The Barbeau lab is spending the day testing the benthic boundary layer just off the coast of the Vandenberg Air Force Base. The benthic boundary layer (BBL) is thought to be a layer of sediment mixing very near the bottom of the seafloor, that upwells trace metals.
The Barbeau lab samples the BBL by first dropping a CTD profile to see if there is a benthic boundary layer at a station location, and then sampling it with a 30L go-flow bottle on their plastic-coated winch.
The bottle is open on deck and cocked close in the air. It is weighted down and dropped very slowly.
When the bottle is under 10-15m of water, the pressure of the water opens the bottle, which we see at the surface by air bubbles escaping. Then we send the bottle to within 5m of the bottom. To close it Sarah sends a messenger down the line to close it. Sara, Maitreyi and Ethan are holding the wire to feel the sensation of it tripping closed.
Then we bring up the bottle and it is carried into the trace metal van to filter the water for trace amounts of iron and ligands. Measuring trace amounts of iron in the BBL allows the Barbeau lab to potentially find the riverine source of iron to the California Current.