AQUA-GAPS/MONET-Derived Concentrations and Trends of PAHs and Polycyclic Musks across Global Waters.

Polycyclic aromatic hydrocarbons (PAHs), released from petrogenic, pyrogenic or diagenetic sources (degradation of wood materials), are of global concern due to their adverse effects, and potential for long-range transport. While dissolved PAHs have been frequently reported in the literature, there has been no consistent approach of sampling across water bodies. Passive samplers from the AQUA/GAPS-MONET initiative were deployed at 46 sites (28 marine and 18 freshwater), and analyzed for 28 PAHs and six polycyclic musks (PCMs) centrally. Freely dissolved PAH concentrations were dominated by phenanthrene (mean concentration 1500 pg L-1; median 530 pg L-1) and other low molecular weight compounds. Greatest concentrations of phenanthrene, fluoranthene, and pyrene were typically from the same sites, mostly in Europe and North America. Of the PCMs, only galaxolide (72% of samples) and tonalide (61%) were regularly detected, and were significantly cross-correlated. Benchmarking of PAHs relative to penta- and hexachlorobenzene confirmed that the most remote sites (Arctic, Antarctic, and mountain lakes) displayed below average PAH concentrations. Concentrations of 11 of 28 PAHs, galaxolide and tonalide were positively correlated (P < 0.05) with population density within a radius of 5 km of the sampling site. Characteristic PAH ratios gave conflicting results, likely reflecting multiple PAH sources and postemission changes.

Utility of a modified o-DGT passive sampler for measurement of bisphenol analogues in freshwater and coastal waters.

Bisphenol analogues (BPs) are commonly found in riverine and coastal waters. However, the lack of a reliable and robust passive sampling method has hindered our ability to monitor these compounds in aquatic systems. The study developed a novel organic-diffusive gradients in thin film (o-DGT) sampler based on stainless steel mesh membrane, polyacrylamide diffusive gel, and hydrophilic-lipophilic balance (HLB) binding gel. This innovative design tackled issues of filter membrane sorption in traditional o-DGT devices and potential gel damage in membrane-less o-DGT devices, showing promising application prospects. The mass accumulation of 15 target BPs was linear over 10 days in both freshwater (r2 ≥ 0.92) and seawater (r2 ≥ 0.94), with no saturation observed. The diffusion coefficients (D) through polyacrylamide diffusive gels ranged from 4.04 × 10-6 to 5.77 × 10-6 cm2 s-1 in freshwater and from 1.74 × 10-6 to 4.69 × 10-6 cm2 s-1 in seawater for the target BPs (except for bisphenol PH) at 22 °C. The D values of the target BPs in seawater were lower than those in freshwater due to the high salinity in seawater (35 ‰). The o-DGT samplers demonstrated good integrity in field applications. The total concentrations of the eight detected BPs ranged from 9.2 to 323 ng L-1, which was consistent with the measurements obtained by grab sampling. Among all BPs, bisphenol S, bisphenol F, and bisphenol A were consistently detected at all sites using both sampling methods. The concentrations of some novel BPs in coastal water measured by grab sampling were comparable to those measured in rivers, suggesting the need to strengthen pollution control of BPs in coastal areas. These results indicate that the o-DGT passive sampling method developed in the present study can be effectively used for monitoring BPs in freshwater and coastal environments.

Development of an accreditation process for analytical methods to measure microplastics in drinking water for regulatory monitoring.

Development of a laboratory accreditation program to ensure competency of laboratories performing analytical measurements is a key step in adopting new analytical measurement methods for regulatory decision-making. Here, we describe California's three-part accreditation process for spectroscopically measuring microplastics in drinking water, and show how data from a multi-laboratory method comparison study informed development of accreditation programs for the resulting methods, which can inform analogous future work for other analytes. The first part is periodic performance evaluation (PE) samples, in which laboratories are provided blind samples of known composition to quantify within acceptable performance limits. The second is inspection, or audit, assessing whether the laboratory has the proper equipment to conduct the work and whether it is correctly employing proper procedures. The third is implementation of a quality management system providing documentation that protocols demonstrated during inspection are continuously maintained. These fell into three broad categories: instrument maintenance; laboratory cleanliness, especially important for microplastics and one that must be accompanied by a blanks measurement and correction process; and training so samples are being processed by qualified analysts. An intercomparison exercise among 22 laboratories was necessary to determine what parameter permutations were important for PE samples, and expected accuracy from competent laboratories. The recommended PE sample composition was two size categories (20-50um and 500um-1mm), two polymer types, and two morphologies (fibers and non-fibers). Discussions among intercomparison exercise participants were key in determining the factors that most contributed to laboratory variability, and the focus for both on-site inspections and quality management systems.

Development and validation of an acid/alkaline digestion method for efficient microplastic extraction from wastewater treatment plant effluents: Sulfuric acid concentration and contact time do matter.

Accurate analysis of microplastic particles (MPs) in environmental samples requires removal of interferences during sample preparation. Wastewater samples are interference-rich and thus particularly challenging, with concentrated sulfuric acid currently deemed impractical as a reagent. Therefore, this study aimed to establish a straightforward, effective, and safe method employing concentrated sulfuric acid and potassium hydroxide to eliminate interferents from effluent samples obtained from wastewater treatment plants (WWTPs). We found that 80 % sulfuric acid at room temperature with a brief contact time of 5 min was viable through a qualitative spot test involving 37 plastics categorized into three types (I, II, and III) based on their polymer structure's oxygen position. A quantitative assessment revealed that treatments involving H2SO4 and KOH (20 %, 24 h, 48 °C), either separately or in combination, had no discernible physical impact on the overall plastics, except for a subtle one for Type III plastics (e.g., nylon and PMMA) known to be labile under harsh pH conditions. This acid/alkaline digestion (AAD) method, incorporating such conditions for H2SO4 and KOH treatments, yielded a high mass removal efficacy (97.8 ± 2.4 %, n = 13) for eliminating natural particle interferents for primary, secondary, and tertiary effluent samples. Furthermore, the AAD method allowed for the determination of MPs in effluents with high surrogate particle recoveries (e.g., 95.1 % for larger than 500 µm size fraction). This method is readily adaptable to create appropriate protocols for different types of environmental matrices.

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.

Patterns of microparticles in blank samples: A study to inform best practices for microplastic analysis.

Quality assurance and quality control (QA/QC) techniques are critical to analytical chemistry, and thus the analysis of microplastics. Procedural blanks are a key component of QA/QC for quantifying and characterizing background contamination. Although procedural blanks are becoming increasingly common in microplastics research, how researchers acquire a blank and report and/or use blank contamination data varies. Here, we use the results of laboratory procedural blanks from a method evaluation study to inform QA/QC procedures for microplastics quantification and characterization. Suspected microplastic contamination in the procedural blanks, collected by 12 participating laboratories, had between 7 and 511 particles, with a mean of 80 particles per sample (±SD 134). The most common color and morphology reported were black fibers, and the most common size fraction reported was 20-212 µm. The lack of even smaller particles is likely due to limits of detection versus lack of contamination, as very few labs reported particles <20 µm. Participating labs used a range of QA/QC techniques, including air filtration, filtered water, and working in contained/'enclosed' environments. Our analyses showed that these procedures did not significantly affect blank contamination. To inform blank subtraction, several subtraction methods were tested. No clear pattern based on total recovery was observed. Despite our results, we recommend commonly accepted procedures such as thorough training and cleaning procedures, air filtration, filtered water (e.g., MilliQ, deionized or reverse osmosis), non-synthetic clothing policies and 'enclosed' air flow systems (e.g., clean cabinet). We also recommend blank subtracting by a combination of particle characteristics (color, morphology and size fraction), as it likely provides final microplastic particle characteristics that are most representative of the sample. Further work should be done to assess other QA/QC parameters, such as the use of other types of blanks (e.g., field blanks, matrix blanks) and limits of detection and quantification.

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.

How to establish detection limits for environmental microplastics analysis.

Establishing analytical detection limits is crucial. Common methods to do so are suitable only for variables with continuous distributions. Because count data for microplastic particles is a discrete variable following the Poisson distribution, currently-used approaches for estimating the detection limit in microplastics analysis are inadequate. Here we evaluate detection limits with techniques for low-level discrete observations to develop proper approaches for estimating the minimum detectable amount (MDA) in microplastic particle analysis, using blank sample data from an interlaboratory calibration exercise for clean water (representing drinking water), dirty water (ambient water), sediment (porous media) and fish tissue (biotic tissues). Two MDAs are applicable: MDAA to evaluate analytical methods, estimated with replicate blank data; and MDAB for individual sample batches, calculated with a single blank count. For illustrative purposes, this dataset's overall MDAA values were 164 counts (clean water), 88 (dirty water), 192 (sediment), and 379 (tissue). MDA values should be reported on a laboratory-specific basis and for individual size fractions, as this provides more useful information about capabilities of individual laboratories. This is due to wide variation in blank levels, as noted by MDAB values (i.e., among different laboratories) from 14 to 158 (clean water), 9 to 86 (dirty water, 9 to 186 (sediment), and 9 to 247 (tissue). MDA values for fibers were considerably greater than for non-fibers, suggesting that separate MDA values should be reported. This study provides a guideline for estimation and application of microplastics MDA for more robust data to support research activities and environmental management decisions.

Comparison of two procedures for microplastics analysis in sediments based on an interlaboratory exercise.

Microplastics (MP) are distributed throughout ecosystems and settle into sediments where they may threaten benthic communities; however, methods for quantifying MP in sediments have not been standardized. This study compares two methods for analyzing MP in sediments, including extraction and identification, and provides recommendations for improvement. Two laboratories processed sediment samples using two methods, referred to as "core" and "augmentation", and identified particles with visual microscopy and spectroscopy. Using visual microscopy, the augmentation method yielded mean recoveries (78%) significantly greater than the core (47%) (p = 0.03), likely due to the use of separatory funnels in the former. Spectroscopic recovery of particles was lower at 42 and 54% for the core and augmentation methods, respectively. We suspect the visual identification recoveries are overestimations from erroneous identification of non-plastic materials persisting post-extraction, indicating visual identification alone is not an accurate method to identify MP, particularly in complex matrices like sediment. However, both Raman and FTIR proved highly accurate at identifying recovered MP, with 96.7% and 99.8% accuracy, respectively. Low spectroscopic recovery of spiked particles indicates that MP recovery from sediments is lower than previously assumed, and MP may be more abundant in sediments than current analyses suggest. To our knowledge, likely due to the excessive time/labor-intensity associated with MP analyses, this is the first interlaboratory study to quantify complete method performance (extraction, identification) for sediments, with regards to capabilities and limitations. This is essential as regulatory bodies move toward long-term environmental MP monitoring.

Quantitative assessment of visual microscopy as a tool for microplastic research: Recommendations for improving methods and reporting.

Microscopy is often the first step in microplastic analysis and is generally followed by spectroscopy to confirm material type. The value of microscopy lies in its ability to provide count, size, color, and morphological information to inform toxicity and source apportionment. To assess the accuracy and precision of microscopy, we conducted a method evaluation study. Twenty-two laboratories from six countries were provided three blind spiked clean water samples and asked to follow a standard operating procedure. The samples contained a known number of microplastics with different morphologies (fiber, fragment, sphere), colors (clear, white, green, blue, red, and orange), polymer types (PE, PS, PVC, and PET), and sizes (ranging from roughly 3-2000 µm), and natural materials (natural hair, fibers, and shells; 100-7000 µm) that could be mistaken for microplastics (i.e., false positives). Particle recovery was poor for the smallest size fraction (3-20 µm). Average recovery (±StDev) for all reported particles >50 µm was 94.5 ± 56.3%. After quality checks, recovery for >50 µm spiked particles was 51.3 ± 21.7%. Recovery varied based on morphology and color, with poorest recovery for fibers and the largest deviations for clear and white particles. Experience mattered; less experienced laboratories tended to report higher concentration and had a higher variance among replicates. Participants identified opportunity for increased accuracy and precision through training, improved color and morphology keys, and method alterations relevant to size fractionation. The resulting data informs future work, constraining and highlighting the value of microscopy for microplastics.

Monitoring microplastics in drinking water: An interlaboratory study to inform effective methods for quantifying and characterizing microplastics.

California Senate Bill 1422 requires the development of State-approved standardized methods for quantifying and characterizing microplastics in drinking water. Accordingly, we led an interlaboratory microplastic method evaluation study, with 22 participating laboratories from six countries, to evaluate the performance of widely used methods: sample extraction via filtering/sieving, optical microscopy, FTIR spectroscopy, and Raman spectroscopy. Three spiked samples of simulated clean water and a laboratory blank were sent to each laboratory with a prescribed standard operating procedure for particle extraction, quantification, and characterization. The samples contained known amounts of microparticles within four size fractions (1-20 µm, 20-212 µm, 212-500 µm, >500 µm), four polymer types (PE, PS, PVC, and PET), and six colors (clear, white, green, blue, red, and orange). They also included false positives (natural hair, fibers, and shells) that may be mistaken for microplastics. Among laboratories, mean particle recovery using stereomicroscopy was 76% ± 10% (SE). For particles in the three largest size fractions, mean recovery was 92% ± 12% SD. On average, laboratory contamination from blank samples was 91 particles (± 141 SD). FTIR and Raman spectroscopy accurately identified microplastics by polymer type for 95% and 91% of particles analyzed, respectively. Per particle, FTIR spectroscopy required the longest time for analysis (12 min ± 9 SD). Participants demonstrated excellent recovery and chemical identification for particles greater than 50 µm in size, with opportunity for increased accuracy and precision through training and further method refinement. This work has informed methods and QA/QC for microplastics monitoring in drinking water in the State of California.

Effects of biofouling on the uptake of perfluorinated alkyl acids by organic-diffusive gradients in thin films passive samplers.

While organic-diffusive gradients in thin films (o-DGT) passive samplers have been used to assess organic contaminants in water, the effects of biofouling on accurate analyte quantification by o-DGT are poorly understood. We evaluated the effects of biofouling on the uptake of six common perfluoroalkyl substances (PFAS) using a previously developed polyacrylamide-WAX (weak anion exchange) o-DGT without a filter membrane. Linear uptake (R2 > 0.91) over 21 days was observed in fouled samplers. The measured sampling rates (Rs) and accumulated masses of PFAS in pre-fouled o-DGT were significantly lower (p < 0.05, 20-39% relative error) than in control-fouled samplers. However, compared to clean o-DGT (no biofouling), the Rs of most PFAS in control-fouled samplers (i.e., those with clean diffusive and binding gels initially) were not affected by biofouling. Under flowing (∼5.8 cm s-1) and static conditions, the measured diffusive boundary layer (DBL) thicknesses for clean o-DGT were 0.016 and 0.082 cm, respectively, whereas the effective in situ biofilm thicknesses for fouled o-DGT were 0.018 and 0.14 cm, respectively. These results suggest that biofilm growth does not have significant effects on target PFAS sampling by o-DGT under typical flowing conditions (≥2 cm s-1). However, rapid surface growth of biofilm on o-DGT deployed in quiescent waters over long periods of time may exacerbate the adverse effects of biofilms, necessitating the estimation of biofilm thickness in situ. This study provides new insights for evaluating the capability of o-DGT samplers when biofilm growth can be significant.

Scrutinizing surficial sediment along a 600-km-long urban coastal zone: Occurrence and risk assessment of fipronil and its three degradates.

Contamination in the coastal zone is closely linked to urbanization and has become a global issue. The coastal aquatic environment is the terminal sink for many chemicals; however, little is known about the occurrence and variation among habitats as well as integrative toxicity for pesticides, i.e., fipronil, and its three major degradates (-desulfinyl, -sulfide, and -sulfone, fiproles hereafter) in sediments in urban coastlines. In the present study, we report results of a random stratified survey for fiproles in surficial sediments in five embayment habitats (strata) along the Southern California Bight (SCB), USA coastline. Fiproles were present in a small areal extent (6.8%) of the SCB embayment, and detected in 14 out of 174 stations with a total concentration of the four analytes ranging from 0.50 to 17.5 µg/kg dry weight. The area-weighted mean concentrations were 3.16 ± 3.37, 0.584 ± 0.558, 0.071 ± 0.103, and 0.005 ± 0.009 µg/kg in brackish estuaries, estuaries, bays, and marinas, respectively, with the results below the detection limits in ports. Fipronil sulfone had the greatest detection frequency (8.05%) and highest mean concentration (3.24 ± 3.36 µg/kg) among the four compounds. A screening-level deterministic risk assessment for invertebrates found that, region-wide, fiproles generally posed an insignificant to low acute risk to the amphipod Eohaustorius estuarius in 7.36% of the SCB embayment area. In addition, high risk to the midge Chironomus dilutus was found in 77.5% of the fiproles-detectable area in the brackish estuary stratum that is a part of the Los Angeles River. Fipronil sulfone was identified as the major contributor of these effects. The results of this study establish a baseline of occurrence and toxicity potential for fiproles in coastal sediments of southern California.

Development and field evaluation of the organic-diffusive gradients in thin-films (o-DGT) passive water sampler for microcystins.

The presence of microcystins (MCs) in waterbodies requires a simple and reliable monitoring technique to characterize better their spatiotemporal distribution and ecological risks. An organic-diffusive gradients in thin films (o-DGT) passive sampler based on polyacrylamide diffusive gel and hydrophilic-lipophilic balance (HLB) binding gel was developed for MCs in water. The mass accumulation of three MCs (MC-LR, -RR, and -YR) was linear over 10 days (R2 ≥ 0.98). Sampling rates (2.68-3.22 mL d-1) and diffusion coefficients (0.90-1.08 × 10-6 cm2 s-1) of three MCs were obtained at 20 °C. Two different passive samplers, o-DGT and the Solid Phase Adsorption Toxin Tracking device (SPATT), were co-deployed to estimate MC levels at three lakes in California, USA. Measured total MC concentrations were up to 10.9 µg L-1, with MC-LR the primary variant at a measured maximum concentration of 2.74 µg L-1. Time-weighted average MC concentrations by o-DGT were lower than grab water samples, probably because grab sampling measures both dissolved and particulate phases (i.e., MCs in cyanobacteria). Passive water samplers by design can only measure dissolved-phase MCs, which are considerably less during the cyanobacteria-laden periods observed. Both o-DGT and grab samples gave comparable results for three MC variants at low levels of MCs, e.g., <0.1 µg L-1. o-DGT showed a higher correlation with grab sampling than SPATT did. This study demonstrates that o-DGT can be effectively used for monitoring and evaluation of dissolved MCs in waters.

Photolysis of the nonsteroidal anti-inflammatory drug sulindac: elucidation of kinetic behaviour and photodegradation pathways in water.

Non-steroidal anti-inflammatory drugs are recognized widely as emerging contaminants. Sulindac has received additional attention as a prodrug in cancer treatment and because of its detection in drinking water and wastewaters. Nevertheless, there is limited knowledge about its kinetic behaviour and fate in the aquatic environment. In this work, the direct photolysis of sulindac, in which photochemical reactions were monitored and phototransformation products identified, was investigated under prolonged periods using UV-A and UV-B radiation and pH conditions (2 and 7) to evaluate the effect of the protonation state and the efficiency of the photolytic process. A novel kinetic mechanism has been proposed in which sulindac exhibits a consecutive reaction pathway, with pseudo-first order kinetics for rapid and reversible Z to E isomerization. Once photoequilibrium was reached, second-order degradation of the isomers in the presence of the new photodegradation products was observed. Photochemical transformation was faster under UV-B irradiation and lower pH, which suggests greater persistence of sulindac at more relevant environmental conditions of UV-A and pH 7. Two novel and major byproducts were identified, corresponding to the oxidative cleavage of the alkene exo to the indene system. The degradation pathway is mainly photoinduced, enhanced by acidic conditions and presumes the double bond as the most reactive site for the parent compound. This research demonstrates an approach for determining kinetics of compounds under challenging conditions, including, absorption from multiple electronic transitions, photoinduced products with unknown extinction coefficients, concentration dependence, photoinduced sensitizing intermediates, and speciation effects. Our work greatly improves our understanding of the degradation process of sulindac and will contribute to exposure assessments and treatment methodologies for this compound in impacted waters.

Crushed recycled glass as a substrate for constructed wetland wastewater treatment: a case study of its potential to facilitate pharmaceutical removal.

The use of recycled glass as a substrate for constructed wetlands was assessed through two studies. The first study examined the dissipation of atenolol, carbamazepine, and sulfamethoxazole in mesocosm-modeled wetlands using glass or limestone gravel as substrates, with or without cattails (Typha spp.). Following pseudo-first-order kinetics, atenolol dissipated the fastest from the water surface of the mesocosms (t1/2~1 day), followed by sulfamethoxazole (t1/2~14 days), and carbamazepine (t1/2~48 days), with no significant differences across treatments. Increased half-lives were observed at greater depth, likely due to light screening. A Monte Carlo sensitivity analysis diagnosed sunlight absorption rates and second-order hydroxyl-mediated indirect photolysis rates to be the main sources of uncertainty in our dissipation rate estimates, compared to our observed rates. The second study examined in situ pharmaceutical removal in tertiary pilot-scale subsurface filters made of crushed recycled glass or sand in a wastewater treatment facility in Manitoba, Canada. Glass and sand showed no significant differences for pharmaceutical removals; atenolol and metoprolol were removed below limits of detection, while carbamazepine and sulfamethoxazole persisted over a retention time of 24 h. Overall, recycled glass performed similarly to traditional substrates for wetland-based wastewater treatment.

Calibration of organic-diffusive gradients in thin films (o-DGT) passive samplers for perfluorinated alkyl acids in water.

The application of the organic-diffusive gradients in thin films (o-DGT) passive sampling technique for the monitoring of per- and polyfluoroalkyl substances (PFAS) in the environment is still limited. Six common PFAS with different chain lengths were evaluated in water by o-DGT. Measured diffusion coefficients (D) in agarose and polyacrylamide diffusive gels ranged from 4.55-8.63 × 10-6 cm2 s-1 and 3.85-7.00 × 10-6 cm2 s-1 at 23 °C, respectively. Experimental sampling rates (Rs) for both agarose- and polyacrylamide-WAX sampler configurations were within 22% relative error of D-based Rs for four of the PFAS. Larger differences for perfluorobutanesulfonic acid (PFBS) and perfluoroundecanoic acid (PFUnDA) ranged from 36% to 56%. In general, in-situ Rs can be predicted using measured D-values for perfluorinated alkyl acids. The mass accumulation of six PFAS in two o-DGT configurations was linear over 21 days (R2 ≥ 0.97). Diffusion and uptake of o-DGT depended on the gel type and specific PFAS. Field demonstrations of o-DGT with WAX and HLB binding gels and polyacrylamide diffusive gels (not prone to biodegradation) found 0.3-19.5 ng L-1 of PFAS in rivers near industrial areas around Guangzhou and Foshan, China, with no apparent differences between the two co-deployed samplers. This study demonstrates that the configurations of o-DGT tested provide a cost-effective monitoring tool for measuring perfluorinated alkyl acids in aquatic systems, in particular the four PFAS for which reasonable correlations were observed.

Evaluating the estrogenicity of an effluent-dominated river in California, USA: Comparisons of in vitro and in vivo bioassays.

Estrogenically active compounds (EACs) in surface waters can disrupt the endocrine system of biota, raising concern for aquatic species. Concentrations of EACs are generally higher in effluent-dominated aquatic systems, such as California's Santa Ana River (SAR). Addressing estrogenicity of effluent-dominated waters is increasingly important due to both increasing urbanization and climate change. To this end, water samples were collected from multiple sites downstream of wastewater treatment plants (WWTPs) and intermittent points along the SAR during 2018-2019 and cell-based bioassays were used to determine estrogen receptor activity. During baseflow conditions, the highest estradiol equivalencies (EEQs) from all SAR water between summer (August and September) and fall (November) sampling events in 2018 were from Yorba Linda (EEQ = 1.36 ± 0.38 ng/L) and Prado (1.14 ± 0.13 ng/L), respectively. Water extracts in January 2019 following a major rainfall generally had higher EEQs with the highest EEQ of 10.0 ± 0.69 ng/L observed at Yorba Linda. During low flow conditions in November 2018, male Japanese medaka (Oryzias latipes) fish were exposed to SAR water to compare to cell bioassay responses and targeted analytical chemistry for 5 steroidal estrogens. Chemical-based EEQ correlations with in vitro EEQs were statistically significant. However, vitellogenin (vtg) mRNA expression in the livers of medaka exposed to SAR water was not significantly different compared to controls. These results indicate that seasonal variation and surface water runoff events influence estrogenic activity in the SAR and may induce estrogenic effects to native fish populations in wastewater-dominated streams in general.

Insitu kinetics of human pharmaceutical conjugates and the impact of transformation, deconjugation, and sorption on persistence in wastewater batch bioreactors.

The fate of selected common pharmaceuticals and four of their major conjugates in wastewater batch bioreactors was evaluated to determine how treatment plant parameters such as addition of air, and the presence of waste activated sludge (WAS) could influence the removal of parent compounds and conjugates. Under a realistic hydraulic residence time (HRT) for each treatment sub-process of approximately 2 h, acetaminophen and its sulfate metabolite were both rapidly degraded (>99%). Propranolol was sulfated and concurrently removed. Deconjugation of N-acetylsulfamethoxazole and sulfamethoxazole-glucuronide contributed to increases of the parent sulfamethoxazole. Thyroxine was resistant to degradation, while thyroxine-glucuronide was rapidly deconjugated (>90% in <2 h). In the absence of WAS, sorption to suspended solids was another major removal mechanism for acetaminophen, propranolol, sulfamethoxazole, and thyroxine. However, with WAS, concentrations associated with suspended solids decreased for all analytes within 24 h. These results indicate that both conjugation and back-transformation are compound-specific and dependent on parameters such as HRT, addition of microbial content, and suspended solids levels. Therefore, conjugation-deconjugation processes may strongly influence the speciation of pharmaceuticals and their fate in wastewater treatment plant effluents.