What is the future of Lake Kussharo, which has been naturally recovering from acid lake of pH 4, eutrophication or acidification once again?

已经从pH 4的酸性湖、富营养化或再次酸化中自然恢复的屈斜路湖的未来是什么？

• 批准号: 15510017
• 负责人: TANAKA Atsushi
• 金额: $ 2.5万
• 依托单位: National Institute for Environmental Studies
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15510017/
• 关键词: Lake Kussharo; acidic lake; water temperature; alkalinity; water budget

Water sampling and observation with CTD were repeated in summer and winter ice-covered seasons. Warm water was supplied from the lake bottom and it was mixed quickly, as was observed last year. Bottom water was cooled to 2℃ in winter, whose density was lighter than the maximum density of water. It was recognized that convection continues even in winter and anormal temperature profile was formed. Flow rate measurement and sampling from more than 10 inflow rivers and one outflow river (Kushiro River) were repeated. With a help of volunteer working around the lake, monthly sampling and observation of Kushiro River started.Loggers for water temperature, conductivity, chlorophyll and turbidity moored at the deepest point of Lake Kussharo from September 2003 were recovered in August 2004. It was shown that lake water mixed throughout the water column in autumn and spring mixing periods, and then the water temperature changed continuously without stabilization at the temperature of maximum water density. Chlorophyll concentration increased just after the ice melting. The logger for water temperature and conductivity was moored at the river mouth of Yukawa, which is acidic and rich in ionic components and the most important site to calculate the acid budget.Alkalinity and ionic components were determined. As a result, slight decreases in the concentration for ionic components and increase in that of alkalinity were detected through precise measurements. For the alkalinity does not decrease at present, re-acidification of Lake Kussharo is not expected. On the other hand, chlorophyll bloom in the spring might be a trigger or symptom for the eutrophication. Continuous observation as well as utilization of public monitoring data for nutrients is required to detect the change in the trophic stage of Lake Kussharo.

在夏季和冬季冰封季节重复进行CTD水样采集和观测。温暖的水是从湖底供应的，它很快就混合了，就像去年观察到的那样。冬季底层水冷却至2℃，其密度小于水的最大密度。人们认识到，即使在冬季，对流仍在继续，并形成了正常的温度廓线。对10多条流入河流和一条流出河流（钏路河）进行了流量测量和采样。在志愿者的帮助下，开始了对钏路河的每月采样和观测。2003年9月以来，在钏路湖最深处停泊的水温、电导率、叶绿素和浊度记录仪于2004年8月被回收。结果表明，在秋季和春季混合期，湖水在整个水体中混合，然后水温连续变化，在最大水密度温度处不稳定。叶绿素浓度在冰融化后迅速上升。水温和电导率记录仪停泊在汤川河口，该河口呈酸性，富含离子成分，是计算酸平衡的最重要地点，测定了碱度和离子成分。结果，通过精确测量检测到离子组分浓度的轻微降低和碱度浓度的增加。由于库沙罗湖的碱度目前没有下降，预计不会再次酸化。另一方面，春季的叶绿素水华可能是富营养化的诱因或征兆。持续观测以及利用公共监测数据的营养盐，需要检测库沙罗湖的营养阶段的变化。