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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:
Log Kp values calculated from analysed concentrations of Y 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:
>= 4.4 - <= 6.02 L/kg
Remarks on result:
other: range for all samples
Phase system:
suspended matter-water
Type:
log Kp
Value:
5.26 L/kg
Remarks on result:
other: mean value all samples
Station number Y (nmol/L) Y (mg/L) Y in SPM (mg/kg) Kp SPM (L/kg)

log Kp

(L/kg)

128a 1.38E+00 1.23E-04 1.13E+01 9.24E+04 4.97E+00
129a 5.50E-01 4.89E-05 1.30E+01 2.66E+05 5.42E+00
130a 3.34E+00 2.97E-04 1.60E+01 5.38E+04 4.73E+00
131a 5.70E-01 5.07E-05 2.12E+01 4.17E+05 5.62E+00
132a 2.55E+00 2.27E-04 1.44E+01 6.34E+04 4.80E+00
133a 3.04E+00 2.70E-04 2.35E+01 8.68E+04 4.94E+00
134a 3.18E+00 2.83E-04 2.13E+01 7.53E+04 4.88E+00
135a 1.49E+00 1.32E-04 4.98E+00 3.76E+04 4.58E+00
138a 3.72E+00 3.31E-04 1.73E+01 5.24E+04 4.72E+00
140a 3.20E-01 2.84E-05 1.84E+01 6.45E+05 5.81E+00
141a 3.60E-01 3.20E-05 1.59E+00 4.96E+04 4.70E+00
142a 4.70E-01 4.18E-05 1.74E+01 4.17E+05 5.62E+00
143a 9.60E-01 8.53E-05 1.56E+01 1.83E+05 5.26E+00
144a 4.97E+00 4.42E-04 1.51E+01 3.42E+04 4.53E+00
145a 9.60E-01 8.53E-05 2.79E+01 3.27E+05 5.51E+00
146a 1.77E+00 1.57E-04 1.56E+01 9.93E+04 5.00E+00
147a 3.80E-01 3.38E-05 1.36E+01 4.01E+05 5.60E+00
148a 4.30E-01 3.82E-05 1.32E+01 3.45E+05 5.54E+00
149a 2.00E-01 1.78E-05 1.85E+01 1.04E+06 6.02E+00
150a 3.70E-01 3.29E-05 2.84E+01 8.62E+05 5.94E+00
151a 5.60E-01 4.98E-05 1.28E+01 2.56E+05 5.41E+00
152a 3.00E-01 2.67E-05 NA
153a 4.40E-01 3.91E-05 1.55E+01 3.97E+05 5.60E+00
128b 5.20E-01 4.62E-05 1.47E+01 3.17E+05 5.50E+00
129b 4.20E-01 3.73E-05 2.43E+01 6.51E+05 5.81E+00
140b 3.10E-01 2.76E-05 3.32E+00 1.20E+05 5.08E+00
141b 3.40E-01 3.02E-05 2.59E+01 8.58E+05 5.93E+00
147b 8.20E-01 7.29E-05 1.35E+01 1.85E+05 5.27E+00
148b 4.70E-01 4.18E-05 1.66E+01 3.97E+05 5.60E+00
150b 5.70E-01 5.07E-05 NA
128c 3.80E-01 3.38E-05 2.60E+01 7.69E+05 5.89E+00
129c 9.10E-01 8.09E-05 2.18E+01 2.70E+05 5.43E+00
130c 7.90E-01 7.02E-05 1.34E+01 1.90E+05 5.28E+00
131c 7.50E-01 6.67E-05 2.42E+01 3.63E+05 5.56E+00
140c 7.30E-01 6.49E-05 NA
141c 4.70E-01 4.18E-05 1.76E+00 4.22E+04 4.63E+00
142c 1.03E+00 9.16E-05 2.34E+01 2.56E+05 5.41E+00
148c 5.20E-01 4.62E-05 2.56E+00 5.53E+04 4.74E+00
149c 4.40E-01 3.91E-05 5.38E+00 1.38E+05 5.14E+00
150c 4.20E-01 3.73E-05 3.95E+00 1.06E+05 5.02E+00
151c 9.30E-01 8.27E-05 1.57E+01 1.89E+05 5.28E+00
152c 5.50E-01 4.89E-05 1.23E+00 2.52E+04 4.40E+00
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 Y. Log Kp suspended matter-water values were calculated from the results obtained for paired samples and ranged between 4.40 and 6.02 L/kg, the mean being 5.26 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 Y).
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:
5.18 L/kg
Temp.:
25 °C
pH:
7.5
Matrix:
deep-sea sediment
Phase system:
sediment-water
Type:
log Kp
Value:
4 L/kg
Temp.:
25 °C
pH:
7.5
Matrix:
near-shore sediment
Conclusions:
In this multitracer experiment, the log Kp for Y for deep-sea and near-shore sediment in artificial seawater was determined to be 5.18 and 4.0 L/kg, respectively.
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:
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.
Phase system:
soil-water
Type:
log Kp
Value:
4.72 L/kg
Remarks on result:
other: untreated soil
Adsorption and desorption constants:
Log Kp soil in untreated soil was 4.72 L/kg.
Log Kp soil in treated soil (CaCO3 or both CaCO3 and organic matter removed) was 3.97 L/kg.
Details on results (Batch equilibrium method):
In this study, the log Kp for yttrium in a soil-water system was determined to be 4.72 L/kg (untreated soil). Since the log Kp obtained in soil treated to remove CaCO3 or both CaCO3 and organic matter was 3.97 L/kg, it was concluded that adsorption of yttrium is not only determined by the oxides and silicates but that CaCO3 also affects adsorption.
Conclusions:
In this study, adsorption of Y was investigated using cultivated Chinese soil and radiolabeled Y. The log Kp in untreated soil was determined to be 4.72 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 and pore water samples were collected from two rivers which receive wastewater from urban Hanoi (Vietnam) and analysed for Y.
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 Y concentration in sediment by Y concentration in pore water (L/kg).
Phase system:
solids-water in sediment
Type:
log Kp
Value:
>= 5.04 - <= 6.57 L/kg
% Org. carbon:
>= 1.2 - <= 10.6
Remarks on result:
other: range for all paired samples, precipitation processes may have been involved
Remarks:
actual range reported was 5.04 to > 6.57 L/kg
Details on results (Batch equilibrium method):
The upper boundary of the range of log Kp values reported in the publication was represented by an unbounded value (> 6.57 L/kg) because the yttrium pore water concentration was below the limit of detection
.
The organic carbon concentration had a significant effect on the sediment Y concentrations, indicating that organic carbon is important for retention controlled by sorption processes.
Conclusions:
In this study, samples of sediment and pore water were taken along two rivers receiving wastewater from Hanoi, Vietnam, and analysed for Y. Log Kpsediment-pore water values of 5.04 to > 6.57 L/kg were reported. However, reliability is restricted, because precipitation processes may have been involved in sediment next to sorption processes, yielding overestimated partitioning coefficients. The unbound value should not be used 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:
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:
4.23 L/kg
Remarks on result:
other: mean for all soil samples tested (70 for Y)
Phase system:
solids-water in soil
Type:
log Kp
Value:
>= 2.56 - <= 5.88 L/kg
Remarks on result:
other: range for all soil samples tested (70 for Y)
Conclusions:
In this study, partitioning of indigenous Y in 70 Canadian soil samples between soil and water under conditions near field capacity was investigated. The mean log Kp for yttrium was determined to be 4.23 L/kg. The range of log Kp values was 2.56 to 5.88 L/kg.
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:
Log Kp values reported in a study in which soil and pore water samples (of re-wetted soil samples) of 59 soils from southern Ontario were analysed for yttrium.
GLP compliance:
not specified
Type of method:
other: field study
Media:
soil
Radiolabelling:
no
Test temperature:
Ambient, not specified.
Analytical monitoring:
yes
Details on sampling:
- 59 field locations in Southern Ontario were identified.
- Within each field 3 random sampling sites were identified and at each sampling site 8 soil profiles were sampled at 0-15 cm, 15-30 cm, and 30-60 cm depths.
- Samples were composited for each depth, i.e. per field location, 3 composite samples corresponding to the 3 depths were obtained for analysis.
- Further information in this entry is given only for the 0-15 cm samples.
Details on matrix:
Min, max, and median for 59 soils sampled at 0-15 cm depth:
Clay content: 6.3-56% (median 26%)
Sand content: 3.2-82% (median 27%)
Carbon content: 0.67-3.9% (median 2.2%)
pH (water): 5.9-8.2 (median 7.6)
Details on test conditions:
Study using field samples.
Computational methods:
Solid/liquid partition coefficients (L/kg) for the 0-15 cm depth soil samples were computed as the concentration in aqua regia extraction (mg/kg) divided by the concentration in pore water (mg/L).
Phase system:
solids-water in soil
Type:
log Kp
Value:
4.34 L/kg
Remarks on result:
other: mean value for all soils sampled

Y in aqua regia extract of soil solids (mg/kg):

median: 15

min: 6.4

max: 27

Y in pore water (µg/L):

median: 0.55

min: 0.2

max: 5.63

Conclusions:
In this study, samples of soil and pore water (from re-wetted soil samples) were taken from 59 different soils. The mean log Kp soil-water was reported to be 4.34 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 Y 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:
no
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:
>= 5.2 - <= 6.19 L/kg
Remarks on result:
other: range for all paired samples
Phase system:
sediment-water
Type:
log Kp
Value:
5.82 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 Y. Log Kp values ranged from 5.20 to 6.19 L/kg, the mean being 5.82 L/kg.
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:
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.
Phase system:
soil-water
Type:
log Kp
Value:
4.67 L/kg
Temp.:
25 °C
% Org. carbon:
1.72
Remarks on result:
other: calcareous soil
Phase system:
soil-water
Type:
log Kp
Value:
4.76 L/kg
Temp.:
25 °C
% Org. carbon:
3.28
Remarks on result:
other: red earth
Conclusions:
In this multitracer study, the adsorption of Y to two Chinese soils, a calcareous soil and a sandy red earth, was investigated in a batch equilibrium experiment. Log Kp values were 4.67 and 4.76 L/kg for the calcareous soil and red earth, respectively.
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:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
GLP compliance:
not specified
Type of method:
batch equilibrium method
Media:
soil
Radiolabelling:
no
Test temperature:
ca. 20°C
Analytical monitoring:
yes
Details on sampling:
Soils:
Four Chinese cultivated soils were collected from Jiangxi Province, southern China (Yingtan soil), Beijing, northern China (Beijing soil), and Heilongjiang Province, northeastern China (Tongjiang and Haerbin soil). All samples taken from surface layer 0-20 cm. Air dried, ground, 1-mm sieved.
Experiment:
Sampling after 1 or 20 weeks of incubation.
Samples filtered 0.45 µm.
Details on matrix:
- Yingtan: ultisol, 19.5% sand, 35.2% silt, 45.3% clay, CEC 14.24 cmol/kg, pH 5.43, 1.53% oc.
- Beijing: mollisol, 37.6% sand, 51.6% silt, 10.8% clay, CEC 15.71 cmol/kg, pH 8.28, 1.35% oc.
- Tongjiang: mollisol, 16.3% sand, 65.5% silt, 18.2% clay, CEC 15.20 cmol/kg, pH 7.16, 5.28% oc.
- Haerbin: mollisol, 9.8% sand, 62.8% silt, 27.4% clay, CEC 26.00 cmol/kg, pH 7.23, 36.40% oc.
Details on test conditions:
Batch equilibrium method.
50.0 mg soil and 10 mL of solution added to 25-mL polypropylene vials.
Final Y concentration in solution initially 1.0 mmol/L, in a background electrolyte solution of 10 mmol/L Ca(NO3)2.
pH values adjusted to 6.0 by adding small amount of Ca(OH)2 solution.
Samples shaken for 24 h at 20°C, and then incubated for either 1 or 20 weeks.
Computational methods:
Kp values were calculated starting from reported values of metal sorbed at the end of the sorption phase. Y remaining in solution was then calculated. Soil:solution ratio was taken into account.
Phase system:
soil-water
Type:
log Kp
Value:
>= 3.61 - <= 4.47 L/kg
Temp.:
20 °C
% Org. carbon:
>= 1.35 - <= 36.4
Remarks on result:
other: range
Phase system:
soil-water
Type:
log Kp
Value:
4.16 L/kg
Temp.:
20 °C
% Org. carbon:
>= 1.35 - <= 36.4
Remarks on result:
other: average
Adsorption and desorption constants:
Desorption kinetics were described using three models, first-order, two site first-order, and log-normal distribution first-order kinetics models. The latter two resulted in excellent fits.
Conclusions:
In this study, sorption of Y was studied in 4 Chinese soils using a batch equilibrium method. Log Kp values ranged from 3.61 to 4.47 L/kg, and the average log Kp was 4.16 L/kg. Desorption was also studied, and indicated the effect of pH on desorption (higher at low pH, lower at high pH).
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
Remarks:
Reliable with restrictions because data needed for Kp calculation were taken from figures.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Water soluble and total rare earth elements (including yttrium) were determined in nine Chinese soils.
GLP compliance:
not specified
Type of method:
other: study using sequential extraction on field samples
Media:
soil
Radiolabelling:
no
Test temperature:
not reported
Analytical monitoring:
yes
Details on sampling:
Soils:
- Nine Chinese cultivated soils collected from Jiangxi Province (Yingtan soil), Beijing, northern China (Beijing soil), Hubei Province, central China (Wuhan soil), Shandong Province, eastern China (Rongcheng soil), Heilongjiang Province, northeastern China (Heilongjiang soil), Guizhou Province, southeast China (Anshun soil), Shanghai, east China (Shanghai soil), Fujian Province, southeast China (Chaozhou soil), and Shanxi Province, northern China (Changzhi soil).
- Samples taken from cultivated surface layer (0-20 cm), air dried, ground, and 1-mm sieved.
Details on matrix:
- Beijing: mollisol, 37.6% sand, 51.6% silt, 10.8% clay, CEC 15.7 cmol/kg, pH 6.90, 0.78% oc.
- Yingtan: ultisol, 19.5% sand, 38.7% silt, 42.4% clay, CEC 14.2 cmol/kg, pH 4.56, 0.89% oc.
- Helongjiang: mollisol, 9.8% sand, 62.8% silt, 27.4% clay, CEC 26.0 cmol/kg, pH 7.35, 3.71% oc.
- Rongcheng: mollisol, 89.7% sand, 3.91% silt, 6.40% clay, CEC 9.82 cmol/kg, pH 6.08, 0.39% oc.
- Wuhan: alfisol, 52.9% sand, 21.4% silt, 25.7% clay, CEC 22.8 cmol/kg, pH 6.73, 1.72% oc.
- Anshun: cambisol, 37.2% sand, 32.8% silt, 30.1% clay, CEC 51.3 cmol/kg, pH 6.29, 6.76% oc.
- Shanghai: luvisol, 21.4% sand, 65.5% silt, 13.2% clay, CEC 36.6 cmol/kg, pH 5.53, 3.02% oc.
- Chaozhou: ferralisol, 29.6% sand, 33.7% silt, 36.7% clay, CEC 18.1 cmol/kg, pH 5.96, 1.81% oc.
- Changzhi: luvisol, 24.6% sand, 52.3% silt, 18.1% clay, CEC 21.9 cmol/kg, pH 7.29, 4.12% oc.
Details on test conditions:
Water-soluble REEs were obtained by shaking 1.0 g of dried soil with 5.0 mL of deionised distilled water in 50 mL polypropylene centrifuge tubes for 24 h. After centrifuging at 4000g for 30 min, the supernatant was filtered with 0.45 µm membrane.
Next to water-soluble REEs, total REEs were determined.
Computational methods:
A range of Kp values was obtained by dividing total Y concentration in the soil under consideration (mg/kg) by the minimum and maximum of the range of water soluble Y reported in figures (mg/kg).
Phase system:
soil-water
Type:
log Kp
Value:
>= 2.42 - <= 3.87 L/kg
% Org. carbon:
>= 0.39 - <= 6.76
Remarks on result:
other: range for all nine soils
Phase system:
soil-water
Type:
log Kp
Value:
3.12 L/kg
% Org. carbon:
>= 0.39 - <= 6.76
Remarks on result:
other: average for all nine soils
Conclusions:
In this study, nine Chinese soils were sampled and total and water soluble Y concentrations determined in the laboratory. This resulted in a range of log Kp soil values of 2.42 to 3.87 L/kg, the average being 3.12 L/kg.
Endpoint:
adsorption / desorption, other
Remarks:
microcosm 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 microcosm study was performed in which concentrations of Y in water and sediment were also monitored.
GLP compliance:
not specified
Type of method:
other: microcosm study
Media:
sediment
Radiolabelling:
no
Test temperature:
Water temperature 22 +/- 1°C
Analytical monitoring:
yes
Details on sampling:
- Water and sediment sampled at 12 and 24 h and 2, 4, 8, 12 and 16 d.
- Water was filtered 0.45 µm.
- Sediment samples were washed with deionised water and dried by air. Then 0.5 g of dried sample was digested with Na2O2 at 700°C and passed through cation-exchange columns.
- Final solutions of all samples brought to 5 mL with 7% HCl.
Details on matrix:
Sediment from eutrophic lake (Xuanwu Lake, Nanjing, China).
Sediment samples were dried by air before adding into aquarium.
Details on test conditions:
Microcosm study using water and sediment from a typical eutrophic lake - Xuanwu Lake in Nanjing, China.
Organisms: duckweeds (Sperollela polyrrhiza), crustaceans (Daphnia magna), goldfish (Carassius auratus), shellfish (Bellamya aeruginosa).
After the system has equilibrated for 1 week, the experiment was initiated by spiking mixed REEs stock solutions (a mixture of five REEs with 1.00 mg/mL each: La(NO3)3.6H2O, CeCl3.7H2O, SmCl3.nH2O, Gd2O3 and Y2O3) into the aquarium to 1 mg/L.
The pH was kept at 6.5-6.8 because rare earth elements would precipitate under alkaline conditions.
Computational methods:
Kp sediment values were calculated dividing concentrations in sediment (mg/kg) by concentrations in water (mg/L).
Phase system:
sediment-water
Type:
log Kp
Value:
3.48 L/kg
Temp.:
22 °C
Remarks on result:
other: Value after 16 days
Details on results (Batch equilibrium method):
Distribution of Y was 87.80% in sediment, 11.69% in water, and 0.51% in biota.
Conclusions:
In this microcosm study, water and sediment Y concentrations were monitored for up to 16 days. Based on the concentrations reported for 16 days, a log Kp sediment of 3.48 L/kg could be calculated. Data were taken from figures.
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 Y 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 laboratory 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:
Lab 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:
5.18 L/kg
Remarks on result:
other: laboratory (sediment and surface water)
Phase system:
sediment-water
Type:
log Kp
Value:
6.04 L/kg
Remarks on result:
other: field (sediment and surface water)
Phase system:
solids-water in sediment
Type:
log Kp
Value:
4.65 L/kg
Remarks on result:
other: laboratory (sediment and pore water)
Phase system:
solids-water in sediment
Type:
log Kp
Value:
5.35 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 Y to sediment was evaluated by determining Y 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 4.65 and 5.35 L/kg when based on sediment and pore water concentrations in laboratory and field, respectively, and 5.18 and 6.04 L/kg when based on sediment and surface water concentrations in laboratory and field, respectively.
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 yttrium to particulate matter is used from experiments performed in the laboratory (e.g., multitracer experiments of Chen et al. (1996) in sediments and of Tao et al. (2000) and Du et al. (1998) in soils; equilibrium partitioning experiments of Sheppard et al. (2007, 2009) in Canadian soil samples and of Wen et al. (2002, 2006) in Chinese soils; microcosm experiment of Yang et al. (1999)) as well as from field or mixed field/laboratory experiments, in which field samples of particulate matter and surface/pore water were analysed for Y. In the multitracer studies, Y in a multitracer solution was used as 'test item'. In the microcosm experiment of Yang et al. (1999), Y2O3 was used as test item in a mixture with other rare earth oxides. Wen et al. (2002) used yttrium trinitrate as test item. In the remaining studies, there was no specific test item, as Y present in field samples was analysed. Therefore, in theory, all studies except the study of Wen et al. (2002) should be considered as read across studies. For these read across studies, the information is summarised below. An elemental approach was followed to cover this endpoint, lumping the data from all available studies.
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Phase system:
sediment-water
Type:
log Kp
Value:
>= 3.48 - <= 6.57 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
Remarks:
the upper value of 6.57 L/kg was reported as being > 6.57 L/kg (Marcussen et al., 2008)
Phase system:
suspended matter-water
Type:
log Kp
Value:
>= 4.4 - <= 6.02 L/kg
Remarks on result:
other: range of log Kp values for suspended matter-water obtained in the read across study
Phase system:
soil-water
Type:
log Kp
Value:
>= 2.42 - <= 5.88 L/kg
Remarks on result:
other: range of log Kp values for soil-water or soil-pore water (at or near field capacity) in the read across studies

Description of key information

A total of twelve 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 5.02 L/kg for sediment-water, a log Kp of 5.26 L/kg for suspended matter-water, and a log Kp of 4.34 L/kg for soil-water.

Key value for chemical safety assessment

Other adsorption coefficients

Type:
other: log Kp sediment-water
Value in L/kg:
5.02

Other adsorption coefficients

Type:
other: log Kp suspended matter-water
Value in L/kg:
5.26

Other adsorption coefficients

Type:
other: log Kp soil-water
Value in L/kg:
4.34

Additional information

In total, twelve 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, five studies were included in the weight of evidence approach. Sneller et al. (2000) reported log Kp values obtained by Stronkhorst and Yland (1998) of 4.65 and 5.35 L/kg when based on pore water concentrations in lab and field, respectively, and 5.18 and 6.04 L/kg when based on surface water concentrations in lab and field, respectively. 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 yttrium. Log Kp values ranged from 5.20 to 6.19 L/kg, the mean being 5.82 L/kg. Chen et al. (1996) performed a multitracer experiment to investigate the adsorptive behaviour of yttrium and lanthanides to marine sediments and obtained log Kp values for yttrium of 5.18 and 4.0 L/kg for deep-sea and near-shore sediment in artificial seawater, respectively. Marcussen et al. (2008) sampled sediment and pore water along two rivers receiving wastewater from Hanoi, Vietnam. Log Kp values for sediment-pore water for these samples were reported to range from 5.04 to > 6.57 L/kg. However, because precipitation processes may have been involved in sediment next to sorption processes, partitioning coefficients may have been overestimated. Moreover, the upper boundary of the range is an unbound value due to a pore water concentration below the detection limit. Therefore only the lower boundary of the reported range was included in the calculation of a key value for partitioning between sediment and water. Finally, the microcosm study of Yang et al. (1999) yielded a log Kp sediment of 3.48 L/kg when using the data for the 16-d sampling point. 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 4.03, 5.02 and 5.72 L/kg, respectively. The median of 5.02 L/kg was taken as key log Kp for sediment-water partitioning of yttrium.

For suspended matter, only one useful study was identified. In this study, Censi et al. (2005) analysed samples of suspended matter and (filtered) seawater taken from various sampling sites in the western Gulf of Thailand. Log Kp suspended-matter values were calculated from the results obtained for paired samples and ranged between 4.40 and 6.02 L/kg, the mean being 5.26 L/kg. This mean value was considered as the key log Kp for suspended matter-water partitioning of yttrium.

For soil, a total of six studies was included in the weight of evidence approach. Wen et al. (2006) gathered samples of nine Chinese soils and analysed total and water soluble yttrium concentrations in the laboratory, which resulted in a range of log Kp values of 2.42 to 3.87 L/kg. Based on data from Du et al. (1998), in which adsorption of yttrium was investigated using cultivated Chinese soil and radiolabeled yttrium, a log Kp of 4.72 L/kg could be obtained. Two other batch equilibrium experiments with Chinese soils yielded similar log Kp values of 4.67 L/kg (calcareous soil) and 4.76 L/kg (red earth) (Tao et al., 2000) and 3.61 to 4.47 L/kg (Wen et al., 2002). In the study of Sheppard et al. (2007), partitioning of indigenous yttrium in 70 Canadian soil samples between soil and water under conditions near field capacity was investigated. The log Kp values obtained ranged from 2.56 to 5.88 L/kg. A later study from the same authors (Sheppard et al., 2009) reported an average log Kp of 4.34 L/kg for 59 Canadian soil samples. To determine a final key value, a single average (arithmetic mean) log Kp value was retained for each study. Retaining a log Kp value per soil (which is preferred) was not possible since not all studies reported log Kp values for all individual soils studied. The 10th, 50th and 90th percentile of the retained values was 3.74, 4.34 and 4.74 L/kg, respectively. The median of 4.34 L/kg was taken as key log Kp for soil-water partitioning of yttrium.

Overall, the obtained adsorption coefficients were similar as for many other metals. Adsorption to soil appears to be mild, however a stronger adsorption of yttrium to suspended matter and sediment seems to occur.