title: Polychlorinated biphenyls in two salt marsh sediments of the Venice Lagoon.
abstract: Polychlorinated biphenyls (PCBs) were measured in two dated salt marsh cores of the Venice Lagoon to assess their input chronology and to evaluate the importance of atmospheric deposition as a source. Sampling sites were chosen in order to evidence the differences between areas located leeward and windward with respect to inputs originating in both the city of Venice and the industrial area. Concentrations of PCB indicators (0.13-15.6 ng g⁻¹) increased gradually from the 1930s, reached maxima from the 1950s to the late 1970s, and then decreased. PCB loadings to marshes are driven by both the atmospheric deposition and the resuspension of subtidal sediments, this latter being more important for heavier congeners. The downwind marsh recorded higher fluxes (0.06-9.72 ng cm⁻² year⁻¹) than the upwind one (0.01-0.53 ng cm⁻² year⁻¹). Recent fluxes are rather consistent with bulk deposition measurements. A higher contribution of CB-101 and CB-118 was detected in the intermediate layers of the downwind site, suggesting a different PCB source for the corresponding time interval. In the other marsh, PCBs showed a rather constant composition at all levels (mostly CB-153, CB-138 and CB-180), accounting for a regional influence. Deep layers showed an enrichment of higher chlorinated congeners at both sites, whereas recent samples conserve the patterns typical of surficial and subsurficial subtidal sediments. The scientific approach adopted in this research can be considered as a sort of methodological procedure for the determination of fluxes and pathways of PCBs through the study of marsh cores.
authors.affiliation: Consiglio Nazionale delle Ricerche (CNR), Istituto di Scienze Marine, U.O.S. di Bologna, Bologna, Italy. cristian.mugnai@bo.ismar.cnr.it
authors.forename: Cristian
authors.initials: C
authors.lastname: Mugnai
authors.forename: Silvia
authors.initials: S
authors.lastname: Giuliani
authors.forename: Luca G
authors.initials: LG
authors.lastname: Bellucci
authors.forename: Claudio
authors.initials: C
authors.lastname: Carraro
authors.forename: Maurizio
authors.initials: M
authors.lastname: Favotto
authors.forename: Mauro
authors.initials: M
authors.lastname: Frignani
mesh_terms: D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D007558:Italy; D011078:Polychlorinated Biphenyls / Q000032:analysis*; D012623:Seawater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data; D053833:Wetlands
chemical_list: D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls