1979 Volume 45 Issue 9 Pages 1099-1107
Accurate information on the relations between the environmental conditions and the population density of hydrocarbon-oxidizing bacteria is indispensable to clarify the self-purificalion in the oil-polluted areas. In spite of the above-mentioned importance, little has been known of them, as yet.
To clarify the influence of the environmental conditions on the population density of heterotrophic bacteria, hydrocarbon-oxidizing bacteria groups A (da) and B (db) in seawater of the coastal waters of the different grades of oil pollution, the following areas were chosen: Iwakuni waters (off oil industrial plants), Bisan Seto (one year after the Mizushima Oil Refinery Accident) and Hibiki Nada (slightly polluted area as control). The following factors were measured as the environmental conditions: oil content (dp), chlorinity, COD and water temparature. And various relations of the density of these bacterial groups to these conditions were statistically estimated.
It may be given as a conclusion of the linear regression analysis that the density of bacteria is clearly affected by the environmental conditions, as indicated by the highly significant coefficients.
Further analyses were conducted by the multiple linear equation in which the areas were used as the dummy variables. And it was found that the dummy variables in the relations of the density of groups A and B with oil content were insignificant. Therefore, the difference in respective areas was not recognized in the relations, and the relations were respectively expressed in the following equations.
log da=3.34+1.35log dp
log db=2.17+1.36log dp
The group compositions of bacteria in respective areas were examined in the principal component analysis. And it was found that the accumulated proportions in z1 (size factor) and z2 (shape factor) were about 86 and 96%, respectively. This fact means that the group composition in these respective areas can be characterized by the distribution figure of scores on axes of z1 and z2.
