20 research outputs found
READING THE SIGNATURES OF CHANGING ENVIRONMENTAL FORCINGS IN SALT-MARSH BIOGEOMORPHIC SYSTEMS
No full textThe question on whether actual tidal morphologies are in equilibrium with current environmental conditions or retain signatures of past climatic changes or human interventions is a classical and fascinating one, furthermore being of intellectual as well as practical interest. Understanding the dynamic response of tidal landscapes to past conditions is critical to predict their response to future environmental changes, such as rate of relative sea-level rise and sediment supply. This is an open and fundamentally important point, particularly in times of natural and anthropogenic changes, during which tidal environments are most exposed to possibly irreversible transformations with far-reaching socio-economic and ecological implications worldwide.
The proposed work aims at analyzing the signatures of changing environmental forcings imprinted in the landscape and in the sedimentary record of the Venice Lagoon to refine our knowledge of tidal landforms dynamics. The thesis is developed following a biogeomorphic approach to the study of salt-marsh landscapes. Marsh biomorphological evolution, in response to changes in the environmental forcings, is analyzed investigating the relative role and mutual interactions and adjustments between physical and biological processes shaping the salt-marsh landscape.
This thesis was carried out through a series of extensive temporal and spatial high-resolution morphological, sedimentological, geochronological and elemental analyses, aimed at exploring the main features of sub-surface marsh samples and lagoonal sediment cores.
The study of sub-surface marsh samples highlights the mutual role of inorganic and organic accretion on salt marshes, which is mainly driven by the inorganic component near the channels, while the organic component largely contributes in the inner-marsh portion. The analyses carried out on sediment cores refine the knowledge of the latest Holocene sedimentary succession of the Venice Lagoon, and furnish a chronostratigraphical model for the evolution over the last two millennia. In particular, for a salt-marsh succession, the analyses highlight the occurrence of a delayed marsh-dynamic response to changing sediment delivery rates
Changes in the wind‐wave field and related salt‐marsh lateral erosion: inferences from the evolution of the Venice Lagoon in the last four centuries
No full textSalt marshes are crucially important ecosystems at the boundary between the land and the sea, that are experiencing
significant losses worldwide mainly dictated by the erosion of their margins. Improving our understanding of the mechanisms controlling
marsh edge erosion is a key step to address conservation issues and salt-marsh response to changes in the environmental forcing.
Here we have employed a complete, coupledWind-Wave Tidal Model (WWTM) to analyse the temporal evolution of the wave field,
and in particular of the mean wave-power density, in the Venice Lagoon over the past four centuries (from 1611 to 2012). We have
then related wave-field changes to the observed erosion patterns determined by comparing recent aerial photographs (1978–2010)
and historical bathymetric data. The results of our analyses from the Venice Lagoon show that, while wave-fields did not significantly
change from 1611 to 1901, a rapid increase in wave-power densities occurred in the last century. This is suggested to depend on the
positive feedback between relevant morphological evolutions and changes in the wave field, both influenced by natural forcing and
anthropogenic pressures.We also emphasize the existence of a strong positive linear relationship between the volumetric marsh erosion
rate and mean wave-power density. We thus suggest that relating salt-marsh lateral erosion rates to properly computed mean
wave-power densities provides a valuable tool to address long-term tidal morphodynamics
MODELLAZIONE DEL CAMPO DI MOTO ONDOSO NELLA LAGUNA DI VENEZIA NEGLI ULTIMI QUATTRO SECOLI
No full textChanges in the wind-wave field within the Venice Lagoon in the last four centuries and related salt-marsh lateral erosion
No full textLinguistic analysis on the example of comic text
No full textDiplomska naloga obravnava jezikovno analizo stripovskega besedila Rdeči alarm avtorja Tomaža Lavriča. Teoretični del zajema opredelitev stripa in umestitev avtorja in dela v prostor slovenskega stripa ter povezavo med jezikoslovjem in stripom, empirični del pa predstavlja rezultate jezikovne analize in potrjuje dve od treh zastavljenih hipotez pri raziskovalnem delu. V stripovskem besedilu so pravopisni odkloni od norme prisotni z namenom poudarka pogovornih prvin. Na leksikalni ravnini se najpogosteje pojavljajo besede in besedne zveze, zaznamovane s kvalifikatorjem pogovorno, torej gre za prevladujočo stilno-zvrstno zaznamovanost. Pojavi se več neuslovarjenih kot uslovarjenih medmetov, kar omogoča nadaljnje raziskovanje te jezikovne ravnine. Splošna ugotovitev diplomskega dela je, da v stripu Rdeči alarm prevladuje značilnost pogovornosti z vsemi prvinami, torej veliko zaznamovane leksike, neuslovarjenih medmetov in pravopisnih odklonov od ustaljene norme, ki so zavestno rabljeni in močno poudarjajo to značilnost literarnega dela.The diploma deals with the linguistic analysis of the comic text Red Alert by Tomaž Lavrič. The theoretical part includes the definition of the comic text and the placement the author and his work in the Slovenian comic text genre. It also defines the connection between linguistics and comic text. The empirical part represents the results of the linguistic analysis and confirms two of three given hypotheses throughout the research.
The deviations from the spelling norm are present in order to emphasize the colloquial elements. Lexical level is the most frequently indicated by the appearance of words and phrases that are marked as colloquial. Therefore, we can talk about the prevailing stylistic and form distinctiveness. The interjections used in the text are mostly not found in dictionaries of Slovene literary language. This enables further research in this linguistic level. The general finding of this work proves that Red Alert has many colloquial elements that are consciously used and strongly emphasize the key feature of this literary work
Aggradation and lateral migration shaping geometry of a tidal point bar: an example from salt marshes of the Northern Venice Lagoon (Italy).
No full textOn the mutual role of salt-marsh inorganic and organic deposition in the Venice Lagoon (Italy)
No full textFluvial response to tectonic deformation: the Ambra Plio-Pleistocene incised-valley deposits (Tuscany, Italy)
No full textSpatial variation of salt-marsh organic and inorganic deposition and organic carbon accumulation: Inferences from the Venice lagoon, Italy
No full textSalt marshes are ubiquitous features of the tidal landscape governed by mutual feedbacks among processes of physical and biological nature. Improving our understanding of these feedbacks and of their effects on tidal geomorphological and ecological dynamics is a critical step to address issues related to salt-marsh conservation and response to changes in the environmental forcing. In particular, the spatial variation of organic and inorganic soil production processes at the marsh scale, a key piece of information to understand marsh responses to a changing climate, remains virtually unexplored. In order to characterize the relative importance of organic vs. inorganic deposition as a function of space, we collected 33 shallow soil sediment samples along three transects in the San Felice and Rigà salt marshes located in the Venice lagoon, Italy. The amount of organic matter in each sample was evaluated using Loss On Ignition (LOI), a hydrogen peroxide (H2O2) treatment, and a sodium hypochlorite (NaClO) treatment following the H2O2 treatment. The grain size distribution of the inorganic fraction was determined using laser diffraction techniques. Our study marshes exhibit a weakly concave-up profile, with maximum elevations and coarser inorganic grains along their edges. The amount of organic and inorganic matter content in the samples varies with the distance from the marsh edge and is very sensitive to the specific analysis method adopted. The use of a H2O2+NaClO treatment yields an organic matter density value which is more than double the value obtained from LOI. Overall, inorganic contributions to soil formation are greatest near the marsh edges, whereas organic soil production is the main contributor to soil accretion in the inner marsh. We interpret this pattern by considering that while plant biomass productivity is generally lower in the inner part of the marsh, organic soil decomposition rates are highest in the better aerated edge soils. Hence the higher inorganic soil content near the edge is due to the preferential deposition of inorganic sediment from the adjacent creek, and to the rapid decomposition of the relatively large biomass production. The higher organic matter content in the inner part of the marsh results from the small amounts of suspended sediment that makes it to the inner marsh, and to the low decomposition rate which more than compensates for the lower biomass productivity in the low-lying inner zones. Finally, the average soil organic carbon density from the LOI measurements is estimated to be 0.044 g C cm-3. The corresponding average carbon accumulation rate for the San Felice and Rigà salt marshes, 132 g C m-2 yr-1, highlights the considerable carbon stock and sequestration rate associated with coastal salt marshes
Latest Holocene depositional history of the southern Venice Lagoon, Italy
No full text Analyzing the signatures of landscape changes in the stratigraphic record is crucial to refine our knowledge of tidal landform dynamics and represents a first step toward the development of predictive morphodynamic models. The southern Venice Lagoon (Italy) is particularly suited to analyze modifications in the depositional environment and, consequently, in the sedimentary record because of the remarkable changes that occurred in the last centuries. We collected 25 cores along a NE–SW linear transect about 5 km long cutting through salt marshes, tidal flats, and subtidal platforms. High-resolution sedimentological analyses defined the spatial arrangement of four deposits along the transect (palustrine, salt marsh, lag, and tidal-flat/subtidal-platform deposits), whose cores were dated through radiocarbon, 210Pb, and 137Cs geochronological analyses. The study succession testifies an evolution from a palustrine freshwater environment to a lagoonal environment over the last 2000 years. The palustrine peat progressively evolved into salt marshes in the 14th century. Salt-marsh aggradation is characterized by different accretion rates over time and occurred in parallel with the decrease in the salt-marsh extent and tidal-flat expansion. Where salt-marsh deposits were locally flooded and impacted by wind waves, a lag deposit developed. As a consequence of the progressive water deepening, organic-rich mud accumulated above the lag. The results, as well as providing the first accretion model for the latest Holocene succession in the southern Venice Lagoon, highlight that the disappearance of salt marshes in this area has to be ascribed to the lateral erosion of their margins, rather than to their progressive drowning. </jats:p
