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Environmental fate & pathways

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ADSORPTION/DESORPTION BEHAVIOUR OF SAS

Table 4.yyy summarizes the sorption constants Kd for 5 soils, 1 sediment and 1 sludge measured in OECD106 Batch tests.These Kd values are low which means that adsorption of SAS to solids is moderate.Due to the much higher organic carbon content of the sludge a higher Kd is observed.

Table 4.yy Adsorption constants Kd of SAS for different solid matrices

 

Soil 1

Soil 2

Soil 3

Soil 4

Soil 5

Soil average

Sediment

Sludge

 

 

 

 

 

 

 

 

 

Organic carbon (%)

3.3

2.4

3.3

1.4

4.4

3.0

0.3

37

 

 

 

 

 

 

 

 

 

Kd (L/kg)

50

56

35

20

75

47

23

208

VOLATILITY OF SAS (HENRY'S LAW CONSTANT HLC)

The HLC of SAS can be calculated e.g. from vapour pressure (IUCLID Section 4.6) water solubility (IUCLID Section 4.8). The Exposure assessment tool EUSES 2.1 recalculates the HLC of 9.8*E-7 Pa*m3*mol-1at 25 degree C to 4.7*E-7 Pa*m3*mol-1at the environmental temperature of 12 °C. The dimensionless air-water partitioning coefficient is calculated to 3*E-10 m3/m3. The HLC shows that volatilisation of SAS from aqueous solutions can be neglected..