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

Carlos A. De Carvalho Filho  Rubens M. Moreira  Otavio E. A. Branco  Pedro H. Dutra  Elizângela A. Dos Santos  Igor F. S. Moura  Peter M. Fleming  Helena E. L. Palmieri 《Environmental Earth Sciences》2017,76(24):830

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.  相似文献   

Characterization of a natural magnetite     

A. C. Doriguetto  N. G. Fernandes  A. I. C. Persiano  E. Nunes Filho  J. M. Grenèche  J. D. Fabris 《Physics and Chemistry of Minerals》2003,30(5):249-255

Single crystals of a rock magnetite were separated from steatite cobbles collected in a geological site near the city of Serro (18° 36′ 47′′ S 43° 22′ 46′′ W), Minas Gerais, Brazil. A typically well-shaped magnetite single crystal was characterized by chemical analysis, ⁵⁷Fe Mössbauer spectrometry at 300, 77 and 4 K and under an applied magnetic field of 6 T at 10 K, magnetization measurements and electronic microprobe. From Mössbauer data, the sample is stoichiometric with a tetrahedral and octahedral site occupancy ratio of 1:2. Elemental chemical analysis and point-to-point electron microscope probing show some inclusions of lamellar ilmenite (≤ 1 mass%) randomly distributed throughout the magnetite matrix, and also that the magnetite matrix is constituted only by Fe²⁺ and Fe³⁺, with no isomorphic substitution. Results are discussed on the basis of the magnetization curve and of the temperature dependence of the AC magnetic susceptibility. The Verwey transition occurs in the temperature range of 100–115 K, observed by a sudden change in the temperature dependence of the magnetization.  相似文献   

Managing Technological and Financial Uncertainty: A Decision Science Approach for Strategic Drilling Decisions     

Filho  Francisco Nepomuceno  Suslick  Saul B.  Walls  Michael R. 《Natural Resources Research》1999,8(3):193-203

This paper presents a framework to improve the quality of investment decisions in petroleum. The model presented enables the decision-maker to explicitly consider two major objectives when evaluating new petroleum opportunities—financial and technological gain. We utilize MultiAttribute Utility Theory (MAUT) to consider simultaneously the technological challenges of petroleum exploration into the capital budgeting process of an exploration and production firm. The MAUT methodology presented in this work demonstrates that in some mature areas the advantages to exploration are restricted further only to financial gain, based upon the present economic potential of the basin. On the other hand, other seemingly less attractive areas, such as deep horizons in deep-water basins, may represent attractive targets for new exploration as a result of the interaction of financial gain and technological advancement. This advantage reflects the technological gain as a key factor for future operations for oil discoveries in areas with big geological potential. The model presented in this work enables the decision-maker to consider explicitly the risk and rewards associated with both financial and technological payoffs, the decision-maker's tolerance for those types of risks, and the relative importance of each of those objectives in the context of ongoing petroleum exploration decisions.  相似文献   

Oxidative stress in the mussel Mytella guyanensis from polluted mangroves on Santa Catarina Island,Brazil     

Torres MA  Testa CP  Gáspari C  Masutti MB  Panitz CM  Curi-Pedrosa R  de Almeida EA  Di Mascio P  Filho DW 《Marine pollution bulletin》2002,44(9):923-932

Digestive glands of the mangrove mussel Mytella guyanensis, collected at one non-polluted site (site 1) and two polluted sites (sites 2 and 3), were analysed for different antioxidant defenses, lipid peroxidation and DNA damage. Thiobarbituric acid-reactive substance (TBARS) and 8-oxo-7,8-dihydro-2'-deoxyguanosine levels were enhanced at the polluted sites. With the exception of superoxide dismutase, the activities of catalase and glutathione peroxidase were also higher at the polluted sites. Greater increases were observed in glutathione reductase, glutathione S-transferase and etoxyresorufine-O-deethylase activities at the polluted sites. Conversely, reduced glutathione content was higher at the control site. Trace metal contents in mussels collected at polluted sites were increased compared to the control site, and there were strong positive correlations between TBARS and Cu and Pb contents. M. guyanensis is routinely exposed to an oxidative stress condition at both polluted sites, and considering xenobiotic bioaccumulation in bivalve molluscs, the mangrove mussel represents an excellent bioindicator for environmental monitoring studies.  相似文献   

Hot-fluid Driven Metasomatism of Samalpatti Carbonatites, South India: Evidence from Petrology, Mineral Chemistry, Trace Elements and Stable Isotope Compositions     

Rajesh K. Srivastava  Anand Mohan  Cesar Fonseca Ferreira Filho 《Gondwana Research》2005,8(1):77-85

The magmatic heritage of carbonatites can be identified on the basis of a combination of geological criteria such as, their mode of occurrence, the nature of associated igneous rocks, the presence of minerals of igneous origin, fenitization, characteristic trace element contents and isotopic composition. Late Proterozoic Samalpatti carbonatites were studied in view of these criteria, and were found to contain metamorphic minerals that normally form under thermal metamorphic conditions and which have unusual chemical compositions. A combination of criteria points clearly to a magmatic origin for these carbonatites. Field relations indicate that the dominant modes of intrusion of carbonatite into the encompassing pyroxenites and syenites include small dykes, veins, or lenses. The igneous nature of these carbonatites has been described elsewhere and chemically they are classified as calico-carbonatites. Currently, very little is known about the metamorphic textures and mineralogy observed in the Samalpatti carbonatites. In this study, several metamorphic minerals are reported including diopside, grossularite, vesuvianite, K-feldspar and wollastonite, and a hornfelsic texture is described. These mineral phases and texture characterize thermal metamorphism under low pressure and high temperature (LP-HT) metamorphic conditions (650°_750°C) or metasomatism aided by hot-fluid advection. The metamorphic nature of minerals reported is also confirmed by electron microprobe study. The Samalpatti carbonatite samples show much lower values of characteristic trace elements (P, Sr, Ba, Zr, Nb, Th, Y and REEs) than average concentrations for magmatic carbonatite. Stable isotopic (d¹³C and d¹⁸O) compositions of Samalpatti carbonatites do not fall in the primary igneous carbonatite (PIC) domain. The petrological and chemical signatures of these carbonatites suggest metasomatism in conjunction with fluid advection. Such a metasomatic process may drastically change the chemistry of the rocks in addition to enrichment of heavier stable isotopes. During this metasomatic process, characteristic elements would be dissolved in the high d¹⁸O fluid, and together with Rayleigh fractionation would contribute to enhanced concentrations of ¹³C and ¹⁸O in Samalpatti carbonatites.  相似文献   

Vulnerability to contamination by phosphorus in a zero-order basin with a high density of pigs and a history of slurry addition: extrapolation of an index     

Rafael da Rosa Couto  Luiz Carloz Pittol Martini  Luciano Colpo Gatiboni  Paulo Belli Filho  Sérgio Roberto Martins  Cleiton Junior Ribeiro Lazzari  Vilmar Müller Júnior  Jucinei José Comin  Paul John Anthony Withers  Ricardo Bergamo Schenato  Gustavo Brunetto 《Environmental Earth Sciences》2018,77(4):144

The application of phosphorus (P)-index methodology to assess the risk of water pollution from agriculture in river basins usually takes time and expends a great amount of resources. This study adapted the P-index methodology using digital mapping of key basin risk criteria for P loss in reference areas to evaluate the wider vulnerability to P loss in a zero-order basin with an intense concentration of pigs and with a history of pig slurry additions to the soil. The P content of eleven reference areas, where ten areas have received various applications of pig slurry and one area has no history of addition, was extrapolated to a zero-order basin using principal component analysis and analysis of hierarchical groupings. Estimated loss of soil and the distance between the P source and the watercourse were mapped using satellite images and in situ evaluations. The methodology of extrapolating was well correlated with a survey of P concentrations in land runoff and provides the potential to improve land management of those areas that are most vulnerable. Principal component analysis and hierarchical clustering analysis proved to be useful tools for the separation of areas with different slurry application times. Our results suggest that the P loss risk could be reduced through the adoption of soil conservation techniques such as reduced-tillage incorporating slurry and crop residue management to provide adequate soil protection, reduce the impact of raindrops and reduce erosion risk and transport of chemical pollutants to water bodies.  相似文献   

Effects of Explicit Urban-Canopy Representation on Local Circulations Above a Tropical Mega-City     

José L. Flores Rojas  Augusto J. Pereira Filho  Hugo A. Karam  Felipe Vemado  Valéry Masson 《Boundary-Layer Meteorology》2018,166(1):83-111

The Advanced Regional Prediction System (ARPS) is coupled with the tropical town energy budget (tTEB) scheme to analyze the effects of the urban canopy circulation over the metropolitan area of São Paulo and its interactions with the sea breeze and mountain-valley circulation in the eastern state of São Paulo, Brazil. Two experiments are carried out for the typical sea-breeze event occurring on 22 August 2014 under weak synoptic forcing and clear-sky conditions: (a) a control run with the default semi-desert surface parametrization and; (b) a tTEB run for the urban canopy of São Paulo. A realistic land-use database over the south-eastern domain of Brazil is used in the downscaling simulation to a horizontal grid resolution of 3 km. Our results indicate that ARPS effectively simulates features of the nighttime and early morning land-breeze circulation, which is affected by the surrounding hills and the nocturnal heat island of São Paulo. By early afternoon, the south-eastern sea-breeze circulation moves inland perpendicular to the upslope of the Serra do Mar scarp, which generates a line of moisture convergence and updrafts further inland. Later, the convergence line reaches São Paulo and interacts with the circulation arising from the urban heat island (UHI), which increases the moisture convergence and strength of updrafts. The surface energy balance indicates that the UHI is caused by large sensible heat storage within the urban canopy during the day, which is later released in the afternoon and at night. The simulations are verified with available radiosonde and surface weather station data, land-surface-temperature estimates from the moderate resolution imaging spectroradiometer, as well as the National Center for Atmospheric Research reanalysis databases. The three-dimensional geometry of the urban canyons within the tTEB scheme consistently improves the thermodynamically-induced circulation over São Paulo.  相似文献   

Synthetic scenario generation of monthly streamflows conditioned to the El Niño–Southern Oscillation: application to operation planning of hydrothermal systems     

Treistman  Felipe  Maceira  Maria Elvira Pi&#;eiro  Penna  D&#;bora Dias Jardim  Dam&#;zio  Jorge Machado  Rotunno Filho  Otto Corr&#;a 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(2):331-353

Stochastic Environmental Research and Risk Assessment - The Brazilian Interconnected Power System is hydro dominated and characterized by large reservoirs presenting multi-year regulation...  相似文献   

Development of a drought vulnerability index using MCDM and GIS: study case in São Paulo and Ceará, Brazil     

de Azevedo Reis  Gabriela  de Souza Filho  Francisco Assis  Nelson  Donald Robert  Rocha  Renan Vieira  da Silva  Samiria Maria Oliveira 《Natural Hazards》2020,104(2):1781-1799

Natural Hazards - Although climate change vulnerability research in general has increased over the last decade, Latin American countries have more directed more limited efforts toward vulnerability...  相似文献   

Apparent discrepancy in contamination history of a sub-tropical estuary evaluated through 210Pb profile and chronostratigraphical markers     

Marques AN  Monna F  da Silva Filho EV  Fernex FE  Fernando Lamego Simões Filho F 《Marine pollution bulletin》2006,52(5):532-539

Zn and Cd concentrations, stable lead isotopes and ²¹⁰Pb-derived chronology were determined in a sediment core sampled at Sepetiba Bay (South-eastern Brazil). During the last decades, the bay’s watershed has been modified by the increase of industrial activities and human interventions. In particular, Zn and Cd ore treatment plants were built near the coast in 1960 and 1970, respectively, and water has been diverted from the adjacent Paraíba do Sul River watershed since 1950. The core collected at shallow depth near the industrial area exhibits four successive events: (i) at 50 cm depth, a change in the ²⁰⁶Pb/²⁰⁷Pb ratio from about 1.162 to more than 1.18 might be the result of the São Francisco Channel opening and water diversion from Paraíba do Sul river; (ii) at 40 cm depth, Zn concentration starts to increase (up to 0.8 mg g⁻¹) (iii) above 30 cm depth, relatively high Cd concentrations (up to 1.6 μg g⁻¹) are observed and (iv) at 16 cm depth, change in unsupported ²¹⁰Pb slope is probably related to a waste dam built to prevent strong metal contamination in the bay. Sediment accumulation rates evaluated by Zn and Cd profiles used as time-markers are higher than those calculated from ²¹⁰Pb-based chronology models. Using the constant initial concentration (CIC) model both events are supposed to date back to about 1884 and 1902, respectively, while using the constant rate of supply (CRS) model it shifts to about 1925 and 1935. Such discrepancies are probably assigned to the fact that these models do not take into account site-specific local sedimentation dynamics. In the study area, particles deposition seems to be controlled by enrichment with unsupported ²¹⁰Pb transported by runoff from a mangrove flat bank. Chronology derived from a model that assumes an exponential increase of the initial ²¹⁰Pb activity fits well with the estimated rates obtained from historical events.  相似文献