Metabolic responses to crude oil during early life stages reveal critical developmental windows in the zebrafish (Danio rerio)

Morphological effects of crude oil exposure on early development in fishes have been well documented, but crude oil's metabolic effects and when in early development these effects might be most prominent remains unclear. We hypothesized that zebrafish (Danio rerio) exposed to crude oil as a high energy water accommodated fraction (HEWAF) would show increased routine oxygen consumption (ṀO₂) and critical oxygen tension (P_Crit) and this effect would be dependent upon day of HEWAF exposure, revealing critical windows of development for exposure effects. Zebrafish were exposed to 0%, 10%, 25%, 50% or 100% HEWAF for 24 h during one of the first six days post-fertilization (dpf). Survival rate, body mass, routine ṀO₂, and P_Crit were then measured at 7 dpf. Survival rate and especially body mass were both decreased based on both exposure concentration and day of crude oil exposure, with the largest decrease when HEWAF exposure occurred at 3 dpf. HEWAF effects on routine ṀO₂ also differed depending upon exposure day. The largest effect occurred at 3 dpf, when ṀO₂ increased significantly by ~60% from 10.1 ± 0.8 μmol O₂/g/h compared to control group value of 6.3 ± 0.4 μmol O₂/g/h. No significant effects of HEWAF exposure on any day were evident for P_Crit (85 ± 4 mmHg in the control population). Overall, the main effects on body mass and ṀO₂ measured at 7 dpf occurred when HEWAF exposures occurred at ~3 dpf. This critical window for metabolism in zebrafish larvae coincides with time of hatching, which may represent an especially vulnerable period in development.

Association of Deepwater Horizon Oil Spill Response and Cleanup Work With Risk of Developing Hypertension

IMPORTANCE

Exposure to hydrocarbons, fine particulate matter (PM2.5), and other chemicals from the April 20, 2010, Deepwater Horizon disaster may be associated with increased blood pressure and newly detected hypertension among oil spill response and cleanup workers.

OBJECTIVE

To determine whether participation in cleanup activities following the disaster was associated with increased risk of developing hypertension.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted via telephone interviews and in-person home exams. Participants were 6846 adults who had worked on the oil spill cleanup (workers) and 1505 others who had completed required safety training but did not do cleanup work (nonworkers). Eligible participants did not have diagnosed hypertension at the time of the oil spill. Statistical analyses were performed from June 2018 to December 2021.

EXPOSURES

Engagement in cleanup activities following the Deepwater Horizon oil spill disaster, job classes, quintiles of cumulative total hydrocarbons exposure level, potential exposure to burning or flaring oil, and estimated PM2.5 were examined.

MAIN OUTCOMES AND MEASURES

Systolic and diastolic blood pressure measurements were collected during home exams from 2011 to 2013 using automated oscillometric monitors. Newly detected hypertension was defined as antihypertensive medication use or elevated blood pressure since the spill. Log binomial regression was used to calculate prevalence ratios (PR) and 95% CIs for associations between cleanup exposures and hypertension. Multivariable linear regression was used to estimate exposure effects on continuous blood pressure levels.

RESULTS

Of 8351 participants included in this study, 6484 (77.6%) were male, 517 (6.2%) were Hispanic, 2859 (34.2%) were non-Hispanic Black, and 4418 (52.9%) were non-Hispanic White; the mean (SD) age was 41.9 (12.5) years at enrollment. Among workers, the prevalence of newly detected hypertension was elevated in all quintiles (Q) of cumulative total hydrocarbons above the first quintile (PR for Q3, 1.29 [95% CI, 1.13-1.46], PR for Q4, 1.25 [95% CI, 1.10-1.43], and PR for Q5, 1.31 [95% CI, 1.15-1.50]). Both exposure to burning and/or flaring oil and gas (PR, 1.16 [95% CI, 1.02-1.33]) and PM2.5 from burning (PR, 1.26 [95% CI, 0.89-1.71]) for the highest exposure category were associated with increased risk of newly detected hypertension, as were several types of oil spill work including cleanup on water (PR, 1.34 [95% CI, 1.08-1.66]) and response work (PR, 1.51 [95% CI, 1.20-1.90]).

CONCLUSIONS AND RELEVANCE

Oil spill exposures were associated with newly detected hypertension after the Deepwater Horizon disaster. These findings suggest that blood pressure screening should be considered for workers with occupational hydrocarbon exposures.

Acute and longer-term cardiovascular conditions in the Deepwater Horizon Oil Spill Coast Guard Cohort

INTRODUCTION

In 2010, the U.S. Coast Guard (USCG) led a clean-up response to the Deepwater Horizon (DWH) oil spill. Human studies evaluating acute and longer-term cardiovascular conditions associated with oil spill-related exposures are sparse. Thus, we aimed to investigate prevalent and incident cardiovascular symptoms/conditions in the DHW Oil Spill Coast Guard Cohort.

METHODS

Self-reported oil spill exposures and cardiovascular symptoms were ascertained from post-deployment surveys (n = 4,885). For all active-duty cohort members (n = 45,193), prospective cardiovascular outcomes were classified via International Classification of Diseases, 9th Edition from military health encounter records up to 5.5 years post-DWH. We used log-binomial regression to calculate adjusted prevalence ratios (aPRs) and 95% confidence intervals (CIs) in the cross-sectional analyses and Cox Proportional Hazards regression to calculate adjusted hazard ratios (aHR) and 95% CIs for incident cardiovascular diagnoses during 2010-2015 and stratifying by earlier (2010-2012) and later (2013-2015) time periods.

RESULTS

Prevalence of chest pain was associated with increasing levels of crude oil exposure via inhalation (aPR_{high vs. none} = 2.00, 95% CI = 1.16-3.42, p-trend = 0.03) and direct skin contact (aPR_{high vs. none} = 2.72, 95% CI = 1.30-5.16, p-trend = 0.03). Similar associations were observed for sudden heartbeat changes and for being in the vicinity of burning oil exposure. In prospective analyses, responders (vs. non-responders) had an elevated risk for mitral valve disorders during 2013-2015 (aHR = 2.12, 95% CI = 1.15-3.90). Responders reporting ever (vs. never) crude oil inhalation exposure were at increased risk for essential hypertension, particularly benign essential hypertension during 2010-2012 (aHR = 2.00, 95% CI = 1.08-3.69). Responders with crude oil inhalation exposure also had an elevated risk for palpitations during 2013-2015 (aHR = 2.54, 95% CI = 1.36-4.74). Cardiovascular symptoms/conditions aPR and aHR estimates were generally stronger among responders reporting exposure to both crude oil and oil dispersants than among those reporting neither.

CONCLUSIONS

In this large study of the DWH oil spill USCG responders, self-reported spill clean-up exposures were associated with acute and longer-term cardiovascular symptoms/conditions.

Polycyclic aromatic hydrocarbons (PAHs) cycling and fates in Galveston Bay, Texas, USA

The cycling and fate of polycyclic aromatic hydrocarbons (PAHs) is not well understood in estuarine systems. It is critical now more than ever given the increased ecosystem pressures on these critical coastal habitats. A budget of PAHs and cycling has been created for Galveston Bay (Texas) in the northwestern Gulf of Mexico, an estuary surrounded by 30-50% of the US capacity of oil refineries and chemical industry. We estimate that approximately 3 to 4 mt per year of pyrogenic PAHs are introduced to Galveston Bay via gaseous exchange from the atmosphere (ca. 2 mt/year) in addition to numerous spills of petrogenic PAHs from oil and gas operations (ca. 1.0 to 1.9 mt/year). PAHs are cycled through and stored in the biota, and ca. 20 to 30% of the total (0.8 to 1.5 mt per year) are estimated to be buried in the sediments. Oysters concentrate PAHs to levels above their surroundings (water and sediments) and contain substantially greater concentrations than other fish catch (shrimp, blue crabs and fin fish). Smaller organisms (infaunal invertebrates, phytoplankton and zooplankton) might also retain a significant fraction of the total, but direct evidence for this is lacking. The amount of PAHs delivered to humans in seafood, based on reported landings, is trivially small compared to the total inputs, sediment accumulation and other possible fates (metabolic remineralization, export in tides, etc.), which remain poorly known. The generally higher concentrations in biota from Galveston Bay compared to other coastal habitats can be attributed to both intermittent spills of gas and oil and the bay's close proximity to high production of pyrogenic PAHs within the urban industrial complex of the city of Houston as well as periodic flood events that transport PAHs from land surfaces to the Bay.

Enterprise Evaluation: A New Opportunity for Public Health Policy

Standard evaluation practice in public health remains limited to evaluative measures linked to individual projects, even if multiple interrelated projects are working toward a common impact. Enterprise evaluation seeks to fill this policy gap by focusing on cross-sector coordination and ongoing reflection in evaluation. We provide an overview of the enterprise evaluation framework and its 3 stages: collective creation, individual data collection, and collective analysis. We illustrate the application of enterprise evaluation to the Gulf Region Health Outreach Program, 4 integrated projects that aimed to strengthen health care in Louisiana, Mississippi, Alabama, and the Florida Panhandle after the Deepwater Horizon oil spill. Shared commitment to sustainability and strong leadership were critical to Gulf Region Health Outreach Program's success in enterprise evaluation. Enterprise evaluation provides an important opportunity for funding agencies and public health initiatives to evaluate the impact of interrelated projects in a more holistic and multiscalar manner than traditional siloed approaches to evaluation.

Dynamic ecological risk modelling of hydrocarbon release scenarios in Arctic waters

The Arctic is an ecologically diverse area that is increasingly vulnerable to damages from oil spills associated with commercial vessels traversing newly open shipping lanes. The significance of such accidents on Arctic marine habitats and the potential for recovery can be examined using ecological risk assessment (ERA) coupled with a dynamic object-oriented Bayesian network (DOOBN). A DOOBN approach is useful to represent the probabilistic relationships inherent in the interactions between key events associated with an oil spill, including oil dispersion from the source, ice-oil slick interactions, seawater-oil slick formation, sedimentation, and exposures to different aquatic life. From such analysis, a probabilistic cost analysis can be performed to examine the theoretical cost of habitat services lost and restored. The application of an ERA-DOOBN model to assess oil spills in the Arctic is demonstrated using a case study. The utility of the model output for determining habitat restoration costs and developing policy guidelines for ecological response measures in the Arctic is also discussed.

A case study on oil pollution in Istanbul Strait: Revisiting 1994 Nassia tanker accident by utilising Potential Incident Simulation Control and Evaluation System (PISCES-II) simulation. What would be different in terms of response if Nassia accident happened today?

Turkey, with her two important straits, is geographically in the middle of one of the major transportation routes and will continue to face risks the oil tankers pose in those sensitive areas. This paper revisits the site of an oil tanker accident that occurred at the northern entrance of the Istanbul Strait in 1994. The aim of the study was to simulate the same accident in PISCES-II Simulator to compare the response actions of the time with the present capabilities. Effort is also made to understand how the negative impacts of an oil spill accident can be lessened. Therefore, the study is planned to set to cover two separate response scenarios for the identical oil spill incident, actually simulating the 1994 M/T Nassica accident. The results showed that oil pollution response in places with strong currents like Istanbul Strait needs special care to sea conditions as well as related assets.

Need to update human health risk assessment protocols for polycyclic aromatic hydrocarbons in seafood after oil spills

The need to include alkylated polycyclic aromatic hydrocarbons in human health risks assessments for oil contaminated seafood after crude oil spills is set forth. This is placed within the context of a brief review of the literature for PAHs and human health risk assessments after oil spills. The example of human health risk assessments for oil contaminated seafood after the Deepwater Horizon oil spill is reviewed with the conclusion that PAHs such as alkylated chrysenes/triphenylenes/benzanthracenes should have been included in the human health risk assessment and not dismissed as present in very low concentrations relative to their parent PAHs.

Categorization of nearshore sampling data using oil slick trajectory predictions

Oil Spill Chemicals (OSCs) represent a risk to the environment and human health, especially in nearshore environments used for recreational purposes. Importantly, the starting point for human health risk assessment is to define the concentration of OSCs at nearshore locations. The objective of this study was to evaluate nearshore sampling data of OSC concentrations in different environmental matrices within time-space specific categories. The categories correspond to OSC concentration values for samples collected prior to nearshore oiling, post nearshore oiling and at no time impacted by oil as predicted by historic oil spill trajectories generated by an Oil Spill Trajectory Model. In general, concentration values for the post category were higher than prior which were higher than unimpacted. Results show differences in PAH concentration patterns within each matrix and for each category. Concentration frequency distributions for most chemicals in each category were log-normally distributed.

Deepwater Horizon oil spill exposures and neurobehavioral function in GuLF study participants

INTRODUCTION

The 2010 Deepwater Horizon (DWH) disaster exposed tens of thousands of oil spill response and cleanup (OSRC) workers to hydrocarbons and other hazardous chemicals. Some hydrocarbons, such as toluene and hexane, have been found to have acute adverse effects on the central nervous system in occupational settings. However, no studies have examined the association between oil spill exposures and neurobehavioral function.

METHODS

We used data from the Gulf Long-term Follow-up Study, a cohort of adults who worked on the DWH response and cleanup. Total hydrocarbon (THC) exposure attributed to oil spill cleanup work was estimated from a job-exposure matrix linking air measurement data to detailed cleanup work histories. Participants were also categorized into 6 job categories, or OSRC classes, based on their activity with the highest exposure. Neurobehavioral performance was assessed at a clinical exam 4-6 years after the spill. We used multivariable linear regression to evaluate relationships of ordinal THC levels and OSRC classes with 16 neurobehavioral outcomes.

RESULTS

We found limited evidence of associations between THC levels or OSRC classes and decreased neurobehavioral function, including attention, memory, and executive function. Workers exposed to ≥3 ppm THC scored significantly worse (difference_1.0-2.9ppm = -0.39, 95% confidence interval (CI) = -0.74, -0.04) than workers exposed to <0.30 ppm THC for the digit span forward count test. There was also a possible threshold effect above 1 ppm THC for symbol digit test total errors (difference_1.0-2.9ppm = -0.56 (95% CI = -1.13, -0.003), difference_≥3.0ppm = -0.55 (95% CI = -1.20, 0.10)). Associations appeared to be stronger in men than in women. A summary latency measure suggested an association between more highly exposed jobs (especially support of operations workers) and decreased neurobehavioral function.

CONCLUSION

OSRC-related exposures were associated with modest decreases in neurobehavioral function, especially attention, memory, and executive function.

Drinking water quality in areas impacted by oil activities in Ecuador: Associated health risks and social perception of human exposure

The unregulated oil exploitation in the Northern Ecuadorian Amazon Region (NEAR), mainly from 1964 to the 90's, led to toxic compounds largely released into the environment. A large majority of people living in the Amazon region have no access to drinking water distribution systems and collects water from rain, wells or small streams. The concentrations of major ions, trace elements, PAHs (polycyclic aromatic hydrocarbons) and BTEX (benzene, toluene, ethylbenzene, xylenes) were analyzed in different water sources to evaluate the impacts of oil extraction and refining. Samples were taken from the NEAR and around the main refinery of the country (Esmeraldas Oil Refinery/State Oil Company of Ecuador) and were compared with domestic waters from the Southern region, not affected by petroleum activities. In most of the samples, microbiological analysis revealed a high level of coliforms representing significant health risks. All measured chemical compounds in waters were in line with national and international guidelines, except for manganese, zinc and aluminum. In several deep-water wells, close to oil camps, toluene concentrations were higher than the natural background while PAHs concentrations never exceeded individually 2 ng·L^-1. Water ingestion represented 99% of the total exposure pathways for carcinogenic and non-carcinogenic elements (mainly zinc) in adults and children, while 20% to 49% of the Total Cancer Risk was caused by arsenic concentrations. The health index (HI) indicates acceptable chronic effects for domestic use according the US-EPA thresholds. Nevertheless, these limits do not consider the cocktail effects of metallic and organic compounds. Furthermore, they do not include the social determinants of human exposure, such as socio-economic living conditions or vulnerability. Most (72%) of interviewed families knew sanitary risks but a discrepancy was observed between knowledge and action: religious beliefs, cultural patterns, information sources, experience and emotions play an important role front to exposure.

Developing Large-Scale Research in Response to an Oil Spill Disaster: a Case Study

Research conducted in the wake of a disaster can provide information to help mitigate health consequences, support future recovery efforts, and improve resilience. However, a number of barriers have prevented time-sensitive research responses following previous disasters. Furthermore, large-scale disasters present their own special challenges due to the number of people exposed to disaster conditions, the number of groups engaged in disaster response, and the logistical challenges of rapidly planning and implementing a large study. In this case study, we illustrate the challenges in planning and conducting a large-scale post-disaster research study by drawing on our experience in establishing the Gulf Long-term Follow-up (GuLF) Study following the 2010 Deepwater Horizon disaster. We describe considerations in identifying at-risk populations and appropriate comparison groups, garnering support for the study from different stakeholders, obtaining timely scientific and ethics review, measuring and characterizing complex exposures, and addressing evolving community health concerns and unmet medical needs. We also describe the NIH Disaster Research Response (DR2) Program, which provides a suite of resources, including data collection tools, research protocols, institutional review board guidance, and training materials to enable the development and implementation of time-critical studies following disasters and public health emergencies. In describing our experiences related to the GuLF Study and the ongoing efforts through the NIH DR2 Program, we aim to help improve the timeliness, quality, and value of future disaster-related data collection and research studies.

Mid-long term oil spill forecast based on logistic regression modelling of met-ocean forcings

Past major oil spill disasters, such as the Prestige or the Deepwater Horizon accidents, have shown that spilled oil may drift across the ocean for months before being controlled or reaching the coast. However, existing oil spill modelling systems can only provide short-term trajectory simulations, being limited by the typical met-ocean forecast time coverage. In this paper, we propose a methodology for mid-long term (1-6 months) probabilistic predictions of oil spill trajectories, based on a combination of data mining techniques, statistical pattern modelling and probabilistic Lagrangian simulations. Its main features are logistic regression modelling of wind and current patterns and a probabilistic trajectory map simulation. The proposed technique is applied to simulate the trajectory of drifting buoys deployed during the Prestige accident in the Bay of Biscay. The benefits of the proposed methodology with respect to existing oil spill statistical simulation techniques are analysed.

Hebei Spirit oil spill and its long-term effect on children's asthma symptoms

On December 7th, 2007, an estimated 12,547 kL of crude oil was spilled from the collision of Hebei Spirit near residential area. Our previous study demonstrated worsening of children's asthma symptoms one year after the accident. This study investigated long-term effect of the oil spill on children's asthma symptoms up to five years after the accident. All elementary and middle school students in the exposure area were surveyed on one year (n = 655), three years (664), and five years (611) after the accident. Oil spill exposure was estimated using two estimates including distance from the oil spill (A) and modeled estimates of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds (B), and each was dichotomously categorized (A: high-exposure vs low-exposure; B: ≥20 mg/m³ vs < 20 mg/m³). Asthma symptoms were evaluated using a standard questionnaire. Oil spill exposure estimates were associated with asthma symptoms on one year (odds ratio (95% confidence interval) A: 1.9 (1.1-3.1); B: 1.6 (0.9-2.7)), three years (A: 1.9 (1.1-3.2); B: 1.3 (0.8-2.2)), and five years (A: 1.2 (0.7-1.9); B: 1.8 (1.1-2.8)) after the oil spill. Significant longitudinal relationship between oil spill exposure estimates and asthma symptoms was also observed (A: 1.6 (1.2-2.2); B: 1.6 (1.1-2.1)). Overall, the effect of oil spill exposure estimates was more severe on younger children. Oil spill exposure estimates were associated with asthma symptoms in children up to five years after the oil spill.

Quantifying exposure levels of coastal facilities to oil spills in Bahrain, Arabian Gulf

The Arabian Gulf is considered as a hub for global oil industry. Thus the Arabian Gulf marine environment is under permanent threat from oil spills due to oil exploitation, production, and transportation. Oil pollution poses adverse effects on marine environment, society, and economy. Oil spill incidents that occurred in Bahrain caused damage to marine environment and threatened the vital coastal facilities along the coastline of Bahrain. This study determined the exposure levels of coastal facilities in Bahrain to oil spills. The General NOAA Operational Modeling Environment (GNOME) model was validated and applied to hypothetical oil spill scenarios. The modeling results showed that the coastal facilities on the north-eastern coastline are more probable to be hit by oil spills, while those on the northern coastline are susceptible to receive more quantity of oil. The time required for oil to reach the western coastline is shorter compared to the other coastlines. The modeling outcomes can be utilized in contingency planning, setting the protection priorities and allocation and mobilization of response resources in both governmental and private sectors. The implications of the present study could be applied on a regional scale to ensure an integrated response to combat and or minimize oil pollution in the Arabian Gulf.

Research of OSA seasonal training in the São Paulo River, BTS: a tool to prevent potential ecotoxicological impacts

Oil exploitation, the basis of the world energy sector, is linked to risks and accidents, causing damage to the affected regions. Oil-suspended particulate matter aggregate (OSA) is a promising technology to mitigate those effects. The present study periodically (February 2016 and July 2016) evaluated the dispersion of oil at 28 points in the São Paulo River's estuary, Todos os Santos Bay, Brazil, analyzing the influence of suspended particulate matter (SPM), particulate organic carbon (POC), ions, and chlorophyll on the formation OSA, targeting the prediction of possible ecotoxicological risks. The results showed that the estuary presented similar characteristics in the expeditions, reflecting the oil dispersion pattern through the formation of OSAs, being 92.86% dispersed in the column in the first and 85.71% in the second expedition. The results also pointed to the possibility of pollution in the food chain, reduced fertility, the emergence of abnormalities and the gradual disappearance of species across the whole river in a possible oil spill.

Performance evaluation of oil spill software systems in early fate and trajectory of oil spill: comparison analysis of OILMAP and PISCES 2 in Mersin bay spill

The aim of this study is to evaluate the performance level of two advanced oil spill software systems in early transport and fate of oil spill through algorithms accepted in oil spill literature. To do this, the performance level of software systems mostly used in real cases have been compared. OILMAP (the oil spill prediction modeling system) and PISCES 2 (potential incident simulation, control and evaluation system) have been used for spill trajectory in the light of four spill scenarios. The findings reveal that the OILMAP has predicted a relatively larger area of spill. In addition, OILMAP has achieved closer results to the calculations of approaches adopted in the literature for evaporation calculations. Besides, OILMAP software has provided highly reliable results in the evaporation rates of oil compared to the calculations of PISCES 2. On the other hand, as for the determination of the risky area, both software systems have yielded results with high reliability values, which could be used in taking precautions against oil spill in such areas.

Potential impacts of offshore oil spills on polar bears in the Chukchi Sea

Sea ice decline is anticipated to increase human access to the Arctic Ocean allowing for offshore oil and gas development in once inaccessible areas. Given the potential negative consequences of an oil spill on marine wildlife populations in the Arctic, it is important to understand the magnitude of impact a large spill could have on wildlife to inform response planning efforts. In this study we simulated oil spills that released 25,000 barrels of oil for 30 days in autumn originating from two sites in the Chukchi Sea (one in Russia and one in the U.S.) and tracked the distribution of oil for 76 days. We then determined the potential impact such a spill might have on polar bears (Ursus maritimus) and their habitat by overlapping spills with maps of polar bear habitat and movement trajectories. Only a small proportion (1-10%) of high-value polar bear sea ice habitat was directly affected by oil sufficient to impact bears. However, 27-38% of polar bears in the region were potentially exposed to oil. Oil consistently had the highest probability of reaching Wrangel and Herald islands, important areas of denning and summer terrestrial habitat. Oil did not reach polar bears until approximately 3 weeks after the spills. Our study found the potential for significant impacts to polar bears under a worst case discharge scenario, but suggests that there is a window of time where effective containment efforts could minimize exposure to bears. Our study provides a framework for wildlife managers and planners to assess the level of response that would be required to treat exposed wildlife and where spill response equipment might be best stationed. While the size of spill we simulated has a low probability of occurring, it provides an upper limit for planners to consider when crafting response plans.

Groundwater contamination by polycyclic aromatic hydrocarbon due to diesel spill from a telecom base station in a Nigerian City: assessment of human health risk exposure

Diesel pollution of groundwater poses great threat to public health, mainly as a result of the constituent polycyclic aromatic hydrocarbons (PAHs). In this study, the human health risk exposure to polycyclic aromatic hydrocarbons (PAHs) in diesel contaminated groundwater used by several families at Ring Road, Jos, Nigeria (as caused by diesel spill from a telecom base station) was assessed. Prior to the groundwater being treated, the residents were using the water after scooping off the visible diesel sheen for purposes of cooking, washing, and bathing. Until this study, it is not clear whether the groundwater contamination had resulted in sub-chronic exposure of the residents using the water to polycyclic aromatic hydrocarbons (PAHs) to the extent of the PAHs posing a health risk. The diesel contaminated groundwater and uncontaminated nearby groundwater (control) were collected and analyzed for PAHs using gas chromatography-mass spectrometry (GC-MS). The dosage of the dermal and oral ingestion entry routes of PAHs was determined. The estimation of the non-carcinogenic health risk was via hazard quotients (HQ) and the associated hazard index (HI), while the estimation of the carcinogenic health risk was via lifetime cancer risks (LCR) and the associated risk index (RI). Obtained results indicate that the exposure of the residents to the PAHs may have made them susceptible to the risk of non-carcinogenic health effects of benzo(a)pyrene and the carcinogenic health effects of benzo(a)anthracene and benzo(a)pyrene.

Three-dimensional oil dispersion model in the Campos Basin, Brazil

This paper presents the physical and mathematical formulation of a three-dimensional oil dispersion model that calculates the trajectory from the seafloor to the sea surface, its assumptions and constraints. It was developed by researchers who are familiar with oil spill dispersion and mathematical analysis. Oil dispersion is calculated through two computational routines. The first calculates the vertical dispersion along the water column and resamples the droplets when the oil reaches the surface. The second calculates the surface displacement of the spill. This model is based on the Eulerian approach, and it uses numerical solution schemes in time and in space to solve the equation for advective-diffusive transport. A case study based on an actual accident that happened in the Campos Basin, in Rio de Janeiro state, considering the instant spill of 1000 m³ was used to evaluate the proposed model. After calculating the vertical transport, it was estimated that the area covered by the oil spill on the surface was about 35,685 m². After calculating the dispersion at the surface, the plume area was estimated as 20% of the initial area, resulting in a final area of 28,548 m².

Toxicity of Cold Lake Blend and Western Canadian Select dilbits to standard aquatic test species

Dilbits are blends of bitumen and natural gas condensates or crude oils with only limited toxicity data. Two dilbits, Cold Lake Blend and Western Canadian Select, were tested as either unweathered or weathered oils for acute and chronic toxicity to standard freshwater and estuarine organisms. Water accommodated fractions of the dilbits were characterized for total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbons (PAHs), and monoaromatics (BTEX). Acute toxicity of unweathered and weathered dilbits ranged from 4 to 16 mg/L TPH, 8 to 40 μg/L total PAHs, and 0.7 to 16 mg/L BTEX in Ceriodaphnia dubia, Pimephales promelas, Americamysis bahia, and Menidia beryllina. Concentrations of weathered dilbits causing impaired growth (A. bahia) and reproduction (C. dubia) ranged from 0.8 to 3.5 mg/L TPH and 6 to 16 μg/L PAHs. The two dilbits had generally similar acute and short term chronic toxicity expressed as TPH or total PAHs as other crude oils and other petroleum products.

Management of oil spill contamination in the Gulf of Patras caused by an accidental subsea blowout

A methodology is presented and applied to assess the oil contamination probability in the Gulf of Patras and the environmental impacts on the environmentally sensitive area of Mesolongi - Aitoliko coastal lagoons, and to examine the effectiveness of response systems. The procedure consists of the following steps: (1) Determination of the computational domain and the main areas of interest, (2) determination of the drilling sites and oil release characteristics, (3) selection of the simulation periods and collection of environmental data, (4) identification of the species of interest and their characteristics, (5) performance of stochastic calculations and oil contamination probability analysis, (6) determination of the worst-cases, (7) determination of the characteristics of response systems, (8) performance of deterministic calculations, and (9) assessment of the impact of oil spill in the areas of interest. Stochastic calculations that were performed for three typical seasonal weather variations of the year 2015, three oil release sites and specific oil characteristics, showed that there is a considerable probability of oil pollution that reaches 30% in the Mesolongi - Aitoliko lagoons. Based on a simplified approach regarding the characteristic of the sensitive birds and fish in the lagoons, deterministic calculations showed that 78-90% of the bird population and 2-4% of the fish population are expected to be contaminated in the case of an oil spill without any intervention. The use of dispersants reduced the amount of stranded oil by approximately 16-21% and the contaminated bird population of the lagoons to approximately 70%; however, the affected fish population increased to 6-8.5% due to the higher oil concentration in the water column. Mechanical recovery with skimmers "cleaned" almost 10% of the released oil quantity, but it did not have any noticeable effect on the stranded oil and the impacted bird and fish populations.

Development of a statistical oil spill model for risk assessment

To gain a better understanding of the impacts from potential risk sources, we developed an oil spill model using probabilistic method, which simulates numerous oil spill trajectories under varying environmental conditions. The statistical results were quantified from hypothetical oil spills under multiple scenarios, including area affected probability, mean oil slick thickness, and duration of water surface exposed to floating oil. The three sub-indices together with marine area vulnerability are merged to compute the composite index, characterizing the spatial distribution of risk degree. Integral of the index can be used to identify the overall risk from an emission source. The developed model has been successfully applied in comparison to and selection of an appropriate oil port construction location adjacent to a marine protected area for Phoca largha in China. The results highlight the importance of selection of candidates before project construction, since that risk estimation from two adjacent potential sources may turn out to be significantly different regarding hydrodynamic conditions and eco-environmental sensitivity.

Long-term environmental monitoring for assessment of change: measurement inconsistencies over time and potential solutions

The importance of long-term environmental monitoring and research for detecting and understanding changes in ecosystems and human impacts on natural systems is widely acknowledged. Over the last decades, a number of critical components for successful long-term monitoring have been identified. One basic component is quality assurance/quality control protocols to ensure consistency and comparability of data. In Norway, the authorities require environmental monitoring of the impacts of the offshore petroleum industry on the Norwegian continental shelf, and in 1996, a large-scale regional environmental monitoring program was established. As a case study, we used a sub-set of data from this monitoring to explore concepts regarding best practices for long-term environmental monitoring. Specifically, we examined data from physical and chemical sediment samples and benthic macroinvertebrate assemblages from 11 stations from six sampling occasions during the period 1996-2011. Despite the established quality assessment and quality control protocols for this monitoring program, we identified several data challenges, such as missing values and outliers, discrepancies in variable and station names, changes in procedures without calibration, and different taxonomic resolution. Furthermore, we show that the use of different laboratories over time makes it difficult to draw conclusions with regard to some of the observed changes. We offer recommendations to facilitate comparison of data over time. We also present a new procedure to handle different taxonomic resolution, so valuable historical data is not discarded. These topics have a broader relevance and application than for our case study.

Sediment quality benchmarks for assessing oil-related impacts to the deep-sea benthos

Paired sediment contaminant and benthic infaunal data from prior studies following the 2010 Deepwater Horizon (DWH) oil spill in the Gulf of Mexico were analyzed using logistic regression models (LRMs) to derive sediment quality benchmarks for assessing risks of oil-related impacts to the deep-sea benthos. Sediment total polycyclic aromatic hydrocarbon (PAH) and total petroleum hydrocarbon (TPH) concentrations were used as measures of oil exposure. Taxonomic richness (average number of taxa/sample) was selected as the primary benthic response variable. Data are from 37 stations (1300-1700 m water depth) in fine-grained sediments (92%-99% silt-clay) sampled within 200 km of the DWH wellhead (most within 40 km) in 2010 and 32 stations sampled in 2011 (29 of which were common to both years). Results suggest the likelihood of impacts to benthic macrofauna and meiofauna communities is low (<20%) at TPH concentrations of less than 606 mg kg^-1 (ppm dry weight) and 700 mg kg^-1 respectively, high (>80%) at concentrations greater than 2144 mg kg^-1 and 2359 mg kg^-1 respectively, and intermediate at concentrations in between. For total PAHs, the probability of impacts is low (<20%) at concentrations of less than 4.0 mg kg^-1 (ppm) for both macrofauna and meiofauna, high (>80%) at concentrations greater than 24 mg kg^-1 and 25 mg kg^-1 for macrofauna and meiofauna, respectively, and intermediate at concentrations in between. Although numerical sediment quality guidelines (SQGs) are available for total PAHs and other chemical contaminants based on bioeffect data for shallower estuarine, marine, and freshwater biota, to our knowledge, none have been developed for measures of total oil (e.g., TPH) or specifically for deep-sea benthic applications. The benchmarks presented herein provide valuable screening tools for evaluating the biological significance of observed oil concentrations in similar deep-sea sediments following future spills and as potential restoration targets to aid in managing recovery. Integr Environ Assess Manag 2017;13:840-851. Published 2017. This article is a US Government work and is in the public domain in the USA.

Marine Environmental Emergencies in the North Pacific Ocean: Lessons Learned from Recent Oil Spills

Increasing marine vessel traffic, and oil and gas exploration and development throughout the North Pacific basin brings increasing risks of oil spills. Recognizing the serious challenges presented to response authorities, this Special Issue was organized by the North Pacific Marine Science Organization to provide an introduction to the current state of scientific understanding regarding the environmental effects of oil spills. Because interactions of spilled oils with biota and their habitats are complex, the most serious environmental damages from these spills are not necessarily those of greatest immediate concern by the public. Our overarching goal for this Special Issue is to provide an efficient introduction to the most important ways that oil spills can harm biota, habitats, and ecosystems through invited, targeted mini-reviews augmented by original research articles. We provide a brief background on the challenges posed by large oil spills to response authorities, summarize findings from the articles published in this Special Issue, and highlight some key research needs.

Contamination and Human Health Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Oysters After the Wu Yi San Oil Spill in Korea

After the collision of the Singapore-registered oil tanker M/V Wu Yi San into the oil terminal of Yeosu, Korea on January 31, 2014, approximately 900 m³ of oil and oil mixture were released from the ruptured pipelines. The oil affected more than 10 km of coastline along Gwangyang Bay. Emergency oil spill responses recovered bulk oil at sea and cleaned up the stranded oil on shore. As part of an emergency environmental impact assessment, region-wide monitoring of oil contamination in oyster had been conducted for 2 months. Highly elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) were detected at most of the spill affected sites. Four days after the spill, the levels of PAHs in oysters increased dramatically to 627-81,000 ng/g, the average of which was 20 times higher than those found before the spill (321-4040 ng/g). The level of PAHs in these oysters increased until 10 days after the spill and then decreased. Due to the strong tidal current and easterly winter winds, the eastern part of the Bay-the Namhae region-was heavily contaminated compared with other regions. The accumulation and depuration of spilled oil in oyster corresponded with the duration and intensity of the cleanup activities, which is the first field observation in oil spill cases. Human health risk assessments showed that benzo[a]pyrene equivalent concentrations exceeded levels of concern in the highly contaminated sites, even 60 days after the spill.

Advances in Understanding the Fate and Effects of Oil from Accidental Spills in the United States Beginning with the Exxon Valdez

Scientific studies of the environmental effects of oil spills in the United States have produced a steady stream of unexpected discoveries countering prior and often simplistic assumptions. In this brief review, I present how major discoveries from scientific studies of oil spill effects on marine ecosystems and environments, beginning with the 1989 Exxon Valdez, have led to a more informed appreciation for the complexity and the severity of the damage that major spills can do to marine ecosystems and to an increasing recognition that our ability to evaluate those damages is very limited, resulting in a structural bias toward underestimation of adverse environmental effects.

III: Use of biomarkers as Risk Indicators in Environmental Risk Assessment of oil based discharges offshore

Offshore oil and gas activities are required not to cause adverse environmental effects, and risk based management has been established to meet environmental standards. In some risk assessment schemes, Risk Indicators (RIs) are parameters to monitor the development of risk affecting factors. RIs have not yet been established in the Environmental Risk Assessment procedures for management of oil based discharges offshore. This paper evaluates the usefulness of biomarkers as RIs, based on their properties, existing laboratory biomarker data and assessment methods. Data shows several correlations between oil concentrations and biomarker responses, and assessment principles exist that qualify biomarkers for integration into risk procedures. Different ways that these existing biomarkers and methods can be applied as RIs in a probabilistic risk assessment system when linked with whole organism responses are discussed. This can be a useful approach to integrate biomarkers into probabilistic risk assessment related to oil based discharges, representing a potential supplement to information that biomarkers already provide about environmental impact and risk related to these kind of discharges.

II. Species sensitivity distributions based on biomarkers and whole organism responses for integrated impact and risk assessment criteria

The aim of this paper is to bridge gaps between biomarker and whole organism responses related to oil based offshore discharges. These biomarker bridges will facilitate acceptance criteria for biomarker data linked to environmental risk assessment and translate biomarker results to higher order effects. Biomarker based species sensitivity distributions (SSD_biomarkers) have been constructed for relevant groups of biomarkers based on laboratory data from oil exposures. SSD curves express the fraction of species responding to different types of biomarkers. They have been connected to SSDs for whole organism responses (WORs) constructed in order to relate the SSD_biomarkers to animal fitness parameters that are commonly used in environmental risk assessment. The resulting SSD curves show that biomarkers and WORs can be linked through their potentially affected fraction of species (PAF) distributions, enhancing the capability to monitor field parameters with better correlation to impact and risk assessment criteria and providing improved chemical/biological integration.

The GuLF STUDY: A Prospective Study of Persons Involved in the Deepwater Horizon Oil Spill Response and Clean-Up

BACKGROUND

The 2010 Deepwater Horizon disaster led to the largest ever marine oil spill. Individuals who worked on the spill were exposed to toxicants and stressors that could lead to adverse effects.

OBJECTIVES

The GuLF STUDY was designed to investigate relationships between oil spill exposures and multiple potential physical and mental health effects.

METHODS

Participants were recruited by telephone from lists of individuals who worked on the oil spill response and clean-up or received safety training. Enrollment interviews between 2011 and 2013 collected information about spill-related activities, demographics, lifestyle, and health. Exposure measurements taken during the oil spill were used with questionnaire responses to characterize oil exposures of participants. Participants from Gulf states completed a home visit in which biological and environmental samples, anthropometric and clinical measurements, and additional health and lifestyle information were collected. Participants are being followed for changes in health status.

RESULTS

Thirty-two thousand six hundred eight individuals enrolled in the cohort, and 11,193 completed a home visit. Most were young (56.2% ≤ 45 years of age), male (80.8%), lived in a Gulf state (82.3%), and worked at least 1 day on the oil spill (76.5%). Workers were involved in response (18.0%), support operations (17.5%), clean-up on water (17.4%) or land (14.6%), decontamination (14.3%), and administrative support (18.3%). Using an ordinal job exposure matrix, 45% had maximum daily total hydrocarbon exposure levels ≥ 1.0 ppm.

CONCLUSIONS

The GuLF STUDY provides a unique opportunity to study potential adverse health effects from the Deepwater Horizon oil spill.

Post-breeding movements of Ancient Murrelet Synthliboramphus antiquus family groups, subsequent migration of adults and implications for management

Increased shipping in British Columbia (BC) waters poses risks for marine birds from marine oil spills. Ancient Murrelets (Synthliboramphus antiquus), small marine diving birds of which half of the world’s population breeds in BC, are especially susceptible to oiling immediately after departing from their breeding colonies, as their offspring are flightless, constraining their parents to remain with them. In 2014 we deployed geolocator loggers on Ancient Murrelets at four breeding colonies, two on the east and two on the west coast of Haida Gwaii to investigate patterns of post-breeding dispersal and subsequent migratory movements. Birds from east coast colonies moved south and east after leaving their colonies, remaining in Queen Charlotte Sound and adjacent waters for 4–6 weeks, whereas those from west coast colonies moved steadily north and west, so that they left BC waters earlier than those from east coast colonies. These movements were consistent with being driven by surface currents. In June, all birds moved rapidly to the eastern Aleutians, SE Bering Sea, and waters off Kamchatka, where they probably moulted. In August, most moved north, some passing through Bering Straits into the Chukchi Sea. In October-November some birds returned to waters off western N America (33%) and the remainder carried on westwards to waters off Japan, Korea and NE China. For the former group the movement to the Bering Sea in June constituted a moult migration and, as such, is the first described for an auk. Those birds wintering in Asia began moving east in February and arrived off BC in March, when observations at colonies show that burrow visits begin in Haida Gwaii. Our data suggest that, immediately after colony departure, birds from the east coast colonies (about half the population of Haida Gwaii) are at higher risk from potential oil spills in northern British Columbia waters than those breeding on the west coast.

A multi-attribute methodology for the prioritisation of oil contaminated sites in the Niger Delta

The Ogoniland region of the Niger Delta contains a vast number of sites contaminated with petroleum hydrocarbons that originated from Nigeria's active oil sector. The United Nations Environment Programme (UNEP) reported on this widespread contamination in 2011, however, wide-scale action to clean-up these sites has yet to be initiated. A challenge for decision makers responsible for the clean-up of these sites has been the prioritisation of sites to enable appropriate allocation of scarce resources. In this study, a risk-based multi-criteria decision analysis framework was used to prioritise high-risk sites contaminated with petroleum hydrocarbons in the Ogoniland region of Nigeria. The prioritisation method used a set of risk-based attributes that took into account chemical and ecological impacts, as well as socio-economic impacts, providing a holistic assessment of the risk. Data for the analysis was taken from the UNEP Environmental Assessment of Ogoniland, where over 110 communities were assessed for oil-contamination. Results from our prioritisation show that the highest-ranking sites were not necessarily the sites with the highest observed level of hydrocarbon contamination. This differentiation was due to our use of proximity as a surrogate measure for likelihood of exposure. Composite measures of risk provide a more robust assessment, and can enrich discussions about risk management and the allocation of resources for the clean-up of affected sites.

Are environmental risk estimations linked to the actual environmental impact? Application to an oil handling facility (NE Spain)

The environmental risk analysis of aquatic systems includes the evaluation of the likelihood that adverse ecological effects may occur as a result of exposure to one or more stressors. In harbor areas, pollution is provided by a complex mixture of substances with different levels of toxicity, persistence and bioaccumulation, which complicates the hazards characterization and their multiple effects. A study of the relationship between the environmental impact and the environmental risk assessment at a specific isolated oil handling facility was undertaken. The environmental risk of the oil handling facility, considering the consequences of specific pollutants, was estimated and the associated environmental impact was quantified based on a 'weights of evidence' approach. The contamination quantified at the potentially affected area around the monobuoy of Tarragona has proved to be related with environmental risk estimations but the lines of evidence obtained do not allow us to assert that the activity developed at this facility has an associated environmental impact.

Preparing for the unprecedented - Towards quantitative oil risk assessment in the Arctic marine areas

The probability of major oil accidents in Arctic seas is increasing alongside with increasing maritime traffic. Hence, there is a growing need to understand the risks posed by oil spills to these unique and sensitive areas. So far these risks have mainly been acknowledged in terms of qualitative descriptions. We introduce a probabilistic framework, based on a general food web approach, to analyze ecological impacts of oil spills. We argue that the food web approach based on key functional groups is more appropriate for providing holistic view of the involved risks than assessments based on single species. We discuss the issues characteristic to the Arctic that need a special attention in risk assessment, and provide examples how to proceed towards quantitative risk estimates. The conceptual model presented in the paper helps to identify the most important risk factors and can be used as a template for more detailed risk assessments.

The spatiotemporal characteristics of environmental hazards caused by offshore oil and gas operations in the Gulf of Mexico

Marine ecosystems are home to a host of numerous species ranging from tiny planktonic organisms, fishes, and birds, to large mammals such as the whales, manatees, and seals. However, human activities such as offshore oil and gas operations increasingly threaten marine and coastal ecosystems, for which there has been little exploration into the spatial and temporal risks of offshore oil operations. Using the Gulf of Mexico, one of the world's hottest spots of offshore oil and gas mining, as the study area, we propose a spatiotemporal approach that integrates spatial statistics and geostatistics in a geographic information system environment to provide insight to environmental management and decision making for oil and gas operators, coastal communities, local governments, and the federal government. We use the records from 1995 to 2015 of twelve types of hazards caused by offshore oil and gas operations, and analyze them spatially over a five year period. The spatial clusters of these hazards are analyzed and mapped using Getis-Ord Gi and local Moran's I statistics. We then design a spatial correlation coefficient matrix for multivariate spatial correlation, which is the ratio of the cross variogram of two types of hazards to the product of the variograms of the two hazards, showing a primary understanding of the degrees of spatial correlation among the twelve types hazards. To the best of our knowledge, it is the first application of spatiotemporal analysis methods to environmental hazards caused by offshore oil and gas operations; the proposed methods can be applied to other regions for the management and monitoring of environmental hazards caused by offshore oil operations.

Oil spill impacts on mangroves: Recommendations for operational planning and action based on a global review

Mangrove tidal wetland habitats are recognised as highly vulnerable to large and chronic oil spills. This review of current literature and public databases covers the last 6 decades, summarising global data on oil spill incidents affecting, or likely to have affected, mangrove habitat. Over this period, there have been at least 238 notable oil spills along mangrove shorelines worldwide. In total, at least 5.5milliontonnes of oil has been released into mangrove-lined, coastal waters, oiling possibly up to around 1.94millionha of mangrove habitat, and killing at least 126,000ha of mangrove vegetation since 1958. However, there were assessment limitations with incomplete and unavailable data, as well as unequal coverage across world regions. To redress the gaps described here in reporting on oil spill impacts on mangroves and their recovery worldwide, a number of recommendations and suggestions are made for refreshing and updating standard operational procedures for responders, managers and researchers alike.

The Deepwater Horizon Oil Spill and Physical Health among Adult Women in Southern Louisiana: The Women and Their Children's Health (WaTCH) Study

BACKGROUND

The Deepwater Horizon Oil Spill (DHOS) is the largest oil spill in U.S. history, negatively impacting Gulf Coast residents and the surrounding ecosystem. To date, no studies have been published concerning physical health outcomes associated with the DHOS in the general community.

OBJECTIVES

We characterized individual DHOS exposure using survey data and examined the association between DHOS exposure and physical health.

METHODS

Baseline data from 2,126 adult women residing in southern Louisiana and enrolled in the Women and Their Children's Health study were analyzed. Exploratory factor analysis was used to characterize DHOS exposure. Odds ratios and 95% confidence intervals for the associations between DHOS exposure and physical health symptoms were estimated using multivariate logistic regression.

RESULTS

A two-factor solution was identified as the best fit for DHOS exposure: physical-environmental exposure and economic exposure. High physical-environmental exposure was significantly associated with all of the physical health symptoms, with the strongest associations for burning in nose, throat, or lungs (OR = 4.73; 95% CI: 3.10, 7.22), sore throat (OR = 4.66; 95% CI: 2.89, 7.51), dizziness (OR = 4.21; 95% CI: 2.69, 6.58), and wheezing (OR = 4.20; 95% CI: 2.86, 6.17). Women who had high-economic exposure were significantly more likely to report wheezing (OR = 1.92; 95% CI: 1.32, 2.79); headaches (OR = 1.81; 95% CI: 1.41, 2.58); watery, burning, itchy eyes (OR = 1.61; 95% CI: 1.20, 2.16); and stuffy, itchy, runny nose (OR = 1.56; 95% CI: 1.16, 2.08).

CONCLUSIONS

Among southern Louisiana women, both physical-environmental and economic exposure to the DHOS were associated with an increase in self-reported physical health outcomes. Additional longitudinal studies of this unique cohort are needed to elucidate the impact of the DHOS on short- and long-term human health.

CITATION

Peres LC, Trapido E, Rung AL, Harrington DJ, Oral E, Fang Z, Fontham E, Peters ES. 2016. The Deepwater Horizon Oil Spill and physical health among adult women in southern Louisiana: the Women and Their Children's Health (WaTCH) study. Environ Health Perspect 124:1208-1213; http://dx.doi.org/10.1289/ehp.1510348.

Modeling oil weathering and transport in sea ice

This paper presents a model of oil weathering and transport in sea ice. It contains a model formulation and scenario simulation to test the proposed model. The model formulation is based on state-of-the-art models for individual weathering and transport processes. The approach incorporates the dependency of weathering and transport processes on each other, as well as their simultaneous occurrence after an oil spill in sea ice. The model is calibrated with available experimental data. The experimental data and model prediction show close agreement. A sensitivity analysis is conducted to determine the most sensitive parameters in the model. The model is useful for contingency planning of a potential oil spill in sea ice. It is suitable for coupling with a level IV fugacity model, to estimate the concentration and persistence of hydrocarbons in air, ice, water and sediments for risk assessment purposes.

A-DROP: A predictive model for the formation of oil particle aggregates (OPAs)

Oil-particle interactions play a major role in removal of free oil from the water column. We present a new conceptual-numerical model, A-DROP, to predict oil amount trapped in oil-particle aggregates. A new conceptual formulation of oil-particle coagulation efficiency is introduced to account for the effects of oil stabilization by particles, particle hydrophobicity, and oil-particle size ratio on OPA formation. A-DROP was able to closely reproduce the oil trapping efficiency reported in experimental studies. The model was then used to simulate the OPA formation in a typical nearshore environment. Modeling results indicate that the increase of particle concentration in the swash zone would speed up the oil-particle interaction process; but the oil amount trapped in OPAs did not correspond to the increase of particle concentration. The developed A-DROP model could become an important tool in understanding the natural removal of oil and developing oil spill countermeasures by means of oil-particle aggregation.

Simulation of oil pollution in the Persian Gulf near Assaluyeh oil terminal

Numerical simulation of oil slick movement with respect to tidal factors and wind effects was performed in order to counteract oil pollution in the Persian Gulf. First, a flow model was invoked with respect to water level fluctuations. The main tidal constituents were applied to the model using the initial conditions of water level variations in the Hormuz Strait near the Hangam Island. The movement of oil pollution was determined due to wind, tide and temperature effects and confirmed by applying a verified field results. Simulations were focused near an important terminal in the Persian Gulf, Assaluyeh Port. The results were led to preparing a risk-taking map in a parallel research for the Persian Gulf.

Assessment of sediment hydrocarbon contamination from the 2009 Montara oil blow out in the Timor Sea

In August 2009, a blowout of the Montara H1 well 260 km off the northwest coast of Australia resulted in the uncontrolled release of about 4.7 M L of light crude oil and gaseous hydrocarbons into the Timor Sea. Over the 74 day period of the spill, the oil remained offshore and did not result in shoreline incidents on the Australia mainland. At various times slicks were sighted over a 90,000 km(2) area, forming a layer of oil which was tracked by airplanes and satellites but the slicks typically remained within 35 km of the well head platform and were treated with 183,000 L of dispersants. The shelf area where the spill occurred is shallow (100-200 m) and includes off shore emergent reefs and cays and submerged banks and shoals. This study describes the increased inputs of oil to the system and assesses the environmental impact. Concentrations of hydrocarbon in the sediment at the time of survey were very low (total aromatic hydrocarbons (PAHs) ranged from 0.04 to 31 ng g(-1)) and were orders of magnitude lower than concentrations at which biological effects would be expected.

The use of sensory perception indicators for improving the characterization and modelling of total petroleum hydrocarbon (TPH) grade in soils

This paper proposes a multistep approach for creating a 3D stochastic model of total petroleum hydrocarbon (TPH) grade in potentially polluted soils of a deactivated oil storage site by using chemical analysis results as primary or hard data and classes of sensory perception variables as secondary or soft data. First, the statistical relationship between the sensory perception variables (e.g. colour, odour and oil-water reaction) and TPH grade is analysed, after which the sensory perception variable exhibiting the highest correlation is selected (oil-water reaction in this case study). The probabilities of cells belonging to classes of oil-water reaction are then estimated for the entire soil volume using indicator kriging. Next, local histograms of TPH grade for each grid cell are computed, combining the probabilities of belonging to a specific sensory perception indicator class and conditional to the simulated values of TPH grade. Finally, simulated images of TPH grade are generated by using the P-field simulation algorithm, utilising the local histograms of TPH grade for each grid cell. The set of simulated TPH values allows several calculations to be performed, such as average values, local uncertainties and the probability of the TPH grade of the soil exceeding a specific threshold value.

An Evaluation of Select Test Variables Potentially Affecting Acute Oil Toxicity

In the wake of the Deepwater Horizon incident (2010) in the Gulf of Mexico, an abundance of research studies have been performed, but the methodologies used have varied making comparisons and replication difficult. In this study, acute toxicity tests with mysids and inland silversides were performed to examine the effect of different variables on test results. The toxicity test variables evaluated in this study included (1) open versus closed static test chambers, (2) natural versus artificial diluent, (3) aerated versus nonaerated test solution, and (4) low versus medium energy water-accommodated (WAF) mixing energies. The use of tests using natural or artificial diluent showed no difference in either toxicity test or analytical chemistry results. Based on median lethal concentrations (LC50) of WAFs of unweathered oil (MASS), mysid tests performed in closed chambers were approximately 41 % lower than LC50 values from open-chamber studies, possibly a result of the presence of low-molecular weight volatile aromatics (i.e., naphthalenes). This research also showed that using a medium-energy WAF (with a 20–25 % vortex) increases the number of chemical components compared with low-energy WAF, thus affecting the composition of the exposure media and increasing toxicity. The comparison of toxic units as a measure of the potential toxicity of fresh and weathered oils showed that weathered oils (e.g., Juniper, CTC) are less toxic than the unweathered MASS oil. In the event of future oil spills, these variables should be considered to ensure that data regarding the potential toxicity and environmental risk are of good quality and reproducible.

The effects of weathering and chemical dispersion on Deepwater Horizon crude oil toxicity to mahi-mahi (Coryphaena hippurus) early life stages

To better understand the impact of the Deepwater Horizon (DWH) incident on commercially and ecologically important pelagic fish species, a mahi-mahi spawning program was developed to assess the effect of embryonic exposure to DWH crude oil with particular emphasis on the effects of weathering and dispersant on the magnitude of toxicity. Acute lethality (96 h LC50) ranged from 45.8 (28.4-63.1) μg l(-1) ΣPAH for wellhead (source) oil to 8.8 (7.4-10.3) μg l(-1) ΣPAH for samples collected from the surface slick, reinforcing previous work that weathered oil is more toxic on a ΣPAH basis. Differences in toxicity appear related to the amount of dissolved 3 ringed PAHs. The dispersant Corexit 9500 did not influence acute lethality of oil preparations. Embryonic oil exposure resulted in cardiotoxicity after 48 h, as evident from pericardial edema and reduced atrial contractility. Whereas pericardial edema appeared to correlate well with acute lethality at 96 h, atrial contractility did not. However, sub-lethal cardiotoxicity may impact long-term performance and survival. Dispersant did not affect the occurrence of pericardial edema; however, there was an apparent reduction in atrial contractility at 48 h of exposure. Pericardial edema at 48 h and lethality at 96 h were equally sensitive endpoints in mahi-mahi.

Long-term effects of discharges of produced water the marine environment from petroleum-related activities at Sonda de Campeche, Gulf of México

Produced water from offshore oil platforms is a major source of oil and related chemicals into the sea. The large volume and high salinity of produced water could pose severe environmental impacts upon inadequate disposal. This study is based on direct field sampling of effluents released into the ocean in the years 2003 and 2013 at the Sonda de Campeche located in the southern part of the Gulf of Mexico. Metals and hydrocarbons were characterized in water, sediments, and fish tissues at the discharge site and compared with those obtained at two reference sites. Chemicals that exceeded risk-based concentrations in the discharge included the metals As, Pb, Cd, and Cr, and a variety of compounds polycyclic aromatic hydrocarbon (PAHs), including naphthalene, fluorenes, and low molecular weight PAHs. The values of low to high molecular weight polycyclic aromatic hydrocarbon (PAHs), and carbon preference index indicate that hydrocarbons in sediments of the discharge zone are originated from the produced water and combustion sources. Fish tissues at the discharge zone and reference site are contaminated with PAHs, dominated by 2- and 3-rings; 4-ring accounted for less than 1% of total PAHs (TPAHs) in 2003, but increased to 7% in 2013. Results suggest that, from 2003 to 2013, discharges of produced water have had a non-negligible impact on ecosystems at a regional level, so the possibility of subtle, cumulative effects from operational discharges should not be ignored.

Identifying the source of tar balls deposited along the beaches of Goa in 2013 and comparing with historical data collected along the West Coast of India

Deposition of oil residues, also known as tar balls, is a seasonal phenomenon, and it occurs only in the southwest monsoon season along the west coast of India. This has become a serious environmental issue, as Goa is a global tourist destination. The present work aims at identifying the source oil of the tar balls that consistently depositing along the Goa coast using multi-marker fingerprint technique. In this context, the tar ball samples collected in May 2013 from 9 beaches of Goa coast and crude oils from different oil fields and grounded ship were subject to multi-marker analyses such as n-alkanes, pentacyclic terpanes, regular steranes, compound specific isotope analysis (CSIA) and principle component analysis (PCA). The n-alkane weathering index shows that samples have been weathered to various degrees, and the status of weathering is moderate. Since the international tanker route passes closer to the west coast of India (WCI), it is generally presumed that tanker wash is the source of the tar balls. We found that 2010/2011 tar balls are as tanker wash, but the present study demonstrates that the Bombay High (BH) oil fields can also contribute to oil contamination (tar balls) along ≈ 650 km stretch of the WCI, running from Gujarat in the north to Goa in the south. The simulated trajectories show that all the particles released in April traveled in the southeast direction, and by May, they reached the Goa coast with the influence of circulation of Indian monsoon system.

A probabilistic approach for a cost-benefit analysis of oil spill management under uncertainty: A Bayesian network model for the Gulf of Finland

Large-scale oil accidents can inflict substantial costs to the society, as they typically result in expensive oil combating and waste treatment operations and have negative impacts on recreational and environmental values. Cost-benefit analysis (CBA) offers a way to assess the economic efficiency of management measures capable of mitigating the adverse effects. However, the irregular occurrence of spills combined with uncertainties related to the possible effects makes the analysis a challenging task. We develop a probabilistic modeling approach for a CBA of oil spill management and apply it in the Gulf of Finland, the Baltic Sea. The model has a causal structure, and it covers a large number of factors relevant to the realistic description of oil spills, as well as the costs of oil combating operations at open sea, shoreline clean-up, and waste treatment activities. Further, to describe the effects on environmental benefits, we use data from a contingent valuation survey. The results encourage seeking for cost-effective preventive measures, and emphasize the importance of the inclusion of the costs related to waste treatment and environmental values in the analysis. Although the model is developed for a specific area, the methodology is applicable also to other areas facing the risk of oil spills as well as to other fields that need to cope with the challenging combination of low probabilities, high losses and major uncertainties.

Intercomparison of oil spill prediction models for accidental blowout scenarios with and without subsea chemical dispersant injection

We compare oil spill model predictions for a prototype subsea blowout with and without subsea injection of chemical dispersants in deep and shallow water, for high and low gas-oil ratio, and in weak to strong crossflows. Model results are compared for initial oil droplet size distribution, the nearfield plume, and the farfield Lagrangian particle tracking stage of hydrocarbon transport. For the conditions tested (a blowout with oil flow rate of 20,000 bbl/d, about 1/3 of the Deepwater Horizon), the models predict the volume median droplet diameter at the source to range from 0.3 to 6mm without dispersant and 0.01 to 0.8 mm with dispersant. This reduced droplet size owing to reduced interfacial tension results in a one to two order of magnitude increase in the downstream displacement of the initial oil surfacing zone and may lead to a significant fraction of the spilled oil not reaching the sea surface.

The use of diagnostic ratios, biomarkers and 3-way Kohonen neural networks to monitor the temporal evolution of oil spills

Oil spill identification relies usually on a wealth of chromatographic data which requires advanced data treatment (chemometrics). A simple approach based on Kohonen neural networks to handle three-dimensional arrays is presented. A suite of 28 diagnostic ratios was considered to monitor six oils along four months. It was found that some traditional diagnostic ratios were not stable enough. In particular, alkylated PAHs (e.g. 1-methyldibenzothiophene, 4-methylpyrene, 27bbSTER and the TA21 and TA26 triaromatic steroids) seemed less resistant to medium-weathering than biomarkers. One (or two) ratios were found to differentiate each product: 30O, 28ab (and 25nor30ab), C3-dbt/C3-phe, 27Ts, TA26 and 29Ts characterized Ashtart, Brent, Maya, Sahara, IFO and Prestige oils, respectively.