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

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1 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

2 Continuous Biogeochemical Monitoring Salinity (LOBO) Nitrate ( M, LOBO) Sampling Interval: 25 1 weeks days Sampling Interval: 1 hr 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

3 Murderkill Estuary Bowers, DE Frederica Bowers (LOBO) Delaware Bay Coursey Pond KCRWTF Killens Pond Hourly measurements of Salinity, Temperature, Depth, Nitrate (NO 3- ), Phosphate (PO 4 3- ), Chlorophyll, Colored Dissolved Organic Matter (CDOM), Dissolved O 2, Turbidity. Co-located with USGS Gauging Station March 2017 Ins and Outs of Protons 3

4 Murderkill Estuary/Delaware Bay Tidally-Coupled Biogeochemical Reactor NOAA MODIS 13 April March 2017 Ins and Outs of Protons 4

5 The Challenges of ph and Protons Measurement in Seawater Definition ph is not a concentration: ph = -log 10 {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 CO 2 parameters (pco 2, DIC, ph nbs, Alkalinity) and [H + T] based equilibrium constants 13 March 2017 Ins and Outs of Protons 5

6 SeapHox: Continuous, stable, high frequency ph sensor for estuarine and marine applications: Solid state, ion-selective, fieldeffect 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

7 Operating Principal of the SeapHox ph sensor Drain Silicon Source H + -Sensitive Ion Specific Field Effect Transistor (ISFET) Reference Electrode H + Responsive Surface H + H + H + H + H + H + H + H + Measured Sample 13 March 2017 Ins and Outs of Protons 7

8 Ocean Acidification Processes 1. Fossil fuel burning produces CO 2 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 primary production of excess organic matter (eutrophication) 3. Aerobic respiration of excess organic matter produces carbonic acid (CH 2 O +O 2 H 2 CO 3 H + + HCO 3- ) 13 March 2017 Ins and Outs of Protons 8

9 Salinity Discharge (m 3 /s) Salt Flux (Kg/s) Downstream Upstream USGS Tidal Salt Balance Calculations July 25 Aug 1 Aug 8 Aug 16 Aug 22

10 Downstream Discharge (m 3 /s) NO 3 - (µm) NO 3 - Flux (mmol/s) Upstream Upstream Downstream Tidal NO 3 - Balance Calculations July 25 Aug 1 Aug 8 Aug 16 Aug 22

11 [H + T] (µm) Discharge (m 3 /s) [H + T] Flux (mmol/s) Upstream Upstream Downstream Downstream Tidal [H + T] Balance July 25 Aug 1 Aug 8 Aug 16 Aug March

12 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

13 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

14 Search: Kent County LOBO 13 March 2017 Ins and Outs of Protons 14

15 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, Coinvestigator) 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

16 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 13 March 2017 Ins and Outs of Protons 16

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19 Distinguishing Between Sources Salinity (S) CDOM Flux Proton Flux 13 March 2017 Ins and Outs of Protons 19