Margareta Wedborg - Academia.edu (original) (raw)
Papers by Margareta Wedborg
The role of humic substances and total organic carbon in the Southern Ocean biogeochermistry
Analytica Chimica Acta, 1985
ABSTRACT The acid-base properties of aquatic fulvic acid, concentrated from the Göta River, were ... more ABSTRACT The acid-base properties of aquatic fulvic acid, concentrated from the Göta River, were studied by means of potentiometri titrations. The forward and reverse titrations exhibited hysteresis, which decreased as the fulvic acid underwent repeated titration. A simple model based on six titratable groups, within the pH range 2.5–10.4, could explain the acid-base properties. Electrostatic polymeric effects and heterogeneity of the fulvic acid (i.e., a distribution of constants rather than a set of distinct constants) were not included in the model. It was found that the three most acidic groups were carboxylic.
Dissolved humic substances and their chemical construents in the marine nitrogen and carbon cycle... more Dissolved humic substances and their chemical construents in the marine nitrogen and carbon cycles of Arctic waters
Water Research, Apr 1, 1988
ABSTRACT
Marine Chemistry, Aug 1, 1988
In a recent paper, van den Berg and Rogers proposed a two-point potentiometric method for estimat... more In a recent paper, van den Berg and Rogers proposed a two-point potentiometric method for estimating the alkalinity of estuarine waters. There are several problems associated with the application of such methods. Potential users should consider these problems before they finally decide whether a one-or two-point method or an alkalinity titration is the suitable choice. The purpose of this note is to discuss errors that can be expected if the procedure of van den Berg and Rogers is used. Some of these errors can be decreased by proper correction, while others are more difficult to compensate for.
Analytica Chimica Acta, 1987
... The influence of fluoride and sulphate on buffers usef for the determination of the pH and sp... more ... The influence of fluoride and sulphate on buffers usef for the determination of the pH and speciation of protolytes in seawater. ... of 0.7 M is quite different from the lowsalinity NBS buffers with an ionic strength of less than 0.1 M, and because it is desirable to make very precise pH ...
Chemosphere, Feb 1, 2011
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
Springer eBooks, Nov 23, 2005
The degree of binding of calcium to aquatic fulvic acid from the Göta River was estimated from po... more The degree of binding of calcium to aquatic fulvic acid from the Göta River was estimated from potentiometric titrations. A pH-glass electrode and a calcium-selective electrode were used to monitor the free concentrations of the competing, central ions. The ionic strength and the temperature were maintained constant at 0.1 M and 25°C. The total concentration of fulvic acid was maintained
Analytica Chimica Acta, May 1, 2001
Analysis of three-dimensional fluorescence spectra has proved to be a valuable tool in the charac... more Analysis of three-dimensional fluorescence spectra has proved to be a valuable tool in the characterisation of fluorescent dissolved organic matter (FDOM). Application of multivariate methods is a development that further enhances the capabilities of fluorescence spectroscopy for qualitative as well as quantitative analysis. In this work, principal component analysis (PCA) and partial least squares regression (PLS) are applied on fully corrected excitation-emission matrices (EEMs). The relation between sampling site and fluorescence properties in a coastal environment is analysed with PCA and PLS. The applicability of fluorescence spectroscopy and multivariate analysis for the evaluation of properties of humic substances (HS) is discussed.
Analytica Chimica Acta, 1986
ABSTRACT
Marine Chemistry, May 1, 1978
A Dead Sea brine (DSB) has a salinity of 250 g/kg and an entirely different ionic balance than st... more A Dead Sea brine (DSB) has a salinity of 250 g/kg and an entirely different ionic balance than standard seawater (SSW) by loss of sodium chloride, calcium sulfate and small amounts of calcium carbonate and gain of magnesium, calcium and potassium chlorides (see Table I).
Deep Sea Research Part B. Oceanographic Literature Review, 1982
On the evaluation Alkalinity. Non-linear curve-fitting of potentiornetric titrations Potentiometr... more On the evaluation Alkalinity. Non-linear curve-fitting of potentiornetric titrations Potentiometric titration pH scales Seawater of seawater with hydrochloric acid Alcalinité Ajustement de courbe non linéaire Titrage potentiométrique Échelles de pH Eau de mer
Journal of Solution Chemistry, 1980
The stability constant K1 of the equilibrium NH3 + H + ~ NH + was determined by potentiometric ti... more The stability constant K1 of the equilibrium NH3 + H + ~ NH + was determined by potentiometric titration in synthetic seawaters of 5 to 40~oo (per mille) salinity and sodium chloride solutions between 0.2 and 0.7 M ionic strength at temperatures of 5, 15 and 25~ Moreover, K1 was determined in sulfate-free seawater of 35~oo salinity and 25~ The dependence of log Kz on salinity (or ionic strength) and temperature can be reasonably well described by Hnear relations. The K~ obtained for sulfate-free seawater agrees very well with earlier experimental results and theoretical predietions. From the measured K1 and literature data on the equilibrium NH3(atm) ~-NH3(aq., NaCl), the atmospheric concentration of ammonia at equilibrium with seawater was estimated.
The journal of automatic chemistry, 1981
Marine Chemistry, Apr 1, 1982
The dependence of the total carbonate concentration of ocean water on temperature and atmospheric... more The dependence of the total carbonate concentration of ocean water on temperature and atmospheric partial pressure of carbon dioxide is calculated. The results show that the increase in total carbonate caused by the increase of carbon dioxide in the atmosphere is ca. 25-50 times larger than the precision in the experimental determination of Ct.
Marine Chemistry, Apr 1, 1989
Deep-sea Research Part I-oceanographic Research Papers, Nov 1, 2007
The purpose of the work presented in this paper was to study the components of fluorescent organi... more The purpose of the work presented in this paper was to study the components of fluorescent organic matter (FOM) resulting from multi-way decomposition of excitation-emission matrices (EEMs) and to find out how their relative distributions and amounts were affected by the changing hydrography and productivity in the Southern Ocean. Data were collected during the austral summer 97/98 along the 61E meridian covering the area between the spring ice edge and the Subtropical Front. By multiway PARAllel FACtor (PARAFAC) analysis, fluorescence EEMs could be decomposed into components that could be used for relative quantification. It is shown that three components suffice to model the fluorescence in this specific region. Two of the components obtained were protein-like and directly related to in-situ production/degradation; they were correlated with chlorophyll a, and were found to mix down to the core of the Antarctic intermediate water (AAIW) in the Subtropical Front. One component was classified as UV/Visible humic-like and showed a distribution that was very closely related to the qsu-calibrated fluorescence, i.e. indicative of terrestrial input, and of long term processes in the ocean. We suggest that the UV/Visible humic-like component consists of refractory material that is not produced or degraded significantly. It is concluded that a small number of components from PARAFAC analysis were satisfactory representatives of the major types of UV-blue fluorescent structural units present. The qualitative and quantitative results from the PARAFAC model also correlated well with other chemical and physical parameters.
Water Air and Soil Pollution, Apr 1, 1991
Sulphur is an essential element for aquatic biosystems, the life processes of which lead to the f... more Sulphur is an essential element for aquatic biosystems, the life processes of which lead to the formation of low molecular weight S compounds in the water. The results of our calculations indicate a pronounced tendency for Hg(II) to form HgS (or HgOHSH) and Hg(SR)2 complexes in the presence of H2S and thiols. Likewise, McHg will form CH3HgSH and CH3HgSR complexes,
Wiley-VCH Verlag GmbH eBooks, Dec 27, 2007
Deep-sea research, Apr 1, 1983
The role of humic substances and total organic carbon in the Southern Ocean biogeochermistry
Analytica Chimica Acta, 1985
ABSTRACT The acid-base properties of aquatic fulvic acid, concentrated from the Göta River, were ... more ABSTRACT The acid-base properties of aquatic fulvic acid, concentrated from the Göta River, were studied by means of potentiometri titrations. The forward and reverse titrations exhibited hysteresis, which decreased as the fulvic acid underwent repeated titration. A simple model based on six titratable groups, within the pH range 2.5–10.4, could explain the acid-base properties. Electrostatic polymeric effects and heterogeneity of the fulvic acid (i.e., a distribution of constants rather than a set of distinct constants) were not included in the model. It was found that the three most acidic groups were carboxylic.
Dissolved humic substances and their chemical construents in the marine nitrogen and carbon cycle... more Dissolved humic substances and their chemical construents in the marine nitrogen and carbon cycles of Arctic waters
Water Research, Apr 1, 1988
ABSTRACT
Marine Chemistry, Aug 1, 1988
In a recent paper, van den Berg and Rogers proposed a two-point potentiometric method for estimat... more In a recent paper, van den Berg and Rogers proposed a two-point potentiometric method for estimating the alkalinity of estuarine waters. There are several problems associated with the application of such methods. Potential users should consider these problems before they finally decide whether a one-or two-point method or an alkalinity titration is the suitable choice. The purpose of this note is to discuss errors that can be expected if the procedure of van den Berg and Rogers is used. Some of these errors can be decreased by proper correction, while others are more difficult to compensate for.
Analytica Chimica Acta, 1987
... The influence of fluoride and sulphate on buffers usef for the determination of the pH and sp... more ... The influence of fluoride and sulphate on buffers usef for the determination of the pH and speciation of protolytes in seawater. ... of 0.7 M is quite different from the lowsalinity NBS buffers with an ionic strength of less than 0.1 M, and because it is desirable to make very precise pH ...
Chemosphere, Feb 1, 2011
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
Springer eBooks, Nov 23, 2005
The degree of binding of calcium to aquatic fulvic acid from the Göta River was estimated from po... more The degree of binding of calcium to aquatic fulvic acid from the Göta River was estimated from potentiometric titrations. A pH-glass electrode and a calcium-selective electrode were used to monitor the free concentrations of the competing, central ions. The ionic strength and the temperature were maintained constant at 0.1 M and 25°C. The total concentration of fulvic acid was maintained
Analytica Chimica Acta, May 1, 2001
Analysis of three-dimensional fluorescence spectra has proved to be a valuable tool in the charac... more Analysis of three-dimensional fluorescence spectra has proved to be a valuable tool in the characterisation of fluorescent dissolved organic matter (FDOM). Application of multivariate methods is a development that further enhances the capabilities of fluorescence spectroscopy for qualitative as well as quantitative analysis. In this work, principal component analysis (PCA) and partial least squares regression (PLS) are applied on fully corrected excitation-emission matrices (EEMs). The relation between sampling site and fluorescence properties in a coastal environment is analysed with PCA and PLS. The applicability of fluorescence spectroscopy and multivariate analysis for the evaluation of properties of humic substances (HS) is discussed.
Analytica Chimica Acta, 1986
ABSTRACT
Marine Chemistry, May 1, 1978
A Dead Sea brine (DSB) has a salinity of 250 g/kg and an entirely different ionic balance than st... more A Dead Sea brine (DSB) has a salinity of 250 g/kg and an entirely different ionic balance than standard seawater (SSW) by loss of sodium chloride, calcium sulfate and small amounts of calcium carbonate and gain of magnesium, calcium and potassium chlorides (see Table I).
Deep Sea Research Part B. Oceanographic Literature Review, 1982
On the evaluation Alkalinity. Non-linear curve-fitting of potentiornetric titrations Potentiometr... more On the evaluation Alkalinity. Non-linear curve-fitting of potentiornetric titrations Potentiometric titration pH scales Seawater of seawater with hydrochloric acid Alcalinité Ajustement de courbe non linéaire Titrage potentiométrique Échelles de pH Eau de mer
Journal of Solution Chemistry, 1980
The stability constant K1 of the equilibrium NH3 + H + ~ NH + was determined by potentiometric ti... more The stability constant K1 of the equilibrium NH3 + H + ~ NH + was determined by potentiometric titration in synthetic seawaters of 5 to 40~oo (per mille) salinity and sodium chloride solutions between 0.2 and 0.7 M ionic strength at temperatures of 5, 15 and 25~ Moreover, K1 was determined in sulfate-free seawater of 35~oo salinity and 25~ The dependence of log Kz on salinity (or ionic strength) and temperature can be reasonably well described by Hnear relations. The K~ obtained for sulfate-free seawater agrees very well with earlier experimental results and theoretical predietions. From the measured K1 and literature data on the equilibrium NH3(atm) ~-NH3(aq., NaCl), the atmospheric concentration of ammonia at equilibrium with seawater was estimated.
The journal of automatic chemistry, 1981
Marine Chemistry, Apr 1, 1982
The dependence of the total carbonate concentration of ocean water on temperature and atmospheric... more The dependence of the total carbonate concentration of ocean water on temperature and atmospheric partial pressure of carbon dioxide is calculated. The results show that the increase in total carbonate caused by the increase of carbon dioxide in the atmosphere is ca. 25-50 times larger than the precision in the experimental determination of Ct.
Marine Chemistry, Apr 1, 1989
Deep-sea Research Part I-oceanographic Research Papers, Nov 1, 2007
The purpose of the work presented in this paper was to study the components of fluorescent organi... more The purpose of the work presented in this paper was to study the components of fluorescent organic matter (FOM) resulting from multi-way decomposition of excitation-emission matrices (EEMs) and to find out how their relative distributions and amounts were affected by the changing hydrography and productivity in the Southern Ocean. Data were collected during the austral summer 97/98 along the 61E meridian covering the area between the spring ice edge and the Subtropical Front. By multiway PARAllel FACtor (PARAFAC) analysis, fluorescence EEMs could be decomposed into components that could be used for relative quantification. It is shown that three components suffice to model the fluorescence in this specific region. Two of the components obtained were protein-like and directly related to in-situ production/degradation; they were correlated with chlorophyll a, and were found to mix down to the core of the Antarctic intermediate water (AAIW) in the Subtropical Front. One component was classified as UV/Visible humic-like and showed a distribution that was very closely related to the qsu-calibrated fluorescence, i.e. indicative of terrestrial input, and of long term processes in the ocean. We suggest that the UV/Visible humic-like component consists of refractory material that is not produced or degraded significantly. It is concluded that a small number of components from PARAFAC analysis were satisfactory representatives of the major types of UV-blue fluorescent structural units present. The qualitative and quantitative results from the PARAFAC model also correlated well with other chemical and physical parameters.
Water Air and Soil Pollution, Apr 1, 1991
Sulphur is an essential element for aquatic biosystems, the life processes of which lead to the f... more Sulphur is an essential element for aquatic biosystems, the life processes of which lead to the formation of low molecular weight S compounds in the water. The results of our calculations indicate a pronounced tendency for Hg(II) to form HgS (or HgOHSH) and Hg(SR)2 complexes in the presence of H2S and thiols. Likewise, McHg will form CH3HgSH and CH3HgSR complexes,
Wiley-VCH Verlag GmbH eBooks, Dec 27, 2007
Deep-sea research, Apr 1, 1983