Title: Chronic metal pollution and soil ecological functioning

Primary Researcher: Stefan Kools
Email address: Stefan.Kools@falw.vu.nl
Submitted on: October 3, 2006

Start date: 01 January 2001
End date: 31 January 2005

Introduction:

Ecotoxicological risk assessment often tacitly assumes that protection of species in an ecosystem is a sufficient condition for protection of the functions of that ecosystem. Ecological theory, however, does not yet have a clear answer on the question how the presence of species relates to ecosystem functions.

Aim:

In the present project, the use of terrestrial model ecosystems (TME) is used to allow a direct evaluation of ecological functions of polluted soil. From different sites, covering a broad range of pollution cores are taken and brought to the lab . These are peaty soils chronically contaminated with heavy metals ("toemaakdekken") from the Ronde Venen near Demmerik. The functions are related to assessments using pollution-induced community tolerance (PICT) of two major functional groups in soil, bacteria and nematodes, together withRIVM en Wageningen UR.
By sampling field soils contaminated to different degrees, and comparing their responses both for PICT and for functions, estimates are sought of the threshold concentrations (NECs) of dominant metals that mark responses in the highly sensitive PICT assays and how these concentrations compare to the NECs for soil functions.

Research:

Five classes of functions are addressed: (i) mineralization of nitrogen and other elements, (ii) leaching of low-molecular weight humic substances (phenolic acids), (iii) degradation of added natural substrates, (iv) degradation of added xenobiotics, and (v) susceptibility to additional stress.
The columns are incubated in the laboratory with plants growing on them, and percolated with artificial rain water. A variety of chemical constituents are determined in the leachate while the column is flushed with about three times the pore volume over a period of several weeks.
All functional parameters are measured on individual soil columns and the results are correlated with the level of heavy metals that is present in the soil.

Funding via University

Yes

External Funding Sponsors

NWO -SSEO