Nitrogen Transformations in a Waterhyacinth-based Water Treatment System
- K. K. Moorhead,
- K. R. Reddy * and
- D. A. Graetz
Fate of added 15NH4-N and 15NO3-N in waterhyacinth [Eichhornia crassipes (Mart.) Solms]-based water treatment system was evaluated under controlled conditions. Labeled 15NH4-N uptake by waterhyacinth exceeded 15NO3-N uptake. Total 15N recovery by waterhyacinth ranged from 57 to 72% for added 15NO3-N and 70 to 89% for added 15NH4-N. Both sediment and detritus were potential sources of N for waterhyacinths. Waterhyacinths cultured in sewage effluent removed 55% of the added 15NH4-N and 14% of the added 15NO3-N, respectively. Three to 44% of the added 15NH4-N was lost through nitrification in the water column and subsequent denitrification in the underlying sediments, whereas 24 to 86% of the added 15NO3-N was lost through denitrification. In a system without plants, 13 to 89% of the added 15NH4-N and 48 to 96% of the added 15NO3-N were lost from the system through a combination of nitrification/denitrification and NH3 volatilization.
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