摘要：The decomposition rates of organic nitrogen and organic phosphorus in lakes and rivers can be important parameters in water quality model calibrations. Commonly, decomposition rate coefficients are calibrated by observing the changes in each component in the field survey. However, in natural field conditions, production and decomposition occur at the same time, and the calibrations may result in uncertainties. In this study, water samples collected from six major rivers in Korea were incubated for 20 days in a dark incubator and the decomposition rates of POP, DOP, LDOP, PON, DON, LPON, LDON, ammonia, and nitrite were determined. By excluding the interference of photosynthesis, animal grazing, and excretion, the decomposition rate coefficients were determined with less uncertainty than in natural conditions. The decomposition data were fit to first-order models of several decomposition pathways, including POP → DIP, POP → DOP → DIP, LPOP → LDOP → DIP, , and . The decomposition rates of dissolved forms were five–seven times higher than particulate forms. And the rates of organic P (0.149 day −1 for LPOP and 0.718 day −1 for LDOP) were 1.6 times higher than those of organic N (0.093 day −1 for LPON and 0.472 day −1 for LDON). Traditionally, the decomposition rates of organic phosphorus and organic nitrogen are not discriminated; the same rate is applied to organic carbon, nitrogen, and phosphorus. The result of this study shows that organic phosphorus and nitrogen should be given different decomposition rates for more accurate models. The rate coefficients measured in this study will provide a guide to the selection of model parameters for water quality modeling.
关键词：decomposition coefficients; decomposition rate; N and P content; POM; DOM
