The sediments of the venice lagoon (Italy) evaluated in a screening risk assessment approach: Part I—application of international sediment quality guidelines

Abstract

A number of studies carried out in recent years have shown the presence of a wide range of contaminants in the Venice Lagoon. It is important to have a good understanding of the ecological quality of Venice Lagoon sediments in order to 1) define and locate areas where a threat to the environment is present and therefore an intervention is needed (i.e., in situ assessment and management); and 2) define sustainable and environmentally correct ways of managing sediments that are to be dredged for navigational purposes or in relation to other interventions (i.e., ex situ management). This study reports on a critical comparison of chemical quality of sediments in Venice Lagoon and its subregions. Data on the Venice Lagoon were compiled from several studies conducted during the past decade on surface sediment contamination; temporal variation and risks for contaminants at depth were not addressed. The comparison of observed pollutant concentrations with local and internationally used sediment quality guidelines (SQGs) was used as a tool to benchmark different sites and for a tier I (screening) ecological risk assessment. Meaning and relevance of a number of SQGs are discussed, together with the options available for carrying out the comparison with sediment data. The screening of the Venice Lagoon sediment quality is discussed from a risk-assessment perspective and appropriate values for use in an in situ-ex situ management framework are suggested. Although there were some differences depending upon which specific SQGs were applied, different SQGs provided the same general picture of screening risk in Venice Lagoon: Although there are geographic differences, median levels for several contaminants in surface sediments exceeded a number of SQGs. Many contaminants exceed threshold effects SQGs, and Hg exceeds probable effects SQGs in most sub-basins except the southern Lagoon. Venice Lagoon south has the lowest screening risk levels, Venice Lagoon central/north has the highest (and is nearest to the Porto Marghera and Venice City Canals sites). Ranges are high in all areas, therefore any remedial or disposal decision should use site-specific data.

Sediment Features and Human Activities Structure the Surface Microbial Communities of the Venice Lagoon

“…Furthermore, C, M, and P were sampled with the same time frequency in 2020. The sites were chosen to cover the four sub-basins, defined according to risk analyses following the international sediment quality guideline of the Lagoon (Apitz et al, 2007; Supplementary Table 2). They are located in the southern (C), in the central (S), in the centralnorth (M and T), and in the northern (P) sub-basins.…”

“…These pollutants were discharged in the water column and then they accumulated in the sediments, by the interaction with the downward fluxes of particulate matter (DePinto et al, 2010). The quality of the Venice Lagoon sediments has been evaluated via different risk assessment screenings: several contaminants exceed sediment quality guidelines thresholds, with the highest screening risk level in the north and central part of the lagoon, near the two hotspots of contamination Porto Marghera and Venice city canals (Apitz et al, 2007).…”

Genome-resolved metagenomics of Venice Lagoon surface sediment bacteria reveals high biosynthetic potential and metabolic plasticity as successful strategies in an impacted environment

“…, cadmium, copper, chromium, zinc) in the sediment of this area (Curran et al 2022 ; Zonta et al 2020 ). Beside the general reduction trend in the Lagoon due to sanitation measures, cadmium, copper, chromium, zinc concentrations are still above the international sediment quality guideline limits (Apitz et al 2007 ; Zonta et al 2020 ). In our dataset, all antibiotic resistant bacteria also carried information for toxic compound resistance (Fig.…”

“…Here, in 2019-2020, we conducted a study in which the sediment prokaryotic communities were characterized with DNA metabarcoding and metagenomics (Banchi et al 2021 ). The surface sediment of five sites, distributed in sub-basins of the Lagoon according to the international risk analyses sediment quality guidelines (Apitz et al 2007 ) were investigated: Chioggia, Marghera, Palude della Rosa, Sacca Sessola, and Tresse. The results highlighted that the microbial communities were significantly influenced by total organic carbon, salinity and grain size, differentiated among sub-basins (mostly due to the rare microbiome), and more stable compared to pelagic communities over time (Banchi et al 2021 ).…”

Contaminants from dredged sediments alter the transcriptome of Manila clam and induce shifts in microbiota composition

“…The chemical composition of Venice lagoon sediments has been extensively studied in the past indicating that sediments stored in industrial canals are that of the most likely sources of chemical contamination to the lagoon environment [ 8 – 10 ]. Among the most important chemicals, high heavy metals concentrations (up to 132, 70, 48, 929 and 8295 μg g −1 for As, Cd, Hg, Pb and Zn, respectively) and PAHs (up to 16,474 μg kg −1 ) were recently described in sediments collected close the industrial area of Porto Marghera [ 9 , 11 ].…”