N. Dirilgen et N. Ince, INHIBITION EFFECT OF THE ANIONIC SURFACTANT SDS ON DUCKWEED, LEMNA-MINOR WITH CONSIDERATIONS OF GROWTH AND ACCUMULATION, Chemosphere, 31(9), 1995, pp. 4185-4196
The growth inhibiting and accumulation effects of sodium dodecyl sulph
ate (SDS) on Lemna minor L. were tested at 1-300 ppm levels both in th
e full-strength and 1/10-diluted Jacob's nutrient media under continuo
us illumination at 26-30 degrees C for a 7-day experimental period. Th
e growth of Lemna minor L. was enhanced by increasing concentrations o
f SDS between 1 and 40 ppm and inhibited thereafter, while no response
was observed when the concentration reached a value of 100 ppm. On th
e contrary, the growth in 1/10-diluted medium was observed to be sligh
tly enhanced up to concentrations of 40 ppm, but more so between 40-80
ppm SDS; exhibiting a sharp inhibition, thereafter. The accumulation
of SDS by Lemna minor L. (expressed on dry weight basis) increased wit
h increasing concentrations of SDS between 1-90 ppm, both in full-stre
ngth aid 1/10-diluted media. The correlation of increasing SDS concent
rations with growth and accumulation were determined by using linear a
nd non-linear regression analysis. The statistical significance of obs
erved differences in full-strength and diluted media were also investi
gated. pH of both full-strength and diluted media at 1-90 ppm of SDS l
evels increased during the test: period and remained constant at highe
r SDS concentrations. This indicated that the biodegradation of SDS ge
nerated the alkaline intermediates in the medium.