Measurement of naphthenic acids in the receiving waters around an offshore oil platform by passive sampling

Analysis of a Passive Sampling Device to Assess the Behavior of Per- and Polyfluoroalkyl Substances in Sediments

Per- and polyfluoroalkyl substances (PFAS) are an emerging class of compounds that cause health and environmental problems worldwide. In aquatic environments, PFAS may bioaccumulate in sediment organisms, which can affect the health of organisms and ecosystems. As such, it is important to develop tools to understand their bioaccumulation potential. In the present study, the uptake of perfluorooctanoic acid (PFOA) and perfluorobutane sulfonic acid (PFBS) from sediments and water was assessed using a modified polar organic chemical integrative sampler (POCIS) as a passive sampler. While POCIS has previously been used to measure time-weighted concentrations of PFAS and other compounds in water, in our study, the design was adapted for analyzing contaminant uptake and porewater concentrations in sediments. The samplers were deployed into seven different tanks containing PFAS-spiked conditions and monitored over 28 days. One tank contained only water with PFOA and PFBS, three tanks contained soil with 4% organic matter, and three tanks contained soil combusted at 550 °C to minimize the influence of labile organic carbon. The uptake of PFAS from the water was consistent with previous research using a sampling rate model or simple linear uptake. For the samplers placed in the sediment, the uptake process was explained well using a mass transport based on the external resistance from the sediment layer. Uptake of PFOS in the samplers occurred faster than that of PFOA and was more rapid in the tanks containing the combusted soil. A small degree of competition was observed between the two compounds for the resin, although these effects are unlikely to be significant at environmentally relevant concentrations. The external mass transport model provides a mechanism to extend the POCIS design for measuring porewater concentrations and sampling releases from sediments. This approach may be useful for environmental regulators and stakeholders involved in PFAS remediation. Environ Toxicol Chem 2023;42:2171-2183. © 2023 SETAC.

Exposure methodologies for dissolved individual hydrocarbons, dissolved oil, water oil dispersions, water accommodated fraction and chemically enhanced water accommodated fraction of fresh and weathered oil

Characterizing the nature and effects of oil released into the marine environment is very challenging. It is generally recognized that "environmentally relevant" conditions for exposure involve a range of temporal and spatial conditions, a range of exposure pathways (e.g., dissolved, emulsions, sorbed onto particulates matter), and a multitude of organisms, populations, and ecosystems. Various exposure methodologies have been used to study the effects of oil on aquatic organisms, and uniform protocols and exposure methods have been developed for the purposes of regulatory toxicological assessments. Ultimately, all exposure methods have drawbacks, it is impossible to totally mimic field conditions, and the choice of exposure methodology depends on the specific regulatory, toxicological, or other research questions to be addressed. The aim of this paper is to provide a concise review of the state of knowledge to identify gaps in that knowledge and summarize challenges for the future.

Treatment of naphthenic acids in oil sands process-affected waters with a surface flow treatment wetland: mass removal, half-life, and toxicity-reduction

This study is the first to investigate the removal of naphthenic acids in a full-scale constructed wetland within the Alberta Oil Sands region. The average mass-removal efficiency for all O₂-naphthenic acids measured in three separate deployments in the wetland ranged from 7.5% to 68.9% and appeared sensitive to physicochemical properties of the naphthenic acids, environmental conditions, and water quality. Treatment efficiency of individual naphthenic acids was found to increase with increasing carbon number and decreasing number of double bond equivalents in the molecule. Treatment efficiency was also found to increase with both higher initial turbidity in OSPW entering the wetland, and warmer average OSPW temperatures during wetland operation. Half-life times of naphthenic acids in the treatment wetland ranged between 8.9 and 39 days and were substantially lower than those in tailings ponds (i.e., 12.9-13.6 years) and laboratory studies focussed on bench-scale aerobic microbial biodegradation (i.e., 44-315 days). Using published dose-response data, biomimetic extraction measurements using solid phase microextraction fibers indicate that 14 days of wetland treatment resulted in a reduction in (4 d) deformity of Danio rerio from 50 to 16%, while exhibiting less than 1% toxic response for less sensitive toxic endpoints. The study concludes that wetland treatment is a feasible and productive treatment method for naphthenic acids in oil sands process-affected water due to a combination of sorption and biodegradation.

The study of polar emerging contaminants in seawater by passive sampling: A review

Emerging Contaminants (ECs) in marine waters include different classes of compounds, such as pharmaceuticals and personal care products, showing "emerging concern" related to the environment and human health. Their measurement in seawater is challenging mainly due to the low concentration levels and the possible matrix interferences. Mass spectrometry combined with chromatographic techniques represents the method of choice to study seawater ECs, due to its sensitivity and versatility. Nevertheless, these instrumental techniques have to be preceded by suitable sample collection and pre-treatment: passive sampling represents a powerful approach in this regard. The present review compiles the existing occurrence studies on passive sampling coupled to mass spectrometry for the monitoring of polar ECs in seawater and discusses the availability of calibration data that enabled quantitative estimations. A vast majority of the published studies carried out during the last two decades describe the use of integrative samplers, while applications of equilibrium samplers represent approximately 10%. The polar Chemcatcher was the first applied to marine waters, while the more sensitive Polar Organic Chemical Integrative Sampler rapidly became the most widely employed passive sampler. The organic Diffusive Gradients in Thin film technology is a recently introduced and promising device, due to its more reliable sampling rates. The best passive sampler selection for the monitoring of ECs in the marine environment as well as future research and development needs in this area are further discussed. On the instrumental side, combining passive sampling with high resolution mass spectrometry to better assess polar ECs is strongly advocated, despite the current challenges associated.

Environmental effects of offshore produced water discharges: A review focused on the Norwegian continental shelf

Produced water (PW), a large byproduct of offshore oil and gas extraction, is reinjected to formations or discharged to the sea after treatment. The discharges contain dispersed crude oil, polycyclic aromatic hydrocarbons (PAHs), alkylphenols (APs), metals, and many other constituents of environmental relevance. Risk-based regulation, greener offshore chemicals and improved cleaning systems have reduced environmental risks of PW discharges, but PW is still the largest operational source of oil pollution to the sea from the offshore petroleum industry. Monitoring surveys find detectable exposures in caged mussel and fish several km downstream from PW outfalls, but biomarkers indicate only mild acute effects in these sentinels. On the other hand, increased concentrations of DNA adducts are found repeatedly in benthic fish populations, especially in haddock. It is uncertain whether increased adducts could be a long-term effect of sediment contamination due to ongoing PW discharges, or earlier discharges of oil-containing drilling waste. Another concern is uncertainty regarding the possible effect of PW discharges in the sub-Arctic Southern Barents Sea. So far, research suggests that sub-arctic species are largely comparable to temperate species in their sensitivity to PW exposure. Larval deformities and cardiac toxicity in fish early life stages are among the biomarkers and adverse outcome pathways that currently receive much attention in PW effect research. Herein, we summarize the accumulated ecotoxicological knowledge of offshore PW discharges and highlight some key remaining knowledge needs.

Monitoring wastewater discharge from the oil and gas industry using passive sampling and Danio rerio bioassay as complimentary tools

Produced water (PW) represents the largest volume waste stream in oil and gas production operations from most offshore platforms. PW is difficult to monitor as releases are rapidly diluted and concentrations can reach trace levels. The use of passive samplers can over come this. Here polyethylene (PE) was calibrated for a diverse range of PW pollutants. Zebrafish were exposed to dilutions of PW and passive sampler extracts in order to investigate the relationship between freely dissolved chemical concentrations and acute toxic effects. The raw PW had an LC50 of 13% (percentage of PW in the standardized zebrafish medium). Observed non-viable deformations to embryos (at 5 hpf) included heart and yolk edema, head, spine and tail deformations. The dose-response relationship of lethal effects showed that if 0.0041 g of PE is exposed to this PW, then extracted, 50% of exposed D. rerio will suffer lethal effects. The sum of tested freely dissolved concentrations that led to 50% lethal effects (mortality and non-viable deformations) was 2.32 × 10^-4 mg/L for PW and 7.92 × 10^-2 mg/L for PE. This implies that exposure to raw PW was more toxic than exposure to PE extracts. This toxicity was attributed both to the presence of contaminants as well as PW salinity. Passive samplers are able to detect very low freely dissolved pollutant concentrations which is important for assessing the spatial dilution of PW releases. Bioassays provide complimentary information as they account for all toxic compounds including those that are not taken up by passive samplers.

Application of the Target Lipid Model and Passive Samplers to Characterize the Toxicity of Bioavailable Organics in Oil Sands Process-Affected Water

Oil sand operations in Alberta, Canada will eventually include returning treated process-affected waters to the environment. Organic constituents in oil sand process-affected water (OSPW) represent complex mixtures of nonionic and ionic (e.g., naphthenic acids) compounds, and compositions can vary spatially and temporally, which has impeded development of water quality benchmarks. To address this challenge, it was hypothesized that solid phase microextraction fibers coated with polydimethylsiloxane (PDMS) could be used as a biomimetic extraction (BE) to measure bioavailable organics in OSPW. Organic constituents of OSPW were assumed to contribute additively to toxicity, and partitioning to PDMS was assumed to be predictive of accumulation in target lipids, which were the presumed site of action. This method was tested using toxicity data for individual model compounds, defined mixtures, and organic mixtures extracted from OSPW. Toxicity was correlated with BE data, which supports the use of this method in hazard assessments of acute lethality to aquatic organisms. A species sensitivity distribution (SSD), based on target lipid model and BE values, was similar to SSDs based on residues in tissues for both nonionic and ionic organics. BE was shown to be an analytical tool that accounts for bioaccumulation of organic compound mixtures from which toxicity can be predicted, with the potential to aid in the development of water quality guidelines.

Fossil Fuel-Derived Polycyclic Aromatic Hydrocarbons in the Taiwan Strait, China, and Fluxes across the Air-Water Interface

On the basis of the application of compound-specific radiocarbon analysis (CSRA) and air-water exchange models, the contributions of fossil fuel and biomass burning derived polycyclic aromatic hydrocarbons (PAHs) as well as their air-water transport were elucidated. The results showed that fossil fuel-derived PAHs (an average contribution of 89%) presented the net volatilization process at the air-water interface of the Taiwan Strait in summer. Net volatile fluxes of the dominant fluorene and phenanthrene (>58% of the total PAHs) were 27 ± 2.8 μg m^-2 day^-1, significantly higher than the dry deposition fluxes (average 0.43 μg m^-2 day^-1). The Δ¹⁴C contents of selected PAHs (fluorene, phenanthrene plus anthracene, fluoranthene, and pyrene) determined by CSRA in the dissolved seawater ranged from -997 ± 4‰ to -873 ± 6‰, indicating that 89-100% (95 ± 4%) of PAHs were supplied by fossil fuels. The South China Sea warm current originating from the southwest China in summer (98%) and the Min-Zhe coastal current originating from the north China in winter (97%) input more fossil fuel PAHs than the Jiulong River estuary (90%) and Xiamen harbor water (93%). The more radioactive decayed ¹⁴C of fluoranthene (a 4-ring PAH) than that of phenanthrene and anthracene (3-ring PAHs) represented a greater fossil fuel contribution to the former in dissolved seawater.

The role of passive sampling in monitoring the environmental impacts of produced water discharges from the Norwegian oil and gas industry

Stringent and periodic iteration of regulations related to the monitoring of chemical releases from the offshore oil and gas industry requires the use of ever changing, rapidly developing and technologically advancing techniques. Passive samplers play an important role in water column monitoring of produced water (PW) discharge to seawater under Norwegian regulation, where they are used to; i) measure aqueous concentrations of pollutants, ii) quantify the exposure of caged organisms and investigate PW dispersal, and iii) validate dispersal models. This article summarises current Norwegian water column monitoring practice and identifies research and methodological gaps for the use of passive samplers in monitoring. The main gaps are; i) the range of passive samplers used should be extended, ii) differences observed in absolute concentrations accumulated by passive samplers and organisms should be understood, and iii) the link between PW discharge concentrations and observed acute and sub-lethal ecotoxicological end points in organisms should be investigated.

Identification of petrogenic produced water components as acetylcholine esterase inhibitors

Effect-directed analysis (EDA) was applied to identify acetylcholine esterase (AChE) inhibitors in produced water. Common produced water components from oil production activities, such as polycyclic aromatic hydrocarbons (PAHs), alkylphenols, and naphthenic acids were tested for AChE inhibition using a simple mixture of PAHs and naphthenic acids. Produced water samples collected from two offshore platforms in the Norwegian sector of the North Sea were extracted by solid phase extraction and fractionated by open-column liquid solid chromatography and high-performance liquid chromatography (HPLC) before being tested using a high-throughput and automated AChE assay. The HPLC fractions causing the strongest AChE inhibition were analysed by gas chromatography coupled to a high-resolution time-of-flight mass spectrometry (GC-HR-ToF-MS). Butylated hydroxytoluene and 4-phenyl-1,2-dihydronaphthalene were identified as two produced water components capable of inhibiting AChE at low concentrations. In order to assess the potential presence of such compounds discharged into aquatic ecosystems, AChE activity in fish tissues was measured. Saithe (Pollachius virens) caught near two offshore platforms showed lower enzymatic activity than those collected from a reference location. Target analysis of saithe did not detected the presence of these two putative AChE inhibitors and suggest that additional compounds such as PAHs, naphthenic acids and yet un-identified compounds may also contribute to the purported AChE inhibition observed in saithe.