Study On Ecology And Water Quality In Lake Koyama

虽然这是该研究项目的最后一年，但新的研究也试图延续过去两年的研究。吉田和他的研究人员在小山湖最深处附近建造了观测桥，每隔两小时记录一次水面下 5.5m 深处的溶解氧、电导率和 pH 值的变化。结果，即使在秋季和冬季，在4.5m深处也发现了缺氧水的形成。春夏季节，随着水温变暖，这种现象自然会出现。对流入小山湖的长良河和流出小山湖的小山河中的挥发性有机化合物进行了分析。由此分析得出，长良河和小山湖中的 VOC 含量低于流经小山村的小山河。Sitizyou 博士在三个鱼类养殖池中对鲫鱼进行杂交、孵化卵、饲养鱼苗。鸟取大学附属的小学生和去年一样，帮助我们放生了幼鱼。长谷川先生继续记录湖中氯离子的变化。过去三年取得的成果被写成两篇论文，并在1999年曼谷举行的国际会议上发表。

Although this was last year of this research project, new study was also tried continuing the last two years study.Yoshida and his co-researchers constructed the observation bridge near the deepest place in Lake Koyama, and recorded the changes of dissolved oxygen, electric conductivity, and pH at the 5.5m deep under water surface at two hour intervals. As the results, the formation of oxygen-deficient water was found at 4.5m deeper even in Autumn and Winter. It is natural that this phenomena will occur in Spring and summer as the water temperature is getting warmer. Volatile organic compounds in the river Nagara, which flows into Lake Koyama and in the river Koyama flowing out of Lake Koyama, were analyzed. It derived from this analysis that VOC in the river Nagara and Lake Koyama was found less than that in the river Koyama which flows through the Koyama village.Dr.Sitizyou crossed crucian carp, hatched eggs, raised fries in three fish breeding ponds. Primary school students attached to Tottori University helped us by releasing young fishes like last year.Mr.Hasegawa continued recording the changes of chlorine ion in the lake. The results gained during last three years were written into two papers and made presentation at the International Conference held in Bangkok, 1999.