Benthic nutrient fluxes in a eutrophic,polymictic lake |
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Authors: | D F Burger D P Hamilton C A Pilditch M M Gibbs |
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Institution: | (1) Centre for Ecology and Biodiversity Research, University of Waikato, Private Bag 3105, Hamilton, New Zealand;(2) National Institute for Water and Atmospheric Research, Private Bag 11115, Hamilton, New Zealand |
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Abstract: | Sediment release rates of soluble reactive phosphorus (SRP) and ammonium (NH4) were determined seasonally at three sites (water depth 7, 14 and 20 m) in Lake Rotorua using in situ benthic chamber incubations.
Rates of release of SRP ranged from 2.2 to 85.6 mg P m−2 d−1 and were largely independent of dissolved oxygen (DO) concentration. Two phases of NH4 release were observed in the chamber incubations; high initial rates of up to 2,200 mg N m−2 d−1 in the first 12 h of deployment followed by lower rates of up to 270 mg N m−2 d−1 in the remaining 36 h of deployment. Releases of SRP and NH4 were highest in summer and at the deepest of the three sites. High organic matter supply rates to the sediments may be important
for sustaining high rates of sediment nutrient release. A nutrient budget of Lake Rotorua indicates that internal nutrient
sources derived from benthic fluxes are more important than external nutrient sources to the lake. |
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Keywords: | Nitrogen Phosphorus Sediment Benthic chambers Internal load External load Lake Rotorua |
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