Role of salinity in the dissolution rates of CaCO3 and its implications for aquaculture liming |
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| Authors: | Marcelo Vinícius do Carmo e Sá Claude E Boyd |
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| Institution: | 1. Fisheries Engineering Department, Agrarian Sciences Center, Federal University of Ceará, Campus do Pici, Fortaleza, Ceará, Brazil;2. School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, USA |
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| Abstract: | This work aimed at assessing the role of salinity in the dissolution rates of CaCO3, discussing its implications for aquaculture liming. A simplified formula of artificial seawater without HCO3? was initially prepared. Four batches of 10 L of diluted artificial seawater (salinity = 3.3 g/L) without HCO3? were prepared. Sixteen Erlenmeyer flasks were filled up with 2 L each of the diluted artificial seawater without HCO3?. Besides, 16 other 2,000‐ml Erlenmeyer flasks were filled up with 2 L of distilled water (freshwater). The experimental treatments were formed by applying increasing amounts of analytical‐grade sodium bicarbonate (NaHCO3) upon brackish water and freshwater. Accordingly, four initial levels of total alkalinity (TA) have been set up as follows: 4–6, 33–35, 62–63 and 120–122 mg/L. Next, approximately one gram of analytical‐grade calcium carbonate (CaCO3) was applied onto each flask. Water's pH, TA and calcium concentration were determined weekly over a 7‐week period, by appropriate methods. For a same initial TA, TA increase over time after CaCO3 application was lower in the brackish water flasks than in the freshwater ones. This was especially clear for moderate (63 mg/L) and high (120 mg/L) alkalinities. It was concluded that brackish and saline waters used for aquaculture would only benefit from CaCO3 liming if their alkalinities were lower than 60–80 mg/L. |
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| Keywords: | aquaculture liming salinity water quality |
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