In order to evaluate suspended particle cleanliness of deep ocean water (DOW), 16 onemonth field samples were collected from DOW pumped from 320m below the surface off the Kochi Prefectural Deep Seawater Research Laboratory from July 2005; surface water (SW) pumped from 5 m below the surface was used as a comparison. Weight of suspended particles filtered onto 0.45 μm Millipore membrane filters was measured. Suspended particles in DOW weighed far less than in SW collected on the same day (14% of those in SW). Weights of suspended particles of DOW were always less than 1 mg/L (0.195-0.993 mg/L, average, 0.550 mg/L). No seasonal patterns were observed in either DOW or SW. Specific filtration speed was 1/3 lower in DOW than SW, and a positive relationship between the amount of suspended particles and the specific filtration speed was only observed for DOW and SW when all the data were analyzed together. Observations of suspended particles collected on Millipore filters by scanning electron microscope revealed that particles found in DOW were small, with few organic aggregates, organic-like films, and planktonic algal cells compared to those of SW. However, trace amounts of chlorophyll α (<4 % of SW) were detected in DOW and other researchers observed planktonic algae (mainly diatoms) when DOW from the present study was cultured under illumination. Consequently, it is important for DOW to be stored under tight darkness to avoid germination of algal seed stock contained in the original DOW.

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Deep Ocean Water(DOW)is sea water from at least 200m below the sea surface and has such characteristics as being clean and rich in mineral components compared to surface seawater. Recently, DOW has been considered for application in many fields(agriculture, fisheries, and health industries such as cosmetics, pharmaceuticals and nutrition). Here we studied the property of DOW and its effects on physiological functions. Since DOW has characteristic properties, we classified it as functional water and assessed its properties by measuring pH, electronic conductivity(EC), dissolved oxygen(DO), oxidation-reduction potential (ORP) and residual chloride. As for the effects of DOW on physiological functions, we discussed the relationship between DOW and reactive oxygen species(ROS), which have potentially deleterious effects on biological systems due to damage to proteins, lipids, and nucleic acids, and are generally considered to be toxic to living organisms. Since DOW is rich in mineral components(not only major minerals but also trace minerals), it is utilized as drinking water. We examined the effects of DOW on physiological functions of mice. Sera from mice orally given DOW showed increased superoxide scavenging activity. This result suggested that DOW may induce a biological substance to augment superoxide scavenging activity. Furthermore, we discussed the heat-retention effect of DOW in relation to energy metabolism.

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The five biggest problems in the 21st century are those on population, energy, food, freshwater and earth environment. The key to solving these problems must be the ocean, which has potential resources of water, elements and energy. Deep ocean water (DOW) is particularly promising, because DOW is cold, clean, nutrient-rich and stable in water quality. When DOW is used with warmer surface ocean water, energy can be generated through Ocean Thermal Energy Conversion (OTEC). Among various trials, only the author's group has been successful and new technologies including Uehara Cycle has been developed. To elevate the thermal conversion rate, Integrated Ocean Thermal Energy Conversion (I-OTEC) was proposed. I-OTEC is a cascade use of OTEC combined with various techniques such as desalination of seawater, hydrogen production, collection of Lithium, production of mineral water, formation of fishing ground and air conditioning. The real plant was deployed at Institute of Ocean Energy, Saga University (IOES) and combinations of each technique have been tested. The prospective sites for I-OTEC were distributed to 96 nations or districts. If I-OTEC is applied in 2% of these sites, 200-108 kw of electric power and 400 × 200 × 10⁸ t/year of freshwater may be generated.

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