Oil Spill Dispersants Research Articles

The Effect of Non-Linear Wave on Oil Spill Dispersion

On 31 March 2018, an oil spill accident polluted Balikpapan Bay. A failure occurred in a pipeline running from Penajam to Balikpapan Oil Refinery, East Kalimantan, Indonesia. Leaking pipeline caused the total estimated volume of leaked oil to approximate 44,000 Barrels of crude oil. MoTuM was used to simulate the dispersion of oil in the area. The modeling results indicate that a strong dynamic tidal current in the Bay controls the oil’s movement. The MoTuM software is suitable for spill combating, contingency plans, and backtracking. MoTuM is developed in Windows System, which integrates 3D Non-Orthogonal Boundary Fitted Ocean Hydrodynamics Model, Trajectory, Fates, Stochastic, Backtracking in Geographic Information System. This paper presents a further study of the effect of non-linear waves on the dispersion of oil in the Bay. The simulation results were validated by comparing the model with a satellite image. The agreement between the result of simulation and satellite image is excellent and shows that the non-linear wave is an essential factor for oil spill dispersion.

Mathematical Modeling of Oil Spill Dispersion in Marine Waters

During the extraction and transportation of oil in marine waters, oil spills may occur. It not only caused serious pollution in some sea areas but also have a grave impact on the marine environment. Studying the oil dispersion pattern is important for addressing oil spills accurately and timely. Therefore, through the mathematical knowledge, such as continuity equation and momentum equation, we establish a mathematical model for the dispersion of oil spills in marine water. The methods that are used include data statistics, construction of graphs and charts, example analogy, hierarchical analysis, and random calculation. The research and analysis are conducted for the oil spill process in marine oil fields.

Ionic Liquid and Tween-80 Mixture as an Effective Dispersant for Oil Spills: Toxicity, Biodegradability, and Optimization.

Chemical dispersants are used extensively for oil spill remediation. Most of these dispersants are composed of a mixture of surfactants and organic solvents, which raises concerns about aquatic toxicity and environmental impact. In this study, the toxicity and biodegradability of an oil spill dispersant composed of the surface-active ionic liquid 1-butyl-3-methylimidazolium lauroyl sarcosinate [Bmim][Lausar] and Tween-80 were investigated. In addition, important environmental factors including salinity, temperature, and wave-mixing energy were optimized to obtain maximum dispersion effectiveness. The acute toxicity against zebrafish (Danio rerio) showed that the developed dispersant was practically non-toxic with a median lethal dose of more than 100 mg L–1 after 96 h. The dispersant also demonstrated outstanding biodegradability of 66% after 28 days. A model was developed using a response surface methodology that efficiently (R2 = 0.992) related the salinity, temperature, and wave-mixing energy of seawater to dispersion effectiveness. The system was then optimized, and a high dispersion effectiveness of 89.70% was obtained with an experimental error of less than 2%. Our findings suggest that the surface-active ionic liquid and Tween-80 mixture could be a viable alternative to toxic chemical dispersants for oil spill remediation.

Performance Measures for Validation of Oil Spill Dispersion Models Based on Satellite and Coastal Data

This article presents a set of performance metrics, whose purpose is to provide a quantitative measure of the ability of oil spill dispersion models to simulate real-world oil spills. The metrics are described in detail and are applied to the output from an existing oil spill model for two specific case studies. The metrics in question make use of both satellite imagery and coastal impact reports as the basis of the validation. Specifically, we recommend the 2-D measure of effectiveness as a means of quantifying model performance based on the extent of overlap between the observations and the model output. Additionally, we show that it is advantageous to supplement the 2-D measure of effectiveness with a newly proposed set of skill scores, based on the geometric area and centroid of a given oil spill. We also demonstrate how the metrics can be used to assess the sensitivity of a model to its input parameters and the impact this has on the accuracy of the resultant forecast. Finally, we offer a real-world interpretation for each metric introduced and suggest ways that they can be used to assist in cleanup operations of actual oil spills.

Surface active ionic liquid and Tween-80 blend as an effective dispersant for crude oil spill remediation

Chemical oil spill dispersants are toxic to the marine environment, spurring a search for environmentally friendly dispersant formulations. We have formulated an oil spill dispersant composed of two biocompatible surfactants, Tween 80 (T) and surface-active ionic liquid (SAIL), [BMIM] [Lausar] (1-butyl-3-methylimidazolium lauroyl sarcosinate). Various micellar, interfacial, and thermodynamic properties of Tween 80 and ionic liquid (T/IL) blends were studied. The T/IL blends were solubilized in simulated seawater, and their oil (light Arab crude oil) dispersion effectiveness was determined by the baffled flask test. A synergistic interaction was observed between T and IL, such that a blend is effective as an oil dispersant, but neither is effective on its own. The stability of crude oil droplets was maximized at a 40/60 (w/w) of T/IL. The dispersion effectiveness at this specific ratio was found to be 81.19%, with a dispersant to oil ratio (DOR) of 1:25 (volume). The size and size distribution of dispersed oil droplets at function of DOR were investigated using optical microscopy and particle size analyzer. The results showed that the sizes of oil droplets decreased with DOR. We conclude that T/IL blends have unique properties which make them viable alternatives for oil spill remediation.

The application of coupled 3d hydrodynamic and oil transport model to oil spill incident in karawang offshore, indonesia

This study presents a coupled hydrodynamic and oil transport numerical model to study the spread of Karawang oil spills at sea due to well-kick failures. This model uses the 3D configuration of ROMS-CROCO in the Java Sea. The model has a resolution of 1 km, 25 vertical layers, and runs from January 2019 to September 2019. Temperature, salinity, sea surface height, ocean currents, and harmonic tides are derived from global models and applied to open boundaries. Hourly atmospheric datasets during model simulation are forced as flux input in the surface. The 3D profile of the flow generated by the model is converted to the GNOME oil transport model format as mover type input to disperse the oil. The hydrodynamic model shows that the result has a good agreement with in-situ data and observation with mean of correlation exceeding r>0.8 for sea surface height and sea surface temperature. Compared with radar satellites, oil spill dispersion shows the same scattered trend as satellite data. Backward modelling shows oil particles returning to the initial spill location. The oil spill was moving westward, and some are stranded on the coast between Karawang and Bekasi.

Effect of water salt composition on oil spill dispersant efficiency determined in laboratory conditions

The effect of the salt composition of water (model aqueous solutions of NaCl and artificial sea salt Instant Ocean, as well as water from the Pechora Sea) on the effectiveness of oil spill dispersants determined in laboratory conditions is studied. The efficiency of dispersants (Finasol OSR 52, Slickgone NS and Slickgone EW) was evaluated three samples of crude oil produced in the Russian Federation. Those oil samples of different composition and properties were used at fixed values of the dispersant-oil ratio (1:10), water temperature (20 ± 2°C) and salinity (35 ± 2%). It is shown that the effectiveness of the oil spill disper­sant depends on the nature (composition) of water in which the oil is dispersed, other things being the same. An anomalous behavior of one of the oil samples was found when it was dispersed in an aqueous so­ lution of NaCl under the action of Finasol OSR 52 and Slickgone EW Good convergence of the numerical values of the efficiency of dispersants was obtained when testing them in an aqueous solution of artificial sea salt Instant Ocean and in the water of the Pechora Sea. It is noted that to assess the effectiveness of dispersants in laboratory conditions, it is advisable to use water of the natural object in which this disper­sant is planned to be used. Moreover, the possibility of using an aqueous solution of the artificial salt when its salt composition is similar to that for real sea water was noted.

Contribution of surfactants and micelles to contamination and treatability of crude oil-contaminated surface water

Subsequent to an oil spill in surface water, impacts of dispersant application on water treatability and residual contamination in distributed potable water remain largely unknown. The desired outcome of dispersant application is attributable to both nonionic and anionic surfactants which reduce interfacial tension. This study evaluated the contribution of surfactants and their agglomerates, micelles, to contamination and treatability of drinking water. Both a commercial oil-spill dispersant and a formulated dispersant solution were applied in surface water, with and without crude oil, and treated by ballasted flocculation. In crude oil-contaminated surface water, the formulated dispersant was applied at two concentrations to generate surfactant monomers and surfactant micelles. Water quality degradation in the absence of crude oil was attributable to surfactants but more importantly to other organic contaminants present in the dispersant matrix. Ballasted flocculation could only handle low dispersant concentrations judging from the generated settled water quality. In the presence of crude oil, dispersant application hindered water quality and treatability due to the introduction of surfactants that were absent in surface water and whose removal was unachievable with an optimized coagulant dose for turbidity and natural organic matter removal prior to contamination. This phenomenon was of greater significance in the presence of micelles. These findings are of relevance to regulators, petrochemical and water industry professionals in their efforts to best design contingency plans for oil-spill remediation of surface water used as drinking water supply.

A cross-comparison of biosurfactants as marine oil spill dispersants: Governing factors, synergetic effects and fates

Biosurfactant-based dispersants (BBDs) may be more effective, cost-efficient and environmentally friendly than dispersants currently used for oil spill response. An improved understanding of BBD performance is needed to advance their development and commercial use. In this study, the ability of four BBDs, i.e. sufactins, trehalose lipids, rhamnolipids and exmulsins, alone and as various combinations to disperse Arabian light crude oil and weathered Alaska North Slope crude oil was compared to a widely used commercial oil dispersant (Corexit 9500A). Surfactin and trehalose lipids, which have balanced surface activity/emulsification ability, showed dispersion efficacy comparable to Corexit 9500A. Rhamnolipids (primarily a surface-active agent) and exmulsins (primarily an emulsifier) when used alone had significantly lower efficacy. However, blends of these surfactants had excellent dispersion performance because of synergistic effects. Balanced surface activity and emulsification ability may be key to formulate effective BBDs. Of the BBDs evaluated, surfactins with an effective dispersant-to-oil ratio as low as 1:62.3 and trehalose lipids with high oil affinity, biodegradation rate, and low toxicity characteristics show the most promise for commercial development.

Deep remediation of oil spill based on the dispersion and photocatalytic degradation of biosurfactant-modified TiO2

The employment of dispersant was an effective method to treat marine oil spill pollution. However, conventional dispersants only showed a single oil dispersion. Here, by modifying TiO2 nanoparticles with biosurfactant-Rhamnolipids (Rha), a highly efficient particulate dispersant with photocatalytic activity was developed. Rha-TiO2 showed both excellent oil spill dispersion and facilitated photodegradation for oil simultaneously. The oil droplets dispersed by Rha-TiO2 in seawater exhibited long time stability, which indicated the synergistic emulsification interactions between TiO2 and Rha in artificial sea water (ASW). The dispersion mechanism of Rha-TiO2 was analyzed, we found the TiO2 nanoparticles alone weren't effectively emulsified oil in high salinity ASW, but the addition of a small amount of Rha could modify the surface wettability of TiO2 nanoparticles to form the stable emulsion. In addition, the addition of a small amount of Rha could reduce the surface tension of the oil-water interface, which contribute to increasing the content of TiO2 nanoparticles at the oil-water interface, form a steric rigid layer around the oil droplets to prevent droplet coalescence and facilitate the further photocatalytic degradation of oil. In short, the Rha-TiO2 nanoparticles could effective disperse oil in ASW, meanwhile the TiO2 also played the role of photocatalytic degradation of oil pollution. Hence, this study developed a novel photocatalytic particulate dispersant to remediate marine oil spill and delivered a new feasible solution for practical oil spill treatment in the future.

Ionic liquid-biosurfactant blends as effective dispersants for oil spills: Effect of carbon chain length and degree of saturation

The well-known toxicity of conventional chemical oil spill dispersants demands the development of alternative and environmentally friendly dispersant formulations. Therefore, in the present study we have developed a pair of less toxic and green dispersants by combining lactonic sophorolipid (LS) biosurfactant individually with choline myristate and choline oleate ionic liquid surfactants. The aggregation behavior of resulted surfactant blends and their dispersion effectiveness was investigated using the baffled flask test. The introduction of long hydrophobic alkyl chain with unsaturation (attached to choline cation) provided synergistic interactions between the binary surfactant mixtures. The maximum dispersion effectiveness was found to be 78.23% for 80:20 (w/w) lactonic sophorolipid-choline myristate blends, and 81.15% for 70:30 (w/w) lactonic sophorolipid-choline oleate blends at the dispersant-to-oil ratio of 1:25 (v/v). The high dispersion effectiveness of lactonic sophorolipid-choline oleate between two developed blends is attributed to the stronger synergistic interactions between surfactants and slower desorption rate of blend from oil-water interface. The distribution of dispersed oil droplets at several DOR were evaluated and it was observed that oil droplets become smaller with increasing DOR. In addition, the acute toxicity analysis of developed formulations against zebra fish (Danio rerio) confirmed their non-toxic behavior with LC50 values higher than 400 ppm after 96 h. Overall, the proposed new blends/formulations could effectively substitute the toxic and unsafe chemical dispersants.

Application of asymmetric dicationic ionic liquids for oil spill remediation in sea water

Three asymmetric dicationic ionic liquids; 1-(2-(1-dodecyl-2-methyl-1H-imidazol-3-ium-3-yl)ethyl)-4-methylpyridin-1-ium bromide, 1-(6-(1-dodecyl-2-methyl-1H-imidazol-3-ium-3-yl)hexyl)-4-methylpyridin-1-ium bromide and 1-(10-(1-dodecyl-2-methyl-1H-imidazol-3-ium-3-yl) decyl)-4-methylpyridin-1-ium bromide (Ia, Ib &Ic respectively) were synthesized and characterized via Elemental analysis, FT-IR, 1H NMR, and Thermo-gravimetric analysis (TGA). Their surface activities were studied. The performance of the synthesized ionic liquids as oil spill dispersants were evaluated at different temperatures (10, 30 & 50 °C) and concentrations (750, 1500, 2000, 3000 ppm). Data reveals that the efficiency is ranked as follows: Ib > Ia > Ic with concentration of 1500 ppm.

Rapid assessment tool for oil spill planning and contingencies

The Rapid Oil Spill Hazard Assessment is presented as a demonstration of concept for a tool providing a framework for managers and planners to assess potential impact areas of oil spills. The tool consists of precomputed oil spill scenarios derived from the analysis of twenty years of modeled current data using Self-Organizing Maps to identify 16 representative patterns. These patterns were used to provide boundary conditions for hydrodynamic and wave models to generate higher resolution current fields, used to drive a Lagrangian oil particle transport model creating the most probable oil spill dispersion patterns. To demonstrate the concept, the tool is applied to the Perdido region in the western Gulf of Mexico. A total of 896 oil spill simulations were performed, considering surface and bottom spills, and were stored in a database for easy access to map arrival probabilities and times to be used in risk and vulnerability analysis.

A comparison of standard test methods for determining the laboratory effectiveness of oil spill dispersants: their benefits and drawbacks

A comparison of two standard test methods for determining the laboratory effectiveness of oil spill dispersants — ASTM F2059-17 «Standard Test Method for Laboratory Oil Spill Dispersant Effectiveness Using the Swirling Flask» and ASTM F3251-17 «Standard Test Method for Laboratory Oil Spill Dispersant Effectiveness Using the Baffled Flask» — is presented in this article. It is underlined that ASTM F2059-17 and ASTM F3251-17 are almost identical from the methodological and technical points of view. The main differences lie in specific design features of the applied test vessels and mixing energies created inside them. It is reasonably established that ASTM F2059-17 can be defined as a low-energy, but ASTM F3251-17 — as a high-energy laboratory test method. The specific examples of application of the test methods for determining the effectiveness of commercially available dispersants are given. It is also concluded that both test methods are necessary to apply for a correct understanding of the dispersant effectiveness. Herewith, the results obtained according to ASTM F2059-17 should be conditionally considered as the lower limit and those according to ASTM F3251-17 — the upper limit of effectiveness of the dispersant. Moreover, the use of gas chromatography with flame ionization detection (GC-FID) is emphasized to be sometimes impossible as a recommended in both ASTM F2059-17 and ASTM F3251-17 method for analyzing the oil extracts obtained during the test. The UV spectrophotometry is proposed instead of GC-FID as an alternative. However, its application is possible only after mandatory optimization of the measurement parameters for each specific oil.

Explosion Suppression Control Technology of FG Strong Adsorption Material for Leakage / Flowing Fire of Hazardous Chemicals

At present, in the process of production, operation, storage, transportation, use and disposal of petroleum and chemical solvents, major environmental disasters, such as fire, explosion and personal injury caused by leakage, are common. The disasters are often aggravated by the backward emergency disposal technology and improper operation. FG polymer is an inert, strong adsorptive material for hydrophobic substance, and the material is safe itself and non-toxic to aquatic fish and plants. In this study, FG polymer is tested in fire-fighting, explosion suppression and controling flowing fire. The result shows that the FG strong adsorption material can quickly absorb oil spill and leakage of hazardous chemicals on water and land surface, therefore controlling and eliminating the spread of flowing fire, isolating oxygen, extinguishing fire, suppressing explosion, and effectively avoiding environmental pollution. This technology can replace the backward emergency disposal methods such as oil spill dispersant, PP absorbent felt. With this technology being applied in emergence rescue, the disposal cost can be reduced by more than 50%, additionally the abilities of risk prevention, hidden danger elimination, and accident suppression can be enhanced significantly.

Development of an Algorithm for Chemically Dispersed Oil Spills

An algorithm utilizing four basic processes was described for chemical oil spill dispersion. Initial dispersion was calculated using a modified Delvigne equation adjusted to chemical dispersion, then the dispersion was distributed over the mixing depth, as predicted by the wave height. Then the droplets rise to the surface according to Stokes’ law. Oil on the surface, from the rising oil and that undispersed, is re-dispersed. The droplets in the water column are subject to coalescence as governed by the Smoluchowski equation. A loss is invoked to account for the production of small droplets that rise slowly and are not re-integrated with the main surface slick. The droplets become less dispersible as time proceeds because of increased viscosity through weathering, and by increased droplet size by coalescence. These droplets rise faster as time progresses because of the increased size. Closed form solutions were provided to allow practical limits of dispersibility given inputs of oil viscosity and wind speed. Discrete solutions were given to calculate the amount of oil in the water column at specified points of time. Regression equations were provided to estimate oil in the water column at a given time with the wind speed and oil viscosity. The models indicated that the most important factor related to the amount of dispersion, was the mixing depth of the sea as predicted from wind speed. The second most important factor was the viscosity of the starting oil. The algorithm predicted the maximum viscosity that would be dispersed given wind conditions. Simplified prediction equations were created using regression.

Towards an End-to-End Analysis and Prediction System for Weather, Climate, and Marine Applications in the Red Sea

AbstractThe Red Sea, home to the second-longest coral reef system in the world, is a vital resource for the Kingdom of Saudi Arabia. The Red Sea provides 90% of the Kingdom’s potable water by desalinization, supporting tourism, shipping, aquaculture, and fishing industries, which together contribute about 10%–20% of the country’s GDP. All these activities, and those elsewhere in the Red Sea region, critically depend on oceanic and atmospheric conditions. At a time of mega-development projects along the Red Sea coast, and global warming, authorities are working on optimizing the harnessing of environmental resources, including renewable energy and rainwater harvesting. All these require high-resolution weather and climate information. Toward this end, we have undertaken a multipronged research and development activity in which we are developing an integrated data-driven regional coupled modeling system. The telescopically nested components include 5-km- to 600-m-resolution atmospheric models to address weather and climate challenges, 4-km- to 50-m-resolution ocean models with regional and coastal configurations to simulate and predict the general and mesoscale circulation, 4-km- to 100-m-resolution ecosystem models to simulate the biogeochemistry, and 1-km- to 50-m-resolution wave models. In addition, a complementary probabilistic transport modeling system predicts dispersion of contaminant plumes, oil spill, and marine ecosystem connectivity. Advanced ensemble data assimilation capabilities have also been implemented for accurate forecasting. Resulting achievements include significant advancement in our understanding of the regional circulation and its connection to the global climate, development, and validation of long-term Red Sea regional atmospheric–oceanic–wave reanalyses and forecasting capacities. These products are being extensively used by academia, government, and industry in various weather and marine studies and operations, environmental policies, renewable energy applications, impact assessment, flood forecasting, and more.

Collision Risk Analysis and Oil Spill Dispersion Modelling in Lombok Strait

Lombok Strait is one of the water areas that designated for international shipping lanes since it has been adopted as the Indonesia Archipelagic Sea lane (IASL) II in 1998. Foreign-flagged ships passing through the strait from southbound to northbound and vice versa. Along with being an archipelagic sea lane, the strait also occupied by high-density crossing traffic connecting Bali and Lombok islands. This crossing traffic mainly dominated by passenger ferry Ro-Ro and pleasure ships as both Bali and Lombok islands are well known as tourist destinations. Aside from being a tourist destination, several islands around the Lombok Strait are also dedicated to Marine Protected Areas (MPA). There are two areas designated for MPA by the Indonesian government in the vicinity of Lombok Strait; Nusa Penida on the west side of IASL II and Gili Matra on the east side. The traffic condition allows the potential for collisions on ships passing through and crossing the Lombok Strait which is very likely caused by navigation errors, human errors, weather conditions, and other technical problems. This study aims to determine the collision risk analysis in terms of annual frequency of collision and grounding as well as the potential dispersion of oil that occurs in the event of a ship collision near the MPA of Nusa Penida. Based on one-year traffic data and forecasted to 20 years, collision and grounding frequencies analysis was conducted using iWRAP method. The analysis found that annual frequency including head-on, overtaking, crossing, merging, bend, and grounding is 4.73×10-1. In addition to the frequency of collisions, oil spill dispersion simulations were carried out using GNOME under two different conditions wind and sea current directions; wind and sea currents that heading to the Northwest, and Southwest. Given a scenario of collision occurred close to Nusa Penida island involving tanker ship that resulting hull damage and oil spill while the wind and sea current directed to Southwest, simulation resulting that oil spill will disperse and polluting MPA of Nusa Penida.

Enhanced marine monitoring and toxicity study of oil spill dispersants including Corexit EC9500A in the presence of diluted bitumen

Observations made for the analysis of the oil spill dispersant tracer dioctyl sulfosuccinate (DOSS) during LC50 toxicity testing, highlighted a stability issue for this tracer compound in seawater. A liquid chromatography high-resolution quadrupole time-of-flight mass spectrometry (LC/QToF) was used to confirm monooctyl sulfosuccinate (MOSS) as the only significant DOSS breakdown product, and not the related isomer, 4-(2-ethylhexyl) 2-sulfobutanedioate. Combined analysis of DOSS and MOSS was shown to be applicable to monitoring of spill dispersants Corexit® EC9500A, Finasol OSR52, Slickgone NS, and Slickgone EW. The unassisted conversion of DOSS to MOSS occurred in all four oil spill dispersants solubilized in seawater, although differences were noted in the rate of MOSS formation. A marine microcosm study of Corexit EC9500A, the formulation most rapid to form MOSS, provided further evidence of the stoichiometric conversion of DOSS to MOSS under conditions relevant to real world dilbit spill. Results supported combined DOSS and MOSS analysis for the monitoring of spill dispersant in a marine environment, with a significant extension of sample collection time by 10 days or longer in cooler conditions. Implications of the unassisted formation of MOSS and combined DOSS:MOSS analysis are discussed in relation to improving dispersant LC50 toxicity studies.

Optimization and Performance Test of Oil Spill Dispersant at Bioremediation of Contaminated Soil with Heavy Oil by Bioslurry Technique

Petroleum industry activities produce waste such as petroleum hydrocarbons which damage to the soil environment due to changes in soil physical, chemical and biological properties. Oil Spill Dispersant (OSD) is a product that can break down waste of oil into small parts so that it can be dispersed naturally. Laboratory experiments aimed to find out optimize and performance test of OSD in the process of bioremediation with using bio-slurry technique on contaminated soil with heavy oil was carried out at Laboratory of Surfactant and Bio-energy Research Center (SBRC), Research and Community Service Institute of Bogor Agricultural University on January - August 2018 using contaminated soil with heavy oil. The experiment used Response Surface Method (RSM) with two factors, namely the incubation time factor (X1) and the Dispersant to oil ratio (DOR) (X2). The observed variables were soil Total Petroleum Hydrocarbons (TPH), pH, total microbes, and Chemical Oxygen Demand (COD) at soil solution. The results showed that the treatment of incubation time and its combination with DOR significantly reduced soil TPH, increased soil acidity, and increased soil total B. megaterium, but did not significantly affect on COD in soil solutions. Optimization of OSD with RSM showed that the higher DOR of OSD and the longer the incubation time, the higher also the rate of biodegradation of TPH. The optimum conditions were reached at DOR of 1.16:1 and incubation time of 7 days which were able to degrade soil TPH of 54.30%. The optimum conditions of soil pH (8.825) was reached at DOR of 1:1 and incubation time of 5 days, as well as the optimum conditions of B. megaterium (8.35 log CFU g-1) was reached at DOR of 0.86:1 and incubation time of 7 days. Oil spill dispersant (OSD) increased COD in soil solution in both uncontaminated and contaminated soils with heavy oil.