Macrophytes Lemna

Huber, W., V. Schubert, and C. Sautter. 1982. Effects of pentachlorophenol on the metabolism of the aquatic macrophyte Lemna minor L. Environ. Pollut. 29A 215-223. 

Environment Canada (1999) Biological test method Test for measuring the inhibition of growth using the freshwater macrophyte, Lemna minor, Environmental Protection Service, Report EPS l/RM/37, Ottawa, ON, 98 pp. 

Hanson ML, Sibley PK, Mabury SA, Muir DCG, Solomon KR. 2003b. Field level evaluation and risk assessment of the toxicity of dichloracetic acid to the aquatic macrophytes Lemna gibba, Myriophyllum spicatum, and Myriophyllum sibericum. Ecotoxicol Environ Safety 55 46-63. 

Environment Canada (1999) Test for Measuring the Inhibition of Growth using the Freshwater Macrophyte Lemna minor, EPS l/RM/37. Environment Canada, Ottawa, Ontario. 

Recent reports on biosorbents based on diverse types of macrophytes are found widely in the literature. Free-floating aquatic plants from the genera Salvinia, Azolla, Eichhornia, Lemna, and Pistia have been described the most. S. natans biomass was able to uptake As(V) at low initial concentrations from 0.25 to 2 mg/L (74.8% and 54%, respectively). The experimental data fitted well to both Langmuir and Freundlich isotherms. The effect of pH and biomass quantities on sorption rate has also been investigated along with some metabolic parameters.105... 

There is virtually no literature describing bioconcentration of organic compounds by wild aquatic macrophytes in spite of the facts that these plants are often the major primary producers in shallow inland waters, and are essential habitat components for both aquatic and terrestrial animals. Lockhart et al. (14) provided a regression equation describing uptake curves for a variety of organic compounds by duckweed (Lemna minor) cultures in laboratory exposures. Predictions from the regression equation agreed quite well with field observations on bioconcentration of permethrin in outdoor ponds (15). 

The intent of this study was to derive rate constants describing uptake and depuration of some forest pesticides using fish (rainbow trout, Salmo gairdneri) and an aquatic macrophyte (duckweed, Lemna minor) in laboratory tests. Since some formulations of forest pesticides also contain solvents of petroleum distillates, experiments were also carried out with a hydrocarbon, fluorene, which is a component of fuel oil (16). 

If the chemical composition of the samples is known or at least partly known (in a stepwise TIE approach) or existing data allow for QSAR calculation, the samples can be ranked by TUs. Arts et al. (2006) studied, in 12 outdoor ditch mesocosms, the effects of sequential contamination with 5 pesticides in a regression design. They applied dosages equivalent with 0.2%, 1%, and 5% of the predicted environmental concentration (PEC) subsequently over 17 weeks. Endpoints recorded over 30 weeks included community composition of macroinvertebrates, plankton, and macrophytes, and leaf litter decomposition as functional ecosystem parameters. TUs were calculated in relation to acute toxicity data for the most sensitive standard species Daphnia magna and Lemna minor. Principal response curves (PRCs), a special form of constrained PCA, and Williams test (NOEC, class 2 LOEC) were used to identify the most sensitive taxa. Next to direct effects on certain species, also indirect effects, for example, how the change in abundance of a sensitive species affects the abundance of another, more tolerant species, can be detected only in mesocosm or in situ experiments. All observed effects were summarized in effect classes in a descriptive manner. 

---