Sediment contact test

Additional test systems, including sediment contact tests, are currently being researched. These systems are comprised of the following organisms ... 

In the case of whole-sediment toxicity determination, the necessary dilutions can be made with reference sediment material. A standardized method whereby polluted sediments can be diluted with unpolluted sediments for sediment-contact tests is currently being researched (Hoss and Krebs, 2003). Hence, the pT-method is capable of capturing the toxic effects of both soluble and adsorbed contaminants in a given sample, assuming that appropriate toxicity tests (i.e., solid-phase contact tests on whole sediment and tests on porewater or elutriates) are used. 

Test performed according to ISO/DIS 16712 (2003) as a liquid-phase and sediment-contact test. 

Chemical pollutants vs. aquatic ecotoxicological tests vs. nematode sediment contact test... 

According to the evaluations of Elbe sediments by raw data of a) aquatic ecotoxicological tests, b) chemical measurements, and c) nematode sediment contact tests in Fig. 3, clustering results by means of all parameters simultaneously (i.e. over the whole property space) for each of the groups and additional partial ordering is shown in Fig. 7. A common characteristic for both chemical and ecotoxicological tests is, that... 

In contrast to the partial orders from chemical concentrations and aquatic ecotoxicological tests, the results of the sediment contact tests with nematodes lead to a total order. This corresponds to a correlation analysis that shows a significant correlation between growth, reproduction and egg hatch (r=0,7). 

Selection Criteria for and Choice of Sediment Contact Tests... 

Toxicity Comparison of the Sediment Contact Tests in Natural Polluted Sediments... 

Sediment contact tests are biological methods for the determination of toxic effects induced by whole sediments in direct contact with test organisms, taking into account all possible pathways of contaminant uptake (particle contact, food, pore water). Sediment contact tests are highly relevant in order for an ecosystem approach to consider the actual bioavailability of contaminants sufficiently. 

However, the above-described fundamental problems (e.g. enviromnental factors, controls, test-phases see Section 6.2.2.) cannot be resolved by further developments of individual tests, but require a comprehensive comparative examination. Such a study should comprise the definition of reference conditions and standardised reference sediments (controls) as the basis for the comparability of several sediment contact tests that are used within one test battery. Further, toxicity thresholds should be defined to assure assessment methods. Meaningful answers to these fundamental questions of sediment risk assessment and classification can be found by pooling research efforts in a joint research project. Such a project is the here described SeKT joint research project (SeKT Sediment Kontakt Test). 

The studies of SeKT have the objective of testing the applicability of sediment contact tests with a possibly wide range of different sediments. This means primarily determining the variabihty of the test results with the aim of improving the reliability of the tests. The project plan comprises i) the application of the sediment contact tests with different sediments in order to identify the influences of natural sediment properties on the test systems ii) the definition of reference conditions, including the standardisation of negative controls iii) the determination of toxicity thresholds for the individual sediment contact tests. Further, iv) the test systems should be validated with contaminated natural sediments and by means of dose-effect relations with sediment samples that were spiked with selected contaminants. The results obtained within the project should serve as a data base for improved interpretation and evaluation of ecotoxicological sediment analyses. 

A sediment contact test battery as applied in the SEKT project can therefore be used as a tool for sediment monitorina. 

One approach to increase certainty of data has been suggested e.g. by Suter (1983) the use of several lines of evidence in order to make a best-judgement weight of evidence decision. In this context, the application of different biotests with different endpoints, exposure routes and sensitivities towards contaminants could be regarded as different lines of evidence. If such a biotest battery, however, comprises e.g. sediment contact tests as well as elutriate tests, additional information could be drawn from the results on whether potential risks of contaminants are sediment-focused or could also affect organisms in tlie water column upon resuspension. 

Feiler. U.. Ahlf, W., Hoess, S., Hollert, H., Neumann-Hensel, H., Meller, M. et al. (2005) The SeKT joint research project definition of reference conditions, control sediments and toxicity thresholds for limnic sediment contact tests, ESPR - Environ Sci. Pollut. Res., 12(5), pp. 257-258. 

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