The DigiSCAN (Digital Submersible Chemical ANalzyer) is a modular, wet-chemical analyzer based on the technology described by Weeks and Johnson (1996). It has been used for nearly two years to monitor processes that regulate nitrate concentration in the Elkhorn Slough. This data is described in an article in Estuaries by Chapin et al. (2004). The following figure shows the relationship between salinity, which is driven down by runoff from surrounding fields during rain events, and nitrate in Azevedo Pond, a tidal embayment in the upper slough. The DigiSCAN is available commercially as the YSI 9600.