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Supersaturated dissolved gas can cause gas bubble disease in fish, potentially increasing their mortality. Previous studies have indicated that total dissolved gas (TDG) has a more serious impact on fish than other dissolved gases, such as dissolved oxygen (DO) or dissolved nitrogen. However, for many reasons, dissolved oxygen (DO) concentrations are generally used as a proxy for determining total dissolved gas (TDG) concentrations. Here, the relationships between TDG and DO concentrations are discussed relative to laboratory experiments and field TDG concentrations downstream of dam projects in China. The relationship between TDG and DO varied with time and space, and no clear or fixed relationship was observed between TDG and DO. Therefore, using DO concentrations to predict TDG supersaturation may result in large errors, and it is thus not appropriate to use DO concentrations as a predictor of TDG concentrations. |
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Keywords:Envrionmetal hydraulics, dissolved gas; total dissolved gas; dissolved oxygen; field observation;Supersaturation |
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