Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 348597
Title Iron and sulphate as possible key factors in the restoration ecology of rich fens in discharge areas
Author(s) Kemmers, R.H.; Delft, S.P.J. van; Jansen, P.C.
Source Wetlands Ecology and Management 11 (2003)6. - ISSN 0923-4861 - p. 367 - 381.
Department(s) Soil Science Centre
Alterra - Centre for Water and Climate
Wageningen Environmental Research
Publication type Refereed Article in a scientific journal
Publication year 2003
Keyword(s) bodemchemie - veengronden - bodemwaterbeweging - calcium - zure gronden - soil chemistry - calcium - acid soils - peat soils - soil water movement
Categories Soil Chemistry
Abstract Seven reference areas in the Netherlandswere selected to trial restoration measuresin acidified rich fens in discharge areas.In about half of the projects the measuresthat aimed to restore the high base statusof the topsoil failed. The aim of thepresent study was to identify the keyfactors and processes in base regulation ofrich fen systems, in order to underpinfuture restoration. We sampled soil andinterstitial water from distinct soilhorizons and analysed it for variablesinvolved in geohydrochemical processes. Wemonitored interstitial water chemistry andredox potentials to calibrate and validatea chemical speciation model, that we usedfor the interpretation of our observations.It appeared that soil pH, Ca2+saturation and iron contents weresignificantly lower at sites whererestoration efforts had failed. At the sametime, soils of these sites were verystratified instead of homogenous. Onlysoils with high iron contents recovered ahigh Ca2+ saturation. All sites werecharacterised by considerable downwardwater fluxes through the soil. Chemicalspeciation modelling was a useful tool forthe interpretation of processes underlyingour observations and helped elucidate thefactors and processes that control therecharge of the CEC by base cations. The modelling results suggested that the mainprocess in proton neutralisation ofsuccessful sites is the production ofinternal alkalinity by reduction of ironoxides. Additional redox capacity can besupplied by the ample presence ofsulphates. From our results we hypothesisethat the CEC will only be rechargedsuccessfully with base cations in thepresence of sufficient redox capacity ofthe soil. It seems that redox processesfacilitate the ionic exchange of protonsfor Ca2+ ions. Sites where restorationefforts failed changed from discharge areasto recharge areas, which caused irondepletion by leaching. We conclude thatproper understanding of the pedological andgeohydrochemical processes that control thebase status of soils is a prerequisite forsuccessful nature restoration. The role ofsoil processes cannot be ignored as itseems that the production of internalalkalinity upon reduction exceeds theexternal supply of alkalinity bygroundwater flow.
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