The PIs propose to develop fluorescence-based fiber optic biosensors designed to measure oceanic trace levels of free Zn2+ and Cu2+ continuously in situ, in real time. These biosensors use a biomolecule, carbonic anhydrase, to transduce the level of free metal ion as a change in fluorescence intensity or lifetime that can be measured through a length of optical fiber. The use of the biomolecule as transducer confers unmatched selectivity and sensitivity on these optical sensors. Proposed improvements in the transducer molecule, fluorescent labels, and optics will permit measurement deep in the water column and in anoxic waters, where current analytical technology is incapable of acquiring the needed data. This capability will permit questions of central importance in surface zinc bioavailability, Cu availability for methanotrophs and denitrifiers, and Cu availability in reducing conditions to finally be addressed. A key goal of this project is the training of students and the introduction of students outside the discipline to marine biogeochemistry and the special character of research in a shipboard environment.
