Measurement of the reducing ability of natural waters and sediments: a simple limnological method

Oláh, János (1970) Measurement of the reducing ability of natural waters and sediments: a simple limnological method. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 37. pp. 209-222. ISSN 0365-3005

Preview

Text 211_cut_MTA_TihanyiBiologiaiKutIntEvkonyve_37.pdf Download (6MB) | Preview

Abstract

In order to measure the potential reducing ability of natural waters and sediments we employed a simple, direct method, which is based on the changes in redox potential of closed systems containing natural substrate. The measuring vessel is a 250 ml graduated glass container fitted with a ground glass stopper or made of rubber into which reference and measuring electrodes are built. By discontinuing the atmospheric oxygen supply, and by excluding photosynthesis because of incubation in darkness, the redox potential decreases in the measuring vessel containing natural substrate. Information received during measurement: 1. time requirement for redox potential decrease; 2. length of decrease; 3. redox potential value characterizing the state of equilibrium. Some typical experiments exemplifying the applicability of the method brought the following results: 1. The supertrophic water of the Inner Lake of Tihany displays a greater reducing ability than that of Lake Balaton, and further, this reducing ability shows significant changes as regards seasons. 2. In the reedery of Lake Balaton the reducing ability of the water in the lotic zone is smaller than in the lenitic zone, and in both cases the reducing ability is higher than that of the open water. 3. The reducing ability of the water deriving from Lake Balaton does not change vertically, at the same time, in the Inner Lake of Tihany the reducing ability towards the bottom increases. The growth showed a direct relation to the quantitative distribution of the total and saprophytic microbial plankton. 4. The influence of bacterio-, phyto- and zooplankton on the reducing ability of the water of Lake Balaton and the Inner Lake of Tihany is different. 5. The sediment in the reedery of Lake Balaton with regard to reducing ability shows a stratification. The highest reducing ability is displayed by the upper, active layer, which contains the highest percentage of bacteria. 6. The reducing ability of the young detritus is smaller than that of the mature detritus. 7. The reducing ability of the sediment in section M in Lake Balaton is greater than in section A. 8. By measuring reducing ability we may also obtain data as to the intensity of mineralizational processes. 9. If the sample gaining the equilibrial state characteristic for oxygenfree condition, is placed in light, its redox potential attains a value of the corresponding initial state.

Actions (login required)

Edit Item