Limnogicai Features of Lake Yogo-ko in the Summer of 1969

概要

論文の詳細を見る
Physico-chemical and biological properties of Lake Yogo-ko were investigated in the summer of 1969. A weak thermal stratification was observed with a gradient of 0.5° per meter in the depth of 4-8m. In late summer, dissolved oxygen disappeared in the layer near bottom. The concentration of NH3-N varied from 48 μg/l in early summer to 2 μg/l in late summer, whereas PO4-P was present close on the same concentration (15-23 μg/l). Melosira italica and Melosira granulata were dominant during June and August, and Ceratium hirundinella in September. The amount of chlorophyll-a in the whole water column varied in a range of 40 mg/m2 to 48 mg/m2 and the daily net primary production ranged from 0.75 g CO2/m2/day to 0.88 g CO2/m2/day during the summer. Upon surveying the data of the last thirty years, Lake Yogo-ko has progressed in eutrophication rapidly in the last decade, and it is moderately eutrophic at present.
日本陸水学会の論文