ABSTRACT

A study of the in-situ behavior and effects of several oils in the subsurface marine environment was conducted in Jan. 1973. A major portion of the field work was conducted during a 7-day saturation dive by the authors operating out of Hydro-Lab, an underwater habitat located in 50 ft of water approximately it miles off Freeport, Grand Bahama Island. Mixtures of a variety of oils and sinking agents were exposed to the subsea environment to investigate sinking-agent effectiveness, and oil degradation, solubility, and migration through bottom sediments. These phenomena were studied both for their intrinsic importance to the ultimate understanding of the subsurface effects of oil and in relation to the feasibility of more comprehensive, in-situ studies of oil-pollution effects on marine biota.

Limited biological experiments were conducted that resulted in the development of experimental procedures to be used in a similar (Phase II) mission planned for May 1974.

Operating from an underwater habitat proved to be a particularly effective procedure for studying the behavior of submerged oil and its short-term impact on marine organisms. The insensitivity of submerged oil to derogative and dispersive activity, combined with the significance of certain biotic responses to its presence, point to the need for continued short-term and long-term investigations of submerged oil impact on the marine environment.

INTRODUCTION

Most of the information currently available on the in-situ behavior and effects of hydrocarbon pollutants in the marine environment has been derived from work on "spills of opportunity." Such field study programs are planned and instituted after an oil spill occurs in which large quantities of oil are released to the environment. The study directed toward the assessment of the environmental impact of the 1969 Santa Barbara oil spill (Straughan and Kolpack, 1971) is typical of this approach.

There are, of course, a number of disadvantages to this type of approach as an applied research technique for investigating the behavior and effects of oil in the marine environment. Among these are the lack of trained on-site observers, missing or poor data on the magnitude and nature of the spill, the absence of information necessary to compare pre- and post spill conditions, and the complete lack of experimental control.

Our work was designed to circumvent these conditions and to systematically develop basic information on the behavior and effect of hydrocarbons introduced by man into the marine environment. The focus of our efforts was on the subsurface aspects of the problem, since it is the ocean floor where spilled oil oaten ends up, due to natural weathering phenomena or to man's use of sinking agents. Once on the bottom, oil may then have a significant environmental impact upon bottom-dwelling fauna and flora.

Another important goal during our program was the assessment of the concept and feasibility of conducting in-situ, underwater oil pollution research from a fixed habitat. Existing research tools and techniques were either modified or new ones developed and their usefulness in this type of work was examined.

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