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The average yearly net ablation rate on permanently ice-covered Lake Fryxell, Victoria Land, Antarctica, is 30 to 40 cm. This figure was calculated by a novel method utilizing a record of ablation which is incorporated in the ice cover of the lake. These values are higher than those measured on Ross Island 80 km. to the east; the difference in ablation rates for the two areas is attributed to the prevalence of katabatic winds in the climate of Taylor Valley. The Lake Fryxell ablation figure is applied to nearby Canada and Commonwealth Glaciers in the calculation of their ice budgets.

Measurements of temperature show that convecting layers in Lake Vanda change their number, thickness, and depth with time and that most of the layers below a depth of 12 meters can be traced for at least 4 km horizontally. The source of the thermal energy of the water and the origin of the layers are discussed briefly. Ii•ITRODUCTIONLake Vanda is permanently covered by ice, which has been about 3.6 meters thick in the

Introduction. Lake Fryxell (77°37′S, 163° 6′E) occupies the lowest part of an enclosed drainage basin near the seaward (eastern) end of the Taylor Valley, Victoria Land. The lake, 5 km by 1½ km, is permanently covered by about 4.5 meters of ice. Angino et al. [1962] first investigated the lake and showed that it contained chemically and thermally stratified water.

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 m -3 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