New method for simultaneous determination of dissolved organic carbon and its stable carbon isotope ratio in liquid samples: environmental applications.

This study reports the development of an all-in-one elemental analyser isotope ratio mass spectrometry (EA-IRMS) system modified for simultaneous analysis of dissolved organic carbon (DOC) concentration and its stable carbon isotope footprint (δ13CDOC) in aqueous samples. The method involves a quantitative oxidation of DOC in a 200 µL liquid sample to CO2, after sample acidification and stripping by nitrogen. The detection limit of the method for DOC quantification was 0.2 mg C/L with an analytical precision of 12 %. Uncertainty of stable isotope determinations was 2 % at 0.2 mg DOC/L, while decreasing to 0.3 % at 20 mg DOC/L. Quantitative oxidation of DOC in aqueous samples was validated by using ring test water samples and Deep Sea reference seawater. The method performances of isotope analysis were evaluated by analysing different isotopic standard solutions. The applicability of the method was tested through the analysis of different environmental types of water, showing that δ13CDOC ranged from - 23.30 to -31.85 ‰, allowing to characterize samples of different environmental origin. The developed method offers several advantages including rapidity, use of small sample volumes and minimal sample pre-treatment, making it a valuable tool for routine DOC concentration measurements paired with isotopic characterization.

Environmental restoration by aquatic angiosperm transplants in transitional water systems: The Venice Lagoon as a case study.

The paper reports the results obtained after 4 years of aquatic angiosperm transplants in areas of the Venice Lagoon (North Adriatic Sea, Mediterranean) where meadows almost disappeared due to eutrophication, pollution and overexploitation of clam resources. The project LIFE12 NAT/IT/000331-SeResto, funded by the European Union, allowed to recolonize the Habitat 1150* (coastal lagoons) in the northernmost part of the lagoon, by extensive manual transplants of small sods or single rhizomes of Zostera marina, Zostera noltei, Ruppia cirrhosa and, in some stations also of Cymodocea nodosa. Over the 4 years of the project more than 75,000 rhizomes were transplanted in 35 stations with the support of local stakeholders (fishermen, hunters and sport clubs). Plants took root in 32 stations forming extensive meadows on a surface of approx. 10 km2 even if some failures were recorded in areas affected by outflows of freshwater rich in nutrients and suspended particulate matter. The rapid recovery of the ecological status of the involved areas was the result of this meadow restoration, which was in compliance with Water Framework Directive (WFD 2000/60/EC) objectives. Moreover, the monitoring of environmental parameters in the water column and in surface sediments allowed to identify the best conditions for successful transplants. Small, widespread interventions and the participation of local stakeholders in the environmental recovery, make this action economically cheap and easily transposable in other similar environments.

Preliminary multi analytical approach to address geographic traceability at the intraspecific level in Scombridae family.

Globalization of seafood product marketing caused the increase of request of an effective fish traceability that enhances the consumer confidence in food safety. In this study, an integrated multi analytical approach based on two different and independent analytical techniques (carbon and nitrogen stable isotopes and fatty acids analysis) was applied in order to identify different fish species and trace their geographical provenience. The investigation was focused on four species (Thunnus thynnus, Thunnus alalunga, Auxis rochei and Scomber scombrus) belonging to the Scombridae family. The DNA barcoding method confirmed genus and species for S. scombrus and A. rochei, but only genus for T. alalunga and T. thynnus. Carbon and nitrogen stable isotopes results evidenced different fish diets and trophic positions, whereas fatty acids analysis displayed that the unsaturated prevailed (∼60 %) over the saturated compounds with a variation among the species and the geographical area in particular for docosahexaenoic and eicosapentaenoic acids percentage. The principal component analysis applied to stable isotopes and fatty acids evidenced a good discrimination among species and their geographical catching area. This multi-disciplinary analytical approach could represent a promising tool to identify the commercial fish and trace their origin in order to guarantee the health of consumers.

Organotin compounds in touristic marinas of the northern Adriatic Sea: occurrence, speciation and potential recycling at the sediment-water interface.

Butyltin compound (BTC) contamination was evaluated in two north Adriatic marinas, San Rocco (Italy) and Lucija (Slovenia). BTC sedimentary concentrations (121 ± 46 and 352 ± 30 ng Sn g-1 in San Rocco and Lucija, respectively) evidenced the past use of antifouling paints, confirmed by the reduced tributyltin content (~ 46%) with respect to the sum of BTC. Elemental and organic carbon isotopic (δ13C) analyses of bulk sediments and its lipid and humic substances were performed in order to evaluate their role in BTC partitioning and preservation. The δ13C of sedimentary bulk and refractory organic matter suggested that diagenetic processes could play a role in the preservation or release of pollutants. No contamination was found in water collected from the benthic chamber and thus, fluxes at the sediment-water interface were not assessed, except for MBT efflux at Lucija (28.9 ng Sn m-2 day-1). Nevertheless, BTC concentrations in porewaters (up to 75 ng Sn l-1) and rather low sediment-porewater partitioning coefficients (Kd) with respect to the data reported in the literature would suggest a potential risk of the reintroduction of BTC into the water column at both sites: at Lucija, sedimentary contamination is high despite the greater Log Kd, whilst at San Rocco, the low BTC concentration is associated with a reduced sediment affinity.

Imposex levels and butyltin compounds (BTs) in Hexaplex trunculus (Linnaeus, 1758) from the northern Adriatic Sea (Italy): Ecological risk assessment before and after the ban.

The aim of this study was to compare imposex and butyltin compounds (BTs) data, collected before and after the organotin ban in 2008, in order to assess temporal and spatial variation of the phenomenon, the decline of BT contamination, and the effects on Hexaplex trunculus population in the coastal area of the northern Adriatic Sea, close to the Venice Lagoon. Both in marine and in lagoon sites, the results obtained in 2013-2015 showed a significant decline in the incidence of imposex in respect to those from the 2002 survey. In 2002, lagoon samples exhibited Relative Penis Size Index (RPSI) higher than marine samples, whereas no differences were detected in the recent survey, when all RPSI values were below 0.6%. Vas Deference Sequence Index (VDSI) mean values were over 4 before the ban introduction and below this value after that, indicating more critical conditions for gastropod population in 2002 rather than in 2013-15. Percentage of sterile females was up to 69% in 2002, whilst in the more recent survey no sterile female was found. Range of BT concentrations in gastropods decreased from 252 to 579 to 16-31ng∑BT/g d.w. BT body burdens varied according to a gender dependant pattern, with higher concentrations observed in females than in males. A first attempt to propose a classification based on BT impact on H. trunculus, according to the Water Framework Directive, revealed that most sites were in Bad ecological status before the ban and attained a Poor/Moderate status after that.

Imposex in Nassarius nitidus (Jeffreys, 1867) as a possible investigative tool to monitor butyltin contamination according to the Water Framework Directive: A case study in the Venice Lagoon (Italy).

Butyltin (TBT, DBT, and MBT) effects on molluscs, especially endocrine disruption in bivalves and gastropods, have been widely investigated. Imposex, the superimposition of male characters onto female gonochoristic Caenogastropods, is the most studied biological effect of TBT. TBT compounds are among the priority hazardous substances within Directives 2000/60/EC (WFD) and 2008/105/EC. The Environmental Quality Standards (EQSs) set by the WFD for TBT are quite difficult to quantify by means of chemical analysis, without the use of expensive and high performance methods. Assuming that EQSs set for TBT were derived from evidence of imposex development at very low concentrations, this specific biomarker could be used as an indirect measure of assessing levels of bioavailable BTs. Therefore, this study aims to validate the use of imposex development as an investigative tool to monitor the bioavailable fraction of BTs within the WFD, by comparing imposex levels and BT concentrations in Nassarius nitidus from the Venice Lagoon. BT concentrations and imposex levels in N. nitidus, collected in 2013, had decreased when compared to previous studies in the same area. Both VDSI and RPLI correlated positively with BT body burden in females, confirming that imposex is a valid tool to monitor bioavailable BTs. However, TBT is still a matter of concern in the Venice Lagoon, as TBT concentrations were still higher than its degradation products suggesting recent fresh TBT inputs in the studied area. To propose imposex levels as an indicator of the impact of BTs within the WFD, classification class boundaries and Ecological Quality Ratios were introduced. As a preliminary attempt, imposex levels were also compared to the OSPAR Commission EcoQOs which linked imposex levels in Nassarius reticulatus with TBT concentrations in water. Based on this comparison the degree of imposex development in the Venice Lagoon suggested that TBT concentrations in water should be over the EQS-AA concentration and, at one site, also over the EQS-MAC. From all the results obtained in this work, it appears that imposex evaluation in N. reticulatus could give information about the ecological status regarding BT compounds under the WFD and also be used to monitor their effects and support chemical analyses until more sensitive methods become available.

Preliminary study to characterize plastic polymers using elemental analyser/isotope ratio mass spectrometry (EA/IRMS).

Plastic waste is a growing global environmental problem, particularly in the marine ecosystems, in consideration of its persistence. The monitoring of the plastic waste has become a global issue, as reported by several surveillance guidelines proposed by Regional Sea Conventions (OSPAR, UNEP) and appointed by the EU Marine Strategy Framework Directive. Policy responses to plastic waste vary at many levels, ranging from beach clean-up to bans on the commercialization of plastic bags and to Regional Plans for waste management and recycling. Moreover, in recent years, the production of plant-derived biodegradable plastic polymers has assumed increasing importance. This study reports the first preliminary characterization of carbon stable isotopes (δ13C) of different plastic polymers (petroleum- and plant-derived) in order to increase the dataset of isotopic values as a tool for further investigation in different fields of polymers research as well as in the marine environment surveillance. The δ13C values determined in different packaging for food uses reflect the plant origin of "BIO" materials, whereas the recycled plastic materials displayed a δ13C signatures between plant- and petroleum-derived polymers source. In a preliminary estimation, the different colours of plastic did not affect the variability of δ13C values, whereas the abiotic and biotic degradation processes that occurred in the plastic materials collected on beaches and in seawater, showed less negative δ13C values. A preliminary experimental field test confirmed these results. The advantages offered by isotope ratio mass spectrometry with respect to other analytical methods used to characterize the composition of plastic polymers are: high sensitivity, small amount of material required, rapidity of analysis, low cost and no limitation in black/dark samples compared with spectroscopic analysis.

A fast and effective routine method based on HS-SPME-GC-MS/MS for the analysis of organotin compounds in biota samples.

This work validated an automated, fast, and low solvent- consuming methodology suited for routine analysis of tributyltin (TBT) and degradation products (dibutyltin, DBT; monobutyltin, MBT) in biota samples. The method was based on the headspace solid-phase microextraction methodology (HS-SPME), coupled with gas chromatographic separation and tandem mass-spectrometry (GC-MS/MS). The effectiveness of the matrix-matched signal ratio external calibration was tested for quantification purposes. The exclusion of matrix influences in the calibration curves proved the suitability of this versatile quantification method. The method detection limits obtained were of 3 ng Sn g(-1) dw for all the analytes. The analysis of references materials showed satisfying accuracy under optimum calibration conditions (% recovery between 87-111%; |Z-scores|<2). The repeatability RSD% and intra-laboratory reproducibility RSD% were lower than 9.6% and 12.6%, respectively. The work proved the remarkable analytical performances of the method and its high potential for routine application in monitoring organotin compounds (OTC).

Evidence of butyltin biomagnification along the Northern Adriatic food-web (Mediterranean Sea) elucidated by stable isotope ratios.

The biomagnification of tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), and total butyltins (ΣBT) was analyzed in the Northern Adriatic food-web (Mediterranean) considering trophodynamic interactions among species and carbon sources in the food-web. Although it is acknowledged that these contaminants bioaccumulate in marine organisms, it is still controversial whether they biomagnify along food-webs. A wide range of species was considered, from plankton feeders to top predators, whose trophic level (TL) was assessed measuring the biological enrichment of nitrogen stable isotopes (δ(15)N). Carbon isotopic signature (δ(13)C) was used to trace carbon sources in the food-web (terrestrial vs marine). At least one butyltin species was detected in the majority of samples, and TBT was the predominant contaminant. A significant positive relationship was found between TL and butyltin concentrations, implying food-web biomagnification. Coherently, the Trophic Magnification Factor resulted higher than 1, ranging between 3.88 for ΣBT and 4.62 for DBT. A negative but not significant correlation was instead found between δ(13)C and butyltin concentrations, indicating a slight decreasing gradient of contaminants concentrations in species according to the coastal influence as carbon source in their diet. However, trophodynamic mechanisms are likely more important factors in determining butyltin distribution in the Northern Adriatic food-web.