A CFD Model to Evaluate Near-Surface Oil Spill from a Broken Loading Pipe in Shallow Coastal Waters

Oil spills continue to generate various issues and concerns regarding their effect and behavior in the marine environment,owing to the related potential for detrimental environmental,economic and social implications.It is essential to have a solid understanding of the ways in which oil interacts with the water and the coastal ecosystems that are located nearby.This study proposes a simplified model for predicting the plume-like transport behavior of heavy Bunker C fuel oil discharging downward from an acutely-angled broken pipeline located on the water surface.The results show that the spill overall profile is articulated in three major flow areas.The first,is the source field,i.e.,a region near the origin of the initial jet,followed by the intermediate or transport field,namely,the region where the jet oil flow transitions into an underwater oil plume flow and starts to move horizontally,and finally,the far-field,where the oil re-surface and spreads onto the shore at a significant distance from the spill site.The behavior of the oil in the intermediate field is investigated using a simplified injection-type oil spill model capable of mimicking the undersea trapping and lateral migration of an oil plume originating from a negatively buoyant jet spill.A rectangular domain with proper boundary conditions is used to implement the model.The Projection approach is used to discretize a modified version of the Navier-Stokes equations in two dimensions.A benchmark fluid flow issue is used to verify the model and the results indicate a reasonable relationship between specific gravity and depth as well as agreement with the aerial data and a vertical temperature profile plot.

Application of Vegetation Indices for Detection and Monitoring Oil Spills in Ahoada West Local Government Area of Rivers State,Nigeria

The study evaluated the environmental effects of an oil spill in Joinkrama 4 and Akimima Ahoada West LGA,Rivers State,Nigeria,using various vegetation indices.Location data for the spill were obtained from the Nigeria Oil Spill Detection and Response Agency,and Landsat imagery was acquired from the United States Geological Survey.Three soil samples were collected from the affected area,and their analysis included measuring total petroleum hydrocarbons(TPH),total hydrocarbons(THC),and polycyclic aromatic hydrocarbons(PAH).The obtained data were processed with ArcGIS software,utilizing different vegetation indices such as the Normalized Difference Vegetation Index(NDVI),Atmospheric Resistant Vegetation Index(ARVI),Soil Adjusted Vegetation Index(SAVI),Green Short Wave Infrared(GSWIR),and Green Near Infrared(GNIR).Statistical analysis was performed using SPSS and Microsoft Excel.The results consistently indicated a negative impact on the environment resulting from the oil spill.A comparison of spectral reflectance values between the oil spill site and the non-oil spill site showed lower values at the oil spill site across all vegetation indices(NDVI 0.0665-0.2622,ARVI-0.0495-0.1268,SAVI 0.0333-0.1311,GSWIR-0.183-0.0517,GNIR-0.0104--0.1980),indicating damage to vegetation.Additionally,the study examined the correlation between vegetation indices and environmental parameters associated with the oil spill,revealing significant relationships with TPH,THC,and PAH.A t-test with a significance level of p<0.05 indicated significantly higher vegetation index values at the non-oil spill site compared to the oil spill site,suggesting a potential disparity in vegetation health between the two areas.Hence,this study emphasizes the harmful effect of oil spills on vegetation and highlights the importance of utilizing vegetation indices and spectral reflectance analysis to detect and monitor the impact of oil spills on vegetation.

Oil Spill Risk Assessment of Offshore Pipeline in the Bohai Sea Under the Perspective of Ecological Protection

In recent decades,the exploration and development of marine oil and gas resources have increased significantly to meet the increasing energy demand of mankind.The Bohai Sea is a semi-closed continental sea that has a weak water exchange capacity and high ecological fragility.However,at present,more than 200 oil platforms have been built in the Bohai Sea,with more than 270 offshore oil pipelines having a length exceeding 1600 km.The oil spill pollution of offshore platforms has a great impact on the marine environment and ecosystems.Therefore,a comprehensive assessment of its risks is of great practical significance.This paper systematically constructs a comprehensive oil spill risk assessment model that combines the oil spill risk probability model and the ocean hydrodynamic model.This paper uses the Bohai Sea offshore pipeline as an example to assess its oil spill risk.The high-risk-value areas of the Bohai Sea offshore pipeline are mainly distributed at the bottom of Liaodong Bay,the bottom of Bohai Bay,near the Caofeidian area,and the northern part of the Yellow River Estuary.

Transport and behavior of marine oil spill containing polycyclic aromatic hydrocarbons in mesocosm experiments

Polycyclic aromatic hydrocarbons(PAHs)are one of the most important groups in oil,and re sponsible for major toxic and/or carcinogenic impact on humans and wildlife.It is important to understand the behavior of PAHs in marine environment after an oil-spill incident.However,interaction between petroleum PAHs and microbial communities in a marine environment remains unclear.Therefore,a series of mesocosm experiments were conducted.in which water-accommodated fraction(WAF)of oil was generated to simulate an oil-spill scenario and to analyze the transport and behavior of marine oil spill containing PAHs with and without dispersants.Results indicate that the application of dispersant could increase the concentration of total PAHs in water column due mainly to significant increase in the concentration of highmolecular weight(HMW)PAHs at a lower removal rate.At the end of the 7-day experiment,significant amount of HMW PAHs were accumulated in sediment.In general,the application of dispersant did not increase the sediment uptake of PAHs but increased the PAHs concentration in water column.

The polarimetric features of oil spills in full polarimetric synthetic aperture radar images

Compared with single-polarized synthetic aperture radar （SAR） images, full polarimetric SAIl images contain not only geometrical and backward scattering characteristics, but also the polarization features of the scattering targets. Therefore, the polarimetric SAR has more advantages for oil spill detection on the sea surface. As a crucial step in the oil spill detection, a feature extraction directly influences the accuracy of oil spill discrimination. The polarimetric features of sea oil spills, such as polarimetric entropy, average scatter angle, in the full polarimetric SAR images are analyzed firstly. And a new polarimetric parameter P which reflects the proportion between Bragg and specular scattering signals is proposed. In order to investigate the capability of the polarimetric features for observing an oil spill, systematic comparisons and analyses of the multipolarization features are provided on the basis of the full polarimetric SAR images acquired by SIR-C/X-SAR and Radarsat-2. The experiment results show that in C-band SAR images the oil spills can be detected more easily than in L-band SAR images under low to moderate wind speed conditions. Moreover, it also finds that the new polarimetric parameter is sensitive to the sea surface scattering mechanisms. And the experiment results demonstrate that the new polarimetric parameter and pedestal height perform better than other polarimetric parameters for the oil spill detection in the C-band SAR images.

The influence of Stokes drift on oil spills:Sanchi oil spill case

Spilled oil floats and travels across the water’s surface under the influence of wind,currents,and wave action.Wave-induced Stokes drift is an important physical process that can affect surface water particles but that is currently absent from oil spill analyses.In this study,two methods are applied to determine the velocity of Stokes drift,the first calculates velocity from the wind-related formula based upon a one-dimensional frequency spectrum,while the second determines velocity directly from the wave model that was based on a twodimensional spectrum.The experimental results of numerous models indicated that:(1)oil simulations that include the influence of Stokes drift are more accurate than that those do not;(2)for medium and long-term simulations longer than two days or more,Stokes drift is a significant factor that should not be ignored,and its magnitude can reach about 2%of the wind speed;(3)the velocity of Stokes drift is related to the wind but is not linear.Therefore,Stokes drift cannot simply be replaced or substituted by simply increasing the wind drift factor,which can cause errors in oil spill projections;(4)the Stokes drift velocity obtained from the two-dimensional wave spectrum makes the oil spill simulation more accurate.

Modelling of the behavior of marine oil spills: applications based on random walk techniques

A numerical model has been developed to simulate the transport and fate of oil spilled at sea. The model combines the transport and fate processes of spilled oil with the random walk technique. Oil movement under the influence of tidal currents, wind driven currents, and turbulent eddies is simulated by the PLUME RW dispersion model developed by HR Wallingford. The weathering processes in the model represent physical and chemical changes of soil slicks with time, and comprise mechanical spreading, dispersion, evaporation and emulsification. Shoreline stranding is determined approximately using a capacity method for different shoreline types. This paper presents details of the model, and describe the results of various sensitivity tests. The model is suitable for oil spill contingency planning.

Parameterization Method of Wind Drift Factor Based on Deep Learning in the Oil Spill Model

Oil spill prediction is critical for reducing the detrimental impact of oil spills on marine ecosystems,and the wind strong-ly influences the performance of oil spill models.However,the wind drift factor is assumed to be constant or parameterized by linear regression and other methods in existing studies,which may limit the accuracy of the oil spill simulation.A parameterization method for wind drift factor(PMOWDF)based on deep learning,which can effectively extract the time-varying characteristics on a regional scale,is proposed in this paper.The method was adopted to forecast the oil spill in the East China Sea.The discrepancies between predicted positions and actual measurement locations of the drifters are obtained using seasonal statistical analysis.Results reveal that PMOWDF can improve the accuracy of oil spill simulation compared with the traditional method.Furthermore,the parameteriza-tion method is validated with satellite observations of the Sanchi oil spill in 2018.

Bioremediation of Oil Spills in Cold Environments: A Review

Oil spills have become a serious problem in cold environments with the ever-increasing resource exploitation, transportation, storage, and accidental leakage of oil. Several techniques, including physical, chemical, and biological methods, are used to recover spilled oil from the environment. Bioremediation is a promising option for remediation since it is effective and economic in removing oil with less undue environmental damages. However, it is a relatively slow process in cold regions and the degree of success depends on a number of factors, including the properties and fate of oil spilled in cold environments, and the major microbial and environmental limitations of bioremediation. The microbial factors include bioavailability of hydrocarbons, mass transfer through the cell membrane, and metabolic limitations. As for the environmental limitations in the cold regions, the emphasis is on soil temperatures, freeze-thaw processes, oxygen and nutrients availability, toxicity, and electron acceptors. There have been several cases of success in the polar regions, particularly in the Arctic and sub-Arctic regions. However, the challenges and constraints for bioremediation in cold environments remain large.

The Mitigation Strategies for Managing the Potential Environmental Risks Posed by Oil and Gas Development on Mangrove Ecosystems in the Coastal Communities

Guyana is an oil-producing country vulnerable to potential oil spills and the environmental risks posed by oil and gas exploration and production activities. Despite the technologically advanced equipment employed by ExxonMobil Guyana and affiliates, an oil spill could occur due to accidents, equipment failures, or sabotages. The selected coastal communities as the study areas in Region 1 and Region 2 could be adversely affected, particularly the mangrove ecosystems. Potential oil spill pollution will adversely impact mangrove ecosystems in Region 1 and Region 2. Mangroves offer significant benefits to coastal communities, such as coastal defence and carbon sequestration, which puts Guyana on the world map. The research aimed to investigate the mitigation strategies to manage the potential environmental risks on mangrove ecosystems in the coastal communities of Region 1 and Region 2. It followed a qualitative approach and conducted semi-structured interviews with the Toshaos of the selected coastal communities. The data analysis strategy was thematic analysis using the Nvivo software. The major themes included legal and policy frameworks, oil spill response strategies, community-based involvement, and monitoring and enforcement of regulations. The significant results included reviewing and updating the regulatory framework for mangrove management and conservation;oil spills mitigation measures such as containment and shoreline protection and cleanup, cost recovery and compensation, and limited monitoring and law enforcement of mangrove management and conservation regulations by inter-agencies. The regulatory and institutional framework is outdated and needs to be amended. The agencies overseeing mangrove management and conservation have overlapping responsibilities and require more coordination. There should be greater collaboration among agencies for mangrove management and conservation and improved monitoring and enforcement programmes through institutional support.

The Environmental Risks Posed by the Oil and Gas Development and Its Potential Impacts on Mangrove Ecosystems and the Coastal Community’s Well-Being

Guyana is an oil-producing country with oil and gas exploration and production operations approximately 190 km offshore. The coastal communities selected as the study areas in Region 1 and Region 2 are adjacent to the coast and 5 to 10 km inshore. In the event of oil spills, Shell Beach Protected Areas and the other selected communities will be negatively impacted, particularly the mangrove ecosystems and the community’s well-being. The research aims to investigate the potential environmental risks posed by oil and gas exploration and production activities. It followed a qualitative approach and employed semi-structured interviews with the Toshaos of the coastal communities. The data analysis strategy was thematic analysis using the Nvivo software. The major themes included community assets, the importance of mangrove ecosystems, and the impacts of mangrove ecosystem damage through oil spills. Oil spill pollution will negatively impact mangrove ecosystems and the coastal community well-being in Region 1 and Region 2. The major results include damage to cultural artefacts, saltwater intrusion of major creeks, reduced fish catch levels, and agriculture products, which are the main economic activities in the selected communities. Consuming contaminated agriculture and marine products will lead to adverse health problems. Mangrove ecosystems provide considerable benefits to coastal community residents, including shields against river bank erosion, natural habitats for wildlife and source of income, shared traditions, social values, recreational facilities, and tourist attractions. These benefits contribute to the overall coastal community’s well-being. The mangrove forests must be protected and conserved to avoid environmental damage.

Lagrangian Model PETROMAR-3D to Describe Complex Processes in Marine Oil Spills

The version 2.1 of PETROMAR-3D model, created in the Center for Marine Meteorology of the Meteorology Institute of Cuba, is presented. This Lagrangian model has been designed to describe the physical processes of marine oil spills in the face of multiple scenarios of the marine environment. Although it is applicable to any part of the world, it is mainly designed for inter-American seas. The novelty has been to integrate the processes of drift and weathering into a model, with updated methods that incorporate 3D phenomena, a very favorable situation to achieve an operating system in Cuba and the region for the immediate and medium term. Python was chosen as the programming language because it has advanced libraries for numerical modeling, automation work and other useful tools for pre-and post-processing. By means of adapters, an important number of atmospheric, hydrodynamic and wave models have been considered to create the scenarios efficiently. The modular distribution in which the code has been created facilitates its use for other dispersion analysis and biophysical applications. Finally, a set of simple images are presented, aimed at informing decision-makers in order to mitigate the effects of the spill on the environment.

Characteristics of the sea ice reflectance spectrum polluted by oil spills based on field experiments in the Bohai Sea

Oil spilled on the sea ice surface in the Bohai Sea of China is studied through the field measurements of the reflectance of a simulated sea ice-oil film mixed pixel. The reflection characteristics of sea ice and oil film are also analyzed. It is found that the mixed pixel of sea ice and oil film is a linear mixed pixel. The means of extracting sea ice pixels containing oil film is presented using a double-band ratio oil-film sea-ice index（DROSI） and a normalized difference oil-film sea-ice index（NDOSI） through the analysis of the reflectance curves of the sea iceoil film pixel for different ratios of oil film. The area proportion of the oil film in the sea ice-oil film pixel can be accurately estimated by the average reflectance of the band of 1 610–1 630 nm, and the volume of the spilled oil can be further estimated. The method of the sea ice-oil film pixel extraction and the models to estimate the proportion of oil film area in the sea ice-oil film pixel can be applied to the oil spill monitoring of the ice-covered area in the Bohai Sea using multispectral or hyperspectral remote sensing images in the shortwave infrared band（1 500–1 780 nm）.

Studies on Marine Oil Spills and Their Ecological Damage

The sources of marine oil spills are mainly from accidents of marine oil tankers or freighters, marine oil-drilling platforms, marine oil pipelines, marine oilfields, terrestrial pollution, oil-bearing atmosphere, and offshore oil production equipment. It is concluded upon analysis that there are two main reasons for marine oil spills: (I) The motive for huge economic benefits of oil industry owners and oil shipping agents far surpasses their sense of ecological risks. (II) Marine ecological safety has not become the main concern of national security. Oil spills are disasters because humans spare no efforts to get economic benefits from oil. The present paper draws another conclusion that marine ecological damage caused by oil spills can be roughly divided into two categories: damage to marine resource value (direct value) and damage to marine ecosystem service value (indirect value). Marine oil spills cause damage to marine biological, fishery, seawater, tourism and mineral resources to various extents, which contributes to the lower quality and value of marine resources.

Doppler Spectrum Analysis of Time-Evolving Sea Surface Covered by Oil Spills

Based on the model of a contaminated sea surface that was proposed by Lombardini et al., the influence of the damping effect of oil films on the sea surface roughness spectrum and the geometrical structure of the sea surface is examined in detail by comparing with a clean sea surface. Fhrthermore, based on a quasi-stationary algorithm, a time series of backscattered echoes from a time-evolving sea surface covered by oil slicks is obtained by utilizing the frequency-domain numerical method of the parallel fast multiple method. Then, the Doppler spectrum is evaluated by performing a standard spectral estimation technique. Finally, the influence of the oil film damping effect on the Doppler spectrum of the backscattered echoes from time-evolving sea surface is investigated in detail by making a comparison of the Doppler spectrum of an oil-covered sea surface with the Doppler spectrum of a dean sea surface. The numerical simulations show that the damping effect of oil films has an influence on the Doppler spectrum signature for both horizontal-to-horizontal and vertical-to-vertical polarizations.

Source diagnostic and weathering indicators of oil spills utilizing bicyclic sesquiterpanes

Bicyclic Sesquiterpanes （BSs） are ubiquitous components of crude oils and ancient sediments. BSs in crude oils and diesel oil were identified and characterized, the effects of moderate weathering on BS distributions were discussed, and a methodology using diagnostic indices of BSs was developed for oil correlation and dif- ferentiation. The results showed that crude oils and oil products had different abundances and distributions of BSs and, consequently, resulted in different diagnostic ratios. The selected diagnostic ratio indices of BSs, such as BS4/BS5 （ratio of 4,4,8,9,9-pentamethyl-decahydronaphthalene to 8/3 （H）-drimane）, BS6/BS5 （ratio of 4,4,9,9,10-pentamethyl-decahydronaphthalene to 8/3 （H）-drimane）, BS8/BS9 （ratio of the second peak to the third peak of C16 sequiterpane）, and BS8/BSIO （ratio of C16 sequiterpane to 8fl （H）-homodrimane）, still maintained better stabilities （%RSD 〈 5%） after weathering for 30 d. The longer weathering process （150 d） had some effect on such ratios （5% 〈 %RSD 〈 10%）. The facts of the uniqueness, abundance in petroleum, and chemical stability of BSs enable them to be suitable as an effective diagnostic means for identifying spilled oil with moderate weathering, particularly for lighter refined product samples that are difficult to identify by current techniques.

Experimental study of C-band microwave scattering characteristics during the emulsification process of oil spills

In this study,oil spill experiments were performed in a water tank to determine changes in the surface scattering characteristics during the emulsification of oil spills.A C-band fully-polarimetric microwave scatterometer and a vector network analyzer were used to observe films of the following oils:crude oil with an asphalt content below3%that is prone to emulsification(type A),fresh crude oil extracted from an oilfield(type B),and industrial crude oil that was dehydrated and purified(type C).The difference in the backscatter results between the emulsified oil film and the calm water surface under C-band microwaves and the influence of the emulsification of the oil film on the backscatter were analyzed in detail.The results demonstrate that under a low-wind and no-waves condition(the maximum wave height was below than 3 mm),the emulsification of crude oil could modulated the backscatter through changes in the surface roughness and the dielectric constant,where the surface roughness had the dominant effect.The surface backscatters of the type B oil were greater than that of the type C oil in both the emulsified and non-emulsified states.In the non-emulsified state,the average differences in the backscatter between the type B and C oils were 2.19 dB,2.63 dB,and 2.21 dB for the polarization modes of VV,HH,and HV/VH,respectively.Smaller corresponding average differences of 0.98 dB,1.49 dB,and 1.5 dB were found for the emulsified state with a 20%moisture constant for the oil film.The results demonstrated that the surface roughness of the different oil films could vary due to the differences in the oil compositions and the oil film properties,which in turn affect the backscatter of the oil film surface.

Space-Time Cluster Analysis of Accidental Oil Spills in Rivers State, Nigeria, 2011–2019

Oil spills cause environmental pollution with a serious threat to local communities and sustainable development.Accidental oil spills can be modelled as a stochastic process where each oil spill event is described by its spatial locations and incidence-time and hence allow for space-time cluster analysis.Spacetime cluster analysis can detect space-time pattern distribution of oil spills which can be useful for implementing preventive measures and evidence-based decision making.This study aims to detect the space-time clusters of accidental oil spills in Rivers state,Nigeria through the Space-time Scan Statistic.The Space-time Scan Statistic was applied under the permutation model to the oil spill data(each for sabotage and operational oil spills)collected at Local Government Area(LGA)-level during the period from 2011 to 2019.The results show that the sabotage oil spill clusters have covered most of the LGAs in the southern part of the state at the start of the study period and then in 2018–2019,it moved to the west covering a single LGA.The operational oil spill clusters covered two neighboring LGAs in the south.In addition,the temporal cluster of sabotage oil spills was seen in 2019 and operational oil spills in 2011–2012.The sabotage oil spills show an increasing trend with the maximum in 2019 while the operational oil spills show a decreasing trend with the minimum in 2019.These findings assist in more effective decision-making for combating the environmental problems and controlling the future spill incidence in the cluster-regions.

Oil Spills, Gas Flaring and Adverse Pregnancy Outcomes: A Systematic Review

Oil spills and gas flaring are major environmental problems and pose major source of adverse health outcomes to communities hosting oil wells and natural gas. As oil is spilt and gas is flared;air, soil and water in affected communities are polluted. Due to this, members of these communities are exposed to higher health risks. One vulnerable group that is usually affected in this regard is pregnant women. This systematic review identified and reviewed past studies on oil pollution and different types of pregnancy outcomes within a twenty-year gap, which is between 1999 and 2019. The review also discussed the exposure pathways of oil pollution. From a literature search on scientific databases conducted in August 2019 for articles relating to the objectives of the review, data were extracted from articles which met the inclusion criteria and contents were systematically analyzed based on types of pregnancy outcomes. This review showed that oil spill and gas flaring may put pregnant women at high risk of hypertensive disorders of pregnancy, gestational diabetes mellitus, maternal depression, miscarriages via three pathways. This review may be of some use in making policy in this area.

Estimating the Variance of the Proportion of Contaminated Soil by Petroleum Spills Using Two-Dimensional Systematic Sampling under Different Approaches

In leading petroleum-producing countries like Kuwait, Brazil, Iran, Iraq and Mexico oil spills frequently occur on land, causing serious damage to crop fields. Soil remediation requires constant monitoring of the polluted area. One common monitoring method involves two-dimensional systematic sampling, which can be used to estimate the proportion of the contaminated soil and study the oil spills’ geographic distribution. A well-known issue using this sampling design involves the analytical derivation of variance of the sample mean (proportion), which requires at least two independent samples. To address the problem, this research proposed a variance estimator based on regression and a corrected estimator using the autocorrelation Geary Index under the model-assisted approach. The construction of the estimators was assisted by geo-statistical models by simulating an auxiliary variable. Similar populations to those in real oil spills were recreated, and the accuracy of proposed estimators was evaluated by comparing their performance with other well-known estimators. The factors considered in this simulation study were: a) the model for simulating the populations (exponential and wave), b) the mean and the variance of the process, c) the level of autocorrelation among units. Given the statistical and computing burdens (bias, ratio between estimated and real variance, convergence and computer time), under the exponential model, the regression estimator showed the best performance;and for the wave model, the corrected version performed even better.