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1.
Nature ; 580(7803): 324-325, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32296185
2.
Water Res ; 175: 115676, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32193027

RESUMO

The fluid flow, species transport, and chemical reactions in geological formations are the chief mechanisms in engineering the exploitation of fossil fuels and geothermal energy, the geological storage of carbon dioxide (CO2), and the disposal of hazardous materials. Porous rock is characterized by a wide surface area, where the physicochemical fluid-solid interactions dominate the multiphase flow behavior. A variety of visual models with differences in dimensions, patterns, surface properties, and fabrication techniques have been widely utilized to simulate and directly visualize such interactions in porous media. This review discusses the six categories of visual models used in geological flow applications, including packed beds, Hele-Shaw cells, synthesized microchips (also known as microfluidic chips or micromodels), geomaterial-dominated microchips, three-dimensional (3D) microchips, and nanofluidics. For each category, critical technical points (such as surface chemistry and geometry) and practical applications are summarized. Finally, we discuss opportunities and provide a framework for the development of custom-built visual models.


Assuntos
Dióxido de Carbono , Geologia , Física , Porosidade , Propriedades de Superfície
3.
Environ Sci Technol ; 54(5): 2832-2842, 2020 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-32019302

RESUMO

Underground repository in crystalline bedrock is a widely accepted solution for long-term disposal of spent nuclear fuels. During future deglaciations, meltwater will intrude via bedrock fractures to the depths of future repositories where O2 left in the meltwater could corrode metal canisters and enhance the migration of redox-sensitive radionuclides. Since glacial meltwater is poor in reduced phases, the quantity and (bio)accessibility of minerogenic Fe(II) in bedrock fractures determine to what extent O2 in future meltwater can be consumed. Here, we determined Fe valence and mineralogy in secondary mineral assemblages sampled throughout the upper kilometer of fractured crystalline bedrock at two sites on the Baltic Shield, using X-ray absorption and Mössbauer spectroscopic techniques that were found to deliver matching results. The data point to extensive O2-consuming capacity of the bedrock fractures, because Fe(II)-rich phyllosilicates were abundant and secondary pyrite was dispersed deep into the bedrock with no overall increase in Fe(II) concentrations and Fe(II)/Fe(III) proportions with depth. The results imply that repeated Pleistocene deglaciations did not cause a measurable decrease in the Fe(II) pool. In surficial fractures, largely opened during glacial unloading, ferrihydrite and illite have formed abundantly via oxidative transformation of Fe(II)-rich phyllosilicates and recently exposed primary biotite/hornblende.


Assuntos
Compostos Férricos , Geologia , Oxirredução , Espectroscopia de Mossbauer , Espectroscopia por Absorção de Raios X , Raios X
4.
Environ Sci Technol ; 54(2): 629-646, 2020 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-31904229

RESUMO

Since the Yucca Mountain project in the U.S. was defunded in 2010, the notion of disposing of spent nuclear fuel (SNF) in deep boreholes has been reinvigorated, most recently by private companies proposing to utilize lateral drilling technology to excavate boreholes for SNF disposal in sedimentary rock. It is claimed that this approach will alleviate site characterization efforts and expand the availability of potential disposal sites. However, long-term safety will hinge upon the prevalence of geochemically reducing, highly saline, and slow-flowing fluids around the waste emplacement zone, and to quantify these parameters in fluids sampled from depths >1 km will present a challenge. Regional data indicate only a narrow geographical extent of such conditions in the conterminous United States. Furthermore, models of radionuclide transport from disposal boreholes must take into account processes that may accelerate degradation of the canisters, plug, and SNF itself, such as radiolysis and attack by constituents of hydrothermal brines, coupled with hydrogeologic features that promote advective groundwater flow. This review summarizes some geologic considerations, most notably those related to geochemistry, that challenge the long-term safety case for deep borehole disposal of SNF.


Assuntos
Água Subterrânea , Resíduos Radioativos , Eliminação de Resíduos , Geologia , Modelos Teóricos , Radioisótopos
5.
Environ Monit Assess ; 192(2): 115, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31940086

RESUMO

Nowadays, the growing concern about the environmental problems affecting the subsoil has focussed efforts on the detection and characterization of contaminated sites through geophysical prospecting methods. In the present study, a case of a contaminated site by hydrocarbons and their study by means of time domain-induced polarization tomography is presented. The response in chargeability of porous media due to this kind of pollutant allows its delimitation using this method. However, one of the limitations for the application of this technique is the presence of lithologies that contain electro-metallic salts. These salts can produce anomalies of chargeability and mask those due to nonaqueous phase liquids. The studies were conducted in an area contaminated by fuel leaks from supply tanks within a train maintenance facility. Those leaks occurred while the tanks were in use, but since their dismantling, the leak stopped. The geology of the area presented strong heterogeneities and the access was limited by train tracks. In order to locate and characterize the contaminant plume, measurements of resistivity and chargeability were carried out. A grid of monitoring wells in this area was also available from which information about free-phase pollutants was obtained, and a new drilling was carried out to verify an unexpected anomaly. The results obtained show that the location of the plume by the geophysical techniques employed can lead to ambiguity, as an anomaly that does not correspond to contaminated areas appeared but to the presence of clays rich in electro-metallic components such as Mg, Fe, Mn and Al.


Assuntos
Monitoramento Ambiental/métodos , Hidrocarbonetos/química , Poluentes do Solo/química , Geologia , Hidrocarbonetos/análise , Metais , Solo , Poluentes do Solo/análise , Tomografia
7.
Sci Total Environ ; 700: 134622, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31693951

RESUMO

Serpentinitic ultramafic geological environments (SUGEs) contain toxic geogenic contaminants (TGCs). Yet comprehensive reviews on the medical geology of SUGEs are still lacking. The current paper posits that TGCs occur widely in SUGEs, and pose human health risks. The objectives of the review are to: (1) highlight the nature, occurrence and behaviour of TGCs associated with SUGEs; (2) discuss the human intake pathways and health risks of TGCs; (4) identify the key risk factors predisposing human health to TGCs particularly in Africa; and (5) highlight key knowledge gaps and future research directions. TGCs of human health concern in SUGEs include chrysotile asbestos, toxic metals (Fe, Cr, Ni, Mn, Zn, Co), and rare earth elements. Human intake of TGCs occur via inhalation, and ingestion of contaminated drinking water, wild foods, medicinal plants, animal foods, and geophagic earths. Occupational exposure may occur in the mining, milling, sculpturing, engraving, and carving industries. African populations are particularly at high risk due to: (1) widespread consumption of wild foods, medicinal plants, untreated drinking water, and geophagic earths; (2) weak and poorly enforced environmental, occupational, and public health regulations; and (3) lack of human health surveillance systems. Human health risks of chrysotile include asbestosis, cancers, and mesothelioma. Toxic metals are redox active, thus generate reactive oxygen species causing oxidative stress. Dietary intake of iron and geophagy may increase the iron overload among native Africans who are genetically predisposed to such health risks. Synergistic interactions among TGCs particularly chrysotile and toxic metals may have adverse human health effects. The occurrence of SUGEs, coupled with the several risk factors in Africa, provides a unique and ideal setting for investigating the relationships between TGCs and human health risks. A conceptual framework for human health risk assessment and mitigation, and future research direction are highlighted.


Assuntos
Monitoramento Ambiental , Substâncias Perigosas/análise , Medição de Risco , África , Animais , Asbestos Serpentinas , Asbestose , Exposição Ambiental , Geologia , Humanos , Ferro , Neoplasias Pulmonares , Mesotelioma , Metais Pesados , Metais Terras Raras , Mineração
8.
Environ Monit Assess ; 192(1): 12, 2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31811443

RESUMO

A decline in surface water sources in Pakistan is continuously causing the over-extraction of groundwater resources which is in turn costing the saltwater intrusion in many areas of the country. The saltwater intrusion is a major problem in sustainable groundwater development. The application of electrical resistivity methods is one of the best known geophysical approaches in groundwater study. Considering the accuracy in extraction of freshwater resources, the use of resistivity methods is highly successful to delineate the fresh-saline aquifer boundary. An integrated geophysical study of VES and ERI methods was carried out through the analysis and interpretation of resistivity data using Schlumberger array. The main purpose of this investigation was to delineate the fresh/saline aquifer zones for exploitation and management of fresh water resources in the Upper Bari Doab, northeast Punjab, Pakistan. The results suggest that sudden drop in resistivity values caused by the solute salts indicates the saline aquifer, whereas high resistivity values above a specific range reveal the fresh water. However, the overlapping of fresh/saline aquifers caused by the formation resistivity was delineated through confident solutions of the D-Z parameters computed from the VES data. A four-layered unified model of the subsurface geologic formation was constrained by the calibration between formation resistivity and borehole lithologs. i.e., sand and gravel-sand containing fresh water, clay-sand with brackish water, and clay having saline water. The aquifer yield contained within the fresh/saline aquifers was measured by the hydraulic parameters. The fresh-saline interface demarcated by the resistivity methods was confirmed by the geochemical method and the local hydrogeological data. The proposed geophysical approach can delineate the fresh-saline boundary with 90% confidence in any homogeneous or heterogeneous aquifer system.


Assuntos
Monitoramento Ambiental/métodos , Geologia/métodos , Água Subterrânea/análise , Água Doce/análise , Água Subterrânea/normas , Paquistão , Sais/análise , Recursos Hídricos
9.
Environ Monit Assess ; 192(1): 49, 2019 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-31848782

RESUMO

This paper deals with the engineering-geological investigation of uncontrolled dumpsites that are abundant in post-communist countries. The sites may be redeveloped in an optimal manner by using the applied methodology of engineering-geological investigations. The research tool is a case study dealing with hazardous uncontrolled dumpsites chemically contaminated by various substances, particularly carcinogenic chromium. The dumpsite is located in the alluvial sediments of an oxbow lake of the Nitra River in the Slovak Republic. The hazard is seen in the fact that the alluvial sediments are permeable and thus the contamination may spread easily. At the same time, it is located near a river, which makes the hazard greater. Apart from the risk of contamination, another risk is related to the methane generated by the dumpsite and thus the risk of self-ignition. In order to identify the uncontrolled dumpsite body, the research was grounded in the different physical properties of the diverse geological environments. Quasi-homogenous blocks of the dumpsite body and its alluvial surroundings were well identified by using the combined three geophysical methods, namely dipole electromagnetic profiling (DEMP), electrical resistance tomography (ERT) and spontaneous polarization (SP). In order to eliminate the risk of contamination spread, redevelopment measures for the uncontrolled dumpsite in the form of sealing walls and surface sealing foil were proposed. A system of methane drainage boreholes was proposed to eliminate the risk of self-ignition. The methodology in this case study is well applicable for other uncontrolled dumpsites, which is an important outcome of the study.


Assuntos
Monitoramento Ambiental/métodos , Locais de Resíduos Perigosos , Cromo , Poluição Ambiental , Geologia , Humanos , Lagos/química , Rios/química , Eslováquia
10.
Environ Monit Assess ; 191(11): 685, 2019 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-31659477

RESUMO

Geologic carbon sequestration (GCS) projects in the USA are required to monitor groundwater quality for geochemical changes above the injection area that may be a result of CO2 or brine leakage from the storage reservoir. Should CO2 migrate into the groundwater around the compliance wells monitoring the shallower hydrologic units, each compliance parameter could react differently depending on its sensitivity to CO2. Statistically determined limits (SDLs) for detection of CO2 leakage into groundwater were calculated using background water quality data from the Illinois Basin Decatur Project (IBDP) sequestration site and prediction and tolerance intervals for specific compliance parameters. If the parameter concentrations varied outside of these ranges during the injection and post injection periods of a GCS project, then additional actions would be required to determine the reason for the changes in groundwater concentrations. Geochemical modeling can simulate the amount of CO2 needed to alter water quality parameters a statistically significant amount. This information can then inform GCS operators and regulators as to which compliance parameters are relevant (sensitive) to CO2 leakage for a given setting. For the system studied in here, Fe, Ca, K, Mg, CO2, and pH were sensitive to CO2 addition while Al, Cl, Na, and Si were not.


Assuntos
Dióxido de Carbono/análise , Sequestro de Carbono , Monitoramento Ambiental , Água Subterrânea/química , Geologia , Illinois , Sais , Qualidade da Água
11.
Nat Commun ; 10(1): 4323, 2019 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-31541087

RESUMO

Development of Archean paleosols and patterns of Precambrian rock weathering suggest colonization of continents by subaerial microbial mats long before evolution of land plants in the Phanerozoic Eon. Modern analogues for such mats, however, have not been reported, and possible biogeochemical roles of these mats in the past remain largely conceptual. We show that photosynthetic, subaerial microbial mats from Indonesia grow on mafic bedrocks at ambient temperatures and form distinct layers with features similar to Precambrian mats and paleosols. Such subaerial mats could have supported a substantial aerobic biosphere, including nitrification and methanotrophy, and promoted methane emissions and oxidative weathering under ostensibly anoxic Precambrian atmospheres. High C-turnover rates and cell abundances would have made these mats prime locations for early microbial diversification. Growth of landmass in the late Archean to early Proterozoic Eons could have reorganized biogeochemical cycles between land and sea impacting atmospheric chemistry and climate.


Assuntos
Microbiota/fisiologia , Atmosfera/química , Clima , Fenômenos Geológicos , Geologia , Indonésia , Metano , Fenômenos Microbiológicos , Microbiota/genética , Modelos Químicos , Fenômenos de Química Orgânica , Oxirredução , Oxigênio/metabolismo , Fotossíntese
12.
J Contam Hydrol ; 226: 103523, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31382075

RESUMO

Soil contamination from industrial activities is a large problem in urban areas worldwide. Understanding the spreading of contamination to underlying aquifers is crucial to make adequate risk assessments and for designing remediation actions. A large part of the northern hemisphere has quaternary deposits consisting of glacial clayey till. The till often has a complex hydrogeological structure consisting of networks of fractures, sand stringers and sand lenses that each contribute to a transport network for water, free phase and dissolved contaminants. Thus, to determine the possible flow-paths of contaminants, the geology must be described in great detail. Normally, multiple boreholes would be drilled in order to describe the geology, but boreholes alone do not provide the needed resolution to map such sand lenses and their connectivity. Cross-borehole full-decay time-domain induced polarization (TDIP) is a new tool that allows for quantitatively mapping not only contrasts in bulk resistivity, but also contrasts in spectral IP parameters. We present a feasibility study with synthetic tests and a field application on a clayey moraine environment with embedded sand lenses, with hitherto unseen ground-truth verification. Indeed, the investigated area was above the water table, which allowed for digging out the entire area after the investigation for an unprecedented description of the lens interconnectivity. The TDIP data were acquired with a full-waveform acquisition at high sampling rate, signal-processed by harmonic denoising, background removal, and de-spiking, and subsequently the full-waveform data were stacked in log-increasing tapered gates (with 7 gates per decade). The resulting TDIP decays, with usable time-gates as early as two milliseconds, were inverted in terms of a re-parameterization of the Cole-Cole model. The inverted models of the field data show a remarkable delineation of the sand lenses/layers at the site, with structure in both the resistivity and the IP parameters matching the results from the ground-truthing. The synthetic examples show that in models both below and above the groundwater table, sand-lenses with thicknesses comparable to the vertical electrode spacing can be well resolved. This suggests that full-decay cross-borehole TDIP is an ideal tool for high-resolution sand-lens imaging.


Assuntos
Água Subterrânea , Poluentes do Solo , Monitoramento Ambiental , Geologia , Tomografia , Movimentos da Água
13.
Environ Sci Technol ; 53(17): 10514-10524, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31369249

RESUMO

In the multibarrier concept for the deep geological disposal of high-level radioactive waste (HLW), bentonite is proposed as a potential barrier and buffer material for sealing the space between the steel canister containing the HLW and the surrounding host rock. In order to broaden the spectra of appropriate bentonites, we investigated the metabolic activity and diversity of naturally occurring microorganisms as well as their time-dependent evolution within the industrial B25 Bavarian bentonite under repository-relevant conditions. We conducted anaerobic microcosm experiments containing the B25 bentonite and a synthetic Opalinus Clay pore water solution, which were incubated for one year at 30 and 60 °C. Metabolic activity was only stimulated by the addition of lactate, acetate, or H2. The majority of lactate- and H2-containing microcosms at 30 °C were dominated by strictly anaerobic, sulfate-reducing, and spore-forming microorganisms. The subsequent generation of hydrogen sulfide led to the formation of iron-sulfur precipitations. Independent from the availability of substrates, thermophilic bacteria dominated microcosms that were incubated at 60 °C. However, in the respective microcosms, no significant metabolic activity occurred, and there was no change in the analyzed biogeochemical parameters. Our findings show that indigenous microorganisms of B25 bentonite evolve in a temperature- and substrate-dependent manner.


Assuntos
Bentonita , Resíduos Radioativos , Geologia , Ferro , Sulfatos
15.
Environ Monit Assess ; 191(9): 563, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31410642

RESUMO

This study aims to determine a baseline for natural soil carbon dioxide (CO2) flux at the surface based on long-term field measurements, with the ultimate purpose to detect the gas leakage at CO2 geological storage sites. CO2 surface monitoring is a tool that measures the safety and effectiveness of CO2 capture and storage (CCS), a technology which is believed to be a reliable approach to mitigate the CO2 emission. However, the fluctuations of naturally occurring CO2 in soil layers complicate the leakage detection as the soil connects both the underground layers and the atmosphere. In this regard, this study not only investigates the natural surface CO2 flux behavior but also develops an equation to estimate the surface CO2 flux with respect to the soil moisture content and temperature. To meet this end, two values within the CO2 flux equation were defined and calculated based on the field measurements; a, representing a water saturation-dependent value, and b, representing the temperature sensitivity (independent of the water saturation). The results show a good agreement between estimated and measured data. Upon which, the maximum baseline for surface CO2 flux was derived and used as a threshold to detect the potential CO2 leakage in the candidate field (INAS, Japan).


Assuntos
Dióxido de Carbono/análise , Monitoramento Ambiental/métodos , Solo/química , Atmosfera/química , Geologia , Japão , Temperatura , Água/química
16.
Nat Commun ; 10(1): 3448, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31371725

RESUMO

Today the terrestrial surface drives biogeochemical cycles on Earth through chemical weathering reactions mediated by the biological influence of soils. Prior to the expansion of life on to land, abiotic weathering may have resulted in different boundary conditions affecting the composition of the biosphere. Here we show a striking difference in weathering produced minerals preserved in the Mesoproterozoic Velkerri Formation. While the bulk chemistry and mineralogy is dominated by illite similar to many modern mudstones, application of a novel microbeam technology reveals that the initial detrital minerals were composed of mica (28%) and feldspar (45%) with only a trace amount (<2%) of typical soil formed clay minerals. The majority of illite and the high Al2O3 fraction previously interpreted as a weathering signal, is present as a replacement of feldspar and mica. These sediments record physical erosion with limited pedogenic clay mineral formation implying fundamentally different weathering pathways.


Assuntos
Minerais/química , Oceanos e Mares , Solo/química , Oligoelementos/química , Tempo (Meteorologia) , Silicatos de Alumínio , Austrália , Fenômenos Químicos , Físico-Química , Argila , Monitoramento Ambiental , Fenômenos Geológicos , Geologia , Compostos de Potássio
17.
Nature ; 571(7763): 99-102, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31270485

RESUMO

The long-term cooling, decline in the partial pressure of carbon dioxide, and the establishment of permanent polar ice sheets during the Neogene period1,2 have frequently been attributed to increased uplift and erosion of mountains and consequent increases in silicate weathering, which removes atmospheric carbon dioxide3,4. However, geological records of erosion rates are potentially subject to averaging biases5,6, and the magnitude of the increase in weathering fluxes-and even its existence-remain debated7-9. Moreover, an increase in weathering scaled to the proposed erosional increase would have removed nearly all carbon from the atmosphere10, which has led to suggestions of compensatory carbon fluxes11-13 in order to preserve mass balance in the carbon cycle. Alternatively, an increase in land surface reactivity-resulting from greater fresh-mineral surface area or an increase in the supply of reactive minerals-rather than an increase in the weathering flux, has been proposed to reconcile these disparate views8,9. Here we use a parsimonious carbon cycle model that tracks two weathering-sensitive isotopic tracers (stable 7Li/6Li and cosmogenic 10Be/9Be) to show that an increase in land surface reactivity is necessary to simultaneously decrease atmospheric carbon dioxide, increase seawater 7Li/6Li and retain constant seawater 10Be/9Be over the past 16 million years. We find that the global silicate weathering flux remained constant, even as the global silicate weathering intensity-the fraction of the total denudation flux that is derived from silicate weathering-decreased, sustained by an increase in erosion. Long-term cooling during the Neogene thus reflects a change in the partitioning of denudation into weathering and erosion. Variable partitioning of denudation and consequent changes in silicate weathering intensity reconcile marine isotope and erosion records with the need to maintain mass balance in the carbon cycle and without requiring increases in the silicate weathering flux.


Assuntos
Atmosfera/química , Ciclo do Carbono , Dióxido de Carbono/análise , Dióxido de Carbono/história , Temperatura Baixa , Sedimentos Geológicos/química , Geologia/história , Retroalimentação , Sedimentos Geológicos/análise , História Antiga , Camada de Gelo/química , Modelos Teóricos , Rios/química , Água do Mar/química , Silicatos/análise
18.
Environ Sci Technol ; 53(15): 9328-9336, 2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31318200

RESUMO

CO2/CH4 interaction determines the prospects for complementary enhanced gas recovery (EGR) associated with CO2 sequestration in shale. We characterize the competitive adsorption of CO2 and CH4 in shale using low-field NMR. Competitive sorption of CO2 relative to CH4 is defined as the CO2/CH4 competitive adsorption ratio (CO2/CH4 CAR for short) when CO2 and CH4 have the same original partial pressure in shale. Results indicate the CO2/CH4 CAR decreases with the logarithm of increasing pressure. Observed CO2/CH4 CARs are on the order of 4.28-5.81 (YDN-1) to 3.43-5.57 (YDN-2), describing the remarkable competitive advantage of CO2 sorption relative to CH4 for shale. Results also indicate that increasing the CO2/CH4 pressure ratio (1) increases the adsorption capacity of shales to CO2 and decreases that to CH4 logarithmically with pressure, and (2) boosts CO2-CH4 displacement and generates greater EGR efficiency in shale, where the EGR efficiency can be inferred by the CO2/CH4 pressure ratio using a Langmuir-like function. Furthermore, the maximum sequestration capacity of adsorbed CO2 during CO2-CH4 competition is on the order of ∼3.87 cm3/g (YDN-1) to ∼5.13 cm3/g (YDN-2). These promising results for EGR and CO2 storage reveal the considerable potential for carbon capture and geological sequestration in shale.


Assuntos
Dióxido de Carbono , Carbono , Adsorção , Geologia , Metano , Minerais
19.
Environ Sci Pollut Res Int ; 26(24): 25235-25246, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31256394

RESUMO

We explored the effect of the presence or absence of humic acid (HA) on the sorption behaviour of Sr onto soil. We examined three different experimental cases for Sr sorption: (1) sorption in the presence of only colloidal HA, (2) sorption in the presence of only soil and (3) sorption in the presence of both colloidal HA and soil (HS). A batch technique was used to study the influencing factors, including the amount of colloidal HA, solid content, pH, initial concentration of Sr and contact time. The experiments showed that the influencing factors significantly affected the sorption process. For example, in the case of soil and HS, the sorption percentage increased rapidly with increasing solid content at m/V < 20 g/L, changing from 8.35% and 37.54% to 49.09% and 77.03%, respectively. Moreover, scanning electron microscopy and Fourier transform infrared spectroscopy were used to characterize samples. The kinetics and isotherms of Sr were best described by the pseudo-second-order and Langmuir models, which indicated that the process was controlled by chemisorption and uniform monolayer sorption with constant energy on the outer surface. These findings provide valuable information for predicting strontium migration in radioactive waste disposal sites.


Assuntos
Coloides/química , Substâncias Húmicas , Resíduos Radioativos/análise , Poluentes do Solo/química , Estrôncio/química , Instalações de Eliminação de Resíduos , Adsorção , Geologia , Cinética , Radioatividade , Solo/química , Poluentes do Solo/análise , Espectroscopia de Infravermelho com Transformada de Fourier
20.
Environ Geochem Health ; 41(6): 2859-2874, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31230339

RESUMO

Insufficient information on the link between health data and geology in developing countries is a major barrier to identify sources of some emerging public health problems. A total of 2868 soil samples were collected from field sheet 0503B in Ghana to evaluate the concentrations and distributions of trace elements and their effects on human health. The samples were sieved to < 106 µm fraction and analysed for elements, As, Ba, K, Zn, Co, Cr, Cu, Mn, Ni, Pb, Mg and Fe by XRF technique and Au by fire assay method. The study identified disparities in averages of As, Cr, Fe and Mg, which resulted in enrichment and deficiencies when compared with the worldwide background average. The measured averages for As and Cr were 17.27 mg/kg and 89.25 mg/kg, respectively, for the entire area. Both averages exceeded the worldwide background values of 10 mg/kg and 8 mg/kg of As and Cr. The four traditional towns with varied activities recorded As concentrations ranging from 6.11 mg/kg at Samreboi, 16.29 mg/kg at Asankragwa, 17.42 mg/kg at Akropong and 25.99 mg/kg at Bogoso. Principal component analysis revealed a good association among Ba, Cr, Cu, Fe, K, Ni, Pb and Zn in Group 1, and their main source was interpreted as the underlying geology. Arsenic, Cr and Mg in Group 2 show a relatively weak correlation, and their sources were ascribed to a combination of geologic and anthropogenic sources. Gold had a good correlation with As, which was associated with the hydrothermal veins in the underlying rocks. The spatial plots generated from transformed soil data by Getis Ord Gi* treatments were visual methods to clearly identify geographically the hotspots and coldspots of elements that cause diseases.


Assuntos
Metais/análise , Poluentes do Solo/análise , Solo/química , Oligoelementos/análise , Arsênico/análise , Cidades , Monitoramento Ambiental/métodos , Monitoramento Ambiental/estatística & dados numéricos , Geologia , Gana , Humanos , Metais/toxicidade , Análise de Componente Principal , Saúde Pública
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