Monte Carlo method applied to modeling copper transport in river sediments

Monte Carlo simulation (MCS) methodology has been applied to explain the variability of parameters for pollutant transport and fate modeling. In this study, the MCS method was used to evaluate the transport and fate of copper in the sediment of the Tibagi River sub-basin tributaries, Southern Brazil. The statistical distribution of the variables was described by a dataset obtained for copper concentration using sequential extraction, organic matter (OM) amount, and pH. The proposed stochastic spatial model for the copper transport in the river sediment was discussed and implemented by the MCS technique using the MatLab 7.3? mathematical software tool. In order to test some hypotheses, the sediment and the water column in the river ecosystem were considered as compartments. The proposed stochastic spatial model makes it possible to predict copper mobility and associated risks as a function of the organic matter input into aquatic systems. The metal mobility can increase with the OM posing a rising environmental risk.     

Geochemical Assessment of a Subtropical Reservoir: A Case Study in Curitiba,Southern Brazil

Suspended particles and dissolved substances in water provide reactive surfaces, influence metabolic activity and contribute to the net sediment deposition. It therefore plays an important part in the ecology and quality of the water mass. The water quality in reservoirs is crucial and it is naturally maintained by flushing and sedimentation, which continuously remove phosphorus from the water. In some reservoirs, however, these removal processes are countered by recycling of ions which could play a key role to start and/or maintain the eutrophic state. The combination of macro‐, trace‐ and microanalysis techniques can be useful to trace pollution sources through a chemical fingerprint, whether be during an acute environmental disaster or a long‐term release of pollutants. The water quality and total metal content of reservoir sediments were assessed in a reservoir, situated in the capital of the Paraná State, in the South‐Eastern part of Brazil. The goal of this paper was to determine the metal presence in the sediment and metal and ionic speciation in the Green River reservoir water. Water and bed sediment samples, collected from various sites during 2008 and 2009, were investigated using XRF, ICP‐OES, ICP‐MS, XRD and zeta potential measurements. Based on the results, the heavy metal concentration and chemical composition of the suspended matter in the water samples, as well as the sediment's chemical composition will be discussed.     

Dispersive Liquid–Liquid Microextraction for Preconcentration and Determination of Nickel in Water

A method for the determination of nickel in water was developed. The procedure involves preconcentration of nickel by using dispersive liquid–liquid microextraction. The Ni(II) ions were extracted in chloroform in the form of complex with the reagent 2‐(2′‐benzothiazolylazo)‐p‐cresol. Ethanol was used as the disperser solvent. After injection of the extracting mixture in a solution of nickel, a cloudy mixture was observed. A quick centrifugation induces phase separation and thus the settling of rich phase. The nickel content in the rich phase is measured by flame atomic absorption spectrometry. Under optimal conditions, the limit of detection and quantification obtained were 1.4 and 4.7 µg L^?1, respectively. Some parameters used to characterize preconcentration systems, such as enrichment factor and consumption index were calculated and resulted in 29 and 0.34 mL, respectively. After optimization of variables and determination of analytical characteristics, the method was used for the analysis of certified reference materials (BCR‐713: wastewater, effluent and BCR‐414: plankton) and real water samples.     

Predicting spectral features in galaxy spectra from broad-band photometry

We explore the prospects of predicting emission-line features present in galaxy spectra given broad-band photometry alone. There is a general consent that colours, and spectral features, most notably the 4000 Å break, can predict many properties of galaxies, including star formation rates and hence they could infer some of the line properties. We argue that these techniques have great prospects in helping us understand line emission in extragalactic objects and might speed up future galaxy redshift surveys if they are to target emission-line objects only. We use two independent methods, Artificial Neural Networks (based on the ANNz code) and Locally Weighted Regression (LWR), to retrieve correlations present in the colour N -dimensional space and to predict the equivalent widths present in the corresponding spectra. We also investigate how well it is possible to separate galaxies with and without lines from broad-band photometry only. We find, unsurprisingly, that recombination lines can be well predicted by galaxy colours. However, among collisional lines some can and some cannot be predicted well from galaxy colours alone, without any further redshift information. We also use our techniques to estimate how much information contained in spectral diagnostic diagrams can be recovered from broad-band photometry alone. We find that it is possible to classify active galactic nuclei and star formation objects relatively well using colours only. We suggest that this technique could be used to considerably improve redshift surveys such as the upcoming Fibre Multi Object Spectrograph (FMOS) survey and the planned Wide Field Multi Object Spectrograph (WFMOS) survey.     

Charmed meson pair production in high-energy pp collisions within the QCD color dipole approach

A study of double-charmed meson production in high-energy proton–proton collisions at the Large Hadron Collider is presented. Considering the color dipole formalism developed in the transverse momentum representation along with the double parton scattering mechanism, predictions are made for the transverse momentum differential cross section for different pairs of -mesons. The theoretical results cover the center-of-mass energy and forward rapidities available by the LHCb experiment. The proton–proton results considering different unintegrated gluon distributions are compared to the respective data collected at the LHC.     

Development of regional future climate change scenarios in South America using the Eta CPTEC/HadCM3 climate change projections: climatology and regional analyses for the Amazon, S?o Francisco and the Paraná River basins

The objective of this study is to assess the climate projections over South America using the Eta-CPTEC regional model driven by four members of an ensemble of the Met Office Hadley Centre Global Coupled climate model HadCM3. The global model ensemble was run over the twenty-first century according to the SRES A1B emissions scenario, but with each member having a different climate sensitivity. The four members selected to drive the Eta-CPTEC model span the sensitivity range in the global model ensemble. The Eta-CPTEC model nested in these lateral boundary conditions was configured with a 40-km grid size and was run over 1961–1990 to represent baseline climate, and 2011–2100 to simulate possible future changes. Results presented here focus on austral summer and winter climate of 2011–2040, 2041–2070 and 2071–2100 periods, for South America and for three major river basins in Brazil. Projections of changes in upper and low-level circulation and the mean sea level pressure (SLP) fields simulate a pattern of weakening of the tropical circulation and strengthening of the subtropical circulation, marked by intensification at the surface of the Chaco Low and the subtropical highs. Strong warming (4–6°C) of continental South America increases the temperature gradient between continental South America and the South Atlantic. This leads to stronger SLP gradients between continent and oceans, and to changes in moisture transport and rainfall. Large rainfall reductions are simulated in Amazonia and Northeast Brazil (reaching up to 40%), and rainfall increases around the northern coast of Peru and Ecuador and in southeastern South America, reaching up to 30% in northern Argentina. All changes are more intense after 2040. The Precipitation–Evaporation (P–E) difference in the A1B downscaled scenario suggest water deficits and river runoff reductions in the eastern Amazon and S?o Francisco Basin, making these regions susceptible to drier conditions and droughts in the future.     

U–Pb dating of granodiorite and granite units of the Los Pedroches batholith. Implications for geodynamic models of the southern Central Iberian Zone (Iberian Massif)

The first U–Pb geochronological results on the magmatic alignment of the Los Pedroches batholith are presented. The batholith is composed of a main granodioritic unit, several granite plutons and an important acid to basic dyke complex, all of them intrusive after the main Variscan regional deformation phase, D1, along the boundary between the Ossa-Morena and Central Iberian zones (SW Iberian Massif). Zircons from samples on both extremes of the granodiorite massif record nearly simultaneous magmatic crystallization at ca. 308 Ma, while the emplacement of granite plutons was diachronic between 314 and 304 Ma. The U–Pb results combined with new field and textural observations allow to better constrain the age of Variscan deformations D2 and D3 across the region, while the age of D1 remains imprecise. Transcurrent D2 shearing-tightening of D1 folds occurred around 314 Ma (lower Westphalian) in relation to the emplacement of the first granitic magmas. D3 faults and shear bands bearing a strong extensional component developed at ca. 308 Ma (upper Westphalian), associated to the intrusion of the main granodiorite pluton (granodiorite) of the batholith. Together with available geochemical and geophysical information, these results point to the Variscan reactivation of lithospheric fractures at the origin and subsequent emplacement of hybrid magmas within this sector of the Massif.     

Combined hydrochemical,isotopic, and multivariate statistics techniques to assess the effects of discharges from a uranium mine on water quality in neighboring streams

The Caldas Uranium Mine (CUM), located on the Poços de Caldas Plateau in the southeastern region of Brazil, is presently undergoing a decommissioning process. The aim of the present investigation is to identify and characterize the effects of acid mine drainage (AMD) originating from the CUM on surface water quality. To achieve these aims, sampling stations were located at two AMD sources: the retention pond at the foot of waste rock pile#4 (WRP#4) and the settling pond that receives effluents from the tailings dam (TD). Ten additional sampling stations were located along watercourses in the vicinity, both downstream and upstream of the mine. Sampling was performed during the rainy and dry seasons in 2010 and 2011. The water analysis detected significant changes in pH, electrical conductivity, F^?, Cd, U, Zn, Al, Mn, As, Ca, SO₄ ^2?, Pb, ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²³²Th, ²²⁸Ra, and Mo in waters downstream of both pond discharge sites. It was demonstrated that the disequilibrium between ²²⁶Ra and ²³⁸U can be used to trace the extent of AMD impacts in nearby streams. Variations in ¹⁸O and ²H enabled the flow of mining-impacted water to be traced from the ponds to nearby streams. Multivariate analysis yielded a three-factor model: Factor 1 was interpreted as being associated with AMD (from WRP#4) and Factor 2 with a Ca–Mo relationship associated with the chemical constitution of the ore and with the treatment of tailings wastes in the area (from TD); Factor 3 was interpreted as being associated with the natural influence of geogenic processes on water quality in the area. The results of this study provide a scientific basis for recommending appropriate remedial actions during mine decommissioning.     

The upper mixed layer during coastal upwelling events on the northern portugal shelf

The upper mixed layer (UML) depth obtained from temperature is very close to that from density:the maximum is about 15m. This indicates that temperature is a good indicator of mixed layer during measurements. When the surface heat flux is balanced by a cross-shore heat flux, the surface mixed layer depth obtained from the WM model (Weatherly and Martin, 1978),hPRT, is roughly the same as observed. The mixed layer depth calculated from the PWP model (Price, Weller and Pinkel, 1986) is close to the depth obtained from thermistor chain temperature data. The results show that both the WM model and PWP model can provide a good estimate of stratification in the study area during the cruise. The value of log( h/u3) is about 9.5 in the study area, which shows that the study area is strongly stratified in summer. Observations on the northern Portugal shelf reveal high variability in stability, giving rise to semi-diurnal, semi-monthly and diurnal oscillations, and long term variations. The fortnightly oscillatio