Protocols for the Performance Verification of In Situ pH Sensors.

Abstract

ACT has initiated a Performance Verification of commercially available in situ pH sensors for four reasons: 1) an increasing awareness of the need to monitor pH to assess ocean acidification and changes in the carbon chemistry speciation in coastal and estuarine ecosystems; 2) development of instrument packages to help in the maintenance and enforcement of water quality standards, 3) pH sensors and sensor packages are already available but vary in performance (see ACT workshop, In-situ measurement of dissolved inorganic carbon speciation in natural waters: pH, pCO2, TA and TCO2 , Honolulu Hawaii, February 2005); 4) verification testing of these instruments is feasible within a reasonable timeframe with existing ACT capabilities and funding. These test protocols delineate how ACT will evaluate the performance characteristics of in situ pH sensors through the collection and analysis of quality-assured environmental data. The goal of ACT’s verification program is to provide industry with an opportunity to have a third-party (ACT) test their instruments in the field and under controlled laboratory settings, and to provide users of this technology with an independent and credible assessment of instrument performance. ACT will also use this opportunity to promote this emerging technology to the scientific and management communities. The instrument performance characteristics examined in the verification reflect the needs of the broader research and management communities. ACT does not certify technologies, nor guarantee that technologies will always operate at the verified standards, especially under conditions other than those used in testing; ACT does not seek to determine regulatory compliance; does not rank technologies, nor directly compare performance between specific instruments; ACT does not label, nor list technologies as “acceptable” or “unacceptable;” and does not seek to determine “best available technology” in any way. ACT will avoid all potential language that implies “winners or losers”. Thus, although the following protocols will be used to test all instruments tested in this program, there will be no direct comparisons of instruments. After the tests are complete, Instrument Performance Verification Statements for each instrument will be released to the public.