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High Resolution In Situ Study of Nutrient Loading and Estuarine Response in the Columbia River. Melissa Gilbert Needoba, J. A. Koch, C. Barnard, A. Baptista, A. Observation ● Prediction ● Analysis ● Collaboration. Acknowledgements: Needoba/Peterson Lab CMOP Staff
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High Resolution In Situ Study of Nutrient Loading and Estuarine Response in the Columbia River Melissa Gilbert Needoba, J. A. Koch, C. Barnard, A. Baptista, A. Observation ● Prediction ● Analysis ● Collaboration Acknowledgements: Needoba/Peterson Lab CMOP Staff CMOP Astoria Field Team www.stccmop.org
Columbia River SATURN-05 Washington RM-17 Upper Estuary River Oregon SATURN-03 Pacific Ocean Lower Estuary
The Study (Summer 2010) - Hypothesis River Estuary Denitrification Decrease in nitrate Remineralization Increase in ammonium Increase in phosphate
Seasonal Variability in the Columbia River SUNA Nitrate Sensor at SATURN-05 The Columbia River supplies excess nitrate to the estuary all year 24.8
N/P Ratios in the estuary NO3-N PO4-P
Calculating End Member Concentrations SATURN-03 Intercept = River end member nitrate concentration Salinity 32.4 = ocean end member nitrate concentration
Calculating End Member Concentrations SATURN-03 Intercept = River end member nitrate concentration Salinity 32.4 = ocean end member nitrate concentration
Calculating End Member N/P Ratios N/P Ratio of River End Member = 6.4
The Study (Summer 2010) - Hypothesis River Estuary Denitrification Decrease in nitrate Remineralization Increase in ammonium Increase in phosphate
Denitrification ? Average nitrate loss of 1.3 μM
Remineralization ? Gain of 0.4 μM Phosphate
Remineralization ? 6.4-
The Study - Results River Estuary Denitrification Decrease in nitrate Remineralization Increase in ammonium Increase in phosphate
RM-17 • Phosphate: Lower at • RM- 17 than at • SATURN-03 • PO4 @ BAT = 0.14 Remineralization or particle attachment? • Higher river • NH4 at RM-17 • than at BAT but not as • high as SATURN-03 • NH4 @ BAT = 0.34 μM
The Study - Results River Estuary Denitrification Decrease in nitrate Remineralization Increase in ammonium Increase in phosphate
Conclusions High resolution in situ nutrient data yields evidence for an overwhelming remineralization signal in the Columbia River during the summer • Lower NO3-N/PO4-P ratios in the estuary than the river • Transport through fresh water marshes decrease nitrate by 25%, increase phosphate 3X and increase ammonium 50X. • During summer months MORE reactive N may be leaving the Columbia River and estuary in the form of ammonium than in nitrate • The Columbia River and estuary may not remove large quantities of anthropogenic nitrate via denitrification during the summer months
Acknowledgments and Funding Sources OHSU/CMOP Advisor: Joseph Needoba CMOP Director: Antonio Baptista Needoba Lab Florian Moeller Michelle Maier Ezra-Mel Pasikatan CMOP Staff: Charles Seaton Paul Turner Sarah Riseman Grant Law CMOP Astoria Field Team: Michael Wilkin Katie Rathmall Greta Klungness WetLabs: Corey Koch Andrew Barnard SubChem Systems Inc.