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1.
Chemosphere ; 241: 125116, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31683429

RESUMO

Oscillating cycles of dewatering (termed drying) and rewetting during managed aquifer recharge (MAR) are used to maintain infiltration rates and could also exert an influence on subsurface microbial structure and respiratory processes. Despite this practice, little knowledge is available about changes to microbial community structure and trace organic chemical biodegradation potential in MAR systems under these conditions. A biologically active two-dimensional (2D) synthetic MAR system equipped with automated sensors (temperature, water pressure, conductivity, soil moisture, oxidation-reduction potential) and embedded water and soil sampling ports was used to test and model these important subsurface processes at the meso-scale. The fate and transport of the antiepileptic drug carbamazepine, the antibiotics sulfamethoxazole and trimethoprim, and the flame retardant tris (2-chloroethyl) phosphate were simulated using the finite element analysis model, FEFLOW. All of these compounds exhibit moderate to poor biodegradability in MAR systems. Within the operational MAR scenario tested, three episodic drying cycles spanning between 18 and 24 days were conducted over a period of 184 days. Notably, cessation of flow and partial dewatering of the 2D synthetic aquifer during dry cycles caused no measurable decrease in soil moisture content beyond the near-surface layer. The episodic flow introduction and dewatering cycles in turn had little impact on overall trace organic chemical biotransformation behavior and soil microbial community structure. However, spatial differences in oxidation-reduction potential and soil moisture were both identified as significant environmental predictors for microbial community structure in the 2D synthetic aquifer.


Assuntos
Biodegradação Ambiental , Dessecação/métodos , Água Subterrânea/química , Poluentes Químicos da Água/química , Molhabilidade , Biotransformação , Fenômenos Geológicos , Água Subterrânea/microbiologia , Microbiota , Compostos Orgânicos/análise , Compostos Orgânicos/química , Oxirredução , Microbiologia do Solo , Poluentes Químicos da Água/análise
2.
An Acad Bras Cienc ; 91(4): e20181337, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31800703

RESUMO

What controls the formation of patchy substrates of white sand vegetation in the Amazonian lowlands is still unclear. This research integrated the geological history and plant inventories of a white sand vegetation patch confined to one large fan-shaped sandy substrate of northern Amazonia, which is related to a megafan environment. We examined floristic patterns to determine whether abundant species are more often generalists than the rarer one, by comparing the megafan environments and older basement rocks. We also investigated the pattern of species accumulation as a function of increasing sampling effort. All plant groups recorded a high proportion of generalist species on the megafan sediments compared to older basement rocks. The vegetation structure is controlled by topographic gradients resulting from the smooth slope of the megafan morphology and microreliefs imposed by various megafan subenvironments. Late Pleistocene-Holocene environmental disturbances caused by megafan sedimentary processes controlled the distribution of white sand vegetation over a large area of the Amazonian lowlands, and may have also been an important factor in species diversification during this period. The integration of geological and biological data may shed new light on the existence of many patches of white sand vegetation from the plains of northern Amazonia.


Assuntos
Sedimentos Geológicos , Fenômenos Geológicos , Melastomataceae , Traqueófitas , Brasil , Geografia , Areia
3.
PLoS One ; 14(12): e0226358, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31856226

RESUMO

A multidisciplinary study (geomorphology, sedimentology and palynology) shows that the landscapes of the southwest coast of Corsica have been deeply modified by humans and the climate since 3000 BC. Significant and rapid landscape transformations are recorded between the Chalcolithic and the Middle Bronze Ages (3000-1300 BC). Several major (2.2 ka BC, 1.2 ka BC) and local (3000 BC) detrital events affected the Taravo Lower Valley in relation to global climatic changes and anthropic activities. The vegetation dynamics since 3000 BC show alternating phases of agriculture and abandonment until the complete disappearance of the original forest populations in the vicinity of the Canniccia Marshes. An early phase of Olea cultivation is recorded between 2900 and 2300 BC. Plant macro-remains indicate that cereals, vine and many species of Fabaceae were cultivated in the nearby of the archaeological sites during the middle to the late Chalcolithic Age. The event of 2.2 ka BC corresponds to an abandonment phase in the lower Taravo Valley. Pastoralism dominated agricultural activities between 2200 and 1700 BC. During Roman times, agriculture is characterized by olive and vine cultivation. A new peak of pastoralism and the cultivation of Castanea are noted during invasion times (500 to 1000 AD), showing that invasions didn't disturb agricultural activities in the Taravo Valley. During the Pisa Period (end of the 9th C. to then end of 13th C. AD), pastoralism declined and vine and cereals were cultivated in the very nearby of the Canniccia Marshes. During the Genoa Period upwards (end of the 13th C. to 1769 AD), a decline in agriculture and a recrudescence of the forest (maquis and pine) are recorded, leading to the settlement of a present-day vegetal landscape dominated by an Erica arborea maquis.


Assuntos
Agricultura , Clima , Arqueologia , França , Fenômenos Geológicos , Pólen/crescimento & desenvolvimento , Rios , Fatores de Tempo
4.
Artigo em Inglês | MEDLINE | ID: mdl-31682563

RESUMO

The purpose of the study was to determine the spatial distribution and pollution assessment of 39 chemical elements in soil from the Republic of North Macedonia. From the whole territory of the country top soil samples (0-30 cm) were collected from 995 locations with a grid of 5 × 5 km distance between the sampling locations. Two analytical techniques were used for the analysis of soil samples: inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry. Based on a comparison of statistical parameters, spatial distribution of particular elements and results of cluster and factor analysis, four mаin geochemical associations were identified: (1) association connected with the Neogene and Quaternary volcanism (Ba, Be, Ce, Hf, K, La, Rb, Th, Tl, U and Zr); (2) association of siderophile elements (Co, Cu, Fe, Mn, Sc, Ti and V); (3) association connected with ophiolites and Mesozoic ultrabasic magmatic rocks of Vardar zone (Cr and Ni) and (4) chalcophile (sulphide) elements (As, Bi, Cd, Pb, Sb, Sn and Zn). The regional distribution was prepared according to the eight statistical regions in Macedonia, distribution according to 15 most common geological formation and distribution according to 13 pedological units.


Assuntos
Monitoramento Ambiental , Metais Pesados/análise , Poluentes do Solo/análise , Solo/química , Fenômenos Geológicos , Humanos
5.
Environ Monit Assess ; 191(12): 726, 2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31701315

RESUMO

Social forestry policies grant local communities the right to access protected forest areas contingent upon certain governmental criteria. However, the adoption of social forestry is known to alter land-cover patterns and promote soil erosion. This study assessed the water quality of Sekampung Hulu and Sangharus Rivers in Lampung, Indonesia, based on their total suspended solid (TSS) concentrations. Subsequently, the extent of soil erosion in the two watersheds was determined, and best management practices (BMPs) were recommended for the study area. Water sampling was conducted in 2016 to estimate TSS levels in the two watersheds. Additionally, the Universal Soil Loss Equation (USLE) was integrated with an ArcGIS model to evaluate soil erosion in the watersheds. The results indicated that TSS concentrations in the Sekampung Hulu and Sangharus Rivers ranged from 36-813 mg L-1 and 16-146 mg L-1, respectively. Further, the average soil erosion rates in the Sekampung Hulu and Sangharus watersheds were 12.5 Mg ha-1 year-1 and 5.6 Mg ha-1 year-1, respectively. The results indicated that young coffee trees increased soil erosion rates, especially in areas characterized by vulnerable soil. The USLE results concurred with the TSS analysis and indicated higher erosion rates for the Sekampung Hulu watershed than the Sangharus watershed. The application of BMPs, including conversion to agroforestry coffee, cover crops, and contour systems, was effective in reducing soil erosion in both the Sekampung Hulu and Sangharus watersheds.


Assuntos
Conservação dos Recursos Naturais/métodos , Florestas , Fenômenos Geológicos , Solo , Produtos Agrícolas , Monitoramento Ambiental/métodos , Agricultura Florestal , Sistemas de Informação Geográfica , Indonésia , Rios , Árvores
6.
Environ Monit Assess ; 191(12): 758, 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31741070

RESUMO

The unsuitable construction of unpaved roads has been causing problems related to the formation of erosive processes, sediments in watersheds, bogs, flooding, and holes. Presuming that the areas where flow accumulation intersects unpaved roads represent risk points, our objectives are (1) to develop a qualitative method based on the GIS software management tool (FlowAccRoad) for the identification of the intersection points between flow accumulation and roads and (2) to verify the discrepancy between the points of intersection produced by digital elevation models (DEM) accounting for different spatial resolutions. In the GIS environment, we used the Shuttle Radar Topography Mission (SRTM) and Goiania (GOI) digital elevation models for the modeling of flow accumulation and vectorization of the unpaved roads, both of which are based on the Bandeira Stream Watershed in Goiania, Goiás, Brazil. This highlights that 54 points of intersection between the flow accumulation and unpaved roads present problems related to erosive processes and quagmires, among others. The FlowAccRoad method identified the principal critical points observed in the field, using both the DEM of 30.4 m of spatial resolution (SRTM) and also of 4.8 m of spatial resolution (GOI). From the FlowAccRoad method, we observed that 91% of the risk points identified through the GOI DEM were located less than 20 m from valid points in the field by using GPS. Analyzing the SRTM DEM, only 45% of the critical risk points identified by the method were located less than 20 m from valid points in the field.


Assuntos
Monitoramento Ambiental/métodos , Fenômenos Geológicos , Brasil , Inundações , Radar , Rios , Áreas Alagadas
7.
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
8.
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 , Química Física , Argila , Monitoramento Ambiental , Fenômenos Geológicos , Geologia , Compostos de Potássio
9.
J Environ Radioact ; 208-209: 106008, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31419761

RESUMO

Channelization significantly affects soil erosion in river floodplains. The object of this study was to use 137Cs as a tracer to determine the 137Cs inventory and derived soil erosion rates under various land use types in a catchment on channelized river floodplain in the lower reaches of Yangtze River, China. Sampling was carried out to establish a137Cs reference inventory in a 70-year old paddy field located on the shoulder-slope of a local hill. The mean reference inventory of 137Cs was 1275 Bq m-2, whereas the 137Cs inventory within the catchment ranged from 284 to 1150 Bq m-2 and the soil erosion rates from -33.3 to -2.4 t ha-1 yr-1, respectively. The dominated land use of paddy in cultivated soils contributed relative low soil erosion. Bamboo and castanea mollissima were preferential for local land uses in uncultivated soils in comparison with woodland and Pinnus massoniana. The rates of soil erosion rates in old tea garden were higher than that in new tea garden. Overall, severe soil erosion and no deposition in the entire catchment occurred in the entire catchment due to the human-induced channelization in the 1970s. Our results suggest that restricting farmland being returned to tea plantations, thereby maintaining the current land use types would reduce soil erosion in river floodplain in the future.


Assuntos
Monitoramento de Radiação , Poluentes Radioativos do Solo/análise , Radioisótopos de Césio/análise , China , Fenômenos Geológicos , Rios/química
10.
Artigo em Inglês | MEDLINE | ID: mdl-31328630

RESUMO

This study represents the first systematic investigation of the spatial distribution of different chemical elements in the soil of the city of Skopje, Republic of Macedonia. For this purpose, surface soil samples from 234 locations were analyzed to determine the content of 20 major and trace elements (Ag, Al, As, Ba, Ca, Cd, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, Sr, V and Zn) to assess the size of the areas eventually affected by heavy metal pollution. All samples were analyzed by atomic emission spectroscopy with inductively coupled plasma (ICP-AES). Cluster and factor analysis (R-mode) were applied in order to show the associations of chemical elements. Four factors were obtained: Factor 1 (K, Na, Ba and Al), Factor 2 (Cr, Ni, Mg and Fe), Factor 3 (Zn, Cd and Cu) and Factor 4 (Sr and Ca). It was established that the distribution of the associations of F1, F2 and F4 are mostly as a result of the complex geology and lithology of the region while the association of F3 represents an anthropogenic association.


Assuntos
Monitoramento Ambiental , Solo/química , Oligoelementos/análise , Monitoramento Ambiental/métodos , Poluição Ambiental/análise , Fenômenos Geológicos , Humanos , Metais Pesados/análise , Poluentes do Solo/análise , Saúde da População Urbana , Urbanização
11.
Artigo em Inglês | MEDLINE | ID: mdl-31315302

RESUMO

The potential of karst aquifers as a drinking water resource is substantial because of their large storage capacity gained in the course of carbonate dissolution. Carbonate dissolution and consequent development of preferential paths are also the reasons for the complex behavior of these aquifers as regards surface and underground flow. Hydrological modeling is therefore of paramount importance for an adequate assessment of flow components in catchments shaped on karsts. The cross tabulation of such components with geology, soils, and land use data in Geographic Information Systems helps decision makers to set up sustainable groundwater abstractions and allocate areas for storage of quality surface water, in the context of conjunctive water resources management. In the present study, a hydrologic modeling using the JAMS J2000 software was conducted in a karst area of Jequitiba River basin located near the Sete Lagoas town in the state of Minas Gerais, Brazil. The results revealed a very high surface water component explained by urbanization of Sete Lagoas, which hampers the recharge of 7.9 hm3 yr-1 of storm water. They also exposed a very large negative difference (-8.3 hm3 yr-1) between groundwater availability (6.3 hm3 yr-1) and current groundwater abstraction from the karst aquifer (14.6 hm3 yr-1), which is in keeping with previously reported water table declines around drilled wells that can reach 48 m in old wells used for public water supply. Artificial recharge of excess surface flow is not recommended within the urban areas, given the high risk of groundwater contamination with metals and hydrocarbons potentially transported in storm water, as well as development of suffosional sinkholes as a consequence of concentrated storm flow. The surface component could however be stored in small dams in forested areas from the catchment headwaters and diverted to the urban area to complement the drinking water supply. The percolation in soil was estimated to be high in areas used for agriculture and pastures. The implementation of correct fertilizing, management, and irrigation practices are considered crucial to attenuate potential contamination of groundwater and suffosional sinkhole development in these areas.


Assuntos
Conservação dos Recursos Hídricos , Modelos Teóricos , Recursos Hídricos , Brasil , Fenômenos Geológicos , Hidrologia , Urbanização , Abastecimento de Água
12.
J Environ Radioact ; 208-209: 106021, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31357076

RESUMO

Fallout radionuclides, such as 137Cs, have been recognized as a valuable means for studying soil erosion processes. In this study, the 137Cs technique was used to assess soil erosion magnitude and to investigate the effectiveness of terrace cultivations in the High Atlas of Morocco, particularly, the Ourika watershed. 137Cs depth distribution profiles were established along slope gradients associated with land use considering cereal crop, arboriculture and native forests. Along the slope gradient, depth distribution profiles highlight dissimilarities reflecting differences in land use, topographic roughness, soil particle distribution and stoniness. 137Cs inventory decreases exponentially with depth and its penetration increases along the slope. It becomes higher at the bottom of the slope, with penetration reaching 30 cm. 137Cs mass activity and inventory significantly decrease in cultivated terraces, compared to native forest. Although the pattern of 137Cs gain/loss varied according to topography, soil properties and vegetation cover, showing eroding and aggrading profiles, most samples had 137Cs values lower than the reference value, suggesting net-loss of soil as a consequence of erosion processes. The net erosion rates were estimated about 8.5 and 6.0 t ha-1 yr-1 in cereal crop and arboriculture agrosystems, respectively, whereas in the forest, the net erosion rate was lower at about 4.2 t ha-1 yr-1. Soil loss on agricultural terraces is not significantly above tolerable erosion rates for Morocco (<7 t ha-1 yr-1), particularly for arboriculture terraces. A strong correlation was observed between 137Cs and both soil organic carbon and slope gradient, in uncultivated area, whereas, there was no correlation for cultivated terraces. Terraced arboriculture systems should be encouraged for better soil preservation against water erosion in the Ourika watershed.


Assuntos
Radioisótopos de Césio/análise , Fenômenos Geológicos , Monitoramento de Radiação , Poluentes Radioativos do Solo/análise , Solo/química , Agricultura , Marrocos
13.
PLoS One ; 14(6): e0218525, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31242202

RESUMO

Rockburst is a common dynamic disaster in deep underground engineering. To accurately predict rockburst intensity grade, this study proposes a novel rockburst prediction model based on variable weight and matter-element extension theory. In the proposed model, variable weight theory is used to optimize the weights of prediction indexes. Matter-element extension theory and grade variable method are used to calculate the grade variable interval corresponding to the classification standard of rockburst intensity grade. The rockburst intensity grade of Engineering Rock Mass is predicted by rock burst intensity level variable and the interval. Finally, the model is tested by predicting the rockburst intensity grades of worldwide several projects. The prediction results are compared with the actual rockburst intensity grades and the prediction results of other models. The results indicate that, after using variable weight theory and grade variable method, the correct rate of prediction results of matter-element extension model is improved, and the safety of the prediction results is also enhanced. This study provides a new way to predict rock burst in underground engineering.


Assuntos
Fenômenos Geológicos , Modelos Teóricos , Força Compressiva , Engenharia , Mineração
14.
Artigo em Inglês | MEDLINE | ID: mdl-31100926

RESUMO

Water pollution is a major threat to public health worldwide. The health risks of ingesting trace elements in drinking water were assessed in the provinces of Punjab and Khyber Pakhtunkhwa, Pakistan. Eight trace elements were measured in drinking water, using Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and compared with permissible limits established by the World Health Organization (WHO) and the Pakistan Environmental Protection Agency (Pak EPA). In addition, health risk indicators such as the chronic daily intake (CDI) and the health risk index (HRI) were calculated. Our results showed that the concentrations of chromium (Cr), nickel (Ni), and manganese (Mn) were 2593, 1306, and 695 ng/g, respectively, in Lahore and Jhang, while the concentrations of arsenic (As) in Lahore, Vehari, Multan, and Jhang were 51, 50.4, 24, and 22 ng/g, respectively, which were higher than the permissible limits suggested by the WHO. The values of CDI were found to be in the order of Cr > Ni > Mn > Cu > As > Pb > Co > Cd. Similarly, the health risk index (HRI) values exceeded the safe limits (>1) in many cities (eg, Cr and Ni in Lahore and As in Vehari, Jhang, Lahore, and Multan). The aforementioned analysis shows that consumption of trace element-contaminated water poses an emerging health danger to the populations of these localities. Furthermore, inter-metal correlation and principal component analysis (PCA) showed that both anthropogenic and geologic activities were primary sources of drinking water contamination in the investigated areas.


Assuntos
Arsênico/análise , Água Potável/análise , Metais Pesados/análise , Poluentes Químicos da Água/análise , Adulto , Monitoramento Ambiental , Fenômenos Geológicos , Atividades Humanas , Humanos , Paquistão , Medição de Risco , Fatores de Risco
15.
An Acad Bras Cienc ; 91(2): e20180514, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31038538

RESUMO

The reviewed and integrated geoheritage inventory of the northern coast of the state of São Paulo, Brazil, resulted in 43 geosites distributed in eight geological frameworks. The selected geosites are representative of a geological history from the Neoproterozoic (Brasiliano-Pan African Cycle) to the recent, covering a minimum 700-Ma timespan. Considering the dynamic character of geoheritage inventories, the results presented in this work were based on previous local, town-based surveys, which were reviewed under the light of new geological data and geoconservation methods. Both qualitative and quantitative geosites assessments were used to discuss their geological representativeness and relevance, as well as legal aspects regarding protection and perspectives for future use. This resulted in a detailed inventory that reflects the current geological knowledge in the northern coast of the state of São Paulo, and may be used to make a general diagnosis of the scientific value, state of conservation, risk of degradation and potential use of the geoheritage. Moreover, it reinforces the importance of locally- and regionally-relevant sites for sustainable land management using geoheritage and to direct the decisions related to the conservation and use of this abiotic part of nature in the region.


Assuntos
Conservação dos Recursos Naturais , Fenômenos Geológicos , Brasil , Sistemas de Informação Geográfica , Geologia/métodos , Registros
16.
PLoS One ; 14(5): e0217381, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31136593

RESUMO

As part of the cultural landscape, administrative toponyms do not only reflect natural and sociocultural phenomena, but also help with related management and naming work. Historically, county-level administrative districts have been stable and basic administrative regions in China, playing a role in the country's management. We explore the spatio-temporal evolutionary characteristics of the county-level administrative toponyms cultural landscape in China's eastern plains areas. A Geographical Information System (GIS) analysis, Geo-Informatic Tupu, Kernel Density Estimation, and correlation coefficients were conducted. We constructed a GIS database of county-level administrative toponyms from the Sui dynasty onward using the Northeast China, North China, and Yangtze Plains as examples. We then summarized the spatio-temporal evolutionary characteristics of the county-level administrative toponyms cultural landscape in China's eastern plains areas. The results indicate that (1) the number of toponyms has roughly increased over time; (2) toponym densities on the three plains are higher than the national average in the corresponding timeframe since the Sui; and (3) county-level administrative toponyms related to mountains and hydrological features accounted for more than 30% of the total in 2010. However, the percentage of county-level administrative toponyms related to natural factors on the three plains has decreased since the Sui. To explore the factors influencing this spatio-temporal evolution, we analyzed the correlations between the toponyms and natural factors and human/social factors. The correlation degree between toponym density and population density is the highest, and that between toponym density and Digital Elevation Model (DEM) the lowest. Temperature changes were important in toponym changes, and population changes have influenced toponym changes over the last 400 years in China.


Assuntos
Características Culturais , China , Características Culturais/história , Evolução Cultural/história , Sistemas de Informação Geográfica , Fenômenos Geológicos , História do Século XVI , História do Século XIX , História do Século XX , História do Século XXI , História Antiga , Humanos , Governo Local/história , Densidade Demográfica , Análise Espaço-Temporal , Terminologia como Assunto
17.
PLoS One ; 14(5): e0215469, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31051007

RESUMO

A group of beads from the artificial cave of La Molina (Lora de Estepa, Sevilla) and Cova del Gegant (Sitges, Barcelona) were made from a biogenic raw material and intentionally covered by a layer of resin. This is the first time this type of treatment has been documented on elements of adornment in the Late Prehistory of the Iberian Peninsula. The composition and nature of the coatings are analysed and the symbolic role of such alterations and imitations of prehistoric adornments is discussed.


Assuntos
Âmbar/história , Pinus/ultraestrutura , Arqueologia , Fenômenos Geológicos , História Antiga , Espanha , Espectrofotometria Infravermelho , Difração de Raios X
18.
PLoS One ; 14(4): e0215893, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31022241

RESUMO

The interaction of active faults as a factor affecting the mechanisms of large earthquakes has been observed in many places. Most aftershock and clustering earthquake sequences do not recur on the main seismogenic fault but are controlled by fault interactions with adjacent seismic structures. Four groups of conceptual models were generated in this study to determine how the geometry of the seismogenic faults controls the distributions of stress fields and earthquakes. The influences of the fault length ratio, center distance, overlap ratio, echelon distance and fault opening angle were considered in a 2D viscoelastic model. The results indicate that the interaction in the slipping zone is larger when collinear interacting faults are more closely positioned, with one fault lengthening. For noncollinear faults, the interaction is stronger as the inner tips pass each other, which impedes their growth after some degree of overlap. Additionally, fault interaction at the slipping zone becomes stronger as the opening angle approaches 180°. We further generated a 3D viscoelastic model of fault interactions in Central North China Block and applied the finite element method to analyze the relationship between distributions of earthquakes and fault geometry. The calculated results reveal well-matched higher stress and maximum shear strain concentrations in the southern part of the Fen-wei Graben Zone than in other zones in Central North China Block, which can be explained by the longer faults, shorter center distances, shorter overlap lengths and larger opening angles. The stress distributions and fault interactions should be considered in long-term seismic hazard assessment in these zones.


Assuntos
Simulação por Computador , Fenômenos Geológicos , Análise Numérica Assistida por Computador , China , Terremotos , Modelos Teóricos
19.
Sci Total Environ ; 674: 615-622, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31029025

RESUMO

Fires are a complex phenomenon that may generate a chain of responses and processes that affect each part of the ecosystem. Thus, it is important to understand the magnitude of the impacts of fire on soil properties and the response of plants to this disturbance. For the moment, few studies have examined the effects of prescribed fire on large plots in afforested pine plantations in Mediterranean ecosystems. To fill this gap, the effects of a prescribed fire on runoff, soil erosion, and water quality for approximately one year after burning have been evaluated in pine plantations in south-eastern Spain. We constructed six erosion plots in the control area and six erosion plots in the burned area that were 4 m long and 2 m wide, immediately after the prescribed fire. Runoff, soil erosion and runoff water quality were studied after each rainy event in all plots. Our results reveal that prescribed fire did not significantly affect runoff and soil erosion when low intensity precipitations occur at pine plantations. In relation to water quality, water turbidity, salinity, pH, organic matter content and ionic substances concentrations increased immediately after prescribed burn, nevertheless these changes disappeared over time. We can conclude that prescribed fire can be a useful tool for fuel reduction in Mediterranean pine plantations without wide and long-term impacts to soil losses, or water quality.


Assuntos
Agricultura/métodos , Conservação dos Recursos Naturais/métodos , Fogo , Ecossistema , Monitoramento Ambiental , Fazendas , Fenômenos Geológicos , Região do Mediterrâneo , Pinus , Chuva , Solo , Espanha , Qualidade da Água
20.
J Environ Qual ; 48(2): 485-492, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30951118

RESUMO

Information on the water quality impact of perennial warm-season grasses (WSGs) when grown in marginal lands as dedicated energy crops is limited. We studied how WSGs affected runoff, sediment, and nutrient losses and related near-surface soil properties to those of no-till corn ( L.) on an eroded soil in southwestern Iowa and a center pivot corner in east-central Nebraska. The experiment at the eroded soil was established in 2012, and treatments included 'Liberty' switchgrass ( L.) and no-till continuous corn. The experiment at the pivot corner was established in 2013 with 'Liberty' switchgrass, 'Shawnee' switchgrass, low-diversity grass mixture, and corn. We simulated rainfall at 63.5 ± 2.8 mm h for 1 h to portray 5-yr return periods and measured water erosion in spring 2017. Time to runoff start and runoff depth did not differ between WSGs and corn. On the eroded soil, sediment and nutrient losses did not differ between treatments. At the pivot corner, sediment (0.71 vs. 0.15 Mg ha) and PO-P (0.037 vs. 0.006 kg ha) losses were five times higher in corn than in WSGs. Near-surface soil properties did not differ on the eroded soil, but at the pivot corner, wet aggregate stability was four times higher and residue cover was 34% higher in WSGs than in corn. Water-stable aggregates were negatively correlated with NO-N and PO-P losses. Overall, WSGs can improve water quality in marginally productive croplands, but their effectiveness appears to be site specific.


Assuntos
Agricultura/métodos , Biodegradação Ambiental , Fenômenos Geológicos , Poluição Difusa/prevenção & controle , Produtos Agrícolas , Nebraska , Nitrogênio/análise , Fósforo/análise , Solo , Zea mays
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