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ผู้เขียน หัวข้อ: On the use of micro-electrodes in fish pond sediments  (อ่าน 46 ครั้ง)
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« เมื่อ: ธันวาคม 02, 2019, 11:27:40 AM »

Leon E. Meijer, Yoram Avnimelech *
Faculty of Agricultural Engineering, Technion-Israel Institute of Technology, 32000 Haifa, Israel
Received 2 March 1999; accepted 17 July 1999

Abstract

The surface layer of fish pond sediments is characterized by very high microbial activity. Oxygen uptake by the microbes at the sediment surface leaves little oxygen to penetrate the sediment. In marine and freshwater lake sediments, oxygen only penetrated a few millimeters. In this study, oxygen penetration into the sediment layer in fish ponds and simulated
fish ponds was measured with an oxygen micro-electrode. Oxygen profiles determined with micro-electrodes showed that oxygen does not penetrate deeper than 1 mm under quiescent conditions in intensive and semi-intensive fish pond sediments. Sediment oxygen consumption (SOD) at approximately 25?C, calculated from measured oxygen profiles, ranged from
45 to 50 mg O2:m2 per h. Change in water temperature and the addition of formaldehyde showed that most of the oxygen consumption in the sediment surface layer is related to biological activity. Redox potential profiles of fish pond sediments measured with a microplatinum electrode, showed reducing conditions conducive to sulfide formation at 2?4 mm
below the sediment surface. Nitrate addition to the overlying water poised redox potential above 300 mV to a sediment depth of about 15 mm. Nitrate thus buffered the sediment?water interface against reducing conditions in the sediment and the possible diffusion of toxic reduced end products to the water. ? 1999 Elsevier Science B.V. All rights reserved.

Keywords: Fish pond sediment; Micro-electrodes; Oxygen; Redox; Nitrate
www.elsevier.nl:locate:aqua-online
* Corresponding author. Tel.: 972-4-829-2480; fax: 972-4-822-1529.
E-mail address: agyoram@tx.technion.ac.il (Y. Avnimelech)
0144-8609:
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