Submarine Groundwater Discharge into the Venice Lagoon: Its Magnitude and Implications (Abstract/Comunicazione in atti di convegno)

Type
Label
  • Submarine Groundwater Discharge into the Venice Lagoon: Its Magnitude and Implications (Abstract/Comunicazione in atti di convegno) (literal)
Anno
  • 2006-01-01T00:00:00+01:00 (literal)
Alternative label
  • J. Rapaglia (1), E. Garcia-Solsona (2), J. Garcia-Orellana (2), H. Bokuniewicz (1), L. Zaggia (3), F. Collavini (3), P. Masque (2), G.M. Zuppi (4), J.K.Cochren (1), A. Beck (1) (2006)
    Submarine Groundwater Discharge into the Venice Lagoon: Its Magnitude and Implications
    in ICCE-2006 30th International Conference on Coastal Engineering, San Diego, California, USA, 2-8 September 2006
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • J. Rapaglia (1), E. Garcia-Solsona (2), J. Garcia-Orellana (2), H. Bokuniewicz (1), L. Zaggia (3), F. Collavini (3), P. Masque (2), G.M. Zuppi (4), J.K.Cochren (1), A. Beck (1) (literal)
Pagina inizio
  • 138 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#titoloVolume
  • ICCE 2006 - International Conference on Coastal Engineering (literal)
Note
  • Abstract (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • 1) Marine Sciences Research Center, Stony Brook University (MRSC-SBU), Stony Brook, NY, USA 2) Institut de Ciència i Tecnologia Ambientals, Universitat Autonoma de Barcelona (ICTA-UAB), Bellaterra, Spain 3) Consiglio Nazionale delle Ricerche, Istituto di Scienze Marine (CNR-ISMAR), Venice, Italy 4) Dipartimento di Scienze Ambientali, Università Cà Foscari di Venezia, Venice, Italy (literal)
Titolo
  • Submarine Groundwater Discharge into the Venice Lagoon: Its Magnitude and Implications (literal)
Abstract
  • The first set of submarine groundwater discharge (SGD) measurements was made in the Venice Lagoon. The Venice Lagoon is a 550 km2 shallow water body (average depth of 100 em), which is connected to the Adriatic Sea by three inlets. It sits atop a series of nine un-confined or semi-confined aquifers with a total thickness of about 1 000 meters (Carbognin et al., 1977). Though the surrounding land is of low relief, and therefore unlikely to support any substantial, water-table hydraulic gradient, freeflowing artesian wells are found. Four hundred SGD measurements were taken between November 2003 and August 2005 using benthic chambers vented to plastic bags in several sites located around the lagoon (including a pristine northern lagoon site and a heavily contaminated site near the Porto Marghera Industrial Zone). The flow rates were variable but averaged 22 cm3 cm-2 d-1 (cm d-1) . These rates were much greater than expected considering the characteristics of the study site. lntegrated measurements of radium isotopes (223 224 226 228Ra) were also made in May-June 2004 and June-July 2005 throughout the lagoon. The integrated radium data was compiled along with the point data collected from the manual seepage devices in order to determine both the magnitude of SGD throughout the lagoon as well as the spatial variability in SGD. Both, the radium mapping and the seepage chamber data, suggest that there are certain areas of high discharge, especially in the northern third of the lagoon. Here flow rates as high as 200 cm d-1 were measured in vented benthic chambers. Flow rates of this magnitude, if representative of even a fraction of the lagoon floor, can easily account for a significant proportion of the overall freshwater balance of the Venice Lagoon, whose surface-water yield averages 35.5 m3/s (Zuliani et al. 2001). Groundwater flowing into the lagoon is driven by the circulation of porewater through marshes augmented with groundwater driven across the sea floor from deeper artesian aquifers in the northern lagoon, whereas, near the industrial zone it is driven by the hydraulic gradient supported by a bulk-headed shoreline. In addition to SGD being a significant source of terrestrial based water in the Lagoon, SGD may provide the major pathway for certain contaminants to enter the lagoonal system as the concentrations of many nutrients and pollutants (e.g. nitrates, phosphates, etc.) are often much higher in groundwater than in seawater (Siomp and Van Capellen 2004). Water samples were collected for analysis in both lagoon sites to test whether SGD could be the primary source for nutrients to enter the lagoon. Ammonium concentration was found to be 2 to 8 fold higher in the device water than in the lagoon water in the northern lagoon, dependent on season, and 10-30 times higher in the waters of the industrial zone. The primary goal of the investigation is to determine the significance of the SGD flux on both the hydrological and chemical budget of the lagoon, especially the role of SGD as a pathway for nutrients to enter the system. In addition the comparison between the pristine northern lagoon site and the industrial site has shed some light on the anthropogenic influence on the water quality of the SGD which enters the lageon, as well as the role that anthropogenic modifications have on the general SGD signature. (literal)
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