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821.
Jaroslava Hajná Ji?í ?ák Václav Kachlík Martin Chadima 《International Journal of Earth Sciences》2012,101(7):1855-1873
The Teplá–Barrandian unit (TBU) has long been considered as a simply bivergent supracrustal ‘median massif’ above the Saxothuringian subduction zone in the Variscan orogenic belt. This contribution reveals a much more complex style of the Variscan tectonometamorphic overprint and resulting architecture of the Neoproterozoic basement of the TBU. For the first time, we describe the crustal-scale NE–SW-trending dextral transpressional Krakovec shear zone (KSZ) that intersects the TBU and thrusts its higher grade northwestern portion severely reworked by Variscan deformation over a southeastern very low grade portion with well-preserved Cadomian structures and only brittle Variscan deformation. The age of movements along the KSZ is inferred as Late Devonian (~380–370?Ma). On the basis of structural, microstructural, and anisotropy of magnetic susceptibility data from the KSZ, we propose a new synthetic model for the deformation partitioning in the Teplá–Barrandian upper crust in response to the Late Devonian to early Carboniferous subduction and underthrusting of the Saxothuringan lithosphere. We conclude that the Saxothuringian/Teplá–Barrandian convergence was nearly frontal during ~380–346?Ma and was partitioned into pure shear dominated domains that accommodated orogen-perpendicular shortening alternating with orogen-parallel high-strain domains that accommodated dextral transpression or bilateral extrusion. The synconvergent shortening of the TBU was terminated by a rapid gravity-driven collapse of the thickened lithosphere at ~346–337?Ma followed by, or partly simultaneous with, dextral strike-slip along the Baltica margin-parallel zones, driven by the westward movement of Gondwana from approximately 345?Ma onwards. 相似文献
822.
J. I. Huertas M. E. Huertas J. Díaz 《International Journal of Environmental Science and Technology》2012,9(2):195-202
Assuming that state-of-the-art air quality models are accurate, then the precision and accuracy of their results directly depend on the precision and accuracy of their geographical, meteorological and emission input data. There are important applications, such as open pit mining, in which emission data are the main source of uncertainty. In such cases, historical air quality experimental data are typically available. The present work proposes a backward air quality simulation approach to assess the accuracy of emission inventories for these applications, with the goal of identifying sources that are over or underestimated. This approach consists of finding constants of the linear combination of the estimated emission that maximize R 2 and make the slope equal to one in the linear correlation analysis when the results from the air quality model are compared to the experimental measurements of air quality. This methodology was applied to the case of the mining region in northern Colombia. As one of the largest open pit coal mining regions in the world, this region consists of seven independent mines with no relevant additional sources of emission. Use of the proposed methodology allowed quantification of the amount by which companies over or underestimated their emission, as well as quantification of uncertainties due to sources not considered in the model but that locally affect each monitoring station. 相似文献
823.
U. J. López-Chuken U. López-Domínguez R. Parra-Saldivar E. Moreno-Jiménez L. Hinojosa-Reyes J. L. Guzmán-Mar E. Olivares-Sáenz 《International Journal of Environmental Science and Technology》2012,9(1):69-77
Chloride salinity has been strongly related to enhanced cadmium (Cd) uptake by plants due to increased solubility in the soil solution, even in agricultural soil with very low levels of cadmium. This finding is relevant because the cadmium content of food crops is an important concern for human health. Therefore, the aim of this study was to predict and discuss the chlorine-enhanced uptake of cadmium by two common crops: maize and tobacco under ??non-saline?? (1?mM) and ??very strongly saline?? (200?mM) scenarios using a modified ??biotic ligand model?? and datasets from a set of soil and hydroponic experiments. Results indicated that predicted cadmium uptake rates (expressed as cadmium in plant ??mol?m?2 root) by maize and tobacco plants were consistently higher (54 and 15%, respectively) assuming conditions of ??very strong salinity?? soil compared to the simulated ??non-saline?? soil. In the light of the results of the present research, valuable information is given on modeled cadmium phytoavailability as an indication of the potential risk due to increased cadmium uptake by crops under saline conditions, especially as the enhancement of cadmium uptake in the presence of Cl? salinity may be a general trend that occurs in many edible crops. The biotic ligand model parameterization applied in the present study attempted to simulate conditions commonly found in natural cadmium and salt-affected soils. However, caution is needed to extrapolate results obtained from these models to real soil conditions. 相似文献
824.
Fuenmayor spring has been monitored continuously for identification purposes to study the behavior of a karst groundwater
system. This paper initially deals with linear methods employing system engineering techniques for the analysis and identification
of a hydrological system, considered as a black box model, which disregards information on the internal structure of the aquifer.
Under a linear time invariant hypothesis, the application of the simple correlation of spectral analysis and parametric identification
of transfer function generated some interesting results in the monitored spring. These tools have historically been successful
in studying a large number of karst springs and continue to be practical approximations in initial attempts to obtain a draft
model. Because of the nonlinear and nonstationary nature of karst, more effective systemic techniques are required to cover
certain aspects of analysis that the linear system cannot reveal adequately. This paper presents interesting results using
Fuenmayor spring data, collected over almost 10 years, to show the ability of wavelet techniques in the identification of
a karst spring system. 相似文献
825.
M. G. García K. L. Lecomte Y. Stupar S. M. Formica M. Barrionuevo M. Vesco R. Gallará R. Ponce 《Environmental Earth Sciences》2012,65(2):535-545
Symptoms of dental fluorosis have been observed in rural communities located in the Sierras Pampeanas de Córdoba, a mountainous
area in Central Argentina. The clinical assessment was performed in the Charbonier Department, where the fluoride (F−) intake was determined to be 3.90 ± 0.20 mg day−1 (n = 16). In this community, mild and severe fluorosis reach an incidence of 86.7% (total teeth surface = 636 teeth) among the
children population. To determine the origin and distribution of fluorine in natural waters from the Charbonier Department
and nearby regions, sampling was performed in the area covering the San Marcos River basin. The obtained results show that
F− concentrations vary between ~1 to ~2.5 mg l−1, with an outlier value of 8 mg l−1. The spatial distribution of F− shows that the lowest concentrations are found at the basin’s catchments. Maximum values are located in two sectors of the
basin: the Charbonier depression in the eastern part and at the San Marcos village, downstream the main collector, in the
western part of the basin. In these two regions, the F− contents in ground- and surface waters are >2.0 mg l−1 and nearly constant. Dissolved F− in natural waters from the study area has its origin in the weathering of F-bearing minerals present in the region’s dominant
lithology. The extent of mineral weathering is mostly determined by the residence time of water within the aquatic reservoir.
Longer residence times and a major solid–water interaction lead to enhanced release of F−. This explains the higher F− concentrations found in basin areas with lower run off. The removal of F− from water appears to occur by neither fluorite precipitation, nor by adsorption. Hence, variations in F− concentrations seem to be more related to regional hydrological conditions. 相似文献
826.
D. E. Martínez O. M. Quiroz Londoño H. E. Massone P. Palacio Buitrago L. Lima 《Environmental Earth Sciences》2012,65(2):411-420
Fluoride pollution is a widespread problem in Argentina, as it is in many areas of the World. Former investigations have demonstrated
that the dissolution of volcanic glass disseminated in the loess-like sediments is the main source of fluoride in the Argentine
pampas. Nevertheless, fluoride distribution is erratic and the factors controlling it are not yet well-known. A large amount
of hydrochemical data collected in the Quequen Grande river catchment is used in order to contribute to the understanding
of fluoride distribution and mobility in groundwater in the Argentine pampas. The Quequen Grande river catchment is 10,000 km2. It extends between two low hills ranges of Precambrian metamorphic rocks and sedimentary Paleozoic rocks, filled by a thick
sequence of Cenozoic sediments, mainly silts and silt-clayed, with sand layers. These sediments form a multilayer phreatic
aquifer, which is recharged from precipitation infiltration, discharging through streams directly into the sea. Fluoride concentration
in surface water (n = 353) ranges between 0 and 6.5 mg/l, with an average value of 2.14 mg/l. Groundwater concentration (n = 135) is from 0 up to 5.7 mg/l, with an average of 1.84 mg/l. Considering the statistic distribution of fluoride, two groups
of samples can be determined. A dominant group between 0 and 3 mg/l, with a mean value around 1.5 mg/l, corresponding to samples
widely distributed in the catchment; and a second one group with fluoride contents between 3 and 6 mg/l, corresponding to
a smaller area in the central-west border. Two different sources are proposed. Volcanic glass dissolution is responsible for
dominant values in the catchment, while the weathering of biotite from the Paleozoic bedrock can be assumed to account for
the higher concentrations in the second group. 相似文献
827.
Oswaldo Eduardo Ramos Ramos Luis Fernando Cáceres Mauricio Rodolfo Ormachea Muñoz Prosun Bhattacharya Israel Quino Jorge Quintanilla Ondra Sracek Roger Thunvik Jochen Bundschuh Maria Eugenia García 《Environmental Earth Sciences》2012,66(3):793-807
Water management in semiarid and arid catchments such as the Poopó Lake Basin requires improved understanding of the complex behavior of the various contaminants, which affect the drinking water quality and considered as crucial for sustainable development of the region. Mechanisms of arsenic (As) release in the surface and groundwater were studied. Hydrochemical data for surface water (4 samples) and groundwater (28 samples) were collected in a small watershed in the Poopó catchment at the highland of the Bolivian Andes (Altiplano). All of them show high electrical conductivity values and moderately oxidizing conditions. The surface water contains high concentration of sulfate and the trace elements As, Zn and Pb in the zone affected by acid mine drainage. There is a large variability of the concentration of As and of the trace elements in the groundwater in the five different regions within the Poopó catchment. The metal concentrations sensitive to changes of redox state and results of speciation modeling suggest that As (V) is a predominant aqueous species, which conforms to the prevailing oxidizing conditions in the shallow groundwater environment. Two generalized trends for As distribution were identified in groundwater: (a) high concentrations are found in the arid zone (100–250 μg/L) in the southern (region III) and in the northwestern (region V) regions, and (b) low concentrations (<50 μg/L) are found in the remaining part of the basin (region I, II and IV). However, the spatial distribution within these regions needs to be investigated further. A conclusion from the present study is that there are multiple sources of As as well as other trace elements (such as Cd, Mn and Zn) in the Poopó Lake Basin. Among the sources and the processes which led to the mobility of As and other trace metals in the region are: (a) weathering of sulfide minerals, (b) oxidation of pyrite and/or arsenopyrite in mineralized areas and (c) desorption from hydrous ferric oxide (HFO) surfaces. In non-mining areas, volcanic ash is suggested to be a significant source of As. 相似文献
828.
Groundwater flow model, recharge estimation and sustainability in an arid region of Patagonia, Argentina 总被引:2,自引:2,他引:0
María del Pilar Alvarez María Marta Trovatto Mario Alberto Hernández Nilda González 《Environmental Earth Sciences》2012,66(7):2097-2108
The Península Valdés, in northeastern Patagonia, Argentina, is characterised by its arid climate and the lack of perennial watercourses; thus, all economic activities depend on the groundwater resources. Water demand is mainly associated with tourism, which is centralised in Puerto Pirámides and supplied by a water desalination plant, and to sheep farming, supplied by the local aquifer. Due to the exponential growth of tourism, the government is planning to exploit groundwater and convey it by aqueduct to the abovementioned locality. The objectives of this study were to corroborate the conceptual geohydrological model, to develop a mathematical model to simulate the response of the aquifer to different scenarios, and to assess the incidence of water input into the system as a variable—a function that poses difficulties in the models for arid regions. The Visual Modflow 4.1 code was used, calibrating it in trial-and-error mode, changing the recharge and hydraulic conductivity parameters with different variants in the recharge zone and in the inclusion or exclusion of the evapotranspiration module. Results indicate the importance of the recharge analysis by treating rainfall at daily time steps. The adjusted model was exposed to four scenarios with variations in water input and in output by pumping. It can be concluded that under different input conditions, but with a controlled extraction, the system responds in a sustainable manner. 相似文献
829.
The ionosphere: effects,GPS modeling and the benefits for space geodetic techniques 总被引:12,自引:8,他引:4
Manuel Hernández-Pajares J. Miguel Juan Jaume Sanz Àngela Aragón-Àngel Alberto García-Rigo Dagoberto Salazar Miquel Escudero 《Journal of Geodesy》2011,85(12):887-907
The main goal of this paper is to provide a summary of our current knowledge of the ionosphere as it relates to space geodetic
techniques, especially the most informative technology, global navigation satellite systems (GNSS), specifically the fully
deployed and operational global positioning system (GPS). As such, the main relevant modeling points are discussed, and the
corresponding results of ionospheric monitoring are related, which were mostly computed using GPS data and based on the direct
experience of the authors. We address various phenomena such as horizontal and vertical ionospheric morphology in quiet conditions,
traveling ionospheric disturbances, solar flares, ionospheric storms and scintillation. Finally, we also tackle the question
of how improved knowledge of ionospheric conditions, especially in terms of an accurate understanding of the distribution
of free electrons, can improve space geodetic techniques at different levels, such as higher-order ionospheric effects, precise
GNSS navigation, single-antenna GNSS orientation and real-time GNSS meteorology. 相似文献
830.
Pérez-López R Nieto JM López-Cascajosa MJ Díaz-Blanco MJ Sarmiento AM Oliveira V Sánchez-Rodas D 《Marine pollution bulletin》2011,62(2):405-411
This study reports the annual amount of heavy metals discharged by industrial activity into the estuary of the Ría of Huelva (SW Spain). The findings showed that the discharged metals found in highest amounts were Fe (11 t y−1), Zn (3.4 t y−1) and Mo (0.88 t y−1). There were other metals with high pollutant charge, such as Ti (232 kg y−1), As (228 kg y−1), Ni (195 kg y−1), Pb (100 kg y−1), Cr (39 kg y−1) and Cd (33 kg y−1). These results were compared with pollutants transported via the Tinto and Odiel rivers from abandoned mining activities in the Iberian Pyrite Belt (IPB), and it was deduced that the amounts spilled exclusively by industries were less than 1% in relation to the total discharge. Hence, the treatment of residues from the IPB should be the priority goal to improve water quality in the estuary. 相似文献