Assessing spatial impacts of historical pulp mill effluent on trophic dynamics in a coastal marine ecosystem using stable isotope (δ13C and δ15N) analysis

Boat Harbour, Nova Scotia was a tidal estuary that was converted into a wastewater treatment facility for pulp mill effluent in 1967. Treated effluent from Boat Harbour was discharged into the coastal Northumberland Strait, contributing significant nutrient and freshwater inputs into the coastal environment, potentially impacting local biogeochemistry and ecosystem structure. This study used stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) of representative taxa to assess spatial variability in nutrient sources and trophic dynamics. Results identified stable isotope variation with depleted δ13C and δ15N values in taxa near Boat Harbour. Blue mussel (Mytilus edulis) and mummichog (Fundulus heteroclitus) were the most suitable bioindicators for identifying variation in nutrient sources. Stable isotope signatures in this study may be reflective of residual pulp mill effluent-derived nutrients, differences in marine versus terrestrial nutrient sources, and a pronounced coastal salinity gradient. The present study defined the baseline nutrient conditions of the Northumberland Strait and will be useful in assessing the effectiveness of remediation activities.

Mechanistic Insights into Myofibrillar Protein Oxidation by Fenton Chemistry Regulated by Gallic Acid

Gallic acid (GA, 3,4,5-trihydroxybenzoic acid) is a widely used natural food additive of interest to food chemistry researchers, especially regarding its effects on myofibrillar protein (MP) oxidation. However, existing studies regarding MP oxidation by GA-combined with Fenton reagents are inconsistent, and the detailed mechanisms have not been fully elucidated. This work validated hydroxyl radical (HO·) as the primary oxidant for MP carbonylation; in addition, it revealed three functions of GA in the Fenton oxidation of MP. By coordination with Fe(III), GA reduces Fe(III) to generate Fe(II), which is the critical reagent for HO· generation; meanwhile, the coordination improves the availability and reactivity of Fe(III) under weakly acidic and near-neutral pH, i.e., pH 4-6. Second, the intermediates formed during GA oxidation, including semiquinone and quinone, promoted Fenton reactivity by accelerating Fe catalytic cycling. Finally, GA can scavenge HO· radicals, thus exhibiting a certain degree of antioxidant property. All three functions contribute to MP oxidation as observed in GA-containing meat.

Baseline monitoring of contaminant concentrations in American lobster (Homarus americanus) tissues from coastal Northumberland Strait, Nova Scotia, Canada

A baseline survey was conducted in 2018 to characterize contaminants in American lobsters, Homarus americanus in the Northumberland Strait, Canada. Sampling included three age classes of lobsters at sites 4, 20, and 70 km from the Boat Harbour estuary, a historically contaminated site set to undergo remediation. Lobster tissues were measured for metal(loids), methylmercury, polycyclic aromatic hydrocarbons, and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-p-furans. Contaminant concentrations were generally below the guidelines set by the Canadian Council of Ministers of the Environment and the Canadian Food Inspection Agency, except for arsenic which was elevated in all age classes from all sites (4.8-12.68 mg kg^-1). Mercury and methylmercury (both ~0.04 mg kg^-1) minimally exceeded one guideline in some age-classes and sites. There was also no consistent pattern of contaminant accumulation across either age classes or at particular sites. This study serves as a baseline for future monitoring following remediation of Boat Harbour.

A universal monoclonal antibody-aptamer conjugation strategy for selective non-invasive bioparticle isolation from blood on a regenerative microfluidic platform

Simultaneous isolation of various circulating tumor cell (CTC) subtypes from whole blood is useful in cancer diagnosis and prognosis. Microfluidic affinity separation devices are promising for CTC separation because of their high throughput capacity and automatability. However, current affinity agents, such as antibodies (mAbs) and aptamers (Apts) alone, are still suboptimal for efficient, consistent, and versatile cell analysis. By introducing a hybrid affinity agent, i.e., an aptamer-antibody (Apt-mAb) conjugate, we developed a universal and regenerative microchip with high efficiency and non-invasiveness in the separation and profiling of various CTCs from blood. The Apt-mAb conjugate consists of a monoclonal antibody that specifically binds the target cell receptor and a surface-bound aptamer that recognizes the conserved Fc region of the mAb. The aptamer then indirectly links the surface functionalization of the microfluidic channels to the mAbs. This hybrid affinity agent and the microchip platform may be widely useful for various bio-particle separations in different biological matrices. Further, the regeneration capability of the microchip improves data consistency between multiple uses and minimizes plastic waste while promoting environmental sustainability. STATEMENT OF SIGNIFICANCE: A hybrid affinity agent, Apt-mAb, consisting of a universal aptamer (Apt) that binds the conserved Fc region of monoclonal antibodies (mAbs) was developed. The invented nano-biomaterial combines the strengths and overcomes the weakness of both Apts and mAbs, thus changing the paradigm of affinity separation of cell subtypes. When Apt-mAb was used to fabricate microfluidic chips using a "universal screwdriver" approach, the microchip could be easily tuned to bind any cell type, exhibiting great universality. Besides high sensitivity and selectivity, the superior regenerative capacity of the microchips makes them reusable, which provides improved consistency and repeatability in cell profiling and opens a new approach towards in vitro diagnostic point-of-care testing devices with environmental sustainability and cost-effectiveness.

Exacerbated Protein Oxidation and Tyrosine Nitration through Nitrite-Enhanced Fenton Chemistry

Nitrite is a common additive used during meat curing to prevent microbial contamination and retain an attractive red color in the product. However, the effects of nitrite on Fenton reactions catalyzed by free iron in meat products are not well understood, although such processes can induce protein oxidation and nitration, affecting the nutritional and aesthetic quality of meat products. This contribution reveals the mechanism through which nitrite affects Fenton reactions that generate reactive nitrogen and oxygen species by increasing the availability of Fe³⁺, facilitating its reduction and stabilizing Fe²⁺, and accelerating Fe³⁺/Fe²⁺ cycling, leading to exacerbated oxidative and nitrosative stress on proteins, with implications not only for meat processing but also in many biological and environmental processes due to the ubiquitous presence of iron, hydrogen peroxide, and nitrite in nature.

Regenerative nanobots based on magnetic layered double hydroxide for azo dye removal and degradation

Azo dye removal and degradation protocol using magnetic LDH-based regenerative nanobots.

Chloride accelerated Fenton chemistry for the ultrasensitive and selective colorimetric detection of copper

A highly selective, ultrasensitive (visual and instrumental detection limits of 40 nM and 0.1 nM, respectively), environmentally-friendly, simple and rapid colorimetric sensor was developed for the detection of copper(II) in water. This sensor is based on a novel signal-amplification mechanism involving reactive halide species (RHSs) including chlorides or bromides, which accelerate copper Fenton reactions oxidizing the chromogenic substrate to develop colour. The results of this study expand our understanding of copper-based Fenton chemistry.

Chemisorption Mechanism of DNA on Mg/Fe Layered Double Hydroxide Nanoparticles: Insights into Engineering Effective SiRNA Delivery Systems

Layered double hydroxide nanoparticles (LDH NPs) have attracted interest as an effective gene delivery vehicle in biomedicine. Recent advances in clinic trials have demonstrated the efficacy of Mg/Fe LDHs for hyperphosphatemia treatment, but their feasibility for gene delivery has not been systematically evaluated. As a starting point, we aimed to study the interaction between oligo-DNA and Mg/Fe LDH NPs. Our investigation revealed the chemisorption mechanism of DNA on Mg/Fe LDH surfaces, wherein the phosphate backbone of the DNA polymer coordinates with the metal cations of the LDH lattice via the ligand-exchange process. This mechanistic insight may facilitate future gene delivery applications using Mg/Fe LDH NPs.

Adsorption of doxorubicin on citrate-capped gold nanoparticles: insights into engineering potent chemotherapeutic delivery systems

Gold nanomaterials have received great interest for their use in cancer theranostic applications over the past two decades. Many gold nanoparticle-based drug delivery system designs rely on adsorbed ligands such as DNA or cleavable linkers to load therapeutic cargo. The heightened research interest was recently demonstrated in the simple design of nanoparticle-drug conjugates wherein drug molecules are directly adsorbed onto the as-synthesized nanoparticle surface. The potent chemotherapeutic, doxorubicin often serves as a model drug for gold nanoparticle-based delivery platforms; however, the specific interaction facilitating adsorption in this system remains understudied. Here, for the first time, we propose empirical and theoretical evidence suggestive of the main adsorption process where (1) hydrophobic forces drive doxorubicin towards the gold nanoparticle surface before (2) cation-π interactions and gold-carbonyl coordination between the drug molecule and the cations on AuNP surface facilitate DOX adsorption. In addition, biologically relevant compounds, such as serum albumin and glutathione, were shown to enhance desorption of loaded drug molecules from AuNP at physiologically relevant concentrations, providing insight into the drug release and in vivo stability of such drug conjugates.

Robust Ag nanoplate ink for flexible electronics packaging

Nanoinks are currently a topic of heightened interest with respect to low temperature bonding processes and printable electronics. We have developed an innovative polyvinylpyrrolidone (PVP)-stabilized Ag nanoplate ink amenable to very strong low temperature packaging, and investigated the relationship between bonding strength and electrical conductivity post-bonding. PVP shell plastic deformations observed in failure microcracks with the formation of PVP nanofibers, revealed bonding strength at low temperatures (<250 °C) was primarily due to adhesive bonding. It is found that, utilizing photonic sintering, ∼ 70 °C reduction of transformation temperature from adhesive to metallic bonding was achieved compared to that of thermal sintering. A numerical simulation was developed to better understand the influences of the light-induced heat generation, which demonstrated near-infrared light can facilitate sintering. Bonding strengths of 27 MPa were achieved at room temperatures, and 29.4 MPa at 210 °C with photonic sintering. Moreover, the anisotropic resistivity was observed with different thermal dependences. These results demonstrate Ag nanoplate inks have potential for low temperature 3D interconnections in lead-free microcircuits, flexible electronic packaging, and diverse sensing applications.

Prevention of doxorubicin sorptive losses in drug delivery studies using polyethylene glycol

Polyethylene glycol enhances the accuracy of drug delivery system evaluations by preventing sorptive losses of hydrophobic drugs to plastic reaction vessels.

Direct writing on paper of foldable capacitive touch pads with silver nanowire inks

Paper-based capacitive touch pads can be fabricated utilizing high-concentration silver nanowire inks needle-printed directly onto paper substrates through a 2D programmable platform. Post deposition, silver nanowire tracks can be photonically sintered using a camera flash to reduce sheet resistance similar to thermal sintering approaches. Touch pad sensors on a variety of paper substrates can be achieved with optimized silver nanowire tracks. Rolling and folding trials, which yielded only modest changes in capacitance and no loss of function, coupled with touch pad functionality on curved surfaces, suggest sufficient flexibility and durability for paper substrate touch pads to be used in diverse applications. A simplified model to predict touch pad capacitance variation ranges with differing touch conditions was developed, with good agreement against experimental results. Such paper-based touch pads have the advantage of simple structure, easy fabrication, and fast sintering, which holds promise for numerous commercial applications including low-cost portable devices where ultrathin and lightweight features, coupled with reliable bending stability are desirable.

Occurrence and degree of intersex (testis-ova) in darters (Etheostoma SPP.) across an urban gradient in the Grand River, Ontario, Canada

The variability and extent of the intersex condition (oocytes in testes, or testis-ova) was documented in fish along an urban gradient in the Grand River, Ontario, Canada, that included major wastewater treatment plant outfalls. A method for rapid enumeration of testis-ova was developed and applied that increased the capacity to quantify intersex prevalence and severity. Male rainbow darters (Etheostoma caeruleum) sampled downstream of the first major wastewater outfall (Waterloo) had a significant increase, relative to 4 upstream reference sites, in the mean proportion of fish with at least 1 testis-oocyte per lobe of testes (9-20% proportion with ≤ 1 testis-oocyte/lobe vs 32-53% and >1.4 testis-oocyte/lobe). A much higher mean incidence of intersex proportion and degree was observed immediately downstream of the second wastewater outfall (Kitchener; 73-100% and 8-70 testis-oocyte/lobe); but only 6.3 km downstream of the Kitchener outfall, the occurrence of intersex dropped to those of the reference sites. In contrast, downstream of a tertiary treated wastewater outfall on a small tributary, intersex was similar to reference sites. Estrogenicity, measured using a yeast estrogen screen, followed a similar pattern, increasing from 0.81 ± 0.02 ng/L 17b-estradiol equivalents (EEq) (Guelph), to 4.32 ± 0.07 ng/L (Waterloo), and 16.99 ± 0.40 ng/L (Kitchener). Female rainbow darter downstream of the Kitchener outfall showed significant decreases in gonadosomatic index and liver somatic index, and increases in condition factor (k) relative to corresponding reference sites. The prevalence of intersex and alterations in somatic indices suggest that exposure to municipal wastewater effluent discharges can impact endocrine function, energy use, and energy storage in wild fish.

Fish community responses to multiple municipal wastewater inputs in a watershed

Municipalities utilize aquatic environments to assimilate their domestic effluent resulting in eutrophication, anoxia, toxicity and endocrine disruption of aquatic biota. The objective of this study was to assess the potential cumulative impacts of municipal wastewater effluent (MWWE) discharges in the Grand River on the health status of a sentinel species and the fish community downstream of 2 MWWE discharges. The fish communities downstream of the MWWE outfalls demonstrated differences in the abundance and diversity, species and family richness, % tolerance and % vulnerability when compared to the fish community upstream or further downstream of these points of effluent discharge. In both years studied, the fish community exposed to MWWE in the riffle-run habitats demonstrated reductions in the proportion of the most prominent fish (Rainbow Darter, Ethoestoma caeruleum) downstream of the outfalls, and a significant increase in the proportion of large mobile, tolerant-omnivorous fish species such as suckers and sunfish. There was less variability in the responses of the fish community to MWWE in the same season between years than between seasons within the same year. An examination of how impaired health of a sentinel species exposed to MWWE discharges parallels changes in the fish community is also conducted. This study successfully demonstrates the cumulative impact of urban development, including multiple outfalls of treated wastewater effluents on fish populations and communities. Municipalities are the major source of nutrients and pharmaceuticals and personal care products to aquatic systems, and they need to consider their impacts carefully with increasing urban population growth and ageing demographics.

Development and evaluation of a new in vivo solid-phase microextraction sampler

The use of solid-phase microextraction (SPME) as a nonlethal technique for in vivo sampling of pharmaceutical residue in fish tissue has been documented in the literature. However, there is need to improve its simplicity and robustness for wider applications in the laboratory and field. The objective of this research is to develop and improve the SPME device for sampling of pharmaceuticals in fish tissue. The practical application of the new device was demonstrated in the field where some wild fish (Esox masquinongy) were caught in the river and sampled by the device. The samples were analyzed using LC coupled with MS/MS (LC-MS/MS). The new in vivo SPME device with a PDMS extraction phase (sorbent) was demonstrated to a robust tool by both experts and nonexpert of the method and it is simpler than the traditional device. The detection limit of the method in gel and fish tissue was 0.01-0.26 ng/g. The interday reproducibility in gel and fish homogenized fish tissue was 8-16% RSD. This study demonstrates that the new device will provide a platform or opportunity for rapid sampling of carbamazepine, diazepam, and nordiazepam in fish muscle with acceptable precision.

Temporal changes in stress and tissue-specific metabolic responses to municipal wastewater effluent exposure in rainbow trout

Sub-chronic exposure to municipal wastewater effluent (MWWE) in situ was recently shown to impact the acute response to a secondary stressor in rainbow trout (Oncorhynchus mykiss). However, little is known about whether MWWE exposure in itself is stressful to the animal. To address this, we carried out a laboratory study to examine the organismal and cellular stress responses and tissue-specific metabolic capacity in trout exposed to MWWE. Juvenile rainbow trout were exposed to 0, 20 and 90% MWWE (from a tertiary wastewater treatment plant), that was replenished every 2d, for 14 d. Fish were sampled 2, 8 or 14 d post-exposure. Plasma cortisol, glucose and lactate levels were measured as indicators of organismal stress response, while inducible heat shock protein 70 (hsp70), constitutive heat shock protein 70 (hsc70) and hsp90 expression in the liver were used as markers of cellular stress response. Impact of MWWE on cortisol signaling was ascertained by determining glucocorticoid receptor protein (GR) expression in the liver, brain and, heart, and metabolic capacity was evaluated by measuring liver glycogen content and tissue-specific activities of key enzymes in intermediary metabolism. Plasma glucose and lactate levels were unaffected by exposure to MWWEs, whereas cortisol showed a transient increase in the 20% group at 8d. Liver hsc70 and hsp90, but not hsp70 expression, were higher in the 90% MWWE group after 8d. There was a temporal change in GR expression in the liver and heart, but not brain of trout exposed to MWWE. Liver glycogen content and activities liver gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK), and alanine aminotransferase (AlaAT) were significantly affected by MWWE exposure. The glycolytic enzymes pyruvate kinase (PK) and hexokinase (HK) activities were significantly higher temporally by MWWE exposure in the gill and heart, but not in the liver and brain. Overall, a 14 d exposure to MWWE evokes a cellular stress response and perturbs the cortisol stress response in rainbow trout. The tissue-specific temporal changes in the metabolic capacity suggest enhanced energy demand in fish exposed to MWWE, which may eventually lead to reduced fitness.

Determination of pharmaceutical residues in fish bile by solid-phase microextraction couple with liquid chromatography-tandem mass spectrometry (LC/MS/MS)

The present study investigates possible uptake and bioconcentration of different classes of pharmaceuticals residues (organic contaminants) in fish bile using a simplified analytical methodology based on solid phase microextration (SPME). The use of solid phase microextraction (SPME), as a simple analytical tool, to screen for target pharmaceuticals in fish bile samples was validated in rainbow trout (Oncorhynchus mykiss) following short-term laboratory exposures to carbamazepine and fluoxetine. While fish bioconcentrated both fluoxetine and carbamazepine from exposure water, fluoxetine accumulated to a greater degree in bile than carbamazepine. Good agreement was obtained for both analytes in bile samples between SPME and traditional liquid (solvent) extraction approaches (R(2) > 0.99). The field application of SPME sampling was further demonstrated in fathead minnow (Pimephales promelas), a small-bodied fish caged upstream and downstream of a local wastewater treatment plant where fluoxetine, atorvastatin, and sertraline were detected in fish bile at the downstream location. SPME is a promising analytical tool for investigating the bioconcentration of trace contaminants in fish bile, facilitating detection of trace environmental contaminants otherwise undetectable due to low concentrations in the environment and biological tissues as well as the complexity of the sample matrices.

Validation and use of in vivo solid phase micro-extraction (SPME) for the detection of emerging contaminants in fish

A variety of emerging chemicals of concern are released continuously to surface water through the municipal wastewater effluent discharges. The ability to rapidly determine bioaccumulation of these contaminants in exposed fish without sacrificing the animal (i.e. in vivo) would be of significant advantage to facilitate research, assessment and monitoring of their risk to the environment. In this study, an in vivo solid phase micro-extraction (SPME) approach was developed and applied to the measurement of a variety of emerging contaminants (carbamazepine, naproxen, diclofenac, gemfibrozil, bisphenol A, fluoxetine, ibuprofen and atrazine) in fish. Our results indicated in vivo SPME was a potential alternative extraction technique for quantitative determination of contaminants in lab exposures and as well after exposure to two municipal wastewater effluents (MWWE), with a major advantage over conventional techniques due to its ability to non-lethally sample tissues of living organisms.

Sampling-rate calibration for rapid and nonlethal monitoring of organic contaminants in fish muscle by solid-phase microextraction

Solid-phase microextraction (SPME) is a promising technique for determining organic contaminants within biotic systems. Existing in vivo SPME-kinetic calibration (SPME-KC) approaches are unwieldy due to the necessity of predetermining a distribution coefficient for the analyte of interest in the tissue and the preloading of a calibrating compound to the fiber. In this study, a rapid and convenient SPME alternative calibration method for in vivo analysis, termed SPME-sampling rate (SPME-SR) calibration, was developed and validated under both laboratory and field conditions to eliminate such presampling requirements. Briefly, the SPME probe is inserted into tissue, in this study fish dorsal-epaxial muscle, for 20 min allowing the concentrations of target analytes in the fish muscle to be determined by the extracted amount of analyte and the predetermined sampling rates. Atrazine, carbamazepine, and fluoxetine were detected nonlethally in the low ppb levels within fish muscle, with both laboratory and field-derived results obtained by in vivo SPME-KC comparable (within a factor of 1.27) to those obtained by lethal sampling followed by tissue liquid extraction. The technique described in this study represents an important advance which broadens the application of SPME in vivo sampling technology.

Solid-phase microextraction coupled to LC-ESI-MS/MS: evaluation and correction for matrix-induced ionization suppression/enhancement for pharmaceutical analysis in biological and environmental samples

Solid-phase microextraction (SPME) coupled to liquid chromatography with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) has been widely used to analyze biological fluids, tissues, and environmental matrixes for a variety of organic compounds including pharmaceuticals. However, effects of the sample matrix coextracted by SPME on tandem mass spectrometry analysis have not been systematically investigated. In this study, we characterized the complexity of matrix effects (ME) by analyzing SPME extracts of fish muscle and brain tissue, blood, and bile, as well as tap water, surface water, and the influent and effluent from a wastewater treatment plant. Significant enhancement or suppression of ionization (>15%) was observed with all biological and environmental samples. Intrasample ME variability was assessed through comparison of multiple samples from the same sample matrix, while intersample variability between different experimental subjects or varying sample treatment, storage, and sampling conditions were evaluated. To correct for ME, an isotopic internal standard (IIS) method was developed, with the strengths and limitations of the approach discussed. This study provides a framework for applying SPME within complex sample systems where the influences of ME are inevitable, thus ensuring more accurate quantitation of analytes during biological and environmental analysis.

The effects of tertiary treated municipal wastewater on fish communities of a small river tributary in Southern Ontario, Canada

Fish community changes associated with a tertiary treated municipal wastewater effluent outfall in the Speed River, Ontario, Canada, were evaluated at nine sites over two seasons (2008) using standardized electrofishing. Habitat evaluations were conducted to ensure that the riffle sites selected were physically similar. The fish community was dominated by several species of darters that differed in their response to the effluent outfall. There was a significant decrease in Greenside Darter (Etheostoma blennioides) but an increase in Rainbow Darter (E. caeruleum) abundance directly downstream of the outfall. Stable isotope signatures (δ(13)C and δ(15)N), which indicate shifts in energy utilization and flow, increased in Rainbow Darter downstream, but showed no change in Greenside Darter. Rainbow Darter may be exploiting a food source that is not as available at upstream sites giving them a competitive advantage over the Greenside Darter immediately downstream of the outfall.

Hydrothermal growth of free standing TiO2 nanowire membranes for photocatalytic degradation of pharmaceuticals

Highly entangled TiO(2) nanowires were directly synthesized by hydrothermal growth on Ti substrates at 180 °C utilizing various organic solvents to oxidize Ti. The growth mechanism, microstructure and phase transition of TiO(2) nanowire membranes were investigated in detail. TiO(2) nanowires, with diameters of 10-20 nm and lengths up to 100 μm, show a phase transition from Type-B to anatase by annealing at 700 °C. Robust, free standing TiO(2) nanowire membranes with millimeter level thickness can be cleaved from Ti substrates or directly prepared from thin Ti foils. These porous TiO(2) membranes, while effective for mechanical microfiltration, can also photocatalytically degrade pharmaceuticals such as trimethoprim under UV irradiation.

Fathead minnow (Pimephales promelas) reproduction is impaired in aged oil sands process-affected waters

Large volumes of fluid tailings are generated during the extraction of bitumen from oil sands. As part of their reclamation plan, oil sands operators in Alberta propose to transfer these fluid tailings to end pit lakes and, over time, these are expected to develop lake habitats with productive capabilities comparable to natural lakes in the region. This study evaluates the potential impact of various oil sands process-affected waters (OSPW) on the reproduction of adult fathead minnow (Pimephales promelas) under laboratory conditions. Two separate assays with aged OPSW (>15 years) from the experimental ponds at Syncrude Canada Ltd. showed that water containing high concentrations of naphthenic acids (NAs; >25 mg/l) and elevated conductivity (>2000 μS/cm) completely inhibited spawning of fathead minnows and reduced male secondary sexual characteristics. Measurement of plasma sex steroid levels showed that male fathead minnows had lower concentrations of testosterone and 11-ketotestosterone whereas females had lower concentrations of 17β-estradiol. In a third assay, fathead minnows were first acclimated to the higher salinity conditions typical of OSPW for several weeks and then exposed to aged OSPW from Suncor Energy Inc. (NAs ∼40 mg/l and conductivity ∼2000 μS/cm). Spawning was significantly reduced in fathead minnows held in this effluent and male fathead minnows had lower concentrations of testosterone and 11-ketotestosterone. Collectively, these studies demonstrate that aged OSPW has the potential to negatively affect the reproductive physiology of fathead minnows and suggest that aquatic habitats with high NAs concentrations (>25 mg/l) and conductivities (>2000 μS/cm) would not be conducive for successful fish reproduction.

Environmental risk assessment for the serotonin re-uptake inhibitor fluoxetine: Case study using the European risk assessment framework

The serotonin re-uptake inhibitor fluoxetine was selected for an environmental risk assessment, using the most recent European guideline (EMEA 2006) within the European Union (EU)-funded Environmental Risk Assessment of Pharmaceuticals (ERAPharm) project due to its environmental persistence, acute toxicity to nontarget organisms, and unique pharmacokinetics associated with a readily ionizable compound. As a widely prescribed psychotropic drug, fluoxetine is frequently detected in surface waters adjacent to urban areas because municipal wastewater effluents are the primary route of entry to aquatic environments. In Phase I of the assessment, the initial predicted environmental concentration of fluoxetine in surface water (initial PEC(SW)) reached or exceeded the action limit of 10 ng/L, when using both a default market penetration factor and prescription data for Sweden, Germany, and the United Kingdom. Consequently, a Phase II risk assessment was conducted in which green algae were identified as the most sensitive species with a NOEC of <0.6 microg/L. From this value, a predicted no effect concentration for surface waters (PNEC(SW)) of 0.012 microg/L was derived. The PEC/PNEC ratio was above the trigger value of 1 in worst-case exposure scenarios indicating a potential risk to the aquatic compartment. Similarly, risks of fluoxetine for sediment-dwelling organisms could not be excluded. No risk assessment was conducted for the terrestrial compartment due to a lack of data on effects of fluoxetine on soil organisms. The need for a separate risk assessment for the main metabolite of fluoxetine, norfluoxetine, was not conducted because of a lack of fate and effect studies. Based on published data, fluoxetine and norfluoxetine appeared to have a low to moderate bioaccumulation potential, which should be confirmed in formal studies according to OECD guidelines. Exposure assessments for fluoxetine according to the current framework rely heavily on K(OC) and K(OW) values. This approach is problematic, because fluoxetine is predominantly a cationic substance at environmental pH values. Consequently, the fate of fluoxetine (and other ionic substances) cannot be predicted using partition coefficients established for nonionic compounds. Further, published estimates for partition coefficients of fluoxetine vary, resulting in considerable uncertainties in both the exposure and environmental risk assessments of fluoxetine.

Tissue-specific in vivo bioconcentration of pharmaceuticals in rainbow trout (Oncorhynchus mykiss) using space-resolved solid-phase microextraction

The space-resolved solid-phase microextraction (SR-SPME) technique was employed to study the tissue-specific bioconcentration of pharmaceuticals in live fish. The segmented design of the SPME fibers allowed for the simultaneous determination of pharmaceutical residues in fish dorsal-epaxial muscle and adipose tissue with a single SPME fiber. The miniaturized fiber endowed the technique with high spatial resolution allowing for quantification of analytes within adjacent, relatively small tissues of immature rainbow trout. The pre-equilibrium sampling and kinetic calibration approach yielded efficient and accurate quantitation of pharmaceuticals in fish tissue. The ability of the SPME method to repeatedly sample the same fish circumvents problems arising from interanimal variation, thus improving the precision of generated bioconcentration kinetic profiles. In vivo monitoring with SR-SPME was validated with in vitro liquid extraction of tissue samples using methanol. Of the nine compounds evaluated, five (atrazine, gemfibrozil, carbamazepine, ibuprofen, and fluoxetine) bioconcentrated in adipose and muscle tissue over the eight exposure days. Although the accumulation of analytes in both tissues was positively correlated, each compound partitioned with differing affinities as modified by their hydrophobicity and unique molecular structure. Water samples analyzed using the SPME technique yielded results similar to those determined by solid-phase extraction (SPE); however, SPME was more rapid and operationally much simpler. This study illustrates the application conditions for in situ SR-SPME while demonstrating the potential of these miniaturized SPME fibers for simultaneous in vivo repeated sampling of multiple tissues.

Antidepressants and their metabolites in municipal wastewater, and downstream exposure in an urban watershed

Antidepressants are a widely prescribed group of pharmaceuticals that can be biotransformed in humans to biologically active metabolites. In the present study, the distribution of six antidepressants (venlafaxine, bupropion, fluoxetine, sertraline, citalopram, and paroxetine) and five of their metabolites was determined in a municipal wastewater treatment plant (WWTP) and at sites downstream of two WWTPs in the Grand River watershed in southern Ontario, Canada. Fathead minnows (Pimephales promelas) caged in the Grand River downstream of a WWTP were also evaluated for accumulated antidepressants. Finally, drinking water was analyzed from a treatment plant that takes its water from the Grand River 17 km downstream of a WWTP. In municipal wastewater, the antidepressant compounds present in the highest concentrations (i.e., >0.5 microg/L) were venlafaxine and its two demethylation products, O- and N-desmethyl venlafaxine. Removal rates of the target analytes in a WWTP were approximately 40%. These compounds persisted in river water samples collected at sites up to several kilometers downstream of discharges from WWTPs. Venlafaxine, citalopram, and sertraline, and demethylated metabolites were detected in fathead minnows caged 10 m below the discharge from a WWTP, but concentrations were all < microg/kg wet weight. Venlafaxine and bupropion were detected at very low (<0.005 microg/L) concentrations in untreated drinking water, but these compounds were not detected in treated drinking water. The present study illustrates that data are needed on the distribution in the aquatic environment of both the parent compound and the biologically active metabolites of pharmaceuticals.

Use of simultaneous dual-probe microdialysis for the determination of pesticide residues in a jade plant (Crassula ovata)

A microdialysis application for the sampling of plant pesticide residues has been developed utilizing two probes with differing perfusate rates simultaneously inserted into symmetric components of a sampling system. A simple empirical equation is proposed to calculate analyte concentrations in a semi-solid matrix using two different dialysate concentrations. In vitro application yielded excellent correlations between the calculated and spiked concentrations. Subsequent in vivo application of this technique for the determination of pesticide distributions in leaves of a jade plant (Crassula ovata) indicated the utility of this approach in complex living matrices.

Application of solid-phase microextraction for in vivo laboratory and field sampling of pharmaceuticals in fish

Previous field studies utilizing solid-phase microextraction (SPME) predominantly focused on volatile and semivolatile compounds in air or water. Earlier in vivo sampling studies utilizing SPME were limited to the liquid matrix (blood). The present study has expanded the SPME technique to semisolid tissues under laboratory and field conditions through the investigation of both theoretical and applied experimental approaches. Pre-equilibrium extraction and desorption were performed in vivo in two separate animals. Excellent linearity was found between the amounts extracted by SPME from the muscle of living fish and the waterborne concentrations of pharmaceuticals. A simple SPME method is also described to simultaneously determine free and total analyte concentrations in living tissue. The utility of in vivo SPME sampling was evaluated in wild fish collected from a number of different river locations under varying degrees of influence from municipal wastewater effluents. Diphenhydramine and diltiazem were detected in the muscle of fish downstream of a local wastewater treatment plant. Based on this study, SPME demonstrated several important advantages such as simplicity, sensitivity, and robustness under laboratory and in vivo field sampling conditions.

Short-term lab exposures of immature rainbow trout (Oncorhynchus mykiss) to sulfite and kraft pulp-mill effluents: effects on oxidative stress and circulating sex steroids

This study investigates the temporal onset of reactive oxygen species (ROS) damage and changes in circulating sex steroids in immature rainbow trout exposed over 21 d to two pulp-mill effluents. Exposure to effluent from a bleached sulfite mill produced increases in 2-thiobarbituric acid reactive substances (TBARS), ethoxyresorufin O-deethylase (EROD) activity, hepatic free iron, and significant depressions in hepatic ascorbic acid. Impairments in pregnenolone production relative to cholesterol availability suggest an effect of sulfite-mill effluent early in the steroidogenic pathway. Induction of vitellogenin in immature fish exposed to effluent from this mill, relative to waterborne 17 beta-estradiol treatments, indicated sulfite-mill effluent contained constituents capable of binding the estrogen receptor. Exposure to a kraft-mill effluent also elevated hepatic TBARS, tissue normalized fatty acyl-coenzyme A oxidase (FAO) activity, and hepatic free iron while producing commensurate declines in hepatic ascorbic acid. Plasma testosterone, 11-ketotestosterone, and 17 beta-estradiol were elevated with kraft-mill effluent exposure, but no changes in vitellogenin induction were observed. In summary, effluent from bleached sulfite and bleached kraft mills yielded similar oxidative stress responses, but marked differences were observed in the endocrine-disrupting potential of each effluent.

Short-term exposures of fish to perfluorooctane sulfonate: acute effects on fatty acyl-coa oxidase activity, oxidative stress, and circulating sex steroids

This study investigated the effects of exposure to waterborne perfluorooctane sulfonate (PFOS) on oxidative stress and reproductive endpoints in fish. Exposures utilized species commonly used in toxicological testing, including the fathead minnow (Pimephales promelas) and rainbow trout (Oncorhynchus mykiss), as well as relatively insensitive taxa such as creek chub (Semotilus atromaculatus), spottail shiner (Notropis hudsonius), and white sucker (Catostomus commersoni). In all fish species, short-term (14-28 d) exposure to PFOS produced only modest mortality at concentrations consistent with environmental spill scenarios. However, PFOS consistently increased hepatic fatty acyl-CoA oxidase activity and increased oxidative damage, as quantified using the 2-thiobarbituric acid-reactive substances assay. Plasma testosterone, 11-ketotestosterone, and 17beta-estradiol titers were often elevated with PFOS exposure. Vitellogenin, the egg yolk precursor protein, was occasionally altered in the plasma with PFOS exposure, but responses varied with maturity. Oviposition frequency and egg deposition in fathead minnow were not significantly impaired with PFOS exposure, despite a trend toward progressive impairment with increasing exposure concentrations. Although short-term PFOS exposure produced significant impacts on biochemical and reproductive endpoints in fish at concentrations consistent with environmental spills, the impact of long-term exposure to environmentally relevant concentrations of PFOS is unclear.

Oxidative stress and sex steroid levels in fish following short-term exposure to pulp-mill effluents

This study investigates the relationship between oxidative stress and reproductive dysfunction in wild white sucker (Catostomus commersoni) with short-term exposures to pulp-mill effluent. Hepatic oxidative damage, as quantified using 2-thiobarbituric acid-reactive substances (TBARS), was often increased with effluent exposure within 4-8 d, but responses varied by species, sex, and effluent. Fatty acyl-coenzyme A (CoA) oxidase (FAO) and ethoxyresorufin O-deethylase (EROD) activities were also significantly induced between 4 and 8 d of exposure. There were marked species differences in oxidative stress, as TBARS, FAO, and EROD responses in white sucker differed dramatically from those of longnose sucker (Catostomus catostomus) exposed under identical conditions. Exposure for 8 d to pulp-mill effluent delayed ovulation in white sucker, and these delays were independent of changes in circulating testosterone and 17alpha,20beta-dihydroxy-4-pregnen-3-one titers. Evaluations of the effects of pulp mill effluent on in vivo plasma steroid levels and in vitro steroidogenic capacities were compromised due to caging stress. In vivo preexposure to pulp-mill effluent did not reduce in vitro ovarian follicle steroidogenic capacities when exposed to additional reactive oxygen species (ROS) generators. Endocrine and oxidative stress parameters may be interrelated, as the in vivo administration of ferric nitrilotriacetate (Fe(3+)NTA) significantly reduced circulating sex steroids. Administration of a superactive GnRH analog containing a dopamine inhibitor significantly increased TBARS within 24 h, indicating endocrine status is capable of modifying oxidative stress responses. This study provides new knowledge regarding the onset of oxidative stress and changes in reproductive endpoints in fish following pulp-mill effluent exposure.

Impact of perfluorooctanoic acid on fathead minnow (Pimephales promelas) fatty acyl-CoA oxidase activity, circulating steroids, and reproduction in outdoor microcosms

This study investigates reproductive impairment and biochemical changes in fathead minnow (Pimephales promelas) exposed for 39 d to varying concentrations of perfluorooctanoic acid (PFOA) under microcosm conditions. While the concentrations tested in this study were much higher than those normally found in the environment, no mortality was associated with PFOA exposure. Only modest changes were observed in condition factor and in relative liver and gonad size. Significant declines in circulating plasma steroids were observed, but these were accompanied by only limited increases in time to first oviposition and decreases in overall egg production. Peroxisome proliferation, as quantified by fatty acyl-CoA oxidase (FAO) activity, was elevated with low PFOA concentrations but attenuated with exposure to higher PFOA doses. Little evidence was seen of differential induction of peroxisome-associated enzyme activity with sex. Oxidative stress, as quantified by the 2-thiobarbituric acid reactive substances (TBARS) assay, was only modestly influenced by PFOA exposure and is not a significant consequence of FAO activity in fathead minnow. Perfluorooctanoic acid appears to be relatively nontoxic at environmentally relevant concentrations but may impact biochemical and reproductive endpoints under conditions associated with environmental spills.

Oxidative stress responses in longnose sucker (Catostomus catostomus) exposed to pulp and paper mill and municipal sewage effluents

While recent evidence indicates that the generation of reactive oxygen species (ROS) and associated oxidative damage are frequently observed in fish populations with exposure to pulp and paper mill effluents, the potential for ROS generation from municipal sewage effluents has not been addressed. This study investigates the utility of measures of oxidative stress in delineating the effects of both pulp and paper mill and municipal sewage discharges. Longnose sucker (Catostomus catostomus) were collected below three pulp and paper mill and two municipal sewage effluent discharges over a 3-year period within the Wapiti and Athabasca River systems in northern Alberta. Biochemical responses in longnose sucker varied between the two rivers systems, with more pronounced changes occurring within the Wapiti River. Of the suite of biochemical parameters examined, fatty acyl-CoA oxidase (FAO) activity was the most sensitive indicator of pulp and paper mill exposure, but was only infrequently induced with exposure to municipal sewage effluent. Hepatic and gonadal 2-thiobarbituric acid reactive substances, lipid hydroperoxides, and hepatic free iron were less consistently elevated with exposure to pulp and paper mill effluent than FAO activity, and were also only infrequently altered with sewage effluent exposure. Hepatic ascorbic acid, liver somatic index, and condition factor were consistently altered with exposure to both sewage and pulp and paper mill effluents. While specific biochemical and organismal responses varied with effluents and time, the collective suite of oxidative stress endpoints proved to be useful tools in identifying relative influences of municipal sewage and pulp and paper mill effluent on fish populations in adjacent receiving waters.

Oxidative stress and bioindicators of reproductive function in pulp and paper mill effluent exposed white sucker

This study investigates oxidative stress and bioindicators of reproductive function in wild white sucker (Catostomus commersoni) collected from environments receiving pulp and paper mill effluent discharges in northern Ontario. Samples were collected over an eight-year period adjacent to three pulp and paper mills using a variety of processing and bleaching techniques. Fish collected downstream of pulp and paper mills within the Moose River basin exhibited elevated hepatic and gonadal 2-thiobarbituric acid reactive substances (TBARS), the presence of which is indicative of oxidative stress in these tissues. Within the Jackfish Bay system, exposure to pulp and paper mill effluent did not elevate hepatic or gonadal TBARS. Hepatic cytochrome P4501A activity (CYP1A) and fatty acyl-CoA oxidase (FAO) activities were frequently increased in livers of Moose River basin fish exposed to pulp and paper mill effluent, while lower activities of both enzymes were found within fish from the Jackfish Bay system. This suggests that oxidative stress may be related to CYP1A and FAO activities. Within the Moose River system, increases in measures of oxidative stress (TBARS, FAO) were generally coincident with decreased levels of 17 beta-estradiol; however, testosterone was often lower in Jackfish Bay system fish without any commensurate changes in oxidative stress. The suite of reproductive and oxidative stress parameters measured in this study varied between seasons and mills suggesting responses to effluent are dynamic and effects are complicated by different receiving environments. The relationship between gonad size, gonadal oxidative stress, and circulating plasma steroids remains unclear.

Utility of the TBARS assay in detecting oxidative stress in white sucker (Catostomus commersoni) populations exposed to pulp mill effluent

Recent evidence indicates that contaminant-stimulated free radical production and resulting oxidative damage may be an important mechanism of toxicity in organisms exposed to water-borne contaminants. This study tested the hypothesis that increases in oxidative stress and associated biochemical alterations would be present in white sucker (Catostomus commersoni) living in an environment receiving pulp mill effluent. Consistent increases in liver TBARS and frequent increases in gonadal TBARS were observed immediately downstream of the pulp mill effluent discharge; observable effects were attenuated with distance until they were not significantly different from reference values. Increases detected with the TBARS assay were commensurate with increases detected using the lipid hydroperoxides assay, a mechanistically independent technique. Fish exposed to pulp mill effluent also exhibited significant increases in hepatic free iron and ascorbic acid and a reduced free radical scavenging capacity in the livers of fish downstream of the effluent discharge relative to reference fish. Increases in oxidative stress are not necessarily dependent on increases in lipid substrate or related to reductions in ascorbic acid. TBARS values similar to those observed in fish resident below pulp mill effluent discharges were observed in white sucker 2 h after intraperitoneal injection using 15 mg/kg body weight ferric nitrilotriacetate (Fe(3+) NTA) as a positive control. This study indicates oxidative stress could be a mechanism of toxicity in fish exposed to pulp mill effluent and demonstrates the utility of TBARS in delineating zones of exposure to pulp mill effluent.