Effects of Aeration and Temperature on Nutrient Regeneration from Selected Aquatic Macrophytes1
- R. A. Ogwada,
- K. R. Reddy and
- D. A. Graetz2
A batch incubation study was conducted to investigate the effect of aeration and temperature on the N and P release by decomposing aquatic macrophytes in eutrophic lake water. Nutrient release by waterhyacinth (Eichhornia crassipes [Mart] Solms), pennywort (Hydrocotyle umbellata L.), hydrilla (Hydrilla verticillata L.), and cattails (Typha latifolia L.) was evaluated under aerobic conditions. Waterhyacinth plants tagged with 15N were used to determine the 15N release at varying temperature levels and under anaerobic (oxygen free) and low-dissolved O2 (open system where the only O2 source was diffusion through the overlying water) conditions.
Nutrient release was found to be rapid initially due to solubilization, followed by slow nutrient release as a result of microbial decomposition. Under aerobic conditions, NO3− formation in the water was found to be significantly related to C/N ratio of the plants. About 48 to 76% of the plant N and 67 to 90% of the plant P were released at the end of 105 d of aerobic decomposition. After 94 d, about 86 and 88% of 15N was released from the plant tissue under anaerobic and low-dissolved O2 conditions, respectively. Nitrogen and phosphorus release were significantly increased with increase in incubation temperature.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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