Study On Ecology And Water Quality In Lake Koyama

虽然这是该研究项目的最后一年，但新的研究也在继续过去两年的研究。吉田和他的同事们在小山湖最深的地方搭建了观测桥，每隔2小时记录下水面下5.5m处溶解氧、电导率和pH值的变化。结果表明，即使在秋冬季节，在4.5m深处仍有缺氧水的形成。随着水温的升高，这种现象在春夏两季自然会出现。对流入小山湖的长原河和流出小山湖的小山河的挥发性有机物进行了分析。据此分析得出，长原河和小山湖的挥发性有机化合物含量低于流经小山村的小山河。sitizyou博士在三个养鱼池中杂交鲫鱼，孵化鱼卵，饲养鱼苗。鸟取大学附属的小学生们像去年一样帮助我们放生幼鱼，长谷川先生继续记录湖中氯离子的变化。最近三年的研究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.