Aqueous heavy metals removal by adsorption on β-diketone-functionalized styrene–divinylbenzene copolymeric resin

An investigation was undertaken regarding the adsorption of different heavy metal ions from aqueous solutions using ??-diketone-functionalized styrene divinylbenzene resin under different experimental conditions such as initial concentration of metal ions, contact time, pH, and chelating capacity. The functionalization of resin was carried out by the condensation reaction of sodium salt of ??-diketones (pentane-1,3-dione) and chloromethylated styrene?Cdivinylbenzene resin in dichloromethane. Functionalized resin beads were characterized by Fourier transform infrared spectroscopy. The batch method was employed using different metal ions solution from 5 to 15?mg/L at different contact times. The adsorption kinetics was tested for the pseudo-first order, pseudo-second order reaction at different experimental conditions. The rate constant of adsorption kinetic models were also calculated and good correlation coefficient (R ²?>?0.9941) was obtained for pseudo-second order kinetic model. The maximum adsorption value obtain for lead (0.725728?mg/g), chromium (0.9199?mg/g), nickel (0.4974?mg/g), cobalt (0.6196?mg/g) and cadmium (0.6519?mg/g) at equilibrium condition, which shows that ??-diketone-functionalized styrene divinylbenzene resin is an effective adsorbent for toxic metal ions.     

Orthopyroxene-clinopyroxene equilibria in the system CaO-MgO-Al2O3-SiO2 (CMAS): new experimental results and implications for two-pyroxene thermometry

A new set of reversal experiments for coexisting ortho- and clinopyroxenes in the system CMAS at conditions between 1,000–1,570° C and 30 to 50 kb is presented and combined with literature data. Pyroxene behaviour, particularly that of clinopyroxene, is very complicated and different styles of Al incorporation into the pyroxene structure for low and high concentrations of Al are indicated, strongly influencing the exchange of the enstatite component between ortho- and clinopyroxene. Thermodynamic modelling of this exchange is problematic because of the large number of unknown coefficients compared to the number of experiments. Thermometry based on such models becomes very dependent on accuracy of experimental data and analyses of small quantities of elements. Despite this complexity very simple empirical thermometric equations are capable of reproducing experimental conditions in the systems CMS and CMAS over a wide range of P, T conditions. We derived the equation which gives a mean error of estimate of 25° C when applied to CMS and CMAS data.Abbreviations Used in the Text cpx clinopyroxene - di diopside, CaMgSi₂O₆ - en enstatite, Mg₂Si₂O₆ - opx orthopyroxene - px Pyroxene - py pyrope - a _i ^j activity of component i in phase j - activity coefficient - G _P,T (A) molar Gibbs free energy difference of reaction (A) at P, T - X _i ^j mole fraction of component i in phase j     

Upper temperature tolerances of exotic brackish-water mussel, Mytilopsis leucophaeata (Conrad): an experimental study

The dark false mussel, Mytilopsis leucophaeata is an important mussel colonising the brackish-water systems of temperate and subtropical regions. Of late it has earned notoriety as a biofouling species in industrial cooling water systems. However, there are no published data on the temperature tolerance of this species. This paper presents data on the upper temperature tolerance of this mussel from the view point of biofouling control using thermal methods. In addition to mortality, response of physiological activities such as oxygen consumption, filtration rate, foot activity and byssus thread production were also studied at temperatures varying from 5 to 35 degrees C. Experiments were also carried out to understand the effect of mussel size, breeding condition, nutritional status and acclimation conditions (temperature and salinity) on the mortality pattern. The physiological activities were significantly reduced at temperatures beyond 27.5 degrees C and ceased at 35 degrees C. In 20 mm size group mussels exposed to 37 degrees C, 50% mortality was observed after 85 min and 100% mortality after 113 min. The effect of mussel size on mortality at different temperatures was significant, with the larger size group mussels showing greater resistance. M. leucophaeata collected during the non-breeding season (December-April) were more tolerant to temperature than those collected during the breeding season (June-October). Nutritional status of the mussel had no significant influence on the thermal tolerance of the mussel: fed and starved (non-fed) mussels succumbed to temperature at comparable rates. The effect of acclimation temperature and acclimation salinity on M. leucophaeata mortality at different temperatures was significant. Survival time increased with increasing acclimation temperature and decreased with increasing salinity. In comparison with other co-occurring species such as Mytilus edulis and Dreissena polymorpha, M. leucophaeata appears to be more tolerant to high temperature stress.     

Simulation of earthquake ground motions using autoregressive moving average (ARMA) models

Parsimonious representations of recorded earthquake acceleration time series are obtained by fitting stationary autoregressive moving average models after a variance-stabilizing transformation. Simulated acceleration series are then constructed by generating realizations from the fitted stationary models and applying the reverse transformation. As demonstrated on three components of a typical series, the response spectra for the observed and simulated series show good agreement for periods of less than eight seconds. Further, the model parameters for the three components are very similar, suggesting a consistency which could be useful for identifying site-specific characteristics.     

Integration of remote sensing data into hydrological models for reservoir management

Abstract

The purpose of this paper is to present the methodology set up to derive catchment soil moisture from Earth Observation (EO) data using microwave spaceborne Synthetic Aperture Radar (SAR) images from ERS satellites and to study the improvements brought about by an assimilation of this information into hydrological models. The methodology used to derive EO data is based on the appropriate selection of land cover types for which the radar signal is mainly sensitive to soil moisture variations. Then a hydrological model is chosen, which can take advantage of the new information brought by remote sensing. The assimilation of soil moisture deduced from EO data into hydrological models is based principally on model parameter updating. The main assumption of this method is that the better the model simulates the current hydrological system, the better the following forecast will be. Another methodology used is a sequential one based on Kalman filtering. These methods have been put forward for use in the European AIMWATER project on the Seine catchment upstream of Paris (France) where dams are operated to alleviate floods in the Paris area.     

Taxila LBM: a parallel,modular lattice Boltzmann framework for simulating pore-scale flow in porous media

The lattice Boltzmann method is a popular tool for pore-scale simulation of flow. This is likely due to the ease of including complex geometries such as porous media and representing multiphase and multifluid flows. Many advancements, including multiple relaxation times, increased isotropy, and others have improved the accuracy and physical fidelity of the method. Additionally, the lattice Bolzmann method is computationally very efficient, thanks to the explicit nature of the algorithm and relatively large amount of local work. The combination of many algorithmic options and efficiency means that a software framework enabling the usage and comparison of these advancements on computers from laptops to large clusters has much to offer. In this paper, we introduce Taxila LBM, an open-source software framework for lattice Boltzmann simulations. We discuss the design of the framework and lay out the features available, including both methods in the literature and a few new enhancements which generalize methods to complex geometries. We discuss the trade-off of accuracy and performance in various methods, noting how the Taxila LBM makes it easy to perform these comparisons for real problems. And finally, we demonstrate a few common applications in pore-scale simulation, including the characterization of permeability of a Berea sandstone and analysis of multifluid flow in heterogenous micromodels.     

Chronology and organic chemistry of the Black Creek Swamp Megafauna site (Late Pleistocene), Kangaroo Island, Australia

The timing of the extinction of the Australian Megafauna and whether it was simultaneous and widespread has been a much researched topic in Quaternary geoscience. The Black Creek Swamp Megafauna site on Kangaroo Island was thought to be a refugium for Megafauna; however, recent and multidiscipline age determinations have established that the fossils are considerably older than the well-quoted extinction age of 45 kyr. Further radiocarbon age determinations, δ¹³C isotope analysis and ¹³C-NMR spectroscopy of the fossil containing organic matter demonstrates that it is highly soluble and accumulated as recently as 31–18 cal. kyr BP. These radiocarbon ages are much younger than the 100–50 kyr age bracket ascertained for the fossil material itself, implying separate episodes of death, deposition and burial. The soluble nature of the organic matter and increasing radiocarbon ages with depth suggests lateral accumulation, probably transported by subsurface waters from elevated areas proximal to the low-lying swamp. Such depositional conditions and ¹⁴C age range implies that the site may have experienced an unusually wet Last Glacial Maximum, due maybe to its proximity to the continental shelf and thus to maritime conditions. C3 vegetation dominates the Black Creek Swamp and its organic matter (δ¹³C; −30‰ and −23‰); however, variations in δ¹³C may indicate climatic shifts. ¹³C-enrichment and an abundance of salt-tolerant gastropods within the site's final phase of sediment accumulation (<6 cal. kyr BP) suggest that conditions during this most recent period were not as wet as those of the Last Glacial Maximum.     

Detecting infiltration and impacts of introduced water using strontium isotopes

Water introduced to surface drainages, such as agricultural and roadway runoff, mine drainage, or coalbed natural gas (CBNG)-produced water, potentially can be of environmental concern. In order to mitigate potential environmental effects, it may be important to be able to trace water discharged to the surface as it infiltrates and interacts with near-surface aquifers. We have chosen to study water withdrawn during CBNG production for isotope tracing in the hyporheic zone because it poses a variety of economic, environmental, and policy issues in the Rocky Mountain states. Ground water quality must be protected as CBNG water is added to semiarid ecosystems. Strontium (Sr) isotopes are effective fingerprints of the aquifer from which water originates. In this study, CBNG water was found to have a higher (87)Sr/(86)Sr ratio than the local alluvial aquifer water. This measurable difference allows the strontium isotope ratio and concentration to be used as tracers of CBNG water following its discharge to the surface. The dissolution and mobilization of salts from soil are an important contributor to ground water quality degradation. In the Powder River basin of Wyoming, the soils are calcium carbonate-buffered systems. The chemical similarity of strontium to calcium allows it to substitute into calcium minerals and enabled us to use strontium isotopes to identify calcium salts mobilized from the soil. Strontium isotopes are an effective monitor of the source of ions and the volume and direction of introduced water flow in the hyporheic zone.