Nitrogen Fixation in the Sediment of Shallow Lake Balaton, a Reservoir and Fishponds

Abstract

For the in situ measurement of nitrogen fixation in lake sediments, we developed a method which assures the rapid saturation with acetylene of the whole enzyme pool in the sediment and maintains near intact physical, chemical and biological environment a t the water-sediment interface. On the basis of seasonal measurements, the annual nitrogen fixation in the sediment was estimated in four types of shallow water ecosystem: the Keszthely Basin, Lake Balaton: 4.7 g N m-2; Koros backwater reservoir: 6.5 g N m-2; a polycultural fishpond: 0.49 g N m-2; and a liquid manure oxidation fishpond: 0.61 g N m-2. The amount of nitrogen fixed in the sediment of the Keszthely Basin was close to the fixation in the water column, while that fixed in the sediment of Koros backwater reservoir was considerably greater.A multiple regression analysis was made on the basis of synoptic studies on the vertica,l distribution of nitrogen fixation in the sediment, the pH, Eh, and concentrations of organic N, NH,-N, N03-N, and N02-N in the interstitial water. The results indicate that nitrogen fixation is related to the depth, the NH,-N concentration, and the redox potential. The vertical distribution of nitrogen fixation cannot be explained in every case by the densities and distributional patterns of the Azotobacter and Clostridium populations. No correlation was observed between nitrogen fixation and total organic-C in lake sediment. A surprisingly close correlation was found between plankton primary production and the sedimentary nitrogen fixation in these lakes ( r =0.85, y=4.5XO.85). Short-term (4 h) in vitro studies revealed a glucose mediated increase of nitrogen fixation, but there was no NH,-N inhibition detected during this short incubation period.

Effects of common carp (Cyprinus carpio Linnaeus, 1758) supplementary feeding with modified cereals on pond water quality and nutrient budget

“…Numerous studies on pond nutrient budgets have been undertaken, both for freshwater fish ponds under various climatic conditions (Boyd, ; Foy and Rosell, ) and for carp ponds in the temperate zone (Oláh et al., ; Schreckenbach et al., ; Knösche et al., ; Gál et al., ). Ponds have a large N retention capacity due to denitrification and fixation in sediments (Oláh et al., ; Pokorný et al., ). According to Knösche et al.…”

“…N‐balance, however, is also influenced by fixation of N from the air, caused by cyanobacteria and bacterial denitrification. Both processes are likely to have a significant effect in carp ponds as they influence the N‐balance in an opposite way (Oláh et al., ).…”

Changes of phosphorus and nitrogen concentration and of phytoplankton in enriched lake enclosures1

“…Aphanizomenon jlos-aquae fixed about 10 g N mm2 during its late summer bloom (lasting 2 months in the hypertrophic area of the lake), which corresponds to an average daily fixation of 170 mg N m-2 (Olah et al 1983). The estimated rate of N2 fixation was similar in the enclosure +P +N (160 mg m-2 d-l), while in the enclosure +P it was 2.5 times higher.…”