The influence of salinity on the characteristics of individual bubbles (2–4 mm in diameter) in fresh and saline water (up to 40 practical salinity units) was investigated. Bubbles were produced by forcing air through capillary tubes. Aqueous solutions in distilled and filtered tap waters with minimized presence of organic additives were used. Salinity, surface tension, and water temperature were monitored. Parameters measured were the bubble surface lifetime, diameter, and rise velocity. The surface lifetime varies widely (in the range of 0.4–35 s) depending on the salinity concentration and the purity of the solutions. Variations with salinity of size and rise velocity of large individual bubbles are discussed. Interpretation of the results in terms of anti-foaming (negative adsorption), as well as the Marangoni and the Gibbs effects, is helpful in understanding the results.
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