Some Advantages of the Duckweed Test to Assess the Toxicity of Environmental Samples

摘要

AbstractIn Germany, wastewater legislation requires all municipal and industrial leachate to be subjected to toxicity tests. However, no phytotoxicity tests using higher plants are currently included among the standard tests. Freshwater microalgae have been used in most phytotoxicity tests and have often been considered as surrogates for higher plants. However, microalgae often do not show the same sensitivity as higher plants and have major disadvantages for the testing of unmodified environmental samples. In the following study, we evaluated the suitability of the giant duckweedSpirodela polyrhizafor assessing the toxicity of a municipal landfill leachate and two leachates of copper mining residue. Duckweed static toxicity tests were performed, and frond number was the endpoint used to calculateEC50values. Symptoms of stress (chlorosis, necrosis, root destruction, and colony breakup) were also recorded. The landfill leachate was toxic withEC50;96hvalues ranging from 1.3 to 2.7 leachate (v/v). Toxicity of the copper slag leachate was largely determined by the elution method used. Leachate obtained using conventional German leaching methods (S4‐eluate) was not toxic to duckweed, whereasEC50values for the pHstat4‐eluate ranged from 3.2 to 4.2 leachate (v/v). The results demonstrate the suitability ofS. polyrhizafor the testing of unmodified wastewater samples and provide further evidence for the addition of a duckweed toxicity test to the standard tests conducted in Germ