CORRESPONDENCE
SIR: Your November ’74 Current Research section had a paper which showed that mussels were killed and oysters harmed by “diluted” outboard motor effluents. A quick calculation of this “low level” water pollution in relation to the number of boats needed to produce it shows: (a) the combustion products of 5 liters of fuel wound up in 2500 liters of seawater; this killed mussels; ( b ) it took 100 min for an 18-hp outboard to consume the 5 liters of fuel (these two steps are data from the paper); and (c) if all this happened on a water body 3 meters deep, it would require a straight 24-hr run by a group of boats each occupying a space 3 by 4 meters on the water surface. This is the supreme nightmare of all boaters-wall t o wall boats! Too bad the authors didn’t consider the effects on the boaters-fumes, noise, collisions, etc. I’d rather be an oyster. 2525 Blackwood Road Wilmington, Del. 19810
Donald W. Smith
Reply
SIR: Donald W. Smith very ably emphasizes the problem of relating preliminary data obtained in the laboratory to the real world. We did not state in the paper that wallto-wall outboard motors are a realistic probability-although there are sports fishermen who will argue the point, especially on opening day of the fishing season. We believe, however, that our initial statement, “Outboard motor effluent may be a significant source of petroleum pollution in the aquatic environment,” represents a realistic assessment of the danger to some productive estuarine environments. In point of fact, the 50-ppb n-hydrocarbon content of the outboard motor effluent used in our study seems reasonable a s an upper limit for a bioassay when compared with a value of 7 ppb of n-hydrocarbons we found in water near a boat-launching ramp in Puget Sound. Shellfish do not grow to maturity in the relatively unpolluted high seas as do tuna and salmon. Oysters and mussels are, like most aquacultured organisms, convenience crops grown close to home and close to active petroleum-powered boat traffic. Oysters and mussels are filter-feeders, concentrating particulate matter by pumping many liters of seawater daily and exposing themselves to food and to whatever else the water may hold. When petroleum leakage from boats occurs in an area of limited flushing, especially in shallow estuaries where oysters are grown, the potential for shellfish pollution becomes real as petroleum toxicants accumulate. Set in the context of sediment-incorporated petroleum components continuously replenished and released through time, the additional effluent from outboard motors could indeed represent an underestimated source of pollution to living marine resources. The data from our laboratory studies indicated that small amounts of petroleum from outboard motor wastes may adversely affect shellfish. We hope that someone will now have the opportunity to evaluate water quality, a t the ppb level, of productive marine environments shared above by man and below by valuable marine organisms sensitive to toxic components of petroleum. For John S. Finley, Northwest Fisheries Center, and Gary G. Gibson, Oregon Fish Commission, Robert C. Clark, Jr. Research Oceanographer Northwest Fisheries Center Seattle, Wash. 981 12
SIR: In July ’74 issue of Environmental Science and Technology, Sutton and Calder ( I ) state that “there is no mention in the literature of solubilities of the higher normal paraffins in high ionic strength media such as seawater.” Thus they studied the dissolution of several highermolecular-weight n-paraffins (n-Cl2 to n-Cz6) in distilled water and in one seawater sample. We wish to inform the readers of your journal that we have previously presented an in-depth study of hydrocarbon “solubility” in saline solutions and in seawater ( 2 ) using n-paraffin (n-& and n-Czo), aromatic, and isoprenoid hydrocarbons. We intentionally put the word “solubility” in quotes as our study indicated that the quantities of hydrocarbon passing a filter are very much dependent on many experimental factors. As we had cautioned readers of our work against interpreting values that we obtained as “absolute hydrocarbon solubilities,” we wish to stress this again to readers of Sutton and Calder ( 1 ) . These authors employed an identical criterion for “solubility” as we did; that material which passes a filter. However, they have not considered and therefore failed to indicate that the shaking and standing times of the hydrocarbon/water mixture, the type of filter used and its pore size, the amount of hydrocarbon added to a given water volume, all will affect the n-paraffin “solubility” values obtained (2-4). Sutton and Calder ( I ) also do not consider the important role that the dissolved organic matter in seawater plays in making n-paraffin hydrocarbons more “soluble” ( 2 ) . In considering the “solubility” behavior of hydrocarbons through an estuary and into the open ocean, we have found in studies on high ionic strength media that not only can the dissolved organic matter play an important role (especially in near shore waters), but that the combined effect of this material and the changing salinity in the media gives a nonlinear “solubility” trend ( 2 ) . We also found that n-paraffin “solubility” in seawater is dependent on the p H of the media (2). Therefore, it appears that Sutton and Calder ( I ) have presented an incomplete and hence misleading picture of the solubility behavior of hydrocarbons in estuarine waters between 0 and 35% salinity. Literature Cited (1) Sutton, C., Calder, J. A , , Enciron. Ski. Tech., 8,65447 (1974). (2) Boehm, P. D., Quinn, J . G., Geochim. Cosmochim. Acta, 37, 2459-77 (1973). (3) Peake, E., Hodgson, G. W., J . A m . Oil Chem. Soc., 43, 215-22 (1966). (4) Peake, E., Hodgson, G. W., ibid.,44, 696-702 (1967).
Graduate School of Oceanography University of Rhode Island Kingston, R. I . 02881
Paul D. Boehm James G. Quinn”
Reply SIR: We would like to reply to the comments of Boehm and Quinn regarding our article in a recent issue of Enuironmental Science and Technology(1). We feel that many of these comments are either incorrect or irrelevant for reasons given below. I t was not our intention to present a “complete” picture of the behavior of hydrocarbons in water, but rather to determine, with as much rigor as the techniques available to us would permit, the true solubility of the hydrocarbons tested, to determine their empirical salting parameter, and to compare this parameter to one calculated from a rather simple theory. We did not attempt to mimic the real environment, but rather attempted to provide hard data which could serve as a partial basis for understanding it. We feel the critical reader will find adequate Volume 9, Number 4,April 1975 365
