Aquatic Geochemistry

, Volume 14, Issue 3, pp 263–288 | Cite as

Increasing Iron Concentrations in UK Upland Waters

  • C. NealEmail author
  • S. Lofts
  • C. D. Evans
  • B. Reynolds
  • E. Tipping
  • M. Neal
Original Paper


Iron distributions in rainfall, streams, soils and groundwaters are described for the Upper River Severn catchment of mid-Wales. Iron is mainly supplied from within-catchment sources with highest concentrations occurring under reducing conditions. Iron concentrations have doubled over the past 20 years (~5.0 μg yr−1 for the forest and ~3.7 μg yr−1 for the moorland). For the forested sites, the gradients are particularly high post-1993. UK rivers/lakes monitored by the UK Acid Waters Monitoring Network show similar increases. Generally, Fe correlates with dissolved organic carbon (DOC). The greatest rates of Fe increase coincide with those for DOC. Thermodynamic modelling using WHAM/Model VI indicates that Fe(III) is mainly in microparticulate form (probably oxyhydroxides) apart from under reducing conditions. It is proposed that Fe increases for surface waters are associated with increased microparticulate Fe(III) due to stabilisation against aggregation by binding of DOM to its surface. The results relate to acidification declines and deforestation leading to land disturbance and wetter conditions within the soil. There will be greater acidification reversal following tree harvesting due to lowering of atmospheric SOx scavenging and this may have resulted in the greater increase in Fe in the later years of the study.


Iron River Acidification Colloids/nanoparticles DOC WHAM 



We are indebted to the UKAWMN for allowing us to use their data, and we thank them for their enthusiasm and openness. Their data show how the UK upland environment is changing rather than opinion and long may the programme continue. We are also grateful to David Cooper for running trend analyses on the UKAWMN dataset.


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Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • C. Neal
    • 1
    Email author
  • S. Lofts
    • 2
  • C. D. Evans
    • 3
  • B. Reynolds
    • 3
  • E. Tipping
    • 2
  • M. Neal
    • 1
  1. 1.Centre for Ecology and Hydrology WallingfordWallingford, OxonUK
  2. 2.Centre for Ecology and Hydrology LancasterLancaster Environment CentreBailrigg, LancasterUK
  3. 3.Centre for Ecology and Hydrology BangorBangor, GwyneddUK

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