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.

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.

Environmental Consequences of Oil Spills on Marine Habitats and the Mitigating Measures—The Niger Delta Perspective

The Niger Delta region has witnessed environmental impacts arising from oil production activities. Soil fertility in these areas and the entire marine habitat was investigated based on the re-occurring spill incidents in the area to establish the consequences of oil pollution on key performance indicators as well as the remedial actions for resuscitation. One of the bases of evaluation was on the fertility profile of the area impacted by oil spills as compared with the areas without oil spills influence. A suitable cost effective and environmentally friendly technique to handle the pollutions in the Niger Delta region can be found in systematic containment, recovery, clean up and restoration of the marine habitat to its initial capacity and status to be able to sustain life once again.

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.

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.

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.

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）.

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.

Assessing impact of oil spills in fairways in Chinese Bohai Sea with the impact matrix method

The density of traffic in Bohai Sea of China is growing,so the evaluation of the impact of potential oil spills becomes necessary.However,the impact of potential oil spills at a large temporal-spatial scale has seldom been studied.In this paper,the effects of potential oil spills in seven main fairways in Chinese Bohai Sea and the risks of five environmental sensitive areas(ESAs)being polluted are studied.A three-dimensional hydrodynamic model,coupled with Lagrangian particle tracking model,was constructed to simulate the transportation of oil spills.Hypothetical oil particles with an idealized,passive tracer were released along fairways and their transportation over20-day and180-day periods were simulated,respectively.An environmental impact matrix was built to reveal the relationship between oil spills in fairways and the pollution of ESAs.Results showed that in short term,Z4and Z5had high risk of being polluted by oil spills.Oil particles released along Fairways1,2and7had strong pollution effects.In long term,Z1,Z3,Z4and Z5had medium risk of being polluted.Oil particles released along Fairway3had strong pollution effects.This study might provide useful data to support marine environment protection.

Probabilistic Modeling of Oil Spills at the Exclusive Economic Zone of Cuba Using Petromar-3D Model

This article shows the probabilistic modeling of hydrocarbon spills on the surface of the sea, using climatology data of oil spill trajectories yielded by applying the lagrangian model PETROMAR-3D. To achieve this goal, several computing and statistical tools were used to develop the probabilistic modeling solution based in the methodology of Guo. Solution was implemented using a databases approach and SQL language. A case study is presented which is based on a hypothetical spill in a location inside the Exclusive Economic Zone of Cuba. Important outputs and products of probabilistic modeling were obtained, which are very useful for decision-makers and operators in charge to face oil spill accidents and prepare contingency plans to minimize its effects. In order to study the relationship between the initial trajectory and the arrival of hydrocarbons spills to the coast, a new approach is introduced as an incoming perspective for modeling. It consists in storage in databases the direction of movement of the oil slick at the first 24 hours. The probabilistic modeling solution presented is of great importance for hazard studies of oil spills in Cuban coastal areas.

Enlightenment on Classification of Environmental Pollution Events of Oil Spills at Sea

At present, China continues to increase domestic oil and gas exploration and development efforts, vigorously increases investment in scientific research, and unswervingly promotes the increase of oil and gas reserves and production, which will also bring new challenges to marine ecological environmental protection and pollution incidents. It is particularly important to thoroughly implement China’s Marine Environmental Protection Law, establish and improve the emergency response mechanism for oil spill pollution environmental incidents, and scientifically and reasonably delineate the level of oil spill pollution incidents. In response to this problem, the standard of the minimum pollution incident was analyzed and explained in this paper.

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.

Detection of oil spills in a complex scene of SAR imagery

We present a method for detecting oil spills in a complex scene of SAR imagery,including segmenting oil spills,and avoiding false alarms.Segmentation is carried out using a multi-time and multi-hierarchical method by dividing the complex sea surface into bright sea and dark sea.Gray-based and edge-based segmentations are done to extract oil spills from bright and dark sea,respectively.The proposed method can extract complete oil spills,obtain better visual results,and increase detection probability more accurately than the traditional method.Based on the surrounding features and the oil spills’features,dark land spots and low contrast dark spots are removed efficiently,thus reducing false alarms.The experimental results demonstrate that the proposed algorithm has fast computation speed,high detection accuracy,and is very useful and effective for detecting oil spills in SAR imagery.

Solar heating assisted rapid cleanup of viscous crude oil spills using reduced graphene oxide-coated sponges

The rapid cleanup of heavy crude oil spills is challenging due to the poor mobility of highly viscous oil.Traditional absorption strategies involve heating oils to a relatively high temperature to reduce their viscosity,but this method is expensive.Herein,a solar-heated reduced graphene oxide(rGO)-wrapped melamine sponge(MS)was proposed to rapidly absorb oil.The prepared rGO-MS exhibited good hydrophobicity and oleophilicity and could be used for the rapid cleanup of oil spills from water.In addition,the excellent photothermal conversion effect of rGO enabled the rGO-MS composite to achieve a solar energy absorption efficiency of 91%.Due to the localized solar energy collection and wetting properties of rGO-MS,viscous oil near the contact region was effectively heated,enabling rapid heavy oil recovery under solar light illumination.This proposed solar heating-assisted viscous oil sorbent has great promise for use in heavy oil spill cleanups in the future.

TiO_(2)@palygorskite composite for the efficient remediation of oil spills via a dispersion-photodegradation synergy

Removing spilled oil from the water surface is critically important given that oil spill accidents are a common occurrence.In this study,TiO_(2)@Palygorskite composite prepared by a simple coprecipitation method was used for oil spill remediation via a dispersion-photodegradation synergy.Diesel could be efficiently dispersed into small oil droplets by TiO_(2)@Palygorskite.These dispersed droplets had an average diameter of 20-30µm and exhibited good time stability.The tight adsorption of TiO_(2)@Palygorskite on the surface of the droplets was observed in fluorescence and SEM images.As a particulate dispersant,the direct contact of TiO_(2)@Palygorskite with oil pollutants effectively enhanced the photodegradation efficiency of TiO_(2)for oil.During the photodegradation process,·O_(2)^(−)and•OH were detected by ESR and radical trapping experiments.The photodegradation efficiency of diesel by TiO_(2)@Palygorskite was enhanced by about 5 times compared with pure TiO_(2)under simulated sunlight irradiation.The establishment of this new dispersion-photodegradation synergistic remediation system provides a new direction for the development of marine oil spill remediation.

Synthetic aperture radar oil spills detection based on morphological characteristics

In recent years,oil spills in coastal regions have received a lot of public concern for its strong impact on the coastal ecological system.Synthetic aperture radar(SAR)is regarded as one of the most suitable sensors for oil spill monitoring for its wide-area and all-day all-weather surveillance capabilities.However,due to its special imaging mechanism,multiplicative speckle noise and dark patches caused by other physical phenomena always affect the accuracy of oil spill detection.In this work,an oil spill detection method based on dual-threshold segmentation and support vector machine was proposed.Experiments on SAR images illustrated the effectiveness of the proposed method in detecting and tracing oil spill from SAR images.