Persistent and transgenerational effects of raw and ozonated oil sands process-affected water exposure on a model vertebrate, the zebrafish

Sample preparation, analytical characterization, monitoring, risk assessment and treatment of naphthenic acids in industrial wastewater and surrounding water impacted by unconventional petroleum production

Industrial extraction of unconventional petroleum results in notable volumes of oil sands process water (OSPW), containing elevated concentrations of naphthenic acids (NAs). The presence of NAs represents an intricate amalgamation of dissolved organic constituents, thereby presenting a notable hurdle for the domain of environmental analytical chemistry. There is growing concern about monitoring the potential seepage of OSPW NAs into nearby groundwater and river water. This review summarizes recent studies on sample preparation, characterization, monitoring, risk assessment, and treatment of NAs in industrial wastewater and surrounding water. Sample preparation approaches, such as liquid-liquid extraction, solid phase microextraction, and solid phase extraction, are crucial in isolating chemical standards, performing molecular level analysis, assessing aquatic toxicity, monitoring, and treating OSPW. Instrument techniques for NAs analysis were reviewed to cover different injection modes, ionization sources, and mass analyzers. Recent studies of transfer and transformation of NAs provide insights to differentiate between anthropogenic and natural bitumen-derived sources of NAs. In addition, related risk assessment and treatment studies were also present for elucidation of environmental implication and reclamation strategies. The synthesis of the current state of scientific knowledge presented in this review targets government regulators, academic researchers, and industrial scientists with interests spanning analytical chemistry, toxicology, and wastewater management.

A latest progress in the study of fish behavior: cross-generational effects of behavior under pollution pressure and new technologies for behavior monitoring

With the development of agriculture and industry, an increasing number of pollutants are being discharged into the aquatic environment. These pollutants can harm aquatic life. The behavioral characteristics of animals are an external manifestation of their internal mechanisms. Changes in behavior reflect damage and changes in the internal mechanisms. Environmental pollution may lead to behavioral changes not only in the parental generation but also in the offspring that has not been exposed to the pollutants. That is, the intrinsic mechanism that leads to behavioral changes is inheritable. Fish are representative species of aquatic organisms and are commonly used in various research studies. The behavior of fish has also received extensive attention, and the monitoring technology for fish behavior has developed rapidly. This article summarizes the development process of behavior monitoring technology and introduces some of the latest technologies for studying fish behavior. This article also summarizes the intergenerational effects of pollutants on fish behavior, as well as the potential intrinsic and genetic mechanisms that may lead to behavioral changes. This article provides a reference for future relevant neurobehavioral studies.

Examining the immunotoxicity of oil sands process affected waters using a human macrophage cell line

Oil sands process affected water (OSPW) is produced during the surface mining of the oil sands bitumen deposits in Northern Alberta. OSPW contains variable quantities of organic and inorganic components causing toxic effects on living organisms. Advanced Oxidation Processes (AOPs) are widely used to degrade toxic organic components from OSPW including naphthenic acids (NAs). However, there is no established biological procedure to assess the effectiveness of the remediation processes. Our previous study showed that human macrophage cells (THP-1) can be used as a bioindicator system to evaluate the effectiveness of OSPW treatments through examining the proinflammatory gene transcription levels. In the present study, we investigated the immunotoxicological changes in THP-1 cells following exposure to untreated and AOP-treated OSPW. Specifically, using proinflammatory cytokine protein secretion assays we showed that AOP treatment significantly abrogates the ability of OSPW to induce the secretion of IL-1β, IL-6, IL-8, TNF-α, IL-1Ra and MCP-1. By measuring transcriptional activity as well as surface protein expression levels, we also showed that two select immune cell surface markers, CD40 and CD54, were significantly elevated following OSPW exposure. However, AOP treatments abolished the immunostimulatory properties of OSPW to enhance the surface expression of these immune proteins. Finally, a transcriptome-based approach was used to examine the proinflammatory effects of OSPW as well as the abrogation of immunotoxicity following AOP treatments. Overall, this research shows how a human macrophage cell-based biomonitoring system serves as an effective in vitro tool to study the immunotoxicity of OSPW samples before and after targeted remediation strategies.

Naphthenic acid fraction components from oil sands process-affected water from the Athabasca Oil Sands Region impair murine osteoblast differentiation and function

The extraction of bitumen from surface mining in the Athabasca Oil Sands Region (AOSR) produces large quantities of oil sands process-affected water (OSPW) that needs to be stored in settling basins near extraction sites. Chemical constituents of OSPW are known to impair bone health in some organisms, which can lead to increased fracture risk and lower reproductive fitness. Naphthenic acid fraction components (NAFCs) are thought to be among the most toxic class of compounds in OSPW; however, the effect of NAFCs on osteoblast development is largely unknown. In this study, we demonstrate that NAFCs from OSPW inhibit osteoblast differentiation and deposition of extracellular matrix, which is required for bone formation. Extracellular matrix deposition was inhibited in osteoblasts exposed to 12.5-125 mg/L of NAFC for 21 days. We also show that components within NAFCs inhibit the expression of gene markers of osteoblast differentiation and function, namely, alkaline phosphatase (Alp), osteocalcin, and collagen type 1 alpha 1 (Col1a1). These effects were partially mediated by the induction of glucocorticoid receptor (GR) activity; NAFC induces the expression of the GR activity marker genes Sgk1 (12.5 mg/L) and p85a (125 mg/L) and inhibits GR protein (125 mg/L) and Opg RNA (12.5 mg/L) expression. This study provides evidence that NAFC concentrations of 12.5 mg/L and above can directly act on osteoblasts to inhibit bone formation and suggests that NAFCs contain components that can act as GR agonists, which may have further endocrine disrupting effects on exposed wildlife.

Fathead Minnows Exposed to Organic Compounds from Oil Sands Tailings as Embryos Have Reduced Survival, Impaired Development, and Altered Behaviors That Persist into Larval Stages

Our study evaluated whether exposure to naphthenic acid fraction compounds (NAFCs) extracted from oil sands process-affected waters (OSPW) has adverse effects on fish embryos that persist into later life. We exposed fathead minnow (Pimephales promelas) embryos to concentrations of NAFCs found in OSPW (2.5-54 mg/L) for 7 days (1 day postfertilization to hatch), then raised surviving larvae in outdoor mesocosms of uncontaminated lake water for 1 month. Embryos exposed to NAFCs were more likely to exhibit malformations (by up to 8-fold) and had slower heart rates (by up to 24%) compared to controls. Fish raised in uncontaminated lake water following exposure to NAFCs as embryos, were 2.5-fold less likely to survive during the larval stage than control fish. These fish also showed up to a 45% decrease in swim activity and a 36% increase in swim burst events during behavioral tests relative to controls. We conclude that exposure to NAFCs during the embryonic stage can have lasting effects on fish survival, physiology, and behavior that persist at least through the larval stage. These findings of delayed mortalities and persistent sublethal effects of embryonic NAFC exposure are relevant to informing the development of regulations on treated OSPW releases from mining operations. Environ Toxicol Chem 2022;41:1319-1332. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Metabolomic Analysis of Hexagenid Mayflies Exposed to Sublethal Concentrations of Naphthenic Acid

The oil sands region in northeastern Alberta, Canada contain approximately 165 billion barrels of oil making it the third largest oil reserves in the world. However, processing of extracted bitumen generates vast amounts of toxic byproduct known as oil sands process waters. Naphthenic acids and associated sodium naphthenate salts are considered the primary toxic component of oil sands process waters. Although a significant body of work has been conducted on naphthenic acid toxicity at levels comparable to what is observed in current oil sands process waters, it is also important to understand any impacts of exposure to sublethal concentrations. We conducted a microcosm study using the mayfly Hexagenia spp. to identify sublethal impacts of naphthenic acid exposure on the survival, growth, and metabolome across a concentration gradient (0–100 μg L⁻¹) of sodium naphthenate. Nuclear magnetic resonance-based metabolomic analyses were completed on both the polar and lipophilic extracted fractions of whole organism tissue. We observed a positive relationship between sodium naphthenate concentration and mean principal component score of the first axis of the polar metabolome indicating a shift in the metabolome with increasing naphthenic acid exposure. Eleven metabolites correlated with increased naphthenic acid concentration and included those involved in energy metabolism and apoptosis regulation. Survival and growth were both high and did not differ among concentrations, with the exception of a slight increase in mortality observed at the highest concentration. Although lethal concentrations of naphthenic acids in other studies are higher (150–56,200 μg L⁻¹), our findings suggest that physiological changes in aquatic invertebrates may begin at substantially lower concentrations. These results have important implications for the release of naphthenic acids into surface waters in the Alberta oil sands region as an addition of even small volumes of oil sands process waters could initiate chronic effects in aquatic organisms. Results of this research will assist in the determination of appropriate discharge thresholds should oil sands process waters be considered for environmental release.

Comparing the effects of unconventional and conventional crude oil exposures on zebrafish and their progeny using behavioral and genetic markers

Diluted bitumen, also known as dilbit, is transported by rail and pipeline across Canada and the United States. Due to the fewer number of studies characterizing the toxicity of dilbit, a dilbit spill poses an unknown risk to freshwater aquatic ecosystems. In the following study, we compared the impact of early-life exposure to conventional and unconventional crude oils on the optomotor behavior, reproductive success, and transgenerational differences in gene expression in zebrafish and their progeny. For exposures, water accommodated fractions (WAFs) of crude oil were generated using a 1:1000 oil to water ratio for 3 different crudes; mixed sweet blend (MSB), medium sour composite (MSC) and dilbit. All three oils generated unique volatile organic compound (VOC) and polycyclic aromatic compound (PAC) profiles. Of the WAFs tested, only dilbit decreased the eye size of 2 dpf larvae, and only MSB exposed larvae had an altered behavioral response to a visual simulation of a predator. Early-life exposure to crude oil had no lasting impact on reproductive success of adult fish; however, each oil had unique impacts on the basal gene expression of the somatically exposed offspring. In this study, the biological effects differed between each of the oils tested, which implied chemical composition plays a critical role in determining the sublethal toxicity of conventional and unconventional crude oils in freshwater ecosystems.

Early-life exposure to weathered, unweathered and dispersed oil has persisting effects on ecologically relevant behaviors in sheepshead minnow

The Deepwater Horizon oil spill released 3.19 million barrels of crude oil into the Gulf of Mexico, making it the largest oil spill in U.S. history. Weathering and the application of dispersants can alter the solubility of compounds within crude oil, thus modifying the acute toxicity of the crude oil to aquatic life. The primary aim of our study was to determine the lasting impact of early-life stage sheepshead minnow (Cyprinodon variegatus variegatus) exposure to weathered, unweathered and dispersed crude oil on prey capture, male aggression, novel object interaction and global DNA methylation. Embryos were exposed from 1 to 10 dpf to water accommodations of crude oil and were raised to adulthood in artificial seawater. Our results suggest exposure to crude oil did not result in lasting impairment of complex behavioral responses of male sheepshead minnow. Exposure to dispersed weathered oil, however, decreased border dwelling in response to a novel object (i.e. decreased anxiety). Principal component analysis revealed that exposure to weathered oil had no overarching effect, but that unweathered crude oil increased variability in exploratory behaviors but decreased variability in anxiety-associated behaviors. Further work is needed to understand the effects of oil exposure on fish behavior and the potential ecological impact of subtle behavioral changes in fishes.