Macroalgae,nutrient cycles,and pollutants in the Lagoon of Venice     

A. Sfriso  B. Pavoni  A. Marcomini  A. A. Orio 《Estuaries and Coasts》1992,15(4):517-528

The Lagoon of Venice is a wide, shallow coastal basin that extends for about 50 km along the northwest coast of the Adriatic Sea. The lagoon has been substantially modified through the actions of man over the last century through the artificial control of the hydraulic dynamics of the laggon including the construction of channels to facilitate navigation. The lagoon is subjected to considerable pollutant loading through the drainage of land under cultivation, municipal sewage, and industrial effluents. In this paper are reported the results of observations designed to document recent changes in macroalgal species composition, seasonal cycles of primary producers and nutrient levels, and the effects of the macroalgal community on concentrations of organic and inorganic pollutants. The dominant macroalgae in the lagoon wasUlva rigida, and the levels of plant nutrients and pollutants were influenced by the seasonal cycles of the macroalgal community.  相似文献   

A proposed methodology for deriving tsunami fragility functions for buildings using optimum intensity measures     

Joshua Macabuag  Tiziana Rossetto  Ioanna Ioannou  Anawat Suppasri  Daisuke Sugawara  Bruno Adriano  Fumihiko Imamura  Ian Eames  Shunichi Koshimura 《Natural Hazards》2016,80(2):1257-1278

  相似文献   

Metazoan/microbial biostalactites from present‐day submarine caves in the Mediterranean Sea          下载免费PDF全文

Rossana Sanfilippo  Antonietta Rosso  Adriano Guido  Adelaide Mastandrea  Franco Russo  Robert Riding  Emma Taddei Ruggiero 《Marine Ecology》2015,36(4):1277-1293

Biostalactites formed by metazoan–microbialite associations from three submerged marine caves in the Plemmirio Peninsula (south of Syracuse, Ionian Sea) are randomly distributed and show different sizes and morphologies, as well as variations in surface roughness/smoothness. The biostalactites consist of crusts a few centimeters thick of small serpulids and other metazoans, associated with fine‐grained carbonate; the larger ones often include a nucleus of serpulid tubes (Protula). The metazoans include mainly serpuloideans, sponges, bryozoans and foraminifers but microbial carbonates are also significant components. The composition of both the living communities and thanatocoenoses on the outer surfaces, as well as the composition and fabric of the internal framework, were analysed and used to reconstruct the history of the caves. All of the identified sessile faunas mainly consist of cryptic and sciaphilic dwellers that reflect cave conditions and their variations through time. The distribution pattern, composition and abundance of the present‐day dwellers largely depend on the degree of roughness of the biostalactite surfaces and their positions within the caves. It has been suggested that the Protula specimens in the nuclei represent pioneer populations that formed aggregates during the early cave colonization phase, in response to relatively high food supply from seawater inflow and intruding continental waters. By contrast, the outer metazoan–microbialite carbonates reflect more confined conditions in the caves caused by Holocene sea‐level rises. Hypotheses are proposed for biostalactite growth, taking into account information about the growth rates of some constituents, and evidence of dissolution effects. Similarities and differences between these biostalactites and other Holocene deposits previously described from submarine caves in the Mediterranean Sea and in tropical reefs are discussed.  相似文献   

Large‐scale modelling of channel flow and floodplain inundation dynamics and its application to the Pantanal (Brazil)     

Adriano Rolim da Paz  Walter Collischonn  Carlos E. M. Tucci  Carlos R. Padovani 《水文研究》2011,25(9):1498-1516

For large‐scale sites, difficulties for applying coupled one‐dimensional (1D)/2D models for simulating floodplain inundation may be encountered related to data scarcity, complexity for establishing channel–floodplain connections, computational cost, long duration of floods and the need to represent precipitation and evapotranspiration processes. This paper presents a hydrologic simulation system, named SIRIPLAN, developed to accomplish this aim. This system is composed by a 1D hydrodynamic model coupled to a 2D raster‐based model, and by two modules to compute the vertical water balance over floodplain and the water exchanges between channel and floodplain. Results are presented for the Upper Paraguay River Basin (UPRB), including the Pantanal, one of the world's largest wetlands. A total of 3965 km of river channels and 140 000 km² of floodplains are simulated for a period of 11 years. Comparison of observed and calculated hydrographs at 15 gauging stations showed that the model was capable to simulate distinct, complex flow regimes along main channels, including channel‐floodplain interactions. The proposed system was also able to reproduce the Pantanal seasonal flood pulse, with estimated inundated areas ranging from 35 000 km² (dry period) to more than 120 000 km² (wet period). Floodplain inundation maps obtained with SIRIPLAN were consistent with previous knowledge of Pantanal dynamics, but comparison with inundation extent provided by a previous satellite‐based study indicates that permanently flooded areas may have been underestimated. The results obtained are promising, and further work will focus on improving vertical processes representation over floodplains and analysing model sensitivity to floodplain parameters, time step and precipitation estimates uncertainty. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Temporal and spatial changes of macroalgae and phytoplankton in a Mediterranean coastal area: the Venice lagoon as a case study   总被引：5，自引：0，他引：5  

Sfriso A  Facca C  Ghetti PF 《Marine environmental research》2003,56(5):617-636

Since the late 1980s the lagoon of Venice, a shallow Mediterranean coastal area, has experienced strong environmental changes. Macroalgae, which were the predominant primary producers of the lagoon, reduced markedly, but neither phytoplankton nor seagrasses replaced them. Temporal and spatial changes in macroalgal standing crop (SC) and phytoplankton concentration were investigated between 1987 and 1998. Maps of macroalgal SC show a marked declining trend. Biomass in fresh weight decreased from: 558 ktonnes in 1987, to 85 ktonnes in 1993 and to 8.7 ktonnes in 1998. As a whole, the biomass in 1998 was only 1.6% of the biomass recorded in 1987. Similarly the macroalgal net (NPP) and gross (GPP) primary production decreased from ca. 1502 and 9721 ktonnes year(-1) to ca. 44 and 229 ktonnes year(-1), respectively. In the early 1990s the clam Tapes philippinarum Adams & Reeve and seagrasses, especially Zostera marina Linnaeus, colonised the bottoms free of macroalgae, but the development of intense clam-fishing activities prevented both phytoplankton blooms and seagrass spreading. Maps of chlorophyll a drawn according to data collected in parallel to macroalgal standing crop show unchanged concentrations. Macroalgae changes are enhanced by comparing annual trends in four areas of the central lagoon during 1989-1992 and 1998-1999. In those areas phytoplankton also decreased significantly. Marked changes of some environmental variables strongly associated with the primary production were recorded both during the lagoon mapping and in the areas studied on a yearly basis.  相似文献   

Macrophyte production in a shallow coastal lagoon. Part I: Coupling with chemico-physical parameters and nutrient concentrations in waters     

Adriano Sfriso  Antonio Marcomini 《Marine environmental research》1997,44(4):351-375

Standing crop and production of macroalgae and seagrasses were recorded, together with the main physical and chemical parameters, including nutrient concentrations of the water column and 5-cm top sediment porewater, the grazing pressure and the settled paniculate matter (SPM) in two areas of the central (Lido station) and southern (Petta di Bò station) parts of the Venice lagoon. Then the whole set of data was analysed by multivariate analysis. The highest standing crops of Ulva (Lido station) and Zostera (Petta di Bò station) monitored throughout the year (February 1994–February 1995) were ~ 6.5 and ~ 11.0 kg fwt m⁻², accounting for an annual net production of ~ 20.4 and ~ 20.9 kg fwt m⁻², respectively. The estimated gross production of Zostera was, however, ca 35–55% lower than that of Ulva because of the higher decomposition rate and grazing pressure suffered by the markedly stratified and light-limited free-floating fronds of the macroalga. At the Lido station, the overall grazing pressure accounted for ca 65% of the net Ulva production, but it was found to exceed the total production in the July–August period. Ammonium and orthophosphate concentrations in the water column and sediment porewater were ca 2–3 times higher at the Ulva than at the Zostera station. Considering the N:P atomic ratios, nitrogen, during the quick spring-summer biomass increase, could be temporarily critical for the macrophytic growth, especially at the Lido station. The rates of sediment resuspension and settlement were ca six times higher at the Zostera than at the Ulva station, mainly because of higher sediment coverage by the large free-floating fronds of Ulva. For the contribution of individual variables explained by the principal component analysis, it is shown that the Ulva decomposition at the Lido station and the Zostera production at Petta di Bò were the major factors affecting the total variance.  相似文献   

Recenti progressi nella costruzione degli anemometri elettrici     

Prof. Dott. Ing. Adriano Albin 《Pure and Applied Geophysics》1941,3(1):66-70

Riassunto Dopo aver brevemente delineato le rispettive possibilità di impiego degli anemometri meccanici ed elettrici, l'Autore descrive un nuovo tipo di anemometro elettrico da lui ideato e costruito che presenta due importanti innovazioni: precisa segnalazione della direzione del vento e lettura diretta delle caratteristiche del vento. Difatti, le direzioni che possono essere indicate sono praticamente illimitate pur usando un cavo di collegamento a solo quattro conduttori tra la parte esterna dell'anemometro e gli indicatori situati presso l'opratore.

---

Zusammenfassung Nach eine kurze Schilderung des Verwendungsmöglichkeiten der mechanischen und elektrischen windmesser, beschreibt der Verf. eine von ihm erdachten und konstruierten elektr. Anemometer, welcher die genaue Feststellung der Windrichtung sowie die direkte Ablesung der Eigentümlichkeiten der Windstärke gestattet.

  相似文献   

Substrate influence and temporal changes on periphytic biomass accrual and metabolism in a tropical humic lagoon     

Rafael D. Guariento  Adriano Caliman  Francisco A. Esteves  Reinaldo L. Bozelli  Alex Enrich-Prast  Vinicius F. Farjalla   《Limnologica》2009,39(3):209-218

We performed a field experiment in a tropical humic coastal lagoon to evaluate periphyton biomass accrual and metabolism on three different substrates (1) plastic ribbons, (2) green and (3) senescent leaves of the emergent macrophyte Typha domingensis) over 30 days. The contribution of autotrophic biomass decreased as total biomass increased over the time. Mean periphytic ash free dry weight ranged from 0.8 to 5.6 mg cm⁻², but periphyton chlorophyll a concentrations presented shorter amplitudes, which oscillated from 0.12 to 0.44 μg cm⁻² throughout the experiment. Periphyton metabolism was overall heterotrophic on all substrates, especially on senescent leaves. Our data show that substrate type influenced both biomass accrual and periphyton net productivity and respiration rates throughout periphyton development and highlighted the dominance of heterotrophic metabolism. The periphyton respiration may be subsidized by both water- and substrate-derived allochthonous energy pathways, shedding light on the role of periphytic assemblages to the carbon cycling, as a source of CO₂ to the system.  相似文献   

An approximate nearest neighbors search algorithm for low-dimensional grid locations     

Adriano Petry  André Grahl Pereira  Jonas Rodrigues de Souza 《Earth Science Informatics》2017,10(2):183-196

We propose a new algorithm for the problem of approximate nearest neighbors (ANN) search in a regularly spaced low-dimensional grid for interpolation applications. It associates every sampled point to its nearest interpolation location, and then expands its influence to neighborhood locations in the grid, until the desired number of sampled points is achieved on every grid location. Our approach makes use of knowledge on the regular grid spacing to avoid measuring the distance between sampled points and grid locations. We compared our approach with four different state-of-the-art ANN algorithms in a large set of computational experiments. In general, our approach requires low computational effort, especially for cases with high density of sampled points, while the observed error is not significantly different. At the end, a case study is shown, where the ionosphere dynamics is predicted daily using samples from a mathematical model, which runs in parallel at 56 different longitude coordinates, providing sampled points not well distributed that follow Earth’s magnetic field-lines. Our approach overcomes the comparative algorithms when the ratio between the number of sampled points and grid locations is over 2849:1.  相似文献   

The slope aspect: A predisposing factor for landsliding?     

Marco Capitani  Adriano Ribolini  Monica Bini 《Comptes Rendus Geoscience》2013,345(11-12):427-438

The influence of slope aspect on the distribution of landslides was studied in the Milia and Roglio basins in Tuscany, Italy. For each basin, the new Tuscany region landslide inventory that was initiated in 2010 was used. The landslides were split into separate datasets based on their prevailing movement typology. To assess the results that were obtained from the different slope aspect values, maps of the lithology, slope angle, distances to streams, and distances to tectonic lineaments were included in the bivariate statistical analysis as comparison terms. For each basin, all of the geo-environmental factor maps were compared with the different landslide typologies with GIS software. Pearson's Chi² (χ²) coefficient was used to test the degree of spatial association between each predictor variable and landslide type. In addition, Cramer's V test was used to quantify the strength of the degree of association. Next, a conditional analysis was applied to all of the possible combinations that occurred between the slope aspect and other landslide-predisposing factors. Overall, the slope aspect significantly affected the distribution of superficial landslide types, but apparently not that of other landslide types.  相似文献