The Reduction of Stranded Oil by In Situ Shoreline Treatment Options

The Svalbard Shoreline Field Trials quantified the effectiveness of sediment relocation, mixing, bioremediation, bioremediation combined with mixing, and natural attenuation as options for the in situ treatment of oiled mixed-sediment (sand and pebble) shorelines. These treatments were applied to oiled plots located in the upper beach at three experimental sites, each with different sediment character and wave-energy exposure. Systematic monitoring was carried out over a 400-day period to quantify oil removal and to document changes in the physical character of the beach, oil penetration, oil loading, movements of oil to the subtidal environment, biodegradation, toxicity, and to validate oil-mineral aggregate formation.The results of the monitoring confirmed that sediment relocation significantly accelerated the rate of oil removal and reduced oil persistence where oil was stranded on the beach face above the level of normal wave activity. Where the stranded oil was in the zone of wave action, sediment relocation accelerated the short-term (weeks) rate of oil loss from the intertidal sediments.Oil removal rates on a beach treated by mechanical mixing or tilling were not significantly higher than those associated with natural recovery. However there is evidence that mixing/tilling may have enhanced microbial activity for a limited period by increasing the permeability of the sediment.Changes in the chemical composition of the oil demonstrated that biodegradation was significant in this arctic environment and a bioremediation treatment protocol based on nutrient enrichment effectively doubled the rate of biodegradation. However, on an operational scale, the success of this treatment strategy was limited as physical processes were more important in causing oil loss from the beaches than biodegradation, even where this oil loss was stimulated by the bioremediation protocols.     

Oil-Mineral Aggregate Formation on Oiled Beaches: Natural Attenuation and Sediment Relocation

The significance of oil-mineral aggregate (OMA) formation on the effectiveness of the in situ shoreline treatment options of natural attenuation (natural recovery) and sediment relocation (surf washing) was examined during field trials on two mixed-sediment (sand and pebble) beaches experimentally oiled with IF-30 oil. At both sites, the amount of oil remaining in the experimental plots was dramatically reduced within five days after sediment relocation treatments. Time-series microscopy and image analysis of breaker-zone water samples demonstrate that OMA formation occurred naturally on the oiled beaches at both sites and was accelerated by the sediment relocation procedure. Lower concentrations of OMA in the breaker zone at Site 3 are attributed to the higher wave-energy levels at this site that presumably facilitated more rapid OMA dispersion. The granulometry and mineralogy of beach sediment and of subtidal sediment trap samples indicate that the material settling in nearshore waters originated from the relocated sediment and that a portion of the finer sediment was probably transported out of the study region before settling. Gas chromatography/mass spectrometry analysis demonstrated that a significant fraction of the oil dispersed into nearshore waters and sediments by interaction with mineral fines was biodegraded. The fact that little or no residual oil was found stranded on the shore in areas adjacent to the experimental plots and that only small amounts of oil were found in nearshore subtidal sediments and sediment trap samples suggests that a large fraction of the oil lost from the experimental plots may have been dispersed in the form of relatively buoyant OMA.     

Experimental design of the Svalbard shoreline field trials

Experimental oil spills on three mixed-sediment beaches in Svalbard, Norway, were designed to evaluate the effectiveness of in situ shoreline cleaning treatments to accelerate natural recovery. These were: sediment relocation (surf washing), mixing (tilling), bioremediation (fertilizer application), and bioremediation combined with mixing. Additionally, natural attenuation was studied as a treatment option. An intermediate fuel oil was applied to the sediment surface in the upper intertidal zone at three experimental sites, each of which had different sediment characteristics and wave-energy exposure. Over a 400-day period, the experiments quantified oil removal, documented changes in the physical character of the beach as well as oil fate and behaviour, assessed toxicity effects associated with treatment, and validated oil-mineral aggregate formation as a result of the selected treatment techniques. The three sites were chosen based on significant differences, and each treatment was quantitatively compared only with other treatments at that site.This paper describes the physical location and the experimental design of the field trials. Some of the key issues that were addressed in the design included: the methodology for application of oil, the application of treatment techniques, the realistic simulation of real-world conditions, and the sampling protocols to overcome sediment and oiling heterogeneity typical of mixed-sediment beaches in order to allow quantitative comparisons of the treatments.     

Bioremediation of Stranded Oil on an Arctic Shoreline

The application of slow-release and soluble fertilizers proved to be an effective and environmentally benign way of stimulating oil biodegradation on an Arctic shoreline. Fertilizer application to the surface of the beach delivered nutrients to the oiled sediment beneath the beach surface. There was no significant run-off of this fertilizer to either the nearshore water or to unfertilized plots, and there were no adverse toxicological effects of the fertilizer application. The fertilizer application was followed by an increase in oxygen consumption and carbon dioxide evolution from the beach, increased microbial biomass, and significantly greater biodegradation of oil on the plots that had received fertilizer. The rate of oil biodegradation was approximately doubled over the course of a year by fertilizer applications in the first two months after the spill.Simple test kits proved adequate to monitor the fertilizer-application process in the field in a time frame that would allow the application process to be fine-tuned during treatment on a real spill. Simple test kits and portable instrumentation were useful in demonstrating the initial success of the bioremediation strategy.     

Toxicity Evaluation with the Microtox Test to Assess the Impact of In Situ Oiled Shoreline Treatment Options: Natural Attenuation and Sediment Relocation

Changes in the toxicity levels of beach sediment, nearshore water, and bottom sediment samples were monitored with the Microtox^® Test to evaluate the two in situ oil spill treatment options of natural attenuation (natural recovery--no treatment) and sediment relocation (surf washing). During a series of field trials, IF-30 fuel oil was intentionally sprayed onto the surface of three mixed sediment (pebble and sand) beaches on the island of Spitsbergen, Svalbard, Norway (78°56^′ N, 16°45^′ E). At a low wave-energy site (Site 1 with a 3-km wind fetch), where oil was stranded within the zone of normal wave action, residual oil concentrations and beach sediment toxicity levels were significantly reduced by both options in less than five days. At Site 3, a higher wave-energy site with a 40-km wind fetch, oil was intentionally stranded on the beach face in the upper intertidal/supratidal zones, above the level of normal wave activity. At this site under these experimental conditions, sediment relocation was effective in accelerating the removal of the oil from the sediments and reducing the Microtox^® Test toxicity response to background levels. In the untreated (natural attenuation) plot at this site, the fraction of residual oil remaining within the beach sediments after one year (70%) continued to generate a toxic response. Chemical and toxicological analyses of nearshore sediment and sediment-trap samples at both sites confirmed that oil and suspended mineral fines were effectively dispersed into the surrounding environment by the in situ treatments. In terms of secondary potential detrimental effects from the release of stranded oil from the beaches, the toxicity level (Microtox^® Test) of adjacent nearshore sediment samples did not exceed the Canadian regulatory limit for dredged spoils destined for ocean disposal.     

CytoSol – Cleaning Oiled Shorelines with a Vegetable Oil Biosolvent

A cleanup process has been developed to aid in the removal of crude or fuel oil from shorelines using CytoSol “biosolvent” formulation based on vegetable oil methyl esters in combination with bioremediation enhancers. The CytoSol biosolvent dissolves and floats the oil, the oil/biosolvent mixture is rinsed off with ambient temperature water for collection as a consolidated layer with skimmers. The collected oil mixture can be recycled as a burner fuel. Nutrient enhancers in the formulation then stimulate the natural biodegradation of the remaining residual hydrocarbons. This new approach minimizes physical and chemical impacts to marine organisms, cleans oiled surfaces effectively, and allows the oiled ecosystem to recover with less mortality than conventional methods involving hot water, detergents or other chemical cleaners. CytoSol is ideally suited for port facilities and waterfronts dealing with occasional small oil spills and has undergone extensive laboratory testing for the US EPA. In 1997, the CytoSol biosolvent was licensed in the state of California as a shoreline cleaner and set up for commercial distribution.CytoSol biosolvent can extract heavy petroleum (crude, fuel oils) off shoreline habitats, mussel-encrusted breakwaters or pilings, and estuary vegetation. The viscosity of the product tends to limit the penetration of the CytoSol/oil mixture into sand and gravel beaches, allowing more of the dissolved oil to be removed from the shoreline by washing. The product has a low specific gravity (0.87), tends to consolidate oil, and is practically immiscible with water, so it facilitates the recovery of spilled oil with conventional skimming and absorbent boom technologies. Since it is non-volatile and non-flammable, there is little danger of explosion or fire when spraying it inside confined spaces.     

Marsh Sensitivity to Burning of Applied Crude Oil

This research note summarizes Spartina alterniflora and Sagittaria lancifolia sensitivity to oiling and in situ burning of applied oil. Experimental plots (2.4 m × 2.4 m × 0.6 m) were constructed in salt and freshwater marsh habitats and South Louisiana Crude (SLC) applied (2 l m⁻²) to stems and leaves of marsh plants of oil and oil/burn treatment plots. Burning was initiated mid-August when winds were calm and a 15-25 cm floodwater layer covered the marsh substrate. Vegetative responses (stem density, height, carbon assimilation and biomass production) were measured for approximately one year following the in situ burns. Application of oil and burning of SLC only had short-term detrimental effects on salt and freshwater marsh vegetation. About one year after burns, vegetative responses measured in oiled and oiled/burned plots approached or exceeded control (no oil or burn) values. Field results suggest, under our experimental conditions, in situ burning of spilled oil in S. alterniflora and S. lancifolia marshes may be a remediation operation to consider.     

Composition and Toxicity of Residual Bunker C Fuel Oil in Intertidal Sediments After 30 Years

In 1970, approximately 2000 m³ of Bunker C crude oil impacted 300 km of Nova Scotia’s coastline following the grounding of the tanker Arrow. Only 10% of the contaminated coast was subjected to cleanup, the remainder was left to cleanse naturally. To determine the long-term environmental impact of residual oil from this spill event, samples of sediment and interstitial water were recovered in 1993, 1997 and 2000 from a sheltered lagoon in Black Duck Cove. This heavily oiled site was intentionally left to recover on its own. Visual observations and chemical analysis confirmed that substantial quantities of the weathered cargo oil were still present within the sediments at this site. However, direct observations of benthic invertebrate abundance suggest that natural processes have reduced the impacts of the residual oil. To confirm this hypothesis, sediment and interstitial water samples from Black Duck Cove were assessed with a comprehensive set of biotests and chemical assays.Residual oil in the sediments had limited effect on hepatic CYP1A protein levels and mixed function oxygenase (MFO) induction in winter flounder (Pleuronectes americanus). No toxicity was detected with the Microtox solid phase test (Vibrio fischeri). Significant sediment toxicity was detected by the amphipod survival test (Eohaustorius estuarius) in four out of the eight contaminated sediments. Interstitial water samples were deemed non-toxic by the Microtox 100% test (Vibrio fischeri) and the echinoid fertilization test (Lytechinus pictus). Sediment elutriates were also found to be non-toxic in the grass shrimp embryo-larval toxicity (GSELTOX) test (Palaemonetes pugio).Recovery at this contaminated site is attributed to natural processes that mediated biodegradation and physical removal of oil from the sediments. In support of the latter mechanism, mineralization experiments showed that all test sediments had the capacity for hexadecane, octacosane and naphthalene degradation, while chemical analysis confirmed that the Bunker C oil from the Arrow had undergone substantial biodegradation.     

Biodegradation of Crude Oil Contaminating Marine Shorelines and Freshwater Wetlands

This paper is a summary of the various factors influencing weathering of oil after it has been released into the environment from a spill incident. Special emphasis has been placed on biodegradation processes. Results from two field studies conducted in 1994 and 1999 involving bioremediation of an experimental oil spill on a marine sandy shoreline in Delaware and a freshwater wetland on the St. Lawrence River in Quebec, Canada have been presented in the paper.     

An exposure index for oiled shorelines

Wave action is the most effective natural cleaning agent of oiled shorelines. Therefore, the degree of exposure of a shoreline to wave action dictates how quickly that shoreline will be cleaned by natural processes. In the absence of recorded wave data, a simplified exposure index, tested on the shorelines of Prince William Sound, Alaska oiled during the Exxon Valdez oil spill, can be used to predict potential cleansing by wave action. Wind gauge data correlated with three effective fetch distances measured perpendicular to and at 45° to the shoreline are used to calculate the exposure index. In Prince William Sound, both biological and geomorphological criteria for exposure to waves agreed with the readings calculated for the index. Surface oil on the exposed shorelines was removed quickly during the first storm season. Sheltered coasts were cleaned more slowly. This technique should also work well for other partially enclosed water bodies.     

Enhanced oil biodegradation with mineral fine interaction

During recent oil spill clean-up operations, residual oils stranded in the intertidal environment were successfully dispersed into the sea by physically accelerating the natural interaction between oil and mineral fines. Oil-mineral fine interaction reduces the adhesion of oil to solid surfaces and promotes the formation of stable micron-sized oil droplets in the water column. By increasing the oil-in-water interface, i.e. the oil becomes more accessible to nutrients, oxygen and bacteria, this interaction becomes a key factor in enhancing oil biodegradation. There is, however, concern that this technique merely transports the oil from one compartment of the environment to another. In our study, controlled laboratory shaker-flask experiments showed that oil-mineral fine interactions stimulates microbial activity by enhancing both the rate and extent of oil degradation by stimulating microbial activity. These results support the application of shoreline oil spill clean-up techniques based on the acceleration of oil-mineral fine interactions.     

石油污染海岸线生物修复技术研究进展

介绍了生物修复、生物强化和生物刺激的基本概念。综述了基于生物强化和生物刺激技术处理石油污染海岸线的研究进展,并指出不同处理技术的优势与不足。分析了影响溢油污染海岸线生物修复的重要因素,包括石油类型、波浪和水流能量、温度、盐度、氧气含量等。对今后研究的主要方向进行了展望。     

Potential for bioremediation of the perchlorate‐contaminated sediments in the Las Vegas Wash area,Henderson, Nevada

This study investigates the potential for perchlorate biodegradation in the sediments of the Las Vegas Wash area in Henderson, Nevada. The continuous transport of perchlorate from a contaminated seepage to the Las Vegas Wash, Lake Mead, and the Colorado River has resulted in considerable deposition of perchlorate along the sediments of the Las Vegas Wash. The contaminated sediments act as a distributed source of perchlorate, making efforts to stop the flow of perchlorate to the Colorado River very challenging. In this study, perchlorate‐ reducing bacteria were enumerated and microcosm tests were performed to investigate the role of indigenous microorganisms and the limitations to natural perchlorate biodegradation in the contaminated sediments. The results of microcosm tests revealed that, despite the high number of perchloratereducing bacteria present, natural perchlorate in the area appears to be limited by (1) high salinity levels, the presence of nitrate, and the low perchlorate concentrations present in the sediments and (2) an insufficient carbon source. However, the potential for in situ bioremediation of the sediments along the Wash area is considered to be high due to the presence of significant numbers of perchlorate‐ reducing bacteria and to the ease in which an additional carbon source could be provided to sustain nitrate and perchlorate biodegradation. The economics of this process are expected to be very favorable; however, detailed cost estimates, pilot‐scale testing, and permit applications are required before this concept can be applied. © 2005 Wiley Periodicals, Inc.     

In-Situ Phytoremediation of Pahs Contaminated Soils Following a Bioremediation Treatment

Phytoremediation of pollutants in soils is an emerging technology, using different soil-plant interaction properties. For organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs), phytodegradation seems to be the most promising approach. It occurs mostly through an increase of the microbial activity in the plant rhizosphere, allowing the degradation of organic substances, a source of carbon for soil microbes. Despite a large amount of available data in the literature concerning laboratory and short term PAH phytodegradation experiments, no actual field application of such technique was previously carried out. In the present study, a soil from a former coking plant was used to evaluate the feasibility and the efficiency of PAH phytodegradation in the field during a three years trial and following a bioremediation treatment. Before the phytoremediation treatment, the soil was homogenized and split into six independent plots with no hydrological connections. On four of these plots, different types of common plant species were sowed: mixture of herbaceous species, short cut (P1), long cut (P2), ornamental plants (P3) and trees (P4). Natural vegetation was allowed to grow on the fifth plot (P5), and the last plot was weeded (P6). Each year, representative sampling of two soil horizons (0–50 and 50–100 cm) was carried out in each plot to characterize the evolution of PAHs concentration in soils and in soils solution obtained by lixiviation. Possible impact of the phytoremediation technique on ecosystems was evaluated using different eco- and genotoxicity tests both on the soil solid matrix and on the soil solution. For each soil horizon, comparable decrease of soil total PAHs concentrations were obtained for three plots, reaching a maximum value of 26% of the initial PAHs concentration. The decrease mostly concerned the 3 rings PAHs. The overall low decrease in PAHs content was linked to a drastic decrease in PAHs availability likely due to the bioremediation treatment. However, soil solutions concentration showed low values and no signficant toxicity was characterized. The mixture of the herbaceous species seemed to be the most promising plants to be used in such procedure.     

Hindcast of a Japan Sea oil spill

An oil spill model was applied to the Nakhodka tanker spill accident that occurred in the Japan Sea in January 1997. The amount of oil spilled was estimated to be around 5000 kl, released over 1 day. Under a 2-m wave height condition, and a 3.5% of drift factor, the model simulated the oil slick to hit the shoreline after 6 days. This was in good agreement with the observed conditions. After drifting to the shoreline, the oil slick moved northeastward with the current. In the model, the simulation where the shoreline absorbs 100% of stranded oil failed to reproduce the actual oil slick trajectory. The simulation in which oil resuspended after stranding indicated a similar trend to the actual case. Therefore, it is likely that a considerable amount of oil that hit the shoreline may have returned to the sea and moved with the current. The effects of current pattern and wind drift angle on the oil slick trajectory were also examined. It is suggested that the wind parameters were of prime importance in reproducing a realistic distribution.     

Pure oxygen-enhanced biodegradation for contaminated groundwater

On-site oxygen generation was chosen as the most effective and efficient source of pure oxygen for enhancing biodegradation at a hydrocarbon-contaminated oil and gas well site in northern Michigan. Contaminants include benzene, toluene, ethylbenzene, and xylenes released through natural gas dehydration practices that were halted in 1985. Free product and contaminated soil were completely removed from the source area in spring 1989, leaving only the groundwater plume for further remediation. This article discusses the project's two phases—a purge and treat system and the pure-oxygen bioremediation system—each costing $75,000. It also details the combined system's technical elements (including purge and monitoring wells, oxygen generator, and drainfield), and cleanup results (including how pure oxygen has helped destroy contaminants, not merely move them to other media).     

石油烃污染土壤微生物修复促进技术

采用原位修复法处理石油烃污染土壤,考察了土壤中石油烃的自然降解情况,研究了土壤改良剂和生物营养剂对石油烃降解的促进作用。实验结果表明:将总石油烃含量约为5 g/kg的实验土样降解30 d,自然降解时总石油烃降解率为7.8%;当单独加入1.0%(w)的土壤改良剂时,总石油烃降解率达36.0%;当单独加入1.0 g/kg的生物营养剂时,总石油烃降解率为51.6%;最佳促进剂配方为土壤改良剂加入量1.0%(w),生物营养剂加入量1.0 g/kg,此条件下总石油烃降解率为80.1%。     

Disposal of oil in sandy coastal soils

A combination of survey and experimental studies is being conducted to determine the ecological risks associated with disposal of oiled beach material (OBM) in coastal sand dunes and dune pastures. Past incidence of burial close to shoreline spill locations was less than expected and the two sites located in Britain showed very different patterns of oil degradation and site recovery. Field scale experiments revealed that breakdown of hydrocarbons within OBM began very quickly after deposition, even in nutrient-poor sand, leading to almost complete degradation of crude oil. There appears to be no lateral or vertical loss of oil or its breakdown products and recolonization of deposited OBM does occur naturally, though supplementary planting helps in stabilizing the sand surface. The application of this method in practical terms is constrained by the availability of suitable sites where it is possible to minimize physical disturbance to dune systems by lorries or other equipment employed in the removal process.     

Use of bio‐traps with multiple substrates and electron acceptors to optimize remediation

Bio‐Traps® were used to investigate biodegradation of benzene, methyl tertiary butyl ether (MTBE), and tertiary butyl alcohol (TBA) under different conditions at a fractured rock site to aid the selection of a bioremediation approach. The Bio‐Traps were amended with the ¹³C‐labeled constituent of interest and sampled sequentially at 15‐, 30‐, 60‐, and 90‐day intervals. The conditions tested were biodegradation during operation of an air sparge system, amendment with nitrate during the air sparge operation, anaerobic biodegradation with the system turned off, and anaerobic biodegradation with nitrate amendment. There was increased biomass with nitrate amendment whether the air sparge system was on or off for all the constituents of interest. The diversity of the microbial community, determined by phospholipid fatty acid analysis, decreased with nitrate amendment as more specialized degraders were selected. The most negative indicators of potential biodegradation performance were observed with the anaerobic control. There was less biomass overall, less incorporation of ¹³C into biomass, and decreased membrane permeability. As testing with additional amendments continues at the site, it is not yet certain which treatment might be selected for bioremediation, but the Bio‐Trap tests thus far have identified that the in situ, natural attenuation condition is least favorable for biodegradation. © 2009 Wiley Periodicals, Inc.     

Effectiveness of “Nochar” Solidifier Polymer in Removing Oil from Open Water in Coastal Wetlands

The use of solidifier in oil spill cleanup has been minimal due to lack of practical application method and in situ field testing and evaluation under various coastal and environmental conditions. Solidifiers are dry granular, hydrophobic polymers that react with oil and form a cohesive mass that floats on water. Unlike sorbents, the oil is retained in the solid mass allowing for easy removal. A field test was conducted in coastal Louisiana in which replicated open water enclosures were oiled with South Louisiana Crude. Granular solidifier was spread over oil and the solidified oil was then removed from the plots. Over 70% of the applied oil was recovered. Results demonstrated that solidifier may, under certain conditions, be an option for removing oil from wetlands.