Contaminated soils and sediments associated with Zn ore metallurgy near the São Francisco River,Minas Gerais (Brazil)

Draining through industrial areas of the Minas Gerais mining state (Brazil), some tributaries of the São Francisco River constitute a potential environmental hazard for this great river and threaten the quality of the regional soils for agriculture and other activities. Extensive geochemistry and mineralogy of sediments, soils and alluvial plains from six selected areas within the Consciência drainage basin close to an important Zn-extraction plant, have been carried out. In this report, detailed mineralogy of those samples and supporting geochemical data are discussed, taking into account their specific climactic and environmental context. Petrographic and electron microprobe characterization of the sand-grained fraction of these materials was complemented by XRD on their finer fraction: the main contaminant minerals are willemite (one of the Zn ores used in the industrial plant) and jarosite, though their contents are quite variable in the studied areas and also with depth; minor amounts of Zn-, Pb-, Cd-, and Mn-bearing mineral phases are also frequent, usually as inclusions in willemite or in polycrystalline clasts, or adsorbed on the finer materials, such as clay minerals and associated Fe-hydroxides. Mineralogical contamination is responsible for high metal contents in the soils and sediments of the areas closer to the plant (e.g. Zn ? 2000 mg kg^?1 and Cd ? 20 mg kg^?1, which are the Intervention Values for Industrial Areas) and the greatest contamination risks are related to the more labile phases that circulate throughout the alluvial plains, the shallow sediments and the stream bed. Monitoring the mineral/chemical contamination and its extent also constitutes a useful basis for future proposals to remediate and recover this industrial area in order to decrease medium- and long-term negative impacts of metal contamination on the local and downstream environments.     

Point-source inertial particle dispersion

The dispersion of inertial particles continuously emitted from a point source is analytically investigated in the limit of small but finite inertia. Our focus is on the evolution equation of the particle joint probability density function p(x,?v,?t), x and v being the particle position and velocity, respectively. For arbitrary inertia, position and velocity variables are coupled, with the result that p(x,?v,?t) can be determined by solving a partial differential equation in a 2d-dimensional space, d being the physical-space dimensionality. For small (but nevertheless finite) inertia, (x,?v)-variables decouple and the determination of p(x,?v,?t) is reduced to solve a system of two standard forced advection–diffusion equations in the space variables x. The latter equations are derived here from first principles, i.e., from the well-known Lagrangian evolution equations for position and particle velocity.     

Methods for Evaluation of Geodetic Data and Seismicity Developed with Numerical Simulations: Review and Applications

In this work we review the development of both established and innovative analytical techniques using numerical simulations of the southern California fault system and demonstrate the viability of these methods with examples using actual data. The ultimate goal of these methods is to better understand how the surface of the Earth is changing on both long-and short-term time scales, and to use the resulting information to learn about the internal processes in the underlying crust and to predict future changes in the deformation and stress field. Three examples of the analysis and visualization techniques are discussed in this paper and include the Karhunen-Loeve (KL) decomposition technique, local Ginsberg criteria (LGC) analysis, and phase dynamical probability change (PDPC). Examples of the potential results from these methods are provided through their application to data from the Southern California Integrated GPS Network (SCIGN), historic seismicity data, and simulated InSAR data, respectively. These analyses, coupled with advances in modeling and simulation, will provide the capability to track changes in deformation and stress through time, and to relate these to the development of space-time correlations and patterns.     

A Second-Order Approach for P-Wave Elastic Impedance Technology

Previous formulation for P-wave elastic impedance (EI) technology considers only first-order effects in isotropic reflectivity. In this paper, Wang's pseudo-quadratic approximation for PP-wave reflection (R_PP) coefficients is used, in order to incorporate nonlinear effects into EI equation. In comparison with coefficients computed with the conventional linear approximation, Wang's pseudo-quadratic formula shows higher accuracy at far incidence. A further nonlinear component in the intermediate region of incidence is responsible for the high accuracy achieved with the pseudo-quadratic Rpp coefficient formula. By applying the same procedures of previous linear formulation to Wang's pseudo-quadratic Rpp coefficient, a second-order approach for EI equation is obtained. This novel approach is formed by multiplication of two terms. The first term represents the previous linear approach for EI equation. As for the second term, it is interpreted as the correction of first-order EI formula to second-order effects. As expected, specialization of the second-order EI equation to normal incidence results in the well-known acoustic impedance (AI). Assumption of invariability in fundamental elastic properties leads to simplification of mathematical procedures. However, high contrasts possibly found within the log window under investigation may corrupt the computation of EI logs by introducing numerical errors. Although two procedures are proposed to cope with numerical errors, modeling shows that the second-order approach for EI is robust enough to handle high contrasts in elastic parameters. Actual well logs are used to verify performance of the novel EI equation in reproducing the amplitude-versus-offset (AVO) response of a mature, oil-bearing sandstone resevoir. As a result, influence of nonlinear effects, which are incorporated into EI equation, is observed on amplitudes and on frequency bandwidth of synthetic seismograms generated at a high angle of incidence. Further experiments with actual well data focus on crossplotting EI logs against fundamental elastic parameters. In terms of accuracy, the outcomes reveal that lithofacies classification can benefit from using the elaboration of EI technology derived in this work.