Distribution of Nutrients in Dae-Cheong Reservoir Sediment

This paper was performed to estimate interrelations between humus level of sediments and nutrient release from sediments in Dae-cheong reservoir. For investigations, sediments were sampled in June and October, in 1997 at fish farms, embayment, and the main stream of Dae-cheong reservoir. Items for investigation are as follows; water content, weight loss on ignition(IG), porosities of sediments, contents of element such as hydrogen, nitrogen, carbon, and nutrient release rates. Water contents and porosities were measured to conjecture the physical trait and grain size trait. Weight loss on ignition was measured to determine the contents of organic substance. For determination of the humus level of sediments, carbon and nitrogen contents were measured by elemental analyzer. As a result of elemental analysis, C/N ratio was determined in the range of $3.0\~13.1$. From the elemental analysis, humus level of Dae-cheong reservoir sediment was estimated from mesohumic state to oligotrophic state. For the determination of nutrient release rate, $PO_4-P$ and $NH_4-N$ concentrations of interstitial water and overlying water were measured. By using the concentration difference between interstitial water and overlying water and using the Fick's diffusion law, the release rates of phosphorus and nitrogen from the sediment samples were calculated. Release rates of nutrients which directly influence to the water quality were $0.05\~8.63mgP/m^2day$ and $4.99\~36.56mgP/m^2day$. It was found that release rate was measured higher in the 1st sampling period than in the 2nd sampling period. For the determination of phosphorus content in sediment, TPs were measured in 807\~1542{\mu}g/g$ in the 1st samling period and $677\~5238{\mu}g/g$ in the End samling period. Phosphorus release rate and phosphorus content were not interrelated each other.