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Environmental fate & pathways

Adsorption / desorption

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Description of key information

According to a study performed using  the batch equilibrium method, the substance can be considered qualitatively mobile for all soils tested at soil/solution ratio of 1:2.

Key value for chemical safety assessment

Koc at 20 °C:
9

Additional information

The log Koc of the test substance was performed using the batch equilibrium method according to OECD guideline 106 and GLP. No deviation from the guideline was observed during the study.

Five soils from Ontario, Canada, were used for the test: silty clay loam, loam, sandy loam, clay loam and loamy sand. Solutions of Test Item at 750 mg/L in 0.01M CaCl2 were added to soil samples at a soil/solution ratio of 1:2. The soils were then shaken at 100 rpm for a 24 hour period until adsorption equilibrium was reached. Samples of the aqueous phase were taken at 3, 6, 24 and 48 hours using the serial method and were analyzed by HPLC method. Kd values from a low of 0.33 cm3/g for silty clay loam soil to a high of 2.44 cm3/g for loamy sand soil were found. At a soil/solution ratio of 1:2, Koc values ranged from 9.4 (loamy sand) to 38.44 (sandy loam). The high organic carbon content soils adsorbed more of the substance than the soils containing lower amounts of organic carbon. In general, chemicals with Kd ≤ 1 cm3/g are considered to be qualitatively mobile. The substance can be considered qualitatively mobile for all soils tested at soil/solution ratio of 1:2.

The Koc values are summarised below (for a soil/solution ratio of 1:2):

Soil type

Koc

Silty clay loam

25.2

Loam

17.0

Sandy loam

38.44

Clay loam

25.83

Loamy sand

9.4