| Abstract: | The time course of uptake has been determined for seven poly(oxyethylene) surfactants, and one anionic surfactant (sodium dodecyl sulphate), into the leaves of wheat plants grown in a phytotron. Uptake was relatively rapid during an initial period of 24 h for six of the eight surfactants; after this period, the uptake rate was lower, and total uptake after 48 h was in the range 80-91% for those six surfactants. The other two compounds, sodium dodecyl sulphate and cetostearyl alcohol-22EO condensate (hexadecan-1-ol/octadecan-1-ol ethylene oxide condensate; average number of ethylene oxide units 22) were barely taken up at all. The observed time course for uptake was consistent with a complex process based on more than one rate-determining process. The physical properties of the surfactants are discussed in relation to their observed uptake behaviour. The surfactant deposit areas, measured by microscopy, were concluded to be not particularly relevant in interpreting the uptake results. Uptake was not related to surfactant chain length, but the physical form of the hydrated surfactant on a leaf surface appeared to influence uptake behaviour. |
