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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:
Suspended matter and water samples were taken from five sampling locations in the Ionian Sea and the Strait of Sicily and were analysed for Yb. Log Kp values for suspended matter-water were calculated from analysed concentrations of Yb in paired samples.
GLP compliance:
not specified
Type of method:
other: field study
Media:
suspended matter
Radiolabelling:
no
Test temperature:
Depending on the depth (temperature decreasing with increasing depth) but overall between 14.56 and 25.90°C for all samples taken at the five locations.
Analytical monitoring:
yes
Details on sampling:
- Samples were collected in the early summer of 1999 during the JUVENILE 99 cruise, aboard the RV Urania.
- At five locations (S24 and S470 in the Ionian Sea and S128, S455 and S458 in the Strait of Sicily), paired samples of water and suspended matter were taken.
- Different samples were taken at different depths at each sampling location, with depth overall ranging between 10 and 650 m.
- The sampling system consisted of a Neil-Brown CTD rosette frame and 24 x 12 L Teflon-lined GoFlo bottles. Upon recovery of the GoFlo bottles, water samples were immediately filtered inside the shipboard through 0.4 µm Millipore filters, using a Teflon tubing apparatus. Samples were acidified to pH 1-2 with HNO3 Merck ULTRAPUR and stored in hot-acid washed polyethylene bottles.
Details on matrix:
No details reported on matrix.
Details on test conditions:
No further details reported.
Computational methods:
Concentrations of the element under consideration analysed in suspended matter were divided by dissolved concentrations of the element analysed in filtered seawater sampled at the same sampling location (including same depth) to obtain Kp values.
Phase system:
suspended matter-water
Type:
log Kp
Value:
>= 3.66 - <= 5.16 L/kg
Remarks on result:
other: range for all paired samples
Phase system:
suspended matter-water
Type:
log Kp
Value:
4.09 L/kg
Remarks on result:
other: mean for all paired samples
Conclusions:
In this study, samples of suspended matter and (filtered) seawater were taken from two sampling locations in the Ionian Sea and 3 sampling locations in the Strait of Sicily and analysed for Yb. Log Kp suspended matter-water values were calculated from the results obtained for paired samples and ranged between 3.66 and 5.16 L/kg, the mean being 4.09 L/kg.
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:
Log Kp values calculated from analysed concentrations of Yb in field samples.
GLP compliance:
not specified
Type of method:
other: field study
Media:
suspended matter
Radiolabelling:
no
Test temperature:
Ambient temperature, not specified.
Analytical monitoring:
yes
Details on sampling:
Water samples were collected from a fishing boat using a hand-made polyethylene sampler consisting of a 5 L Niskin bottle. Upon recovery of the bottles, water samples were filtered through 0.2 μm Millipore® filters, using a Teflon tubing apparatus. The filtration was done immediately on board, and samples were always transported within 8 h to the laboratory. Filtered samples were acidified to pH 1–2 with HNO3 (Merck ULTRAPUR®) and stored in hot-acid-washed polyethylene bottles.
Seafloor sediments were sampled with a Van Veen bucket in the same stations where seawater and suspended materials in the water column were collected.
In order to increase the signal/noise ratio in the studied seawaters, for Y and REE analyses 1000 mL of each sample was pre-concentrated with a CHELEX 100® (100–200 mesh) ion exchange resin:
• pH value of each seawater sample was set to 6.0 ± 0.1 with CH3COONH4, and an aliquot of each seawater sample passed on an 8-cm-long column filled with CHELEX-100 100–200 mesh previously cleaned and conditioned.
• REY were eluted with 5 mL of HNO3 3.5 M, giving a 100-fold enrichment factor. Details of the procedures are reported in the literature.
Details on matrix:
Sediment and suspended matter samples taken from several sampling locations in the western Gulf of Thailand.
Details on test conditions:
Seawater and suspended matter samples were taken at 0.5 m depth and/or at greater depths between 5 and 18 m.
Computational methods:
Concentrations of the element under consideration analysed in suspended matter were divided by dissolved concentrations of the element analysed in filtered seawater sampled at the same sampling location (including same depth) to obtain Kp values.
For sediment-water Kp values, the concentration analysed in the sediment sample was divided by the dissolved concentration in filtered seawater from the greatest sampling depth.
Phase system:
suspended matter-water
Type:
log Kp
Value:
>= 5.02 - <= 6.32 L/kg
Remarks on result:
other: range for all samples
Phase system:
suspended matter-water
Type:
log Kp
Value:
5.78 L/kg
Remarks on result:
other: mean value for all samples

Station number

Yb (mg/L)

Yb in SPM (mg/kg)

Kp SPM (L/kg)

Log Kp

128a

7.15001E-06

1.315

183915.8

5.264619

129a

3.76881E-06

2.225

590371.8

5.771126

130a

2.46997E-05

4.169

168787.3

5.22734

131a

1.00052E-05

3.398

339624.3

5.530999

132a

2.82003E-05

2.963

105069.7

5.021477

133a

1.88008E-05

5.172

275094.7

5.439482

134a

1.78006E-05

5.213

292854.9

5.466652

135a

8.1E-06

10.721

1323580

6.12175

138a

2.13497E-05

5.213

244172.3

5.387696

140a

5.14275E-06

3.259

633707.8

5.801889

141a

3.07838E-06

1.462

474924.9

5.676625

142a

4.90049E-06

2.623

535252.3

5.728559

143a

4.95067E-06

3.294

665363.9

5.823059

144a

3.18999E-05

4.236

132790.3

5.123166

145a

5.45076E-06

6.481

1189009

6.075185

146a

9.44971E-06

2.998

317258.3

5.501413

147a

2.95898E-06

2.798

945594.8

5.975705

148a

3.03512E-06

1.997

657963.8

5.818202

149a

2.18376E-06

3.683

1686537

6.226996

150a

3.84841E-06

6.172

1603779

6.205145

151a

6.52015E-06

4.724

724523.5

5.860052

152a

6.12735E-06

NA

NA

153a

2.72365E-06

3.322

1219687

6.086248

128b

4.34676E-06

2.139

492090.1

5.692045

129b

2.95898E-06

5.122

1731000

6.238297

140b

2.54888E-06

5.268

2066791

6.315297

141b

2.99359E-06

4.946

1652196

6.218062

147b

4.69977E-06

3.182

677054.9

5.830624

148b

3.57501E-06

3.313

926711.6

5.966945

150b

7.82141E-06

NA

NA

128c

3.55078E-06

5.691

1602746

6.204865

129c

7.50301E-06

3.852

513393.7

5.71045

130c

7.82141E-06

2.952

377425.7

5.576831

131c

8.83542E-06

4.626

523574.3

5.718978

140c

4.50077E-06

NA

NA

141c

2.69942E-06

2.861

1059856

6.025247

142c

5.00086E-06

4.947

989230.6

5.995298

148c

3.52656E-06

3.639

1031885

6.013631

149c

6.38691E-06

0.96

150307.5

5.176981

150c

4.42809E-06

6.433

1452770

6.162197

151c

5.59957E-06

3.247

579865.5

5.763327

152c

3.59923E-06

1.471

408698.3

5.611403

Conclusions:
In this study, samples of suspended matter and (filtered) seawater were taken from various sampling sites in the western Gulf of Thailand and analysed for Yb. Log Kp suspended matter-water values were calculated from the results obtained for paired samples and ranged between 5.02 and 6.32 L/kg, the mean being 5.78 L/kg.
Endpoint:
adsorption / desorption, other
Remarks:
multitracer experiment
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:
Multitracer experiment. The adsorption of elements on model samples of marine particulates, including deep-sea and near-shore sediments, was studied.
GLP compliance:
no
Type of method:
other: multitracer experiment
Media:
sediment
Radiolabelling:
yes
Remarks:
radioactive multitracers are used
Test temperature:
25°C
Analytical monitoring:
yes
Details on sampling:
The suspension was shaken in an 8-shape mode with a shaker at 25° C. After centrifugation, a portion of the supernatant solution was pipetted.
Details on matrix:
Matrix 1
COLLECTION AND STORAGE
- Geographic location: deep-sea sediment Penrhyn Basin (12°26.44'S, 157°57.20'W, depth 5351 m)
- Storage conditions: in artificial seawater (storage 2 mg/cm³ artificial seawater), pH of suspension adjusted to 7.5

Matrix 2
COLLECTION AND STORAGE
- Geographic location: near-shore sediment Suruga Bay (34°44.52.'N, 169°27.05'E, depth ca. 600 m)
- Storage conditions: in artificial seawater (storage 2 mg/cm³ artificial seawater), pH of suspension adjusted to 7.5
Details on test conditions:
TEST CONDITIONS
10 cm3 of artificial sea water and 0.01 cm3 of a multitracer solution were put into a polyethylene bottle. After the pH was adjusted to 7.5 with a 1 M Na2CO3 solution, the adsorbent suspension was added. Resulting concentrations of adsorbent were 0.1, 0.05 and 0.01 mg/cm3. pH of suspension was readjusted to 7.5 when necessary.

Artifical seawater containing 23.94 g NaCl and 0.196 g NaHCO3 / 1000 cm3 water was used.

TEST SYSTEM
- Type, size and further details on reaction vessel: polyethylene bottle.
- Amount of soil/sediment/sludge and water per treatment: 10 cm3 artificial seawater + 0.01 cm3 of a multitracer solution + 0.1, 0.05 or 0.01 mg adsorbent/cm3.
- Suspension was shaken in a 8-shape mode with a shaker at 25°C.
- To reach equilibrium, 1-2 days of shaking was needed (not further specified for Yb).
Computational methods:
Kads = (Aads/m)/(Asoln/V) = ((Ai - Af)/Af)(V/m)
Aads = radioactivity in the adsorbent after adsorption equilibrium
Asoln = radioactivity in the solution after adsorption equilibrium
V = volume of the solution (cm3)
m = amount of adsorbent (g)
Ai = radioactivity in the solution before adsorption equilibrium
Af = radioactivity in the solution after adsorption equilibrium
Phase system:
sediment-water
Type:
log Kp
Value:
4.63 L/kg
Temp.:
25 °C
pH:
7.5
Matrix:
deep-sea sediment
Phase system:
sediment-water
Type:
log Kp
Value:
4.6 L/kg
Temp.:
25 °C
pH:
7.5
Matrix:
near-shore sediment
Conclusions:
In this multitracer experiment, the log Kp for Yb for deep-sea and near-shore sediment in artificial seawater was determined to be 4.63 and 4.60 L/kg, 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:
Sediment, pore water, suspended matter, and water samples were taken in the Forsmark area, Baltic Sea, and analysed for Yb.
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 by dividing Yb concentration in solid phase by Yb concentration in water (L/kg).
Kpsuspended matter-water as well as Kpsediment-pore water were calculated (the latter for upper layer (0-3 cm) and lower layer (3-6 cm)).
Phase system:
suspended matter-water
Type:
log Kp
Value:
4.81 L/kg
Remarks on result:
other: Concentrations in filtered water were below the detection limit, therefore the detection limit was used as aquatic Yb concentration.
Phase system:
solids-water in sediment
Type:
log Kp
Value:
3.26 L/kg
Remarks on result:
other: Concentrations in sediment and pore water of upper sediment layer (0-3 cm) were used.
Details on results (Batch equilibrium method):
For the lower sediment layer (3-6 cm), a log Kpsediment-pore water of 3.72 L/kg was obtained (Yb concentration in pore water was however below the detection limit, consequently the detection limit was used for calculation of the log Kp).
Conclusions:
In this study, water, suspended matter, sediment, and pore water samples were taken in the Forsmark area, Baltic Sea, and analysed for ytterbium. The log Kpsuspended matter-water was calculated to be 4.81 L/kg, using the detection limit as aquatic ytterbium concentration since ytterbium was not detectable in the water phase. The log Kpsediment-pore water for the upper sediment layer (0-3 cm) was determined to be 3.26 L/kg.
Endpoint:
adsorption / desorption, other
Remarks:
field study and laboratory study with 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
Qualifier:
no guideline followed
Principles of method if other than guideline:
Field study in which Yb 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 laboratory study using field samples
Media:
other: sediment and suspended matter
Radiolabelling:
no
Test temperature:
Field sampling: no temperature range given.
Laboratory 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.
Laboratory 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 Yb concentrations reported for the six locations and the laboratory study in pore water, surface water, sediments and suspended solids.
Phase system:
sediment-water
Type:
log Kp
Value:
ca. 5.64 L/kg
Remarks on result:
other: calculated using median values for field samples (sediment and surface water)
Phase system:
solids-water in sediment
Type:
log Kp
Value:
ca. 5.24 L/kg
Remarks on result:
other: calculated using median values for field samples (sediment and pore water)
Phase system:
suspended matter-water
Type:
log Kp
Value:
ca. 5.81 L/kg
Remarks on result:
other: calculated using median values for field samples (suspended matter and surface water)
Phase system:
sediment-water
Type:
log Kp
Value:
ca. 5.32 L/kg
Remarks on result:
other: calculated using median values for laboratory study samples (sediment and surface water)
Phase system:
solids-water in sediment
Type:
log Kp
Value:
ca. 4.75 L/kg
Remarks on result:
other: calculated using median values for laboratory study samples (sediment and pore water)
Adsorption and desorption constants:
see above
Statistics:
Median values used for Kp calculation, hence Kp values only indicative. Paired values for aqueous and solid phase not reported.
Conclusions:
In this study, ytterbium 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 Kp values for sediment-surface water were 5.64 L/kg (field) and 5.32 L/kg (laboratory). Log Kp values for sediment-pore water were 5.24 L/kg (field) and 4.75 L/kg (laboratory). The log Kp value for suspended solids-surface water was 5.81 L/kg (field).
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:
no guideline followed
Principles of method if other than guideline:
In this study, Kp values were measured for 54 elements in 112 Canadian soils. For 37 soils, the method followed was to incubate soils at field capacity for one week and then extract pore water by centrifugal filtration. For the other 75 soils, sufficient water was added to create a saturated paste which was allowed to equilibrate for one week with daily stirring. Samples were then centrifuged and the supernatant of the water was filtered and collected for pore water analysis.
GLP compliance:
not specified
Type of method:
other: equilibration at field capacity
Media:
soil
Radiolabelling:
no
Test temperature:
Not reported - ambient.
Analytical monitoring:
yes
Details on sampling:
- For the 37 soils incubated at field capacity for one week, pore water was extracted by centrifugal filtration (Thibault and Sheppard, 1992). All pore water samples were filtered to pass 0.45 µm.
- For the 75 archived soils, to which sufficient water was added to create a saturated paste which was allowed to equilibrate for one week with daily stirring, the samples were centrifuged and the supernatant water was filtered to pass 0.45 µm and collected for pore water analysis.
Details on matrix:
COLLECTION AND STORAGE
Soil samples were obtained in two ways:
- 75 soils were obtained by contacting researchers from across Canada with the request to provide soil samples they had in archive, of which soil series and soil properties were well known. The obtained soil samples represented (sparsely) most provinces.
- A further 37 soils were included where adsorption coefficients had been determined with the same methods and laboratories for previous research projects (unpublished data). Of these, 22 represented different sites from within a 2 km2 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.
- In all cases, the trace elements present in the soils were not of recent origin.

PROPERTIES
- TOC % (total organic carbon): 0.05-10% (geometric mean, GSD and median = 2.9, 2.1 and 2.6%, respectively)
- % sand: 1.7-97% (geometric mean, GSD and median = 45, 24 and 43%, respectively)
- % silt: 1.8-79% (geometric mean, GSD and median = 34, 15 and 35%, respectively)
- % clay: 1.4-70% (geometric mean, GSD and median = 20, 16 and 14%, respectively)
- pH: 3.5-8.2 (geometric mean, GSD and median = 6.2, 1.1 and 6.2, respectively)
Details on test conditions:
- The method considered as the best for measurement of adsorption coefficients is to incubate soils at field capacity for one week, and then extract pore water by centrifugal filtration (Thibault and Sheppard 1992). This was done for the 37 soils from the previous studies. Field capacity is defined in this case as the water held against gravitational drainage in the centrifuge tubes. In some cases, the yield of water was low enough that several soil aliquots had to be (simultaneously) extracted and a composite pore water sample used. All pore water samples were subsequently filtered to pass 0.45 μm. This method is achievable for medium- to light-textured soils. However, many of the 75 archived soils were heavier, and centrifugal filtration was not possible.
- For all of the 75 archived soils, sufficient water was added to create a saturated paste, typically 40 mL water in 60 g of dry soil. This 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.
Computational methods:
The soil/liquid partition coefficient, Kp, was computed as the concentration on the solids (mg/kg) divided by the concentration in the liquid (mg/L), with final units of L/kg. The Central Limit Theorem, experience with this type of data, and review of the data obtained, indicated that the best default assumption was that the concentrations and the Kp values were log-normally distributed. Thus, geometric mean (GM) and geometric standard deviation (GSD) are reported, and correlations and regressions were computed with log-transformed data. Forward stepwise regression was used to relate Kp to soil properties (pH, clay content (%) and total organic carbon (%)), and only coefficients significant at P < 0.05 were retained in the equations. No variable interactions were included in the regression process.
Phase system:
solids-water in soil
Type:
log Kp
Value:
4.3 L/kg
Remarks on result:
other: mean for all soil samples tested (107 for Yb)
Phase system:
solids-water in soil
Type:
log Kp
Value:
>= 2.45 - <= 5.56 L/kg
Remarks on result:
other: range for all soil samples tested (107 for Yb)
Details on results (Batch equilibrium method):
In this study, the mean log Kp for ytterbium was determined to be 4.30 L/kg. The results of this study were used by Sheppard (2011) to derive regression equations for predicting log Kp based on pH and clay content. The obtained relationship was: Log(Kp) = 2.71 + 0.244·(pH) − 0.000962·(clay)·(pH).
Reference: Sheppard SC, 2011. Robust Prediction of Kd from Soil Properties for Environmental Assessment. Human and Ecological Risk Assessment 17, 263-279.
Conclusions:
In this study, partitioning of indigenous Yb in 107 Canadian soil samples between soil and water under conditions near field capacity was investigated. The mean log Kp for ytterbium was determined to be 4.30 L/kg. The range of log Kp values was 2.45 to 5.56 L/kg.
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 Yb 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:
field study, results reported in scientific literature, no information on GLP
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).
Phase system:
sediment-water
Type:
log Kp
Value:
>= 5.58 - <= 6.36 L/kg
Remarks on result:
other: range for all paired samples
Phase system:
sediment-water
Type:
log Kp
Value:
6.09 L/kg
Remarks on result:
other: mean for all paired samples
Conclusions:
In this study, samples of sediment and water were taken from 15 sampling stations in 4 Japanese estuaria and analysed for Yb. Log Kp values ranged from 5.58 to 6.36 L/kg, the mean being 6.09 L/kg.
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:
Sediment, pore water, and surface water samples were taken at five locations in The Netherlands. These samples were analysed for Yb.
GLP compliance:
not specified
Type of method:
other: field study
Media:
sediment
Radiolabelling:
no
Test temperature:
Temperature at sampling occasions between 18 and 21°C.
Analytical monitoring:
yes
Details on sampling:
Five locations in The Netherlands, four of them in highly industrialised region around city of Rotterdam. All sampling sites in catchment of Rhine and Meuse rivers. 1. Veluwemeer, 2. Botlekpark, 3. Kralingse Plas, 4. Nieuwe Maas, 5. Charlois.
Samples were taken in August and September 2000.
Surface water samples (n=3) 0.45 µm filtered.
Pore water samples (n=3) were extracted in situ using Rhizon soil moisture samplers (MOM type, Eijkelkamp Agrisearch Equipment, Giesbeek, The Netherlands).
Sediment samples (n=3) were collected with a bottom sampler according to Ekman-Birge (Hydro-bios, Kiel, Germany).
Details on matrix:
Average pH of sampling locations at time of sampling was between 7.30 and 8.72. Quite similar for pore water (between 6.92 and 7.55).
No characteristics given for sediment.
Details on test conditions:
Field study.
Computational methods:
Kp sediment values were calculated dividing concentration in sediment (mg/kg) by concentrations in either surface water or pore water (mg/L).
This was done separately for the < 2 mm sediment fraction and the < 0.063 mm sediment fraction.
Phase system:
sediment-water
Type:
log Kp
Value:
>= 5.3 - <= 6.04 L/kg
Remarks on result:
other: range derived from Figure 11 (< 2-mm sediment fraction)
Phase system:
solids-water in sediment
Type:
log Kp
Value:
>= 5 - <= 5.4 L/kg
Remarks on result:
other: range derived from Figure 12 (< 2-mm sediment fraction)
Concentration of test substance at end of adsorption equilibration period:
The lanthanide concentrations measured in the < 0.063-mm sediment fraction were similar as those in the < 2-mm sediment fraction for three out of the five sampled locations. For the locations Nieuwe Maas and Veluwemeer, the < 0.063-mm sediment fraction however contained higher lanthanide concentrations than the sediment fraction < 2 mm. These locations are those with the lowest concentrations of lanthanides measured in the < 2-mm fraction and the highest in the < 0.063-mm fraction. This is due to exclusion of the relatively high sand fraction of these sediments, which for the most part is > 0.063 mm and contains low lanthanide concentrations.
Conclusions:
In this study, sediment, surface water, and pore water samples were taken at five locations in The Netherlands in the Rhine-Meuse catchment. Yb was determined in all samples and log Kp sediment-surface water was reported (in figures) to range from 5.30 to 6.04 L/kg, whereas the log Kp sediment-pore water was reported (also in figures) to range from 5.0 to 5.40 L/kg.
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:
Water, suspended matter, and sediment samples were taken from 8 locations along the Yangtze River and analysed for Yb. Log Kp values were calculated from analysed concentrations of Yb in the field samples.
GLP compliance:
not specified
Type of method:
other: field study
Media:
other: sediment and suspended matter
Radiolabelling:
no
Test temperature:
Ambient temperature, not specified.
Analytical monitoring:
yes
Details on sampling:
Samples of water, suspended matter and sediments were taken simultaneously in July-August, 1992. Industrially polluted areas and municipal waste water outlets were avoided. Unfiltered water samples were preserved for analysis of total amount of REEs. Filtered water (through 0.45 µm filtration membranes) was preserved for analysis of the dissolved fraction of REEs. Both unfiltered and filtered water samples were acidified to a pH < 2 with ultra-pure HNO3. Suspended matter samples were taken from the membranes directly. The suspended matter and sediments were air dried, and passed through a 20 mesh sieve for speciation analysis.
For analysis of the contents of REEs, the suspended matter and sediments were also ground until all the samples passed a 100 mesh sieve.
Details on matrix:
Eight sampling locations along the mainstream of the Yangtze River - no further details on matrix reported.
Details on test conditions:
No further details reported.
Computational methods:
For suspended matter-water Kp values, the concentration of the element under consideration analysed in suspended matter was divided by the dissolved concentration of the element analysed in filtered water samples.
For sediment-water Kp values, the concentration of the element under consideration analysed in the sediment sample was divided by the dissolved concentration of the element analysed in filtered water samples.
Phase system:
suspended matter-water
Type:
log Kp
Value:
>= 5.46 - <= 5.64 L/kg
Remarks on result:
other: range for all samples
Phase system:
suspended matter-water
Type:
log Kp
Value:
5.59 L/kg
Remarks on result:
other: mean value for all samples
Phase system:
sediment-water
Type:
log Kp
Value:
>= 5.48 - <= 5.6 L/kg
Remarks on result:
other: range for all samples
Phase system:
sediment-water
Type:
log Kp
Value:
5.56 L/kg
Remarks on result:
other: mean for all samples
Conclusions:
In this study, samples of suspended matter, sediment, and water were taken from 8 sampling sites in the Yangtze River and analysed for Yb. Log Kp suspended matter-water values were calculated from the results obtained for paired samples and ranged between 5.46 and 5.64 L/kg, the mean being 5.59 L/kg. Log Kp sediment-water values were also calculated from the results obtained for paired samples and ranged between 5.48 and 5.60 L/kg, the mean being 5.56 L/kg.
Endpoint:
adsorption / desorption, other
Remarks:
read across data
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
For this endpoint, data on the adsorption of ytterbium to particulate matter is used from experiments performed in the laboratory (e.g., multitracer experiment of Chen et al. (1996) in sediments; equilibrium partitioning experiments of Sheppard et al. (2007) in Canadian soil samples) as well as from field or mixed field/laboratory experiments, in which field samples of particulate matter and surface/pore water were analysed for Yb. In the multitracer study, Yb in a multitracer solution was used as 'test item'. In the remaining studies, there was no specific test item, as Yb present in field samples was analysed. Therefore, in theory, all studies should be considered as read across studies. An elemental approach was followed to cover this endpoint, lumping the data from all available studies.
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Phase system:
sediment-water
Type:
log Kp
Value:
>= 3.26 - <= 6.36 L/kg
Remarks on result:
other: range of log Kp values for sediment-surface water and sediment-pore water obtained in the read across studies
Phase system:
suspended matter-water
Type:
log Kp
Value:
>= 3.66 - <= 6.32 L/kg
Remarks on result:
other: range of log Kp values for suspended matter-water obtained in the read across studies
Phase system:
solids-water in soil
Type:
log Kp
Value:
>= 2.45 - <= 5.56 L/kg
Remarks on result:
other: range of log Kp values for soil-pore water (at or near field capacity) in the read across study
Endpoint:
adsorption / desorption, other
Remarks:
field study and lab study with field samples
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
secondary literature
Qualifier:
no guideline followed
Principles of method if other than guideline:
The concentration of Yb in water and sediment at state of equilibrium was measured in laboratory tests and in the field and Kp values were calculated.
GLP compliance:
no
Type of method:
other: field study and lab experiment with field samples
Media:
sediment
Radiolabelling:
no
Test temperature:
no data
Analytical monitoring:
yes
Details on sampling:
Samples of sediment, pore water and surface water were taken at Nieuwe Maas, Rhine estuary, the Netherlands.
Samples in the laboratory study were taken after 10 days.
All water samples 0.45 µm filtered.
Details on matrix:
- Details on collection location: Nieuwe Maas, Rhine estuary, The Netherlands, three different collection times.
- pH at time of collection: 8-8.5
- Organic carbon (%): 0.88, 2.17 and 2.77 % at different sample collection times
Details on test conditions:
Laboratory experiment: duration time 10 d
Computational methods:
Kp sediment-surface water and Kp sediment-pore water distribution coefficients were calculated using measured concentrations in solid and aqueous phase.
Phase system:
sediment-water
Type:
log Kp
Value:
5.35 L/kg
Remarks on result:
other: lab (sediment and surface water)
Phase system:
sediment-water
Type:
log Kp
Value:
5.87 L/kg
Remarks on result:
other: field (sediment and surface water)
Phase system:
solids-water in sediment
Type:
log Kp
Value:
4.75 L/kg
Remarks on result:
other: lab (sediment and pore water)
Phase system:
solids-water in sediment
Type:
log Kp
Value:
5.36 L/kg
Remarks on result:
other: field (sediment and pore water)

Sneller et al. stated, that the differences between the laboratory and the field derived data are probably due to disturbance and subsequent oxidation of the sediments in the laboratory experiments, causing relatively high concentrations in the pore water. In addition, increased decay of organic material in the disturbed sediments, involving reduction-processes, may contribute to release of REEs from sediment. For these reasons, field derived partition coefficients are preferred over laboratory derived values for calculation of MACs (maximum acceptable concentrations).

Furthermore, when evaluating the partitioning data one must keep in mind that pH, the presence of negative counterions and the concentration of dissolved organic carbon (DOC) in the (pore-) water strongly influence the concentration of REEs in solution. When pH, DOC concentrations and negative counterion concentrations are high, a large part of the total dissolved REE concentrations may not represent ´true´ partitioning.

Conclusions:
In this study, adsorption of Yb to sediment was evaluated by determining Yb in sediment, pore water, and surface water sampled in the field and after 10 days of using sediment/water samples in a study in the laboratory. The obtained log Kp sediment values were 5.35 and 5.87 L/kg when based on sediment and surface water concentrations in laboratory and field, respectively, and 4.75 and 5.36 L/kg when based on sediment and pore water concentrations in laboratory and field, respectively.

Description of key information

A total of ten studies was used in a weight of evidence approach to cover the endpoint. Data were available for suspended matter, sediment and soil. The following final key values were retained: a log Kp of 5.34 L/kg for sediment-water, a log Kp of 5.32 L/kg for suspended matter-water, and a log Kp of 4.30 L/kg for soil-water.

Key value for chemical safety assessment

Other adsorption coefficients

Type:
other: log Kp sediment-water
Value in L/kg:
5.34

Other adsorption coefficients

Type:
other: log Kp suspended matter-water
Value in L/kg:
5.32

Other adsorption coefficients

Type:
other: log Kp soil-water
Value in L/kg:
4.3

Additional information

In total, ten studies were selected as useful for covering the adsorption/desorption endpoint using a weight of evidence approach. Data were available for sediment, suspended matter and soil, and will be further discussed below.

For sediment, seven studies were included in the weight of evidence approach. Moermond et al. (2001) determined ytterbium concentrations in sediment, surface water and pore water samples taken from six locations along the Rhine-Meuse estuary (The Netherlands), and also determined ytterbium concentrations in sediment, surface water and pore water during experiments performed in the laboratory using the obtained field samples. Only medians and ranges were reported, therefore, only indicative adsorption coefficients could be calculated using the median values. Log Kp values for sediment-surface water were 5.64 L/kg (field) and 5.32 L/kg (laboratory). Log Kp values for sediment-pore water were 5.24 L/kg (field) and 4.75 L/kg (laboratory). Sneller et al. (2000) reported log Kp values obtained by Stronkhorst and Yland (1998) of 4.75 and 5.36 L/kg when based on pore water concentrations in lab and field, respectively, and 5.35 and 5.87 L/kg when based on surface water concentrations in lab and field, respectively. In the study by Weltje et al. (2002), sediment, surface water, and pore water samples were taken at five locations in The Netherlands in the Rhine-Meuse catchment. Log Kp sediment-surface water was reported (in figures) to range from 5.30 to 6.04 L/kg, whereas the log Kp sediment-pore water was reported (also in figures) to range from 5.0 to 5.40 L/kg. In the study by Kumblad and Bradshaw (2008) water, sediment, and pore water samples were taken in the Forsmark area, Baltic Sea, and analysed for ytterbium. The log Kp sediment-pore water for the upper sediment layer (0-3 cm) was determined to be 3.26 L/kg. 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 ytterbium. Log Kp values ranged from 5.58 to 6.36 L/kg, the mean being 6.09 L/kg. Chen et al. (1996) performed a multitracer experiment to investigate the adsorptive behaviour of ytterbium and other lanthanides to marine sediments and obtained log Kp values for ytterbium of 4.63 and 4.60 L/kg for deep-sea and near-shore sediment in artificial seawater, respectively. Finally, Zhang et al. (1998) sampled sediment and (filtered) seawater at 8 sampling sites in the Yangtze river and analysed the samples for ytterbium. Log Kp sediment-water values were calculated from the results obtained for paired samples and ranged between 5.48 and 5.60 L/kg, the mean being 5.56 L/kg. To determine a final key value, a single average (arithmetic mean) log Kp value was retained for each study. Pore water-based and surface water-based data were however not lumped, individual average values (arithmetic mean) were retained for this. The 10th, 50th and 90th percentile of the retained values was 4.48, 5.34 and 5.71 L/kg, respectively. The median of 5.34 L/kg was taken as key log Kp for sediment-water partitioning of ytterbium.

For suspended matter, five studies were identified as useful. In the study of Censi et al. (2005), samples of suspended matter and (filtered) seawater were taken from various sampling sites in the western Gulf of Thailand and analysed for ytterbium. Log Kp suspended matter-water values were calculated from the results obtained for paired samples and ranged between 5.02 and 6.32 L/kg, the mean being 5.78 L/kg. In a similar study by Censi et al. (2004), samples of suspended matter and (filtered) seawater were taken from two sampling locations in the Ionian Sea and three sampling locations in the Strait of Sicily. Based on the results of this study, log Kp values were calculated ranging from 3.66 to 5.16 L/kg, the mean being 4.09 L/kg. Moermond et al. (2001) determined ytterbium concentrations in surface water and suspended matter samples from six locations along the Rhine-Meuse estuary (the Netherlands). The log Kp value calculated based on the results of this study was 5.81 L/kg. Zhang et al. (1998) took samples of suspended matter and (filtered) seawater from 8 sampling sites in the Yangtze river and analysed the samples for ytterbium. Log Kp suspended matter-water values were calculated from the results obtained for paired samples and ranged between 5.46 and 5.64 L/kg, the mean being 5.59 L/kg. Finally, in the study by Kumblad and Bradshaw (2008), water and suspended matter samples were taken in the Forsmark area, Baltic Sea, and analysed for ytterbium. The log Kp suspended matter-water was reported to be 4.81 L/kg, using the detection limit as aquatic ytterbium concentration since ytterbium was not detectable in the water phase. Therefore, the latter value was not taken into account for calculation of the key log Kp suspended matter-water. Because there is a limited amount of studies included in the weight of evidence approach for suspended matter, the arithmetic mean was calculated of the (arithmetic) mean values from Moermond et al. (2001), Censi et al. (2004, 2005) and Zhang et al. (1998), resulting in an average log Kp value of 5.32 L/kg, which is considered as the key value for characterising the distribution of ytterbium between suspended matter and water.

For soil, only one study was identified as useful. In the study of Sheppard et al. (2007), partitioning of indigenous ytterbium in 107 Canadian soil samples between soil and water under conditions near field capacity was investigated. The log Kp values obtained ranged from 2.45 to 5.56 L/kg. The mean log Kp value for ytterbium was determined to be 4.30 L/kg (geometric mean of Kp values or arithmetic mean of log Kp values). Since only one study is available, this mean value can be considered as the key value for characterising the distribution of ytterbium between soil and water.