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

Isabel Ribeiro da Costa  Rita Fonseca  Catarina Pinho  Alexandre Araújo  Luísa Catarina Martins  Nuno Dias  Ana Isabel Janeiro  Guilherme Freitas 《Environmental Earth Sciences》2018,77(5):202

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.  相似文献   

Paleoenvironmental reconstruction of a Late Quaternary lagoon system in southern Brazil (Jaguaruna region,Santa Catarina state) based on multi‐proxy analysis     

Paula Garcia Carvalho do Amaral  Paulo César Fonseca Giannini  Florence Sylvestre  Luiz Carlos Ruiz Pessenda 《第四纪科学杂志》2012,27(2):181-191

This paper provides a paleoenvironmental reconstruction of a Late Quaternary lagoon system in the Jaguaruna region of Santa Catarina state, southern Brazil. Integrated results of bulk sedimentary organic matter characterization (δ¹³C, δ¹⁵N and C/N), microfossil (pollen and diatom) and grain‐size analysis from three shallow cores (～2.5 m depth) allowed us to propose an evolving paleogeographic scenario in this coastal region for the last ca. 5500 cal a BP. The lagoonal system in this area was more extensive during the mid‐Holocene than today, with a gradual and continuous lagoon–sea disconnection until the present. We add to the debate regarding relative sea‐level (RSL) variations for the Brazilian coast during the Holocene and discuss the importance of sedimentary dynamics for interpreting changes in coastal ecosystems. The multi‐proxy analysis suggests that changes in coastal ecosystems could be directly related to local sedimentary processes, which are not necessarily linked to RSL fluctuations and/or to climatic variations. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Kaimal's isopleths from a closure model     

Osvaldo L. L. Moraes  Joao Goedert 《Boundary-Layer Meteorology》1988,45(1-2):83-92

Kaimal's isopleths for the spectra of the Kansas experiment are derived from a closure model built after Claussen's mechanisms for the spectral transfer of kinetic energy in a steady-state and horizontally homogeneous flow. The connection of the predicted three-dimensional spectrum with the measured one-dimensional one is accomplished via the additional assumption that turbulence in the Kansas experiment was basically isotropic.Partially financed by CAPES, FINEP and CNPq.On leave from Faculdade de Engenharia de Joinville, SC, Brazil.  相似文献   

Phosphorus dynamics in water and sediments in urbanized and non-urbanized rivers in Southern Brazil   总被引：1，自引：0，他引：1  

Pagliosa PR  Fonseca A  Bosquilha GE  Braga ES  Barbosa FA 《Marine pollution bulletin》2005,50(9):965-974

Phosphorus flux models show that the removal tends to be a common feature in polluted estuarine systems whereas the release of P to the adjacent coastal area occurs in pristine environments. This study analyzes the distribution of P in water and sediments along six rivers in the south coast of Brazil. Three rivers located inside protected areas were considered non-polluted and used as a control of urbanization. The other three, situated within urbanized areas, were considered as having highly elevated concentrations of P. Results showed a different behavior of P in water and sediments located in urbanized and non-urbanized areas. The concentrations of dissolved organic (P-org) and inorganic (P-inorg) phosphorus in water, and the total phosphorus (P-tot) and polyphosphate (P-poly) in sediments where higher in the urbanized rivers compared to the non-urbanized ones. Both P of punctual origin and of diffuse origin contributed to the maintenance of elevated concentrations and disturbed the natural fluxes along the polluted rivers. The minimum and maximum concentrations in urbanized areas varied from 0.39 to 12.45 (microM) for P-org and 0.00 to 5.92 (microM) for P-inorg in water, and in sediments from 89.90 to 808.16 (microM g(-1)) for P-tot and 0.00 to 76.51 (microM g(-1)) for P-poly. In non-urbanized areas concentrations in water varied from 0.22 to 1.20 (microM) for P-inorg and 4.43 to 5.56 (microM) for P-org, and in sediments from 45.91 to 652.26 (microM g(-1)) for P-tot and 0.00 to 8.61 (microM g(-1)) for P-poly. Using a hierarchical sampling design and a simple model of variation of P (K(d) model) it was possible to demonstrate that urbanized and non-urbanized estuaries may act as sinks or sources of P. The variation of P analysis in different points along each of the six rivers showed that release and removal areas may occur within a same river independently of its urbanization.  相似文献   

Reducing the Impact of Outliers in Ore Reserves Estimation   总被引：1，自引：0，他引：1  

Joao Felipe Costa 《Mathematical Geology》2003,35(3):323-345

Mining applications commonly faces surprising high values designated as outliers. These values impact dramatically statistical analysis and interpretation. A comprehensive analysis on the causes for the presence of unexpected high values was recommended. However, if an erroneous value was accepted as a part of the solution, some form of correction is recommended. A methodology based on the robust kriging (RoK) algorithm is proposed to be used in exploratory data analysis and also to deal with problems associated with the presence of outliers in the sample data set. The efficiency of RoK method as an interpolator is tested in different types of mineralizations. Importantly, the parent population from which the data was sampled is available, thus allowing direct quantitative assessment of the effectiveness of the estimation technique. The performance of the method is tested in the context of ore reserves estimation. RoK model is compared to models generated by ordinary kriging, median indicator kriging, and lognormal kriging. RoK proved to be more accurate and more precise than those methods reducing substantially the number of misclassified blocks.  相似文献   

Columnar joints in the Patino Formation sandstones, Eastern Paraguay： a dynamic interaction between dyke intrusion, quartz dissolution and cooling-induced fractures     

Victor Fernandez Velazquez Paulo Cesar Fonseca Giannini Claudio Riccomini Alethea Ernandes Martins Sallun Jorge Hachiro Celso de Barros Gomes 《《幕》》2008,31(3):302-308

The Patiho Formation sandstones, which crop out in Aregud neighborhood in Eastern Paraguay and show columnar joints near the contact zone with a nephelinite dyke, have as their main characteristics the high pro- portion of syntaxial quartz overgrowth and a porosity originated from different processes, initially by dissolu- tion and later by partial filling and fracturing. Features like the presence of floating grains in the syntaxial cement, the transitional interpenetrative contact between the silica-rich cement and grains as well as the intense fracture porosity are strong indications that the cement has been formed by dissolution and reprecipita- tion of quartz from the framework under the effect of thermal expansion followed by rapid contraction. The increase of the silica-rich cement towards the dyke in association with the orthogonal disposition of the columns relative to dyke walls are indicative that the igneous body may represent the main heat source for the interstitial aqueous solutions previously existing in the sediments. At macroscopic scale, the increasing of inter- nal tensions in the sandstones is responsible for the nucleation of polygons, leading to the individualization of prisms, which are interconnected by a system of joints, formed firstly on isotherm surfaces of low tem- perature and later on successive adjacent planes towards the dyke heat source.  相似文献   

New approaches to environmental monitoring: the use of ICT to explore volunteered geographic information   总被引：3，自引：0，他引：3  

Cristina Gouveia  Alexandra Fonseca 《GeoJournal》2008,72(3-4):185-197

Citizen participation in environmental monitoring is not a new idea. However, recent developments in information and communication technologies (ICT), such as the social web and the miniaturization of sensors, have created new opportunities to promote citizen participation in environmental monitoring. The analysis of existing citizen initiatives that use ICT tools, identified the need for a framework conceptualizing ways to increase the contribution of volunteered geographic data in environmental monitoring. Environmental Collaborative Monitoring Networks (ECMN) are proposed in this paper as a framework that combines the concepts of traditional environmental monitoring networks with the ideals of the open source movement. Such framework can guide the creation of fixed and mobile monitoring networks and is organized based on three building blocks: (1) Motivated Citizens; (2) Sensing Devices; and (3) Back-End Information Infrastructure. To illustrate the issues involved in the implementation of the building blocks of ECMN, the Senses@Watch project is presented, which explored the use of sensory data as a source of monitoring data.  相似文献   

Experimental investigation of a fast monohull in forced harmonic motions     

A. Marn  J. Ponce  N. Fonseca  C. Guedes Soares 《Applied Ocean Research》2004,26(6):241-255

The paper presents the results of an experimental investigation of added masses and damping coefficients of a model of a fast monohull. A model of 4.5 m length between perpendiculars was constructed of fiber glass reinforced plastic (FRP) with four segments connected by a backbone. The backbone was instrumented with load cells at the positions of the cuts. This configuration, combined with load cells measuring the force exerted by the forced motion actuators, made it possible to obtain the hydrodynamic coefficients for each of the four hull segments.

The investigation focused on the vertical motions. Thus, the experimental program included forced harmonic heave and pitch motions in calm water (no incident waves). Subtracting inertial and restoring forces from total measured forces, one obtained the hydrodynamic component, which then resulted in the hydrodynamic coefficients. The effects of steady forward speed on the radiation forces were investigated by conducting model tests at four forward speeds. Finally, nonlinear effects were assessed by conducting model tests for three amplitudes of forced heave and forced pitch motions.  相似文献   

Oxygen solubility and speciation in sulphide-rich mattes     

Raúl O.C. Fonseca  Ian H. Campbell  John D. Fitzgerald 《Geochimica et cosmochimica acta》2008,72(11):2619-2635

Sulphide-rich liquids are common in magmatic environments forming over a wide range of temperature, pressure, fO₂ and fS₂. They are economically important because they sequester valuable metals such as Cu, Ni, Au and Pt from silicate melts. The presence of accessory amounts of primary oxides associated with sulphide mineralisations is often ignored or unexplained. Experimental work has shown that large amounts of oxygen can dissolve into mattes at fO₂ typical of terrestrial environments. At the quartz-fayalite-magnetite fO₂ buffer, the molar fraction of O in the matte exceeds that of S, placing the composition of the matte to the magnetite side of the mss (monosulphide solid solution)-magnetite join in the Fe-S-O system. However, sulphides crystallise before magnetite in most sulphide mineralisations and are much more abundant. Moreover, the speciation of O in a matte is not well known. Here we report the results of an experimental study of the solubility of O in mattes as a function of fS₂, fO₂, temperature, and composition. We confirm previous observations that Ni and Cu have a negative effect on the solubility of O in mattes. We show evidence for the existence of FeSO as a structural constituent of mattes in the Fe-S-O system. We present a simple parameterisation of the amount of O dissolved in mattes under relevant geological conditions, and use this parameterisation to discuss mechanisms for the crystallisation of primary spinels associated with sulphides in the Kambalda massive sulphide deposit (Western Australia) and the Sudbury Igneous Complex (Ontario, Canada).  相似文献   

High efficacy on diclofenac removal by activated carbon produced from potato peel waste     

M. Bernardo  S. Rodrigues  N. Lapa  I. Matos  F. Lemos  M. K. S. Batista  A. P. Carvalho  I. Fonseca 《International Journal of Environmental Science and Technology》2016,13(8):1989-2000

In the present study, a novel porous carbon obtained by K₂CO₃ activation of potato peel waste under optimized conditions was applied for the first time as liquid-phase adsorbent of sodium diclofenac in parallel with a commercial activated carbon. The biomass-activated carbon presented an apparent surface area of 866 m² g^?1 and well-developed microporous structure with a large amount of ultramicropores. The obtained carbon presented leaching and ecotoxicological properties compatible with its safe application to aqueous medium. Kinetic data of laboratory-made and commercial sample were best fitted by the pseudo-second-order model. The commercial carbon presented higher uptake of diclofenac, but the biomass carbon presented the higher adsorption rate which was associated with its higher hydrophilic nature which favoured external mass transfer. Both adsorbents presented adsorption isotherms that were best fitted by Langmuir model. The biomass carbon and the commercial carbon presented adsorption monolayer capacities of 69 and 146 mg g^?1, and Langmuir constants of 0.38 and 1.02 L mg^?1, respectively. The better performance of the commercial sample was related to its slightly higher micropore volume, but the most remarkable effect was the competition of water molecules in the biomass carbon.  相似文献