title: Microbenthic chamber with microelectrode for in-situ determination of fluxes of dissolved S(-II), I-, O2, Mn, and Fe.
abstract: A 2-mL microbenthic chamber was fitted with a microelectrode for the in-situ determination of benthic fluxes of S(-II), I-, O2, Mn(II), and Fe(I). Detection was by voltammetry using a battery operated potentiostat and a gold microelectrode. The chamber was fitted on a Perspex plate to be placed on sediments. Because of the small chamber volume, benthic fluxes could be determined in a few hours rather than days, without the need for sample extraction. Tests on homogenized sediments in the laboratory showed fluxes of 17.1+/-1.8 nmoles cm(-2) min(-1) S(-II) and 1.3+/-0.2 nmoles cm(-2) min(-1) Mn. Benthic fluxes of oxygen and iodide were determined in situ in the field. The oxygen flux was negative (consumption) at a rate of -4.9+/-0.5 nmoles cm(-2) min(-1) O2. The I- flux was initially negative in oxygenated waters at a rate of -30+/-3 pmoles cm(-2) min(-1) and subsequently turned positive to a rate of 12+/-1 pmoles cm(-2) min(-1) when the oxygen concentration dropped. The rate of change in the microbenthic chamber was sufficiently quick to complete a flux measurement within minutes.
authors.affiliation: Department of Earth and Ocean Sciences, University of Liverpool, Liverpool L69 3GP, United Kingdom.
authors.forename: Conrad S
authors.initials: CS
authors.lastname: Chapman
authors.forename: Constant M G
authors.initials: CM
authors.lastname: Van Den Berg
mesh_terms: D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D005618:Fresh Water / Q000032:analysis; D019015:Geologic Sediments / Q000032:analysis; D007454:Iodides / Q000032:analysis*; D007501:Iron / Q000032:analysis*; D008345:Manganese / Q000032:analysis*; D008839:Microelectrodes; D010084:Oxidation-Reduction; D010100:Oxygen / Q000032:analysis*; D012623:Seawater / Q000032:analysis; D013455:Sulfur / Q000032:analysis*; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D007454:Iodides; D014874:Water Pollutants, Chemical; D008345:Manganese; D013455:Sulfur; D007501:Iron; D010100:Oxygen