Geochemical Constraints on Light Emission in Seafloor Hydrothermal Systems: An Experimental Study Using In-Situ Spectral and Chemical Sensor Techniques

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Recent studies with highly sensitive CCD camera systems deployed from the submersible ALVIN have revealed light being emitted from hydrothermal fluids venting at the ocean floor. In general, these studies reveal photon fluxes from the vent fluids in excess of those predicted from simple blackbody radiation, suggesting a number of in-situ light-generating processes. In particular, chemiluminescence (emission of light that accompanies chemical reactions), sonoluminescence (light emitted by vapor bubble implosion or cavitation), or crystalloluminescence (emission of light accompanying onset of mineral precipitation) are thought to be the mose likely processes to account for this. This investigation is designed to assess unambiguously the intensity and spectral characteristics of light generated by chemical reactions, vapor generation, effects and crystallization processes at temperatures and pressures applicable to marine hydrothermal systems. Under this award, the PIs will use a series of computer controlled Ti-flow reactors, modified to contain optical windows, fiber optic cables, spectrometer, and CCD detector that will allow the intensity and spectral variability of light to be measured and monitored. The experiments will be designed to specifically assess the role of chemiluminescence, sonoluminescence and crystalloluminescnce on light generation for an appropriate range of temperatures, pressures, compositional effects, and fluid flow rates. The experiments will include a number of in-situ chemical sensors developed at to better constrain the distribution of aqueous species during the experiments, while simultaneously linking these data to spectral observations.