Osmotically pumped chemical analyzers are being developed at MBARI by Hans Jannasch, Carole Sakamoto and Kenneth Johnson. The completely self contained analyzers are mounted on mooring cables or on instrument cages and continuously measure dissolved nitrate concentrations for over three month time periods (1/e response time <13 min, 1 reading taken each each 5 to 15 minutes depending on available SRAM). OsmoAnalyzers measuring dissolved nitrate have been deployed on moorings in Monterey Bay, at the JGOFS Time Series sites off of Bermuda (BATS) and Hawaii (HOT), on several DOE/OMP moorings off Cape Hatteras and on two of the TOGA/TAO moorings on the equatorial Pacific.
We are currently adapting this technology to analyze for S=, with further plans to adapt colorimetric determinations for Mn and Fe, and PO4 and Si. A more complete description of the analyzers can be found in Jannasch et al., 1994, Anal. Chem., 66, 3352-3361.
The bare OsmoAnalyzer in the laboratory. From left to right are the sample pump (NaCl and membranes visible in the top and bottom compartments, respectively), the reagent pumps (on orange tubes), the support plate (with the manifold, source and detector on top), and the standard and blank injection pumps. The analyzer is 20 x 15 x 8 cm.
Deploying nitrate OsmoAnalyzers on the first HOT mooring (January 1997).
Mark Pickerill and myself on the fantail of the R.V. Moana Wave (Univ. of Hawaii).