Marine oil spill risk mapping for accidental pollution and its application in a coastal city

Accidental marine oil spill pollution can result in severe environmental, ecological, economic and other consequences. This paper discussed the model of Marine Oil Spill Risk Mapping (MOSRM), which was constructed as follows: (1) proposing a marine oil spill risk system based on the typical marine oil spill pollution accidents and prevailing risk theories; (2) identifying suitable indexes that are supported by quantitative sub-indexes; (3) constructing the risk measuring models according to the actual interactions between the factors in the risk system; and (4) assessing marine oil spill risk on coastal city scale with GIS to map the overall risk. The case study of accidental marine oil spill pollution in the coastal area of Dalian, China was used to demonstrate the effectiveness of the model. The coastal areas of Dalian were divided into three zones with risk degrees of high, medium, and low. And detailed countermeasures were proposed for specific risk zones.

Hydrophobic poly(alkoxysilane) organogels as sorbent material for oil spill cleanup

In this study, reusable poly(alkoxysilane) organogels with high absorption capacities were synthesized by the condensation of a cyclo aliphatic glycol (UNOXOL™) and altering the chain length of the alkyltriethoxysilanes. The structural and thermal properties of cross-linked poly(alkoxysilane) polymers were determined by FTIR, solid-state (13)C and (29)Si CPMAS NMR and TGA. The oil absorbency of poly(alkoxysilane)s was determined through oil absorption tests, absorption and desorption kinetics. Results showed that the highest oil absorbency capacities were found to be 295% for hexane, 389% for euro diesel, 428% for crude oil, 652% for gasoline, 792% for benzene, 792% for toluene, 868% for tetrahydrofuran, and 1060% for dichloromethane for the poly(alkoxysilane) gels based on UNOXOL™ and dodecyltriethoxysilane. Owing to their hydrophobic structure, the poly(alkoxysilane) organogels can selectively absorb crude oil from water. The reusability of the absorbents was quantitatively investigated, demonstrating that absorbents can be used effectively at least nine times.

DNA damage caused by organic extracts of contaminated sediment, crude, and weathered oil and their fractions recovered up to 5 years after the 2007 Hebei Spirit oil spill off Korea

We examined the degree of DNA damage caused by three fractions (F1, aliphatic hydrocarbons; F2, aromatic hydrocarbons; and F3, polar compounds) of the organic extract of sediments taken from Taean, Korea, following the Hebei Spirit oil spill. DNA damage was measured using the comet assay with blood cells of the striped beakfish (Oplegnathus fasciatus). DNA damage was also examined for fractions of crude oil (Iranian Heavy Crude Oil, IHC), weathered oil and six subfractions (F2.1-F2.6). The greatest DNA damage was found from the Sinduri dune region and DNA damage decreased to 40% weathered oil in F2 fraction compared with crude oil. The DNA damage of the sum of fractions was found higher than the organic extracts of sediments, suggesting antagonistic interactions between the genotoxic compounds. This study confirmed the persistence of potential genotoxicity in sediments of the severely affected regions as long as 5 years after the oil spill.

Relative bioavailability and toxicity of fuel oils leaking from World War II shipwrecks

The Norwegian Authorities have classified 30 WWII shipwrecks to have a considerable potential for pollution to the environment, based on the location and condition of the wreck and the types and amount of fuel. Oil thus far has been removed from eight of these shipwrecks. The water accommodated fractions of oils from two British wrecks and two German wrecks have been studied with special emphasis on chemistry and biological effects (algae growth (Skeletonema costatum) and copepod mortality (Calanus finmarchicus)). Chemical analyses were also performed on three additional German wreck oils. The results from these studies show that the coal based oils from German WWII shipwrecks have higher toxicity to marine organisms than the mineral oils from the British shipwrecks. The potential for higher impact on the marine environment of coal based oils has resulted in an altering of the priority list for oil recovery from WWII wrecks by the authorities.

Development of a hybrid proximal sensing method for rapid identification of petroleum contaminated soils

Using 108 petroleum contaminated soil samples, this pilot study proposed a new analytical approach of combining visible near-infrared diffuse reflectance spectroscopy (VisNIR DRS) and portable X-ray fluorescence spectrometry (PXRF) for rapid and improved quantification of soil petroleum contamination. Results indicated that an advanced fused model where VisNIR DRS spectra-based penalized spline regression (PSR) was used to predict total petroleum hydrocarbon followed by PXRF elemental data-based random forest regression was used to model the PSR residuals, it outperformed (R(2)=0.78, residual prediction deviation (RPD)=2.19) all other models tested, even producing better generalization than using VisNIR DRS alone (RPD's of 1.64, 1.86, and 1.96 for random forest, penalized spline regression, and partial least squares regression, respectively). Additionally, unsupervised principal component analysis using the PXRF+VisNIR DRS system qualitatively separated contaminated soils from control samples.

CAPSULE

Fusion of PXRF elemental data and VisNIR derivative spectra produced an optimized model for total petroleum hydrocarbon quantification in soils.

Natural dispersion revisited

This paper presents a new semi-empirical model for oil droplet size distributions generated by single breaking wave events. Empirical data was obtained from laboratory experiments with different crude oils at different stages of weathering. The paper starts with a review of the most commonly used model for natural dispersion, which is followed by a presentation of the laboratory study on oil droplet size distributions formed by breaking waves conducted by SINTEF on behalf of the NOAA/UNH Coastal Response Research Center. The next section presents the theoretical and empirical foundation for the new model. The model is based on dimensional analysis and contains two non-dimensional groups; the Weber and Reynolds number. The model was validated with data from a full scale experimental oil spill conducted in the Haltenbanken area offshore Norway in July 1982, as described in the last section of the paper.

Potential oil spill risk from shipping and the implications for management in the Caribbean Sea

The semi enclosed Caribbean Sea is ranked as having one of the most intense maritime traffic in the world. These maritime activities have led to significant oil pollution. Simultaneously, this sea supports many critical habitats functioning as a Large Marine Ecosystem (LME). While the impacts of oil pollution are recognised, a number of management challenges remain. This study applies spatial modelling to identify critical areas potentially at risk from oil spills in the form of a potential oil spill risk (POSR) model. The model indicates that approximately 83% of the sea could be potentially impacted by oil spills due to shipping. The results from this study collectively support a management framework for minimising ship generated oil pollution in the Caribbean Sea. Among the recommended components are a common policy, surveillance and monitoring controls, standards, monitoring programmes, data collection and greater rates of convention ratifications.

Predictive modeling of subsurface shoreline oil encounter probability from the Exxon Valdez oil spill in Prince William Sound, Alaska

To better understand the distribution of remaining lingering subsurface oil residues from the Exxon Valdez oil spill (EVOS) along the shorelines of Prince William Sound (PWS), AK, we revised previous modeling efforts to allow spatially explicit predictions of the distribution of subsurface oil. We used a set of pooled field data and predictor variables stored as Geographic Information Systems (GIS) data to generate calibrated boosted tree models predicting the encounter probability of different categories of subsurface oil. The models demonstrated excellent predictive performance as evaluated by cross-validated performance statistics. While the average encounter probabilities at most shoreline locations are low across western PWS, clusters of shoreline locations with elevated encounter probabilities remain in the northern parts of the PWS, as well as more isolated locations. These results can be applied to estimate the location and amount of remaining oil, evaluate potential ongoing impacts, and guide remediation. This is the first application of quantitative machine-learning based modeling techniques in estimating the likelihood of ongoing, long-term shoreline oil persistence after a major oil spill.

A targeted health risk assessment following the Deepwater Horizon oil spill: polycyclic aromatic hydrocarbon exposure in Vietnamese-American shrimp consumers

BACKGROUND

The Deepwater Horizon oil spill of 2010 prompted concern about health risks among seafood consumers exposed to polycyclic aromatic hydrocarbons (PAHs) via consumption of contaminated seafood.

OBJECTIVE

The objective of this study was to conduct population-specific probabilistic health risk assessments based on consumption of locally harvested white shrimp (Litopenaeus setiferus) among Vietnamese Americans in southeast Louisiana.

METHODS

We conducted a survey of Vietnamese Americans in southeast Louisiana to evaluate shrimp consumption, preparation methods, and body weight among shrimp consumers in the disaster-impacted region. We also collected and chemically analyzed locally harvested white shrimp for 81 individual PAHs. We combined the PAH levels (with accepted reference doses) found in the shrimp with the survey data to conduct Monte Carlo simulations for probabilistic noncancer health risk assessments. We also conducted probabilistic cancer risk assessments using relative potency factors (RPFs) to estimate cancer risks from the intake of PAHs from white shrimp.

RESULTS

Monte Carlo simulations were used to generate hazard quotient distributions for noncancer health risks, reported as mean ± SD, for naphthalene (1.8 × 10-4 ± 3.3 × 10-4), fluorene (2.4 × 10-5 ± 3.3 × 10-5), anthracene (3.9 × 10-6 ± 5.4 × 10-6), pyrene (3.2 × 10-5 ± 4.3 × 10-5), and fluoranthene (1.8 × 10-4 ± 3.3 × 10-4). A cancer risk distribution, based on RPF-adjusted PAH intake, was also generated (2.4 × 10-7 ± 3.9 × 10-7).

CONCLUSIONS

The risk assessment results show no acute health risks or excess cancer risk associated with consumption of shrimp containing the levels of PAHs detected in our study, even among frequent shrimp consumers.

GC estimation of organic hydrocarbons that threaten shallow Quaternary sandy aquifer Northwestern Gulf of Suez, Egypt

Soil and groundwater contamination is one of the important environmental problems at petroleum-related sites, which causes critical environmental and health defects. Severe petroleum hydrocarbon contamination from coastal refinery plant was detected in a shallow Quaternary sandy aquifer is bordered by Gulf in the Northwestern Gulf of Suez, Egypt. The overall objective of this investigation is to estimate the organic hydrocarbons in shallow sandy aquifers, released from continuous major point-source of pollution over a long period of time (91 years ago). This oil refinery contamination resulted mainly in the improper disposal of hydrocarbons and produced water releases caused by equipment failures, vandalism, and accidents that caused direct groundwater pollution or discharge into the gulf. In order to determine the fate of hydrocarbons, detailed field investigations were made to provide intensive deep profile information. Eight composite randomly sediment samples from a test plot were selected for demonstration. The tested plot was 50 m long × 50 m wide × 70 cm deep. Sediment samples were collected using an American auger around the point 29° 57' 33″ N and 32° 30' 40″ E in 2012 and covered an area of 2,500 m(2) which represents nearly 1/15 of total plant area (the total area of the plant is approximately 3.250 km(2)). The detected total petroleum hydrocarbons (TPHs) were 2.44, 2.62, 4.54, 4.78, 2.83, 3.22, 2.56, and 3.13 wt%, respectively. TPH was calculated by differences in weight and subjected to gas chromatography (GC). Hydrocarbons were analyzed on Hewlett-Packard (HP-7890 plus) gas chromatograph equipped with a flame ionization detector (FID). The percentage of paraffine of the investigated TPH samples was 7.33, 7.24, 7.58, 8.25, 10.25, 9.89, 14.77, and 17.53 wt%, respectively.

A Monte Carlo simulation based two-stage adaptive resonance theory mapping approach for offshore oil spill vulnerability index classification

In this paper, a Monte Carlo simulation based two-stage adaptive resonance theory mapping (MC-TSAM) model was developed to classify a given site into distinguished zones representing different levels of offshore Oil Spill Vulnerability Index (OSVI). It consisted of an adaptive resonance theory (ART) module, an ART Mapping module, and a centroid determination module. Monte Carlo simulation was integrated with the TSAM approach to address uncertainties that widely exist in site conditions. The applicability of the proposed model was validated by classifying a large coastal area, which was surrounded by potential oil spill sources, based on 12 features. Statistical analysis of the results indicated that the classification process was affected by multiple features instead of one single feature. The classification results also provided the least or desired number of zones which can sufficiently represent the levels of offshore OSVI in an area under uncertainty and complexity, saving time and budget in spill monitoring and response.

A three-step model to assess shoreline and offshore susceptibility to oil spills: the South Aegean (Crete) as an analogue for confined marine basins

This study combines bathymetric, geomorphological, geological data and oil spill predictions to model the impact of oil spills in two accident scenarios from offshore Crete, Eastern Mediterranean. The aim is to present a new three-step method of use by emergency teams and local authorities in the assessment of shoreline and offshore susceptibility to oil spills. The three-step method comprises: (1) real-time analyses of bathymetric, geomorphological, geological and oceanographic data; (2) oil dispersion simulations under known wind and sea current conditions; and (3) the compilation of final hazard maps based on information from (1) and (2) and on shoreline susceptibility data. The results in this paper show that zones of high to very-high susceptibility around the island of Crete are related to: (a) offshore bathymetric features, including the presence of offshore scarps and seamounts; (b) shoreline geology, and (c) the presence near the shore of sedimentary basins filled with unconsolidated deposits of high permeability. Oil spills, under particular weather and oceanographic conditions, may quickly spread and reach the shoreline 5-96 h after the initial accident. As a corollary of this work, we present the South Aegean region around Crete as a valid case-study for confined marine basins, narrow seaways, or interior seas around island groups.

The effect of sand composition on the degradation of buried oil

The potential effects of the mineralogical composition of sediment on the degradation of oil buried on sandy beaches were investigated. Toward that purpose, a laboratory experiment was carried out with sandy sediment collected along NW Iberian Peninsula beaches, tar-balls from the Prestige oil spill (NW Spain) and seawater. The results indicate that the mineralogical composition is important for the physical appearance of the oil (tar-balls or oil coatings). This finding prompted a reassessment of the current sequence of degradation for buried oil based on compositional factors. Moreover, the halo development of the oil coatings might be enhanced by the carbonate concentration of the sand. These findings open new prospects for future monitoring and management programs for oiled sandy beaches.

Statistics of extremes in oil spill risk analysis

The Deepwater Horizon oil spill (DWH) in 2010 in the Gulf of Mexico is the largest accidental marine oil spill in the history of the petroleum industry. After DWH, key questions were asked: What is the likelihood that a similar catastrophic oil spill (with a volume over 1 million barrels) will happen again? Is DWH an extreme event or will it happen frequently in the future? The extreme value theory (EVT) has been widely used in studying rare events, including damage from hurricanes, stock market crashes, insurance claims, flooding, and earthquakes. In this paper, the EVT is applied to analyze oil spills in the U.S. outer continental shelf (OCS). Incorporating the 49 years (1964-2012) of OCS oil spill data, the EVT is capable of describing the oil spills reasonably well. The return period of a catastrophic oil spill in OCS areas is estimated to be 165 years, with a 95% confidence interval between 41 years and more than 500 years. Sensitivity tests indicate that the EVT results are relatively stable. The results of this study are very useful for oil spill risk assessment, contingency planning, and environmental impact statements on oil exploration, development, and production.

Mapping polycyclic aromatic hydrocarbon and total toxicity equivalent soil concentrations by visible and near-infrared spectroscopy

In this study, we used data from spectroscopic models based on visible and near-infrared (vis-NIR; 350-2500 nm) diffuse reflectance spectroscopy to develop soil maps of polycyclic aromatic hydrocarbons (PAHs) and total toxicity equivalent concentrations (TTEC) of the PAH mixture. The TTEC maps were then used for hazard assessment of three petroleum release sites in the Niger Delta province of Nigeria (5.317°N, 6.467°E). As the paired t-test revealed, there were non-significant (p > 0.05) differences between soil maps of PAH and TTEC developed with chemically measured and vis-NIR-predicted data. Comparison maps of PAH showed a slight to moderate agreement between measured and predicted data (Kappa coefficient = 0.19-0.56). Using proposed generic assessment criteria, hazard assessment showed that the degree of action for site-specific risk assessment and/or remediation is similar for both measurement methods. This demonstrates that the vis-NIR method may be useful for monitoring hydrocarbon contamination in a petroleum release site.

Disutility analysis of oil spills: graphs and trends

This paper reports the results of an analysis of oil spill cost data assembled from a worldwide pollution database that mainly includes data from the International Oil Pollution Compensation Fund. The purpose of the study is to analyze the conditions of marine pollution accidents and the factors that impact the costs of oil spills worldwide. The accidents are classified into categories based on their characteristics, and the cases are compared using charts to show how the costs are affected under all conditions. This study can be used as a helpful reference for developing a detailed statistical model that is capable of reliably and realistically estimating the total costs of oil spills. To illustrate the differences identified by this statistical analysis, the results are compared with the results of previous studies, and the findings are discussed.

Three dimensional simulation of transport and fate of oil spill under wave induced circulation

An oil spill model is developed and coupled to a current-wave model to simulate oil spill transport in aquatic environments where waves are present. The oil spill model incorporates physical-chemical processes of oil spill, and simulates oil slick transport by a circulation-driven Lagrangian Parcel model. Using the coupled oil spill model and the current-wave model CH3D-SWAN, a laboratory observed wave induced circulation and oil slick evolution are successfully simulated, while different current-wave coupling schemes generate different flow patterns and oil slick evolution. The modeling system is also shown to simulate Langmuir circulation and resulting oil slicks. Hypothetical scenarios of oil spill near Virginia coast during Hurricane Isabel and Irene are simulated using the oil spill model and the CH3D-Storm Surge Modeling System to assess the role of storm waves during oil spill. The spill area is significantly larger when storm waves are considered, implying waves significantly increase oil spill dispersion.

Assessing mobility and redistribution patterns of sand and oil agglomerates in the surf zone

Heavier-than-water sand and oil agglomerates that formed in the surf zone following the Deepwater Horizon oil spill continued to cause beach re-oiling 3years after initial stranding. To understand this phenomena and inform operational response now and for future spills, a numerical method to assess the mobility and alongshore movement of these "surface residual balls" (SRBs) was developed and applied to the Alabama and western Florida coasts. Alongshore flow and SRB mobility and potential flux were used to identify likely patterns of transport and deposition. Results indicate that under typical calm conditions, cm-size SRBs are unlikely to move alongshore, whereas mobility and transport is likely during storms. The greater mobility of sand compared to SRBs makes burial and exhumation of SRBs likely, and inlets were identified as probable SRB traps. Analysis of field data supports these model results.

A cross-scale numerical modeling system for management support of oil spill accidents

A flexible 2D/3D oil spill modeling system addressing the distinct nature of the surface and water column fluids, major oil weathering and improved retention/reposition processes in coastal zones is presented. The system integrates hydrodynamic, transport and oil weathering modules, which can be combined to offer different-complexity descriptions as required by applications across the river-to-ocean continuum. Features include accounting for different composition and reology in the surface and water column mixtures, as well as spreading, evaporation, water-in-oil emulsification, shoreline retention, dispersion and dissolution. The use of unstructured grids provides flexibility and efficiency in handling spills in complex geometries and across scales. The use of high-order Eulerian-Lagrangian methods allows for computational efficiency and for handling key processes in ways consistent with their distinct mathematical nature and time scales. The modeling system is tested through a suite of synthetic, laboratory and realistic-domain benchmarks, which demonstrate robust handling of key processes and of 2D/3D couplings. The application of the modeling system to a spill scenario at the entrance of a port in a coastal lagoon illustrates the power of the approach to represent spills that occur in coastal regions with complex boundaries and bathymetry.

The Deepwater Horizon Oil Spill and the Mississippi Gulf Coast: Mental health in the context of a technological disaster

A significant percentage of disaster survivors experience negative psychological, physical, and social outcomes after a disaster. The current study advances the literature concerning the Deepwater Horizon Oil Spill (the Gulf Oil Spill) while addressing weaknesses of previous research. The current study includes a clinical sample of 1,119 adults receiving mental health services in the coastal counties of Mississippi after the Gulf Oil Spill. The levels of clinical symptoms reported on the Depression Anxiety Stress Scales (DASS-21) and PTSD Checklist (PCL-S) were examined in relation to other domains of functioning potentially affected by the spill (finances, social relationships, and physical health). Participants reported substantial worsening of their functioning across each life domain. Furthermore, chronic problems in living related to the Gulf Oil Spill were significantly associated with higher levels of psychological distress, although the pattern differed somewhat for persons living above and below the poverty line, with lower income individuals reporting a higher level of overall distress. These data support the perspective that the experience of the Gulf Oil Spill is strongly associated with a deleterious effect on mental health symptoms.

A probabilistic model for accidental cargo oil outflow from product tankers in a ship-ship collision

In risk assessment of maritime transportation, estimation of accidental oil outflow from tankers is important for assessing environmental impacts. However, there typically is limited data concerning the specific structural design and tank arrangement of ships operating in a given area. Moreover, there is uncertainty about the accident scenarios potentially emerging from ship encounters. This paper proposes a Bayesian network (BN) model for reasoning under uncertainty for the assessment of accidental cargo oil outflow in a ship-ship collision where a product tanker is struck. The BN combines a model linking impact scenarios to damage extent with a model for estimating the tank layouts based on limited information regarding the ship. The methodology for constructing the model is presented and output for two accident scenarios is shown. The discussion elaborates on the issue of model validation, both in terms of the BN and in light of the adopted uncertainty/bias-based risk perspective.

Chronic oiling of marine birds in California by natural petroleum seeps, shipwrecks, and other sources

We assessed temporal and spatial patterns of chronic oiling of seabirds in California during 2005-2010, using data on: (1) live oiled birds reported to the Oiled Wildlife Care Network (OWCN) from throughout the state, and (2) dead oiled birds found during systematic monthly beached-bird surveys in central California. A mean of 245 (± 141 SD) live miscellaneous oiled birds (not associated with known oil spills) were reported to the OWCN per year, and 0.1 oiled dead birds km(-1) per month were found on beach surveys in central California. Chemical fingerprinting of oiled feathers from a subset of these birds (n=101) indicated that 89% of samples tested were likely from natural petroleum seeps off southern and central California. There was a pronounced peak during late winter in the number of oiled birds reported in southern California, which we theorize may be related to large storm waves disturbing underwater seeps.

A review of oil, dispersed oil and sediment interactions in the aquatic environment: influence on the fate, transport and remediation of oil spills

The 2010 Deepwater Horizon oil spill has spurred significant amounts of researches on fate, transport, and environmental impacts of oil and oil dispersants. This review critically summarizes what is understood to date about the interactions between oil, oil dispersants and sediments, their roles in developing oil spill countermeasures, and how these interactions may change in deepwater environments. Effects of controlling parameters, such as sediment particle size and concentration, organic matter content, oil properties, and salinity on oil-sediment interactions are described in detail. Special attention is placed to the application and effects of oil dispersants on the rate and extent of the interactions between oil and sediment or suspended particulate materials. Various analytical methods are discussed for characterization of oil-sediment interactions. Current knowledge gaps are identified and further research needs are proposed to facilitate sounder assessment of fate and impacts of oil spills in the marine environment.

Evaluation of poly-aromatic hydrocarbons (PAHs) in the aquatic species of Suez Gulf water along El-Sokhna area to the Suez refineries

The Egyptian Red Sea environment especially along El-Sokhna area to the Suez refineries (Suez) is severely contaminated with organic compounds, as well as overfishing. This may be well contributory to recent serious declines in fish stocks. Fish embryos are also particularly vulnerable to oil exposure, even at extremely low concentrations of less than one part per billion. Consequently, even traces of oil pollution at levels often considered safe for wildlife can cause severe damage to fish. Sixteen polycyclic aromatic hydrocarbons (PAHs) were investigated in ten fish species of aquatic species by high performance liquid chromatography (HPLC). The compositions of PAHs determined in all samples were measured in order to use them as chemical markers for identifying different sources of PAH pollutants in the studied region. The total content of these16 PAHs ranged from 399.616 up to 67,631.779 ng/g wet weight. The data show that these values are considered to be alarmingly high enough to cause lethal toxicity effect by accumulation. All studied aquatic species samples are characterized by relatively high concentrations of the six-membered ring PAHs. The origin of PAHs in the collected samples is either petrogenic, biogenic, or mixed petrogenic and biogenic.

Distribution and sources of polycyclic aromatic hydrocarbons in surface sediments of the Hormuz strait, Persian Gulf

The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were determined in the sediment from the Hormuz strait, Persian Gulf. The sum of 16 PAHs (ΣPAH) concentrations varied from 72.17 to 277.77 ng g(-1) dry weight, with an average value of 131.20 ± 59.29 ng g(-1) dry weight. An ecological risk assessment of PAHs, indicated that adverse biological effects caused by acenaphthene and acenaphthylene occasionally may take place in the sediment of Hormuz strait. PAH source identification showed that the PAHs in the sediments come from pyrogenic and mixed origin. Based on classification of pollution levels, sediments from Hormuz strait could be considered as low to moderately polluted with PAHs.