short T2* of 0.27 ± 0.03 ms and T1 of 116±6 ms were observed for collagen-bound <span class="hlt">water</span> in bovine bone. A longer T2* of 1.84 ± 0.52 ms and T1 of 527±28 ms were observed for <span class="hlt">pore</span> <span class="hlt">water</span> in bovine bone. UTE MRI measurements showed a <span class="hlt">pore</span> <span class="hlt">water</span> concentration of 4.7-5.3% by volume and collagen-bound <span class="hlt">water</span> concentration of 15.7-17.9% in bovine bone. THO-H2O exchange studies showed a <span class="hlt">pore</span> <span class="hlt">water</span> concentration of 5.9 ± 0.6% and collagen-bound <span class="hlt">water</span> concentration of 18.1 ± 2.1% in bovine bone. Gravimetrical analysis showed a <span class="hlt">pore</span> <span class="hlt">water</span> concentration of 6.3 ± 0.8% and collagen-bound <span class="hlt">water</span> concentration of 19.2 ± 3.6% in bovine bone. A mineral <span class="hlt">water</span> concentration of 9.5 ± 0.6% was derived in bovine bone with the THO-H2O exchange study. UTE measured <span class="hlt">pore</span> <span class="hlt">water</span> concentration is highly correlated (R2 = 0.72, P < 0.0001) with μCT porosity in the human cortical bone study. Both bovine and human bone studies suggest that UTE sequences could reliably measure collagen-bound and <span class="hlt">pore</span> <span class="hlt">water</span> concentration in cortical bone using a clinical scanner. PMID:26527298</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5875534','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5875534"><span>Upwelling of hydrothermal solutions through ridge flank sediments shown by <span class="hlt">pore</span> <span class="hlt">water</span> profiles</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Maris, C.R.P.; Bender, M.L.</p> <p>1982-05-07</p> <p>High calcium ion and low magnesium ion concentrations in sediment <span class="hlt">pore</span> <span class="hlt">waters</span> in cores from the Galapagos Mounds Hydrothermal Field on the flank of the Galapagos Spreading Center are believed to be due to a calcium-magnesium exchange reaction between circulating seawater and basement basalt. The nonlinearity of the calcium ions and magnesium ion gradients indicates that these discharging hydrothermal solutions on the ridge flank are upwelling at the rate of about 1 centimeter per year through the pelagic sediments of the Mounds Field and at about 20 centimeters per year through the hydrothermal mounds themselves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AdWR..107..191L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AdWR..107..191L"><span>Dynamic <span class="hlt">pore</span>-scale network model (PNM) of <span class="hlt">water</span> imbibition in porous media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, J.; McDougall, S. R.; Sorbie, K. S.</p> <p>2017-09-01</p> <p>A dynamic <span class="hlt">pore</span>-scale network model is presented which simulates 2-phase oil/<span class="hlt">water</span> displacement during <span class="hlt">water</span> imbibition by explicitly modelling intra-<span class="hlt">pore</span> dynamic bulk and film flows using a simple local model. A new dynamic switching parameter, λ, is proposed within this model which is able to simulate the competition between local capillary forces and viscous forces over a very wide range of flow conditions. This quantity (λ) determines the primary <span class="hlt">pore</span> filling mechanism during imbibition; i.e. whether the dominant force is (i) piston-like displacement under viscous forces, (ii) film swelling/collapse and snap-off due to capillary forces, or (iii) some intermediate local combination of both mechanisms. A series of 2D dynamic <span class="hlt">pore</span> network simulations is presented which shows that the λ-model can satisfactorily reproduce and explain different filling regimes of <span class="hlt">water</span> imbibition over a wide range of capillary numbers (Ca) and viscosity ratios (M). These imbibition regimes are more complex than those presented under drainage by (Lenormand et al. (1983)), since they are determined by a wider group of control parameters. Our simulations show that there is a coupling between viscous and capillary forces that is much less important in drainage. The effects of viscosity ratio during imbibition are apparent even under conditions of very slow flow (low Ca)-displacements that would normally be expected to be completely capillary dominated. This occurs as a result of the wetting films having a much greater relative mobility in the higher M cases (e.g. M = 10) thus leading to a higher level of film swelling/snap-off, resulting in local oil cluster bypassing and trapping, and hence a poorer oil recovery. This deeper coupled viscous mechanism is the underlying reason why the microscopic displacement efficiency is lower for higher M cases in <span class="hlt">water</span> imbibition processes. Additional results are presented from the dynamic model on the corresponding effluent fractional flows (fw</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70024130','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70024130"><span>Sequestration of priority pollutant PAHs from sediment <span class="hlt">pore</span> <span class="hlt">water</span> employing semipermeable membrane devices</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Williamson, K.S.; Petty, J.D.; Huckins, J.N.; Lebo, J.A.; Kaiser, E.M.</p> <p>2002-01-01</p> <p>Semipermeable membrane devices (SPMDs) were employed to sample sediment <span class="hlt">pore</span> <span class="hlt">water</span> in static exposure studies under controlled laboratory conditions using (control pond and formulated) sediments fortified with 15 priority pollutant polycyclic aromatic hydrocarbons (PPPAHs). The sediment fortification level of 750 ng/g was selected on the basis of what might be detected in a sediment sample from a contaminated area. The sampling interval consisted of 0, 4, 7, 14, and 28 days for each study. The analytical methodologies, as well as the extraction and sample cleanup procedures used in the isolation, characterization, and quantitation of 15 PPPAHs at different fortification levels in SPMDs, <span class="hlt">water</span>, and sediment were reported previously (Williamson, M.S. Thesis, University of Missouri - Columbia, USA; Williamson et al., Chemosphere (This issue - PII: S0045-6535(02)00394-6)) and used for this project. Average (mean) extraction recoveries for each PPPAH congener in each matrix are reported and discussed. No procedural blank extracts (controls) were found to contain any PPPAH residues above the method quantitation limit, therefore, no matrix interferences were detected. The focus of this publication is to demonstrate the ability to sequester environmental contaminants, specifically PPPAHs, from sediment <span class="hlt">pore</span> <span class="hlt">water</span> using SPMDs and two different types of fortified sediment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21774502','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21774502"><span>Liquid CO2 displacement of <span class="hlt">water</span> in a dual-permeability <span class="hlt">pore</span> network micromodel.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Changyong; Oostrom, Mart; Grate, Jay W; Wietsma, Thomas W; Warner, Marvin G</p> <p>2011-09-01</p> <p>Permeability contrasts exist in multilayer geological formations under consideration for carbon sequestration. To improve our understanding of heterogeneous <span class="hlt">pore</span>-scale displacements, liquid CO(2) (LCO(2))-<span class="hlt">water</span> displacement was evaluated in a <span class="hlt">pore</span> network micromodel with two distinct permeability zones. Due to the low viscosity ratio (logM = -1.1), unstable displacement occurred at all injection rates over 2 orders of magnitude. LCO(2) displaced <span class="hlt">water</span> only in the high permeability zone at low injection rates with the mechanism shifting from capillary fingering to viscous fingering with increasing flow rate. At high injection rates, LCO(2) displaced <span class="hlt">water</span> in the low permeability zone with capillary fingering as the dominant mechanism. LCO(2) saturation (S(LCO2)) as a function of injection rate was quantified using fluorescent microscopy. In all experiments, more than 50% of LCO(2) resided in the active flowpaths, and this fraction increased as displacement transitioned from capillary to viscous fingering. A continuum-scale two-phase flow model with independently determined fluid and hydraulic parameters was used to predict S(LCO2) in the dual-permeability field. Agreement with the micromodel experiments was obtained for low injection rates. However, the numerical model does not account for the unstable viscous fingering processes observed experimentally at higher rates and hence overestimated S(LCO2).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1024084','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1024084"><span>Liquid CO2 Displacement of <span class="hlt">Water</span> in a Dual-Permeability <span class="hlt">Pore</span> Network Micromodel</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhang, Changyong; Oostrom, Martinus; Grate, Jay W.; Wietsma, Thomas W.; Warner, Marvin G.</p> <p>2011-09-01</p> <p>Permeability contrasts exist in multilayer geological formations under consideration for carbon sequestration. To improve our understanding of heterogeneous <span class="hlt">pore</span>-scale displacements, liquid CO2 (LCO2) - <span class="hlt">water</span> displacement was evaluated in a <span class="hlt">pore</span> network micromodel with two distinct permeability zones. Due to the low viscosity ratio (logM = -1.1), unstable displacement occurred at all injection rates over two orders of magnitude. LCO2 displaced <span class="hlt">water</span> only in the high permeability zone at low injection rates with the mechanism shifting from capillary fingering to viscous fingering with increasing flow rate. At high injection rates, LCO2 displaced <span class="hlt">water</span> in the low permeability zone with capillary fingering as the dominant mechanism. LCO2 saturation (SLCO2) as a function of injection rate was quantified using fluorescent microscopy. In all experiments, more than 50% of LCO2 resided in the active flowpaths, and this fraction increased as displacement transitioned from capillary to viscous fingering. A continuum-scale two-phase flow model with independently determined fluid and hydraulic parameters was used to predict SLCO2 in the dual-permeability field. Agreement with the micromodel experiments was obtained for low injection rates. However, the numerical model does not account for the unstable viscous fingering processes observed experimentally at higher rates and hence overestimated SLCO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20075700','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20075700"><span>Behavior of trace metals in the sediment <span class="hlt">pore</span> <span class="hlt">waters</span> of intertidal mudflats of a tropical wetland</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yu, K.T.; Lam, M.H.W.; Yen, Y.F.; Leung, A.P.K.</p> <p>2000-03-01</p> <p>Vertical profiles of dissolved Cd, Cr, Cu, Pb, Zn, Fe, and Mn in the sediment <span class="hlt">pore</span> <span class="hlt">waters</span> of the intertidal mudflats of the Mai Po and Inner Deep Bay Ramsar Site of Hong Kong, People's Republic of China, were measured using the polyacrylamide gel diffusive equilibration thin film (DET) technique. The ranges of concentrations of dissolved Cd, Cr, Cu, Pb, Zn, Fe, and Mn in the <span class="hlt">pore</span> <span class="hlt">water</span> of the top 0 to 20 cm of sediment were 2.2 to 10.0 nM, 346.0 to 950.0 nM 243.8 to 454.8 nM, 23.2 to 51.2 nM, 39.8 to 249.5 {micro}M, and 13.4 to 20.7 {micro}M, respectively. Enrichment of these trace metals was observed in the upper 0- to 7-cm layer. Profiles of conditional distribution coefficient, log(K{sub D}), of the trace metals and results of multiple regression analysis have revealed that reduction of Mn (hydrous) oxides was the major remobilization mechanism for Cd, Cr, Cu, Pb, and Zn in the mudflats. Benthic diffusive fluxes of these trace metals from the mudflats were also estimated on the basis of the concentration gradients of trace metals between surface sediments and the overlying <span class="hlt">water</span> column. The magnitude of the estimated diffusive fluxes followed the order Zn > Cr > Cu > Pb > Cd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780062895&hterms=Water+buffalo&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DWater%2Bbuffalo','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780062895&hterms=Water+buffalo&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DWater%2Bbuffalo"><span><span class="hlt">Water</span> vapor weathering of Taurus-Littrow orange soil - A <span class="hlt">pore</span>-structure analysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cadenhead, D. A.; Mikhail, R. S.</p> <p>1975-01-01</p> <p>A <span class="hlt">pore</span>-volume analysis was performed on <span class="hlt">water</span> vapor adsorption data previously obtained on a fresh sample of Taurus-Littrow orange soil, and the analysis was repeated on the same sample after its exposure to moist air for a period of approximately six months. The results indicate that exposure of an outgassed sample to high relative pressures of <span class="hlt">water</span> vapor can result in the formation of substantial micropore structure, the precise amount being dependent on the sample pretreatment, particularly the outgassing temperature. Micropore formation is explained in terms of <span class="hlt">water</span> penetration into surface defects. In contrast, long-term exposure to moist air at low relative pressures appears to reverse the process with the elimination of micropores and enlargement of mesopores possibly through surface diffusion of metastable adsorbent material. The results are considered with reference to the storage of lunar samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.H53B1036V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.H53B1036V"><span>Solute contributions from precipitation to the compositions of soil <span class="hlt">waters</span> in a <span class="hlt">marine</span> terrace chronosequence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vivit, D. V.; White, A. F.; Bullen, T. D.; Fitzpatrick, J.</p> <p>2010-12-01</p> <p>Solute loading of soil <span class="hlt">waters</span> by rainfall together with evapo-transpiration can increase the concentrations of various dissolved constituents. This process complicates the modeling of saturation states for the different mineral phases in the soil profile that are products of the weathering of primary minerals found in the original granitic source material. The estimation of true rates of regolith weathering due to CO2 drawdown at temperate hydrogeological sites requires having soil <span class="hlt">pore</span> <span class="hlt">water</span> solute concentration data which have been corrected for solute inputs from precipitation before proceeding with chemical weathering calculations. As part of a chemical weathering study of a coastal <span class="hlt">marine</span> terrace chronosequence located in the vicinity of Wilder Ranch State Park, Santa Cruz County, CA, bulk samplers and automatic precipitation-event samplers installed at a range of sites enabled us to determine elemental concentrations and isotopic compositions of rainfall solutes which influence the overall compositions of the <span class="hlt">pore</span> <span class="hlt">waters</span>. Variations in rain sample chemistry (mole-ratio data using Na, Mg, Ca, Cl and SO4) correlated with precipitation intensity result from solute inputs contributed by <span class="hlt">marine</span> and terrestrial aerosols. Higher strontium-isotope ratios (87Sr/86Sr), which point to radiogenic dust sources, occur in rain <span class="hlt">water</span> collected in the fall at the beginning of the rainy season while lower ratio values indicating <span class="hlt">marine</span> aerosol sources appear in winter and spring samples. Use of the NOAA HYSPLIT particle-tracking program for computing the chronological progression of storm tracks during precipitation events could show the development of solute levels in rain. Subsequently, the installation of wind sensors along with the automatic rain collectors afforded the capability of correlating high resolution wind-speed and wind-direction data with changing compositions of rain samples collected at fixed-time intervals during storm events. Wind data show that wind</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25427672','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25427672"><span><span class="hlt">Water</span> transport in the nano-<span class="hlt">pore</span> of the calcium silicate phase: reactivity, structure and dynamics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hou, Dongshuai; Li, Zongjin; Zhao, Tiejun; Zhang, Peng</p> <p>2015-01-14</p> <p>Reactive force field molecular dynamics was utilized to simulate the reactivity, structure and dynamics of <span class="hlt">water</span> molecules confined in calcium-silicate-hydrate (C-S-H) nano-<span class="hlt">pores</span> of 4.5 nm width. Due to the highly reactive C-S-H surface, hydrolytic reactions occur in the solid-liquid interfacial zone, and partially surface adsorbed <span class="hlt">water</span> molecules transforming into the Si-OH and Ca-OH groups are strongly embedded in the C-S-H structure. Due to the electronic charge difference, the silicate and calcium hydroxyl groups have binomial distributions of the dipolar moment and <span class="hlt">water</span> orientation. While Ca-OH contributes to the Ow-downward orientation, the ONB atoms in the silicate chains prefer to accept H-bonds from the surface <span class="hlt">water</span> molecules. Furthermore, the defective silicate chains and solvated Caw atoms near the surface contribute to the glassy nature of the surface <span class="hlt">water</span> molecules, with large packing density, pronounced orientation preference, and distorted organization. The stable H-bonds connected with the Ca-OH and Si-OH groups also restrict the mobility of the surface <span class="hlt">water</span> molecules. The significant reduction of the diffusion coefficient matches well with the experimental results obtained by NMR, QENS and PCFR techniques. Upon increasing the distance from the channel, the structural and dynamic behavior of the <span class="hlt">water</span> molecules varies and gradually translates into bulk <span class="hlt">water</span> properties at distances of 10-15 Å from the liquid-solid interface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3488140','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3488140"><span>Deuterium nuclear magnetic resonance unambiguously quantifies <span class="hlt">pore</span> and collagen-bound <span class="hlt">water</span> in cortical bone</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ong, Henry H.; Wright, Alexander C.; Wehrli, Felix W.</p> <p>2012-01-01</p> <p>Bone <span class="hlt">water</span> (BW) plays a pivotal role in nutrient transport and conferring bone with its viscoelastic mechanical properties. BW is partitioned between the <span class="hlt">pore</span> spaces of the Haversian and lacuno-canalicular system, and <span class="hlt">water</span> predominantly bound to the matrix proteins (essentially collagen). The general model of BW is that the former predominantly experiences fast isotropic molecular reorientation, whereas <span class="hlt">water</span> in the bone matrix undergoes slower anisotropic rotational diffusion. Here, we provide direct evidence for the correctness of this model and show that unambiguous quantification in situ of these two functionally and dynamically different BW fractions is possible. The approach chosen relies on nuclear magnetic resonance (NMR) of deuterium (2H) that unambiguously separates and quantifies the two fractions on the basis of their distinguishing microdynamic properties. Twenty-four specimens of the human tibial cortex from six donors (3 male, 3 female, ages 27-83 years) were cored and 2H spectra recorded at 62 MHz (9.4 Tesla) on a Bruker Instruments DMX 400 spectrometer after exchange of native BW with 2H2O. Spectra consisted of a doublet signal resulting from quadrupole interaction of <span class="hlt">water</span> bound to collagen. Doublet splittings were found to depend on the orientation of the osteonal axis with respect to the magnetic field direction (8.2 and 4.3 kHz for parallel and perpendicular orientation, respectively). In contrast, the isotropically reorienting <span class="hlt">pore</span>-resident <span class="hlt">water</span> yielded a single resonance line superimposed on the doublet. Nulling of the singlet resonance allowed separation of the two fractions. The results indicate that in human cortical bone 60-80% of detectable BW is collagen-bound. Porosity determined as the difference between total BW and collagen bound <span class="hlt">water</span> fraction was found to strongly parallel μCT based measurements (R2 = 0.91). Our method provides means for direct validation of emerging relaxation-based measurements of cortical bone porosity by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26266899','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26266899"><span>Occurrence and significance of polychlorinated biphenyls in <span class="hlt">water</span>, sediment <span class="hlt">pore</span> <span class="hlt">water</span> and surface sediments of Umgeni River, KwaZulu-Natal, South Africa.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gakuba, Emmanuel; Moodley, Brenda; Ndungu, Patrick; Birungi, Grace</p> <p>2015-09-01</p> <p>The Umgeni River is one of the main sources of <span class="hlt">water</span> in KwaZulu-Natal, South Africa; however; there is currently a lack of information on the presence and distribution of polychlorinated biphenyls (PCBs) in its sediment, sediment <span class="hlt">pore</span> <span class="hlt">water</span> and surface <span class="hlt">water</span>. This study aims to determine the occurrence and significance of selected PCBs in the surface <span class="hlt">water</span>, sediment <span class="hlt">pore</span> <span class="hlt">water</span> and surface sediment samples from the Umgeni River. Liquid-liquid and soxhlet extractions were used for <span class="hlt">water</span> or <span class="hlt">pore</span> <span class="hlt">water</span>, and sediments, respectively. Extracts were cleaned up using a florisil column and analysed by gas chromatography-mass spectrometry. The total concentrations of eight polychlorinated biphenyls were 6.91-21.69 ng/mL, 40.67-252.30 ng/mL and 102.60-427.80 ng/g (dry weight), in unfiltered surface <span class="hlt">water</span>, unfiltered sediment <span class="hlt">pore</span> <span class="hlt">water</span> and surface sediments, respectively. The percentage contributions of various matrices were 4, 36 and 60 % for unfiltered surface <span class="hlt">water</span>, unfiltered <span class="hlt">pore</span> <span class="hlt">water</span> and sediment, respectively. The highest concentrations of PCBs were found in <span class="hlt">water</span>, <span class="hlt">pore</span> <span class="hlt">water</span> and sediment collected from sampling sites close to the Northern Wastewater Treatment Works. The highest chlorinated biphenyl, PCB 180, was the most abundant at almost all sampling sites. To our knowledge, this is the first report on occurrence of polychlorinated biphenyls in the Umgeni River <span class="hlt">water</span>, <span class="hlt">pore</span> <span class="hlt">water</span> and sediment system and our results provide valuable information regarding the partitioning of the PCBs between the <span class="hlt">water</span> and sediment systems as well as the organic chemical quality of the <span class="hlt">water</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4824874','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4824874"><span>Praziquantel degradation in <span class="hlt">marine</span> aquarium <span class="hlt">water</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dawson, Matthew R.; Ellis, Helen; Stamper, M. Andrew</p> <p>2016-01-01</p> <p>Praziquantel (PZQ) is a drug commonly utilized to treat both human schistosomiasis and some parasitic infections and infestations in animals. In the aquarium industry, PZQ can be administered in a “bath” to treat the presence of ectoparasites on both the gills and skin of fish and elasmobranchs. In order to fully treat an infestation, the bath treatment has to maintain therapeutic levels of PZQ over a period of days or weeks. It has long been assumed that, once administered, PZQ is stable in a <span class="hlt">marine</span> environment throughout the treatment interval and must be mechanically removed, but no controlled experiments have been conducted to validate that claim. This study aimed to determine if PZQ would break down naturally within a <span class="hlt">marine</span> aquarium below its 2 ppm therapeutic level during a typical 30-day treatment: and if so, does the presence of fish or the elimination of all living biological material impact the degradation of PZQ? Three 650 L <span class="hlt">marine</span> aquarium systems, each containing 12 fish (French grunts: Haemulon flavolineatum), and three 650 L <span class="hlt">marine</span> aquariums each containing no fish were treated with PZQ (2 ppm) and concentrations were measured daily for 30 days. After one round of treatment, the PZQ was no longer detectable in any system after 8 (±1) days. The subsequent two PZQ treatments yielded even faster PZQ breakdown (non-detectable after 2 days and 2 ± 1 day, respectively) with slight variations between systems. Linear mixed effects models of the data indicate that day and trial most impact PZQ degradation, while the presence of fish was not a factor in the best-fit models. In a completely sterilized <span class="hlt">marine</span> system (0.5 L) PZQ concentration remained unchanged over 15 days, suggesting that PZQ may be stable in a <span class="hlt">marine</span> system during this time period. The degradation observed in non-sterile <span class="hlt">marine</span> systems in this study may be microbial in nature. This work should be taken into consideration when providing PZQ bath treatments to <span class="hlt">marine</span> animals to ensure</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27069797','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27069797"><span>Praziquantel degradation in <span class="hlt">marine</span> aquarium <span class="hlt">water</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thomas, Amber; Dawson, Matthew R; Ellis, Helen; Stamper, M Andrew</p> <p>2016-01-01</p> <p>Praziquantel (PZQ) is a drug commonly utilized to treat both human schistosomiasis and some parasitic infections and infestations in animals. In the aquarium industry, PZQ can be administered in a "bath" to treat the presence of ectoparasites on both the gills and skin of fish and elasmobranchs. In order to fully treat an infestation, the bath treatment has to maintain therapeutic levels of PZQ over a period of days or weeks. It has long been assumed that, once administered, PZQ is stable in a <span class="hlt">marine</span> environment throughout the treatment interval and must be mechanically removed, but no controlled experiments have been conducted to validate that claim. This study aimed to determine if PZQ would break down naturally within a <span class="hlt">marine</span> aquarium below its 2 ppm therapeutic level during a typical 30-day treatment: and if so, does the presence of fish or the elimination of all living biological material impact the degradation of PZQ? Three 650 L <span class="hlt">marine</span> aquarium systems, each containing 12 fish (French grunts: Haemulon flavolineatum), and three 650 L <span class="hlt">marine</span> aquariums each containing no fish were treated with PZQ (2 ppm) and concentrations were measured daily for 30 days. After one round of treatment, the PZQ was no longer detectable in any system after 8 (±1) days. The subsequent two PZQ treatments yielded even faster PZQ breakdown (non-detectable after 2 days and 2 ± 1 day, respectively) with slight variations between systems. Linear mixed effects models of the data indicate that day and trial most impact PZQ degradation, while the presence of fish was not a factor in the best-fit models. In a completely sterilized <span class="hlt">marine</span> system (0.5 L) PZQ concentration remained unchanged over 15 days, suggesting that PZQ may be stable in a <span class="hlt">marine</span> system during this time period. The degradation observed in non-sterile <span class="hlt">marine</span> systems in this study may be microbial in nature. This work should be taken into consideration when providing PZQ bath treatments to <span class="hlt">marine</span> animals to ensure maximum</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/355592','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/355592"><span>Toxicity identification evaluation of metal-contaminated sediments using an artificial <span class="hlt">pore</span> <span class="hlt">water</span> containing dissolved organic carbons</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Boucher, A.M.; Watzin, M.C.</p> <p>1999-03-01</p> <p>Recent investigations of sediment-associated pollutants in Lake Champlain indicated significant contamination with As, Mn, and Ni in Outer Malletts Bay, Vermont, US. Ceriodaphnia dubia exposed to sediment <span class="hlt">pore</span> <span class="hlt">water</span> from several sites in Outer Malletts Bay showed repeatable, acute mortality at only one site. A toxicity identification evaluation (TIE) was conducted on <span class="hlt">pore</span> <span class="hlt">water</span> to determine the contaminants causing mortality at this site. Unlike most TIE applications, the dilution <span class="hlt">water</span> used in these tests was formulated to match the hardness, alkalinity, pH, conductivity, and dissolved organic carbon content of the <span class="hlt">pore</span> <span class="hlt">water</span>. Results from phase 1 of the TIE indicated that divalent metals may be responsible for toxicity. Phase 2 results revealed levels of Mn above LC50 values. Spiking experiments employed in phase 3 confirmed Mn as the principal toxicant in sediment <span class="hlt">pore</span> <span class="hlt">water</span>. The formulated <span class="hlt">pore</span> <span class="hlt">water</span> worked well and helped ensure that toxicant behavior was influenced primarily by each TIE manipulation and not by physical and chemical differences between the dilution and site <span class="hlt">water</span>. Although the Mn toxicity at this site may be the result of its unique geomorphology, this situation underscores the need to look broadly for potential toxicants when evaluating contaminated sites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25569179','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25569179"><span>Chabazite: stable cation-exchanger in hyper alkaline concrete <span class="hlt">pore</span> <span class="hlt">water</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Van Tendeloo, Leen; Wangermez, Wauter; Kurttepeli, Mert; de Blochouse, Benny; Bals, Sara; Van Tendeloo, Gustaaf; Martens, Johan A; Maes, André; Kirschhock, Christine E A; Breynaert, Eric</p> <p>2015-02-17</p> <p>To avoid impact on the environment, facilities for permanent disposal of hazardous waste adopt multibarrier design schemes. As the primary barrier very often consists of cement-based materials, two distinct aspects are essential for the selection of suitable complementary barriers: (1) selective sorption of the contaminants in the repository and (2) long-term chemical stability in hyperalkaline concrete-derived media. A multidisciplinary approach combining experimental strategies from environmental chemistry and materials science is therefore essential to provide a reliable assessment of potential candidate materials. Chabazite is typically synthesized in 1 M KOH solutions but also crystallizes in simulated young cement <span class="hlt">pore</span> <span class="hlt">water</span>, a pH 13 aqueous solution mainly containing K(+) and Na(+) cations. Its formation and stability in this medium was evaluated as a function of temperature (60 and 85 °C) over a timeframe of more than 2 years and was also asessed from a mechanistic point of view. Chabazite demonstrates excellent cation-exchange properties in simulated young cement <span class="hlt">pore</span> <span class="hlt">water</span>. Comparison of its Cs(+) cation exchange properties at pH 8 and pH 13 unexpectedly demonstrated an increase of the KD with increasing pH. The combined results identify chabazite as a valid candidate for inclusion in engineered barriers for concrete-based waste disposal.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/477292','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/477292"><span>Geochemical properties of bentonite <span class="hlt">pore</span> <span class="hlt">water</span> in high-level-waste repository condition</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ohe, Toshiaki; Tsukamoto, Masaki</p> <p>1997-04-01</p> <p>The chemically favorable nature of bentonite <span class="hlt">pore</span> <span class="hlt">water</span> is clarified by the PHREEQE geochemical simulation code. Bentonite is viewed as a candidate buffer material for a high-level-waste repository, and bentonite`s <span class="hlt">pore</span> <span class="hlt">water</span> chemistry is expected to result in a reduced Eh and weak alkaline pH region. Pyrite (Fe{sub 2}S), initially contained in bentonite, alters to magnetite (Fe{sub 3}O{sub 4}), and this redox couple reaction controls the oxidation reduction potential. A mild alkaline pH condition is produced mainly by an ion exchange reaction between the sodium in bentonite and the protons in the solution. A geochemical simulation of the ion exchange reactions and the pyrite-magnetite alteration suggests that a favorable chemical condition would exist during the waste glass dissolution and indicates that the Ph and the Eh values are {minus}7.5 to {minus}9.4 and {minus}450 to {minus}320 mV, respectively, when the granitic groundwater intrudes into the compacted bentonite in the repository.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22764500','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22764500"><span>Trophic cascade induced by molluscivore predator alters <span class="hlt">pore-water</span> biogeochemistry via competitive release of prey.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>van Gils, Jan A; van der Geest, Matthijs; Jansen, Erik J; Govers, Laura L; de Fouw, Jimmy; Piersma, Theunis</p> <p>2012-05-01</p> <p>Effects of predation may cascade down the food web. By alleviating interspecific competition among prey, predators may promote biodiversity, but the precise mechanisms of how predators alter competition have remained elusive. Here we report on a predator-exclosure experiment carried out in a tropical intertidal ecosystem, providing evidence for a three-level trophic cascade induced by predation by molluscivore Red Knots (Calidris canutus) that affects <span class="hlt">pore</span> <span class="hlt">water</span> biogeochemistry. In the exclosures the knots' favorite prey (Dosinia isocardia) became dominant and reduced the individual growth rate in an alternative prey (Loripes lucinalis). Dosinia, a suspension feeder, consumes suspended particulate organic matter (POM), whereas Loripes is a facultative mixotroph, partly living on metabolites produced by sulfur-oxidizing chemoautotrophic bacteria, but also consuming suspended POM. Reduced sulfide concentrations in the exclosures suggest that, without predation on Dosinia, stronger competition for suspended POM forces Loripes to rely on energy produced by endosymbiotic bacteria, thus leading to an enhanced uptake of sulfide from the surrounding <span class="hlt">pore</span> <span class="hlt">water</span>. As sulfide is toxic to most organisms, this competition-induced diet shift by Loripes may detoxify the environment, which in turn may facilitate other species. The inference that predators affect the toxicity of their environment via a multi-level trophic cascade is novel, but we believe it may be a general phenomenon in detritus-based ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1210970R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1210970R"><span><span class="hlt">Pore</span> <span class="hlt">water</span> pressure variations in Subpermafrost groundwater : Numerical modeling compared with experimental modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rivière, Agnès.; Goncalves, Julio; Jost, Anne; Font, Marianne</p> <p>2010-05-01</p> <p>Development and degradation of permafrost directly affect numerous hydrogeological processes such as thermal regime, exchange between river and groundwater, groundwater flows patterns and groundwater recharge (Michel, 1994). Groundwater in permafrost area is subdivided into two zones: suprapermafrost and subpermafrost which are separated by permafrost. As a result of the volumetric expansion of <span class="hlt">water</span> upon freezing and assuming ice lenses and frost heave do not form freezing in a saturated aquifer, the progressive formation of permafrost leads to the pressurization of the subpermafrost groundwater (Wang, 2006). Therefore disappearance or aggradation of permafrost modifies the confined or unconfined state of subpermafrost groundwater. Our study focuses on modifications of <span class="hlt">pore</span> <span class="hlt">water</span> pressure of subpermafrost groundwater which could appear during thawing and freezing of soil. Numerical simulation allows elucidation of some of these processes. Our numerical model accounts for phase changes for coupled heat transport and variably saturated flow involving cycles of freezing and thawing. The flow model is a combination of a one-dimensional channel flow model which uses Manning-Strickler equation and a two-dimensional vertically groundwater flow model using Richards equation. Numerical simulation of heat transport consisted in a two dimensional model accounting for the effects of latent heat of phase change of <span class="hlt">water</span> associated with melting/freezing cycles which incorporated the advection-diffusion equation describing heat-transfer in porous media. The change of hydraulic conductivity and thermal conductivity are considered by our numerical model. The model was evaluated by comparing predictions with data from laboratory freezing experiments. Experimental design was undertaken at the Laboratory M2C (Univesité de Caen-Basse Normandie, CNRS, France). The device consisted of a Plexiglas box insulated on all sides except on the top. Precipitation and ambient temperature are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.H21B0837V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.H21B0837V"><span>Solute contributions from precipitation to the compositions of soil <span class="hlt">waters</span> in a <span class="hlt">marine</span> terrace chronosequence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vivit, D. V.; White, A. F.; Bullen, T. D.; Fitzpatrick, J.</p> <p>2009-12-01</p> <p>Solute loading of soil <span class="hlt">waters</span> by rainfall together with evapo-transpiration can increase the concentrations of various dissolved constituents. This process complicates the modeling of saturation states for the different mineral phases in the soil profile that are products of the weathering of primary minerals in the original granitic source material. The estimation of true rates of regolith weathering due to CO2 drawdown at temperate hydrogeological sites requires having soil <span class="hlt">pore</span> <span class="hlt">water</span> solute concentration data which have been corrected for solute inputs from precipitation before proceeding with chemical weathering calculations. As part of a chemical weathering study of a coastal <span class="hlt">marine</span> terrace chronosequence located in the vicinity of Wilder Ranch State Park, Santa Cruz County, CA, bulk samplers and automatic precipitation-event samplers were used at a range of sites to determine elemental concentrations as well as isotopic compositions of rainfall solutes which influence the overall compositions of the <span class="hlt">pore</span> <span class="hlt">waters</span>. Variations in rain sample chemistry correlated with precipitation intensity (see Fig. 1) are a result of solute inputs from aerosols of <span class="hlt">marine</span> and terrestrial origins. Higher isotope ratios (87Sr/86Sr), which point to radiogenic dust sources, were found in rain collected in the fall at the beginning of the rainy season while lower ratio values indicating <span class="hlt">marine</span> aerosol effects were seen in winter and spring samples. To further understand the development of solute levels in rain, the NOAA HYSPLIT particle-tracking program was used to follow the chronological progression of storm tracks during precipitation events. Subsequently, wind sensors along with the automatic rain collectors were installed in an effort to correlate high resolution wind-speed and wind-direction data with changing compositions of rain samples collected at fixed-time intervals during storm events. Wind data show that wind directions during periods of rainfall generally deviate from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020892','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020892"><span>Changes in14c activity over time during vacuum distillation of carbon from rock <span class="hlt">pore</span> <span class="hlt">water</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Davidson, G.R.; Yang, I.C.</p> <p>1999-01-01</p> <p>The radiocarbon activity of carbon collected by vacuum distillation from a single partially saturated tuff began to decline after approximately 60% of the <span class="hlt">water</span> and carbon had been extracted. Disproportionate changes in 14C activity and ??13C during distillation rule out simple isotopic fractionation as a causative explanation. Additional phenomena such as matrix diffusion and ion exclusion in micropores may play a role in altering the isotopic value of extracted carbon, but neither can fully account for the observed changes. The most plausible explanation is that distillation recovers carbon from an adsorbed phase that is depleted in 14C relative to DIC in the bulk <span class="hlt">pore</span> <span class="hlt">water</span>. ?? 1999 by the Arizona Board of Regents on behalf of the University of Arizona.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28538189','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28538189"><span>Evaluation of methods to sample fecal indicator bacteria in foreshore sand and <span class="hlt">pore</span> <span class="hlt">water</span> at freshwater beaches.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vogel, Laura J; Edge, Thomas A; O'Carroll, Denis M; Solo-Gabriele, Helena M; Kushnir, Caitlin S E; Robinson, Clare E</p> <p>2017-09-15</p> <p>Fecal indicator bacteria (FIB) are known to accumulate in foreshore beach sand and <span class="hlt">pore</span> <span class="hlt">water</span> (referred to as foreshore reservoir) where they act as a non-point source for contaminating adjacent surface <span class="hlt">waters</span>. While guidelines exist for sampling surface <span class="hlt">waters</span> at recreational beaches, there is no widely-accepted method to collect sand/sediment or <span class="hlt">pore</span> <span class="hlt">water</span> samples for FIB enumeration. The effect of different sampling strategies in quantifying the abundance of FIB in the foreshore reservoir is unclear. Sampling was conducted at six freshwater beaches with different sand types to evaluate sampling methods for characterizing the abundance of E. coli in the foreshore reservoir as well as the partitioning of E. coli between different components in the foreshore reservoir (<span class="hlt">pore</span> <span class="hlt">water</span>, saturated sand, unsaturated sand). Methods were evaluated for collection of <span class="hlt">pore</span> <span class="hlt">water</span> (drive point, shovel, and careful excavation), unsaturated sand (top 1 cm, top 5 cm), and saturated sand (sediment core, shovel, and careful excavation). Ankle-depth surface <span class="hlt">water</span> samples were also collected for comparison. <span class="hlt">Pore</span> <span class="hlt">water</span> sampled with a shovel resulted in the highest observed E. coli concentrations (only statistically significant at fine sand beaches) and lowest variability compared to other sampling methods. Collection of the top 1 cm of unsaturated sand resulted in higher and more variable concentrations than the top 5 cm of sand. There were no statistical differences in E. coli concentrations when using different methods to sample the saturated sand. Overall, the unsaturated sand had the highest amount of E. coli when compared to saturated sand and <span class="hlt">pore</span> <span class="hlt">water</span> (considered on a bulk volumetric basis). The findings presented will help determine the appropriate sampling strategy for characterizing FIB abundance in the foreshore reservoir as a means of predicting its potential impact on nearshore surface <span class="hlt">water</span> quality and public health risk. Copyright © 2017 Elsevier Ltd. All rights</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890049512&hterms=results+top&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dresults%2Btop','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890049512&hterms=results+top&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dresults%2Btop"><span>Cloud top liquid <span class="hlt">water</span> from lidar observations of <span class="hlt">marine</span> stratocumulus</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Spinhirne, J. D.; Boers, R.; Hart, W. D.</p> <p>1989-01-01</p> <p><span class="hlt">Marine</span> stratus clouds were simultaneously observed by nadir Nd:YAG lidar measurements and in situ cloud physics measurements. A procedure was applied to derive the two-dimensional vertical cross section of the liquid <span class="hlt">water</span> from within the cloud top lidar observations. A comparison to direct in-cloud liquid <span class="hlt">water</span> observations gave good results. The liquid <span class="hlt">water</span> retrieval was limited to an effective optical depth of 1.5. The true cloud optical thickness was also obtained from the retrieval procedure to a corresponding limit of 3.8. The optical thickness of the observed <span class="hlt">marine</span> stratus clouds was predominantly below 3.0.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4507585','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4507585"><span>Investigation of Two Novel Approaches for Detection of Sulfate Ion and Methane Dissolved in Sediment <span class="hlt">Pore</span> <span class="hlt">Water</span> Using Raman Spectroscopy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Du, Zengfeng; Chen, Jing; Ye, Wangquan; Guo, Jinjia; Zhang, Xin; Zheng, Ronger</p> <p>2015-01-01</p> <p>The levels of dissolved sulfate and methane are crucial indicators in the geochemical analysis of <span class="hlt">pore</span> <span class="hlt">water</span>. Compositional analysis of <span class="hlt">pore</span> <span class="hlt">water</span> samples obtained from sea trials was conducted using Raman spectroscopy. It was found that the concentration of SO42− in <span class="hlt">pore</span> <span class="hlt">water</span> samples decreases as the depth increases, while the expected Raman signal of methane has not been observed. A possible reason for this is that the methane escaped after sampling and the remaining concentration of methane is too low to be detected. To find more effective ways to analyze the composition of <span class="hlt">pore</span> <span class="hlt">water</span>, two novel approaches are proposed. One is based on Liquid Core Optical Fiber (LCOF) for detection of SO42−. The other one is an enrichment process for the detection of CH4. With the aid of LCOF, the Raman signal of SO42− is found to be enhanced over 10 times compared to that obtained by a conventional Raman setup. The enrichment process is also found to be effective in the investigation to the prepared sample of methane dissolved in <span class="hlt">water</span>. By CCl4 extraction, methane at a concentration below 1.14 mmol/L has been detected by conventional Raman spectroscopy. All the obtained results suggest that the approach proposed in this paper has great potential to be developed as a sensor for SO42− and CH4 detection in <span class="hlt">pore</span> <span class="hlt">water</span>. PMID:26016919</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/wri/1993/4144/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/wri/1993/4144/report.pdf"><span><span class="hlt">Pore-water</span> extraction from unsaturated tuff by triaxial and one-dimensional compression methods, Nevada Test Site, Nevada</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Mower, Timothy E.; Higgins, Jerry D.; Yang, In C.; Peters, Charles A.</p> <p>1994-01-01</p> <p>Study of the hydrologic system at Yucca Mountain, Nevada, requires the extraction of <span class="hlt">pore-water</span> samples from welded and nonwelded, unsaturated tuffs. Two compression methods (triaxial compression and one-dimensional compression) were examined to develop a repeatable extraction technique and to investigate the effects of the extraction method on the original <span class="hlt">pore</span>-fluid composition. A commercially available triaxial cell was modified to collect <span class="hlt">pore</span> <span class="hlt">water</span> expelled from tuff cores. The triaxial cell applied a maximum axial stress of 193 MPa and a maximum confining stress of 68 MPa. Results obtained from triaxial compression testing indicated that <span class="hlt">pore-water</span> samples could be obtained from nonwelded tuff cores that had initial moisture contents as small as 13 percent (by weight of dry soil). Injection of nitrogen gas while the test core was held at the maximum axial stress caused expulsion of additional <span class="hlt">pore</span> <span class="hlt">water</span> and reduced the required initial moisture content from 13 to 11 percent. Experimental calculations, together with experience gained from testing moderately welded tuff cores, indicated that the triaxial cell used in this study could not apply adequate axial or confining stress to expel <span class="hlt">pore</span> <span class="hlt">water</span> from cores of densely welded tuffs. This concern led to the design, fabrication, and testing of a one-dimensional compression cell. The one-dimensional compression cell used in this study was constructed from hardened 4340-alloy and nickel-alloy steels and could apply a maximum axial stress of 552 MPa. The major components of the device include a corpus ring and sample sleeve to confine the sample, a piston and base platen to apply axial load, and drainage plates to transmit expelled <span class="hlt">water</span> from the test core out of the cell. One-dimensional compression extracted <span class="hlt">pore</span> <span class="hlt">water</span> from nonwelded tuff cores that had initial moisture contents as small as 7.6 percent; <span class="hlt">pore</span> <span class="hlt">water</span> was expelled from densely welded tuff cores that had initial moisture contents as small as 7</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.C53A0551R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.C53A0551R"><span>A combined experimental and numerical study of <span class="hlt">pore</span> <span class="hlt">water</span> pressure variations in sub-permafrost groundwater</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rivière, A.; Anne, J.; Goncalves, J.</p> <p>2013-12-01</p> <p>The past few decades have seen a rapid development and progress in research on past and current hydrologic impacts of permafrost evolution. In permafrost area, groundwater is subdivided into two zones: supra-permafrost and sub-permafrost which are separated by permafrost. Knowledge of the sub-permafrost aquifers is often lacking due to the difficulty to access those systems. The few available data show that this aquifers are generally artesian below the continuous permafrost. In the literature, there are two plausible explanations for the relatively high <span class="hlt">pore</span> pressures in the sub-permafrost aquifer; the recharge related to the ice sheet melting and the expulsion of <span class="hlt">water</span> related to the ice expansion. In this study, we investigated areas where ice sheets have never developed like in the Paris basin region. The ice expansion induces also soil surface uplift. Our study focuses on modifications of <span class="hlt">pore</span> <span class="hlt">water</span> pressure in the sub-permafrost aquifer and the soil surface motion during the permafrost development (freezing front deepening). To fill in the gaps to the field data availability, we developed an experimental approach. Experimental design was undertaken at the Laboratory M2C (Université de Caen-Basse Normandie, CNRS, France). The device consisted in a 2 m2 box insulated at all sides except on the top where a surface temperature was prescribed. The box is filled with silty sand of which hydraulics and thermal parameters are known. Soil temperatures, <span class="hlt">pore</span> <span class="hlt">water</span> pressure and soil motion are continuously recorded at different elevations in the sand-box. We developed a two-dimensional transient fully coupled heat and <span class="hlt">water</span> transport model to simulate thawing and freezing processes taking into account the phase change (Latent heat effects). The balance equations are solved using of a finite difference numerical scheme. Experimental results are used to verify the implementation of the hydro-mechanical processes in our numerical simulations. Experimental and numerical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..188a2028T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..188a2028T"><span>Study of phosphate release from Bogor botanical gardens’ sediment into <span class="hlt">pore</span> <span class="hlt">water</span> using diffusive gradient in thin film (DGT)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tirta, A. P.; Saefumillah, A.; Foliatini</p> <p>2017-04-01</p> <p>Eutrophication is one of the environmental problems caused by the excessive nutrients in aquatic ecosystems. In most lakes, phosphate is a limiting nutrient for algae photosynthesis. Even though the concentration of phosphate from external loading into the <span class="hlt">water</span> body has been reduced, eutrophication could still be occured due to internal mobilization of phosphate from the sediment <span class="hlt">pore</span> <span class="hlt">water</span> into the overlying <span class="hlt">water</span>. Therefore, the released phosphate from sediments and their interaction in the <span class="hlt">pore</span> <span class="hlt">water</span> must be included in the monitoring of phosphate concentration in aquatic system. The released phosphate from sediment into <span class="hlt">pore</span> <span class="hlt">water</span> has been studied by DGT device with ferrihydrite as binding gel and N-N‧-methylenebisacrylamide as crosslinker. The results showed that DGT with 15% acrylamide; 0.1 % N-N‧-methylenebisacrylamide and ferrihydrite as binding gel was suitable for the measurement of the released phosphate from sediment into <span class="hlt">pore</span> <span class="hlt">water</span>. The result of the deployed DGT in oxic and anoxic conditions in seven days incubation showed the released phosphate process from the sediment into <span class="hlt">pore</span> <span class="hlt">water</span> was affected by incubation time and the existence of oxygen in the environment. The released phosphate from the sediment into <span class="hlt">pore</span> <span class="hlt">water</span> in anoxic condition has a higher value than oxic condition. The experimental results of the deployed DGT in natural sediment core at a depth of 1 to 15 cm from the surface of the <span class="hlt">water</span> for 7 days showed that the sediment has a different phosphate mass profile based on depth. The concentration of phosphate tends to be increased with depth. The maximum CDGT of phosphate released in oxic and anoxic conditions at 7th day period of incubation are 29.23 μg/L at 14 cm depth and 30.19 μg/L at 8 cm depth, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApWS....7.2321Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApWS....7.2321Z"><span>Effect of <span class="hlt">pore</span> <span class="hlt">water</span> velocities and solute input methods on chloride transport in the undisturbed soil columns of Loess Plateau</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, BeiBei; Wang, QuanJiu</p> <p>2017-09-01</p> <p>Studies on solute transport under different <span class="hlt">pore</span> <span class="hlt">water</span> velocity and solute input methods in undisturbed soil could play instructive roles for crop production. Based on the experiments in the laboratory, the effect of solute input methods with small pulse input and large pulse input, as well as four <span class="hlt">pore</span> <span class="hlt">water</span> velocities, on chloride transport in the undisturbed soil columns obtained from the Loess Plateau under controlled condition was studied. Chloride breakthrough curves (BTCs) were generated using the miscible displacement method under <span class="hlt">water</span>-saturated, steady flow conditions. Using the 0.15 mol L-1 CaCl2 solution as a tracer, a small pulse (0.1 <span class="hlt">pore</span> volumes) was first induced, and then, after all the solution was wash off, a large pulse (0.5 <span class="hlt">pore</span> volumes) was conducted. The convection-dispersion equation (CDE) and the two-region model (T-R) were used to describe the BTCs, and their prediction accuracies and fitted parameters were compared as well. All the BTCs obtained for the different input methods and the four <span class="hlt">pore</span> <span class="hlt">water</span> velocities were all smooth. However, the shapes of the BTCs varied greatly; small pulse inputs resulted in more rapid attainment of peak values that appeared earlier with increases in <span class="hlt">pore</span> <span class="hlt">water</span> velocity, whereas large pulse inputs resulted in an opposite trend. Both models could fit the experimental data well, but the prediction accuracy of the T-R was better. The values of the dispersivity, λ, calculated from the dispersion coefficient obtained from the CDE were about one order of magnitude larger than those calculated from the dispersion coefficient given by the T-R, but the calculated Peclet number, Pe, was lower. The mobile-immobile partition coefficient, β, decreased, while the mass exchange coefficient increased with increases in <span class="hlt">pore</span> <span class="hlt">water</span> velocity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EP%26S...66..137T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EP%26S...66..137T"><span>Origin and transport of <span class="hlt">pore</span> fluids in the Nankai accretionary prism inferred from chemical and isotopic compositions of <span class="hlt">pore</span> <span class="hlt">water</span> at cold seep sites off Kumano</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Toki, Tomohiro; Higa, Ryosaku; Ijiri, Akira; Tsunogai, Urumu; Ashi, Juichiro</p> <p>2014-12-01</p> <p>We used push corers during manned submersible dives to obtain sediment samples of up to 30 cm from the subseafloor at the Oomine Ridge. The concentrations of B in <span class="hlt">pore</span> <span class="hlt">water</span> extracted from the sediment samples from cold seep sites were higher than could be explained by organic matter decomposition, suggesting that the seepage fluid at the site was influenced by B derived from smectite-illite alteration, which occurs between 50°C and 160°C. Although the negative δ18OH2O and δDH2O values of the <span class="hlt">pore</span> fluids cannot be explained by freshwater derived from clay mineral dehydration (CMD), we considered the contribution of <span class="hlt">pore</span> fluids in the shallow sediments of the accretionary prism, which showed negative δ18OH2O and δDH2O values according to the results obtained during Integrated Ocean Drilling Program (IODP) Expeditions 315 and 316. We calculated the mixing ratios based on a four-end-member mixing model including freshwater derived from CMD, <span class="hlt">pore</span> fluids in the shallow (SPF) accretionary prism sediment, seawater (SW), and freshwater derived from methane hydrate (MH) dissociation. However, the Oomine seep fluids were unable to be explained without four end members, suggesting that deep-sourced fluids in the accretionary prism influenced the seeping fluids from this area. This finding presents the first evidence of deep-sourced fluids at cold seep sites in the Oomine Ridge, indicating that a megasplay fault is a potential pathway for the deep-sourced fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.B34A..04L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.B34A..04L"><span>Determining Carbonate Concretion Formation Temperatures and <span class="hlt">Pore</span> <span class="hlt">Water</span> δ18O Values Using the Clumped Isotope Approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Loyd, S. J.; Corsetti, F. A.; Tripati, A. K.</p> <p>2010-12-01</p> <p>The porosity/permeability of siliciclastic strata is affected by post-depositional cementation, but determining at what depth and under what conditions cementation occurs is difficult with standard techniques. The oxygen isotopic composition of solid phase carbonate cements (δ18Ocarb) can be related to temperature (and by extension depth) of formation, and thus has been widely used in diagenetic studies. However, δ18Ocarb paleothermometry requires the prediction or assumption of <span class="hlt">pore</span> <span class="hlt">water</span> δ18O (δ18Opw), a parameter that is poorly constrained in past diagenetic environments (for convenience δ18Opw is usually assumed to be 0‰ VSMOW). Here, we use clumped isotope thermometry (CIT)—a fluid δ18O-independent temperature proxy—to avoid the often ambiguous yet necessary δ18Opw assumption applied to δ18Ocarb paleothermometery and reevaluate the temperature of carbonate concretion formation in the Miocene Monterey Formation (dolomite) and the Cretaceous Holz Shale (calcite) of southern California. CIT analysis of Monterey Formation concretions produced slightly increased temperatures of formation versus traditional δ18Ocarb paleothermometry, whereas the Holz Shale concretions produced significantly decreased temperatures. Inputting the CIT-derived temperature into the associated δ18Ocarb-temperature equation allows the calculation of the ancient δ18Opw. Calculated δ18Opw values range from ~ -8 to +2‰ VSMOW, significantly different from coeval seawater. δ18Opw less than 0‰ can be generated by a number of processes including the influx of non-<span class="hlt">marine</span> fluids and/or hydrate formation, whereas δ18Opw greater than 0‰ can be produced by silicate diagenesis, influx of evaporative brines, or hydrate dissolution. These data demonstrate that <span class="hlt">pore</span> <span class="hlt">water</span> modifying diagenetic processes were operating in past environments and emphasize that the formation temperatures of diagenetic carbonates should be calculated using a fluid δ18O-independent approach, such as</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JPhD...45j5302S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JPhD...45j5302S"><span>Monitoring <span class="hlt">water</span> transport between <span class="hlt">pores</span> and voids in aerated gypsum using two-dimensional nuclear magnetic resonance exchange measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Song, Kyung-Min; Mitchell, Jonathan; Jaffel, Hamouda; Gladden, Lynn F.</p> <p>2012-03-01</p> <p>We investigate the connectivity between aeration voids (radius 200-300 µm) and <span class="hlt">pores</span> (radius 20 µm) in aerated gypsum plaster using two-dimensional (2D) nuclear magnetic resonance T2-T2 relaxation time exchange experiments. These measurements provide an estimate of diffusive exchange rates for <span class="hlt">water</span> molecules moving between environments differentiated by relaxation time. Aerated gypsum is a lightweight material manufactured by the inclusion of voids to reduce the bulk density. Such materials exhibit a multi-modal distribution of <span class="hlt">pore</span> and void sizes and are associated with novel <span class="hlt">water</span> imbibition processes. Here, we use T2-T2 exchange experiments to characterize the extent of fluid communication between the voids and <span class="hlt">pores</span> to better understand the structure-transport relationships in these systems. In turn, this will aid the design of gypsum plasters with improved physical and mechanical properties. Utilizing an analytical model based on diffusion-driven exchange, we extract exchange times and hence diffusive length-scales, which are equivalent to the <span class="hlt">pore</span> diameter. Overall, we conclude that the voids and <span class="hlt">pores</span> are well connected. This confirms our previous hypothesis that <span class="hlt">water</span> uptake occurs via capillary-driven imbibition through a continuum of voids and <span class="hlt">pores</span> in aerated gypsum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001GeoRL..28.1227B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001GeoRL..28.1227B"><span>Mercury cycling in boreal ecosystems: The long-term effect of acid rain constituents on peatland <span class="hlt">pore</span> <span class="hlt">water</span> methylmercury concentrations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Branfireun, Brian A.; Bishop, Kevin; Roulet, Nigel T.; Granberg, Gunnar; Nilsson, Mats</p> <p></p> <p>Sulphate-reducing bacteria have been identified as primary methylators of mercury (Hg) in the laboratory and in field investigations. However, no studies have investigated the effect of long-term deposition of sulphate on methylmercury (MeHg) dynamics in peatlands, which are known to be significant sources of MeHg to downstream <span class="hlt">waters</span> in the boreal forest zone. As an ancillary experiment to a larger project investigating the effects of acid rain constituents on peatland carbon dynamics, the influence of experimentally elevated Na2SO4 and/or NH4NO3 deposition on peat <span class="hlt">pore</span> <span class="hlt">water</span> MeHg concentrations was determined using a simple mesocosm experimental design. After three years, additions of S in amounts equivalent to the 1980s dry and wet deposition in Southern Sweden resulted in peat <span class="hlt">pore</span> <span class="hlt">water</span> MeHg concentrations up to six times above background levels. Elevated N loads had no effect on <span class="hlt">pore</span> <span class="hlt">water</span> MeHg concentrations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4764808','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4764808"><span>Active Sampling Device for Determining Pollutants in Surface and <span class="hlt">Pore</span> <span class="hlt">Water</span> – the In Situ Sampler for Biphasic <span class="hlt">Water</span> Monitoring</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Supowit, Samuel D.; Roll, Isaac B.; Dang, Viet D.; Kroll, Kevin J.; Denslow, Nancy D.; Halden, Rolf U.</p> <p>2016-01-01</p> <p>We designed and evaluated an active sampling device, using as analytical targets a family of pesticides purported to contribute to honeybee colony collapse disorder. Simultaneous sampling of bulk <span class="hlt">water</span> and <span class="hlt">pore</span> <span class="hlt">water</span> was accomplished using a low-flow, multi-channel pump to deliver <span class="hlt">water</span> to an array of solid-phase extraction cartridges. Analytes were separated using either liquid or gas chromatography, and analysis was performed using tandem mass spectrometry (MS/MS). Achieved recoveries of fipronil and degradates in <span class="hlt">water</span> spiked to nominal concentrations of 0.1, 1, and 10 ng/L ranged from 77 ± 12 to 110 ± 18%. Method detection limits (MDLs) were as low as 0.040–0.8 ng/L. Extraction and quantitation of total fiproles at a wastewater-receiving wetland yielded concentrations in surface <span class="hlt">water</span> and <span class="hlt">pore</span> <span class="hlt">water</span> ranging from 9.9 ± 4.6 to 18.1 ± 4.6 ng/L and 9.1 ± 3.0 to 12.6 ± 2.1 ng/L, respectively. Detected concentrations were statistically indistinguishable from those determined by conventional, more laborious techniques (p > 0.2 for the three most abundant fiproles). Aside from offering time-averaged sampling capabilities for two phases simultaneously with picogram-per-liter MDLs, the novel methodology eliminates the need for <span class="hlt">water</span> and sediment transport via in situ solid phase extraction. PMID:26905924</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...621886S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...621886S"><span>Active Sampling Device for Determining Pollutants in Surface and <span class="hlt">Pore</span> <span class="hlt">Water</span> - the In Situ Sampler for Biphasic <span class="hlt">Water</span> Monitoring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Supowit, Samuel D.; Roll, Isaac B.; Dang, Viet D.; Kroll, Kevin J.; Denslow, Nancy D.; Halden, Rolf U.</p> <p>2016-02-01</p> <p>We designed and evaluated an active sampling device, using as analytical targets a family of pesticides purported to contribute to honeybee colony collapse disorder. Simultaneous sampling of bulk <span class="hlt">water</span> and <span class="hlt">pore</span> <span class="hlt">water</span> was accomplished using a low-flow, multi-channel pump to deliver <span class="hlt">water</span> to an array of solid-phase extraction cartridges. Analytes were separated using either liquid or gas chromatography, and analysis was performed using tandem mass spectrometry (MS/MS). Achieved recoveries of fipronil and degradates in <span class="hlt">water</span> spiked to nominal concentrations of 0.1, 1, and 10 ng/L ranged from 77 ± 12 to 110 ± 18%. Method detection limits (MDLs) were as low as 0.040-0.8 ng/L. Extraction and quantitation of total fiproles at a wastewater-receiving wetland yielded concentrations in surface <span class="hlt">water</span> and <span class="hlt">pore</span> <span class="hlt">water</span> ranging from 9.9 ± 4.6 to 18.1 ± 4.6 ng/L and 9.1 ± 3.0 to 12.6 ± 2.1 ng/L, respectively. Detected concentrations were statistically indistinguishable from those determined by conventional, more laborious techniques (p > 0.2 for the three most abundant fiproles). Aside from offering time-averaged sampling capabilities for two phases simultaneously with picogram-per-liter MDLs, the novel methodology eliminates the need for <span class="hlt">water</span> and sediment transport via in situ solid phase extraction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JEPT...87..773Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JEPT...87..773Z"><span>Numerical Investigation of Physicochemical Processes Occurring During <span class="hlt">Water</span> Evaporation in the Surface Layer <span class="hlt">Pores</span> of a Forest Combustible Material</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhdanova, A. O.; Kuznetsov, G. V.; Strizhak, P. A.</p> <p>2014-07-01</p> <p>A numerical investigation of the physicochemical processes occurring during <span class="hlt">water</span> evaporation from the <span class="hlt">pores</span> of the surface layer of a forest combustible material has been carried out. The characteristic features of the suppression of the thermal decomposition reaction of a combustible material with <span class="hlt">water</span> filling fullyits <span class="hlt">pores</span> and formation of a <span class="hlt">water</span> fi lm over its surface have been determined. The characteristic times of suppression of thermal decomposition reactions under various environmental conditions and the thickness and kinds of forest combustible material (birch leaves, pine and spruce needles, etc.) have been established.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70038464','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70038464"><span>Toxicity of sediment <span class="hlt">pore</span> <span class="hlt">water</span> in Puget Sound (Washington, USA): a review of spatial status and temporal trends</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Long, Edward R.; Carr, R. Scott; Biedenbach, James M.; Weakland, Sandra; Partridge, Valerie; Dutch, Margaret</p> <p>2013-01-01</p> <p>Data from toxicity tests of the <span class="hlt">pore</span> <span class="hlt">water</span> extracted from Puget Sound sediments were compiled from surveys conducted from 1997 to 2009. Tests were performed on 664 samples collected throughout all of the eight monitoring regions in the Sound, an area encompassing 2,294.1 km2. Tests were performed with the gametes of the Pacific purple sea urchin, Strongylocentrotus purpuratus, to measure percent fertilization success as an indicator of relative sediment quality. Data were evaluated to determine the incidence, degree of response, geographic patterns, spatial extent, and temporal changes in toxicity. This is the first survey of this kind and magnitude in Puget Sound. In the initial round of surveys of the eight regions, 40 of 381 samples were toxic for an incidence of 10.5 %. Stations classified as toxic represented an estimated total of 107.1 km2, equivalent to 4.7 % of the total area. Percent sea urchin fertilization ranged from >100 % of the nontoxic, negative controls to 0 %. Toxicity was most prevalent and pervasive in the industrialized harbors and lowest in the deep basins. Conditions were intermediate in deep-<span class="hlt">water</span> passages, urban bays, and rural bays. A second round of testing in four regions and three selected urban bays was completed 5–10 years following the first round. The incidence and spatial extent of toxicity decreased in two of the regions and two of the bays and increased in the other two regions and the third bay; however, only the latter change was statistically significant. Both the incidence and spatial extent of toxicity were lower in the Sound than in most other US estuaries and <span class="hlt">marine</span> bays.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25399780','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25399780"><span>Temporal evolution and variability of dissolved inorganic nitrogen in beach <span class="hlt">pore</span> <span class="hlt">water</span> revealed using radon residence times.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Goodridge, Blair M; Melack, John M</p> <p>2014-12-16</p> <p>We coupled measurements of beach <span class="hlt">pore</span> <span class="hlt">water</span> residence time, determined using the radioisotopic tracer (222)Rn, with dissolved carbon and nitrogen chemistry to identify the temporal evolution and variability of dissolved inorganic nitrogen (DIN) concentrations in beach <span class="hlt">pore</span> <span class="hlt">water</span> along the Santa Barbara, California coastline. <span class="hlt">Pore</span> <span class="hlt">water</span> dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) ratios (DOC:TDN) were negative exponentially correlated with residence time. Mean <span class="hlt">pore</span> <span class="hlt">water</span> residence times were positively correlated with tidal amplitudes, and ranged from 4.4 to 6.4 days. We used this range in mean residence times to model radon residence time distributions (RTDs), and integrated them with modeled DIN vs residence time relationships (DIN-temporal evolution, or DIN-te curves) to derive volume-weighted mean (VWM) DIN concentrations. We observed 1.2-fold and 5.2-fold differences (20% and 420% increases) in VWM DIN concentrations over the range in modeled RTDs and DIN-te curves, respectively, and a maximum 6.4-fold difference (540% increase) in VWM DIN concentrations for an interactive shift in the RTD and the DIN-te curve. Our study suggests that accounting for temporal variability in the RTD and DIN concentration of <span class="hlt">pore</span> <span class="hlt">water</span> is necessary to obtain more accurate estimates of DIN delivery to coastal oceans.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70014185','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014185"><span>Solid-state 13C NMR studies of dissolved organic matter in <span class="hlt">pore</span> <span class="hlt">waters</span> from different depositional environments</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Orem, W.H.; Hatcher, P.G.</p> <p>1987-01-01</p> <p>Dissolved organic matter (DOM) in <span class="hlt">pore</span> <span class="hlt">waters</span> from sediments of a number of different depositional environments was isolated by ultrafiltration using membranes with a nominal molecular weight cutoff of 500. This > 500 molecular weight DOM represents 70-98% of the total DOM in these <span class="hlt">pore</span> <span class="hlt">waters</span>. We determined the gross chemical structure of this material using both solid-state 13C nuclear magnetic resonance spectroscopy and elemental analysis. Our results show that the DOM in these <span class="hlt">pore</span> <span class="hlt">waters</span> appears to exist as two major types: one type dominated by carbohydrates and paraffinic structures and the second dominated by paraffinic and aromatic structures. We suggest that the dominance of one or the other structural type of DOM in the <span class="hlt">pore</span> <span class="hlt">water</span> depends on the relative oxidizing/reducing nature of the sediments as well as the source of the detrital organic matter. Under dominantly anaerobic conditions carbohydrates in the sediments are degraded by bacteria and accumulate in the <span class="hlt">pore</span> <span class="hlt">water</span> as DOM. However, little or no degradation of lignin occurs under these conditions. In contrast, sediments thought to be predominantly aerobic in character have DOM with diminished carbohydrate and enhanced aromatic character. The aromatic structures in the DOM from these sediments are thought to arise from the degradation of lignin. The large amounts of paraffinic structures in both types of DOM may be due to the degradation of unidentified paraffinic materials in algal or bacterial remains. ?? 1987.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17937318','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17937318"><span>Predicting bioavailability of sediment polycyclic aromatic hydrocarbons to Hyalella azteca using equilibrium partitioning, supercritical fluid extraction, and <span class="hlt">pore</span> <span class="hlt">water</span> concentrations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hawthorne, Steven B; Azzolina, Nicholas A; Neuhauser, Edward F; Kreitinger, Joseph P</p> <p>2007-09-01</p> <p>Polycyclic aromatic hydrocarbon (PAH) bioavailability to Hyalella azteca was determined in 97 sediments from six former manufactured-gas plants and two aluminum smelter sites. Measurements of Soxhlet extractable, rapidly released based on mild supercritical fluid extraction, and <span class="hlt">pore</span> <span class="hlt">water</span> dissolved concentrations of 18 parent and 16 groups of alkyl PAHs (PAH34) were used to predict 28 daysurvival based on equilibrium partitioning and hydrocarbon narcosis models. Total PAH concentrations had little relationship to toxicity. Amphipods survived in sediments with PAH34 concentrations as high as 2990 microg/g, while sediments as low as 2.4 microg/g of PAH34 resulted in significant mortality. Equilibrium partitioning using either total extractable or rapidly released concentrations significantly improved predictions. However, <span class="hlt">pore</span> <span class="hlt">water</span> PAH34 concentrations were best for predicting amphipod survival and correctly classified toxic and nontoxic sediment samples with an overall model efficiency of 90%. Alkyl PAHs accounted for 80% of the toxicity, demonstrating that careful measurement of the 16 alkyl clusters in <span class="hlt">pore</span> <span class="hlt">water</span> is required. Regression analysis of the <span class="hlt">pore</span> <span class="hlt">water</span> PAH34 data from 97 field sediments against amphipod survival resulted in a mean 50% lethal residue value of 33 micromol/g of lipid, consistent with 32 micromol/g of lipid for fluoranthene determined by others in controlled laboratory conditions, thus demonstrating the applicability of EPA's hydrocarbon narcosis model when using <span class="hlt">pore</span> <span class="hlt">water</span> PAH34 concentrations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.H33L..01B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.H33L..01B"><span><span class="hlt">Water</span>-Organic-Rock Reactions Recorded in <span class="hlt">Pores</span> in Shales from the Marcellus and Rose Hill Formations (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brantley, S. L.; Jin, L.; Rother, G.; Cole, D. R.; gu, X.; Balashov, V. N.</p> <p>2013-12-01</p> <p>The porosity of shales varies depending upon such attributes as the mineralogy, grain size, organic content, depth and duration of burial, and extent of <span class="hlt">water</span>-rock reaction. Today, shales are being exploited when they contain significant natural gas, and the connectivity of <span class="hlt">pores</span> are important toward controlling both recovery of gas after hydrofracking. In fact, the fine-scale nature of the <span class="hlt">pores</span> controls aspects of release of natural gas and brines during hydrofracturing and gas exploitation. Despite the importance of shale as a source rock for natural gas and petroleum, it remains difficult to quantify and image porosity in shales because of their fine-scale nature. We are using neutron scattering, FIB SEM, CT microtomography, and other techniques to understand <span class="hlt">pores</span> in a black (Marcellus) and a grey shale (Rose Hill formation) sampled in Pennsylvania. Samples were recovered both from outcrop and from depth in wellbores. We also report a new approach for investigating <span class="hlt">pores</span> in shales by using neutron scattering before and after removal of organic matter. <span class="hlt">Pores</span> in the two shales are observed to be isotropic (i.e. in the plane of bedding) or anisotropic (i.e. perpendicular to bedding), as expected for sediments that have been compacted after burial. Some nanometer-sized <span class="hlt">pores</span> are observed in the organic matter of the Marcellus to be spherical; other <span class="hlt">pores</span> are observed to be present in pyrite framboids and among silicate grains in that rock. We have no evidence that significant porosity is present in the organic matter in the Rose Hill formation, a relatively organic-poor shale, but <span class="hlt">pores</span> are observed between and in clay particles. We also investigate how progressive <span class="hlt">water</span>-rock reaction changes the primary porosity in the shales by investigating weathering samples. FIB SEM images document that organic matter is oxidized and removed significantly from the weathering Marcellus before the rock turns to soil, leaving behind porosity. Pyrite oxidation and dissolution</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21357685','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21357685"><span>Mineralogy and <span class="hlt">pore</span> <span class="hlt">water</span> chemistry of a boiler ash from a MSW fluidized-bed incinerator</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bodenan, F.; Guyonnet, D.; Piantone, P.; Blanc, P.</p> <p>2010-07-15</p> <p>This paper presents an investigation of the mineralogy and <span class="hlt">pore</span> <span class="hlt">water</span> chemistry of a boiler ash sampled from a municipal solid waste fluidized-bed incinerator, subject to 18 months of dynamic leaching in a large percolation column experiment. A particular focus is on the redox behaviour of Cr(VI) in relation to metal aluminium Al{sup 0}, as chromium may represent an environmental or health hazard. The leaching behaviour and interaction between Cr(VI) and Al{sup 0} are interpreted on the basis of mineralogical evolutions observed over the 18-month period and of saturation indices calculated with the geochemical code PhreeqC and reviewed thermodynamic data. Results of mineralogical analyses show in particular the alteration of mineral phases during leaching (e.g. quartz and metal aluminium grains), while geochemical calculations suggest equilibria of percolating fluids with respect to specific mineral phases (e.g. monohydrocalcite and aluminium hydroxide). The combination of leaching data on a large scale and mineralogical analyses document the coupled leaching behaviour of aluminium and chromium, with chromium appearing in the <span class="hlt">pore</span> fluids in its hexavalent and mobile state once metal aluminium is no longer available for chromium reduction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10729262','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10729262"><span>NMR characterization of the <span class="hlt">pore</span> structure and anisotropic self-diffusion in salt <span class="hlt">water</span> Ice</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Menzel; Han; Stapf; Blumich</p> <p>2000-04-01</p> <p>NMR imaging and one- and two-dimensional self-diffusion propagator measurements of the liquid phase in salt <span class="hlt">water</span> ice are presented. The properties of the network of brine-filled <span class="hlt">pores</span> are found to depend on the growth conditions of the ice. Two types of samples are compared: (a) shock-frozen ice produced in the probe in situ and (b) ice grown over several hours under controlled conditions. By shock-freezing, an ice structure could be produced which featured streak-like porous channels of diameters of up to 300 &mgr;m allowing almost unrestricted self-diffusion along one preferential axis but reduced diffusivities in the remaining directions. In ice grown under controlled conditions, the <span class="hlt">pore</span> sizes are near the resolution limit of the imaging experiment of typically 50 &mgr;m. For this type of samples, strongly non-Gaussian self-diffusion propagators are obtained, indicating restricted self-diffusion on rms scales of 30 &mgr;m. Common to all samples was the observation of highly anisotropic self-diffusion. One- and two-dimensional propagators are compared in order to estimate the degree of anisotropy and the size of the restrictions. Copyright 2000 Academic Press.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20153161','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20153161"><span>Mineralogy and <span class="hlt">pore</span> <span class="hlt">water</span> chemistry of a boiler ash from a MSW fluidized-bed incinerator.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bodénan, F; Guyonnet, D; Piantone, P; Blanc, P</p> <p>2010-07-01</p> <p>This paper presents an investigation of the mineralogy and <span class="hlt">pore</span> <span class="hlt">water</span> chemistry of a boiler ash sampled from a municipal solid waste fluidized-bed incinerator, subject to 18 months of dynamic leaching in a large percolation column experiment. A particular focus is on the redox behaviour of Cr(VI) in relation to metal aluminium Al(0), as chromium may represent an environmental or health hazard. The leaching behaviour and interaction between Cr(VI) and Al(0) are interpreted on the basis of mineralogical evolutions observed over the 18-month period and of saturation indices calculated with the geochemical code PhreeqC and reviewed thermodynamic data. Results of mineralogical analyses show in particular the alteration of mineral phases during leaching (e.g. quartz and metal aluminium grains), while geochemical calculations suggest equilibria of percolating fluids with respect to specific mineral phases (e.g. monohydrocalcite and aluminium hydroxide). The combination of leaching data on a large scale and mineralogical analyses document the coupled leaching behaviour of aluminium and chromium, with chromium appearing in the <span class="hlt">pore</span> fluids in its hexavalent and mobile state once metal aluminium is no longer available for chromium reduction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PhDT.......109R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhDT.......109R"><span>Using direct measurements of submarine groundwater discharge to investigate the coupling between surface and <span class="hlt">pore</span> <span class="hlt">waters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rapaglia, John Paul</p> <p></p> <p>Submarine groundwater discharge (SGD) and its associated impact on coastal ecosystems was investigated at the sediment-<span class="hlt">water</span> interface using diverse methods. This intercomparison of methods was the objective of a major project carried out in 5 diverse hydrogeological settings (Cockburn Sound, Australia; Donnalucata, Sicily; Shelter Island, USA; Ubatuba Bay, Brazil; and Flic-en-Flac Bay, Mauritius). Small-scale sedimentary processes were deemed very important in the control of local hydrogeological characteristics. Seepage meters were used to directly measure the flow of <span class="hlt">water</span> across the sediment-sea interface. Coincident measurements of bulk ground conductivity (BGC) were made alongside seepage meters at four of these locations. An inverse relationship between BGC and SGD allowed for the extrapolation of point measurements of SGD to larger areas using BGC data. SGD estimates made using this method compared favorably with those obtained using other techniques. Using seepage meters to measure flow rates, along with a manual drive point piezometer to measure <span class="hlt">pore</span> <span class="hlt">water</span> profiles, the coupling between <span class="hlt">pore</span> <span class="hlt">water</span> composition and advection due to SGD was investigated. The process of dispersion was found to determine both the shape and depth of salinity, nutrient, and radium profiles in the sediment. Dispersion may be controlled by biological or physical processes including the rate of advection itself, all of which change over time. Dispersion coefficients ranging from 0.02 m2d -1 to 2.8 m2d-1 were estimated from direct measurements. This data also allowed for the investigation of anthropogenic impacts on the signature of SGD in coastal lagoons. At Shelter Island, the pilings of a pier altered the flow of groundwater into the sea by piercing a confining layer and allowing for a large influx of fresh groundwater from below. In the Venice Lagoon, the difference in <span class="hlt">water</span> elevation between the lagoon and the sea has been investigated as a possible driver of SGD beneath the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24061783','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24061783"><span>Pilot-scale in situ bioremediation of HMX and RDX in soil <span class="hlt">pore</span> <span class="hlt">water</span> in Hawaii.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Payne, Zachary M; Lamichhane, Krishna M; Babcock, Roger W; Turnbull, Stephen J</p> <p>2013-10-01</p> <p>A nine-month in situ bioremediation study was conducted in Makua Military Reservation (MMR) in Oahu, Hawaii (USA) to evaluate the potential of molasses to enhance biodegradation of royal demolition explosive (RDX) and high-melting explosive (HMX) contaminated soil below the root zone. MMR has been in operation since the 1940's resulting in subsurface contamination that in some locations exceeds USEPA preliminary remediation goals for these chemicals. A molasses-<span class="hlt">water</span> mixture (1 : 40 dilution) was applied to a treatment plot and clean <span class="hlt">water</span> was applied to a control plot via seven flood irrigation events. <span class="hlt">Pore</span> <span class="hlt">water</span> samples were collected from 12 lysimeters installed at different depths in 3 boreholes in each test plot. The difference in mean concentrations of RDX in <span class="hlt">pore</span> <span class="hlt">water</span> samples from the two test plots was very highly significant (p < 0.001). The concentrations differences with depth were also very highly significant (p < 0.001) and degradation was greatly enhanced at depths from 5 to 13.5 ft. biodegradation was modeled as first order and the rate constant was 0.063 per day at 5 ft and decreased to 0.023 per day at 11 ft to 13.5 ft depth. Enhanced biodegradation of HMX was also observed in molasses treated plot samples but only at a depth of 5 ft. The difference in mean TOC concentration (surrogate for molasses) was highly significant with depth (p = 0.003) and very highly significant with treatment (p < 0.001). Mean total nitrogen concentrations also differed significantly with treatment (p < 0.001) and depth (p = 0.059). The molasses <span class="hlt">water</span> mixture had a similar infiltration rate to that of plain <span class="hlt">water</span> (average 4.12 ft per day) and reached the deepest sensor (31 ft) within 5 days of application. Most of the molasses was consumed by soil microorganisms by about 13.5 feet below ground surface and treatment of deeper depths may require greater molasses concentrations and/or more frequent flood irrigation. Use of the bioremediation method described herein</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMED31B0881P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMED31B0881P"><span><span class="hlt">Pore</span> <span class="hlt">Water</span> Arsenic Dynamics in Rice Paddies Under Projected Future Climates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Plaganas, M.; Wang, T.; Muehe, E. M.; Fendorf, S. E.</p> <p>2016-12-01</p> <p>Rice is one of the staple crops in the world, with 50% of the global population eating rice daily. Many rice-producing regions of the world are irrigated with groundwater contaminated with arsenic (As), and in particular South and Southeast Asia, where geogenic As is leached into the groundwater. Use of groundwater pervasively high in As leads to subsequent accumulation in paddy soils. Arsenic, a toxic metalloid, also decreases rice productivity and further jeopardizes food security. Hence, rice agriculture is concerned with its productivity in a climate change impacted future and the particular impacts of arsenic on yields. However, past studies do not address the prevalence of As in paddy soils or its fate in the rhizosphere and ultimate impact on the plant. The objective of our study was to determine changes in <span class="hlt">pore</span> <span class="hlt">water</span> As dynamics in the rhizosphere of rice plants grown on As-contaminated paddy soil under climate conditions projected for the end of the century. In order to address this objective, we designed greenhouse chambers with today's climate and projected climate conditions for the year 2100, specifically 5°C increase in temperature and doubled concentration of atmospheric CO2. We hypothesize that the effects of climate change with these conditions will increase the mobility of As in the rhizosphere, and thus, decrease rice growth in As-bearing paddies more than, so far, expected. We examined <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry including pH and As concentrations, and correlate that to the height of the plants. Furthermore, the dynamics of other elements in the <span class="hlt">pore</span> <span class="hlt">water</span> such as carbon, iron, sulfur, manganese, and silica are further evaluated for their effects on rice growth. Arsenic will have an impact on rice production and conditions induced by future climatic conditions need to be considered for food security. Considering that climate change will decrease the global agricultural output, we should urgently consider adapting our agricultural practices to aid</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS44A..08H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS44A..08H"><span>Sediment-<span class="hlt">pore</span> <span class="hlt">water</span> interactions controlling cementation in the NanTroSEIZE drilling transects</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hong, W.; Spinelli, G. A.; Torres, M. E.</p> <p>2012-12-01</p> <p>One goal of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is to understand how changes in subducting sediment control the transition from aseismic to seismogenic behavior in subduction zones. In the sediment entering the Nankai subduction zone, dramatic changes in physical and chemical properties occur across a diagenetic boundary; they are thought to affect sediment strength and deformation. The dissolution of disseminated volcanic ash and precipitation of silica cement may be responsible for these changes in physical properties, but the mechanism controlling cementation was unclear (Spinelli et al., 2007). In this study, we used CrunchFlow (Steefel, 2009) to simulate chemical reactions and fluid flow through 1-D sediment columns at Integrated Ocean Drilling Program (IODP) sites on the incoming plate in Nankai Trough. The simulations include the thermodynamics and kinetics of sediment-<span class="hlt">water</span> interactions, advection of <span class="hlt">pore</span> <span class="hlt">water</span> and sediment due to compaction, and multi-component diffusion in an accumulating sediment column. Key reactions in the simulations are: ash dissolution, amorphous silica precipitation and dissolution, and zeolite precipitation. The rate of ash decomposition was constrained using Sr isotope data of Joseph et al. (2012). Our model reproduces the distinct diagenetic boundary observed in sediment and <span class="hlt">pore</span> <span class="hlt">water</span> chemistry, which defines two zones. Above this boundary (zone 1), dissolved and amorphous silicate contents are high and the potassium concentration remains near seawater values or gradually decreases toward the boundary. Below the boundary, both dissolved and amorphous silicate content drop rapidly, concomitant with a decrease in dissolved potassium. Our model shows that these changes in the system are driven by formation of clinoptilolite in response to changes in <span class="hlt">pore</span> fluid pH. The low pH values (<7.6) above the diagenetic boundary accelerate ash decomposition and maintain clinoptilolite slightly undersaturated. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NIMPB.294..537H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NIMPB.294..537H"><span>A summary of global 129I in <span class="hlt">marine</span> <span class="hlt">waters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>He, Peng; Aldahan, A.; Possnert, G.; Hou, X. L.</p> <p>2013-01-01</p> <p>Despite the many investigations concerning the occurrence of anthropogenic iodine-129 in the atmosphere, terrestrial and <span class="hlt">marine</span> environments, there is a lack of a comprehensive collection of data on the distribution of the isotope in <span class="hlt">marine</span> <span class="hlt">waters</span>. The temporal and spatial variability of anthropogenic 129I is strongly linked to the major point sources in the Irish Sea and the English Channel and the global <span class="hlt">marine</span> spreading pathways are partly outlined from these sources. The temporal evolution is still, however, not well defined when transport and dissipation are considered in the different oceans and ocean compartments. We here summarize available published literature data on 129I temporal and spatial distribution in the global <span class="hlt">marine</span> <span class="hlt">water</span>. The results show presence of numerous data sets for the North Atlantic and Arctic Oceans where strong variability in terms of <span class="hlt">water</span> depth, time and location also occur. Scarcity of data on 129I from the Pacific, Indian and South Atlantic Oceans demonstrates gaps in the coverage of the isotope spatial extent. These shortcomings in the spatial coverage may relate to the understanding that the anthropogenic 129I signal will take a long time to be transported, if at all, from the North Atlantic into other oceans. Data from recent expeditions in the Southern oceans and the Geotraces ocean profiling will reveal additional information about 129I distribution in the <span class="hlt">marine</span> <span class="hlt">waters</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1514238S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1514238S"><span>Impact of long term wetting on <span class="hlt">pore</span> <span class="hlt">water</span> chemistry in a peat bog in Ontario, Canada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schaper, Jonas; Blodau, Christian; Holger Knorr, Klaus</p> <p>2013-04-01</p> <p>Peatlands of the northern hemisphere store a remarkable amount of carbon but also contribute to global methane emissions. As large areas in the boreal and subarctic zone are considered to undergo significant climate change it is necessary to understand how these ecosystems react to altered environmental conditions. Since not only temperatures but also precipitation is likely to increase in these regions, it is of particular interest to understand the impact of raised <span class="hlt">water</span> tables and changing local hydrological flow patterns on peatlands' carbon cycle. We chose a pristine bog that was partly flooded by a reservoir lake created 60 years ago in Ontario, Canada. <span class="hlt">Water</span> management in the reservoir resulted in seasonal flooding, shifting hydrological flow patterns and vegetation gradients. The impact of partial flooding on <span class="hlt">pore</span> <span class="hlt">water</span> chemistry and DIC and CH4 concentrations were studied within surface peat layers. Samples were taken with <span class="hlt">pore</span> <span class="hlt">water</span> peepers along the vegetation- and flooding gradient. Turnover rates of DIC and methane were calculated from obtained concentration profiles and peat porosity under the assumption that transport is dominated by diffusion. Values of pH changed remarkably from 4 within the undisturbed bog part to almost 8 at the lake shore. Ca2+ and Mg2+ were the only ions that showed significant distribution patterns with readily increasing concentrations towards the lake <span class="hlt">water</span> body. CH4 and DIC concentrations also increased towards the lake and peaked in around 100 cm depth right at the shore with maximum concentrations being 2766 μmol L-1 for CH4 and 7543 μmol L-1 for DIC, respectively. Turnover rates also increased towards the shore albeit some uncertainty lies in this finding as steady state condition required for calculations were probably not established and transport was not only dominated by diffusion. Maximum CH4 production rates were modeled to be 36 nmol cm-3 d-1 and maximum DIC production was calculated to 64 nmol cm-3 d-1. Ca2</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA581688','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA581688"><span>Photochemical Transformation of Munitions Constituents in <span class="hlt">Marine</span> <span class="hlt">Waters</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2012-05-01</p> <p>products wa-escpuratcd and identified using solid ph:Jsc extraction and liquid spectrometry. ’lhe photolysis rntes of2,6-dinitsoto lucne(2,6-DI’I’t~ 2,4...Various <span class="hlt">marines</span> and estuary <span class="hlt">waters</span> studied 10 Table 3. Rate constants for photolysis of 2,6-DNT in natural ...<span class="hlt">waters</span> (hr-1) 14 Table 4. Rate constants for photolysis of 2,4-DNT in natural <span class="hlt">waters</span> (hr-1) 14 Table</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28735731','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28735731"><span><span class="hlt">Marine</span> debris in harbour porpoises and seals from German <span class="hlt">waters</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Unger, B; Herr, H; Benke, H; Böhmert, M; Burkhardt-Holm, P; Dähne, M; Hillmann, M; Wolff-Schmidt, K; Wohlsein, P; Siebert, U</p> <p>2017-09-01</p> <p>Records of <span class="hlt">marine</span> debris in and attached to stranded harbour porpoises (Phocoena phocoena), harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) were studied comprising information on 6587 carcasses collected along the German coast between 1990 and 2014, the decomposition state allowed for necropsy in 1622 cases. <span class="hlt">Marine</span> debris items were recorded in 31 carcasses including 14 entanglements (5 harbour porpoises, 6 harbour seals, 3 grey seals) and 17 cases of ingestion (4 harbour porpoises, 10 harbour seals, 3 grey seals). Objects comprised general debris (35.1%) and fishing related debris (64.9%). Injuries associated with <span class="hlt">marine</span> debris included lesions, suppurative ulcerative dermatitis, perforation of the digestive tract, abscessation, suppurative peritonitis and septicaemia. This study is the first investigation of <span class="hlt">marine</span> debris findings in all three <span class="hlt">marine</span> mammal species from German <span class="hlt">waters</span>. It demonstrates the health impacts <span class="hlt">marine</span> debris can have, including severe suffering and death. The results provide needed information on debris burdens in the North and Baltic Seas for implementing management directives, such as the <span class="hlt">Marine</span> Strategy Framework Directive (MSFD). Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JCHyd.140..164R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JCHyd.140..164R"><span>Diffusive release of uranium from contaminated sediments into capillary fringe <span class="hlt">pore</span> <span class="hlt">water</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rod, Kenton A.; Wellman, Dawn M.; Flury, Markus; Pierce, Eric M.; Harsh, James B.</p> <p>2012-10-01</p> <p>Despite remediation efforts at the former nuclear weapons facility, leaching of uranium (U) from contaminated sediments to the ground <span class="hlt">water</span> persists at the Hanford site 300 Area. Flooding of contaminated capillary fringe sediments due to seasonal changes in the Columbia River stage has been identified as a source for U supply to ground <span class="hlt">water</span>. We investigated U release from Hanford capillary fringe sediments by packing sediments into reservoirs of centrifugal filter devices and saturating them with Columbia River <span class="hlt">water</span> for 3 to 84 days at varying solution-to-solid ratios. After specified times, samples were centrifuged. Within the first three days, there was an initial rapid release of 6-9% of total U, independent of the solution-to-solid ratio. After 14 days of reaction, however, the experiments with the narrowest solution-to-solid ratios showed a decline in dissolved U concentrations. The removal of U from the solution phase was accompanied by removal of Ca and HCO3-. Geochemical modeling indicated that calcite could precipitate in the narrowest solution-to-solid ratio experiment. After the rapid initial release in the first three days for the wide solution-to-solid ratio experiments, there was sustained release of U into the <span class="hlt">pore</span> <span class="hlt">water</span>. This sustained release of U from the sediments had diffusion-limited kinetics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23041367','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23041367"><span>Diffusive release of uranium from contaminated sediments into capillary fringe <span class="hlt">pore</span> <span class="hlt">water</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rod, Kenton A; Wellman, Dawn M; Flury, Markus; Pierce, Eric M; Harsh, James B</p> <p>2012-10-01</p> <p>Despite remediation efforts at the former nuclear weapons facility, leaching of uranium (U) from contaminated sediments to the ground <span class="hlt">water</span> persists at the Hanford site 300 Area. Flooding of contaminated capillary fringe sediments due to seasonal changes in the Columbia River stage has been identified as a source for U supply to ground <span class="hlt">water</span>. We investigated U release from Hanford capillary fringe sediments by packing sediments into reservoirs of centrifugal filter devices and saturating them with Columbia River <span class="hlt">water</span> for 3 to 84days at varying solution-to-solid ratios. After specified times, samples were centrifuged. Within the first three days, there was an initial rapid release of 6-9% of total U, independent of the solution-to-solid ratio. After 14days of reaction, however, the experiments with the narrowest solution-to-solid ratios showed a decline in dissolved U concentrations. The removal of U from the solution phase was accompanied by removal of Ca and HCO(3)(-). Geochemical modeling indicated that calcite could precipitate in the narrowest solution-to-solid ratio experiment. After the rapid initial release in the first three days for the wide solution-to-solid ratio experiments, there was sustained release of U into the <span class="hlt">pore</span> <span class="hlt">water</span>. This sustained release of U from the sediments had diffusion-limited kinetics. Copyright © 2012 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22428849','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22428849"><span>Ceramic <span class="hlt">pore</span> channels with inducted carbon nanotubes for removing oil from <span class="hlt">water</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chen, Xinwei; Hong, Liang; Xu, Yanfang; Ong, Zheng Wei</p> <p>2012-04-01</p> <p><span class="hlt">Water</span> contaminated with tiny oil emulsions is costly and difficult to treat because of the colloidal stability and deformable nature of emulsified oil. This work utilizes carbon nanotubes (CNTs) in macro/mesopore channels of ceramic membrane to remove tiny oil droplets from <span class="hlt">water</span>. The CNTs were implanted into the porous ceramic channels by means of chemical vapor deposition. Being hydrophobic in nature and possessing an interfacial curvature at nanoscale, CNTs enabled tiny oil emulsion in submicrometer and nano scales to be entrapped while permeating through the CNTs implanted <span class="hlt">pore</span> channels. Optimizing the growth condition of the CNTs resulted in a uniform distribution of CNT grids, which allowed the development of lipophilic layers during filtration. These lipo-layers drastically enhanced the separation performance. The filtration capability of CNT-ceramic membrane was assessed by the purification of a dilute oil-in-<span class="hlt">water</span> (o/w) emulsion containing ca. 210 ppm mineral oil 1600 ppm emulsifier, and a trace amount of dye, a proxy polluted <span class="hlt">water</span> source. The best CNT-tailored ceramic membrane, prepared under the optimized CNT growth condition, claimed 100% oil rejection rate and a permeation flux of 0.6 L m(-2) min(-1), driven by a pressure drop of ca. 1 bar for 3 days on the basis of UV measurement. The CNT-sustained adsorption complements the size-exclusion mechanism in removing soluble oil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=59667&keyword=Animation&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78833931&CFTOKEN=14454573','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=59667&keyword=Animation&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78833931&CFTOKEN=14454573"><span>DEVELOPMENT OF <span class="hlt">MARINE</span> <span class="hlt">WATER</span> QUALITY CRITERIA</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The U.S. Environmental Protectional Agency has developed guidelines for deriving numerical national <span class="hlt">water</span> quality criteria for the protection of aquatic organisms and their uses. These guidelines provide the method for deriving <span class="hlt">water</span> quality criteria, including minimum data base...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=59667&keyword=teaching+AND+english&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=59667&keyword=teaching+AND+english&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>DEVELOPMENT OF <span class="hlt">MARINE</span> <span class="hlt">WATER</span> QUALITY CRITERIA</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The U.S. Environmental Protectional Agency has developed guidelines for deriving numerical national <span class="hlt">water</span> quality criteria for the protection of aquatic organisms and their uses. These guidelines provide the method for deriving <span class="hlt">water</span> quality criteria, including minimum data base...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6874662','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6874662"><span><span class="hlt">Pore</span> <span class="hlt">water</span> chemistry of an alkaline rift valley lake: Lake Turkana, Kenya</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cerling, T.E.; Johnson, T.C.; Halfman, J.D.; Lister, G.</p> <p>1985-01-01</p> <p>Lake Turkana is the largest closed basin lake in the African rift system. It has evolved through the past 5000 years to become a moderately alkaline lake. Previous mass balance argument suggest that sulfate is removed from the lake by sulfate reduction in the sediments, and that the lake is accumulating in chloride, sodium, and alkalinity. Studies of <span class="hlt">pore</span> <span class="hlt">water</span> from 12 meter cores collected in November 1984 show that sulfate is reduced in the sediment column with a net production of alkalinity. Some sodium is lost from the lake and diffuses into the sediment to maintain charge balance. At several meters depth, organic matter is destroyed by methanogenic bacteria, as shown by the high delta /sup 13/C values for dissolved inorganic carbon. Magnesium and calcium molar ratios change with depth; chloride, sodium, and alkalinity also change with depth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850024431','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850024431"><span>Microanalysis of dissolved iron and phosphate in <span class="hlt">pore</span> <span class="hlt">waters</span> of hypersaline sediment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Haddad, R.; Shaw, T.</p> <p>1985-01-01</p> <p>Diurnal fluctuations of reduced iron concentrations, expected to occur in reduced sediments in the photic zone, were studied. Iron concentration was compared to O2-H2S, a microcanalysis of sulfate reduction was performed, as well as an examination of diurnal concentration of dissolved phosphate and changes in interstitial CO2. The iron profiles suggest a strong correlation between iron remobilization and processes occurring in the light. Phosphate profiles suggest the removal of phosphate is strongly correlated with precipitation of oxidized iron in the upper 2 mm to 5 mm of the sediments. <span class="hlt">Pore</span> <span class="hlt">water</span> CO2 concentrations and carbon isotope ratios are presented. These data are from the analyses of minisediment cores collected from the 42 per mil salt pond and incubated in the laboratory under light and dark conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/936298','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/936298"><span>Micron-<span class="hlt">pore</span>-sized metallic filter tube membranes for filtration of particulates and <span class="hlt">water</span> purification</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Phelps, Tommy Joe; Palumbo, Anthony Vito; Fagan, Lisa Anne; Bischoff, Brian L; Miller, Curtis Jack; Drake, Meghan M; Judkins, Roddie Reagan</p> <p>2008-01-01</p> <p>Robust filtering techniques capable of efficiently removing particulates and biological agents from <span class="hlt">water</span> or air suffer from plugging, poor rejuvenation, low permeance, and high backpressure. Operational characteristics of pressure-driven separations are in part controlled by the membrane <span class="hlt">pore</span> size, charge of particulates, transmembrane pressure and the requirement for sufficient <span class="hlt">water</span> flux to overcome fouling. With long term use filters decline in permeance due to filter-cake plugging of <span class="hlt">pores</span>, fouling, or filter deterioration. Though metallic filter tube development at ORNL has focused almost exclusively on gas separations, a small study examined the applicability of these membranes for tangential filtering of aqueous suspensions of bacterial-sized particles. A mixture of fluorescent polystyrene microspheres ranging in size from 0.5 to 6 {micro}m in diameter simulated microorganisms in filtration studies. Compared to a commercial filter, the ORNL 0.6 {micro}m filter averaged approximately 10-fold greater filtration efficiency of the small particles, several-fold greater permeance after considerable use and it returned to approximately 85% of the initial flow upon backflushing versus 30% for the commercial filter. After filtering several liters of the particle-containing suspension, the ORNL composite filter still exhibited greater than 50% of its initial permeance while the commercial filter had decreased to less than 20%. When considering a greater filtration efficiency, greater permeance per unit mass, greater percentage of rejuvenation upon backflushing (up to 3-fold), and likely greater performance with extended use, the ORNL 0.6 {micro}m filters can potentially outperform the commercial filter by factors of 100-1000 fold.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23722150','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23722150"><span>Plant uptake of elements in soil and <span class="hlt">pore</span> <span class="hlt">water</span>: field observations versus model assumptions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Raguž, Veronika; Jarsjö, Jerker; Grolander, Sara; Lindborg, Regina; Avila, Rodolfo</p> <p>2013-09-15</p> <p>Contaminant concentrations in various edible plant parts transfer hazardous substances from polluted areas to animals and humans. Thus, the accurate prediction of plant uptake of elements is of significant importance. The processes involved contain many interacting factors and are, as such, complex. In contrast, the most common way to currently quantify element transfer from soils into plants is relatively simple, using an empirical soil-to-plant transfer factor (TF). This practice is based on theoretical assumptions that have been previously shown to not generally be valid. Using field data on concentrations of 61 basic elements in spring barley, soil and <span class="hlt">pore</span> <span class="hlt">water</span> at four agricultural sites in mid-eastern Sweden, we quantify element-specific TFs. Our aim is to investigate to which extent observed element-specific uptake is consistent with TF model assumptions and to which extent TF's can be used to predict observed differences in concentrations between different plant parts (root, stem and ear). Results show that for most elements, plant-ear concentrations are not linearly related to bulk soil concentrations, which is congruent with previous studies. This behaviour violates a basic TF model assumption of linearity. However, substantially better linear correlations are found when weighted average element concentrations in whole plants are used for TF estimation. The highest number of linearly-behaving elements was found when relating average plant concentrations to soil <span class="hlt">pore-water</span> concentrations. In contrast to other elements, essential elements (micronutrients and macronutrients) exhibited relatively small differences in concentration between different plant parts. Generally, the TF model was shown to work reasonably well for micronutrients, whereas it did not for macronutrients. The results also suggest that plant uptake of elements from sources other than the soil compartment (e.g. from air) may be non-negligible. Copyright © 2013 Elsevier Ltd. All rights</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17884208','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17884208"><span>Micron-<span class="hlt">pore</span>-sized metallic filter tube membranes for filtration of particulates and <span class="hlt">water</span> purification.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Phelps, T J; Palumbo, A V; Bischoff, B L; Miller, C J; Fagan, L A; McNeilly, M S; Judkins, R R</p> <p>2008-07-01</p> <p>Robust filtering techniques capable of efficiently removing particulates and biological agents from <span class="hlt">water</span> or air suffer from plugging, poor rejuvenation, low permeance, and high backpressure. Operational characteristics of pressure-driven separations are in part controlled by the membrane <span class="hlt">pore</span> size, charge of particulates, transmembrane pressure and the requirement for sufficient <span class="hlt">water</span> flux to overcome fouling. With long term use filters decline in permeance due to filter-cake plugging of <span class="hlt">pores</span>, fouling, or filter deterioration. Though metallic filter tube development at ORNL has focused almost exclusively on gas separations, a small study examined the applicability of these membranes for tangential filtering of aqueous suspensions of bacterial-sized particles. A mixture of fluorescent polystyrene microspheres ranging in size from 0.5 to 6 microm in diameter simulated microorganisms in filtration studies. Compared to a commercial filter, the ORNL 0.6 microm filter averaged approximately 10-fold greater filtration efficiency of the small particles, several-fold greater permeance after considerable use and it returned to approximately 85% of the initial flow upon backflushing versus 30% for the commercial filter. After filtering several liters of the particle-containing suspension, the ORNL composite filter still exhibited greater than 50% of its initial permeance while the commercial filter had decreased to less than 20%. When considering a greater filtration efficiency, greater permeance per unit mass, greater percentage of rejuvenation upon backflushing (up to 3-fold), and likely greater performance with extended use, the ORNL 0.6 microm filters can potentially outperform the commercial filter by factors of 100-1,000 fold.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AtmEn.152..323Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AtmEn.152..323Y"><span>Responses of CO2 emission and <span class="hlt">pore</span> <span class="hlt">water</span> DOC concentration to soil warming and <span class="hlt">water</span> table drawdown in Zoige Peatlands</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Gang; Wang, Mei; Chen, Huai; Liu, Liangfeng; Wu, Ning; Zhu, Dan; Tian, Jianqing; Peng, Changhui; Zhu, Qiuan; He, Yixin</p> <p>2017-03-01</p> <p>Peatlands in Zoige Plateau contains more than half of peatland carbon stock in China. This part of carbon is losing with climate change through dissolved organic carbon (DOC) export and carbon dioxide (CO2) emissions, both of which are vulnerable to the environmental changes, especially on the Zoige Plateau with a pace of twice the observed rate of global climate warming. This research aimed to understand how climate change including soil warming, rainfall reduction and <span class="hlt">water</span> table change affect CO2 emissions and whether the trends of changes in CO2 emission are consistent with those of <span class="hlt">pore</span> <span class="hlt">water</span> DOC concentration. A mesocosm experiment was designed to investigate the CO2 emission and <span class="hlt">pore</span> <span class="hlt">water</span> DOC during the growing seasons of 2009-2010 under scenarios of passive soil warming, 20% rainfall reduction and changes to the <span class="hlt">water</span> table levels. The results showed a positive relationship between CO2 emission and DOC concentration. For single factor effect, we found no significant relationship between <span class="hlt">water</span> table and CO2 emission or DOC concentration. However, temperature at 5 cm depth was found to have positive linear relationship with CO2 emission and DOC concentration. The combined effect of soil warming and rainfall reduction increased CO2 emission by 96.8%. It suggested that the drying and warming could stimulate potential emission of CO2. Extending this result to the entire peatland area in Zoige Plateau translates into 0.45 Tg CO2 emission per year over a growing season. These results suggested that the dryer and warmer Zoige Plateau will increase CO2 emission. We also found the contribution rate of DOC concentration to CO2 emission was increased by 12.1% in the surface layer and decreased by 13.8% in the subsurface layer with combined treatment of soil warming and rainfall reduction, which indicated that the warmer and dryer environmental conditions stimulate surface peat decomposition process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMGC51F1167S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMGC51F1167S"><span>Rare earth elements in <span class="hlt">pore</span> <span class="hlt">waters</span> from Cabo Friós western boundary upwelling system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smoak, J. M.; Silva-Filho, E. V.; Rousseau, T.; Albuquerque, A. L.; Caldeira, P. P.; Moreira, M.</p> <p>2015-12-01</p> <p>Rare earth elements (REE) are a group of reactive trace elements in aqueous media, they have a coherent chemical behavior with however a subtle and gradual shift in physicochemical properties allowing their use as tracers of sources and processes. Uncertainties on their oceanic inputs and outputs still remains [Arsouze et al., 2009; Siddall et al., 2008; Tachikawa et al., 2003]. The <span class="hlt">water</span>-sediment interface were early on identified as a relevant REE source due to the high distribution coefficient between sediments and <span class="hlt">pore</span> <span class="hlt">waters</span> [Elderfield and Sholkovitz, 1987] and substantially higher concentration then the <span class="hlt">water</span> column [Abbott et al., 2015; Haley et al., 2004; Sholkovitz et al., 1989; Soyol-Erdene and Huh, 2013]. Here we present a cross shelf transect of 4 short <span class="hlt">pore</span> <span class="hlt">waters</span> REE profiles on a 680 km2 mud bank located in the region of Cabo Frio, Brazil. This study reveals similar trends at the four sites: a REE production zone reflected by a maximum in concentration at the top of the sediment evolving with depth toward a REE consumption zone reflected by a minimum in REE concentrations. PAAS normalized patterns shows 1) a progressive depletion in LREE with depth with HREE/LREE ratios comprised between 1.1 and 1.6 in the 2 first centimeters evolving gradually to ratios comprised between 2.8 and 4.7 above 7 cm 2) A sharp gradient in negative Ce anomaly with Ce/Ce* values reaching 0.3. With maximum Nd concentrations comprised between 780 and 1200 pmol.kg and considering that seawater Nd concentrations of Brazilian shelf bottom <span class="hlt">waters</span> are comprised between 24 and 50 pmol.Kg-1 we apply the Fick´s First Law of diffusion and estimate that 340 +/- 90 nmol. m-2 Y-1 of Nd is released in the Cabo frio´s mudbank. This flux is in the same order of magnitude of recent estimates by [Abbott et al., 2015] in the slope of Oregon´s margin. Unraveling processes responsible for the REE production zone will help to refine the global REE fluxes estimates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/355543','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/355543"><span>Determination of acute Zn toxicity in <span class="hlt">pore</span> <span class="hlt">water</span> from soils previously treated with sewage sludge using bioluminescence assays</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chaudri, A.M.; Knight, B.P.; Barbosa-Jefferson, V.L.</p> <p>1999-06-01</p> <p>The effects of increasing concentrations of Zn and Cu in soil <span class="hlt">pore</span> <span class="hlt">water</span> from soils of a long-term sewage sludge field experiment on microbial bioluminescence were investigated. Concentrations of total soluble Zn, free Zn{sup 2+}, and soluble Cu increased sharply in soil <span class="hlt">pore</span> <span class="hlt">water</span> with increasing total soil metal concentrations above 140 mg of Zn kg{sup {minus}1} or 100 mg of Cu kg{sup {minus}1}. Two luminescence bioassays were tested, based on two bacteria (Escherichia coli and Pseudomonas fluorescens) with the lux genes encoding bacterial luminescence inserted into them. The bioluminescence response of the two microorganisms declined as total soil Zn, soil <span class="hlt">pore</span> <span class="hlt">water</span> soluble Zn, and soil <span class="hlt">pore</span> <span class="hlt">water</span> free Zn{sup 2+} concentrations increased. The EC{sub 25} values for E. coli and P. fluorescens were 1.3 {+-} 0.2 and 4.3 {+-} 0.5 mg L{sup {minus}1} on a free Zn{sup 2+} basis, respectively. The EC{sub 50} values were 2.5 {+-} 0.2 and 9.6 {+-} 0.9 mg of free Zn{sup 2+} L{sup {minus}1}, respectively. Copper had no significant effect on bioluminescence in the two assays, even at the largest soil <span class="hlt">pore</span> <span class="hlt">water</span> concentration of about 620 {micro}g L{sup {minus}1}, corresponding to a total Cu concentration in bulk soil of about 350 mg kg{sup {minus}1}. Thus, the decline in bioluminescence of the two assays was ascribed to increasing soil <span class="hlt">pore</span> <span class="hlt">water</span> free Zn{sup 2+} and not soluble Cu.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70030383','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030383"><span>Assessing sulfate reduction and methane cycling in a high salinity <span class="hlt">pore</span> <span class="hlt">water</span> system in the northern Gulf of Mexico</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Pohlman, J.W.; Ruppel, C.; Hutchinson, D.R.; Downer, R.; Coffin, R.B.</p> <p>2008-01-01</p> <p><span class="hlt">Pore</span> <span class="hlt">waters</span> extracted from 18 piston cores obtained on and near a salt-cored bathymetric high in Keathley Canyon lease block 151 in the northern Gulf of Mexico contain elevated concentrations of chloride (up to 838 mM) and have <span class="hlt">pore</span> <span class="hlt">water</span> chemical concentration profiles that exhibit extensive departures (concavity) from steady-state (linear) diffusive equilibrium with depth. Minimum ??13C dissolved inorganic carbon (DIC) values of -55.9??? to -64.8??? at the sulfate-methane transition (SMT) strongly suggest active anaerobic oxidation of methane (AOM) throughout the study region. However, the nonlinear <span class="hlt">pore</span> <span class="hlt">water</span> chemistry-depth profiles make it impossible to determine the vertical extent of active AOM or the potential role of alternate sulfate reduction pathways. Here we utilize the conservative (non-reactive) nature of dissolved chloride to differentiate the effects of biogeochemical activity (e.g., AOM and/or organoclastic sulfate reduction) relative to physical mixing in high salinity Keathley Canyon sediments. In most cases, the DIC and sulfate concentrations in <span class="hlt">pore</span> <span class="hlt">waters</span> are consistent with a conservative mixing model that uses chloride concentrations at the seafloor and the SMT as endmembers. Conservative mixing of <span class="hlt">pore</span> <span class="hlt">water</span> constituents implies that an undetermined physical process is primarily responsible for the nonlinearity of the <span class="hlt">pore</span> <span class="hlt">water</span>-depth profiles. In limited cases where the sulfate and DIC concentrations deviated from conservative mixing between the seafloor and SMT, the ??13C-DIC mixing diagrams suggest that the excess DIC is produced from a 13C-depleted source that could only be accounted for by microbial methane, the dominant form of methane identified during this study. We conclude that AOM is the most prevalent sink for sulfate and that it occurs primarily at the SMT at this Keathley Canyon site.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMPP14B..03H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMPP14B..03H"><span>Ca Isotopes in Shallow <span class="hlt">Water</span> <span class="hlt">Marine</span> Carbonates - How I Learned to Stop Worrying and Embrace Diagenesis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Higgins, J. A.; Blättler, C. L.; Swart, P. K.; Santiago Ramos, D. P.; Akhtar, A.</p> <p>2016-12-01</p> <p>The geochemistry of shallow <span class="hlt">water</span> carbonate sediments has been used to reconstruct the temperature and isotopic composition of seawater as well as the global carbon and oxygen cycles over >3 billion years of Earth history. An underlying and heavily debated assumption in most studies utilizing the chemistry of carbonate minerals is that the chemical composition of the sample accurately preserves a record of the fluid from which it precipitated. Diagenetic or post-depositional alteration of the geochemistry by either meteoric or <span class="hlt">marine</span> fluids is a widespread phenomenon in modern and recent shallow and deep-sea carbonate sediments. Diagenetic alteration is observed at all scales, from micron, to thin section, to stratigraphic units, making it difficult to quantify its effects on the geochemistry of carbonate sediments in the geologic record. Here we explore the possibility of using the Ca isotopic composition of sedimentary carbonates as a diageneitc tool using a large data set of Neogene carbonate sediments and associated <span class="hlt">pore</span> fluids from the Bahamas. We find that the δ44/40Ca values of bulk carbonate sediments at these sites exhibits systematic stratigraphic variability that is related to both mineralogy and diagenesis (<span class="hlt">marine</span> and meteoric). The observed variability in bulk sediment Ca isotopes requires large-scale fluid-dominated early <span class="hlt">marine</span> diagenesis in significant <span class="hlt">water</span> depths (up to 650 mbsl) and suggests that fluid-dominated early <span class="hlt">marine</span> diagenesis plays a fundamental role in determining the geochemistry (δ13C, δ18O, and trace elements) of shallow <span class="hlt">water</span> carbonate sediments in the geologic record.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA603989','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA603989"><span>The Determination of Sediment Polycyclic Aromatic Hydrocarbon (PAH) Bioavailability using Direct <span class="hlt">Pore</span> <span class="hlt">Water</span> Analysis by Solid-Phase Microextraction (SPME)</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2010-08-01</p> <p>sample of sediment (20 ml to < 40 ml ) to provide PAH concentration data of sediment <span class="hlt">pore</span> <span class="hlt">water</span>, which has been shown to be correlated to the results...of carbon that might be present, 2) enable the collection of a very small quantity of sediment (20 to 40 ml ), and 3) provide low detection limits in...the analysis of PAHs in <span class="hlt">pore</span> <span class="hlt">water</span> (pg/ ml or ppt). The method developed by the SCBA is EPA SW-846 Method SW-8272 and ASTM Method D-7363-07</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PCE....36.1817S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PCE....36.1817S"><span>Testing geochemical models of bentonite <span class="hlt">pore</span> <span class="hlt">water</span> evolution against laboratory experimental data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Savage, David; Arthur, Randy; Watson, Claire; Wilson, James; Strömberg, Bo</p> <p></p> <p>The determination of a bentonite <span class="hlt">pore</span> <span class="hlt">water</span> composition and understanding its evolution with time underpins many radioactive waste disposal issues, such as buffer erosion, canister corrosion, and radionuclide solubility, sorption, and diffusion, inter alia. Previous modelling approaches have tended to ignore clay dissolution-precipitation reactions, a consequence of which is that montmorillonite is theoretically preserved indefinitely in the repository system. Here, we investigate the applicability of an alternative clay <span class="hlt">pore</span> fluid evolution model, that incorporates clay dissolution-precipitation reactions as an integral component and test it against well-characterised laboratory experimental data, where key geochemical parameters, Eh and pH, have been measured directly in compacted bentonite. Simulations have been conducted using different computer codes (Geochemist’s Workbench, PHREEQC, and QPAC) to test the applicability of this model. Thermodynamic data for the Gibb’s free energy of formation of MX-80 smectite used in the calculations were estimated using two different methods (‘Polymer’ and ‘Vieillard’ Models). Simulations of ‘end-point’ pH measurements in batch bentonite-<span class="hlt">water</span> slurry experiments showed different pH values according to the complexity of the system studied. The most complete system investigated revealed pH values were a strong function of partial pressure of carbon dioxide, with pH increasing with decreasing PCO 2 (with log PCO 2 values ranging from -3.5 to -7.5 bars produced pH values ranging from 7.9 to 9.6). A second set of calculations investigated disequilibrium between clay and <span class="hlt">pore</span> fluid in laboratory squeezing cell tests involving pure <span class="hlt">water</span> (pH = 9.0) or a 1 M NaOH solution (pH = 12.1). Simulations carried out for 100 days (the same timescale as the experiments) showed that smectite remained far from equilibrium throughout, and that the lowering of pH due to smectite hydrolysis was trivial. However, extending the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C43A0787M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C43A0787M"><span>Low Methane Concentrations in Sediment Along the Siberian Slope: Inference From <span class="hlt">Pore</span> <span class="hlt">Water</span> Geochemistry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miller, C.; Dickens, G. R.; Jakobsson, M.</p> <p>2015-12-01</p> <p>The Eastern Siberian Arctic Ocean (ESAO) is experiencing some of the fastest rates of climate warming. Additionally, the ESAO hosts 80% of the world's subsea permafrost, and presumably holds large amounts of methane in sediments as gas hydrate and free gas. Despite these vast stores of vulnerable carbon, the ESAO is sparingly explored. Here, we present <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry results from cores taken during the SWERUS-C3 international expedition and along five transects. Four of these are along the slopes of Arlis Spur, Central East Siberia, Henrietta Island-Makarov Basin, and Eastern Lomonosov Ridge; one is along the shelf in Herald Trough.Upward methane flux toward the seafloor, as inferred from dissolved sulfate and alkalinity profiles, is negligible on slopes the Arlis Spur, Central East Siberia, and Eastern Lomonosov Ridge. Methane flux from slopes near Henrietta Island and Makarov Basin ranged from 13.7 (367 m <span class="hlt">water</span> depth) to 16.2 mmol/m2-kyr (964 m <span class="hlt">water</span> depth). The highest flux on the slope, located at the intersection with Lomonosov Ridge, is 25.8 mmol/m2-kyr. In contrast to the generally low methane fluxes of the continental slope, the shelf sediments in Herald Trough have high upward methane fluxes, with measured rates up to 156.9 mmol/m2-kyr. These methane results are the first of their kind in this climatically sensitive region, and contradict previous assumptions regarding high methane flux rates along the slope.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.G51A0940B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.G51A0940B"><span>A Mechanism for Seismically Induced <span class="hlt">Pore</span> Pressure Changes Inferred from High Frequency <span class="hlt">Water</span> Well Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brodsky, E. E.; Roeloffs, E.; Woodcock, D.; Gall, I.; Manga, M.</p> <p>2002-12-01</p> <p>Earthquakes can produce <span class="hlt">water</span> level changes in certain distant wells orders of magnitude larger than can be explained by static stress changes. The redistribution of <span class="hlt">pore</span> pressure can generate crustal deformation and perhaps even trigger seismicity. Some studies suggest that earthquakes induce permeability increases or other aquifer property changes. Standard hydrogeological methods do not continuously measure aquifer properties therefore it is difficult to monitor the inferred variations. We developed a new method to measure aquifer properties over short times by combining high-sample rate <span class="hlt">water</span> level data (1 sps) and seismic data for a site near Grants Pass Oregon. The new method motivates a new model in which the seismic waves remove transient barriers of sediment in a fracture. Pumping test data for the site is well-modeled by a single, infinitesimally thin square planar fracture embedded in a unbounded, homogeneous and isotropic confined aquifer. For this geometry, the amplification factor χ, defined as the ratio of the <span class="hlt">water</span> level amplitude to the ground velocity, as a function of frequency f is \\[ χ = A(\</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040090001&hterms=water+temperature+depth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dwater%2Btemperature%2Bdepth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040090001&hterms=water+temperature+depth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dwater%2Btemperature%2Bdepth"><span>Method for determining stable isotope ratios of dissolved organic carbon in interstitial and other natural <span class="hlt">marine</span> <span class="hlt">waters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bauer, J. E.; Haddad, R. I.; Des Marais, D. J.</p> <p>1991-01-01</p> <p>A procedure is described for the analysis of the stable carbon isotopic composition of dissolved organic carbon (DOC) in natural <span class="hlt">waters</span> from <span class="hlt">marine</span> and higher-salinity environments. Rapid (less than 5 min) and complete oxidation of DOC is achieved using a modification of previous photochemical oxidation techniques. The CO2 evolved from DOC oxidation can be collected in less than 10 min for isotopic analysis. The procedure is at present suitable for oxidation and collection of 1-5 micromoles of carbon and has an associated blank of 0.1-0.2 micromole of carbon. Complete photochemical oxidation of DOC standards was demonstrated by quantitative recovery of CO2 as measured manometrically. Isotopic analyses of standards by photochemical and high-temperature sealed-tube combustion methods agreed to within 0.3%. Photochemical oxidation of DOC in a representative sediment <span class="hlt">pore-water</span> sample was also quantitative, as shown by the excellent agreement between the photochemical and sealed-tube methods. The delta 13C values obtained for <span class="hlt">pore-water</span> DOC using the two methods of oxidation were identical, suggesting that the modified photochemical method is adequate for the isotopically non-fractionated oxidation of <span class="hlt">pore-water</span> DOC. The procedure was evaluated through an analysis of DOC in pond and <span class="hlt">pore</span> <span class="hlt">waters</span> from a hypersaline microbial mat environment. Concentrations of DOC in the <span class="hlt">water</span> column over the mat displayed a diel pattern, but the isotopic composition of this DOC remained relatively constant (average delta 13C = -12.4%). <span class="hlt">Pore-water</span> DOC exhibited a distinct concentration maximum in the mat surface layer, and delta 13C of <span class="hlt">pore-water</span> DOC was nearly 8% lighter at 1.5-2.0-cm depth than in the mat surface layer (0-0.5-cm depth). These results demonstrate the effectiveness of the method in elucidating differences in DOC concentration and delta 13C over biogeochemically relevant spatial and temporal scales. Carbon isotopic analysis of DOC in natural <span class="hlt">waters</span>, especially <span class="hlt">pore</span> <span class="hlt">waters</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA461868','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA461868"><span>Impact of a Hydrate-Based <span class="hlt">Marine</span> Desalination Technology on <span class="hlt">Marine</span> Microbiota and <span class="hlt">Water</span> Quality</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2006-12-27</p> <p>natural bacterial assemblage in primarily two ways: metabolic rate (production) and assemblage composition. Changing <span class="hlt">water</span> quality can impact the...of the process <span class="hlt">water</span> that was inhibitory to bacterial metabolism of natural <span class="hlt">marine</span> assemblages. Among the possible inhibiting factors is pH, low...assemblage adaptation in PAH -impacted ecosystems. In B. C. Alleman and A. Leeson (eds.) In Situ and On-Site Bioremediation. Battelle Press, Columbus, OH</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JSCGE..67..464Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JSCGE..67..464Y"><span>MONITORING OF <span class="hlt">PORE</span> <span class="hlt">WATER</span> PRESSURE AND <span class="hlt">WATER</span> CONTENT AROUND A HORIZONTAL DRIFT THROUGH EXCAVATION - MEASUREMENT AT THE 140m GALLERY IN THE HORONOBE URL -</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yabuuchi, Satoshi; Kunimaru, Takanori; Kishi, Atsuyasu; Komatsu, Mitsuru</p> <p></p> <p>Japan Atomic Energy Agency has been conducting the Horonobe Underground Research Laboratory (URL) project in Horonobe, Hokkaido, as a part of the research and development program on geological disposal of high-level radioactive waste. <span class="hlt">Pore</span> <span class="hlt">water</span> pressure and <span class="hlt">water</span> content around a horizontal drift in the URL have been monitored for over 18 months since before the drift excavation was started. During the drift excavation, both <span class="hlt">pore</span> <span class="hlt">water</span> pressure and <span class="hlt">water</span> content were decreasing. <span class="hlt">Pore</span> <span class="hlt">water</span> pressure has been still positive though it continued to decrease with its gradient gradually smaller after excavation, while <span class="hlt">water</span> content turned to increase about 6 months after the completion of the excavation. It turned to fall again about 5 months later. An unsaturated zone containing gases which were dissolved in groundwater may have been formed around the horizontal drift.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.7687R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.7687R"><span><span class="hlt">Marine</span> <span class="hlt">water</span> quality under climate change conditions/scenarios</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rizzi, Jonathan; Torresan, Silvia; Critto, Andrea; Zabeo, Alex; Brigolin, Daniele; Carniel, Sandro; Pastres, Roberto; Marcomini, Antonio</p> <p>2016-04-01</p> <p>The increase of sea temperature and the changes in <span class="hlt">marine</span> currents are generating impacts on coastal <span class="hlt">waters</span> such as changes in <span class="hlt">water</span> biogeochemical and physical parameters (e.g. primary production, pH, salinity) leading to progressive degradation of the <span class="hlt">marine</span> environment. With the main aim of analysing the potential impacts of climate change on coastal <span class="hlt">water</span> quality, a Regional Risk Assessment (RRA) methodology was developed and applied to coastal <span class="hlt">marine</span> <span class="hlt">waters</span> of the North Adriatic (i.e. coastal <span class="hlt">water</span> bodies of the Veneto and Friuli Venezia Giulia regions, Italy). RRA integrates the outputs of regional models providing information on macronutrients (i.e. dissolved inorganic nitrogen e reactive phosphorus), dissolved oxygen, pH, salinity and temperature, etc., under future climate change scenarios with site-specific environmental and socio-economic indicators (e.g. biotic index, presence and extension of seagrasses, presence of aquaculture). The presented approach uses Geographic Information Systems to manage, analyse, and visualize data and employs Multi-Criteria Decision Analysis for the integration of stakeholders preferences and experts judgments into the evaluation process. RRA outputs are hazard, exposure, vulnerability, risk and damage maps useful for the identification and prioritization of hot-spot areas and vulnerable targets in the considered region. Therefore, the main aim of this contribution is to apply the RRA methodology to integrate, visualize, and rank according to spatial distribution, physical and chemical data concerning the coastal <span class="hlt">waters</span> of the North Adriatic Sea in order to predict possible changes of the actual <span class="hlt">water</span> quality.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25892066','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25892066"><span>Analysis of intracellular and extracellular microcystin variants in sediments and <span class="hlt">pore</span> <span class="hlt">waters</span> by accelerated solvent extraction and high performance liquid chromatography-tandem mass spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zastepa, Arthur; Pick, Frances R; Blais, Jules M; Saleem, Ammar</p> <p>2015-05-04</p> <p>The fate and persistence of microcystin cyanotoxins in aquatic ecosystems remains poorly understood in part due to the lack of analytical methods for microcystins in sediments. Existing methods have been limited to the extraction of a few extracellular microcystins of similar chemistry. We developed a single analytical method, consisting of accelerated solvent extraction, hydrophilic-lipophilic balance solid phase extraction, and reversed phase high performance liquid chromatography-tandem mass spectrometry, suitable for the extraction and quantitation of both intracellular and extracellular cyanotoxins in sediments as well as <span class="hlt">pore</span> <span class="hlt">waters</span>. Recoveries of nine microcystins, representing the chemical diversity of microcystins, and nodularin (a <span class="hlt">marine</span> analogue) ranged between 75 and 98% with one, microcystin-RR (MC-RR), at 50%. Chromatographic separation of these analytes was achieved within 7.5 min and the method detection limits were between 1.1 and 2.5 ng g(-1) dry weight (dw). The robustness of the method was demonstrated on sediment cores collected from seven Canadian lakes of diverse geography and trophic states. Individual microcystin variants reached a maximum concentration of 829 ng g(-1) dw on sediment particles and 132 ng mL(-1) in <span class="hlt">pore</span> <span class="hlt">waters</span> and could be detected in sediments as deep as 41 cm (>100 years in age). MC-LR, -RR, and -LA were more often detected while MC-YR, -LY, -LF, and -LW were less common. The analytical method enabled us to estimate sediment-<span class="hlt">pore</span> <span class="hlt">water</span> distribution coefficients (K(d)), MC-RR had the highest affinity for sediment particles (log K(d)=1.3) while MC-LA had the lowest affinity (log K(d)=-0.4), partitioning mainly into <span class="hlt">pore</span> <span class="hlt">waters</span>. Our findings confirm that sediments serve as a reservoir for microcystins but suggest that some variants may diffuse into overlying <span class="hlt">water</span> thereby constituting a new route of exposure following the dissipation of toxic blooms. The method is well suited to determine the fate and persistence of different</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1812210D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1812210D"><span>Monitoring and Analysis of Transient <span class="hlt">Pore</span> <span class="hlt">Water</span> Pressures in Large Suspended Rock Slides near Poschiavo, CH</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Palézieux, Larissa; Loew, Simon; Zwahlen, Peter</p> <p>2016-04-01</p> <p>Many mountain slopes in the Alps exhibit large compound rock slides or Deep Seated Gravitational Slope Deformations. Due to the basal rupture plane geometry and the cumulative displacement magnitude such landslide bodies are often strongly deformed, highly fractured and - at least locally - very permeable. This can lead to high infiltration rates and low phreatic groundwater tables. This is also the situation in the studied mountain slopes southwest of Poschiavo, where large suspended rockslides occur, with very little surface runoff at high elevations, and torrents developing only at the elevation of the basal rupture planes. Below the landslide toes, at altitudes below ca. 1700 m a.s.l., groundwater appears forming spring lines or distributed spring clusters. Within the scope of the design of a hydropower pump storage plant in the Poschiavo valley by Lagobianco SA (Repower AG), numerous cored and deep boreholes (of 50 to 300 m depth) have been drilled along the planned pressure tunnel alignement at elevations ranging from 963 to 2538 m a.s.l. in the years 2010 and 2012. In several boreholes Lugeon and transient pressure tests were executed and <span class="hlt">pore</span> <span class="hlt">water</span> pressure sensors installed in short monitoring sections at various depths. Most of these boreholes intersect deep rockslides in crystalline rocks and limestones, showing highly fragmented rock masses and cohesionless cataclastic shear zones of several tens of meters thickness. This study explores these borehole observations in landslides and adjacent stable slopes and links them to the general hydrologic and hydrogeologic framework. The analysis of the <span class="hlt">pore</span> <span class="hlt">water</span> pressure data shows significant variability in seasonal trends and short-term events (from snow melt and summer rain storms) and remarkable pressure differences over short horizontal and vertical distances. This reflects rock mass damage within landslide bodies and important sealing horizons at their base. Based on <span class="hlt">water</span> balances, the estimated effective</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5181194','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5181194"><span>The lipid geochemistry of interstitial <span class="hlt">waters</span> of recent <span class="hlt">marine</span> sediments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Saliot, A.; Brault, M.; Boussuge, C. )</p> <p>1988-04-01</p> <p>To elucidate the nature of biogeochemical processes occurring at the <span class="hlt">water</span>-sediment interface, the authors have analyzed fatty acids, n-alkanes and sterols contained in interstitial <span class="hlt">waters</span> collected from oxic and anoxic <span class="hlt">marine</span> sediments in the eastern and western intertropical Atlantic Ocean and in the Arabian Sea. Lipid concentrations in interstitial <span class="hlt">waters</span> vary widely and are generally much higher than concentrations encountered in the overlying sea <span class="hlt">water</span>. Higher concentrations in interstitial <span class="hlt">water</span> are observed in environments favorable for organic input and preservation of the organic matter in the <span class="hlt">water</span> column and in the surficial sediment. The analysis of biogeochemical markers in the various media of occurrence of the organic matter such as sea <span class="hlt">water</span>, suspended particles, settling particles and sediment is discussed in terms of differences existing between these media and bio-transformations of the organic matter at the <span class="hlt">water</span>-sediment interface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23246660','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23246660"><span>Relationships of surface <span class="hlt">water</span>, <span class="hlt">pore</span> <span class="hlt">water</span>, and sediment chemistry in wetlands adjacent to Great Salt Lake, Utah, and potential impacts on plant community health.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carling, Gregory T; Richards, David C; Hoven, Heidi; Miller, Theron; Fernandez, Diego P; Rudd, Abigail; Pazmino, Eddy; Johnson, William P</p> <p>2013-01-15</p> <p>We collected surface <span class="hlt">water</span>, <span class="hlt">pore</span> <span class="hlt">water</span>, and sediment samples at five impounded wetlands adjacent to Great Salt Lake, Utah, during 2010 and 2011 in order to characterize pond chemistry and to compare chemistry with plant community health metrics. We also collected <span class="hlt">pore</span> <span class="hlt">water</span> and sediment samples along multiple transects at two sheet flow wetlands during 2011 to investigate a potential link between wetland chemistry and encroachment of invasive emergent plant species. Samples were analyzed for a suite of trace and major elements, nutrients, and relevant field parameters. The extensive sampling campaign provides a broad assessment of Great Salt Lake wetlands, including a range of conditions from reference to highly degraded. We used nonmetric multidimensional scaling (NMS) to characterize the wetland sites based on the multiple parameters measured in surface <span class="hlt">water</span>, <span class="hlt">pore</span> <span class="hlt">water</span>, and sediment. NMS results showed that the impounded wetlands fall along a gradient of high salinity/low trace element concentrations to low salinity/high trace element concentrations, whereas the sheet flow wetlands have both elevated salinity and high trace element concentrations, reflecting either different sources of element loading or different biogeochemical/hydrological processes operating within the wetlands. Other geochemical distinctions were found among the wetlands, including Fe-reducing conditions at two sites and sulfate-reducing conditions at the remaining sites. Plant community health metrics in the impounded wetlands showed negative correlations with specific metal concentrations in sediment (THg, Cu, Zn, Cd, Sb, Pb, Ag, Tl), and negative correlations with nutrient concentrations in surface <span class="hlt">water</span> (nitrite, phosphate, nitrate). In the sheet flow wetlands, invasive plant species were inversely correlated with <span class="hlt">pore</span> <span class="hlt">water</span> salinity. These results indicate that sediment and <span class="hlt">pore</span> <span class="hlt">water</span> chemistry play an important role in wetland plant community health, and that monitoring and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70021295','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70021295"><span>A mini drivepoint sampler for measuring <span class="hlt">pore</span> <span class="hlt">water</span> solute concentrations in the hyporheic zone of sand-bottom streams</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Duff, J.H.; Murphy, F.; Fuller, C.C.; Triska, F.J.</p> <p>1998-01-01</p> <p>A new method for collecting <span class="hlt">pore-water</span> samples in sand and gravel streambeds is presented. We developed a mini drivepoint solution sampling (MINIPOINT) technique to collect <span class="hlt">pore-water</span> samples at 2.5-cm vertical resolution. The sampler consisted of six small-diameter stainless steel drivepoints arranged in a 10-cm-diameter circular array. In a simple procedure, the sampler was installed in the streambed to preset drivepoint depths of 2.5, 5.0, 7.5, 10.0, 12.5, and 15.0 cm. Sampler performance was evaluated in the Shingobee River, Minnesota, and Pinal Creek, Arizona, by measuring the vertical gradient of chloride concentration in <span class="hlt">pore</span> <span class="hlt">water</span> beneath the streambed that was established by the uninterrupted injection to the stream for 3 d. <span class="hlt">Pore-water</span> samples were withdrawn from all drivepoints simultaneously. In the first evaluation, the vertical chloride gradient was unchanged at withdrawal rates between 0.3 and 4.0 ml min-1 but was disturbed at higher rates. In the second evaluation, up to 70 ml of <span class="hlt">pore</span> <span class="hlt">water</span> was withdrawn from each drivepoint at a withdrawal rate of 2.5 ml min-1 without disturbing the vertical chloride gradient. Background concentrations of other solutes were also determined with MINIPOINT sampling. Steep vertical gradients were present for biologically reactive solutes such as DO, NH4/+, NO3/-, and dissolved organic C in the top 20 cm of the streambed. These detailed solute profiles in the hyporheic zone could not have been determined without a method for close interval vertical sampling that does not disturb natural hydrologic mixing between stream <span class="hlt">water</span> and groundwater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26802565','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26802565"><span>Concentrations, diffusive fluxes and toxicity of heavy metals in <span class="hlt">pore</span> <span class="hlt">water</span> of the Fuyang River, Haihe Basin.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tang, Wenzhong; Duan, Shenghui; Shan, Baoqing; Zhang, Hong; Zhang, Wenqiang; Zhao, Yu; Zhang, Chao</p> <p>2016-05-01</p> <p>While the concentrations of heavy metals in <span class="hlt">pore</span> <span class="hlt">water</span> provide important information about their bioavailability, to date few studies have focused on this topic. In this study, <span class="hlt">pore</span> <span class="hlt">water</span> in river sediments collected from nine sampling sites (S1-S9) was examined to determine the concentrations, fluxes, and toxicity of heavy metals in the Fuyang River. The results showed that the average concentrations of Cr, Ni, Cu, As, Zn, and Pb in <span class="hlt">pore</span> <span class="hlt">water</span> were 17.06, 15.97, 20.93, 19.08, 43.72, and 0.56μgL(-1), respectively; these concentrations varied as the <span class="hlt">pore</span> <span class="hlt">water</span> depth increased. The diffusive fluxes of Cr, Ni, Cu, As, Zn, and Pb were in the following range: (-0.37) to 3.17, (-1.37) to 2.63, (-4.61) to 3.44, 0.17-6.02, (-180.26) to 7.51, and (-0.92) to (-0.29)μg(m(2)day)(-1), respectively. There was a potential risk of toxicity from Cu to aquatic organisms, as indicated by a value of the Interstitial <span class="hlt">Water</span> Criteria Toxic Units that exceeded 1.0. Values of the Nemeraw Index were 2.06, 0.48, 0.11, 0.20, 1.11, 1.03, 0.99, 0.88, and 0.89 from S1 to S9, respectively. Only S1 was moderately polluted by heavy metals in <span class="hlt">pore</span> <span class="hlt">water</span>. Copyright © 2016 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/367433','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/367433"><span>Development of a toxicity-based fractionation approach for the identification of phototoxic PAHs in <span class="hlt">pore</span> <span class="hlt">water</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kosian, P.A.; Makynen, E.A.; Ankley, G.T.; Monson, P.D.</p> <p>1995-12-31</p> <p>Environmental matrices often contain complex mixtures of chemical compounds, however, typically only a few chemicals are responsible for observed toxicity. To determine those chemicals responsible for toxicity, a toxicity-based fractionation technique coupled with gas chromatography/mass spectrometry (GC/MS) has been used for the isolation and identification of nonpolar toxicants in aqueous samples. In this study, this technique was modified to separate and identify polycyclic aromatic hydrocarbons (PAHs) responsible for phototoxicity in <span class="hlt">pore</span> <span class="hlt">water</span>. Whole <span class="hlt">pore</span> <span class="hlt">water</span>, obtained from sediments collected near an oil refinery discharge site, was found to be toxic to Lumbriculus variegatus in the presence of ultraviolet (UV) light. Solid phase extraction disks and high pressure liquid chromatography were used, in conjunction with toxicity tests with L. variegatus, to extract and fractionate phototoxic chemicals from the <span class="hlt">pore</span> <span class="hlt">water</span>. GC/MS analysis was performed on the toxic fractions and a tentative list of compound identifications were made based on interpretation of mass spectra and elution information from the chromatographic separation. The compounds identified include PAHs and substituted PAHs that are known or predicted to be phototoxic in the presence of UV light. The results show that a modified toxicity-based fractionation approach can be successfully applied to identify phototoxic PAHs in sediment <span class="hlt">pore</span> <span class="hlt">water</span> and therefore used in the assessment of contaminated sediments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.6356P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.6356P"><span>Early cements versus <span class="hlt">pore-water</span> chemical composition in the subsurface of the sabkha of Abu Dhabi</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Paul, Andreas; Yuan, Peng; Court, Wesley M.; Lokier, Stephen W.; Dutton, Kirsten E.; Van der Land, Cees; Lessa Andrade, Luiza; Sherry, Angela; Head, Ian M.</p> <p>2017-04-01</p> <p>The coastal sabkha of Abu Dhabi is a complex depositional system in an extremely arid climate. This depositional system is marked by the formation of primary carbonate and microbial deposits, and by the development of secondary evaporite and cement phases. A number of earlier studies have assessed the formation of these secondary phases, yet no research has established a relationship between lateral and vertical variations in the chemical composition of <span class="hlt">pore</span> <span class="hlt">water</span> and the nature of, in particular, the precipitating <span class="hlt">pore</span>-filling cements, re-crystallisation features and dissolution. This study aims to establish an understanding of the environmental and sedimentary factors that control early post-depositional changes to sediment composition as a result of sediment - <span class="hlt">pore</span> <span class="hlt">water</span> interactions. A particular focus is to characterise changes in the chemistry of the <span class="hlt">pore</span> <span class="hlt">water</span> throughout a tidal cycle, aiming at understanding how the influx of 'fresh' lagoonal sea <span class="hlt">water</span> influences the chemistry of the <span class="hlt">pore</span> <span class="hlt">water</span>, and which elements are replenished on a daily basis. The initial data presented here is based upon the relationship between the petrographic analysis of sediment samples and lateral and vertical variations in the chemistry of in-situ sampled <span class="hlt">pore</span> <span class="hlt">water</span>. The <span class="hlt">pore</span> <span class="hlt">water</span> is characterised with respect to pH, salinity, alkalinity, dissolved organic carbon, and the concentrations of a variety of common metallic and non-metallic elements, including (but not limited to) Ca, Fe, Mg, P, S and Sr. Initial results show that concentrations of Mg, P, and V, and the ratios Mg/Ca and Sr/Ca are highest at the seaward sampling locations. Contrastingly, individual concentrations for Ca, Sr, Fe, Si, and Cu are highest at the most landward locality. In particular the higher concentrations for Ca and Sr might indicate diagenetic processes and are thus enriched as a result of e.g. aragonite dissolution. A striking pattern in Mg concentrations show the highest values for this element</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16678886','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16678886"><span>The impact of sampling techniques on soil <span class="hlt">pore</span> <span class="hlt">water</span> carbon measurements of an Icelandic Histic Andosol.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sigfusson, Bergur; Paton, Graeme I; Gislason, Sigurdur R</p> <p>2006-10-01</p> <p>The carbon in soil <span class="hlt">pore</span> <span class="hlt">water</span> from a Histic Andosol from Western Iceland was studied at three different scales; in the field, in undisturbed outdoor mesocosms and in laboratory repacked microcosms. <span class="hlt">Pore</span> <span class="hlt">water</span> was extracted using suction cup lysimeters and hollow-fibre tube sampler devices (Rhizon samplers). There were significant differences in all measured variables, dissolved inorganic carbon (DIC), dissolved organic carbon (DOC) and pH values between the scales of the experiment. Gaseous constituents of soil solution and pH were more susceptible to changes in scale and the type of sampling devices used. Dissolved inorganic carbon concentrations did not differ significantly between field and mesocosm solutions but where up to 14 times lower in microcosms compared to mesocosms solutions. Rhizon samplers yielded solutions with up to 4.7 times higher DIC concentrations than porous cup lysimeters. Mesocosm surface horizon DOC concentrations were 20 and 2 times higher than in field and microcosms respectively. There was difference in DOC concentration between sampling methods (up to 8 times higher in suction cups than rhizon samplers) above 50 cm depth. Soil solution pH values did not differ between field and mesocosms and mesocosms and microcosms respectively down to 80 cm depth. Direct comparison between field and microcosms was not possible due to the nature of sampling devices. Soil solutions sampled with Rhizon samplers yielded lower pH values (up to 1.3 pH units) than those sampled with suction cups. Twenty percent of annually bound organic carbon at the soils surface under field conditions was lost by leaching of DOC and through decomposition to DIC in disturbed non-vegetated microcosms. This percentage increased to 38% in undisturbed vegetated mesocosms highlighting the importance of surface vegetation in importing carbon to soils. Increased influx of nutrients will increase growth and photosynthesis but decrease carbon sequestration in near surface horizons</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUSM.H33B..05B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUSM.H33B..05B"><span>Diffusion of Nutrients in an Isolated Wetland Resulting From Shallow <span class="hlt">Pore</span> <span class="hlt">Water</span> Gradients Affected by Antecedent Soil Conditions.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bhadha, J. H.; Jawitz, J. W.; Dunne, E. J.; Perkins, D. B.</p> <p>2007-05-01</p> <p>Historically sequestered nutrients in wetland soils may be gradually released to the <span class="hlt">water</span> column through the process commonly referred to as internal loading. The watershed for Lake Okeechobee, FL (USA) is heavily agricultural and excess nutrients in this area are drained to the Lake by ditches and canals. Formerly isolated, wetlands in this area have also been extensively ditched and drained. In this study, diffusive fluxes of nutrients were calculated using Fick's First Law from shallow <span class="hlt">pore</span> <span class="hlt">water</span> gradients, and later compared to fluxes measured by an incubated laboratory experiment on 10-cm intact soil cores from the same sites. Three intact soil cores from a wetland located on an operational beef farm were used to measure total phosphorus (TP), along with soil properties such as porosity, bulk density, and pH. Simultaneously, <span class="hlt">pore</span> <span class="hlt">water</span> concentrations of total organic carbon (TOC), total Kjeldahl nitrogen (TKN), and soluble reactive phosphorus (SRP) were also measured at the same three sites for a period of twelve months, and compared to surface <span class="hlt">water</span> concentrations during flooded periods. A strong correlation between concentration gradients in <span class="hlt">pore</span> <span class="hlt">water</span> SRP and those observed in soil TP, suggests that shallow <span class="hlt">pore</span> <span class="hlt">water</span> concentrations reflect antecedent soil conditions. If this is true, then fluxes associated with diffusion and advection could greatly affect the total ground <span class="hlt">water</span> fluxes across the soil-<span class="hlt">water</span> interface. Fickian diffusive fluxes, estimated six times over a twelve month sampling period, were found to vary between 7-38 mg.m-2.d-1 for TOC, 1-18 mg.m-2.d-1 for TKN, and 0.04-0.86 mg.m-2.d-1 for SRP. While factors such as wetland stage and hydroperiod may have affected the fluxes, it is ultimately the concentration gradients across the soil-<span class="hlt">water</span> interface that drives diffusive fluxes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19760039151&hterms=Seismic+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DSeismic%2Bwaves','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19760039151&hterms=Seismic+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DSeismic%2Bwaves"><span>The effects of pressure, temperature, and <span class="hlt">pore</span> <span class="hlt">water</span> on velocities in Westerly granite. [for seismic wave propagation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Spencer, J. W., Jr.; Nur, A. M.</p> <p>1976-01-01</p> <p>A description is presented of an experimental assembly which has been developed to conduct concurrent measurements of compressional and shear wave velocities in rocks at high temperatures and confining pressures and with independent control of the <span class="hlt">pore</span> pressure. The apparatus was used in studies of the joint effects of temperature, external confining pressure, and internal <span class="hlt">pore</span> <span class="hlt">water</span> on sonic velocities in Westerly granite. It was found that at a given temperature, confining pressure has a larger accelerating effect on compressional waves in dry rock, whereas at a given confining pressure, temperature has a larger retarding effect on shear waves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12714300','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12714300"><span>Chemical analyses of <span class="hlt">pore</span> <span class="hlt">water</span> from boreholes USW SD-6 and USW WT-24, Yucca Mountain, Nevada.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, In C; Peterman, Zell E; Scofield, Kevin M</p> <p>2003-01-01</p> <p>Analyses of <span class="hlt">pore</span> <span class="hlt">water</span> extracted from cores of boreholes USW SD-6 in the central part and USW WT-24 in the northern part of Yucca Mountain, Nevada, show significant vertical and lateral variations in dissolved-ion concentrations. Analyses of samples of only a few milliliters of <span class="hlt">pore</span> <span class="hlt">water</span> extracted by uniaxial or triaxial compression and by ultracentrifugation methods from adjacent core samples are generally in agreement, within the analytical error of 10% to 15%. However, the values of silica for <span class="hlt">water</span> obtained by ultracentrifugation are consistently lower than values for <span class="hlt">water</span> obtained by compression. The larger concentrations probably are due to localized pressure solution of silicate minerals during compression. The shallower <span class="hlt">water</span> from core in borehole USW SD-6 was extracted from nonwelded units collectively referred to as the Paintbrush Tuff nonwelded (PTn). The deeper <span class="hlt">water</span> was from core in both boreholes USW SD-6 and USW WT-24 in the nonwelded units referred to as the Calico Hills nonwelded (CHn). Significant differences in mean dissolved-ion concentrations in <span class="hlt">pore</span> <span class="hlt">water</span> between the PTn and CHn are (1) decreases in Ca, Mg, SO(4), and NO(3) and (2) increases in HCO(3) and (Na+K)/(Ca+Mg) ratios. The decrease in NO(3) and the increase in HCO(3) could be the result of denitrification through the oxidation of organic matter. The decrease in Ca and associated increase in (Na+K)/(Ca+Mg) is the result of ion exchange with zeolites in the CHn in borehole USW WT-24. This effect is not nearly as pronounced in borehole USW SD-6, probably reflecting a smaller amount of zeolitization of the CHn in USW SD-6. Geochemical calculations using the PHREEQC code indicate that the <span class="hlt">pore</span> <span class="hlt">water</span> from both boreholes USW SD-6 and USW WT-24 is uniformly undersaturated in anhydrite, gypsum, and amorphous silica, but supersaturated in quartz and chalcedony. The saturation of calcite, aragonite, sepiolite, and dolomite is more variable from sample to sample.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18688535','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18688535"><span>Melting behavior of <span class="hlt">water</span> in cylindrical <span class="hlt">pores</span>: carbon nanotubes and silica glasses.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sliwinska-Bartkowiak, M; Jazdzewska, M; Huang, L L; Gubbins, K E</p> <p>2008-08-28</p> <p>We report a study of the effects of confinement in multi-walled carbon nanotubes and mesoporous silica glasses (SBA-15) on the solid structure and melting of both H(2)O and D(2)O ice, using differential scanning calorimetry, dielectric relaxation spectroscopy, and neutron diffraction. Multi-walled nanotubes of 2.4, 3.9 and 10 nm are studied, and the SBA-15 studied has <span class="hlt">pores</span> of mean diameter 3.9 nm; temperatures ranging from approximately 110 to 290 K were studied. We find that the melting point is depressed relative to the bulk <span class="hlt">water</span> for all systems studied, with the depression being greater in the case of the silica mesopores. These results are shown to be consistent with molecular simulation studies of freezing in silica and carbon materials. The neutron diffraction data show that the cubic phase of ice is stabilized by the confinement in carbon nanotubes, as well as in silica mesopores, and persists up to temperatures of about 240 K, above which there is a transition to the hexagonal ice structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22571231','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22571231"><span>Level and degradation of Deepwater Horizon spilled oil in coastal marsh sediments and <span class="hlt">pore-water</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Natter, Michael; Keevan, Jeff; Wang, Yang; Keimowitz, Alison R; Okeke, Benedict C; Son, Ahjeong; Lee, Ming-Kuo</p> <p>2012-06-05</p> <p>This research investigates the level and degradation of oil at ten selected Gulf saltmarsh sites months after the 2010 BP Macondo-1 well oil spill. Very high levels (10-28%) of organic carbon within the heavily oiled sediments are clearly distinguished from those in pristine sediments (<3%). Dissolved organic carbon in contaminated <span class="hlt">pore-waters</span>, ranging up to hundreds of mg/kg, are 1 to 2 orders of magnitude higher than those at pristine sites. Heavily oiled sediments are characterized by very high sulfide concentrations (up to 80 mg/kg) and abundance of sulfate reducing bacteria. Geochemical biomarkers and stable carbon isotope analyses fingerprint the presence of oils in sediments. Ratios of selected parameters calculated from the gas chromatograph spectra are in a remarkable narrow range among spilled oils and initial BP crude. At oiled sites dominated by C(4) plants, δ(13)C values of sediments (-20.8 ± 2.0‰) have been shifted significantly lower compared to marsh plants (-14.8 ± 0.6‰) due to the inflow of isotopically lighter oil (-27 ± 0.2‰). Our results show that (1) lighter compounds of oil are quickly degraded by microbes while the heavier fractions of oil still remain and (2) higher inputs of organic matter from the oil spill enhance the key microbial processes associated with sulfate reducing bacteria.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1611775L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1611775L"><span>Estimation of <span class="hlt">water</span> saturated permeability of soils, using 3D soil tomographic images and <span class="hlt">pore</span>-level transport phenomena modelling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lamorski, Krzysztof; Sławiński, Cezary; Barna, Gyöngyi</p> <p>2014-05-01</p> <p>There are some important macroscopic properties of the soil porous media such as: saturated permeability and <span class="hlt">water</span> retention characteristics. These soil characteristics are very important as they determine soil transport processes and are commonly used as a parameters of general models of soil transport processes used extensively for scientific developments and engineering practise. These characteristics are usually measured or estimated using some statistical or phenomenological modelling, i.e. pedotransfer functions. On the physical basis, saturated soil permeability arises from physical transport processes occurring at the <span class="hlt">pore</span> level. Current progress in modelling techniques, computational methods and X-ray micro-tomographic technology gives opportunity to use direct methods of physical modelling for <span class="hlt">pore</span> level transport processes. Physically valid description of transport processes at micro-scale based on Navier-Stokes type modelling approach gives chance to recover macroscopic porous medium characteristics from micro-flow modelling. <span class="hlt">Water</span> microflow transport processes occurring at the <span class="hlt">pore</span> level are dependent on the microstructure of porous body and interactions between the fluid and the medium. In case of soils, i.e. the medium there exist relatively big <span class="hlt">pores</span> in which <span class="hlt">water</span> can move easily but also finer <span class="hlt">pores</span> are present in which <span class="hlt">water</span> transport processes are dominated by strong interactions between the medium and the fluid - full physical description of these phenomena is a challenge. Ten samples of different soils were scanned using X-ray computational microtomograph. The diameter of samples was 5 mm. The voxel resolution of CT scan was 2.5 µm. Resulting 3D soil samples images were used for reconstruction of the <span class="hlt">pore</span> space for further modelling. 3D image threshholding was made to determine the soil grain surface. This surface was triangulated and used for computational mesh construction for the <span class="hlt">pore</span> space. Numerical modelling of <span class="hlt">water</span> flow through the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.H51A0561Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.H51A0561Z"><span>Interaction of Ammonia Gas with Sediments and <span class="hlt">Pore</span> <span class="hlt">Water</span> and Induced Uranium Immobilization under Vadose Zone Conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhong, L.; Szecsody, J. E.; Truex, M. J.</p> <p>2014-12-01</p> <p>Preliminary studies have demonstrated the potential of ammonia gas (NH3) treatment on contaminated sediment as a vadose zone uranium remediation approach. In this work, we conducted batch, column, and flow wedge experiments to study the ammonia gas transport and interaction with sediments and <span class="hlt">pore</span> <span class="hlt">water</span>. The uranium immobilization effectiveness of the ammonia gas treatment technology was also evaluated. Ammonia gas quickly partitions into sediment <span class="hlt">pore</span> <span class="hlt">water</span> and significantly increases the pH (up to ~13.2) and the electrical conductivity (EC). The rate and range of the increase in both pH and EC are dependent on the ammonia concentration in the gas and the <span class="hlt">pore</span> <span class="hlt">water</span> content and chemistry. The pH and EC changes follow a similar pattern. During an ammonia gas injection into a heterogeneous system, it was observed that the NH3 front proceeded faster in layers of lower <span class="hlt">water</span> content compared to the same sediment layers of higher <span class="hlt">water</span> content. Elevated pH values (11 to 13.2) initially resulted from the NH3 gas partitioning into the <span class="hlt">pore</span> <span class="hlt">water</span> was buffered down to ~ 9 after 7 months of sediment exposure to the air. The rate of NH3 diffusion in sediment is a function of the <span class="hlt">water</span> content in the sediment. Higher cation/anion concentrations during the ammonia gas treatment indicated mineral dissolution due to pH increase, while lower ionic concentrations after the pH buffering revealed significant mineral precipitation. This precipitation incorporates uranium into mineral structures or provides a coating to uranium minerals, therefore achieving uranium immobilization. Treatment with 5% v/v NH3 gas for one week followed by three weeks buffering resulted in a 75% reduction in the mobile uranium mass. After 2 to 12 months of treatment, the immobile phase of uranium mass increased by up to 2.3 times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27541153','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27541153"><span>Distribution, diffusive fluxes, and toxicity of heavy metals and PAHs in <span class="hlt">pore</span> <span class="hlt">water</span> profiles from the northern bays of Taihu Lake.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lei, Pei; Zhang, Hong; Shan, Baoqing; Zhang, Bozheng</p> <p>2016-11-01</p> <p><span class="hlt">Pore</span> <span class="hlt">water</span> plays a more significant role than do sediments in pollutant cycling dynamics. Also, concentrations of pollutants in <span class="hlt">pore</span> <span class="hlt">water</span> provide important information about their bioavailability or eco-toxicity; however, very few studies have focused on this topic. In this study, four duplicate sediment cores from three typical northern bays as well as the central part of Taihu Lake were collected to investigate the distribution, diffusive fluxes, and toxicity of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in <span class="hlt">pore</span> <span class="hlt">water</span> profiles, which will be good in understanding the mobility and toxicity of these toxic pollutants and achieving better environmental management. The diffusive fluxes of heavy metals across the sediment-<span class="hlt">water</span> interface was estimated through Fick's First Law, and the toxicity of heavy metals and PAHs in <span class="hlt">pore</span> <span class="hlt">water</span> was assessed by applying a <span class="hlt">water</span> quality index (interstitial <span class="hlt">water</span> toxicity criteria unit, IWCTU) and a hazard index (HI), respectively. The average concentrations of Cr, Cu, Ni, Pb, and Zn in surface <span class="hlt">pore</span> <span class="hlt">water</span> were 18.8, 23.4, 12.0, 13.5, and 42.5 μg L(-1), respectively. Also, concentrations of the selected heavy metals in both overlying <span class="hlt">water</span> and <span class="hlt">pore</span> <span class="hlt">water</span> from Taihu Lake were all lower than the standard values of the environmental quality standards for surface <span class="hlt">water</span>. The concentrations as the <span class="hlt">pore</span> <span class="hlt">water</span> depth increased, and the highest detected concentrations of heavy metals were recorded between 3 and 5 cm below the sediment surface. The average diffusive fluxes of these metals were 27.3, 24.8, 7.03, 7.81, and -3.32 μg (m(2) day)(-1), respectively, indicating export from sediment into overlying <span class="hlt">water</span>, with the exception of Zn. There was a potential risk of toxicity, mainly from Pb and Cu, indicating that heavy metals in <span class="hlt">pore</span> <span class="hlt">water</span> had slight to moderate impact on sediment-dwelling organisms by values of the IWCTU and the Nemeraw index. The total PAH concentrations in <span class="hlt">pore</span> <span class="hlt">water</span> were higher than those in overlying</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3448652','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3448652"><span>The Influence of Sulphate Deposition on the Seasonal Variation of Peat <span class="hlt">Pore</span> <span class="hlt">Water</span> Methyl Hg in a Boreal Mire</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bergman, Inger; Bishop, Kevin; Tu, Qiang; Frech, Wolfgang; Åkerblom, Staffan; Nilsson, Mats</p> <p>2012-01-01</p> <p>In this paper we investigate the hypothesis that long-term sulphate (SO42−) deposition has made peatlands a larger source of methyl mercury (MeHg) to remote boreal lakes. This was done on experimental plots at a boreal, low sedge mire where the effect of long-term addition of SO42− on peat <span class="hlt">pore</span> <span class="hlt">water</span> MeHg concentrations was observed weekly throughout the snow-free portion of 1999. The additions of SO42− started in 1995. The seasonal mean of the <span class="hlt">pore</span> <span class="hlt">water</span> MeHg concentrations on the plots with 17 kg ha−1 yr−1 of sulphur (S) addition (1.3±0.08 ng L−1, SE; n = 44) was significantly (p<0.0001) higher than the mean MeHg concentration on the plots with 3 kg ha−1 yr−1 of ambient S deposition (0.6±0.02 ng L−1, SE; n = 44). The temporal variation in <span class="hlt">pore</span> <span class="hlt">water</span> MeHg concentrations during the snow free season was larger in the S-addition plots, with an amplitude of >2 ng L−1 compared to +/−0.5 ng L−1 in the ambient S deposition plots. The concentrations of <span class="hlt">pore</span> <span class="hlt">water</span> MeHg in the S-addition plots were positively correlated (r2 = 0.21; p = 0.001) to the groundwater level, with the lowest concentrations of MeHg during the period with the lowest groundwater levels. The <span class="hlt">pore</span> <span class="hlt">water</span> MeHg concentrations were not correlated to total Hg, DOC concentration or pH. The results from this study indicate that the persistently higher <span class="hlt">pore</span> <span class="hlt">water</span> concentrations of MeHg in the S-addition plots are caused by the long-term additions of SO42− to the mire surface. Since these <span class="hlt">waters</span> are an important source of runoff, the results support the hypothesis that SO42− deposition has increased the contribution of peatlands to MeHg in downstream aquatic systems. This would mean that the increased deposition of SO42− in acid rain has contributed to the modern increase in the MeHg burdens of remote lakes hydrologically connected to peatlands. PMID:23029086</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23029086','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23029086"><span>The influence of sulphate deposition on the seasonal variation of peat <span class="hlt">pore</span> <span class="hlt">water</span> methyl Hg in a boreal mire.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bergman, Inger; Bishop, Kevin; Tu, Qiang; Frech, Wolfgang; Åkerblom, Staffan; Nilsson, Mats</p> <p>2012-01-01</p> <p>In this paper we investigate the hypothesis that long-term sulphate (SO(4) (2-)) deposition has made peatlands a larger source of methyl mercury (MeHg) to remote boreal lakes. This was done on experimental plots at a boreal, low sedge mire where the effect of long-term addition of SO(4) (2-) on peat <span class="hlt">pore</span> <span class="hlt">water</span> MeHg concentrations was observed weekly throughout the snow-free portion of 1999. The additions of SO(4) (2-) started in 1995. The seasonal mean of the <span class="hlt">pore</span> <span class="hlt">water</span> MeHg concentrations on the plots with 17 kg ha(-1) yr(-1) of sulphur (S) addition (1.3±0.08 ng L(-1), SE; n = 44) was significantly (p<0.0001) higher than the mean MeHg concentration on the plots with 3 kg ha(-1) yr(-1) of ambient S deposition (0.6±0.02 ng L(-1), SE; n = 44). The temporal variation in <span class="hlt">pore</span> <span class="hlt">water</span> MeHg concentrations during the snow free season was larger in the S-addition plots, with an amplitude of >2 ng L(-1) compared to +/-0.5 ng L(-1) in the ambient S deposition plots. The concentrations of <span class="hlt">pore</span> <span class="hlt">water</span> MeHg in the S-addition plots were positively correlated (r(2) = 0.21; p = 0.001) to the groundwater level, with the lowest concentrations of MeHg during the period with the lowest groundwater levels. The <span class="hlt">pore</span> <span class="hlt">water</span> MeHg concentrations were not correlated to total Hg, DOC concentration or pH. The results from this study indicate that the persistently higher <span class="hlt">pore</span> <span class="hlt">water</span> concentrations of MeHg in the S-addition plots are caused by the long-term additions of SO(4) (2-) to the mire surface. Since these <span class="hlt">waters</span> are an important source of runoff, the results support the hypothesis that SO(4) (2-) deposition has increased the contribution of peatlands to MeHg in downstream aquatic systems. This would mean that the increased deposition of SO(4) (2-) in acid rain has contributed to the modern increase in the MeHg burdens of remote lakes hydrologically connected to peatlands.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27656005','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27656005"><span>Mercury in <span class="hlt">Marine</span> and Oceanic <span class="hlt">Waters</span>-a Review.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gworek, Barbara; Bemowska-Kałabun, Olga; Kijeńska, Marta; Wrzosek-Jakubowska, Justyna</p> <p></p> <p>Mercury contamination in <span class="hlt">water</span> has been an issue to the environment and human health. In this article, mercury in <span class="hlt">marine</span> and oceanic <span class="hlt">waters</span> has been reviewed. In the aquatic environment, mercury occurs in many forms, which depend on the oxidation-reduction conditions. These forms have been briefly described in this article. Mercury concentrations in <span class="hlt">marine</span> <span class="hlt">waters</span> in the different parts of the world have been presented. In the relevant literature, two models describing the fate and behavior of mercury in saltwater reservoirs have been presented, a conceptual model which treats all the oceans as one ocean and the "ocean margin" model, providing that the ocean margins manifested themselves as the convergence of continents and oceans, covering such geological features, such as estuaries, inland seas, and the continental shelf. These two conceptual models have been summarized in the text. The mercury content in benthic sediments usually reflects is level in the <span class="hlt">water</span> reservoir, particularly in reservoirs situated in contaminated areas (mines, metallurgical plants, chemically protected crops). The concentrations of mercury and its compounds determined in the sediments in surface <span class="hlt">waters</span> in the different parts of the world have been presented. Due to the fact that the pollution caused by mercury is a serious threat for the <span class="hlt">marine</span> environment, the short paragraph about mercury bioaccumulation in aquatic organisms has been included. The cited data demonstrated a large scatter of mercury contents both between the fish species and the <span class="hlt">water</span> areas. Mathematical models, valuable tools which provide information about the possible responses of ecosystems, developed to simulate mercury emissions, both at a small scale, for local <span class="hlt">water</span> reservoirs, and at a global scale, as well as to model mercury bioaccumulation in the chain web of aquatic systems have been described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21077669','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21077669"><span>Bioavailability of PAHs in aluminum smelter affected sediments: evaluation through assessment of <span class="hlt">pore</span> <span class="hlt">water</span> concentrations and in vivo bioaccumulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ruus, Anders; Bøyum, Olav; Grung, Merete; Næs, Kristoffer</p> <p>2010-12-15</p> <p>Bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) from coal tar pitch polluted sediments was predicted by (1) a generic approach based on organic carbon-<span class="hlt">water</span> partitioning and Gibbs linear free energy relationship (between K(OW) and K(OC)), and (2) measurements of freely dissolved concentrations of PAHs in the sediment <span class="hlt">pore</span> <span class="hlt">water</span>, using passive samplers and solid phase extraction. Results from these predictions were compared with those from in vivo bioaccumulation experiments using Nereis diversicolor (Polychaeta), Hinia reticulata (Gastropoda), and Nuculoma tenuis (Bivalvia). Measured sediment/<span class="hlt">water</span> partition coefficients were higher than predicted by the generic approach. Furthermore, predicted biota-to-sediment accumulation factors (BSAFs) derived from measured <span class="hlt">pore</span> <span class="hlt">water</span> concentrations were more in agreement with the bioaccumulation observed for two of the three species. Discrepancies associated with the third species (N. tenuis) were likely a result of particles remaining in the intestine (as shown by microscopic evaluation). These results indicate the importance of conducting site-specific evaluations of <span class="hlt">pore</span> <span class="hlt">water</span> concentrations and/or bioaccumulation studies by direct measurements to accurately provide a basis for risk assessment and remediation plans. The importance of knowledge regarding specific characteristics of model organisms is emphasized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26573312','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26573312"><span>Distributions, fluxes, and toxicities of heavy metals in sediment <span class="hlt">pore</span> <span class="hlt">water</span> from tributaries of the Ziya River system, northern China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhu, Xiaolei; Shan, Baoqing; Tang, Wenzhong; Li, Shanshan; Rong, Nan</p> <p>2016-03-01</p> <p>The distributions and mobilities of metals in <span class="hlt">pore</span> <span class="hlt">water</span> strongly influence the biogeochemical processes and bioavailabilities of metals at sediment-<span class="hlt">water</span> interfaces. Heavy metal concentrations were measured in <span class="hlt">pore</span> <span class="hlt">water</span> samples from the Shaocun River (SR), the Wangyang River (WR), and the Xiao River (XR), tributaries of the Ziya River system, northern China. The aim was to assess heavy metal contamination in the system and the associated environmental risks. The mean Cd, Cr, Cu, Ni, Pb, and Zn concentrations in all three tributaries were 0.373, 57.1, 37.7, 20.4, 14.0, and 90.6 μg/L, respectively. The calculated Cd, Cr, Cu, Ni, Pb, and Zn diffusion fluxes in the rivers were -0.427 to 0.469, -71.8 to 42.5, 3.16 to 86.6, 5.29 to 14.0, 7.24 to 19.0, and -204 to 21.9 μg/(m(2) day), respectively, showing that the <span class="hlt">pore</span> <span class="hlt">water</span> was a source of most of the metals to the <span class="hlt">water</span> column. Only Cu and Pb in the XR and Cu in the WR exceeded the final chronic value recommended by the US Environmental Protection Agency, but the metals in the WR sediment could have caused toxic effects. These results are likely to be useful to the authorities responsible for sustainable river management.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/123342','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/123342"><span>Chlorofluorocarbon-11 removal in anoxic <span class="hlt">marine</span> <span class="hlt">waters</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bullister, J.L.; Lee, B.S.</p> <p>1995-07-15</p> <p>Measurements of the chlorofluorocarbons CCl{sub 3}F (F-11) and CCl{sub 2}F{sub 2}(F-12) made in the subsurface anoxic zones of the Black Sea and Saanich Inlet, B.C., Canada show a pronounced depletion of dissolved F-11. These zones are strongly reducing and are characterized by the absence of dissolved nitrate (NO{sub 3}{sup {minus}}) and the presence of hydrogen sulfide (H{sub 2}S). Models incorporating the atmospheric input histories of these CFCs and the observed distributions are used to estimate residence times for <span class="hlt">water</span> in these zones and first order in-situ removal rates for F-11. In contrast, measurements in the mid-depth low-oxygen zone of the eastern Pacific (where NO{sub 3}{sup {minus}} is present and H{sub 2}S is below detection limits) do not show evidence of similar rapid F-11 removal. 22 refs., 3 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25835808','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25835808"><span>Investigation of the Effect of the Tortuous <span class="hlt">Pore</span> Structure on <span class="hlt">Water</span> Diffusion through a Polymer Film Using Lattice Boltzmann Simulations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gebäck, Tobias; Marucci, Mariagrazia; Boissier, Catherine; Arnehed, Johan; Heintz, Alexei</p> <p>2015-04-23</p> <p>Understanding how the <span class="hlt">pore</span> structure influences the mass transport through a porous material is important in several applications, not the least in the design of polymer film coatings intended to control drug release. In this study, a polymer film made of ethyl cellulose and hydroxypropyl cellulose was investigated. The 3D structure of the films was first experimentally characterized using confocal laser scanning microscopy data and then mathematically reconstructed for the whole film thickness. Lattice Boltzmann simulations were performed to compute the effective diffusion coefficient of <span class="hlt">water</span> in the film and the results were compared to experimental data. The local porosities and <span class="hlt">pore</span> sizes were also analyzed to determine how the properties of the internal film structure affect the <span class="hlt">water</span> effective diffusion coefficient. The results show that the top part of the film has lower porosity, lower <span class="hlt">pore</span> size, and lower connectivity, which results in a much lower effective diffusion coefficient in this part, largely determining the diffusion rate through the entire film. Furthermore, the local effective diffusion coefficients were not proportional to the local film porosity, indicating that the results cannot be explained by a single tortuosity factor. In summary, the proposed methodology of combining microscopy data, mass transport simulations, and <span class="hlt">pore</span> space analysis can give valuable insights on how the film structure affects the mass transport through the film.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1166855','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1166855"><span><span class="hlt">Pore</span>-scale simulation of liquid CO2 displacement of <span class="hlt">water</span> using a two-phase lattice Boltzmann model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Liu, Haihu; Valocchi, Albert J.; Werth, Charles J.; Kang, Oinjun; Oostrom, Martinus</p> <p>2014-11-01</p> <p>A lattice Boltzmann color-fluid model, which was recently proposed by Liu et al. [H. Liu, A.J. Valocchi, and Q. Kang. Three-dimensional lattice Boltzmann model for immiscible two-phase flow simulations. Phys. Rev. E, 85:046309, 2012.] based on a concept of continuum surface force, is improved to simulate immiscible two-phase flows in porous media. The new improvements allow the model to account for different kinematic viscosities of both fluids and to model fluid-solid interactions. The capability and accuracy of this model is first validated by two benchmark tests: a layered two-phase flow with a viscosity ratio, and a dynamic capillary intrusion. This model is then used to simulate liquid CO2 (LCO2) displacing <span class="hlt">water</span> in a dual-permeability <span class="hlt">pore</span> network. The extent and behavior of LCO2 preferential flow (i.e., fingering) is found to depend on the capillary number (Ca), and three different displacement patterns observed in previous micromodel experiments are reproduced. The predicted variation of LCO2 saturation with Ca, as well as variation of specific interfacial length with LCO2 saturation, are both in good agreement with the experimental observations. To understand the effect of heterogeneity on <span class="hlt">pore</span>-scale displacement, we also simulate LCO2 displacing <span class="hlt">water</span> in a randomly heterogeneous <span class="hlt">pore</span> network, which has the same size and porosity as the dual-permeability <span class="hlt">pore</span> network. In comparison to the dual-permeability case, the transition from capillary fingering to viscous fingering occurs at a higher Ca, and LCO2 saturation is higher at low Ca but lower at high Ca. In either <span class="hlt">pore</span> network, the LCO2-<span class="hlt">water</span> specific interfacial length is found to obey a power-law dependence on LCO2 saturation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6240107','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6240107"><span>Contaminated <span class="hlt">marine</span> sediments: <span class="hlt">Water</span> column and interstitial toxic effects</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Burgess, R.M.; Schweitzer, K.A.; McKinney, R.A.; Phelps, D.K.</p> <p>1993-01-01</p> <p>The toxicity that contaminated sediments may introduce into the <span class="hlt">water</span> column has not been measured extensively. In order to quantify this potential toxicity, the seawater overlying two uncontaminated and three contaminated <span class="hlt">marine</span> sediments was evaluated in the laboratory with the sea urchin Arbacia punctulata fertilization test. Concentrations of polychlorinated biphenyls (PCBs) and copper, as representative contaminants, were also measured. To characterize sources of toxicity, samples were chemically manipulated using reversed-phase chromatography, cation exchange, and chelation. <span class="hlt">Water</span> column toxicity and contaminant concentrations were higher in the suspended exposures than in bedded exposures. Interstitial <span class="hlt">water</span> toxicity and contaminant concentrations were generally greater than either bedded or suspended exposures. Chemical manipulation indicated that the observed toxicity in <span class="hlt">water</span> column exposures was probably caused by metallic and/or nonionic organic contaminants. Conversely, manipulation of interstitial <span class="hlt">waters</span> did not result in significantly reduced toxicity, suggesting that other toxicants such as ammonia and hydrogen sulfide may be active.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6449724','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6449724"><span>Contaminated <span class="hlt">marine</span> sediments: <span class="hlt">Water</span> column and interstitial toxic effects</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Burgess, R.M.; McKinney, R.A. ); Schweitzer, K.A. ); Phelps, D.K. )</p> <p>1993-01-01</p> <p>The toxicity that contaminated sediments may introduce into the <span class="hlt">water</span> column has not been measured extensively. In order to quantify this potential toxicity, the seawater overlying two uncontaminated and three contaminated <span class="hlt">marine</span> sediments was evaluated in the laboratory with the sea urchin Arbacia punctulata fertilization test. Concentration of polychlorinated biphenyls (PCBs) and copper, as representative contaminants, were also measured. To characterize sources of toxicity, samples were chemically manipulated using reversed-phase chromatography, cation exchange, and chelation. <span class="hlt">Water</span> column toxicity and contaminant concentrations were higher in the suspended exposures than in bedded exposures. Interstitial <span class="hlt">water</span> toxicity and contaminant concentrations were generally greater than either bedded or suspended exposures. Chemical manipulation indicated that the observed toxicity in <span class="hlt">water</span> column exposures was probably caused by metallic and/or nonionic organic contaminants. Conversely, manipulation of interstitial <span class="hlt">water</span> did not result in significantly reduced toxicity, suggesting that other toxicants such as ammonia and hydrogen sulfide may be active.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12180811','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12180811"><span>Effect of <span class="hlt">pore-water</span> velocity on chemical nonequilibrium transport of Cd, Zn, and Pb in alluvial gravel columns.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pang, Liping; Close, Murray; Schneider, Daniela; Stanton, Greg</p> <p>2002-08-01</p> <p>This paper investigates the effects of <span class="hlt">pore-water</span> velocity on chemical nonequilibrium during transport of Cd, Zn, and Pb through alluvial gravel columns. Three <span class="hlt">pore-water</span> velocities ranging from 3 to 60 m/day were applied to triplicate columns for each metal. Model results for the symmetric breakthrough curves (BTCs) of tritium (3H2O) data suggest that physical nonequilibrium components were absent in the uniformly packed columns used in these studies. As a result, values of <span class="hlt">pore-water</span> velocity and dispersion coefficient were estimated from fitting 3H2O BTCs to an equilibrium model. The BTCs of metals display long tailing, indicating presence of chemical nonequilibrium in the system, which was further supported by the decreased metal concentrations during flow interruption. The BTCs of the metals were analysed using a two-site model, and transport parameters were derived using the CXTFIT curve-fitting program. The model results indicate that the partitioning coefficient (beta), forward rate (k1), and backward rate (k2) are positively correlated with <span class="hlt">pore-water</span> velocity (V); while the retardation factor (R), mass transfer coefficient ((omega), and ratio of k1/k2 are inversely correlated with V. There is no apparent relationship between the fraction of exchange sites at equilibrium (f) and V. The influence of Von k2 is much greater than on R, beta, omega, and k1. A one-order-of-magnitude change in V would cause a two-order-of-magnitude change in k2 while resulting in only a one order-of-magnitude change in R, beta, omega, and k1. The forward rates for the metals are found to be two to three orders-of-magnitude greater than the corresponding backward rate. However, the difference between the two rates reduces with increasing <span class="hlt">pore-water</span> velocity. Model results also suggest that Cd and Zn behave similarly, while Pb is much more strongly sorbed. At input concentrations of about 4 mg/l and <span class="hlt">pore-water</span> velocities of 3-60 m/day in the groundwater within alluvial gravel, this</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/2011/1078/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/2011/1078/"><span>Sediment <span class="hlt">pore-water</span> toxicity test results and preliminary toxicity identification of post-landfall <span class="hlt">pore-water</span> samples collected following the Deepwater Horizon oil release, Gulf of Mexico, 2010</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Biedenbach, James M.; Carr, Robert S.</p> <p>2011-01-01</p> <p><span class="hlt">Pore</span> <span class="hlt">water</span> from coastal beach and marsh sediments from the northern Gulf of Mexico, pre- and post-landfall of the Deepwater Horizon oil release, were collected and evaluated for toxicity with the sea urchin fertilization and embryological development assays. There were 17 pre-landfall samples and 49 post-landfall samples tested using both assays. Toxicity was determined in four pre-landfall sites and in seven post-landfall sites in one or both assays as compared to a known reference sediment <span class="hlt">pore-water</span> sample collected in Aransas Bay, Texas. Further analysis and testing of five of the post-landfall toxic samples utilizing Toxicity Identification Evaluation techniques indicated that ammonia, and to a lesser extent metals, contributed to most, if not all, of the observed toxicity in four of the five samples. Results of one sample (MS-39) indicated evidence that ammonia, metals, and non-ionic organics were contributing to the observed toxicity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/2011/1078/pdf/of2011-1078.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/2011/1078/pdf/of2011-1078.pdf"><span>Sediment <span class="hlt">pore-water</span> toxicity test results and preliminary toxicity identification of post-landfall <span class="hlt">pore-water</span> samples collected following the Deepwater Horizon oil release, Gulf of Mexico, 2010</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Biedenbach, James M.; Carr, Robert S.</p> <p>2011-01-01</p> <p><span class="hlt">Pore</span> <span class="hlt">water</span> from coastal beach and marsh sediments from the northern Gulf of Mexico, pre- and post-landfall of the Deepwater Horizon oil release, were collected and evaluated for toxicity with the sea urchin fertilization and embryological development assays. There were 17 pre-landfall samples and 49 post-landfall samples tested using both assays. Toxicity was determined in four pre-landfall sites and in seven post-landfall sites in one or both assays as compared to a known reference sediment <span class="hlt">pore-water</span> sample collected in Aransas Bay, Texas. Further analysis and testing of five of the post-landfall toxic samples utilizing Toxicity Identification Evaluation techniques indicated that ammonia, and to a lesser extent metals, contributed to most, if not all, of the observed toxicity in four of the five samples. Results of one sample (MS-39) indicated evidence that ammonia, metals, and non-ionic organics were contributing to the observed toxicity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2229644','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2229644"><span>A <span class="hlt">Marine</span> Snail Neurotoxin Shares with Scorpion Toxins a Convergent Mechanism of Blockade on the <span class="hlt">Pore</span> of Voltage-Gated K Channels</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>García, Esperanza; Scanlon, Martin; Naranjo, David</p> <p>1999-01-01</p> <p>κ-Conotoxin-PVIIA (κ-PVIIA) belongs to a family of peptides derived from a hunting <span class="hlt">marine</span> snail that targets to a wide variety of ion channels and receptors. κ-PVIIA is a small, structurally constrained, 27-residue peptide that inhibits voltage-gated K channels. Three disulfide bonds shape a characteristic four-loop folding. The spatial localization of positively charged residues in κ-PVIIA exhibits strong structural mimicry to that of charybdotoxin, a scorpion toxin that occludes the <span class="hlt">pore</span> of K channels. We studied the mechanism by which this peptide inhibits Shaker K channels expressed in Xenopus oocytes with the N-type inactivation removed. Chronically applied to whole oocytes or outside-out patches, κ-PVIIA inhibition appears as a voltage-dependent relaxation in response to the depolarizing pulse used to activate the channels. At any applied voltage, the relaxation rate depended linearly on the toxin concentration, indicating a bimolecular stoichiometry. Time constants and voltage dependence of the current relaxation produced by chronic applications agreed with that of rapid applications to open channels. Effective valence of the voltage dependence, zδ, is ∼0.55 and resides primarily in the rate of dissociation from the channel, while the association rate is voltage independent with a magnitude of 107–108 M−1 s−1, consistent with diffusion-limited binding. Compatible with a purely competitive interaction for a site in the external vestibule, tetraethylammonium, a well-known K-<span class="hlt">pore</span> blocker, reduced κ-PVIIA's association rate only. Removal of internal K+ reduced, but did not eliminate, the effective valence of the toxin dissociation rate to a value <0.3. This trans-<span class="hlt">pore</span> effect suggests that: (a) as in the α-KTx, a positively charged side chain, possibly a Lys, interacts electrostatically with ions residing inside the Shaker <span class="hlt">pore</span>, and (b) a part of the toxin occupies an externally accessible K+ binding site, decreasing the degree of <span class="hlt">pore</span> occupancy</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.9896H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.9896H"><span>Geochemical changes in <span class="hlt">pore</span> <span class="hlt">water</span> and reservoir rock due to CO2 injection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huq, Farhana; Blum, Philipp; Nowak, Marcus; Haderlein, Stefan; Grathwohl, Peter</p> <p>2010-05-01</p> <p>In response to current global warming, carbon capture and storage has been identified as one of the promising option. Thus, it can be an interim solution that is indeed a bridge to the future renewable energy without altering the present mode of energy consumption. Although large natural CO2 sinks are terrestrial eco-system and oceans, geological media or more specifically large sedimentary basins are now the most feasible options for carbon sequestration. At the study site, a former gas field (Altmark), which is located in the South of the Northeast German Basin, CO2 is planned to be injected into the reservoir with high pressure (> 50 bar) and temperature (125°C). Afterwards, CO2 dissolves into the <span class="hlt">pore</span> <span class="hlt">water</span> leading to acidification and follow up reactions such as dissolution/precipitation, which potentially change the porosity-permeability of the reservoir and the wetting properties of the mineral surfaces. The Altmark site was chosen due to its large storage capacity, well explored reservoir, high seal integrity due to the presence of massive salt layer (cap rock) and existing infrastructure required for enhanced gas recovery. The main objective of the current study is to quantify the CO2 trapping in aqueous solution under in situ reservoir condition. Therefore, it is necessary to investigate the geochemical changes in fluid composition due to dissolution of minerals under controlled laboratory conditions and to quantify the concentrations of complexing agents that might influence the concentration of total dissolved CO2 in aqueous solution over time. To observe these geochemical and hydraulic changes due to the injection of CO2, a closed system (batch system) technique is developed to study the influence of salinity, temperature, pressure and kinetics on mineral reactions. In addition to the closed system, a flow through (open) autoclave system was constructed. <span class="hlt">Water</span> saturated sedimentary rock cores (e.g. from the Altmark site; 5cm long, 3cm diameter) are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.H23D0904T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.H23D0904T"><span>Paleohydrological Information from Profiles in <span class="hlt">Pore</span> <span class="hlt">Water</span> of Holocene Low-Permeability Cores and Groundwater Flow Simulation, Lake Kasumigaura, Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takamoto, N.; Shimada, J.</p> <p>2014-12-01</p> <p>The paleohydrological information can become important to predict hydrological conditions in the future. In Japan, which hydrologically is characterized by relatively small catchment scales with steep relief of topography under humid temperate climatic conditions, the residence time of the groundwater should be relatively short. Thus the paleohydrological information preserved in the groundwater aquifer should also be limited compared with the continental aquifer. However, regarding groundwater in clay and silt sediments have low-permeability characteristic, archiving the paleohydrologic information at the time of deposition is expected.  Therefore, in this study, cores were drilled into Holocene clay and silt deposits (Site K-1 and Site K-2) in the Lake Kasumigaurain Japan, where the depositional rate 10,000 years ago was rapid and it has been affected strongly by sea level changes including transgression and regression. By using the obtained core samples and extracted <span class="hlt">pore</span> <span class="hlt">water</span> from the cores, paleohydrologic information was investigated, and it was tried to understand hydrologic environments at the study area during a Holocene. In addition, groundwater flow and solute transport simulation were conducted to reproduce profiles of <span class="hlt">pore</span> <span class="hlt">water</span>.  Results of investigation show that the profiles of <span class="hlt">pore</span> <span class="hlt">water</span> contents reflect sea level change and the difference in hydrological environment at that time at each site. The content of the paleo-brackish <span class="hlt">water</span> in the culmination of transgression was about 14,000 mg/l in Cl-, -13.0‰ in δD and -2.6‰ in δ18O. It is allowed better understanding paleohydrological information by studying not only inorganic chemistry contents and stable isotopes of <span class="hlt">pore</span> <span class="hlt">water</span> and also the diatom fossils and groundwater flow and solute transport simulation. We will characterize the paleohydrological information of the study area acquired by those investigations and analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11108852','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11108852"><span>Diurnal changes in <span class="hlt">pore</span> <span class="hlt">water</span> sulfide concentrations in the seagrass Thalassia testudinum beds: the effects of seagrasses on sulfide dynamics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee; Dunton</p> <p>2000-12-20</p> <p>The dynamics of the seagrass-sulfide interaction were examined in relation to diel changes in sediment <span class="hlt">pore</span> <span class="hlt">water</span> sulfide concentrations in Thalassia testudinum beds and adjacent bare areas in Corpus Christi Bay and lower Laguna Madre, Texas, USA, during July 1996. <span class="hlt">Pore</span> <span class="hlt">water</span> sulfide concentrations in seagrass beds were significantly higher than in adjacent bare areas and showed strong diurnal variations; levels significantly decreased during mid-day at shallow sediment depths (0-10 cm) containing high below-ground tissue biomass and surface area. In contrast, diurnal variations in sediment sulfide concentrations were absent in adjacent bare patches, and at deeper (>10 cm) sediment depths characterized by low below-ground plant biomass or when the grasses were experimentally shaded. These observations suggest that the mid-day depressions in sulfide levels are linked to the transport of photosynthetically produced oxygen to seagrass below-ground tissues that fuels sediment sulfide oxidation. Lower sulfide concentrations in bare areas are likely a result of low sulfate reduction rates due to low organic matter available for remineralization. Further, high reoxidation rates due to rapid exchange between anoxic <span class="hlt">pore</span> <span class="hlt">water</span> and oxic overlying <span class="hlt">water</span> are probably stimulated in bare areas by higher current velocity on the sediment surface than in seagrass beds. The dynamics of <span class="hlt">pore</span> <span class="hlt">water</span> sulfides in seagrass beds suggest no toxic sulfide intrusion into below-ground tissues during photosynthetic periods and demonstrate that the sediment chemical environment is considerably modified by seagrasses. The reduced sediment sulfide levels in seagrass beds during photosynthetic periods will enhance seagrass production through reduced sulfide toxicity to seagrasses and sediment microorganisms related to the nutrient cycling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15013719','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15013719"><span>Comparison of Experimental and Model Data for the Evaporation of a Synthetic Topopah Spring Tuff <span class="hlt">Pore</span> <span class="hlt">Water</span>, Yucca Mountain, NV</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Alai, M; Sutton, M; Carroll, S</p> <p>2003-10-14</p> <p>The evaporation of a range of synthetic <span class="hlt">pore</span> <span class="hlt">water</span> solutions representative of the potential high-level-nuclear-waste repository at Yucca Mountain, NV is being investigated. The motivation of this work is to understand and predict the range of brine compositions that may contact the waste containers from evaporation of <span class="hlt">pore</span> <span class="hlt">waters</span>, because these brines could form corrosive thin films on the containers and impact their long-term integrity. A relatively complex synthetic Topopah Spring Tuff <span class="hlt">pore</span> <span class="hlt">water</span> was progressively concentrated by evaporation in a closed vessel, heated to 95 C in a series of sequential experiments. Periodic samples of the evaporating solution were taken to determine the evolving <span class="hlt">water</span> chemistry. According to chemical divide theory at 25 C and 95 C our starting solution should evolve towards a high pH carbonate brine. Results at 95 C show that this solution evolves towards a complex brine that contains about 99 mol% Na{sup +} for the cations, and 71 mol% Cl{sup -}, 18 mol% {Sigma}CO{sub 2}(aq), 9 mol% SO{sub 4}{sup 2-} for the anions. Initial modeling of the evaporating solution indicates precipitation of aragonite, halite, silica, sulfate and fluoride phases. The experiments have been used to benchmark the use of the EQ3/6 geochemical code in predicting the evolution of carbonate-rich brines during evaporation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70011623','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70011623"><span>Geochemistry of <span class="hlt">pore</span> <span class="hlt">waters</span> from Shell Oil Company drill holes on the continental slope of the northern Gulf of Mexico</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Manheim, F. T.; Bischoff, J.L.</p> <p>1969-01-01</p> <p><span class="hlt">Pore</span> <span class="hlt">waters</span> were analyzed from 6 holes drilled from M.V. "Eureka" as a part of the Shell Oil Co. deeper offshore study. The holes were drilled in <span class="hlt">water</span> depths of 600-3,000 ft. (approximately 180-550 m) and penetrated up to 1,000 ft. (300 m) of Pliocene-Recent clayey sediments. Salt and anhydrite caprock was encountered in one diapiric structure on the continental slope. Samples from holes drilled near diapiric structures showed systematic increases of <span class="hlt">pore-water</span> salinity with depth, suggestive of salt diffusion from underlying salt plugs. Anomalous concentrations of K and Br indicate that at least one plug contains late-stage evaporite minerals. Salinities approaching halite saturation were observed. Samples from holes away from diapiric structures showed little change in <span class="hlt">pore-water</span> chemistry, except for loss of SO4 and other variations attributable to early-stage diagenetic reactions with enclosing sediments. Thus, increased salt concentrations in even shallow sediments from this part of the Gulf appear to provide an indicator of salt masses at depth. ?? 1969.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26702554','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26702554"><span>Behaviour of pharmaceuticals and personal care products in constructed wetland compartments: Influent, effluent, <span class="hlt">pore</span> <span class="hlt">water</span>, substrate and plant roots.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hijosa-Valsero, María; Reyes-Contreras, Carolina; Domínguez, Carmen; Bécares, Eloy; Bayona, Josep M</p> <p>2016-02-01</p> <p>Seven mesocosm-scale constructed wetlands (CWs) with different design configurations, dealing with primary-treated urban wastewater, were assessed for the concentration, distribution and fate of ten pharmaceutical and personal care products (PPCPs) [ibuprofen, ketoprofen, naproxen, diclofenac, salicylic acid, caffeine, carbamazepine, methyl dihydrojasmonate, galaxolide and tonalide] and eight of their transformation products (TPs). Apart from influent and effluent, various CW compartments were analysed, namely, substrate, plant roots and <span class="hlt">pore</span> <span class="hlt">water</span>. PPCP content in <span class="hlt">pore</span> <span class="hlt">water</span> depended on the specific CW configuration. Macrophytes can take up PPCPs through their roots. Ibuprofen, salicylic acid, caffeine, methyl dihydrojasmonate, galaxolide and tonalide were present on the root surface with a predominance of galaxolide and caffeine in all the planted systems. Naproxen, ibuprofen, salicylic acid, methyl dihydrojasmonate, galaxolide and tonalide were uptaken by the roots. In order to better understand the removal processes, biomass measurement and biodegradability studies through the characterization of internal-external isomeric linear alkylbenzenes present on the gravel bed were performed. Three TPs namely, ibuprofen-amide, 3-ethylbenzophenone and 4-hydroxy-diclofenac were identified for the first time in wetland <span class="hlt">pore</span> <span class="hlt">water</span> and effluent <span class="hlt">water</span>, which suggests de novo formation (they were not present in the influent). Conversely, O-desmethyl-naproxen was degraded through the wetland passage since it was detected in the influent but not in the subsequent treatment stages. Biodegradation pathways are therefore suggested for most of the studied PPCPs in the assessed CWs. Copyright © 2015 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26312406','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26312406"><span>Redox processes in <span class="hlt">pore</span> <span class="hlt">water</span> of anoxic sediments with shallow gas.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ramírez-Pérez, A M; de Blas, E; García-Gil, S</p> <p>2015-12-15</p> <p>The Ría de Vigo (NW Spain) has a high organic matter content and high rates of sedimentation. The microbial degradation of this organic matter has led to shallow gas accumulations of methane, currently distributed all along the ría. These peculiar characteristics favor the development of anoxic conditions that can determine the dynamics of iron and manganese. In order to study the role played by iron and manganese in the processes that take place in anoxic sediments with shallow gas, four gravity cores were retrieved in anoxic sediments of the Ría de Vigo in November 2012. Methane was present in two of them, below 90cm in the inner zone and below 200cm, in the outer zone. <span class="hlt">Pore</span> <span class="hlt">water</span> was collected and analyzed for vertical profiles of pH, sulfide, sulfate, iron and manganese concentrations. Sulfate concentrations decreased with depth but never reached the minimum detection limit. High sulfide concentrations were measured in all cores. The highest sulfide concentrations were found in the inner zone with methane and the lowest were in the outer zone without methane. Concentrations of iron and manganese reached maximum values in the upper layers of the sediment, decreasing with depth, except in the outer zone without gas, where iron and manganese concentration increased strongly toward the bottom of the sediment. In areas with shallow gas iron reduction, sulfate reduction and methane production processes coexist, showing that the traditional redox cascade is highly simplified and suggesting that iron may be involved in a cryptic sulfur cycle and in the oxidation of methane.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AdWR...30.1562S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AdWR...30.1562S"><span>Analytical-modeling analysis of how <span class="hlt">pore-water</span> gradients of toxic metals confer community resistance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schwarz, Alex O.; Rittmann, Bruce E.</p> <p>2007-06-01</p> <p>We develop a mechanistic explanation of how microbial communities are able to protect themselves from toxicity from inflowing metal concentrations much higher than the metal-toxicity thresholds of individual microorganisms. We propose a general bio-protection mechanism, of widespread applicability to microbial communities, by which some bacteria induce <span class="hlt">pore-water</span> metal gradients by producing ligands that bind the metal toxicant, reducing the toxicant's concentration to non-inhibitory levels for much of the community. Sulfate-reducing communities are a good example of community-based bio-protection. In particular, we develop analytical solutions to derive metal-resistance criteria for two distinctly different systems displaying gradient-based resistance: permeable reactive barriers (PRBs), which are advection dominated, and sediments, which are diffusion dominated. In advection-dominated systems, the most significant variables influencing the development of static gradients are groundwater velocity and the rate of ligand production. By transporting the toxicant into the PRB and by preventing ligand from moving upgradient, a fast groundwater velocity can overwhelm the chemical gradient bio-protection mechanism. Likewise, the stability of a chemical gradient bio-protection scheme increases in proportion to the rate of ligand generation. In diffusion-dominated systems, resistance depends on the rate of ligand generation and the diffusion length for movement of metal into the sediment. For both cases, we derive quantitative stability criteria that include the phenomena described here. These criteria demonstrate that diffusion-dominated systems offer greater potential for gradient-based metal resistance than do advection-dominated systems. When diffusion controls transport, metal movement into the reactive zone can be slowed down, and a greater fraction of the ligand is available for reaction with the metal, since it is not swept away by advection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/244882','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/244882"><span>Rapid toxicity screening of sediment <span class="hlt">pore</span> <span class="hlt">waters</span> using physiological and biochemical biomarkers of Daphnia magna</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Coen, W.M. De; Janssen, C.R.; Persoone, G.</p> <p>1995-12-31</p> <p>Two new rapid toxicity tests, based on ingestion activity and digestive enzyme activity of D. magna, were developed and evaluated. The ingestion activity was measured using fluorescent latex micro-beads and an automated microplate fluorimeter allowing a sensitive quantification of the feeding activity of the organisms. The activity of the digestive enzymes, 6-galactosidase, esterase and trypsin, was determined in test organism homogenates using the following fluorogenic{sup 1} and chromogenic{sup 2} substrates: 4-methylumbelliferyl-{beta}-D galactoside{sup 1}, fluorescin diacetate{sup 1} and N-Benzoyl-L-arginine-4-nitroanilide{sup 2}. Both biomarker techniques were developed to allow rapid toxicity screening on a routine basis. The toxicity of the <span class="hlt">pore</span> <span class="hlt">waters</span> of eight contaminated samples was assessed with the aid of the developed biomarker assays. Comparison of the conventional 24h EC50 values with the EC50 values obtained with the 1.5h ingestion test and the threshold concentrations of the 2h digestive enzyme tests revealed a positive correlation between the different effect concentrations. A similar correlation (r{sup 2} = 0.87) between the conventional 24h EC50 values and 1.5h EC50 values was observed in toxicity tests with pure compounds. Correlation coefficients for the relationships between the 3 enzyme effect concentrations and the 24h EC50 values ranged from 0.95 to 0.98, The positive correlations between the conventional and biomarker effect criteria, observed for both environmental samples and pure compounds, demonstrate the potential use of the developed methods as rapid toxicity screening tools.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/658778','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/658778"><span>Canadian <span class="hlt">water</span> quality guidelines. Appendix 22: Interim <span class="hlt">marine</span> and estuarine <span class="hlt">water</span> quality guidelines for general variables</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p></p> <p>1996-12-31</p> <p>This document has been prepared in response to the need for <span class="hlt">marine</span> <span class="hlt">water</span> quality guidelines for general <span class="hlt">water</span> quality variables. It presents interim guidelines, summaries of existing guidelines if any, the rationale for the guidelines, and variable-specific background information, and notes gaps in data, for the following variables: Debris, including floating or submerged litter, and settleable matter; dissolved oxygen; pH; salinity; temperature; and suspended solids and turbidity. For the purpose of this document, the <span class="hlt">marine</span> environment includes shorelines, estuaries up to the freshwater limit, and nearshore and offshore <span class="hlt">waters</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-10-04/pdf/2012-24481.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-10-04/pdf/2012-24481.pdf"><span>77 FR 60687 - Record of Decision for the U.S. <span class="hlt">Marine</span> Corps Basewide <span class="hlt">Water</span> Infrastructure Project at <span class="hlt">Marine</span>...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-10-04</p> <p>... Department of the Navy Record of Decision for the U.S. <span class="hlt">Marine</span> Corps Basewide <span class="hlt">Water</span> Infrastructure Project at <span class="hlt">Marine</span> Corps Base Camp Pendleton, California AGENCY: Department of the Navy, DoD. ACTION: Notice of...) of 1969, 42 United States Code (U.S.C.) Section 4332(2)(c), the regulations of the Council on...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GGG....14.1626B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GGG....14.1626B"><span>Using ammonium <span class="hlt">pore</span> <span class="hlt">water</span> profiles to assess stoichiometry of deep remineralization processes in methanogenic continental margin sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Burdige, David J.; Komada, Tomoko</p> <p>2013-05-01</p> <p>many continental margin sediments, a deep reaction zone exists which is separated from remineralization processes near the sediment surface. Here, methane diffuses upward to a depth where it is oxidized by downwardly diffusing sulfate. However, the methane sources that drive this anaerobic oxidation of methane (AOM) in the sulfate-methane transition zone (SMT) may vary among sites. In particular, these sources can be thought of as either (i) "internal" sources from in situ methanogenesis (regardless of where it occurs in the sediment column) that are ultimately coupled to organic matter deposition and burial, or (ii) "external" sources such as hydrocarbon reservoirs derived from ancient source rocks, or deeply buried gas hydrates, both of which are decoupled from contemporaneous organic carbon deposition at the sediment surface. Using a modeling approach, we examine the relationship between different methane sources and <span class="hlt">pore</span> <span class="hlt">water</span> sulfate, methane, dissolved inorganic carbon (DIC), and ammonium profiles. We show that <span class="hlt">pore</span> <span class="hlt">water</span> ammonium profiles through the SMT represent an independent "tracer" of remineralization processes occurring in deep sediments that complement information obtained from profiles of solutes directly associated with AOM and carbonate precipitation, i.e., DIC, methane, and sulfate. <span class="hlt">Pore</span> <span class="hlt">water</span> DIC profiles also show an inflection point in the SMT based on the type of deep methane source and the presence/absence of accompanying upward DIC fluxes. With these results, we present a conceptual framework which illustrates how shallow <span class="hlt">pore</span> <span class="hlt">water</span> profiles from continental margin settings can be used to obtain important information about remineralization processes and methane sources in deep sediments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27049790','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27049790"><span>Use of sunlight to degrade oxytetracycline in <span class="hlt">marine</span> aquaculture's <span class="hlt">waters</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Leal, J F; Esteves, V I; Santos, E B H</p> <p>2016-06-01</p> <p>Oxytracycline (OTC) is a broad spectrum antibiotic authorized for use in European aquaculture. Its photo-degradation has been widely studied in synthetic aqueous solutions, sometimes resorting to expensive methods and without proven effectiveness in natural <span class="hlt">waters</span>. Thus, this work studied the possibility to apply the solar photo-degradation for removal of OTC from <span class="hlt">marine</span> aquaculture's <span class="hlt">waters</span>. For that, <span class="hlt">water</span> samples were collected at different locals of the <span class="hlt">water</span> treatment circuit, from two different aquaculture companies. <span class="hlt">Water</span> samples were firstly characterized regarding to pH, salinity, total suspended solids (TSS), organic carbon and UV-Vis spectroscopic characteristics. Then, the samples were spiked with OTC and irradiated using simulated sunlight in order to evaluate the matrix effects on OTC photo-degradation. From kinetic results, the apparent quantum yields and the outdoor half-life times, at 40°N for midsummer and midwinter days were estimated by the first time for these conditions. For a midsummer day, at sea level, the outdoor half-life time predicted for OTC in these aquaculture's <span class="hlt">waters</span> ranged between 21 and 25 min. Additionally, the pH and salinity effects on the OTC photo-degradation were evaluated and it has been shown that high pH values and the presence of sea salt increase the OTC photo-degradation rate in aquaculture's <span class="hlt">waters</span>, compared to results in deionised <span class="hlt">water</span>. The results are very promising to apply this low-cost methodology using the natural sunlight in aquaculture's <span class="hlt">waters</span> to remove OTC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JCHyd.142...75P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JCHyd.142...75P"><span>Influence of <span class="hlt">pore</span> <span class="hlt">water</span> velocity on the release of carbofuran and fenamiphos from commercial granulates embedded in a porous matrix</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Paradelo, Marcos; Pérez-Rodríguez, Paula; Arias-Estévez, Manuel; López-Periago, J. Eugenio</p> <p>2012-11-01</p> <p><span class="hlt">Pore</span> <span class="hlt">water</span> flow velocity can influence the processes involved in the contaminant transport between relative stagnant zones of porous media and their adjacent mobile zones. A particular case of special interest is the occurrence of high flow rates around the controlled release granules containing pesticides buried in soil. The release of the pesticides carbofuran and fenamiphos from commercial controlled release formulations (CRFs) was studied, comparing release tests in a finite volume of <span class="hlt">water</span> with <span class="hlt">water</span> flow release tests in saturated packed sand at different seepage velocities. For <span class="hlt">water</span> release kinetics, the time taken for 50% of the pesticide to be released (T50) was 0.64 hours for carbofuran and 1.97 hours for fenamiphos. In general, the release rate was lower in the porous matrix than in the free <span class="hlt">water</span> tests. The faster release rate for carbofuran was attributed to its higher <span class="hlt">water</span> diffusivity. The seepage velocity has a strong influence on the pesticide release rate. The dominant release mechanism varies with the progress of release. The evolution of the mechanism is discussed on the basis of the successive steps that involve the moving boundary of the dissolution front of the pesticide inside the granule, the concentration gradient inside the granule and the flow boundary layer resistance to solute diffusion around the granule. The <span class="hlt">pore</span> <span class="hlt">water</span> velocity influences the overall release dynamics. Therefore, seepage velocity should be considered in pesticide release to evaluate the risk of pesticide leaching, especially in scenarios with fast infiltration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27974156','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27974156"><span>Floating <span class="hlt">Marine</span> Debris in <span class="hlt">waters</span> of the Mexican Central Pacific.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Díaz-Torres, Evelyn R; Ortega-Ortiz, Christian D; Silva-Iñiguez, Lidia; Nene-Preciado, Alejandro; Orozco, Ernesto Torres</p> <p>2017-02-15</p> <p>The presence of <span class="hlt">marine</span> debris has been reported recently in several oceans basins; there is very little information available for Mexican Pacific coasts, however. This research examined the composition, possible sources, distribution, and density of Floating <span class="hlt">Marine</span> Debris (FMD) during nine research surveys conducted during 2010-2012 in the Mexican Central Pacific (MCP). Of 1820 floating objects recorded, 80% were plastic items. Sources of FMD were determined using key objects, which indicated that the most were related to the presence of the industrial harbor and of a growing fishing industry in the study area. Densities were relatively high, ranging from 40 to 2440objects/km(2); the highest densities were recorded in autumn. FMD were distributed near coastal regions, mainly in Jalisco, influenced by river outflow and surface currents. Our results seem to follow worldwide trends and highlight the need for further studies on potential ecological impacts within coastal <span class="hlt">waters</span> of the MCP. Copyright © 2016 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70005222','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70005222"><span>Characterization of the intragranular <span class="hlt">water</span> regime within subsurface sediments: <span class="hlt">pore</span> volume, surface area, and mass transfer limitations</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hay, Michael B.; Stoliker, Deborah L.; Davis, James A.; Zachara, John M.</p> <p>2011-01-01</p> <p>Although "intragranular" <span class="hlt">pore</span> space within grain aggregates, grain fractures, and mineral surface coatings may contain a relatively small fraction of the total porosity within a porous medium, it often contains a significant fraction of the reactive surface area, and can thus strongly affect the transport of sorbing solutes. In this work, we demonstrate a batch experiment procedure using tritiated <span class="hlt">water</span> as a high-resolution diffusive tracer to characterize the intragranular <span class="hlt">pore</span> space. The method was tested using uranium-contaminated sediments from the vadose and capillary fringe zones beneath the former 300A process ponds at the Hanford site (Washington). Sediments were contacted with tracers in artificial groundwater, followed by a replacement of bulk solution with tracer-free groundwater and the monitoring of tracer release. From these data, intragranular <span class="hlt">pore</span> volumes were calculated and mass transfer rates were quantified using a multirate first-order mass transfer model. Tritium-hydrogen exchange on surface hydroxyls was accounted for by conducting additional tracer experiments on sediment that was vacuum dried after reaction. The complementary ("wet" and "dry") techniques allowed for the simultaneous determination of intragranular porosity and surface area using tritium. The Hanford 300A samples exhibited intragranular <span class="hlt">pore</span> volumes of ~1% of the solid volume and intragranular surface areas of ~20%–35% of the total surface area. Analogous experiments using bromide ion as a tracer yielded very different results, suggesting very little penetration of bromide into the intragranular porosity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70036215','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70036215"><span>Characterization of the intragranular <span class="hlt">water</span> regime within subsurface sediments: <span class="hlt">Pore</span> volume, surface area, and mass transfer limitations</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hay, M.B.; Stoliker, D.L.; Davis, J.A.; Zachara, J.M.</p> <p>2011-01-01</p> <p>Although "intragranular" <span class="hlt">pore</span> space within grain aggregates, grain fractures, and mineral surface coatings may contain a relatively small fraction of the total porosity within a porous medium, it often contains a significant fraction of the reactive surface area, and can thus strongly affect the transport of sorbing solutes. In this work, we demonstrate a batch experiment procedure using tritiated <span class="hlt">water</span> as a high-resolution diffusive tracer to characterize the intragranular <span class="hlt">pore</span> space. The method was tested using uranium-contaminated sediments from the vadose and capillary fringe zones beneath the former 300A process ponds at the Hanford site (Washington). Sediments were contacted with tracers in artificial groundwater, followed by a replacement of bulk solution with tracer-free groundwater and the monitoring of tracer release. From these data, intragranular <span class="hlt">pore</span> volumes were calculated and mass transfer rates were quantified using a multirate first-order mass transfer model. Tritium-hydrogen exchange on surface hydroxyls was accounted for by conducting additional tracer experiments on sediment that was vacuum dried after reaction. The complementary ("wet" and "dry") techniques allowed for the simultaneous determination of intragranular porosity and surface area using tritium. The Hanford 300A samples exhibited intragranular <span class="hlt">pore</span> volumes of ???1% of the solid volume and intragranular surface areas of ???20%-35% of the total surface area. Analogous experiments using bromide ion as a tracer yielded very different results, suggesting very little penetration of bromide into the intragranular porosity. Copyright 2011 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/334212','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/334212"><span>Ion and <span class="hlt">water</span> transport in a Nafion{reg_sign} membrane <span class="hlt">pore</span>: A statistical mechanical model with molecular structure</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Paddison, S.J.; Zawodzinski, T.A. Jr.; Paul, R.</p> <p>1998-12-31</p> <p>With the well established importance of the coupling of <span class="hlt">water</span> and protons through electroosmotic drag in operating PEFCs the authors present here a derivation of a mathematical model that focuses on the computation of the mobility of an hydronium ion through an arbitrary cylindrical <span class="hlt">pore</span> of a PEM with a non-uniform charge distribution on the walls of the <span class="hlt">pore</span>. The total Hamiltonian is derived for the hydronium ion as it moves through the hydrated <span class="hlt">pore</span> and is effected by the net potential due to interaction with the solvent molecules and the pendant side chains. The corresponding probability density is derived through solution of the Liouville equation. This probability density is then used to compute the friction tensor for the hydronium ion. The authors find two types of contributions: (a) due to the solvent-ion interactions for which they adopt the conventional continuum model; (b) due to the interaction between the pendant charges and the hydronium ion. The latter is a new result and displays the role of the non-uniform nature of the charge distribution on the <span class="hlt">pore</span> wall.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/211908','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/211908"><span>Bioavailability of metals and toxicity identification of the sediment <span class="hlt">pore</span> <span class="hlt">waters</span> from Plow Shop Pond, Fort Devens, Massachusetts</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jop, K.; Putt, A.; Shepherd, S.; Askew, A.; Bleiler, J.; Reed, S.; George, C.</p> <p>1995-12-31</p> <p>Plow Shop Pond is a shallow, 30-acre pond located at Fort Devens, Massachusetts. An ecological risk assessment was conducted at Plow Shop Pond as part of a remedial investigation. Preliminary analysis revealed high concentrations of arsenic, copper, chromium, lead, and mercury in the sediment. Therefore, a laboratory testing program was incorporated into this investigation to assess the toxicity of sediments to aquatic organisms. The screening testing program included short-term chronic exposure of Ceriodaphnia dubia to <span class="hlt">pore</span> <span class="hlt">waters</span>, 10-day exposures of Chironomus tentans and Hyalella azteca to bulk sediments and a bioaccumulation study with Lumbriculus variegatus. Survival and reproduction of C. dubia, growth of amphipods and reproduction of oligochaetes appeared to indicate sediment toxicity at some sites within the pond. Although high concentrations of arsenic, copper, mercury and lead were detected in the whole sediments and <span class="hlt">pore</span> <span class="hlt">waters</span>, the response could not be correlated to a particular element. Also, relatively low bioaccumulation of methyl mercury and high uptake of inorganic mercury was established for three sediment samples. To characterize and identify the source of toxicity, a toxicity identification evaluation program using sediments collected at several locations was performed. The <span class="hlt">pore</span> <span class="hlt">water</span> from these samples was used for fractionation coupled with a 10-day test using H. azteca. Survival and growth were evaluated as endpoints during the exposures. Partitioning of metals and their bioavailability was influenced primarily by organic carbon and AVS concentration. At least two constituents were responsible for the toxicity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21538492','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21538492"><span>Intercomparison and applicability of some dynamic and equilibrium approaches to determine methylated mercury species in <span class="hlt">pore</span> <span class="hlt">water</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Jinling; Feng, Xinbin; Qiu, Guangle; Yao, Heng; Shang, Lihai; Yan, Haiyu</p> <p>2011-08-01</p> <p>To assess adequately the impact of methylmercury (MeHg) on sensitive wetland ecosystems, accurate measurements of MeHg in <span class="hlt">pore</span> <span class="hlt">water</span> are required. In the present study, the feasibility of three methods for porewater sampling was investigated with respect to MeHg in sediments and rice paddy fields. The performance of dialysis samplers (peepers), sediment core sectioning followed by porewater separation by centrifugation (core), and the thin film diffusive samplers (DGT) were evaluated. These methods were intercompared in field experiments at two sites in Guizhou province, SW China disparately impacted by mercury pollution. All the methods report that the concentrations of MeHg in the soils of the Gouxi (GX) rice paddy near Wanshan were much higher than that in the sediment of the Hongjiadu Reservoir (HR), which is located within the Wujiang River basin. The three methods also report different MeHg profiles at the same site. However, these methods exhibit different temporal and spatial resolution scales, due to the differing operations involved with the sampling methods, may also reflect different states of MeHg in <span class="hlt">pore</span> <span class="hlt">water</span>. This corresponds to MeHg derived from diffusive flux, equilibrium concentration, and bulk concentration in <span class="hlt">pore</span> <span class="hlt">water</span> detected by DGT, peeper, and sediment core, respectively. The advantages and limits of the three methods are also presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14672723','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14672723"><span>Changes in constituent equilibrium leaching and <span class="hlt">pore</span> <span class="hlt">water</span> characteristics of a Portland cement mortar as a result of carbonation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Garrabrants, A C; Sanchez, F; Kosson, D S</p> <p>2004-01-01</p> <p>Two equilibrium-based characterization protocols were applied to ground samples of a cement-based material containing metal oxide powders in both noncarbonated and carbonated states. The effects of carbonation were shown through comparison of (i) material buffering capacity, (ii) constituent equilibrium as a function of leachate pH, and (iii) constituent solubility and release as a function of liquid-to-solid (LS) ratio. As expected, the material alkalinity was significantly neutralized during carbonation. In addition, carbonation of the cement material led to the formation of calcium carbonate and a corresponding increase in arsenic release across the entire pH range. The solubility as a function of pH for lead and copper was lower in the alkaline pH range (pH>9) for carbonated samples compared with the parent material. When solubility and release as a function of LS ratio was compared, carbonation was observed to decrease calcium solubility, sodium and potassium release, and ionic strength. In response to carbonate solid formation, chloride and sulfate release as a function of LS ratio was observed to increase. Trends in constituent concentration as a function of LS ratio were extrapolated to estimate <span class="hlt">pore</span> <span class="hlt">water</span> composition at a 0.06 mL/g LS ratio. Significant differences were observed upon comparison of estimated <span class="hlt">pore</span> <span class="hlt">water</span> composition to leachate concentrations extracted at LS ratio of 5 mL/g. These differences show that practical laboratory extractions cannot be assumed directly representative of <span class="hlt">pore</span> <span class="hlt">water</span> concentrations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9784R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9784R"><span>Evaluation of chloride mass balance of <span class="hlt">pore</span> <span class="hlt">water</span> as an indicator of groundwater recharge to the Monterrey Metropolitan Area, Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rosales-Lagarde, Laura; Pasten, Ernesto; Mora, Abrahan; Mahlknecht, Jürgen</p> <p>2016-04-01</p> <p>Monterrey Metropolitan Area in Nuevo Leon, Mexico, is the third largest metropolitan area and one of the most important industrial sites of Mexico. Groundwater constitutes 40% of the <span class="hlt">water</span> supply to this urban area. This supply is under constant stress due to the population increase. The unsaturated zone at six sites along two cross-sections was characterized to evaluate the potential of chloride concentration as an indicator of recharge. The selected sites include the range of topographic elevations, vegetation, and annual precipitation of the study area. In each site, boreholes up to 5 m deep were drilled and soil was sampled every 0.5 m. The grain size of each soil sample was determined and <span class="hlt">pore</span> <span class="hlt">water</span> extracted to determine the <span class="hlt">water</span> content percentage, and the chloride, sulfate and nitrate concentration of the <span class="hlt">pore</span> <span class="hlt">water</span>. The undersaturated zone consists of alluvial deposits with an average gravel and sand content greater than 60% for all but one of the sampling sites. The <span class="hlt">pore</span> <span class="hlt">water</span> content varies from 0.4 to 25% by weight with a decreasing trend as depth increases in areas with agriculture. Sulfate has the highest anion concentration in the <span class="hlt">pore</span> <span class="hlt">waters</span>, ranging from 42 to 45,000 mg/L and no apparent distribution pattern along the soil profile columns. Chloride concentration ranges from 8 to 3600 mg/L with an increase in concentration below 1.5 m depth in all the profiles. Chloride and sulfate concentrations with depth are directly correlated suggesting a common input, possibly dissolution-precipitation of evaporite minerals from nearby outcrops or an anthropogenic input. Hence, it is unlikely that chloride behaves as a conservative ion. As a result, its concentration is not likely to be a good indicator of groundwater recharge. Finally; the nitrate concentration ranges from 2 to 96 mg/L nitrate, without a clear pattern along the soil profiles. Low concentration of nitrate in the soil profiles below agricultural areas may suggest denitrification as suggested</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997JHyd..197...47O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997JHyd..197...47O"><span>Origin of <span class="hlt">pore</span> <span class="hlt">water</span> and salinity in the lacustrine aquitard overlying the regional aquifer of Mexico City</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ortega-Guerrero, Adrian; Cherry, John A.; Aravena, Ramon</p> <p>1997-10-01</p> <p>A series of six ancient connected lakes occupied the broad plain of the closed Basin of Mexico. This study pertains to two of these lakes. 18O, 2H and chemical patterns in the <span class="hlt">pore</span> <span class="hlt">water</span> of the broad aquitard formed from sediment in these lakes indicate that the origin of this paleo-lake <span class="hlt">water</span> was local meteoric <span class="hlt">water</span>, which entered the ancient lakes as runoff, and groundwater from springs. Evaporation of surface <span class="hlt">water</span> in the former Chalco Lake caused concentration of dissolved salts and enrichment in the heavy isotopes 18O and 2H. During high <span class="hlt">water</span> periods, the south easternmost ancient Lake Chalco fed partially evaporated <span class="hlt">water</span> to the closed Lake Texcoco, the lowest of the lakes, where further evaporation occurred causing higher concentration of salts and enrichment of heavy isotopes. These major ions and stable isotopes follow the evaporation trends characteristic of closed or nearly closed evaporatic basins elsewhere in the world. Paleo-lake evaporation lines in Lakes Chalco and Texcoco originated from the same starting <span class="hlt">water</span> and developed as a consequence of the topographic position of the former lakes and local climatological conditions. A modern evaporation line developed after the drainage of the lakes, reflecting evaporation of modern infiltrating meteoric <span class="hlt">water</span>. The presence of brackish <span class="hlt">pore</span> <span class="hlt">water</span> in most of the Chalco aquitard, which has a maximum thickness of 300 m, indicates that upward vertical groundwater flow has not been capable of displacing the paleo-lake <span class="hlt">water</span>. This suggests that vertical advection was not significant throughout the hundreds of thousands of years of existence of the aquitard sediments. One-dimensional numerical simulations of the deeper part of the 18O profile representing the thicker part of the aquitard sediments, 140 m, showed that this profile was developed by molecular diffusion with a small upward advective flux, where apparently the Chalco aquitard always had enriched brackish <span class="hlt">water</span> overlying the fresh <span class="hlt">water</span> aquifer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.1172T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.1172T"><span>Gas Hydrate and <span class="hlt">Pore</span> Pressure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tinivella, Umberta; Giustiniani, Michela</p> <p>2014-05-01</p> <p>Many efforts have been devoted to quantify excess <span class="hlt">pore</span> pressures related to gas hydrate dissociation in <span class="hlt">marine</span> sediments below the BSR using several approaches. Dissociation of gas hydrates in proximity of the BSR, in response to a change in the physical environment (i.e., temperature and/or pressure regime), can liberate excess gas incrising the local <span class="hlt">pore</span> fluid pressure in the sediment, so decreasing the effective normal stress. So, gas hydrate dissociation may lead to excess <span class="hlt">pore</span> pressure resulting in sediment deformation or failure, such as submarine landslides, sediment slumping, pockmarks and mud volcanoes, soft-sediment deformation and giant hummocks. Moreover, excess <span class="hlt">pore</span> pressure may be the result of gas hydrate dissociation due to continuous sedimentation, tectonic uplift, sea level fall, heating or inhibitor injection. In order to detect the presence of the overpressure below the BSR, we propose two approachs. The fist approach models the BSR depth versus <span class="hlt">pore</span> pressure; in fact, if the free gas below the BSR is in overpressure condition, the base of the gas hydrate stability is deeper with respect to the hydrostatic case. This effect causes a discrepancy between seismic and theoretical BSR depths. The second approach models the velocities versus gas hydrate and free gas concentrations and <span class="hlt">pore</span> pressure, considering the approximation of the Biot theory in case of low frequency, i.e. seismic frequency. Knowing the P and S seismic velocity from seismic data analysis, it is possibile to jointly estimate the gas hydrate and free gas concentrations and the <span class="hlt">pore</span> pressure regime. Alternatively, if the S-wave velocity is not availbale (due to lack of OBS/OBC data), an AVO analysis can be performed in order to extract information about Poisson ratio. Our modeling suggests that the areas characterized by shallow <span class="hlt">waters</span> (i.e., areas in which human infrastructures, such as pipelines, are present) are significantly affected by the presence of overpressure condition</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017363','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017363"><span>Differential equations governing slip-induced <span class="hlt">pore</span>-pressure fluctuations in a <span class="hlt">water</span>-saturated granular medium</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Iverson, R.M.</p> <p>1993-01-01</p> <p>Macroscopic frictional slip in <span class="hlt">water</span>-saturated granular media occurs commonly during landsliding, surface faulting, and intense bedload transport. A mathematical model of dynamic <span class="hlt">pore</span>-pressure fluctuations that accompany and influence such sliding is derived here by both inductive and deductive methods. The inductive derivation shows how the governing differential equations represent the physics of the steadily sliding array of cylindrical fiberglass rods investigated experimentally by Iverson and LaHusen (1989). The deductive derivation shows how the same equations result from a novel application of Biot's (1956) dynamic mixture theory to macroscopic deformation. The model consists of two linear differential equations and five initial and boundary conditions that govern solid displacements and <span class="hlt">pore-water</span> pressures. Solid displacements and <span class="hlt">water</span> pressures are strongly coupled, in part through a boundary condition that ensures mass conservation during irreversible <span class="hlt">pore</span> deformation that occurs along the bumpy slip surface. Feedback between this deformation and the <span class="hlt">pore</span>-pressure field may yield complex system responses. The dual derivations of the model help explicate key assumptions. For example, the model requires that the dimensionless parameter B, defined here through normalization of Biot's equations, is much larger than one. This indicates that solid-fluid coupling forces are dominated by viscous rather than inertial effects. A tabulation of physical and kinematic variables for the rod-array experiments of Iverson and LaHusen and for various geologic phenomena shows that the model assumptions commonly are satisfied. A subsequent paper will describe model tests against experimental data. ?? 1993 International Association for Mathematical Geology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26829659','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26829659"><span>Colloid Mobilization in a Fractured Soil: Effect of <span class="hlt">Pore-Water</span> Exchange between Preferential Flow Paths and Soil Matrix.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mohanty, Sanjay K; Saiers, James E; Ryan, Joseph N</p> <p>2016-03-01</p> <p>Exchange of <span class="hlt">water</span> and solutes between contaminated soil matrix and bulk solution in preferential flow paths has been shown to contribute to the long-term release of dissolved contaminants in the subsurface, but whether and how this exchange can affect the release of colloids in a soil are unclear. To examine this, we applied rainfall solutions of different ionic strength on an intact soil core and compared the resulting changes in effluent colloid concentration through multiple sampling ports. The exchange of <span class="hlt">water</span> between soil matrix and the preferential flow paths leading to each port was characterized on the basis of the bromide (conservative tracer) breakthrough time at the port. At individual ports, two rainfalls of a certain ionic strength mobilized different amounts of colloids when the soil was pre-exposed to a solution of lower or higher ionic strength. This result indicates that colloid mobilization depended on rainfall solution history, which is referred as colloid mobilization hysteresis. The extent of hysteresis was increased with increases in exchange of <span class="hlt">pore</span> <span class="hlt">water</span> and solutes between preferential flow paths and matrix. The results indicate that the soil matrix exchanged the old <span class="hlt">water</span> from the previous infiltration with new infiltrating <span class="hlt">water</span> during successive infiltration and changed the <span class="hlt">pore</span> <span class="hlt">water</span> chemistry in the preferential flow paths, which in turn affected the release of soil colloids. Therefore, rainfall solution history and soil heterogeneity must be considered to assess colloid mobilization in the subsurface. These findings have implications for the release of colloids, colloid-associated contaminants, and pathogens from soils.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNH41C1830H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNH41C1830H"><span>Seasonal Effects on the Relationships Between Soil <span class="hlt">Water</span> Content, <span class="hlt">Pore</span> <span class="hlt">Water</span> Pressure and Shear Strength and Their Implications for Slope Stability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hughes, P. N.</p> <p>2015-12-01</p> <p>A soil's shear resistance is mainly dependent upon the magnitude of effective stress. For small to medium height slopes (up to 10m) in clay soils the total stress acting along potential failure planes will be low, therefore the magnitude of effective stress (and hence soil shear strength) will be dominated by the <span class="hlt">pore-water</span> pressure. The stability of slopes on this scale through periods of increased precipitation is improved by the generation of negative <span class="hlt">pore</span> pressures (soil suctions) during preceding, warmer, drier periods. These negative <span class="hlt">pore</span> <span class="hlt">water</span> pressures increase the effective stress within the soil and cause a corresponding increase in shearing resistance. The relationships between soil <span class="hlt">water</span> content and <span class="hlt">pore</span> <span class="hlt">water</span> pressure (soil <span class="hlt">water</span> retention curves) are known to be hysteretic, but for the purposes of the majority of slope stability assessments in partially saturated clay soils, these are assumed to be consistent with time. Similarly, the relationship between shear strength and <span class="hlt">water</span> content is assumed to be consistent over time. This research presents a laboratory study in which specimens of compacted Glacial Till (typical of engineered slopes within the UK) were subjected to repeated cycles of wetting and drying to simulate seasonal cycles. At predetermined <span class="hlt">water</span> contents, measurements of soil suction were made using tensiometer and dewpoint potentiometer methods. The undrained shear strength of the specimens was then measured using triaxial strength testing equipment. Results indicate that repeated wetting and drying cycles caused a change in the soil <span class="hlt">water</span> retention behaviour. A reduction in undrained shear strength at corresponding <span class="hlt">water</span> contents along the wetting and drying paths was also observed. The mechanism for the change in the relationship is believed to be a deterioration in the soil physical structure due to shrink/swell induced micro-cracking. The non-stationarity of these relationships has implications for slope stability assessment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989CSR.....9..767F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989CSR.....9..767F"><span>Variations of nitrogen nutrient concentrations in the sediment <span class="hlt">pore</span> <span class="hlt">waters</span> of the northwestern Mediterranean continental shelf</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fernex, François; Baratie, Raymond; Span, Daniel; Vandelei Fernandes, Lazaro</p> <p>1989-09-01</p> <p>This contribution presents information on nitrogen nutrients dissolved in the sediment <span class="hlt">pore</span> <span class="hlt">waters</span> of the oligotrophic northwestern Mediterranean Sea. The areas studied are situated in various geographical environments, adjacent to or offshore from a river mouth and on wide or narrow parts of the continental shelf. Near the pro-delta of the Rhoˆne River, which carries about 5 × 10 6 t y -1 of solid matter, measurements indicate that the rate of nitrogen nutrient production (ammonification) reaches frequently (or even exceeds) 2 × 10 6 μmol cm -3 s -1. The production rate near the mouth of the Siagne River, a mountain stream, is generally lower, at 10 -7 μmol -3 s -1; exceptionally, it reaches 10 6 to 1.5 × 10 -6 μmol cm -3 s -1. Adjacent to any river mouth, the concentrations of inorganic nitrogen species dissolved in the surficial sediments vary with time. A similar pattern occurs at locations far from a river mouth. High levels of organic matter in the sediments in the latter areas is related to planktonic blooms, which occur mainly in spring. There is more temporal variation in concentrations in sediments just below the sediment-seawater boundary, than in the deeper deposits. Ammonia concentrations increase regularly, with depth, within the sediment. In contrast, the nitrate profiles are frequently irregular and show a concentration maximum at 1 or 2 cm below the interface; then, below a minimum value at 5-8 cm, then a second maximum at 10-15 cm. According to incubation experiments, the production of nitrate occurs at 15-20 cm, where oxygen is still present at concentrations higher than 1-1.5 mg l -1. The low nitrate concentrations at about 6-8 cm appear to result from relatively high denitrifying activity at this level within the sediments. Concentrations of the nitrogen nutrients are generally higher in the surficial sediment <span class="hlt">pore</span> <span class="hlt">waters</span>, than in the overlying seawater. There is a flux of these species from the sediment to the seawater. In continental</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70025689','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70025689"><span>Chemical analyses of <span class="hlt">pore</span> <span class="hlt">water</span> from boreholes USW SD-6 and USW WT-24, Yucca Mountain, Nevada</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Yang, I.C.; Peterman, Z.E.; Scofield, K.M.</p> <p>2003-01-01</p> <p>Analyses of <span class="hlt">pore</span> <span class="hlt">water</span> extracted from cores of boreholes USW SD-6 in the central part and USW WT-24 in the northern part of Yucca Mountain, Nevada, show significant vertical and lateral variations in dissolved-ion concentrations. Analyses of samples of only a few milliliters of <span class="hlt">pore</span> <span class="hlt">water</span> extracted by uniaxial or triaxial compression and by ultracentrifugation methods from adjacent core samples are generally in agreement, within the analytical error of 10% to 15%. However, the values of silica for <span class="hlt">water</span> obtained by ultracentrifugation are consistently lower than values for <span class="hlt">water</span> obtained by compression. The larger concentrations probably are due to localized pressure solution of silicate minerals during compression. The shallower <span class="hlt">water</span> from core in borehole USW SD-6 was extracted from nonwelded units collectively referred to as the Paintbrush Tuff nonwelded (PTn). The deeper <span class="hlt">water</span> was from core in both boreholes USW SD-6 and USW WT-24 in the nonwelded units referred to as the Calico Hills nonwelded (CHn). Significant differences in mean dissolved-ion concentrations in <span class="hlt">pore</span> <span class="hlt">water</span> between the PTn and CHn are (1) decreases in Ca, Mg, SO4, and NO3 and (2) increases in HCO3 and (Na+K)/(Ca+Mg) ratios. The decrease in NO3 and the increase in HCO3 could be the result of denitrification through the oxidation of organic matter. The decrease in Ca and associated increase in (Na+K)/(Ca+Mg) is the result of ion exchange with zeolites in the CHn in borehole USW WT-24. This effect is not nearly as pronounced in borehole USW SD-6, probably reflecting a smaller amount of zeolitization of the CHn in USW SD-6. Geochemical calculations using the PHREEQC code indicate that the <span class="hlt">pore</span> <span class="hlt">water</span> from both boreholes USW SD-6 and USW WT-24 is uniformly undersaturated in anhydrite, gypsum, and amorphous silica, but supersaturated in quartz and chalcedony. The saturation of calcite, aragonite, sepiolite, and dolomite is more variable from sample to sample. ?? 2002 Elsevier Science B.V. All rights</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/949046','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/949046"><span>A <span class="hlt">pore</span>-scale model of two-phase flow in <span class="hlt">water</span>-wet rock</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Silin, Dmitriy; Patzek, Tad</p> <p>2009-02-01</p> <p>A finite-difference discretization of Stokes equations is used to simulate flow in the <span class="hlt">pore</span> space of natural rocks. Numerical solutions are obtained using the method of artificial compressibility. In conjunction with Maximal Inscribed Spheres method, these computations produce relative permeability curves. The results of computations are in agreement with laboratory measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27389452','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27389452"><span>Prevalence of microplastics in the <span class="hlt">marine</span> <span class="hlt">waters</span> of Qatar.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Castillo, Azenith B; Al-Maslamani, Ibrahim; Obbard, Jeffrey Philip</p> <p>2016-10-15</p> <p>Microplastics are firmly recognized as a ubiquitous and growing threat to <span class="hlt">marine</span> biota and their associated <span class="hlt">marine</span> habitats worldwide. The evidence of the prevalence of microplastics was documented for the first time in the <span class="hlt">marine</span> <span class="hlt">waters</span> of Qatar's Exclusive Economic Zone (EEZ). An optimized and validated protocol was developed for the extraction of microplastics from plankton-rich seawater samples without loss of microplastic debris present and characterized using Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy. In total 30 microplastic polymers have been identified with an average concentration of 0.71particlesm(-3) (range 0-3particlesm(-3)). Polypropylene, low density polyethylene, polyethylene, polystyrene, polyamide, polymethyl methacrylate, cellophane, and acrylonitrile butadiene styrene polymers were characterized with majority of the microplastics either granular shape, sizes ranging from 125μm to 1.82mm or fibrous with sizes from 150μm to 15.98mm. The microplastics are evident in areas where nearby anthropogenic activities, including oil-rig installations and shipping operations are present.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/837485','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/837485"><span>Strontium Isotopes in <span class="hlt">Pore</span> <span class="hlt">Water</span> as an Indicator of <span class="hlt">Water</span> Flux at the Proposed High-Level Radioactive Waste Repository, Yucca Mountain, Nevada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>B. Marshall; K. Futa</p> <p>2004-02-19</p> <p>The proposed high-level radioactive waste repository at Yucca Mountain, Nevada, would be constructed in the high-silica rhyolite (Tptp) member of the Miocene-age Topopah Spring Tuff, a mostly welded ash-flow tuff in the {approx}500-m-thick unsaturated zone. Strontium isotope compositions have been measured in <span class="hlt">pore</span> <span class="hlt">water</span> centrifuged from preserved core samples and in leachates of <span class="hlt">pore-water</span> salts from dried core samples, both from boreholes in the Tptp. Strontium isotope ratios ({sup 87}Sr/{sup 86}Sr) vary systematically with depth in the surface-based boreholes. Ratios in <span class="hlt">pore</span> <span class="hlt">water</span> near the surface (0.7114 to 0.7124) reflect the range of ratios in soil carbonate (0.7112 to 0.7125) collected near the boreholes, but ratios in the Tptp (0.7122 to 0.7127) at depths of 150 to 370 m have a narrower range and are more radiogenic due to interaction with the volcanic rocks (primarily non-welded tuffs) above the Tptp. An advection-reaction model relates the rate of strontium dissolution from the rocks with flow velocity. The model results agree with the low transport velocity ({approx}2 cm per year) calculated from carbon-14 data by I.C. Yang (2002, App. Geochem., v. 17, no. 6, p. 807-817). Strontium isotope ratios in <span class="hlt">pore</span> <span class="hlt">water</span> from Tptp samples from horizontal boreholes collared in tunnels at the proposed repository horizon have a similar range (0.7121 to 0.7127), also indicating a low transport velocity. Strontium isotope compositions of <span class="hlt">pore</span> <span class="hlt">water</span> below the proposed repository in core samples from boreholes drilled vertically downward from tunnel floors are more varied, ranging from 0.7112 to 0.7127. The lower ratios (<0.7121) indicate that some of the <span class="hlt">pore</span> <span class="hlt">water</span> in these boreholes was replaced by tunnel construction <span class="hlt">water</span>, which had an {sup 87}Sr/{sup 86}Sr of 0.7115. Ratios lower than 0.7115 likely reflect interaction of construction <span class="hlt">water</span> with concrete in the tunnel inverts, which had an {sup 87}Sr/{sup 86}Sr < 0.709. These low Sr ratios indicate penetration of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12171411','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12171411"><span>A new rechargeable dialysis <span class="hlt">pore</span> <span class="hlt">water</span> sampler for monitoring sub-aqueous in-situ sediment caps.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jacobs, Patrick H</p> <p>2002-07-01</p> <p>A new rechargeable dialysis <span class="hlt">pore</span> <span class="hlt">water</span> sampler is proposed that is adapted to the requirements of monitoring in-situ sediment remediation techniques, in particular in-situ capping. Sampling and recharging of the sampler can be carried out from a boat or a pontoon by means of separate tubing and a peristaltic pump. The possibility of repeated sampling permits a temporal as well as a spatial resolution of <span class="hlt">pore</span> <span class="hlt">water</span> geochemistry. This aims to facilitate a monitoring of temporal variations in contaminant profiles within a cap matrix. To meet these particular requirements the basic peeper design is modified. In this manuscript constructive details and materials used are discussed as well as the feasibility and reliability of the sampling and recharging process. The peeper is designed for I m depth profile with spatial resolution of 1/5.5cm and the practical temporal resolution, that chiefly depends on sediment characteristics, is 1/3 weeks. Results from laboratory and field testing show that sample volumes of 20 cm3 can be obtained from a depth of 8 m without mixing of sample and recharge <span class="hlt">water</span>. The field test results with an exposure time of 8 months indicate that no clogging of neither the membranes nor the sample tubing occurred. The temporal development of the concentration-vs. -depth profiles of sodium, iron, and nickle, chosen as examples from the investigated metals in the <span class="hlt">pore</span> <span class="hlt">water</span>, document the stability of the monitoring system. The results thus corroborate that this new type of sampler can be employed as a tool for monitoring contaminants at the sediment-to-<span class="hlt">water</span> interface and particularly within an in-situ cap.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24704964','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24704964"><span>Response of <span class="hlt">pore</span> <span class="hlt">water</span> Al, Fe and S concentrations to waterlogging in a boreal acid sulphate soil.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Virtanen, Seija; Simojoki, Asko; Hartikainen, Helinä; Yli-Halla, Markku</p> <p>2014-07-01</p> <p>Environmental hazards caused by acid sulphate (AS) soils are of worldwide concern. Among various mitigation measures, waterlogging has mainly been studied in subtropical and tropical conditions. To assess the environmental relevance of waterlogging as a mitigation option in boreal AS soils, we arranged a 2.5-year experiment with monolithic lysimeters to monitor changes in the soil redox potential, pH and the concentrations of aluminium (Al), iron (Fe) and sulphur (S) in <span class="hlt">pore</span> <span class="hlt">water</span> in response to low and high groundwater levels in four AS soil horizons. The monoliths consisted of acidic oxidized B horizons and a reduced C horizon containing sulphidic material. Eight lysimeters were cropped (reed canary grass, Phalaris arundinacea) and two were bare without a crop. Waterlogging was conducive to reduction reactions causing a slight rise in pH, a substantial increase in Fe (Fepw) and a decrease in Al (Alpw) in the <span class="hlt">pore</span> <span class="hlt">water</span>. The increase in Fepw was decisively higher in the cropped waterlogged lysimeters than in the bare ones, which was attributable to the microbiologically catalysed reductive dissolution of poorly ordered iron oxides and secondary minerals. In contrast to warmer climates, Fepw concentrations remained high throughout the experiment, indicating that the reduction was poised in the iron range, while sulphate was not reduced to sulphide. Therefore, the precipitation of iron sulphide was negligible in the environment with a low pH and abundant with poorly ordered Fe oxides. Increased Fe in <span class="hlt">pore</span> <span class="hlt">water</span> counteracts the positive effects of waterlogging, when <span class="hlt">water</span> is flushed from fields to watercourses, where re-oxidation of Fe causes acidity and oxygen depletion. However, waterlogging prevented further oxidation of sulphidic materials and decreased Alpw to one-tenth of the initial concentrations, and even to one-hundredth of the levels in the low <span class="hlt">water</span> table lysimeters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70156341','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70156341"><span>An overview of <span class="hlt">marine</span> biodiversity in United States <span class="hlt">waters</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Fautin, Daphne G.; Delton, Penelope; Incze, Lewis S.; Leong, Jo-Ann C.; Pautzke, Clarence; Rosenberg, Andrew A.; Sandifer, Paul; Sedberry, George R.; Tunnell, John W.; Abbott, Isabella; Brainard, Russell E.; Brodeur, Melissa; Eldredge, Lucius G.; Feldman, Michael; Moretzsohn, Fabio; Vroom, Peter S.; Wainstein, Michelle; Wolff, Nicholas</p> <p>2010-01-01</p> <p><span class="hlt">Marine</span> biodiversity of the United States (U.S.) is extensively documented, but data assembled by the United States National Committee for the Census of <span class="hlt">Marine</span> Life demonstrate that even the most complete taxonomic inventories are based on records scattered in space and time. The best-known taxa are those of commercial importance. Body size is directly correlated with knowledge of a species, and knowledge also diminishes with distance from shore and depth. Measures of biodiversity other than species diversity, such as ecosystem and genetic diversity, are poorly documented. Threats to <span class="hlt">marine</span> biodiversity in the U.S. are the same as those for most of the world: overexploitation of living resources; reduced <span class="hlt">water</span> quality; coastal development; shipping; invasive species; rising temperature and concentrations of carbon dioxide in the surface ocean, and other changes that may be consequences of global change, including shifting currents; increased number and size of hypoxic or anoxic areas; and increased number and duration of harmful algal blooms. More information must be obtained through field and laboratory research and monitoring that involve innovative sampling techniques (such as genetics and acoustics), but data that already exist must be made accessible. And all data must have a temporal component so trends can be identified. As data are compiled, techniques must be developed to make certain that scales are compatible, to combine and reconcile data collected for various purposes with disparate gear, and to automate taxonomic changes. Information on biotic and abiotic elements of the environment must be interactively linked. Impediments to assembling existing data and collecting new data on <span class="hlt">marine</span> biodiversity include logistical problems as well as shortages in finances and taxonomic expertise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20689852','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20689852"><span>An overview of <span class="hlt">marine</span> biodiversity in United States <span class="hlt">waters</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fautin, Daphne; Dalton, Penelope; Incze, Lewis S; Leong, Jo-Ann C; Pautzke, Clarence; Rosenberg, Andrew; Sandifer, Paul; Sedberry, George; Tunnell, John W; Abbott, Isabella; Brainard, Russell E; Brodeur, Melissa; Eldredge, Lucius G; Feldman, Michael; Moretzsohn, Fabio; Vroom, Peter S; Wainstein, Michelle; Wolff, Nicholas</p> <p>2010-08-02</p> <p><span class="hlt">Marine</span> biodiversity of the United States (U.S.) is extensively documented, but data assembled by the United States National Committee for the Census of <span class="hlt">Marine</span> Life demonstrate that even the most complete taxonomic inventories are based on records scattered in space and time. The best-known taxa are those of commercial importance. Body size is directly correlated with knowledge of a species, and knowledge also diminishes with distance from shore and depth. Measures of biodiversity other than species diversity, such as ecosystem and genetic diversity, are poorly documented. Threats to <span class="hlt">marine</span> biodiversity in the U.S. are the same as those for most of the world: overexploitation of living resources; reduced <span class="hlt">water</span> quality; coastal development; shipping; invasive species; rising temperature and concentrations of carbon dioxide in the surface ocean, and other changes that may be consequences of global change, including shifting currents; increased number and size of hypoxic or anoxic areas; and increased number and duration of harmful algal blooms. More information must be obtained through field and laboratory research and monitoring that involve innovative sampling techniques (such as genetics and acoustics), but data that already exist must be made accessible. And all data must have a temporal component so trends can be identified. As data are compiled, techniques must be developed to make certain that scales are compatible, to combine and reconcile data collected for various purposes with disparate gear, and to automate taxonomic changes. Information on biotic and abiotic elements of the environment must be interactively linked. Impediments to assembling existing data and collecting new data on <span class="hlt">marine</span> biodiversity include logistical problems as well as shortages in finances and taxonomic expertise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2914028','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2914028"><span>An Overview of <span class="hlt">Marine</span> Biodiversity in United States <span class="hlt">Waters</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Fautin, Daphne; Dalton, Penelope; Incze, Lewis S.; Leong, Jo-Ann C.; Pautzke, Clarence; Rosenberg, Andrew; Sandifer, Paul; Sedberry, George; Tunnell, John W.; Abbott, Isabella; Brainard, Russell E.; Brodeur, Melissa; Eldredge, Lucius G.; Feldman, Michael; Moretzsohn, Fabio; Vroom, Peter S.; Wainstein, Michelle; Wolff, Nicholas</p> <p>2010-01-01</p> <p><span class="hlt">Marine</span> biodiversity of the United States (U.S.) is extensively documented, but data assembled by the United States National Committee for the Census of <span class="hlt">Marine</span> Life demonstrate that even the most complete taxonomic inventories are based on records scattered in space and time. The best-known taxa are those of commercial importance. Body size is directly correlated with knowledge of a species, and knowledge also diminishes with distance from shore and depth. Measures of biodiversity other than species diversity, such as ecosystem and genetic diversity, are poorly documented. Threats to <span class="hlt">marine</span> biodiversity in the U.S. are the same as those for most of the world: overexploitation of living resources; reduced <span class="hlt">water</span> quality; coastal development; shipping; invasive species; rising temperature and concentrations of carbon dioxide in the surface ocean, and other changes that may be consequences of global change, including shifting currents; increased number and size of hypoxic or anoxic areas; and increased number and duration of harmful algal blooms. More information must be obtained through field and laboratory research and monitoring that involve innovative sampling techniques (such as genetics and acoustics), but data that already exist must be made accessible. And all data must have a temporal component so trends can be identified. As data are compiled, techniques must be developed to make certain that scales are compatible, to combine and reconcile data collected for various purposes with disparate gear, and to automate taxonomic changes. Information on biotic and abiotic elements of the environment must be interactively linked. Impediments to assembling existing data and collecting new data on <span class="hlt">marine</span> biodiversity include logistical problems as well as shortages in finances and taxonomic expertise. PMID:20689852</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70042340','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70042340"><span><span class="hlt">Pore-water</span> chemistry from the ICDP-USGS coer hole in the Chesapeake Bay impact structure--Implications for paleohydrology, microbial habitat, and <span class="hlt">water</span> resources</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sanford, Ward E.; Voytek, Mary A.; Powars, David S.; Jones, Blair F.; Cozzarelli, Isabelle M.; Eganhouse, Robert P.; Cockell, Charles S.</p> <p>2009-01-01</p> <p>We investigated the groundwater system of the Chesapeake Bay impact structure by analyzing the <span class="hlt">pore-water</span> chemistry in cores taken from a 1766-m-deep drill hole 10 km north of Cape Charles, Virginia. <span class="hlt">Pore</span> <span class="hlt">water</span> was extracted using high-speed centrifuges from over 100 cores sampled from a 1300 m section of the drill hole. The <span class="hlt">pore-water</span> samples were analyzed for major cations and anions, stable isotopes of <span class="hlt">water</span> and sulfate, dissolved and total carbon, and bioavailable iron. The results reveal a broad transition between fresh and saline <span class="hlt">water</span> from 100 to 500 m depth in the post-impact sediment section, and an underlying syn-impact section that is almost entirely filled with brine. The presence of brine in the lowermost post-impact section and the trend in the dissolved chloride with depth suggest a transport process dominated by molecular diffusion and slow, compaction-driven, upward flow. Major ion results indicate residual effects of diagenesis from heating, and a pre-impact origin for the brine. High levels of dissolved organic carbon (6-95 mg/L) and the distribution of electron acceptors indicate an environment that may be favorable for microbial activity throughout the drilled section. The concentration and extent of the brine is much greater than had previously been observed, suggesting its occurrence may be common in the inner crater. However, groundwater flow conditions in the structure may reduce the salt-<span class="hlt">water</span>-intrusion hazard associated with the brine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26490407','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26490407"><span>Changes in the <span class="hlt">water</span> quality conditions of Kuwait's <span class="hlt">marine</span> <span class="hlt">waters</span>: Long term impacts of nutrient enrichment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Devlin, M J; Massoud, M S; Hamid, S A; Al-Zaidan, A; Al-Sarawi, H; Al-Enezi, M; Al-Ghofran, L; Smith, A J; Barry, J; Stentiford, G D; Morris, S; da Silva, E T; Lyons, B P</p> <p>2015-11-30</p> <p>This work analyses a 30 year <span class="hlt">water</span> quality data set collated from chemical analyses of Kuwait's <span class="hlt">marine</span> <span class="hlt">waters</span>. Spatial patterns across six sites in Kuwait Bay and seven sites located in the Arabian Gulf are explored and discussed in terms of the changing influences associated with point and diffuse sources. Statistical modelling demonstrated significant increases for dissolved nutrients over the time period. Kuwait <span class="hlt">marine</span> <span class="hlt">waters</span> have been subject to inputs from urban development, untreated sewage discharges and decreasing river flow from the Shatt al-Arab River. Chlorophyll biomass showed a small but significant reduction; the high sewage content of the coastal <span class="hlt">waters</span> from sewage discharges likely favouring the presence of smaller phytoplankton taxa. This detailed assessment of temporal data of the impacts of sewage inputs into Kuwait's coastal <span class="hlt">waters</span> establishes an important baseline permitting future assessments to be made as sewage is upgraded, and the river continues to be extracted upstream.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/391144','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/391144"><span>Acute toxicity of saline produced <span class="hlt">waters</span> to <span class="hlt">marine</span> organisms</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pillard, D.A.; Evans, J.M.; DuFresne, D.L.</p> <p>1996-11-01</p> <p>Produced <span class="hlt">waters</span> from oil and gas drilling operations are typically very saline, and may cause acute toxicity to <span class="hlt">marine</span> organisms due imbalances as well as to an excess or deficiency of to osmotic specific common ions. In order to better understand the relationship between toxicity and ion concentration, laboratory toxicity tests were conducted using mysid shrimp (Mysidopsis bahia), sheepshead minnow, (Cyprinodon variegatus), and inland silvemide (Menidia beryllina). For each species the ionic concentration of standard laboratory <span class="hlt">water</span> was proportionally increased or decreased to produce test solutions with a range of salinities. Individual ions (sodium, potassium, calcium, magnesium, strontium, chloride, bromide, sulfate, bicarbonate, and borate) were also manipulated to examine individual ion toxicity. Organisms were exposed for 48 hours. The three test species differ in their tolerance of salinity. Mysid shrimp show a marked decrease in survival at salinities less than approximately 5 ppt. Both fish species tolerated low salinity <span class="hlt">water</span>, however, silversides were less tolerant of saline <span class="hlt">waters</span> (salinity greater than 40 ppt). There were also significant differences in the responses of the organisms to different ions. The results show that salinity of the test solution may play an important role in the responses of the organisms to produced <span class="hlt">water</span> effluent. Predictable toxicity/ion relationships developed in this study can be used to estimate whether toxicity in produced <span class="hlt">water</span> is a result of common ions, salinity, or some other unknown toxicant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/27903','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/27903"><span>Chapter 21: Oceanographic Processes and <span class="hlt">Marine</span> Productivity in <span class="hlt">Waters</span> Offshore of Marbled Murrelet Breeding Habitat</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Jr. Hunt</p> <p>1995-01-01</p> <p>Marbled Murrelets (Brachyramphus marmoratus) occupy nearshore <span class="hlt">waters</span> in the eastern North Pacific Ocean from central California to the Aleutian Islands. The offshore <span class="hlt">marine</span> ecology of these <span class="hlt">waters</span> is dominated by a series of currents roughly parallel to the coast that determine <span class="hlt">marine</span> productivity of shelf <span class="hlt">waters</span> by influencing the rate of nutrient...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/962849','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/962849"><span>Electrical Resistivity Correlation to Vadose Zone Sediment and <span class="hlt">Pore-Water</span> Composition for the BC Cribs and Trenches Area</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Serne, R. Jeffrey; Ward, Anderson L.; Um, Wooyong; Bjornstad, Bruce N.; Rucker, Dale F.; Lanigan, David C.; Benecke, Mark W.</p> <p>2009-06-01</p> <p>This technical report documents the results of geochemical and soil resistivity characterization of sediment obtained from four boreholes drilled in the BC Cribs and Trench area. Vadose zone sediment samples were obtained at a frequency of about every 2.5 ft from approximately 5 ft bgs to borehole total depth. In total, 505 grab samples and 39 six-inch long cores were obtained for characterization. The <span class="hlt">pore-water</span> chemical composition data, laboratory-scale soil resistivity and other ancillary physical and hydrologic measurements and analyses described in this report are designed to provide a crucial link between direct measurements on sediments and the surface-based electrical-resistivity information obtained via field surveys. A second goal of the sediment characterization was to measure the total and <span class="hlt">water</span>-leachable concentrations of key contaminants of concern as a function of depth and distance from the footprints of inactive disposal facilities. The total and <span class="hlt">water</span>-leachable concentrations of key contaminants will be used to update contaminant distribution conceptual models and to provide more data for improving base-line risk predictions and remedial alternative selections. The ERC “ground truthing” exercise for the individual boreholes showed mixed results. In general, the high concentrations of dissolved salts in the <span class="hlt">pore</span> <span class="hlt">waters</span> of sediments from C5923, C5924 and C4191 produced a low resistivity “target” in the processed resistivity field surveys, and variability could be seen in the resistivity data that could relate to the variability in <span class="hlt">pore</span>- <span class="hlt">water</span> concentrations but the correlations (regression R2 were mediocre ranging from 0.2 to 0.7 at best; where perfect correlation is 1.0). The field-based geophysical data also seemed to suffer from a sort of vertigo, where looking down from the ground surface, the target (e.g., maximum <span class="hlt">pore-water</span> salt concentration) depth was difficult to resolve. The best correlations between the field electrical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.B11D0378G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.B11D0378G"><span><span class="hlt">Pore</span> <span class="hlt">water</span> chemistry in a disturbed and an undisturbed peat forests in Brunei Darussalam: Nutrient and carbon contents</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gandois, L.; Cobb, A.; Abu Salim, K.; Chieng Hei, I.; Lim Biaw Leng, L.; Corlett, R.; Harvey, C.</p> <p>2010-12-01</p> <p>Tropical peat swamp forests in their natural state are important reservoir of biodiversity, carbon and <span class="hlt">water</span>. However, they are rapidly vanishing due to agricultural conversion (mainly to oil palms), logging, drainage and fire. Peat swamp forests constitute an important contribution to global and regional biodiversity, providing an habitat to rare and threatened species. They encompass a sequence of forest types from the perimeter to the center of mildely elevated domes, and at our site in Brunei, are host to Shorea Albida trees (Anderson, 1983). They constitute a large terrestrial carbon reservoir (tropical peat soils contain up to 70 Pg C, which accounts for 20% of global peat soil carbon and 2% of the global soil carbon (Hirano et al., 2007)). In tropical peat swamp forests, the most important factors controling organic matter accumulation, as well as the biodiversity and structure of the forest, are hydrology and nutrients availability (Page et al., 1999). Study of <span class="hlt">pore</span> <span class="hlt">water</span> in peat swamp forest can provide key information on carbon cycle, including biomass production, organic matter decomposition and leaching of carbon in draining <span class="hlt">water</span>. However, data on <span class="hlt">pore</span> <span class="hlt">water</span> chemistry and nutrient concentrations in pristine tropical peatlands, as well as the effect of forest exploitation are scarce. The study area is located in the Belait district in Brunei Darussalam in Borneo Island. Brunei is perhaps the best of the regional guardians of peat forest systems; potentially irreversible damage to peat forest ecosystems has been widespread elsewhere. Two sites, one pristine dome and a logging concession, are being investigated. In order to assess the chemical status of the peat soil, <span class="hlt">pore</span> <span class="hlt">water</span> is sampled at different depth along the dome radius. The chemistry of <span class="hlt">pore</span> <span class="hlt">water</span>, including pH, conductivity, dissolved oxygen, concentration of major elements, as well as organic carbon content and properties are analyzed. References: Anderson, 1983. The tropical peat swamp of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.water.usgs.gov/sir2005-5036/','USGSPUBS'); return false;" href="http://pubs.water.usgs.gov/sir2005-5036/"><span>Pushpoint sampling for defining spatial and temporal variations in contaminant concentrations in sediment <span class="hlt">pore</span> <span class="hlt">water</span> near the ground-<span class="hlt">water</span> / surface-<span class="hlt">water</span> interface</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Zimmerman, Marc J.; Massey, Andrew J.; Campo, Kimberly W.</p> <p>2005-01-01</p> <p>During four periods from April 2002 to June 2003, <span class="hlt">pore-water</span> samples were taken from river sediment within a gaining reach (Mill Pond) of the Sudbury River in Ashland, Massachusetts, with a temporary pushpoint sampler to determine whether this device is an effective tool for measuring small-scale spatial variations in concentrations of volatile organic compounds and selected field parameters (specific conductance and dissolved oxygen concentration). The <span class="hlt">pore</span> <span class="hlt">waters</span> sampled were within a subsurface plume of volatile organic compounds extending from the nearby Nyanza Chemical Waste Dump Superfund site to the river. Samples were collected from depths of 10, 30, and 60 centimeters below the sediment surface along two 10-meter-long, parallel transects extending into the river. Twenty-five volatile organic compounds were detected at concentrations ranging from less than 1 microgram per liter to hundreds of micrograms per liter (for example, 1,2-dichlorobenzene, 490 micrograms per liter; cis-1,2-dichloroethene, 290 micrograms per liter). The most frequently detected compounds were either chlorobenzenes or chlorinated ethenes. Many of the compounds were detected only infrequently. Quality-control sampling indicated a low incidence of trace concentrations of contaminants. Additional samples collected with passive-<span class="hlt">water</span>-diffusion-bag samplers yielded results comparable to those collected with the pushpoint sampler and to samples collected in previous studies at the site. The results demonstrate that the pushpoint sampler can yield distinct samples from sites in close proximity; in this case, sampling sites were 1 meter apart horizontally and 20 or 30 centimeters apart vertically. Moreover, the pushpoint sampler was able to draw <span class="hlt">pore</span> <span class="hlt">water</span> when inserted to depths as shallow as 10 centimeters below the sediment surface without entraining surface <span class="hlt">water</span>. The simplicity of collecting numerous samples in a short time period (routinely, 20 to 30 per day) validates the use of a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ESASP.722E.194U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ESASP.722E.194U"><span>Mapping <span class="hlt">Marine</span> Macroalgae In Case 2 <span class="hlt">Waters</span> Using CHRIS PROBA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Uhl, Florian; Oppelt, Natascha; Bartsch, Inka</p> <p>2013-12-01</p> <p><span class="hlt">Marine</span> macroalgae fulfil an important role in coastal ecosystems providing food and habitat for wildlife. The impacts of climate change and increasing human encroachment exert significant pressures on coastal ecosystems. Monitoring of <span class="hlt">marine</span> macroalgae communities provides information on the state of habitats and their structural changes. At landscape scale airborne remote sensing became an acknowledged tool to monitor coastal vegetation; for an operational use of macroalgae mapping, however, satellite remote sensing has significant advantages. In this paper, we therefore analyse the performance of three approaches to assess sublitoral macroalgae communities in the turbid coastal <span class="hlt">waters</span> around the island of Helgoland (North Sea, Germany) using CHRIS/Proba and EnMAP-like data. A Slope Based Index Classification, which has already been successfully applied in Helgolands intertidal zone during low tide, performed best; it was able to map the presence of sublitoral macroalgae with high accuracy (>80%) for both sensors. However successful detection of macroalgae was only achievable in <span class="hlt">water</span> depths up to 2m.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7000235','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7000235"><span>Metabolic regulation of amino acid uptake in <span class="hlt">marine</span> <span class="hlt">waters</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kirchman, D.L.; Hodson, R.E.</p> <p>1986-03-01</p> <p>To determine the relationships among the processes of uptake, intracellular pool formation, and incorporation of amino acids into protein, the authors measured the uptake of dipeptides and free amino acids by bacterial assemblages in estuarine and coastal <span class="hlt">waters</span> of the southeast US. The dipeptide phenylalanyl-phenylalanine (phe-phe) lowered V/sub max/ of phenylalanine uptake when the turnover rate of phenylalanine was relatively high. When the turnover rate was relatively low, phe-phe either had no effect or increased V/sub max/ of phenylalanine uptake. An analytical model was developed and tested to measure the turnover time of the intracellular pool of phenylalanine. The results suggested that the size of the intracellular pool is regulated, which precludes high assimilation rates of both phenylalanine and phe-phe. In <span class="hlt">waters</span> with relatively low phenylalanine turnover rates, bacterial assemblages appear to have a greater capacity to assimilate phenylalanine and phe-phe simultaneously. <span class="hlt">Marine</span> bacterial assemblages do not substantially increase the apparent respiration of amino acids when concentrations increase. The authors conclude that sustained increases in uptake rates and mineralization by <span class="hlt">marine</span> bacterial assemblages in response to an increase in the concentrations of dissolved organic nitrogen is determined by the rate of protein synthesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6654414','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6654414"><span>Sulfide variation in the <span class="hlt">pore</span> and surface <span class="hlt">waters</span> of artificial salt-marsh ditches and a natural tidal creek</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rey, J.R.; Shaffer, J.; Kain, T.; Stahl, R.; Crossman, R. )</p> <p>1992-09-01</p> <p><span class="hlt">Pore</span> and surface <span class="hlt">water</span> sulfide variation near artificial ditches and a natural creek are examined in salt marshes bordering the Indian River Lagoon in east-central Florida. <span class="hlt">Pore</span> <span class="hlt">water</span> sulfide concentrations ranged from 0 [mu]g-at l[sup [minus]1] to 1,640 [mu]g-at l[sup [minus]1]. On average, the natural creek had the lowest sulfide concentrations (mean < 1.0 [mu]g-at l[sup [minus]1]) and the perimeter ditch of a managed salt marsh impoundment the highest (436.5 [mu]g-at l[sup [minus]1]). There was a trend of increasing sulfide concentration in the summer, and sharp peaks in late fall-early winter which correspond with peak litter input into the sediments. Significant differences in sulfide concentration between sites are attributed to differences in <span class="hlt">water</span> flow and in organic matter content. Delaying the seasonal opening of culverts (which connect impounded marshes with the lagoon) until lagoon <span class="hlt">water</span> levels rise in fall may prevent massive fish kills that have been associated with high sulfide levels in the impoundment perimeter ditches. 35 refs., 7 figs., 5 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14641903','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14641903"><span>Distribution of arsenic and copper in sediment <span class="hlt">pore</span> <span class="hlt">water</span>: an ecological risk assessment case study for offshore drilling waste discharges.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sadiq, Rehan; Husain, Tahir; Veitch, Brian; Bose, Neil</p> <p>2003-12-01</p> <p>Due to the hydrophobic nature of synthetic based fluids (SBFs), drilling cuttings are not very dispersive in the <span class="hlt">water</span> column and settle down close to the disposal site. Arsenic and copper are two important toxic heavy metals, among others, found in the drilling waste. In this article, the concentrations of heavy metals are determined using a steady state "aquivalence-based" fate model in a probabilistic mode. Monte Carlo simulations are employed to determine <span class="hlt">pore</span> <span class="hlt">water</span> concentrations. A hypothetical case study is used to determine the <span class="hlt">water</span> quality impacts for two discharge options: 4% and 10% attached SBFs, which correspond to the best available technology option and the current discharge practice in the U.S. offshore. The exposure concentration (CE) is a predicted environmental concentration, which is adjusted for exposure probability and bioavailable fraction of heavy metals. The response of the ecosystem (RE) is defined by developing an empirical distribution function of predicted no-effect concentration. The pollutants' <span class="hlt">pore</span> <span class="hlt">water</span> concentrations within the radius of 750 m are estimated and cumulative distributions of risk quotient (RQ=CE/RE) are developed to determine the probability of RQ greater than 1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70033840','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70033840"><span><span class="hlt">Pore-water</span> chemistry from the ICDP-USGS core hole in the Chesapeake Bay impact structure-Implications for paleohydrology, microbial habitat, and <span class="hlt">water</span> resources</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sanford, W.E.; Voytek, M.A.; Powars, D.S.; Jones, B.F.; Cozzarelli, I.M.; Cockell, C.S.; Eganhouse, R.P.</p> <p>2009-01-01</p> <p>We investigated the groundwater system of the Chesapeake Bay impact structure by analyzing the <span class="hlt">pore-water</span> chemistry in cores taken from a 1766-m-deep drill hole 10 km north of Cape Charles, Virginia. <span class="hlt">Pore</span> <span class="hlt">water</span> was extracted using high-speed centrifuges from over 100 cores sampled from a 1300 m section of the drill hole. The <span class="hlt">pore-water</span> samples were analyzed for major cations and anions, stable isotopes of <span class="hlt">water</span> and sulfate, dissolved and total carbon, and bioavailable iron. The results reveal a broad transition between freshwater and saline <span class="hlt">water</span> from 100 to 500 m depth in the postimpact sediment section, and an underlying synimpact section that is almost entirely filled with brine. The presence of brine in the lowermost postimpact section and the trend in dissolved chloride with depth suggest a transport process dominated by molecular diffusion and slow, compaction-driven, upward flow. Major ion results indicate residual effects of diagenesis from heating, and a pre-impact origin for the brine. High levels of dissolved organic carbon (6-95 mg/L) and the distribution of electron acceptors indicate an environment that may be favorable for microbial activity throughout the drilled section. The concentration and extent of the brine is much greater than had previously been observed, suggesting that its occurrence may be common in the inner crater. However, groundwater-flow conditions in the structure may reduce the saltwater-intrusion hazard associated with the brine. ?? 2009 The Geological Society of America.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70031443','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70031443"><span>Composition of <span class="hlt">pore</span> <span class="hlt">water</span> in lake sediments, research site "B", Osage County, Oklahoma: Implications for lake <span class="hlt">water</span> quality and benthic organisms</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Zielinski, R.A.; Herkelrath, W.N.; Otton, J.K.</p> <p>2007-01-01</p> <p>Shallow ground <span class="hlt">water</span> at US Geological Survey research site B in northeastern Oklahoma is contaminated with NaCl-rich brine from past and present oil production operations. Contaminated ground <span class="hlt">water</span> provides a potential source of salts, metals, and hydrocarbons to sediment and <span class="hlt">water</span> of adjacent Skiatook Lake. A former brine storage pit 10 m in diameter that is now submerged just offshore from site B provides an additional source of contamination. Cores of the upper 16-40 cm of lake sediment were taken at the submerged brine pit, near an offshore saline seep, and at a location containing relatively uncontaminated lake sediment. <span class="hlt">Pore</span> <span class="hlt">waters</span> from each 2-cm interval were separated by centrifugation and analyzed for dissolved anions, cations, and trace elements. High concentrations of dissolved Cl- in <span class="hlt">pore</span> <span class="hlt">waters</span> (200-5000 mg/L) provide the most direct evidence of contamination, and contrast sharply with an average value of only about 37 mg/L in Skiatook Lake. Chloride/Br- mass ratios of 220-240 in contaminated <span class="hlt">pore</span> <span class="hlt">waters</span> are comparable to values in contaminated well <span class="hlt">waters</span> collected onshore. Dissolved concentrations of Se, Pb, Cu and Ni in Cl--rich <span class="hlt">pore</span> <span class="hlt">waters</span> exceed current US Environmental Protection Agency criteria for probable toxicity to aquatic life. At the submerged brine storage pit, the increase of Cl- concentration with depth is consistent with diffusion-dominant transport from deeper contaminated sediments. Near the offshore saline seep, <span class="hlt">pore</span> <span class="hlt">water</span> Cl- concentrations are consistently high and vary irregularly with depth, indicating probable Cl- transport by layer-directed advective flow. Estimated annual contributions of Cl- to the lake from the brine storage pit (???20 kg) and the offshore seep (???9 kg) can be applied to any number of similar sources. Generous estimates of the number of such sources at site B indicate minimal impact on <span class="hlt">water</span> quality in the local inlet of Skiatook Lake. Similar methodologies can be applied at other sites of Na</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18726245','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18726245"><span>Effect of sampling method on contaminant measurement in <span class="hlt">pore-water</span> and surface <span class="hlt">water</span> at two uranium operations: can method affect conclusions?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Robertson, Erin L; Liber, Karsten</p> <p>2009-08-01</p> <p>This paper describes a comparison of two methods of sediment <span class="hlt">pore-water</span> sampling and two methods of surface <span class="hlt">water</span> sampling that were used in a broader investigation of cause(s) of adverse effects on benthic invertebrate communities at two Saskatchewan uranium operations (Key Lake and Rabbit Lake). Variables measured and compared included pH, ammonia, DOC, and trace metals. The two types of sediment <span class="hlt">pore-water</span> samples that were compared are centrifuged and 0.45-microm filtered sediment core samples vs. 0.2-microm dialysis (peeper) samples. The two types of surface <span class="hlt">water</span> samples that were compared are 53-microm filtered Van Dorn horizontal beta samples vs. 0.2-microm dialysis (peeper) samples. Results showed that 62% of the sediment core <span class="hlt">pore</span> <span class="hlt">water</span> values were higher than the corresponding peeper <span class="hlt">pore-water</span> measurements, and that 63% of the Van Dorn surface <span class="hlt">water</span> measurements were lower than corresponding peeper surface <span class="hlt">water</span> measurements. Furthermore, only 24% and 14% of surface <span class="hlt">water</span> and <span class="hlt">pore-water</span> measurements, respectively, fell within +/-10% range of one another; 73% and 50%, respectively, fell within +/-50%. Although somewhat confounded by differences in filtering method, the observed differences are believed to primarily be related to small, vertical differences in the environment sampled. Despite observed differences in concentrations of toxicologically relevant variables generated by the different sampling methods, the weight of evidence (WOE) conclusions drawn from each set of exposure data on the possible cause(s) of in situ toxicity to Hyalella azteca from a related study were the same at each uranium operation. However, this concurrence was largely due to other dominant lines of evidence. The WOE conclusions at Key Lake were dominated by the toxicity response of H. azteca in relation to exposure chemistry, where as the WOE conclusions at Rabbit Lake were informed by exposure chemistry, the toxicological response of H. azteca, and whole-body contaminant</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70011999','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70011999"><span>Gas hydrates (clathrates) causing <span class="hlt">pore-water</span> freshening and oxygen isotope fractionation in deep-<span class="hlt">water</span> sedimentary sections of terrigenous continental margins</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hesse, R.; Harrison, W.E.</p> <p>1981-01-01</p> <p>The occurrence of gas hydrates in deep-<span class="hlt">water</span> sections of the continental margins predicted from anomalous acoustic reflectors on seismic profiles has been confirmed by recent deep-sea drilling results. On the Pacific continental slope off Guatemala gas hydrates were brought up for the first time from two holes (497, 498A) drilled during Leg 67 of the DSDP in <span class="hlt">water</span> depths of 2360 and 5500 m, respectively. The hydrates occur in organic matter-rich Pleistocene to Miocene terrigenous sediments. In the hydrate-bearing zone a marked decrease in interstitial <span class="hlt">water</span> chlorinities was observed starting at about 10-20 m subbottom depth. <span class="hlt">Pore</span> <span class="hlt">waters</span> at the bottom of the holes (near 400 m subbottom) have as little as half the chlorinity of seawater (i.e. 9???). Similar, but less pronounced, trends were observed during previous legs of the DSDP in other hydrate-prone segments of the continental margins where recharge of fresh <span class="hlt">water</span> from the continent can be excluded (e.g. Leg 11). The crystallization of hydrates, like ice, excludes salt ions from the crystal structure. During burial the dissolved salts are separated from the solids. Subsidence results in a downward motion of the solids (including hydrates) relative to the <span class="hlt">pore</span> fluids. Thawing of hydrates during recovery releases fresh <span class="hlt">water</span> which is remixed with the <span class="hlt">pore</span> fluid not involved in hydrate formation. The volume of the latter decreases downhole thus causing downward decreasing salinity (chlorinity). Hydrate formation is responsible for oxygen isotope fractionation with 18O-enrichment in the hydrate explaining increasingly more positive ??18O values in the <span class="hlt">pore</span> fluids recovered (after hydrate dissociation) with depth. ?? 1981.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28881239','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28881239"><span>Comparing in situ colorimetric DET and DGT techniques with ex situ core slicing and centrifugation for measuring ferrous iron and dissolved sulfide in coastal sediment <span class="hlt">pore</span> <span class="hlt">waters</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rathnayake Kankanamge, Nadeeka; Bennett, William W; Teasdale, Peter R; Huang, Jianyin; Welsh, David T</p> <p>2017-08-29</p> <p>In productive coastal sediments the separation between different biogeochemical zones (e.g. oxic, iron(III)-reducing and sulfate-reducing) may be on the scale of millimetres. Conventional measurement techniques simply cannot resolve changes in <span class="hlt">pore</span> <span class="hlt">water</span> solute concentrations over such small distances. The diffusive equilibration in thin films (DET) and the diffusive gradients in thin films (DGT) techniques allow in situ determination of <span class="hlt">pore</span> <span class="hlt">water</span> solute concentration profiles with one-dimensional profiles and/or two-dimensional distributions on the millimetre scale. Here we compare measurements of <span class="hlt">pore</span> <span class="hlt">water</span> iron(II) and sulfide using conventional core sampling (slicing and centrifugation) and colorimetric DET-DGT techniques. DET-DGT samplers were deployed within replicate sediment cores from three different sites, which were processed by slicing and centrifugation following retrieval of the samplers, so that the measurements were approximately co-located. Iron(II) concentrations were determined by DET at all three sites (0.3-262 μmol L(-1)), while dissolved sulfide was consistently measured by DGT at one site only (0.003-112 μmol L(-1)). <span class="hlt">Pore</span> <span class="hlt">water</span> concentrations of iron(II) and sulfide determined conventionally following <span class="hlt">pore</span> <span class="hlt">water</span> extraction (iron(II); 0.4-88 μmol L(-1) and sulfide; 0.05-36 μmol L(-1)), were systematically lower than the colorimetric DET and DGT measurements in the same sample. This underestimation was most likely due to the mixing of sediment from different biogeochemical zones during <span class="hlt">pore</span> <span class="hlt">water</span> extraction, which resulted in the precipitation of iron(II) and sulfide. This study shows that conventional <span class="hlt">pore</span> <span class="hlt">water</span> extraction methods can be unreliable for the determination of redox-active solutes due to artefacts associated with <span class="hlt">pore</span> <span class="hlt">water</span> mixing. Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/ED239839.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/ED239839.pdf"><span>Wet Worlds: Explore the World of <span class="hlt">Water</span>. <span class="hlt">Marine</span> and Fresh <span class="hlt">Water</span> Activities for the Elementary Classroom.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Solomon, Gerard; And Others</p> <p></p> <p>Complete with student worksheets, field trip ideas, illustrations, vocabulary lists, suggested materials, and step-by-step procedures, the document presents a compilation of ideas for teaching elementary school (K-6) students about <span class="hlt">marine</span> and fresh <span class="hlt">water</span>. In the first unit students build miniature monuments and observe the deterioration of…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23346958','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23346958"><span>Adsorption of carbon dioxide, methane, and their mixtures in porous carbons: effect of surface chemistry, <span class="hlt">water</span> content, and <span class="hlt">pore</span> disorder.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Billemont, Pierre; Coasne, Benoit; De Weireld, Guy</p> <p>2013-03-12</p> <p>The adsorption of carbon dioxide, methane, and their mixtures in nanoporous carbons in the presence of <span class="hlt">water</span> is studied using experiments and molecular simulations. Both the experimental and numerical samples contain polar groups that account for their partially hydrophilicity. For small amounts of adsorbed <span class="hlt">water</span>, although the shape of the adsorption isotherms remain similar, both the molecular simulations and experiments show a slight decrease in the CO2 and CH4 adsorption amounts. For large amounts of adsorbed <span class="hlt">water</span>, the experimental data suggest the formation of methane or carbon dioxide clathrates in agreement with previous work. In contrast, the molecular simulations do not account for the formation of such clathrates. Another important difference between the simulated and experimental data concerns the number of <span class="hlt">water</span> molecules that desorb upon increasing the pressure of carbon dioxide and methane. Although the experimental data indicate that <span class="hlt">water</span> remains adsorbed upon carbon dioxide and methane adsorption, the molecular simulations suggest that 40 to 75% of the initial amount of adsorbed <span class="hlt">water</span> desorbs with carbon dioxide or methane pressure. Such discrepancies show that differences between the simulated and experimental samples are crucial to account for the rich phase behavior of confined <span class="hlt">water</span>-gas systems. Our simulations for carbon dioxide-methane coadsorption in the presence of <span class="hlt">water</span> suggest that the <span class="hlt">pore</span> filling is not affected by the presence of <span class="hlt">water</span> and that adsorbed solution theory can be applied for pressures as high as 15 MPa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70035576','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70035576"><span>Polar organic compounds in <span class="hlt">pore</span> <span class="hlt">waters</span> of the Chesapeake Bay impact structure, Eyreville core hole: Character of the dissolved organic carbon and comparison with drilling fluids</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rostad, C.E.; Sanford, W.E.</p> <p>2009-01-01</p> <p><span class="hlt">Pore</span> <span class="hlt">waters</span> from the Chesapeake Bay impact structure cores recovered at Eyreville Farm, Northampton County, Virginia, were analyzed to characterize the dissolved organic carbon. After squeezing or centrifuging, a small volume of <span class="hlt">pore</span> <span class="hlt">water</span>, 100 ??L, was taken for analysis by electrospray ionization-mass spectrometry. Porewater samples were analyzed directly without filtration or fractionation, in positive and negative mode, for polar organic compounds. Spectra in both modes were dominated by low-molecular-weight ions. Negative mode had clusters of ions differing by -60 daltons, possibly due to increasing concentrations of inorganic salts. The numberaverage molecular weight and weight-average molecular weight values for the <span class="hlt">pore</span> <span class="hlt">waters</span> from the Chesapeake Bay impact structure are higher than those reported for other aquatic sources of natural dissolved organic carbon as determined by electrospray ionization-mass spectrometry. In order to address the question of whether drilling mud fluids may have contaminated the <span class="hlt">pore</span> <span class="hlt">waters</span> during sample collection, spectra from the <span class="hlt">pore</span> <span class="hlt">waters</span> were compared to spectra from drilling mud fluids. Ions indicative of drilling mud fluids were not found in spectra from the <span class="hlt">pore</span> <span class="hlt">waters</span>, indicating there was no detectable contamination, and highlighting the usefulness of this analytical technique for detecting potential contamination during sample collection. ?? 2009 The Geological Society of America.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1343742-linking-basin-scale-pore-scale-gas-hydrate-distribution-patterns-diffusion-dominated-marine-hydrate-systems-diffusion-driven-hydrate-growth-sands','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1343742-linking-basin-scale-pore-scale-gas-hydrate-distribution-patterns-diffusion-dominated-marine-hydrate-systems-diffusion-driven-hydrate-growth-sands"><span>Linking basin-scale and <span class="hlt">pore</span>-scale gas hydrate distribution patterns in diffusion-dominated <span class="hlt">marine</span> hydrate systems: DIFFUSION-DRIVEN HYDRATE GROWTH IN SANDS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Nole, Michael; Daigle, Hugh; Cook, Ann E.; ...</p> <p>2017-02-01</p> <p>The goal of this study is to computationally determine the potential distribution patterns of diffusion-driven methane hydrate accumulations in coarse-grained <span class="hlt">marine</span> sediments. Diffusion of dissolved methane in <span class="hlt">marine</span> gas hydrate systems has been proposed as a potential transport mechanism through which large concentrations of hydrate can preferentially accumulate in coarse-grained sediments over geologic time. Using one-dimensional compositional reservoir simulations, we examine hydrate distribution patterns at the scale of individual sand layers (1 to 20 m thick) that are deposited between microbially active fine-grained material buried through the gas hydrate stability zone (GHSZ). We then extrapolate to two- dimensional and basin-scalemore » three-dimensional simulations, where we model dipping sands and multilayered systems. We find that properties of a sand layer including <span class="hlt">pore</span> size distribution, layer thickness, dip, and proximity to other layers in multilayered systems all exert control on diffusive methane fluxes toward and within a sand, which in turn impact the distribution of hydrate throughout a sand unit. In all of these simulations, we incorporate data on physical properties and sand layer geometries from the Terrebonne Basin gas hydrate system in the Gulf of Mexico. We demonstrate that diffusion can generate high hydrate saturations (upward of 90%) at the edges of thin sands at shallow depths within the GHSZ, but that it is ineffective at producing high hydrate saturations throughout thick (greater than 10 m) sands buried deep within the GHSZ. As a result, we find that hydrate in fine-grained material can preserve high hydrate saturations in nearby thin sands with burial.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B13A0154K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B13A0154K"><span>Radiocarbon Evidence for Active Turnover of <span class="hlt">Pore-Water</span> Dissolved Organic Carbon in the Methanogenic and Sulfate-Methane-Transition Zones of Santa Barbara Basin Sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Komada, T.; Li, H. L.; Cada, A. K.; Burdige, D.; Magen, C.; Chanton, J.; Grose, A. M.</p> <p>2014-12-01</p> <p>Diverse metabolic activities have been documented in the deep biosphere. However, how these activities affect carbon cycling in the subsurface, and how they in turn affect the <span class="hlt">marine</span> and global cycles of carbon are still unclear. Here we present natural-abundance 14C and 13C data from the uppermost 4.5 m of the sediments of the Santa Barbara Basin, California Borderland, showing active turnover of dissolved organic carbon (DOC) within, and immediately below, the sulfate-methane transition zone (SMTZ; ~1.25 m). DOC concentrations increased with depth throughout the core, indicating net production within the sediment column. Enhanced DOC production was observed near the sediment-<span class="hlt">water</span> interface, and also at ~30 cm below the SMTZ (~1.55 m). ∆14C values of DOC increased across the sediment-<span class="hlt">water</span> interface, then decreased with depth, consistent with net production of modern DOC near the sediment-<span class="hlt">water</span> interface, and input of 14C-depleted DOC from deeper horizons. An isotope mixing plot constructed with these data shows that the DOC diffusing upward at the base of the core is devoid of 14C, yet the DOC diffusing into and out of the SMTZ is relatively enriched (-460‰ and -300‰, respectively). This difference in 14C content of the DOC flux can only be reconciled if the following two are occurring within, and immediately below, the SMTZ: (1) >90% of the 14C-dead basal DOC flux is removed from the <span class="hlt">pore</span> <span class="hlt">water</span> (by, e.g., oxidation, fermentation, methanogenesis, precipitation), and (2) this DOC is replaced by material produced in this region at a rate that exceeds the upward basal flux. The 14C and 13C signatures suggest sedimentary organic matter to be the dominant source of DOC in process (2). Our data provide a unique insight into the active transformation of DOC and sedimentary organic matter in the subsurface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19908907','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19908907"><span>Measuring low picogram per liter concentrations of freely dissolved polychlorinated biphenyls in sediment <span class="hlt">pore</span> <span class="hlt">water</span> using passive sampling with polyoxymethylene.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hawthorne, Steven B; Miller, David J; Grabanski, Carol B</p> <p>2009-11-15</p> <p>Studies into bioaccumulation of polychlorinated biphenyls (PCBs) have increasingly focused on congeners that are freely dissolved in sediment interstitial <span class="hlt">pore</span> <span class="hlt">water</span>. Because of their low <span class="hlt">water</span> solubilities and their tendency to persist and concentrate as they progress in the food chain, interest has grown in methods capable of measuring individual PCB congeners at low part-per-quadrillion (picogram per liter) concentrations. Obtaining large volumes of <span class="hlt">pore</span> <span class="hlt">water</span> is difficult (or impossible), which makes conventional analytical approaches incapable of attaining suitable detection limits. In the present study, nondepletive sampling is used to achieve very low detection limits of freely dissolved PCBs, while requiring no separation of the sediment and <span class="hlt">water</span> slurry. Commercially available 76 microm thick polyoxymethylene (POM) coupons were placed directly into wet sediments and left to reach equilibrium with the <span class="hlt">pore</span> <span class="hlt">water</span> and sediment PCBs for up to 84 days, with 28 days found to be sufficient. Freely dissolved concentrations were then calculated by dividing the PCB concentration found in the POM by its POM/<span class="hlt">water</span> partitioning coefficient (K(POM)). The K(POM) values required for determining <span class="hlt">water</span> concentrations were measured using two spiked sediments and two historically contaminated sediments for all 62 PCB congeners that are present at greater than trace concentrations in commercial Aroclors. Log K(POM) values ranged from ca. 4.6 for dichloro-congeners to ca. 7.0 for octachloro-congeners and correlate well with octanol/<span class="hlt">water</span> coefficients (K(OW)) (r(2) = 0.947) so that a simple linear equation can be used to calculate dissolved concentrations within a factor of 2 or better for congeners having no measured K(POM) value. Detection limits for freely dissolved PCBs ranged from ca. 20 pg/L (part-per-quadrillion) for dichloro-congeners down to ca. 0.2 pg/L for higher-molecular-weight congeners. Sorption isotherms were found to be linear (r(2) > 0.995) over at least 3</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21595462','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21595462"><span>Predicting <span class="hlt">pore</span> <span class="hlt">water</span> EPA-34 PAH concentrations and toxicity in pyrogenic-impacted sediments using pyrene content.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Arp, Hans Peter H; Azzolina, Nicholas A; Cornelissen, Gerard; Hawthorne, Steven B</p> <p>2011-06-15</p> <p>Sediment and freely dissolved <span class="hlt">pore</span> <span class="hlt">water</span> concentrations of the U.S. Environmental Protection Agency's list of 34 alkyl and parent PAHs (EPA-34) were measured in 335 sediment samples from 19 different sites impacted by manufactured gas plants, aluminum smelters and other pyrogenic sources. The total EPA-34 freely dissolved <span class="hlt">pore</span> <span class="hlt">water</span> concentration, C(pw,EPA-34), expressed as toxic units (TU) is currently considered one of the most accurate measures to assess risk at such sites; however, it is very seldom measured. With this data set, we address how accurately C(pw,EPA-34) can be estimated using limited 16 parent PAH data (EPA-16) commonly available for such sites. An exhaustive statistical analysis of the obtained data validated earlier observations that PAHs with more than 3 rings are present in similar relative abundances and their partitioning behavior typically follows Raoult's law and models developed for coal tar. As a result, sediment and freely dissolved <span class="hlt">pore</span> <span class="hlt">water</span> concentrations of pyrene and other 3- and 4-ring PAHs exhibit good log-log correlations (r² > 0.8) to most individual EPA-34 PAHs and also to C(pw,EPA-34). Correlations improve further by including the ratio of high to low molecular weight PAHs, as 2-ring PAHs exhibit the most variability in terms of their relative abundance. The most practical result of the current work is that log C(pw,EPA-34) estimated by the recommended pyrene-based estimation techniques was similarly well correlated to % survival of the benthic amphipods Hyalella azteca and Leptocheirus plumulosus as directly measured log C(pw,EPA-34) values (n = 211). Incorporation of the presented C(pw,EPA-34) estimation techniques could substantially improve risk assessments and guidelines for sediments impacted by pyrogenic residues, especially when limited data are available, without requiring any extra data or measurement costs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21326079','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21326079"><span>Experimental Study on the pH of <span class="hlt">Pore</span> <span class="hlt">water</span> in Compacted Bentonite under Reducing Conditions with Electromigration</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nessa, S.A.; Idemitsu, K.; Yamazaki, S.; Ikeuchi, H.; Inagaki, Y.; Arima, T.</p> <p>2008-07-01</p> <p>Compacted bentonite and carbon steel are considered a good buffer and over-pack materials in the repositories of high-level radioactive waste disposal. Sodium bentonite, Kunipia-F contains approximately 95 wt% of montmorillonite. Bentonites prominent properties of high swelling, sealing ability and cation exchange capacity provide retardation against the transport of radionuclides from the waste into the surrounding rocks in the repository and its properties determine the behavior of bentonite. In this regards, the pH of <span class="hlt">pore</span> <span class="hlt">water</span> in compacted bentonite is measured with pH test paper wrapped with semi-permeable membrane of collodion sheet under reducing conditions. On 30 days, the pH test paper in the experimental apparatus indicated that the pH of <span class="hlt">pore</span> <span class="hlt">water</span> in compacted bentonite is around 8.0 at saturated state. The carbon steel coupon is connected as the working electrode to the potentiostat and is held at a constant supplied potential between +300 and -300 mV vs. Ag/AgCl electrode for up to 7 days. During applying electromigration the pH of <span class="hlt">pore</span> <span class="hlt">water</span> in bentonite decreased and it reached 6.0{approx}6.0 on 7 days. The concentration of iron and sodium showed nearly complementary distribution in the bentonite specimen after electromigration. It is expected that iron could migrate as ferrous ion through the interlayer of montmorillonite replacing exchangeable sodium ions in the interlayer. Semi-permeable membrane of collodion sheet does not affect the color change of pH test paper during the experiment. (authors)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvE..92e2719R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvE..92e2719R"><span>Protein-fluctuation-induced <span class="hlt">water-pore</span> formation in ion channel voltage-sensor translocation across a lipid bilayer membrane</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rajapaksha, Suneth P.; Pal, Nibedita; Zheng, Desheng; Lu, H. Peter</p> <p>2015-11-01</p> <p>We have applied a combined fluorescence microscopy and single-ion-channel electric current recording approach, correlating with molecular dynamics (MD) simulations, to study the mechanism of voltage-sensor domain translocation across a lipid bilayer. We use the colicin Ia ion channel as a model system, and our experimental and simulation results show the following: (1) The open-close activity of an activated colicin Ia is not necessarily sensitive to the amplitude of the applied cross-membrane voltage when the cross-membrane voltage is around the resting potential of excitable membranes; and (2) there is a significant probability that the activation of colicin Ia occurs by forming a transient and fluctuating <span class="hlt">water</span> <span class="hlt">pore</span> of ˜15 Å diameter in the lipid bilayer membrane. The location of the <span class="hlt">water-pore</span> formation is nonrandom and highly specific, right at the insertion site of colicin Ia charged residues in the lipid bilayer membrane, and the formation is intrinsically associated with the polypeptide conformational fluctuations and solvation dynamics. Our results suggest an interesting mechanistic pathway for voltage-sensitive ion channel activation, and specifically for translocation of charged polypeptide chains across the lipid membrane under a transmembrane electric field: the charged polypeptide domain facilitates the formation of hydrophilic <span class="hlt">water</span> <span class="hlt">pore</span> in the membrane and diffuses through the hydrophilic pathway across the membrane; i.e., the charged polypeptide chain can cross a lipid membrane without entering into the hydrophobic core of the lipid membrane but entirely through the aqueous and hydrophilic environment to achieve a cross-membrane translocation. This mechanism sheds light on the intensive and fundamental debate on how a hydrophilic and charged peptide domain diffuses across the biologically inaccessible high-energy barrier of the hydrophobic core of a lipid bilayer: The peptide domain does not need to cross the hydrophobic core to move across a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3796548','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3796548"><span>Revealing Sources and Distribution Changes of Dissolved Organic Matter (DOM) in <span class="hlt">Pore</span> <span class="hlt">Water</span> of Sediment from the Yangtze Estuary</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Ying; Zhang, Di; Shen, Zhenyao; Feng, Chenghong; Chen, Jing</p> <p>2013-01-01</p> <p>Dissolved organic matter (DOM) in sediment <span class="hlt">pore</span> <span class="hlt">waters</span> from Yangtze estuary of China based on abundance, UV absorbance, molecular weight distribution and fluorescence were investigated using a combination of various parameters of DOM as well as 3D fluorescence excitation emission matrix spectra (F-EEMS) with the parallel factor and principal component analysis (PARAFAC-PCA). The results indicated that DOM in <span class="hlt">pore</span> <span class="hlt">water</span> of Yangtze estuary was very variable which mainly composed of low aromaticity and molecular weight materials. Three humic-like substances (C1, C2, C4) and one protein-like substance (C3) were identified by PARAFAC model. C1, C2 and C4 exhibited same trends and were very similar. The separation of samples on both axes of the PCA showed the difference in DOM properties. C1, C2 and C4 concurrently showed higher positive factor 1 loadings, while C3 showed highly positive factor 2 loadings. The PCA analysis showed a combination contribution of microbial DOM signal and terrestrial DOM signal in the Yangtze estuary. Higher and more variable DOM abundance, aromaticity and molecular weight of surface sediment <span class="hlt">pore</span> <span class="hlt">water</span> DOM can be found in the southern nearshore than the other regions primarily due to the influence of frequent and intensive human activities and tributaries inflow in this area. The DOM abundance, aromaticity, molecular weight and fluorescence intensity in core of different depth were relative constant and increased gradually with depth. DOM in core was mainly composed of humic-like material, which was due to higher release of the sedimentary organic material into the porewater during early diagenesis. PMID:24155904</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/1002893','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/1002893"><span>Temporal and vertical distribution of total ammonia nitrogen and un-ionized ammonia nitrogen in sediment <span class="hlt">pore</span> <span class="hlt">water</span> from the upper Mississippi River</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Frazier, Bradley E.; Naimo, Teresa J.; Sandheinrich, Mark B.</p> <p>1996-01-01</p> <p>We examined the temporal and vertical distribution of total ammonia nitrogen (TAN) and un-ionized ammonia nitrogen (NH3-N) in sediment <span class="hlt">pore</span> <span class="hlt">water</span> and compared the temporal patterns of TAN and NH3-N concentrations in overlying surface <span class="hlt">water</span> with those in <span class="hlt">pore</span> <span class="hlt">water</span>. <span class="hlt">Pore</span> <span class="hlt">water</span> was obtained by core extraction and subsequent centrifugation. We measured TAN concentrations and calculated NH3-N concentrations from February through October 1993 at four sites in Pool 8, upper Mississippi River, at depths of 0 to 4, 4 to 8, and 8 to 12 cm below the sediment-<span class="hlt">water</span> interface. Total ammonia nitrogen and NH3-N concentrations were significantly different among sampling dates (p = 0.0001) and sediment depths (p = 0.0001). Concentrations of TAN and NH3-N in surface <span class="hlt">water</span> were significantly less than those in <span class="hlt">pore</span> <span class="hlt">water</span> from all sediment depths (p < 0.05). Concentrations in <span class="hlt">pore</span> <span class="hlt">water</span> ranged from 0.07 to 4.0 mg TAN/L and less than 1 to 20 I?g NH3-N/L in winter, and from 0.07 to 10.0 mg TAN/L and 1 to 175 I?g NH3-N/L in summer; greatest concentrations were usually found in sediments 8 to 12 cm deep. Annual mean TAN concentrations were positively correlated with silt and volatile solids content and were negatively correlated with sand content. Because of the high variability of TAN and NH3-N concentrations in <span class="hlt">pore</span> <span class="hlt">water</span>, sediment toxicity studies should take into account the season and the depth at which sediments are obtained. The annual mean NH3-N concentration in <span class="hlt">pore</span> <span class="hlt">water</span> at one site (55 I?g/L) exceeded the concentration (30 I?g/L) demonstrated to inhibit growth of fingernail clams in laboratory studies. However, these concentrations apparently were not lethal, as evidenced by the presence of fingernail clams at this site.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4478152','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4478152"><span>Bi-Component T2* Analysis of Bound and <span class="hlt">Pore</span> Bone <span class="hlt">Water</span> Fractions Fails at High Field Strengths</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Seifert, Alan C.; Wehrli, Suzanne L.; Wehrli, Felix W.</p> <p>2015-01-01</p> <p>Osteoporosis involves degradation of bone’s trabecular architecture, cortical thinning, and enlargement of cortical <span class="hlt">pores</span>. Increased cortical porosity is a major cause of the decreased strength of osteoporotic bone. The majority of cortical <span class="hlt">pores</span>, however, are below the resolution limit of MRI. Recent work has shown that porosity can be evaluated by MRI-based quantification of bone <span class="hlt">water</span>. Bi-exponential T2* fitting and adiabatic inversion preparation are the two most common methods purported to distinguish bound and <span class="hlt">pore</span> <span class="hlt">water</span> in order to quantify matrix density and porosity. To assess the viability of T2* bi-component analysis as a method for quantifying bound and <span class="hlt">pore</span> <span class="hlt">water</span> fractions, we have applied this method to human cortical bone at 1.5T, 3T, 7T, and 9.4T, and validated the resulting pool fractions against μCT-derived porosity and gravimetrically-determined bone densities. We also investigated alternative methods: 2D T1–T2* bi-component fitting by incorporating saturation-recovery, 1D and 2D fitting of CPMG echo amplitudes, and deuterium inversion recovery. Short-T2* pool fraction was moderately correlated with porosity (R2 = 0.70) and matrix density (R2 = 0.63) at 1.5T, but the strengths of these associations were found to diminish rapidly as field strength increases, falling below R2 = 0.5 at 3T. Addition of the T1 dimension to bi-component analysis only slightly improved the strengths of these correlations. T2*-based bi-component analysis should therefore be used with caution. Performance of deuterium inversion-recovery at 9.4T was also poor (R2 = 0.50 versus porosity and R2 = 0.46 versus matrix density). CPMG-derived short-T2 fraction at 9.4T, however, is highly correlated with porosity (R2 = 0.87) and matrix density (R2 = 0.88), confirming the utility of this method for independent validation of bone <span class="hlt">water</span> pools. PMID:25981785</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6218741','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6218741"><span><span class="hlt">Pore</span> <span class="hlt">water</span> chemistry of the mounds hydrothermal field, Galapagos Spreading Center: Results from Glomar Challenger piston coring</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bender, M.L.</p> <p>1983-02-10</p> <p>On DSDP Leg 70, Glomar Challenger piston cored hydrothermal MnO/sub 2/-encrusted nontronite mounds and adjacent pelagic sediments through to basement. <span class="hlt">Pore</span> <span class="hlt">waters</span> were collected by centrifuging, squeezing, and in situ sampling: analyses are presented here for Ca, Mg, Si, NH/sub 3/, Mn, and Fe. Our results confirm Maris and Bender's (1982) conclusions that hydrothermal solutions enriched in Ca by 1-2 mM and depleted in Mg by approx.2 mM are upwelling through the mounds and the surrounding pelagic sediments. Si, NH/sub 3/, and Mn/sup 2 +/ concentrations generally increase upcore, reflecting addition of products of metabolic reactions to upwelling hydrothermal solutions. <span class="hlt">Pore</span> <span class="hlt">water</span> iron concentrations decrease upcore, probably as a result of oxidation and precipitation of upwelling hydrothermal iron. The formation of nontronite (Fe(III)/sub 4/Si/sub 8/O/sub 20/(OH)/sub 4/) involves oxidation of dissolved Fe/sup 2 +/. Several models, constrained by the electron balance, are proposed to explain the process of nontronite formation. The stratigraphy of the mounds (thick nontronite covered by a thin MnO/sub 2/ crust) may be explained by postulating Fe/sup 2 +/ oxidation by MnO/sub 2/ and replacement of MnO/sub 2/ by nontronite at the base of the MnO/sub 2/ crust, followed by upward migration of Mn/sup 2 +/ and precipitation of MnO/sub 2/ at the sediment <span class="hlt">water</span> interface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JAESc.143....1N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JAESc.143....1N"><span>A study of clay <span class="hlt">pore</span> <span class="hlt">water</span> and sporopollens for characterizing paleoenvironments in the Hebei Plain, Northern China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Niu, Hong; Liang, Xing; Lu, Guoping; Peng, Fei; Jin, Menggui; Gu, Yansheng</p> <p>2017-08-01</p> <p>We developed a clay <span class="hlt">pore</span> <span class="hlt">water</span> (CPW) isotopic method for tracing paleoenvironments characterized by sporopollens. The thick clayey layers have the advantage of preserving <span class="hlt">pore</span> <span class="hlt">water</span> regardless of whether the <span class="hlt">water</span> is inherent in the clayey layers or not. Therefore, the clayey layers are a suitable target from which paleoenvironmental information can be extracted. Sediment sporopollens as well as CPW deuterium and oxygen isotopes were investigated in drilling cores obtained from a 130-m borehole at a field site in Hengshui in the North China Plain. Our interpretation of δ18O in CPW was consistent with sporopollens climate indices, indicating that CPW was an effective proxy for obtaining paleoenvironmental information. Sporopollens species were abundant in the cores, but the quantity of each species was low. Furthermore, mean annual temperature and precipitation curves were established using a pollen-climatic response surface model. The results indicated two warm-humid periods (5.2-0 m, 22.6-11 m) and one cold-dry period (8.8-6.4 m) in the Holocene as well as two warm-humid periods (90.6-83 m, 110.6-108.2 m) and three cold-dry periods (approximately 40 m, 66.4-56.8 m, approximately 100 m) in the Late Pleistocene. Data derived from the sporopollens and CPW cumulatively elucidate the environmental change in Northern China.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1983JGR....88.1049B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1983JGR....88.1049B"><span><span class="hlt">Pore</span> <span class="hlt">water</span> chemistry of the Mounds Hydrothermal Field, Galapagos Spreading Center: Results from Glomar Challenger Piston Coring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bender, Michael L.</p> <p>1983-01-01</p> <p>On DSDP Leg 70, Glomar Challenger piston cored hydrothermal MnO2-encrusted nontronite mounds and adjacent pelagic sediments through to basement. <span class="hlt">Pore</span> <span class="hlt">waters</span> were collected by centrifuging, squeezing, and in situ sampling; analyses are presented here for Ca, Mg, Si, NH3, Mn, and Fe. Our results confirm Maris and Bender's (1982) conclusions that hydrothermal solutions enriched in Ca by 1-2 mM and depleted in Mg by ˜2 mM are upwelling through the mounds and the surrounding pelagic sediments. Si, NH3, and Mn2+ concentrations generally increase upcore, reflecting addition of products of metabolic reactions to upwelling hydrothermal solutions. <span class="hlt">Pore</span> <span class="hlt">water</span> iron concentrations decrease upcore, probably as a result of oxidation and precipitation of upwelling hydrothermal iron. The formation of nontronite (Fe(III)4Si8O20(OH)4) involves oxidation of dissolved Fe2+. Several models, constrained by the electron balance, are proposed to explain the process of nontronite formation. The stratigraphy of the mounds (thick nontronite covered by a thin MnO2 crust) may be explained by postulating Fe2+ oxidation by MnO2 and replacement of MnO2 by nontronite at the base of the MnO2 crust, followed by upward migration of Mn2+ and precipitation of MnO2 at the sediment <span class="hlt">water</span> interface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1997/0245/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1997/0245/report.pdf"><span>Chemical data for bottom sediment, lake <span class="hlt">water</span>, bottom-sediment <span class="hlt">pore</span> <span class="hlt">water</span>, and fish in Mountain Creek Lake, Dallas, Texas, 1994-96</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Jones, S.A.; Van Metre, P.C.; Moring, J.B.; Braun, C.L.; Wilson, J.T.; Mahler, B.J.</p> <p>1997-01-01</p> <p>Mountain Creek Lake is a reservoir adjacent to two U.S. Department of the Navy facilities, the Naval Weapons Industrial Reserve Plant and the Naval Air Station in Dallas, Texas. A Resource Conservation and Recovery Act Facility Investigation found ground-<span class="hlt">water</span> plumes containing chlorinated solvents on both facilities. These findings led to a U.S. Geological Survey study of Mountain Creek Lake adjacent to both facilities between June 1994 and August 1996. Bottom sediments, lake <span class="hlt">water</span>, bottom-sediment <span class="hlt">pore</span> <span class="hlt">water</span>, and fish were collected for chemical analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPS...331..462A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPS...331..462A"><span>Validation of <span class="hlt">pore</span> network simulations of ex-situ <span class="hlt">water</span> distributions in a gas diffusion layer of proton exchange membrane fuel cells with X-ray tomographic images</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Agaesse, Tristan; Lamibrac, Adrien; Büchi, Felix N.; Pauchet, Joel; Prat, Marc</p> <p>2016-11-01</p> <p>Understanding and modeling two-phase flows in the gas diffusion layer (GDL) of proton exchange membrane fuel cells are important in order to improve fuel cells performance. They are scientifically challenging because of the peculiarities of GDLs microstructures. In the present work, simulations on a <span class="hlt">pore</span> network model are compared to X-ray tomographic images of <span class="hlt">water</span> distributions during an ex-situ <span class="hlt">water</span> invasion experiment. A method based on watershed segmentation was developed to extract a <span class="hlt">pore</span> network from the 3D segmented image of the dry GDL. <span class="hlt">Pore</span> network modeling and a full morphology model were then used to perform two-phase simulations and compared to the experimental data. The results show good agreement between experimental and simulated microscopic <span class="hlt">water</span> distributions. <span class="hlt">Pore</span> network extraction parameters were also benchmarked using the experimental data and results from full morphology simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS33A2003P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS33A2003P"><span>In situ Determination of <span class="hlt">Pore-water</span> pH in Reducing Sediments near Methane Seeps and Vents by Laser Raman Spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peltzer, E. T.; Walz, P. M.; Luna, M.; Zhang, X.; Brewer, P. G.</p> <p>2015-12-01</p> <p>Sediments near methane vents and seeps are often anoxic in nature due to the microbial oxidation of organic matter. When the <span class="hlt">pore-water</span> oxygen is consumed, the microbial population resorts to using sulfate as the terminal electron receptor. For the anaerobic oxidation of methane, the net reaction is: CH4 + SO42- = HCO3- + HS- + H2O. Hydrogen sulfide produced by this reaction dissociates into bisulfide in proportion to the <span class="hlt">pore-water</span> pH. Since the first pK of H2S is about 7 and close to the in situ <span class="hlt">pore-water</span> pH, it satisfies the criteria for a useful pH indicating dye. Although the two forms of hydrogen sulfide are not visually discernable by the human eye, these two forms have distinct Raman spectra and thus can be easily quantified using an in situ spectrometer. The relative Raman cross-sections of the hydrogen sulfide species were determined in the laboratory across a range of relevant pH values and at the approximate salinity (ionic strength) and temperature of deep-sea <span class="hlt">pore</span> <span class="hlt">waters</span>. With this calibration, it is simple to compute the <span class="hlt">pore-water</span> pH from the relative abundance of the two sulfide species: pH = pK1 + log10([HS-]/[H2S]). <span class="hlt">Pore-water</span> profiles were investigated at several sites in the Santa Monica basin around methane mounds, gas vents and cold seeps. A titanium <span class="hlt">pore-water</span> probe with a stainless steel frit was used to filter and collect <span class="hlt">pore-water</span> samples at 5-10 cm intervals in the top 50-60 cm of sediment. Filtration and collection of the <span class="hlt">pore-water</span> samples was usually accomplished in 5-10 minutes, with acquisition of the laser Raman spectra requiring only 2-4 minutes additional time. Vertical profiles of sulfate, total sulfide (H2S + HS-), methane and pH were collected simultaneously using the laser Raman spectrometer and <span class="hlt">pore-water</span> profile sampler. Sulfate was observed to decrease from seawater concentrations to below detection limits while both methane and total sulfide increased proportionally to the sulfate loss. Once total sulfide concentrations</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4169402','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4169402"><span>Importance of Boreal Rivers in Providing Iron to <span class="hlt">Marine</span> <span class="hlt">Waters</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kritzberg, Emma S.; Bedmar Villanueva, Ana; Jung, Marco; Reader, Heather E.</p> <p>2014-01-01</p> <p>This study reports increasing iron concentrations in rivers draining into the Baltic Sea. Given the decisive role of iron to the structure and biogeochemical function of aquatic ecosystems, this trend is likely one with far reaching consequences to the receiving system. What those consequences may be depends on the fate of the iron in estuarine mixing. We here assess the stability of riverine iron by mixing <span class="hlt">water</span> from seven boreal rivers with artificial sea salts. The results show a gradual loss of iron from suspension with increasing salinity. However, the capacity of the different river <span class="hlt">waters</span> to maintain iron in suspension varied greatly, i.e. between 1 and 54% of iron was in suspension at a salinity of 30. The variability was best explained by iron:organic carbon ratios in the riverine <span class="hlt">waters</span> – the lower the ratio the more iron remained in suspension. <span class="hlt">Water</span> with an initially low iron:organic carbon ratio could keep even higher than ambient concentrations of Fe in suspension across the salinity gradient, as shown in experiments with iron amendments. Moreover, there was a positive relationship between the molecular size of the riverine organic matter and the amount of iron in suspension. In all, the results point towards a remarkably high transport capacity of iron from boreal rivers, suggesting that increasing concentrations of iron in river mouths may result in higher concentrations of potentially bioavailable iron in the <span class="hlt">marine</span> system. PMID:25233197</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=203992','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=203992"><span>Survival of Candida albicans in tropical <span class="hlt">marine</span> and fresh <span class="hlt">waters</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Valdes-Collazo, L; Schultz, A J; Hazen, T C</p> <p>1987-01-01</p> <p>A survey of Candida albicans indicated that the organism was present at all sites sampled in a rain forest stream and in near-shore coastal <span class="hlt">waters</span> of Puerto Rico. In the rain forest watershed no relationship existed between densities of fecal coliforms and densities of C. albicans. At two pristine sites in the rain forest watershed both C. albicans and Escherichia coli survived in diffusion chambers for extended periods of time. In near-shore coastal <span class="hlt">waters</span> C. albicans and E. coli survival times in diffusion chambers were enhanced by effluent from a rum distillery. The rum distillery effluent had a greater effect on E. coli than on C. albicans survival in the diffusion chambers. These studies show that neither E. coli nor C. albicans organisms are good indicators of recent fecal contamination in tropical <span class="hlt">waters</span>. It further demonstrates that pristine freshwater environments and <span class="hlt">marine</span> <span class="hlt">waters</span> receiving organic loading in the tropics can support densities of C. albicans which may be a health hazard. Images PMID:3310885</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28799749','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28799749"><span>Closed <span class="hlt">Pore</span> Structured NiCo2O4-Coated Nickel Foams for Stable and Effective Oil/<span class="hlt">Water</span> Separation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Yan; Zheng, Xi; Yan, Zhanheng; Tian, Dongliang; Ma, Jianmin; Zhang, Xiaofang; Jiang, Lei</p> <p>2017-08-30</p> <p>To solve the serious problem caused by oily wastewater pollution, unique interface designs, for example, membranes with superwetting properties such as superhydrophobicity/superoleophilicity and sup