The Distribution and Decomposition of Organic Phosphorus and Organic Nitrogen in River Ecosystems of Korea

Abstract

The spatial and temporal distributions of phosphorus and nitrogen and a number of physical, chemical and biological parameters were analyzed to in the Youngsan and the Sumjin River systems, Korea. Substantial amount of P and N was observed in both the rivers all the year round. Mean N:P ratios showed large variations among the sampling sites; highest ratio was observed in most sampling sites during summer. Relative proportions of DOP: TP were fairly constant (0.08-0.09) in both the rivers. In the composition of nitrogen almost all sampling sites of both the rivers were dominated with NO;-N followed by NH3- N and NO>-N. Variations in dissolved nutrients tended to co-vary with particulate forms (PON and POP), implying that dissolved nutrients are primarily released from the decomposition of particulate forms or dissolved forms are in equilibrium with particulate forms. Chlorophyll a levels in the Sumjin River appear to be negatively correlated with the ammonia, implying ammonia is absorbed by algae with preference. While chlorophyll a was positively correlated with TP and DIP in the Sumjin River, negative correlations of these parameters was observed in the Youngsan River. The pattern in concentration of nutrients was found to be related with land use and domestic sewage in the study area. Inter-parameter relationships may be strongly influenced by geographical factors relative to temporal factors.