ABSTRACT: Background, Aims and ScopeA 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: i) 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 ii) define sustainable and environmentally correct ways of managing sediments which are to
be dredged for navigational purposes or in relation to other interventions (i.e., ex situ management).
MethodsTo examine how various regional and international SQGs ‘classed’ screening risk in Venice Lagoon sediments, data on median
contaminant levels in surface sediments in Venice Lagoon resulting from a literature review were compared to a range of local
and international sediment quality guidelines (SQGs). Then data on sediment contaminant levels in various areas and sub-basins
of Venice Lagoon (main Lagoon, Porto Marghera and Venice City Canals) and in other regional and international transitional
and coastal ecosystems with various levels of human impact (urbanization and industrialization) were evaluated based upon
a selected consensus-based SQG. Finally, screening sediment quality for all of Venice Lagoon was mapped and contoured, relative
to this consensus-based SQG and briefly compared with direct toxicity measurement through a battery of bioassays.
ResultsSQGs allow the sediment areas to be put in terms of potential, or screening, risk. Although there were some differences depending
upon which specific SQGs were applied, the Venice SQGs and other international SQGs provided the same general picture of screening
risk in Venice Lagoon despite geographic differences. 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).
DiscussionThe Venice Lagoon sediments have hazard quotients on the low end of the range of moderately urbanized and industrialized sites
and higher than background case studies reviewed. Hg levels in the Venice Lagoon were generally higher than equivalent sites,
while other contaminants were either equivalent or lower. In Porto Marghera (PM) and Venice City Canals (VC), for many contaminants
of interest, PM, and for some, VC sediments have the highest levels of any case study reviewed. Ranges are high, so in all
cases, remedial or disposal decisions should be based upon site-specific (and preferably tiered) data.
ConclusionsThe use of hazard quotients makes it possible to compare screening risks due to different mixes of contaminants within and
between sites, but results should be interpreted with caution. How these sites rank when compared to some of the other highly
industrialized sites depends upon how data are synthesized and communicated. Actual risk must be evaluated using a weight
of evidence (WOE) approach, as site-specific bioavailability and background levels will differ both regionally and internationally.
Recommendations and PerspectivesWhilst there are subtle differences, the current Venice sediment classifications (A, B and C) ‘performed’ in a similar manner
to SQGs in similar classes, suggesting that regions of Venice Lagoon would not be classified much differently if other SQGs
such as TEL, ERL, PEL, ERM or AET were adopted. The Italian sediment quality objectives, on the other hand, are significantly
more conservative than any other SQGs examined, with the exception of the Flemish Reference values. A number of European nations
are considering criteria based upon contaminant levels in relatively pristine modern sites, or based upon derivations of historical
(pre-anthropogenic) contaminant levels. When used as a standard, such an approach lacks discriminating power, designating
almost all sediments within an urbanized or industrialized region as of concern, or even, in many cases, mandating action
or prohibiting various management approaches in a large percentage of sediments. While generally based upon the laudable desire
to return sites to unimpacted levels, there is a risk that overprotective criteria have the opposite effect: by designating
too large a percentage of sediments as requiring management or control, limited resources may be improperly allocated. Which
set of SQGs is most ‘appropriate’ for the Venice Lagoon sediments depends upon the questions being asked. However, the Venice
classifications are currently being used as pass-fail criteria, without consideration of site-specific conditions. The fact
that they performed similarly to SQGs in similar classes suggests that any work to develop more site-specific SQGs (with the
same general decision classes) would probably not make much difference in how sediments were ultimately classified and managed
unless the fundamental approach was changed from a pass-fail to a tiered and WOE approach integrated in a comprehensive decision
framework. For Venice Lagoon, and for other regions, although SQGs should be developed with care, in a scientifically defensible
and risk-based manner, an equally or more important issue to be addressed is their role in overall decision frameworks.
Journal of Soils and Sediments 04/2012; 7(5):326-341. · 1.86 Impact Factor
ABSTRACT: The 96-h water-only exposure and 10-d sediment toxicity tests with the amphipod Corophium orientale were performed in order to enhance the knowledge about its overall sensitivity and its applicability to Venice Lagoon sediments. The values obtained with cadmium as reference toxicant demonstrated a certain variability of the LC(50); the higher value was found in spring and the lower in late summer. Tests with other pure chemicals (Ni, Total Ammonia, Sodium Dodecyl-Sulphate) showed good discriminatory power; the toxicity gradient observed was: Cd (LC(50) of 3.3 mg/L)>SDS (LC(50) of 8.7 mg/L)>total ammonia (LC(50) of 126mg/L)>Ni (LC(50) of 352 mg/L). Sediment toxicity test results were used to obtain information on non-treatment factors (grain-size, TOC content) that could act as confounding factors, and to develop a site-specific toxicity-score based on minimum significant difference approach. Confounding factors seem not to affect test results. The procedure to develop the toxicity score took into account the relatively lower sensitivity of C. orientale with respect to other amphipods commonly used in toxicity tests (Ampelisca abdita and Rhepoxynius abronius).
Ecotoxicology and Environmental Safety 05/2008; 70(1):174-84. · 2.29 Impact Factor
ABSTRACT: The objective of this study was to carry out a critical comparison of data on the screening quality of surface sediments in Venice Lagoon (VL; main lagoon and its subbasins, Porto Marghera [PM], and Venice City Canals) and in other transitional and coastal ecosystems with various levels of human impact (urbanization and industrialization). To put VL in terms of reference and industrialized sites in the region, case studies were selected from the North Adriatic Region; to gain insight into how VL sediments compared to transitional areas throughout the world, case studies also were selected from a number of regions internationally. In order to compare regional levels of contamination, statistically processed sediment contaminant levels within a region (minimum, maximum, mean, and median), not individual sample values, are compared. The screening quality (relative to a variety of sediment quality guidelines) and the drivers of screening risk (based upon contaminant mixtures) of the VL sediments and other coastal and transitional sites are compared and discussed. The VL sediments have hazard quotients on the low end of the range typical of moderately urbanized and industrialized sites and higher than background conditions among the case studies reviewed. The Hg levels in the VL were generally higher than at other sites, and other contaminants were either equivalent or lower. Although sediments have somewhat higher levels of some contaminants and lower levels of other contaminants in PM and Venice City (VC) canals, levels for most contaminants are comparable to case studies with high levels of anthropogenic impact. For many contaminants of interest, PM (and for some, VC) sediments have some of the highest levels of any case study reviewed. How PM and VC rank when compared to other highly industrialized sites depends upon how data are synthesized and how ranges are taken into account. Actual risk must be evaluated using a weight-of-evidence approach, because natural background levels and site-specific bioavailability will differ both regionally and internationally.
Integrated Environmental Assessment and Management 08/2007; 3(3):415-38.
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.
Integrated Environmental Assessment and Management 08/2007; 3(3):393-414.