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Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
15 August 2007 - 17 September 2008
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study conducted to GLP in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.
Qualifier:
according to guideline
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
batch equilibrium method
Media:
soil
Radiolabelling:
no
Test temperature:
20°C +/- 2°C
Analytical monitoring:
yes
Details on sampling:
- Concentrations:
Preliminary test : Three soil-to-solution ratios = 1/50, 1/25, 1/5; one test item concentration = 0.89 mg/l
Screening test : one soil-to-solution ratio = 1/50; one test item concentration = 1.23 mg/l
- Sampling interval:
Preliminary test : 48 hours
Screening test : adsorption phase: 2, 5, 24 and 48 hours ; desorption phase: 2, 4, 24 and 48 hours
- Sample storage before analysis: before analyses all samples were stabilized by adding 0.5 ml nitric acid to 5 ml supernatant.
Details on matrix:
COLLECTION AND STORAGE
- Geographic location:
Soil I (SI): Hanhofen (Speyer, Rheinland-Pfalz, Germany; latitude 49°19¿N, longitude 08°20¿E). The sampling side was a meadow in the sampling year and at least 4 former years.
Soil II (SII): Attenschwiller (68220 Attenschwiller, France, latitude 47°34¿N, longitude 7°27¿E). The field cover at the time of sampling consisted of weeds.
Soil III (SIII): Siebeldingen (Speyer, Rheinland-Pfalz, Germany, latitude 49°12¿N, longitude 08°03¿E). The sampling site was uncultivated in the sampling year and at least 4 years before.
- Collection procedures: Sampling and handling of the soils were performed under consideration of ISO 10381-6 ¿(Soil Quality-Sampling-Guidance on the collection, handling and storage of soil for the assessment of microbial processes in the laboratory)¿.
- Sampling depth (cm): The three soils were sampled from the top 20 cm layer.
- Storage conditions and length: no data except that SI, SII and SIII were sampled on August 2006, March 2007 and September 2006, respectively.
- Soil preparation: The soils, sieved to 2-mm, were air-dried at room temperature and homogenized. Disaggregation was performed with minimal force, so that the original texture of the soil was changed as little as possible. In order to eliminate microbial degradation of the test item, the soils were sterilized before use by ¿-irradiation (Studer Hard, 4658 Däniken / Switzerland). Thereafter, the soil samples were pre-equilibrated with 50% of the targeted volume of the aqueous phase by shaking for at least 20 hours at 20 °C prior to application of the test item.

PROPERTIES
- Soil texture
% sand: SI = 79.1, SII = 11.8, SIII = 21.9.
% silt: SI = 13.5, SII = 72.8, SIII = 36.0.
% clay: SI = 7.9, SII = 15.4, SIII = 42.
- Horizon: no data.
- Soil taxonomic classification: SI = Loamy sand, SII = Silt loam, SIII = Clay.
- Soil classification system: The soil types above mentioned were determined according to USDA (United States Department of Agriculture).
- Soil series and order: no data.
- pH: SI = 5.6, SII = 7.4, SIII = 7.0.
- Organic carbon (%): SI = 2.36, SII = 0.99, SIII = 1.89.
- CEC (meq/100 g): SI = 11.0, SII = 10.2, SIII = 20.0.
- Nitrogen content (%): SI = 0.21, SII = 0.11, SIII = 0.21.
- Organic matter (%): SI = 4.07, SII = 1.71, SIII = 3.26.
- C/N-ratio: SI = 11.2, SII = 9.0, SIII = 9.0
- Moisture (in g per 100 g dry soil): SI = 0.95, SII = 1.02, SIII = 5.78.
- Other: None of the soils had been fertilised or treated with pesticides for at least 12 months prior to sampling.
No further data.


Details on test conditions:
TEST CONDITIONS
- Buffer: none.
- pH: The pH of the aqueous phase was measured before and after contact with the soil at the soil-to-solution ratio of 1/50. The pH of the CaCl2-solution was 7.05 before contact with the soil and 6.59, 6.85 and 6.89 after contact with soil I to III, respectively.
- Suspended solids concentration: no data.

TEST SYSTEM
- Type, size and further details on reaction vessel: The study was performed in Teflon centrifuge tubes (preliminary test) or glass bottles (screening test).

- Water filtered: No.

- Number of reaction vessels/concentration: All experiments including controls were performed in duplicate.

- Measuring equipment: The concentration of Cerium Carbonate 99.9 Humide in the samples was determined by analysis of dissolved cerium using inductively coupled plasma mass spectroscopy (ICP-MS).

- Test performed in closed vessels (due to significant volatility of test substance) or in open system: No data.

- Method of preparation of test solution, incubation conditions and study conduct:
1) Preparation of the application solution:
Preliminary test: An application solution (AS1) was prepared for the preliminary test by weighing 1.66 mg of the test item and diluting it in 350 mL 0.01 M CaCl2 solution. Its final concentration was calculated to be 0.0036 mg/mL, taking into account the purity of the test item (76.7%, Section 3.1). The application solution was thoroughly mixed before use.
Screening test: An application solution (AS2) was prepared for the screening test in the same way as for the preliminary test only using an amount of 10.22 mg test item in 1500 mL 0.01 M CaCl2 solution. Its final concentration, corrected for purity, was calculated to be 0.0052 mg/mL.

2) Application: After pre-equilibration of the soil with 0.01 M CaCl2 solution, aliquots of the corresponding application solutions were added on the surface of the supernatant using a pipette as described in the table reported in the field ¿Any other information on materials and methods incl. tables¿. Besides the treated samples, controls (duplicates, without soil) and blanks (duplicates, without test item) were subjected to precisely the same steps as the test samples. The control samples checked the stability of the test item in CaCl2 solution whereas the blanks served as a background control during the analysis to detect interfering compounds or contaminated soils. Analysis was only performed for the longest interval (48 hours). All test tubes were shaken briefly by hand, and then mechanically shaken on a rotary shaker in a temperature-controlled room.

3) Test concentrations: for the different parts of the adsorption/desorption test, the following test concentrations were measured by ICP/MS:
Preliminary test: 0.89 mg/L.
Screening test: 1.23 mg/L.

4) Conditions for adsorption/desorption:
Adsorption: All test tubes were shaken horizontally on a rotary shaker at about 150 strokes per minute. The agitation device kept the soil in suspension during shaking. After shaking, the samples were centrifuged (10 minutes at about 2800 or 3000 rpm) and the supernatants decanted into tarred, labelled sample containers. The volumes of the supernatants were determined gravimetrically. At the different sampling intervals, the samples were removed for ICP/MS analysis for determination of the test item concentration. The equilibrium concentration of the test item, and its total amount in the aqueous phase, were calculated based on the results of the analyses. The amount of test item adsorbed onto soil particles was obtained from the difference between the initial and final amount of test item in the aqueous phase.
Desorption: After separation of the soil from the adsorption solution, the same volume of 0.01 M CaCl2 as removed after the adsorption step was added. Thereafter, the mixtures were agitated in the same way as for the adsorption part. The samples were centrifuged and the supernatant analyzed by ICP/MS at the different shaking intervals. The desorption equilibrium concentration of the test item, and its total amount in the aqueous phase, were calculated based on the results of the ICP/MS analyses. The remaining soil water in all samples was determined gravimetrically, and the mass of the test item left over from the adsorption equilibrium and the desorption step, respectively, was calculated.

5) Study conduct:
Preliminary test: The preliminary test was conducted using the three soils and three soil-to-solution ratios (1/50, 1/25 and 1/5) in order to select the optimal soil/solution ratio (for the subsequent screening test), to determine the adsorption of the test item onto the surfaces of the test vessels and the stability of the test item during the test period. A test item concentration of 0.89 mg/L and a sampling time of 48 hours were used. At each sampling interval, duplicate tubes were sampled and the supernatants analyzed by ICP/MS for the test item concentration. Based on the results of the preliminary test and in order to obtain adsorption greater than 50% for any soil (which enables accurate measurements of the test item in the aqueous phase), soil-to-solution ratio of 1/50 was selected for the subsequent screening test.
Mass balance: The mass balance was carried out on all soils directly after the 48-hour adsorption step in the screening test at the soil-to-solution ratio of 1/50 (two tubes per soil). After sampling, the supernatant was removed and the soil was extracted three times, each using 5 mL nitric acid (10%). The extracts resulting from the same tube were combined and analyzed by ICP/MS.
Screening test: The adsorption kinetics were studied using the same soils as used for the preliminary test at the soil-to-solution ratio of 1/50 and a test item concentration of 1.23 mg/L. Additionally, the distribution coefficients KD and KOC were determined after 48 hours of adsorption. After 2, 5, 24 and 48 hours of shaking during the adsorption phase, duplicate tubes were sampled and the supernatants analyzed by ICP/MS. In order to determine whether Cerium Carbonate 99.9 Humide is readily desorbed from soil or not, a desorption experiment was performed directly after the adsorption step using sampling times at 2, 4, 24 and 48 hours.
Computational methods:
The following parameters were calculated using a commercially available Excel computer program:
- A: Percentage of substance adsorbed
- Kd: Distribution coefficient
- D: Percentage of substance desorbed
- Kdes: Desorption coefficient
- Koc: Organic carbon normalized adsorption/desorption coefficient
Type:
Koc
Value:
3 940 404
Type:
log Koc
Value:
6.6
Adsorption and desorption constants:
Adsorption: The Kd values amounted to 11784, 59264 and >100843 mL/g for soils I to III, respectively, with corresponding Koc values of 499332, 5986256 and >5335623 mL/g, respectively.
Desorption: The Kd des values were 10147, 102180, > 225268 mL/g for soils I to III, respectively, with corresponding Koc des of 429968, 10321193 and >11918936 mL/g respectively.
Recovery of test material:
The mass balance showed overall recoveries of 83.6%, 100.9% and 87.4% of the initial amount applied for soils I to III, respectively. Most of the applied test item was found in soil (83.2 to 100.8%). Insignificant amounts (0.4% of applied or less) were detected in the supernatant.
Concentration of test substance at end of adsorption equilibration period:
After addition of 61.6 ¿g Cerium Carbonate 99.9 Humide, 61.33 to 61.56 ¿g were adsorbed to the soils, with only <0.03-0.27 ¿g detected in the supernatant.
Concentration of test substance at end of desorption equilibration period:
The amount of test item desorbed remained low and constant with time, with <0.02% to 1.9% of the adsorbed amount desorbed for all three soils within the 48-hour desorption experiment.
After 48 hours of shaking in the desorption experiment 0.31 ¿g, 0.03 ¿g and <0.01 ¿g was recovered in the desorption solution of soils I to III . In the soils, between 61.03 ¿g and >61.55 ¿g were recovered after the desorption step.
Sample no.:
#1
Duration:
48 h
% Adsorption:
83.6
Sample no.:
#2
Duration:
48 h
% Adsorption:
100.9
Sample no.:
#3
Duration:
48 h
% Adsorption:
87.4
Sample no.:
#1
Duration:
48 h
% Desorption:
0.5
Sample no.:
#2
Duration:
48 h
% Desorption:
0.05
Sample no.:
#3
Duration:
48 h
% Desorption:
< 0.02
Transformation products:
no
Details on results (Batch equilibrium method):
see below table 1 and 2
Statistics:
All calculations were done using the program VALIDATA 3.0 according to DIN 38402-part51.

Table 1: Concentration of  test item in the solid and liquid phases at the end of adsorption equilibration period (mean ± s.d.)

Concentration

Soil 1 (loamy sand)

Soil 2 (silt loam)

Soil 3 (clay)

on soil (µg)

In solution (µg a.i./mL)

% adsorbed

on soil (µg)

In solution (µg a.i./mL)

% adsorbed

on soil (µg)

In solution (µg a.i./mL)

% adsorbed

Control*

1.215  µg a.i./mL in solution ; 98.7% adsorbed

Conc.

(1.23 mg/l)

 61.33

 0.0053

 99.6

 61.54

 0.0012

 99.9

 61.56

 0.0006

 99.9

* control = without soil

Table 2: Concentration of test item in the solid and liquid phases at the end of desorption.

Concentration

Soil 1 (loamy sand)

Soil 2 (silt loam)

Soil 3 (clay)

on soil

(µg)

in solution (µg)

% desorbed as % of the adsorbed

on soil

(µg)

in solution (µg)

% desorbed as % of the adsorbed

on soil

(µg)

in solution (µg)

% desorbed as % of the adsorbed

Conc.

(1.23 mg/l)

 61.03

 0.31

 0.5

 61.51

 0.03

 0.05

 > 61.55

  < 0.01

  < 0.02

Validity criteria fulfilled:
yes
Conclusions:
Dicerium tricarbonate was strongly adsorbed to soil.
Executive summary:

The adsorption/desorption behaviour of the test item, dicerium tricarbonate, on soil was determined using three soils and the batch equilibrium method according to OECD Guideline N°106.

Initially, a preliminary test was performed in order to investigate the adsorption behaviour of dicerium tricarbonate. For this purpose, three soils, a test concentration of 0.89 mg/L and three soil (dry weight) to aqueous phase ratios: 1/50 (1 g/50 mL), 1/25 (1 g/25 mL) and 1/5 (5 g/25 mL) were used. Very high adsorption was observed for all three ratios. After 48 hours of agitation, virtually all of the initial amount of test item was adsorbed (>99%).

Therefore, for the subsequent screening test, the maximum soil-to-solution ratio of 1/50 was selected together with a test item concentration of 1.23 mg/L and the same three soils. The adsorption/desorption kinetics of dicerium tricarbonate were determined after 2, 4 or 5, 24 and 48 hours of agitation. After 2 hours of agitation, adsorption represented 95%, 100% and 100% for soils I to III, respectively. Only low desorption was observed during the 48-hour desorption period (maximum of 2% of test item desorbed for all three soils).

The mass balance was performed during the screening test at the soil to solution ratio of 1/50. The amount of applied test item recovered from the samples represented 83.6%, 100.9% and 87.4% for soils I to III, respectively. Most of the applied amount was extracted from the soils, with only <0.4% of applied detected in the supernatants. The mass balance results confirmed the strong adsorption of dicerium tricarbonate to soil.

The following adsorption/desorption distribution coefficients were obtained for the soils at the selected ratio of 1/50:

- Mean Koc value: 3940404

- Mean Koc, des value: 7556699

Endpoint:
adsorption / desorption: screening
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study conducted on read-across material
Justification for type of information:
Read-across to structurally similar substance Lanthanum oxide.
Reason / purpose for cross-reference:
read-across source
Type:
Koc
Value:
5 480 283
Type:
log Koc
Value:
6.36
Endpoint:
adsorption / desorption: screening
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study conducted on read-across material
Justification for type of information:
Read-across to structurally similar substance Cerium carbonate
Reason / purpose for cross-reference:
read-across source
Type:
Koc
Value:
3 940 404
Type:
log Koc
Value:
6.6
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
15 August 2007 - 13 August 2008
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study conducted to GLP in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.
Qualifier:
according to guideline
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
batch equilibrium method
Media:
soil
Radiolabelling:
no
Test temperature:
20 ± 2 °C
Analytical monitoring:
yes
Details on sampling:
- Concentrations:
Preliminary test: Three soil-to-solution ratios = 1/50, 1/25, 1/5; one test item concentration = 0.64 mg/L
Screening test: One soil-to-solution ratio = 1/50; one test item concentration = 1.29 mg/L
- Sampling interval:
Preliminary test: 48 hours
Screening test: adsorption phase: 2, 5, 24 and 48 hours; desorption phase: 2, 4, 24 and 48 hours
- Sample storage before analysis: before analyses all samples were stabilised by adding 0.5 mL nitric acid to 5 mL supernatant.
Details on matrix:
COLLECTION AND STORAGE
- Geographic location:
Soil I (SI): Hanhofen (Speyer, Rheinland-Pfalz, Germany; latitude 49°19’N, longitude 08°20’E). The sampling side was a meadow in the sampling year and at least 4 former years.
Soil II (SII): Attenschwiller (68220 Attenschwiller, France, latitude 47°34’N, longitude 7°27’E). The field cover at the time of sampling consisted of weeds.
Soil III (SIII): Siebeldingen (Speyer, Rheinland-Pfalz, Germany, latitude 49°12’N, longitude 08°03’E). The sampling site was uncultivated in the sampling year and at least 4 years before.
- Collection procedures: Sampling and handling of the soils were performed under consideration of ISO 10381-6 “(Soil Quality-Sampling-Guidance on the collection, handling and storage of soil for the assessment of microbial processes in the laboratory)”.
- Sampling depth (cm): The three soils were sampled from the top 20 cm layer.
- Storage conditions and length: no data except that SI, SII and SIII were sampled on August 2006, March 2007 and September 2006, respectively.
- Soil preparation: The soils, sieved to 2 mm, were air-dried at room temperature and homogenised. Disaggregation was performed with minimal force, so that the original texture of the soil was changed as little as possible. In order to eliminate microbial degradation of the test material, the soils were sterilised before use by γ-irradiation (Studer Hard, 4658 Däniken / Switzerland). Thereafter, the soil samples were pre-equilibrated with 50 % of the targeted volume of the aqueous phase by shaking for at least 20 hours at 20 °C prior to application of the test material.

PROPERTIES
- Soil texture
% sand: SI = 79.1, SII = 11.8, SIII = 21.9.
% silt: SI = 13.5, SII = 72.8, SIII = 36.0.
% clay: SI = 7.9, SII = 15.4, SIII = 42.
- Horizon: no data.
- Soil taxonomic classification: SI = Loamy sand, SII = Silt loam, SIII = Clay.
- Soil classification system: The soil types above mentioned were determined according to USDA (United States Department of Agriculture).
- Soil series and order: no data.
- pH: SI = 5.6, SII = 7.4, SIII = 7.0.
- Organic carbon (%): SI = 2.36, SII = 0.99, SIII = 1.89.
- CEC (meq/100 g): SI = 11.0, SII = 10.2, SIII = 20.0.
- Nitrogen content (%): SI = 0.21, SII = 0.11, SIII = 0.21.
- Organic matter (%): SI = 4.07, SII = 1.71, SIII = 3.26.
- C/N-ratio: SI = 11.2, SII = 9.0, SIII = 9.0
- Moisture (in g per 100 g dry soil): SI = 0.95, SII = 1.02, SIII = 5.78.
- Other: None of the soils had been fertilised or treated with pesticides for at least 12 months prior to sampling.
No further data.
Details on test conditions:
TEST CONDITIONS
- Buffer: none.
- pH: The pH of the aqueous phase was measured before and after contact with the soil at the soil-to-solution ratio of 1/50. The pH of the CaCl2-solution was 7.05 before contact with the soil and 6.79, 6.90 and 6.87 after contact with soil I to III, respectively.
- Suspended solids concentration: no data.

TEST SYSTEM
- Type, size and further details on reaction vessel: The study was performed in Teflon centrifuge tubes (preliminary test) or glass bottles (screening test).

- Water filtered: No.

- Number of reaction vessels/concentration: All experiments including controls were performed in duplicate.

- Measuring equipment: The concentration of the test material in the samples was determined by analysis of dissolved lanthanum using inductively coupled plasma mass spectroscopy (ICP-MS).

- Test performed in closed vessels (due to significant volatility of test substance) or in open system: No data.

- Method of preparation of test solution, incubation conditions and study conduct:
1) Preparation of the application solution:
Preliminary test: An application solution (AS1) was prepared for the preliminary test by weighing 1.21 mg of the test material and diluting it in 350 mL 0.01 M CaCl2 solution. Its final concentration was calculated to be 0.0034 mg/mL, taking into account the purity of the test material. The application solution was thoroughly mixed before use.
Screening test: An application solution (AS2) was prepared for the screening test in the same way as for the preliminary test only using an amount of 5.05 mg test material in 1500 mL 0.01 M CaCl2 solution. Its final concentration, corrected for purity, was calculated to be 0.0034 mg/mL.

2) Application: After pre-equilibration of the soil with 0.01 M CaCl2 solution, aliquots of the corresponding application solutions were added on the surface of the supernatant using a pipette as described in the table reported in the field “Any other information on materials and methods incl. tables”. Besides the treated samples, controls (duplicates, without soil) and blanks (duplicates, without test material) were subjected to precisely the same steps as the test samples. The control samples checked the stability of the test material in CaCl2 solution whereas the blanks served as a background control during the analysis to detect interfering compounds or contaminated soils. Analysis was only performed for the longest interval (48 hours). All test tubes were shaken briefly by hand, and then mechanically shaken on a rotary shaker in a temperature-controlled room.

3) Test concentrations: for the different parts of the adsorption/desorption test, the following test concentrations were measured by ICP/MS:
Preliminary test: 0.64 mg/L.
Screening test: 1.29 mg/L.

4) Conditions for adsorption/desorption:
Adsorption: All test tubes were shaken horizontally on a rotary shaker at about 150 strokes per minute. The agitation device kept the soil in suspension during shaking. After shaking, the samples were centrifuged (10 minutes at about 2800 or 3000 rpm) and the supernatants decanted into tarred, labelled sample containers. The volumes of the supernatants were determined gravimetrically. At the different sampling intervals, the samples were removed for ICP/MS analysis for determination of the test material concentration. The equilibrium concentration of the test material, and its total amount in the aqueous phase, were calculated based on the results of the analyses. The amount of test material adsorbed onto soil particles was obtained from the difference between the initial and final amount of test material in the aqueous phase.
Desorption: After separation of the soil from the adsorption solution, the same volume of 0.01 M CaCl2 as removed after the adsorption step was added. Thereafter, the mixtures were agitated in the same way as for the adsorption part. The samples were centrifuged and the supernatant analysed by ICP/MS at the different shaking intervals. The desorption equilibrium concentration of the test material, and its total amount in the aqueous phase, were calculated based on the results of the ICP/MS analyses. The remaining soil water in all samples was determined gravimetrically, and the mass of the test material left over from the adsorption equilibrium and the desorption step, respectively, was calculated.

5) Study conduct:
Preliminary test: The preliminary test was conducted using the three soils and three soil-to-solution ratios (1/50, 1/25 and 1/5) in order to select the optimal soil/solution ratio (for the subsequent screening test), to determine the adsorption of the test material onto the surfaces of the test vessels and the stability of the test material during the test period. A test material concentration of 0.64 mg/L and a sampling time of 48 hours were used. After 48 h, duplicate tubes were sampled and the supernatants analysed by ICP/MS for the test material concentration. Based on the results of the preliminary test, the soil-to-solution ratio of 1/50 was selected for the subsequent screening test.
Mass balance: The mass balance was carried out on all soils directly after the 48-hour adsorption step in the screening test at the soil-to-solution ratio of 1/50 (two tubes per soil). After sampling, the supernatant was removed and the soil was extracted three times, each using 5 mL nitric acid (10 %). The extracts resulting from the same tube were combined and analysed by ICP/MS.
Screening test: The adsorption kinetics were studied using the same soils as used for the preliminary test at the soil-to-solution ratio of 1/50 and a test material concentration of 1.29 mg/L. Additionally, the distribution coefficients Kd and Koc were determined after 48 hours of adsorption. After 2, 5, 24 and 48 hours of shaking during the adsorption phase, duplicate tubes were sampled and the supernatants analysed by ICP/MS. In order to determine whether the test material is readily desorbed from soil or not, a desorption experiment was performed directly after the adsorption step using sampling times at 2, 4, 24 and 48 hours.
Computational methods:
The following parameters were calculated using a commercially available Excel computer program:
- A: Percentage of substance adsorbed
- Kd: Distribution coefficient
- D: Percentage of substance desorbed
- Kdes: Desorption coefficient
- Koc: Organic carbon normalized adsorption/desorption coefficient
Type:
Koc
Value:
5 480 283
Type:
log Koc
Value:
6.36
Adsorption and desorption constants:
Adsorption: The Kd values amounted to 5451, 46861 and 216905 mL/g for soils I to III, respectively, with corresponding Koc values of 230978, 4733400 and 11476472 mL/g, respectively.
Desorption: The Kd des values were 15203, 2641, 30858 mL/g for soils I to III, respectively, with corresponding Koc des of 644212, 266724 and 163702 mL/g, respectively.
Recovery of test material:
The mass balance showed overall recoveries of 62.0, 79.1 and 75.9 % of the initial amount applied for soils I to III, respectively. Most of the applied test material was found in soil (62 to 79 %). Insignificant amounts (0.1 % of applied or less) were detected in the supernatant.
Concentration of test substance at end of adsorption equilibration period:
After addition of 64.5 μg of test material, 63.9 to 64.5 μg were adsorbed to the soils, with only 0.01 to 0.59 μg detected in the supernatant.
Concentration of test substance at end of desorption equilibration period:
The amount of test material desorbed remained low and constant with time, with <0.1 to 3.3 % of the adsorbed amount desorbed for all three soils within the 48-hour desorption experiment.
After 48 hours of shaking in the desorption experiment 0.28, 1.23 and 0.54 μg was recovered in the desorption solution of soils I to III. In the soils, between 63.20 and 63.95 μg were recovered after the desorption step.
Sample no.:
#1
Duration:
48 h
% Adsorption:
62
Sample no.:
#2
Duration:
48 h
% Adsorption:
79.1
Sample no.:
#3
Duration:
48 h
% Adsorption:
75.9
Sample no.:
#1
Duration:
48 h
% Desorption:
0.4
Sample no.:
#2
Duration:
48 h
% Desorption:
1.9
Sample no.:
#3
Duration:
48 h
% Desorption:
0.8
Transformation products:
no
Details on results (Batch equilibrium method):
See Tables 1 and 2 below
Statistics:
All calculations were done using the program VALIDATA 3.0 according to DIN 38402-part51.

Table 1: Concentration of the Test Material in the Solid and Liquid Phases at the end of Adsorption Equilibration Period (Mean ± S.D.)

Concentration

(mg/L)

Soil 1 (loamy sand)

Soil 2 (silt loam)

Soil 3 (clay)

On soil (µg)

In solution (µg a.i./mL)

% Adsorbed

On soil (µg)

In solution (µg a.i./mL)

% Adsorbed

On soil (µg)

In solution (µg a.i./mL)

% Adsorbed

Control*

1.238 µg a.i./mL in solution; 96.0 % adsorbed

1.29

63.92

0.0117

99.1

64.43

0.001

99.9

64.49

0.0003

100.0

*Control = without soil

 

Table 2: Concentration of the Test Material in the Solid and Liquid Phases at the end of Desorption.

Concentration

(mg/L)

Soil 1 (loamy sand)

Soil 2 (silt loam)

Soil 3 (clay)

On soil (µg)

In solution (µg)

% Desorbed as % of the Adsorbed

On soil (µg)

In solution (µg)

% Desorbed as % of the Adsorbed

On soil (µg)

In solution (µg)

% Desorbed as % of the Adsorbed

1.29

63.67

0.28

0.4

63.20

1.23

1.9

63.95

0.54

0.8

Validity criteria fulfilled:
yes
Conclusions:
The test material was strongly adsorbed to soil.
Executive summary:

The adsorption/desorption behaviour of the test material on soil was determined using three soils and the batch equilibrium method in accordance with the standardised guideline OECD 106.

Initially, a preliminary test was performed in order to investigate the adsorption behaviour of the test material. For this purpose, three soils, a test concentration of 0.64 mg/L and three soil (dry weight) to aqueous phase ratios: 1/50 (1 g/50 mL), 1/25 (1 g/25 mL) and 1/5 (5 g/25 mL) were used. Very high adsorption was observed for all three ratios. After 48 hours of agitation, virtually all of the initial amount of test material was adsorbed (≥99 %).

Therefore, for the subsequent screening test, the maximum soil-to-solution ratio of 1/50 was selected together with a test material concentration of 1.29 mg/L and the same three soils. The adsorption/desorption kinetics of the test material were determined after 2, 4 or 5, 24 and 48 hours of agitation. After 2 hours of agitation, adsorption represented 96, 100 and 100 % for soils I to III, respectively. Only low desorption was observed during the 48-hour desorption period (maximum of 3 % of test material desorbed for all three soils).

The mass balance was performed during the screening test at the soil to solution ratio of 1/50. The amount of applied test material recovered from the samples represented 62, 79 and 76 % for soils I to III, respectively. Most of the applied amount was extracted from the soils, with only ≤0.5 % of applied detected in the supernatants. The mass balance results confirmed the strong adsorption of the test material to soil.

The following adsorption/desorption distribution coefficients were obtained for the soils at the selected ratio of 1/50:

- Mean Koc value: 5480283

- Mean Koc, des value: 358213

Endpoint:
adsorption / desorption, other
Remarks:
field study
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
reliable with restrictions (Klimisch 2) because samples were taken from a polluted area and because precipitation processes may have been involved in the sediment, resulting in higher log Kp values.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Sediment and pore water samples were collected from two rivers which receive wastewater from urban Hanoi (Vietnam) and analysed for Er and Ce.
GLP compliance:
not specified
Type of method:
other: field study
Media:
sediment
Radiolabelling:
no
Test temperature:
not reported
Analytical monitoring:
yes
Details on sampling:
- Sediment samples collected from To Lich and Kim Nguu rivers, both of which receive wastewater from urban Hanoi, Vietnam. Samples collected from three sites in both rivers with a stainless steel Kajak core sediment sampler equipped with a polymethylmethacrylat inner liner with an inner diameter of 46 mm. Three replicates were collected from each site. Core samples were subdivided into sections 0-10cm, 10-20cm, 20-30cm. Sediment samples were dried at 45°C until constant weight, passed through a 2 mm stainless steel sieve and pulverised in an agate mortar.
- Pore water was extracted from sediment samples: sediment from 0-10cm depth was transferred to polypropylene büchner funnel with 25 µm mesh nylon filter and a minimum of 15 mL pore water was extracted under suction of 10 kPa. Pore water was filtered through a 0.45 µm nylon filter (Millipore) and acidified with 0.1 mL 70% HNO3 (Baker Instra-Analysed).
Details on matrix:
- % organic carbon: 1.2-5.3% in To Lich river samples, 1.8-10.6% in Kim Nguu rivers
- pH of pore water was 7.4-8.1
- redox potential of pore water was -257 to -185 mV
Details on test conditions:
field study
Computational methods:
Partitioning coefficients were calculated by dividing Ce concentration in sediment by Ce concentration in pore water (L/kg).
Key result
Type:
log Kd
Value:
5.41 - 6.23
Matrix:
Sediment-pore water
Remarks on result:
other: Erbium
Type:
log Kd
Value:
5.15 - 7.18
Matrix:
Sediment-pore water
Remarks on result:
other: Ceruim
Details on results (Batch equilibrium method):
Organic matter seemed to have the most important effect on sediment Ce concentrations.
Validity criteria fulfilled:
not specified
Conclusions:
In this study, samples of sediment and pore water were taken along two rivers receiving wastewater from Hanoi, Vietnam, and analysed for Er and Ce. Sediment-pore water for these samples were reported to range from 5.41 to > 6.23 for erbium and 5.15 - 7.18 for cerium. Reliability is restricted, because precipitation processes may have been involved in sediment next to sorption processes, yielding overestimated partitioning coefficients. Suggest using only the lowest boundary for further data analysis.
Endpoint:
adsorption / desorption, other
Remarks:
Field study
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reason / purpose for cross-reference:
read-across source
Key result
Type:
log Kd
Value:
5.41 - 6.23
Matrix:
Sediment-pore water
Remarks on result:
other: Erbium
Type:
log Kd
Value:
5.15 - 7.18
Matrix:
Sediment-pore water
Remarks on result:
other: Cerium
Conclusions:
In this study, samples of sediment and pore water were taken along two rivers receiving wastewater from Hanoi, Vietnam, and analysed for Er and Ce. Sediment-pore water for these samples were reported to range from 5.41 to > 6.23 for erbium and 5.15 - 7.18 for cerium. Reliability is restricted, because precipitation processes may have been involved in sediment next to sorption processes, yielding overestimated partitioning coefficients. Suggest using only the lowest boundary for further data analysis.
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
GLP compliance:
not specified
Type of method:
batch equilibrium method
Media:
soil
Radiolabelling:
yes
Test temperature:
not reported
Analytical monitoring:
yes
Details on sampling:
Referred to previous papers (Yin et al., 1966; Du et al., 1996a, 1996b; Tao et al., 1996a, 1996b).
Contact time was 2 h.
Details on matrix:
Calcareous, sierozen soil, samples taken from top layer (0-20 cm) of cultivated land of Yuzhong county in the middle Gansu province, China.
Details on test conditions:
Experiments were conducted with untreated soil, treated soil to remove CaCO3, and treated soil to remove both CaCO3 and organic matter.
Ratio of solution to soil was 12.5 g/L.
Contact time 2 h.
Computational methods:
Kp calculations based on change in activity in aqueous solution before and after adsorption.
If the activity in the supernatant after adsorption was lower than the minimum detectable activity of the detector, Kp was roughly estimated from the activity before adsorption and the minimum detectable activity.
Key result
Type:
Kd
Value:
34 400 other: mg/g
Matrix:
Calcareous Chinese soil
Remarks on result:
other: Erbium
Type:
Kd
Value:
4 100 - 51 000 other: mg/g
Matrix:
Calcareous Chinese soil
Remarks on result:
other: Lanthanum
Type:
Kd
Value:
400 - 26 300 other: mg/g
Matrix:
Calcareous Chinese soil
Remarks on result:
other: Cerium
Adsorption and desorption constants:
Log Kp soil in untreated soil was 2.60.
Log Kp soil in treated soil (CaCO3 or both CaCO3 and organic matter removed) was 4.42.
Details on results (Batch equilibrium method):
Adsorption of lanthanides is concluded to be largely determined by oxides and silicate clays rather than CaCO3 and organic matter, because the values of lanthanides on both treated soils (CaCO3 and/or organic matter removed) are either greater or equal to those for untreated soil.
Conclusions:
Adsorption of erbium was investigated using calcareous Chinese soil and radiolabeled erbium, which gave a Kd value of 34 400 mg/g. This compares to values of 4 100 - 51 000 mg/g and 400 - 26 300 mg/g under the same conditions for lanthanum and cerium respectively.
Endpoint:
adsorption / desorption: screening
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reason / purpose for cross-reference:
read-across source
Key result
Type:
Kd
Value:
34 400 other: mg/g
Matrix:
Calcareous Chinese soil
Remarks on result:
other: Erbium
Type:
Kd
Value:
4 100 - 51 000 other: mg/g
Matrix:
Calcareous Chinese soil
Remarks on result:
other: Lanthanum
Type:
Kd
Value:
400 - 26 300 other: mg/g
Matrix:
Calcareous Chinese soil
Remarks on result:
other: Cerium
Conclusions:
Adsorption of erbium was investigated using calcareous Chinese soil and radiolabeled erbium, which gave a Kd value of 34 400 mg/g. This compares to values of 4 100 - 51 000 mg/g and 400 - 26 300 mg/g under the same conditions for lanthanum and cerium respectively.
Endpoint:
adsorption / desorption, other
Remarks:
field study
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
Field study in which Er concentrations were determined in surface water and sediment. Samples were taken from 15 different stations located in 4 different estuarine areas in Japan.
GLP compliance:
not specified
Remarks:
Reference is a publication and GLP status is not specified.
Type of method:
other: field study
Media:
sediment
Radiolabelling:
no
Test temperature:
Field water samples: 17.4-27.0°C with a geomean of 22.1°C
Analytical monitoring:
yes
Details on sampling:
Sampling locations:
- Near the mouth of the Mabechi River off Aomori (August 2007). Estuarine area located on the North Pacific side of Honshu. Water depth up to 60 m. 3 sampling stations.
- Near the mouth of the Mogami River off Yamagata (August 2007). Estuarine area located on the Japan sea side of Honshu. Water depth up to 55 m. 3 sampling stations.
- Near the mouth of the Kuma River off Kumamoto (November 2007). Semiclosed estuarine area located in the Yatsushiro Sea on the North Pacific Ocean side of Kyushu. Water depth up to 30 m. 3 sampling stations.
- Near the mouth of the Yura River off Kyoto (seasonal differences investigated - July, September, November 2007). Semiclosed estuarine area located in the SW part of Honshu at Wakasa Bay on the Japan Sea. Water depth up to 55 m. July: 3 sampling stations. September: 4 sampling stations. November: 2 sampling stations.

Water samples:
In each of the 4 estuarine areas, bottom water samples were taken 1-15 m above the seafloor at 2–4 stations that were located at different distances from the mouth of each river.
- Water was collected in acid-cleaned, Teflon-coated, 5-L horizontal Niskin X sampling bottles (General Oceanics).
- For metal analysis samples were filtered (< 0.2 µm fraction) with a precleaned 0.2 µm pore size capsule cartridge-type polytetrafluoroethylene filter (Advantec) connected to a sampling bottle spigot and then the water sample was gravity-filtered into a precleaned 250-mL low density polyethylene bottle. The filtrates were acidified with 0.1 mL of 68% superpure grade HNO3 (Tama Chemicals, AA-100) per 100 mL. The acidified solutions (pH < 2) were kept in a refrigerator (5°C) until the analyses for dissolved elements were done.

Sediment samples:
Surface sediments were collected at the same sampling point as for the water collection in the estuarine areas using an Eckmann bottom corer (Miyamoto Riken Inc., A-15). The surface sediment samples were transferred to polyethylene bags and stored in a refrigerator. The raw surface sediments were dried at room temperature, and then sieved (2 mm) to remove large particles and shell fragments before being dried at 105°C to a constant weight, which indicated the complete removal of moisture. Afterwards, the dried samples were transferred to glass bottles and stored in a dark place until analysis.
Details on matrix:
Both sandy and muddy sediments were observed, color from brown over dark brown and very dark grey to black.
Water content of sediments between 26 and 70% (geometric mean 42%).
Loss on ignition between 2.1 and 9.3% (geometric mean 4.8%).
Details on test conditions:
Field study
Temperature range of water samples: 17.4-27°C
Salinity range of water samples: 31.9-34.2 g/L
pH range of water samples: 8.1-8.4
DO (dissolved oxygen) concentration in water samples: 6.7-8.3 mg/L
SPM (suspended particulate matter) concentration 0.1-4.1 mg/L
DOC (dissolved organic carbon) concentration: 0.82-1.36 mg/L
Computational methods:
Kd = Cs/Cb
where Cs (g/kg) and Cb (g/L) represent the total element concentration in surface sediment and the dissolved element concentration in estuarine water, respectively.
In the publication, the factor of 0.2 was added because in the International Atomic Energy Agency (IAEA) Technical Report Series 422, 20% of the total concentration of each element in sediment was defined as exchangeable fraction with the aqueous phase. Because of doubts on the application of this factor it was not used here (i.e. the value in the study was divided by 0.2).
Key result
Type:
Kd
Value:
57 000 - 370 000 L/kg
Matrix:
Sediment and water
Remarks on result:
other: Erbium
Type:
Kd
Value:
680 000 - 5 900 000 L/kg
Matrix:
Sediment and water
Remarks on result:
other: Cerium
Type:
Kd
Value:
150 000 - 2 600 000 L/kg
Matrix:
Sediment and water
Remarks on result:
other: Lanthanum
Transformation products:
not measured
Conclusions:
In this study, samples of sediment and water were taken from 15 sampling stations in 4 Japanese estuaria and analysed for Er. Kd values for erbium ranged from 57 000 - 370 000 L/kg, the mean being 210 000 L/kg. In comparison, lanthanum and cerium Kd values ranged from 150 000 - 2 600 000 L/kg and 680 000 - 5 900 000, respectively.
Endpoint:
adsorption / desorption, other
Remarks:
Field study
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reason / purpose for cross-reference:
read-across source
Key result
Type:
Kd
Value:
57 000 - 370 000
Matrix:
Sediment and water
Remarks on result:
other: Erbium
Type:
Kd
Value:
150 000 - 2 600 000 L/kg
Matrix:
Sediment and water
Remarks on result:
other: lanthanum
Type:
Kd
Value:
680 000 - 5 900 000 L/kg
Matrix:
Sediment and water
Remarks on result:
other: cerium
Conclusions:
Samples of sediment and water were taken from 15 sampling stations in 4 Japanese estuaria and analysed for erbium, lanthanum and cerium. Kd values for erbium ranged from 57 000 - 370 000 L/kg, the mean being 210 000 L/kg. In comparison, lanthanum and cerium Kd values ranged from 150 000 - 2 600 000 L/kg and 680 000 - 5 900 000, respectively.
Endpoint:
adsorption / desorption, other
Remarks:
field study and lab study using field samples
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
a Klimisch 2 score (reliable with restrictions) was assigned because paired concentrations are not reported and adsorption coefficients are calculated using medians.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Field study in which Er concentrations were determined in both surface water, pore water, sediment, and suspended matter. Samples were taken from 6 sampling locations in the Rhine-Meuse estuary in the Netherlands. Further, also a lab study was performed using field samples.
GLP compliance:
not specified
Type of method:
other: both field study and lab study using field samples
Media:
other: sediment and suspended matter
Radiolabelling:
no
Test temperature:
Field sampling: no temperature range given.
Lab experiment: 15 °C
Analytical monitoring:
yes
Details on sampling:
Field sampling:
- Surface-water samples, suspended solids, and sediments (through 25-cm-deep, box-core sampling) were collected during June and July 1997 at six locations in the Rhine-Meuse estuary.
- Sampling locations: Nieuwe Maas, Nieuwe Maas, First Petroleum Harbour, Botlekhaven, Northsea Loswal Noord, and Northsea Terheide 30. Locations 1,2,6 are relatively clean. Locations 3,4 are directly influenced by industrial discharges, and location 5 is a disposal site for sediments that are contaminated through industrial discharges.
- Surface water samples were 0.45 µm filtered.
- Pore water samples were obtained by positive-pressure filtration (0.45 µm).
Lab study (location 2 sediment and water):
- Samples taken after 10 days.
Details on matrix:
- Sampling: see above.
- Organic carbon (%) median (range): 5.9 (4.0-24.2) in suspended solids of the six locations, 1.94 (0.08-3.82) in sediments of the six locations, 2.13 (0.88-2.81) for the sediments used in the lab study.
Details on test conditions:
Field study: no specific test conditions.
Lab study:
For every assay, two acid-rinsed polystyrene aquaria (replicates) were filled with sediments (1750 g wet weight) and seawater (4 L) from the appropriate location (2). Standard conditions: pH = 8.1, salinity 30 g/L, no addition of complexing agents, exposure time 10 d.
Further assays were conducted with diversified conditions:
- varying pH: 7.1, 7.7, 8.1 and 8.5;
- varying salinity: 10, 20 and 30 g/L
- addition of complexing agents: 500 mg H(PO4)2-, 400 µg F-
Computational methods:
Indicative adsorption coefficients could only be calculated using the median Er concentrations reported for the six locations and the lab study in pore water, surface water, sediments and suspended solids.
Key result
Type:
log Kd
Value:
4 - 5
Matrix:
Surface water, pore water, sediment and suspended solids
Remarks on result:
other: Erbium values dependent on salinity, pH, fluoride concentration and phosphate concentration.
Type:
log Kd
Value:
4 - 5.2
Matrix:
Surface water, pore water, sediment and suspended solids
Remarks on result:
other: Lanthanum values dependent on salinity, pH, fluoride concentration and phosphate concentration.
Adsorption and desorption constants:
see above
Conclusions:
In this study, cerium concentrations were determined in surface water, pore water, sediment and suspended solids of six locations in the Rhine-Meuse estuary (the Netherlands) as well as in a lab study using field samples of one of the six locations. Only medians and ranges were reported, therefore, only indicative adsorption coefficients could be calculated using the median values. Log Kd values were in the range of 4.0 – 5.0 for erbium and 4.0 - 5.2 for lanthanum depending salinity, pH, fluoride concentration and phosphate concentration.
Endpoint:
adsorption / desorption, other
Remarks:
field study and lab study using field samples
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reason / purpose for cross-reference:
read-across source
Key result
Type:
log Kd
Value:
4 - 5
Matrix:
Surface water, pore water, sediment and suspended solids
Remarks on result:
other: Erbium value depending salinity, pH, fluoride concentration and phosphate concentration.
Type:
log Kd
Value:
4 - 5.2
Matrix:
Surface water, pore water, sediment and suspended solids
Remarks on result:
other: Lanthanum value depending salinity, pH, fluoride concentration and phosphate concentration
Conclusions:
In this study, cerium concentrations were determined in surface water, pore water, sediment and suspended solids of six locations in the Rhine-Meuse estuary (the Netherlands) as well as in a lab study using field samples of one of the six locations. Only medians and ranges were reported, therefore, only indicative adsorption coefficients could be calculated using the median values. Log Kd values were in the range of 4.0 – 5.0 for erbium and 4.0 - 5.2 for lanthanum depending salinity, pH, fluoride concentration and phosphate concentration.
Endpoint:
adsorption / desorption, other
Remarks:
field study
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
for calculation of the Kpsuspended matter-water, the detection limit was used as aquatic Ce concentration since Ce was not detectable in the water phase. This reduces the reliability of this value.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Sediment, pore water, suspended matter, and water samples were taken in the Forsmark area, Baltic Sea, and analysed for Ce.
GLP compliance:
not specified
Type of method:
other: field study
Media:
other: sediment and suspended matter
Radiolabelling:
no
Test temperature:
between 2.3 and 12.3°C during sampling
Analytical monitoring:
yes
Details on sampling:
- Location and timing: all samples collected between 12-20 April 2005 in the bay between the north side of the islands of Stor and Lill-Tixlan, between the Forsmark nuclear power station and the town of Öregrund, NW Baltic Proper.
- Integrated water samples (10 L) collected from 0-4 m depth using a metal-free pump.
- Particulate organic matter in the water column was sampled through filtration of the water samples.
- Sediment: Kajak cores were taken at 7-8 m depth and sliced into two sections (0-3 cm and 3-6 cm).
- Pore water was extracted by centrifugation (20 min at 4500 rpm) from sediment samples.
Details on matrix:
no details reported
Details on test conditions:
field test
Computational methods:
Partitioning coefficients were calculated e.g. by dividing Ce concentration in solid phase by Ce concentration in water (L/kg).
Kpsuspended matter-water was calculated as well as Kpsediment-pore water for upper layer (0-3 cm) and lower layer (3-6 cm).
Key result
Type:
Kd
Value:
640 other: kg/m3
Matrix:
Water and suspended matter
Remarks on result:
other: Erbium
Type:
Kd
Value:
3 300 other: kg/m3
Matrix:
Water and suspended matter
Remarks on result:
other: Cerium
Key result
Type:
Kd
Value:
1.4 - 2.6 other: kg/m3
Matrix:
Water and sediment
Remarks on result:
other: Erbium
Type:
Kd
Value:
2.6 - 92 other: kg/m3
Matrix:
Water and sediment
Remarks on result:
other: Cerium
Conclusions:
In this study, water, suspended matter, sediment, and pore water samples were taken in the Forsmark area, Baltic Sea, and analysed for Er and Ce. Reported Kd values of 1.4 - 6.2 kg/m^3 for erbium compared to 2.6 - 92 kg/m^3 for cerium measured in water and sediment. A Kd value of 640 kg/m^3 for erbium compared to 3 300 kg/m3 for cerium was measured in water and suspended matter.
Endpoint:
adsorption / desorption, other
Remarks:
Field study
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reason / purpose for cross-reference:
read-across source
Key result
Type:
Kd
Value:
640 other: kg/m3
Matrix:
Water and suspended matter
Remarks on result:
other: Erbium measured in water and suspended matter
Type:
Kd
Value:
3 300 other: kg/m3
Matrix:
Water and suspended matter
Remarks on result:
other: Cerium
Key result
Type:
Kd
Value:
1.4 - 6.2 other: kg/m3
Matrix:
Water and sediment
Remarks on result:
other: Erbium
Type:
Kd
Value:
2.6 - 92 other: kg/m3
Matrix:
Water and sediment
Remarks on result:
other: Cerium
Conclusions:
In this study, water, suspended matter, sediment, and pore water samples were taken in the Forsmark area, Baltic Sea, and analysed for Er and Ce. Reported Kd values of 1.4 - 6.2 kg/m^3 for erbium compared to 2.6 - 92 kg/m^3 for cerium measured in water and sediment. A Kd value of 640 kg/m^3 for erbium compared to 3 300 kg/m3 for cerium was measured in water and suspended matter.
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well performed study.
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
GLP compliance:
not specified
Type of method:
batch equilibrium method
Media:
soil
Radiolabelling:
yes
Test temperature:
ca. 25°C
Analytical monitoring:
yes
Details on sampling:
After shaking for 2 h, the two phases were separated by centrifugation at 4000 rpm for 30 min.
Details on matrix:
1. Calcareous soil: irrigating soil, surface 0-20 cm, cultivated land in Jiuquan county of the Gansu corridor, China. pH 8.30, 1.72% oc, 13.5% CaCO3, CEC 5.94 meq./100 g soil, 10.4% clay.
2. Red earth: coastal sandy soil, from the coast of Da-Ya Bay of Guangdong province, China. pH 6.4, 3.28% oc, no CaCO3, CEC 6.82 meq./100 g soil, 2.0% clay.
Details on test conditions:
Batch equilibrium experiments at ca. 25°C.
50 mg soil and 4.0 mL aqueous solution containing 2.0 mL of multitracer solution and 2.0 mL of compound solution in a polyethylene test tube.
Test tubes shaken for 2 h.
Computational methods:
Values of Kp calculated from the difference in activities measured before and after sorption in the aqueous solution. If not detectable, minimum detectable activities were used for Kp calculation.
Type:
Kd
Value:
34 000 other: mg/g
Matrix:
Alumina and red earth
Remarks on result:
other: Erbium
Type:
Kd
Value:
4 100 - 5 300 other: mg/g
Matrix:
Alumina and red earth
Remarks on result:
other: Lanthanum
Type:
Kd
Value:
400 - 1 100 other: mg/g
Matrix:
Alumina and red earth
Remarks on result:
other: Cerium
Conclusions:
In this multitracer study, the adsorption of Er, La and Ce to two Chinese soils, a calcareous soil and a sandy red earth, was investigated in a batch equilibrium experiment. Kd values of 34 000 mg/g were observed for erbium in alumina and red earth compared to 4 100 - 5 300 mg/g and 400 - 1 100 mg/g under the same conditions for lanthanum and cerium respectively.
Endpoint:
adsorption / desorption: screening
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reason / purpose for cross-reference:
read-across source
Key result
Type:
Kd
Value:
34 000 other: mg/g
Matrix:
Alumina and red earth
Remarks on result:
other: Erbium
Type:
Kd
Value:
4 100 - 5 300 other: mg/g
Matrix:
Alumina and red earth
Remarks on result:
other: Lanthanum
Type:
Kd
Value:
400 - 1 100 other: mg/g
Matrix:
Alumina and red earth
Remarks on result:
other: Cerium
Conclusions:
In this multitracer study, the adsorption of Er, La and Ce to two Chinese soils, a calcareous soil and a sandy red earth, was investigated in a batch equilibrium experiment. Kd values of 34 000 mg/g were observed for erbium in alumina and red earth compared to 4 100 - 5 300 mg/g and 400 - 1 100 mg/g under the same conditions for lanthanum and cerium respectively.
Endpoint:
adsorption / desorption, other
Remarks:
Field study
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
A survey of 54 elements in up to 112 soils assessing the background levels of trace elements and their leachability from soils was completed. From this, the Kd was computed.
GLP compliance:
not specified
Remarks:
Publication
Type of method:
batch equilibrium method
Media:
soil
Analytical monitoring:
yes
Matrix type:
other: Mean of all soils
% Clay:
1.4 - 70
% Silt:
1.8 - 79
% Sand:
1.7 - 97
% Org. carbon:
0.05 - 10
pH:
3.5 - 8.2
Details on matrix:

Soil samples were obtained in two ways. The primary method was to contact researchers from across Canada and obtain soil samples they had in archive where the soil series and soil properties were well known. These were representative of agricultural soils in their region. Samples were obtained for 75 soils represented most provinces. A further 37 soils were included where Kd analyses had been done with the same methods and laboratories for previous research projects. Of these, 22 represented different sites from within a 2 km^2 study area in Southern Ontario and 15 were from benchmark sites in Manitoba, Ontario and Nova Scotia chosen specifically to represent a range of ecozones and soil Great Groups.
Details on test conditions:
Properties such as pH (in water), texture (three size classes of mineral material) and organic carbon content were obtained. Clay content and pH were significantly correlated (r = 0.26, P < 0.01, n = 102) indicative that generally only sandy soils were acidic. Total organic carbon was not correlated to either clay content or pH.
Sorption Kds for seven elements added during incubation vs desorption Kds for the same elements native to the soil without additions were compared. Kd measurements on six archived samples of 37 soils measured previously were taken.
The soils were incubated at field capacity for one week then pore water was extracted by centrifugal filtration for 37 soils. All pore water samples were subsequently filtered to pass through 0.45 μm. Many of the 75 archived samples were heavier and centrifugal filtration was not possible. For the 75 archived soils, sufficient water was added to create a saturated paste, typically 40 mL water in 60 g dry soil which was allowed to equilibrate for one week in loosely capped plastic centrifuge tubes with daily stirring. The samples were centrifuged and the supernatant water was filtered to pass 0.45 μm and collected for pore water analysis.
The Kd was computed as the concentration on the solids divided by the concentration in liquid.
Key result
Type:
Kd
Value:
330 - 520 000
Matrix:
Soil
Remarks on result:
other: Erbium
Type:
Kd
Value:
500 - 1 600 000
Matrix:
Soil
Remarks on result:
other: Lanthanum
Type:
Kd
Value:
440 - 3 700 000
Matrix:
Soil
Remarks on result:
other: Cerium
Adsorption and desorption constants:
Correlations among the Kd values were examined and it was observed that there were two general groups of elements: those whose log Kd were correlated to that of simple cations such as K, and those whose log Kd were correlated to those of Rare Earth Elements (REE) such as Ce, La and Eu.
Transformation products:
not measured
Conclusions:
Partitioning of indigenous erbium, lanthanum and cerium in 95 - 112 Canadian soil samples between soil and water under conditions near field capacity was investigated. The range of Kd values obtained were 330 – 520 000, 500 – 1 600 000 and 440 – 3 700 000 for erbium, lanthanum and cerium respectively.
Endpoint:
adsorption / desorption, other
Remarks:
Field study
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reason / purpose for cross-reference:
read-across source
Type:
Kd
Value:
330 - 520 000
Matrix:
Soil
Remarks on result:
other: Erbium
Type:
Kd
Value:
500 - 1 600 000
Matrix:
Soil
Remarks on result:
other: Lanthanum
Type:
Kd
Value:
440 - 3 700 000
Matrix:
Soil
Remarks on result:
other: Cerium
Transformation products:
not measured
Conclusions:
Partitioning of indigenous erbium, lanthanum and cerium in 95 - 112 Canadian soil samples between soil and water under conditions near field capacity was investigated. The range of Kd values obtained were 330 – 520 000, 500 – 1 600 000 and 440 – 3 700 000 for erbium, lanthanum and cerium respectively.

Description of key information

The following adsorption/desorption distribution coefficients were obtained for the analogous test materials Lanthanum oxide and cerium carbonate at the soil-to-solution ratio of 1/50:
- Mean Koc value: 5480283, 3940404, respectively
As a representative value, the lower mean value was used as the key value.

Key value for chemical safety assessment

Koc at 20 °C:
3 940 404

Additional information

A total of nine studies was used in a weight of evidence approach to cover the endpoint. OECD 106 compliant batch sorption studies on lanthanum oxide and cerium carbonate were available and these showed mean Koc values (3 soils) of 5 480 283 and 3 940 404, respectively for the two rare earth metals (the same group as erbium).


Seven published papers were available determining sorption values (Kd) for erbium in suspended matter, sediment and soil.  Importantly, these papers generally also provided results for cerium and/or lanthanum using the same methodology as for erbium. The overall summary taking into account all results was that the sorption of erbium was slightly lower than that of lanthanum and cerium but that the ranges of data overlapped. This is further discussed below:


For sediment, three studies were included in the weight of evidence approach. In the study of Takata et al. (2010), samples of sediment and water were taken from 15 sampling stations in 4 Japanese estuaria and analysed for erbium, lanthanum and cerium. Kd values for erbium ranged from 57 000 – 370 000 L/kg, the mean being 210 000 L/kg. In comparison, lanthanum and cerium log Kd values ranged from 150 000 – 2 600 000 L/kg and 680 000 – 5 900 000, respectively. Marcussen et al. (2008) sampled sediment and pore water along two rivers receiving wastewater from Hanoi, Vietnam. Log Kd values for sediment-pore water for these samples were reported to range from 5.41 to > 6.23 L/kg for erbium and 5.15 - 7.18 for cerium. Based on data from the study of Moermond et al. (2001), log Kd values were in the range of 4.0 – 5.0 for erbium and 4.0 - 5.2 for lanthanum depending salinity, pH, fluoride concentration and phosphate concentration. Kumblad and Bradshaw (2008) reported Kd values of 1.4-6.2 kg/m3 for erbium compared to 2.6 - 92 kg/m^3 for cerium measured in water and sediment sampled in the Forsmark area, Baltic Sea.


For suspended matter one study was identified as useful. Kumblad and Bradshaw (2008) reported a Kd value of 640 kg/m3 for erbium compared to 3 300 kg/m^3 for cerium measured in water and suspended matter sampled in the Forsmark area, Baltic Sea.


For soil, a total of three studies were included in the weight of evidence approach. In the study of Sheppard et al. (2007), partitioning of indigenous erbium, lanthanum and cerium in 95 - 112 Canadian soil samples between soil and water under conditions near field capacity was investigated. The range of Kd values obtained were 330 – 520 000, 500 – 1 600 000 and 440 – 3 700 000 for erbium, lanthanum and cerium respectively. Data from Du et al. (1998), in which adsorption of erbium was investigated using calcareous Chinese soil and radiolabeled erbium, gave a Kd value of 34 400 mg/g. This compares to values of 4 100 – 51 000 mg/g and 400 – 26 300 mg/g under the same conditions for lanthanum and cerium respectively.  This work was extended by Tao et al. (2000) who found Kd values of 34 000 mg/g for erbium in alumina and red earth compared to 4 100 – 5 300 mg/g and 400 – 1 100 mg/g under the same conditions for lanthanum and cerium respectively.


In conclusion, the published papers confirm that sorption constants for erbium are high and overlap the ranges of those for lanthanum and cerium. Using the batch sorption studies on lanthanum oxide and cerium carbonate enables an appropriate read-across to a standard OECD 106 guideline result for dierbium trioxide. The lower Koc value of 3 940 404 from cerium carbonate is appropriate for use as the endpoint for risk assessment of dierbium trioxide.