Silicon control of strontium and cesium partitioning in hydroxide-weathered sediments     

Jon Chorover  Sunkyung Choi  R. Jeff Serne  Caleb Strepka  Karl T. Mueller 《Geochimica et cosmochimica acta》2008,72(8):2024-2047

Cation partitioning and speciation in an aqueous soil suspension may depend on the coupling of reaction time, sorbate amount and mineral weathering reactions. These factors were varied in sediment suspension experiments to identify geochemical processes that affect migration of Sr²⁺ and Cs⁺ introduced to the subsurface by caustic high level radioactive waste (HLRW). Three glacio-fluvial and lacustrine sediments from the Hanford Site (WA, USA) were subjected to hyperalkaline (pH > 13), Na-Al-NO₃-OH solution conditions within a gradient field of (i) sorptive concentration (10⁻⁵-10⁻³ m) and (ii) reaction time (0-365 d). Strontium uptake (q_Sr) exceeded that of cesium at nearly all reaction times. Sorbent affinity for both Cs⁺ and Sr²⁺ increased with clay plus silt content at early times, but a prolonged slow uptake process was observed over the course of sediment weathering that erased the texture effect for Sr²⁺; all sediments showed similar mass normalized uptake after several months of reaction time. Strontium became progressively recalcitrant to desorption after 92 d, with accumulation and aging of neoformed aluminosilicates. Formation of Cs⁺ and Sr²⁺-containing cancrinite and sodalite was observed after 183 d by SEM and synchrotron μ-XRF and μ-XRD. EXAFS data for q_Sr ≈ 40 mmol kg⁻¹ showed incorporation of Sr²⁺ into both feldspathoid and SrCO₃(s) coordination environments after one year. Adsorption was predominant at early times and low sorbate amount, whereas precipitation, controlled largely by sediment Si release, became increasingly important at longer times and higher sorbate amount. Kinetics of contaminant desorption at pH 8 from one year-weathered sediments showed significant dependence on background cation (Ca²⁺ versus K⁺) composition. Results of this study indicate that co-precipitation and ion exchange in neoformed aluminosilicates may be an important mechanism controlling Sr²⁺ and Cs⁺ mobility in siliceous sediments impacted by hyperalkaline HLRW.  相似文献   

Direct Trace Element Determination in Oil and Gas Produced Waters with Inductively Coupled Plasma‐Optical Emission Spectrometry: Advantages of High‐Salinity Tolerance     

Aaron M. Jubb  Mark A. Engle  Jessica M. Chenault  Madalyn S. Blondes  Cloelle G. Danforth  Colin Doolan  Tanya J. Gallegos  Dan Mueller  Jenna L. Shelton 《Geostandards and Geoanalytical Research》2020,44(2):385-397

Waters co‐produced during petroleum extraction are the largest waste streams from oil and gas development. Reuse or disposal of these waters is difficult due to their high salinities and the sheer volumes generated. Produced waters (PWs) may also contain valuable mineral commodities. While an understanding of produced water trace element composition is required for evaluating the associated resource and waste potential of these materials, measuring trace elements in brines is challenging due to the dilution requirements of typical methods. Alternatively, inductively coupled plasma‐optical emission spectrometry (ICP‐OES) has shown promise as being capable of direct measurements of trace elements within PWs with minimal dilution. Here, we evaluate direct ICP‐OES trace element quantification in PWs for seventeen trace elements (As, Al, Ba, Be, Cd, Cr, Co, Cu, Hg, Mo, Ni, Pb, Rb, Sb, U, V and Zn) within fifteen PWs from five U.S. continuous reservoirs. The total analytical uncertainties associated with the trace element levels determined using ICP‐OES were estimated to be better than ± 30% (2s) except for Rb, which could not be determined due to ionisation interferences. The ICP‐OES results are compared with trace element levels determined using inductively coupled plasma‐mass spectrometry from the same samples. Our results demonstrate the potential for direct analysis of high‐salinity waters using ICP‐OES with minimal dilution and provide trace element concentrations in waters from several important U.S. petroleum‐generating reservoirs where available data are sparse.  相似文献   

Relation between flow,surface‐layer armoring and sediment transport in gravel‐bed rivers     

John Pitlick  Erich R. Mueller  Catalina Segura  Robert Cress  Margaret Torizzo 《地球表面变化过程与地形》2008,33(8):1192-1209

This study investigates trends in bed surface and substrate grain sizes in relation to reach‐scale hydraulics using data from more than 100 gravel‐bed stream reaches in Colorado and Utah. Collocated measurements of surface and substrate sediment, bankfull channel geometry and channel slope are used to examine relations between reach‐average shear stress and bed sediment grain size. Slopes at the study sites range from 0·0003 to 0·07; bankfull depths range from 0·2 to 5 m and bankfull widths range from 2 to 200 m. The data show that there is much less variation in the median grain size of the substrate, D_50s, than there is in the median grain size of the surface, D₅₀; the ratio of D₅₀ to D_50s thus decreases from about four in headwater reaches with high shear stress to less than two in downstream reaches with low shear stress. Similar trends are observed in an independent data set obtained from measurements in gravel‐bed streams in Idaho. A conceptual quantitative model is developed on the basis of these observations to track differences in bed load transport through an idealized stream system. The results of the transport model suggest that downstream trends in total bed load flux may vary appreciably, depending on the assumed relation between surface and substrate grain sizes. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

The U-WEDGE Transformation Method for Multivariate Geostatistical Simulation     

Ute A. Mueller  Jacqueline Ferreira 《Mathematical Geosciences》2012,44(4):427-448

To speed up multivariate geostatistical simulation it is common to transform the set of attributes into spatially uncorrelated factors that can be simulated independently. Spatial decorrelation methods are usually based on the diagonalisation of the variance/covariance and semivariogram matrices of the set of attributes for a chosen family of lag spacings. These matrices are symmetric and there are several efficient methods for the approximate joint diagonalisation of a family of symmetric matrices. One of these is the uniformly weighted exhaustive diagonalisation with Gauss iterations (U-WEDGE) method. In contrast to the method of minimum/maximum autocorrelation factors (MAF), where a two structure linear model of coregionalisation is assumed, U-WEDGE can be applied directly to the set of experimental semivariogram matrices without having to place restrictions on the number of structures in the linear model of coregionalisation, thus removing one of the restrictions placed on the subsequent modelling of the spatial structure of the factors. We use an iron-ore data set to illustrate the method and present a comparison between the simulated attributes obtained from U-WEDGE and MAF with the full co-simulation of the attributes.  相似文献   

Determination of a precise rotation period for the Deep Space 1 target, Comet 19P/Borrelly     

Béatrice E.A. Mueller  Nalin H. Samarasinha  Jörn Helbert 《Icarus》2010,209(2):745-752

The rotation period derived by Mueller and Samarasinha (Mueller, B.E.A., Samarasinha, N.H. [2002]. Earth Moon Planets 90, 463-471) of the Deep Space 1 (DS1) mission target, Comet 19P/Borrelly, using ground-based data from July 28 to August 1, 2000, is improved by two orders of magnitude. This precision is reached in a multistep process.Combining all available ground-based data in 2000 decreases the error by an order of magnitude. Next, assuming that the rotation period did not change between 2000 and 2001, constraints from the HST 2001 data (Weaver, H.A., Stern, S.A., Parker, J.Wm. [2003]. Astron. J. 126, 444-451) yield three possible rotation periods: P = 1.088 ± 0.003 days, P = 1.108 ± 0.002 days, and P = 1.135 ± 0.003 days, which are consistent with our initial derivation of P = 1.08 ± 0.04 days (Mueller, B.E.A., Samarasinha, N.H. [2002]. Earth Moon Planets 90, 463-471).These three periods are further refined and the error bars further improved by another order of magnitude by linking the combined ground-based data from 2000 to the nuclear orientation of Borrelly at the DS1 encounter in 2001 (see Table 2). Due to aliasing, there are seven possible rotation periods around P = 1.088 days, five possible periods around P = 1.108 days, and six possible periods around P = 1.135 days, with precisions of the order of 0.0002 days (≈17 s).  相似文献   

Influences of sudden changes in discharge and physical stream characteristics on transient storage and nitrate uptake in an urban stream          下载免费PDF全文

Jennifer Mueller Price  Brian P. Bledsoe  Daniel W. Baker 《水文研究》2015,29(6):1466-1479

Changes in the physical structure of urban streams can occur abruptly due to flashy high‐flow events and subsequently alter stream processes, including transient storage and nitrate uptake. We examined temporal variability in transient storage and nitrate uptake by exploring the effects of altered physical characteristics resulting from a single high‐flow event in three reaches of Spring Creek, an urban stream in Fort Collins, Colorado, USA. Study reaches of varying geomorphic and hydraulic characteristics were chosen to represent distinct geomorphic settings in terms of substrate size, sinuosity, bed slope, and degree of rehabilitation and structural controls. We performed detailed physical characterizations and multiple nutrient injections of Br^? and NO₃^? to estimate transient storage and nitrate uptake in each reach. A comparison of pre‐flood and post‐flood data indicates that transient storage and nitrate uptake are highly context specific and mediated by interactions between geomorphic setting and flood discharge. In the two reaches that showed significant post‐flood increases in transient storage (250% to 350% increases in F_med²⁰⁰), the pool‐riffle reach exhibited a significant increase in uptake velocity, while the channelized reach did not. In contrast, transient storage decreased post‐flood in the third reach containing hydraulic structures. These complex responses likely reflect reach‐specific differences in hyporheic versus in‐channel storage. This study shows that repeat injections are necessary to describe nutrient dynamics because transient storage and nitrate uptake can be highly variable over time (showing changes on the order of 100%) due to variation in discharge and geomorphically influential flow events. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

A cleaner river: long term use of semipermeable membrane devices demonstrate that concentrations of selected organochlorines and PAHs in the Brisbane River estuary, Queensland have reduced substantially over the past decade     

Mueller JF  Mortimer MR  O'Brien J  Komarova T  Carter S 《Marine pollution bulletin》2011,63(5-12):73-76

We first used semipermeable membrane devices as samplers to evaluate concentrations of organochlorines and PAHs in the Brisbane River in 1998. Here we revisit this work and repeat the study a decade later in the same season (summer), also taking account of results from a similar study involving PAHs in the summer of 2001-2002. The accumulation of organochlorines and most PAHs in the samplers in the recent assessment was substantially less than in the 1998 deployment, suggesting that the ambient concentrations of these chemicals have decreased considerably over the last decade. In all cases there was high reproducibility of the mass of chemicals accumulated in the sampler. We used performance reference compounds in the later deployment, and assuming that the kinetics were similar in both deployment periods, we estimate that the concentration of dieldrin, the organochlorine found at highest concentrations, decreased from approximately 3.9 ng/L to about 1.4 ng/L. The decrease of most other analytes of interest including DDE and DDD was greater, potentially indicating that dieldrin is still entering the Brisbane River through run-off from urban areas where it was used widely for treatment of termites until 1995. DDT use in Australia ceased in the mid 1980s.  相似文献   

Identification of the natural product 2,3,4,5-tetrabromo-1-methylpyrrole in Pacific biota, passive samplers and seagrass from Queensland, Australia     

Gaul S  Bendig P  Olbrich D  Rosenfelder N  Ruff P  Gaus C  Mueller JF  Vetter W 《Marine pollution bulletin》2011,62(11):2463-2468

Halogenated natural products (HNPs) are frequently detected in marine organisms. High HNP concentrations have previously been found in marine mammals from the Great Barrier Reef, Australia, including in the blubber of herbivorous dugongs (Dugong dugon). To identify the source of HNPs we initially focused on the analysis of Australian seagrass (Halophila ovalis) which serves as the principal food source for dugongs. GC/MS analysis of the seagrass indicated the presence of several organobromine compounds. One compound was identified as 2,3,4,5-tetrabromo-1-methylpyrrole (TBMP) by synthesis. Subsequent analysis of semipermeable membrane devices demonstrated that the photo-sensitive TBMP is widespread in the Great Barrier Reef (Queensland, Australia). The detection of larger TBMP concentrations in fish fillets from Chile and traces in mussels from New Zealand indicated that this potential HNP may be distributed throughout the Southern Pacific Ocean.  相似文献   

Use of micro-XRF chemical analysis for mapping volcanogenic massive sulfide related hydrothermal alteration: Application to the subaqueous felsic dome-flow complex of the Cap d'Ours section,Glenwood rhyolite,Rouyn-Noranda,Québec,Canada     

Dominique Genna  Damien Gaboury  Lyndsay Moore  Wulf U. Mueller 《Journal of Geochemical Exploration》2011

A new analytical method using micro-X-ray fluorescence (XRF) is presented for the in situ analysis of major elements in rock samples. This approach has allowed for a separate study of hydrothermal alteration of matrix versus fragments in volcaniclastic material (i.e. flow breccia). This is particularly important for volcanogenic massive sulfide (VMS) exploration in subaqueous felsic dome-flow complexes, where brecciated facies are omnipresent and the imprint of hydrothermal alteration is typically heterogeneous. In this study, eleven elements are measured with a 1.7 by 1.3 mm window considered to be representative of each sample, based on replicate analyses. An average is calculated for the analyzed window and yields a nearly complete analysis with the exception of loss of ignition (LOI). Micro-XRF data were validated using whole rock XRF analyses performed on the same sample block. The application of this chemical method has been tested successfully on thin sections from the Cap d'Ours section of the Glenwood rhyolite in the Rouyn-Noranda region of Québec, Canada. With 58 samples spaced at approximately 50 m intervals, two styles of alteration zoning were recognized: (1) a lateral and concordant zoning expressed by vent-proximal silicification in the west grading toward vent-distal chlorite–sericite alteration to the east, and (2) vertical and discordant zoning expressed by stronger sericitization in the upper part of later volcanic quartz- and feldspar-phyric endogenous lobes. The former is typical of cooling induced by seawater interaction at the lava–water interface at temperatures greater than 400 °C, whereas the latter is related to lower temperature (< 300 °C) hydrothermal mineralization associated with endogenous lobe emplacement within the volcanic pile. The presented results clearly demonstrate the potential use of the micro-XRF data for characterizing weak to intense hydrothermal alteration in highly fragmented volcanic rocks.  相似文献   

Physical characterization of the potentially hazardous high-albedo Asteroid (33342) 1998 WT₂₄ from thermal-infrared observations     

Alan W. Harris  Michael Mueller  Schelte J. Bus 《Icarus》2007,188(2):414-424

The potentially hazardous Asteroid (33342) 1998 WT₂₄ approached the Earth within 0.0125 AU on 2001 December 16 and was the target of a number of optical, infrared, and radar observing campaigns. Interest in 1998 WT₂₄ stems from its having an orbit with an unusually low perihelion distance, which causes it to cross the orbits of the Earth, Venus, and Mercury, and its possibly being a member of the E spectral class, which is rare amongst near-Earth asteroids (NEAs). We present the results of extensive thermal-infrared observations of 1998 WT₂₄ obtained in December 2001 with the 3-m NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii and the ESO 3.6-m telescope in Chile. A number of thermal models have been applied to the data, including thermophysical models that give best-fit values of 0.35±0.04 km for the effective diameter, 0.56±0.2 for the geometric albedo, pv, and 100-300 J m⁻² s^−0.5 K⁻¹ for the thermal inertia. Our values for the diameter and albedo are consistent with results derived from radar and polarimetric observations. The albedo is one of the highest values obtained for any asteroid and, since no other taxonomic type is associated with albedos above 0.5, supports the suggested rare E-type classification for 1998 WT₂₄. The thermal inertia is an order of magnitude higher than values derived for large main-belt asteroids but consistent with the relatively high values found for other near-Earth asteroids. A crude pole solution inferred from a combination of our observations and published radar results is β=−52°, λ=355° (J2000), but we caution that this is uncertain by several tens of degrees.  相似文献