The dynamic behavior of bacterial flora in the mass culture of larvae of Iwagaki Oyster, Crassortrea nippona was investigated with the addition of Nannochloropsis sp. culture fluids. Three additional methods were examined, 1) addition of Nannochloropsis sp. culture fluid (cell (+)), 2) addition of supernatant from centrifuged Nannochloropsis sp. culture fluid (cell (-)) and 3) no addition of Nannochloropsis sp. culture fluids as control.
The obtained results are as follows;
1) Growth and vital ratio of the larvae by means of added cells (-) are superior to those using other methods. 2) In the cell (-) system, it was found that Moraxella sp. becomes preponderant over Vibrio sp., regardless of initial conditions of bacterial florae in cultivation water, and this dynmic behavior of the bacterial florae is favorable for the mass culture of larvae.

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The determination of dissolved oxygen using the Winkler method in an electrolyte solution such as brine or mother liquid used in a salt manufacturing process is discussed. The solubility of oxygen in pure water at 298-363 K conforms to the value proposed by Winkler. And the measured values of brine obtained from salt farms using the Winkler method and the van Slyke-Neil method are almost the same. It is believed that the Winkler method is effective for measuring the solubility of dissolved oxygen at high temperatures.
On the other hand, the salting-out parameters of oxygen are calculated using the relationship between the solubility of oxygen and the ionic strength in NaCl, MgCl₂, CaCl₂, KCl solutions, respectively. The solubility of oxygen in various mixed electrolyte solutions is accurately estimated by using the salting-out parameters and the ionic strength at 343 and 363 K. From these results, it is believed that the solubility of oxygen can be calculated from the composition of electrolyte solution.

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Major-to-ultratrace elements in common salts were determined by ICP-AES (inductively coupled plasma atomic emission spectrometry) and ICP-MS (inductively coupled plasma mass spectrometry). The salt samples (Fukken salt, Noto salt, Akoh salt, Seto salt, JT salt) were dissolved in pure water, and the salt water solutions were filtered with a membrane filter (pore size 0.45μm). The filtrates and the particulates remained on the filter for each salt sample were analysed as the water-soluble and particulate constituents of salts, respectively. Although the portion of particulates in natural salts was ca. 0.006-0.06%, the concentrations of Al, Ti, Fe, Zn, Ga, Y, rare earth elements, and Th in particulate constituents were more than 80% of their total concentrations in salt. Sodium, K, Mg, Ca and Sr were mostly in water-soluble forms. In addition, more than 80% of Mo and Cd were also in water-soluble forms for all salts examined here, reflecting their chemical forms in sea water.

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The elemental composition (Ca, Sr, Zn and Fe) of otoliths from migrating chum salmon, Oncorhynchus keta, captured at the Kitakami river and Ishinomaki Bay was analyzed to understand the migratory history using aparticle induced X-ray emission (PIXE) technique. The Sr/Ca ratio of salmon otoliths was lower (less than 1×10^-3) in the portion formed in a freshwater environment and higher (approximately 4.8×10^-3) in a sea water environment. When the fish migrated from sea water into a freshwater environment, the otoliths Sr/Ca ratios significantly increased. The highest values were found in the fish captured at the lower part of the Kitakami river (about 20 km upriver from the mouth). The values from the fish captured at the upper part of the Kitakami river (about 200 km upriver from the mouth) were also not less than those of the fish captured at Ishinomaki Bay. Abnormally high otolith Sr/Ca ratios for these upriver-migrating fish, when compared to the values from nonmigrating salmon inhabiting stable environmental (salinity and temperature) conditions, provided evidence that they were stressed. No significant changes in the otoliths' Zn/Ca ratios were found, while these values were inversely proportional to the Sr/Ca ratios. However, a rapid drop in the Zn/Ca ratio and an increase in the Sr/Ca ratio was observed in some individuals in which higher values for the Fe/Ca were found. These results suggest that these otolith parameters don't exactly reflect the salinity and temperature history in upriver-migrating chum salmon because the physiological mechanism of incorporating of Sr, Zn and Ca within the otolith of those fish is abnormal, though for fish in non-stressful conditions the Sr/Ca and the Zn/Ca ratios in otoliths are effective indices for predicting the history of environmental conditions experienced by the fish in the past. Regarding the relationship between the Sr/Ca and the Zn/Ca ratios, and also the Fe/Ca ratio, there is a possibility that they are linked to various ecological and physiological factors.

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Iron uptake rates of Chattonella marina, Gymnodinium mikimotoi and Heterosigma akashiwo were measured using radioactive EDTA-⁵⁹Fe. Adsorbed iron on plankton was removed with a Ti (III) solution after which only intracellular iron was obtained. Order of uptake rates of the plankton in 0.2 μM Fe concentration was 10^-16-10^-17 mol/cell/h. Maximum iron uptake rates and half-saturation constants were respectively 2.5×10^-15 and 0.8 for C. marina and 2.3×10^-15 mol/cell/h and 0.6 μM for G. mikimoto.

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The exergy conversion efficiency was calculated in the case where a low level exergy of heat discharged from a factory is converted into a high exergy level of electricity via dialytic battery, and was found to be in the range of 0.494% to 0.797%. Efficiency increases with an increase in feed temperature and in the case of counter-current feed flow configuration. The feed to the dialytic battery is composed of sea water and concentrated sea water, which is concentrated by evaporating water by means of a cooling tower. The heat required is extracted from the warm industrial waste water discharged from factories.
The sea water, whose temperature is raised to 40°C, is fed into an ideal cooling tower and placed in contact with the air (temperature 15°C, humidity 70%, the yearly average values in the Tokyo area). At equilibrium, about 5% of the water being fed to the cooling tower is evaporated and the temperature of the concentrate is lowered to 12°C. The ideal cooling tower number is found to be 47 for concentrating the sea water to a saturated state (26.4 wt% salt).
The dialytic battery is composed of 1000 paired anion exchange membranes and cation (area resistivity 2Ω·cm² for each) and a maximum output of 43.3 kW was calculated at the following operating condition; 40°C, saturated sea water (5415 mol/m³), fresh sea water (598 mol/m³), average feed velocity 0.01 m/s.
Assuming that 10% of one million yen/kW as the initial investment for this system is allocated to the membrane, the cost of the membrane might be 50 yen/m² in the case of 1 W/(m²·pair), and 150 yen/m² in the case of 3 W/(m²·pair).

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