New Zealand Journal of Marine and Freshwater Research abstracts

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Sediments of Lake Rotorua as sources and sinks for plant nutrients

E. White

Beverley J. Don

M. T. Downes

Linda J. Kemp

A. L. Mackenzie

G. W. Payne

Ecology Division, DSIR, P.O. Box 415, Taupo, New Zealand

Abstract Lake Rotorua, on the Central Volcanic Plateau of the North Island of New Zealand, is a third-class lake of 81km² and 10.7 m average depth. The lake is eutrophic and in recent years has produced blue-green algal blooms of potential nuisance proportions. By a mass balance approach, nutrient exchanges between lake sediments and the water above were quantified. Phosphorus released from temporarily deoxygenated sediments was estimated at 20-40 mg.m-2.d-¹ and nitrogen at 250-530 mg.m-².d-1. Phosphorus sedimentation was less than 1 mg.m-^d-¹ when the sediment surface was oxidised. A massive net loss of nitrogenous material from lakewater to sediments and/or the atmosphere, equivalent to 20 mg.m-².d^Kl, may contribute to the shortage of nitrogen exhibited by the algae of this lake.

N.Z. Journal of Marine and Freshwater Research 12 (2): 121-30.
Received 17 September 1976; revision received 3 March 1978.

PDF file of entire paper: medium quality (705K); (scanned from paper original: notes about this process)

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