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Widespread Increases in Iron Concentration in European and North American Freshwaters

Björnerås, C. LU ; Weyhenmeyer, Gesa A.; Evans, C. D.; Gessner, Mark O.; Grossart, H. P.; Kangur, K.; Kokorite, I.; Kortelainen, P.; Laudon, H. and Lehtoranta, J., et al. (2017) In Global Biogeochemical Cycles 31(10). p.1488-1500
Abstract

Recent reports of increasing iron (Fe) concentrations in freshwaters are of concern, given the fundamental role of Fe in biogeochemical processes. Still, little is known about the frequency and geographical distribution of Fe trends or about the underlying drivers. We analyzed temporal trends of Fe concentrations across 340 water bodies distributed over 10 countries in northern Europe and North America in order to gain a clearer understanding of where, to what extent, and why Fe concentrations are on the rise. We found that Fe concentrations have significantly increased in 28% of sites, and decreased in 4%, with most positive trends located in northern Europe. Regions with rising Fe concentrations tend to coincide with those with... (More)

Recent reports of increasing iron (Fe) concentrations in freshwaters are of concern, given the fundamental role of Fe in biogeochemical processes. Still, little is known about the frequency and geographical distribution of Fe trends or about the underlying drivers. We analyzed temporal trends of Fe concentrations across 340 water bodies distributed over 10 countries in northern Europe and North America in order to gain a clearer understanding of where, to what extent, and why Fe concentrations are on the rise. We found that Fe concentrations have significantly increased in 28% of sites, and decreased in 4%, with most positive trends located in northern Europe. Regions with rising Fe concentrations tend to coincide with those with organic carbon (OC) increases. Fe and OC increases may not be directly mechanistically linked, but may nevertheless be responding to common regional-scale drivers such as declining sulfur deposition or hydrological changes. A role of hydrological factors was supported by covarying trends in Fe and dissolved silica, as these elements tend to stem from similar soil depths. A positive relationship between Fe increases and conifer cover suggests that changing land use and expanded forestry could have contributed to enhanced Fe export, although increases were also observed in nonforested areas. We conclude that the phenomenon of increasing Fe concentrations is widespread, especially in northern Europe, with potentially significant implications for wider ecosystem biogeochemistry, and for the current browning of freshwaters.

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publication status
published
subject
keywords
Browning, Climate change, Freshwaters, Iron, Trends
in
Global Biogeochemical Cycles
volume
31
issue
10
pages
1488 - 1500
publisher
American Geophysical Union
external identifiers
  • scopus:85031758536
  • wos:000416625200002
ISSN
0886-6236
DOI
10.1002/2017GB005749
language
English
LU publication?
yes
id
660010d3-f417-4569-b1b9-aba8098493cd
date added to LUP
2017-10-31 11:13:08
date last changed
2018-02-18 23:46:27
@article{660010d3-f417-4569-b1b9-aba8098493cd,
  abstract     = {<p>Recent reports of increasing iron (Fe) concentrations in freshwaters are of concern, given the fundamental role of Fe in biogeochemical processes. Still, little is known about the frequency and geographical distribution of Fe trends or about the underlying drivers. We analyzed temporal trends of Fe concentrations across 340 water bodies distributed over 10 countries in northern Europe and North America in order to gain a clearer understanding of where, to what extent, and why Fe concentrations are on the rise. We found that Fe concentrations have significantly increased in 28% of sites, and decreased in 4%, with most positive trends located in northern Europe. Regions with rising Fe concentrations tend to coincide with those with organic carbon (OC) increases. Fe and OC increases may not be directly mechanistically linked, but may nevertheless be responding to common regional-scale drivers such as declining sulfur deposition or hydrological changes. A role of hydrological factors was supported by covarying trends in Fe and dissolved silica, as these elements tend to stem from similar soil depths. A positive relationship between Fe increases and conifer cover suggests that changing land use and expanded forestry could have contributed to enhanced Fe export, although increases were also observed in nonforested areas. We conclude that the phenomenon of increasing Fe concentrations is widespread, especially in northern Europe, with potentially significant implications for wider ecosystem biogeochemistry, and for the current browning of freshwaters.</p>},
  author       = {Björnerås, C. and Weyhenmeyer, Gesa A. and Evans, C. D. and Gessner, Mark O. and Grossart, H. P. and Kangur, K. and Kokorite, I. and Kortelainen, P. and Laudon, H. and Lehtoranta, J. and Lottig, N. and Monteith, D. T. and Nõges, P and Nõges, T and Oulehle, F. and Riise, G. C. and Rusak, J. A. and Räike, A. and Sire, J. and Sterling, S. and Kritzberg, E. S.},
  issn         = {0886-6236},
  keyword      = {Browning,Climate change,Freshwaters,Iron,Trends},
  language     = {eng},
  month        = {10},
  number       = {10},
  pages        = {1488--1500},
  publisher    = {American Geophysical Union},
  series       = {Global Biogeochemical Cycles},
  title        = {Widespread Increases in Iron Concentration in European and North American Freshwaters},
  url          = {http://dx.doi.org/10.1002/2017GB005749},
  volume       = {31},
  year         = {2017},
}