New Zealand Journal of Marine and Freshwater Research abstracts

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Nitrogen and phosphorus in the sediments of Lake Rotorua

G.R. Fish

Fisheries Research Division, Ministry of Agriculture and Fisheries, P.O. Box 951, Rotorua, New Zealand

and

LA. Andrew

Forest Research Institute, Private Bag, Rotorua, New Zealand

Abstract Kjeldahl nitrogen and total phosphorus concentrations were measured at approximately 1 cm depth intervals in 10 short sediment cores from Lake Rotorua. The concentrations, high at the surface and falling to a more constant value at about 20 cm below, did not vary significantly with the season of retrieval or with the siting of the core in the lake. Samples of sediments from Lake Rotoiti, and from below the layer of Rotomahana Mud (erupted from Mount Tarawera in 1886) in Lake Rotorua, had consistently lower concentrations, possibly characterising less eutrophic lake sources. Only an insignificant proportion of the nitrogen and phosphorus present in the sediments seems to be lost to the overlying lake water when it is oxygen-depleted during summer stratification.

Keywords Lake Rotorua; sediments; nitrogen; phosphorus; eutrophication; freshwater lakes.

New Zealand Journal of Marine & Freshwater Research, 1980, 14(2): 121-128
Received 21 November 1979; revision received 19 February 1980 Fisheries Research Division Publication 402

PDF file of entire paper: medium quality (643K); (scanned from paper original: notes about this process)

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