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Long-term time-series are a fundamental prerequisite to understand and detect climate shifts and trends. Understanding the complex interplay of changing ocean variables and the biological implication for marine ecosystems requires extensive data collection for monitoring and hypothesis testing and validation of modelling products. In marginal seas, such as Mediterranean Sea, there are still monitoring gaps, both in time and in space. To contribute filling these gaps, an extensive dataset of dissolved inorganic nutrients profiles (nitrate, NO3; phosphate, PO43−; and silicate, SiO2) have been collected between 2004 and 2017 in the Western Mediterranean Sea and subjected to quality control techniques to provide to the scientific community a publicly available, long-term, quality controlled, internally consistent biogeochemical data product. The database includes 870 stations of dissolved inorganic nutrients sampled during 24 cruises, including temperature and salinity. Details of the quality control (primary and secondary quality control) applied are reported. The data are available in PANGAEA (https://doi.org/10.1594/PANGAEA.904172, Belgacem et al. 2019).

Ocean life relies on the loads of dissolved inorganic nutrients (nitrate, phosphate and silicate) and other micro-nutrients into the euphotic layer. They fuel phytoplankton growth that maintains the equilibrium of the food web. Ocean circulation and physical processes continually drive the large -scale distribution of chemicals toward a homogeneous distribution (Williams and Follows, 2003). The biological and biochemical processes counteract this tendency. Therefore, describing nutrient dynamics is important to understand the overall ecosystem functioning.At global scale, most of the biogeochemical descriptions are based on model simulations and satellite data, since nutrient in situ observations are generally infrequent and not homogeneously distributed in space and time. Climatological mapping is often used to understand the biogeochemical state of the ocean representing monthly, seasonally or annual averaged fields.Within this context, the western Mediterranean Sea climatology (BGC-WMED) presented here is a product derived from in situ observations, derived from various data sources: in total, 2253 in-situ inorganic nutrient profiles over the period 1981-2017 have been used (Medar/MEDATLAS, Fichaut et al., 2003; the CNR-WMED biogeochemical dataset, Belgacem et al., 2020; SeaDataNet data product, https://www.seadatanet.org; Mediterranean Ocean Observing System for the Environment, MOOSE, http://www.moose-network.fr/).Annual mean gridded nutrient fields for the period 1981-2017, and sub-periods 1981-2004 and 2005-2017, on a horizontal 1/4° × 1/4° grid have been produced. The biogeochemical climatology is built on 19 depth levels and for the dissolved inorganic nutrients nitrate, phosphate and orthosilicate. To generate smooth and homogeneous interpolated fields, an advanced N-dimensional version of DIVA, DIVAnd v2.5.1 (Barth et al., 2014), which is based on the variational inverse method (VIM) (Brasseur et al., 1996), has been used.A sensitivity analysis was carried out to assess the comparability of the data product with the observational data. The BGC-WMED has then been compared to other available data products, i.e. the medBFM biogeochemical reanalysis and the biogeochemical component of WOA18.Keywords: Mediterranean Sea, climatology, inorganic nutrient, in situ observations.

The elemental composition of surficial sediments of Venice Lagoon (Italy) in 1987, 1993, 1998 and 2003 were investigated. Zn and Cr concentrations resulted in higher than background levels, but only Cd and Hg were higher than legal quality standards (Italian Decree 2010/260 and Water Framework Directive 2000/60/EC). Contaminants with similar spatial distribution are sorted into three groups by means of correlation analysis: (i) As, Co, Cd, Cu, Fe, Pb, Zn; (ii) Ni, Cr; (iii) Hg. Interannual concentrations are compared by applying a factor analysis to the matrix of differences between subsequent samplings. A general decrease of heavy metal levels is observed from 1987 to 1993, whereas particularly high concentrations of Ni and Cr are recorded in 1998 as a consequence of intense clam fishing, subsequently mitigated by better prevention of illegal harvesting. Due to the major role played by anthropogenic sediment resuspension, bathymetric variations are also considered.

Sediment samples were collected in the Gulf of Gdansk, and the Vistula and Szczecin Lagoons—all located in the coastal zone of the Southern Baltic Sea—just after the total ban on using harmful organotins in antifouling paints on ships came into force, to assess their butyltin and phenyltin contamination extent. Altogether, 26 sampling stations were chosen to account for different potential exposure to organotin pollution and environmental conditions: from shallow and well-oxygenated waters, shipping routes and river mouths, to deep and anoxic sites. Additionally, the organic carbon content, pigment content, and grain size of all the sediment samples were determined, and some parameters of the near-bottom water (oxygen content, salinity, temperature) were measured as well. Total concentrations of butyltin compounds ranged between 2 and 182 ng Sn g−1 d.w., whereas phenyltins were below the detection limit. Sediments from the Gulf of Gdansk and Vistula Lagoon were found moderately contaminated with tributyltin, whereas those from the Szczecin Lagoon were ranked as highly contaminated. Butyltin degradation indices prove a recent tributyltin input into the sediments adjacent to sites used for dumping for dredged harbor materials and for anchorage in the Gulf of Gdansk (where two big international ports are located), and into those collected in the Szczecin Lagoon. Essential factors affecting the degradation and distribution of organotins, based on significant correlations between butyltins and environmental variables, were found in the study area. Electronic supplementary material The online version of this article (doi:10.1007/s11356-013-2115-x) contains supplementary material, which is available to authorized users.

Sediment samples were collected in two Polish ports of international significance--the Port of Gdańsk and the Port of Gdynia (Gulf of Gdańsk, Baltic Sea)--in order to assess their butyltin and phenyltin contamination; this was done in 2008, just after the total ban on using harmful organotins in antifouling paints on ships came into force. Altogether, 21 sampling stations were chosen to present a diversity of port sites: from port canals and shipyards to anchorages and dumping sites. The organic carbon content and grain size of all the sediment samples were determined, and some environmental parameters (oxygen content, salinity) were measured as well. Total concentrations of butyltin compounds in sediment samples were very different and ranged between 1 and 18,520 ng Sn g(-1) d.w. Phenyltin contents were distinctly lower and ranged from below the limit of detection (most samples) to 660 ng Sn g(-1) d.w. The highest concentrations of organotins were found in the shipyards, the maximum total organotin content (19,180 ng Sn g(-1) d.w.) being found in the Gdańsk Ship Repair Yard 'Remontowa'. Butyltin degradation indices indicate a recent tributyltin input into the port sediments. The results obtained from this work prove that the international ban on using organotins may not be enough to protect the marine environment. It is necessary to monitor organotin contamination in ports and establish concentration limits of these compounds for the disposal of dredged material at sea.

Imposex, namely the superimposition of male characteristics, such as penis and vas deferens, on females of gonochoristic gastropods is one of the most harmful effects of TBT on marine organisms. The development of such malformations on marine organisms have led to limitations in the use of TBT in antifouling paints in several countries. Regulation 782/2003 by the EU prohibits the application of organotin compounds. However, in other non EU Mediterranean countries, such as Croatia, the IMO convention has failed to be transposed into domestic legislation and TBT-based antifouling paints are still used. Different restrictions to TBT use and, consequently, likely different levels of TBT contamination between Italy and Croatia gave the cue to this work, whose aims are: (a) monitoring organotin compound levels and imposex degree in Hexaplex trunculus, a common gastropod in the Mediterranean Sea, and an exhibitor of imposex; (b) assessing the level of organotin compounds build-up in the visceral coil and in the rest of the soft body (ROSB) of this organism, in order to try to understand how H. trunculus metabolizes these pollutants; (c) investigating the relationship between organotin compound concentrations in tissues of H. trunculus and the level of imposex development. The results indicate that the incidence of imposex is still high in Italy (Lagoon of Venice) after more than 10 years from the ban of TBT-based antifouling paints. The sampling in Croatian coasts indicates that the absence of restrictions on the use of TBT is likely to cause very high levels of OTC contamination.

In this study, the Active BioMonitoring (ABM) approach has been investigated using species of indigenous (from a pristine site) and transplanted (to a polluted area) hard clam Mercenaria mercenaria as an indicator organism of water/sediment pollution in Tampa Bay, Florida, a highly urbanized and industrialized subtropical estuary. A range of possible induced stress indices was selected and used on the basis of potential pollutant toxicity mechanisms including specific enzymatic responses (MFO as BPH and NADPH cytochrome c reductase, antioxidant enzymes as SOD and caltalase, PDH) and general cellular damage (lysosomal latency, histopathological lesions). The organic sediment contamination compared to the animal body burden revealed bioaccumulation activity in transplanted clams. The marked increases of BPH and catalase activities, together with the significant reduction of lysosomal membrane stability in transplanted animals, suggested their potential for application as biomarkers in subtropical coastal pollution monitoring.

The light absorbing fraction of dissolved organic carbon (DOC), known as chromophoric dissolved organic matter (CDOM) showed wide seasonal variations in the temperate estuarine zone in front of the Po River mouth. DOC concentrations increased from winter through spring mainly as a seasonal response to increasing phytoplankton production and thermohaline stratification. The monthly dependence of the CDOM light absorption by salinity and chlorophyll a concentrations was explored. In 2003, neither DOC nor CDOM were linearly correlated with salinity, due to an exceptionally low Po river inflow. Though the CDOM absorbance coefficients showed a higher content of chromophoric dissolved organic matter in 2004 with respect to 2003, the spectroscopic features confirmed that the qualitative nature of CDOM was quite similar in both years. CDOM and DOC underwent a conservative mixing, only after relevant Po river freshets, and a change in optical features with an increase of the specific absorption coefficient was observed, suggesting a prevailing terrestrial origin of dissolved organic matter.

The concentrations of polychlorinated biphenyls have been determined over a period of 1 year in surface sediments sampled monthly and semi-monthly in the lagoon of Venice. At the sampling station, due to the poor water circulation and an over-abundance of nutrients, macroalgae thrive in spring-summer and standing crops greater than 12 kg m-2 were determined. As a consequence of rapid algal decomposition, sediment PCB concentrations were observed to increase. In particular, on occasions when anoxia occurred at the end of July and all the biomass had decayed, PCB concentrations increased by more than one order of magnitude. In March, when macroalgae started to grow, concentrations were 13 ng g-1 (dry wt); in July-August they exceeded 100 ng g-1. The sediment PCB concentrations were restored to the previous values after algal biomass became negligible, in November. Concentrations of PCBs in young algae fronds were 27 +/- 12 ng g-1, and 121 +/- 4 ng g-1 in older fronds.

Specimens of Nassarius nitidus were collected in seven stations of the Venice Lagoon to assess the levels of tributyltin (TBT) and its metabolites monobutyltin and dibutyltin in the tissues and monitor their effect on organisms, in particular the phenomenon of imposex (superimposition of male sexual characteristics on females). The following values of population indices were found: vas deferens sequence: 1.2 ± 0.7–4.0 ± 0.5; relative penis length: 6–47%. The least impacted station was situated in the northern part of the Lagoon, where females without imposex were found and Butyltin (BuTs) concentrations in the organisms (average sum of BuTs = 43 ± 14 ng Sn g-1 w.) were significantly lower than in the other stations (range of average sum of BuTs: 101 ± 22–217 ± 27 ng Sn g-1 d.w.). Population indices were found to be related to the TBT content in the tissues. In particular VDSI had a significant logarithmic correlation: r = 0.95, n = 8, p less than 0.05.

For almost one century an important steel plant has been active at the Bagnoli industrial area (Naples, Southern Italy). The environmental survey of near shore and offshore sediments has been carried out as fundamental part of a clean up project. The characteristics of the area, supposed type of pollution, national and international protocols in force were taken into consideration in designing sampling schemes and selecting analytical parameters. For this work, sediment grain size, PAHs, PCBs, trace elements, total hydrocarbons and organic matter were considered. Factor analysis evidenced two main types of pollution in the proximity of the industrial plant, both probably attributable to the activity of the industrial site. The first one, due to Cd, Pb, Zn and Mn seems determined by localised activities at the southern part of the plant. The second one, due to Fe and Mn, appears directly linked to the whole contaminated area.

Major, minor and trace elements, loss of ignition, specific surface area, quantities of calcite and dolomite, qualitative mineralogical composition, grain-size distribution and organic micropollutants (PAH, PCB, DDT) were determined on surficial marine sediments sampled during the 1990 ASCOP (Adriatic Scientific Cooperative Program) cruise. Mineralogical composition and carbonate content of the samples were found to be comparable with data previously reported in the literature, whereas geochemical composition and distribution of major, minor and trace elements for samples in international waters and in the central basin have never been reported before. The large amount of information contained in the variables of different origin has been processed by means of a comprehensive approach which establishes the relations among the components through the mathematical–statistical calculation of principal components (factors). These account for the major part of data variance loosing only marginal parts of information and are independent from the units of measure. The sample descriptors concerning natural components and contamination load are discussed by means of a statistical model based on an R-mode Factor analysis calculating four significant factors which explain 86.8% of the total variance, and represent important relationships between grain size, mineralogy, geochemistry and organic micropollutants. A description and an interpretation of factor composition is discussed on the basis of pollution inputs, basin geology and hydrodynamics. The areal distribution of the factors showed that it is the fine grain-size fraction, with oxides and hydroxides of colloidal origin, which are the main means of transport and thus the principal link between chemical, physical and granulometric elements in the Adriatic.

Samples of seven genera of seaweeds (Ulva, Gracilaria, Porphyra, Grateloupia, Undaria, Fucus and Cystoseira), which can be used as environmental biomonitors and in several applications like human alimentation, animal feeding and cosmetics, were collected in four sampling sites in the Lagoon of Venice in spring and autumn 1999 with the aim of determining the contamination due to organic micropollutants (polychlorinated biphenyls. PCBs; chlorinated pesticides; polycyclic aromatic hydrocarbons, PAHs). On an average, most of the considered species were contaminated especially by PAHs (up to 56 ng g(-1) dry wt. (dw)) whereas concentrations of PCBs and pesticides in macroalgal tissues were significantly correlated and did not exceed 5 ng g-1 dw. Among the studied genera the most contaminated by PAHs were Ulva, Undaria and Cystoseira. The highest concentrations of PCBs and pesticides were found in Cystoseira, Fucus and Gracilaria. The least contaminated genus was Porphyra. Although macroalgal specimens were sampled in differently contaminated areas placed from the mainland to the Lido Lagoon mouth, no quantitatively meaningful differences of concentrations were found among the sampling stations., Des échantillons de sept genres de macro-algues (Ulva, Gracilaria, Porphyra, Grateloupia, Undaria, Fucus et Cystoseira) qui peuvent être utilisées comme bio-indicateurs et dans plusieurs autres applications, comme l’alimentation humaine, animale et en cosmétique, ont été recueillis dans quatre stations d’échantillonnage dans la lagune de Venise au printemps et à l'automne 1999 pour déterminer leur contamination en micropolluants organiques (biphényls polychlorés, PCB, pesticides chlorés et hydrocarbures polycycliques aromatiques, HAP). La plupart des espèces considérées sont contaminées essentiellement par des HAP (jusqu’à 56 ng g–1 poids sec), tandis que les concentrations de PCB et de pesticides dans les tissus, étant bien corrélées, ne sont pas plus hautes que 5 ng g–1, p.s. Parmi les genres étudiés, les plus contaminés par HAP sont Ulva, Undaria et Cystoseira. Les concentrations les plus hautes de PCB et de pesticides ont été trouvés dans Cystoseira, Fucus, Gracilaria, tandis que le genre le moins contaminé est Porphyra. Bien que les échantillons de macro-algues aient été recueillis dans différents endroits de la lagune situés entre la terre ferme et l’ouverture du Lido, aucune différence significative n’a été trouvée entre les concentrations déterminées pour chaque station.

The grazing pressure of the macrofaunal invertebrates associated with the biomass of Ulva rigida in the Venice lagoon, their species composition and relationship with environmental variables have been studied. Fifteen sampling campaigns were carried out during different seasons both in the central basin of the lagoon, dominated by macroalgae (especially U. rigida C. Ag.) and in the southern basin, prevalently populated by seagrasses (especially Zostera marina L.). Replicate experiments were conducted in the field by exposing Ulva fronds in net cages of 10 and 1 mm (control) mesh-sizes to allow or prevent grazer entrance. The grazing pressure was determined as Ulva growth rate difference in the cages. In the absence of invertebrate herbivores, Ulva exhibited per cent relative growth rates (%RGRs) ranging from 1.5 to 9.5% day(-1), whereas in their presence the %RGRs were significantly lower (from -2.5 to 3.4% day(-1)) and frequently negative, especially in the station dominated by macroalgae. In this area, peak grazing rates and macrofauna biomasses of up to 8.6% day(-1) and 1,480 g m(-2) fwt (84.4 ash-free dry weight), respectively, were found. On the whole, during in field experiments in the Ulva-dominated station, herbivores removed an amount of biomass whose percentage ranged from 59 to 165% (mean: 103%) of the biomass yield (grazers excluded) found in the cages. These results suggest the possibility that grazers could act as an important factor affecting Ulva production in the Venice lagoon. Macrofauna populations were analysed by means of multivaliate techniques applied to biological variables only and biological and environmental variables together. Data of individual abundance, after a log(x + 1) transformation and the calculation of the Bray-Curtis matrix, were classified using the Cluster Analysis and ordinated by means of the Non-Metric Multidimensional Scaling (MDS) technique, in accordance with the strategies used in the study of multispecies distributions. Finally, biological and environmental variables were analysed together by means of correlation matrices and the Principal Component Analysis.

In this study the clam, Tapes philippinarum, a filter-feeding bivalve living in soft bottoms, was used to investigate the water/sediment pollution in Venice Lagoon (Venice, Italy), a heavily urbanised and industrialised area. To this end, clams collected from indigenous populations in a clean farming area (Val Doga) were transplanted into a relatively low contaminated site (Palude della Rosa) and in a heavily polluted area (Porto Marghera), for 5 weeks. A range of possible induced stress indices were measured, on the basis of potential toxicity mechanisms, including specific enzymatic activities [Bap hydroxylase and NADPH cytochrome c reductase, superoxide dismutase, catalase, glutathione peroxidase and propionaldehyde dehydrogenase (PDH)] and general cellular responses (lysosomal latency). Moreover, chemical analyses (polychlorinated biphenyls, polycyclic aromatic hydrocarbon, DDTs) were carried out on sediments and animal tissues at the beginning and end of the transplantation experiments. The chemical results show an active bio-accumulation activity from sediment in clams translocated to the most polluted area. Correspondingly, biological data indicate marked effects on PDH activity and latency in T. philippinarum from the same site. In contrast, no similar pattern has been observed in the other considered indices, possibly due to antagonistic effects of the complex contaminant mixture present in the environment.

The exchange rates of nitrogen and phosphorus compounds between the Adriatic Sea and the inner parts of the central lagoon of Venice, highly populated by macroalgae, have been estimated by monitoring monthly, for 1 year, a number of stations located both along the main channels and in shallow areas of the lagoon as well as in the sea. Total inorganic nitrogen (TIN), between February and September, was 3–4 times higher in the sea station than in the lagoon. During the same period, the lagoon inflow of TIN through the two channels (Lido and Malamocco) that connect the central lagoon with the sea was 1.2 times higher than the total loads entering the whole lagoon by freshwater sources. In contrast, phoshorus concentrations were higher (15–45%) only in April–June. Four seasonal campaigns were also carried out both in flood and ebb tide at the lagoon mouths. Results confirm the TIN and phosphate inflow from the sea to the lagoon between March and September. On a yearly basis, nutrient concentrations were negatively correlated with chlorinity. The nutrient concentrations monitored concurrently at two stations located on a freshwater stream entering the lagoon (Osellino river) were ∼ 1 order of magnitude higher than those of the lagoon and sea stations. The annual mean phosphate concentration of the Osellino river, monitored in these campaigns, was ∼ 50% of that measured in 1982.

The presence‐absence of macroalgae and/or phytoplankton in some areas of the Venice lagoon and the factors controlling the prevailing of one over the other were tested by monitoring two critical sites over March‐December 1990. One, Sacca Sessola [B1], was the lagoon area more densely populated by macroalgae, vice versa the other, namely Fusina [D] displayed only phytoplankton blooms. For this purpose macroalgae and phytoplankton biomass variations were studied directly in field. In addition, macroalgal biomass growth was studied by resuspending pre‐determined biomass amounts into net cages placed at different depths. These semi‐natural methods were not able to reproduce the real algal growth, however allowed to identify the main causes of phytoplankton blooms and macroalgal absence at Fusina.

PCBs and chlorinated pesticide concentrations have been detected in samples of macroalgae collected in three areas of the lagoon of Venice with different hydro-dynamical characteristics and contamination levels, during a whole year. Halocarbon concentrations in macroalgae were found to depend on a number of factors including the species, the sample location, and frond age. The amounts of PCBs yearly recycled by algae have been estimated and the effect of PCBs stored in biomass onto the concentrations in sediments have been calculated.

The persistent metabolites of the nonionic surfactant nonylphenol polyethoxylates (NPnEO, n=1–18), namely nonylphenol (NP), nonylphenol monoethoxylate (NP1EO) and nonylphenol diethoxylate (NP2EO), were analysed in marine samples including sediment, artificially resuspended sediment and water. The UV-fluorescence high-performance liquid chromatography determination was carried out after Soxhlet extraction with hexane from the sedimentary matrices followed by clean-up on aminosilica minicolumns. Four sampling campaigns at five representative stations of the Venice lagoon were conducted to ascertain temporal and spatial variability of the examined chemicals. A portable resuspending device allowed us to analyse the first 0.01–0.15-mm sediment layer, where the sum of NP, NP1EO and NP2EO was in the range 0.15–13.7 μg g−1 (dry weight basis), at least five times higher than in the underlying 5 cm of sediment. Amounts of resuspended material, and concentrations of NP, NP1EO, NP2EO bound to it, showed a marked seasonal dependence: as much as twice the resuspended material, per unit of sediment surface, was measured in April and July, compared with that in February, but resuspended NP, NP1EO and NP2EO per unit of sediment surface were in February one order of magnitude higher. A major factor responsible for this trend was related to the proliferation of macroalgae which contained an average NP+NP1EO+NP2EO concentration of 0.25±0.15 μg g−1 (dry wt.). In water, NPEO oligomers with up to 13 ethoxy units were found at an overall concentration range of 0.6–4.5 μg l−1.

Four seasonal samplings of lagoon waters were carried out during successive phases of high and low tide at stations located within Venice and its surroundings to monitor various physico-chemical parameters (pH, redox potential, temperature), salinity, nutrient concentrations (nitrogen, phosphorus, carbon compounds) and bacteria (total coliform bacteria). Salinity was used as a parameter for estimating the hydrographic distance from the Adriatic Sea, and for grouping stations into five homogeneous areas. A negative correlation was found between salinity and the concentrations of nutrients. Gradients of increasing concentrations of nutrients were observed at increasing hydrographic distance from the sea. The contributions to eutrophication of fresh waters entering the lagoon from the hinterland and of waste waters from the city have been estimated and found to be comparable. Some necessary interventions for the restoration of the lagoon are suggested.

The Lagoon of Venice is a wide, shallow coastal basin that extends for about 50 km along the northwest coast of the Adriatic Sea. The lagoon has been substantially modified through the actions of man over the last century through the artificial control of the hydraulic dynamics of the laggon including the construction of channels to facilitate navigation. The lagoon is subjected to considerable pollutant loading through the drainage of land under cultivation, municipal sewage, and industrial effluents. In this paper are reported the results of observations designed to document recent changes in macroalgal species composition, seasonal cycles of primary producers and nutrient levels, and the effects of the macroalgal community on concentrations of organic and inorganic pollutants. The dominant macroalgae in the lagoon wasUlva rigida, and the levels of plant nutrients and pollutants were influenced by the seasonal cycles of the macroalgal community.

Nutrient concentrations (P, N compounds and C org ) and chemical-physical parameters (T, DO%, pH, Eh) were monitored in water and sediment in the Lagoon of Venice for one year. Large variations appeared to depend mainly on macroalgal biomass fluctuations which occurred during spring-summer. Sediment was the main sink of nutrients from decomposing macroalgae. Sedimentary phosphorus, nitrogen and carbon increased 75, 160, and 70%, respectively. When macroalgae were negligible, in August–March, nutrients accumulated in sediment were released to the overlying water. Due to the occurrence of anaerobic conditions, the highest concentrations of phosphorus in water were observed in spring-summer. The release of sedimentary nitrogen was higher in September–March. Macroalgal assimilation varied the N:P atomic ratio in water from 50–78 in winter to 0.7–5 in spring-summer. In addition, the N:P ratio in sediment increased from values around 7 in winter to more than 13 between May and July, approaching the N:P values found in macroalgae (8.5–12). Therefore, in spring-summer, the availability of nitrogen in water appeared to be the limiting factor for the macroalgal growth.

Data concerning grain-size distribution, mineralogy, geochemistry, and chlorinated hydrocarbon concentrations, obtained from 246 surface sediment samples collected in the Northern Adriatic sea (Italian area), provide the basis for a multivariate statistical analysis which evaluates the influence of riverine inputs, the differences among various depositional environments and the presence of polluted zones. Cluster analysis applied to grain size has identified nine groups of lithotypes associated with the morphology and the hydrology of the basin. In the Gulf of Venice, principal component analysis on clay minerals and carbonates has permitted recognition of two main areas located north and south of the Brenta river. More subareas correspond to other lithological types. Principal component analysis of nine metal (Hg, Cd, Cu, Pb, Cr, Zn, Fe, Ni, and Co) concentrations reveals that the studied sea area is more complex from the geochemical point of view. Three geochemical zones related to riverine inputs, different lithotypes and specific forms of contamination are identified. High pollution of both halocarbons and heavy metals is associated with fine grain size.

High-performance liquid chromatography (HPLC) has been used for the preparative separation of environmentally relevant aliphatic and polycyclic aromatic hydrocarbons (PAHs), and for quantifying PAHs. Normal-phase HPLC was employed as a fractionation step, whereas the quantitative determination of the PAHs was accomplished by using reversed-phase HPLC. In both cases, GC and GC/MS were used as confirmatory techniques. The concentrations of twelve unsubstituted PAHs in sixteen surface and deeper sediments, taken from the northern and central Adriatic Sea, are reported, together with an evaluation of their dependence upon the percentages of fine material and total organic carbon.

Three cores (length 60 cm, i.d. 10 cm) collected in the most contaminated area of the lagoon of Venice (Italy) were sectioned (14, 12 and 15 sections each respectively) and analysed. Concentrations of heavy metals (Hg, Pb, Cd, Co, Cu, Zn, Cr, Ni, Fe), organic carbon, total nitrogen and total phosphorus were determined. Eh and pH profiles are discussed. Background (pre-industrial) levels for metals were estimated from the deepest sections. The principal component analysis performed on the metal concentrations, normalized on the backgrounds, revealed that two components can account for 99% of the variability. The first clearly represents the mercury pollution, the second weights the contribution of zinc and, to a lesser degree, of other metals (Cd, Cu, Co, Pb) to a contamination mainly caused by discharges of industrial tailings. Radiodating of two cores permitted us to reconstruct the historical evolution of the sediment pollution as related to the development of specific activities in the industrial zone of Porto Marghera. Total phosphorus and organic carbon accumulation was significant in the upper 10–20 cm of the cores.

Potential alkaline phosphatase activity and nutrient concentration have been determined in the seawater, interstitial water and sediments of the most polluted area in the Venice Lagoon, at 6 stations, during three cruises performed in the October/November 1982 period, when a minimum phytoplankton standing crop existed. The relationships between parameters were established by linear regression analysis. The results clearly indicate the important role of alkaline phosphatase (APA) in phosphorus regeneration. Indeed, APA appears to be a good indicator of the degree of nutrient regeneration occurring in surface sediments on a global basis. In the Venice Lagoon a significant nutrient release from the sediments to the overlying lagoon water takes place. This process appears to be at least as important as external contributions in both establishing and controlling the concentration of the nutrients in lagoon waters.

Twenty-three polycyclic aromatic hydrocarbons (PAHs) were analysed by reversed-phase high-performance liquid chromatography coupled with a variable wavelength absorption detector. Compounds not chromatographically resolved were individually quantified by using characteristic UV-VIS absorption maxima programmed over three runs during the chromatographic separation. Detection limits ranging from 0.1 to 1 ng g−1 (dry weight) were found in the analysis of sediment core extracts.

Macroalgae biomass and concentrations of nitrogen, phosphorus and chlorophyll a were determined weekly or biweekly in water and sediments, during the spring-summer of 1985 in a hypertrophic area of the lagoon of Venice. Remarkable biomass production (up to 286 g m −2 day −1 , wet weight), was interrupted during three periods of anoxia, when macroalgal decomposition (rate: up to 1000 g m −2 day −1 ) released extraordinary amounts of nutrients. Depending on the macroalgae distribution in the water column, the nutrients released in water varied from 3·3 to 19·1 μg-at litre −1 for total inorganic nitrogen and from 1·8 to 2·7 μg-at litre −1 for reactive phosphorus. Most nutrients, however, accumulated in the surficial sediment (up to 0·640 and to 3·06 mg g −1 for P and N respectively) redoubling the amounts already stored under aerobic conditions, Phytoplankton, systematically below 5 mg m −3 as Chl. a , sharply increased up to 100 mg m −3 only after the release of nutrients in water by anaerobic macroalgal decomposition. During the algal growth periods, the N:P atomic ratio in water decreased to 0·7, suggesting that nitrogen is a growth-limiting factor. This ratio for surficial sediment was between 6·6 and 13·1, similar to that of macroalgae (8·6–12·0).

Heavy metal (Hg, Pb, Cd, Cu, Cr, Ni, Co, Zn and Fe) concentrations, textural characters and mineralogical compositions have been determined on 246 surface sediment samples from the Northern Adriatic Italian sea area. The relationship between the heavy metals content and the pelite (

Concentrations of chlorinated hydrocarbons (p, p′-DDT, DDD, DDE, polychlorinated biphenyls) and polycyclic aromatic hydrocarbons were determined by GC, GC-MS and HPLC in the 15 sections of a 210Pb radiodated sediment core (50 cm length; 10 cm id) sampled in the lagoon of Venice. From the average sedimentation rate of each section, the fluxes of contaminants to the sediment surface were calculated and interpreted on the basis of the industrial evolution of the Venetian region.