Richard R. Lessard

The Roles of Photooxidation and Biodegradation in Long-term Weathering of Crude and Heavy Fuel Oils

Abstract Although spilled oil is subject to a range of natural processes, only combustion, photooxidation and biodegradation destroy hydrocarbons and remove them from the biosphere. We present laboratory data that demonstrate the molecular preferences of these processes, and then examine some oil residues collected from previously documented releases to confirm the important roles that these processes play in removing spilled oil from both marine and terrestrial environments.

SAVING OILED MANGROVES USING A NEW NON-DISPERSING SHORELINE CLEANER

ABSTRACT Mangroves are ranked as one of the most sensitive marine environments. If mangroves are oiled and no further action is taken, the probability of mortality to the trees is high. One of the ...

Key Parameters Affecting the Dispersion of Viscous Oil

ABSTRACT Oil viscosity has been perceived as a major factor affecting the dispersibility of oil. Very high viscosity oils—20,000 centistokes (cs) or more—can readily be observed as resisting the breakup of the oil into dispersed droplets. However, there are instances where a relatively viscous oil will disperse much more readily than another oil of similar viscosity. An extensive study has been conducted at ExxonMobil Research facilities in New Jersey to define the molecular makeup of 14 viscous heavy fuel oil products and determine the property of the viscous oils, besides viscosity, that influences dispersibility. Dispersibility was measured by a standard laboratory dispersant test using a COREXIT dispersant selected from the U.S. Environmental Protection Agency (EPA) National Contingency Plan (NCP) Product Schedule. Initially, IATROSCAN (TLC) and gas chromatography data failed to show any correlation between chemical properties, such as sulfur, aromatics, paraffins, resins, vanadium, nickel content, et...

MODIFICATION OF THE DISPERSANT COREXIT®9500 FOR USE IN FRESHWATER

ABSTRACT Recent inland spills in Latin America have generated interest in dispersant use for freshwater oil spills. However, oil spill dispersants primarily are formulated for use in marine waters....

DEMULSIFYING DISPERSANT FOR AN EXTENDED WINDOW OF USE

ABSTRACT Recent data with a modern demulsifying oil spill dispersant (Corexit 9500) challenge old viscosity limits for the window of opportunity for dispersant use on viscous oils and emulsions. Th...

Crude Oil Releases to the Environment: Natural Fate and Remediation Options

Crude oils and other hydrocarbons have been a part of the biosphere for millions of years, so it is no surprise that a ubiquitous, diverse population of hydrocarbon-consuming microorganisms uses this resource as a source of carbon and energy. These organisms can respond rapidly to human-associated oil spills, although sometimes mobilizing their full benefits requires physical treatments to disperse or remove bulk oil, such as by the use of dispersants, mechanical pick-up or combustion. Modern environmentally responsible remediation activities work to stimulate these natural processes without causing any additional adverse environmental impact.

The Impact of Oil Dispersant Solvent on Performance

Modern oil spill dispersant formulations are concentrated blends of surface active agents (surfactants) in a solvent carrier system. The surfactants are effective for lowering the interfacial tension of the oil slick and promoting and stabilizing oil-in-water dispersions. The solvent system has 2 key functions: (1) reduce viscosity of the surfactant blend to allow efficient dispersant application, and (2) promote mixing and diffusion of the surfactant blend into the oil film. A more detailed description than previously given in the literature is proposed to explain the mechanism of chemical dispersion and illustrate how the surfactant is delivered by the solvent to the oil-water interface. Laboratory data are presented which demonstrate the variability in dispersing effectiveness due to different solvent composition, particularly for viscous and emulsified test oils with viscosities up to 20,500 mPa{center_dot}s. Other advantages of improved solvent components can include reduced evaporative losses during spraying, lower marine toxicity and reduced protective equipment requirements. Through this improved understanding of the role of the solvent, dispersants which are more effective over a wider range of oil types are being developed.

MAINTAINING DISPERSANT STOCKPILES AND ASSESSING THEIR QUALITY

ABSTRACT Ensuring the capability to mount a rapid and effective dispersant response when needed for an oil spill includes a proactive approach to manage dispersant stockpiles in such a way as to en...

Exxon Oil Spill Technology Advances from the Valdez Cleanup

ABSTRACT The Exxon Valdez oil spill in 1989 was the largest marine oil spill in U.S. history. It triggered a massive cleanup and accelerated major changes to the U.S. structure for combating oil sp...