| Autor: |
Verdouw, H., Boers, P. C. M., Dekkers, E. M. J. |
| Zdroj: |
Archiv für Hydrobiologie; March 1989, Vol. 105 Issue: 1 p79-92, 14p |
| Abstrakt: |
In Lake Vechten (The Netherlands) the dynamics of sedimentary and hypolimnetic ammonia within the nitrogen cycle was investigated during stratification. About 90 percent of the ammonia in the sediment was adsorbed on sediment particles. The relation with ammonia dissolved in the pore water was described by a linear adsorption isotherm with K = 23.7 ± 5.8. Ammonia turnover, measured with a 15N isotope dilution technique, occurred predominantly in the upper 1 cm of the sediments. Net production was 1.6 ± 0.2 µg NH3-N (g wet sediment)-1d-1 which rate did not vary during the year. Turnover constants were about 0.07 d-1 Only towards the end of the stratification significant uptake rates were measured. Total net production for the upper 6 cm of the sediments was 3 to 4µ g NH3-N cm-2d-1. Transport to the overlying water was calculated from the concentration gradients in the pore water and a diffusion coefficient of ammonia of 1.3 x 10-5 cm²s-1. This transport practically balanced the net ammonia production. An ammonia budget, including Particulate Organic Nitrogen input by sedimentation and NH3-N efflux by dispersive transport, for the water strata below 7.2 m showed, that 55 percent of the input was recovered as ammonia that virtually completely originated from the sediments. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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