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Hydraulic fracturing is an industrial process allowing for the extraction of gas or oil. To fracture the rocks, a proprietary mix of chemicals is injected under high pressure, which later returns to the surface as flowback and produced water (FPW). FPW is a complex chemical mixture consisting of trace metals, organic compounds, and often, high levels of salts. FPW toxicity to the model freshwater crustacean Daphnia magna was characterized utilizing acute (48 h median lethal concentrations; LC50) and chronic (21 day) exposures. A decrease in reproduction was observed, with a mean value of 18.5 neonates produced per replicate over a 21 day chronic exposure to 0.04% FPW, which was a significant decrease from the average of 64 neonates produced in the controls. The time to first brood was delayed in the highest FPW (0.04%) treatment. Neonates exhibited an LC50 of 0.19% of full-strength FPW, making them more sensitive than adults, which displayed an LC50 value of 0.75%. Quantitative PCR highlighted significant changes in expression of genes encoding xenobiotic metabolism (cyp4) and moulting (cut). This study is the first to characterize chronic FPW toxicity and will help with the development of environmental monitoring and risk assessment of FPW spills. [ABSTRACT FROM AUTHOR]

We describe a novel method for measuring stable bromine isotope compositions in saline solutions such as seawater, brines, and formation waters. Bromine is extracted from the samples by ion exchange chromatography on anion exchange resin AG 1-X4 with NH4NO3 and measured by MC-ICP-MS in wet plasma conditions. Sample introduction through a small spray chamber provided good sensitivity and stability of the Br signal compared to direct injection (d-DIHEN) and desolvation (APEX). NH4NO3 media allowed fast (<3 min) washing of the system. Despite Ar2H+ spectral interference on 81Br+, for the first time low-resolution mode (with appropriate tuning of Ar2H+/81Br+ sensitivity) gave higher precision 81Br/79Br measurements than high-resolution (HR), due to the narrowness of the 81Br+ plateau in HR mode and to slight mass drifting with time. Additionally, 1 μg Br is the lower amount needed for a triplicate determination of δ81Br by MC-ICP-MS, with reproducibility often < ± 0.1‰ (2 SD). Four HBr solutions were prepared by evaporation/condensation in order to obtain in-house reference solutions with 3‰ variations in δ81Br and to assess the reproducibility and accuracy of the method. Long-term (>3 years) reproducibility between ± 0.11 and ± 0.27‰ (2 SD) was obtained for the four HBr solutions, the international standard reference material NIST SRM 977 (δ81BrSMOB = -0.65 ± 1.1‰, 1 SD), and seawaters (synthetic and natural). The accuracy of the MC-ICP-MS method was validated by comparing the δ81Br obtained for these solutions with dual-inlet IRMS measurements on CH3Br gas. Finally, the method was successfully applied to 22 natural samples. [ABSTRACT FROM AUTHOR]

The effect of pH on the extent and type of dissolved components in synthetic produced water samples prepared from seven crude oils was investigated. More nitrogen containing compounds, probably due to improved water solubility of pyridinic nitrogen functionalities, were seen at the low pH. The affinity of the water-soluble compounds for air-water interfaces was in most cases higher at higher pH. This was due to increased oxygen content in the water-soluble species, probably associated with carboxylic acid functionalities. Differences in the affinity of water-soluble crude oil components to gas bubbles are anticipated to influence the oil removal efficiency by gas flotation. The dynamic interfacial adsorption was followed by a maximum bubble pressure tensiometer, while the dissolved species were characterized by total organic carbon measurements, total nitrogen measurements, FT-IR spectroscopy, and UV/vis spectroscopy. [ABSTRACT FROM AUTHOR]

The densities of CO2 solution of the brine from Teikoku Oil Field located at Niigata Prefecture in Japan are measured by a magnetic suspension balance at temperatures from 303.15 to 323.15 K, pressures from 10 to 20 MPa, and CO2 mole fractions of 0, 0.0038, 0.0040, 0.0087, 0.0100, and 0.0160. Results show that the densities of CO2-brine solution increase to 0.86% from that of brine and linearly increases with pressure at a gradient of 0.411 kg·m-3·MPa-1 and with CO2 mole fraction at an average gradient of 514 kg·m-3·mol-1 at a temperature of 303.15 K. On the other hand, the density of CO2-brine solution decreases with increasing temperature at an average rate of -0.377 kg·m-3·K-1 under our experimental conditions. The ePC-PSAFT model is applied to predict the data obtained from this study and those from literature. It is demonstrated that the model works well with average relative deviation (ARD) of 0.27%. A correlation of density ratio of CO2-brine solution to brine is provided and validated by data used in the ePC-PSAFT model, which is convenient for engineering application in comparison with that by the ePC-PSAFT. The ARDs for density ratio predicted by ePC-PSAFT and correlation are 0.075% and 0.019% for this work, respectively. [ABSTRACT FROM AUTHOR]

The densities of CO2 solution of the brine from Teikoku Oil Field located at Niigata Prefecture in Japan are measured by a magnetic suspension balance at temperatures from 303.15 to 323.15 K, pressures from 10 to 20 MPa, and CO2 mole fractions of 0, 0.0038, 0.0040, 0.0087, 0.0100, and 0.0160. Results show that the densities of CO2-brine solution increase to 0.86% from that of brine and linearly increases with pressure at a gradient of 0.411 kg•m-3•MPa-1 and with CO2 mole fraction at an average gradient of 514 kg•m-3•mol-1 at a temperature of 303.15 K. On the other hand, the density of CO2-brine solution decreases with increasing temperature at an average rate of -0.377 kg•m-3•K-1 under our experimental conditions. The ePC-PSAFT model is applied to predict the data obtained from this study and those from literature. It is demonstrated that the model works well with average relative deviation (ARD) of 0.27%. A correlation of density ratio of CO2-brine solution to brine is provided and validated by data used in the ePC-PSAFT model, which is convenient for engineering application in comparison with that by the ePC-PSAFT. The ARDs for density ratio predicted by ePC-PSAFT and correlation are 0.075% and 0.019% for this work, respectively. [ABSTRACT FROM AUTHOR]

Microbial activity during the holding and reuse of wastewater from hydraulic fracturing operations, termed produced water, may lead to issues with corrosion, sulfide release, and fouling. Biocides are applied to control biological activity, often with limited efficacy, which is typically attributed to chemical interactions with the produced water. However, it is unknown whether there is a biologically driven mechanism to biocide tolerance in produced water. Here, we demonstrate that produced water exposure results in an enhanced tolerance against the typically used biocide glutaraldehyde and increased susceptibility to the oxidative biocide hypochlorite in a native and a model bacteria and that this altered resistance is due to the salinity of the produced water. In addition, we elucidate the genetic response of the model organism Pseudomonas fluorescens to produced water exposure to provide a mechanistic interpretation of the altered biocide resistance. The RNA-seq data demonstrated the induction of genes involved in osmotic stress, energy production and conversion, membrane integrity, and protein transport following produced water exposure, which facilitates bacterial survival and alters biocide tolerance. Efforts to fundamentally understand biocide resistance mechanisms, which enable the optimization of biocide application, hold significant implications for greening of the fracturing process through encouraging produced water recycling. Specifically, these results suggest the necessity of optimizing biocide application at the level of individual shale plays, rather than historical experience, based upon produced water characteristics and salinity. [ABSTRACT FROM AUTHOR]

Particles were recovered from offshoreproduced water and analyzedin terms of chemical composition, surface properties, and suspensionstability. The recovered particles were identified to be iron (FeIIFeIIIOx(OH)y) aluminosilicate covered with an organic layer.Both the chemical composition and surface properties were alteredupon calcination. Destabilization of suspensions occurred throughsedimentation and aggregation of particles. Increased temperatureenhanced the destabilization of the investigated suspensions, whilethe organic layer surrounding the particles and the dissolved componentsin the produced water slowed it down. [ABSTRACT FROM AUTHOR]

A matrixof 18 synthetic produced water samples was analyzed bypartial least-squares (PLS) regression modeling. This has been doneto investigate the correlation between crude oil properties and watersolubility and affinity of the dissolved hydrocarbons for air/waterinterface which is referred to as produced water quality. The syntheticproduced water samples were prepared with nine crude oils and twoaqueous phases in the presence and absence of divalent cations (Ca2+, Mg2+). The total organic carbon content anddynamic surface tension was determined for the samples. The findingsof the PLS modeling are summarized as follows: produced water qualitywas not correlated to the amount (wt %) of aromatics, resins, andasphaltenes in the crude oils but with the amount (wt %) of heteroatomspresent in the different fractions. The water solubility and affinityfor air/water interfaces of the crude oil hydrocarbons was promotedby oxygen-containing compounds and reduced by nitrogen- and sulfur-containingcompounds. Heteroatom-containing molecules of similar class originatingfrom aromatic, resin, and asphaltene fractions of crude oils contributedto different degrees of water solubility and affinity for adsorptionat air–water interfaces. This can be related to the differencesin the molecular structures of the compounds. Furthermore, the presenceof divalent cations showed more influence on the quality of producedwater samples of crude oils with high total acid number and nitrogencontent. [ABSTRACT FROM AUTHOR]

In the rapidly developing shale gas industry, managing produced water is a major challenge for maintaining the profitability of shale gas extraction while protecting public health and the environment. We review the current state of practice for produced water management across the United States and discuss the interrelated regulatory, infrastructure, and economic drivers for produced water reuse. Within this framework, we examine the Marcellus shale play, a region in the eastern United States where produced water is currently reused without desalination. In the Marcellus region, and in other shale plays worldwide with similar constraints, contraction of current reuse opportunities within the shale gas industry and growing restrictions on produced water disposal will provide strong incentives for produced water desalination for reuse outside the industry. The most challenging scenarios for the selection of desalination for reuse over other management strategies will be those involving high-salinity produced water, which must be desalinated with thermal separation processes. We explore desalination technologies for treatment of high-salinity shale gas produced water, and we critically review mechanical vapor compression (MVC), membrane distillation (MD), and forward osmosis (FO) as the technologies best suited for desalination of high-salinity produced water for reuse outside the shale gas industry. The advantages and challenges of applying MVC, MD, and FO technologies to produced water desalination are discussed, and directions for future research and development are identified. We find that desalination for reuse of produced water is technically feasible and can be economically relevant. However, because produced water management is primarily an economic decision, expanding desalination for reuse is dependent on process and material improvements to reduce capital and operating costs. [ABSTRACT FROM AUTHOR]

The exponential increase in fossil energy production from Devonian-age shale in the Northeastern United States has highlighted the management challenges for produced waters from hydraulically fractured wells. Confounding these challenges is a scant availability of critical water quality parameters for this wastewater. Chemical analyses of 160 flowback and produced water samples collected from hydraulically fractured Marcellus Shale gas wells in Pennsylvania were correlated with spatial and temporal information to reveal underlying trends. Chloride was used as a reference for the comparison as its concentration varies with time of contact with the shale. Most major cations (i.e., Ca, Mg, Sr) were well-correlated with chloride concentration while barium exhibited strong influence of geographic location (i.e., higher levels in the northeast than in southwest). Comparisons against brines from adjacent formations provide insight into the origin of salinity in produced waters from Marcellus Shale. Major cations exhibited variations that cannot be explained by simple dilution of existing formation brine with the fracturing fluid, especially during the early flowback water production when the composition of the fracturing fluid and solid-liquid interactions influence the quality of the produced water. Water quality analysis in this study may help guide water management strategies for development of unconventional gas resources. [ABSTRACT FROM AUTHOR]

Produced water is the contaminated water that is brought to the surface in the process of recovering oil and gas. On the basis of discharge volume, this type of contaminated water is the largest contributor to the offshore waste stream. Modeling studies of large amounts of wastewater discharge into offshore areas have helped in the understanding of pollutant dispersion behaviors in marine environments and in further evaluating the potential environmental effects resulting from produced water discharges. This study presents an integrated three-dimensional (3D) approach for the simulation of produced water discharges in offshore areas. Specifically, an explicit second-order finite difference method was used to model the far-field pollutant dispersion behavior, and this method was coupled with the jet-plume model JETLAG with an extension of the 3D cross-flow conditions to simulate the near-field mixing processes. A dynamic coupling technique with full consideration of the interaction between the discharged fluids and receiving waters was employed in the model. A case study was conducted on the Grand Banks of Newfoundland, Canada. The field validation of the modeling results was conducted for both the near-field and far-field dispersion processes, and the modeling results were in good agreement with the field observations. This study provides an integrated system tool for the simulation of complex transport processes in offshore areas, and the results from such modeling systems can be further used for the risk assessment analysis of the surface water environment. [ABSTRACT FROM AUTHOR]

A systematic technique has been developed to determineantiscalingefficiency and dissolution capacity for calcium carbonate in oilfieldbrines under various ultrasonic treating conditions. During the staticexperiments, effects of ultrasonic frequency, acoustic intensity,treating time, and water level on the antiscaling efficiency havebeen evaluated, while the underlying antiscaling mechanism is identifiedand determined. Physically, the formation of calcium carbonate ispromoted as a result of the decreased molecular force and acceleratedmovement of salty ions under ultrasonic irradiation. Most of the formedscale is found to loosely suspend in the liquid, rather than tightlyadhere to the solid surface. During the dynamic experiments, orthogonaltests have been designed to examine effects of interval time, treatingtime, and flow velocity on antiscaling efficiency. As for the dissolutionexperiment, dissolution capacity is measured to evaluate the effectof ultrasonic frequency on dissolution of the formed calcium carbonate.The antiscaling efficiency is found to achieve its maximum value of81.1%, using the ultrasonic treatment with a frequency of 28 kHz,an acoustic intensity of 0.61 W/cm2, an interval time of2 h, a treatment time of 15 min, and a flow velocity of 1.8 m/s. Itis also found that dissolution capacity does not impose a dominanteffect on scale prevention and that the highest dissolution capacityof 19.3% is obtained with an ultrasonic frequency of 28 kHz. [ABSTRACT FROM AUTHOR]

Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters with other waters in the Appalachian Basin in the event of an accidental release, and to provide information about the source of the dissolved solids. Strontium isotopic ratios of Marcellus produced waters collected over a geographic range of ∼375 km from southwestern to northeastern Pennsylvania define a relatively narrow set of values (ϵSWSr = +13.8 to +41.6, where ϵSWSr is the deviation of the 87Sr/86Sr ratio from that of seawater in parts per 104); this isotopic range falls above that of Middle Devonian seawater, and is distinct from most western Pennsylvania acid mine drainage and Upper Devonian Venango Group oil and gas brines. The uniformity of the isotope ratios suggests a basin-wide source of dissolved solids with a component that is more radiogenic than seawater. Mixing models indicate that Sr isotope ratios can be used to sensitively differentiate between Marcellus Formation produced water and other potential sources of TDS into ground or surface waters. [ABSTRACT FROM AUTHOR]

The solubility of five groups of natural gas in reservoir formation water was measured under (333.2 to 393.2) K and (15.0 to 43.6) MPa. The formation water and corresponding natural gas were sampled in situ from a China oilfield. The range of total dissolved solids (TDS) of the reservoir formation water samples is from (8744 to 80634) mg·kg−1. The mole fraction of methane in natural gas ranges from 0.7575 to 0.9449. The experimental results show that, with the increase of temperature and pressure, the solubility of natural gas in formation water goes through a minimum value under the experimental conditions. The solubility of natural gas in formation water was also influenced by a composition of gas phase and TDS of liquid phase. The salt effect becomes more significant in the high-pressure region. [ABSTRACT FROM AUTHOR]

A water treatment approach combining ultrafiltration (UF) and micellar-enhanced ultrafiltration (MEUF) techniques was used for the removal of organic contaminants in field produced water samples from Canada and the United States. Free oil droplets and suspended solids were separated by initial UF treatments while MEUF was necessary for the removal of dissolved organics. It was shown that the amphiphilic characteristics of some organics commonly existing in produced water contributed to lowering the critical micelle concentration (CMC) of the surfactant employed. Lower surfactant concentrations could, therefore, be employed leading to lower fouling and back contamination and higher permeate flux. In addition, the incorporation of organic contaminants into the structure of cetylpyridinium chloride (CPC) micelles resulted in larger size and higher dissolution capacity of the "mixed micelles". The performance of polymeric and ceramic membranes of different molecular weight cutoffs (MWCOs) was evaluated by analyzing the permeate flux, recovery ratio, and solute percent rejection as functions of trans-membrane pressure (TMP). A mathematical model based on Darcy's law and the resistance in-series model successfully described the flux decline as a function of TMP for the two field samples and the two membranes studied. [ABSTRACT FROM AUTHOR]

Produced water from offshore oil production platforms represents the largest direct discharge of effluent into the offshore environment. Produced water effluents contain a complex mixture of substances which are known to bind to the estrogen receptor (ER) and antagonize the androgen receptor (AR). Short-chain petrogenic alkylphenoln have been identified as responsible for around 35% of the ER agonist activity measured in vitro while the compounds responsible for antagonizing the androgen receptor are unknown. For the first time we report that petrogenic naphthenic acids are weak ER agonists that account for much of the 65% of the "unknown" ER agonist potency in North Sea produced waters while also disrupting the binding of AR agonists to the AR ligand receptor. We also report other known petrogenic components such as polycyclic aromatic hydrocarbons (PAHs) and alkylphenols as environmental AR antagonists. Our investigation shows that these petrogenic components are responsible for the majority of the ER and AR receptor mediated activity in produced waters. This hypothesis is supported by data from an effects-directed analysis of produced water using normal-phase high-performance liquid chromatography (HPLC) fractionation in combination with the yeast estrogen and androgen assays as well as androgen receptor binding assays of commercially available mixtures of naphthenic acids. [ABSTRACT FROM AUTHOR]

Large discharges from oil and gas production platforms (produced water) have led to concerns for adverse biological effects in marine areas. The aim of this study was to investigate the development of DNA adduct formation and related biomarkers in fish after chronic exposure to water-soluble components of oil. Atlantic cod (Gadus morhua) were exposed for up to 44 weeks to three treatments (low, pulsed, high) containing environmentally relevant concentration of low-molecular-weight polycyclic aromatic hydrocarbons (PAHs) and short- chained alkylphenols (APs). A time- and dose-related pattern of DNA adduct formation (measured using 32P-postlabeling) was observed. The results suggested that an extended exposure period (more than 16 weeks) would be required for the formation of DNA adduct levels above background. Interestingly, fish receiving pulsed high exposure did not develop elevated concentrations of DNA adducts, possibly due to DNA repair processes. No obvious relationship between DNA adduct concentration and cytochrome P4501A activity (EROD) was observed. This study has demonstrated the genotoxic potential of water-soluble oil components, relevant for operational discharges (produced water) and chronic oil spills. The quantification of PAH metabolites in bile and hepatic DNA adduct formation appear to be suitable for environmental monitoring of chronic oil pollution. [ABSTRACT FROM AUTHOR]

Fields from which oil is produced by injection of sulfate-bearing water often exhibit an increase in sulfide concentration with time (souring). Nitrate added to the injection water lowers the sulfide concentration by the action of sulfide-oxidizing, nitrate-reducing bacteria (SO-NRB). However, the injected nitrate can also be reduced with oil organics by heterotrophic NRB (hNRB). Aqueous volatile fatty acids (VFAs; a mixture of acetate, propionate, and butyrate) are considered important electron donors in this regard. Injection and produced waters from a western Canadian oil field with a low in situ reservoir temperature (30 °C) had only 0.1-0.2 mM VFAs. Amendment of these waters with nitrate gave therefore only partial reduction. More nitrate was reduced when 2% (v/v) oil was added, with light oil giving more reduction than heavy oil. GC-MS analysis of in vitro degraded oils and electron balance considerations indicated that toluene served as the primary electron donor for nitrate reduction. The differences in the extent of nitrate reduction were thus related to the toluene content of the light and heavy oil (30 and 5 mM, respectively). Reduction of nitrate with sulfide by SO-NRB always preceded thatwith oil organics by hNRB, even though microbially catalyzed kinetics with either electron donor were similar. Inhibition of hNRB by sulfide is responsible for this phenomenon. Injected nitrate will thus initially be reduced with sulfide through the action of SO-NRB. However, once sulfide has been eliminated from the near-injection welibore region, oil organics will be targeted by the action of hNRB. Hence, despite the kinetic advantage of SO-NRB, the nitrate dose required to eliminate sulfide from a reservoir depends on the concentration of hNRB-degradable oil organics, with toluene being the most important in the field under study. Because the toluene concentration is lower in heavy oil than in light oil, nitrate injection into a heavy-oil-producing field of low temperature is more likely to succeed in containing souring. [ABSTRACT FROM AUTHOR]

Coal bed natural gas (CBNG) produced water is usually disposed into nearby constructed disposal ponds. Geochemistry of produced water, particularly trace elements interacting with a semiarid environment, is not clearly understood. The objective of this study was to collect produced water samples at outfalls and corresponding disposal ponds and monitor pH, iron (Fe), aluminum (Al), chromium (Cr), manganese (Mn), lead (Pb), copper (Cu), zinc (Zn), arsenic (As), boron (B), selenium (Se), molybdenum (Mo), cadmium (Cd), and barium (Ba). Outfalls and corresponding disposal ponds were sampled from five different watersheds including Cheyenne River (CHR), Belle Fourche River (BFR), Little Powder River (LPR), Powder River (PR), and Tongue River (TR) within the Powder River Basin (PRB), Wyoming from 2003 to 2005. Paired t-tests were conducted between CBNG outfalls and corresponding disposal ponds for each watershed. Results suggest that produced water from CBNG outfalls is chemically different from the produced water from corresponding disposal ponds. Most trace metal concentrations in the produced water increased from outfall to disposal pond except for Ba. In disposal ponds, Ba, As, and B concentrations increased from 2003 to 2005. Geochemical modeling predicted precipitation and dissolution reactions as controlling processes for Al, Cu, and Ba concentrations in CBNG produced water. Adsorption and desorption reactions appear to control As, Mo, and B concentrations in CBNG water in disposal ponds. Overall, results of this study will be important to determine beneficial uses (e.g., irrigation, livestock/wildlife water, and aquatic life) for CBNG produced water in the PRB, Wyoming. [ABSTRACT FROM AUTHOR]

Injection of carbon dioxide into depleted oil fields or deep saline aquifers represents one of the most promising means of long-term storage of this greenhouse gas. While the ultimate goal of CO2 injection in the subsurface is mineral storage of CO2 as carbonates, short-term (<50 year) storage of injected CO2 is most likely to be accomplished by ionic trapping of CO2 as bicarbonate ions (HCO3-) and hydrogeological trapping of molecular CO2. Here, we demonstrate a technique for quantifying ionic trapping of injected CO2 as HCO3- using geochemical data collected prior to and during 40 months of CO2 injection into a hydrocarbon reservoir at the International Energy Agency (IEA) Weyburn CO2 Monitoring and Storage Project, Saskatchewan, Canada. As a result of injection of CO2 with a low carbon isotope ratio (°13C value), fluid and gas samples from four selected production wells showed an increase in HCO3- concentration and a decrease in °13C values of HCO3- and CO2 over the observation period. Isotope and mass balance calculations indicate that, after 40 months of injection, ∼80% of the HCO3- in the reservoir brines sampled from the four wells formed via dissolution and dissociation of injected CO2. This chemical and isotopic technique should be applicable to CO2 injection and storage in oil fields and in deep saline aquifers, provided there is sufficient carbon isotopic distinction between injected CO2 and baseline aquifer HCO3- and CO2. [ABSTRACT FROM AUTHOR]

The effects of hydraulic fracturing (HF) flowback and produced water (HF-FPW), a complex saline mixture of injected HF fluids and deep formation water that return to the surface, was examined in rainbow trout (Oncorhynchus mykiss). Exposure to HF-FPWs resulted in significant induction of ethoxyresorufin-O-deethylase (EROD) activity in both liver and gill tissues. Increased lipid peroxidation via oxidative stress was also detected by thiobarbituric acid reactive substances (TBARS) assay. The mRNA expressions of a battery of genes related to biotransformation, oxidative stress, and endocrine disruption were also measured using quantitative real-time polymerase chain reaction (Q-RT-PCR). The increased expression of cyp1a (2.49 ± 0.28-fold), udpgt (2.01 ± 0.31-fold), sod (1.67 ± 0.09-fold), and gpx (1.58 ± 0.10-fold) in raw sample exposure group (7.5%) indicated elevated metabolic enzyme activity, likely through the aryl hydrocarbon receptor pathway, and generation of reactive oxygen species. In addition, the elevated vtg and era2 expression demonstrated endocrine disrupting potential exerted by HF-FPW in rainbow trout. The overall results suggested HF-FPW could cause significant adverse effects on fish, and the organic contents might play the major role in its toxicity. Future studies are needed to help fully determine the toxic mechanism(s) of HF-FPW on freshwater fish, and aid in establishing monitoring, treatment, and remediation protocols for HF-FPW. [ABSTRACT FROM AUTHOR]