1. Spatial variability in drainage basin DOC fluxes : Is there a relationship to remotely- sensed measurements? Joe Salisbury (UNH) Jacqui Aitkenhead-Peterson (UNH) Janet Campbell (UNH) L. David Meeker (UNH) Frank Muller-Karger (USF) Charlie Vorosmarty (UNH)

2. 0102030 0 0.5 1 1.5 2 Kennebec: m = -0.017 0102030 0 0.5 1 1.5 2 Penobscot: m = -0.040 Absorption @ 550nm. (m-1) Salinity (psu) Advertised title: Coastal river plumes in the Gulf of Maine: Linking salinity vs. absorption relationships to terrestrial DOC fluxes

3. Outline: 1. Drainage basin plume identification 2. DOC flux model 3. Previous work with NEGOM data 4. Salinity – CDOM relationships in the Gulf of Maine 5. Relationship to drainage basin DOC fluxes

5. Aitkenhead-McDowell DOC flux model - relates soil C:N ratio to DOC flux (kg hectare -1 year -1 ) - Biome-based Results for several rivers entering the northern Gulf of Mexico DOC Index – The Aitkenhead-McDowell modeled flux divided by climatological runoff. Same units as concentration (mg l -1 ) Perhaps similar to average concentration

6. ag443 vs. salinity within individual plumes (NEGOM-3) 11-13-89 to 11-25-98 Right – rescaled for detail

8. Salinity versus CDOM absorption @550nm for 9 Maine Rivers

11. Conclusions: 1.Relationships between ag and salinity appear to be local 2.The slope of this relationship is often related to the DOC endmember concentration and its proxy – the DOC index Why we’re continuing work on this : Hope to develop localized algorithms that would enable the retrieval of surface DOC concentration via remotely sensed data

12. The end This work was supported by NASA's Office of Earth Sciences through a grant entitled "A satellite-based system for monitoring biogeochemical fluxes between the continental land mass and the coastal ocean" (NAG5-12451, C. Vorosmarty, P.I.), and by the NOAA Coastal Services Center through an award to the UNH Center for Coastal Ocean Observation and Analysis (COOA). (NOAA award NA16OC2740).

13. Ancillary slides CDOM : DOC relationships along a salinity gradient Kennebec River and its estuary

14. CDOM absorption versus salinity absorption @440 (1/m) Salinity (psu)

16. Linear model Mean, range and standard deviation for 5 psu bins End member

18. -505101520253035 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 ( ag443:carbon – end member ag443:carbon) versus salinity ag443:carbon - endmember ag443:carbon Salinity (psu)

19. 051015202530 0 1 2 3 4 5 6 7 8 Dissolved organic carbon versus salinity (modeled) DOC (mg/l) Salinity (psu) conservative mixing model 3rd order polynomial (good fit)

20. 051015202530 0 5 10 15 20 25 30 35 Cumulative carbon loss (percent) along the salinity gradient DOC (mg/l) Salinity (psu) Conservative mixing line value = 0%

21. 051015202530 0 10 20 30 40 50 60 70 80 90 Total DOC removal across a salinity gradient percent DOC concentration reduction Salinity (psu)

22. 051015202530 -0.05 0 0.05 0.1 0.15 0.2 0.25 Rate of carbon removal (mg/l C per psu) DOC (mg/l) Salinity (psu)

23. Salinity versus absorption (left) and [DOC] (right) Kennebec Penobscot Union

24. no data 0.3 0.4 0.5 0.6 0.7 024681012141618 0 200 400 600 800 1000 1200 Wind speed m s -1 Remote determination of ROFI – (covariance technique) January - March, 1999

25. no data 0.3 0.4 0.5 0.6 0.7 024681012141618 0 200 400 600 800 1000 1200 Wind speed m s -1 Covariance Technique July-September, 1999

26. 051015202530 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 ag550 versus salinity (best fit lines) for 7 cruises - Kennebec River Salinity (psu) best fit intercept Seasonality?

27. Kennebec discharge versus ag550/salinity intercept Discharge (ft 3 s -1 ) Zero intercept