Comparison of the linear Van den Berg/Ružić transformation and a non-linear fit of the Langmuir isotherm applied to Cu speciation data in the estuarine environment

Gerringa, Loes J. A.; Herman, Peter M. J.; Poortvliet, T.C.W.

doi:10.1016/0304-4203(94)00041-b

Cited by 148 publications

(110 citation statements)

References 27 publications

Supporting

Mentioning

107

Contrasting

Order By: Relevance

“…In preliminary experiments for this study, we followed a dithiocarbamate liquid extraction protocol with GF-AAS detection (Grasshoff et al 1999). Although our analysis of the SAFe D2 intercalibration sample using this method (1033 6 17 pmol L 21 , n 5 2) shows good agreement with the consensus value (1011 6 24 pmol L 21 ), the GF-AAS Cd concentrations for the Southern Ocean samples are , 55% lower than those determined by ID-TIMS.…”

Section: Resultsmentioning

confidence: 99%

“…Aliquots for determination of dissolved Cd were filtered through 0.2 mm cartridges (Sartobran) into acid-cleaned low-density polyethylene (LDPE) bottles (Nalgene) and acidified to pH , 2 with quartz-still-purified HCl. Nutrient samples were analyzed by the Royal Netherlands Institute for Sea Research using a TrAAcs 800 autoanalyzer (Bran & Luebbe) following standard methods described in Grasshoff et al (1999). Temperature, salinity, dissolved oxygen, and fluorescence were recorded using Seabird TM sensors and validated using standard procedures (Grasshoff et al 1999).…”

Section: Methodsmentioning

confidence: 99%

“…Analysis of the titration data was done by nonlinear regression using a one-ligand model (Eq. 1; Gerringa et al 1995).…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Dissolved cadmium in the Southern Ocean: Distribution, speciation, and relation to phosphate

Baars¹,

Abouchami²,

Galer³

et al. 2014

Limnology & Oceanography

109

View full text Add to dashboard Cite

We report isotope dilution analyses of dissolved cadmium (Cd) and electrochemical Cd speciation measurements in the Atlantic sector of the Southern Ocean. Bioavailable inorganic Cd is . 100 times higher in nearsurface waters south of the Polar Front compared to the Subantarctic Zone because of upwelling and reduced complexation by organic Cd ligands. To trace local changes in the relation between Cd and P, we examine the deviations from a linear deep-water Cd vs. P relation (Cd*), and find that changes in Cd* coincide with the position of frontal systems and covary with primary productivity and total dissolved Mn and Fe concentrations. These covariations agree with potential local changes in phytoplankton Cd uptake rates, resulting from differences in the availability of Cd, Zn, Mn, and Fe. A band of negative Cd* values is associated with formation of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW). In contrast to SAMW, which may export low Cd : P ratios from the Southern Ocean, the Cd : P ratios in AAIW increase by mixing with underlying Upper Circumpolar Deep Water before being exported from the Southern Ocean. Deep waters show constant Cd : P ratios, and both elements behave conservatively with end-member mixing between deep waters of the Weddell Gyre, the Antarctic Circumpolar Current, and inflowing North Atlantic Deep Water. Overall, our results support the hypothesis that the kink in the global Cd vs. P relation is largely caused by high Cd : P uptake ratios in the trace-nutrient-limited Southern Ocean.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Dissolved cadmium in the Southern Ocean: Distribution, speciation, and relation to phosphate

Baars¹,

Abouchami²,

Galer³

et al. 2014

Limnology & Oceanography

109

View full text Add to dashboard Cite

show abstract

“…(1), nonlinear regression of the Langmuir isotherm, Gledhill and van den Berg, 1994;Gerringa et al, 1995). By using the Langmuir model it is assumed that equilibrium between all Fe(III) species exists, all binding sites between Fe and the unknown ligand Lt are equal and binding is reversible.…”

Section: Calculation Of Iron Speciationmentioning

confidence: 99%

Speciation of Fe in the Eastern North Atlantic Ocean

Thuroczy

Gerringa

Klunder

et al. 2010

Deep Sea Research Part I: Oceanographic Research Papers

Self Cite

View full text Add to dashboard Cite

a b s t r a c tIn the Eastern North Atlantic Ocean iron (Fe) speciation was investigated in three size fractions: the dissolvable from unfiltered samples, the dissolved fraction (o 0.2 mm) and the fraction smaller than 1000 kDa ( o 1000 kDa). Fe concentrations were measured by flow injection analysis and the organic Fe complexation by voltammetry. In the research area the water column consisted of North Atlantic Central Water (NACW), below which Mediterranean Overflow Water (MOW) was found with the core between 800 and 1000 m depth. Below 2000 m depth the North Atlantic Deep Water (NADW) proper was recognised. Dissolved Fe and Fe in the o 1000 kDa fraction showed a nutrient like profile, depleted at the surface, increasing until 500-1000 m depth below which the concentration remained constant. Fe in unfiltered samples clearly showed the MOW with high concentrations (4 nM) compared to the overlying NACW and the underlying NADW, with 0.9 nM and 2 nM Fe, respectively. By using excess ligand (Excess L) concentrations as parameter we show a potential to bind Fe. The surface mixed layer had the highest excess ligand concentrations in all size fractions due to phytoplankton uptake and possible ligand production. The ratio of Excess L over Fe proved to be a complementary tool in revealing the relative saturation state of the ligands with Fe. In the whole water column, the organic ligands in the larger colloidal fraction (between 0.2 mm and 1000 kDa) were saturated with Fe, whereas those in the smallest fraction ( o1000 kDa) were not saturated with Fe, confirming that this fraction was the most reactive one and regulates dissolution and colloid aggregation and scavenging processes. This regulation was remarkably stable with depth since the alpha factor (product of Excess L and K 0 ), expressing the reactivity of the ligands, did not vary and was 10 13 . Whereas, in the NACW and the MOW, the ligands in the particulate (4 0.2 mm) fraction were unsaturated with Fe with respect to the dissolved fraction, thus these waters had a scavenging potential.Crown

show abstract

“…The ligand concentration and the conditional stability constant were calculated using the non-linear fit of the Langmuir isotherm (Gerringa et al, 1995).…”

Section: Cle-acsvmentioning

confidence: 99%

Enhancement of the reactive iron pool by marine diatoms

et al. 2008

View full text Add to dashboard Cite

Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Abstract Short term (2 days) laboratory experiments were performed to study the change in irradiance induced production of Fe(II) in seawater in the presence of two open oceanic Southern Ocean diatom species, Thalassiosira sp. and Chaetoceros brevis. Three irradiance conditions were applied: 1) UVB + UVA + VIS, 2) UVA + VIS, and 3) VIS, and Fe concentrations of 0 and 5 nM Fe were added to natural Southern Ocean seawater (containing 0.32 nM dissolved Fe and 1.69 equivalents of nM L − 1 Fe dissolved organic ligands, log K′ = 22.03). The photoproduced concentration of Fe(II) showed no relationship with the concentration of total dissolved Fe or the concentration of strongly chelated iron. During incubations with the diatoms an increase in the Fe(II) concentration during the second day suggested a modification of the Fe speciation. In the presence of Thalassiosira sp. photoreduction of Fe(III) was observed, whereas in the presence of C. brevis irradiance independent Fe(III) reduction played an important role in the Fe(II) production. Furthermore, a decrease in the strongly chelated Fe concentration, in concert with a decrease in the conditional stability constant, suggested a modification of the strongly chelated Fe fraction in the experiments with C. brevis. The chelated Fe fraction did not change in cultures with Thalassiosira sp. Overall, the presence of diatoms appeared to enhance the reactive Fe pool improving the biological availability of Fe.

show abstract

Comparison of the linear Van den Berg/Ružić transformation and a non-linear fit of the Langmuir isotherm applied to Cu speciation data in the estuarine environment

Cited by 148 publications

References 27 publications

Dissolved cadmium in the Southern Ocean: Distribution, speciation, and relation to phosphate

Dissolved cadmium in the Southern Ocean: Distribution, speciation, and relation to phosphate

Speciation of Fe in the Eastern North Atlantic Ocean

Enhancement of the reactive iron pool by marine diatoms

Contact Info

Product

Resources

About