Collaborative Research: Autonomous alkalinity sensors: design improvements and in situ testing

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The PI request funding to undertake design improvements and complete the evaluation of an autonomous sensor for measurement of seawater total alkalinity (SAMI-alk). Total alkalinity (AT) is one of the four measureable dissolved inorganic carbon parameters and is therefore of paramount importance in the study of carbon cycling in the oceans. AT is commonly measured as part of shipboard hydrographic surveys and ocean time-series and has more recently become a critical parameter for ocean acidification studies. An autonomous AT sensor can be used in combination with other CO2 parameter sensors that are commercially available, i.e. pH and pCO2, to remotely quantify the inorganic carbon system. For example, if pH and AT are accurately measured, total dissolved inorganic carbon (DIC), carbonate, and CaCO3 saturation state can be calculated. Long-term mooring based quantification of these parameters is not yet possible. Through a previous NSF grant, we demonstrated that a novel titration methodology named Tracer Monitored Titration (TMT) could simplify AT analysis by eliminating the need for volumetric or gravimetric measurements required for conventional AT titrations. The SAMI-alk was tested both in the lab and during a cruise. The performance on the cruise was not as good as the laboratory tests. This proposal requests funds to complete the SAMI-alk development and evaluation.Broader Impacts: The ability to measure alkalinity is a key need for acidification research. If successful, the instrumentation development proposed here will provide an important tool for understanding the vulnerability and response of marine ecosystems to acidification. The PI has actively pursued commercialization of the autonomous instruments that he has developed in the past. Commercialization of the proposed alkalinity sensor through will greatly broaden the impacts of the technology, making it broadly available to the ocean sciences community. The project includes funding for on undergraduate student.