Registration Dossier

Environmental fate & pathways

Adsorption / desorption

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Adsorption to soil, sediment and sewage sludge (OECD 106): 680-697 L/kg at 20 °C

Below, no value for KOC / log KOC is given. This is because partitioning of cationic surfactants to soil and sediment is governed by ionic interaction (no correlation with organic carbon content of soil). Calculation of the environmental partitioning based on Koc alone would therefore result in erroneous predictions. For this reason, instead of Koc compartment specific values for Kd (or Kp) are given and used to calculate the distributrion in the environment.

Key value for chemical safety assessment

Other adsorption coefficients

Type:
log Kp (solids-water in soil)
Value in L/kg:
2.843
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in suspended matter)
Value in L/kg:
2.843
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in sediment)
Value in L/kg:
2.843
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in raw sewage sludge)
Value in L/kg:
2.833
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in settled sewage sludge)
Value in L/kg:
2.833
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in activated sewage sludge)
Value in L/kg:
2.833
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in effluent sewage sludge)
Value in L/kg:
2.833
at the temperature of:
20 °C

Additional information

Slangen (2000) studied the adsorption behaviour of 1-14C-labelled n-octadecylamine in a batch equilibrium experiment according OECD 106. Two soils collected in UK (Cranfield 164 soil, 21.8% clay, 6.6% organic matter, silt loam; Cranfield 266 soil, 50.2% clay, 2.6% organic matter, clay), one sediment collected in The Netherlands (18.7% clay, 4.1% organic matter, silt loam) and a sewage sludge (45.9% clay, 51.9% organic matter, silty clay) were used. The adsorption isotherms determined by Slangen (2000) are non-linear.The distribution constants for soils and sediment decrease dramatically as the concentrations decrease.Apparently extrapolation to low concentrations would lead to unrealistically low results. Following the approach suggested by Danish EPA (2004) data originating from the 2 lowest measured concentrations are used to calculate Kd. Because there is no principal difference between soil and sediments with respect to the sorption properties, as a worst case approach the mean value for sediment obtained at the two lowest equilibrium concentrations (707 and 687 L/kg) is also used for soils and suspended particles.

For the adsorption onto sludge, values of 687 and 674 L/kg were determined for the 2 lowest concentrations. The mean value (680 LL/kg) is used for the exposure calculation.

With a Kpsuspof 697 L/kg and a concentration of 15 mg/L suspended matter in surface waters, the adsorbed fraction is calculated as 1.0%.

Reference:

Danish EPA (2004): Pesticides Research 63, Scenarios and Model Describing Fate and Transport of Pesticides in Surface Water for Danish Conditions. Appendix D - Uncertainty Analysis of the Registration Model. Version 1.0 May 2004. http://www2.mst.dk/udgiv/publications/2004/87-7614-251-5/pdf/87-7614-252-3.pdf