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Environmental fate & pathways

Adsorption / desorption

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Administrative data

Endpoint:
adsorption / desorption: screening
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
No guideline study but well performed and well documented. The results of this study can be considered relevant for the substance since this substance will not stay as such present in the terrestrial environment but will release calcium ions and hydroxyl ions. Consequently, any study focussing on the adsorption behaviour of calcium ions in soil can be considered relevant. Although reliable, the study is considered as a supporting study because the endpoint can be waived for "Reaction mass of limestone and dicalcium silicate" as such.

Data source

Reference
Reference Type:
publication
Title:
Partitioning of base cations and sulphate between solid and dissolved phases in three podzolised forest solids.
Author:
Gustafsson, J.P., van Hees, P., Starr, M., Karltun, E. and Lundström, U.
Year:
2000
Bibliographic source:
Geoderma 94: 311-333

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
Principles of method if other than guideline:
In a first series of experiments, the chemical composition of centrifuged soil water from several soil horizons from three different podzolised soils was determined during different sampling occasions. The concentration of exhangeable cations was determined using a BaCl2 extraction.
For this first series of experiments, this IUCLID entry only focusses on the results for Ca obtained from extractions of the B2 horizon of the Hyytiälä soil obtained during 4 sampling occasions.
A second series of experiments included a series of batch equilibrium experiments in which the adsorption and desorption of Ca was studied in B2 horizon of the Hyytiälä soil. In these experiments, 2 g of soil was shaken for 8 days with 20 mL of different solutions with or without added Ca (0.218 mM CaCl2) and increasing pH levels
GLP compliance:
not specified
Type of method:
batch equilibrium method
Media:
soil

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
In the first series of experiments, no test substance was added and the study focussed on exchangeable cations. In the second series of experiments, in some cases CaCl2 was added to investigate adsorption of added Ca to soil particles in batch equilibrium experiments.
Common name: calcium chloride
Radiolabelling:
no

Study design

Batch equilibrium or other method

Analytical monitoring:
yes

Results and discussion

Adsorption coefficientopen allclose all
Type:
Kd
Value:
37.6
Remarks on result:
other: L/kg. Experiment 1, sample 1.
Type:
Kd
Value:
42
Remarks on result:
other: L/kg. Experiment 1, sample 2.
Type:
Kd
Value:
49.1
Remarks on result:
other: L/kg. Experiment 1, sample 3.
Type:
Kd
Value:
5.3
Remarks on result:
other: L/kg. Experiment 1, sample 4.
Type:
Kd
Value:
38
Remarks on result:
other: L/kg. Experiment 2.

Any other information on results incl. tables

Experiment 1:

 

Sample 1:

Sorbed: 22.61 mg Ca/kg

Not-sorbed: 0.60 mg Ca/kg

Kd: 37.6 l/kg

 

Sample 2:

Sorbed: 37.84 mg Ca/kg

Not-sorbed: 0.90 mg Ca/kg

Kd: 42.0 l/kg

 

Sample 3:

Sorbed: 42.48 mg Ca/kg

Not-sorbed: 0.87 mg Ca/kg

Kd: 49.1 l/kg

 

Sample 4:

Sorbed: 11.38 mg Ca/kg

Not-sorbed: 2.14 mg Ca/kg

Kd: 5.3 l/kg

 

Experiment 2:

For this experiment, only a Kd was calculated for that treatment in which 0.218 mM CaCl2 was added to the solution but no HCl was added (i.e., adsorption experiment at soil pH, i.e. at a pH of ca. 5.1).

Sorbed: 29.68 mg Ca/kg

In solution: 0.78 mg Ca/L

Kd: 38.0 l/kg..

Applicant's summary and conclusion

Conclusions:
From the results of this study, Kd values could be calculated for adsorption of Ca to soil particles from the B horizon of a podzolized soil. In a first set of experiments exchangeable Ca2+ was measured in centrifugates of 4 samples of the soil under consideration. These experiments yielded Kd values of 5.3 to 49.1 L/kg. The second set of experiments were batch equilibrium experiments with the B2 horizon of the same soil and different solutions (with or without added CaCl2 and/or HCl). From the results of the experiment with added CaCl2 and without added HCl, a Kd of 38.0 could be calculated, which agrees very well with those from the first set of experiments.