Mesocosm experiments identifying hotspots of groundwater upwelling in a water column by fibre optic distributed temperature sensing          下载免费PDF全文

Amaya Irene Marruedo Arricibita  Stefan Krause  Jesus Gomez‐Velez  David M. Hannah  Jörg Lewandowski 《水文研究》2018,32(2):185-199

Lacustrine groundwater discharge (LGD) can substantially impact ecosystem characteristics and functions. Fibre optic distributed temperature sensing (FO‐DTS) has been successfully used to locate groundwater discharge into lakes and rivers at the sediment–water interface, but locating groundwater discharge would be easier if it could be detected from the more accessible water surface. So far, it is not clear if how and under which conditions the LGD signal propagates through the water column to the water surface–atmosphere interface, and what perturbations and signal losses occur along this pathway. In the present study, LGD was simulated in a mesocosm experiment. Under winter conditions, water with temperatures of 14 to 16 °C was discharged at the bottom of a 10 × 2.8‐m mesocosm. Water within this mesocosm ranged from 4.0 to 7.4 °C. Four layers (20, 40, 60, and 80 cm above the sediment) of the 82 cm deep mesocosm were equipped with FO‐DTS for tracing thermal patterns in the mesocosm. Aims are (a) to test whether the positive buoyancy of relatively warm groundwater imported by LGD into shallow water bodies allows detection of LGD at the lake's water surface–atmosphere interface by FO‐DTS, (b) to analyse the propagation of the temperature signal from the sediment‐water interface through the water column, and (c) to learn more about detectability of the signal under different discharge rates and weather conditions. The experiments supported the benchmarking of scale dependencies and robustness of FO‐DTS applications for measuring upwelling into aquatic environments and revealed that weather conditions can have important impacts on the detection of upwelling at water surface–atmosphere interfaces at larger scales.  相似文献   

Magnetic properties as indicators of pedogenic and pyrogenic processes at the Upper Paleolithic site of Kostenki 14     

Anastasiia Kurgaeva  Sergey Sedov  Sol Moreno-Roso  Hermenegildo Barceinas Cruz  Beatriz Ortega Guerrero  Elizabeth Solleiro-Rebolledo  Andrei Sinitsyn 《Geoarchaeology》2024,39(2):143-167

In geoarchaeological studies, there is an issue with distinguishing between natural and anthropogenic signals in pedological paleoarchives. With the pedostratigraphy of the Upper Paleolithic site of Kostenki 14, this issue is reflected by problems with the determination of features of pedogenic and pyrogenic processes. This issue was addressed by means of a thorough analysis of the magnetic properties of paleosols accompanied by micromorphological observations. Most of the humic samples were shown to be a result of pedogenesis, but two samples (a Paleolithic hearth sample and a sample from paleosol IIc) had features of intensely burnt material. The difference in the typical intensity of large-scale (natural or human-induced) and local-scale anthropogenic fire allowed for suggesting that the magnetic properties of the burnt sample were the result of an anthropogenically controlled fire event, that is, a hearth. This study shows that the magnetic properties of paleosols can be used to differentiate anthropogenic activity, in particular—burning, from pedogenic processes. This indicator is especially helpful in finding disturbed combustion features when the hearth structure is lost. This methodology used to demonstrate the local human-induced pyrogenic effect at the Upper Paleolithic site can contribute to the discussion of the niche construction effect of human activities in the Pleistocene.  相似文献   

Separation of PP- and PS-wave reflected seismic data using two-dimensional finite offset common-reflection-surface traveltime approximation     

Raphael Di Carlo Silva dos Santos  João Carlos Ribeiro Cruz  Manuel de Jesus dos Santos Costa 《Geophysical Prospecting》2020,68(7):2046-2063

Recently, the interest in PS-converted waves has increased for several applications, such as sub-basalt layer imaging, impedance estimates and amplitude-versus-offset analysis. In this study, we consider the problem of separation of PP- and PS-waves from pre-stacked multicomponent seismic data in two-dimensional isotropic medium. We aim to demonstrate that the finite-offset common-reflection-surface traveltime approximation is a good alternative for separating PP- and PS-converted waves in common-offset and common shot configurations by considering a two-dimensional isotropic medium. The five parameters of the finite-offset common-reflection-surface are firstly estimated through the inversion methodology called very fast simulated annealing, which estimates all parameters simultaneously. Next, the emergence angle, one of the inverted parameters, is used to build an analytical separation function of PP and PS reflection separation based on the wave polarization equations. Once the PP- and PS-converted waves were separated, the sections are stacked to increase the signal-to-noise ratio using the special curves derived from finite-offset common-reflection-surface approximation. We applied this methodology to a synthetic dataset from simple-layered to complex-structured media. The numerical results showed that the inverted parameters of the finite offset common-reflection-surface and the separation function yield good results for separating PP- and PS-converted waves in noisy common-offset and common shot gathers.  相似文献   

Effect of drainage area on hypsometry from an analysis of small-scale drainage basins in the Siwalik Hills (Central Nepal)     

J.-E. Hurtrez    C. Sol  F. Lucazeau   《地球表面变化过程与地形》1999,24(9):799-808

Hypsometry of drainage basins (area–elevation analysis) has generally been used to infer the stage of geomorphic development and to study the influence of varying forcing factors (i.e. tectonics, climate, lithology) on topography. However, the scale dependence of hypsometry has generally been neglected. In order to assess the scale dependence of hypsometry, this study focuses on the sensitivity of hypsometry to different Digital Elevation Model (DEM) resolutions and on the influence of drainage area. Hypsometry inferred from different DEMs is shown to be robust against variations of their resolution. However, hypsometry appears to be dependent on drainage area. We propose that this scale dependence may reflect the varying importance of river and hillslope processes with basin area. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Supportive elements to the decision-making process in the emergency planning of the Angra dos Reis Nuclear Power Complex,Brazil     

Corbiniano Silva  Luiz Claudio Gomes Pimentel  Luiz Landau  Paulo Fernando Lavalle Heilbron Filho  Fabiana Guimarães Resende Gobbo  Pryscila de Jesus de Sousa 《Environmental Earth Sciences》2017,76(3):133

Accidents in nuclear power plants are problems of great complexity, mainly due to their consequences, such as the population evacuation from the enterprise influence area. The decision-making and emergency plans must be well articulated and require good local geographic space knowledge and the interactions of their environments. This study is a contribution to the emergency plans for the Almirante Álvaro Alberto Nuclear Power Plant, currently the only nuclear complex in Brazil, located in Angra dos Reis, Rio de Janeiro. The study confirmed the region’s main geoenvironmental aspects as winds and rainfall, landslides and population density were evaluated as important elements in the local emergency process. Their integrated analysis supported scenario identification and critical regional points and highlighted population evacuation escape routes. These important results characterized the support to local emergency management actions and guidelines. Furthermore, the geographic information systems was configured as an integrated spatial and temporal analysis platform to associate meteorological, geological/geomorphological and socio-economic data, playing a key role to support the evacuation planning in the event of nuclear power plant accidents.  相似文献   

Revisited mixed extreme wave climate model for reanalysis data bases     

R. Mínguez  F. Del Jesus 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(7):1851-1856

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The Landscape of Diversity in U.S. Higher Education Geography     

Joy K. Adams  Patricia Solís  Jean McKendry 《The Professional geographer》2013,65(2):183-194

Palynological analyses were completed for the A and B horizons of a forested Mollic Hapludalf to determine type, amount, and distribution of pollen and spores within the soil solum. Hypotheses regarding the origin of pollen and the mechanisms of its movement within soil bodies are also advanced. Pollen downwash within the mineral soil seems to be very slow and confined to the uppermost porous and most homogenized part of the solum. The predominance of non-arboreal pollen at depth was believed to be a result of deposition with the loess parent material. High arboreal pollen frequencies in the upper horizons coupled with increases in non-arboreal types at depth indicate gradual ongoing mixing from the present vegetation into the soil.  相似文献   

Exploring the Impact of Contextual Information on Student Performance and Interest in Open Humanitarian Mapping     

Patricia Solís  Patricia R. DeLucia 《The Professional geographer》2013,65(3):523-535

The opportunity to engage university students in authentic, open humanitarian mapping raises important questions about how to guide the quality and productivity of volunteer spatial contributions while providing a valuable learning experience. It presents the unique chance to pique new mappers’ interest, satisfaction, and confidence in spatial technologies in particular, and technology in general, as well as pique their interest in the people and places that are served by the humanitarian mapping projects. This article shares the findings of a study that explores the importance of sharing authentic contextual information about the purpose of the humanitarian mapping task. Two groups of beginner mappers were given mapping tasks, with only one group being provided details on the purpose. Comparisons were made on their respective performance and changes in affective response to a series of questions about technology, education, good citizenship, and empathy. Measures of the quantity and quality of spatial data produced; their respective levels of interest, satisfaction, and confidence in technology; and affective responses before and after mapping show the relative effects of contextual information. Results provide insights about the potential effectiveness of authentic instruction on the performance of mapping as well as the potential effect on mappers themselves. Key Words: citizenship, data quality, empathy, humanitarian mapping, volunteered geographic information.  相似文献   

A high-resolution modeling study of the Western Iberian Margin mean and seasonal upper ocean circulation   总被引：1，自引：0，他引：1  

Rita Nolasco  Ana Cordeiro Pires  Nuno Cordeiro  Bernard Le Cann  Jesus Dubert 《Ocean Dynamics》2013,63(9-10):1041-1062

The mean seasonal hydrography and circulation of the Western Iberian Margin (WIM) are studied by means of a high-resolution configuration of the Regional Oceanic Modeling System. A comparison of 5-year model averages for January and July with climatological datasets shows a general good agreement in the reproduction of the mean water mass properties and hydrographic distribution. We find that there is a prevailing tendency for slope poleward flow at about 80–100 km offshore at all latitudes from the surface to 1,500 m with strong vertical coupling. This northward flow, which is mainly along slope and amounts up to 8–10 cm s^?1, exhibits several mean flow recirculation regions on its way and evidences of an offshore pathway of poleward flow. Transports at different zonal sections further confirm the poleward flow tendency with two peaks of poleward transport in summer (3–10 Sv) and winter (2–7 Sv). The transport time series emphasize the seasonal character of the alongshore circulation and the interannual intrinsic variability of the circulation, since the forcing fields are climatological. As a conceptual essay with the purpose of assessing the Mediterranean Water flow influence on the WIM mean circulation, a second model configuration is setup, where the Mediterranean outflow into the study domain is removed. We find that there is an attenuation of the mesoscale field, but the slope poleward flow intensifies and remains as a mean dynamical feature closer to the upper slope.  相似文献   

Total mercury in terrestrial systems (air-soil-plant-water) at the mining region of San Joaquín,Queretaro, Mexico     

Sergio Martínez-Trinidad  Gilberto Hernández Silva  Juventino Martínez Reyes  Gregorio Solorio Munguía  Sara Solís Valdez  Martha Elena Ramírez Islas  Rocío García Martínez 《Geofísica Internacional》2013,52(1):43-58

Deficient management of cinnabar mining left the San Joaquín region with high concentrations of mercury in its soils (2.4 – 4164 mg kg^-1). Numerous cinnabar mines have contributed to the dispersion of mercury into agricultural (0.5 –314 mg kg^-1) and forest (0.2 – 69 mg kg^-1) soils. Sediments are a natural means of transportation for mercury, causing its spreading, especially in areas near mine entrances (0.6 – 687 mg kg^-1). The nearness of maize crops to mines favors mercury accumulation in the different plant structures, such as roots, stems, leaves, and grain (0.04 – 8.2 mg kg^-1); these being related to mercury volatilization and accumulation in soils. Mercury vapor present in the settlements could indicate a constant volatilization from lands and soils (22 – 153 ng m^-3). The mercury levels found in the soils, in maize grain, and in the air resulted greater than the standards reported by the Official Mexican Norm (NOM) and the World Health Organization (WHO). Mercury in rainwater is due mainly to the presence of suspended atmospheric particles, later deposited on the surface (1.5 – 339 μg |^-1). Mercury dissolution was found in the drinking water (10 – 170 ng |^-1), with concentrations below those established by the NOM and the WHO. The contamination existing in the San Joaquín region does not reach the levels of the world’s greatest mercury producers: Almaden (Spain) and Idrija (Slovenia). It is, however, like that found in other important second degree world producers such as Guizhou (China). The population of San Joaquín, as well as its surrounding environment, are constantly exposed to mercury contamination, thus making a long term monitoring necessary to determine its effects, especially to people.  相似文献