Community Research and Development Information Service - CORDIS

The use of terrestrial model ecosystem to assess environmental risks in ecosystems

The Terrestrial Model Ecosystem (TME) can be used to determine the potential fate and ecological effects of a chemical substance including mixtures of chemicals (test substance) which might be released to a site-specific ecosystem. TMEs consist of encased intact (non-homogenized) soil-cores that are extracted from the site of interest so minimizing the disturbance to the natural vegetation, soil microflora and fauna, and the layering of the soil inside the cores. The size of a soil-core is between 17 and 20 cm in diameter and between 30 and 60 cm in depth. All soil-cores are placed in special containers and kept under temperature-controlled conditions, moisture-controlled conditions, and light-controlled conditions (eg in a greenhouse or growth chamber). Each soil-core is watered via special rain-heads and leachates are sampled at the bottom of each core. The measured effect end-points include parameters that describe ecosystem functions (eg microbial respiration, enzyme activity, decomposition rate) and ecosystem structures (eg microbial biomass, species composition and abundance of soil fauna, nutrient losses in leachate). The overall fate of the test substance is assessed by measuring end-points such as mass balance, bioconcentration factors and tendency to move through the model ecosystem.

The validated and successfully ring-tested TME method can be used as an instrument of prognosis for the notification of new substances. Furthermore, the TMEs can be applied if the risk assessment of new or existing substances shows that further information is required. Within the notification procedure the benefit for regulatory authorities is to be able to conduct an improved environmental risk assessment for the soil compartment which includes experimental data on ecosystem structure and function; the benefit for the chemical industry is to have a reliable cost basis when discussing a terrestrial-level-2-study with regulatory authorities; further, the industry as well as the regulatory authorities are in a position to evaluate the test results on the basis of agreed assessment rules; last but not least the benefit for the environment can be expected to be a risk reduction for soil contaminations. Also the TME method can be used as an instrument of prognosis for evaluating environmental risks caused by complex contaminants (eg fly ash, sewage sludge) and by genetically modified micro-organisms and it can be used as an instrument of diagnosis for contaminated field sites and for quality control purposes of remediated soils. Finally the TME method can be applied as an instrument in ecological research.

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