The Ins and Outs of Estuarine + Acidification: Proton [H T] Fluxes in the Murderkill Estuary (Delaware)

Stephen F. Gonski*, Daniel T. Pettay, Wei Jun Cai, and William J. Ullman.

School of Marine Science and Policy University of Delaware Lewes and Newark, Delaware

(*Present address: Department of Geography, University of Calgary)

13 March 2017 Ins and Outs of Protons 1 Continuous Biogeochemical Monitoring

30

25

20

15

10 Salinity(LOBO) Salinity(LOBO)

5

0 200 SamplingSamplingSampling Interval: Interval: Interval: 25 1weeksdays day 1 hr

150 M,LOBO) M,LOBO)   100 Nitrate( Nitrate( 50

0 10-Oct 17-Oct 24-Oct 31-Oct 07-Nov 14-Nov 21-Nov 28-Nov 05-Dec 12-Dec 19-Dec 26-Dec 02-Jan 09-Jan

13 March 2017 Ins and Outs of Protons 2 Delaware Murderkill Bay Bowers Estuary (LOBO)

Bowers, DE Frederica Coursey KCRWTF Pond

Killens Pond

Hourly measurements of Salinity, Temperature, Depth, - 3- Nitrate (NO3 ), Phosphate (PO4 ), Chlorophyll, Colored Dissolved Organic Matter (CDOM), Dissolved O2, Turbidity. Co-located with USGS Gauging Station 01484085 13 March 2017 Ins and Outs of Protons 3 Murderkill Estuary/Delaware Bay Tidally-Coupled Biogeochemical Reactor

NOAA MODIS 13 April 2016

13 March 2017 Ins and Outs of Protons 4 The Challenges of pH and Protons Measurement in Seawater • Definition • pH is not a concentration: pH = -log10 {H+} • {H+} is also not a concentration • Analysis • Traditional glass-membrane pH electrodes work badly in high ionic strength solution due to poisoning of glass membrane by high levels of alkali ions (Na+ and K+) • Standardization • Dilute NBS/NIST standards are not appropriate for seawater • Tris standards in seawater are now available for + measurements on the marine [H T] concentration scale • Solutions to the above challenges • Use Ion-Selective Field-Effect Transistor (ISFET) technology + • Use Marine [H T] scale in concentration units • Use Marine Tris Buffers for calibration • Verify instrumental performance with measurements of other + CO2 parameters (pCO2, DIC, pHnbs, ) and [H T] based equilibrium constants 13 March 2017 Ins and Outs of Protons 5 SeapHox: Continuous, stable, high frequency pH sensor for estuarine and marine applications: Solid state, ion-selective, field- effect transistor (ISFET) technology developed by Ken Johnson (MBARI) and Todd Marz (SIO). Now available commercially from Hach/Seabird Electronics

Kent County Land- Ocean Biogeochemical Observatory

13 March 2017 Ins and Outs of Protons 6 Operating Principal of the SeapHox pH sensor

H+-Sensitive Ion Specific Field Effect Transistor Silicon (ISFET) Drain Source

H+ Responsive Surface H+ H+ H+ H+ H+ + H+ H Reference Electrode H+ Measured Sample

13 March 2017 Ins and Outs of Protons 7 Processes

1. Fossil fuel burning produces CO2 and other acidic gases 2. Dry and wet deposition of these gases from the atmosphere to the ocean Coastal Acidification Processes 1. Ocean Acidification + … 2. Nutrient export through rivers and groundwater supports of excess organic matter (eutrophication) 3. Aerobic respiration of excess organic matter produces carbonic + - (CH2O +O2  H2CO3  H + HCO3 )

13 March 2017 Ins and Outs of Protons 8 Tidal Salt Balance Calculations Aug22 USGS 01484085 Aug16 Downstream Aug8 Aug1 July 25

Upstream

Salt Flux (Kg/s) Flux Salt /s) Salinity Discharge (m Discharge 3 - - 3 NO3 Flux (mmol/s) NO3 (µM) Discharge (m /s) Upstream Upstream July 25 July Aug 1 Aug Aug 8 Aug Downstream Aug 16 Aug Downstream

Aug 22 Aug

3 Balance Calculations Balance NO Tidal - Downstream /s) 3

Discharge (m Upstream Tidal [H Tidal + T ] Balance T] (µM) + [H /s) Downstream mmol ] Flux ( T + Upstream [H

July 25 Aug 1 Aug 8 Aug 16 Aug 22 13 March 2017 11 Summary of Results

• Salt Balance indicates that there is no net salt flux, consistent with a single marine source of salt (also indicates that measured discharges are accurate and sufficiently precise for nutrient and proton flux calculations). • Proton Balance shows evidence of both terrestrial (Murderkill Watershed and Marshes and perhaps KCRWTF) and marine sources (Delaware Bay), + but net downstream [H T] fluxes. • Variability of Proton Balance is consistent with physical forcing by tides and other processes.

13 March 2017 Ins and Outs of Protons 12 Work in Progress…

• Watershed Sources: Can these be identified, separated, and quantified? • Surface water discharge from the watershed (ponds) • Direct groundwater discharge to the Murderkill Estuary • Wastewater discharge from KCRWTF • Freshwater and saltwater marshes as a source of nutrients and/or protons • Annual cycle of proton fluxes • Do proton fluxes vary seasonally or with weather patterns? If so, what are the mechanisms? • Does the impact of proton fluxes on coastal waters vary with season? If so, why?

13 March 2017 Ins and Outs of Protons 13 Search: “Kent County LOBO”

13 March 2017 Ins and Outs of Protons 14 Research Support for Murderkill Estuary Studies • Kent County Board of Public Works (Andrew Jakubowitch and Hans Medlarz) • Delaware Department of Natural Resources and Environmental Control (John Schneider and Hassan Mirsajadi) • Delaware Sea Grant College Program (Joanna York, Co- investigator) • US Geological Survey, Dover (Betzy Reyes and Tony Tallman) • NSF EPSCOR (Scott Andres (DGS), Co-Investigator) • Yoana G. Voynova (Helmholz-Zentrum, Geestacht) and Christopher R. Main (DNREC), Sarah Jane Fischer, and others …

13 March 2017 Ins and Outs of Protons 15 “Emerging Contaminants of Concern” vs. “Emerging Concerns Related to Known Contaminants”

“Emerging Contaminants” can be broadly defined as any synthetic or naturally occurring chemical that is not commonly monitored in the environment and causes known or suspected adverse ecological and/or human health effects. In some cases, release of emerging chemical or microbial contaminants has likely occurred for a long time, but may not have been recognized until new detection methods were developed. In other cases the synthesis of new chemicals or changes in the use of existing chemicals can create new sources of emerging contaminants. (USGS Toxic Substance Hydrology Program https://toxics.usgs.gov/investigations/cec/index.php)”

13 March 2017 Ins and Outs of Protons 16 13 March 2017 Ins and Outs of Protons 17 13 March 2017 Ins and Outs of Protons 18 Distinguishing Between Sources

Salinity (S)

Proton Flux CDOM Flux

13 March 2017 Ins and Outs of Protons 19