Preliminary Estimate of the Reservoir Age in the Lagoon of Venice

Abstract

ABSTRACT. The Lagoon of Venice was formed about 6000 years ago due to the marine transgression associated with the late Pleistocene sea level rise. Already by the time of the Republic of Venice (727-1797 AD) it was recognized that the future of the city and its many historical buildings was strongly correlated with the future of the lagoon itself. During the centuries many engineering projects such as modification of the fluvial systems, construction of coastal barriers, and dredging of navigation channels were carried out to preserve the lagoonal environment. The present-day lagoon is the result of all these processes and covers an area of 540 km 2 with an average depth of 0.6 m. A series of radiocarbon age determinations carried out on material obtained from cores collected in the Lagoon of Venice indicate within the sedimentary units the existence of a number of discontinuities and slumping events due to the highly active lagoonal environment. The evaluation of data obtained from a variety of different materials-both terrestrial and marine-allowed us to determine for the first time the marine reservoir effect in the lagoon of Venice. The discussion includes a comparison with other relevant measurements and a possible explanation to the relatively high reservoir age (1200-1300 yr).

Extreme storms during the last 6500 years from lagoonal sedimentary archives in the Mar Menor (SE Spain)

“…The reservoir age (R(t)) with a value of 1003 ± 62 14 C yr is 600 years higher than the mean marine reservoir age (around 400 years) and may be explained by isolation of the lagoon from the Mediterranean Sea. This high reservoir age value is similar to other estimates in different Mediterranean lagoons (Zoppi et al, 2001;Sabatier et al, 2010).…”

“…The radiocarbon age of lagoonal and marine organisms is usually older than the atmospheric 14 C age and has to be corrected by the substraction of the "reservoir age" (Siani et al, 2001;Reimer and McCormac, 2002;Zoppi et al, 2001;Sabatier et al, 2010;Dezileau et al, 2016b). We evaluated the modern reservoir 14 C age by comparing an age derived from 137 Cs and 210 Pb data and from geochemical analysis of mining-contaminated lagoonal sediments with an AMS 14 C age of a pre-bomb mollusc shell (see Sabatier et al, 2010, for method).…”

Holocene Variations of Radiocarbon Reservoir Ages in a Mediterranean Lagoonal System

“…The calculated modern R(t) value of 943 ± 25 14 C yr is about 600 yr higher than the global mean sea surface reservoir age. This high value, probably due to the relative isolation of the lagoon from marine inputs, is in good agreement with other R(t) estimates in Mediterranean lagoonal systems (Zoppi et al 2001;Sabatier et al 2008). 14 C ages were also obtained on a series of Holocene mollusk shells sampled at different depths of the ~8-m-long core PB06.…”

“…In the northern part of the Lagoon of Venice, Zoppi et al (2001) estimated a high R(t) value of 1200 yr by comparing benthic foraminifera and continental leaves at 1900 cal BP. This area seems to be more isolated from the sea than Pierre Blanche Lagoon, with a strong input of freshwater that explains the larger R(t) values.…”

Links between hydrology and sedimentology in the Lagoon of Venice, Italy

“…The average sedimentation rate in the Lagoon is about 0.5 cm yr -1 , although erosion is prevalent near Malamocco and Chioggia, as indicated by radionuclide studies (Battiston et al, 1988;Pavoni et al, 1992;Adami et al, 1992;Zoppi et al, 2001). Its morphology is characterised by a network of channels of variable depths, estuaries, tidal marshes, mud flats, and open and closed fish ponds.…”