New Zealand Journal of Marine and Freshwater Research abstracts

---

Nitrogen and phosphorus in the Ngongotaha Stream

R. A. HOARE

Ministry of Works and Development
Hamilton Science Centre
Private Bag
Hamilton, New Zealand

Abstract This paper gives the data and methods used to calculate the nitrogen and phosphorus loads of the Ngongotaha Stream, near Rotorua, New Zealand. The variations in concentration with time and with flow rate are given in some detail, as examples of what may happen in other streams of the central volcanic plateau, and a novel way to define a flow-concentration curve is described. Nitrate, ammonia, dissolved reactive phosphorus (DRP), total phosphorus (TP), and total Kjeldahl nitrogen (TKN) concentrations were measured, and mean concentrations in 1976 base flow were found to be 527, 25, 32, 48, and! 162 mg m³ respectively. Nitrate concentrations showed seasonal variations, and although changes occurred during floods, they were not correlated with flow rate. DRP concentrations showed little variation, except that they dropped at the peak of the largest floods. TP was strongly correlated with flow rate during floods, and TP loads could best be calculated by allowing for a curvilinear relationship between concentration and flow rate. The logarithms of the TP load carried by a flood and the peak flow rate of the flood were highly correlated (R = 0.984). The annual loads of nitrate, ammonia, DRP, TP, and TKN were estimated to be 34, 1.3, 2.9, 6.0, and 26 tonnes in 1976.

Keywords phosphorus; nitrogen; nutrients; water quality; Rotorua; flows; correlation analysis; suspended matter; water analysis

New Zealand Journal of Marine and Freshwater Research, 1982, Vol. 16 : 339-349
Received 7 December 1981; accepted 9 July 1982

PDF file of entire paper: medium quality (774K); (scanned from paper original: notes about this process)

---

This year's abstracts | Journal home page | All abstracts | Publishing home page