Venice 
Italy
The
city of Venice, Italy, lies in the Lagoon of Venice (Laguna Veneta)
which is connected to the Northern Adriatic Sea through the port entrances
of Lido, Malamocco, and Chioggia. The lagoon serves as a drainage basin
for over 1.5 million persons living in the city and adjacent mainland.
For several hundred years, the city and the lagoon have undergone dramatic
configurational and compositional changes due to man’s influence.
The city of Venice is actually made up of 117 different islands linked
by a series of over 150 interconnecting canals and 400 bridges. Tourism,
nearby industrial zones, and lack of adequate municipal treatment facilities
have all put tremendous stress on the lagoon’s fragile ecosystems.
Since the 1920’s, the industrial zones of nearby Porto Marghera
have discharged both industrial chemicals and petroleum products into
the water and atmosphere. In addition the lagoon serves as a major oil
transport harbor in Italy for tankers as well as commercial and pleasure
craft. Indeed, the entire survival of the city has long been completely
dependent upon boat traffic. In addition, although sewage treatment
plants have been built fairly recently for the nearby costal cities,
Venice itself still has no sewage treatment facilities. Pathogenic and
toxic components of untreated municipal waste are still being discharged
directly into Venice’s canals and coastal waters.
Our
early work in the canals and lagoon of Venice was directed toward public
health issues. In order to evaluate the degree of organic pollution
in the area, petroleum hydrocarbons, chlorinated hydrocarbons and fecal
sterols were analyzed in sediment and mussel samples (Mytilus galloprovincialis).
Although the canals in Venice are at least partially flushed by tides,
most canals still have mud bottoms which are ideal for preservation
of chemical pollutants. Petroleum hydrocarbon contamination has been
observed in essentially all areas except the Northern Adriatic. Highest
hydrocarbon concentrations have been found near the industrial zone
of Porto Marghera followed by decreasing concentrations in the Venetian
canals and Veneto Lagoon. Based upon alkylated homolog distributions
of polycyclic aromatic hydrocarbons, fossil fuel combustion appears
to be the major source of these hydrocarbons. Chlorinated hydrocarbons
were present in a wide range of concentrations. The spatial distribution
of these compounds (HCB, HCH, DDT and PCB) could be clearly correlated
with local inputs. The fecal sterol, coprostanol, was analyzed to evaluate
the accumulation dispersal of untreated waste from the city of Venice.
Coprostanol “hotspots” gave indications of where health hazards
may exist for local populations. All contaminants generally showed much
higher concentrations in the interior canals of Venice, and lower concentrations
in the outer edges of the city and Lagoon. This was clearly related
to reduced tidal flushing in the interior canals. Mussels and sediments
show similar trends in the contaminant distributions, however due to
a variety of environmental stresses, mussels are completely absent from
the interior canals where the highest contaminant levels have been observed.
Accumulation studies have shown that over a period of 20 years the levels
of petroleum contamination have decreased with time, due to reduction
of industrial inputs resulting from increased environmental legislation,
and to initiating an aggressive dredging program within the interior
canals.
Representative publications:
Van Vleet, E.S., Fossato, V.U., Sherwin, M.R., Lovett, H.B. and Dolci, F. 1988. Distribution of coprostanol, petroleum hydrocarbons, and chlorinated hydrocarbons in sediments from canals and coastal waters of Venice, Italy. Organic Geochemistry 13: 757-763.
Fossato, V.U., Van Vleet, E.S. and Dolci, F. 1989. Chlorinated hydrocarbons in sediments of Venetian Canals Archivio di Oceanografia e Limnologia 21: 151-161.
Sherwin, M.R., E.S. Van Vleet, V.U. Fossato and F. Dolci. 1993. Coprostanol (5ß-cholestan-3ß-ol) in lagoonal sediments and mussels of Venice, Italy. Marine Pollution Bulletin. 26:501-507.
Wetzel, D.L. and E.S. Van Vleet. 2003. Persistence of petroleum hydrocarbon contamination in sediments of Venice, Italy: 1995 and 1998. Marine Pollution Bulletin. 46:1015-1023.
Wetzel, D.L. and E.S. Van Vleet. 2004. Accumulation and Distribution of Petroleum Hydrocarbons Found in Mussels (Mytilus galloprovincialis) in the Canals of Venice, Italy. Marine Pollution Bulletin. 48:927-936.
Wetzel, D.L. and E.S. Van Vleet. 2004. The use of semipermeable membrane devices (SPMDs) as a proxy for the accumulation of organic pollutants in mussels. Submitted to Environmental Science and Technology.
