A chemical remediation technique for a nearly-total removal of arsenic and mercury from contaminated marine sediments.

After decades of industrial exploitation of the coast and consequent contamination of the sites and marine sediments, it became essential to recover the marine ecosystem by remediation methods to remove toxic contaminants. In this work, a remediation method was developed to clean marine sediments contaminated by arsenic (As) and mercury (Hg). The method can be applied to mobile platforms and is based on an environmentally friendly approach designed to minimise further contamination. The method was tested on two artificially contaminated sediments and two real samples collected from two highly contaminated sites in southern Italy, Augusta Bay and Bagnoli Gulf, characterised by high Hg and As concentrations, respectively. The method consists of four steps: washing with sodium hydroxide (NaOH) to remove metals associated with humic acid; Fenton-reaction using α-CycloDextrin (aCD) to stabilise Fe(II) at natural pH and oxidise As (III) and Hg (0 or I); complexation reaction with aCD; and complexation with sodium sulfide (Na2S) to remove Hg as soluble Hg-polysulfides. Compared to other remediation experiences in literature, this technique provides the best removal efficiency for As and Hg (ranging between 26 -71 % and 57-95 %, respectively). Considering the residual concentrations of As and Hg and the contamination threshold fixed by European Regulation for re-use, the treated sediment can be used in several civil and industrial contexts. The presented method operates in line with the principles of the circular economy to preserve natural resources, prevent secondary pollution, and promote the effective re-use of clean environmental matrices (soils, sediments and aqueous solutions), thus minimising landfill waste.

Encapsulated in sediments: eDNA deciphers the ecosystem history of one of the most polluted European marine sites.

The Anthropocene is characterized by dramatic ecosystem changes driven by human activities. The impact of these activities can be assessed by different geochemical and paleontological proxies. However, each of these proxies provides only a fragmentary insight into the effects of anthropogenic impacts. It is highly challenging to reconstruct, with a holistic view, the state of the ecosystems from the preindustrial period to the present day, covering all biological components, from prokaryotes to multicellular eukaryotes. Here, we used sedimentary ancient DNA (sedaDNA) archives encompassing all trophic levels of biodiversity to reconstruct the two century-natural history in Bagnoli-Coroglio (Gulf of Pozzuoli, Tyrrhenian Sea), one of the most polluted marine-coastal sites in Europe. The site was characterized by seagrass meadows and high eukaryotic diversity until the beginning of the 20th century. Then, the ecosystem completely changed, with seagrasses and associated fauna as well as diverse groups of planktonic and benthic protists being replaced by low diversity biota dominated by dinophyceans and infaunal metazoan species. The sedaDNA analysis revealed a five-phase evolution of the area, where changes appear as the result of a multi-level cascade effect of impacts associated with industrial activities, urbanization, water circulation and land-use changes. The sedaDNA allowed to infer reference conditions that must be considered when restoration actions are to be implemented.

Heavy metal background levels and pollution temporal trend assessment within the marine sediments facing a brownfield area (Gulf of Pozzuoli, Southern Italy).

In this study, site-specific natural background levels (NBLs) were determined for 18 elements (Al, As, Be, Cd, Co, Cu, Cr, Fe, Hg, K, Mn, Mo, Ni, Pb, Tl, U, V, and Zn) in two sediment cores collected offshore the Bagnoli-Coroglio brownfield site (Gulf of Pozzuoli, southern Italy) to accurately assess the degree of contamination and the historical trends in Heavy Metals (HMs) enrichment. This objective was pursued taking in account the high temporal and spatial variability of the geochemical properties of the area due to the local geothermal activity. Moreover, the temporal variation of Polycyclic Aromatic Hydrocarbons (PAHs) was investigated.226Ra was used as an extraordinary marker to confirm 210Pb dating. It especially allowed defining the geochronological framework of the sediment core closer the brownfield up to around 1500, providing compelling support to correlate the investigated elements' occurrences with natural geogenic dynamic. Sediment samples were accurately dated and analyzed for chemical and particle size composition. The contamination factor (Cf) and the pollution load index (PLI) showed very high enrichment of Cd, Cu, Hg, Pb, and Zn. The contamination profiles of HMs and PAHs follow the same pattern in both sediment cores, increasing from deep to upper layers. The highest contamination levels for HMs and PAHs were observed between 10 and 30 cm, corresponding to the periods of most intense industrial activity. Decreasing trends of pollutants were observed in the surface layers (0-10 cm), probably affected by a natural attenuation process due to the cessation of industrial activities.

Nested interactions between chemosynthetic lucinid bivalves and seagrass promote ecosystem functioning in contaminated sediments.

In seagrass sediments, lucinid bivalves and their chemoautotrophic bacterial symbionts consume H2S, relying indirectly on the plant productivity for the presence of the reduced chemical. Additionally, the role of lucinid bivalves in N provisioning to the plant (through N2 fixation by the symbionts) was hypothesized. Thus, lucinids may contribute to sediment detoxification and plant fitness. Seagrasses are subject to ever-increasing human pressure in coastal environments. Here, disentangling nested interactions between chemosynthetic lucinid bivalves and seagrass exposed to pollution may help to understand seagrass ecosystem dynamics and to develop successful seagrass restoration programs that consider the roles of animal-microbe symbioses. We evaluated the capacity of lucinid bivalves (Loripes orbiculatus) to promote nutrient cycling and seagrass (Cymodocea nodosa) growth during a 6-week mesocosm experiment. A fully crossed design was used to test for the effect of sediment contamination (metals, nutrients, and hydrocarbons) on plant and bivalve (alone or interacting) fitness, assessed by mortality, growth, and photosynthetic efficiency, and for the effect of their nested interaction on sediment biogeochemistry. Plants performed better in the contaminated sediment, where a larger pool of dissolved nitrogen combined with the presence of other trace elements allowed for an improved photosynthetic efficiency. In fact, pore water nitrogen accumulated during the experiment in the controls, while it was consumed in the contaminated sediment. This trend was accentuated when lucinids were present. Concurrently, the interaction between clams and plants benefitted both organisms and promoted plant growth irrespective of the sediment type. In particular, the interaction with lucinid clams resulted in higher aboveground biomass of C. nodosa in terms of leaf growth, leaf surface, and leaf biomass. Our results consolidate the notion that nested interactions involving animal-microbe associations promote ecosystem functioning, and potentially help designing unconventional seagrass restoration strategies that exploit chemosynthetic symbioses.

Gathering new knowledge from existing monitoring dataset of Campania marine coastal area (Southern Italy).

In this study we propose, a multi-step strategy of selection and characterization of long-term dataset of contaminant concentrations in different environmental matrices (i.e., water and sediment). Starting from a high quality and homogeneous dataset of chemical parameters, a selection of a usable refined dataset followed by statistical characterization and hazard assessment was performed. The database of chemical contamination data from monitoring activities in the coastal marine water area of the Campania Region (Italy) produced by the Regional Agency for Environmental Protection of Campania (ARPAC) between 2013 and 2019 was utilized. Descriptive and multivariate statistics were applied to the extracted data subset to describe spatial variability and to investigate the relationships between matrices and contaminants. In addition, the impact on the sediment matrix was considered using the contamination factor (Cf), the sediment quality guidelines (SQG), and the probability of exceedance (PoE) of given thresholds for metals and organic compounds. The results highlighted the main anthropogenic pressures between the Gulf of Pozzuoli and the Gulf of Napoli, and the potential hazard posed in particular by metals (i.e., Pb, C, and Hg), TBT, and PAHs. A wide range of As concentration along the Campania coastline and Ni occurrence in the southern part of the region, mainly attributable to geogenic origin, was also evidenced. This approach allows extracting new knowledge from large dataset systematically collected by ARPAC monitoring activity, to support possible actions of contamination control and mitigation.

Polyethylene, Polystyrene, and Polypropylene leachate impact upon marine microalgae Dunaliella tertiolecta.

In the aquatic environment, plastics may release several hazardous substances of severe ecotoxicological concern not covalently bound to the polymers. The aim of this study was to examine the adverse effects of leachates of different virgin polymers, polypropylene (PP), polyethylene (PE), and polystyrene (PS) on marine microalgae Dunaliella tertiolecta. The tests carried out on D. tertiolecta included: growth inhibition, oxidative stress (DCFH-DA), and DNA damage (COMET assay). Polypropylene and PS leachates produced growth inhibition at the lowest concentration (3.1% of leachate). In contrast, a hormesis phenomenon was observed with PE leachates. An algae inhibition growth ranking (PP>PS>PE) was noted, based upon EC50 values. Reactive oxygen species (ROS) generated were increased with leachates concentrations with PS exhibiting the highest ROS levels, while a marked genotoxic effect (30%) was found only with PP. All leachates were free from detectable quantities of organic compounds (GC/MS) but showed the presence of transition, post-transition and alkaline earth metals, metalloids, and nonmetals (

Integrated characterization and risk management of marine sediments: The case study of the industrialized Bagnoli area (Naples, Italy).

The aim of the present work is to demonstrate the practical importance of a multidisciplinary approach and weighted criteria to synthesize and integrate different typologies of data (or lines of evidence, LOEs), including chemical levels in marine sediments, their bioavailability to specific indicator species, ecotoxicological effects measured through subcellular biomarkers and batteries of bioassays, and potential impacts of pollution on local benthic communities. The area of Bagnoli (Gulf of Naples, Southern Italy) was selected as a model case-study, as it is a coastal area chronically impacted by massive industrial contamination (trace metals and hydrocarbons), and dismissed decades ago without any subsequent remediation or habitat restoration. The results of each LOE were elaborated to provide specific hazard indices before their overall integration in a weight of evidence (WOE) evaluation. Levels of some trace metals and PAHs revealed a severe contamination in the entire study area. Bioavailability of hydrocarbons was evident particularly for high molecular weight PAHs, which also caused significant variations of cellular biomarkers, such as cytochrome P450 metabolization in fish, lysosomal membrane destabilization in mussels, genotoxic effects both in fish and molluscs. The results of a battery of bioassays indicated less marked responses compared to those obtained from chemical and biomarkers analyses, with acute toxicity still present in sediments close to the source of contamination. The analysis of benthic assemblages showed limited evidence of impact in the whole area, indicating a good functioning of local ecosystems at chronic contamination. Overall, the results of this study confirm the need of combining chemical and biological data, the quantitative characterization of various typologies of hazard and the importance of assessing an integrated environmental WOE risk, to orientate specific and scientifically-supported management options in industrialized areas.

Adverse effects of oxo-degradable plastic leachates in freshwater environment.

The production of biodegradable plastics is considered to be a way to reduce plastic waste issue. Among others, oxo-degradant additives enable a faster degradation of plastics in the environment. However, the introduction of these new materials could provoke the release of substances potentially toxic in the environment. This work determined and compared the toxicity of leachates from various additivated polymers (polyethylene, PE; polypropylene, PP; polystyrene, PS) upon different test organisms: plants (Sorghum saccharatum, Lepidium sativum, Sinapis alba, and Vicia faba), crustacean (Daphnia magna), and luminescent bacteria (Vibrio fischeri). Daphnia magna survival was mainly affected by PS and PP leachates (72% and 61% effect, respectively) while PS notably reduced the reproduction rate. On plants, only PP exerted a negative effect (S. saccharatum IG% 32.4), while V. fischeri always showed values around 50%. The data integration, through the Toxicity Test Battery Integrated Index (TBI) approach, allowed to rank the leachates toxicity as PE > PS > PP. This result could be mainly ascribable to the highest metals content in PE since no difference with organic compounds analysis was evidenced. In conclusion, since the polymers exerted dissimilar toxicity, the additive could not be considered the sole responsible of the measured toxicity, but its role in the enhancement of the virgin polymers leachates effects can be solidly hypothesized.

A new approach to testing potential leaching toxicity of fouling release coatings (FRCs).

Fouling release coatings (FRCs) are today the main environment-friendly alternative to traditional self-polishing coatings, that continuously release biocides and/or heavy metals into water. FRCs are available on the market as environmentally friendly AF paints and most of them do not contain bioactive agents, however no complete and reliable assessment of their environmental impact has yet been carried out. Only few literature data proving their AF efficacy combined with a demonstrated lack of toxicological effects are available. Ecotoxicological bioassays are commonly used to predict the potential environmental impact of traditional AF paints. Standardized methodologies to obtain leaching products from biocide-based paints are available, while few studies propose experimental methods to assess the potential effects of biocide-free FRCs leachates on non-target organisms. The aim of this work is to propose an experimental protocol to obtain leaching products from biocide-free FRCs in order to evaluate the potential release of substances having toxic effects, by means of an ecotoxicological bioassay. Two ecotoxicological end-points with different sensitivity levels were considered (multi-end-point approach). Five silicone-based commercial coatings were used: their leaching products were collected after different immersion times following the developed experimental method and then two ecotoxicological end-points were evaluated on II stage nauplii of the crustacean Amphibalanus amphitrite as model organism. Moreover, chemical analyses were performed on leachates collected after each immersion time, focusing on the presence of metals in leaching products. From the results obtained from the bioassay, even if not indicative of the real environmental impact of FRCs, a release of toxic substances was observed from tested coatings during early immersion stages, likely to affect the exposed model organism. The potential leaching toxicity of the five tested products was compared. No clear correspondence could be identified between the concentrations of metals detected in leachates and the obtained ecotoxicological data, thus suggesting that other active components might be released by FRCs responsible for the toxic effects pointed out on A. amphitrite larvae.

A sensitive method for the determination of Sulfonamides in seawater samples by Solid Phase Extraction and UV-Visible spectrophotometry.

The authors have developed a sensitive spectrophotometric method for determination of sulfonamide derivatives such as sulfanilamide (SAA), sulfadiazine (SDZ), sulfacetamide (SCT) sulfamethoxazole (SMX), sulfamerazine (SMR), sulfadimethoxine (SDX), sulfamethiazole (SMT) and Sulfathiazole (STZ). This method is based on the Bratton-Marshall reaction, which involves the diazotization of sulfonamides with sodium nitrite under acidic conditions, followed by coupling with N-(1-naphtyl) ethylenediamine dihydrochloride (NED) to form a pink colored compound. Therefore, the Bratton-Marshall method was modified by optimizing the reaction conditions, which allows us to determine a low concentration range of sulfonamides compared to the reported methods. The limits of detection and quantification obtained were 0.019-0.05 and 0.06-0.16µgmL-1, respectively. In comparison with other reported methods using different coupling agents, the proposed method was found to be the most simple and sensitive for sulfonamides determination. In this paper, the modified method was successfully employed for the determination of sulfonamides in drinking water, seawater and pharmaceutical and veterinary formulations. The purpose of this work is to optimize and develop a simple method for extraction and concentration of sulfonamides present as residues in seawater and their quantification with the recommended spectrophotometric method. Solid phase extraction (SPE) of sulfonamides from seawater samples was evaluated using Oasis HLB cartridges (3mL, 540mg). The recovery efficiency was investigated in the sulfonamides concentration range comprised between 0.19 and 126ngmL-1. The ease of use of this extraction method makes it very useful for routine laboratory work.

Heavy metal pollution and potential ecological risks in rivers: a case study from southern Italy.

We monitored heavy metal (As, Cd, Hg, and Pb) concentrations in surface water, sediments, and oligochaetes in four major rivers in Calabria (southern Italy) over the course of 1 year. As, Cd, and Pb showed accumulation factors of 10(3)-10(5) for water to sediment and 1-10 for sediment to oligochaetes. Hg showed a water to sediment accumulation factor of 10-100. Finally, Hg concentrations exceeded the Italian quality standard for freshwater in all of the rivers, and As concentrations in sediments exceeded the respective Canadian standard. However, the application of an ecological risk assessment method indicated low risks for all monitored rivers.

Determination of selected polychlorinated dibenzo-p-dioxins/furans in marine sediments by the application of gas-chromatography-triple quadrupole mass spectrometry.

Selected polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were detected by gas-chromatography coupled to triple quadrupole mass spectrometry (GC-QqQ-MS/MS) in marine sediments collected in central Italy. Total PCDD/Fs concentrations ranged from 11.58 to 193.29 pg/g d.w., with PCDFs as the major contributors in most cases. The congener profiles were characterized by high OCDD (70.7%-91.4%). The PCDD/Fs values are within or close to the Environmental Canada sediment reference values (0.85 pg TEQ/g d.w.). GC-QqQ-MS/MS can be a suitable alternative to standard methods for PCDD/Fs determination in environmental samples. The measured PCDD/Fs amounts could be considered as a basis for future monitoring programs.

Towards a label-free optical porous silicon DNA sensor.

We report on the fabrication of an optical silicon-based label-free DNA sensor. n-Type crystalline silicon wafers have been electrochemically etched to form porous silicon layers and characterized in terms of porosity, pore distribution, surface composition and photoluminescence. Samples (0.25 cm(2)) have been cut and properly derivatized using trimethoxy-3-bromoacetamidopropylsilane in order to link single strand DNA (ss-DNA). Such a molecule is not commercially available and has been ad-hoc prepared by reacting hydrobromic acid and 3-aminopropyltrimethoxysilane in presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide as coupling agent. Trimethoxy-3-bromoacetamidopropylsilane acts as a bridge anchored to the porous silicon surface through the silane group while immobilizing ss-DNA by means of the bromoacetamido moiety. We have found that derivatized samples exhibit a photoluminescence that is stable in time and is not modified after exposure to non-complementary DNA strand. On the other hand, a sensible enhancement of the light emission has been observed when the derivatized samples react with the complementary strand, showing that the specific ss-DNA/complementary DNA (c-DNA) interaction can be optically sensed without using further labeling steps. This strongly strengthens the possible role of silicon as a material for biosensors.