New Zealand Journal of Marine and Freshwater Research abstracts

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SELF-PURIFICATION OF SMALL FRESHWATER STREAMS: PHOSPHATE, NITRATE, AND AMMONIA REMOVAL

R. H. S. McColl

Freshwater Section, Ecology Division, Department of Scientific and Industrial Research, P.O. Box 415, Taupo, New Zealand

Abstract Uptake of stream nutrients by organisms or sediments of the stream bed is affected by the nutrient loading to which the stream is accustomed. In a stream with nutrient-poor waters, added phosphate and ammonia were removed rapidly and efficiently at water temperatures within the range 4.5 - 15.0°c on passing over a mat of filamentous algae and trapped sediment. Nitrate was removed less efficiently or not at all. In another stream where nutrients were abundant, phosphate and nitrate from a sewage outfall were not significantly removed by the stream bed flora up to 100 m downstream at summer temperatures. Sodium was used as an inert marker to measure the dilution of added nutrients or sewage effluent by the stream waters; electrical conductivity was rejected as a measure because it is influenced by photosynthesis. Studies of nutrient run-off should take account of stream-bed removal when the effects of run-off on eutrophication of lakes are being considered.

N.Z. Journal of Marine and Freshwater Research 8 (2): 375-88.
(Received for publication 9 August 1973)

PDF file of entire paper: medium quality (795K); (scanned from paper original: notes about this process)

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