Environmental Test Procedures
For one view of this test, see Lewis, Michael A. (1995) "Use of
Freshwater Plants in Phytotoxicity Testing: A Review." Environ.
Foliar exposure and incorporation of test substances into
sediments are also contemplated for future EPA testing in
"A Sediment Toxicity Method Using Lemna Minor, Duckweed" a poster presentation (Society of Environmental Toxicology and Analytical Chemistry meeting, Nashville, Tennessee, November, 2000) by Lazorchak, J.M., Williams, D.E., Suszcynsky-Meister, E.M. and Smith, M.E., U.S. EPA and SBI Environmental, Cincinnati, OH.
"A sediment toxicity method using Lemna minor (duckweed). We developed a Lemna minor sediment toxicity test method to assess sediment contaminants which may affect plants. In addition to the duckweed method, sediments were also tested using a miniaturized freshwater amphipod method and a fathead minnow embryo/ larval (FHM) survival test. Of the three endpoints used in duckweed tests, results indicated that chlorophyll a was a more sensitive measure than either frond number or wet weight. A sediment reference toxicant method has been developed for KCl and Atrazine. The duckweed method is convenient to use and provides an additional sediment toxicity indicator."
"The endpoints for the test are frond number and frond dry weight at the end of a 7-day toxicity test. Procedures are given for culturing L. minor in the laboratory. General or universal conditions and procedures are outlined for testing various substances for their effects on Lemna growth. Additional conditions and procedures are stipulated, which are specific for testing samples of chemical, effluent, elutriate, leachate, or receiving water. Instructions and requirements are included on apparatus, facilities, handling and storing samples, preparing test solutions and initiating tests, specific test conditions, appropriate observations and measurements, endpoints, methods of calculation, validation, and the use of reference toxicants."
This method is written in English and includes a very valuable list of definitions. For example, frond and frond number:
Frond is an individual leaf-like structure on a duckweed colony. It is the smallest unit,
(i. e. individual) capable of reproducing.
3.19 Frond number
According to this standard all fronds protruding from a mother frond which is directly
visible without magnification from above.
"Image processing for biology" Matthias Eberius of LemnaTec writes, "We have developed a computerized image analysis system for the Lemna growth inhibition test (as standardized by ASTM, OECD and soon by ISO). The core of the LemnaTec Scanalyzer is software to quantify Lemna images, including their number, color, frond area and other measures. The system provides GLP-compliant documentation and will support the overall management of the bioassay. The use of this system raises data quality and reduces the costs of measurement and documentation. For cost-effective and flexible use, our clients can choose from purchase of the complete system or image analysis service on a confidential fee-for-service basis. High quality digital images may be sent to us via the Internet for analysis, which eliminates the need for purchase of a complete system. Tools for analysis of other bioassays are also available."
Duckweed FAQ Reports
"The Lemna-Test is the most standardized test using higher plants in bio testing. Till present it is applied mainly for testing of chemicals (OECD-REVISED DRAFT DOCUMENT 221) and sewage water (ISO/WD 20079, DIN-Normung) for possible adverse effects on higher plants."
Reports on the following topics are available online in Adobe Acrobat format
Answers to other frequently-asked questions and other topics also are available
- Comparison of the sensitivity algae vs. Duckweed: A simulation study
- Duckweed growth inhibition tests and standardisation
- Using the Duckweed Growth Inhibition Test to detect and evaluate soil contamination
- Observation Parameters of the Duckweed Growth Inhibition Test Frond number - Total Frond Area - Dry weight
- Observation Parameters in the Duckweed Growth Inhibition Test: The Colour of duckweed
[ link ].
Lemnatec GmbH invites potential clients to send images from their own Lemna growth inhibition bioassays for sample analysis.
Airborne Monitoring of Duckweed
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Revised: August 13, 2013