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STABLE ISOTOPE VARIATIONS IN SUSPENDED PARTICLES IN A TEMPERATE NORTH PACIFIC ESTUARY, OREGON, USA
Citation:
Sigleo, A C. STABLE ISOTOPE VARIATIONS IN SUSPENDED PARTICLES IN A TEMPERATE NORTH PACIFIC ESTUARY, OREGON, USA. Presented at 2001 Estuarine Research Federation meeting, St. Petersburg Beach, FL, November 4-8, 2001.
Description:
Spatial distributions of 13C and 15N in suspended particles were examined monthly over an annual cycle in the euphotic zone (0.5m) of the Yaquina River and Estuary, Oregon. Suspended organic matter in estuaries is a mixture of land-derived and oceanic carbon and nitrogen. In addition, in situ biological processes both produce and consume organic components. Because the stable isotopes of carbon and nitrogen often reflect the isotopic composition their sources, these isotopes provide a means of identifying the sources. In the Yaquina estuary both 13C and 15N in suspended particles increased from the freshwater terrestrial region of the river downstream to the Pacific Ocean. Isotopic carbon increased from -27.7 ? 1.4 to -22.1 ? 1.5 per mil 13C between the freshwater terrestrial region of the river to the Pacific Ocean. Particulate nitrogen increased from 2.6 ? 1.0 per mil in the freshwater region to 7.2 ? 1.4 per mil 15N at the ocean. These increases were non-linear, indicating that processes in addition to simple mixing of the two end members were occurring. Isotopic data suggest that river outflow may be relatively more important as a source of nutrients in the freshwater portion of the estuary, whereas remineralization and nutrient recycling are suggested in the intertidal regions of the estuary.