Short- and medium-chain chlorinated paraffins in surface sediment from Lake Ontario.

Concentrations of short- and medium-chain chlorinated paraffins (SCCPs and MCCPs) were analyzed and investigated in surficial sediment collected in 2018 from ten different nearshore sites in Lake Ontario and the St. Lawrence River influenced by inputs from varying urban and historical land uses. Sites were grouped into two categories of tributary and lake according to their location. Results show that tributary sites had higher concentrations of total chlorinated paraffin (CP) than lake sites. Humber Bay, a lake site, had the highest total CP concentration (55,000 ng/gTOC) followed by Humber River, a tributary site (50,000 ng/gTOC). The lowest concentrations were found in eastern Lake Ontario and Lake St. Francis in the St. Lawrence River (540 ng/gTOC). Higher concentrations of chlorinated paraffins (CPs) were found where runoff and wastewater inputs from urban areas, current industrial activities, and population were the greatest. Levels of MCCPs were higher than SCCPs at all sites but one, Lake St. Francis. Among the SCCPs, C13 and among the MCCPs C14 were the dominant chain length alkanes, with C14 being the highest among both groups. The SCCPs and MCCPs profiles suggest that they can be used to distinguish between sites impacted by local sources vs. sites impacted by short-/long-range transport of these chemicals.

Reductions of Plastic Microbeads from Personal Care Products in Wastewater Effluents and Lake Waters Following Regulatory Actions.

Plastic microbeads were widely used as exfoliants in personal care products (PCPs; e.g., hand/body washes) in North America, but restrictions were imposed on their use in PCPs in the U.S. (2017) and Canada (2018). We provide the first assessment of whether restrictions are effectively reducing microbeads entering surface waters. We examined their abundance, character, and trends in wastewater treatment plant (WWTP) effluents in Toronto, Canada, from 2016 to 2019, and in adjacent Lake Ontario surface waters (2015 and 2018), encompassing the period before and after the bans. Microbeads isolated from PCPs purchased in 2015 provided a visual morphological key with "irregular" and "spherical" microbead categories. Median concentrations of irregular microbeads, composed of polyethylene plastic, declined by up to 86% in WWTP effluents from 8.4 to 14.3 particles/m3 before to 2.0-2.2 particles/m3 after the bans, while those of spherical microbeads, predominantly synthetic/polyethylene wax, ranged within 0.5-2.3 particles/m3 and did not differ before and after the bans since, as nonplastic, they were not regulated. Similarly, amounts of irregular microbeads declined relative to spherical microbeads in Lake Ontario, indicating that product changes may be influencing observations in lake waters. The results suggest that the Canadian and U.S. restrictions effectively and rapidly reduced plastic microbeads entering waters via WWTPs.

Size-Resolved Identification and Quantification of Micro/Nanoplastics in Indoor Air Using Pyrolysis Gas Chromatography-Ion Mobility Mass Spectrometry.

Humans are exposed to differing levels of micro/nanoplastics (MNPs) through inhalation, but few studies have attempted to measure <1 µm MNPs in air, in part due to a paucity of analytical methods. We developed an approach to identify and quantify MNPs in indoor air using a novel pyrolysis gas chromatographic cyclic ion mobility mass spectrometer (pyr-GCxcIMS). Four common plastic types were targeted for identification, namely, (polystyrene (PS), polyethylene (PE), polypropylene (PP), and polymethyl methacrylate (PMMA). The method was applied to size-resolved particulate (56 nm to 18 µm) collected from two different indoor environments using a Micro-Orifice Uniform Deposit Impactors (MOUDI) model 110 cascade impactor. Comprehensive two-dimensional separation by GCxcIMS also enabled the retrospective analysis of other polymers and plastic additives. The mean concentrations of MNP particles with diameters of <10 µm and <2.5 µm in the laboratory were estimated to be 47 ± 5 and 27 ± 4 µg/m3, respectively. In the private residence, the estimated concentrations were 24 ± 3 and 16 ± 2 µg/m3. PS was the most abundant MNP type in both locations. Nontargeted screening revealed the presence of plastic additives, such as TDCPP (tris(1,3-dichloro-2-propyl)phosphate) whose abundance correlated with that of polyurethane (PU). This is consistent with their use as flame retardants in PU-based upholstered furniture and building insulation. This study provides evidence of indoor exposure to MNPs and underlines the need for further study of this route of exposure to MNPs and the plastic additives carried with them.

Passive-Sampler-Derived PCB and OCP Concentrations in the Waters of the World─First Results from the AQUA-GAPS/MONET Network.

Persistent organic pollutants (POPs) are recognized as pollutants of global concern, but so far, information on the trends of legacy POPs in the waters of the world has been missing due to logistical, analytical, and financial reasons. Passive samplers have emerged as an attractive alternative to active water sampling methods as they accumulate POPs, represent time-weighted average concentrations, and can easily be shipped and deployed. As part of the AQUA-GAPS/MONET, passive samplers were deployed at 40 globally distributed sites between 2016 and 2020, for a total of 21 freshwater and 40 marine deployments. Results from silicone passive samplers showed α-hexachlorocyclohexane (HCH) and γ-HCH displaying the greatest concentrations in the northern latitudes/Arctic Ocean, in stark contrast to the more persistent penta (PeCB)- and hexachlorobenzene (HCB), which approached equilibrium across sampling sites. Geospatial patterns of polychlorinated biphenyl (PCB) aqueous concentrations closely matched original estimates of production and use, implying limited global transport. Positive correlations between log-transformed concentrations of Σ7PCB, ΣDDTs, Σendosulfan, and Σchlordane, but not ΣHCH, and the log of population density (p < 0.05) within 5 and 10 km of the sampling sites also supported limited transport from used sites. These results help to understand the extent of global distribution, and eventually time-trends, of organic pollutants in aquatic systems, such as across freshwaters and oceans. Future deployments will aim to establish time-trends at selected sites while adding to the geographical coverage.

The influence of complex matrices on method performance in extracting and monitoring for microplastics.

Previous studies have evaluated method performance for quantifying and characterizing microplastics in clean water, but little is known about the efficacy of procedures used to extract microplastics from complex matrices. Here we provided 15 laboratories with samples representing four matrices (i.e., drinking water, fish tissue, sediment, and surface water) each spiked with a known number of microplastic particles spanning a variety of polymers, morphologies, colors, and sizes. Percent recovery (i.e., accuracy) in complex matrices was particle size dependent, with ∼60-70% recovery for particles >212 µm, but as little as 2% recovery for particles <20 µm. Extraction from sediment was most problematic, with recoveries reduced by at least one-third relative to drinking water. Though accuracy was low, the extraction procedures had no observed effect on precision or chemical identification using spectroscopy. Extraction procedures greatly increased sample processing times for all matrices with the extraction of sediment, tissue, and surface water taking approximately 16, 9, and 4 times longer than drinking water, respectively. Overall, our findings indicate that increasing accuracy and reducing sample processing times present the greatest opportunities for method improvement rather than particle identification and characterization.

A fit-for-purpose categorization scheme for microplastic morphologies.

Microplastic categorization schemes are diverse, thereby posing challenges for cross-study comparisons. Further, categorization schemes are not necessarily aligned with and, thus, useful for applications such as source reduction initiatives. To address these challenges, we propose a hierarchical categorization approach that is "fit for purpose" to enable the use of a scheme that is tailored to the study's purpose and contains categories, which, if adopted, would facilitate interstudy comparison. The hierarchical categorization scheme is flexible to support various study purposes (e.g., to support regulation and toxicity assessment) and it aims to improve the consistency and comparability of microplastics categorization. Categorization is primarily based on morphology, supplemented by other identification methods as needed (e.g., spectroscopy). The use of the scheme was illustrated through a literature review aimed at critically evaluating the categories used for reporting microplastic morphologies in North American freshwater environments. Categorization and grouping schemes for microplastic particles were highly variable, with up to 19 different categories used across 68 studies, and nomenclature was inconsistent across particle morphologies. Our review demonstrates the necessity for a "fit for purpose" categorization scheme to guide the information needs of scientists and decision-makers for various research and regulatory objectives across global, regional, and local scales. Integr Environ Assess Manag 2023;19:422-435. © 2022 SETAC.

Maternal exposure to polystyrene microplastics alters placental metabolism in mice.

INTRODUCTION: The rapid growth in the worldwide use of plastics has resulted in a vast accumulation of microplastics in the air, soil and water. The impact of these microplastics on pregnancy and fetal development remains largely unknown. In pregnant mice, we recently demonstrated that exposure to micro- and nanoplastics throughout gestation resulted in significant fetal growth restriction. One possible explanation for reduced fetal growth is abnormal placental metabolism. OBJECTIVES: To evaluate the effect of maternal exposure to microplastics on placental metabolism. METHODS: In the present study, CD-1 pregnant mice were exposed to 5 µm polystyrene microplastics in filtered drinking water at one of four concentrations (0 ng/L (controls), 102 ng/L, 104 ng/L, 106 ng/L) throughout gestation (n = 7-11/group). At embryonic day 17.5, placental tissue samples were collected (n = 28-44/group). Metabolite profiles were determined using 1 H high-resolution magic angle spinning magnetic resonance spectroscopy. RESULTS: The relative concentration of lysine (p = 0.003) and glucose (p < 0.0001) in the placenta were found to decrease with increasing microplastic concentrations, with a significant reduction at the highest exposure concentration. Multivariate analysis identified shifts in the metabolic profile with MP exposure and pathway analysis identified perturbations in the biotin metabolism, lysine degradation, and glycolysis/gluconeogenesis pathways. CONCLUSION: Maternal exposure to microplastics resulted in significant alterations in placental metabolism. This study highlights the potential impact of microplastic exposure on pregnancy outcomes and that efforts should be made to minimize exposure to plastics, particularly during pregnancy.

Local Monitoring Should Inform Local Solutions: Morphological Assemblages of Microplastics Are Similar within a Pathway, But Relative Total Concentrations Vary Regionally.

Pathways for microplastics to aquatic ecosystems include agricultural runoff, urban runoff, and treated or untreated wastewater. To better understand the importance of each pathway as a vector for microplastics into waterbodies and for mitigation, we sampled agricultural runoff, urban stormwater runoff, treated wastewater effluent, and the waterbodies downstream in four regions across North America: the Sacramento Delta, the Mississippi River, Lake Ontario, and Chesapeake Bay. The highest concentrations of microplastics in each pathway varied by region: agricultural runoff in the Sacramento Delta and Mississippi River, urban stormwater runoff in Lake Ontario, and treated wastewater effluent in Chesapeake Bay. Material types were diverse and not unique across pathways. However, a PERMANOVA found significant differences in morphological assemblages among pathways (p < 0.005), suggesting fibers as a signature of agricultural runoff and treated wastewater effluent and rubbery fragments as a signature of stormwater. Moreover, the relationship between watershed characteristics and particle concentrations varied across watersheds (e.g., with agricultural parameters only being important in the Sacramento Delta). Overall, our results suggest that local monitoring is essential to inform effective mitigation strategies and that assessing the assemblages of morphologies should be prioritized in monitoring programs to identify important pathways of contamination.

Factors driving the spatial distribution of microplastics in nearshore and offshore sediment of Lake Huron, North America.

Offshore and nearshore sediment samples from Lake Huron, North America, were analysed for microplastics. Normalized abundances ranged from 59 to 335,714 particles per kg of dry weight sediment (p kg-1 dw). Of the four main basins of Lake Huron, the North Channel contained the greatest microplastic abundances, averaging 47,398 p kg-1 dw, followed by Georgian Bay (21,390 p kg-1 dw), the main basin (15,910 p kg-1 dw) and Saginaw Bay (1592 p kg-1 dw). Results indicate that greater lake depths (p = 0.004), associated with finer grained sediment (p = 0.048), are significant zones of deposition. Regression analysis reveals that source-driven factors generally do not account for microplastic abundances and distribution. Instead, process-driven hydrodynamic forces such as waves and surface currents could be driving distribution and deposition into the offshore environment. The findings suggest that these often overlooked processes should be considered when investigating microplastics quantity in bottom sediment of large lakes.

Organophosphate esters in Great Lakes fish: An improved analysis to assess concentrations and human exposure via consumption.

Organophosphate esters (OPEs) are flame retardant and plasticizer chemicals added to electronics, furniture, textiles, and other building materials and consumer products. In this study, fillets of fish often caught by anglers in the North American Great Lakes, Lake Trout (Salvelinus namaycush) across four Great Lakes and nearshore fish species near the large urban and industrial centers of Toronto and Hamilton, Canada, were analyzed for 22 OPEs. A rapid microextraction of homogenized tissues with methanol dramatically reduced preparation and sample handling time while achieving recoveries of 69-141%, and the optimized liquid chromatographic separation improved isomeric separations, including aryl-OPEs. Twelve of the 22 OPEs were detected, with frequencies of detection ranging from 8.3% to 98%, and five compounds were detected in >50% of the fish. The average ± standard deviation for the sum of 12 OPEs (ΣOPE12) ranged from 9.6 ± 0.9 (L. Erie 2017) to 74 ± 44 (L. Superior 2001) ng/g wet weight in Lake Trout, and 12 ± 2.7 to 35 ± 30 ng/g wet weight in nearshore fish species from the Toronto and Hamilton areas. The aryl-OPEs were dominant in Lake Trout, comprising 32-77% of total ΣOPE12 concentrations. In nearshore fish, the OPE patterns reflected the relative degree of exposure to run-off and wastewater inputs in the sampled receiving environments. The intake of OPEs via human consumption of Great Lakes Lake Trout and nearshore fish was estimated to range 6.5-31 ng/kg body weight/day, which is approximately 1-2 orders of magnitude lower than exposures via indoor air and ingestion/inhalation of dusts, and 3 orders of magnitude lower than estimated reference doses. The inclusion of additional OPE analytes enabled patterns of exposure and accumulation to be distinguished in fish of different species and location, and were related to source and food web influences.

Microplastic contamination in Great Lakes fish.

Freshwater ecosystems, generally adjacent to human population and more contaminated relative to adjacent marine ecosystems, are vulnerable to microplastic contamination. We sampled 7 species of fish from Lake Ontario and Lake Superior and assessed their gastrointestinal (GI) tracts to quantify ingested microplastics and other anthropogenic particles. A subset of the microparticles were chemically analyzed to confirm polymer types and anthropogenic origins. We documented the highest concentration of microplastics and other anthropogenic microparticles ever reported in bony fish. We found 12,442 anthropogenic microparticles across 212 fish (8 species) from nearshore Lake Ontario, 943 across 50 fish (1 species) from Humber River, and 3094 across 119 fish (7 species) from Lake Superior. Fish from Lake Ontario had the greatest mean abundance of anthropogenic microparticles in their GI tracts (59 particles/fish [SD 104]), with up to 915 microparticles in a single fish. Fish from Lake Superior contained a mean [SD] of 26 [74] particles/fish, and fish from Humber River contained 19 [14] particles/fish. Most particles were microfibers. Overall, ≥90% of particles were anthropogenic, of which 35-59% were microplastics. Polyethylene (24%), polyethylene terephthalate (20%), and polypropylene (18%) were the most common microplastics. Ingestion of anthropogenic particles was significantly different among species within Lake Ontario (p < 0.05), and the abundance of anthropogenic particles increased as fish length increased in Lake Ontario (ρ = 0.62). Although we cannot extrapolate the concentration of microplastics in the water and sediments of these fish, the relatively high abundance of microplastics in the GI tracts of fish suggests environmental exposure may be above threshold concentrations for risk.

Contaminación por Microplásticos en Peces de los Grandes Lagos Resumen Los ecosistemas de agua dulce, generalmente contiguos a poblaciones humanas y más contaminados en relación con los ecosistemas marinos adyacentes, son vulnerables a la contaminación por microplásticos. Muestreamos siete especies de peces del Lago Ontario y del Lago Superior y analizamos sus tractos gastrointestinales (GI) para cuantificar los microplásticos ingeridos, además de otras partículas antropogénicas. Un subconjunto de las micropartículas fue analizado químicamente para confirmar los tipos de polímero y los orígenes antropogénicos. Documentamos la concentración más alta de microplásticos y de otras micropartículas antropogénicas jamás reportada en peces óseos. Encontramos 12,442 micropartículas antropogénicas en 212 peces (ocho especies) del Lago Ontario, 943 en 50 peces (una especie) en el Río Humber y 30,094 en 119 peces (siete especies) del Lago Superior. Los peces del Lago Ontario tuvieron la mayor abundancia promedio de micropartículas antropogénicas en sus tractos GI (59 partículas/pez [DS 104]), con hasta 915 micropartículas en un solo pez. Los peces del Lago Superior tuvieron un promedio [DS] de 26 [74] partículas/pez y los peces del Río Humber tuvieron 19 [14] partículas/pez. La mayoría de las partículas eran microfibras. En general, ≥90% de las partículas eran antropogénicas, de las cuales el 35-39% eran microplásticos. El polietileno (24%), el tereftalato de polietileno (20%) y el polipropileno (18%) fueron los microplásticos más comunes. La ingesta de partículas antropogénicas tuvo una diferencia significativa entre las especies del Lago Ontario (p < 0.05) y la abundancia de las partículas antropogénicas incrementó conforme aumentó la longitud de los peces en el Lago Ontario (ρ = 0.62). Aunque no podemos extrapolar la concentración de microplásticos en el agua y los sedimentos para estos peces, la abundancia relativamente alta de microplásticos en los tractos GI de los peces sugiere que la exposición ambiental puede estar por encima del umbral de concentraciones para el riesgo.

NMR spectroscopy of wastewater: A review, case study, and future potential.

NMR spectroscopy is arguably the most powerful tool for the study of molecular structures and interactions, and is increasingly being applied to environmental research, such as the study of wastewater. With over 97% of the planet's water being saltwater, and two thirds of freshwater being frozen in the ice caps and glaciers, there is a significant need to maintain and reuse the remaining 1%, which is a precious resource, critical to the sustainability of most life on Earth. Sanitation and reutilization of wastewater is an important method of water conservation, especially in arid regions, making the understanding of wastewater itself, and of its treatment processes, a highly relevant area of environmental research. Here, the benefits, challenges and subtleties of using NMR spectroscopy for the analysis of wastewater are considered. First, the techniques available to overcome the specific challenges arising from the nature of wastewater (which is a complex and dilute matrix), including an examination of sample preparation and NMR techniques (such as solvent suppression), in both the solid and solution states, are discussed. Then, the arsenal of available NMR techniques for both structure elucidation (e.g., heteronuclear, multidimensional NMR, homonuclear scalar coupling-based experiments) and the study of intermolecular interactions (e.g., diffusion, nuclear Overhauser and saturation transfer-based techniques) in wastewater are examined. Examples of wastewater NMR studies from the literature are reviewed and potential areas for future research are identified. Organized by nucleus, this review includes the common heteronuclei (13C, 15N, 19F, 31P, 29Si) as well as other environmentally relevant nuclei and metals such as 27Al, 51V, 207Pb and 113Cd, among others. Further, the potential of additional NMR methods such as comprehensive multiphase NMR, NMR microscopy and hyphenated techniques (for example, LC-SPE-NMR-MS) for advancing the current understanding of wastewater are discussed. In addition, a case study that combines natural abundance (i.e. non-concentrated), targeted and non-targeted NMR to characterize wastewater, along with in vivo based NMR to understand its toxicity, is included. The study demonstrates that, when applied comprehensively, NMR can provide unique insights into not just the structure, but also potential impacts, of wastewater and wastewater treatment processes. Finally, low-field NMR, which holds considerable future potential for on-site wastewater monitoring, is briefly discussed. In summary, NMR spectroscopy is one of the most versatile tools in modern science, with abilities to study all phases (gases, liquids, gels and solids), chemical structures, interactions, interfaces, toxicity and much more. The authors hope this review will inspire more scientists to embrace NMR, given its huge potential for both wastewater analysis in particular and environmental research in general.

Nontargeted Screening Using Gas Chromatography-Atmospheric Pressure Ionization Mass Spectrometry: Recent Trends and Emerging Potential.

Gas chromatography-high-resolution mass spectrometry (GC-HRMS) is a powerful nontargeted screening technique that promises to accelerate the identification of environmental pollutants. Currently, most GC-HRMS instruments are equipped with electron ionization (EI), but atmospheric pressure ionization (API) ion sources have attracted renewed interest because: (i) collisional cooling at atmospheric pressure minimizes fragmentation, resulting in an increased yield of molecular ions for elemental composition determination and improved detection limits; (ii) a wide range of sophisticated tandem (ion mobility) mass spectrometers can be easily adapted for operation with GC-API; and (iii) the conditions of an atmospheric pressure ion source can promote structure diagnostic ion-molecule reactions that are otherwise difficult to perform using conventional GC-MS instrumentation. This literature review addresses the merits of GC-API for nontargeted screening while summarizing recent applications using various GC-API techniques. One perceived drawback of GC-API is the paucity of spectral libraries that can be used to guide structure elucidation. Herein, novel data acquisition, deconvolution and spectral prediction tools will be reviewed. With continued development, it is anticipated that API may eventually supplant EI as the de facto GC-MS ion source used to identify unknowns.

No evidence of spherical microplastics (10-300 µm) translocation in adult rainbow trout (Oncorhynchus mykiss) after a two-week dietary exposure.

The consumption of fish contaminated with microplastics is often cited as a pathway for human exposure. However, because their guts are generally removed before consumption, exposure may be low compared to other routes such as shellfish, drinking water and dust. Still, microplastics have been found to translocate from the gut to other tissues, making exposure from eating fish fillets or other seafood products a potential concern. To better understand fish as an exposure route for microplastics in humans, we tested hypotheses about whether translocation occurs and if efficiency of translocation is dependent on particle size. We investigated the amount and distribution of fluorescent polyethylene microspheres (10-300 µm) in the gut, liver, fillets and gonads of adult rainbow trout after a two-week dietary exposure. Fish were fed food pellets dosed with up to ~9,800 microspheres per gram of food. Total exposures over the entire experiment ranged from ~80,000-850,000 microspheres per fish. We did not find any particles in the fillets, liver, or gonads of any fish, suggesting that translocation of spherical microplastics of this size range does not occur in adult rainbow trout. The quantity of microplastics found in the gut was also low or absent after a 24-hour depuration period, indicating effective excretion in this laboratory population. This research suggests that the consumption of fish fillets may not be a significant exposure pathway for microspheres >10 µm in size to contaminate humans. Future studies should test for different sizes, morphologies and species to further our understanding.

Performance of the organic-diffusive gradients in thin-films passive sampler for measurement of target and suspect wastewater contaminants.

Although passive sampling is widely accepted as an excellent tool for environmental monitoring, their integration with suspect or non-targeted screening by high-resolution mass spectrometry has been limited. This study describes the application of the organic-diffusive gradients in thin-films (o-DGT) passive sampler as a tool for accurate measurement of both targeted and suspect polar organic contaminants (primarily pharmaceuticals) in wastewater. First, performance of o-DGT was assessed alongside the polar organic chemical integrative sampler (POCIS) and active sampling at two wastewater treatment facilities using targeted analyses. Overall, water concentrations measured by o-DGT, POCIS, and 24-hr integrative active samples were in good agreement with each other. There were exceptions, including a systematic difference between o-DGT and POCIS at certain sites that we propose was a result of site-specific conditions and a difference in sampling rates between the two techniques. The second component of this work involved suspect screening of the o-DGT extracts using high-resolution, high mass accuracy quadrupole time-of-flight mass spectrometry (QTOF). Lamotrigine, venlafaxine, and des-methylvenlafaxine were three suspect compounds identified and selected as proof-of-concept case studies to determine the feasibility and accuracy of o-DGT for estimating water concentrations based upon predicted sampling rates using a previously validated o-DGT diffusion model. Semi-quantification of the suspect compounds was conducting using an average surrogate response factor based on the suite of compounds measured by the targeted analyses. This, combined with the modelled sampling rates provided time-weighted average wastewater concentrations of the identified suspects within a factor of 2 of the true value, confirmed by isotope dilution with mass labelled internal surrogates. To the knowledge of the authors, this work is the first to demonstrate the utility of the o-DGT passive sampler as a potential environmental screening tool that can be integrated into the rapidly advancing field of non-targeted high resolution mass spectrometry.

Rapid fingerprinting of source and environmental microplastics using direct analysis in real time-high resolution mass spectrometry.

Microplastics are ubiquitous in the aquatic and terrestrial environment. To prevent further contamination, methods to determine their sources are needed. Techniques to quantify and characterize microplastics in the environment are still evolving for polymers and the additives and leachable substances embedded therein, which constitute the "chemical fingerprint" of an environmental microplastic. There is a critical need for analytical methods that yield such diagnostic information on environmental microplastics that enables identification of their composition and sources of pollution. This study reports on a novel approach for rapid fingerprinting of environmental microplastics and the screening of additives using Direct Analysis in Real Time (DART)-high resolution mass spectrometry. A variety of plastic samples were investigated, including virgin pre-production pellets, microbeads from personal care products, microplastics found in the aquatic environment, and synthetic fibers. The resulting mass spectra display ∼10,000 discrete peaks, corresponding to plastic additives released by thermal desorption and polymer degradation products generated by pyrolysis. These were used to characterize differences among plastic types, microplastic source materials, and environmental samples. Multivariate statistics and elemental composition analysis approaches were applied to analyze fingerprints from the mass spectra. This promising analytical approach is sensitive, (potentially) high-throughput, and can aid in the elucidation of possible sources of microplastics and perhaps eventually to the analysis of bulk environmental samples for plastics.

Compositional space: A guide for environmental chemists on the identification of persistent and bioaccumulative organics using mass spectrometry.

Since 2001, twenty-eight halogenated groups of persistent organic pollutants (POPs) have been banned or restricted by the Stockholm Convention. Identifying new POPs among the hundreds of thousands of anthropogenic chemicals is a major challenge that is increasingly being met by state-of-the-art mass spectrometry (MS). The first step to identification of a contaminant molecule (M) is the determination of the type and number of its constituent elements, viz. its elemental composition, from mass-to-charge (m/z) measurements and ratios of isotopic peaks (M + 1, M + 2 etc.). Not every combination of elements is possible. Boundaries exist in compositional space that divides feasible and improbable compositions as well as different chemical classes. This study explores the compositional space boundaries of persistent and bioaccumulative organics. A set of ~305,134 compounds (PubChem) was used to visualize the compositional space occupied by F, Cl, and Br compounds, as defined by m/z and isotope ratios. Persistent bioaccumulative organics, identified by in silico screening of 22,049 commercial chemicals, reside in more constrained regions characterized by a higher degree of halogenation. In contrast, boundaries surrounding non-halogenated chemicals could not be defined. Finally, a script tool (R code) was developed to select potential POPs from high resolution MS data. When applied to household dust (SRM 2585), this approach resulted in the discovery of previously unknown chlorofluoro flame retardants.

Characterization of Polycyclic Aromatic Compounds in Commercial Pavement Sealcoat Products for Enhanced Source Apportionment.

Coal tar-based sealcoat (CTSC) products are an urban source of polycyclic aromatic compounds (PACs) to the environment. However, efforts to assess the environmental fate and impacts of CTSC-derived PACs are hindered by the ubiquity of (routinely monitored) PACs released from other environmental sources. To advance source identification of CTSC-derived PACs, we use comprehensive two-dimensional gas chromatography-high resolution mass spectrometry (GC × GC/HRMS) to characterize the major and minor components of CTSC products in comparison to those in other sources of PACs, viz., asphalt-based sealcoat products, diesel particulate, diesel fuel, used motor oil and roofing shingles. GC × GC/HRMS analyses of CTSC products led to the confident assignment of compounds with 88 unique elemental compositions, which includes a set of 240 individual PACs. Visualization of the resulting profiles using Kendrick mass defect plots and hierarchical cluster analysis highlighted compositional differences between the sources. Profiles of alkylated PAHs, and heteroatomic (N, O, S) PACs enabled greater specificity in source differentiation. Isomers of specific polycyclic aromatic nitrogen heterocycles (PANHs) were diagnostic for coal tar-derived PAC sources. The compounds identified and methods used for this identification are anticipated to aid in future efforts on risk assessment and source apportionment of PACs in environmental matrices.

Metabolomic responses to pre-chlorinated and final effluent wastewater with the addition of a sub-lethal persistent contaminant in Daphnia magna.

Consumer products such as perfluorooctanesulfonic acid (PFOS) and pharmaceuticals (PCPPs) enter aquatic ecosystems through inefficient removal during wastewater treatment. Often, the sterilization process of wastewater includes the addition of sodium hypochlorite that can react with PCPPs and other organic matter (i.e., dissolve organic matter) to generate disinfection by-products and can cause the final effluent to be more harmful to aquatic organisms. Here, we exposed Daphnia magna to two stages of wastewater, the pre-chlorinated wastewater (PreCl) and the final effluent. In addition, we exposed D. magna, to the final effluent with a concentration gradient of added PFOS, to investigate if this persistent contaminant altered the toxicity of the final effluent. After 48 h of contaminant exposure, we measured the daphnids metabolic responses to the different stages of wastewater treatment, and with the addition of PFOS, utilizing proton nuclear magnetic resonance spectroscopy and liquid chromatography tandem mass spectrometry. We found few significant changes to the metabolic profile of animals exposed to the PreCl wastewater; however, animals exposed to the final effluent displayed increases in many amino acids and decreases in some sugar metabolites. With the addition of PFOS to the final effluent, the metabolic profile shifted from increased amino acids and decreased sugar metabolites and energy molecules especially at the low and high concentrations of PFOS. Overall, our results demonstrate the metabolome is sensitive to changes in the final effluent that are caused by sterilization, and with the addition of a persistent contaminant, the metabolic profile is further altered.

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans associated with settling particles in Lake Ontario.

Sediment traps were deployed at seven sites in the western and central basins of Lake Ontario for calculation of concentrations and down fluxes for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) to assess ongoing loadings to Lake Ontario from the Niagara River watershed. Traps were deployed at multiple depths (beginning at 20 m) during two seasonal time periods at stations impacted by the outflow of the Niagara River, and stations reflecting deeper water offshore conditions. Settling particles were collected seasonally to assess the influence of physical characteristics of the water column, i.e., isothermal conditions vs. stratified conditions, on concentrations and fluxes of PCDD/Fs. At all stations and for all depth intervals, PCDD/F concentrations were higher in the winter sampling period (range of 3120-10,600 pg g-1), compared to the spring - summer - fall time period (range of 320-6900 pg g-1). These results indicated bottom sediments in central and western Lake Ontario were more highly-contaminated, compared to contemporary particulate material entering the lake via the Niagara River or resulting from shoreline erosion. However, assessment of PCDD/F congener profiles and ratios also indicated source areas within the Niagara River watershed continued to episodically contribute loadings to Lake Ontario. The results also indicated changes in discharges of PCDD/Fs from sources in the Niagara River result in changes in congener profiles in settling particles, which can be detected by continued monitoring.