Nutrient behavior, primary production,a nd infauna in a river system with inputs from fishpond effluents /
by Della Grace Bacaltos.
- Diliman, Quezon City, Cavite State University- Main Campus 2000.
- xiii, 151 p. : illustrations ; 28 cm.
Thesis (Phd--Marine Science) University of the Philippines
This dissertation has assessed the environmental conditions in Sta. Rita River, a river estuary used as a discharge and irrigation area for approximately 316 has of fishponds. The study has estimated nutrient concentrations and fluxes both in the water column and in the sediments, related nutrient levels to seasonal variation (wet and dry), measured primary productivity and assessed the composition and spatial distribution of infauna. These objectives have been attained to elucidate scientific knowledge on nutrient behavior and primary production in a river system affected by fishpond effluents, which may be used to provide insights for management.
On the average, nitrate and ammonia concentrations increased to 3.1 wM and 14 uM during the wet season (September 1997) from 0.4 #M and 7.4 uM during the dry season (February 1997), while phosphate decreased from 5.4 uM to 1.3 uM. The increase in nitrate concentration indicates freshwater input while the decrease in phosphate values imply less of freshwater influence but more from ponds and domestic wastes. Nutrient trends and fluxes indicate that tidal oscillation and advection are important processes in the river. Porewater concentrations of ammonia reached an average level of 3,018 wM in
September 1997 from a level of 2,000 wM in June 1993. Computations done using benthic flux estimate and nutrient concentration in the water column showed that it may take a minimum of 15 days for phosphate, 13 days for nitrite, and 0.3 day for ammonia to replace the standing stock of these nutrients in the water column using the highest benthic flux estimates. This indicates that nutrients regenerated in the sediments could be important in the inventory of nutrients in the water column. The higher average gross
Nutrient--Pollution of water--Philippines--Anda (Pangasinan) Sewage disposal--Environmental aspects--Philippines