Phytotoxicity of some chloroanilines and chlorophenols, in relation to bioavailability in soil
article
Soil adsorption and the effect of four chlorophenols and three chloroanilines on the growth of lettuce (Lactuca sativa) were determined in two soil types differing in organic matter content and pH. Adsorption increased with increasing organic matter content of the soils. Phytotoxicity, based on dosed amounts, was significantly higher in the soil with the low level of organic matter. This difference could be reduced by recalculating the EC<sub>50</sub> values for the effect of the test substances on plant growth in mg kg<sup>-1</sup> dry soil towards concentrations in mg L<sup>-1</sup> pore water using data from soil adsorption experiments. For pentachlorophenol only this recalculation increased rather than decreased the difference between the two soils, however, when the EC<sub>50</sub> values for pentachlorophenol were corrected for the difference in soil pH, almost the same values resulted for both soils. Calculated EC<sub>50</sub> values on the basis of pore water concentrations appeared to be in good agreement with values determined in nutrient solution tests. These results indicate that, for plants, the toxicity and therefore the bioavailability of organic chemicals in soil mainly depend on the concentration in the soil solution, and can be predicted on the basis of sorption data. Attempts to develop QSARs relating log EC<sub>50</sub> values in K(ow)) pore water with lipophilicity (expressed as the octanol/water partition coefficient: log K(ow)) of the test substances resulted in a statistically significant relationship. This relationship was further improved by correcting the chlorophenol data for dissociation effects.
Topics
TNO Identifier
280545
ISSN
00496979
Source
Water, Air, and Soil Pollution, 88(1-2), pp. 119-132.
Publisher
Kluwer Academic Publishers
Place of publication
Dordrecht, Netherlands
Pages
119-132
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