Mapping groundwater quality variables using PCA and geostatistics: a case study of Bajo Andarax,southeastern Spain

Abstract

A case study is presented for the application of statistical and geostatistical methods to the problem of estimating groundwater quality variables. This methodology has been applied to the investigation of the detrital aquifer of the Bajo Andarax (Almería, Spain). The use of principal components analysis is proposed, as a first step, for identifying relevant types of groundwater and the processes that bring about a change in their quality. As a result of this application, three factors were obtained, which were used as three new variables (VI: sulphate influence; V2: thermal influence; and V3: marine influence). Analysis of their spatial distribution was performed through the calculation of experimental and theoretical variograms, which served as input for geostatistical modelling using ordinary block kriging. This analysis has allowed a probabilistic representation of the data to be obtained by mapping the three variables throughout the aquifer for each sampling point. In this way, one can evaluate the spatial and temporal variation of the principal physico-chemical processes associated with the three variables VI, V2 and V3 implicated in the groundwater quality of the detrital aquifer.     

Treatment of an ECF bleaching effluent with white-rot fungi in an air-lift bioreactor

Pulp and paper mills utilise huge amount of natural resources, inorganic and organic materials along with large volume of water in different stages of paper manufacturing, resulting in a significant volume of effluents. The aim of this work was to investigate the treatment of a bleaching effluent [effluent chlorine free (ECF)] from the cellulose industry with white-rot fungi in an air-lift bioreactor. This effluent was submitted to the biological treatment with three white-rot fungi, and, every 24 h for 120 h, analytical tests were performed to analyse the quality parameters of treatment (COD, phenols, colour, pH). Before and after treatment, the effluent was analysed as its molecular mass distribution and absorptivity in the UV/VIS. Lentinus edodes, Trametes versicolor and Trametes villosa promoted similarly significant reductions in the following characteristics: (a) effluent colour (40–44 %), (b) total phenol (30–51 %) and (c) COD (37–43 %). The UV/visible spectrometry reading of the effluent after the fungi treatment showed a reduction in the absorbance of all wavelengths between 260 and 500 nm. The size exclusion HPLC profile of the effluent was modified, and the treatment promoted changes in the intensity of the peaks associated with compounds of high and low molecular weight. Phenoloxidases were produced during the treatment. T. versicolor produced the highest levels of laccase, and L. edodes was the only fungus that produced peroxidases.     

Controls on the alluviation of oxbow lakes by bed‐material load along the Sacramento River,California

Differences in the nature and quantity of sediment filling oxbow lakes have significant implications for the evolution of meandering rivers and the development of floodplains, influencing rates of meander migration and the valley width over which migration takes place. In an effort to identify the controls on the alluviation of oxbow lakes by coarse bed material, this study examined the sedimentary records stored within oxbow lakes of the Sacramento River of California, USA, and found that the volume of gravel in storage correlated negatively with the diversion angle separating flow between the river channel and the entrance into each lake. A method was devised for estimating the original channel bathymetry of the studied lakes and for modelling the hydraulic and sediment‐transport effects of the diversion angle within channels recently abandoned by meander cut‐off. The diversion angle determines the width of a flow separation within the abandoned‐channel entrance, reducing the discharge diverted from the river channel and thus limiting the ability of the abandoned channel to transport bed material. Aggradation rates are faster within entrances to abandoned channels with high diversion angles, resulting in the rapid isolation of lakes that store only a small volume of coarse‐grained sediment. Aggradation rates are slower within channel entrances where diversion angles are low, resulting in the slow transitioning of such channels into oxbow lakes with a larger and more extensive accumulation of coarse‐grained sediment. These findings compare well with observations in other natural settings and the mechanism which is described for the control of the diversion may explain why some oxbow lakes remain as open‐water environments for centuries, whereas others are filled completely within decades of cut‐off.     

THE STORM OF NOVEMBER 1826 IN THE CANARY ISLANDS: POSSIBLY A TROPICAL CYCLONE?

This work analyses a storm that occurred in the Canary Islands early in November 1826. Through a study based on historical climate data, some of the adverse effects of the storm are described and some of the possible causes are discussed. The main goal of this work is to establish an approximate reconstruction of this historical event which will allow us to compare it to a recent meteorological event that had a great impact on the archipelago: “Tropical Storm Delta”, in November 2005. Studying and reviewing the origin of the 1826 storm verifies the hypothesis that extremely violent perturbations have not only occurred in the Canaries on other occasions, but that these past events were also more intense and had more serious consequences than Delta. Therefore, the idea that other tropical perturbations have occurred in the region of the Canary Islands before Delta is presented.     

C/1995 O1 (Hale-Bopp): Gas Production Curves And Their Interpretation

The discovery of C/1995 O1 (Hale-Bopp) at 7 AU from the Sun provided the first opportunity to follow the activity of a bright comet over a large range of heliocentric distances r_h. Production rates of a number of parent molecules and daughter species have been monitored both pre- and postperihelion. CO was found to be the major driver of the activity far from the Sun, surpassed by water within 3 AU whose production rate reached 10³¹ s⁻¹ at perihelion. Gas production curves obtained for various species show several behaviours with r_h. Gas production curves contain important information concerning the physical state of cometary ices, the structure of the nucleus and all the processes taking place inside the nucleus leading to outgassing. They are relevant to the study of several other phenomena such as the sublimation from icy grains, dust mantling or seasonal effects. For some species, such as H₂CO or HNC, they permit to constrain their origin in the coma. We discuss models of subsurface gas production in distant comets and predictions of how such a source may vary as the comet moves along its orbit, approaching perihelion and receding again. Features in the observed gas production curves of comet Hale-Bopp are generally interpretable in terms of either subsurface production (typical example: CO at large r_h) or free sublimation (typical example: H₂O). Possible implications for the vertical stratification of the cometary ices are reviewed, and preference is found for a model with crystallization of amorphous ice close to the nuclear surface. This revised version was published online in July 2006 with corrections to the Cover Date.     

Auroras Observed in Portugal in Late 18th Century Obtained from Printed and Manuscript Meteorological Observations

We present a new catalogue of observations of the aurora borealis at Lisbon, i.e., at low-latitudes, in the late 18th century by Jacob Præ torius and Henrique Schulze, two German artillery officers. Dates of 18 auroras compiled by Præ torius and Schulze are compared with those published in other catalogues for that period. The number of annual auroras observed by the two Germans is then compared with two indices of solar activity showing a very good level of consistency between all time series. Finally, we have assessed the number of auroras observed taking into consideration the phase of the lunar cycle and the geomagnetic latitude of Lisbon.     

Newly identified “Tunnunik” impact structure,Prince Albert Peninsula,northwestern Victoria Island,Arctic Canada

Regional geological mapping of the glaciated surface of northwestern Victoria Island in the western Canadian Arctic revealed an anomalous structure in otherwise flat‐lying Neoproterozoic and lower Paleozoic carbonate rocks, located south of Richard Collinson Inlet. The feature is roughly circular in plan view, approximately 25 km in diameter, and characterized by quaquaversal dips of approximately 45°, decreasing laterally. The core of the feature also exhibits local vertical dips, low‐angle reverse faults, and drag folds. Although brecciation was not observed, shatter cones are pervasive in all lithologies in the central area, including 723 Ma old dikes that penetrate Neoproterozoic limestones. Their abundance decreases distally, and none was observed in surrounding, horizontally bedded strata. This circular structure is interpreted as a deeply eroded meteorite impact crater of the complex type, and the dipping strata as the remnants of the central uplift. The variation in orientation and shape of shatter cones point to variably oriented stresses with the passage of the shock wave, possibly related to the presence of pore water in the target strata as well as rock type and lithological heterogeneities, especially bed thickness. Timing of impact is poorly constrained. The youngest rocks affected are Late Ordovician (approximately 450 Ma) and the impact structure is mantled by undisturbed postglacial sediments. Regional, hydrothermal dolomitization of the Ordovician limestones, possibly in the Late Devonian (approximately 360 Ma), took place before the impact, and widespread WSW–ENE‐trending normal faults of probable Early Cretaceous age (approximately 130 Ma) apparently cross‐cut the impact structure.     

The Trojan problem

There has been a renewed interest in the Trojan problem in recent years. Significant progress has been made in discovering and understanding dynamical features of motion of Jupiter's Trojan asteroids. The dynamics of hypothetical Trojan-type asteroids of other major planets has also been the subject of several recent investigations. This paper offers an overview on the current status of researches on real and hypothetical Trojan asteroids of the major planets. Results of analytical and numerical works are surveyed. Questions of dynamical properties, long-term evolution of orbits, stability regions around the triangular Lagrangian points are discussed among other problems of the Trojans.