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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Experimental Koc values for thiourea in three soils were determined to be 28.95, 26.13. and 36.49. The mean value (Koc = 30.5) is carried forward to the risk assessment.

Key value for chemical safety assessment

Koc at 20 °C:
30.5

Additional information

The adsorption and desorption of thiourea was determined in a test according to OECD guideline 106 (May 12, 1981). In this test three different soil types with the following characteristics were used:

Soil type Sand [%] Silt [%]  Clay [%]  Organic carbon [%]  Carbonate as CaCO3 [%] pH 
Alfisol 12.9 64.3  19.6  0.76  0.75  7.45 
Spodosol 81.5 10.0  7.2  3.56   - 3.88
Entisol 8.5 68.3 20.6 1.11 5.55 7.9

The results for thiourea adsorption to soil are as follows:

Soil type Adsorption [%] K Koc
Alfisol 5.00 0.22 28.95
Spodosol 17.80 0.93 26.13
Entisol 8.45 0.41 36.49 

The determined K values for thiourea are dependent on soil texture characteristics, pH and content of organic carbon. The mean Koc from the three soil types is carried forward to the risk assessment of thiourea.