Acrylaldehyde

Adsorption / desorption

Description of key information

Based on the calculated and experimental Koc values (Koc=51-270), acrolein is expected to be moderately to highly mobile in soil. However, there are indications that the adsorption of acrolein to soil (bound fraction) is irreversible. 

Additional information

1. European Union Risk Assessment Report of Acrolein (EU, 2001)

Using the measured log Kow of -1.10, a Koc of 2.8 l/kg can be estimated according to the TGD (1996). Experimentally determined Koc-values (dimensionless) were in the range of 51-270 for two different soils, but further details of this study are lacking. Based on the calculated and experimental Koc values, acrolein is expected to be moderately to highly mobile in soil. However, there are indications that the adsorption of acrolein to soil (bound fraction) is irreversible. In a simulation test, assuming the absence of water evaporation, acrolein was found to evaporate for 79% from sandy soil and 47% from loam soil during one year. When the water evaporated simultaneously, 85% of acrolein evaporated for both types of soil. In another experimental study acrolein showed a limited (30% of 0.1% solution) sorption to activated carbon. These experimental results further support the conclusion that acrolein has a low sorption to soil and therefore leaching may occur. However, volatilisation and degradation processes are expected to attenuate movement through soil towards groundwater.

As important details are lacking for the experimentally derived Koc-values, the calculated Koc of 2.8 l/kg will be used throughout the further exposure assessment of acrolein. Kp-values for soil, sediment and suspended matter can subsequently be calculated by multiplying the Koc with the corresponding foc-values, resulting in Kp's of 0.06 l/kg (soil), 0.14 l/kg (sediment) and 0.28 l/kg (suspended matter). It should be kept in mind, however, that the derivation of a Kp from low log Kow-values is less reliable (estimation outside domain).

2. Agreement with further international Reports and Studies published after finalisation of the EU Risk Assessment Report 2001

US ATSDR (2007): Using a linear regression equation based on log Kow data, an adsorption coefficient (Koc) of 24 was estimated, which suggests that adsorption of acrolein to suspended solids and sediments in water would not be significant. This does not take into account the reactivity of acrolein which could lead to the removal of acrolein from water through chemical binding of the compound to dissolved or suspended organics in water and sediments. The relatively low estimated Koc value suggests that acrolein will be highly mobile in soil and that this compound has the potential to leach significantly.

WHO (2002): In the terrestrial environment, acrolein undergoes biodegradation, hydrolysis, volatilization, and irreversible sorption to soil. These processes are expected to significantly decrease the high infiltration rate of acrolein estimated from its low experimental Koc. The overall reactivity-based half-life of acrolein in soil is estimated to be between 30 and 100 h.

3. Substantial disagreements in comparison to further international Reports to European Union Risk Assessment Report 2001

None

4. Additional aspects in further international Reports

None

5. Additional information in newer Studies, not included in the European Union Risk Assessment Report 2001 or further cited international reports

None

6. Conclusions

Based on the calculated and experimental Koc values (Koc=51-270), acrolein is expected to be moderately to highly mobile in soil. However, there are indications that the adsorption of acrolein to soil (bound fraction) is irreversible.