PROJECT TITLE: A Fluorosensor Sediment Profile Imaging Incubation system (F-SPII) for sediment biogeochemistry and diagenetic process studies
Project Summary
Diagenetic reactions and material transport in surface sediments exert major controls on biogeochemical cycling in shallow marine environments. The PIs propose to develop a sediment profile imaging camera and incubation system for integration with planar optode fluorescence sensors. The system will allow rapid in situ reconnaissance and manipulative process studies of 2-dimensional chemical patterns and solute transport rates in bottom deposits. Building on earlier REMOTS technology, the fluorosensor sediment profiling and incubation system will penetrate the upper 10 - 15 cm of the seabed, allowing direct contact of a set of solute specific sensor foils with overlying water and underlying sediment in vertical section. The sampled zone will encompass the most biogeochemically active region of sedimentary deposits. In addition to visible imaging, the instrument will be capable of fluorescence intensity, ratiometric excitation - emission response, and fluorescence lifetime imaging of the vertical section over areas ~300 cm2 and at high spatial resolution. The optical system design will readily allow incorporation of new excitation sources as high power LED technology rapidly advances. The F-SPII system will be tethered and designed for use primarily in estuarine, harbor, and shelf environments, but could be modified for deeper deployments. Images will be monitored and automatically processed realtime on shipboard. Initial applications will utilize existing O2, pH, and pCO2 sensor foils but the instrument will be used to further optimize them, and to evaluate and optimize novel planar sensors under development (composites, H2S, Ca++). The F-SPII will also be utilized to examine the distribution of naturally fluorescent components, such as subclasses of DOC in surface sediment (e.g., humics) and possibly photopigments. An incubation chamber will optionally be deployed, allowing capture of a known volume of overlying water for sediment - water solute flux measurements and fluorescent tracer injection. The suite of measurements obtained should provide unprecedented elucidation of early diagenetic remineralization rates and complex reaction patterns, as well as quantification of solute transport processes in the bioturbated zone.
