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91.
Induced polarization,resistivity, and self-potential: a case history of contamination evaluation due to landfill leakage 总被引:2,自引:1,他引:1
José Domingos Faraco Gallas Fabio Taioli Walter Malagutti Filho 《Environmental Earth Sciences》2011,63(2):251-261
This article compares the efficiency of induced polarization (IP) and resistivity in characterizing a contamination plume
due to landfill leakage in a typical tropical environment. The resistivity survey revealed denser electrical current flow
that induced lower resistivity values due to the high ionic content. The increased ionic concentration diminished the distance
of the ionic charges close to the membrane, causing a decrease in the IP phenomena. In addition, the self-potential (SP) method
was used to characterize the preferential flow direction of the area. The SP method proved to be effective at determining
the flow direction; it is also fast and economical. In this study, the resistivity results were better correlated with the
presence of contamination (lower resistivity) than the IP (lower chargeability) data. 相似文献
92.
Ecological consideration of trace element contamination in sediment cores from Sundarban wetland,India 总被引:2,自引:1,他引:1
E. V. Silva Filho M. P. Jonathan M. Chatterjee S. K. Sarkar S. M. Sella A. Bhattacharya K. K. Satpathy 《Environmental Earth Sciences》2011,63(6):1213-1225
This article reports on the concentration of selected trace elements (Mn, Zn, Cr, Cu, Ba, As, B, V, and Hg) and major elements
(Fe and Al) from the intertidal sediment cores from Sundarban wetland, India. This is a typical meso-macrotidal estuarine
area affected by domestic and industrial activities located upstream. The overall concentrations range is low to moderate,
indicating the environmental conditions in the outfall zone (grain size, hydrodynamic regime, and confinement), which favors
the in situ accumulation of pollutants. The extent of contamination from trace elements in Sundarban core sediments is evaluated
through a two-pronged approach: (i) by determining the metal enrichment in the sediments through the calculation of Pollution
Load Index (PLI), Enrichment Factor (EF) and Index of Geoaccumulation (I
geo), and (ii) by defining a potential level of biological risk by the use of quality criteria such as Threshold Effect Level
(TEL) and Effects Range-Low (ERL) benchmarks. On the basis of the calculated indices, sediments are particularly enriched
with Cr, Cu, B, V, and As. Those enrichments seem to be due to the fine granulometry of the regions with Fe and Mn oxi-hydroxides
being the main metal carriers. Trace Elements input to the Sundarban wetland need to be kept under strict control in future
specially with reference to As since, according to TEL and ERL benchmarks, it already appears to be associated with a potential
biological risk. 相似文献
93.
A. Issa Filho A.B.R.M.D. Dos Santos B.F. Riffel F.E.V. Lapido-Loureiro I. McReath 《Journal of Geochemical Exploration》1991,40(1-3)
Using published data and the results of a new study, the main characteristics of seven Angolan carbonatite complexes are here presented. With the exception of the Lupongola complex which intrudes anorthosites, the remaining complexes are hosted by Precambrian silicic rocks. The complexes are of central or dike type and are well exposed. They represent some of the seven morpholithological types present in the province and have some intermediate lithochemical features between those of Brazilian and East African examples.Sovites at Lupongola are the richest in Sr and F, and also have the highest CaO/MgO and La/Y ratios of all sovites studied. Carbonatites from Bonga and Bailundo are the richest in P2O5, while those from Coola and Longonjo are the richest in BaO. Ferrocarbonatites from Bailundo and Virulundo have the highest REE contents. TiO2 contents are usually low. Only Bonga carbonatites show well-defined variation between Ba and Mn contents and the index CaO/(CaO+Fe2O3+FeO+MnO+MgO).The CO2-SiO2-(Al2O3+Na2O+K2O) diagram distinguishes silicified carbonatites, feldspar-bearing carbonatites in which the main silicate mineral is K-feldspar, carbonatites and fenites. Potassic fenitization of country rocks is well developed at Bailundo, Bonga and Virulundo, and probably it also affected cogenetic nepheline syenites at Tchivira and Monte Verde.Fluorcarbonates of Ca and REE are encountered in all chemical varieties of carbonatites, and crystallized during late stages of rock formation. They have a strong influence both on total REE contents and on the slopes of chondrite-normalized patterns. Fluorapatite and pyrochlore are other important potential REE host minerals in the rocks studied. The REE patterns usually have discrete negative Ce anomalies, and sometimes show very discrete negative Eu anomalies. Apart from these anomalies, some rocks have very near-linear patterns, but most show inflections, which may occur between light and middle, and between middle and heavy REE. The origins of these variations are still uncertain.Other aspects of rock geochemistry show that, while some features could be explained by crystal fractionation differentiation processes, late-stage or secondary chemical modifications were widespread. 相似文献
94.
Elfany Reis do Nascimento Lopes Carlos de Souza José Paixão de Sousa Jocy Ana Filho José Luiz Albuquerque Lourenço Roberto Wagner 《Water Resources》2021,48(1):29-40
Water Resources - The objective of this study is to develop an anthropic exposure indicator for river basins using quantitative and qualitative aspects of the landscape and morphometric analysis... 相似文献
95.
Daniel T. C. Yao Waldyr Lopes de Oliveira‐Filho Xiao‐Chuan Cai Dobroslav Znidarcic 《国际地质力学数值与分析法杂志》2002,26(2):139-161
The consolidation and desiccation behaviour of soft soils can be described by two time‐dependent non‐linear partial differential equations using the finite strain theory. Analytical solutions do not exist for these governing equations. In this paper, we develop efficient numerical methods and software for finding the numerical solutions. We introduce a semi‐implicit time integration scheme, and show numerically that our method converges. In addition, the numerical solution matches well with the experimental result. A boundary refinement method is also developed to improve the convergence and stability for the case of Neumann type boundary conditions. Interface governing equations are derived to maintain the continuity of consolidation and desiccation processes. This is useful because the soil column can undergo desiccation on top and consolidation on the bottom simultaneously. The numerical algorithms has been implemented into a computer program and the results have been verified with centrifuge test results conducted in our laboratory. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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100.
Land use changes due to energy policy as a determining factor for morphological processes in fluvial systems in São Paulo State,Brazil
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Cenira Maria Lupinacci Fabiano Tomazini da Conceição Adriano Luis Heck Simon Archimedes Perez Filho 《地球表面变化过程与地形》2017,42(14):2402-2413
The number of hydroelectric dams used for energy production and the cultivation of sugar cane crops for ethanol production have increased significantly in the southeastern region of Brazil. These land use/land cover changes (LULCC) associated with energy policy can affect landscape changes over a range of temporal and spatial scales. This article focuses on how human–landscape interactions have influenced geomorphological dynamics in the lower course of the Piracicaba River for two different scenarios that represent pre‐dam and post‐dam conditions in 1962 and 2007, respectively, and the expansion of sugar cane crops after 1975. This assessment was performed by mapping land use and geomorphological changes in the study area in the 1962 and 2007 scenarios, in addition to quantifying the sedimentation rates upstream from the Barra Bonita Reservoir using 210Pb. The main land uses identified for the 1962 scenario were pastures, meadows, annual crops and forests. However, the main land use change was the expansion of sugar cane cropland from 4 to 39%. In the 1962 scenario, the lower course of the Piracicaba River had a predominantly meandering pattern, and there were pronounced alluvial plains in the region. In the 2007 scenario, oxbow lakes were not mapped, and the river terraces were reduced in area due to construction of the Barra Bonita Reservoir. The changes in the sedimentation rates indicate an association between the construction of the Barra Bonita Reservoir and the expansion of sugar cane crops. It was therefore not possible to assess the specific influences of each anthropogenic change on the sedimentation processes, reinforcing that the human–landscape systems in São Paulo State associated with energy policy are complex. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献