Isotopic-based evidence for reduced benthic contributions to fish after a whole-lake addition of nanosilver

Silver nanoparticles (AgNPs) are added as antibacterial and anti-odor agents to a wide range of textiles, with high potential for release into aquatic environments via domestic wastewater. Previous work demonstrating the negative impacts of AgNP exposure on periphyton production suggests benthic primary production could be reduced in aquatic ecosystems impacted by AgNP discharge. To evaluate the potential for AgNPs to alter benthic-pelagic coupling in aquatic ecosystems, tissue-stable isotope ratios of carbon and nitrogen from northern pike (Esox lucius) and yellow perch (Perca flavescens) were measured before, during, and after the addition of AgNPs to a whole-lake ecosystem, and compared to those collected from a nearby reference lake. A shift in carbon isotope ratios toward more negative values was observed in both P. flavescens and E. lucius collected from the lake where AgNPs were added, with no shift in similar magnitude observed in E. lucius from the reference lake. Consequently, Bayesian estimates of benthic energy consumed decreased by 32% for P. flavescens and by 40% for E. lucius collected after AgNP additions relative to pre-addition estimates, greater in magnitude or opposite in direction of trends observed in our reference lake. Analyses suggest no changes in fish nitrogen isotope ratios related to AgNP additions. We hypothesize that the observed reduction in littoral energy use of fish reported here is a response to AgNP settling in littoral benthic habitats-the main habitat in lakes supporting periphyton-as AgNP has been shown elsewhere to significantly reduce the rates of periphyton production. Further, our study highlights the need to broaden the scope of risk assessments for AgNPs and other emerging contaminants prone to settling to consider habitat-specific impacts on resource utilization by organisms after their release into aquatic ecosystems.

Consumption and activity decline in Northern Pike (Esox lucius) during and after silver nanoparticle addition to a lake

Silver nanoparticles (AgNPs) are antimicrobial additives in many consumer products with high potential for release into aquatic ecosystems. Though AgNPs have been shown to have negative impacts on fish in laboratory experiments, these effects are rarely observed at ecologically relevant concentrations or in situ in field settings. To evaluate ecosystem-level effects of this contaminant, AgNPs were added to a lake at the IISD Experimental Lakes Area (IISD-ELA) during 2014 and 2015. Mean total silver (TAg) concentrations in the water column were 4 µg L^-1 during additions. The growth of Northern Pike (Esox lucius) declined, and their primary prey, Yellow Perch (Perca flavescens) became less abundant after AgNP exposure. Here, we used a combined contaminant-bioenergetics modeling approach to show that individual activity and both individual and population-level consumption of Northern Pike declined significantly in the lake dosed with AgNPs, which, combined with other evidence, suggests that observed declines in body size were likely a result of indirect effects (i.e., reduced prey availability). Further, we found the contaminant-bioenergetics approach was sensitive to modelled elimination rates of mercury, overestimating consumption and activity by 43% and 55%, respectively, when using the mercury elimination rate commonly used in these models versus field-derived estimates for this species. This study contributes to the growing evidence of potentially long-term negative impacts on fish from chronic exposure to environmentally relevant concentrations of AgNPs in a natural setting.

Compounds of wastewater origin in remote upland lakes in Ireland

It is well established that persistent organic pollutants are transported long distances in the atmosphere and deposited into aquatic and terrestrial ecosystems in remote areas, including high altitude lakes. The objective of this research was to evaluate whether compounds of wastewater origin were present in four remote upland headwater lakes in Ireland that primarily receive loadings from atmospheric deposition. Using Polar Organic Chemical Integrative Samplers (POCIS) deployed in the lakes for 60 to 68 days, seven compounds were detected at levels that could be quantified but 25 of the target compounds were not detected. The detected compounds included the cannabinoid metabolite, tetrahydrocannabinol carboxylate (THC-COOH), codeine, acetaminophen (paracetamol), ibuprofen, and the artificial sweeteners, sucralose, and saccharin, which were all present at concentrations estimated to be < 125 ng/L. Caffeine was also present in the lakes at estimated concentrations between 213 and 1320 ng/L. Cocaine and tramadol were detected in POCIS deployed in some of the lakes, but at levels below the limits of quantitation. The highest concentrations of the target analytes were detected in two lakes located in the eastern part of Ireland. These data are consistent with regional atmospheric transport of these compounds originating from wastewater treatment plants in Ireland. However, contaminants from wastewater treatment plants in the United Kingdom may also be a source in these upland lakes that are located far from emissions of urban pollution.

Freshwater mussels in an impacted watershed: Influences of pollution from point and non-point sources

The Grand River watershed in a densely populated region of Ontario supports one of the richest assemblages of freshwater mussels in Canada. However, water quality in this watershed is influenced by urban development, agriculture, and industry. Mussel populations and water chemistry in the lower Grand River and the Boston Creek tributary were evaluated to determine whether point sources of pollution such as discharges of domestic wastewater and industrial effluent, and non-point sources of pollution are affecting mussel distribution and population structure. Semi-quantitative population surveys conducted at 9 study sites identified 20 mussel species, including 3 Species at Risk. Mussel abundance (34-160 mussels/search hour) and species richness indicated that mussel populations in the lower Grand River watershed are continuing to recover from historical lows reported in the 1970s. However, changes in populations at some sites were consistent with altered water chemistry. Most notable was that the three most abundant mussel species in the Boston Creek tributary downstream of a gypsum plant discharge were significantly smaller in length than those upstream of this site. The water chemistry in this habitat was characterized by elevated conductivity (∼2000 μS/cm) and calcium (∼500 mg/L), as well as concentrations of sulfate (∼1000 mg/L) that can be toxic to freshwater mussels. In the Grand River downstream of the confluence with Boston Creek, there tended to be (p > 0.05) fewer mussels (mean 34 ± 20/search h) compared to upstream (mean 67 ± 15/search h) and this corresponded to altered water chemistry, including elevated sulfate (239 mg/L) downstream of the confluence relative to upstream (58 mg/L). These data indicate that chronic exposures to high levels of major ions is likely driving changes to mussel population structure. In addition, the discharges of wash water from a gypsum plant may be impacting sensitive biota in the main stem Grand River well beyond the immediate tributary receiving environment.

Whole-lake nanosilver additions reduce northern pike (Esox lucius) growth

Nanosilver (AgNP) is an anti-microbial agent widely used in consumer products, with significant potential for these nanoparticles to be released into aquatic environments. Laboratory studies involving short-term exposures of fish to AgNP show a range of toxicological effects, but these studies do not address potential responses in long-lived organisms resulting from chronic exposures. A collaborative study involving additions of AgNP to environmentally relevant concentrations over two field seasons took place at the IISD-Experimental Lakes Area, providing an opportunity to study the impacts of chronic exposures to long-lived fish species. In the present study, we evaluated the abundance and growth of an apex predator, Northern Pike (Esox lucius), collected from Lake 222 before, during and after the AgNP dosing period and compared results to those from a nearby unmanipulated lake (Lake 239). While the abundance of Northern Pike from Lake 222 during the study period was essentially stable, per capita availability of their primary prey species, Yellow Perch (Perca flavescens) declined by over 30%. Northern Pike fork length- and weight-at-age (indices of growth rate) declined following AgNP additions, most notably in age 4 and 5 fish. No similar changes in prey availability or growth were observed in Northern Pike from the reference lake. Body condition did not change in Northern Pike collected from either Lake 222 or Lake 239. Our results indicate that declines in the growth of Northern Pike chronically exposed to AgNP likely resulted from reduced prey availability but direct sublethal effects from AgNP exposure could also have been a factor. The persistence of reduced growth in Northern Pike two years after the cessation of AgNP additions highlight the potential legacy impacts of this contaminant once released into aquatic ecosystems.

The occurrence of tire wear compounds and their transformation products in municipal wastewater and drinking water treatment plants

In the present study, 29 chemicals derived from tire wear were monitored by deploying Polar Organic Chemical Integrative Samplers (POCIS) in four WWTPs and two drinking water treatment plants (DWTPs) located in a municipality in southern Ontario, Canada. Target analytes included 1,3-diphenylguanidine (DPG), the oxidation byproduct of N-(1,3-dimethylbutyl)-N'-phenyl-1,4-benzenediamine called 6PPD-quinone, hexamethoxymethylmelamine (HMMM), and 26 of HMMM's known transformation products (TPs). This study is the first to monitor all these target compounds in DWTPs, as well as to report data for the presence of 6PPD-quinone in WWTPs. HMMM and selected TPs of this compound were detected in POCIS deployed in the WWTPs and in the DWTPs. The maximum estimated time-weighted average (TWA) concentration of HMMM of 83.2 ± 25.2 ng/L was observed in the effluent of one of the WWTPs. The TWA concentrations were not determined for any of the other target analytes, as POCIS sampling rates have not been determined for these chemicals. The total mass of HMMM and its TPs accumulated on POCIS frequently exceeded 4000 ng and the masses were generally lower in WWTP effluents relative to the influents. For other target analytes, the amounts accumulated on POCIS deployed in WWTP effluents frequently exceeded the amounts accumulated on POCIS deployed in the influents. DPG was detected in POCIS deployed in both the WWTPs and the DWTPs, and 6PPD-quinone was detected in POCIS deployed in both the influent and the effluent of WWTPs. We speculate that these tire wear compounds are entering WWTPs through stormwater overflows into the sewers or from commercial sources (e.g., car washes). This study highlights the need for an assessment of both WWTPs and DWTPs as sinks and sources of these tire wear compounds and the efficacy of treatment processes to remove them from both wastewater and drinking water.

Calibration and field validation of POCIS passive samplers for tracking artificial sweeteners as indicators of municipal wastewater contamination in surface waters

Polar organic chemical integrative samplers (POCIS) are widely used to track contaminants in surface waters. However, POCIS have not been used previously to monitor for artificial sweeteners as an indicator of wastewater pollution. In this study, we report for the first time the POCIS sampling rates (Rs_cal) for four artificial sweetener compounds, acesulfame (0.001 L/day), sucralose (0.114 L/day), cyclamate (0.001 L/day), and saccharin (0.002 L/day). We also prepared a modified POCIS with Strata X-AW anion exchange resin as a sorbent (i.e., ax-POCIS) and determined the sampling rates for sucralose (0.060 L/day) and acesulfame (0.128 L/day). Rs_cal values were adjusted according to the rate of loss of the performance reference compound, metoprolol-d₆ from deployed POCIS to yield field sampling rates (i.e., Rs_field). Field validation of the monitoring method was conducted in Presqu'ile Bay on the north-central coast of Lake Ontario that is impacted by discharges from a sewage lagoon. POCIS were deployed at four sites within the bay and in the lagoon discharge. The four artificial sweeteners, as well as caffeine, ibuprofen, and other microcontaminants of sewage origin, were present throughout the bay at estimated concentrations in the ng/L range, and in the lagoon discharge at estimated concentrations higher by approximately one order of magnitude. Because acesulfame is present in ionic form over the pH range of natural waters, there are uncertainties related to the sampling rates using the standard POCIS. Sucralose is recommended as the best choice for source tracking using POCIS. There was good agreement between the concentrations of sucralose estimated from POCIS and the measured concentrations in grab samples of surface water in the bay. The present study provides key data for monitoring artificial sweeteners using POCIS.

Impacts of endocrine disrupting chemicals on reproduction in wildlife and humans

Endocrine disrupting chemicals (EDCs) are ubiquitous in aquatic and terrestrial environments. The main objective of this review was to summarize the current knowledge of the impacts of EDCs on reproductive success in wildlife and humans. The examples selected often include a retrospective assessment of the knowledge of reproductive impacts over time to discern how the effects of EDCs have changed over the last several decades. Collectively, the evidence summarized here within reinforce the concept that reproduction in wildlife and humans is negatively impacted by anthropogenic chemicals, with several altering endocrine system function. These observations of chemicals interfering with different aspects of the reproductive endocrine axis are particularly pronounced for aquatic species and are often corroborated by laboratory-based experiments (i.e. fish, amphibians, birds). Noteworthy, many of these same indicators are also observed in epidemiological studies in mammalian wildlife and humans. Given the vast array of reproductive strategies used by animals, it is perhaps not surprising that no single disrupted target is predictive of reproductive effects. Nevertheless, there are some general features of the endocrine control of reproduction, and in particular, the critical role that steroid hormones play in these processes that confer a high degree of susceptibility to environmental chemicals. New research is needed on the implications of chemical exposures during development and the potential for long-term reproductive effects. Future emphasis on field-based observations that can form the basis of more deliberate, extensive, and long-term population level studies to monitor contaminant effects, including adverse effects on the endocrine system, are key to addressing these knowledge gaps.

An introduction to the sources, fate, occurrence and effects of endocrine disrupting chemicals released into the environment

Many classes of compounds are known or suspected to disrupt the endocrine system of vertebrate and invertebrate organisms. This review of the sources and fate of selected endocrine disrupting chemicals (EDCs) in the environment includes classes of compounds that are "legacy" contaminants, as well as contaminants of emerging concern. EDCs included for discussion are organochlorine compounds, halogenated aromatic hydrocarbons, brominated flame retardants, per- and polyfluoroalkyl substances, alkylphenols, phthalates, bisphenol A and analogues, pharmaceuticals, drugs of abuse and steroid hormones, personal care products, and organotins. An exhaustive survey of the fate of these contaminants in all environmental media (e.g., air, water, soil, biota, foods and beverages) is beyond the scope of this review, so the priority is to highlight the fate of EDCs in environmental media for which there is a clear link between exposure and endocrine effects in humans or in biota from other taxa. Where appropriate, linkages are also made between the fate of EDCs and regulatory limits such as environmental quality guidelines for water and sediments and total daily intake values for humans.

Vitellogenin Induction in Mucus from Brook Trout (Salvelinus fontinalis)

Induction of vitellogenin (VTG) is widely used as a biomarker of exposure of male or immature fish to chemicals that are agonists of the estrogen receptor (i.e., xenoestrogens). Analysis of VTG in samples of epidermal mucosa collected from fish is a non-invasive method for evaluating whether wild fish are exposed to xenoestrogens. In this study, the mean levels of VTG in the mucus of immature brook trout (Salvelinus fontinalis) collected from the Credit River in Ontario, Canada downstream of aging residential septic systems and in an agricultural watershed were 0.67 ng per mg protein, which was significantly elevated relative to the mean VTG levels of 0.22 ng per mg protein in the mucus of immature brook trout collected from a less impacted site. To validate the mucus assay, immature brook trout were exposed in the laboratory to 17α-ethinylestradiol (EE2) at nominal concentrations of 10, 50 and 100 ng/L and VTG levels in mucus from these fish showed a concentration-dependent increase relative to fish from the control treatment. This study illustrates the utility of this non-lethal method for assessing whether wild fish have been exposed in situ to xenoestrogens. Exposures to xenoestrogens from non-point sources may be impacting brook trout populations in urban watersheds in southern Ontario.

Methods for the analysis of endocrine disrupting chemicals in selected environmental matrixes

Endocrine disrupting chemicals (EDCs) are heterogenous in structure, chemical and physical properties, and their capacity to partition into various environmental matrixes. In many cases, these chemicals can disrupt the endocrine systems of vertebrate and invertebrate organisms when present at very low concentrations. Therefore, sensitive and varied analytical methods are required to detect these compounds in the environment. This review summarizes the analytical methods and instruments that are most used to monitor for EDCs in selected environmental matrixes. Only those matrixes for which there is a clear link between exposures and endocrine effects are included in this review. Also discussed are emerging methods for sample preparation and advanced analytical instruments that provide greater selectivity and sensitivity.

Sources of microbial contamination in the watershed and coastal zone of Soufriere, St. Lucia

The Sustainable Development Goal 6 calls for global progress by 2030 in treating domestic wastewater and providing access to adequate sanitation facilities. However, meeting these goals will be a challenge for most Small Island Developing States, including Caribbean island nations. In the nearshore zone of the Soufriere region on the Caribbean island of St. Lucia, there is a history of high levels of bacteria of fecal origin. Possible land-based sources of microbial contamination in the Soufriere Bay include discharges from the Soufriere River and transport of wastewater, including fecal material from the town of Soufriere. This area is an important tourist destination and supports a local fishery. To identify the sources of microbial contamination in Soufriere Bay, a range of monitoring methods were employed in this study. In grab samples of surface water collected from the Soufriere River, counts of total coliforms and Escherichia coli were elevated above water quality guidelines. However, the spikes in concentrations of these indicator organisms in the river did not necessarily coincide with the spikes in the levels of total coliforms and E. coli detected in samples collected on the same dates in Soufriere Bay, indicating that there are other sources of pollution in the Bay besides discharges from the river. Monitoring for chemical indicators of wastewater (i.e., caffeine, sucralose, fluconazole) in the Soufriere River indicated that there are inputs of sewage or human fecal material throughout the watershed. However, analysis of Bacteroidales 16S rRNA genetic markers for fecal bacteria originating from humans, bovine ruminants, or other warm-blooded animals indicated that the majority of microbial contamination in the river was not from humans. Monitoring for chemical indicators of wastewater using passive samplers deployed in Soufriere Bay indicated that there are two "hot spots" of contamination located offshore of economically depressed areas of the town of Soufriere. This study indicates that efforts to control contamination of Soufriere Bay by fecal microorganisms must include management of pollution originating from both sewage and domestic animals in the watershed.

Runoff of the Tire-Wear Compound, Hexamethoxymethyl-Melamine into Urban Watersheds

Hexamethoxymethyl-melamine (HMMM) is used as a crosslinking agent in resins and plastics and in the manufacture of tires. In the present study, surface water samples were collected from two rivers adjacent to high traffic highways in the Greater Toronto Area in Ontario, Canada. Composite samples collected from the Don River and Highland Creek during rain events and a period of rapid snowmelt were preconcentrated using solid phase extraction and analyzed using liquid chromatography with high-resolution mass spectrometry. Elevated concentrations (> 1 µg/L) of HMMM were detected in surface waters during rain events in October of 2019 and during snow melt in early March of 2020. There were lower average concentrations of HMMM detected during rain events in the winter and spring of 2020. Temporal profiles of changes in the concentrations of HMMM in composite samples collected every 3 h during a rain event in October 2019 closely corresponded to the hydrograph profiles at the sampling sites, with the HMMM concentrations peaking > 6 h after the peak in water levels. This work contributes to the literature showing that HMMM is a ubiquitous contaminant of urban watersheds and that runoff from roads is a vector for the transport of this compound into urban surface waters.

The Tire Wear Compounds 6PPD-Quinone and 1,3-Diphenylguanidine in an Urban Watershed

Prompted by a recent report that 6PPD-quinone (6PPD-q), a by-product of a common tire manufacturing additive that is present in road runoff, is toxic to coho salmon (Oncorhynchus kisutch), extracts of water samples collected from an urban river were re-analyzed to determine if this compound was present in stormwater-influenced flows. In addition, extracts were analyzed for 1,3-diphenylguanidine (DPG), which is also used in tire manufacturing. Samples were originally collected in the fall of 2019 and winter of 2020 in the Greater Toronto Area of Canada from the Don River, a highly urbanized watershed in close proximity to several major multi-lane highways. These target compounds were analyzed using ultra-high pressure liquid chromatography with high resolution mass spectrometric detection with parallel reaction monitoring. Both 6PPD-q and DPG were detected above limits of quantification (i.e., 0.0098 µg/L) in all extracts. Maximum concentrations for 6PPD-quinone of 2.30 ± 0.05 µg/L observed in the river during storm events exceeded the LC₅₀ for this compound for coho salmon (i.e., > 0.8 µg/L). In composite samples collected at intervals throughout one rain event, both compounds reached peak concentrations a few hours after initiation of the event (i.e., 0.52 µg/L for DPG and 2.85 µg/L for 6PPD-q), but the concentrations of 6PPD-q remained elevated above 2 µg/L for over 10-h in the middle of the event. Estimates of cumulative loads of these compounds in composite samples indicated that kg amounts of these compounds entered the Don River during each hydrological event, and the loads were proportional to the amounts of precipitation. This study contributes to the growing literature indicating that potentially toxic tire-wear compounds are present at elevated levels and are transported via road runoff into urban surface waters during rain events.

Detection of selected tire wear compounds in urban receiving waters

Road runoff is an important vector for the transport of chemicals originating from tire wear into receiving waters. In this study, samples of surface water were collected in the summer of 2020 from two rivers near high-traffic corridors in the Greater Toronto Area (GTA) in Canada. These samples were analyzed for two additives used in tire production, 1,3-diphenyl guanidine (DPG) and hexamethoxymethylmelamine (HMMM), as well 26 of the transformation compounds of HMMM. In addition, samples were analyzed for 6PPD-quinone (6PPD-q), an oxidation by-product of a tire additive that was recently identified as a candidate compound responsible for mass mortalities of Coho salmon (Oncorhynchus kisutch) in spawning streams in the USA. Grab and composite samples were collected during rain events (i.e., wet events) at both locations. Grab samples were collected from the Don River upstream, downstream and at the point of discharge from a municipal wastewater treatment plant (WWTP) during a period of dry weather. Of the target analytes, 6PPD-q, DPG and HMMM, as well as 15 of the transformation compounds of HMMM, were detected at concentrations above limits of quantitation. The concentrations of 6PPD-q in the receiving waters during wet events were within the range of the LC50 for adult Coho salmon. One of the transformation products (TPs) of HMMM, dimethoxymethylmelamine was detected in a composite sample from Highland Creek at an estimated concentration greater than 10 μg/L, indicating that more research is needed to evaluate the potential hazards to the aquatic environment from this compound. Sampling in the Don River during a dry period showed that discharges of wastewater from WWTPs are also continuous sources of the TPs of HMMM. This study contributes to the growing literature showing that chemicals derived from tire wear are ubiquitous in urban watersheds and may be a significant hazard to aquatic organisms.

Effects of opioids on reproduction in Japanese medaka, Oryzias latipes

To study the effects of exposure of fish to opioid drugs, we exposed Japanese medaka (Oryzias latipes) over a full life cycle to codeine spiked into river water at nominal concentrations of 100, 1,000 and 25,000 ng/L and to fentanyl spiked into river water at nominal concentrations of 5, 25 and 1,000 ng/L. The measured concentrations during medaka exposures were consistent with the nominal concentrations. Treatments with codeine at all test concentrations reduced the number of eggs produced by female medaka, as well as the number of mature oocytes observed histologically in the ovaries. Exposures to codeine also resulted in altered concentrations of hormones within the hypothalamic-pituitary-gonadal axis, including reduced levels of 17β-estradiol in female medaka. Fentanyl did not affect reproduction or the levels of hormones in medaka at the concentrations tested. Monitoring of surface waters in southern Ontario, Canada downstream of wastewater treatment plants showed that the test concentrations of fentanyl and codeine were environmentally relevant. The results of this work contribute to the literature on the impacts of opioids and other drugs of abuse released into surface waters.

Changes to levels of microcontaminants and biological responses in rainbow trout exposed to extracts from wastewater treated by catalytic ozonation

Two separate pilot-scale studies were performed at two wastewater treatment plants comparing conventional ozonation and catalytic ozonation with an alumina-based catalyst supplied by BASF. The results of the first pilot study showed that catalytic ozonation achieved the same degree of disinfection as conventional ozonation with 30% lower applied ozone dose and enhanced the removal of several contaminants of emerging concern (CECs). The second pilot study conducted over 6 months of operation with the same batch of catalyst showed sustained enhanced removal of CECs relative to ozonation alone. The removals of CECs by catalytic ozonation was particularly effective for compounds with low reaction rates with ozone, indicating reactions with hydroxyl radicals formed in the presence of the catalyst. Analysis of plasma vitellogenin and total glutathione in liver tissues of juvenile rainbow trout (Oncorhynchus mykiss) injected with wastewater extracts indicated that catalytic ozonation removed the estrogenic activity and modulated oxidative stress caused by exposure to the organic compounds in wastewater extracts. Analysis of other biomarker responses indicated that no transformation products were formed that can cause lipid damage in the liver or affect levels of a brain neurotransmitter (i.e. serotonin). Catalytic ozonation is a promising technology to increase the efficiency of ozone treatment of municipal wastewater and to meet increasingly more stringent regulations for effluent quality.

Using Indigenous and Western knowledge systems for environmental risk assessment

Indigenous rights, knowledge, and value systems are linked inextricably to the lands, waters, and non-human beings that form the environments of Indigenous Peoples. Across the globe, the rights of Indigenous peoples are being formally recognized and as a result, efforts are being made to include Indigenous Knowledge and value systems in environmental policy and decision making. Scientists and decision makers must not only recognize this reality, but also operationalize these efforts through meaningful changes to create space for the inclusion of Indigenous Knowledge, Indigenous values, and sovereignty within the current methods for scientific enquiry and the development of environmental policies. Professionals in the environmental field have a responsibility to ensure that their work has a positive impact on Indigenous Peoples and their environments. In this study, we explore the concept of consultation and informed consent through the lens of the development of environmental policy and decision making. We will discuss these concepts in the context of ecological risk assessment related to a case study focused on contaminated sediment in a harbor within the Great Lakes. We will demonstrate a process that deconstructs the current protocols for risk assessments at sites with localized pollutants in sediment and rebuilds them with elements that recognize both Western and Indigenous knowledge systems. This process includes collaborative fieldwork, relationship building, and informal and formal interviews with participants and community members. By utilizing such approaches, we were able to develop a risk assessment framework that recognizes the sovereignty of Indigenous peoples and promotes effective Nation-to-Nation decision making.

Multi-Level Responses of Yellow Perch (Perca flavescens) to a Whole-Lake Nanosilver Addition Study

Silver nanoparticles (AgNP) are widely used as antibacterial agents in both commercial products and for industrial applications. As such, AgNP has a high potential for release into freshwater environments. As part of a whole-lake ecosystem experiment to examine the impacts of AgNP exposure at low µg/L concentrations over multiple years, we evaluated biological responses in Yellow Perch (Perca flavescens) before, during, and after AgNP additions to a freshwater lake. Yellow Perch were monitored for responses to in situ AgNP additions at the cellular (suite of biomarkers), individual (growth, prey consumption, and metabolism), and population (abundance and gross prey consumption) scales. At the cellular level, several biomarkers of oxidative stress in liver tissues revealed down-regulation, including decreased mRNA levels of catalase and glutathione peroxidase in Yellow Perch collected during AgNP exposure, and elevated ratios of reduced to oxidized glutathione. At the individual level, Yellow Perch bioenergetic models revealed that prey consumption and total metabolism significantly declined during AgNP additions and remained depressed one year after AgNP addition. At the population level, Yellow Perch densities and gross prey consumption declined after AgNP was added to the lake. Together, these results reveal a holistic assessment of the negative impacts of chronic exposure to environmentally relevant AgNP concentrations (i.e., µg/L) on Yellow Perch at cellular, individual, and population levels.

Pesticides in Surface Waters in Argentina Monitored Using Polar Organic Chemical Integrative Samplers

Polar Organic Chemical Integrative Samplers (POCIS) were deployed in two watersheds in Córdoba province and one watershed in Buenos Aires province in Argentina. The fungicides, tebuconazole, carbendazim and azoxystrobin, and the herbicides, atrazine, dicamba and 2,4-D were detected in POCIS deployed in each of the three watersheds. Estimated time weighted average concentrations of atrazine were greater than 2 µg/L at the outflow of Brava Lake in Buenos Aires province, and this concentration exceeds the Canadian water quality guideline for protection of aquatic life. The concentrations of all other pesticides were less than 400 ng/L. The distribution of pesticides detected in surface waters indicated that the sources were runoff from agricultural and urban lands and discharges from wastewater treatment plants.

Micropollutants related to human activity in groundwater resources in Barbados, West Indies

Several micropollutants, including caffeine, artificial sweeteners, pharmaceuticals, steroid hormones and a current-use pesticide were analyzed in water samples collected from five groundwater pumping stations in Barbados. The presence of caffeine and three artificial sweeteners (i.e. acesulfame, sucralose, saccharin) in groundwater samples indicated that groundwater was being contaminated by infiltration of wastewater into the karst aquifer. An estrogen (i.e. estrone), three pharmaceuticals (i.e. carbamazepine, trimethoprim, ibuprofen) and a transformation product of the fungicide, chlorothalonil (i.e. 4-hydroxychlorothalonil) were also detected at ng/L concentrations in groundwater collected from two or more pumping sites. The concentrations of carbamazepine and trimethoprim were correlated with the concentrations of caffeine (R² values of 0.70 to 0.80), indicating pharmaceutical contamination of groundwater by infiltration from domestic wastewater. The concentrations of caffeine were generally higher in groundwater samples collected in June during the wet season relative to the concentrations in samples collected in February during the dry season, indicating that infiltration of contaminants is higher during periods of heavy rainfall. Rapid rates of degradation and relatively slow rates of infiltration may explain why several target analytes were not detected in groundwater. Elevated concentrations of 4-hydroxychlorothalonil > 0.1 μg/L in samples collected at two of the monitoring sites warrant further studies on the sources and the distribution of this compound and other pesticides used in agriculture and for turf-treatment (e.g. golf courses). Overall, more data are needed in order to implement mitigation strategies that are effective in reducing chemical contamination in groundwater in Barbados.

Assessing the effects of environmentally relevant concentrations of antidepressant mixtures to fathead minnows exposed over a full life cycle

Antidepressant drugs have been detected in municipal wastewater effluents (MWWEs) at ng/L to low μg/L concentrations. We exposed fathead minnow (Pimephales promelas) over a full lifecycle to a mixture of five antidepressants at concentrations similar to a MWWE (1× AntiD Mix); venlafaxine at 2400 ng/L, citalopram at 240 ng/L, fluoxetine at 90 ng/L, sertraline at 20 ng/L, and bupropion at 90 ng/L, and 10× these concentrations (i.e. 10× AntiD Mix). Mean measured concentrations of venlafaxine, citalopram, fluoxetine, sertraline, and bupropion were 2300, 160, 110, 7 ng/L, and below detection limits, respectively, for the 1× AntiD Mix, and 33,000, 2900, 1000, 210, and 100 ng/L, respectively for the 10× AntiD Mix. During the life-cycle exposure, no significant changes were observed in survival of fathead minnows. When male fish from the exposed treatments reached maturity, their weights were increased compared to control males. There were no significant differences in condition factor, gonadosomatic index, or liver-somatic index in the exposed fish. Exposed fathead minnows produced similar numbers of eggs as control fish, and there were no changes in nest-defense behaviours of male minnows. Egg quality, % fertilization, and % hatching in F1 fry were unaffected by exposure to the antidepressants. Eggs hatched 0.5 d earlier, deformities in fry were 50% lower, and there were transient decreases in length of F1 larvae at 8 days post-hatch in offspring from the treatment with the 10× AntiD Mix. Overall, exposure to the antidepressant mixture at environmentally relevant concentrations (i.e. 1× AntiD Mix) caused no adverse effects in fathead minnows. Exposure to the 10× AntiD Mix increased the weight of adult male minnows and caused subtle effects in F1 offspring. This study is the first to assess sublethal effects in fish exposed to mixtures of antidepressants over a full lifecycle. CAPSULE: No effects were observed in fathead minnow exposed for a lifecycle to antidepressant mixtures at environmentally-relevant concentrations.

Pesticides related to land use in watersheds of the Great Lakes basin

In this study, we evaluated the distribution and concentrations of a range of neonicotinoid insecticides (NNIs) and other insecticides, fungicides, biocides and selected herbicides in watersheds that drain into the lower Great Lakes in Ontario, Canada. Polar Organic Chemical Integrative Samplers (POCIS) were deployed in 18 watersheds during late May to late June of 2016. Grab samples were also collected in 7 of these watersheds. There was generally good agreement between the time-weighted average concentrations of pesticides estimated from the POCIS and the concentrations detected in grab samples. The NNIs, thiamethoxam, clothianidin and imidacloprid, were present in several watersheds at concentrations that exceeded the Canadian Water Quality Guideline for imidacloprid of 0.23 μg/L. The new generation insecticides, flonicamid and flupyradifurone were also detected in some watersheds, which is the first report of these pesticides in the peer-reviewed literature. Atrazine, 2,4-D, dicamba, carbendazim, thiophanate methyl and several azole-based fungicides were also widely detected. Discriminant Function Analysis (DFA) indicated that a high proportion (i.e. >80%) of the watersheds could be discriminated from each other on the basis of the pattern of pesticides detected in surface waters, and the proportion of field crops in the watershed.

Accumulation of Silver in Yellow Perch ( Perca flavescens) and Northern Pike ( Esox lucius) From a Lake Dosed with Nanosilver

A total of 15 kg of silver nanoparticles (AgNPs) was added continuously over two ice-free field seasons to a boreal lake (i.e., Lake 222) at the IISD Experimental Lakes Area in Canada. We monitored the accumulation of silver (Ag) in the tissues of yellow perch ( Perca flavescens) and northern pike ( Esox lucius) exposed to the AgNPs under environmentally relevant conditions. The greatest accumulation was observed in the liver tissues of pike, and a single pike sampled in the second year of additions had the highest concentration observed in liver of 5.1 micrograms per gram of wet weight. However, the Ag concentrations in gill and muscle tissue of both pike and perch did not exceed 0.35 micrograms per gram of wet weight. Following additions of AgNP, the Ag residues in fish tissues declined, with a half-life of Ag in pike liver of 119 days. Monitoring using passive sampling devices and single-particle inductively coupled plasma mass spectrometry during the AgNP addition phase confirmed that Ag nanoparticles were present in the water column and that estimated mean concentrations of Ag increased over time to a maximum of 11.5 μg/L. These data indicate that both a forage fish and a piscivorous fish accumulated Ag in a natural lake ecosystem dosed with AgNPs, leading to Ag concentrations in some tissues of the piscivorous species that were 3 orders of magnitude greater than the concentrations in the water.

Silver near municipal wastewater discharges into western Lake Ontario, Canada

Because of the widespread use of silver nanoparticles in commercial products, discharges of municipal wastewater may be a point source of silver in the aquatic environment. We monitored two sites in western Lake Ontario impacted by discharges from wastewater treatment plants serving the City of Toronto. Concentrations of silver were elevated in bottom sediments and suspended sediments collected at the two sites. We also deployed two types of passive samplers in the water column at the two sites, the newly developed Carbon Nanotube Integrative Samplers for monitoring "CNIS-labile" silver and Diffusive Gradient in Thin Film samplers for monitoring "DGT-labile" silver. Results from these passive samplers indicated that the concentrations of silver at the two sites were either below detection limits or were in the ng/L range. In laboratory experiments where the sediments were re-suspended in Milli-Q water, a small proportion of the silver (i.e., < 25%) was labile and partitioned as colloidal or dissolved silver into the liquid phase after agitation. Nanoparticles tentatively identified as silver nanoparticles were detected by single-particle ICP-MS in suspension after agitation of both suspended and bottom sediments. Therefore, there is a need to assess whether silver species, including silver nanoparticles are transported from wastewater treatment plants into sediments in the aquatic environment. This study is unique in focusing on the in situ distribution of silver in natural waters and in sediments that are potentially impacted by urban sources of nanoparticles.

Neonicotinoid pesticides in drinking water in agricultural regions of southern Ontario, Canada

Because of the persistence and solubility of neonicotinoid insecticides (NNIs), there is concern that these compounds may contaminate sources of drinking water. The objective of this project was to evaluate the distribution of NNIs in raw and treated drinking water from selected municipalities that draw their water from the lower Great Lakes in areas of southern Ontario, Canada where there is high intensity agriculture. Sites were monitored using Polar Organic Chemical Integrative Samplers (POCIS) and by collecting grab samples at six drinking water treatment plants. Thiamethoxam, clothianidin and imidacloprid were detected in both POCIS and grab samples of raw water. The frequency of detection of NNIs was much lower in treated drinking water, but some compounds were still detected at estimated concentrations in the low ng L^-1 range. Thiamethoxam was detected in one grab sample of raw drinking water at a mean concentration of 0.28 μg L^-1, which is above the guidelines for drinking water recommended in some jurisdictions, including the European Union directive on pesticide levels <0.1 μg L^-1 in water intended for human consumption. Further work is required to determine whether contamination of sources of drinking water with this class of insecticides is a global problem in agricultural regions.

Contaminants of Emerging Concern in Wastewaters in Barbados, West Indies

There have been few reports in the peer-reviewed literature on the levels of contaminants of emerging concern (CECs) in municipal wastewater from the Caribbean region. In this study of wastewater collected from two wastewater treatment plants in Barbados, caffeine and ibuprofen were detected at µg/L concentrations, whereas two steroid hormones (i.e. androstenedione, estrone) and several prescription pharmaceuticals were detected at ng/L concentrations. Among drugs of abuse, benzoylecgonine (i.e. metabolite of cocaine), MDMA (i.e. Ecstasy) and MDA (i.e. 3,4-methylenedioxyamphetamine) were present at the highest concentrations in untreated wastewater. Overall, these data show that there is potential impact in the marine environment in Barbados from CECs discharged into the coastal zone.

Nest-defense behaviors in fathead minnows after lifecycle exposure to the antidepressant venlafaxine

Venlafaxine is an antidepressant and anti-anxiety drug that has been detected in municipal wastewater at low μg/L concentrations. In this study, the nest-defense behavior of adult male fathead minnows (Pimephales promelas) was observed in fish exposed for a full lifecycle to venlafaxine nominal concentrations of 0.88, 8.8, and 88 μg/L (i.e. 1, 9.3, 75 μg/L mean measured concentrations). Nest-defense behaviors quantified were the time taken to contact a dummy intruder fish (on a flexible stick, held near each nest) and the number of contacts made during a 1 min period. In male fathead minnows exposed to venlafaxine over a full lifecycle at environmentally relevant nominal concentrations (i.e. 0.88 and 8.8 μg/L) no significant effects were observed in behavior. However, in males exposed over a full lifecycle to the highest concentration of venlafaxine (i.e. 88 μg/L), nest-defense behaviors were increased in males with empty nests, as shown by the significantly elevated percentage of empty-nest males that made contact with the dummy intruder fish (89%) relative to the lower percentage of contacts (65%) among the Control males (p = 0.046). Lifecycle exposure to high venlafaxine (88 μg/L) caused males to over-protect their empty nests. Environmental venlafaxine concentrations are approximately 70 x lower than this, so it is unlikely that behavioral changes from venlafaxine exposure would occur in the environment. Normal nest defense behaviours in control males varied, depending on whether they were protecting empty nests or nests with eggs. Compared to Control males with empty nests, more Control males with eggs in their nests made contact with the dummy intruder fish (p = 0.014), contact was faster (i.e. <10 s, p = 0.011), and they hit the dummy intruder fish more times in 1 min (p = 0.031) This study is the first to assess reproductive behaviors in fish exposed to an antidepressant over a full lifecycle.

Evaluation of wastewater treatment by ozonation for reducing the toxicity of contaminants of emerging concern to rainbow trout (Oncorhynchus mykiss)

Although conventional wastewater treatment technologies are effective at removing many contaminants of emerging concern (CECs) from municipal wastewater, some contaminants are not removed efficiently. Ozonation may be a treatment option for reducing the concentrations of recalcitrant CECs in wastewater, but this process may generate toxic transformation products. In the present study, we conducted semibatch experiments to ozonate municipal wastewater effluent spiked with 5 commonly detected CECs. The purpose of the present study was to evaluate whether ozonation increased or decreased biological responses indicative of sublethal toxicity in juvenile rainbow trout (Oncorhynchus mykiss) injected intraperitoneally (i.p.) with extracts prepared from ozonated and nonozonated wastewater effluent. Blood, liver, and brain tissues were collected from the fish at 72 h post injection for analysis of a battery of biomarkers. In fish i.p. injected with the extracts from nonozonated wastewater effluent, significant induction of plasma vitellogenin (VTG) was observed, but ozonation of the municipal wastewater effluent spiked with CECs significantly reduced this estrogenic response. However, in fish injected with extracts from spiked municipal wastewater effluent after ozonation, the balance of hepatic glutathione in its oxidized (glutathione disulfide [GSSG]) form was altered, indicating oxidative stress. Levels of the neurotransmitter serotonin were significantly elevated in brain tissue from trout injected with the extracts from ozonated spiked municipal wastewater effluent, a biological response that has not been previously reported in fish. Other in vivo biomarkers showed no significant changes across treatments. These results indicate that ozonation reduces the estrogenicity of wastewater, but may increase other sublethal responses. The increase in biomarker responses after ozonation may be because of the formation of biologically active products of transformation of CECs, but further work is needed to confirm this conclusion. Environ Toxicol Chem 2018;37:274-284. © 2017 SETAC.

Effect of imidacloprid on the survival of Xenopus tadpoles challenged with wild type frog virus 3

The sensitivity of amphibians to Ranavirus may be increased by exposure to other environmental stressors, including chemical contaminants. Neonicotinoid insecticides comprise 27% of the global insecticide market and have been detected in wetlands and other aquatic habitats. The present study focused on the effects of exposure of pre-metamorphic Xenopus laevis to the neonicotinoid, imidacloprid (IMI) on sensitivity to frog virus 3 (FV3) infection. It was hypothesized that exposure of tadpoles to IMI at sublethal concentrations of 1 and 500μgL^-1 would increase FV3 related mortalities relative to tadpole mortalities in a control treatment with only the virus. However, contrary to the predicted outcome, IMI reduced the rates of mortality following viral challenge, although the total mortalities by the 25th day after infection did not differ among the treatments. These results should not be interpreted as an indication that neonicotinoid insecticides are beneficial to aquatic ecosystems, since these insecticides cause toxic responses at low concentrations to other non-target aquatic organisms.

Toxicity of extracts from municipal wastewater to early life stages of Japanese medaka (Oryzias latipes) to evaluate removals of micropollutants by wastewater treatment

Treatment of municipal wastewater reduces the concentrations of some pharmaceuticals and personal care products (PPCPs), hormones, and drugs of abuse. However, reduced concentrations of these micropollutants in wastewater may not correlate with reduced toxicity because transformations of micropollutants and/or the formation of disinfection by-products may generate toxic compounds. In the present study, we prepared extracts by solid phase extraction of samples collected from wastewater treatment plants (WWTPs) at various stages of treatment and tested these extracts for toxicity to early life stages of Japanese medaka (Oryzias latipes). Toxicity data for extracts prepared from a WWTP with secondary treatment showed that the numbers of exposed embryos (n = 12 per treatment) that did not hatch increased from 1 of 12 for the treatment with untreated effluent to 5 of 12 for the treatment with final treated effluent. For extracts prepared from a WWTP with tertiary treatment, toxicity among exposed embryos (n = 12 per treatment) also increased with each step of wastewater treatment, as shown by mortalities of 2 of 12 and 8 of 12 in treatments with extracts from untreated and final treated effluent, respectively, as well as an increase in the numbers of embryos that did not hatch from 2 of 12 to 9 of 12 in treatments with untreated and final treated effluent, respectively. Ozonation of treated wastewater collected from a third WWTP caused a high incidence of delayed hatch in exposed embryos (n = 24 per treatment). However, hatching success and the numbers of developmental abnormalities in embryos from this ozonation treatment were not different from controls. The present study shows the value of including toxicity testing to assess the effectiveness of technologies for treatment of municipal wastewater. Environ Toxicol Chem 2018;37:136-144. © 2017 SETAC.

Bioconcentration of polycyclic musks in fathead minnows caged in a wastewater effluent plume

The synthetic polycyclic musks HHCB (Galaxolide^®) and AHTN (Tonalide^®) were monitored in fathead minnows (FHMs) caged for a month at various locations in the North Saskatchewan River (NSR), upstream and downstream of the Gold Bar wastewater treatment plant that serves the city of Edmonton, AB, Canada. In addition, the distribution of these musk compounds in the river was predicted using the fugacity-based Quantitative Water Air Sediment Interface (QWASI) model. In FHMs caged 0.15 km downstream of the wastewater outfall, mean concentrations of HHCB and AHTN were 7.4 and 0.4 μg g^-1 wet weight, respectively. These are among the highest reported concentrations of these musk compounds in fish exposed to treated wastewater. The musk concentrations in FHMs were significantly lower further downstream of the outfall. High bioconcentration factors (BCFs) in FHMs that exceeded 10⁴ higher than estimated concentrations in water indicated that there were low rates of biotransformation of the musks in the fish. In the FHMs caged at the site closest to the wastewater outfall, HHCB concentrations in FHMs were comparable to the body burdens that have been reported to moderate expression of vitellogenin in female rainbow trout, indicating that fish in the NSR downstream of the wastewater outfall may be at risk of anti-estrogenic effects. The QWASI model applied to six individual river sections of the NSR predicted that the largest fluxes of HHCB and AHTN would be for downstream transport in water, which explains why FHMs accumulated elevated concentrations of the musks at the furthest downstream site, 9.9 km from the wastewater discharge.

Contaminants of emerging concern in surface waters in Barbados, West Indies

Contaminants of emerging concern (CECs), including pharmaceuticals, artificial sweeteners, steroid hormones, and current-use pesticides have been detected in surface waters around the world, but to date, there have been no reports in the peer-reviewed literature on the levels of these classes of contaminants in freshwater resources in the Caribbean region. In the present study, multi-residue solid phase extraction (SPE) and liquid chromatography with tandem mass spectroscopy (LC-MS/MS) were used to analyze grab samples of surface waters collected from five different watersheds in Barbados, West Indies. The artificial sweeteners (AS), acesulfame, cyclamate, saccharin, and sucralose were widely detected in the watersheds, indicating contamination from domestic wastewater, and the concentrations of these chemical tracers in water were correlated with the concentrations of the non-prescription pharmaceutical, ibuprofen (R ² values of 0.4-0.6). Surprisingly, the concentrations of another chemical tracer of domestic wastewater, caffeine were not correlated with ibuprofen or AS concentrations. Several other prescription pharmaceuticals and the steroid hormones, estrone and androstenedione, were detected in selected watersheds at low ng/L concentrations. The fungicide, chlorothalonil was widely detected in surface waters at low (< 10 ng/L) concentrations, but the levels of this pesticide were not correlated with the concentrations of the other target analytes, indicating that the source of this pesticide is not domestic wastewater. An informal survey of disposal practices for out of date or unused drugs by pharmacies in Barbados indicated that disposal into trash destined for the landfill and flushing down the sink might be significant sources of contamination of water resources by pharmaceuticals.

A Method for Preparing Silver Nanoparticle Suspensions in Bulk for Ecotoxicity Testing and Ecological Risk Assessment

Methods are needed to prepare stable suspensions of engineered nanoparticles in aqueous matrixes for ecotoxicity testing and ecological risk assessments. We developed a novel method of preparing large volumes of silver nanoparticles (AgNP) in suspension using a commercially available rotor-stator dispersion mill. AgNP in powder form (PVP capped, 30-50 nm) was suspended in deionized water and natural lake water at 1 g/L and the addition of 0.025% (w/v) gum arabic (GA) increased stability over 2 weeks after preparation. The concentrations of total and dissolved Ag in the suspensions did not change significantly over this period. Analysis of hydrodynamic diameters of the major peaks in suspension using dynamic light scattering showed that suspensions prepared with GA were stable, and this was confirmed by single-particle ICP-MS analysis. This method for dispersing AgNPs provides an inexpensive, yet reliable method for preparing suspensions for toxicity testing and ecosystem level studies of the fate and biological effects of AgNPs in aquatic ecosystems.

Biomarkers of exposure to nanosilver and silver accumulation in yellow perch (Perca flavescens)

There is a risk of exposure of aquatic organisms to silver nanoparticles (AgNPs) from discharges of municipal and industrial wastewater. In the present study, yellow perch (Perca flavescens) were exposed to environmentally relevant concentrations (1 mg/L and 100 mg/L) of AgNPs and silver ions (Ag⁺ ) in static-renewal experiments conducted over 96 h and 10 d. The greatest accumulation of total Ag occurred in the liver of P. flavescens, and there was >10-fold more accumulation in the treatments with Ag⁺ relative to the AgNP treatments. Residues of total Ag increased with concentration and duration of exposure in liver, gill, and muscle. Both exposures caused a 2-fold induction of gene expression for metallothionein (mt) in liver tissue after 96 h of exposure and reductions in levels of oxidized glutathione (GSSG) in liver after 10 d of exposure. Both AgNPs and Ag⁺ decreased the expression of heat-shock proteins (hsp70). Exposure to the high concentration of AgNPs for 10 d significantly increased lipid peroxidation in gill tissue, as indicated by the thiobarbituric acid reactive substances (TBARS) assay. There was a negative correlation between mean levels of GSSG and TBARS for both gill and liver tissue when data for all treatments were combined. It is significant that these biological responses were observed in P. flavescens exposed to AgNPs, even though accumulation of total Ag was at least 10-fold lower relative to the treatments with Ag⁺ . Environ Toxicol Chem 2017;36:1211-1220. © 2016 SETAC.

Fate and mass balance of contaminants of emerging concern during wastewater treatment determined using the fractionated approach

Contaminants of emerging concern (CECs) are often poorly removed from wastewater using conventional treatment technologies and there is limited understanding of their fate during treatment. Inappropriate sampling strategies lead to inaccuracies in estimating removals of CECs. In this study, we used the "fractionated approach" that accounts for the residence time distribution (RTD) in treatment units to investigate the fate of 26 target CECs in a municipal wastewater treatment plant (WWTP) that includes primary, secondary and tertiary treatment steps. Prior hydraulic calibration of each treatment unit was performed. Wastewater and sludge samples were collected at different locations along the treatment train and the concentrations of target CECs were measured by liquid chromatography mass spectrometry. The most substantial aqueous removal occurred during activated sludge treatment (up to 99%). Removals were <50% in the primary clarifier and tertiary rotating biological contactors (RBCs) and up to 70% by sand filtration. Mass balance calculations demonstrated that (bio)degradation accounted for up to 50% of the removal in the primary clarifier and 100% in activated sludge. Removal by sorption to primary and secondary sludge was minimal for most CECs. Analysis of the selected metabolites demonstrated that negative removals obtained could be explained by transformations between the parent compound and their metabolites. This study contributes to the growing literature by applying the fractionated approach to calculate removal of different types of CECs across each wastewater treatment step. An additional level of understanding of the fate of CECs was provided by mass balance calculations in primary and secondary treatments.

Monitoring contaminants of emerging concern from tertiary wastewater treatment plants using passive sampling modelled with performance reference compounds

The Lake Simcoe watershed in Ontario, Canada is an important recreational area and a recharge zone for groundwater resources. Lake Simcoe is a relatively shallow lotic system that has been impacted by urban development, recreation, industry and agriculture. As part of a watershed management plan, six wastewater treatment plants (WWTPs) located in this catchment basin were selected to measure the inputs of contaminants of emerging concern (CECs) of wastewater origin. These WWTPs were recently upgraded to tertiary treatment for phosphorus removal. Polar organic chemical integrative samplers (POCIS) and semipermeable membrane devices (SPMDs) were used to monitor for hydrophilic and hydrophobic CECs, respectively, in treated and untreated wastewater. The passive samplers were calibrated with performance reference compounds (PRCs) by measuring the loss of deuterated beta blocker drugs spiked into POCIS and the loss of PCB congeners spiked into SPMDs over the course of 14-day deployment periods. From the PRC data, field sampling rates of CECs were determined and applied to estimate time-weighted average (TWA) concentrations and mass loadings in mg/day/1000 members of the population serviced. In treated wastewater, TWA concentrations of an antibiotic, sulfamethoxazole, the prescription drugs, carbamazepine, naproxen and gemfibrozil, and the non-prescription drug, ibuprofen, were estimated to be in the low (<18 ng/L) range. The artificial sweeteners, sucralose and acesulfame, were particularly useful chemical tracers, with estimated TWA concentrations in treated wastewater ranging from 128 to 213 ng/L and 4 to 33 ng/L, respectively. The steroid hormones were detected only rarely in treated wastewater. Triclosan, triclocarban and the synthetic musks, HHCB and AHTN, were removed efficiently (>77 %), possibly because of the tertiary treatment technologies. Therefore, the mass loadings for these personal care products were all <5 mg/day/1000 people. Overall, this study indicates that tertiary treatment technologies designed for phosphorus removal do not entirely remove the target CECs.

Carbon Nanotube Integrative Sampler (CNIS) for passive sampling of nanosilver in the aquatic environment

Nanomaterials such as nanosilver (AgNP) can be released into the aquatic environment through production, usage, and disposal. Sensitive and cost-effective methods are needed to monitor AgNPs in the environment. This work is hampered by a lack of sensitive methods to detect nanomaterials in environmental matrixes. The present study focused on the development, calibration and application of a passive sampling technique for detecting AgNPs in aquatic matrixes. A Carbon Nanotube Integrative Sampler (CNIS) was developed using multi-walled carbon nanotubes (CNTs) as the sorbent for accumulating AgNPs and other Ag species from water. Sampling rates were determined in the laboratory for different sampler configurations and in different aquatic matrixes. The sampler was field tested at the Experimental Lakes Area, Canada, in lake water dosed with AgNPs. For a configuration of the CNIS consisting of CNTs bound to carbon fiber (i.e. CNT veil) placed in Chemcatcher® housing, the time weighted average (TWA) concentrations of silver estimated from deployments of the sampler in lake mesocosms dosed with AgNPs were similar to the measured concentrations of "colloidal silver" (i.e. <0.22μm in size) in the water column. For a configuration of CNIS consisting of CNTs in loose powder form placed in a custom made housing that were deployed in a whole lake dosed with AgNPs, the estimated TWA concentrations of "CNIS-labile Ag" were similar to the concentrations of total silver measured in the epilimnion of the lake. However, sampling rates for the CNIS in various matrixes are relatively low (i.e. 1-20mL/day), so deployment periods of several weeks are required to detect AgNPs at environmentally relevant concentrations, which can allow biofilms to develop on the sampler and could affect the sampling rates. With further development, this novel sampler may provide a simple and sensitive method for screening for the presence of AgNPs in surface waters.

Monitoring the Fate and Transformation of Silver Nanoparticles in Natural Waters

There is potential for silver nanoparticles (AgNPs) to be released into surface waters and thus affect aquatic organisms. However, agglomeration, dissolution, surface modifications and chemical speciation are important transformation processes that control the toxicity of AgNPs. Analytical methods are needed to determine the size distribution, mass and form of AgNPs and other silver species in natural waters. Cloud point extraction, single particle inductively coupled plasma mass spectrometry (spICP-MS) and asymmetric flow field flow fractionation with on-line ICP-MS (AF4-ICP-MS) are analytical techniques that show potential for quantitative analysis of AgNPs in aquatic matrices at environmentally relevant concentrations. In this review, we discuss the fate processes for AgNPs in natural waters and the analytical methods that can be used to determine the distribution of AgNPs and their transformation products.

Linking drugs of abuse in wastewater to contamination of surface and drinking water

The concentrations of 17 drugs of abuse, including cocaine, several amphetamines, opioid drugs, and 2 metabolites--benzoylecgonine, a metabolite of cocaine, and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrolidine, a metabolite of methadone--were investigated in an urban watershed that is heavily impacted by discharges of municipal wastewater. The artificial sweetener sucralose was also monitored as a persistent tracer of contamination from municipal wastewater. Monitoring was conducted in a municipal wastewater treatment plant (WWTP) and at sites upstream and downstream of the WWTP discharge, as well as in a drinking water treatment plant (DWTP) located 19 km downstream of the WWTP discharge that withdraws raw water from the river. Drug concentrations were monitored with polar organic chemical integrative samplers deployed for 2 wk in the river and in the WWTP and DWTP. Several of the investigated compounds exhibited a decrease in concentration with distance downstream from the wastewater discharge into the river, but there was little attenuation of sucralose, cocaine, benzoylecgonine, morphine, acetylmorphine, acetylcodeine, and oxycodone. Heroin and methadone were not detected at any sample locations. Amphetamine, methamphetamine, 3,4-methylenedioxy-methamphetamine, and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrolidine were not detected in the samples collected at the drinking water intake. Many of the drugs of abuse were not removed effectively in the DWTP, including cocaine, benzoylecgonine, methylenedioxyamphetamine, ephedrine, and several prescription opioids, most probably because the DWTP was operating at or above its rated treatment capacity. These data indicate that there can be transport of drugs of abuse from wastewater sources into drinking water in urban watersheds.

Direct UV photolysis of selected pharmaceuticals, personal care products and endocrine disruptors in aqueous solution

Pharmaceuticals and personal care products (PPCPs), and endocrine disrupting compounds (EDCs) are micropollutants of emerging concern that have been detected in the aquatic environment and in some cases, in drinking water at nanogram per liter levels. The goal of this study was to evaluate the removal of 15 model PPCPs and EDCs from water by direct UV photolysis, using either low (LP)-or medium (MP) -pressure mercury vapor arc lamps. Some of the model compounds are either weak bases or weak acids, and therefore, the pKa values were determined or confirmed for those compounds using spectrophotometric titrations. The molar absorption coefficients of ionized and non-ionized forms were also determined. The quantum yields at 253.7 nm in phosphate buffer solutions of pH 7.2 were determined to be 0.033 ± 0.004 for sulfamethoxazole, 0.0035 ± 0.0008 for sulfachloropyridazine, 0.006 ± 0.002 for acetaminophen, 0.34 ± 0.07 for triclosan, 0.35 ± 0.14 for estrone, 0.08 ± 0.05 for 17α-ethinylestradiol, 0.086 ± 0.012 for ibuprofen. The quantum yield for 4-n-nonylphenol photolysis at 253.7 nm varied with the initial concentration from 0.32 ± 0.08 at 23 μg/L to 0.092 ± 0.006 at 230 μg/L. The pseudo-first order rate constants determined for direct photolysis at 253.7 nm of the studied micropollutants followed the order: triclosan ≈ sulfamethoxazole >> 4-n-nonylphenol ≈ sulfachloropyridazine ≈ estrone > acetaminophen ≈ 17α-ethinylestradiol ≈ ibuprofen. In contrast to the results observed for the monochromatic radiation (LP lamp), all 15 model compounds photolyzed under exposure to the broadband radiation emitted by the MP lamp.

Assessment of biomarkers for contaminants of emerging concern on aquatic organisms downstream of a municipal wastewater discharge

Contaminants of emerging concern (CECs), including pharmaceuticals, personal care products and estrogens, are detected in wastewater treatment plant (WWTP) discharges. However, analytical monitoring of wastewater and surface water does not indicate whether CECs are affecting the organisms downstream. In this study, fathead minnows (Pimephales promelas) and freshwater mussels Pyganodon grandis Say, 1829 (synonym: Anodonta grandis Say, 1829) were caged for 4 weeks in the North Saskatchewan River, upstream and downstream of the discharge from the WWTP that serves the Edmonton, AB, Canada. Passive samplers deployed indicated that concentrations of pharmaceuticals, personal care products, an estrogen (estrone) and an androgen (androstenedione) were elevated at sites downstream of the WWTP discharge. Several biomarkers of exposure were significantly altered in the tissues of caged fathead minnows and freshwater mussels relative to the upstream reference sites. Biomarkers altered in fish included induction of CYP3A metabolism, an increase in vitellogenin (Vtg) gene expression in male minnows, elevated ratios of oxidized to total glutathione (i.e. GSSG/TGSH), and an increase in the activity of antioxidant enzymes (i.e. glutathione reductase, glutathione-S-transferase). In mussels, there were no significant changes in biomarkers of oxidative stress and the levels of Vtg-like proteins were reduced, not elevated, indicating a generalized stress response. Immune function was altered in mussels, as indicated by elevated lysosomal activity per hemocyte in P. grandis caged closest to the wastewater discharge. This immune response may be due to exposure to bacterial pathogens in the wastewater. Multivariate analysis indicated a response to the CECs Carbamazepine (CBZ) and Trimethoprim (TPM). Overall, these data indicate that there is a 1 km zone of impact for aquatic organisms downstream of WWTP discharge. However, multiple stressors in municipal wastewater make measurement and interpretation of impact of CECs difficult since water temperature, conductivity and bacteria are also inducing biomarker responses in both fish and mussels.

Environmental Fate of Silver Nanoparticles in Boreal Lake Ecosystems

Silver nanoparticles (AgNPs) are currently the most commonly used nanoparticles in consumer products, yet their environmental fate in natural waters is poorly understood. In the present study, we investigated the persistence, transformations and distribution of polyvinylpyrrolidone (PVP) and citrate (CT) coated AgNPs in boreal lake mesocosms dosed either with a 6-week chronic regimen or a one-time pulse treatment at environmentally relevant dosing levels. In the chronic treatments, total Ag (TAg) concentrations reached ∼40% of target concentrations by the end of the experiment, and in the pulsed mesocosms, TAg dissipated slowly, with a half-life of ∼20 days. Sediments and periphyton on the mesocosm walls were an important sink for Ag. We found little effect of AgNP loading and surface coating on the persistence of TAg. There were also no differences between treatments in the degree of agglomeration of AgNPs, as indicated by the accumulation and distribution of Ag in the particulate and colloidal fractions. The low ionic strength and relatively high dissolved organic carbon concentrations in the lake water likely contributed to the relative stability of AgNP in the water column. The low concentrations of dissolved Ag (<1 μg L(-1)) in the size fraction <3 kDaA reflect the importance of natural ligands in controlling the concentrations of Ag released by dissolution of AgNPs. Overall, these data indicate that AgNPs are relatively stable in the tested lake environment and appear to result in quantities of highly toxic ionic Ag(+) that are below our limit of detection.

Chronic sublethal exposure to silver nanoparticles disrupts thyroid hormone signaling during Xenopus laevis metamorphosis

Nanoparticles (NPs) are engineered in the nanoscale (<100 nm) to have unique physico-chemical properties from their bulk counterparts. Nanosilver particles (AgNPs) are the most prevalent NPs in consumer products due to their strong antimicrobial action. While AgNP toxicity at high concentrations has been thoroughly investigated, the sublethal effects at or below regulatory guidelines are relatively unknown. Amphibian metamorphosis is mediated by thyroid hormone (TH), and initial studies with bullfrogs (Rana catesbeiana) indicate that low concentrations of AgNPs disrupt TH-dependent responses in premetamorphic tadpole tailfin tissue. The present study examined the effects of low, non-lethal, environmentally-relevant AgNP concentrations (0.018, 0.18 or 1.8 μg/L Ag; ∼10 nm particle size) on naturally metamorphosing Xenopus laevis tadpoles in two-28 day chronic exposures beginning with either pre- or prometamorphic developmental stages. Asymmetric flow field flow fractionation with online inductively coupled plasma mass spectrometry and nanoparticle tracking analysis indicated a mixture of single AgNPs with homo-agglomerates in the exposure water with a significant portion (∼30-40%) found as dissolved Ag. Tadpoles bioaccumulated AgNPs and displayed transient alterations in snout/vent and hindlimb length with AgNP exposure. Using MAGEX microarray and quantitative real time polymerase chain reaction transcript analyses, AgNP-induced disruption of five TH-responsive targets was observed. The increased mRNA abundance of two peroxidase genes by AgNP exposure suggests the presence of reactive oxygen species even at low, environmentally-relevant concentrations. Furthermore, differential responsiveness to AgNPs was observed at each developmental stage. Therefore, low concentrations of AgNPs had developmental stage-specific endocrine disrupting effects during TH-dependent metamorphosis.

Analysis of drugs of abuse in wastewater from two Canadian cities

Several drugs of abuse, including amphetamines, cocaine and its metabolite, benzoylecgonine and several opioid prescription drugs were detected in wastewater from two Canadian cities, a small community (75,000 population) and a large urban center (1.6 million population). The objective of this study was to evaluate community use of these drugs in two cities with large differences in population size and demographics. In addition, we evaluated the use of the Polar Organic Chemical Integrative Sampler (POCIS) as a monitoring tool for drugs of abuse. Heroin was not detected at either location, probably because this illicit drug is metabolized to morphine prior to excretion. Acetylcodeine and acetylmorphine were also not detected. Estimates of community consumption from wastewater analysis indicated that the most widely used drug was cocaine at a median level of consumption in the larger city of approximately 38 doses per day per 1000 people. Consumption of the substituted amphetamine, ephedrine, as well as methamphetamine was also higher in the larger city, at 21 and 1.8 doses per day per 1000 people, respectively. Use of amphetamine, MDMA and tramadol were similar in both centers, but use of oxycodone was greater in the smaller city. Use of MDMA (ecstasy) peaked on weekends. Ketamine was detected in wastewater from the larger city; the first report of abuse of this veterinary anesthetic in a North American city. POCIS sampling rates were determined for the first time for 7 of the target compounds. Comparing the time weighted average concentrations estimated from POCIS data to the concentrations obtained from 24-h composite samples, the data were generally comparable, except for some compounds which were not detected in POCIS deployed in the untreated wastewater, probably because of biofouling or accumulation of debris on the cages containing the POCIS. This study indicates that the size and demographics of population centers can influence the patterns of abuse of drugs.

Removal of selected pharmaceuticals, personal care products and artificial sweetener in an aerated sewage lagoon

A sewage lagoon serving the small municipality of Lakefield in Ontario, Canada was monitored in the summer, fall and winter to determine removals of carbamazepine, trimethoprim, sulfamethoxazole, ibuprofen, gemfibrozil, triclosan, sucralose, HHCB and AHTN. Concentrations of these compounds in untreated and treated wastewater were estimated by deploying POCIS and SPMD passive samplers in the sewage lagoon. Passive samplers were also deployed at several points upstream and downstream of the point of discharge from the lagoon into the Otonabee River. LC-MS/MS and GC-MS were utilized to determine the concentrations of pharmaceuticals and personal care products (PPCPs) and sucralose, an artificial sweetener. Among PPCPs sampled by POCIS, the highest estimated concentration in untreated wastewater was ibuprofen sampled during the fall, at an estimated concentration of 60.3 ng/L. The estimated average concentration of sucralose was 13.6 ng/L in the untreated wastewaters. Triclosan, HHCB and AHTN in SPMDs were highest during fall season, at 30, 1677 and 109 ng/L, respectively. For all compounds except gemfibrozil, carbamazepine and sucralose, removals were highest in the summer (83.0 to 98.8%) relative to removals in the fall (48.4 to 91.4%) and winter (14.0 to 78.3%). Finally, the estimated concentrations of carbamazepine, sulfamethoxazole, triclosan and HHCB were compared with predicted values obtained through application of the WEST® modeling tool, with a new model based on the River Water Quality Model No. 1 and extended with dynamic mass balances describing the fate of chemicals of emerging concern subject to a variety of removal pathways. The model was able to adequately predict the fate of these four compounds in the lagoon in summer and winter, but the model overestimated removals of three of the four test compounds in the fall sampling period. This lagoon was as effective at removing PPCPs as many conventional WWTPs, but removals were better during the summer.

Interactive effects of silver nanoparticles and phosphorus on phytoplankton growth in natural waters

Increasing amounts of silver nanoparticles (AgNPs) are expected to enter the aquatic ecosystems where their effects on natural phytoplankton communities are poorly understood. We investigated the effects of AgNPs and its interactions with phosphorus (P) supply on the growth kinetics and stoichiometry of natural phytoplankton. Lake water was dosed with AgNPs (carboxy-functionalized capping agent; ∼10-nm particle size; ∼20% Ag w/w) at four different concentrations and five P concentrations and incubated in situ for 3 days. A treatment with ionic silver (AgNO3) was used as a positive control. We found that growth rates, calculated from changes in seston carbon and chlorophyll, responded significantly and interactively (p < 0.0001) to both AgNPs and P. AgNPs reduced the maximum phytoplankton growth rates by 11-85%. In the positive control, no or very little growth was observed. Inhibition of growth rates after exposure to Ag might be related to the reduction in chlorophyll and the inhibition of C and N acquisition rather than P uptake mechanisms. AgNPs, P supply and their interactions also significantly (p < 0.0001) reduced sestonic C:P and N:P ratios and increased C:N, C:Chl and cell-bound Ag stoichiometry. Our results indicate that fate and toxicity of AgNP will vary with phosphorus pollution level in aquatic ecosystems.