STP1091: Seed Germination and Root Elongation Toxicity Tests in Hazardous Waste Site Evaluation: Methods Development and Applications

    Linder, G
    NSI Technology Services Corporation, CERL, Corvallis, OR

    Greene, JC
    U.S. Environmental Protection Agency, Environmental Research Laboratory, Corvallis, OR

    Ratsch, H
    U.S. Environmental Protection Agency, Environmental Research Laboratory, Corvallis, OR

    Nwosu, J
    NSI Technology Services Corporation, CERL, Corvallis, OR

    Smith, S
    NSI Technology Services Corporation, CERL, Corvallis, OR

    Wilborn, D
    NSI Technology Services Corporation, CERL, Corvallis, OR

    Pages: 11    Published: Jan 1990


    Abstract

    Techniques modified from methods originally developed in the plant and weed science disciplines have yielded short-term tests that assess toxic chemical effects on plants. The seed germination and root elongation bioassays are laboratory toxicity tests that evolved to assess the direct and indirect soil toxicity of hazardous waste sites. These assessment tools are part of a collection of single-species toxicity tests that evaluate toxicity endpoints (seed germination and root elongation) pertinent to ecological assessments for terrestrial hazardous waste sites. Seed germination tests measure toxicity associated with soils directly, while root elongation tests consider the indirect effects of water-soluble constituents that may be present in site samples. In the seed germination toxicity test, site soil is mixed with a reference soil to yield a logarithmic series of exposure concentrations into which test seeds are planted. Germination is evaluated after a five-day exposure, and effective concentrations associated with a 50% reduction in seed germination are calculated. Contrasted to this direct test of soil toxicity, the root elongation test evaluates soil eluates that are prepared from site samples and contain watersoluble soil constituents potentially available to plants on-site and off-site. For the root elongation test, seeds are placed onto moistened filter paper that lines petri dish exposure chambers. Then, the exposure chambers are covered and incubated in complete darkness for five days; inhibition of root elongation is calculated as an EC50 (exposure concentration that yields a 50% reduction in root length relative to controls) upon termination of the test. By using a variety of plant species and developing a comparative toxicity database, both seed germination and root elongation toxicity tests may be applied on a site-specific basis and contribute to the toxicity assessment required as part of an ecological assessment for a hazardous waste site.

    Keywords:

    seed germination, root elongation, terrestrial toxicity testing, ecological assessment, toxicity assessment, hazardous waste site remediation


    Paper ID: STP19062S

    Committee/Subcommittee: E47.13

    DOI: 10.1520/STP19062S


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