Trophic Transfer of Micropollutants and Their Metabolites in an Urban Riverine Food Web.

Trophic magnification factors (TMFs, i.e., the average change in the log-concentration of a pollutant per trophic level) have been extensively assessed for the so-called persistent organic pollutants, especially organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), which are biomagnified along the food web. In contrast, trophic dilution was documented for pollutants with a high metabolic conversion rate, such as phthalate plasticizers and polycyclic aromatic hydrocarbons (PAHs). However, the fate of their metabolites across the food web has been rarely investigated. In this comparative study, the trophodynamics of 104 micropollutants and 25 of their metabolites were investigated in a freshwater food web from the urban Orge River, France. Trophic levels were determined using stable isotopes. Pyrethroid pesticides and their metabolites were not detected. As predicted, PCBs and OCPs biomagnified (TMF >1), while all chlorinated paraffins (CPs), PAHs, and phthalates underwent a trophic dilution (TMF <1). TMFs significantly decreased with a metabolic transformation rate and increased with hydrophobicity. The levels of PAH or phthalate metabolites were not significantly correlated with trophic levels or underwent a trophic dilution. This study highlighted that the relative contribution of metabolite levels in TMF values calculated for both parent compound and its metabolite(s) is weak compared to TMF values of the parent compound only in a riverine food web.

Evidence for the Trophic Transfer of Perfluoroalkylated Substances in a Temperate Macrotidal Estuary.

The present survey examines the trophodynamics of a suite of 19 perfluoroalkyl substances (PFASs) in a temperate macrotidal estuary (Gironde, SW France). Across the 147 biota samples (18 taxa) collected, perfluorooctane sulfonate (PFOS), perfluorooctane sulfonamide (FOSA), and C8-C14 perfluoroalkyl carboxylates (PFCAs) were the most-recurrent analytes. ΣPFASs ranged between 0.66-45 ng per g of wet weight of the whole body. Benthic organisms had relatively high ΣPFASs compared to demersal organisms and displayed specific composition profiles with higher relative abundances of C8 and C9 PFCAs. Trophic magnification factors (TMFs) were determined through the use of linear mixed effect models including censored data, thereby considering data below detection limits as well as the interspecific variability of δ15N and PFAS levels (random effects). TMFs were almost consistently >1 in the benthic food web as well as when considering all data pooled together, providing evidence for the biomagnification of several PFASs in estuarine environments. In addition, in contrast with previous observations, TMFs determined in the estuarine benthic web were found to significantly decrease with increasing chain length for C8-C14 PFCAs and C6-C8 perfluoroalkyl sulfonates. This suggests that PFAS chemical structure might not be necessarily predictive of TMFs, which are also influenced by the trophic web characteristics.

Data analysis strategies for the characterization of chemical contaminant mixtures. Fish as a case study.

Thousands of chemicals are potentially contaminating the environment and food resources, covering a wide spectrum of molecular structures, physico-chemical properties, sources, environmental behavior and toxic profiles. Beyond the description of the individual chemicals, characterizing contaminant mixtures in related matrices has become a major challenge in ecological and human health risk assessments. Continuous analytical developments, in the fields of targeted (TA) and non-targeted analysis (NTA), have resulted in ever larger sets of data on associated chemical profiles. More than ever, the implementation of advanced data analysis strategies is essential to elucidate profiles and extract new knowledge from these large data sets. Specifically focusing on the data analysis step, this review summarizes the recent progress in integrating data analysis tools into TA and NTA workflows to address the challenging characterization of chemical mixtures in environmental and food matrices. As fish matrices are relevant in both aquatic pollution and consumer exposure perspectives, fish was chosen as the main theme to illustrate this review, although the present document is equally relevant to other food and environmental matrices. The key features of TA and NTA data sets were reviewed to illustrate the challenges associated with their analysis. Advanced filtering strategies to mine NTA data sets are presented, with a particular focus on chemical filters and discriminant analysis. Further, the applications of supervised and unsupervised multivariate analysis methods to characterize exposure to chemical mixtures, and their associated challenges, is discussed.

Biomagnification of perfluoroalkyl acids (PFAAs) in the food web of an urban river: assessment of the trophic transfer of targeted and unknown precursors and implications.

The present work examined the trophic transfer of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in a typical urban river (Orge River, near Paris, France), and aimed to investigate the potential contribution of precursors to the biomagnification of perfluoroalkyl acids (PFAAs). Sixteen PFAAs, twelve of their precursors (pre-PFAAstargeted) and two fluorinated alternatives to long-chain PFASs were analyzed in water, sediments and biota (including biofilm, invertebrates and fish). Twenty two compounds were detected in biological samples (2.0-147 ng g-1 wet weight), perfluorooctane sulfonate (PFOS) and C12-C14 perfluoroalkyl carboxylates (PFCAs) being predominant while ∑pre-PFAAstargeted contributed to 1-18% of ∑PFASs. Trophic magnification factors (TMFs) were >1 (i.e. denoting biomagnification) for C9-C14 PFCAs, C7-C10 perfluoroalkyl sulfonates (PFSAs) and several pre-PFAAs (e.g. 8 : 2 and 10 : 2 fluorotelomer sulfonates). The significant decrease in ∑pre-PFCAs/∑PFCAs concentration ratio with trophic level suggested a likely contribution of selected precursors to the biomagnification of PFCAs through biotransformation, while this was less obvious for PFOS. The total oxidizable precursor assay, applied for the first time to sediment and biota, revealed the presence of substantial proportions of extractable unknown pre-PFAAs in all samples (i.e. 15-80% of ∑PFASs upon oxidation). This proportion significantly decreased from sediments to invertebrates and fish, thereby pointing to the biotransformation of unattributed pre-PFAAs in the trophic web, which likely contributes to the biomagnification of some PFAAs (i.e. C9-C12 PFCAs and C7-C10 PFSAs).

Where has the pollution gone? A survey of organic contaminants in Ho Chi Minh city / Saigon River (Vietnam) bed sediments.

A wide range of persistent organic chemicals, including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), some insecticides, as well as polybrominated diphenyl ethers (PBDEs) and some perfluoroalkyl substances (PFASs) were analyzed in 17 bed sediments collected along the Saigon River and at adjacent canal mouths from upstream to downstream in Ho Chi Minh City (Vietnam). Concentrations were rather low for PAHs, as well as for legacy PCBs and dichloro-diphenyl-trichlorethane and metabolites (DDTs), or below detection limits for several PFASs and all PBDEs measured. Several insecticides (chlorpyrifos-ethyl, and the pyrethroids cypermethrin and λ-cyhalothrin) displayed rather high concentrations at a few sites within the city. There was no distinct upstream - downstream trend for PAHs, (DDTs) or PCBs. Although adjacent canal sediments tended to be more contaminated than Saigon River sediments, the differences were not significant. Emissions are almost certainly substantial for PAHs, and probably also for other contaminants such as PBDEs and some PFASs. During the dry season, contaminants are presumably stored in the city, either in canals or on urban surfaces. Heavy rainfall during the monsoon period carries away contaminated particle flows into the canals and then the Saigon River. The strong tidal influence in the river channel hinders the accumulation of contaminated particles. Contaminated deposits should accordingly be investigated further downstream in depositional environments, such as the mangrove.

Per- and poly-fluoroalkyl compounds in freshwater fish from the Rhône River: Influence of fish size, diet, prey contamination and biotransformation.

Pools of aquatic plants and benthic invertebrates were collected along with 47 individuals from three cyprinid fish species (Barbus barbus, Gobio gobio, Rutilus rutilus) at a site in the Rhône River (France). Carbon and nitrogen isotopic ratios (δ13C and δ15N) and a wide range of per- and poly-fluorinated chemicals (PFASs) were analysed in all samples. The sum of PFAS concentrations (ΣPFAS) increased from aquatic plants to fish dorsal muscles; molecular profiles were dominated by C9-C13 perfluorocarboxylic acids (PFCAs), while perfluorooctane sulfonate (PFOS) and perfluorooctane sulfonamide (FOSA) were detected in all samples at lower concentrations. ΣPFAS and especially ΣPFCAs were higher in barbels (B. barbus) than in other species, while roaches (R. rutilus) were less contaminated by PFOS than barbels and gudgeons (G. gobio). Gudgeons accumulated significantly higher FOSA concentrations. Young (small) barbels displayed significantly higher PFOS, perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) concentrations than did large specimens; conversely, perfluorotetradecanoic acid (PFTeDA) concentrations were significantly higher in large barbels. Multiple linear regressions were performed on the whole set of fish samples with size, mass and isotopic ratios as explicative variables, and several single compounds as explained variables. Regardless of the compound, the regressions did not explain much of the contamination variability. However, adding species as a qualitative variable, i.e. performing analyses of covariance (ANCOVAs) improved the fit greatly, while adding sex did not. Diet (i.e. δ13C and δ15N) was the main factor explaining interspecific differences. Biotransformation was assessed by comparing concentration ratios of PFOS or FOSA to their precursors in the food-web compartments. These ratios increased from invertebrates to fish, and differed among fish species, suggesting that biotransformation occurred but was species-specific. Biomagnification factor calculations showed that C11-C13 PFCAs, PFOS and FOSA were apparently biomagnified in barbels and gudgeons.