Multiresidue determination and predicted risk assessment of emerging contaminants in sediments from Kongsfjorden, Svalbard

The present work provides the first data on the occurrence of different classes of pharmaceuticals and personal care products (PPCPs) in surface marine sediments from an Arctic fjord (Kongsfjorden, Svalbard Islands, Norway). The target compounds included: ciprofloxacin; enrofloxacin; amoxicillin; erythromycin; sulfamethoxazole; carbamazepine; diclofenac; ibuprofen; acetylsalicylic acid; paracetamol; caffeine; triclosan; N,N-diethyl-meta-toluamide; 17β-estradiol; 17α-ethinyl estradiol and estrone. Sampling was performed in the late summer, when high sedimentation rates occur, and over 5 years (2018-2022). Based on the environmental concentrations (MECs) found of emerging contaminants and the relative predicted no-effect concentrations (PNECs), an environmental risk assessment (ERA) for sediments was performed, including the estimation of the Risk Quotients (RQs) of selection and propagation of antimicrobial resistance (AMR) in this Arctic marine ecosystem. Sediments were extracted by Pressurized Liquid Extraction (PLE) and the extracts were purified by Solid Phase Extraction (SPE). Analytical determination was conducted with liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS). PPCPs were detected in the sediments along the fjord in all the years investigated, with overall concentrations similar in most cases to those reported in urbanized areas of the planet and ranging from a minimum of 6.85 ng/g for triclosan to a maximum of 684.5 ng/g for ciprofloxacin. This latter was the only antibiotic detected but was the most abundant compound (32 %) followed by antipyretics (16 %), hormones (14 %), anti-inflammatories (13 %), insect repellents (11 %), stimulants (9 %), and disinfectants (5 %). Highest concentrations of all PPCPs detected were found close to the Ny-Ålesund research village, where human activities and the lack of appropriate wastewater treatment technologies were recognized as primary causes of local contamination. Finally, due to the presence in the sediments of the PPCPs investigated, the ERA highlights a medium (0.1 < RQ < 1) to high risk (RQ > 1) for organisms living in this Arctic marine ecosystem, including high risk of the spread of AMR.

Application of the Aliivibrio fischeri bacterium bioassay for assessing single and mixture effects of antibiotics and copper

The Aliivibrio fischeri bioassay was successfully applied in order to evaluate the acute effect of sulfamethoxazole (SMX), ciprofloxacin (CIP), chlortetracycline (CTC) and copper (Cu), alone or in binary, ternary, and overall mixture. The toxicity results are reported in terms of both effective concentrations, which inhibited 50% of the bacterium bioluminescence (EC50%), and in Toxic Units (TUs). The TUs were compared with predicted values obtained using the Concentration Addition model (CA). Finally, the toxicity of water extracts from a soil contaminated by the three antibiotics (7 mg Kg-1 each) in the presence/absence of copper (30 mg Kg-1) was also evaluated. Copper was the most toxic chemical (EC50: 0.78 mg L-1), followed by CTC (EC50: 3.64 mg L-1), CIP (96 mg L-1) and SMX (196 mg L-1). Comparing the TU and CA values of the mixtures, additive effects were generally found. However, a synergic action was recorded in the case of the CIP+Cu co-presence and antagonistic effects in the case of CTC+Cu and the ternary mixture (containing each antibiotic at 0.7 mg L-1), were identified. Soil water extracts did not show any toxicity, demonstrating the buffering ability of the soil to immobilize these chemicals.

Priority Organic Pollutants and Endocrine-Disrupting Compounds in Arctic Marine Sediments (Svalbard Islands, Norway)

The present study investigated the occurrence and distribution of polycyclic aromatic hydrocarbons (PAHs) and phenolic endocrine-disrupting compounds (PEDCs), including bisphenol A (BPA), 4-nonylphenol (4-NP), and its monoethoxylate (NP1EO) and diethoxylate precursors in marine sediments in an Arctic fjord (Svalbard, Norway). The contribution of different local sources of contamination was also evaluated, together with a risk assessment for the marine environment. Samples were collected during two consecutive summer seasons (2018 and 2019), and target contaminants were analyzed with gas chromatography-mass spectrometry (MS) and high-performance liquid chromatography-MS/MS. The results showed no statistical differences between total PAH concentrations measured in 2018 (mean value 53.7 ± 54.3 ng/g) and 2019 (mean value 58.1 ± 63.6 ng/g). Low-ring (three or four rings) PAHs were the most abundant congeners, and single PAH ratios indicated a predominance of petrogenic sources (i.e., coal and liquid fossil fuel combustion). Nonylphenols and BPA showed a significant decrease in 2019 compared to 2018; 4-NP and NP1EO prevailed in both years, particularly in sediments close to the Ny-Ålesund research village. Overall, the results indicate that local anthropic activities are the major source of contamination in the Kongsfjorden ecosystem, but also melting waters from glaciers in the summer season can play an important role as a secondary source of pollutants previously trapped in ice. Comparison between our data and empirical and mechanistic indices derived from sediment quality guidelines suggests that the occurrence of PAHs and PEDCs in sediments does not currently pose a risk for this Arctic ecosystem, but further investigation is needed on the spread of hazardous contaminants and their effects on these fragile environments. Environ Toxicol Chem 2023;42:953-965. SETAC.

Bioaccumulation of antibiotics and resistance genes in lettuce following cattle manure and digestate fertilization and their effects on soil and phyllosphere microbial communities

The degradation and bioaccumulation of selected antibiotics such as the sulfonamide sulfamethoxazole (SMX) and the fluoroquinolones enrofloxacin (ENR) and ciprofloxacin (CIP) were investigated in soil microcosm experiments where Lactuca sativa was grown with manure or digestate (1%) and spiked with a mixture of the three antibiotics (7.5 mg/kg each). The soil, rhizosphere and leaf phyllosphere were sampled (at 0 and 46 days) from each microcosm to analyze the antibiotic concentrations, main resistance genes (sul1, sul2, qnrS, aac-(6')-Ib-crand qepA), the intI1and tnpA mobile genetic elements and the microbial community structure.Overall results showed that SMX and CIP decreased (70-85% and 55-79%, respectively), and ENR was quite persistent during the 46-day experiment. In plant presence, CIP and ENR were partially up-taken from soil to plant. In fact the bioaccumulation factors were > 1, with higher values in manure than digestate amended soils. The most abundant gene in soil was sul2 in digestate- and aac-(6')-Ib-cr in the manure-amended microcosms. In soil, neither sulfamethoxazole-resistance (sul1 and sul2), nor fluoroquinolone-resistance (aac-(6')-Ib-cr, qepA and qnrS) gene abundances were correlated with any antibiotic concentration. On the contrary, in lettuce leaves, the aac-(6')-Ib-cr gene was the most abundant, in accordance with the fluoroquinolone bioaccumulation. Finally, digestate stimulated a higher soil microbial biodiversity, introducing and promoting more bacterial genera associated with antibiotic degradation and involved in soil fertility and decreased fluoroquinolone bioaccumulation.

Antibiotics and antibiotic resistance genes in anaerobic digesters and predicted concentrations in agroecosystems

In recent decades, the innovative practice of management and valorization of agrozootechnical waste as energy through anaerobic digestion (AD) has been rapidly growing. However, whether applying digestate to soil as biofertilizer can be a source of antibiotics (ABs) and antibiotic resistance genes (ARGs) has not been fully investigated so far. In this work the ARGs responsible for sulfamethoxazole (SMX) resistance (sul1, sul2), ciprofloxacin (CIP) resistance (qnrS, qepA, aac-(6')-Ib-cr) and the mobile genetic element intl1, together with the concentrations of the antibiotics SMX and CIP, were measured in several anaerobic digesters located in Central Italy. Based on these results, the concentrations of antibiotics and ARGs which can potentially reach soil through amendment with digestate were also estimated. The highest CIP and SMX concentrations were found during winter and spring in anaerobic digesters. The highest ARG abundances were found for the aac-(6')-Ib-cr and sul2 genes. The overall results showed that application of digestate to soil does not exclude AB contamination and spread of ARGs in agroecosystems, especially in the case of ciprofloxacin, owing to its high intrinsic persistence.

Sub-lethal effects of soil multiple contamination on the avoidance behaviour of Eisenia fetida

Natural ecosystems are frequently exposed to complex mixtures of different chemicals. However, the environmental risk assessment is mainly based on data from individual substances. In this study, the individual and combined effects on the terrestrial earthworm E. fetida exposed to the anionic surfactant sodium lauryl ether sulphate (SLES) and the pesticides chlorpyrifos (CPF) and imidacloprid (IMI) were investigated, by using the avoidance behaviour as endpoint. Earthworms were exposed to a soil artificially contaminated with five sub-lethal concentrations of each contaminant, both as single substances and in combination of binary and ternary mixtures. Overall results showed that IMI provoked the highest avoidance effect on earthworms, with a concentration value that induced an avoidance rate of 50% of treated organisms (AC50) of 1.30 mg/kg, followed by CPF (AC50 75.26 mg/kg) and SLES (AC50 139.67 mg/kg). The application of the Combination Index (CI) method, indicated that a deviation from the additive response occurred for most of the tested chemical mixtures, leading to synergistic or antagonistic avoidance responses. Synergistic effects were produced by the exposure to the two lowest concentrations of the CPF+IMI mixture, and by the highest concentrations of SLES+CPF and SLES+CPF+IMI mixtures. On the contrary, antagonistic effects were observed at the lowest concentrations of the binary mixtures containing the SLES and at almost all the tested concentrations of the SLES+CPF+IMI mixture (with the exception of the highest tested concentration). These results show that the avoidance test is suitable to assess the detrimental effects exerted on earthworms by chemical mixtures in soil ecosystems and the use of behavioural endpoints can increase the ecological significance of environmental risk assessment procedures.

Bioaugmentation With a Consortium of Bacterial Sodium Lauryl Ether Sulfate-Degraders for Remediation of Contaminated Soils

The anionic surfactant sodium lauryl ether sulfate (SLES) is the main component of most commercial foaming agents (FAs) used in the excavation of highway and railway tunnels with Earth pressure balance-tunnel boring machines (EPB-TBMs). Several hundreds of millions of tons of spoil material, consisting of soil mixed with FAs, are produced worldwide, raising the issue of their handling and safe disposal. Reducing waste production and reusing by-products are the primary objectives of the “circular economy,” and in this context, the biodegradation of SLES becomes a key question in reclaiming excavated soils, especially at construction sites where SLES degradation on the spot is not possible because of lack of space for temporary spoil material storage. The aim of the present work was to apply a bacterial consortium (BC) of SLES degraders to spoil material excavated with an EPB-TBM and coming from a real construction site. For this purpose, the BC capability to accelerate SLES degradation was tested. Preliminary BC growth, degradation tests, and ecotoxicological evaluations were performed on a selected FA. Subsequently, a bioaugmentation experiment was conducted; and the microbial abundance, viability, and SLES concentrations in spoil material were evaluated over the experimental time (0.5, 3, 6, 24, 48, and 144 h). Moreover, the corresponding aqueous elutriates were extracted from all the soil samples and analyzed for SLES concentration and ecotoxicological evaluations with the bacterium Aliivibrio fischeri. The preliminary experiments showed the BC capability to grow under 14 different concentrations of the FA. The maximum BC growth rates and degradation efficiency (100%) were achieved with initial SLES concentrations of 125, 250, and 500 mg/L. The subsequent bioaugmentation of the spoil material with BC significantly (sixfold) improved the degradation time of SLES (DT₅₀ 1 day) compared with natural attenuation (DT₅₀ 6 days). In line with this result, neither SLES residues nor toxicity was recorded in the soil extracts showing the spoil material as a by-product promptly usable. The bioaugmentation with BC can be a very useful for cleaning spoil material produced in underground construction where its temporary storage (for SLES natural biodegradation) is not possible.

Multiple exposure of the Boreogadus saida from bessel fjord (NE Greenland) to legacy and emerging pollutants

This work investigates the occurrence of OCPs, such as hexachlorocyclohexane (α-, β-, γ- and δ-HCH) isomers, dichlorodiphenyltrichloroethane (p,p'-DDT) and its metabolite dichlorodiphenyldichloroethylene (p,p'-DDE), endosulfan (α- and β-EDS) isomers, chlorpyrifos (CPF), dacthal (DAC) and phenolic compounds, such as 4-nonylphenol (4-NP) and its precursors nonylphenol polyethoxylates (NP1EO and NP2EO) and bisphenol A (BPA), in polar cod sampled in and outside Bessel Fjord (NE Greenland). Linear regressions between target contaminants and morphological parameters (age, length, weight, gonad- and hepato-somatic indices and Fulton K) have been also evaluated. Polar cod collected at shelf had higher average concentrations of BPA, NP1EO, NP2EO and 4-NP (muscle: 6.2, 13.2, 8.9 and 1.9 ng/g w.w., respectively; liver: 5.8, 7.5, 5.2 and 0.9 ng/g w.w. respectively), than fjord's specimens (muscle: 3.5, 9.1, 3.9 and 1.0 ng/g w.w., respectively; liver: 2.4, 5.3, 2.9 and 1.1 ng/g w.w. respectively). ΣHCHs, ΣEDSs, ΣDDTs, CPF and DAC, were more accumulated in the polar cod from the fjord (average amount in muscle: 9.1, 4.8, 7.9, 3.8 and 2.8 ng/g w.w., respectively; average amount in the liver: 11.2, 9.0, 3.8, 5.9 and 4.9 ng/g w.w., respectively) than shelf's ones (average amount in muscle 3.9, 4.5, 4.2, 0.9 and 1.2 ng/g w.w., respectively; average amount in liver 7.8, 6.3, 2.1, 3.4 and 2.5 ng/g w.w., respectively). The comparison between the concentration of target contaminants and morphologic parameters suggested a different exposure of polar cod occupying the fjord and shelf habitats, due to a combination of genetic and dietary differences, climate change effects and increased human activities.

Germination, root elongation, and photosynthetic performance of plants exposed to sodium lauryl ether sulfate (SLES): an emerging contaminant

The anionic surfactant SLES (sodium lauryl ether sulfate) is an emerging contaminant, being the main component of foaming agents that are increasingly used by the tunnel construction industry. To fill the gap of knowledge about the potential SLES toxicity on plants, acute and chronic effects were assessed under controlled conditions. The acute ecotoxicological test was performed on Lepidum sativum L. (cress) and Zea mays L. (maize). Germination of both species was not affected by SLES in soil, even at concentrations (1200 mg kg-1) more than twice higher than the maximum realistic values found in contaminated debris, thus confirming the low acute SLES toxicity on terrestrial plants. The root elongation of the more sensitive species (cress) was instead reduced at the highest SLES concentration. In the chronic phytotoxicity experiment, photosynthesis of maize was downregulated, and the photosynthetic performance (PITOT) significantly reduced already under realistic exposures (360 mg kg-1), owing to the SLES ability to interfere with water and/or nutrients uptake by roots. However, such reduction was transient, likely due to the rapid biodegradation of the surfactant by the soil microbial community. Indeed, SLES amount decreased in soil more than 90% of the initial concentration in only 11 days. A significant reduction of the maximum photosynthetic capacity (Pnmax) was still evident at the end of the experiment, suggesting the persistence of negative SLES effects on plant growth and productivity. Overall results, although confirming the low phytotoxicity and high biodegradability of SLES in natural soils, highlight the importance of considering both acute and nonlethal stress effects to evaluate the environmental compatibility of soil containing SLES residues.

Occurrence, distribution and pollution pattern of legacy and emerging organic pollutants in surface water of the Kongsfjorden (Svalbard, Norway): Environmental contamination, seasonal trend and climate change

This work aimed to investigate the contamination pattern in Kongsfjorden marine environment (Svalbard, 79°N 12°E) and to disentangle primary and secondary emissions. Surface seawater, sampled in two seasons, was analysed by GC-MS and LC-MS/MS to detect polychlorobiphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), nonylphenols (NPs), bisphenol A (BPA) and perfluoroalkyl and polyfluoroalkyl substances (PFASs). In summer, average ΣPAHs, BPA, ΣNPs, ΣPFASs and ΣPCBs concentrations were 17.3 ± 11.1 ng/L, 0.9 ± 0.3 ng/L, 10.0 ± 6.9 ng/L, 0.4 ± 0.7 ng/L and 1.8 ± 1.3 pg/L, respectively; while in winter, they were 13.6 ± 10.1 ng/L, 0.5 ± 0.2 ng/L, 6.8 ± 3.3 ng/L, <LOD and 0.6 ± 0.4 pg/L, respectively. The application of generalized linear models (GLMs) highlighted that: PFAS pattern agrees their predominant long-range hydrospheric transport; the additive effect of the distance to glacier and harbour affected PAH, NP and BPA distributions; the additive effect of season and distance from the glacier, but not their interaction, influenced PCBs distribution, indicating melting glaciers as potential secondary POP sources.

Effects of Sulfamethoxazole on the Microbial Community Dynamics During the Anaerobic Digestion Process

Anaerobic digestion (AD) treatment of cattle manure and slurry makes it possible to produce biogas, a renewable and storable biofuel, as well as digestate, a residual organic matter that can be used to replace chemical fertilizers. On the other hand, the intense use of antibiotics (e.g., sulfamethoxazole) in animal husbandry practices is showing increasing negative impacts resulting from the release of still metabolically active molecules into agroecosystems. In the present study, cattle manure collected from an AD plant-feeding tank was used as feedstock for AD experiments in which some batches were spiked with 5 mg L^-1 of sulfamethoxazole (SMX). Adding the antibiotic affected the microbial community dynamic; in particular, the efficiency of the acidogenic and acetogenic phases of the process corresponded to higher CH₄ and H₂ production than in the control. SMX was also degraded, and at the end of the experiment (69 days), just 20% of its initial concentration was found. The relative abundance (ARG/16S) of resistance genes sul1, sul2, and the proxy intI1 initially found in the ingestate decreased during the AD in both the spiked and control batches, suggesting that this process lowers the likelihood of antibiotic resistance genes spreading.

Co-presence of the anionic surfactant sodium lauryl ether sulphate and the pesticide chlorpyrifos and effects on a natural soil microbial community

There is a growing concern about the simultaneous presence in the environment of different kinds of pollutants, because of the possible synergic or additive effects of chemical mixtures on ecosystems. Chlorpyrifos (CPF) is an organophosphate insecticide extensively used in agricultural practices. The anionic surfactant sodium lauryl ether sulphate (SLES) is the main component of several commercial products, including foaming agents used in underground mechanised excavation. Both compounds are produced and sold in high amounts worldwide and can be found in the environment as soil contaminants. The persistence of SLES and CPF in agricultural soils and their possible effects on the natural microbial community was evaluated in microcosms. The experimental set consisted of soil samples containing the autochthonous microbial community and treated with only SLES (70 mg/kg), only CPF (2 mg/kg) or with a mix of both compounds. Control microcosms (without the contaminants) were also performed. Soil samples were collected over the experimental period (0, 7, 14, 21 and 28 days) and analysed for CPF, SLES and the main metabolite of CPF (3, 5, 6-trichloropyridinol, TCP). The half-life time (DT50) of each parent compound was estimated in all experimental conditions. At the same time, the abundance, activity and structure of the microbial community were also evaluated. The results showed that the co-presence of SLES and CPF did not substantially affect their persistence in soil (DT50 of 11 and 9 days with co-presence and 13 and 10 days, respectively, when alone); however, in the presence of SLES, a higher amount of the metabolite TCP was found. Interestingly, some differences were found in the bacterial community structure, abundance and activity among the various conditions.

Toxic response of the bacterium Vibrio fischeri to sodium lauryl ether sulphate residues in excavated soils

Sodium lauryl ether sulphate (SLES) is the main chemical component in several lubricant products used for soil conditioning in the mechanized excavation industry using Earth Pressure Balance-Tunnel Boring Machines. During the tunnelling process, huge amounts of excavated soil are produced and the SLES presence can affect the subsequent re-use of this material as a by-product. Currently, there is still no regulatory indication of reliable and sensitive bioassays for monitoring soil quality during the excavation process. The main objective of this work was to verify if the Vibrio fischeri screening test was suitable as a consistent and precautionary tool for this specific purpose. Firstly, the ecotoxicity (EC₂₀ and EC₅₀) of the SLES standard solution and three commercial products (SLES content from 10 to 50%) were evaluated to select the most environmental friendly product. Subsequently, soil samples from about 2 years of tunnelling in a real construction site, conditioned with the selected product, were evaluated for their environmental compatibility with the prescriptions of an Italian site-specific protocol. The latter established 2 mg/L as a threshold value for SLES concentration in soil water extracts and a no toxic response (≤20%) for the Vibrio fischeri test. The comparison of the bacterium bioluminescence inhibition values (%) with analytical determinations showed an ecotoxicity when SLES was >2 mg/L. The toxicity was directly related to SLES concentration, indicating that the V. fischeri test and the SLES analyses are suitable tools for assessing excavated soil as a by-product, ensuring its safe reuse in accordance with a green production process (circular economy).

Isolation and Characterization in a Soil Conditioned With Foaming Agents of a Bacterial Consortium Able to Degrade Sodium Lauryl Ether Sulfate

The anionic surfactant Sodium Lauryl Ether Sulfate (SLES) is the principal component of several commercial foaming products for soil conditioning in the tunneling industry. Huge amounts of spoil material are produced during the excavation process and the presence of SLES can affect its re-use as a by-product. Anionic surfactants can be a risk for ecosystems if occurring in the environment at toxic concentrations. SLES biodegradability is a key issue if the excavated soil is to be reused. The aim of this study was to identify bacteria able to degrade SLES, so that it could potentially be used in bioaugmentation techniques. Enrichment cultures were performed using bacterial populations from spoil material collected in a tunnel construction site as the inoculum. A bacterial consortium able to grow in a few hours with SLES concentrations from 125 mg/L to 2 g/L was selected and then identified by Next Generation Sequencing analysis. Most of bacteria identified belonged to Gamma-Proteobacteria (99%) and Pseudomonas (ca 90%) was the predominant genus. The bacterial consortium was able to degrade 94% of an initial SLES concentration of 250 mg/L in 9 h. A predictive functional analysis using the PICRUSt2 software showed the presence of esterase enzymes, responsible for SLES degradation. The bacterial consortium selected could be useful for its possible seeding (bioaugmentation) on spoil material from tunneling excavation.

Environmental risk assessment of the anionic surfactant sodium lauryl ether sulphate in site-specific conditions arising from mechanized tunnelling

Sodium lauryl ether sulphate (SLES) is the anionic surfactant commonly utilized as the main synthetic chemical component in most foaming agents used in mechanized tunnelling. This produces huge amounts of soil debris which can contain residual concentrations of SLES. The absence of environmental quality standards for soil and water and the limited information about SLES persistence in real excavated soils do not facilitate any re-use of soil debris as by-products. The environmental risk assessment (ERA) of foaming agents containing SLES can be a valid tool for this purpose. In this study, an ERA analysis of SLES in 12 commercial formulations (cf) used for tunnelling excavation was performed. Various soils from different tunnel excavation sites were conditioned with the selected foaming agents containing SLES. Predicted or measured environmental concentrations (PECs, MECs) were determined and then compared with the Predicted No Effect Concentrations (PNECs) for both the terrestrial and aquatic compartments. The results indicate a reduction of the potential risk over time for these ecosystems, with differences depending on both the commercial foaming formulation and the spoil material characteristics. However, because potential threats to the natural environment cannot be excluded, some risk management and mitigation actions are discussed.

Dissipation of the antibiotic sulfamethoxazole in a soil amended with anaerobically digested cattle manure

The application of anaerobically digested cattle manure on agricultural land for both improving its quality and recycling a farm waste is an increasingly frequent practice in line with the circular economy. However, knowledge on the potential risk of spreading antibiotic resistance through this specific practice is quite scarce. The antibiotic sulfamethoxazole (SMX) is one of the most heavily prescribed in veterinary medicine. In this study, SMX dissipation and the possible effects on natural microorganisms were investigated in a soil amended with an anaerobically digested cattle manure produced from a biogas plant inside a livestock farm. Microcosm experiments were performed using amended soil treated with SMX (20 mg/kg soil). During the experimental time (61 days), soil samples were analysed for SMX and N4-acetylsulfamethoxazole, microbial abundance, activity and structure. Furthermore, the prevalence of the intI1 gene was also determined. The overall results showed that, although there was an initial negative effect on microbial abundance, SMX halved in about 7 days in the digestate-amended soil. The intI1 gene found in both the digestate and amended soil suggested that the use of anaerobically digested cattle manure as fertilizer can be a source of antibiotic resistant bacteria (ARBs) and genes (ARGs) in agroecosystems.

Chemical mixtures and fluorescence in situ hybridization analysis of natural microbial community in the Tiber river

The Water Framework Directive (WFD) regulates freshwater and coastal water quality assessment in Europe. Chemical and ecological water quality status is based on measurements of chemical pollutants in water and biota together with other indicators such as temperature, nutrients, species compositions (phytoplankton, microalgae, benthos and fish) and hydromorphological conditions. However, in the current strategy a link between the chemical and the ecological status is missing. In the present WFD, no microbiological indicators are foreseen for integrating the different anthropogenic pressures, including mixtures of chemicals, nutrients and temperature changes, to provide a holistic view of the freshwater ecosystem water quality. The main aim of this work was to evaluate if natural microbial populations can be valuable indicators of multiple stressors (e.g. chemical pollutants, temperature, nutrients etc.) to guide preventive and remediation actions by water authorities. A preliminary survey was conducted to identify four sites reflecting a contamination gradient from the source to the mouth of a river suitable to the objectives of the European Marie Curie project, MicroCoKit. The River Tiber (Italy) was selected as a pilot case study to investigate the correlation between bacteria taxa and the chemical status of the river. The main physicochemical parameters, inorganic elements, organic pollutants and natural microbial community composition were assessed at four selected sites corresponding to pristine, agricultural, industrial and urban areas for three consecutive years. The overall chemical results indicated a correspondence between different groups of contaminants and the main contamination sources at the selected sampling points. Phylogenetic analysis of the microbial community analyzed by Fluorescence In Situ Hybridization method (FISH) revealed differences among the four sampling sites which could reflect an adaptive bacterial response to the different anthropogenic pressures.

Assessment of biodegradation of the anionic surfactant sodium lauryl ether sulphate used in two foaming agents for mechanized tunnelling excavation

The anionic surfactant sodium lauryl ether sulphate (SLES) is the main component in most foaming agents used for mechanized tunneling excavation. The process produces huge amounts of soil debris that can have a potential impact on ecosystems. The lack of accurate information about SLES persistence in excavated soil has aroused increasing concern about how it is recycled. The objective of this study was to assess SLES biodegradability in two commercial foaming agents (P1 and P2). Microcosm experiments were performed with two different soils collected from a tunnel construction site and conditioned with P1 or P2 (85.0 or 83.0 mg kg ^-1 of SLES, respectively). At selected times soil samples were collected for assessing the SLES residual concentration using Pressured Liquid Extraction followed by methylene blue active substance analysis (MBAS). Simultaneously, soil microbial abundance (DAPI counts), viability (Live/Dead method), activity (dehydrogenase analysis) and phylogenetic structure (Fluorescent In Situ Hybridization) were evaluated. SLES halved faster in the silty-clay soil (6 d) than in the gravel in a clay-silty-sand matrix (8-9 days). At day 28 it was degraded in both soils. Its biodegradation was ascribed to the significant increase in Gamma-Proteobacteria. At this time, the spoil material can be considered as a by-product.

Distribution patterns of organic pollutants and microbial processes in marine sediments across a gradient of anthropogenic impact

Marine sediments are part of the hydrological cycle and the ultimate storage compartment of land-derived organic matter, including pollutants. Since relevant microbially-driven processes occurring at benthic level may affect the quality of the overall aquatic system, the necessity for incorporating information about microbial communities functioning for ecosystem modelling is arising. The aim of this field study was to explore the links occurring between sediment contamination patterns by three selected class of organic pollutants (Polycyclic Aromatic Hydrocarbons, PAHs, Nonylphenols, NPs, Bisphenol A, BPA) and major microbial properties (Prokaryotic Biomass, PB; total living biomass, C-ATP; Prokaryotic C Production rate, PCP; Community Respiration rate, CR) across a gradient of anthropogenic pollution. Sediments were sampled from 34 sites selected along 700 km of the western coastline of the Adriatic Sea. Organic contamination was moderate (PAHs <830 ng g^-1; NPs <350  ng g^-1; BPA <38  ng g^-1) and decreased southward. The amount of PAHs-associated carbon (C-PAHs) increased significantly with sediment organic carbon (OC), along with microbial functional rates. The negative relation between PCP/CR ratio and OC indicated the shift toward oxidative processes in response to organic pollution and potential toxicity, estimated as Toxic Equivalents (TEQs). Our outcomes showed that sediment organic contamination and benthic microbial processes can be intimately linked, with potential repercussions on CO₂ emission rates and C-cycling within the detritus-based trophic web.

Persistence of the antibiotic sulfamethoxazole in river water alone or in the co-presence of ciprofloxacin

Sulfamethoxazole and ciprofloxacin are among the most prescribed antibiotics and are frequently detected in surface water ecosystems. The aim of this study was to assess the role of a riverine natural microbial community in sulfamethoxazole (SMX) degradation in presence and absence of ciprofloxacin (CIP). River samples were collected from a stretch of the Tiber River highly impacted by human pressure. An experimental set up was performed varying some abiotic (dark/UV-light) and biotic (presence/absence of microorganisms) conditions that can affect antibiotic degradation. The residual concentrations of SMX and CIP were measured (HPLC-MS or HPLC-UV/FLD) and the effects on the natural microbial community were assessed in terms of microbial number (N. live cells/mL) and structure (Fluorescence In Situ Hybridization - FISH). Finally, the occurrence of the antibiotic resistance sul1 gene was also verified using quantitative PCR (qPCR). In 28 days, in the presence of both UV-light and microorganisms SMX disappeared (<LOD). SMX decreased partially in the dark (24%) and a slightly higher depletion was found in sterile river water and UV-light (30%). However, only in the presence of the microbial populations and in dark conditions, SMX disappeared subsequently at days 60. In the co-presence of CIP and light, SMX was more persistent (50%) than when alone. The depletion of CIP was not negatively influenced by SMX occurrence. The antibiotics did not negatively affect the microbial numbers. The FISH analysis showed that some bacterial populations were initially inhibited by the presence of the antibiotics, but at the end of the experiment, a general increase in most groups was observed together with an increase in the copy numbers of the sul1 gene. Therefore, the antibiotics at the dose of 500 μg/L did not have biocide effects on the natural microbial community and, instead, promoted some resistant natural bacterial populations able to degrade them.

Clam bioaccumulation of Alkylphenols and Polyciclic aromatic hydrocarbons in the Venice lagoon under different pressures

Biota-Sediment Accumulation Factors (BSAFs) of nonylphenols (NPs) and polycyclic aromatic hydrocarbons (PAHs) in Ruditapes philippinarum from the Venice Lagoon (Italy) were determined with the aim to verify whether the routine biomonitoring studies are reliable in contaminated sites. Clams and sediments were collected in field campaigns (October 2003 to June 2004) in three sites of the Venice Lagoon. Results showed that Marghera and Campalto sediments were more contaminated by NPs and PAHs than Poveglia. Different trends were observed in the contamination of clams with the highest BSAFs found at Poveglia. BSAF trend appeared to be inversely related to the contaminant pressure on the sites. These results suggest that clam bioaccumulation is not always representative of the chemical pressure on aquatic biota. The direct correlation between sediment and biota concentrations in contaminated sites can be lost as a function of the site-specific conditions such as sediment toxicity and food availability.

Characteristics and environmental fate of the anionic surfactant sodium lauryl ether sulphate (SLES) used as the main component in foaming agents for mechanized tunnelling

The anionic surfactant sodium lauryl ether sulphate (SLES) is the main component of most commercial products used for soil conditioning in the excavation industry, in particular as lubricants for mechanized tunnelling. Its use during the excavation processes can result in either the subsequent possible re-use of the huge amount of soil debris as by-products (e.g. land covering) or its discharge as waste. Currently, there are neither SLES soil threshold limits in European legislation, nor comprehensive studies on the environmental risk for soil ecosystems in these exposure scenarios. In this context, the present paper reviews the available data on the intrinsic characteristics of persistence and the ecotoxicological effects of the anionic surfactant SLES. Although SLES is generally reported to be biodegradable in standard tests, with degradation rates between 7 h and 30 days, depending on the initial conditions, data on its biodegradation in environmental studies are quite scarce. Consequently, assessing SLES biodegradation rates in field conditions is crucial for evaluating if in residual concentrations (typically in the range 40-500 mg/kg in excavated soils) it can or not be a potential hazard for terrestrial and water organisms. Laboratory ecotoxicological tests pointed out detrimental effects of SLES for aquatic organisms, while data on the terrestrial species are rather poor so far and further studies at the expected environmental concentrations are necessary. Finally, the review reports the main analytical methods available for detecting anionic surfactants in solid matrices and the future research needed to improve knowledge on the possible environmental risks posed by the use of SLES in foaming agents for mechanized tunnelling.

Microbial responses to polycyclic aromatic hydrocarbon contamination in temporary river sediments: Experimental insights

Temporary rivers are characterized by dry-wet phases and represent an important water resource in semi-arid regions worldwide. The fate and effect of contaminants have not been firmly established in temporary rivers such as in other aquatic environments. In this study, we assessed the effects of sediment amendment with Polycyclic Aromatic Hydrocarbons (PAHs) on benthic microbial communities. Experimental microcosms containing natural (Control) and amended sediments (2 and 20 mg PAHs kg(-1) were incubated for 28 days. The PAH concentrations in sediments were monitored weekly together with microbial community structural (biomass and phylogenetic composition by TGGE and CARD-FISH) and functional parameters (ATP concentration, community respiration rate, bacterial carbon production rate, extracellular enzyme activities). The concentration of the PAH isomers did not change significantly with the exception of phenanthrene. No changes were observed in the TGGE profiles, whereas the occurrence of Alpha- and Beta-Proteobacteria was significantly affected by the treatments. In the amended sediments, the rates of carbon production were stimulated together with aminopeptidase enzyme activity. The community respiration rates showed values significantly lower than the Control after 1 day from the amendment then recovering the Control values during the incubation. A negative trend between the respiration rates and ATP concentration was observed only in the amended sediments. This result indicates a potential toxic effect on the oxidative phosphorylation processes. The impoverishment of the energetic resources that follows the PAH impact may act as a domino on the flux of energy from prokaryotes to the upper level of the trophic chain, with the potential to alter the temporary river functioning.

Occurrence of selected pharmaceuticals in the principal sewage treatment plants in Rome (Italy) and in the receiving surface waters

This paper provides data on the occurrence of selected human pharmaceuticals (carbamazepine, clofibric acid, diclofenac, fenofibrate, fenoprofen, gemfibrozil, ibuprofen, ketoprofen, and naproxen) including steroid hormones (17β-estradiol, 17α-ethinylestradiol, and estrone) in influents/effluents to/from the four principal wastewater treatment plants (WWTPs) serving the city of Rome (Italy), in two different sampling campaigns. Target compounds were also analyzed in the receiving River Tiber and River Aniene. Analytical determination was carried out by LC-MS/MS after sample cleanup and concentration by off-line solid-phase extraction (SPE). The aim of the study was to increase the information currently available on the presence and persistence of pharmaceuticals in Italian urban wastewaters and to evaluate the environmental impact of the pharmaceutical residues discharged through effluents into the receiving rivers. Results indicated that after the treatment processes, most of pharmaceuticals were not completely eliminated, as average removal efficiencies were in the 14-100% wide range during both sampling periods, with higher yields in spring than in winter. Levels detected in overall samples ranged from 5 to 2,230 ng/L in influents and from 5 to 1,424 ng/L in effluents. Carbamazepine, diclofenac, ibuprofen, and gemfibrozil showed the highest persistence to removal. Concentrations in the receiving waters were about one order of magnitude lower than in effluents, with a tendency to increase progressively through the urban tract of the river. Finally, an environmental risk analysis showed that carbamazepine, gemfibrozil, and estrone can pose a high risk at the concentrations detected in effluents and a medium risk in rivers, highlighting their potential hazard for the health of the aquatic ecosystem.

Capability of the natural microbial community in a river water ecosystem to degrade the drug naproxen

The present work aims at evaluating the ability of the River Tiber natural microbial community to degrade naproxen in water samples collected downstream from a wastewater treatment plant. For this purpose, different water microcosms were set up (microbiologically active vs sterile ones) and treated with naproxen (100 μg/L) alone or in the co-presence of gemfibrozil in order to evaluate if the co-presence of the latter had an influence on naproxen degradation. The experiment was performed in the autumn and was compared with the same experimental set performed in spring of the same year to highlight if seasonal differences in the river water influenced the naproxen degradation. Pharmaceutical concentrations and microbial analysis (total cell number, viability, and microbial community composition) were performed at different times in the degradation experiments. The overall results show that the natural microbial community in the river water had a key role in the naproxen degradation. In fact, although there was a transient negative effect on the natural microbial community in all the experiments (3 h after adding the pharmaceutical), the latter was able to degrade naproxen within about 40 days. On the contrary, no decrease in the pharmaceutical concentration was observed in the sterile river water. Moreover, the co-presence of the two drugs lengthened the naproxen lag phase. As regards the natural microbial community composition detected by Fluorescence in situ Hybridization, Alpha and Gamma-Proteobacteria increased when the pharmaceutical halved, suggesting their role in the degradation. This study shows that with the concentration studied, naproxen was degraded by the natural microbial populations collected from a river chronically contaminated by this pharmaceutical.

Organic priority substances and microbial processes in river sediments subject to contrasting hydrological conditions

Flood and drought events of higher intensity and frequency are expected to increase in arid and semi-arid regions, in which temporary rivers represent both a water resource and an aquatic ecosystem to be preserved. In this study, we explored the variation of two classes of hazardous substances (Polycyclic Aromatic Hydrocarbons and Nonylphenols) and the functioning of the microbial community in river sediments subject to hydrological fluctuations (Candelaro river basin, Italy). Overall, the concentration of pollutants (∑PAHs range 8-275ngg(-1); ∑NPs range 299-4858ngg(-1)) suggests a moderate degree of contamination. The conditions in which the sediments were tested, flow (high/low) and no flow (wet/dry/arid), were associated to significant differences in the chemical and microbial properties. The total organic carbon contribution decreased together with the stream flow reduction, while the contribution of C-PAHs and C-NPs tended to increase. NPs were relatively more concentrated in sediments under high flow, while the more hydrophobic PAHs accumulated under low and no flow conditions. Passing from high to no flow conditions, a gradual reduction of microbial processes was observed, to reach the lowest specific bacterial carbon production rates (0.06fmolCh(-1)cell(-1)), extracellular enzyme activities, and the highest doubling time (40h) in arid sediments. In conclusion, different scenarios for the mobilization of pollutants and microbial processes can be identified under contrasting hydrological conditions: (i) the mobilization of pollutants under high flow and a relatively higher probability for biodegradation; (ii) the accumulation of pollutants during low flow and lower probability for biodegradation; (iii) the drastic reduction of pollutant concentrations under dry and arid conditions, probably independently from the microbial activity (abiotic processes). Our findings let us infer that a multiple approach has to be considered for an appropriate water resource exploitation and a more realistic prevision of the impact of pollutants in temporary waters.

Occurrence of priority hazardous PAHs in water, suspended particulate matter, sediment and common eels (Anguilla anguilla) in the urban stretch of the River Tiber (Italy)

This study investigated the occurrence of polycyclic aromatic hydrocarbons (PAHs) in water, suspended particulate matter (SPM), bed sediment and common eels (Anguilla anguilla) in the urban stretch of the River Tiber (Italy). The selected PAHs, fluoranthene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, benzo(g,h,i)perylene, indeno(1,2,3-cd)pyrene, belong to the EC priority list of dangerous substances. SPM was found to be the most polluted compartment, with values ranging from 1663.1 to 15472.9 ngg(-1) (Σ(6)PAHs), followed by sediment samples, from 157.8 to 271.6 ngg(-1) and by aqueous samples, from 23.9 to 72.0 ngL(-1). The distribution coefficient (K(d)) showed a good correlation with particle organic carbon (OC) content, while K(oc) values experimentally measured for sediment/SPM deviated from those predicted by K(ow), implying that for very hydrophobic compounds, K(ow) alone may not be an appropriate descriptor of all the thermodynamic forces involved in their sorption to aquatic particles. Some selected PAH ratios indicated that PAHs in the River Tiber come mainly from pyrolitic sources and vehicular traffic. Concentrations of individual PAHs in muscles of common eels varied from 0.8 to 7.0 ngg(-1) wet wt. and the calculated toxicity equivalent concentration (TEQ, 1.8 ngg(-1) wet wt.) of total PAHs fell below the recommended screening value (SV) in US EPA guidelines, suggesting no concern for human consumption.

Interactions between trophic and toxic factors in a polluted urban river

To investigate how particulate materials and the toxicity of a polluted river can affect biomass production of a particle feeding organism, monthly water samples of the River Lambro were collected upstream and downstream from major pollution sources. These samples were characterized for physical and chemical endpoints, and tested for acute and chronic toxicity (7-day) using Ceriodaphnia dubia. Comparing the effects of unfiltered and filtered water samples, we showed that: (a) despite the higher contamination of the downstream reach, unfiltered (whole) downstream samples often supported a higher biomass production of C. dubia than upstream samples; (b) filtering downstream water samples and thereby removing suspended particulate matter (SPM) controlled this compensatory effect and resulted in a clear inhibition of daphnid biomass production; (c) despite the compensatory and likely nutritional role of particulate materials, an inverse relationship was found between daphnid biomass production and the content of organic carbon of SPM, as well as between the SPM organic content and the temperature of the river. These results show that SPM of the downstream reach can simultaneously exert trophic and toxic effects, and their interaction determines the final result but under the control of major system factors such as water temperature.

Uptake and accumulation of sediment-associated 4-nonylphenol in a benthic invertebrate (Lumbriculus variegatus, freshwater oligochaete)

In the present work, the oligochaete Lumbriculus variegatus was exposed for 56 d to lake sediment spiked with 4-nonylphenol (4-NP), which is a breakdown product of alkylphenol polyethoxylates, an important class of nonionic surfactants. During the exposure period, the content of 4-NP was determined in the oligochaetes, sediment, overlying water, and pore water in order to monitor the distribution of the 4-NP in the compartments of the test system. Concentration of 4-NP in L. variegatus increased linearly over the course of the test, with an uptake rate coefficient of 1.9 x 10(-2) (+/- 0.2 x 10(-2); [g carbon/(g lipid x h)]). No steady state was reached at the end of the exposure period, suggesting that the elimination of 4-NP by the organism was negligible. Ingested sediments played an important role in the accumulation of 4-NP in L. variegatus, which may achieve very high 4-NP body concentrations. The 56-d biota sediment accumulation factor (BSAF) was 24 +/- 7 g carbon/g lipid. L. variegatus also was exposed to 4-NP-contaminated field sediment, and field oligochaetes and sediments were collected for 4-NP pollution assessment in aquatic ecosystem. The 4-NP uptake with natural sediment was in accordance with that measured with spiked sediments, suggesting that the bioavailability of sediment-associated 4-NP for L. variegatus was not affected by 4-NP sediment concentration and abiotic sediment characteristics. The BSAFs measured in field oligochaetes, ranging from 39 to 55 g carbon/g lipid, was relatively higher than the bioaccumulation factor measured in laboratory tests. The results suggest that 4-NP concentration can reach high levels in benthic oligochaetes; this can be an important way of exposure for their pelagic predators.

Determination of endocrine disrupting chemicals in environmental solid matrices by extraction with a non-ionic surfactant (Tween 80)

A readily applicable method based on extraction by aqueous non-ionic surfactant solutions (Tween 80) and RP-HPLC coupled to fluorescence detection, has been developed for the simultaneous determination of the phenolic endocrine disrupting chemicals (EDCs) nonylphenol (NP), nonylphenol monoethoxylate (NP1EO) and nonylphenol diethoxylate (NP2EO) and bisphenol A (BPA) in environmental solid matrices. Clean up of sample extracts was performed on Si-C18 solid phase extraction (SPE) cartridges. The overall Tween 80 extraction-SPE-RP-HPLC procedure was validated for accuracy and precision by analyzing sediment samples spiked with known amounts of EDCs. Recoveries for NP, NP1EO, NP2EO and BPA and limits of detection are in agreement with conventional extraction methods. The developed methodology was successfully applied to the analysis of target compounds in Italian river sediments, river suspended matter and benthonic macroinvertebrate organisms (oligochaetes Lumbriculus variegatus). Results confirmed that this relatively simple procedure performed satisfactorily in the determination of phenolic EDCs in environmental solid matrices of different complexity and that it can be a suitable alternative method to conventional systems even for routine analyses.

Quality assessment of bed sediments of the Po River (Italy)

Comprehensive and contemporary evaluations of physical, chemical and toxicological endpoints have been performed on bed sediments of the Po River, the major Italian watercourse. Two extensive sampling campaigns were conducted in summer and winter low-flow conditions. Composite sediment samples were collected from ten reaches of the main river: the first was located in the upper region (ambient control), and the others downstream of the confluences of nine principal tributaries. The two sampling programs were paralleled by contemporary investigations on the macroinvertebrate community. The particle-size composition along the Po River showed a relatively uniform distribution of fine sand, a progressive downstream decrease of coarse sands and a corresponding increase of fine materials. The levels of polychlorinated biphenyls (PCB), polycyclic aromatic hydrocarbons (PAH), extractable organo halides (EOX), Cd, Cr, Cu, Hg, Ni, Pb and Zn were determined in sediment fine particles (< 63 microm), and showed marked changes across the ten river reaches. Their longitudinal trends, as those of organic carbon and total nitrogen, were very similar and largely independent of the survey season. Sediment quality benchmarks were used to evaluate sediment chemistry, and, although the overall level of contamination was from moderate to low, the reaches located downstream of the tributaries Dora Riparia, Dora Baltea, Lambro and Oglio were considered to be at risk. Sediments were tested for toxicity on Oncorhynchus mykiss, Ceriodaphnia dubia, Raphidocelis subcapitata and Vibrio fischeri. The toxicity tests were conducted both with sediment extracts and whole samples. Sediment extracts showed toxic potentials that were consistent with the spatial distribution of contaminants. Whole-sediment toxicity showed moderate/low effects which also included false positives and negatives. Alterations of the macroinvertebrate community were found for many kilometers downstream of Dora Riparia, and with a seasonal dependence, also in other reaches of the Italian river. Principal component analysis (PCA) was used to describe the longitudinal and temporal changes of the Po River, and allowed the selection of the most useful and discriminating indicators.