@article {Syverson2017,
	title = {{Fe isotope fractionation between chalcopyrite and dissolved Fe during hydrothermal recrystallization: An experimental study at 350 {\textdegree}C and 500 bars}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {200},
	year = {2017},
	pages = {87{\textendash}109},
	abstract = {Equilibrium Fe isotope fractionation between chalcopyrite and dissolved Fe was determined in acidic chloride-bearing fluid at 350 {\textdegree}C and 500 bars. The study utilized deformable gold-cell technology, which allowed time-series sampling of solution during chalcopyrite recrystallization and isotope exchange. A key element of the experimental design involved the addition of anomalous dissolved 57Fe to an on-going experiment as a means of determining the degree and rate of isotope exchange. Taking explicit account of imposed chemical and isotopic mass balance constraints of Fe in fluid and mineral (chalcopyrite) reservoirs, these data indicate that no more than 1000 h is required for the isotopically anomalous dissolved Fe reservoir to exchange completely with the coexisting chalcopyrite. The experimental calibration of the rate of Fe isotope exchange for the $δ$57Fe-spiked experiment provides critical insight for the time necessary to achieve Fe isotope exchange in two non-spiked, but otherwise identical experiments. The Fe isotope data indicate that the equilibrium fractionation between chalcopyrite and dissolved Fe, $Δ$56FeCpy-Fe (aq), at 350 {\textdegree}C is small, 0.09 {\textpm} 0.17{\textperthousand} (2$\sigma$), and is in good agreement with recent theoretical equilibrium predictions. Owing to the apparent rate of Fe isotope exchange at 350 {\textdegree}C, it is likely that chalcopyrite formed at high temperature deep-sea vents (black smoker systems) achieves isotopic equilibrium, and effectively records the Fe isotopic composition of the coexisting end-member hydrothermal fluid. Comparison of the experimental mineral{\textendash}fluid equilibrium fractionation factors with conjugate chalcopyrite and dissolved Fe pairs sampled from high temperature hydrothermal vent systems at Axial Caldera and Main Endeavour Field (Juan de Fuca Ridge) are in agreement with this inference. The experimental data were further used to determine the mineral{\textendash}mineral equilibrium Fe isotope fractionation between pyrite-chalcopyrite, $Δ$56FePyr-Cpy, at 350 {\textdegree}C by combining previously determined pyrite-Fe2+(aq) equilibrium fractionation data with chalcopyrite-Fe2+(aq) from this study. The empirically determined $Δ$56FePyr-Cpy value, 0.90 {\textpm} 0.34{\textperthousand} (2$\sigma$), is consistent with theoretical predictions, and when coupled with mineral{\textendash}fluid Fe isotope fractionation systematics and experimentally determined exchange rates, helps to delineate processes of sulfide mineralization in hydrothermal systems.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	doi = {10.1016/j.gca.2016.12.002},
	author = {Syverson, D D and Luhmann, A J and Tan, C Y and Borrok, D M and Ding, K and Seyfried, W E}
}
@article {Tan2016,
	title = {{Development and Application of a New Mobile pH Calibrator for Real-Time Monitoring of pH in Diffuse Flow Hydrothermal Vent Fluids}},
	journal = {Marine Technology Society Journal},
	volume = {50},
	number = {2},
	year = {2016},
	pages = {37{\textendash}47},
	abstract = {In situ measurement of pH in diffuse flow hydrothermal vent fluids is necessary to investigate the feedback between geochemical and biochemical processes. Accurate pH determination has been unusually challenging owing to temperature and pressure effects that place severe constraints on the performance of a wide variety of pH sensor systems. In this paper, we describe a newly developed mobile pH calibrator (MpHC), which makes use of In situ calibration protocols that enhance the accuracy of pH measurement and monitoring on the ocean floor at deep-sea hydrothermal vents. The MpHC combines the physically robust and highly sensitive iridium solid-state pH electrode with a flow control system to perform 2-point calibration with on-board pH buffer solutions. The small size and novel design of the sensor probe allow more effective access to seafloor hydrothermal vent fluids and their associated sulfide structures and biological communities. The MpHC is capable of In situ deployment by submersible via ICL (inductively couple link) communication around hydrothermal vents at pressures and temperatures up to 45 MPa and 100 degrees C, respectively. In this paper, we also present results of In situ calibration methods used to correct the standard potential and slope (mV/pH) of the solid-state electrode for temperature effects. The MpHC has been deployed most recently using the submersible Alvin during cruise AT26-17 to Axial Seamount and Main Endeavour Field, Juan De Fuca Ridge in the NE Pacific. With In situ calibration functionality, the MpHC offers the prospect of more successful longer-term measurements in keeping with power availability provided by cabled seafloor observatories coming online in the NE Pacific.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	author = {Tan, C Y and Ding, K and Seyfried, W E}
}
