[en] A study of the relationship between oil spill dispersant effectiveness and mixing energy was conducted using three different laboratory apparatus which use rotational motion to generate mixing energy. The stability of the resulting emulsions was gauged by measuring the amount of oil that remained in the water column over time. The findings are that each oil/dispersant combination shows a unique onset or threshold of dispersion. The effectiveness increases nearly linearly with energy, expressed as flask rotational speed. Natural dispersion was also measured and shows similar behavior to chemical dispersion except that the thresholds occur at a higher energy and effectiveness rises more slowly with increasing energy. Effectiveness, defined as the percentage of oil in the water column, rises rapidly to 100% with increasing energy for light oils treated with chemical dispersants. Heavier oils will disperse but to lesser effectiveness values. Effectiveness varies significantly with quantity of dispersant. Stability of the resulting emulsion is affected by dispersant amount. Effectiveness can be viewed as a tradeoff between energy, stability, and dispersant quantity. As energy and quantity are increased, so is the effectiveness. Stability of the resulting emulsion is relatively independent of energy, but dependent on amount of dispersant. High dispersion can be achieved using high energy and low dispersant amount, but the resulting dispersion is less stable than one using more dispersant. 21 refs., 2 figs., 2 tabs

[en] The Hamburg Ship Model Basin has converted one of its ice tanks into an environmental test basin for cold regions. The test basin is 30 m long, 6 m wide and 1.5 m deep. Special features of the basin are ice making facilities that can achieve 2 mm/h of ice growth, a mobile wave generator, a current device which is used together with a longitudinal bulkhead to operate the basin as a circulating water channel, and oil recovery devices. Typical sea ice conditions which can be simulated include homogeneous level ice of constant thickness, pack ice fields, rafted ice, and pressure ridges. A joint industry research program has been proposed to investigate weathering, fate, and spreading of various oils in different ice conditions with and without currents. Laboratory testing will also be dedicated to the development of suitable techniques for combatting oil spills in ice-covered areas. 2 figs

[en] During the January-May 1991 Gulf War, an estimated 6 million bbl of oil was spilled into the Arabian Gulf, mostly around Mina Al-Ahmadi in southern Kuwait. Three models were used to analyze the fate and transport of the spills originating at Al-Ahmadi. The first generation model, GULFSLIK I, was developed in the late 1970s and predicts the movements of a spill by considering that the center of the slick advects with a velocity equal to 3% of the wind speed. This model is best for the initial forecasting of oil spill movement. The second generation GULFSLIK II Model predicts the trajectory of spills at 24 h intervals, requiring as input the average daily wind velocity. Surface currents are obtained for the model from a reliable 3-dimensional hydrodynamic model of the Gulf coupled with an appropriate interpolation scheme. Comparisons between predicted spill trajectories and actual sightings show GULFSLIK II to be reasonably accurate. The third generation model, called OILPOL, consists of a set of algorithms describing the processes of advection, turbulent diffusion, surface spreading, vertical mechanical dispersion, emulsification, and evaporation. After 80 days, results show under 8% of the initial oil volume remains on the sea surface while 15% is suspended in the water column or sedimented on the sea bed. Comparisons of simulation results and actual sightings show excellent agreement. 4 refs., 7 figs., 2 tabs

[en] The oil spills from the Agip Abruzzo and the Haven in April 1991 are described. The Agip Abruzzo collided with a ferry near Livorno, Italy and spilled 3,000 tonnes of Iranian crude oil. Another 12,000 tonnes burned and 140 people were killed in the incident. The spill had little effect on the sea environment as most of the spilled oil was removed. The Haven oil tanker exploded just after unloading crude oil at Arenzano, Italy, spilling 3,000 tonnes of oil along the Ligurian coast. A series of nine explosions occurred over the next few days and the ship finally sank in 60 m of water. Spill cleanup procedures used at sea and along the affected coast are reviewed. Crude oil residues drifting along the coast of the Balearic Islands were sampled and analyzed in May and July 1991 to determine whether they came from the Haven tanker. Experiments were also conducted to determine the evaporated fraction of heavy Iranian crude oil as a function of time when spilled on sea water or different sizes of beach sand. The analyzed samples were concluded not to have come from the Haven spill. 9 refs., 9 figs., 1 tab

[en] A crude oil spill occurred at an exploratory well site near Prudhoe Bay, Alaska during drilling in the winter of 1969-70. The oil infiltrated a portion of the gravel pad and flowed onto the adjacent tundra. Although some attempts were made to clean up the site at the time, a large area of contaminated gravel and tundra remained in 1990. Based on a detailed site assessment, 2.2 hectares had such high total petroleum hydrocarbon (TPH) concentrations that excavation and incineration were selected as the most appropriate remedial actions. In the remaining less-contaminated areas that were not excavated and in subsurface soil horizons, bioremediation was selected. During the winter of 1991, an estimated 19,000 m³ of soil was excavated and incinerated in a rotary kiln. During summer 1991, biodegradation of the TPH in the remaining soil was promoted by tilling, watering and draining, and fertilizing. Excavation of the heavily contaminated soil reduced mean TPH concentrations by 89% at the tundra surface. Bioremediation for 53 days reduced mean TPH concentrations by 74%. Hydrocarbon-degrading bacteria and soil and groundwater properties important to microbial growth were also monitored. Two strains of Pseudomonas species showed a good ability to degrade crude oil and probably were responsible for the large reduction in TPH concentrations observed after one summer. 5 refs., 5 figs

[en] An oil spill model system is being developed in cooperation with several major oil companies and government agencies from the USA and Canada. The system, called ASAP, enables prediction of the trajectory of an oil spill in the water anywhere in the world. Within a half hour of notification of a spill, the ASAP user is able to evaluate a variety of spill response scenarios. The model also has the capability to be updated, based on observations of the oil distribution and composition. The model is being developed for operation on personal and laptop computers and will provide deterministic and stochastic spill forecast simulations. Embedded in the system are low resolution data for coastlines, bathymetry, currents, and statistical winds. The model system relies on an easy-to-use, mouse-driven graphical interface. Environmental data are user-selectable, and a library of oil types is included. The oil spill fates model allows the user to select which algorithms are to be used to predict the oil's drift, spread, evaporation, emulsification, shoreline interactions, dissolution, dispersion, and ice-oil interactions. A hypothetical session to set up a new map area with ASAP is outlined. ASAP is scheduled for completion in 1993

[en] When oil is spilled at sea, several weathering processes can occur simultaneously. These processes can either be studied isolated in small-scale laboratory investigations or in connection with experimental field trials with oil at sea. To get the opportunity to study these processes simultaneously, under controlled conditions, a meso-scale flume basin was constructed. The basin is ca 9 m long and 0.5 m wide and made of plexiglass. When filled with sea water to a depth of 0.4 m, the volume is ca 1,750 liters. Three water pumps are installed at the bottom of the basin to achieve a basic and uniform circulation of the water. Adjustable fans and wave generator can provide a variety of wind and wave conditions in the basin. A sunlamp is used to provide radiation for artifical photolysis if photooxidation of the oil is desired. The whole basin is located in a temperature-adjustable cooling room. Examples of test results on evaporative loss, water uptake, viscosity, and natural dispersion of North Sea crudes are presented. 6 refs., 6 figs

[en] The effectiveness of dispersants for use under Arctic conditions was tested using the IFP dilution test (Bocard et al., 1990). Arctic conditions in this context are defined as 0 degree C temperature and water salinities of 0.5% and 3.3%. The study was performed in two steps, first with a screening activity where 14 dispersants were tested on water-in-oil (w/o) emulsions from two weathered oil types. In the next step, the five most promising dispersants were tested on both weathered water-free oils and w/o emulsions from four different oil types. The results show that many of the most used dispersants which previously have shown an excellent effectiveness at 3.3% salinity may have a very low effectiveness at 0.5% salinity. Recently developed products specially designed for low salinity use such as Inipol IPF are effective at low salinities, but suffer from a rather poor effectiveness at high salinities. This is of significant operational importance in Arctic oil spill combat operations, since the salinity may vary due to ice melting. The study shows the need for development of dispersants with high effectiveness both at low temperature and over a wide range of salinities. 10 refs., 3 figs., 3 tabs

[en] In 1991, a series of 14 mesoscale fire experiments was performed to measure the burning characteristics of crude oil on salt water. These oil burns in a pan ranged in size from 6 to 15 m square. Results of the measurements for burning rate and smoke emissions are compared to those from previous smaller-scale burns. The burning rate, as indicated by the regression rate of the oil surface, was found to be 0.055 ±0.01 mm/s for pan fires with effective diameters greater than 7 m. Smoke particulate yields from fires greater than 2 m diameter were found to be ca 0.13 of the oil burned on a mass basis. Predictions of smoke plume trajectory and particulate deposition at ground level from the Large Eddy Simulation (LES) model developed as part of this research effort were found to be different from those predicted by the SCREEN model. LES is a steady state 3-dimensional calculation of smoke plume trajectory and smoke particulate deposition based on a mixed finite difference and Lagrangian particle tracking method. 23 refs., 21 figs., 18 tabs

[en] The most common form of remote sensing as applied to oil spills is aerial remote sensing. The technology of aerial remote sensing, mainly from aircraft, is reviewed along with aircraft-mounted remote sensors and aircraft modifications. The characteristics, advantages, and limitations of optical techniques, infrared and ultraviolet sensors, fluorosensors, microwave and radar sensors, and slick thickness sensors are discussed. Special attention is paid to remote sensing of oil under difficult circumstances, such as oil in water or oil on ice. An infrared camera is the first sensor recommended for oil spill work, as it is the cheapest and most applicable device, and is the only type of equipment that can be bought off-the-shelf. The second sensor recommended is an ultraviolet and visible-spectrum device. The laser fluorosensor offers the only potential for discriminating between oiled and un-oiled weeds or shoreline, and for positively identifying oil pollution on ice and in a variety of other situations. However, such an instrument is large and expensive. Radar, although low in priority for purchase, offers the only potential for large-area searches and foul-weather remote sensing. Most other sensors are experimental or do not offer good potential for oil detection or mapping. 48 refs., 8 tabs