Characteristics of autochthonous deposition and resuspension of sediments in the Takahamairi bay of Lake Kasumigaura.

Abstract

There was a time lag of one or two months between the peak of primary production and that of autochthonous deposited flux, which resulted in a surprising increase in chlorophyll a concentration of lake water in mid-summer. Calculated autochthonous deposited rates of carbon, nitrogen, and phosphorus in backwater regions and near the inflow river mouth were much higher than those at offshore due to the contamination of allochthonous matter . In regard to the resuspension rates, a logarithmic decrease against water depth and significant correlations with some meteorological conditions were observed. The sum of autochthonous and allochthonous deposited fluxes exceeded the accumulation rates in sediments estimated both by the mass balance method and the sediment dating method by a factor of 8-17 for nitrogen and 2-10 for phosphorus, both of which were much larger than the ratios observed in other lakes.The shallowness of this lake greatly influenced these ratios because of the large resuspension rate followed by rapid decomposition in lake water and high activity of benthos .

Nutrient dynamics and the eutrophication of shallow lakes Kasumigaura (Japan), Donghu (PR China), and Okeechobee (USA)

“…Van Liere and Gulati, 1992). Studies have included long-term observations (Aizaki and Otsuki, 1987;James et al, 1995a,b), experimental manipulations (Moss et al, 1996), detailed studies of the processes involved in nutrient cycling and trophic dynamics (Fukushima et al, 1987;Olila and Reddy, 1993), and the application of dynamic models Matsuoka et al, 1986;James et al, 1997).…”

Seasonal and Horizontal Variations of Heterotrophic Bacterial Number in Eutrophic Shallow Lake Kasumigaura

“…Lake kasumigaura is a shallow lake with a mean depth of 4m and a maximum depth of 7m. In this lake, resuspension of bottom sediments frequently occurs (FUKUSHIMA et al, 1987). Heterotroph numbers at the surface of bottom sediments in Takahama-iri Bay were about 100 times larger than those in lake water (AIZAKI, unpublished).…”