Modelling of the groundwater hydrological behaviour of the Langueyú creek basin by using N‐way multivariate methods

The groundwater hydrochemical behaviour of the Langueyú creek basin (Argentina) has been evaluated through a systematic survey, followed by application of hydrological and chemometric multivariate techniques. Ten physicochemical parameters were determined in groundwater samples collected from 26 wells during four sampling campaigns (June 2010; October 2010; February 2011 and June 2011), originating a tridimensional experimental dataset X . Univariate statistical and graphical hydrochemical tools (contour maps and Piper diagrams) applied to individual campaigns, allowed to reach some preliminary conclusions. However, a best visualization of the aquifer behaviour was achieved by applying Principal Component Analysis (MA‐PCA) and N‐way PCA procedures, Parallel Factor Analysis and Tucker3. Results were consistent with two‐term models, being Tucker3 [2 2 1] the most adequate, explaining a large amount of the dataset variance (50.7%) with a low complexity. The first Tucker3 [1 1 1] interaction (38.2% of variance) is related with (i) calcium/magnesium versus sodium/potassium ion exchange processes; (ii) an increase of ionic concentration and (iii) a decrease of nitrate pollution, all processes along the direction of the groundwater flow. The second [2 2 1] interaction (12.5% of variance), accounts for the predominant role played by conductivity, bicarbonate and magnesium in the dataset. The seasonal variations are closely related to concentration/dilution phenomena originated by the variations of the phreatic levels, although this point will require additional sampling to establish a definitive hydrochemical model. Copyright © 2013 John Wiley & Sons, Ltd.     

The first description and confirmation of the Vista Alegre impact structure in the Paraná flood basalts of southern Brazil

Abstract– The Vista Alegre structure, centered at 25°57′S and 52°41′W, has been recently proposed as a meteorite impact structure. The 9.5 km‐diameter structure is located in the Paraná state of southern Brazil, within the Paraná Basin, which contains one of the largest and most extensive flood basalt provinces on Earth. The Paraná flood basalts belong to the Serra Geral Formation and are temporally related to the opening of the South Atlantic Ocean, having been dated at about 133–132 Ma. Tholeiitic basalts dominate the western portion of Paraná state, with some minor rhyodacites. Morphologically, Vista Alegre has a prominent circular outline, in the form of an incomplete ring of escarpments, and an inner depression. The presence of a central uplift is not obvious, but it is inferred by the occurrence of deformed sandstone blocks near the center of the structure. These sandstones are possibly related to the Triassic Pirambóia Formation and/or to the Cretaceous Botucatu Formation. These units are normally at stratigraphic depths of about 700–800 m below the present surface in this portion of the Paraná Basin. The structure appears to be in an advanced erosion stage and its interior is occupied by a soil cover several meters thick, extensively used for agriculture. As a result there are limited outcrops in the interior of the structure, all of polymict breccias, some of them melt‐bearing. We report the extensive occurrence of shatter cones, in the form of fine‐grained rock clasts within the polymict breccias. The shatter cone‐bearing breccias occur at different locations within the structure, separated by several kilometers. The nested shatter cones range in size from about 0.5 to 20 cm for individual cones, and up to half a meter for complete assemblages. The shatter cones formed in fine‐grained Parana flood basalt and might be the first examples of shatter cones in such a rock type. In addition, planar deformation features (PDFs) were found in quartz grains within sedimentary rock clasts of the polymict breccia. These findings confirm the impact origin of the Vista Alegre structure.     

Dynamics of contaminants in phosphogypsum of the fertilizer industry of Huelva (SW Spain): From phosphate rock ore to the environment

The dynamics of trace elements from phosphate rock ore to the environment in a phosphoric acid plant located in SW Spain and the impact of phosphogypsum wastes were investigated through total digestion and BCR-sequential extraction. Based on total concentration, element transfer factors as criteria for examining the potential environmental risk of waste with respect to ore rock were calculated, and it was observed that most trace elements are only transferred into phosphogypsum at rates of 2–12%. However, based on those concentrations that are likely to be most readily mobile in the environment, phosphogypsum acts as a higher emission source of contaminants than the original rock. About 100 million tonnes of phosphogypsum are stack-piled in a dump of 1200 ha over salt-marshes of an estuary formed by the confluence of the Tinto and Odiel rivers. Phosphogypsum has been applied, at the recommended rate of 20–25 t/ha since 1978–2001, to improve fertility and reduce Na saturation in agricultural soils of the Guadalquivir river valley (140 km²). Phosphogypsum capacity as a source of mobile contaminants in three environmental scenarios (water leaching, exposure to oxidising and reducing conditions) was quantified by combining sequential extraction and waste mass. The amounts of mobile contaminants that could be released for every tonne of phosphogypsum are approximately 7 × 10² g Sr, 1.1 × 10² g Fe, 55 g Y, 30 g Ce, 12 g Cr, 11 g Ti, 5 g Zn, 4 g each of Cu and Pb, 3 g each of V and Cd, 2 g each of As and Ni and 1 g U. Multiplying these amounts by 100 Mt and 20–25 t/ha, it is possible to calculate risk assessments of phosphogypsum for both estuarine zones, e.g. in a hypothetical stack collapse and waste spilling, and agricultural soils, respectively.     

First Late Triassic Record of a Paleoentomofauna from South America(Malargüe Basin,Mendoza Province,Argentina)

<正>Late Middle Triassic to early Late Triassic insects from Argentina have been previously described from the Bermejo and Cuyana Basins where they have been recovered from the Ischichuca-Los Rastros and Potrerillos-Cacheuta Formations,respectively.The insect fauna discussed herein was collected during field studies in 1986/1987 from the Llantenes section(Norian to Rhaetian? Late Triassic),which is situated in the Malargue Basin in southern Mendoza province.The insect remains were found in the upper part of the Llantenes section (Llantenes Formation),which is built up of two coarsening-upwards cycles reflecting a deltaic progradation of a fluvial into a lacustrine environment(lower part),succeeded by repeated progradations into a floodplain-dominated environment(upper part;with finds of insects,conchostracans,fish remains,plant fragments,and drifted logs).The new finds represent the youngest Triassic insect records described from Argentina and even from South America in its entirety.There is only one contemporaneous fossil assemblage in Gondwana:in the Clarence/Moreton Basin(Aberdare Conglomerate;Late Norian)in Australia.The new Triassic insects include an impression of an isolated Mecopterida-like wing(Mendozachorista volkheimeri gen.et sp.nov.; Mendozachoristidae fam.nov.),coleopteran elytra of the Permosynidae(Ademosyne rosenfeldi sp.nov.and Ademosyne llantenesensis sp.nov.)and other isolated body fragments.This new Late Triassic entomofauna from Argentina is of considerable importance in the reconstruction of the biotic recovery of continental environments in Gondwana after the catastrophic mass extinction at the P/T boundary.     

Heavy metal mobility assessment in sediments from the Odiel River (Iberian Pyritic Belt) using sequential extraction

The Tessier sequential extraction scheme (SES) was applied to sediments from the Odiel river catchment (Iberian Pyritic Belt, SW of Spain), one of the most acid rivers on Earth, to assess the chemical association (exchangeable, carbonatic, bound to manganese and iron oxides, bound to organic matter and residual mineral) of heavy metals (Zn, Cd, Pb, Cu, Cr, Mn, Ni, Fe, and Hg). Sediments are very heterogeneous in their textural characteristics, showing different grain size. Twenty-seven samples were studied from from areas along the Odiel River, from the source to the mouth, with special interest in the Odiel Marshes Natural Park due to its ecological significance. Samples were classified as sandy (especially at the river mouth with low iron oxide and organic matter content) and clay-silty (in the middle of the river catchment with high iron oxide content). The numerous sandy samples with low pH values explain the low levels of metals upstream, although potential metals contributions arise from mining and ore. However, the presence of sulfate in the mining area and carbonate at the mouth may explain the high presence of lead and iron in these sandy zones. Some percentage of mobile Ni, Cu, and Zn were detected in the mining area, but the elevated relative percentage of exchangeable Cd in the estuary is even more remarkable. The percentage of Zn bound to carbonate is considerable in the catchment but especially in the estuary. However, Cu is only detected in the carbonate phase downstream, in spite of the low concentration of carbonate, which represents a drawback in the application of the Tessier SES to these types of samples. Finally, relatively high percentages of residual, non-mobile, Hg and Pb were observed, in the estuarine and mining areas, respectively. Sand, lime, and clay fractions of representative samples from Areas I, II, and III were used in a metal speciation study. Mainly, the elements analyzed had accumulated in the non-residual fractions. In the mining area of the Pyrite Belt, the elements analyzed are mainly bound to Fe–Mn oxides (Fe + Mn + Cu + Cr + Pb + Mn ± Zn) and the organic matter/sulfide fraction (Ni + Zn + Hg ± Cd), independent of sediment grain size. In conclusion, we show that the results of the study of chemical speciation in sediments from acid rivers are independent of the sediment grain size considered.     

Invariance in Von Zeipel method

Celestial Mechanics and Dynamical Astronomy - In this paper the relation between the Von Zeipel generating functions, in two canonical systems, is considered. Explicit recursive formulae between...     

Remote Observation of the Spatial Variability of Surface Waves Interacting With an Estuarine Outflow

This paper explores the application of phased-array high-frequency (HF) radars to identify locations of enhanced local waveheights. Measurements of the near-surface current velocities and waveheights were obtained from HF radars deployed near the mouth of the Chesapeake Bay in the fall of 1997. The radar-derived near-surface velocities were compared with the upper bin (2-m depth) of four upward-looking acoustic Doppler current profilers (ADCPs). The slopes of the linear correlations were close to one and the root-mean-square (rms) differences were similar to previous studies. Significant waveheight (Hs) estimates from both radars were compared with a laser height gauge. The largest differences were observed during low winds due to overestimates at one of the radar stations and during storms when the laser measurement failed. Further analysis focused on the HF radar results from the more reliable of the two sites. The rms difference between this radar and the in situ sensor was 0.29 m. Synoptic observations of Hs over the Chesapeake Bay revealed regions of current-induced wave shoaling and refraction. Hs over the estuarine outflow increased between 19-50% relative to the incident Hs in light onshore winds (~5 m/s). In stronger winds (>10 m/s), Hs also increased by up to 25% when there was a tidal outflow in the surface layer, although the near-surface currents were responding to both the wind and the ebbing tide. Hs was not enhanced when the outflow was below a thicker layer (>5 m) of wind-forced onshore flow     

Chemical Evolution from the AGB to the Planetary Nebula Phase

An overview is given on the wealth of data recently provided by large mm-wave radiotelescopes on AGB stars, planetary nebulae (PNe), and transition objects. The observations reveal that there is an observable chemical evolution in the neutral gas as a star evolves beyond the AGB, through the proto-PN and PN phases. Significant changes in the abundances of some key molecules (such as CS, CN, HCO+, HCN, and HC3N) take place during the fast evolution of the envelopes. Chemistry can thus be used as a rough clock to date the evolutionary stage of post-AGB envelopes and proto-PN objects. However, once the PN is formed, the observed abundances in the molecular clumps of the envelope remain relatively constant. The chemical evolution of the molecular envelopes likely occurs through the development of photon-dominated regions produced by the ultraviolet field of the central star. The main chemical processes which likely control the evolution are also reviewed. This revised version was published online in September 2006 with corrections to the Cover Date.     

Hysteretic energy spectrum and damage control

The inelastic response of single‐degree‐of‐freedom (SDOF) systems subjected to earthquake motions is studied and a method to derive hysteretic energy dissipation spectra is proposed. The amount of energy dissipated through inelastic deformation combined with other response parameters allow the estimation of the required deformation capacity to avoid collapse for a given design earthquake. In the first part of the study, a detailed analysis of correlation between energy and ground motion intensity indices is carried out to identify the indices to be used as scaling parameters and base line of the energy dissipation spectrum. The response of elastoplastic, bilinear, and stiffness degrading systems with 5 per cent damping, subjected to a world‐wide ensemble of 52 earthquake records is considered. The statistical analysis of the response data provides the factors for constructing the energy dissipation spectrum as well as the Newmark–Hall inelastic spectra. The combination of these spectra allows the estimation of the ultimate deformation capacity required to survive the design earthquake, capacity that can also be presented in spectral form as an example shows. Copyright © 2001 John Wiley & Sons, Ltd.     

Cryogenic Drilling: A New Drilling Method for Environmental Remediation

Cryogenic drilling is a technique developed at the University of California (UC), Berkeley, for drilling in unstable sediments of environmental monitoring, for characterizing, and for remediation wells, The method uses standard air rotary drilling techniques, but with cold nitrogen rather than ambient air as the circulating fluid in order to freeze and stabilize the borehole wall. Several laboratory and full-scale field tests have been performed. A.52-foot-deep (16 m) soil boring and 24 foot (7 m) monitoring well have been drilled as part of the Lawrence Berkeley Laboratory Site Characterization Project. Continued testing and refinement of the equipment and operational method are in progress. The method has been proposed for use as part of the Department of Energy (DOE) weapons site cleanup at locations with unstable sediments such as Hanford, Sandia, and Idaho National Engineering Laboratory (INEL).