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991.
José Antonio Grande María Luisa De La Torre María Santisteban Teresa Valente José Paulino Fernandez Eva Pérez-Ostalé 《水文科学杂志》2013,58(8):1503-1511
ABSTRACTThis paper presents hydrochemical data of an AMD stream, Poderosa Creek, in the Iberian Pyrite Belt, obtained between its source, in the Poderosa Mine portal, and its confluence with the Odiel River. The main objective is to establish potential interdependent relationships between sulphate and metal loads and the following physico-chemical variables: pH, electrical conductivity (EC), redox potential (EH) and dissolved oxygen (DO). All the parameters show an overall increasing tendency from the tunnel exit to the confluence at the Odiel River. The TDS and EC are two relevant exceptions. They behave similarly, showing a decreasing trend and a strong inflection that describes a minimum immediately after the discharging point. Spatial analysis combined with statistical tools reveal typical AMD processes and the respective physico-chemical implications. Inputs with distinctive hydrochemical signatures impose relevant modifications in the Poderosa Creek waters. This indicates low hydrochemical inertia and high vulnerability to external stimuli.
Editor D. Koutsoyiannis; Associate editor not assigned 相似文献
992.
Juan C. Colombo Carlos N. Skorupka Claudio Bilos Leandro Tatone Natalia Cappelletti M. Carolina Migoya 《水文科学杂志》2013,58(6):1155-1163
AbstractWater quality of the Uruguay River was evaluated with multi-parametric (temperature, turbidity, conductivity, pH, dissolved oxygen) and sediment trap data (particle flux, total organic carbon and nitrogen contents) and correlated to precipitation, river discharge and El Niño Southern Oscillation (ENSO) indices for the period 2006–2011. Hydro-meteorological parameters averaged 24–85% variability with coincident precipitation (200–400 mm month-1), discharge (7000–28 000 m3 s-1) and turbidity peaks (50–80 NTU) in the austral spring, and absolute maxima during the El Niño 2009 episode. Spectral analysis of discharge and sea-surface temperature anomaly (SSTA) showed consistent variance maxima at approx. 3 and 1.5 years. Deseasonalized discharge was significantly correlated to SSTA. During river floods, pH decreased (from 7.5 to 6.6) and particle dynamics peaked (turbidity: 15–80 NTU; vertical fluxes: 20–200 g m-2 d-1; total solid load: <1000 to 100 000 t d-1),whereas TOC remained stable (3.2 ± 0.8%) and C/N ratios increased (10–12) due to the higher contribution of terrestrial detritus. 相似文献
993.
Samuel Beskow Luis Carlos Timm Vitor Emanuel Quevedo Tavares Tamara Leitzke Caldeira Leandro Sanzi Aquino 《水文科学杂志》2013,58(14):2567-2578
ABSTRACTThe objective of this study was to evaluate, based on a data-scarce basin in southern Brazil, the potential of the Lavras Simulation of Hydrology (LASH) model for estimating daily streamflows, annual streamflow indicators and the flow–duration curve. It was also used to simulate the different runoff components and their consistency with the basin physiographical characteristics. The statistical measures indicated that LASH can be considered suitable according to widely used classifications and when compared with other studies involving hydrological models. LASH also showed satisfactory results for annual indicators, especially for maximum and average annual streamflows, as well as for the flow–duration curve. It was found that the model was consistent with the basin characteristics when simulating runoff components. The results obtained in this study allowed us to conclude that the LASH model has the potential to aid practitioners in water resources management of basins with scarce data and similar soil and land-use conditions.
Editor A. Castellarin; Associate editor Y. Gyasi-Agyei 相似文献
994.
Flow near a model spur dike with a fixed scoured bed 总被引:1,自引:0,他引:1
Three-dimensional flow velocities were measured using an acoustic Doppler velocimeter at a closely spaced grid over a fixed scoured bed with a submerged spur dike. Three-dimensional flow velocities were measured at 3,484 positions around the trapezoidal shaped submerged model spur dike. General velocity distributions and detailed near field flow structures were revealed by the measurement. Clear differences were revealed between flow over fixed flat and scoured beds. Strong lateral flows were the dominant cause of the observed local scour. Shear stresses were higher for the scoured bed than in the flat bed case. Decreasing rates of scour as the scour hole developed were attributed to increases in critical shear stress in the scour holes caused by the increase in the length and magnitude of adverse slopes associated with the two main scour holes. 相似文献
995.
Soil Microbial and Enzyme Activities Response to Pollution Near an Aluminium Smelter 总被引:2,自引:0,他引:2
Juan Carlos García‐Gil Jozef Kobza Pedro Soler‐Rovira Soňa Javoreková 《洁净——土壤、空气、水》2013,41(5):485-492
The aim of this research was to assess the impact caused by a long‐term pollution by fluoride and heavy metals in two soils (PS1 and PS2) near an aluminium smelter in Slovakia, on soil microbial biomass C (MBC), basal respiration, metabolic quotient (qCO2) water‐soluble organic C (WSOC) and enzymes activities involved in the C, N and P biogeochemical cycles. An unpolluted soil was used as control (C0). Results obtained for soil fluoride content reflected a gradient of fluoride exposure in topsoils of contaminated sites. Decreases in microbial and enzymatic activities and in MBC to organic C ratio were found in PS2 site, which is closer to the smelter and exhibited the highest fluoride content. PS1‐soil showed an extreme alkaline pH caused by leaching of waste effluents from the smelter dumping site, higher contents of Zn, Cu, Pb and Cd, significantly larger MBC, qCO2 and catalase and urease activities, and much larger basal respiration and dehydrogenase activity than PS2 and C0‐soil. Phosphatase, β‐glucosidase and BAA‐protease were negatively correlated with WSOC, basal respiration and dehydrogenase activity, and showed some degree of inhibition in polluted sites. These results may indicate different responses of microbial communities to ecosystem disturbances, caused by the drastic changes in soil's physicochemical properties as result of the long‐term emissions of fly ash with high levels of contaminants that are still affecting soil microbial and enzymatic activities. 相似文献
996.
Constantin Cosma Alexandra Cucoş Botond Papp Robert Begy Tiberiu Dicu Mircea Moldovan Lucia Adina Truţă Dan Constantin Niţă Bety-Denissa Burghele Liviu Suciu Carlos Sainz 《Acta Geophysica》2013,61(4):859-875
B?i?a-?tei mine is an open pit mine in NW Romania (West Carpathian Mountains). It was the largest surface uranium deposit in the world. Two means of uranium transport and dissemination were used over time. The first was the natural way, represented by transportation of geological sediments by Cri?ul-B?i?a River that crosses the B?i?a surface deposit. These sediments were used as building materials (stone, gravel, sand). The second way was related to the people living in this valley, who used also the uranium waste as building material. The preliminary indoor radon concentrations measured in the buildings ranged from 40 to 4000 Bq m?3 with a mean value of 241 Bq m?3. A focused radon survey facilitated the selection of 20 houses with the highest indoor radon that were therefore proposed for remediation. To find the radon sources of these houses, systematic investigations on radon were performed. The remedial measures for these 20 houses were tested on a chosen pilot house. 相似文献
997.
Lobate scarps, thought to be the surface expression of large thrust faults, are the most spectacular contractional tectonic features visible on Mercury. Most lobate scarps follow a general and relatively simple pattern, with a roughly arcuate or linear form in plan view, and an asymmetric cross section characterized by a steeply rising scarp face and a gently declining back scarp. In this work, we study two peculiar and complex scarps in the Rembrandt region of Mercury through MESSENGER imagery. On the one hand, the formation of these scarps resulted in the deformation of features such as impact craters, fractures, extensional faults, and volcanic plains, while on the other hand, the deformed features partly influenced the formation of the scarps. Evidence for structural control on the formation of the scarps includes their orientation, segmentation, bifurcation, change in structural trend and dip orientation, and transition into high-relief ridges or wrinkle ridge morphologies in some cases. Thus, these two lobate scarps provide examples of complex geological relations among other features, expanding the recognized richness of mercurian geology. Also, the southern scarp records a complex history of contraction, suggesting that the development of some mercurian lobate scarps may be more complex than usually thought. 相似文献
998.
Robert S. French Mark R. Showalter Rafael Sfair Carlos A. Argüelles Myriam Pajuelo Patricio Becerra Matthew M. Hedman Philip D. Nicholson 《Icarus》2012,219(1):181-193
Image photometry reveals that the F ring is approximately twice as bright during the Cassini tour as it was during the Voyager flybys of 1980 and 1981. It is also three times as wide and has a higher integrated optical depth. We have performed photometric measurements of more than 4800 images of Saturn’s F ring taken over a 5-year period with Cassini’s Narrow Angle Camera. We show that the ring is not optically thin in many observing geometries and apply a photometric model based on single-scattering in the presence of shadowing and obscuration, deriving a mean effective optical depth τ ≈ 0.033. Stellar occultation data from Voyager PPS and Cassini VIMS validate both the optical depth and the width measurements. In contrast to this decades-scale change, the baseline properties of the F ring have not changed significantly from 2004 to 2009. However, we have investigated one major, bright feature that appeared in the ring in late 2006. This transient feature increased the ring’s overall mean brightness by 84% and decayed with a half-life of 91 days. 相似文献
999.
Antonio González-Ramón Manuel López-Chicano Juan Carlos Rubio-Campos 《Environmental Earth Sciences》2012,67(3):923-937
A small karst aquifer of great structural complexity has been subjected to significant resource withdrawal over recent decades. This exploitation aroused social conflict due to the effect it has had on emblematic springs. This research has analysed piezometric data collected over the course of 12 years and the spatial hydrochemical data supplied by the main water points associated with it. The spatial and temporal evolution of the main chemical species in the groundwater and the hydrogeochemical processes affecting them have been studied, modelling them with the programme PHREEQC. These data suggest a complicated model of hydrogeological function with sectors storing water at different depths and connected to each other locally as determined by the geological structure. 相似文献
1000.
Mapping the Risk of Burning in the Brazilian Amazon with the Use of Logistic Regression and Fuzzy Inference 总被引:1,自引:1,他引:0
Camil Wadih Salame Joaquim Carlos Barbosa Queiroz Gilberto de Miranda Rocha Mario Miguel Amin 《Mathematical Geosciences》2012,44(3):241-256
Through the PRODESDIGITAL Project, the National Institute for Space Research (INPE) has been mapping vegetal coverage in the
Brazilian Legal Amazon using Landsat satellite images. INPE not only identifies deforested areas but also releases a daily
map of burning areas. Burning is frequently used as the cheapest way to deforest, to clear areas for farming and to increase
the soil’s fertility in a short period of time. In many instances, these fires get out of control and end up accidentally
invading areas of forest exploited by the lumber industry, agricultural plantations and pastures. However, the deforestation
and burning area maps alone are insufficient for monitoring and control on a regional scale. It is necessary to know in an
analytical way how actions (deforestation and burnings) that characterize human occupation are occurring in a region. In this
research, two methods are used that allow the inclusion of co-variation in the estimation of variables of interest: logistic
regression, which is a statistical method that considers a categorical or discrete response variable and discrete and/or continuous
co-variation; and fuzzy logic, which makes use of artificial intelligence methods to incorporate into computational models
information based on the knowledge or experience of a specialist. In both methods, the response variable may be related to
the probability of occurrence of the environmental variable under study. 相似文献