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1.
Science ; 371(6530): 731-735, 2021 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-33574212

RESUMO

Fin whale calls are among the strongest animal vocalizations that are detectable over great distances in the oceans. We analyze fin whale songs recorded at ocean-bottom seismometers in the northeast Pacific Ocean and show that in addition to the waterborne signal, the song recordings also contain signals reflected and refracted from crustal interfaces beneath the stations. With these data, we constrain the thickness and seismic velocity of the oceanic sediment and basaltic basement and the P-wave velocity of the gabbroic lower crust beneath and around the ocean bottom seismic stations. The abundant and globally available fin whale calls may be used to complement seismic studies in situations where conventional air-gun surveys are not available.


Assuntos
Baleia Comum/fisiologia , Sedimentos Geológicos , Vocalização Animal , Acústica , Animais , Fenômenos Geológicos , Oceano Pacífico
2.
Proc Natl Acad Sci U S A ; 118(2)2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33419920

RESUMO

Life in environments devoid of photosynthesis, such as on early Earth or in contemporary dark subsurface ecosystems, is supported by chemical energy. How, when, and where chemical nutrients released from the geosphere fuel chemosynthetic biospheres is fundamental to understanding the distribution and diversity of life, both today and in the geologic past. Hydrogen (H2) is a potent reductant that can be generated when water interacts with reactive components of mineral surfaces such as silicate radicals and ferrous iron. Such reactive mineral surfaces are continually generated by physical comminution of bedrock by glaciers. Here, we show that dissolved H2 concentrations in meltwaters from an iron and silicate mineral-rich basaltic glacial catchment were an order of magnitude higher than those from a carbonate-dominated catchment. Consistent with higher H2 abundance, sediment microbial communities from the basaltic catchment exhibited significantly shorter lag times and faster rates of net H2 oxidation and dark carbon dioxide (CO2) fixation than those from the carbonate catchment, indicating adaptation to use H2 as a reductant in basaltic catchments. An enrichment culture of basaltic sediments provided with H2, CO2, and ferric iron produced a chemolithoautotrophic population related to Rhodoferax ferrireducens with a metabolism previously thought to be restricted to (hyper)thermophiles and acidophiles. These findings point to the importance of physical and chemical weathering processes in generating nutrients that support chemosynthetic primary production. Furthermore, they show that differences in bedrock mineral composition can influence the supplies of nutrients like H2 and, in turn, the diversity, abundance, and activity of microbial inhabitants.


Assuntos
Ecossistema , Fenômenos Geológicos , Hidrogênio/metabolismo , Camada de Gelo/microbiologia , Ciclo do Carbono , Dióxido de Carbono/metabolismo , Islândia , Metagenoma , Oxirredução
3.
PLoS One ; 16(1): e0244719, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33481832

RESUMO

A fundamental premise of river management is that practitioners understand the resource they are working with. In river management this requires that baseline information is available on the structure, function, health and trajectory of rivers. Such information provides the basis to contextualise, to plan, to be proactive, to prioritise, to set visions, to set goals and to undertake objective, pragmatic, transparent and evidence-based decision making. In this paper we present the State-wide NSW River Styles database, the largest and most comprehensive dataset of geomorphic river type, condition and recovery potential available in Australia. The database is an Open Access product covering over 216,600 km of stream length in an area of 802,000 km2. The availability of the database presents unprecedented opportunities to systematically consider river management issues at local, catchment, regional and state-wide scales, and appropriately contextualise applications in relation to programs at other scales (e.g. internationally)-something that cannot be achieved independent from, or without, such a database. We present summary findings from the database and demonstrate through use of examples how the database has been used in geomorphologically-informed river management. We also provide a cautionary note on the limitations of the database and expert advice on lessons learnt during its development to aid others who are undertaking similar analyses.


Assuntos
Conservação dos Recursos Naturais/métodos , Rios , Austrália , Bases de Dados Factuais , Ecossistema , Fenômenos Geológicos , Rios/química
4.
PLoS One ; 15(12): e0243979, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33320914

RESUMO

The Multi-Transmitting Formula (MTF) proposed by Liao et al. is a local artificial boundary condition widely used in numerical simulations of wave propagation in an infinite medium, while the drift instability is usually caused in its numerical implementation. In view of a physical interpretation of the Gustafsson, Kreiss and Sundström criterion on numerical solutions of initial-boundary value problems in the hyperbolic partial differential equations, the mechanism of the drift instability of MTF was discussed, and a simple measure for eliminating the drift instability was proposed by introducing a modified operator into the MTF. Based on the theory of spherical wave propagation and damping effect of medium, the physical implication on modified operator was interpreted. And the effect of the modified operator on the reflection coefficient of MTF was discussed. Finally, the validity of the proposed stable implementation measure was verified by numerical tests of wave source problem and scattering problem.


Assuntos
Fenômenos Geológicos , Modelos Teóricos , Movimento (Física)
5.
PLoS One ; 15(12): e0243293, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33332375

RESUMO

The main cause of problematic soil failure under a certain load is due to low bearing capacity and excessive settlement. With a growing interest in employing shallow foundation to support heavy structures, it is important to study the soil improvement techniques. The technique of using geosynthetic reinforcement is commonly applied over the last few decades. This paper aims to determine the effect of using geogrid Tensar BX1500 on the bearing capacity and settlement of strip footing for different types of soils, namely Al-Hamedat, Ba'shiqah, and Al-Rashidia in Mosul, Iraq. The analysis of reinforced and unreinforced soil foundations was conducted numerically and analytically. A series of conditions were tested by varying the number (N) and the width (b) of the geogrid layers. The results showed that the geogrid could improve the footing's bearing capacity and reduce settlement. The soil of the Al-Rashidia site was sandy and indicated better improvement than the other two sites' soils (clayey soils). The optimum geogrid width (b) was five times the footing width (B), while no optimum geogrid number (N) was obtained. Finally, the numerical results of the ultimate bearing capacity were compared with the analytical results, and the comparison showed good agreement between both the analyses and the optimum range published in the literature. The significant findings reveal that the geogrid reinforcement may induce improvement to the soil foundation, however, not directly subject to the width and number of the geogrid alone. The varying soil properties and footing size also contribute to both BCR and SRR values supported by the improvement factor calculations. Hence, the output complemented the benefit of applying reinforced soil foundations effectively.


Assuntos
Materiais de Construção , Solo , Argila/química , Materiais de Construção/análise , Fenômenos Geológicos , Iraque , Areia/química , Solo/química
6.
PLoS One ; 15(9): e0238864, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32960904

RESUMO

The objectives are exploring the impacts of geologic hazards on the construction of homestays, improving the safety of homestay buildings, guaranteeing the safety of tourists, and enhancing the disaster-resistance of homestays in scenery spots. The computer simulation system and Building Information Modeling (BIM) technology are employed to construct a geologic hazard prediction model for homestays. The model utilizes a time history method to establish a complete early-warning and monitoring system by learning the geologic disaster data. The detection of various geologic hazards has verified the effectiveness of the proposed model. The results show that the model can reduce the losses in the case of water accumulation and landslides during storms, and the BIM technology-based homestay buildings will suffer fewer losses. In the case of earthquakes, BIM technology-based homestay buildings have no noticeable shaking and displacement. Compared to traditional construction methods, the displacement is reduced by 49.15%. In the case of a spontaneous fire, the burning area of the BIM technology-based homestay building is only 270m2. The most severe factors affecting the construction of homestay buildings are earthquakes and landslide risks. The BIM technology generates 3D building planning; therefore, planners can fully understand the problems in the building. In the meantime, the multi-source monitoring data of multiple geologic hazards can be monitored and fed back, thereby improving the timeliness of early-warning of geologic hazards. The results are of considerable significance to the prevention of losses caused by geologic hazards, which can significantly improve the understanding of geologic hazards.


Assuntos
Simulação por Computador , Indústria da Construção/métodos , Planejamento em Desastres/métodos , Desastres/prevenção & controle , Habitação , Medição de Risco/métodos , Fenômenos Geológicos , Humanos , Deslizamentos de Terra , Modelos de Riscos Proporcionais
7.
Sci Total Environ ; 743: 140818, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32758850

RESUMO

Hydrogen sulfide (H2S) represents one of the main pollutants originating from both geologic phenomena such as volcanoes, geysers, fumaroles and hot springs, and geothermal plants that produce heat and electricity. Many increasing data suggest that H2S retains a variety of biological properties, and modulates many pathways related to cardiovascular pathophysiology although its role as beneficial/adverse determinant on cardiovascular disease (CVD) is not clearly established. In this review, the current knowledge on the association between H2S exposure and risk of CVD in geothermal areas has been examined. The few epidemiological studies carried out in geothermal areas suggest, in some cases, a protective role of H2S towards CVD, while in others a positive association between exposure to H2S and increased incidence of CVD. Most of the studies have an ecological design that does not allow to produce evidence to support a causal relationship and also often lack for an adequate adjustment for individual CVD risk factors. The review has also considered the potential role of two other aspects not sufficiently explored in this relationship: the production of endogenous H2S that is a gasotransmitter producing beneficial effects on cardiovascular function at low concentration and the intake of H2S-releasing drugs for the treatment of patients affected by hypertension, inflammatory diseases, and CVD. Thus, a threshold effect of H2S and the shift of action as beneficial/adverse determinant given by the synergy of exogenous exposure and endogenous production cannot be excluded. In this complex scenario, an effort is warranted in the future to include a more comprehensive evaluation of risk for CVD in relation to H2S emissions, especially in geothermal areas.


Assuntos
Doenças Cardiovasculares , Sulfeto de Hidrogênio , Eletricidade , Fenômenos Geológicos , Humanos , Incidência
8.
Nat Commun ; 11(1): 3880, 2020 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-32759942

RESUMO

Geological sources of H2 and abiotic CH4 have had a critical role in the evolution of our planet and the development of life and sustainability of the deep subsurface biosphere. Yet the origins of these sources are largely unconstrained. Hydration of mantle rocks, or serpentinization, is widely recognized to produce H2 and favour the abiotic genesis of CH4 in shallow settings. However, deeper sources of H2 and abiotic CH4 are missing from current models, which mainly invoke more oxidized fluids at convergent margins. Here we combine data from exhumed subduction zone high-pressure rocks and thermodynamic modelling to show that deep serpentinization (40-80 km) generates significant amounts of H2 and abiotic CH4, as well as H2S and NH3. Our results suggest that subduction, worldwide, hosts large sources of deep H2 and abiotic CH4, potentially providing energy to the overlying subsurface biosphere in the forearc regions of convergent margins.


Assuntos
Ecossistema , Hidrogênio/química , Metano/química , Minerais/química , Compostos Orgânicos/química , Termodinâmica , Amônia/química , Fenômenos Químicos , Fenômenos Geológicos , Sulfeto de Hidrogênio/química , Fenômenos Mecânicos , Fenômenos de Química Orgânica , Alcaloides de Triptamina e Secologanina/química , Erupções Vulcânicas
9.
Proc Natl Acad Sci U S A ; 117(29): 16824-16830, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32632000

RESUMO

The rise of animals occurred during an interval of Earth history that witnessed dynamic marine redox conditions, potentially rapid plate motions, and uniquely large perturbations to global biogeochemical cycles. The largest of these perturbations, the Shuram carbon isotope excursion, has been invoked as a driving mechanism for Ediacaran environmental change, possibly linked with evolutionary innovation or extinction. However, there are a number of controversies surrounding the Shuram, including its timing, duration, and role in the concomitant biological and biogeochemical upheavals. Here we present radioisotopic dates bracketing the Shuram on two separate paleocontinents; our results are consistent with a global and synchronous event between 574.0 ± 4.7 and 567.3 ± 3.0 Ma. These dates support the interpretation that the Shuram is a primary and synchronous event postdating the Gaskiers glaciation. In addition, our Re-Os ages suggest that the appearance of Ediacaran macrofossils in northwestern Canada is identical, within uncertainty, to similar macrofossils from the Conception Group of Newfoundland, highlighting the coeval appearance of macroscopic metazoans across two paleocontinents. Our temporal framework for the terminal Proterozoic is a critical step for testing hypotheses related to extreme carbon isotope excursions and their role in the evolution of complex life.


Assuntos
Coevolução Biológica , Meio Ambiente , Fósseis , Animais , Ciclo do Carbono , Fenômenos Geológicos
10.
PLoS One ; 15(7): e0234071, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32667926

RESUMO

The objective is to study the design method of roadway support and provide technical support for coal mining and other mining methods that need deep roadway excavation. Through literature review, the occurrence, development mechanism and influencing factors of surrounding loose rock zones of roadways are analyzed. A method of detecting is selected according to the characteristics of surrounding rock loosening. Knowledge of elastoplastic mechanics is used to theoretically study the failure mechanism of surrounding rock in deep re-mining roadways. Based on the artificial neural network prediction model (ANN), the surrounding rock is classified and a support network model of the decision system is constructed. After the design of roadway support, a sharp change of vault subsidence normally occurs within about 7 days after excavation, and the total subsidence is 14 mm. In the following month, deformation is slow, subsidence is small, and it is basically stable after one month. The curve of the vault subsidence rate shows that the vault subsidence rate is less than or equal to 1mm/d after 7 days. The convergence rate is also less than 1 mm/d after 7 days. There are two cave mouths AB and CD, and the convergence value of AB is 6.47mm, CD is 10.26mm: CD is slightly larger than AB, and it is close to stable one month later. It is essentially consistent with the time of vault settlement and stability, and the amount of deformation is approximately the same. This shows that, with the advance of the working face, the displacement of the surrounding rock in the section away from the working face will gradually decrease and the surrounding rock will be stable. The stability time of surrounding rock displacement of the portal section is the same as that of vault subsidence under the initial support, and the amount of deformation is approximately the same, indicating that the support parameters and construction methods are reasonable.


Assuntos
Minas de Carvão , Técnicas de Apoio para a Decisão , Aprendizado Profundo , Engenharia/métodos , Fenômenos Geológicos , Deslizamentos de Terra , Elasticidade , Fenômenos Mecânicos , Maleabilidade
11.
PLoS One ; 15(6): e0233483, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32492031

RESUMO

The newly discovered plattenkalk (platy limestone) locality of Wattendorf, southern Germany, has yielded a diverse fauna and flora dated to the base of the late Kimmeridgian, Late Jurassic. We here describe three fossil turtle specimens that were recovered during systematic excavations of a distinct, 15 cm thick package of plattenkalks by the Naturkunde-Museum Bamberg. The first specimen is a large shell of Achelonia formosa, a taxon that is based on material from the late Kimmeridgian of Cerin, France. The new specimen suggests synonymy with Enaliochelys chelonia from the late Kimmeridgian of the United Kingdom. The second is a near-complete skeleton of the enigmatic Tropidemys seebachi, which was previously known only from the late Kimmeridgian of Hannover, northern Germany. The third specimen is a partial skeleton of Eurysternum wagleri, which had previously been known only from the early Tithonian of the Solnhofen region, southern Germany. In addition to new anatomical insights, the new material provides further evidence for spatial links during the late Kimmeridgian between northern and southern Germany, France, and the United Kingdom and temporal link from the late Kimmeridgian to the early Tithonian. The prevalence of partial, though articulated specimens is suggestive of predation by an unknown large marine reptile.


Assuntos
Fósseis , Tartarugas , Animais , Fósseis/anatomia & histologia , Fósseis/história , Fenômenos Geológicos , Alemanha , História Antiga , Paleontologia , Filogeografia , Especificidade da Espécie , Tartarugas/anatomia & histologia , Tartarugas/classificação
12.
PLoS One ; 15(6): e0233340, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32492038

RESUMO

The miniaturization of stone tools, as reflected through the systematic production of bladelets and bladelet tools (microliths), characterized many industries of the Late Pleistocene, with the Levantine Epipalaeolithic serving as a well-studied example. It is commonly held that microliths were used as modular inserts in composite projectiles, while their incorporation in other tools for different tasks is generally overlooked, the latter aspect being the main focus of this paper. We present here a more inclusive approach through a case study of the Geometric Kebaran (Middle Epipalaeolithic, ca. 18,500-15,000 cal BP) site of Neve David, Mount Carmel, Israel. Recent excavations at the site exposed a variety of features, and one well-preserved shallow pit provided a large lithic assemblage with ca. 90 microliths. We studied this assemblage using both the low- and high- magnification use-wear protocols, accompanied by a range of experiments. Our results show that a) the fragmentation rate is very high in this assemblage (ca. 90%), b) most of the microliths have identifiable use-wear, c) the microliths were commonly used as inserts in composite projectiles, d) many microliths were used for functions not related to weaponry and hunting, such as wood-working, weed harvesting and meat processing. These findings strongly support the suggestion that the small insets, regardless of their specific type (trapeze, rectangle, backed/retouched bladelet), were used in a wide variety of composite tools. We argue that such a versatile approach and flexibility in the use of microliths reflect a technological advantage where a minimal set of microlithic types, produced in large numbers, could provide the required elements for weapons, as well as for a variety of cutting, processing and harvesting tools needed for mundane tasks at a large Middle Epipalaeolithic camp.


Assuntos
Armas/história , Arqueologia , Desenho de Equipamento/história , Fenômenos Geológicos , História Antiga , Humanos , Indústrias/história , Israel , Miniaturização , Tecnologia/história
13.
J Environ Public Health ; 2020: 4749765, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32377205

RESUMO

The increase of urbanization level has led to the rapid increase of impervious surface area (ISA). The aim of this work is to clarify the relationship between the ISA and water quality and lay a foundation for the improvement and protection of the water quality in the basin. Taking the Fuxian Lake Basin in Yunnan Province as an example, based on the Landsat ETM+ remote sensing image and the Gram-Schmidt (GS) image fusion algorithm, the four-terminal model and the linear spectral mixture model (LSMM) were used to extract the impervious surface of the watershed from 2006 to 2015. And statistical methods were used to distinguish its relationship with water quality. The results show that the four-terminal model and the linear spectral mixture model can effectively extract the impervious surface information of the Fuxian Lake Basin. The average root mean square error (RMS) of the image decomposition results from 2006 to 2015 was less than 0.02. In the past 10 years, the ISA has changed significantly in the Fuxian Lake Basin. The ISA showed an overall upward trend from 2006 to 2015. It increased from 24.73 km2 in 2006 to 35.14 km2 in 2015, an increase of 10.81 km2. From the value anomaly, the ISA in 2006 and 2009 is lower than the multiyear average, and those in the other years are higher than the multiyear average. The percentage of ISA in the basin was significantly positively correlated with Chemical Oxygen Demand-Mn (CODMn) and total phosphorus (TP) (r is 0.772, 0.763), and the correlation in the flooding season was greater than that in the dry season. The ISA threshold for water quality deterioration is around 10% in the Fuxian Lake Basin. Reducing ISA coverage, controlling ISA to less than 10%, and preventing nonpoint source pollution during flooding season will be the best measures to effectively improve the water quality environment in the basin.


Assuntos
Monitoramento Ambiental , Lagos/química , Poluição Química da Água/análise , Análise da Demanda Biológica de Oxigênio , China , Monitoramento Ambiental/métodos , Fenômenos Geológicos , Modelos Teóricos , Fósforo/análise , Estações do Ano , Urbanização , Poluição Química da Água/prevenção & controle
14.
PLoS One ; 15(5): e0232179, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32374733

RESUMO

We report fossils of the darter Anhinga pannonica Lambrecht, 1916 from two late Miocene (Tortonian, 11.62 and 11.44 Ma) avifaunas in Southern Germany. The material from the hominid locality Hammerschmiede near Pforzen represents the most comprehensive record of this species and includes most major postcranial elements except for the tarsometatarsus. We furthermore show that the putative cormorant Phalacrocorax brunhuberi (von Ammon, 1918) from the middle Miocene of Regensburg-Dechbetten is another, previously misclassified, record of A. pannonica, and this may also be true for early Miocene fossils described as P. intermedius Milne-Edwards, 1867. A. pannonica was distinctly larger than extant darters and reached the size of A. grandis from the late Miocene of North America. We detail that only fossils from the Miocene of Europe and Africa can be referred to A. pannonica, whereas putative records from Asia fall within the size range of extant darters. A. pannonica appears to have been a long-living species (16 to 6 Ma) with an extensive distribution from the equator to the northern mid-latitudes. The extinction of large-sized darters in Europe is likely to have been due to climatic cooling in the late Neogene, but the reasons for their disappearance in Africa and South America remain elusive.


Assuntos
Aves/anatomia & histologia , Tamanho Corporal , Fenômenos Geológicos , Animais , Evolução Biológica , Fósseis , Alemanha
15.
PLoS One ; 15(5): e0232433, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32459811

RESUMO

In order to cope with the problems of high frequency and multiple causes of mountain fires, it is very important to adopt appropriate technologies to monitor and warn mountain fires through a few surface parameters. At the same time, the existing mobile terminal equipment is insufficient in image processing and storage capacity, and the energy consumption is high in the data transmission process, which requires calculation unloading. For this circumstance, first, a hierarchical discriminant analysis algorithm based on image feature extraction is introduced, and the image acquisition software in the mobile edge computing environment in the android system is designed and installed. Based on the remote sensing data, the land surface parameters of mountain fire are obtained, and the application of image recognition optimization algorithm in the mobile edge computing (MEC) environment is realized to solve the problem of transmission delay caused by traditional mobile cloud computing (MCC). Then, according to the forest fire sensitivity index, a forest fire early warning model based on MEC is designed. Finally, the image recognition response time and bandwidth consumption of the algorithm are studied, and the occurrence probability of mountain fire in Muli county, Liangshan prefecture, Sichuan is predicted. The results show that, compared with the MCC architecture, the algorithm presented in this study has shorter recognition and response time to different images in WiFi network environment; compared with MCC, MEC architecture can identify close users and transmit less data, which can effectively reduce the bandwidth pressure of the network. In most areas of Muli county, Liangshan prefecture, the probability of mountain fire is relatively low, the probability of mountain fire caused by non-surface environment is about 8 times that of the surface environment, and the influence of non-surface environment in the period of high incidence of mountain fire is lower than that in the period of low incidence. In conclusion, the surface parameters of MEC can be used to effectively predict the mountain fire and provide preventive measures in time.


Assuntos
Algoritmos , Processamento de Imagem Assistida por Computador/métodos , Incêndios Florestais/prevenção & controle , China , Computação em Nuvem , Sistemas Computacionais , Conservação dos Recursos Naturais/métodos , Conservação dos Recursos Naturais/estatística & dados numéricos , Análise Discriminante , Fenômenos Geológicos , Humanos , Processamento de Imagem Assistida por Computador/estatística & dados numéricos , Software , Propriedades de Superfície , Incêndios Florestais/estatística & dados numéricos
16.
Chemosphere ; 254: 126696, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32335434

RESUMO

In this work, a geochemical approach was used as strong-scientific tool for pre-selection of suitable remediation systems to treat Cr-contaminated groundwaters. The geochemical characterization allowed to select Nanofiltration (NF) and Reverse Osmosis (RO) as suitable remediation processes, whereas through a new geochemical modeling, the evolution of water chemistry during the water-rock interaction was also studied. The new reaction path modelling was performed re-evaluating the role of Fe as main oxidant in the system and the analytic concentrations of relevant solutes, including Cr(VI), were reproduced. The spring with the highest Cr(VI) content was treated to lower its concentration below the threshold values. A laboratory-scale set-up was used to carry out both NF and RO experiments. The experiments were conducted on different commercial membranes varying the operating pressures. The results showed high Cr(VI) rejections (around 95%) for all tested membranes, leading to Cr(VI) concentrations below the threshold limits. The high flux, obtained already at lower operating pressures, combined with high selectivity towards Cr(VI) makes NF a favorable remediation option.


Assuntos
Cromo/análise , Modelos Químicos , Poluentes Químicos da Água/análise , Purificação da Água , Filtração , Fenômenos Geológicos , Água Subterrânea/química
17.
Sci Rep ; 10(1): 6794, 2020 04 22.
Artigo em Inglês | MEDLINE | ID: mdl-32321943

RESUMO

Magadiite, a rare hydrous sodium-silicate mineral [NaSi7O13(OH)3·4(H2O)], was discovered about 50 years ago in sediments around Lake Magadi, a hypersaline alkaline lake fed by hot springs in the semi-arid southern Kenya Rift Valley. Today this harsh lacustrine environment excludes most organisms except microbial extremophiles, a few invertebrates (mostly insects), highly adapted fish (Alcolapia sp.), and birds including flamingos. Burrows discovered in outcrops of the High Magadi Beds (~25-9 ka) that predate the modern saline (trona) pan show that beetles and other invertebrates inhabit this extreme environment when conditions become more favourable. Burrows (cm-scale) preserved in magadiite in the High Magadi Beds are filled with mud, silt and sand from overlying sediments. Their stratigraphic context reveals upward-shallowing cycles from mud to interlaminated mud-magadiite to magadiite in dm-scale units. The burrows were formed when the lake floor became fresher and oxygenated, after a period when magadiite precipitated in shallow saline waters. The burrows, probably produced by beetles, show that trace fossils can provide evidence for short-term (possibly years to decades) changes in the contemporary environment that might not otherwise be recognised or preserved physically or chemically in the sediment record.


Assuntos
Ambientes Extremos , Fósseis , Sedimentos Geológicos/química , Silicatos/metabolismo , Animais , Aves/fisiologia , Peixes/fisiologia , Geografia , Fenômenos Geológicos , Fontes Termais , Insetos/fisiologia , Quênia , Lagos , Águas Salinas
18.
PLoS One ; 15(4): e0231790, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32310971

RESUMO

Seemingly empty spaces in various archaeological settings have left many unanswered questions. This paper focuses on the appearance, maintenance and possible function of a large empty area situated at the summit plateau of the Iron Age oppidum Bibracte in France. Multidisciplinary research of the infill of the ditch that delimited this area in the 1st century BC has provided evidence on the primary function and the formation processes of the structure itself, and for the reconstruction of the appearance, maintenance and function of the area it enclosed. The results allow us to gain insight into a variety of topics, including the role of trees, hygiene measures and waste management strategies at this urbanised hilltop centre. This paper demonstrates that multi-proxy analyses provide detailed insight into the function of archaeological features in a local environmental context and the potential of such approaches in archaeology.


Assuntos
Arqueologia , Urbanização/história , Arqueologia/métodos , Diatomáceas/classificação , França , Sedimentos Geológicos/análise , Fenômenos Geológicos , História Antiga , Humanos , Datação Radiométrica/métodos , Árvores/classificação , Gerenciamento de Resíduos/história
19.
Sci Rep ; 10(1): 5051, 2020 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-32327670

RESUMO

Cenozoic ectothermic continental tetrapods (amphibians and reptiles) have not been documented previously from Antarctica, in contrast to all other continents. Here we report a fossil ilium and an ornamented skull bone that can be attributed to the Recent, South American, anuran family Calyptocephalellidae or helmeted frogs, representing the first modern amphibian found in Antarctica. The two bone fragments were recovered in Eocene, approximately 40 million years old, sediments on Seymour Island, Antarctic Peninsula. The record of hyperossified calyptocephalellid frogs outside South America supports Gondwanan cosmopolitanism of the anuran clade Australobatrachia. Our results demonstrate that Eocene freshwater ecosystems in Antarctica provided habitats favourable for ectothermic vertebrates (with mean annual precipitation ≥900 mm, coldest month mean temperature ≥3.75 °C, and warmest month mean temperature ≥13.79 °C), at a time when there were at least ephemeral ice sheets existing on the highlands within the interior of the continent.


Assuntos
Anuros , Mudança Climática/história , Fósseis , Animais , Regiões Antárticas , Ecossistema , Água Doce , Sedimentos Geológicos , Fenômenos Geológicos , História Antiga , Camada de Gelo , Ílio , Crânio
20.
Ecotoxicol Environ Saf ; 195: 110475, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32208212

RESUMO

Risk assessment regarding heavy metals in tea is crucial to ensure the health of tea customers. However, the effects of geological difference on distribution of heavy metals in soils and their accumulation in tea leaves remain unclear. This study aimed to estimate the impacts of geological difference on distribution of cadmium (Cd), lead (Pb), thallium (Tl), mercury (Hg), arsenic (As), antimony (Sb), chromium (Cr), nickel (Ni), and manganese (Mn) in soils and their accumulation in tea leaves, and further evaluate their health risks. 22 soils and corresponding young tea leaves (YTL) and old tea leaves (OTL), from geologically different plantations, were sampled and analyzed. Results showed that heavy metals concentrations in soils, derived from Permian limestone and Cambrian weakly mineralized dolomite, were obviously greater than those from Silurian clastic rock. The geological difference controlled the distribution of soil heavy metals to a large extent. Contents of Cd, Tl, and Mn in tea leaves mainly depended on their contents in soils. Soil Hg, Pb, As, and Sb contents may not be the only influencing factors for their respective accumulation in tea leaves. More attentions should be paid to soil acidification of tea plantations to ensure the tea quality security. Target hazard quotients (THQ) of Cd, Pb, Tl, Hg, As, Sb, Cr, and Ni and hazard index (HI) via tea intake were below one, indicating no human health risk. The non-mineralized Silurian area was less at risk of heavy metals accumulation in tea leaves than the Cambrian metallogenic belt and the Permian Cd-enriched zone. This study could provide an important basis to understand and mitigate the potential risks of heavy metals in tea.


Assuntos
Metais Pesados/análise , Poluentes do Solo/análise , Chá/química , Antimônio/análise , Arsênico/análise , Cádmio/análise , China , Cromo/análise , Monitoramento Ambiental , Fenômenos Geológicos , Humanos , Chumbo/análise , Manganês/análise , Mercúrio/análise , Níquel/análise , Folhas de Planta/química , Medição de Risco , Solo/química , Tálio/análise
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