Fluxes of dissolved and nonfossil particulate organic carbon from an Oceania small river (Lanyang Hsi) in Taiwan

Concentrations of dissolved and particulate organic carbon (DOG & POC) in river waters were measured during 1993-1994 in the Lanyang Hsi watershed, which represents a typical small Oceania river. The DOC concentrations varied in the range of 0.5-4 mg/l during non-typhoon period, but rose to as high as 8 mg/l during Typhoon Tim in July, 1994. Based on the log-linear relationship between the DOC load and the discharge rate, we estimated the DOC export to be 3.4 +/- 0.6 ktC/yr, and the DOC yield to be 4.1 +/- 0.7 gC/m(2)/yr, which is considerably higher than a former estimate (ca. 0.1 gC/m(2)/yr) for the Oceania. On the other hand, the DOC yield is less than the concurrent POC yield (21.7 +/- 4.7 gC/m(2)/yr) by a factor of five, but most of the exported POC is fossil carbon. Under the assumption that the suspended sediments contain a mean fossil POC content of 0.5%, the nonfossil POC yield was calculated to be 4.6 +/- 3.0 gC/m(2)/yr, comparable to the DOC yield. Since DOC and nonfossil POC are directly related to the ecosystem, their combined fluxes give a biogenic organic carbon yield of 8.7 +/- 3.1 gC/m(2)/yr.