Oxygen deficit determinations for a major river in eastern Hong Kong, China

Determination of oxygen deficit in the Hong Kong Shing-Mun River was based on the oxygen uptake by water, algal respiration and river sediment and the oxygen supplied to the river by surface reaeration and algal photosynthesi s. A systematic study was conducted to examine the effect of water temperat ure, flow velocity and water depth on both the oxygen demands and the oxyge n supplies. The oxygen budget of a water column in a selected section of th e river was modeled. The results of the oxygen budget analysis showed that when water temperature was around 10 degrees C (the lowest temperature in t he river), no deficit was observed. When water temperature was 10 degrees C to 20 degrees C, a small oxygen deficit appeared, especially in the deeper water. At the highest water temperature (30 degrees C), the oxygen deficit was maximal, -6.84 g O-2/m(2)/day, in the night-time during the Spring tid e period. (C) 2000 Elsevier Science Ltd. All rights reserved.