Oxygen Profiles in Salty Crust
Needle sensors used for profiles in salt crusts.
Needle sensors (pH, H2S, oxygen) have been successfully applied to measure profiles in salt crusts in the Read Sea in Israel (Dr. Don Canfield and Ketil Sørensen, University of Southern Denmark).
Since the crust was impossible to penetrate without breaking the needle sensor, a pre-drilled hole was used for measurements of the profiles.
First a hole was made in the water covered gypsum crust with a syringe needle, then the equilibrium was allowed to settle in the pore water that filled up the hole and then profiles were measured with the needle sensors.
The graph below shows an oxygen profile measured in the crust showing two distinct photosynthetic zones of bacteria (the green and the purple).