Search results for "oceanic"

Posidonia oceanica as a Historical Monitor Device of Lead Concentration in Marine Environment

2005

We show that Posidonia oceanica is able to reliably monitor the variability of environmental lead (Pb). We analyze lead concentration measured in the scales and rhizomes of Posidonia oceanica collected in seven sites along the coasts of the Sicily island and subsequently fractioned them according to a lepidochronological analysis. We measure lead concentration in Posidonia oceanica tissues by using the flame atomic absorption spectrophotometry technique. We compare the measured lead concentration with the estimated lead emission in air due to the gasoline sold and used for combustion in car engines in Sicily. By computation of the Pearson cross-correlation coefficient, we show that lead con…

Influence of hydrodynamic conditions on the production and fate ofPosidonia oceanicain a semi-enclosed shallow basin (Stagnone di Marsala, Western Si…

2004

An integrated approach using hydrodynamic and transport numerical models, lepidochronology and stable isotope analysis was used to investigate how local hydrodynamic conditions influence the primary production and fate of the seagrass Posidonia oceanica in a Mediterranean semi-enclosed marine system (Stagnone di Marsala). The water mass exchange aptitude of different sectors of the basin was analysed, and data collected were used to select two sectors (colonized by Posidonia oceanica showing the lowest and highest water exchange values) for biological analyses. According to the mean dispersal coefficient differences simulated by the hydrodynamic model, growth rate and primary production of …

Chemistry, mineralogy and radioactivity inposidonia oceanicameadows from North-Western Sicily

2004

This paper presents measurements of major, minor, metal trace elements and radionuclides in sediments and in Posidonia oceanica samples from north-western Sicily (Italy). The mineralogical and chemical composition of sediments were determined by X-ray diffraction and X-ray fluorescence techniques, respectively. A flame atomic absorption spectrophotometry was used to measure concentrations of Cu, Zn, Cd and Pb in P. oceanica samples and in sediments. Specific activities of selected radionuclides have been determined by high-resolution gamma spectrometry. Standard statistical analysis was used to assess correlations between different elements and different sample types.

Comparison of the fish assemblages associated with Posidonia oceanica after the partial loss and consequent fragmentation of the meadow

2005

An extensive Posidonia oceanica meadow was partially destroyed by excavation, resulting in areas of seagrass habitat of equal complexity (shoot density) but different heterogeneity (degree of fragmentation). The fish assemblages associated with differently fragmented beds were compared from a landscape perspective. Differences in the fish assemblages were detected, with several species showing different patterns: (1) species that increased their abundance along with the degree of bed fragmentation, (2) species that were more abundant in fragmented beds, but did not show differences between more or less fragmented beds, and (3) species that were mostly abundant in large seagrass patches or i…

Trace metals in “Posidonia oceanica” seagrass from south-eastern Sicily

2005

Heavy-metal concentrations were measured in sediments and tissues of Posidonia oceanica seagrass from south-eastern Sicily (Italy) in order to assess the degree of metal pollution in the coastal area. Seagrasses and sediments were collected at four sites along the south-eastern coast of Sicily. Flame atomic absorption spectrophotometry (FAAS) was used to measure concentrations of Cu, Zn, Cd and Pb. Standard statistical analyses were used to assess significant differences among the levels of the elements measured in different tissues and sediment and spatial distribution. The greatest values of potentially toxic metal concentrations were observed at the station near the industrial sites of A…

Analisi della prateria a Posidonia oceanica (L.) Delile (Najadales, Potamogetonaceae)dell’Area Marina Protetta “Isola di Ustica” (Sicilia nord-occide…

2009

Vengono presentati i risultati di uno studio sul posidonieto dell’Area Marina protetta “Isola di Ustica” (Sicilia nord-occidentale), comprendente l’analisi lepidocronologica, fenologica e il censimento della flora epifita delle foglie e dei rizomi di Posidonia oceanica (L.) Delile (Najadales,Potamogetonaceae). Le osservazioni e i campionamenti sono stati effettuati in nove stazioni distribuite lungo tre transetti. I risultati ottenuti mostrano che attualmente la prateria è complessivamente in una situazione di equilibrio. Ciò indica buone condizioni ambientali anche se non ottimali per la fioritura della pianta dato che come risulta dall’analisi lepidocronologica e dalle osservazioni dirett…

Flow and Heat Transfer in Corrugated Passages: Direct and Large Eddy Simulation and Comparison with Experimental Results

1993

Direct and large-eddy numerical simulations are presented for the transitional and turbulent flow with heat transfer in corrugated passages, representative of compact heat exchangers such as rotary air preheaters (regenerators), at Reynolds number ranging from 103 to 104. Pressure drop and heat transfer results are compared with wind-tunnel experimental data; the agreement is quite satisfactory, and superior to that obtained by more traditional methods.

Phenols content and 2-D electrophoresis protein pattern: a promising tool to monitor Posidonia meadows health state

2007

Abstract Background The endemic seagrass Posidonia oceanica (L.) Delile colonizes soft bottoms producing highly productive meadows that play a crucial role in coastal ecosystems dynamics. Human activities and natural events are responsible for a widespread meadows regression; to date the identification of "diagnostic" tools to monitor conservation status is a critical issue. In this study the feasibility of a novel tool to evaluate ecological impacts on Posidonia meadows has been tested. Quantification of a putative stress indicator, i.e. phenols content, has been coupled to 2-D electrophoretic protein analysis of rhizome samples. Results The overall expression pattern from Posidonia rhizom…

Natural peptides as scaffold for synthetic antibiofilm and antimicrobial peptides (SAAMPs) useful to control antimicrobial resistance spreading

Influence of spatial precipitation sampling on hydrological response at catchment scale

2014

Retrieving precipitation data from raingauge network is a classical and common practice in hydrology and climatology. These data represent the key input in hydrological modeling to reproduce, for example, the characteristics of a flood phenomenon. The accuracy of the model results is strongly dependent on the consistency of the monitoring network in terms of spatial scale, i.e. network density and location of raingauges, and time resolution. In this context, several studies have been carried out to analyze how the rainfall sampling influences the estimation of total runoff volume. The aim of this paper is to use a physically based and distributed-parameter hydrologic model to investigate ho…