1 High Resolution In Situ Study of Nutrient Loading and Estuarine Response in the Columbia River Observation ● Prediction ● Analysis ● Collaboration Melissa Gilbert Needoba, J. A. Koch, C. Barnard, A. Baptista, A. Acknowledgements: Needoba/Peterson Lab CMOP Staff CMOP Astoria Field Team

2 Columbia River Washington Pacific Ocean Oregon SATURN-03 SATURN-05 River Lower Estuary RM-17 Upper Estuary

3 The Study (Summer 2010) - Hypothesis Denitrification Decrease in nitrate Remineralization Increase in ammonium Increase in phosphate Estuary River

4 The Columbia River supplies excess nitrate to the estuary all year Seasonal Variability in the Columbia River SUNA Nitrate Sensor at SATURN

5 Estuary Data

6 N/P Ratios in the estuary NO 3 -N PO 4 -P

7 N/P Ratios in the Estuary

8 Calculating End Member Concentrations SATURN-03 Salinity 32.4 = ocean end member nitrate concentration Intercept = River end member nitrate concentration

9 Calculating End Member Concentrations SATURN-03 Salinity 32.4 = ocean end member nitrate concentration Intercept = River end member nitrate concentration

10 Calculating End Member N/P Ratios N/P Ratio of River End Member = 6.4

11 The Study (Summer 2010) - Hypothesis Denitrification Decrease in nitrate Remineralization Increase in ammonium Increase in phosphate Estuary River

12 Denitrification ? Average nitrate loss of 1.3 μM

13 Remineralization ? Gain of 0.4 μM Phosphate

14 Remineralization ? 6.4-

15 The Study - Results Denitrification Decrease in nitrate Estuary River Remineralization Increase in ammonium Increase in phosphate

16 RM-17 Phosphate: Lower at RM- 17 than at SATURN-03 PO BAT = 0.14 Higher river NH 4 at RM-17 than at BAT but not as high as SATURN-03 NH BAT = 0.34 μM Remineralization or particle attachment?

17 The Study - Results Denitrification Decrease in nitrate Estuary River Remineralization Increase in ammonium Increase in phosphate

18 Conclusions Lower NO 3 -N/PO 4 -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 High resolution in situ nutrient data yields evidence for an overwhelming remineralization signal in the Columbia River during the summer

19 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.