In order to determine algal growth in aquacultural wastewater and the effect of the addition of digested aquacultural solid waste, 7-days culture experiment using the green alga Scenedesmus quadricauda was conducted at a constant temperature of 25°C under continuous light and aeration. Media treatments used in the experiment were derived from diluted wastewater and solid waste that was digested with concentrated sulfuric acid and hydrogen peroxide at 440°C. Treatments included diluted wastewater (WW), diluted wastewater with solid waste which had undergone digestion (WW/SW), and diluted wastewater with sulfuric acid and hydrogen peroxide (WW/SA/HP) as a control. Algal growth occurred in all media treatments examined although low growth and nitrogen removal was recorded in WW and WW/SA/HP. Final readings in WW and WW/SA/HP for phosphorus were not detected. These results indicated that two treatments without containing solid waste were insufficient phosphorus as a nutrient for the algal growth. In contrast, growth of S. quadricauda in WW/SW was higher than in the other two treatments and was comparable to algal growth observed in synthetic medium. The final readings in WW/SW for nitrogen, phosphorous, potassium, iron, manganese, zinc and copper were reduced by over 70% when compared to the initial readings. It is clear from these findings that the addition of digested solid waste resulted in superior nitrogen removal from aquacultural wastewater by S. quadricauda.

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A method for estimating three-dimensionally DTM (Digital Terrain Model) and DCHM (Digital Canopy Height Model) from range data measured by a portable scanning Lidar was examined. This method is expressed by (1) measurement of ground and tree canopy from nine points using a portable scanning Lidar, (2) transformation from polar coordinate to orthogonal coordinate and estimation of DEM (Digital Elevation Model) for each set of range data, (3) estimation of a composite DEM from DEM's obtained at nine points, (4) estimation of DTM from the composite DEM, and (5) calculation of DCHM by subtracting DTM from the composite DEM. As a result, the DCHM and DTM showed exact tree canopy and terrain surfaces. The error of DCHM was within 0.34 m (0.18 m in RMSE) in comparison with results measured by a rangefinder.

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Gas exchange rates for 20-m² soybean (Glycine max [L.] Merr.) stands were tracked throughout growth and development in three separate experiments with different photosynthetic photon fluxes (PPF) levels. Canopy photosynthesis and transpiration rates increased in all three experiments with canopy ground during early growth (10 to 30 days after planting-DAP) and reached a maximum ca. 40 DAP. Dark period respiration rates increased with increasing biomass (10 to 30 DAP) and reached a maximum ca. 30 to 40 DAP. Photosynthetic rates showed a linear increase with growth PPF levels in the three experiments, as well as during short-term tests in which lamps were dimmed to achieve different PPFs. In contrast, canopy transpiration rates were similar in all three studies. Photosynthesis and transpiration rates both decreased as the stands matured (ca. 55 to 90 DAP), whereas dark period respiration rates remained relatively constant until ca. 75 DAP, after which the rates gradually decreased.

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Dynamic and simultaneous evaluation of the rates of uptake of water and mineral nutrients by roots of the plant population was enabled in the NFT (Nutrient Film Technique) system. The system is composed of a circulation unit (an NFT bed, a reservoir tank, etc.) and a water supply unit (a water supply tank, a solenoid valve, etc.) for controlling the nutrient solution. A water level sensor is installed in the circulation unit to detect the decrease in the volume of nutrient solution caused by the uptake of water by plants. The circulation unit is automatically replenished with fresh nutrient solution from the supply unit by the on-off action of the solenoid valve which is manipulated according to a feedback signal from the water level sensor. Therefore, the rate of water uptake by roots can be evaluated from the supply volume per on-off action of the solenoid valve and the frequency of the on-off action. The rate of uptake of mineral nutrients by roots can be evaluated based on the quantity of mineral nutrients introduced with the supplied fresh nutrient solution and the change in the concentration of mineral nutrients in the circulation unit. High accuracy in dynamic and static characteristics of the evaluation system was demonstrated by the performance test in which the rates of uptake of water and a mineral nutrient were changed in stepwise every hour. The system is applicable to short and long-term measurement of uptake rates affected by fluctuating solar radiation and salt stress in the greenhouse.

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Necessity of ethical principals for eco-engineers was examined. In Western countries, ethical principals or standards and guidelines have been stipulated and maintained by scientific societies for engineering. In Japan recently, numbers of scientific societies that state ethical principals or standards are increasing rapidly. It was considered that establishment of ethical precepts is getting to be a necessary condition to be accepted by society or global society. Ethical problems on Eco-engineering studies were also examined. As a result, various types of problems, including engineering, ethics, environmental ethics and medical ethics, were found out. We confirm eco-engineers' responsibility for human society and propose to discuss ethical principals or standards for eco-engineers.

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Ethical problems on eco-engineering experiments, especially on the Mini-earth project using the Eco-nauts was examined. Results showed that studies of eco-engineering had severe bio-ethical problems when those studies adopted an ecological system including humans as experimental subject. On the Mini-earth project, there appeared the problem as informed consent on the Eco-nauts. The problem was placed in the context of bio-ethics. As a result, we concluded that institutional review board (IRB) was effective for the Mini-earth project and partnership between researchers and Eco-nauts were essential.

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