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

摘要

Seed germination tests measure soil toxicity directly, while root elongation tests consider the indirect effects of water-soluble constituents which may be present in site-samples. In the seed germination toxicity test, site-soil is mixed with a reference soil to yield 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. Root elongation tests evaluate site-soil eluates. Here seeds are placed onto moistened filter paper which lines Petri dish exposure chambers; exposure chambers are then covered and incubated in complete darkness for five days. Inhibition of root elongation is calculated as an EC50 (exposure concentration which yields a 50% reduction in root length relative to controls) upon termination of the test.