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Project Progress

Using UHNAI funds in 2004-2005, we began to acquire laboratory equipment and initiate the first environmental electrochemistry research effort at UH, making use of solid-state voltammetric sensors. Voltammetric techniques provide simultaneous, real-time detection of O₂, H₂O₂, HS, S(0), S_x², S₂O₃, S₄O₆, Fe(II), Fe(III), FeS_(aq), Mn(II), and Zn(II). We leveraged the UHNAI funding with a grant awarded to Cowen and Glazer from NOAA Office of Exploration (NOAA-OE-2005-014) aimed at characterizing subseafloor hydrothermal fluids. We acquired and tested an in situ voltammetric analyzer capable of seafloor data-logging. A plumbing manifold was designed and fabricated to attach to standard ODP borehole CORKs (Circulation Obviation Retrofit Kits). We worked with UH engineers to couple the voltammetric analyzer to an in situ filtration unit and we successfully deployed the instrument package from the manned submersible, DSV Alvin, during a cruise to the flanks of Juan de Fuca in September, 2005. The major objectives of the Cowen/Glazer component of the cruise were: (1) to perform the first field tests of our new instrument system, (2) to analyze and filter samples of basement fluids in situ, (3) to test a data logging in situ voltammetric electroanalyzer for use in detecting deep-ocean neutrally-buoyant hydrothermal plumes, and (4) to test an in situ voltammetric analyzer on board Alvin at ancillary seafloor targets of opportunity. The primary target for sampling was IODP borehole 1301B. Unfortunately, 1301B was found to be under-pressured instead of over-pressured, contrary to expectations. Onboard hydrogeologists were confident that this was a result of the borehole observatory not being completely sealed properly at time of installation (2004, IODP). Efforts by several PIs are underway to find a near-term solution to this problem (i.e., have IODP seal boreholes 1301A and 1301B as early as Nov.). Consequently, Objective 2 was not realized during this cruise. However, all of the other objectives were met, all with promising results. Additionally, a proof of concept test was successfully performed of an osmosampler-electrochemical flowcell design that was improvised onboard the ship in collaboration with Hans Jannasch (MBARI). We identified a number of minor design improvements for our instrument package that once made, will improve preparation and deployment of the system. The composite results of the cruise demonstrate that the overall system, as well as its component parts, will be very effective at: (1) interfacing with CORK observatory fluid delivery systems; (2) distributing basement fluids to a variety of sensors and samplers; (3) providing continuous in situ voltammetric analyses of basement fluids; (4) providing simultaneous isolation (filtration) of multiple samples of particles from programmable volumes of fluids and at programmable times/intervals.

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