title: Real-time redox speciation of iron in estuarine and coastal surface waters.
abstract: An automated, shipboard-use system was developed for real-time speciation of iron in coastal surface waters. It comprised a towed Fish underway sampler and a modified reverse flow injection analysis system with a liquid waveguide capillary flow cell-spectrophotometric detection device. The detection was based on the reaction between ferrozine and Fe(II). The detection limits of 0.3 and 0.7 nM were achieved for Fe(II) and Fe(II+III), together with their respective dynamic linear ranges of 0.5-250 and 0.9-250 nM. The system was successfully deployed and run consecutively for about 1 week during a cruise in August 2009 to the East China Sea off the Changjiang Estuary. The distribution of operationally defined field dissolvable Fe(II) and Fe(II+III) (expressed as Fea(II) and Fea(II+III)) in these areas was obtained, which showed that both Fea(II) and Fea(II+III) concentrations decreased with salinity when there were relatively high Fea(II) concentrations (up to about 120 nM) near shore. A distinct distribution of Fea(II) to Fea(II+III) ratios was also revealed, with a ratio of 0.58 in the water off Changjiang Estuary and 0.19 in the open ocean.
authors: Yongming
authors: Y
authors: Huang
authors: Dongxing
authors: D
authors: Yuan
authors: Yong
authors: Y
authors: Zhu
authors: Sichao
authors: S
authors: Feng
mesh_terms: D000818:Animals; D002681:China; D017753:Ecosystem; D063366:Estuaries; D005843:Geography; D007501:Iron / Q000032:analysis*; D009792:Oceans and Seas; D010084:Oxidation-Reduction; D010100:Oxygen / Q000032:analysis; D010655:Phenylenediamines / Q000737:chemistry; D054712:Salinity; D012767:Ships; D012995:Solubility; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D010655:Phenylenediamines; D014867:Water; C045488:N,N-dimethyl-3-phenylenediamine; D007501:Iron; D010100:Oxygen