1,720,972 research outputs found
Effects of outcrop-scale structural and diagenetic heterogeneities on flow and mass transport in a porous sandstone aquifer
Get PDFWe apply outcrop-based structural and in-situ petrophysical properties measurements for the construction of flow and mass transport calibrated numerical models in a porous sandstone aquifer. The hydraulic conductivity in this aquifer is influenced by the presence of deformation bands and related carbonate nodules. These heterogeneities are shown to decrease the hydraulic conductivity of the host rock by 2-3 orders of magnitude. The result obtained is robust, given that the models were calibrated with hydrologic field data. Our upscaling methodology for hydraulic conductivity allows inclusion of outcrop-scale structures and diagenetic features by means of inversion of the advective velocity for conservative particles. This approach can be used for easily implementing field data in aquifers or other geofluids reservoir simulators. Our experiments show that the use of an equivalent isotropic hydraulic conductivity approach fails to correctly account for mass transport in porous sandstone aquifers and we recommend implementing, as much as possible, the local heterogeneities and anisotropies in hydraulic conductivity within the model to be able to have a more realistic and conservative estimate of advection and dispersion. Our findings should be helpful to those scientists dealing with geofluids modeling and groundwater pollution
The Influence of Climate Change on the Water Budget in the Regional Park of the Po River Delta (Italy)
No full textAn end-of-the month water balance model called Watbal was used to calculate the components of the hydrologic water budget for several sites of the Regional Park of the Po River Delta (Italy). A sandy soil covered with Pine trees, served as an analogue for the Pinewoods of San Vitale (Ravenna) and the Pinewoods of Cervia, a clay rich soil covered with Swamp Reed served as an analogue for Punte Alberete (Ravenna), and a clay-rich soil with corn simulated agricultural land near Cervia. Both long term measured monthly average temperature and precipitation values served as input as well as three other climate scenarios with increased average temperatures and/or precipitation, to simulate climatic changes in the near future. The modeling results show that the effect of a change in temperature is much more dramatic than a change in precipitation: the increase in evapotranspiration due to average air temperature increase by two degrees, is not compensated by an increase of 2.5 % of the average accumulative monthly precipitation. This effect is more pronounced on clay rich soils than on sandy soils. Clay will release more moisture in warmer times while the soil moisture in sand is very low during the warmest months also now, and cannot decrease much further. The predicted loss of freshwater due to increased evapotranspiration would have a large effect on the water supply for irrigation and drinking water and would alter many of the habitats posing a danger for existing plant and animal communities
Application of analytical diffusion models to outcrop observations: Implications for mass transport by fluid flow through fractures
Get PDFA pavement outcrop with excellent exposure of spatial relationships among joints, veins, small offset normal faults, and associated alteration halos (redox fronts) provided an opportunity to compare predictions of analytical models for reaction front propagation in a fracture-matrix system with a real-field situation. The results have important implications for fluid flow and pollutant transport through a fractured medium. The alteration halos observed suggest that all joints of different sets and most small faults are conductive to meteoric water at shallow depth. On the other hand, veins are local barriers to mass transport by diffusion. By using petrologic and petrophysical data, analytical modeling, and the width of the alteration halos, it was possible to estimate when the fracture network was open to fluid flow. The inferred time for fluid flow and diffusion through the fracture network is sensitive to the porosity n of the rock matrix used in the analytical solutions: 2200 ± 500 years with n = 0.08, 4600 ± 900 years with n = 0.05, and 16,000 ± 4000 with n = 0.02. The second and third age determinations are consistent with the landscape evolution of the area since the end of the last Wűrmian ice age and with the timing required to fill the fractures observed in outcrop. We suggest that analytical modeling is an important tool for the determination of transport and reaction time scales in fractured formations where it is constrained by a robust petrophysical and chemical properties data set
The Influence of Climate Change on the Water Budget in the Regional Park of the Po River Delta (Italy).
No full textAn end-of-the month water balance model called Watbal was used to calculate the components of the hydrologic water budget for several sites of the Regional Park of the Po River Delta (Italy). A sandy soil covered with Pine trees, served as an analogue for the Pinewoods of San Vitale (Ravenna) and the Pinewoods of Cervia, a clay rich soil covered with Swamp Reed served as an analogue for Punte Alberete (Ravenna), and a clay-rich soil with corn simulated agricultural land near Cervia. Both long term measured monthly average temperature and precipitation values served as input as well as three other climate scenarios with increased average temperatures and/or precipitation, to simulate climatic changes in the near future. The modeling results show that the effect of a change in temperature is much more dramatic than a change in precipitation: the increase in evapotranspiration due to average air temperature increase by two degrees, is not compensated by an increase of 2.5 % of the average accumulative monthly precipitation. This effect is more pronounced on clay rich soils than on sandy soils. Clay will release more moisture in warmer times while the soil moisture in sand is very low during the warmest months also now, and cannot decrease much further. The predicted loss of freshwater due to increased evapotranspiration would have a large effect on the water supply for irrigation and drinking water and would alter many of the habitats posing a danger for existing plant and animal communities
The Influence of Three-dimensional Dune Topography on Salt Water Intrusion in Marina Romea, Italy: A Numerical Modeling Study Using LIDAR Data.
No full textThe paper presents a 3-D variable density model of an area about 400m by 500 m including the beach, dunes and part of the Pine forest north east of the tourist town Marina Romea along the Adriatic Coast, Northern Italy. The 3D topography, derived from LIDAR data of the area is imported into this model, to test the hypothesis that the interruption of the dune belt for the construction of bathing establishments on the beach has enhanced saltwater intrusion into the unconfined aquifer underneath the Pine fores
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Effects of Soil salinization on the earthworm Eisenia andrei: life cicle traits and histochemical biomarkers
No full textSalinisation is the process that leads to an excessive increase of water-soluble salts in the soil, and one of the most widespread soil degradation processes. Along the Adriatic Coast of the Emilia-Romagna region in Italy, our area of interest, soil salinisation is enhanced by salt water seepage, caused among others by subsidence and drainage. Salt prevents, limits or disturbs the normal metabolism and nutrient uptake of plants and other soil biota. Biological effects on plants, in particular crop species, are widely studied because of the socio-economical consequences of agricultural soil loss. Impacts on soil fauna are less known, in spite of its importance in determining soil fertility. Salinity might cause a decreased resistance of organisms to other stressors, eventually leading to synergistic effects. Here we report the results of a laboratory experiment that is intended as a first step of an ongoing study on the interactive effects of soil salinity and pesticide contamination on the earthworm Eisenia andrei. A natural silty soil was collected in the field, dried, grounded and sieved through a 2 mm mesh, to eliminate skeleton. Glass containers (223x121 mm, h: 77 mm) were used as experimental chambers; in each container 500 g of dry soil were mixed with 150 ml of spiking solution (NaCl dissolved in distilled water). A control treatment (distilled water) and five NaCl concentrations ranging from 0.1 to 12 g/L were prepared. Each treatment was replicated in two containers. Ten adult worms for each container were incubated in the experimental soils at controlled environmental conditions (20°C, 400-800 lux, 16 h light/8 h dark). After 28 days ofexposure, three life cycle endpoints were assessed: survival, growth, and reproduction (number of laid cocoons). In addition, three histochemical biomarker were determined: lysosomal membrane stability (neutral red retention assay), lipofuscin and neutral lipid accumulation. Soil salinity had significant adverse effects on all the life cycle endpoints, and it was possible to obtain preliminary estimates of effective median concentration (survival: 10±1 g/L, growth: 8±2 g/L, reproduction: 4 g/L). Soil salinisation did not alter the response of the biomarkers analysed in the present work. Although the biomarker sensitivity to pollutants is reported higher that that of life cycle endpoints, it appears they are not impaired by salinity and may be used for future investigations on polluted salinised soils. As an overall, our study indicates that adverse effects on earthworms are possible at levels of soil salinisation still compatible with agricultural land use, even in the absence of other stressors
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