Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Characteristics of declining dissolved oxygen concentrations in Lakes Kasumigaura and Kitaura, two shallow polymictic eutrophic lakes in Japan
To elucidate the patterns and characteristics of dissolved oxygen (DO) decline near bottom in shallow polymictic eutrophic lakes, we conducted a statistical analysis of monthly measurements for 12 years at 14 stations and hourly observation for 8 years at two stations in Lakes Kasumigaura and Kitaura. Results indicated that DO decline (hereafter, <2 mg/L) was negligible at stations with a depth of <5 m. Thus, we consider this depth to be critical depth for studying DO decline conditions in these lakes. The collected data revealed that DO decline events lasting more than 2 days occurred a few times a year. During these events, wind blew weakly (usually, <2 m/s), and diurnal stratification was formed by solar radiation. The averaged DO declining rate leading up to these events was 4.3 (±2.7) mg L−1 d−1, suggesting that within a few days, DO can fall into a declined state. The occurrence probability of DO declined events in the respective summer increased significantly with the proportion of weak wind hours (<2 m/s). Significant correlations between wind velocity and DO change rate (1 hr difference in DO) supported the importance of wind on DO changes in polymictic lakes. The influence of mean air temperature on DO decline events was insignificant.
Characteristics of declining dissolved oxygen concentrations in Lakes Kasumigaura and Kitaura, two shallow polymictic eutrophic lakes in Japan
To elucidate the patterns and characteristics of dissolved oxygen (DO) decline near bottom in shallow polymictic eutrophic lakes, we conducted a statistical analysis of monthly measurements for 12 years at 14 stations and hourly observation for 8 years at two stations in Lakes Kasumigaura and Kitaura. Results indicated that DO decline (hereafter, <2 mg/L) was negligible at stations with a depth of <5 m. Thus, we consider this depth to be critical depth for studying DO decline conditions in these lakes. The collected data revealed that DO decline events lasting more than 2 days occurred a few times a year. During these events, wind blew weakly (usually, <2 m/s), and diurnal stratification was formed by solar radiation. The averaged DO declining rate leading up to these events was 4.3 (±2.7) mg L−1 d−1, suggesting that within a few days, DO can fall into a declined state. The occurrence probability of DO declined events in the respective summer increased significantly with the proportion of weak wind hours (<2 m/s). Significant correlations between wind velocity and DO change rate (1 hr difference in DO) supported the importance of wind on DO changes in polymictic lakes. The influence of mean air temperature on DO decline events was insignificant.
Characteristics of declining dissolved oxygen concentrations in Lakes Kasumigaura and Kitaura, two shallow polymictic eutrophic lakes in Japan
Fukushima, Takehiko (Autor:in) / Kitamura, Tatsumi (Autor:in) / Komuro, Syunsuke (Autor:in) / Nakagawa, Keita (Autor:in) / Nagahama, Yumi (Autor:in) / Matsumoto, Syunichi (Autor:in) / Matsushita, Bunkei (Autor:in)
Lakes & Reservoirs: Research & Management ; 24 ; 314-323
01.12.2019
10 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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