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SUSPENDED AND BENTHIC SEDIMENT RELATIONSHIPS IN THE YAQUINA ESTUARY, OREGON: NUTRIENT PROCESSING
Citation:
SIGLEO, A. C. SUSPENDED AND BENTHIC SEDIMENT RELATIONSHIPS IN THE YAQUINA ESTUARY, OREGON: NUTRIENT PROCESSING. Presented at Estuarine Research Federation Biannual Meeting, Providence, RI, November 04 - 08, 2007.
Impact/Purpose:
research presentation
Description:
Measurements of nutrient loading and subsequent nutrient processing are fundamental for determining biogeochemical processes in rivers and estuaries. In Oregon coastal watersheds, nutrient transport is strongly seasonal with up to 94% of the riverine dissolved nitrate and silica being transported during the winter months of greater rainfall and river flow. During the summer months, upwelled oceanic nitrate and phosphorous are tidally entrained into coastal estuaries, supplementing watershed nutrient input. Denitrification studies from the freshwater through the saline parts of the estuary, generally indicated no significant difference in denitrification rate with either season or location within the estuary. To further examine nutrient processing in the Yaquina Estuary, benthic sediments were compared with the overlying suspended sediment for total organic carbon (TOC), total nitrogen (TN), C/N ratios and C and N isotopes. Carbon and nitrogen isotope ratios generally were comparable in both benthic and suspended sediments. TOC and TN were both lower in benthic sediments suggesting mixture with mineral material and utilization by benthic organisms. The C/N ratios, however, were markedly higher in the upper 3cm of sediment. Thus although riverine nutrient loading is strongly seasonal, in this temperate climate, monthly measurements indicated that benthic remineralization processes generally proceed year round.
