| We documented metalimnetic intrusions twice in Toolik Lake in 1999.
The first was identified by low conductivity waterat 8 m depth. We believed
it formed by the mechanism indicated below. Stream water entered
the lake near the time of ice off, mixed in the two shallow basins near
the inlet to the lake and then flowed out into the main lake and into other
basins along lines of constant density. The chlorophyll maximum occurred
at the depths of the low conductivity water, and we believe that this inflow
led to its formation. See Chlorophyll Maximum.
The second instrusion also formed after a rainstorm. Due to the
warmer stream temperatures, this inflow occurred between 2 and 6 m depth.
We documented its location with transects of conductivity and by tracing
Rhodamine WT which we introduced into the stream waters during high flow.
This second intrusion also advected waters with high concentrations of
chlorophyll into other portions of the basin.
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