The cleanliness and stability of Muroto deep seawater were examined throughout the year. Surface and deep seawater samples were collected monthly from January 2000 to December 2000 on the surface or from a depth of 320 m off the coast of Cape Muroto at the Kochi Prefectural Deep Seawater Laboratory. The numbers and sizes of suspended particles in the seawater samples were analyzed using a particle analyzer. In the deep seawater, the numbers of particles with diameters of 1-50 μm were 334-844/ml (yearly average of 549/ml) and those with diameters of 10-50 μm were only 10-28/ml (yearly average of 19.4/ml). Particle numbers of the deep seawater varied slightly from month to month, but no seasonal variations were observed. On the other hand, the numbers of particles with diameters of 1 -50μm in the surface seawater samples were 1445-7289/ml (yearly average of 4416/ml) and showed clear seasonal variations. The particle numbers of the surface seawater were high in spring and summer, but low in winter. These results demonstrate that the Muroto deep seawater is cleaner and more stable in suspended particles contained than the surface seawater, and therefore it is better use for industrial uses, particularly for those having filtration processes.

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Deep seawater (DSW) is pumped up from a depth of 320 meters off Muroto in Kochi Prefecture, Japan. Since DSW is known to be less polluted and contains various minerals, it has been used for a variety of fermented foods in Japan. To investigate the effects of DSW in Japanese “sake”-fermentation, we carried out small-scale (1-2 L) fermentation tests. The addition of DSW elevated levels of aroma components, including isoamyl acetate, ethyl caproate and ethyl caprylate. For further elucidation of the mechanism underlying this phenomenon, we used cDNA microarray analysis for studying yeast gene expression during fermentation. The addition of DSW substantially increased the transcript levels of several genes known to be involved in the biosynthesis and metabolism of amino acids and fatty acids. It is therefore suggested that the rise in transcription of these genes resulted in the increased aroma production. The sensory evaluation revealed that the addition of DSW in fermentation resulted in significantly superior flavor profile of the final products compared with the addition of NaCl, a major component of seawater. Interestingly, the microarray analysis demonstrated the addition of NaCl by itself induced stress during fermentation as indicated by mRNA levels in “sake” yeast. The addition of DSW appeared to ameliorate the negative effect induced by NaCl. Taken together, these results indicate that addition of DSW in the fermentation processes provides unique advantages for the “sake” production.

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Regional business promotion has been considered by means of resource utilization of deep seawater (DSW) in particular attention to the cost of pumping facility of DSW.
Existing pumping facilities of DSW have been examined their design, construction and cost. Although there is a large scale merit of the pumping facilities in the construction cost, important thing is to chose a suitable maximum size of pumping capacity based upon possible utilization demand of DSW in the area. A business model for regional promotion according to the business scale is proposed under the consideration of construction and running cost of pumping facility.
Choosing a suitable scale for each region, DSW could be used as a resource to support the regional economy.

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In order to evaluate a behavior of pumped-up deep seawater into an euphotic zone, we conducted an field test of a free-drifting buoy equipped with an autonomous CTD vertical profiling vehicle, a current meter and a cruciform drag sail. The autonomous CTD profiling vehicle showed a good performance under favorable sea conditions although the upward movement was not smooth enough under high wave conditions (more than 1-1.5m), and the free-drifting buoy approximately followed in situ current. We also discussed the improvement method of the present free-drifting buoy.

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Muroto deep ocean water has been pumped up from a point within a 3 km distance from the coast and at depths of 320m or 344 m in the sea, in Muroto, Kochi, Japan. In this study, in order to clarify the characteristics of selenium in the Muroto deep ocean water, total selenium and selenium speciation were investigated. Both inorganic and organic selenium were detected, and two distinct features of the selenium were discovered. Compared to ocean surface and river waters, (1) Muroto deep ocean water contained a high level of total selenium, and (2) less toxic selenium species, namely selenite and organic selenide were dominant. The total selenium content of Muroto deep ocean water was in the same range of the North Pacific Ocean. The majority of selenite and selenate occurred in the dissolved fraction; however, around 60 % of the organic selenide was found in the particulate fraction (particles diameter>0.22μm). Selenium contained in the organic and inorganic particulates accounted for 55 and 45% of the total particulates selenium, respectively. Moreover, free and combined seleno-amino acids accounted for more than 70% of the dissolved organic selenide.

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