Removal of Pyridine from Aqueous Solution by Adsorption on an Activated Carbon Cloth     

Pedro Alonso‐Davila  Oliva L. Torres‐Rivera  Roberto Leyva‐Ramos  Raul Ocampo‐Perez 《洁净——土壤、空气、水》2012,40(1):45-53

Pyridine is a very toxic pollutant that has to be removed from wastewater. In this work, adsorption of pyridine on activated carbon cloth (ACC) is studied as a possible alternative for eliminating pyridine from aqueous solution. The ACC was produced from polyacrylonitrile. The adsorption equilibrium data of pyridine on ACC was obtained in a batch adsorber. The experimental data was interpreted with the isotherms of Langmuir, Freundlich, and Prausnitz‐Radke (PR), and the PR isotherm better represented the experimental data. The capacity of ACC for adsorbing pyridine was favored increasing the solution pH from 3 to 6, and this effect was due to the π–π dispersive and electrostatic interactions between the pyridine species in solution and the surface complexes of ACC. The modified Langmuir model fitted reasonably well the influence of pH on the adsorption capacity. In this model was assumed that both neutral pyridine and pyridinium were simultaneously adsorbed on ACC accordingly to the experimental results. The adsorption capacity was almost independent of temperature. The reversibility study revealed that 75% of the pyridine can be desorbed from ACC indicating that part of the pyridine was irreversibly adsorbed, and possibly chemisorbed.  相似文献   

Coral communities and reefs from Guerrero,Southern Mexican Pacific     

Ramón A. López‐Pérez  Luis E. Calderón‐Aguilera  Héctor Reyes‐Bonilla  José D. Carriquiry  Pedro Medina‐Rosas  Amilcar L. Cupul‐Magaña  María D. Herrero‐Pérezrul  Héctor A. Hernández‐Ramírez  Miguel Á. Ahumada‐Sempoal  Betsabe M. Luna‐Salguero 《Marine Ecology》2012,33(4):407-416

Corals in the Eastern Pacific extend south from the Gulf of California to Ecuador and oceanic Chile, and west from Colombia to Clipperton Atoll. Nevertheless, large stretches of the Mexican Pacific remain fundamentally unstudied. Therefore, to assess the current conditions of coral communities, a coastal fringe ～300 km long (17°40′ N, 101°39′ W to 16°46′ N, 99°49′ W) was surveyed within the Southern Mexican Pacific, between 2005 and 2009. Fifteen stony coral species were identified at 13 coral communities and six Pocillopora‐dominated fringing reefs, with Pocillopora verrucosa and Pocillopora damicornis the primary contributing taxa. Reef development was identified in embayments or behind rocks or islands that offered shelter from northern and northwestern winds. Observations of Pocillopora effusus, Pocillopora inflata, Porites lobata, Pavona clavus, and Pavona varians expanded the species known geographic ranges by several degrees of latitude, suggesting reef building fauna comprised a mixture of widespread and relatively rare Eastern Pacific corals. Results indicated greater live coral cover in the Ixtapa‐Zihuatanejo area (15–73%) than in the Acapulco localities, which had high algal dominance; the reefs in the latter region exhibited high erosion. Regional differences are likely the result of long‐standing anthropogenic pressures around Acapulco since 1950, when it became an important tourist destination. This paper is the first detailed report of ecologically stressed corals and coral reefs from the state of Guerrero on the Mexican Southern Pacific coast.  相似文献   

Geomorphic monitoring and response to two dam removals: rivers Urumea and Leitzaran (Basque Country,Spain)          下载免费PDF全文

Askoa Ibisate  Alfredo Ollero  Daniel Ballarín  Jesús Horacio  Daniel Mora  Amaia Mesanza  Carles Ferrer‐Boix  Vanesa Acín  David Granado  Juan Pedro Martín‐Vide 《地球表面变化过程与地形》2016,41(15):2239-2255

Dam removal has been demonstrated to be one of the most frequent and effective fluvial restoration actions but at most dam removals, especially of small dams, there has been little geomorphological monitoring. The results of the geomorphological monitoring implemented in two dams in the rivers Urumea and Leitzaran (northern Spain) are presented. The one from the River Urumea, originally 3.5 m high and impounding 500 m of river course, was removed instantaneously whereas that in the River Leitzaran, 12.5 m high, and impounding 1500 m of river course, is in its second phase of a four‐stage removal process. Changes in channel morphology, sediment size and mobility and river bed morphologies were assessed. The monitoring included several different techniques: topographical measurements of the channel, terrestrial laser scanner measurements of river bed and bars, sediment grain size and transport; all of them repeated in four (May, August, November 2011 and May 2012) and five (July and September 2013, April and August 2014 and June 2015) fieldwork campaigns in the River Urumea and River Leitzaran, respectively. Geomorphic responses of both dam removals are presented, and compared. Morphological channel adjustments occurred mainly shortly after dam removals, but with differences among the one removed instantaneously, that was immediate, whereas that conducted by stages took longer. Degradational processes were observed upstream of both dams (up to 1.2 m and 4 m in the River Urumea and River Leitzaran, respectively), but also aggradational processes (pool filling), upstream of Inturia Dam (2.85 m at least). Less evident aggradational processes were observed downstream of the dams (up to 0.37 m and 0.50 m in the River Urumea and River Leitzaran, respectively). Flood events, especially a 100 year flood registered during the monitoring period of Mendaraz Dam removal, reactivated geomorphological processes as incision and bank erosion, whereas longitudinal profile recovery, grain‐size sorting and upstream erosion took longer. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Hydrostratigraphic framework and hydrogeological behaviour of the Mancha Oriental System (SE Spain)     

David Sanz  Juan José Gómez-Alday  Santiago Castaño  Angel Moratalla  Jorge De las Heras  Pedro Emilio Martínez-Alfaro 《Hydrogeology Journal》2009,17(6):1375-1391

The Mancha Oriental System (MOS) has a surface area of 7,260 km², making it one of the largest carbonate aquifer systems in Spain. The system sustains about 1,000 km² of irrigated crops and supplies groundwater to 275,000 inhabitants. The economic transformation brought about by the development of extensive irrigated cropland has led to a water-balance disequilibrium of about 75 million m³/year. This input–output deficit has negative consequences in the quantity and quality of the available resources, in the river–aquifer relationship, and in the associated ecosystems as well. To understand the hydrogeological behaviour of the system, it is necessary to design a conceptual model. Further, the conceptualisation of a groundwater flow system is a requirement of the European Water Framework Directive for the characterisation of groundwater bodies. The robustness of the conceptual model depends heavily on the user capability of representing the real system. In this work, a multidisciplinary approach has been used to represent the three-dimensional geological framework and the groundwater flow conceptualisation of the MOS. Data management and three-dimensional visualisation have been carried out by means of geographical information system (GIS) tools and software for contouring and three-dimensional surface mapping.  相似文献   

Experimental investigation on the seismic performance of masonry buildings using shaking table testing   总被引：1，自引：1，他引：0  

Paulo B. Lourenço  Leonardo Avila  Graça Vasconcelos  J.Pedro Pedro Alves  Nuno Mendes  Alfredo C. Costa 《Bulletin of Earthquake Engineering》2013,11(4):1157-1190

Masonry buildings worldwide exhibited severe damage and collapse in recent strong earthquake events. It is known that their brittle behavior, which is mainly due to the combination of low tensile strength, large mass and insufficient connection between structural elements, is the main limitation for their structural implementation in residential buildings. A new construction system for masonry buildings using concrete blocks units and trussed reinforcement is presented here and its seismic behavior is validated through shaking table tests. Dynamic tests of two geometrically identical two-story reduced scale (1:2) models have been carried out, considering artificial accelerograms compatible with the elastic response spectrum defined by the Eurocode 8. The first model was reinforced with the new proposed system while the second model was built with unreinforced masonry. The experimental analysis encompasses local and global parameters such as cracking patterns, failure mechanisms, and in-plane and out-of-plane behavior in terms of displacements and lateral drifts from where the global dynamic behavior of the two buildings is analyzed comparatively. Finally, behavior factors for the design recommendations in case of unreinforced masonry are also evaluated.  相似文献   

Paleo- and Neoproterozoic magmatic and tectonometamorphic evolution of the Isla Cristalina de Rivera (Nico Pérez Terrane, Uruguay)   总被引：1，自引：0，他引：1  

Pedro Oyhant?abal  Martin Wagner-Eimer  Klaus Wemmer  Bernhard Schulz  Robert Frei  Siegfried Siegesmund 《International Journal of Earth Sciences》2012,101(7):1745-1762

The Isla Cristalina de Rivera crystalline complex in northeastern Uruguay underwent a multistage magmatic and metamorphic evolution. Based on SHRIMP U–Pb zircon, Th–U–Pb monazite (CHIME-EPMA method) and K–Ar age data from key units several events can be recognized: (1) multistage magmatism at 2,171–2,114?Ma, recorded on zircon of the granulitic orthogneisses and their 2,093–2,077?Ma overgrowths; (2) a distinct amphibolite facies metamorphism at ~1,980?Ma, recorded by monazite; (3) greenschist facies reworking and shearing at ca. 606?Ma (monazite and K–Ar on muscovite) along the Rivera Shear Zone, and finally (4) intrusion of the post-tectonic Sobresaliente and Las Flores granites at around 585?Ma. Lithological similarities, geographic proximity and coeval magmatic and metamorphic events indicate a similar tectonometamorphic evolution for the Isla Cristalina de Rivera, the Valentines Block in Uruguay and the Santa María Chico Granulitic Complex in southern Brazil, since at least 2.1?Ga.  相似文献   

Comments on Lowe et al. “Otolith Microchemistry Reveals Substantial Use of Freshwater by Southern Flounder in the Northern Gulf of Mexico”     

Pedro?MoraisEmail author 《Estuaries and Coasts》2012,35(3):904-906

Lowe et al. (Estuaries and Coasts, 34:630–639, 2011) hypothesized that juvenile southern flounder Paralichthys lethostigma (Jordan and Gilbert 1884) would migrate from the Gulf of Mexico into the Mobile-Tensaw River Delta (AL, USA) and use low-salinity (oligohaline/freshwater) habitats during, at least, a portion of their first year of life. Thus, they analyzed the Sr/Ca ratio profiles along the sagittal otoliths of southern flounder collected in the Mobile-Tensaw River Delta and observed that one third of the flounders had low Sr/Ca levels in the otoliths’ core and throughout the otolith, suggesting that these fishes hatched in freshwater or low-salinity habitats where they spend the majority of their life. The other two thirds of southern flounder showed high levels of Sr/Ca ratio in the otoliths’ core following a marked decline of Sr/Ca ratio, which then maintained along the remainder of the otolith. This pattern was interpreted as larvae hatched in higher salinity waters before entering the Mobile-Tensaw River Delta; however, in this paper, I list several arguments to support an alternative interpretation for this pattern. I suggest that the high levels of Sr/Ca ratios in the otoliths’ core of southern flounder does not reflect the saline conditions where larvae hatched, instead it reflects the location where the female progenitor hydrated the eggs. Thus, adding my interpretation on the data of Lowe et al. (Estuaries and Coasts, 34:630–639, 2011), it seems that southern flounder might hatch in or near freshwater habitats and the migration of southern flounder into an estuarine ecosystem to spawn might exist.  相似文献   

Moisture transport and intraseasonal variability in the South America monsoon system   总被引：1，自引：0，他引：1  

Leila M. V. Carvalho  Ana E. Silva  Charles Jones  Brant Liebmann  Pedro L. Silva Dias  Humberto R. Rocha 《Climate Dynamics》2011,36(9-10):1865-1880

This paper examines moisture transport on intraseasonal timescales over the continent and over the South Atlantic convergence zone (SACZ) during the South America (SA) summer monsoon. Combined Empirical Orthogonal Function analysis (EOFc) of Global Precipitation Climatology Project pentad precipitation, specific humidity, air temperature, zonal and meridional winds at 850?hPa (NCEP/NCAR reanalysis) are performed to identify the large-scale variability of the South America monsoon system and the SACZ. The first EOFc was used as a large-scale index for the South American monsoon (LISAM), whereas the second EOFc characterized the SACZ. LISAM (SACZ) index showed spectral variance on 30?C90 (15?C20) days and were both band filtered (10?C100?days). Intraseasonal wet anomalies were defined when LISAM and SACZ anomalies were above the 75th percentile of their respective distribution. LISAM and SACZ wet events were examined independently of each other and when they occur simultaneously. LISAM wet events were observed with the amplification of wave activity in the Northern Hemisphere and the enhancement of northwesterly cross-equatorial moisture transport over tropical continental SA. Enhanced SACZ was observed with moisture transport from the extratropics of the Southern Hemisphere. Simultaneous LISAM and SACZ wet events are associated with cross-equatorial moisture transport along with moisture transport from Subtropical Southwestern Atlantic.  相似文献   

Ontogenic shifts in predatory roles involving two invasive species     

Pedro Manuel Anastácio  Emília Pereira Leite  Margarida Ferreira  Luís Vicente  Alexandra Marçal Correia 《Limnologica》2011,41(3):228-234

The red swamp crayfish, Procambarus clarkii, and the eastern mosquitofish, Gambusia holbrooki have been introduced worldwide, but the interactions between these invasive species are not well known. The effects of crayfish presence, crayfish size and water depth on the consumption of G. holbrooki by P. clarkii were analyzed, as were the effects of mosquitofish presence and water depth on the consumption of recently hatched crayfish (RHC) by mosquitofish. To better understand this subject we conducted aquaria and open air mesocosm experiments simulating a rice field section. Aquarium experiments showed that P. clarkii consumes G. holbrooki and that G. holbrooki consumes RHC. Adult crayfish size did not significantly affect the consumption of mosquitofish and water depth had no effect on the consumption of G. holbrooki by P. clarkii and vice versa. In the outdoor mesocosm experiments P. clarkii caused no statistically significant effect on G. holbrooki numbers or biomass when compared with controls without crayfish. In spite of this, the analysis of crayfish stomach contents clearly demonstrated that several G. holbrooki individuals were consumed, indicating that crayfish can profit from the presence of G. holbrooki. Results from our study suggest that in shallow pools there are strong interactions between the two invasive species since adult crayfish predate mosquitofish and mosquitofish predate recently hatched crayfish. Therefore, there are bidirectional trophic interactions between these invasive species which change depending on their relative size. We believe that these interactions should become more relevant in confined areas such as small shallow pools formed during the late summer and autumn.  相似文献   

Estrogen pollution in a highly productive ecosystem off central-south Chile     

Bertin A  Inostroza PA  Quiñones RA 《Marine pollution bulletin》2011,62(7):1530-1537

While the presence of steroid estrogens in the environment has become a major environmental and health concern, their occurrence in coastal sediments remains poorly characterized. In this study, we measured the levels of three natural (estrone, 17β-estradiol, estriol) and one synthetic (17α-ethinylestradiol) estrogens in 54 coastal sediment samples collected from nine locations off central-southern Chile. Steroid estrogens were found in every sample. Remarkably high levels of 17α-ethinylestradiol were detected, reaching up to 48.14 ng/g dry weight. As a result, the global estrogenic loads were estimated to be high at all sites. Interestingly, they were found to correlate with the size of human populations served by sewage plants. Our study indicates that 17α-ethinylestradiol may accumulate in coastal sediments. The possible impact of this highly potent synthetic estrogen on the biota of the marine ecosystem off central-south Chile and on human health remains an open question.  相似文献