Search results for " sand"

Mineralogical and chemical variability of fluvial sediments: 1. Bedload sand (Ganga–Brahmaputra, Bangladesh)

2010

This study investigates the natural processes that control concentration of detrital minerals and consequently chemical elements in river sand. The novelty of our approach consists in the systematic integration of detailed textural, petrographical, mineralogical and chemical data, and in the quantitative description and modeling of relationships among mineralogical and chemical variables for each sample and each grain-size class in each sample. Bed sediment in transit in the largest sedimentary system on Earth chiefly consists of fine-grained lithofeldspatho quartzose sand including rich amphibole–epidote–garnet suites, mixed with minor very-fine grained-sand to silt subpopulations containi…

Multiple Non-linear Reservoirs to Model Water Balance Components in Sandy Soils

2023

In the hydrologic literature, to model water flow in unsaturated soils, the Richards equation is usually applied, allowing the main components of the hydrologic cycle, as rainfall partitioning into surface runoff and infiltration, to be determined. The Richards equation is highly nonlinear, making very challenging to derive analytical solutions. Recently, for constant rainfall intensity, under the simplified hypothesis of gravity-driven infiltration, and by assuming a capacitance framework, a simplified solution of the Richards equation that considers the Brooks and Corey hydraulic conductivity function was suggested. By maintaining the assumption that the infiltration process is dominated …

Considerations on systematics of the Phytoseiidae (Acari: Mesostigmata), with definition of a new species group and description of a new species

2015

The authors debate some aspects of the classification of the Phytoseiidae, especially the subfamily Typhlodrominae. Within this taxon, the rhenanus group is the most numerous species group of Typhlodromus (Anthoseius), with 206 nominal species. Detailed observation of morphological characters of the species in this group showed a considerable variation, suggesting the presence of different natural lineages. The discovery of the new species here described, Typhlodromus (Anthoseius) sandrae Ragusa & Tsolakis n. sp., allowed the definition of the new porathi species group. Definition of the new species group, a dichotomous key as well as the description of the new species are given.

9 . Collared Sand Martin Riparia riparia

2022

Collared Sand Martin Riparia riparia

Migration patterns and fat reserves of Curlew Sandpipers Calidris ferruginea at a stopover site in southern Italy

2006

The Volturno Plain, southern Italian coast, is a regular stopover site for Curlew Sandpipers during northward migration. During 1992–1998, 2,177 Curlew Sandpipers were ringed and measured on northward migration; numbers trapped each year fluctuated. Peak passage was during the period 6–10 May, with 94% of birds trapped in the period 1–20 May. Median date of passage of males preceded females by about five days. Using a new visual method to evaluate fat deposition in waders, there was a strong correlation between body weight and visually estimated fat deposits. Birds showed a mass increase of 2.8 g/day. The mean stopover duration was 2.2 days. Only 0.9% of the total catch of Curlew Sandpipers…

Multibeam Sonar System for Detecting Seabed Features

2010

Discriminating between Posidonia oceanica meadows and sand substratum using multibeam sonar

2010

Abstract Di Maida, G., Tomasello, A., Luzzu, F., Scannavino, A., Pirrotta, M., Orestano, C., and Calvo, S. 2011. Discriminating between Posidonia oceanica meadows and sand substratum using multibeam sonar. – ICES Journal of Marine Science, 68: 12–19. High-resolution, multibeam sonar (MBS) (455 kHz) was used to identify two typologies of seabed 8 m deep: Posidonia oceanica meadow and sandy substratum. The results showed that the heterogeneity of the architecture of the P. oceanica canopy and the relatively simple morphology of a sandy substratum can be detected easily by statistical indices such as standard deviation or range-of-beam depth. Based on these indices, an automated classification…

Co-existing with the alien: evidence for environmental control on trophic interactions between a native (Atherina boyeri) and a non-indigenous fish s…

2022

Biological invasions are a widespread problem worldwide, as invasive non-indigenous species (NIS) may affect native populations through direct (e. g., predation) or indirect (e.g., competition) trophic interactions, leading to changes in the food web structure. The trophic relationships of the invasive eastern mosquitofish Gambusia holbrooki and the native big-scale sand smelt Atherina boyeri coexisting in three Mediterranean coastal ponds characterized by different trophic statuses (from oligotrophic to hypereutrophic) were assessed in spring through isotopic niche analysis and Bayesian mixing models. The two fish relied on the distinctive trophic pathways in the different ponds, with the …

Developments of innovative methodologies for Marine Relict Sand Deposits (DSMRs) identification and remotely-sensed shoreline extraction

2023

This Industrial PhD project is a part of the theme set out in point “Blu Growth” of the National Strategy of Intelligent Specialization (SNSI) approved by the European Commission, which defines among the objectives the sector that refers precisely to the marine extraction industry: activities of extraction of natural resources from the sea, that can be reported to the ATECO code “08.12.0, Extraction of gravel, sand; extraction of clays and kaolin". The proposal includes research actions aimed at the development of innovative systems and tools useful to identify and study the area where is higher the probability to detect the submerged relict sand deposits in some sector of the Mediterranean…

EVOLUZIONE DELLA COMPOSIZIONE GRANULOMETRICA DI SABBIE POMICEE SOTTOPOSTE A COMPRESSIONE 1-D FINO AD ALTE PRESSIONI

2012

Nell’articolo si riportano i risultati di uno studio sperimentale sull’evoluzione della composizione granulometrica di sabbie pomicee sottoposte a compressione 1-D fino a pressioni di 100 MPa. La sperimentazione è stata eseguita su sabbie asciutte con coefficiente di uniformità compreso tra 1.18 e 1.66 e con diametro iniziale dei grani compreso tra 0.18 e 2mm. Il crushing dei grani è significativo per tutte le granulometrie indagate a partire da pressioni efficaci basse (dell’ordine di appena 150 kPa). I risultati della ricerca dimostrano che, anche per queste sabbie dotate di un doppio ordine di pori – intergranulari e intragranulari - esiste una composizione granulometrica limite superior…