SPILLS OF EMULSIFIED FUELS: Risks and Response by National Research Council

Author:National Research Council
Language: eng
Format: epub
Tags: Environment and Environmental Studies : Waste Disposal and Clean Up
Publisher: NATIONAL ACADEMY PRESS
Published: 2002-01-29T00:00:00+00:00

UNDERSTANDING ECOLOGICAL RISKS ASSOCIATED WITH SURFACTANT

Although the impacts of petroleum hydrocarbons on marine and aquatic organisms have been studied for years, the long-term chronic effects of the surfactants used in Orimulsion-400 and many other household products, are less well understood. Consequently, additional discussion of these compounds seems warranted. Surfactants in oil and bitumen emulsions are predominantly two types: (1) the AE and (2) the alkylphenyl ethoxylates (APE) and nonylphenol ethoxylates (NPE), together referred to here as APE (Karsa, 1998; Talmage, 1994). In 1998 an estimated 465 million pounds of AE and LAS were used predominantly as surfactants in household products in the United States (Stanford Research Institute, 1998). Given their widespread use, their possible toxicological interactions (i.e., additive effects), their presumed concentrations in some major U.S. rivers, and the risks they pose in aquatic systems, major synthetic surfactants (AE, APE, and LAS) are receiving greater attention from environmental protection agencies worldwide. This is especially true since background concentrations of surfactants and their intermediary decay products, together with their additive effects with indigenous pollutants, may already have impacted aquatic resources and human health, notwithstanding the effects from accidental spills of emulsified fuels.

Criteria for allowable concentrations of the synthetic commercial blends of surfactants (AE, APE, and LAS) apparently do not exist in the United States. Yet their reportedly low concentrations in the 1980s may only reflect dilution by the very high discharges in U.S. rivers, compared to the smaller rivers in other industrialized nations (Ahel et al., 2000; Naylor et al., 1992). Currently, there is no monitoring program in the United States designed to track changes in loading rates of specific surfactants to rivers. Only one study in the late 1980s reported a concentration of 0.5 ppb above, and 1.1 ppb below, an effluent of the commonly used AE in a river (Talmage, 1994).

In view of this, it is instructive to view environmental risks of spilled emulsified fuels from another perspective. A spill of the entire contents of one barge loaded with 3,000 barrels of Orimulsion-400, at 6.2 barrels per metric ton, would release about 1,380 pounds of AE (at 0.13 percent by volume in Orimulsion-400). Were this to occur in the lower Mississippi River at average discharge (about 500,000 cubic feet per second [cfs]), the concentration of surfactant would be about 80 ppb immediately downstream of the spill, if the background levels were zero. This concentration (80 ppb) is about one-fourth of the 0.28 ppm concentration derived for use in risk assessment of AE, estimated from stream mesocosm investigations (Dorn et al., 1997). However, it is near the predicted NOEC (110 ppb) for AE, estimated to be 50 to 100 times lower than the predicted environmental concentrations, derived from monitoring results of removal rates for AE and other surfactants by sewage treatment facilities (van de Plassche et al., 1999).

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