Volume 2 (2007): Article 7

The influence of degree of peat decomposition on phosphorus binding forms in fens.

by S. Jordan, S. Velty and J. Zeitz

This article is dedicated to the memory of our very good friend and colleague,
Dr Silke Velty, 07 April 1973 – 14 October 2007.

Published online: 14.10.2007

Summary

Re-wetting of drained fens can release phosphorus, introducing a eutrophication risk for associated aquatic ecosystems. Characterisation of the different forms of organic and inorganic bound phosphorus in the peat is an important step towards the development of tools for assessing the level of risk attached to individual rewetting projects. In the work reported here, a sequential extraction (fractionation) method was used to distinguish the following P binding forms:
1. labile P, detected by NH₄Cl extraction;
2. redox-sensitive P, detected by Na₂S₂O₄/NaHCO₃ extraction;
3. P adsorbed to metal oxides, detected by HCl extraction;
4. P bound to humic substances, detected by NaOH extraction; and
5. organic and refractory bound P, detected using H₂SO₄ and H₂O₂.
Special attention was paid to the degree of decomposition (DPD) of the peat, and metal concentrations were measured in selected fractions. Higher P concentrations were found in completely humified than in little humified peat for all fractions except the NH₄Cl (labile P) fraction, where P content increased as DPD decreased. As only 1% of total phosphorus (TP) was present as labile P, the results indicate that the decisive horizons for nutrient release after re-wetting are those that are completely humified due to pedogenetic changes. The principal metal sorption partner for P was Fe.

Citation

Jordan, S., Velty, S. & Zeitz, J. (2007): The influence of degree of peat decomposition on phosphorus binding forms in fens. Mires and Peat 2: Art. 7. (Online: http://www.mires-and-peat.net/pages/volumes/map02/map0207.php)

Reviewers

IMCG and IPS acknowledge the work of the reviewers.