Importance of dissolved organic matter produced by duckweed (Lemna minor) in a southern English river

SUMMARY. 1. The quantity of dissolved organic carbon (DOC) released by axenic Lemna minor cultures in the laboratory has been determined by an absolute method and by 14C labelling. 2. Good agreement was obtained between the two methods and from 1.1% to 2.6% of the total carbon fixed was released. 3. The DOC produced by L. minor has been analysed by ultrafiltra- tion and compared with a similar analysis of DOC in natural river water. 4. The results of ullrafiltration analyses indicate that the proportion of low molecular weight (<1000 Daltons) material in DOM produced by axenic L. minor is significantly greater than is found in its natural habitat.

[1]  D. Orr,et al.  Distribution of epiphytic bacteria on freshwater plants , 1986 .

[2]  T. Ford,et al.  A temporal study of colloidal and dissolved organic carbon in rivers: apparent molecular weight spectra and their relationship to bacterial activity , 1985 .

[3]  R. Hough,et al.  Photosynthesis, photorespiration, and productivity in Lemna minor L.1 , 1985 .

[4]  W. McDowell,et al.  Sources and molecular weight of "dissolved" organic carbon in an oligotrophic lake , 1984 .

[5]  Cathy M. Tate,et al.  The Effects of Watershed Disturbance on Dissolved Organic Carbon Dynamics of a Stream , 1983 .

[6]  J. Meyer,et al.  Leaf-shredding insects as a source of dissolved organic carbon in headwater streams. , 1983 .

[7]  J. Meyer,et al.  Seston and Dissolved Organic Carbon Dynamics in a Southern Appalachian Stream , 1982 .

[8]  A J Stewart,et al.  Measuring chlorophyll a and C-labeled photosynthate in aquatic angiosperms by the use of a tissue solubilizer. , 1982, Plant physiology.

[9]  C. Dahm.  Pathways and Mechanisms for Removal of Dissolved Organic Carbon from Leaf Leachate in Streams , 1981 .

[10]  J. Baker,et al.  Estimation of the growth rates of epiphytic bacteria and Lemna minor in a river , 1979 .

[11]  C. McLay.  The effect of pH on the population growth of three species of duckweed: Spirodela oligorrhiza, Lemna minor and Wolffia arrhiza , 1976 .

[12]  C. D. Baker,et al.  Improved methods for the measurement of dissolved and particulate organic carbon in fresh water and their application to chalk streams , 1974 .

[13]  H. Casey,et al.  The chemical composition and flow of the River Frome and its main tributaries , 1973 .