抄録
“Closed Ecology Experiment Facilities”(CEEF) were constructed at the Institute for Environmental Sciences in Japan to conduct stable carbon isotope tracer experiments for improvement of prediction models on dynamics of radioactive carbon in the environment. A model closed ecosystem including two people, two goats and crops (150 m2), is to be established for four months yearly from 2005 to 2009 in the CEEF. In the experiment conducted under closed conditions in 2003, rice, soybean, peanut and safflower were cultivated sequentially in the closed “Plant Module”(PM) of the CEEF. Transplanting (or seeding) and harvest of each crop at regular intervals were maintained during 28 days, and flows of CO2, O2 and carbon to and from the crops were analyzed. Gas exchange rate and carbon balance of six female goats were determined in a gastight chamber during three or four days using an open-flow measurement system, Human habitation tests in the CEEF lasting five days were conducted under ventilated condition in 2003. Gas exchange of people was calculated using equations predicting gas exchange rate from energy consumption estimated from time records of activity, age and body weight, and respiration quotient (RQ = CO2/O2) measured during experiments conducted outside the CEEF. Total CO2 and O2 exchange for two goats and two men was estimated to be 62 and 71% of those of crops, respectively. It was deduced from the estimation that carbon balances of these three ecosystem components will be equivalent in the long-term. Water balance of crops was also measured or estimated for the 28-day cultivation period. Water balance of animals was also measured or estimated based on closed holding experiments. Water balance of human was measured during the five-day habitation study. The flows of water for the crops, animals and human in the CEEF system were estimated for the most part successfully, although small inconsistence exist.
