Effect of siderophores on the light-induced dissolution of colloidal iron(III) (hydr)oxides

Borer, Paul; Sulzberger, Barbara; Reichard, P.U.; Kraemer, Stephan M.

doi:10.1016/j.marchem.2004.08.006

Cited by 133 publications

(121 citation statements)

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“…Previous studies on the dissolution of colloidal Fe (hydr)oxides show that oxalate is a suitable ligand because of the formation of surface ternary complex Fe(III)oxide-oxalate-Fe(II) acting as an electron bridge for electron transfer from Fe(III) to Fe(II) (Sulzberger et al 1989). Oxalate solution, as used in this study, can result in significant Fe(hydr)oxides dissolution by three pathways acting synergistically (Sulzberger et al 1989, Borer et al 2005): (1) surface chelation, (2) Fe(II)-catalyzed dissolution in the presence of other chelating agent (e.g., EDTA), and (3) light-induced dissolution in presence of electron donor (e.g., oxalate). In this case, the Fe desorption efficiency could not be predicted solely using the Eigen-Wilkens theory and the affinity of the washing agent for Fe(III), as opposed to previous observations for other transition metals (Hassler et al 2004).…”

Section: Assessmentmentioning

confidence: 99%

Discriminating between intra‐ and extracellular metals using chemical extractions: an update on the case of iron

Hassler

Schoemann

2009

Limnology & Ocean Methods

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Iron influences the climate system by limiting primary productivity. It is therefore essential to accurately measure the iron fraction associated with phytoplankton in aquatic systems. A washing procedure using EDTA, being efficient for numerous trace metals, is not strong enough to remove iron adsorbed to the surface of microorganisms. Stronger washing solutions are used for iron, but these have only been assessed for a marine diatom. This study assesses the applicability of the oxalate washing procedure for both fresh-and seawater aquatic systems. We assessed iron solubilization as a result of oxalate washing in both synthetic and natural freshwater and seawater, and we tested it on several model phytoplankton and natural assemblages from Lake Champlain, the Southern Ocean, and the Derwent River estuary. We report the effects of the oxalate solution contact time, concentration, and amendment. Our study shows that 20-min washing provides an efficient measurement of the intracellular phytoplanktonic pool of iron in both freshwater and seawater. The direct amendment of oxalate in the experimental solution presents many advantages that are critical for the measurement of size-fractionated particulate iron. These include fine control of bioaccumulation termination, a significant gain in time, and homogeneity of the washing treatment.

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Section: Assessmentmentioning

confidence: 99%

Discriminating between intra‐ and extracellular metals using chemical extractions: an update on the case of iron

Hassler

Schoemann

2009

Limnology & Ocean Methods

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“…Thus the membrane permeability of diatoms might have changed, although the heat-killed cells were kept intact (observed under the microscope). In addition, Fe dissociation from the cell surface might be overestimated because of DFB competition binding (Borer et al 2005). However, Fe release from the intracellular compartments of living cells was not affected because neither the DFB-Fe complex (Wells 1999;Kuma et al 2000) nor DFB was directly bioavailable, at least for this algal species.…”

Section: Fe Efflux Under Different Temperatures and Irradiances-mentioning

confidence: 99%

Fulfilling iron requirements by a coastal diatom under different temperatures and irradiances

Miao

Wang

2006

Limnol. Oceanogr.

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The strategies used by a coastal diatom, Thalassiosira pseudonana, for potentially different iron (Fe) requirements under different temperatures and irradiances were examined on the basis of three parameters: Fe uptake rate, cellspecific growth rate, and Fe efflux rate constant. These three variables determined the cellular Fe concentration, and they were all quantified under different temperatures and irradiances during long-term (days) and short-term (hours) 59 Fe exposures. Results obtained from both exposures were consistent. Although more Fe was required under the lower irradiance, Fe uptake rate decreased 1.78ϫ and 2.20ϫ as the irradiance decreased from 340 to 40 mol photons m Ϫ2 s Ϫ1 when measured by short-and long-term exposures, respectively. Under this condition, the cellspecific growth rate decreased from 1.30-1.50 to 0.51-0.63 d Ϫ1 to keep a relatively high intracellular Fe concentration under lower irradiance. The opposite trend was observed for temperature. The higher Fe requirement at higher temperature was fulfilled mainly through an increase of Fe uptake rate with increasing temperature. For example, the Fe uptake rate increased by 1.21ϫ and 2.55ϫ as the temperature increased from 15ЊC to 24ЊC in the short-and long-term exposures, respectively. In contrast, the cell-specific growth rate was relatively constant (0.92-1.06 d Ϫ1

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“…This gradient results from the increased input of Fe at coastal margins from river outflow and the upwelling of suspended shelf sediments (Bruland et al 1991;Kuma et al 1996). Rivers can indirectly supply dissolved Fe to nearshore ecosystems by exporting Fe-rich particles to the coastal shelf area that are subsequently upwelled to the surface (Johnson et al 1999), where Fe may be remineralized from these particles in the presence of light and Febinding ligands (Borer et al 2005). The upwelling of bottom boundary layer (BBL) sediments, particularly from midshelf mudbelt deposits (Xu et al 2002), has been identified as the predominant source of Fe to shelf surface waters along the California coast (Johnson et al 1999;Fitzwater et al 2003).…”

mentioning

confidence: 99%

Dissolved iron speciation in two distinct river plumes and an estuary: Implications for riverine iron supply

Buck

Lohan

Berger

et al. 2007

Limnology & Oceanography

153

117

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Dissolved iron (Fe) speciation in the Columbia River plume, the San Francisco Bay plume, and the Columbia River estuary was investigated using competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV) with the added ligand salicylaldoxime. A stronger L 1 -type Fe-binding ligand class was measured in all surface samples, and in the Columbia River estuary. A weaker L 2 -type ligand class was present in the far-field Columbia River plume and the San Francisco Bay plume but was not observed in the low-salinity (S 5 1.4-22.5) waters of the near-field Columbia River plume or estuary. Concentrations of total dissolved Fe were correlated with the concentrations of the stronger L 1 -type ligand in nonestuarine (S . 13) surface samples. Leachable particulate (.0.4 mm) Fe concentrations in the Columbia River plume were measured to supplement existing data from the San Francisco Bay plume. There is a large concentration of readily leachable particulate Fe in the two plumes, yet it is the concentration of ambient L 1 -type ligands that appears to dictate the concentration of dissolved Fe in these waters and, consequently, the supply of dissolved Fe to neighboring coastal waters. The correlation between dissolved Fe and L 1 ligand concentrations in both plume waters, as well as in California Current and upwelled surface waters, suggests that this relationship will persist in other coastal environments and should be considered when evaluating and modeling coastal Fe cycling and supply.

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Effect of siderophores on the light-induced dissolution of colloidal iron(III) (hydr)oxides

Cited by 133 publications

References 64 publications

Discriminating between intra‐ and extracellular metals using chemical extractions: an update on the case of iron

Discriminating between intra‐ and extracellular metals using chemical extractions: an update on the case of iron

Fulfilling iron requirements by a coastal diatom under different temperatures and irradiances

Dissolved iron speciation in two distinct river plumes and an estuary: Implications for riverine iron supply

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