Anthropogenic contaminants in Venice Lagoon sediments and their pore fluids: Results from the SIOSED Project

Gieskes, Joris M.; Han, Seunghee; Rathburn, Anthony E.; Rothwell, Guy; Pérez, M. Elena; Porrachia, Magali; Barbanti, Andrea; Deheyn, Dimitri D.

doi:10.1016/j.marchem.2015.05.008

Cited by 12 publications

(10 citation statements)

References 32 publications

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“…However, a large petrochemical industrial district, the PMIZ, has been in operation since the 1950s at the lagoon-mainland interface, representing the main source of soil and water pollution around the area (e.g., Zonta et al, 2007). Despite an almost 50 km long cut-off wall built up along the canal banks of the PMIZ to prevent discharge of contaminated waters into the lagoon (Paris et al, 2011), results from chemical analyses provided evidence of a high content of Hg, Zn, and other metals in the bottom sediments and pore water not only in front of the industrial site (Gieskes et al, 2015), but also at distance. Although quite gentle in the shallower subsurface, the natural groundwater flow from the mainland seaward has likely transported the contaminants to the lagoon ecosystem over the last decades.…”

Section: Main Insightsmentioning

confidence: 99%

Hydrogeological effects of dredging navigable canals through lagoon shallows. A case study in Venice

Teatini

Isotton²,

Nardean

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. For the first time a comprehensive investigation has been carried out to quantify the possible effects of dredging a navigable canal on the hydrogeological system underlying a coastal lagoon. The study is focused on the Venice Lagoon, Italy, where the port authority is planning to open a new 10 m deep and 3 km long canal to connect the city passenger terminal to the central lagoon inlet, thus avoiding the passage of large cruise ships through the historic center of Venice. A modeling study has been developed to evaluate the short (minutes), medium (months), and long (decades) term processes of water and pollutant exchange between the shallow aquifer system and the lagoon, possibly enhanced by the canal excavation, and ship wakes. An in-depth characterization of the lagoon subsurface along the channel has supported the numerical modeling. Piezometer and sea level records, geophysical acquisitions, laboratory analyses of groundwater and sediment samples (chemical analyses and ecotoxicity testing), and the outcome of 3-D hydrodynamic and computational fluid dynamic (CFD) models have been used to set up and calibrate the subsurface multi-model approach. The numerical outcomes allow us to quantify the groundwater volume and estimate the mass of anthropogenic contaminants (As, Cd, Cu, Cr, Hg, Pb, Se) likely leaked from the nearby industrial area over the past decades, and released into the lagoon from the canal bed by the action of depression waves generated by ships. Moreover, the model outcomes help to understand the effect of the hydrogeological layering on the propagation of the tidal fluctuation and salt concentration into the shallow brackish aquifers underlying the lagoon bottom.

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Section: Main Insightsmentioning

confidence: 99%

Hydrogeological effects of dredging navigable canals through lagoon shallows. A case study in Venice

Teatini

Isotton²,

Nardean

et al. 2017

Hydrol. Earth Syst. Sci.

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show abstract

“…Two reasons support the choice to neglect anisotropy: firstly, the shallow depth of interest that reduces the effect of the geostatic load in decreasing K along the vertical direction (Whipkey and Kirkby, 1978); secondly, bioturbation that enhances the "original" hydraulic conductivity of sedimentary units along the vertical direction. Such activities are typically limited to less than a meter in depth (Gerino et al, 2007), but can affect large thicknesses in highly dynamic coastal depositional environments (Gingras et al, 2015). However, note that a precise calibration of the model is beyond the scope of the study.…”

Section: Model Limitationsmentioning

confidence: 99%

“…The use of these peculiar ecosystems, for fish and shell farming, tourism, and transportation of people and goods, has usually contrasted with the preservation and protection of habitat and biodiversity (Kennish and Paerl, 2010). One typical intervention in coastal systems is dredging of canals and inlets, which may be performed to increase the water volume exchanged with the sea (Gong et al, 2008) or for navigation purposes (Fortunato and Oliveiram, 2007;Healy et al, 1996). Elsewhere, dredging has been used as a source of fill material for adjacent upland development and land reclamation (López et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Ms revised according with Reviewer's #1 and #2 suggestions

Teatini¹

2017

Preprint

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For the first time a comprehensive investigation has been carried out to quantify the possible effects of dredging a navigable canal on the hydrogeological system underlying a coastal lagoon. The study is focused on the Venice Lagoon, Italy, where the port authority is planning to open a new 10 m deep and 3 km long canal to connect the city passenger terminal to the central lagoon inlet, thus avoiding the passage of large cruise ships through the historic center of Venice. A modeling study has been developed to evaluate the short (minutes), medium (months), and long (decades) term processes of water and pollutant exchange between the shallow aquifer system and the lagoon, possibly enhanced by the canal excavation, and ship wakes. An in-depth characterization of the lagoon subsurface along the channel has supported the numerical modeling. Piezometer and sea level records, geophysical acquisitions, laboratory analyses of groundwa-ter and sediment samples (chemical analyses and ecotoxicity testing), and the outcome of 3-D hydrodynamic and computational fluid dynamic (CFD) models have been used to set up and calibrate the subsurface multi-model approach. The numerical outcomes allow us to quantify the groundwater volume and estimate the mass of anthropogenic contaminants (As, Cd, Cu, Cr, Hg, Pb, Se) likely leaked from the nearby industrial area over the past decades, and released into the lagoon from the canal bed by the action of depression waves generated by ships. Moreover, the model outcomes help to understand the effect of the hydrogeological layering on the propagation of the tidal fluctuation and salt concentration into the shallow brackish aquifers underlying the lagoon bottom.

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“…Previous studies on Venice lagoon sediments have emphasized the mapping and evolution of organic carbon (OC) and contaminants in the solid phase of the sediments (Lucchini et al, 2002;Sfriso et al, 2005) in the context of past eutrophication (Pastres et al, 2004) and its relation to oxygen dynamics (Lovato et al, 2013). Other studies (Gieskes et al, 2015) investigated early diagenesis and porewater composition of lagoon sediments, including dissolved sulfide in relation with dredging and disposal of contaminated sediments. The mineralization of organic matter from sewage discharge in the canals network within the historical city, and its contribution to sulfide release was also investigated (Zaggia et al, 2007;Azzoni et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Early Diagenesis in Sediments of the Venice Lagoon (Italy) and Its Relationship to Hypoxia

et al. 2021

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This work focuses on sediments of a shallow water lagoon, located in a densely populated area undergoing multiple stressors, with the goal of increasing the understanding of the links between diagenetic processes occurring in sediments, the dynamics of dissolved oxygen (DO) in the water column, and potential consequences of hypoxia. Sediment data were collected over three consecutive years, from 2015 to 2017, during spring–summer, at five stations. Measured variables included: sediment porosity, grain size and organic carbon content, porewater microprofiles of O2, pH and H2S, porewater profiles of dissolved inorganic carbon (DIC), total alkalinity (TA), NH4+, NO3–, dissolved Fe, and SO42–. In addition, long-term time series of oxygen saturations in the water column (years 2005–2017) were utilized in order to identify the occurrence and duration of hypoxic periods. The results show that the median DO saturation value in summer months was below 50% (around 110 μmol L–1), and that saturation values below 25% (below the hypoxic threshold) can persist for more than 1 week. Sediment stations can be divided in two groups based on their diagenetic intensity: intense and moderate. At these two groups of stations, the average DIC net production rates, estimated trough a steady-state model (Profile) were, respectively, of 2.8 and 1.0 mmol m–2 d–1, SO42– consumption rates were respectively 1.6 and 0.4 mmol m–2 d–1, while diffusive oxygen uptake fluxes, calculated from the sediment microprofile data, were of 28.5 and 17.5 mmol m–2 d–1. At the stations characterized by intense diagenesis, total dissolved sulfide accumulated in porewaters close to the sediment-water interface, reaching values of 0.7 mM at 10 cm. Considering the typical physico-chemical summer conditions, the theoretical time required to consume oxygen down to the hypoxic level by sediment oxygen demand ranges between 5 and 18 days, in absence of mixing and re-oxygenation. This estimation highlights that sediment diagenesis may play a crucial role in triggering and maintaining hypoxia of lagoon waters during the summer season in specific high intensity diagenesis zones. This role of the sediment could be enhanced by changes in regional climate conditions, such as the increase in frequency of summer heat waves.

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Anthropogenic contaminants in Venice Lagoon sediments and their pore fluids: Results from the SIOSED Project

Cited by 12 publications

References 32 publications

Hydrogeological effects of dredging navigable canals through lagoon shallows. A case study in Venice

Hydrogeological effects of dredging navigable canals through lagoon shallows. A case study in Venice

Ms revised according with Reviewer's #1 and #2 suggestions

Early Diagenesis in Sediments of the Venice Lagoon (Italy) and Its Relationship to Hypoxia

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