Influence of the natural organic matter in the removal of caffeine from water by fixed-bed column adsorption     

S. Álvarez-Torrellas  J. L. Sotelo  A. Rodríguez  G. Ovejero  J. García 《International Journal of Environmental Science and Technology》2017,14(4):833-840

The removal of caffeine from tap water by F-400 granular activated carbon in fixed-bed adsorption experiments was carried out. Textural and chemical characterization of the adsorbent through N₂ adsorption–desorption isotherms, Fourier transform infrared spectrometry, isoelectric point determination and scanning electron microscopy studies was developed in studies previously reported. Caffeine breakthrough curves and total organic carbon profiles at different operation conditions (inlet concentration, volumetric flow rate and mass of adsorbent) were obtained. These experimental results showed a displacement of the natural organic matter from the active sites exerted by caffeine molecules due to their higher affinity to the surface carbon. This behavior led to an overshooting, a local outlet natural organic matter concentration higher than the feed quantity. A competitive effect seems to be observed in the removal of the target compound, decreasing the efficiency of the process. Axial dispersion coefficients and dimensionless numbers were estimated for the caffeine removal onto F-400 activated carbon. Therefore, the regeneration of the adsorbent by adsorption–desorption cycles was studied.  相似文献   

Metallophilic fungi research: an alternative for its use in the bioremediation of hexavalent chromium     

M. A. García-Hernández  J. F. Villarreal-Chiu  M. T. Garza-González 《International Journal of Environmental Science and Technology》2017,14(9):2023-2038

Contamination by hexavalent chromium has had a large impact on modern society and human health. This problem is a consequence of its great industrial applicability to several products and processes. Short-term exposure to hexavalent chromium can cause irritation, ulceration in skin and stomach and in addition to cancer, dermatitis, and damage to liver, renal circulation and nervous tissues, with even death being observed in response to long-term exposures. Many techniques have been used for the remediation of this pollutant, including physical and chemical approaches and, in more recent years, biological methods. Filamentous fungi isolated from contaminated sites exhibit a significant tolerance to heavy metal; hence, they are an important source of microbiota capable of eliminating hexavalent chromium from the environment. However, these microorganisms can do so in different ways, including biosorption, bioreduction, and bioaccumulation, among others. In this review, we explore several of the most documented mechanisms that have been described for fungi/hexavalent chromium interactions and their potential use in bioremediation.  相似文献   

Aftershock seismic assessment taking into account postmainshock residual drifts          下载免费PDF全文

Jorge Ruiz‐García  Julio D. Aguilar 《地震工程与结构动力学》2015,44(9):1391-1407

This paper introduces and evaluates a methodology for the aftershock seismic assessment of buildings taking explicitly into account residual drift demands after the mainshock (i.e., postmainshock residual interstory drifts, RIDR_o). The methodology is applied to a testbed four‐story steel moment‐resisting building designed with modern seismic design provisions when subjected to a set of near‐fault mainshock–aftershock seismic sequences that induce five levels of RIDR_o. Once the postmainshock residual drift is induced to the building model, a postmainshock incremental dynamic analysis is performed under each aftershock to obtain its collapse capacity and its capacity associated to demolition (i.e., the capacity to reach or exceed a 2% residual drift). The effect of additional sources of stiffness and strength (i.e., interior gravity frames and slab contribution) and the polarity of the aftershocks are examined in this study. Results of this investigation show that the collapse potential under aftershocks strongly depends on the modeling approach (i.e., the aftershock collapse potential is modified when additional sources of lateral stiffness and strength are included in the analytical model). Furthermore, it is demonstrated that the aftershock capacity associated to demolition (i.e., the aftershock collapse capacity associated to a residual interstory drift that leads to an imminent demolition) is lower than that of the aftershock collapse capacity, which mean that this parameter should be a better measure of the building residual capacity against aftershocks. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Fire severity and surface rock fragments cause patchy distribution of soil water repellency and infiltration rates after burning   总被引：3，自引：0，他引：3       下载免费PDF全文

Ángel J. Gordillo‐Rivero  Jorge García‐Moreno  Antonio Jordán  Lorena M. Zavala  Fernando M. Granja‐Martins 《水文研究》2014,28(24):5832-5843

Although fire‐induced soil water repellency (SWR) and its effects on soil hydrology and geomorphology have been studied in detail, very few studies have considered the effect of rock fragments resting on the soil surface or partly embedded in soil. In this research, we have studied the effect of rock fragments on the strength and spatial distribution of fire‐induced SWR at different fire severities. A fire‐affected area was selected for this experiment and classified into different zones according to fire severity (unburned, low, moderate and high) and rock fragment cover (low, <20% and high, >60%). During 7 days after fire, SWR and infiltration rates were assessed in the soil surface covered by individual rock fragments and in the midpoint between two adjacent rock fragments (with maximum spacing of 20 cm). SWR increased with fire severity. Rock fragments resting on the soil surface increased the heterogeneity of the spatial distribution of fire‐induced SWR. SWR increased significantly with rock fragment cover in bare areas under moderate and high fire severity, but quantitatively important changes were only observed under high fire severity. In areas with a low rock fragment cover, water repellency from soil surfaces covered by rock fragments increased relative to bare soil surfaces, with increasing SWR. In areas with a high rock fragment cover, SWR increased significantly from non‐covered to covered soil surfaces only after low‐severity burning. Rock fragment cover did not affect infiltration rates, although it decreased significantly in soil surfaces after high‐severity burning in areas under low and high rock fragment cover. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Experimental modelling of flocculation processes-the case of Paraiba do Sul Estuary     

Alfredo TRENTO  Susana VINZN 《国际泥沙研究》2014,29(3):378-390

The aggregation dynamics of fine sediments was analysed through laboratory tests using Couette and disk flocculators.It was shown that floc sizes tend to increase as concentrations grow both in fresh and salt water,in agreement with the aggregation theory,and that equilibrium diameters are slightly greater in salt environments for flocs developed either under shear stress or by differential sedimentation.Their transport and the aggregation processes were preliminarily studied in the estuary of the Paraiba do Sul River using a particle tracking model and field data.The floc breakup process by shear stress was included in the model.Yield stresses,which were determined by fractal dimensions and differential density,were accounted for.After the calibration of the collision efficiency coefficients,the numerical model was able to predict floc sizes comparable with those measured at the Paraiba do Sul estuary,which,in turn,were similar to those obtained during the laboratory experiments in the Couette flocculator.  相似文献   

Local site effect microzonation of Lorca town (SE Spain)   总被引：1，自引：0，他引：1  

M. Navarro  A. García-Jerez  F. J. Alcalá  F. Vidal  T. Enomoto 《Bulletin of Earthquake Engineering》2014,12(5):1933-1959

Local site effect assessment based on subsurface ground conditions is often the key to evaluate urban seismic hazard. The site effect evaluation in Lorca town (south-eastern Spain) started with a classification of urban geology through the geological mapping at scale 1:10,000 and the use of geotechnical data and geophysical surveys. The 17 geological formations identified were classified into 5 geological/seismic formations according to their seismic amplification capacity obtained from ambient vibration measurements as well as from simultaneous strong motion records. The shear-wave velocity structure of each geological/seismic formation was evaluated by means of inversion of Rayleigh wave dispersion data obtained from vertical-component array records of ambient noise. Nakamura’s method was applied to determine a predominant period distribution map. The spectral amplification factors were fourfold the values recorded in a reference hard-rock site. Finally, the capability of this study for explaining the damage distribution caused by the May 11th, 2011 Lorca destructive earthquake (Mw \(=\) 5.2) was examined. The methods used in this work are of assistance to evaluate ground amplification phenomena in urban areas of complex geology as Lorca town due to future earthquakes with applicability on urban seismic risk management.  相似文献   

Slope instabilities triggered by the 11th May 2011 Lorca earthquake (Murcia,Spain): comparison to previous hazard assessments and proposition of a new hazard map and probability of failure equation     

Martín Jesús Rodríguez-Peces  Julián García-Mayordomo  José Jesús Martínez-Díaz 《Bulletin of Earthquake Engineering》2014,12(5):1961-1976

The Lorca Basin has been the object of recent research aimed at studying the phenomena of earthquake-induced landslides and its assessment in the frame of different seismic scenarios. However, it has not been until the 11th May 2011 Lorca earthquakes when it has been possible to conduct a systematic approach to the problem. In this paper we present an inventory of slope instabilities triggered by the Lorca earthquakes which comprises more than 100 cases, mainly rock and soil falls of small size (1–100  \(\hbox {m}^{3}\) ). The distribution of these instabilities is here compared to two different earthquake-triggered landslide hazard maps: one considering the occurrence of the most probable earthquake for a 475-years return period in the Lorca Basin \((\hbox {M}_{\mathrm{w}}=5.0)\) based on both low- and high-resolution digital elevation model (DEM); and a second one matching the occurrence of the \(\hbox {M}_{\mathrm{w}}=5.2\) 2011 Lorca earthquake, which was performed using the higher resolution DEM. The most frequent Newmark displacements related to the slope failures triggered by the 2011 Lorca earthquakes are lower than 2 cm in both the hazard scenarios considered. Additionally, the predicted Newmark displacements were correlated to the inventory of slope instabilities to develop a probability of failure equation. The fit seems to be very good since most of the mapped slope failures are located on the higher probability areas. The probability of slope failure in the Lorca Basin for a seismic event similar to the \(\hbox {M}_{\mathrm{w}}\) 5.2 2011 Lorca earthquake can be considered as very low (0–4 %).  相似文献   

Deep-sea Fe-Mn Crusts from the Northeast Atlantic Ocean: Composition and Resource Considerations     

Susana Bolhão Muiños  James R. Hein  Martin Frank  José Hipólito Monteiro  Luís Gaspar  Tracey Conrad 《Marine Georesources & Geotechnology》2013,31(1):40-70

Eighteen deep-sea ferromanganese crusts (Fe-Mn crusts) from 10 seamounts in the northeast Atlantic were studied. Samples were recovered from water depths of ～1,200 to ～4,600 m from seamounts near Madeira, the Canary and Azores islands, and one sample from the western Mediterranean Sea.

The mineralogical and chemical compositions of the samples indicate that the crusts are typical continental margin, hydrogenetic Fe-Mn crusts. The Fe-Mn crusts exhibit a Co + Cu + Ni maximum of 0.96 wt%. Platinum-group element contents analyzed for five samples showed Pt contents from 153 to 512 ppb.

The resource potential of Fe-Mn crusts within and adjacent to the Portuguese Exclusive Economic Zone (EEZ) is evaluated to be comparable to that of crusts in the central Pacific, indicating that these Atlantic deposits may be an important future resource.  相似文献   

Benthic recovery after fish farming cessation: a "beyond-BACI" approach     

Aguado-Giménez F  Piedecausa MA  Gutiérrez JM  García-Charton JA  Belmonte A  García-García B 《Marine pollution bulletin》2012,64(4):729-738

The development of a benthic environment after fish-farming cessation was examined. To ascertain whether recovery occurred, several abiotic (granulometry, acid-volatile sulfides, total phosphorus and redox potential) and biotic (polychaete abundance) variables were monitored using a "beyond-BACI" approach. Before the cessation of farming, the geochemical conditions and polychaete assemblages differed among the impacted and control sites. After cessation, an improvement of the geochemical conditions was achieved. A significant tendency toward a recovery of the polychaete assemblage in the impacted area was observed, but significant differences still remained compared with the control sites. The acid-volatile sulfide level was responsible for these differences. The abundance of polychaete families associated with organically enriched sediments diminished at the impacted site after cessation, whereas the abundance of some sensitive and omnivorous families increased. The "beyond-BACI" approach provided a wider framework than other approaches, enabling us to differentiate the natural variability from those changes induced by the fish farm and farming cessation.  相似文献   

Stephen Edward Coleman (1966–2012)     

Mustafa Altinakar  Rob Ettema  Marcelo García  Bruce Melville  Vladimir Nikora  Gary Parker 《Acta Geophysica》2012,60(6):1500-1501

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