Dissolved Oxygen Supersaturation Research Articles

Gas supersaturation in surface waters of aquaculture ponds

During the 1988 and 1989 growing seasons, dissolved gas pressures were measured in 0·04 ha to 0·06 ha earthen ponds (n = 17) used to produce channel catfish or bluegill sunfish, both with and without supplemental aeration. Surface waters in early morning hours (0630 to 0830 h) were typically saturated with nitrogen (N 2) and argon (Ar), undersaturated with dissolved oxygen (DO), and supersaturated with carbon dioxide. Total gas pressures (ΔP) were low, averaging −40 mmHg (range −127 to 62 mmHg). During afternoon hours (1300 to 1500 h) ΔP increased to a mean of 111 mmHg (range −46 to 334 mmHg); 34% of afternoon ΔP values were above that known to cause mortality in channel catfish during continuous exposure bioassays (115 mmHg), yet no excessive mortality was observed. High afternoon ΔP values resulted from DO supersaturation caused by phytoplankton photosynthesis and, to a lesser extent, N 2 and Ar supersaturation. The N 2 and Ar supersaturation apparently resulted from cooling and saturation of surface waters with air during evening hours, and the subsequent increase in water temperature during daylight hours (daily increase X = 3·4°C; range 1·1 to 7·9°C) without sufficient gas release.

On the dissolved surface oxygen supersaturation in the Arctic

Recently we reported anomalous dissolved neon‐helium ratios in the Arctic Ocean and suggested that the neon supersaturation is caused by the freezing process. We also predicted supersaturation of dissolved gases such as oxygen, which are heavier than neon. To pursue the tracer potential of these gases, we recently collected more seawater samples for the measurements of the noble gases, made dissolved oxygen measurements, and performed a set of laboratory freezing experiments. Here, we report the results of dissolved oxygen measurements made during the laboratory freezing experiments, and during the MIZEX 84 field program. In the laboratory we found that 1cm of ice growth caused approximately 0.5% dissolved oxygen supersaturation in a 90cm deep water column. Conversely, the ice phase was 53±2% undersaturated in dissolved oxygen, a result which is, within experimental uncertainties, identical to that obtained in the field.