A New Interlaboratory Characterisation of Silicon,Rare Earth Elements and Twenty‐Two Other Trace Element Concentrations in the Natural River Water Certified Reference Material SLRS‐6 (NRC‐CNRC)

The natural river water reference material SLRS‐6 (NRC‐CNRC) is the newest batch of a quality control material routinely used in many international environmental laboratories. This work presents a nine‐laboratory compilation of measurements of major and trace element concentrations and their related uncertainties, unavailable in the NRC‐CNRC certificate (B, Cs, Li, Ga, Ge, Hf, Nb, P, Rb, Rh, Re, S, Sc, Se, Si, Sn, Th, Ti, Tl, W, Y, Y, Zr and REEs). Measurements were mostly made using inductively coupled plasma‐mass spectrometry. The results are compared with equivalent data for the last batch of the material, SLRS‐5, measured simultaneously with SLRS‐6 in this study. In general, very low concentrations, close to the quantification limits, were found in the new batch. The Sr isotopic ratio is also reported.     

THE DETERMINATION OF FLUORINE BY PROTON INDUCED GAMMA RAY EMISSION SPECTROMETRY (PIGE) IN EIGHTEEN CHINESE STANDARD REFERENCE SAMPLES OF STREAM SEDIMENTS, SOILS AND ROCKS: GSD 9-12, GSS 1-8 AND GSR 1-6

Eighteen new Chinese standard reference samples (including stream sediments, soils and rocks) have been analysed by an automated proton induced gamma ray emission (PIGE) method for fluorine. Results of determinations are reported and are generally in good agreement with the "usable values" previously published.     

Spatial variability of palaeosols across Cretaceous interfluves in the Dunvegan Formation, NE British Columbia, Canada: palaeohydrological, palaeogeomorphological and stratigraphic implications

A basic sedimentological and palaeopedological framework is now in place for non-marine sequence models. The variability of interfluve palaeosols has not, however, been systematically documented, nor have the stratigraphic implications of that variability been incorporated into sequence models. Interfluve palaeosol variability in the deltaic Dunvegan Formation, NE British Columbia, Canada, is investigated, for which a detailed allostratigraphic and palaeogeographic framework has been developed, based on abundant well (> 2300 logs) and outcrop (> 60 sections) control. Regionally extensive valley fills and interfluves have been mapped in coastal plain deposits over an area of about 50 000 km². This palaeogeographic framework permits interfluve surfaces exposed in outcrop to be located in terms of distance from the margins of coeval valleys. The micromorphological, geochemical and mineralogical characteristics of five representative sequence-bounding palaeosols located from 250 m to more than 15 km from coeval valley margins are described. These interfluve palaeosols are similar to modern Alfisols and all record (i) aggradation on an alluvial/coastal plain; (ii) a subsequent static and/or degradational phase related to valley incision, non-deposition and soil thickening; and (iii) a final aggradational phase related to valley filling and renewed sedimentation across the coastal plain. Within this overall template, however, variations in palaeosol thickness, redoximorphic features, illuvial clay content and geochemistry suggest developmental control by hydrological characteristics that were influenced by both the nature of the underlying alluvial sediments and distance from the valley margin. The presence of mature interfluve palaeosols with complex developmental histories suggests that landscape dissection may have been related to terrace development associated with valley incision. Palaeosols closer to valley margins are thicker, contain more illuvial clay and display characteristics suggesting better drained conditions relative to those palaeosols that developed further from valley margins. Subsequent deposition on interfluves also reflects distance from valleys, with those sites close to valleys accumulating cumulic soils with evidence of brackish groundwater, whereas far from valleys (> 10–15 km), groundwater was fresh and clastic supply minimal, encouraging peat formation. Variations in drainage and palaeotopography during landscape dissection resulted in different palaeosol development styles on interfluve surfaces that can be shown, on the basis of physical correlation, to have the same geomorphic age. These observations support the concept of the soil-forming interval as a basis for pedostratigraphic correlation in ancient terrestrial deposits. Palaeosol variability on interfluves is to be expected, and recognition and documentation of this variability is an important prerequisite to palaeogeomorphological, palaeoclimatic and sequence stratigraphic interpretations.     

Classifications of retail stores and shopping centres: some methodological issues

This paper reviews current methods used in classifying retail outlets and areas devoted to retailing, in the geographical and town planning literature. For retail outlets, classifications based upon types of goods sold, and types of shopping trip, are discussed. This is followed by an analysis of modern large store development which reflects property developers' and retailers' concerns. Areas devoted to retail uses are subdivided into unplanned ‘retail areas’ and planned ‘shopping centres’. Traditional classifications based upon central place theory are reviewed for both of these types, and found wanting in the light of recent changes in retail development practice and consumer behaviour. Classifications based upon physical development characteristics and type of shopping trip are recommended. Finally, classifications of urban retail location are examined. This revised version was published online in July 2006 with corrections to the Cover Date.     

Refinement Indicators for Optimal Selection of Geostatistical Realizations Using the Gradual Deformation Method

In the analysis of petroleum reservoirs, one of the most challenging problems is to use inverse theory in the search for an optimal parameterization of the reservoir. Generally, scientists approach this problem by computing a sensitivity matrix and then perform a singular value decomposition in order to determine the number of degrees of freedom i.e. the number of independent parameters necessary to specify the configuration of the system. Here we propose a complementary approach: it uses the concept of refinement indicators to select those degrees which have the greatest sensitivity to an objective function quantifying the mismatch between measured and simulated data. We apply this approach to the problem of data integration for petrophysical reservoir charaterization where geoscientists are currently working with multimillion cell geological models. Data integration may be performed by gradually deforming (by a linear combination) a set of these multimillion grid geostatistical realizations during the optimization process. The inversion parameters are then reduced to the number of coefficients of this linear combination. However, there is an infinity of geostatistical realizations to choose from which may not be efficient regarding operational constraints. Following our new approach, we are able through a single objective function evaluation to compute refinement indicators that indicate which realizations might improve the iterative geological model in a significant way. This computation is extremely fast as it implies a single gradient computation through the adjoint state approach and dot products. Using only the most sensitive realizations from a given set, we are able to resolve quicker the optimization problem case. We applied this methodology to the integration of interference test data into 3D geostatistical models.     

The influence of a season of extreme wet weather events on exposure of the World Heritage Area Great Barrier Reef to pesticides

The 2010-2011 wet season was one of extreme weather for the State of Queensland, Australia. Major rivers adjacent to the Great Barrier Reef (GBR) were discharging at rates 1.5 to >3 times higher than their long term median. Exposure to photosystem II herbicides has been routinely monitored over a period of up to 5 years at 12 inshore GBR sites. The influence of this wet season on exposure to photosystem II herbicides was examined in the context of this long-term monitoring record and during flood plume events in specific regions. Median exposures expressed as diuron equivalent concentration were an average factor of 2.3 times higher but mostly not significantly different (p<0.05) to the median for the long-term monitoring record. The herbicides metolachlor and tebuthiuron were frequently detected in flood plume waters at concentrations that reached or exceeded relevant water quality guidelines (by up to 4.5 times).     

Magnesium isotopes constraints on the origin of Mg-rich olivines from the Allende chondrite: Nebular versus planetary?

High precision Mg isotope measurements by multi-collector ion microprobe show that refractory olivines from the Allende chondrite, either olivines isolated in the matrix (2 samples studied) or olivines in type I chondrules (6 samples studied), have variable δ²⁶Mg* enrichments and deficits (calculated in permil as the ²⁶Mg deviation from the instrumental mass fractionation line) relative to the Earth. Most average δ²⁶Mg* (noted δ²⁶Mg*_av) values (between 10 and 20 analyses per chondrule) are negative but the total range is from ?0.029 (± 0.010) ‰ (2 sigma errors) to + 0.011 (± 0.011) ‰ with an exception of one olivine at + 0.043 (± 0.023) ‰. These variations in δ²⁶Mg*_av reflect the formation of the olivines from reservoirs enriched in various amounts of ²⁶Mg by the decay of short-lived ²⁶Al (T_1/2 = 0.73 Ma). Similarly, 30 analyses of olivines from the Eagle Station pallasite show a δ²⁶Mg*_av value of ?0.033 ± 0.008‰, as negative as some olivines from Allende chondrules and the Solar system initial δ²⁶Mg* value of ?0.038 ± 0.004‰ (defined at the time of formation of type B Ca–Al-rich inclusions – CAIs – when ²⁶Al/²⁷Al = 5.23 × 10^?5, Jacobsen et al., 2008).Because olivines are Al-poor and because their Mg isotopic compositions are not reset during the chondrule forming events, their δ²⁶Mg*_av can be used to calculate model crystallization ages relative to various theoretical Mg isotope growth curves. The two end-member scenarios considered are (i) a “nebular” growth in which the Al/Mg ratio remains chondritic and (ii) a “planetary” growth in which a significant increase of the Al/Mg ratio can be due to, for instance, olivine magmatic fractionation. The low δ²⁶Mg*_av value of olivines from the Eagle Station pallasite demonstrate that metal-silicate differentiation occurred as early as ~ 0. 15_- 0. 23^+ 0. 29 Ma after CAIs in either of the growth scenarios. Similarly the variable δ²⁶Mg*_av values of refractory olivines can be understood if they were formed in planetesimals which started to differentiate as early as the Eagle Station parent body. Accretion of these planetesimals must have been coeval to the formation of CAIs and their disruption could explain why their fragments (Mg-rich olivines) were distributed in the chondrule forming regions of the disk.     

A one-dimensional modeling study of the diurnal cycle in the equatorial Atlantic at the PIRATA buoys during the EGEE-3 campaign

A one-dimensional model is used to analyze, at the local scale, the response of the equatorial Atlantic Ocean under different meteorological conditions. The study was performed at the location of three moored buoys of the Pilot Research Moored Array in the Tropical Atlantic located at 10° W, 0° N; 10° W, 6° S; and 10° W, 10° S. During the EGEE-3 (Etude de la circulation océanique et de sa variabilité dans le Golfe de Guinee) campaign of May–June 2006, each buoy was visited for maintenance during 2 days. On board the ship, high-resolution atmospheric parameters were collected, as were profiles of temperature, salinity, and current. These data are used here to initialize, force, and validate a one-dimensional model in order to study the diurnal oceanic mixed-layer variability. It is shown that the diurnal variability of the sea surface temperatures is mainly driven by the solar heat flux. The diurnal response of the near-surface temperatures to daytime heating and nighttime cooling has an amplitude of a few tenths of degree. The computed diurnal heat budget experiences a net warming tendency of 31 and 27 W m⁻² at 0° N and 10° S, respectively, and a cooling tendency of 122 W m⁻² at 6° S. Both observed and simulated mixed-layer depths experience a jump between the nighttime convection phase and the well-stabilized diurnal water column. Its amplitude changes dramatically depending on the meteorological conditions occurring at the stations and reaches its maximum amplitude (~50 m) at 10° S. At 6° and 10° S, the presence of barrier layers is observed, a feature that is clearer at 10° S. Simulated turbulent kinetic energy (TKE) dissipation rates, compared to independent microstructure measurements, show that the model tracks their diurnal evolution reasonably well. It is also shown that the shear and buoyancy productions and the vertical diffusion of TKE all contribute to the supply of TKE, but the buoyancy production is the main source of TKE during the period of the simulation.     

Fully Equipped to Succeed: Migratory Contingents Seen as an Intrinsic Potential for Striped Bass to Exploit a Heterogeneous Environment Early in Life

Migratory contingents, groups of individuals belonging to the same population that adopt different migratory patterns, have been identified in numerous Striped Bass (Morone saxatilis) populations along North American East Coast. We tested the hypothesis that migratory contingents may develop early in life to maximize the exploitation of the variety of habitats faced by a recently introduced fish population. Using the discriminatory power provided by otolith chemistry, we studied early-life history stages of Striped Bass in a recently reintroduced population in the St. Lawrence Estuary. Migratory patterns were inferred using multivariate analysis of four otolith trace elements (Sr, Ba, Mn, and Mg) on juveniles (0+ and 1+). Three migratory contingents were identified during early-life history stages: freshwater residents, oligohaline migrants, and mesohaline migrants. This study demonstrates the rapid establishment, in less than 10 years since initial stocking, of three migratory contingents initiated early in life among the St. Lawrence Striped Bass population. We postulate that diversification provided by the establishment of distinct migratory contingents among early-life history stages promotes the rapid colonization of new environments through the exploration and exploitation of an increased number of nursery habitats.     

Réflexions sur la formation des bandes de Forbes : l'instabilité de la fusion de la glace saleReflections on the formation of Forbes ogives: the instability of fusion of dirty ice

Forbes ogives show alternations of dark (ice + mineral dust) and light bands at the surface of certain glaciers. We propose to understand their origin by the influence of the content of mineral matter on the lowering of the temperature and pressure of ice fusion and upon the increase of fusion velocity. We are then in an unstable situation: a local increase in the mineral content being induced by the fusion process, which in turn increases; this creates a dark band. The movement of the glacier cannot keep up with the fusion: pressure is lowered again below the fusion point, and a white band is formed. To cite this article: B. Guy et al., C. R. Geoscience 334 (2002) 1061–1070.