High temperature hydrothermal fluids are collected during the MOMARSAT 2018 cruise by gas-tight fluid sampler manipulated and triggered by the hydraulic arm of the submarine vehicle (HOV Nautile). Several hydrothermal vents are sampled, namely : Aisics, Montsegur, Montserrat, Isabel, Sintra, Y3, White Castle, Crystal, Capelinhos, Cimendeff, Tour Eiffel.

Several chemical analyses are performed aboard the research vessel: such as salinity and d20/20 by refractometer, Conductivity, salinity and total dissolved solid (TDS) by electrode (standard solution at 1413 µS/cm), pH and Eh by electrode (pH standard 4.01 and 7; Eh standard solution at -220mV), iron concentration by photometer (up to 5 ppm), H2S and total S concentrations measured by electrode (AquaMS, amperometric method) at measured pH value. Regional Node: EMSO-Azores Vent field : Lucky Strike Latitude : 37º17’N Longitude : 32º16’W 1600 – 1750 m depth