Transformation of iodate to iodide in marine phytoplankton driven by cell senescence
نویسندگان
چکیده
Previous studies have suggested that phytoplankton play an important role in the biogeochemical cycling of iodine, due to the appearance of iodide in the euphotic zone. Changes in the speciation of iodine over the course of the growth cycle were examined in culture media for a variety of phytoplankton taxa (diatoms, dinoflagellates and prymnesiophytes). All species tested showed the apparent ability to reduce iodate to iodide, though production rates varied considerably between species (0.01 to 0.26 nmol l–1 μg–1 chl a d–1), with Eucampia antarctica the least and Pseudo-nitzschia turgiduloides the most efficient iodide producers. Production was found to be species specific and was not related to biomass (indicated by e.g. cell size, cell volume, or chl a content). In all species, except for the mixotrophic dinoflagellate Scrippsiella trochoidea, iodide production commenced in the stationary growth phase and peaked in the senescent phase of the algae, indicating that iodide production is connected to cell senescence. This suggests that iodate reduction results from increased cell permeability, which we hypothesize is due to subsequent reactions of iodate with reduced sulphur species exuded from the cell. A shift from senescence back to the exponential growth phase resulted in a decline in iodide and indicated that phytoplankton-mediated oxidation of iodide to iodate was likely to be occurring. Iodide production could not be observed in healthy cells kept in the dark for short periods. Bacterial processes appeared to play only a minor role in the reduction of iodate to iodide.
منابع مشابه
Iodine assimilation by marine diatoms and other phytoplankton in nitrate-replete conditions
Several marine phytoplankton species, primarily diatoms, were examined for the accumulation of iodide (10 species) and iodate (9 species) using radioactive iodine-125 in f/2 artificial seawater, a nitrate-enriched medium. Iodide accumulation (net uptake) rates were variable, and diatoms exhibited the highest rates. Emiliania huxleyi and Synechococcus sp. did not accumulate iodide. Accumulation ...
متن کاملIodate and Iodide Distributions in the Waters of a Stratified Estuary
Speciation and distribution of inorganic iodine in the highly stratified Krka estuary (east coast of the Adriatic Sea) were investigated in the period from December 2000 to April 2001. Conservative behavior of total inorganic iodine was confirmed during the investigated period, but significant temporal and longitudinal variations were also observed. Concentrations of iodate and iodide were less...
متن کاملSpectrophotometric Simultaneous Kinetic Determination of Iodide and Iodate Using Partial Least-Squares Calibration Method in a Single Kinetic Run
A rapid, sensitive and versatile kinetic method is presented for the simultaneous spectrophotometric determination of iodide and iodate by partial least-squares regression (PLS) using original and derivate data named as absorbance and rate data. The method is based on the catalytic effect of the cited anions on the reaction rate between Ce(IV) and As(III) in 2 mol l?1 sulfuric acid medium. The ...
متن کاملThe potential role of kelp forests on iodine speciation in coastal seawater
Kelps have a major role in marine and atmospheric iodine cycling in the coastal zone of temperate regions, with potential wide-ranging impacts on ozone destruction in the coastal marine boundary layer. However, little is known about the impact of kelp forests on iodine speciation in coastal sea water. To address this, we examined iodide and iodate concentrations in seawater in and around a gian...
متن کاملEmission of iodine-containing volatiles by selected microalgae species
In this study we present the results of an emission study of different phytoplankton samples in aqueous media treated with elevated ozone levels. Halocarbon measurements show that the samples tested released bromoform and different iodocarbons, including iodomethane, iodochloromethane and diiodomethane. Iodide and iodate levels in the liquid phase were representative of concentrations of surfac...
متن کامل