A state-wide survey in Oregon (USA) of trace metals and organic chemicals in municipal effluent

Embryotoxicity Induced by Triclopyr in Zebrafish (Danio rerio) Early Life Stage

Triclopyr, an auxin-like herbicide that is widely employed for managing weeds in food crops and pastures, has been identified in various environmental settings, particularly aquatic ecosystems. Limited understanding of the environmental fate of this herbicide, its potential repercussions for both the environment and human health, and its insufficient monitoring in diverse environmental compartments has caused it to be recognized as an emerging contaminant of concern. In this study, we have investigated how triclopyr affects zebrafish, considering a new alternative methodology. We focused on the endpoints of developmental toxicity, neurotoxicity, and behavior of zebrafish embryos and larvae. We determined that triclopyr has a 96 h median lethal concentration of 87.46 mg/L (341.01 µM). When we exposed zebrafish embryos to sublethal triclopyr concentrations (0.5, 1, 5, 10, and 50 μM) for up to 144 h, we found that 50 µM triclopyr delayed zebrafish egg hatchability. Yolk sac malabsorption was significant at 0.5, 1, 5, and 10 µM triclopyr. In zebrafish larvae, uninflated swim bladder was significant only at 50 µM triclopyr. Furthermore, zebrafish larvae had altered swimming activity after exposure to 10 µM triclopyr for 144 h. In summary, these comprehensive results indicate that even low triclopyr concentrations can elicit adverse effects during early zebrafish development.

Identification of point and nonpoint emission sources of neonicotinoid pollution in regional surface water

Neonicotinoid insecticides are widely applied in farmland, with high detection rates in soils and surface waters, posing potential risks to biodiversity and human health. As a nonpoint emission, surface runoff is widely regarded as the major source of neonicotinoid pollution in surface waters, but few studies have determined the point source contribution to rivers that may be primarily from wastewater treatment plants (WWTPs). Here, we collected the surface water from eight river basins in Zhejiang Province of China and quantified residual concentrations of eight widely commercialized neonicotinoids. Four of these were detected in all samples, with concentrations of dinotefuran and nitenpyram of 119 ± 166 and 87.6 ± 25.3 ng/L, respectively, representing more than 90 % of the total (282 ± 174 ng/L). Neonicotinoid residues were higher in tributaries due to nearby farmland and more dilution effects in the mainstream, and the residues were higher in lower reaches which can be explained by the water flow direction. Significant spatial differences in neonicotinoid distribution between surface water and agricultural soils result from environmental factors (e.g., water turbidity, precipitation, temperature) impacting migration and transport processes. Neonicotinoid residues in surface water showed a significant positive correlation with total WWTP emissions after adjusting for environmental factors. Conversely, no significant association was observed with cropland density (a nonpoint emission source), indicating that point emission source (contributing 20.6 %) predominantly influenced neonicotinoid residue spatial variation in river basin-scale surface water.

Biogeochemical transformation of mercury driven by microbes involved in anaerobic digestion of municipal wastewater

Anaerobic digestion (AD) with municipal wastewater contained heavy metal mercury (Hg) highly affects the utilization of activated sludge, and poses severe threat to the health of human beings. However, the biogeochemical transformation of Hg during AD remains unclear. Here, we investigated the biogeochemical transformation and environmental characteristics of Hg and the variations of dominant microbes during AD. The results showed that Hg(II) methylation is dominant in the early stage of AD, while methylmercury (MeHg) demethylation dominates in the later stage. Dissolved total Hg (DTHg) in the effluent sludge decreased with time, while THg levels enhanced to varying degrees at the final stage. Sulfate significant inhibits MeHg formation, reduces bioavailability of Hg(II) by microbes and thus inhibits Hg(II) methylation. Microbial community analysis reveals that strains in Methanosarcina and Aminobacterium from the class of Methanomicrobia, rather than Deltaproteobacteria, may be directly related to Hg(II) methylation and MeHg demethylation. Overall, this research provide insights into the biogeochemical transformation of Hg in the anaerobic digestion of municipal wastewater treatment. This work is beneficial for scientific treatment of municipal wastewater and effluent sludge, thus reducing the risk of MeHg to human beings.

Novel and Simple Method for Quantification of 2,4,6-Trichlorophenol with Microbial Conversion to 2,4,6-Trichloroanisole

Contamination with 2,4,6-trichloroanisole (TCA) often causes taste and odor (T&O) problems in drinking water due to its low odor threshold concentration. Microbial O-methylation of the precursor 2,4,6-trichlorophenol (TCP) would be the dominant mechanism for TCA formation. Simple and rapid measurement of TCP in the low concentration range is necessary to control the problems induced by TCA. In this study, the combination of microbial conversion and instrumental analysis was proposed as a method of TCP quantification. Fungi and bacteria were isolated from various water samples and examined for their ability to produce TCA from TCP. As a result, a strain exhibiting quantitative TCA production and a high growth rate was obtained and named Mycolicibacterium sp. CB14. The conversion rate of TCP to TCA by this strain was found to be high and stable (85.9 ± 5.3%), regardless of the applied TCP concentration, although within the range of 0.1-10 µg/L. The limits of detection and quantification for TCP by this proposed method were determined to be 5.2 ng/L and 17.3 ng/L, respectively. By improving the methods, Mycolicibacterium sp. CB14 could be used for the quantification of TCP at very low concentration levels, which is sufficient to manage the T&O problem caused by TCA.

Tracking Targets of Dynamic Super-Enhancers in Vitro to Better Characterize Osteoclastogenesis and to Evaluate the Effect of Diuron on the Maturation of Human Bone Cells

BACKGROUND

Osteoclasts are major actors in the maintenance of bone homeostasis. The full functional maturation of osteoclasts from monocyte lineage cells is essential for the degradation of old/damaged bone matrix. Diuron is one of the most frequently encountered herbicides, particularly in water sources. However, despite a reported delayed ossification in vivo, its impact on bone cells remains largely unknown.

OBJECTIVES

The objectives of this study were to first better characterize osteoclastogenesis by identifying genes that drive the differentiation of CD14+ monocyte progenitors into osteoclasts and to evaluate the toxicity of diuron on osteoblastic and osteoclastic differentiation in vitro.

METHODS

We performed chromatin immunoprecipitation (ChIP) against H3K27ac followed by ChIP-sequencing (ChIP-Seq) and RNA-sequencing (RNA-Seq) at different stages of differentiation of CD14+ monocytes into active osteoclasts. Differentially activated super-enhancers and their potential target genes were identified. Then to evaluate the toxicity of diuron on osteoblasts and osteoclasts, we performed RNA-Seq and functional tests during in vitro osteoblastic and osteoclastic differentiation by exposing cells to different concentrations of diuron.

RESULTS

The combinatorial study of the epigenetic and transcriptional remodeling taking place during differentiation has revealed a very dynamic epigenetic profile that supports the expression of genes vital for osteoclast differentiation and function. In total, we identified 122 genes induced by dynamic super-enhancers at late days. Our data suggest that high concentration of diuron (50μM) affects viability of mesenchymal stem cells (MSCs) in vitro associated with a decrease of bone mineralization. At a lower concentration (1μM), an inhibitory effect was observed in vitro on the number of osteoclasts derived from CD14+ monocytes without affecting cell viability. Among the diuron-affected genes, our analysis suggests a significant enrichment of genes targeted by pro-differentiation super-enhancers, with an odds ratio of 5.12 (ρ=2.59×10-5).

DISCUSSION

Exposure to high concentrations of diuron decreased the viability of MSCs and could therefore affect osteoblastic differentiation and bone mineralization. This pesticide also disrupted osteoclasts maturation by impairing the expression of cell-identity determining genes. Indeed, at sublethal concentrations, differences in the expression of these key genes were mild during the course of in vitro osteoclast differentiation. Taken together our results suggest that high exposure levels of diuron could have an effect on bone homeostasis. https://doi.org/10.1289/EHP11690.

Summary of data from the UKWIR chemical investigations programme and a comparison of data from the past ten years' monitoring of effluent quality

This paper reports summary data from a ten-year programme of investigation into the composition of wastewater treatment works' effluents in the UK. The so-called Chemical Investigations Programme focused on determinands of regulatory importance and involved monitoring of effluents for over seventy trace substances and sanitary determinands at more than 600 UK treatment works sites. The results provide a definitive overview of effluent quality. Although raw data are available, this publication of summary data provides a convenient résumé of the current state of knowledge. An analysis of changes in concentrations over the monitoring period between 2010 and 2020 shows that for several substances (nickel, diethylhexylphthalate, nonylphenol, tributyltin, the brominated diphenyl ethers and triclosan) significant reductions in wastewater concentration have occurred over the period of interest, these are likely to have resulted from a combination of tighter regulatory controls and/or improved wastewater treatment.

Regional extent, environmental relevance, and spatiotemporal variability of neonicotinoid insecticides detected in Florida's ambient flowing waters

The use of imidacloprid and, to a lesser degree, other neonicotinoid insecticides is widespread in FL (and globally). The moderate to high water solubility and environmental persistence of neonicotinoids allows these compounds to readily enter, and be retained in, water resources where they may harm nontarget organisms and impact biological communities and associated trophic structures negatively. To better understand imidacloprid's chronic long-term exposure potential to aquatic invertebrate communities in FL, grab water samples were collected monthly in 2015 at 77 monitoring stations statewide. Fifty-eight stations (75%), representing 24 of the 25 drainage basins sampled, had detectable concentrations of imidacloprid, with concentrations ranging from 2 to 660 nanograms per liter [ng/L]. Imidacloprid basin medians were found to be correlated with two of six land use categories (urban, transportation, agriculture, and three crop classes) examined; urban (rho = 0.43, p-value = 0.03), and orchards and vineyards (rho 0.49, p-value = 0.01). The resampling of 12 select stations, representing eight basins, between August 2019 and July 2020, for the neonicotinoids acetamiprid, clothianidin, dinotefuran, imidacloprid, and thiamethoxam, showed that (1) median values of imidacloprid continued to exceed the US EPA chronic freshwater Invertebrate Aquatic Life Benchmark (IALB) (10 ng/L), (2) imidacloprid concentration was directly correlated with flow measurements, and (3) while median imidacloprid concentration decreased between the two sampling events (48.5 vs. 34.5 ng/L, p-value = 0.01) differences in event 1 and 2 streamflow regimes and disruptions due to the COVID-19 pandemic likely affected this outcome. Clothianidin was the only other neonicotinoid found to have values greater than a US EPA IALB, with detections at three stations exceeding the chronic IALB (50 ng/L). This study highlights the challenges associated with limiting neonicotinoids from entering water resources and identifies means to reduce their entry into and persistence within FL water resources.

Point or non-point source: Toxicity evaluation using m-POCIS and zebrafish embryos in municipal sewage treatment plants and urban waterways

Municipal sewage treatment plants (STPs) have been regarded as an important source of organic contaminants in aquatic environment. To assess the impact of STPs on occurrence and toxicity of STP-associated contaminants in receiving waterways, a novel passive sampler modified from polar organic chemical integrative sampler (m-POCIS) was deployed at the inlet and outlet of a STP and several upstream and downstream sites along a river receiving STP effluent in Guangzhou, China. Eighty-seven contaminants were analyzed in m-POCIS extracts, along with toxicity evaluation using zebrafish embryos. Polycyclic musks were the predominant contaminants in both STP and urban waterways, and antibiotics and current-use pesticides (e.g., neonicotinoids, fiproles) were also ubiquitous. The m-POCIS extracts from downstream sites caused significant deformity in embryos, yet the toxicity could not be explained by the measured contaminants, implying the presence of nontarget stressors. Sewage treatment process substantially reduced embryo deformity, chemical oxygen demand, and contamination levels of some contaminants; however, concentrations of neonicotinoids and fiproles increased after STP treatment, possibly due to the release of chemicals from perturbed sludge. Source identification showed that most of the contaminants found in urban waterways were originated from nonpoint runoff, while cosmetics factories and hospitals were likely point sources for musks and antibiotics, respectively. Although the observed embryo toxicity could not be well explained by target contaminants, the present study showed a promising future of using passive samplers to evaluate chemical occurrence and aquatic toxicity concurrently. Zebrafish embryo toxicity significantly decreased after sewage treatment, but higher toxicity was observed for downstream samples, demonstrating that urban runoff may produce detrimental effects to aquatic life, particularly in rainy season. These results highlight the relevance of monitoring nonpoint source pollution along with boosting municipal sewage treatment infrastructure.

Specific phenotypic, genomic, and fitness evolutionary trajectories toward streptomycin resistance induced by pesticide co-stressors in Escherichia coli

To explore how co-occurring non-antibiotic environmental stressors affect evolutionary trajectories toward antibiotic resistance, we exposed susceptible Escherichia coli K-12 populations to environmentally relevant levels of pesticides and streptomycin for 500 generations. The coexposure substantially changed the phenotypic, genotypic, and fitness evolutionary trajectories, resulting in much stronger streptomycin resistance (>15-fold increase) of the populations. Antibiotic target modification mutations in rpsL and rsmG, which emerged and dominated at late stages of evolution, conferred the strong resistance even with less than 1% abundance, while the off-target mutations in nuoG, nuoL, glnE, and yaiW dominated at early stages only led to mild resistance (2.5-6-fold increase). Moreover, the strongly resistant mutants exhibited lower fitness costs even without the selective pressure and had lower minimal selection concentrations than the mildly resistant ones. Removal of the selective pressure did not reverse the strong resistance of coexposed populations at a later evolutionary stage. The findings suggest higher risks of the selection and propagation of strong antibiotic resistance in environments potentially impacted by antibiotics and pesticides.

Evaluation and comparison of advanced oxidation processes for the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D): a review

Organochlorine pesticides have generated public concern worldwide because of their toxicity to human health and the environment, even at low concentrations, and their persistence, being mostly nonbiodegradable. The use of 2,4-dichlorophenoxyacetic acid (2,4-D) has increased in recent decades, causing severe water contamination. Several treatments have been developed to degrade 2,4-D. This manuscript presents an overview of the physicochemical characteristics, uses, regulations, environmental and human health impacts of 2,4-D, and different advanced oxidation processes (AOPs) to degrade this organic compound, evaluating and comparing operation conditions, efficiencies, and intermediaries. Based on this review, 2,4-D degradation is highly efficient in ozonation (system O₃/plasma, 99.8% in 30 min). Photocatalytic, photo-Fenton, and electrochemical processes have the optimal efficiencies of degradation and mineralization: 97%/79.67% (blue TiO₂ nanotube arrays//UV), 100%/98% (Fe²⁺/H₂O₂/UV), and 100%/84.3% (MI-meso SnO₂), respectively. The ozonation and electrochemical processes show high degradation efficiencies, but energy costs are also high, and photocatalysis is more expensive with a separation treatment used to recover the catalyst in the solution. The Fenton process is a viable economic-environmental option, but degradation efficiencies are often low (50-70%); however, they are increased when solar UV radiation is used (90-100%). AOPs are promising technologies for the degradation of organic pollutants in real wastewater, so evaluating their strengths and weaknesses is expected to help select viable operational conditions and obtain optimal efficiencies.

Emerging investigator series: municipal wastewater as a year-round point source of neonicotinoid insecticides that persist in an effluent-dominated stream

Neonicotinoids in aquatic systems have been predominantly associated with agriculture, but some are increasingly being linked to municipal wastewater. Thus, the aim of this work was to understand the municipal wastewater contribution to neonicotinoids in a representative, characterized effluent-dominated temperate-region stream. Our approach was to quantify the spatiotemporal concentrations of imidacloprid, clothianidin, thiamethoxam, and transformation product imidacloprid urea: 0.1 km upstream, the municipal wastewater effluent, and 0.1 and 5.1 km downstream from the wastewater outfall (collected twice-monthly for one year under baseflow conditions). Quantified results demonstrated that wastewater effluent was a point-source of imidacloprid (consistently) and clothianidin (episodically), where chronic invertebrate exposure benchmarks were exceeded for imidacloprid (36/52 samples; 3/52 > acute exposure benchmark) and clothianidin (8/52 samples). Neonicotinoids persisted downstream where mass loads were not significantly different than those in the effluent. The combined analysis of neonicotinoid effluent concentrations, instream seasonality, and registered uses in Iowa all indicate imidacloprid, and seasonally clothianidin, were driven by wastewater effluent, whereas thiamethoxam and imidacloprid urea were primarily from upstream non-point sources (or potential in-stream transformation for imidacloprid urea). This is the first study to quantify neonicotinoid persistence in an effluent-dominated stream throughout the year-implicating wastewater effluent as a point-source for imidacloprid (year-round) and clothianidin (seasonal). These findings suggest possible overlooked neonicotinoid indoor human exposure routes with subsequent implications for instream ecotoxicological exposure.

Neonicotinoid Insecticides in Surface Water, Groundwater, and Wastewater Across Land-Use Gradients and Potential Effects

Neonicotinoid insecticides cause adverse effects on nontarget organisms, but more information about their occurrence in surface and groundwater is needed across a range of land uses. Sixty-five sites in Minnesota, USA, representing rivers, streams, lakes, groundwater, and treated wastewater, were monitored via collection of 157 water samples to determine variability in spatiotemporal neonicotinoid concentrations. The data were used to assess relations to land use, hydrogeologic condition, and potential effects on aquatic life. Total neonicotinoid concentrations were highest in agricultural watersheds (median = 12 ng/L), followed by urban (2.9 ng/L) and undeveloped watersheds (1.9 ng/L). Clothianidin was most frequently detected in agricultural areas (detection frequency = 100%) and imidacloprid most often in urban waters (detection frequency = 97%). The seasonal trend of neonicotinoid concentrations in rivers, streams, and lakes showed that their highest concentrations coincided with spring planting and elevated streamflow. Consistently low neonicotinoid concentrations were found in shallow groundwater in agricultural regions (<1.2-16 ng/L, median = 1.4 ng/L). Treated municipal wastewater had the highest concentrations across all hydrologic compartments (12-48 ng/L, median = 19 ng/L), but neonicotinoid loads from rivers and streams (median = 4100 mg/d) were greater than in treated wastewater (700 mg/d). No samples exceeded acute aquatic-life benchmarks for individual neonicotinoids, whereas 10% of samples exceeded a chronic benchmark for neonicotinoid mixtures. Although 62% of samples contained 2 or more neonicotinoids, the observed concentrations suggest there were low acute and potential chronic risks to aquatic life. This the first study of its size in Minnesota and is critical to better understanding the drivers of wide-scale environmental contamination by neonicotinoids where urban, agricultural, and undeveloped lands are present. Environ Toxicol Chem 2021;40:1017-1033. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Total mercury and methylmercury migration and transformation in an A2/O wastewater treatment plant

Municipal wastewater treatment plants (MWTPs) serve an essential role in reducing mercury (Hg) pollution. However, few studies quantified the transport and transformation of Hg through MWTPs, particularly plants based on the anaerobic-anoxic-aerobic (A²/O) process. Here, we present a mass balance for total mercury (THg) and total methylmercury (TMeHg) at the plant, and investigate the influence of pH, temperature, and dissolved oxygen on the occurrence and fate of methylmercury (MeHg) in the system. The concentrations of the THg and TMeHg in the raw sewage were 40.3 ± 26.6 ng/L (4.3 ± 2.7 g/day) and 1.9 ± 0.6 ng/L (193 ± 58 mg/day), respectively. Their concentrations in the plant's effluent water were 7.4 ± 1.5 ng/L (0.74 ± 0.2 g/day) and 0.04 ± 0.01 ng/L (3.9 ± 1.0 mg/day), corresponding to decreases of ~82% for THg and ~98% for TMeHg. Within the plant, only ~10% of the THg was removed with primary sedimentation, as Hg in the raw sewage was predominately in dissolved form. In contrast, a significant portion of TMeHg (~43%) was associated with incoming particulate matter. Much of the remaining Hg was removed in subsequent A²/O process and secondary clarifiers, with a ~78% of the THg entering the plant transferring to the dewatered sludge (concentration 1.05 ± 0.28 μg/g; 3.2 ± 0.8 g/day). These same steps decreased TMeHg in the water by ~95%, with <10% of that reduction being TMeHg transferred to the sludge (concentration 2.1 ± 1.1 ng/g; 6.2 ± 3.3 mg/day), suggesting >90% TMeHg degradation. In addition, the most important factor that impacted the variation of TMeHg concentrations was pH, then was temperature. Dissolved oxygen showed no relationship with TMeHg and DMeHg. Overall, this study demonstrates that A²/O MWTPs effectively remove MeHg from wastewater, however, sludge remains an important potential source of Hg to the environment.

DEET occurrence in wastewaters: Seasonal, spatial and diurnal variability - mismatches between consumption data and environmental detection

DEET (N, N-diethyl-m-toluamide) is one of the most frequently detected trace organic contaminants (TOrC) in wastewaters and is used primarily as an insect repellent. It was introduced for use in the general public in 1957. It is ubiquitously present in the environment and DEET concentrations are usually among the highest reported for TOrCs. Due to recent concerns about possible analytical interferences in detection methods being reported, this study focused on possible artifacts caused by seasonal, spatial, and diurnal variations in wastewater influent concentration of DEET. We also compared usage data to observed wastewater concentrations of seven wastewater treatment plants (WWTPs) in four different regions in the US monitored from November 2014 to November 2016. Consumption data obtained reveal patterns of consumption according to climatic regions and season. During the summer DEET usage accounts for almost 60% of all usage during a year, while during the winter months DEET usage accounts for <5%. Concerning spatial distribution, while per capita consumption of DEET in Florida is three times higher than the one observed in Arizona (44 g vs 14 g), DEET concentrations in wastewater tend to be much higher in Arizona. Regardless of WWTPs or monitoring period, concentrations as high as 15,200 ng/L were observed during the month of October 2016. While DEET has a diurnal variation in the wastewater influent, with a maximum at 18:00, the diurnal variability is not enough to explain the great discrepancies between consumption of DEET versus occurrence in wastewaters. Although LC-MS/MS analysis of isobaric and structural mimics suggests some possibility of interferences, NMR spectroscopy analysis of environmental samples does not support the presence of such mimics in real samples.

The removal of pharmaceuticals during wastewater treatment: Can it be predicted accurately?

The presence of active pharmaceutical ingredients (APIs) in the environment is of growing concern and effluents from wastewater treatment works (WwTWs) are one of the major sources. This research combines the outputs of a multimillion pound UK program of work to evaluate the fate of APIs in the wastewater treatment process. A combination of analysis of measured data and modelling has been applied to 18 APIs, representing a wide range of medicinal application and physico-chemical characteristics. Some isomers (for atorvastatin) and metabolites (for sertraline, carbamazepine and erythromycin) were also included. High variability was observed between removal rates for individual APIs between WwTW, which after statistical analysis could not be explained by the nominal WwTW process (e.g. activated sludge or trickling filter). Nor was there a clear relationship between API removal and physico-chemical parameters such as pKa, charge or log Kow. A publically available sewage process model, SimpleTreat 4.0 which has been rigorously validated and is now being used for exposure assessment with REACH legislation for organic chemicals and within the Biocidal Products Regulation by the European Medicines Agency for APIs, was used to estimate removal rates with which to compare with measured data. SimpleTreat provided estimates of removal rates within ±30% of observed values for the majority of the APIs measured, with the use of readily available WwTW specific parameters such as flow, total suspended solids and BOD data. The data and correlations provided in this study provide support for any future considerations regarding the management of API discharge to the aquatic environment.

Mercury in Municipal Sewage and Sewage Sludge

Wide occurrence of mercury species, including the highly toxic and readily bioaccumulative methylmercury (MeHg), in municipal sewage (MS) and sewage sludge (SS) has been evidenced in recent studies. Considering that vast amounts of MS and SS are produced globally each year and the majority of MS is discharged into aqueous environments, i.e., the main sites for MeHg bioaccumulation, special attention should be paid on the source and environmental behaviors of sewage-borne and sludge-borne mercury species. This review aims to summarize the findings on the occurrence of mercury species in MS and SS, their transport and transformation in MS treatment plants, as well as their fate and environmental implications.

Evidence-based logic chains demonstrate multiple impacts of trace metals on ecosystem services

Trace metals can have far-reaching ecosystem impacts. In this study, we develop consistent and evidence-based logic chains to demonstrate the wider effects of trace metal contamination on a suite of ecosystem services. They demonstrate knock-on effects from an initial receptor that is sensitive to metal toxicity, along a cascade of impact, to final ecosystem services via alterations to multiple ecosystem processes. We developed logic chains to highlight two aspects of metal toxicity: for impacts of copper pollution in soil ecosystems, and for impacts of mercury in freshwaters. Each link of the chains is supported by published evidence, with an indication of the strength of the supporting science. Copper pollution to soils (134 unique chains) showed a complex network of pathways originating from direct effects on a range of invertebrate and microbial taxa and plants. In contrast, mercury pollution on freshwaters (63 unique chains) shows pathways that broadly follow the food web of this habitat, reflecting the potential for mercury bioaccumulation. Despite different pathways, there is considerable overlap in the final ecosystem services impacted by both of these metals and in both ecosystems. These included reduced human-use impacts (food, fishing), reduced human non-use impacts (amenity value) and positive or negative alterations to climate regulation (impacts on carbon sequestration). Other final ecosystem goods impacted include reduced crop production, animal production, flood regulation, drinking water quality and soil purification. Taking an ecosystem services approach demonstrates that consideration of only the direct effects of metal contamination of soils and water will considerably underestimate the total impacts of these pollutants. Construction of logic chains, evidenced by published literature, allows a robust assessment of potential impacts indicating primary, secondary and tertiary effects.

Anaerobic degradation of 2,4-dichlorophenoxyacetic acid by Thauera sp. DKT

Thauera sp. strain DKT isolated from sediment utilized 2,4-dichlorophenoxyacetic acid (2,4D) and its relative compounds as sole carbon and energy sources under anaerobic conditions and used nitrate as an electron acceptor. The determination of 2,4D utilization at different concentrations showed that the utilization curve fitted well with the Edward model with the maximum degradation rate as 0.017 ± 0.002 mM/day. The supplementation of cosubstrates (glucose, acetate, sucrose, humate and succinate) increased the degradation rates of all tested chemical substrates in both liquid and sediment slurry media. Thauera sp. strain DKT transformed 2,4D to 2,4-dichlorophenol (2,4DCP) through reductive side-chain removal then dechlorinated 2,4DCP to 2-chlorophenol (2CP), 4-chlorophenol (4CP) and phenol before complete degradation. The relative degradation rates by the isolate in liquid media were: phenol > 2,4DCP > 2CP > 4CP > 2,4D ≈ 3CP. DKT augmentation in sediment slurry enhanced the degradation rates of 2,4D and chlorophenols. The anaerobic degradation rates in the slurry were significantly slower compared to the rates in liquid media.

Active pharmaceutical ingredients entering the aquatic environment from wastewater treatment works: A cause for concern?

This work reports on the variation in wastewater treatment works (WwTW) influent concentrations of a wide variety of active pharmaceutical ingredients (APIs), their removal efficiency, effluent concentrations and potential risks to the aquatic environment. The research is based on data generated from two large UK-wide WwTW monitoring programmes. Taking account of removal of parent compound from the aqueous phase during treatment in combination with estimates of dilution available it is possible to prioritise the APIs of greatest risk of exceeding estimates of predicted no effect concentrations (PNEC) in receiving waters for all WwTW in the UK. The majority of substances studied were removed to a high degree, although with significant variation, both within and between WwTW. Poorer removal (between influent and effluent) was observed for ethinyloestradiol, diclofenac, propranolol, the macrolide antibiotics, fluoxetine, tamoxifen and carbamazepine. All except the last two of these substances were present in effluents at concentrations higher than their respective estimated PNEC (based on measurement of effluents from 45 WwTW on 20 occasions). Based on available dilution data as many as 890 WwTW in the UK (approximately 13% of all WwTW) may cause exceedances of estimated riverine PNECs after mixing of their effluents with receiving waters. The overall degree of risk is driven by the toxicity value selected, which in itself is controlled by the availability of reliable and relevant ecotoxicological data and consequently the safety factors applied. The dataset and discussion, provides information to assist in the future management of these types of chemicals.

Passage of fiproles and imidacloprid from urban pest control uses through wastewater treatment plants in northern California, USA

Urban pest control insecticides-specifically fipronil and its 4 major degradates (fipronil sulfone, sulfide, desulfinyl, and amide), as well as imidacloprid-were monitored during drought conditions in 8 San Francisco Bay (San Francisco, CA, USA) wastewater treatment plants (WWTPs). In influent and effluent, ubiquitous detections were obtained in units of ng/L for fipronil (13-88 ng/L), fipronil sulfone (1-28 ng/L), fipronil sulfide (1-5 ng/L), and imidacloprid (58-306 ng/L). Partitioning was also investigated; in influent, 100% of imidacloprid and 62 ± 9% of total fiproles (fipronil and degradates) were present in the dissolved state, with the balance being bound to filter-removable particulates. Targeted insecticides persisted during wastewater treatment, regardless of treatment technology utilized (imidacloprid: 93 ± 17%; total fiproles: 65 ± 11% remaining), with partitioning into sludge (3.7-151.1 μg/kg dry wt as fipronil) accounting for minor losses of total fiproles entering WWTPs. The load of total fiproles was fairly consistent across the facilities but fiprole speciation varied. This first regional study on fiprole and imidacloprid occurrences in raw and treated California sewage revealed ubiquity and marked persistence to conventional treatment of both phenylpyrazole and neonicotinoid compounds. Flea and tick control agents for pets are identified as potential sources of pesticides in sewage meriting further investigation and inclusion in chemical-specific risk assessments. Environ Toxicol Chem 2017;36:1473-1482. © 2016 SETAC.

Critical assessment of the ubiquitous occurrence and fate of the insect repellent N,N-diethyl-m-toluamide in water

The insect repellent diethyltoluamide (DEET) is among the most frequently detected organic chemical contaminants in water across a wide range of geographies from around the world. These observations are raising critical questions and increasing concerns regarding potential environmental relevance, particularly when the emergence of severe neurological conditions attributed to the Zika virus has increased the use of insect repellents. After dermal application, DEET is washed from the skin when bathing and enters the municipal sewer system before discharge into the environment. Mainly measured by gas chromatography or liquid chromatography coupled to mass spectrometry (GC-MS or LC-MS), more than 200 peer-reviewed publications have already reported concentrations of DEET ranging ng/L to mg/L in several water matrices from North America, Europe, Asia, Oceania, and more recently Africa and South America. While conventional wastewater treatment technology has limited capacity of removal, advanced technologies are capable of better attenuation and could lower the environmental discharge of organic contaminants, including DEET. For instance, adsorption on activated carbon, desalinating membrane processes (nanofiltration and reverse osmosis), ozonation, and advanced oxidation processes can achieve 50% to essentially 100% DEET attenuation. Despite the abundant literature on the topic, the ubiquity of DEET in the environment still raises questions due to the apparent lack of obvious spatio-temporal trends in concentrations measured in surface water, which does not fit the expected usage pattern of insect repellents. Moreover, two recent studies showed discrepancies between the concentrations obtained by GC-MS and LC-MS analyses. While the occurrence of DEET in the environment is well established, the concentrations reported should be interpreted cautiously, considering the disparities in methodologies applied and occurrence patterns observed. Therefore, this manuscript provides a critical overview of the origin of DEET in the environment, the relevant analytical methods, the occurrence reported in peer-reviewed literature, and the attenuation efficacy of water treatment processes.

Spatial and temporal variability of contaminants within estuarine sediments and native Olympia oysters: A contrast between a developed and an undeveloped estuary

Chemical contaminants can be introduced into estuarine and marine ecosystems from a variety of sources including wastewater, agriculture and forestry practices, point and non-point discharges, runoff from industrial, municipal, and urban lands, accidental spills, and atmospheric deposition. The diversity of potential sources contributes to the likelihood of contaminated marine waters and sediments and increases the probability of uptake by marine organisms. Despite widespread recognition of direct and indirect pathways for contaminant deposition and organismal exposure in coastal systems, spatial and temporal variability in contaminant composition, deposition, and uptake patterns are still poorly known. We investigated these patterns for a suite of persistent legacy contaminants including polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) and chemicals of emerging concern including pharmaceuticals within two Oregon coastal estuaries (Coos and Netarts Bays). In the more urbanized Coos Bay, native Olympia oyster (Ostrea lurida) tissue had approximately twice the number of PCB congeners at over seven times the total concentration, yet fewer PBDEs at one-tenth the concentration as compared to the more rural Netarts Bay. Different pharmaceutical suites were detected during each sampling season. Variability in contaminant types and concentrations across seasons and between species and media (organisms versus sediment) indicates the limitation of using indicator species and/or sampling annually to determine contaminant loads at a site or for specific species. The results indicate the prevalence of legacy contaminants and CECs in relatively undeveloped coastal environments highlighting the need to improve policy and management actions to reduce contaminant releases into estuarine and marine waters and to deal with legacy compounds that remain long after prohibition of use. Our results point to the need for better understanding of the ecological and human health risks of exposure to the diverse cocktail of pollutants and harmful compounds that will continue to leach from estuarine sediments over time.

Year-Round Monitoring of Contaminants in Neal and Rogers Creeks, Hood River Basin, Oregon, 2011-12, and Assessment of Risks to Salmonids

Pesticide presence in streams is a potential threat to Endangered Species Act listed salmonids in the Hood River basin, Oregon, a primarily forested and agricultural basin. Two types of passive samplers, polar organic chemical integrative samplers (POCIS) and semipermeable membrane devices (SPMDs), were simultaneously deployed at four sites in the basin during Mar. 2011-Mar. 2012 to measure the presence of pesticides, polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs). The year-round use of passive samplers is a novel approach and offers several new insights. Currently used pesticides and legacy contaminants, including many chlorinated pesticides and PBDEs, were present throughout the year in the basin's streams. PCBs were not detected. Time-weighted average water concentrations for the 2-month deployment periods were estimated from concentrations of chemicals measured in the passive samplers. Currently used pesticide concentrations peaked during spring and were detected beyond their seasons of expected use. Summed concentrations of legacy contaminants in Neal Creek were highest during July-Sept., the period with the lowest streamflows. Endosulfan was the only pesticide detected in passive samplers at concentrations exceeding Oregon or U.S. Environmental Protection Agency water-quality thresholds. A Sensitive Pesticide Toxicity Index (SPTI) was used to estimate the relative acute potential toxicity among sample mixtures. The acute potential toxicity of the detected mixtures was likely greater for invertebrates than for fish and for all samples in Neal Creek compared to Rogers Creek, but the indices appear to be low overall (<0.1). Endosulfans and pyrethroid insecticides were the largest contributors to the SPTIs for both sites. SPTIs of some discrete (grab) samples from the basin that were used for comparison exceeded 0.1 when some insecticides (azinphos methyl, chlorpyrifos, malathion) were detected at concentrations near or exceeding acute water-quality thresholds. Early life stages and adults of several sensitive fish species, including salmonids, are present in surface waters of the basin throughout the year, including during periods of peak estimated potential toxicity. Based on these data, direct toxicity to salmonids from in-stream pesticide exposure is unlikely, but indirect impacts (reduced fitness due to cumulative exposures or negative impacts to invertebrate prey populations) are unknown.

Mass Balance Assessment for Six Neonicotinoid Insecticides During Conventional Wastewater and Wetland Treatment: Nationwide Reconnaissance in United States Wastewater

Occurrence and removal of six high-production high-volume neonicotinoids was investigated in 13 conventional wastewater treatment plants (WWTPs) and one engineered wetland. Flow-weighted daily composites were analyzed by isotope dilution liquid chromatography tandem mass spectrometry, revealing the occurrence of imidacloprid, acetamiprid, and clothianidin at ng/L concentrations in WWTP influent (60.5 ± 40.0; 2.9 ± 1.9; 149.7 ± 289.5, respectively) and effluent (58.5 ± 29.1; 2.3 ± 1.4; 70.2 ± 121.8, respectively). A mass balance showed insignificant removal of imidacloprid (p = 0.09, CI = 95%) and limited removal of the sum of acetamiprid and its degradate, acetamiprid-N-desmethyl (18 ± 4%, p = 0.01, CI = 95%). Clothianidin was found only intermittently, whereas thiamethoxam, thiacloprid, and dinotefuran were never detected. In the wetland, no removal of imidacloprid or acetamiprid was observed. Extrapolation of data from 13 WWTPs to the nation as a whole suggests annual discharges on the order of 1000-3400 kg/y of imidacloprid contained in treated effluent to surface waters nationwide. This first mass balance and first United States nationwide wastewater reconnaissance identified imidacloprid, acetamiprid, and clothianidin as recalcitrant sewage constituents that persist through wastewater treatment to enter water bodies at significant loadings, potentially harmful to sensitive aquatic invertebrates.

The fate of mercury in municipal wastewater treatment plants in China: Significance and implications for environmental cycling

Municipal wastewater treatment plants (WWTPs) play an important role in controlling pollutant discharges to surface waters. Previous studies suggested that the removal of mercury (Hg) by WWTPs was strongly correlated with solid removal. However, conclusions regarding possible transformations of Hg species within WWTPs were not consistent across those studies. We characterized total Hg (THg) and methylmercury (MeHg) concentrations and loads in a WWTP located in Jiaozuo, China, to further understand Hg fate and transformations in WWTPs. THg and MeHg were primarily associated with wastewater solids, and removal of both were greater than 90%; concentrations in the sewage were (2.0±2.7)×10(3)ng/L and 7.5±5.8ng/L, respectively. A mass balance calculation revealed that 80% of the THg input to the WWTP ended up in the sewage sludge (SS), while more than 70% of the influent MeHg mass was degraded, indicating WWTPs are an important sink for sewage-borne Hg. THg and MeHg concentrations in SS were (3.9±1.4)×10(3)ng/g and 6.3±2.3ng/g, respectively, suggesting SS could be a significant source of THg and MeHg to the environment if not handled properly. The significance of sewage and SS in the biogeochemical cycling of THg and MeHg in China is discussed.

Spoilt for choice: A critical review on the chemical and biological assessment of current wastewater treatment technologies

The knowledge we have gained in recent years on the presence and effects of compounds discharged by wastewater treatment plants (WWTPs) brings us to a point where we must question the appropriateness of current water quality evaluation methodologies. An increasing number of anthropogenic chemicals is detected in treated wastewater and there is increasing evidence of adverse environmental effects related to WWTP discharges. It has thus become clear that new strategies are needed to assess overall quality of conventional and advanced treated wastewaters. There is an urgent need for multidisciplinary approaches combining expertise from engineering, analytical and environmental chemistry, (eco)toxicology, and microbiology. This review summarizes the current approaches used to assess treated wastewater quality from the chemical and ecotoxicological perspective. Discussed chemical approaches include target, non-target and suspect analysis, sum parameters, identification and monitoring of transformation products, computational modeling as well as effect directed analysis and toxicity identification evaluation. The discussed ecotoxicological methodologies encompass in vitro testing (cytotoxicity, genotoxicity, mutagenicity, endocrine disruption, adaptive stress response activation, toxicogenomics) and in vivo tests (single and multi species, biomonitoring). We critically discuss the benefits and limitations of the different methodologies reviewed. Additionally, we provide an overview of the current state of research regarding the chemical and ecotoxicological evaluation of conventional as well as the most widely used advanced wastewater treatment technologies, i.e., ozonation, advanced oxidation processes, chlorination, activated carbon, and membrane filtration. In particular, possible directions for future research activities in this area are provided.

Temporal and spatial contamination of polybrominated diphenyl ethers (PBDEs) in wastewater treatment plants in Hong Kong

Polybrominated diphenyl ethers (PBDEs) are widely used as flame retardants which cause adverse effects to human health and environments. Wastewater treatment plants (WWTPs) receive PBDEs from various discharges but also release them back to the environment via treated effluent and sludge, depending on the removal efficiency of WWTPs. This study investigated the contamination of PBDEs in primary influent, final effluent and dewatered sludge in four WWTPs in Hong Kong from October 2011 to January 2013. Results showed that the concentrations and composition profiles of eight PBDE congeners (BDE-28, －47, －99, －100, －153, －154,－183 and －209) differed among WWTPs and fluctuated during the study period. Higher concentrations of PBDEs were detected in the influent and dewatered sludge from the two WWTPs receiving both domestic and industrial wastewaters than the two serve mainly residential and commercial districts. However, the PBDE concentrations in the effluent were comparable among WWTPs. The concentrations of Σ8PBDEs (total of eight congeners) in the influent of all WWTPs ranged from 1 to 254 ng L(-1) but decreased to 12-27 ng L(-1) in effluent, with removal efficiency ranged from 20 to 53%. High concentrations of PBDEs, ranging from 9 to 307 ng g(-1) dry weights, were detected in dewatered sludge. The predominated congeners in influent were BDE-47 and -209 but shifted to BDE-47 and －99 in effluent and BDE-209 in dewatered sludge. Every day, it is estimated 0.66-73 g PBDEs entered the four WWTPs, while 0.38-38 g and 0.17-17 g PBDEs were discharged to the surrounding waters via effluent and disposed to landfill sites in sludge form, respectively. These results indicated that the four WWTPs in Hong Kong were not designed for effectively removal of PBDEs, 52-80% of the incoming PBDEs were still remained in effluent and 21-45% was precipitated in sludge, both outputs became significant contamination sources.

Stress-related gene expression changes in rainbow trout hepatocytes exposed to various municipal wastewater treatment influents and effluents

The present study sought to examine the performance of six different wastewater treatment processes from 12 wastewater treatment plants using a toxicogenomic approach in rainbow trout hepatocytes. Freshly prepared rainbow trout hepatocytes were exposed to increasing concentrations of influent (untreated wastewaters) and effluent (C(18)) extracts for 48 h at 15 °C. A test battery of eight genes was selected to track changes in xenobiotic biotransformation, estrogenicity, heavy metal detoxification, and oxidative stress. The wastewaters were processed by six different treatment systems: facultative and aerated lagoons, activated sludge, biological aerated filter, biological nutrient removal, chemically assisted primary treated, and trickling filter/solids contact. Based on the chemical characteristics of the effluents, the treatment plants were generally effective in removing total suspended solids and chemical oxygen demand, but less so for ammonia and alkalinity. The 12 influents differed markedly with each other, which makes the comparison among treatment processes difficult. For the influents, both population size and flow rate influenced the increase in the following mRNA levels in exposed hepatocytes: metallothionein (MT), cytochrome P4503A4 (CYP3A4), and vitellogenin (VTG). Gene expression of glutathione S-transferase (GST) and the estrogen receptor (ER), were influenced only by population size in exposed cells to the influent extracts. The remaining genes-superoxide dismutase (SOD) and multidrug resistance transporter (MDR)-were not influenced by either population size or flow rate in exposed cells. It is noteworthy that the changes in MT, ER, and VTG in cells exposed to the effluents were significantly affected by the influents across the 12 cities examined. However, SOD, CYP1A1, CYP3A4, GST, and MDR gene expression were the least influenced by the incoming influents. The data also suggest that wastewater treatments involving biological or aeration processes had the best performance. We found that the effects of municipal effluents on gene expression depended on the population size, the initial properties of the incoming influent, and the wastewater treatment method applied. Considering that the long-term goals of wastewater treatment is to produce clean effluents for the aquatic biota and independent of the incoming influent, more research is needed in developing treatment processes to better protect aquatic life from anthropogenic contamination.

Two generations of fall armyworm (Lepidoptera: Noctuidae) contamination by di-n-butylphthalate

The effects of di-n-butylphthalate (DnBP) were investigated with respect to bioaccumulation and whether these effects occurred over a second generation in the fall armyworm Spodoptera frugiperda (J.E. Smith, 1797). The concentrations of DnBP in males and females of the second generation were higher than those in first one. However, frequency of mortality of exposed individuals in the second generation was approximately 57% less but the reduction in size and weight was more pronounced than in the first generation.

The significance of hazardous chemicals in wastewater treatment works effluents

The advent of increasingly stringent and wider ranging European Union legislation relating to water and the environment has required regulators to assess compliance risk and to respond by formulating appropriate pollution control measures. To support this process the UK Water Industry has completed a national Chemicals Investigation Programme (CIP), to monitor over 160 wastewater treatment works (WwTWs) for 70 determinands. Final effluent concentrations of zinc, polynuclear aromatic hydrocarbons (fluoranthene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(g,h,i)perylene and indeno(1,2,3-cd)pyrene), "penta" congeners (BDEs) 47 and 99, tributyltin, triclosan, erythromycin, oxytetracycline, ibuprofen, propranolol, fluoxetine, diclofenac, 17β-estradiol and 17α-ethinyl estradiol exceeded existing or proposed Environmental Quality Standards (EQSs) in over 50% of WwTWs. Dilution by receiving water might ensure compliance with EQSs for these chemicals, apart from the BDEs. However, in some cases there will be insufficient dilution to ensure compliance and additional management options may be required.