Determination of humic substances in natural waters by cathodic stripping voltammetry of their complexes with iron

Laglera, Luis M.; Battaglia, Gianluca; Berg, Constant M.G. van den

doi:10.1016/j.aca.2007.07.059

Cited by 96 publications

(97 citation statements)

References 30 publications

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“…Here, 7.4 ppb (PF) and 33.6 ppb (SAZ) SRFA equivalents were measured at the depth of Chl a maximum (Table S1). However, this analytical approach is not specific to humic substances; other types of compounds differing from humics, such as glutathione, can be detected (40). EPS was also detected by this technique with 22 nM of EPS (37.4 ppm of EPS) corresponding to 37.9 ppb of SRFA equivalent.…”

Section: Resultsmentioning

confidence: 86%

“…Our study shows that, in the iron-deficient open ocean, saccharides can significantly contribute to the operationally defined pool of SRFA-like substances detected by the technique developed by Laglera and van den Berg (40). In offshore pelagic waters, the nature of organic substances detected by this technique would be quite different from SRFA or coastal organic material, likely closer to the bacterial EPS used here.…”

Section: Discussionmentioning

confidence: 82%

“…Not surprisingly, the concentrations of SRFA-equivalent substances in the euphotic zone of the Southern Ocean (this study) were much lower than for the Irish Sea and at depth in the Pacific Ocean (36-370 ppb of SRFA equivalents; refs. 16,40). In our study, the SRFA-equivalent concentrations detected, would correspond to 4 nM of EPS in the PF and 20 nM of EPS in the SAZ.…”

Section: Discussionmentioning

confidence: 99%

“…Accuracy of the CLE-AdCSV method was verified using reference seawaters (NASS-5 and SAFe D2; SI Materials and Methods). In addition, operationally defined humiclike compounds were determined (40). SRFA (standard I, International Humic Substances Society) was used to calibrate the instrument (SI Materials and Methods) and concentrations were expressed in SRFA equivalents.…”

Section: Methodsmentioning

confidence: 99%

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Saccharides enhance iron bioavailability to Southern Ocean phytoplankton

Hassler

Schoemann

Nichols

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

254

218

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Iron limits primary productivity in vast regions of the ocean. Given that marine phytoplankton contribute up to 40% of global biological carbon fixation, it is important to understand what parameters control the availability of iron (iron bioavailability) to these organisms. Most studies on iron bioavailability have focused on the role of siderophores; however, eukaryotic phytoplankton do not produce or release siderophores. Here, we report on the pivotal role of saccharides-which may act like an organic ligand-in enhancing iron bioavailability to a Southern Ocean cultured diatom, a prymnesiophyte, as well as to natural populations of eukaryotic phytoplankton. Addition of a monosaccharide (>2 nM of glucuronic acid, GLU) to natural planktonic assemblages from both the polar front and subantarctic zones resulted in an increase in iron bioavailability for eukaryotic phytoplankton, relative to bacterioplankton. The enhanced iron bioavailability observed for several groups of eukaryotic phytoplankton (i.e., cultured and natural populations) using three saccharides, suggests it is a common phenomenon. Increased iron bioavailability resulted from the combination of saccharides forming highly bioavailable organic associations with iron and increasing iron solubility, mainly as colloidal iron. As saccharides are ubiquitous, present at nanomolar to micromolar concentrations, and produced by biota in surface waters, they also satisfy the prerequisites to be important constituents of the poorly defined "ligand soup," known to weakly bind iron. Our findings point to an additional type of organic ligand, controlling iron bioavailability to eukaryotic phytoplankton-a key unknown in iron biogeochemistry.trace metals | carbohydrates | organic matter | exopolymeric substances | plankton

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Section: Resultsmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Saccharides enhance iron bioavailability to Southern Ocean phytoplankton

Hassler

Schoemann

Nichols

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

254

218

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“…2,[8][9][10][11][12] In seawater, the majority of dissolved ferric (Fe(III)) and ferrous (Fe(II)) species are present in the form of complexes with dissolved organic matter. 2,[13][14][15] Based on this, a fertilizer comprised of a steel slag and compost was tested for its ability to supply dissolved Fe to barren coastal areas, and this attempt was successful and resulted in the restoration of seaweed beds. 16 In this technique, seawater extractable organic matter (SWEOM) from the compost serves as a chelator of Fe and allows for its elution from the steel slag.…”

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confidence: 99%

Determination of Labile Fe(II) Species Complexed with Seawater Extractable Organic Matter Under Seawater Conditions Based on the Kinetics of Ligand-exchange Reactions with Ferrozine

2013

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Barren ground is a phenomenon associated with the depletion of seaweed in coastal areas. The development of barren ground has been attributed to a lack of soluble Fe (<1 nM), 1 which is an essential micronutrient for the growth of algae. 2,3 In macroalgae, the uptake of soluble iron is required for the gametophyte to produce an oogonium or an antheridium, 4-7 and a sporophyte is formed from the matured gametophyte. 3 Thus, a lack of dissolved Fe in coastal area seawater can lead to seaweed depletion. It is known that natural organic matter plays an important role in the mobility, solubility and bioavailability of trace metals in terrestrial and aquatic environments. 2,[8][9][10][11][12] In seawater, the majority of dissolved ferric (Fe(III)) and ferrous (Fe(II)) species are present in the form of complexes with dissolved organic matter. 2,[13][14][15] Based on this, a fertilizer comprised of a steel slag and compost was tested for its ability to supply dissolved Fe to barren coastal areas, and this attempt was successful and resulted in the restoration of seaweed beds. 16 In this technique, seawater extractable organic matter (SWEOM) from the compost serves as a chelator of Fe and allows for its elution from the steel slag. 17,18 Fe(III)-oxides are found on the surface of the steel slag, 19 and can be reduced to soluble Fe(II) species in the presence of dissolved organic matter. 20 It has been reported that all of the reduced Fe(II) species are complexed with dissolved organic matter. 21 Therefore, the nature of the complex produced between SWEOM and Fe(II) need to be evaluated to better understand the performance of such fertilizers.On the other hand, estimating the bioavailability of a metal to aquatic biota is an important approach. 22,23 The kinetic stability of complexes is a key factor in determining the bioavailability of metal species. 2,3,22,24,25 Readily dissociable complexes (labile species) are the likely primary source of soluble iron for algae. 2,19,[26][27][28] A key factor in the uptake of Fe(II) involves ligand-exchange reactions between dissolved organic matter and receptor proteins on the cell-membrane. 2 The kinetics of ligand-exchange reactions of Fe(II)-humic acid complexes have been investigated using ortho-phenanthroline or ferrozine (FZ) as models of receptor proteins, 17,29 although the conditions (pH 3.6 or 5, I = 0.02) were far from those for seawater (pH 8, I = 0.7). To investigate the contribution of SWEOM as a chelator of Fe, it should be examined that the complexation ability under the conditions of seawater. However, it is difficult to determine both free and complex species of Fe(II) at higher pH and ionic strength levels because Fe(II) is readily oxidized to insoluble Fe(III)-hydroxides, which precipitates from the solution. 30 Indeed, pH and ionic strength both have a dramatic 2013 © The Japan Society for Analytical Chemistry † To whom correspondence should be addressed. Experimental MaterialsAmmonium iron(II) sulfate hexahydrate (Fe(SO4)2(NH4)2·6H2O), tris(hydroxymethyl)ami...

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Determination of Bismuth by Adsorptive Stripping Voltammetry Using Aluminum Oxide for Elimination of Environmental Sample Matrix Interferences

Koper

Grabarczyk

2014

Electroanalysis

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The aim of this work was to find a fast new and simple method for efficient elimination of negative influence of humic substances and synthetic surfactants in the voltammetric determination of bismuth. The negative influence of the organic matrix present in environmental water samples due to their adsorption on aluminum oxide was successfully evaluated. The organic compounds such as humic substances and surface active compounds were removed by adsorption on the surface of aluminum oxide from the water samples. The application of this method was the recovery of Bi(III) from spiked water samples.

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Determination of humic substances in natural waters by cathodic stripping voltammetry of their complexes with iron

Cited by 96 publications

References 30 publications

Saccharides enhance iron bioavailability to Southern Ocean phytoplankton

Saccharides enhance iron bioavailability to Southern Ocean phytoplankton

Determination of Labile Fe(II) Species Complexed with Seawater Extractable Organic Matter Under Seawater Conditions Based on the Kinetics of Ligand-exchange Reactions with Ferrozine

Determination of Bismuth by Adsorptive Stripping Voltammetry Using Aluminum Oxide for Elimination of Environmental Sample Matrix Interferences

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