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Salinity Effects on Iron Speciation in Boreal River Waters

Herzog, Simon D. LU ; Persson, Per LU and Kritzberg, Emma S. LU (2017) In Environmental Science and Technology 51(17). p.9747-9755
Abstract

Previous studies report high and increasing iron (Fe) concentrations in boreal river mouths. This Fe has shown relatively high stability to salinity-induced aggregation in estuaries. The aim of this study was to understand how the speciation of Fe affects stability over salinity gradients. For Fe to remain in suspension interactions with organic matter (OM) are fundamental and these interactions can be divided in two dominant phases: organically complexed Fe, and colloidal Fe (oxy)hydroxides, stabilized by surface interactions with OM. The stability of these two Fe phases was tested using mixing experiments with river water and artificial seawater. Fe speciation of river waters and salinity-induced aggregates was determined by... (More)

Previous studies report high and increasing iron (Fe) concentrations in boreal river mouths. This Fe has shown relatively high stability to salinity-induced aggregation in estuaries. The aim of this study was to understand how the speciation of Fe affects stability over salinity gradients. For Fe to remain in suspension interactions with organic matter (OM) are fundamental and these interactions can be divided in two dominant phases: organically complexed Fe, and colloidal Fe (oxy)hydroxides, stabilized by surface interactions with OM. The stability of these two Fe phases was tested using mixing experiments with river water and artificial seawater. Fe speciation of river waters and salinity-induced aggregates was determined by synchrotron-based extended X-ray absorption fine structure (EXAFS) spectroscopy. The relative contribution of the two Fe phases varied widely across the sampled rivers. Moreover, we found selective removal of Fe (oxy)hydroxides by aggregation at increasing salinity, while organically complexed Fe was less affected. However, Fe-OM complexes were also found in the aggregates, illustrating that the control of Fe stability is not explained by the prevalence of the respective Fe phases alone. Factors such as colloid size and the chemical composition of the OM may also impact the behavior of Fe species.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Environmental Science and Technology
volume
51
issue
17
pages
9 pages
publisher
The American Chemical Society
external identifiers
  • scopus:85028961483
  • wos:000410255800036
ISSN
0013-936X
DOI
10.1021/acs.est.7b02309
language
English
LU publication?
yes
id
42888a88-1498-49ee-bc2f-3d9442eb68d1
date added to LUP
2017-09-26 11:05:51
date last changed
2018-01-16 13:26:37
@article{42888a88-1498-49ee-bc2f-3d9442eb68d1,
  abstract     = {<p>Previous studies report high and increasing iron (Fe) concentrations in boreal river mouths. This Fe has shown relatively high stability to salinity-induced aggregation in estuaries. The aim of this study was to understand how the speciation of Fe affects stability over salinity gradients. For Fe to remain in suspension interactions with organic matter (OM) are fundamental and these interactions can be divided in two dominant phases: organically complexed Fe, and colloidal Fe (oxy)hydroxides, stabilized by surface interactions with OM. The stability of these two Fe phases was tested using mixing experiments with river water and artificial seawater. Fe speciation of river waters and salinity-induced aggregates was determined by synchrotron-based extended X-ray absorption fine structure (EXAFS) spectroscopy. The relative contribution of the two Fe phases varied widely across the sampled rivers. Moreover, we found selective removal of Fe (oxy)hydroxides by aggregation at increasing salinity, while organically complexed Fe was less affected. However, Fe-OM complexes were also found in the aggregates, illustrating that the control of Fe stability is not explained by the prevalence of the respective Fe phases alone. Factors such as colloid size and the chemical composition of the OM may also impact the behavior of Fe species.</p>},
  author       = {Herzog, Simon D. and Persson, Per and Kritzberg, Emma S.},
  issn         = {0013-936X},
  language     = {eng},
  month        = {09},
  number       = {17},
  pages        = {9747--9755},
  publisher    = {The American Chemical Society},
  series       = {Environmental Science and Technology},
  title        = {Salinity Effects on Iron Speciation in Boreal River Waters},
  url          = {http://dx.doi.org/10.1021/acs.est.7b02309},
  volume       = {51},
  year         = {2017},
}