Investigating the State of Acidification in the Southern California Bight

Transcription

1 Investigating the State of Acidification in the Southern California Bight Karen McLaughlin SCCWRP Symposium February 26, 2015

2 What is Ocean Acidification? Ocean Acidification is the other CO 2 problem : Ocean ph decreases when CO 2 dissolves in seawater Atmospheric CO2 data from Mauna Loa Observatory, Hawaii ph data from the Hawaii Ocean Time Series Station (HOTS) Feely et al. (2009)

3 ph monitoring is a regulatory requirement California Ocean Plan: ph shall not be changed at any time more than 0.2 units from that which occurs naturally

4 Problem: ph is REALLY hard to measure well Glass Electrodes have been the only available technology for profiling ph in seawater Stated accuracy is ±0.2 ph units Actual performance is really much less Difference between glass electrodes and reference ph

5 Partnerships to Improve Monitoring 1. Improve ph monitoring with existing technology Bight 13 Nutrients Program, Acidification Component 2. Evaluate the next generation of monitoring technology DuraFET XPRIZE

6 Bight 13 Acidification Study Elements 1. Pilot new protocols to improve ph monitoring Discrete spectrophotometric ph samples for in situ calibration and drift correction 2. Get a synoptic picture of aragonite saturation state in the SCB Measuring discrete total alkalinity and ph allows for calculation of aragonite saturation state Assess seasonal and interannual patterns

7 Bight 13 Acidification Sampling Plan Sampling started May 2014 and will continue quarterly through 2016 Collect discrete samples at 20% of CTD stations for in situ calibration of ph sensors. Two Depths Three Depths

8 Improve Member Agency Monitoring Assess Correctability of Glass Electrode Data Directionally offset could be corrected with best practices How many discrete samples ultimately needed depends on sensor performance Linear Data: Potentially Correctable CTD ph CTD ph Random Error: No Correction Possible Discrete ph Discrete ph Discrete ph Discrete ph Good Data: No Correction Necessary CTD ph CTD ph

9 Preliminary Findings An in situ calibration looks promising Offset between discrete and CTD ph consistent with calibration in NIST standards Average difference: ± This may be good for assessing status and possibly trends in ph, but probably not much use for regulatory purposes Offset of glass electrodes from discrete bottle sample ph

10 Evaluate New Monitoring Technology Durafet ph Sensor comparison Six groups with range of experience deployed Durafet sensors in coastal time series mode Collected discrete ph samples for comparison at regular intervals

11 Intercomparison of Durafet sensors Findings: DuraFET sensors have greater accuracy and stability and less uncertainty than glass electrodes All Sites Most Experienced Sites With experience and best practices uncertainty of less than 0.02 ph units is achievable. Count Count Limitations: Can not be used in profiling applications Can not be deployed at depths >80m ph (mcp - ISFET) 10 5

12 Evaluate New Monitoring Technology XPRIZE for developing innovative technologies for monitoring ph $2M award to stimulate development of new ph sensors Aim is improved accuracy and precision and versatility of deployment environment Overall award expected early this year

13 XPRIZE Regulatory Monitoring Post-Prize Use Bight 13 Acidification Program to evaluate cutting edge technologies for coastal ph XPRIZE will select 4 instruments for testing based on performance during principle competition POTWs will deploy the instruments during regulatory monitoring XPRIZE tech will be evaluated against SeaBird CTD and Bight 13 acidification discrete reference ph POTWs will provide feedback on the technologies (ease of use, accuracy, etc.) to determine the winning sensor

14 Summary Existing monitoring programs are insufficient to identify spatial and temporal changes in ph ph data quality could be improved with best practices and/or new technologies SCCWRP is on the frontlines of improving ph monitoring practices to ensure compliance with California Ocean Plan Objectives

15 Questions? Karen McLaughlin