"INTRODUCTION In July 1970 Battelle initiated a research program for Esso Research and Engineering Company for an integrated laboratory and field study on the effects of undispersed and dispersed oil in the marine environment. In January 1971 the program responsibilities were assumed by the Committee for Air and Water Conservation^ now the Committee on Environmental Affairs@ of the American Petroleum Institute. This program was exploratory at its outset. Principal objectives as it developed were to determine the toxicity of oil and chemically dispersed oil on marine organisms@ to develop the bioassay procedures@ and to delineate those chemical@ physical@ ecological and microbial factors which would have important influence on the determinations of toxicity. It was envisioned that these laboratory findings would be validated@ in follow-on work@ not here undertaken@ in simulated natural conditions. Each of the tasks proposed for the initial laboratory phase was designed to be applied during the proposed field phase@ or to the assessment of an actual oil spill and need to be considered in that context. Exposure times for the experimental studies on acute@ chronic and sublethal toxicity were limited to relatively short duration exposures which would normally be associated with the accidental discharge of oil. Many of the experimental techniques for the bioassay studies have been described in a research report for an earlier program sponsored by the American Petroleum Institute entitled ""Development o. Bioassay Procedures for Oil and Oil Dispersant Chemicals."" The flow-through bioassay system was developed in lieu of the standard static bioassay test. The flow-through bioassay system has many advantages in that it provides a chemically fresh contaminant at metered concentrations@ which is important when using chemicals with volatile or unstable components@ and a continuous replenishment of diluent water with controlled water quality parameters@ which minimizes the effect of metabolic by-products. The method also provides the only practical approach to long-term studies. There are however some complicating factors when using oil as a test material in any system. First@ oil is a complex mixture of components which have different degrees of volatility and solubility in seawater. Second@ these components have different toxicities and toxic mechanisms to marine organisms. The bioassay studies reported here have for the most part only considered oil per se@ and no studies have been carried out using individual or separated components. Two methods were considered for mixing the oil with the seawater in the test bioassays. In the first@ oil and water could be mechanically mixed to a degree that a uniform distribution of small oil globules would exist throughout the system. In the second@ the oil and water could be contacted in a static mixer and then allowed to separate into two phases on passing through the system@ with the oil on the surface and only very small oil globules present in the tank volume. In both cases solubilization of some of the components would occur. The second approach was used in these studies since it more nearly approximates the conditions that would apply in the case of a spill or discharge to the environment. Direct contact by the organisms with the oil would be limited and they would only be exposed@ in most cases@ to the small oil globules and the solubilized components. While an attempt was made to develop as realistic a bioassay system as is presently feasible for laboratory approaches@ one must keep in mind how far removed from realistic circumstances any laboratory approach is in actuality. Foremost considerations are the natural processes of dilution and degradation of oil in a spill situation. Dilution typically takes place more rapidly than the 96 hour period considered standard for determination of the TLm@ and one therefore might wish to consider a shorter period as more representative e.g. 24 or 48 hours. Microbial decomposition can be quite rapid@ and in our work we have had to take exceptional precautions to prevent marked hydrocarbon losses@ even in the laboratory handling of oil in water samples. Other factors tending to lessen oil exposures in a natural situation are evaporation@ photo-oxidation@ and particle adsorption/sedimentation. By comparison@ in the laboratory bioassays the organisms are effectively confined to relatively high concentrations of oil. Under these conditions the organisms are exposed to a ""worst case"" situation unlikely to exist in a natural environment. In the standard bioassay test methodology the TLm for a toxicant is expressed on the basis of the metered inflow@ and our data are expressed in these terms for comparison with other oil bioassay studies. However@ the TLm values based on metered inflow of oil do not necessarily represent the oil concentration to which the organism is exposed. We therefore determined the concentration of oil in a series of calibration runs in order to compare the metered inflow with the concentration of oil in the water column which represents an estimated exposure concentration. In ail of the bioassay tests we have not considered the effects of many parameters which are controlled by natural processes@ and which would affect the persistence@ and hence the toxicity of oil following a release to the environment. These parameters include dilution effects expected@ evaporation@ photo-oxidation@ adsorption on particles with subsequent sedimentation@ and microbial degradation. For most processes the rate at which the oil passes through the bioassay system is short@ in comparison with the time required for these reactions to be effective in altering oil concentrations affecting the bioassay. For the reasons outlined in the paragraphs above@ it remains extremely difficult to extrapolate any laboratory bioassay results to the actual toxicological effects in a marine environment after an oil spill. Kuwait and South Louisiana were the two crude oils used in this program@ because they are extensively transported by industry. The first is a heavy oil of high sulfur content; the second@ a lighter oil of high paraffin content. No. 2 fuel oil was the principal refined product used@ because of its aromatic content. The oil used was unusually high in aromatics (40%). Since the inception of this program certain changes have been made@ by mutual agreement between Battelle and the Committee. These changes principally involved greater effort directed to the rather difficult analytical problems arising in connection with sampling and measuring hydrocarbons in the two-phase oil/water system. Also@ at the request of the Committee@ preliminary studies were conducted on the overall rate of accumulation and loss of paraffin and naphthalene compounds by selected marine organisms. These studies did not include research on the mechanisms and kinetics of transfer@ accumulation and loss. Specific analytical methods were@ however@ developed for these studies."
API PUBL 4191-1973 history
1973API PUBL 4191-1973 EFFECTS OF OIL AND CHEMICALLY DISPERSED OIL ON SELECTED MARINE BIOTA — A LABORATORY STUDY