The impact of bioturbation by small mammals on heavy metal redistribution in an embanked floodplain of the River Rhine

S. Wijnhoven, I. Thonon, G.D. Velde, R. Leuven, M. Zorn, H.J.P. Eijsackers, T. Smits

Research output: Contribution to journalArticleAcademicpeer-review

21 Citations (Scopus)

Abstract

Floodplains along large European rivers are diffusely polluted with heavy metals due to emissions in the past. Because of low mobility of heavy metals in floodplain soils and improvements of water quality, these pollutants will remain in place, and can gradually become covered with less contaminated sediments. Bioturbators, especially earthworms, can play an important role in the mixing and surfacing of contaminated substrate. Surfaced substrate can be redistributed by recurrent flooding events, even to areas outside the floodplain. The question remained to what extent bioturbation by small mammals contributes to the redistribution of heavy metals from river sediments in floodplains. Extensive fieldwork on bioturbators such as voles, moles and earthworms and their distribution patterns, as well as on sediment deposition and bioturbation, was conducted at the `Afferdensche en Deestsche Waarden¿ floodplain over the years 2001¿2003. Field data were combined with data of experiments in field enclosures and substrate columns to calculate the amounts of sediment and heavy metals (Zn, Cu, Pb and Cd) redistributed during the floods as well as on an annual basis. Moles and voles surfaced considerable amounts of substrate and heavy metals, but not as much as earthworms which contribute a substantial proportion of the total deposition and redistribution during floods. Although the impact of moles and voles on the redistribution during floods was only locally important, on an annual basis the bioturbation activity of especially moles in floodplains cannot be neglected. The annual amounts of substrate and heavy metals surfaced by all investigated bioturbators were even larger than the total amounts of substrate and heavy metals deposited during floods
Original languageEnglish
Pages (from-to)183-210
JournalWater Air and Soil Pollution
Volume177
Issue number1-4
DOIs
Publication statusPublished - 2006

Keywords

  • ecological risk-assessment
  • spatial variability
  • soil
  • sedimentation
  • earthworms
  • grassland
  • profile

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