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Horizontal sedimentation differences in a eutrophic Swiss lake
Author(s) -
Bloesch Jurg,
Uehlinger Urs
Publication year - 1986
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1986.31.5.1094
Subject(s) - nepheloid layer , sedimentation , profundal zone , settling , sediment , eutrophication , hydrology (agriculture) , particulates , environmental science , littoral zone , oceanography , geology , phosphorus , sediment trap , water column , nutrient , geomorphology , ecology , chemistry , geotechnical engineering , environmental engineering , biology , organic chemistry
Settling fluxes measured by means of sediment traps were 887 g dry wt m −2 yr −1 , 113 g POC m −2 yr −1 , and 2.6 g PP m −2 yr −1 in 1982–1983 at a central station in eutrophic Lake Hallwil, Switzerland. Nearshore settling rates were higher by a factor of 1.4–3.4. Since particulate organic carbon (POC), particulate phosphorus (PP), and biomass concentration in the lake water showed vertical rather than horizontal differences, this result was attributed to permanent bottom sediment resuspension and redeposition in the littoral zone. Horizontal sediment transport (sediment focusing) and sediment resuspension in the profundal zone in winter, when wind and turbulence are increased, accounted for only about 20% of the sedimentation rates. Because 70–80% of the total sedimentation for the year occurred during summer, such processes are of minor importance in Lake Hallwil, although a “nepheloid” layer with increased POC and PP concentrations 5–8 m above the bottom was present. It is stressed that the mechanisms of sediment transport must be known to permit interpretation of trap results and to understand lake metabolism.