Total Oxidizable Precursor (TOP) Assay-Best Practices, Capabilities and Limitations for PFAS Site Investigation and Remediation.

The comprehensive characterization of per- and polyfluoroalkyl substances (PFASs) is necessary for the effective assessment and management of risk at contaminated sites. While current analytical methods are capable of quantitatively measuring a number of specific PFASs, they do not provide a complete picture of the thousands of PFASs that are utilized in commercial products and potentially released into the environment. These unmeasured PFASs include many PFAS precursors, which may be converted into related PFAS chemicals through oxidation. The total oxidizable precursor (TOP) assay offers a means of bridging this gap by oxidizing unknown PFAS precursors and intermediates and converting them into stable PFASs with established analytical standards. The application of the TOP assay to samples from PFAS-contaminated sites has generated several new insights, but it has also presented various technical challenges for laboratories. Despite the increased number of literature studies that include the TOP assay, there is a critical and growing gap in the application of this method beyond researchers in academia. This article outlines the benefits and challenges of using the TOP assay with aqueous samples for site assessments and suggests ways to address some of its limitations.

Assessment of filter subsampling and extrapolation for quantifying microplastics in environmental samples using Raman spectroscopy.

A common method for characterizing microplastics (MPs) involves capturing the plastic particles on a filter after extraction and isolation from the sediment particles. Microplastics captured on the filter are then scanned with Raman spectroscopy for polymer identification and quantification. However, scanning the whole filter manually using Raman analysis is a labor-intensive and time-consuming process. This study investigates a subsampling method for Raman spectroscopic analysis of microplastics (operationally defined here as 45-1000 µm in size) present in sediments and isolated onto laboratory filters. The method was evaluated using spiked MPs in deionized water and two environmentally contaminated sediments. Based on statistical analyses, we found quantification of a sub-fraction of 12.5 % of the filter in a wedge form was optimal, efficient, and accurate for estimating the entire filter count. The extrapolation method was then used to assess microplastic contamination in sediments from different marine regions of the United States.

Delivering outpatient virtual clinics during the COVID-19 pandemic: early evaluation of clinicians' experiences.

BACKGROUND: The COVID-19 pandemic has put health systems across the world under significant pressure. In March 2020, a national directive was issued by the National Health Service (NHS) England instructing trusts to scale back face-to-face outpatient appointments, and rapidly implement virtual clinics. METHODS: A multidisciplinary team of change managers, analysts and clinicians were assembled to evaluate initial implementation of virtual clinics at Guy's and St Thomas' NHS Foundation Trust. In-depth interviews were conducted with clinicians who have delivered virtual clinics during the pandemic. An inductive thematic approach was used to analyse clinicians' early experiences and identify enablers for longer term sustainability. RESULTS: Ninety-five clinicians from specialist services across the trust were interviewed between April and May 2020 to reflect on their experiences of delivering virtual clinics during Wave I COVID-19. Key reflections include the perceived benefits of virtual consultations to patients and clinicians; the limitations of virtual consultations compared with face-to-face consultations; and the key enablers that would optimise and sustain the delivery of virtual pathways longer term. CONCLUSIONS: In response to the pandemic, outpatient services across the trust were rapidly redesigned and virtual clinics implemented. As a result, services have been able to sustain some level of service delivery. However, clinicians have identified challenges in delivering this model of care and highlighted enablers needed to sustaining the delivery of virtual clinics longer term, such as patient access to diagnostic tests and investigations closer to home.

Quantification of microplastics in sediments from Narragansett Bay, Rhode Island USA using a novel isolation and extraction method.

Microplastics are small plastic particles found ubiquitously in marine environments. In this study, a hybridized method was developed for the extraction of microplastics (45-1000 µm) from sediments using sodium bromide solution for density separation. Method development was tested using spiked microplastics as internal standards. The method was then used to extract microplastics from sediments in Narragansett Bay, Rhode Island, USA. Suspect microplastics were analyzed with Raman spectroscopy. Microplastic abundance ranged from 40 particles/100 g sediment to 4.6 million particles/100 g sediment (wet weight). Cellulose acetate fibers were the most abundant microplastic. These results are some of the first data for microplastics in Rhode Island sediments.

Comparison of microplastic isolation and extraction procedures from marine sediments.

Microplastics (MPs) are small (<5 mm) plastic particles which pose a threat to marine ecosystems. Identifying MPs is crucial for understanding their fate and effects. Many MP extraction methods exist, but procedural differences prevent meaningful comparisons across datasets. This method comparison examines the efficiency of five methods for extracting MPs (40-710 µm) from marine sediments. Known quantities of MPs were spiked into sediments. The MPs were extracted and enumerated to demonstrate percent recovery. Findings determined that sediment matrix, MP properties, and extraction method affect the percent recovery of MPs from sediments. Average recoveries of spiked microplastics were between 0 and 87.4% and varied greatly by sediment type, microplastic, and method of extraction. In general, larger particle and lower density MPs were more effectively recovered. Marine sediments low in organic matter and with larger grain size also had higher percent recoveries of MPs. These findings support the need for method optimization and unified procedures.

Contaminants, mutagenicity and toxicity in the surface waters of Kyiv, Ukraine.

Kyiv is Ukraine's capital and largest city. Home to 3 million people, this area has a rich history of agriculture and industry. The Dnieper River is Ukraine's largest river and it passes through the center of Kyiv. Little information on emerging and legacy compounds or their toxicity in the Dnieper River exists. For this investigation, water was sampled for PAHs, PCBs, metals and emerging contaminants including pharmaceuticals and personal care products. The effects of surface waters in the Dnieper were evaluated using the Ames, chronic and acute daphnia, and a ciliate (Colpoda stennii) assays. Concentrations of legacy and emerging contaminants were found in seven stations near the municipal water treatment plant (MWTP) and receiving waters. The MWTP appeared to remove some of the emerging contaminants, however the legacy compounds (PCBs and PAHs) were not affected by the MWTP and appeared to be more wide-spread indicating a number of sources to the Dnieper River. Acute and chronic toxicity were associated with the influent and effluent of the MWTP, however mutagenicity was noted in surface waters throughout the Dnieper River including upstream of the MWTP. This study provides the first snapshot of possible human health and ecological risks associated with surface waters of the Dnieper. More research on seasonal changes and sources of toxicity, mutagenicity and contaminants would aid in completing a more comprehensive risk assessment of surface waters of the Dnieper River.

Identification of hydroxyl and sulfate free radicals involved in the reaction of 1,4-dioxane with peroxone activated persulfate oxidant.

This research investigates the formation of free radical intermediates in an advanced oxidation processes (AOP) capable of destroying recalcitrant contaminants. The AOP studied is marketed as OxyZone® and relies on the premise of successful persulfate activation by peroxone (hydrogen peroxide plus ozone) and the formation of free radicals. The goal of this research was to determine which radicals are involved in the treatment of the model contaminant, 1,4-dioxane, which is a ubiquitous, recalcitrant organic groundwater pollutant difficult to destroy by conventional oxidants. In a parallel study, the peroxone activation persulfate (PAP) solution investigated herein rapidly degraded 1,4-dioxane. The degradation rates of 1,4-dioxane were measured as a function the oxidant:contaminant ratio. Its degradation products or mechanism were not investigated, however. Electron paramagnetic resonance (EPR) spectroscopy spin trapping was used to identify radicals produced in the oxidant solution, its active ingredients, and their possible interplay. The data presented herein indicate that the combination of hydrogen peroxide and dissolved ozone in the presence of persulfate results in the co-occurrence hydroxyl and sulfate radicals and possibly superoxide/hydroperoxyl radicals. These findings progress our understanding of the chemical radicals formed during PAP treatment of aqueous phase contaminants, such as 1,4-dioxane.

Magnitude of acute toxicity of marine sediments amended with conventional copper and nanocopper.

It is well known that copper (Cu) is toxic to marine organisms. We measured and compared the acute toxicity of several forms of Cu (including nanoCu) amended into a marine sediment with mysids and amphipods. For all the forms of Cu tested, toxicity, measured as the median lethal concentration, ranged from 708 to > 2400 mg Cu/kg (dry sediment) for mysids and 258 to 1070 mg Cu/kg (dry sediment) for amphipods. Environ Toxicol Chem 2018;37:2677-2681. © 2018 SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Assessing the release of copper from nanocopper-treated and conventional copper-treated lumber into marine waters II: Forms and bioavailability.

One application of nanocopper is as a wood-preserving pesticide in pressure-treated lumber. Recent research has shown that pressure-treated lumber amended with micronized copper azole (MCA), which contains nanosized copper, releases copper under estuarine and marine conditions. The form of copper released (i.e., ionic, nanocopper [1-100 nm in size]) is not fully understood but will affect the bioavailability and toxicity of the metal. In the present study, multiple lines of evidence, including size fractionation, ion-selective electrode electrochemistry, comparative toxicity, and copper speciation were used to determine the form of copper released from lumber blocks and sawdust. The results of all lines of evidence supported the hypothesis that ionic copper was released from MCA lumber and sawdust, with little evidence that nanocopper was released. For example, copper concentrations in size fractionations of lumber block aqueous leachates including unfiltered, 0.1 µm, and 3 kDa were not significantly different, suggesting that the form of copper released was in the size range operationally defined as dissolved. These results correlated with the ion-selective electrode data which detects only ionic copper. In addition, comparative toxicity testing resulted in a narrow range of median lethal concentrations (221-257 µg/L) for MCA lumber blocks and CuSO4 . We conclude that ionic copper was released from the nanocopper pressure-treated lumber under estuarine and marine conditions. Environ Toxicol Chem 2018;37:1969-1979. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Assessing the release of copper from nanocopper-treated and conventional copper-treated lumber into marine waters I: Concentrations and rates.

Little is known about the release of metal engineered nanomaterials (ENMs) from consumer goods, including lumber treated with micronized copper. Micronized copper is a recent form of antifouling wood preservative containing nanosized copper particles for use in pressure-treated lumber. The present study investigated the concentrations released and the release rate of total copper over the course of 133 d under freshwater, estuarine, and marine salinity conditions (0, 1, 10, and 30‰) for several commercially available pressure-treated lumbers: micronized copper azole (MCA) at 0.96 and 2.4 kg/m3 , alkaline copper quaternary (ACQ) at 0.30 and 9.6 kg/m3 , and chromated copper arsenate (CCA) at 40 kg/m3 . Lumber was tested as blocks and as sawdust. Overall, copper was released from all treated lumber samples. Under leaching conditions, total release ranged from 2 to 55% of the measured copper originally in the lumber, with release rate constants from the blocks of 0.03 to 2.71 (units per day). Generally, measured release and modeled equilibrium concentrations were significantly higher in the estuarine conditions compared with freshwater or marine salinities, whereas rate constants showed very limited differences between salinities. Furthermore, organic carbon was released during the leaching and demonstrated a significant relationship with released copper concentrations as a function of salinity. The results indicate that copper is released into estuarine/marine waters from multiple wood treatments including lumber amended with nanoparticle-sized copper. Environ Toxicol Chem 2018;37:1956-1968. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Effects of micronized and nano-copper azole on marine benthic communities.

The widespread use of copper nanomaterials (CuNMs) as antibacterial and antifouling agents in consumer products increases the risk for metal contamination and adverse effects in aquatic environments. Information gaps exist on the potential toxicity of CuNMs in marine environments. We exposed field-collected marine meio- and macrobenthic communities to sediments spiked with micronized copper azole (MCA) using a novel method that brings intact benthic cores into the laboratory and exposes the organisms via surface application of sediments. Treatments included field and laboratory controls, 3 spiked sediments: low-MCA (51.9 mg/kg sediment), high-MCA (519 mg/kg sediment), and CuSO4 (519 mg/kg sediment). In addition, single-species acute testing was performed with both MCA and CuSO4. Our results indicate that meio- and macrofaunal assemblages exposed to High-MCA and CuSO4 treatments differed significantly from both the laboratory control and the low-MCA treatments. Differences in macrofauna were driven by decreases in 3 Podocopa ostracod species, the bivalve Gemma gemma, and the polychaetes Exogone verugera and Prionospio heterobranchia relative to the laboratory control. Differences in the meiofaunal community are largely driven by nematodes. The benthic community test results were more sensitive than the single-species test results. Findings of this investigation indicate that CuNMs represent a source of risk to marine benthic communities comparable to that of dissolved Cu. Environ Toxicol Chem 2018;37:362-375. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Aggregation, Sedimentation, Dissolution, and Bioavailability of Quantum Dots in Estuarine Systems.

To understand their fate and transport in estuarine systems, the aggregation, sedimentation, and dissolution of CdSe quantum dots (QDs) in seawater were investigated. Hydrodynamic size increased from 40 to 60 nm to >1 mm within 1 h in seawater, and the aggregates were highly polydispersed. Their sedimentation rates in seawater were measured to be 4-10 mm/day. Humic acid (HA), further increased their size and polydispersity, and slowed sedimentation. Light increased their dissolution and release of dissolved Cd. The ZnS shell also slowed release of Cd ions. With sufficient light, HA increased the dissolution of QDs, while with low light, HA alone did not change their dissolution. The benthic zone in estuarine systems is the most probable long-term destination of QDs due to aggregation and sedimentation. The bioavailability of was evaluated using the mysid Americamysis bahia. The 7-day LC50s of particulate and dissolved QDs were 290 and 23 µg (total Cd)/L, respectively. For mysids, the acute toxicity appears to be from Cd ions; however, research on the effects of QDs should be conducted with other organisms where QDs may be lodged in critical tissues such as gills or filtering apparatus and Cd ions may be released and delivered directly to those tissues.

Selected pharmaceuticals entering an estuary: Concentrations, temporal trends, partitioning, and fluxes.

In many coastal watersheds and ecosystems, rivers discharging to estuaries receive waters from domestic wastewater-treatment plants resulting in the release and distribution of pharmaceuticals to the marine environment. In the present study, 15 active pharmaceutical ingredients were measured regularly over 1 yr in the dissolved and particulate phases as they entered Narragansett Bay from the Pawtuxet River in Cranston (Rhode Island, USA). Of the active pharmaceutical ingredients measured, 14 were consistently present in the dissolved phase, with concentrations ranging from below detection to >310 ng/L, whereas 8 were present in the particulate phase (0.2-18 ng/g). Partition coefficients (Kd s and KOC s) were determined, and organic carbon normalization reduced variability associated with Kd s for the active pharmaceutical ingredients evaluated. Flux estimates based on river flow were calculated for both dissolved and particulate-phase active pharmaceutical ingredients, with particulate fluxes being low (1-12 g/yr) and dissolved fluxes of active pharmaceutical ingredients being 155 g/yr to 11 600 g/yr. Results indicate that the pharmaceuticals measured in the present study reside primarily in the dissolved phase and thus are likely bioavailable on entering the estuarine waters of Narragansett Bay. This long-term temporal study provides important information on seasonal and annual dynamics of pharmaceuticals in an urban estuarine watershed. Environ Toxicol Chem 2016;35:2665-2673. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America.