Twenty successful dives were conducted with DSV Alvin to measure in situ the speciation of Fe(II) and SH₂S in  diffuse flows around hydrothermal vents and in plumes above black smokers. The hydrothermal vents were located 2500 m deep at 9^oN Equatorial Pacific Rise (EPR) and 2000 m deep in the Guaymas Basin (Sea of Cortés, Gulf of California). A selection of pictures onboard R/V Atlantis and DSV Alvin are shown below.
 

R/V Atlantis II in Manzanillo (Mexico)

We used voltammetry to measure O_2(aq), Fe(II), FeS_(aq), and SH₂S in situ with mercury-coated solid-state microelectrodes. The potentiostat for this cruise was built by Don Nuzzio (Analytical Instrument Systems, Inc). It was encased in a water-proof canister resistant to high pressures. Solid state Au/Hg microelectrodes were built in our laboratory to perform these measurements and placed into a wand for easy handling by the arms of DSV Alvin.

To learn more about the cruise, check out the web page of Extreme I (9N EPR) and Extreme 2000 (Guaymas Basin).

The first picture shows Biovent before it collapsed. The chimney is leaning to the right. The black "smoke" can be seen in the back. On the bottom left, the two wands carrying electrodes are stored in Alvin's basket.

The second picture shows the port arm of Alvin holding the microelectrode wand next to the chimney. Voltamogramms are recorded and analyzed in real time.

 
 
 
 

In the third picture, the wand is placed in the plume 1 m above the chimney. The temperature at this location can be up to 50C.
 

In the last picture, the microelectrodes are positioned just above a Riftia clump with the starboard arm of Alvin. The temperature at this location is 20C.