Osamu Nishimura

Grazing characteristics of musty-odor-compound-producing Phormidium tenue by a microflagellate, Monas guttula

Abstract The grazing characteristics of musty odorous 2-methylisoborneol-(MIB)-producing Phormidium tenue by a microflagellate, Monas guttula , were studied in a batch culture experiment. M. guttula , which was isolated from the biological treatment facility of water supply treatment processes, could effectively graze the viable cells of P. tenue with 98% removal ratio within 24 h at an initial concentration of 3.4 × 10 6 filaments ml −1 . The maximum specific growth rate of 3.8 day −1 and the saturation coefficient of 0.5 mg liter −1 of P. tenue concentration as a substrate were obtained. M. guttula was found to be the main contributor of MIB degradation. Removal ratio of MIB with the initial concentration of 120 μg liter −1 by M. guttula was 42% at 48 h of cultivation, but bacteria without M. guttula could not degrade MIB.

Testing an artificial beach system for removal of pollution in a coastal zone

The developmental activities and utilizations of Japanese coastal seas have been increased recently. Consequently, the production of coastal fisheries, especially of those in enclosed seas, are considerably affected by artificial impacts such as reclamation from the sea and increased pollution load. The objective of this paper is to propose a new ecotechnological method to recover the polluted coastal environment by using an artificial beach system. An artificial beach (5 m × 10 m) was constructed in the Matsushima Bay facing the Pacific Sea, about 300 km northeast from Tokyo. The area was polluted by fishery production and untreated wastewaters from rural district. The major merits of this system are simplicity of the structure, energy-free operation, capability to use tidal current cycle effectively, and ease of maintenance. The results of field investigation indicated that rapid removals of turbidity, suspended solids, phosphorus and ammonium nitrogen by the artificial beach system were achieved. The removal rate of total organic carbon was high because of the retention of the particulate matters. These performances were related to physical and biological filtration through the artificial beach system. It suggests that restoration of polluted coastal area may be expected using this artificial beach system.

STUDY ON BIOACCUMULATION OF TRACE METALS IN SESSILE ANIMALSIN SHIMIZU PORT SEAWALL

The Port of Shimizu consists of semi-closed estuaries, and the heavy metal content of its water is higher than in open sea water. This contaminant presumably flowed into the harbor where it accumulated in the past. Recovering these contaminants would be extremely costly and energy-intensive, so it is not realistic. So this study examined a method of recovering this contaminant through bioaccumulation by the food chain. The state of sessile animal was investigated and the change over time of the amount of heavy metals accumulated in oysters and mussels that are the dominant species in the Port of Shimizu was surveyed, to set the appropriate recovery time for these sessile animals. They accumulate trace metals in a higher density than in the sea water within the port. Moreover, the sessile animals within the Port of Shimizu port die in larger numbers than during the summer. Therefore, it was assumed that the most appropriate recovery time is the spring season before the sessile animals die, regardless of the amount of trace metals accumulated in their tissue.