Evidence of small microplastics in waters and sediments of the Venice Lagoon: quantitative analysis and polymer identification using Micro-FTIR

Microplastics are emerging pollutants in all environmental compartments (e.g. water, soil, sediments, etc.). Their contamination is well documented since 1970’s, although specific references to this topic were made in the US and in Europe in 2008. Microplastic particles are generally classified according their sizes, but the classification has been subject of lengthy debates. Finally, the European Chemical Agency (ECHA, 2019) has proposed the definition of microplastic as “a material composed of solid polymer-containing particles, to which additives or other substances may have been added, with particle dimensions ranging from 1 nm to 5 mm and with fiber lengths ranging from 3 nm to 15 mm and length to diameter ratio of >3. Furthermore, ECHA has firmly stated the need of polymer identification when analyzing microplastics. In literature several methods have been employed, especially microscopic methods which do not allow the identification of polymers. In these studies only a subset of samples was analyzed via FTIR. In several studies only large microplastics were studied and small microplastics were neglected, especially in water studies, since the mesh sizes of manta trawls can be either 330 µm or 100 µm. In this study small microplastics (1-100 µm) were studied in sediments and waters of the Venice Lagoon using micro-FTIR. These small particles can be mistaken as food particles and then ingested by the biota. Small microplastics can cause damages and obstructions of gastrointestinal tract, and they can be accumulated within the organisms along the trophic net. A method of purification, quantification and polymer identification was developed. Six sites in the Venice Lagoon were studied; preliminary findings showed differences among the sites studied

Quantification and characterization of additives, plasticizers, and small microplastics (5-100 μm) in highway stormwater runoff

Highway stormwater (HSW) runoff is a significant pathway for transferring microplastics from land-based sources to the other surrounding environmental compartments. Small microplastics (SMPs, 5-100 μm), additives, plasticizers, natural, and nonplastic synthetic fibers, together with other components of micro-litter (APFs), were assessed in HSW samples via Micro-FTIR; oleo-extraction and purification procedures previously developed were optimized to accomplish this goal. The distribution of SMPs and APFs observed in distinct HSW runoff varied significantly since rainfall events may play a crucial role in the concentration and distribution of these pollutants. The SMPs' abundance varied from 11932 ± 151 to 18966 ± 191 SMPs/L. The dominating polymers were vinyl ester (VE), polyamide 6 (PA6), fluorocarbon, and polyester (PES). The APFs' concentrations ranged from 12825 ± 157 to 96425 ± 430 APFs/L. Most APFs originated from vehicle and tire wear (e.g., Dioctyl adipate or 5-Methyl-1H-benzotriazole). Other sources of these pollutants might be pipes, highway signs, packaging from garbage debris, road marking paints, atmospheric deposition, and other inputs. Assessing SMPs in HSW runoff can help evaluating the potential threat they may represent to receiving water bodies and air compartments. Besides, APFs in HSW runoff may be efficient proxies of macro- and microplastic pollution

Microplastic accumulation in benthic invertebrates in Terra Nova Bay (Ross Sea, Antarctica)

Microplastic contamination of the benthic invertebrate fauna in Terra Nova Bay (Ross Sea, Antarctica) was determined. Twelve macrobenthic species, characterized by different feeding strategies, were selected at 3 sampling sites at increasing distance from the Italian Scientific Base (Mario Zucchelli, Camp Icarus, Adelie Cove). The 83% of the analyzed macrobenthic species contained microplastics (0.01–3.29 items mg−1). The size of the particles, measured by Feret diameter, ranged from 33 to 1000 µm with the highest relative abundance between 50 and 100 µm. Filter-feeders and grazers displayed values of microplastic contamination from 3 to 5 times higher than omnivores and predators, leading to the hypothesis that there is no evident bioaccumulation through the food web. The prevalent polymers identified by micro-FTIR were nylon (86%) and polyethylene (5%); other polymers identified in Antarctic benthos were polytetrafluoroethylene, polyoxymethylene, phenolic resin, polypropylene, polystyrene resin and XT polymer. Keywords: Antarctica, Benthos, Microplastics, Food web, FTIR, Nile re

A multibiomarker approach in clams (Ruditapes philippinarum) for a toxicological evaluation of dredged sediments

The Lagoon of Venice is often dredged for channel maintenance. To avoid harmful consequences to the ecosystem, a proper disposal of bottom sediments requires a preliminary evaluation of its potential toxicity before excavation. Here we evaluated the effects of polluted sediments on clams (Ruditapes philippinarum) using a multibiomarker approach. Bivalves were exposed for 3 and 14 days to five sediment samples collected along a navigation canal between Venice historical centre and the industrial area of Porto Marghera. Immunological, antioxidant, detoxification, and neurotoxicity biomarkers were analysed in haemolymph, gill, and digestive gland. As a control, sediment collected far from pollution sources was used. Two experiments were performed to assess potential seasonal/gametogenic influence in clam sensitivity. A different response of clam biomarkers was observed during the two experiments and among sampling sites. Clams’ digestive gland resulted to be the most sensitive tissue analysed showing significant differences among sites in all biomarkers analysed. Greater differences were present due to seasonality rather than exposure. The concentrations of metals and organic pollutants increased from the city centre to the industrial area, highlighting the influence that industrial activities had on the lagoon ecosystem. However, bioaccumulation in clams did not follow the same clear pattern, suggesting low bioavailability of compounds due to relatively high organic matter content. Biomarkers modulation was mainly driven by metals, both present in sediments and bioaccumulated. In comparison, effects of organic pollutants on the biomarkers tested were negligible. Other sources of contamination not investigated (e.g. pesticides) were suggested by neurotoxicity biomarkers alteration

Hydrogeological effects of dredging navigable canals through lagoon shallows. A case study in Venice

For the first time a comprehensive investigation has been carried out to quantify the possible effects of dredging a navigable canal on the hydrogeological system underlying a coastal lagoon. The study is focused on the Venice Lagoon, Italy, where the port authority is planning to open a new 10m deep and 3km long canal to connect the city passenger terminal to the central lagoon inlet, thus avoiding the passage of large cruise ships through the historic center of Venice. A modeling study has been developed to evaluate the short (minutes), medium (months), and long (decades) term processes of water and pollutant exchange between the shallow aquifer system and the lagoon, possibly enhanced by the canal excavation, and ship wakes. An in-depth characterization of the lagoon subsurface along the channel has supported the numerical modeling. Piezometer and sea level records, geophysical acquisitions, laboratory analyses of groundwater and sediment samples (chemical analyses and ecotoxicity testing), and the outcome of 3-D hydrodynamic and computational fluid dynamic (CFD) models have been used to set up and calibrate the subsurface multi-model approach. The numerical outcomes allow us to quantify the groundwater volume and estimate the mass of anthropogenic contaminants (As, Cd, Cu, Cr, Hg, Pb, Se) likely leaked from the nearby industrial area over the past decades, and released into the lagoon from the canal bed by the action of depression waves generated by ships. Moreover, the model outcomes help to understand the effect of the hydrogeological layering on the propagation of the tidal fluctuation and salt concentration into the shallow brackish aquifers underlying the lagoon bottom.Facultad de Ciencias Naturales y MuseoCentro de Investigaciones Geológica

Contaminants from dredged sediments alter the transcriptome of Manila clam and induce shifts in microbiota composition

Background The reuse of dredged sediments in ports and lagoons is a big issue as it should not affect the quality and the equilibrium of ecosystems. In the lagoon of Venice, sediment management is of crucial importance as sediments are often utilized to built-up structures necessary to limit erosion. However, the impact of sediment reuse on organisms inhabiting this delicate area is poorly known. The Manila clam is a filter-feeding species of high economic and ecological value for the Venice lagoon experiencing a drastic decline in the last decades. In order to define the molecular mechanisms behind sediment toxicity, we exposed clams to sediments sampled from different sites within one of the Venice lagoon navigable canals close to the industrial area. Moreover, we investigated the impacts of dredged sediments on clam’s microbial communities. Results Concentrations of the trace elements and organic chemicals showed increasing concentrations from the city of Venice to sites close to the industrial area of Porto Marghera, where PCDD/Fs and PCBs concentrations were up to 120 times higher than the southern lagoon. While bioaccumulation of organic contaminants of industrial origin reflected sediments’ chemical concentrations, metal bioaccumulation was not consistent with metal concentrations measured in sediments probably due to the activation of ABC transporters. At the transcriptional level, we found a persistent activation of the mTORC1 signalling pathway, which is central in the coordination of cellular responses to chemical stress. Microbiota characterization showed the over-representation of potential opportunistic pathogens following exposure to the most contaminated sediments, leading to host immune response activation. Despite the limited acquisition of new microbial species from sediments, the latter play an important role in shaping Manila clam microbial communities. Conclusions Sediment management in the Venice lagoon will increase in the next years to maintain and create new canals as well as to allow the operation of the new mobile gates at the three Venice lagoon inlets. Our data reveal important transcriptional and microbial changes of Manila clams after exposure to sediments, therefore reuse of dredged sediments represents a potential risk for the conservation of this species and possibly for other organisms inhabiting the Venice lagoon

Hydrogeological effects of dredging navigable canals through lagoon shallows. A case study in Venice

For the first time a comprehensive investigation has been carried out to quantify the possible effects of dredging a navigable canal on the hydrogeological system underlying a coastal lagoon. The study is focused on the Venice Lagoon, Italy, where the port authority is planning to open a new 10m deep and 3km long canal to connect the city passenger terminal to the central lagoon inlet, thus avoiding the passage of large cruise ships through the historic center of Venice. A modeling study has been developed to evaluate the short (minutes), medium (months), and long (decades) term processes of water and pollutant exchange between the shallow aquifer system and the lagoon, possibly enhanced by the canal excavation, and ship wakes. An in-depth characterization of the lagoon subsurface along the channel has supported the numerical modeling. Piezometer and sea level records, geophysical acquisitions, laboratory analyses of groundwater and sediment samples (chemical analyses and ecotoxicity testing), and the outcome of 3-D hydrodynamic and computational fluid dynamic (CFD) models have been used to set up and calibrate the subsurface multi-model approach. The numerical outcomes allow us to quantify the groundwater volume and estimate the mass of anthropogenic contaminants (As, Cd, Cu, Cr, Hg, Pb, Se) likely leaked from the nearby industrial area over the past decades, and released into the lagoon from the canal bed by the action of depression waves generated by ships. Moreover, the model outcomes help to understand the effect of the hydrogeological layering on the propagation of the tidal fluctuation and salt concentration into the shallow brackish aquifers underlying the lagoon bottom.Facultad de Ciencias Naturales y MuseoCentro de Investigaciones Geológica

Microplastics, Additives, and Plasticizers in Freshwater Bivalves: Preliminary Research of Biomonitoring

Microplastics are widespread in freshwater environments and could impact these ecosystems. Bivalves are freshwater organisms that are particularly exposed to microplastic contamination. Therefore, in this preliminary study, the accumulation of microplastics, plasticizers, and additives in the freshwater bivalves Anodonta cygnea was investigated through active biomonitoring. Specimens bought commercially were exposed in three rivers in Central Italy for different exposure times: short (1 month) and long (3 months). The gills and the gastrointestinal tract (GIT) were analyzed separately to evaluate the possible uptake and ingestion of particles via Micro-FTIR. For the first time, small microplastics (SMPs, 5–100 µm), plasticizers, additives, and other micro-litter components, e.g., natural and non-plastic synthetic fibers (APFs), were identified in the bivalve A. cygnea. The most abundant polymer in the gills (94.4%) and in the GITs (66.1%) was polyamide, which had the highest concentration in each river. A decrease in SMPs’ abundance was observed over time in the gills in each river, while the abundance in the GIT increased. Compared to polymers, a greater variety of APFs was observed in rivers. The APFs changed during the time of exposure and between different rivers more evidently than polymers, allowing for a clearer identification of the possible sources. These results highlighted the plastic pollution caused by SMPs using freshwater bivalves as sentinel organisms and the need to further investigate the additives that can be proxies of the presence of microplastics in the environment and biot

Additives, plasticizers and small microplastics (<100 μm) in wet and dry depositions from an urban area of Venice, Italy

The atmosphere is considered one of the most important pathways for the transport of microplastics (MPs) from urban areas to far and remote places (Evangeliou et al., 2020; Zhang et al., 2019). Atmospheric depositions consist of dry and wet depositions, and it may be a positive driver in atmospheric pathways of MPs, especially for the smallest particles (SMPs &lt; 100 µm), since they are considering the current scavenging mechanisms for aerosol particles. However, there is a lack of knowledge on the amount and relative pathways of these emerging pollutants in atmospheric depositions, including sampling, pretreatments, and analytical techniques for their quantification and chemical identification. Further, additives and plasticizers can be leached from MPs and SMPs in depositions and they can be transported through different environmental compartments contributing to potential toxic effects on different organisms (Beiras et al., 2021). In this study, SMPs, additives, plasticizers, natural and non-plastic synthetic fibers (APFs), and of other components of micro-litter were investigated in wet and dry depositions from an urban area of Mestre (Venice-Italy). A wet and dry deposimeter was used for the sampling procedure with glass decontaminated buckets. A pretreatment method was developed for the quantification and chemical identification of both SMPs and APFs using a MicroFTIR to avoid further degradation/denaturation of these compounds. From the results, the removal efficiency of wet deposition in terms of the total SMPs and APs from the atmosphere is higher than in dry periods due to the scavenging effect. The consequence of this atmospheric removal by precipitation is the main sink for SMPs and APs on the ground with consequences in aquatic and terrestrial compartments. Different sources from the urban area could affect the abundance and distribution of SMPs and APs. Different APs investigated could be a good proxy of SMPs presence in the environment, for instance, road dust resuspension

Tyre Wear Particles and Small Microplastics (SMPs <100 Μm) From Highway Stormwater Runoff: Sampling, Pre-Treatment Procedures and First Results

Highway stormwater runoff is a direct pathway for conveying microplastics (MPs) and other environmental pollutants from land-based sources to the aquatic and terrestrial environment. However, the concerns on stormwater for microplastic pollution and the other components of microlitter (additives and plasticizers) have grown exponentially and the knowledge on their pathways and impacts are now very limited. Important sources of microplastic in stormwater runoff are related to traffic vehicles, polymer-modified bitumen, road paint, atmospheric deposition and the wear of tyres. Hence, due to their small size, smaller MPs (SMPs, &lt; 100 μm), additives and tyre wear particles (TWPs) can pose a risk for the environments as they can be ingested by different kinds of biota and can cause potential health problems for human beings. Only very limited studies have been paid attention to microplastics, especially SMPs, and TWPs from highway stormwater runoff with a consequent lack of knowledge regarding the amounts, size, and composition of these pollutants emitted in the different environmental pathways. There are currently no standardized methods and harmonized techniques for the collection, pretreatments, contamination procedures, and analysis of SMPs and TWPs from stormwater runoff, making significant differences in the data of these pollutants studies difficult to compare. In this study, stormwater runoff samples were collected during different rainfall events from a trafficked highway near Venice, Italy. A pre-treatment procedure (e.g., oleo-extraction, purification, and filtration) was developed and optimized in a Clean Room (ISO 7) at Ca’ Foscari University of Venice to prevent any possible plastic contamination. Quantification and simultaneous chemical identification were performed via MicroFTIR for SMPs, TWPs, additives, and plasticizers in stormwater runoff samples. Further, pyrolysis gas chromatography-mass spectrometry (Pyr-GC/MS) was developed to confirm the presence of specific SMPs and TWPs in the same samples analyzed. The cross-validation among MicroFTIR and Pyr-GC/MS techniques allows the standardization of pretreatment and analytical methods. Regarding TWPs, different tests were carried out and the first results of quantification and chemical identification of specific markers were obtained