title: High-resolution in situ analysis of nitrate and phosphate in the oligotrophic ocean.
abstract: Accurate, high-resolution profiles of nitrate and phosphate distributions in the open ocean are difficult to obtain using conventional techniques. Concentrations typically range from low nanomolar levels in the stratified euphotic zone to micromolar levels below the nutricline. With multiple pumps, a heating cartridge, a long-path-length cell, and a multiwavelength spectrometer, the reconfigured Spectrophotometric Elemental Analysis System (SEAS) provides the capability to fully ascertain the distributions of nitrate and phosphate in the upper 200 m of the oligotrophic ocean. By utilizing a 15 cm path length and multiple wavelength spectrophotometry, SEAS can detect nitrate concentrations from 2 nM to 20 microM and, with a 50 cm path length, can accurately measure phosphate concentrations from 1 nM to 1 microM. SEAS is capable of collecting auxiliary data from up to four separate instruments, including a CTD, a fluorometer, a PAR sensor, and a second SEAS instrument. Sampling frequency depends on peripheral instrument selection and ranges from 0.4 to 0.75 Hz.
authors.affiliation: College of Marine Science, University of South Florida, 140 Seventh Avenue South, St. Petersburg, Florida 33701, USA.
authors.forename: Lori R
authors.initials: LR
authors.lastname: Adornato
authors.forename: Eric A
authors.initials: EA
authors.lastname: Kaltenbacher
authors.forename: Danielle R
authors.initials: DR
authors.lastname: Greenhow
authors.forename: Robert H
authors.initials: RH
authors.lastname: Byrne
mesh_terms: D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D009566:Nitrates / Q000032:analysis*; D009792:Oceans and Seas; D010710:Phosphates / Q000032:analysis*; D012623:Seawater / Q000737:chemistry*; D012984:Software
chemical_list: D009566:Nitrates; D010710:Phosphates