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Investigation of Residence Time and Groundwater Flux in Venice Lagoon: Comparing Radium Isotope and Hydrodynamical Models
Biology Faculty Publications
  • John Rapaglia, Sacred Heart University
  • Christian Ferrarin, National Research Council of Italy
  • Luca Zaggia, National Research Council of Italy
  • W. S. Moore, University of South Carolina - Columbia
  • Georg Umgiesser, National Research Council of Italy
  • Ester Garcia-Solsona, Universitat Autònoma de Barcelona
  • Jordi Garcia-Orellana, Universitat Autònoma de Barcelona & SUNY Stony Brook
  • Pere Masqué, Universitat Autònoma de Barcelona
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The four naturally-occurring isotopes of radium were coupled with a previously evaluated hydrodynamic model to determine the apparent age of surface waters and to quantify submarine groundwater discharge (SGD) into the Venice Lagoon, Italy. Mean apparent age of water in the Venice Lagoon was calculated using the ratio of 224Ra to 228Ra determined from 30 monitoring stations and a mean pore water endmember. Average apparent age was calculated to be 6.0 d using Ra ratios. This calculated age was very similar to average residence time calculated for the same period using a hydrodynamic model (5.8 d). A mass balance of Ra was accomplished by quantifying each of the sources and sinks of Ra in the lagoon, with the unknown variable being attributed to SGD. Total SGD were calculated to be 4.1 ± 1.5, 3.8 ± 0.7, 3.0 ± 1.3, and 3.5 ± 1.0 × 1010 L d−1 for 223,224,226, 228Ra, respectively, which are an order of magnitude larger than total mean fluvial discharge into the Venice Lagoon (3.1 × 109 L d−1). The SGD as a source of nutrients in the Venice Lagoon is also discussed and, though significant to the nutrient budget, is likely to be less important as the dominant control on SGD is recirculated seawater rather than freshwater.
Citation Information
Rapaglia, John, et al. "Investigation of Residence Time and Groundwater Flux in Venice Lagoon: Comparing Radium Isotope and Hydrodynamical Models." Journal of Environmental Radioactivity 101.7 (2010): 571–581.