Summer sedimentation in six shallow arctic lakes |
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Authors: | Kenneth Fortino Anne E Hershey Matthew D Keyse Steve C Whalen |
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Institution: | (1) University of North Carolina at Greensboro, Greensboro, NC, USA;(2) Present address: University of North Carolina at Chapel Hill, Chapel Hill, NC, USA;(3) Present address: University of Alaska Fairbanks, Fairbanks, AK, USA;(4) University of North Carolina at Chapel Hill, Chapel Hill, NC, USA |
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Abstract: | The movement of sediment between the lake bottom and water column of shallow lakes can be sizeable due to the large potential
for resuspension in these systems. Resuspended sediments have been shown to alter phytoplankton community composition and
elevate water column production and nutrient concentrations. We measured the summer sedimentation rates of two lakes in 2003
and six lakes in 2004. All lakes were shallow and located in the Alaskan Arctic. In 2004, turbidity, light attenuation, total
sediment:chlorophyll a mass in the sediment traps, and thermal stratification were also measured in each of the lakes. The sediment:chlorophyll
a mass was much greater than if the sediment was derived from phytoplankton production in all of the lakes, indicating that
the source of the sedimenting material was resuspension and allochthonous inputs. Consistent with these findings, the temporal
variation in sedimentation rate was synchronous between most lakes, and sedimentation rate was positively related to wind
speed and rainfall suggesting that sedimentation rate was strongly influenced by landscape-scale factors (e.g., wind and rain
events). Two of the lakes are located on deposits of loess that accumulated during past glacial periods. These two lakes had
sedimentation rates that were significantly greater and more variable than any of the other lakes in the study, as well as
high turbidity and light attenuation. Our results indicate that sedimentation in these shallow arctic lakes is supported primarily
by allochthonous inputs and resuspension and that landscape-scale factors (e.g., weather and geology) impact on the transport
of materials between the lake bottom and water column.
Handling editor: J. Saros |
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Keywords: | Resuspension Turbidity Loess Primary production Light extinction Geology Alaska |
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