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EFFECT OF AMOUNT OF CRUDE OIL ON EXTENT OF ITS BIODEGRADATION IN OPEN WATER- AND SANDY BEACH-LABORATORY SIMULATIONS
Citation:
Lepo, J. E., C R. Cripe, J. L. Kavanaugh, S. Zhang, AND G. P. Norton. EFFECT OF AMOUNT OF CRUDE OIL ON EXTENT OF ITS BIODEGRADATION IN OPEN WATER- AND SANDY BEACH-LABORATORY SIMULATIONS. ENVIRONMENTAL TECHNOLOGY. Selper LIMITED, London, Uk, 24:1291-1302, (2003).
Impact/Purpose:
We examined the biodegradation of varying amounts of artifically weathered Alaskan North Slope crude oil in laboratory microcosm test systems that use natural seawater and simulate spills in open water and on sandy beaches
Description:
Bioremediation of marine oil spills, a technology using hydrocarbon-degrading and emulsifying capabilities of microorganisms, has many unexplored limitations, and among them is degree of environmental oil contamination. We examined the biodegradation of varying amounts of artificially weathered Alaskan North Slope crude oil in laboratory microcosm test systems that use natural seawater and simulate spills in open water and on sandy beaches. The model bioremediation treatment consisted of periodic applications of marine bacteria, selected to degrade n-alkanes and a range of aromatic compounds, suspended in a salts solution that suplied inorganic N and P. The highest levels of oiling, 1.9 ml for the beach, and 2.5 ml for the open water, created nominal 0.5-mm slicks; a series of lower oil doses were tested for each microcosm. Beach microcosms dosed with 0.38 ml lost an average of 22.5% weight in response to model bioremediation treatments whereas those with the high-dose oiling lost 11.3%. Open-water microcosms dosed with 0.25 ml lost 19.1% in response to model bioremediation treatments and microcosms with high-dose oiling lost 2.9%. Thus, the lower doses of oil were more highly degraded as reflected in percentage of total oil weight lost. The model bioremediation treatment also affected a greater number of the selected analytical endpoints in the lower-oil-dose tests than it did in the high-dose experiments and the lower-dose-rate tests showed more substantial degradation of the more recalcitrant components. Based on observed biodegradation trends in these microcosm systems we believe that bioremediation will have practical effect within a rather narrow range of oiling levels. Above a certain threshold, bioremediation may not remove enough of the oil to be considered effective. Below a certain amount of oil the distinction between the active bioremediation treatment and the intrinsic biodegradation of the controls was less prominent, i.e., fewer of the oil component