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Environmental fate & pathways

Adsorption / desorption

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Endpoint:
adsorption / desorption, other
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No guideline study, but well performed and well documented. Paired observations in river water and sediment. Relatively uncontaminated systems.
Justification for type of information:
See read-across justification attached below.
Reason / purpose:
read-across source
Qualifier:
no guideline followed
Principles of method if other than guideline:
Monitoring of ambient Bismuth concentrations in 27 unpolluted sediments from Argentina.
GLP compliance:
not specified
Type of method:
other: monitoring study
Media:
sediment
Radiolabelling:
no
Test temperature:
Not reported.
Analytical monitoring:
yes
Details on sampling:
At each sample site, when possible, samples of surface water, river sediment and plants were collected during the spring. Samples for elemental analyses were passed through a 0.45 gm filter and acidified immediately with HNO3 (2%). River sediments: Stream sediment samples were sieved to less than 200 gm in the field and dried at 40 °C in an oven in the laboratory.

Computational methods:
Kp (L/kg dw) = Bi concentration in sediment (mg Bi/kg dw) / Bi concentration in water (mg Bi/L)
Phase system:
solids-water in sediment
Type:
log Kp
Value:
>= 2.75 - <= 3.8
Remarks on result:
other: geometric mean of 3.28
Adsorption and desorption constants:
Kp (solids-water in sediment) range is 562-6333 L/kg dw with geometric mean of 1887 L/kg dw.
Concentration of test substance at end of adsorption equilibration period:
Concentration solid phase = <0.01-1.9 mg Bi/kg dw
Concentration solution phase = <0.01-0.89 µg Bi/L
Validity criteria fulfilled:
not specified
Conclusions:
No guideline followed, but study well performed and well documented. Adsorption experiment resulted in a log Kp (solids-water in sediment) range of 2.75-3.80 with a geometric mean of 3.28.
Endpoint:
adsorption / desorption, other
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: Kd values derived from graphs, no sufficient documentation.
Justification for type of information:
Please see read-across justification attached below.
Reason / purpose:
read-across source
Qualifier:
no guideline followed
Principles of method if other than guideline:
Adsorption of bismuth was measured in a soils at concentrations closely corresponding to those expected for field conditions.
GLP compliance:
not specified
Type of method:
batch equilibrium method
Media:
soil
Radiolabelling:
yes
Test temperature:
Not reported.
Analytical monitoring:
yes
Details on test conditions:
TEST CONDITIONS
- 4 adsorption/desorption experiments conducted (a-e):
a) Ambient Bi, solid phase: sandy top soil, pH H2O: 5, OM%: 3.5, Clay%: 0, CEC: 22 cmolc/kg.
b) Ambient Bi, solid phase: sandy loam top soil, pH H2O: 8, OM%: 2.5, Clay%: 20, CEC: 16 cmolc/kg.
c) Sewage sludge, solid phase: sandy top soil, pH H2O: 5, OM%: 3.5, Clay%: 0, CEC: 22 cmolc/kg.
d) Sewage sludge, solid phase:sandy loam top soil, pH H2O: 8, OM%: 2.5, Clay%: 20, CEC: 16 cmolc/kg.


-Soil:solution ratio with distilled H2O or salt solutions (0.035 and 0.00035 M): 5g soil, 25 ml solution.
-3 days equilibration
Computational methods:
Kp (L/kg dw) = Bi concentration in soil (mg Bi/kg dw) / Bi concentration in water (mg Bi/L)
Phase system:
solids-water in soil
Type:
log Kp
Value:
2.7 - 3 L/kg
Remarks on result:
other: desorption, sandy top soil
Phase system:
solids-water in soil
Type:
log Kp
Value:
3.7 - 4 L/kg
Remarks on result:
other: desorption, sandy loam top soil
Phase system:
solids-water in activated sewage sludge
Type:
log Kp
Value:
0.7 - 2.18 L/kg
Remarks on result:
other: adsorption from sewadge sludge solution, sandy top soil
Phase system:
solids-water in activated sewage sludge
Type:
log Kp
Value:
2.4 - 3 L/kg
Remarks on result:
other: adsorption from sewadge sludge solution, sandy loam top soil
Adsorption and desorption constants:
experiment a: Kp (solids-water in soil) range is 500-1000 L/kg dw.
experiment b: Kp (solids-water in soil) range is 5000-10000 L/kg dw.
experiment c: Kp (solids-water in soil) range is 5-150 L/kg dw.
experiment d: Kp (solids-water in soil) range is 250-1000 L/kg dw.
Concentration of test substance at end of adsorption equilibration period:
Concentration solid phases and Concentration solution phases are not reported.
Statistics:
not reported
Validity criteria fulfilled:
not specified
Conclusions:
No guideline followed, Kd values were derived from graphs, no sufficient documentation. Study is disregarded.
Endpoint:
adsorption / desorption, other
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Study period:
Not specified
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No guideline study, but well performed and well documented study.
Justification for type of information:
See read-across justification attached below.
Reason / purpose:
read-across source
Qualifier:
no guideline followed
Principles of method if other than guideline:
The aim is to assess how much municipal wastewater contributes to the loading of metals in the St. Lawrence River.
GLP compliance:
not specified
Type of method:
other: monitoring study
Media:
other: suspended matter
Radiolabelling:
no
Test temperature:
Not reported.
Analytical monitoring:
yes
Details on sampling:
Water samples were collected directly from the plant well, using a pneumatic pump and acid-washed Teflon tubes. The samples were kept at 4°C in low density polyethylene containers and delivered to the laboratory within 6 h where they were filtered through preweighed 0.45 µm Nuclepore polycarbonate membrane filters. The filters were frozen with their content of suspended matter and the filtrate was acidified with ultrapure nitric acid to pH 2.
Treated urban effluents were collected once a month. Samples were taken proportionally to flow rate during a 24-h period in the middle of the week. The samples were than transported to the laboratory and filtered in the same way as samples collected directly from the plant well.
All material coming in contact with the samples was acid washed. The 0,45 µm pore size polycarbonate membrane filters and polypropylene filter holders were leached for 3 d in dilute nitric acid at room temperature. The low-density polyethylene bottles containing the samples were immersed for successive 3-d periods in concentrated and diluted nitric acids at 50°C, rinsed several times with Milli-Q demineralized water and placed individually within a double layer of plastic bags.
Computational methods:
Kp (L/kg dw) = Bi concentration in suspended matter (mg Bi/kg dw) / Bi concentration in water (mg Bi/L)
Phase system:
solids-water in suspended matter
Type:
log Kp
Value:
5.62 - 5.71
Adsorption and desorption constants:
Kp (suspended matter from the St. Lawrence river) = 414286 L/kg dw
Kp (suspended matter from the effluent of Montreal purification plant) = 510714 L/kg dw
Concentration of test substance at end of adsorption equilibration period:
Suspended matter from the St. Lawrence river:
Concentration solid phase = 0.29±0.11 mg Bi/kg dw
Concentration solution phase = 0.0007±0.0003 µg Bi/l
Suspended matter from the effluent of Montreal purification plant:
Concentration solid phase = 2.86±1.52 mg Bi/kg dw
Concentration solution phase = 0.0056±0.004 µg Bi/L
Validity criteria fulfilled:
yes
Conclusions:
No guideline followed, but study well performed and well documented. Adsorption experiment resulted in a log Kp (solids-water in suspended matter) range of 5.62-5.71 with an average of 5.67.
Endpoint:
adsorption / desorption, other
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Study is a review. Primary studies are not available.
Justification for type of information:
Please see read-across justification below.
Reason / purpose:
read-across source
Qualifier:
no guideline followed
Principles of method if other than guideline:
Adsorption of bismuth in soil and suspended matter.
GLP compliance:
not specified
Type of method:
other: not reported
Media:
sediment
Radiolabelling:
no
Test temperature:
Not reported.
Analytical monitoring:
not specified
Details on test conditions:
Not reported.
Computational methods:
Kp (L/kg dw) = Bi concentration in soil or suspended matter (mg Bi/kg dw) / Bi concentration in water (mg Bi/L)
Phase system:
solids-water in suspended matter
Type:
log Kp
Value:
5.79
Phase system:
solids-water in soil
Type:
log Kp
Value:
2.83
Adsorption and desorption constants:
Kp (solids-water in suspended matter) is 616595 L/kg dw.
Kp (solids-water in soil) is 676 L/kg dw.
Concentration of test substance at end of adsorption equilibration period:
Concentration solid phase and Concentration solution phase are not reported.
Validity criteria fulfilled:
not specified
Conclusions:
Review study; primary data not available. However results for log Kp soil used as tentative value because of lack of other, reliable data. The results for log Kp suspended matter are not used because they are covered by assessment of the original study.
Endpoint:
adsorption / desorption, other
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: Not all paired measurements. No individual data available.
Justification for type of information:
Please see read-across justification attached below.
Reason / purpose:
reference to same study
Reason / purpose:
read-across source
Qualifier:
no guideline followed
Principles of method if other than guideline:
Monitoring of ambient Bismuth concentrations in sediments near a mine site in Korea.
GLP compliance:
not specified
Type of method:
other: monitoring study
Media:
sediment
Radiolabelling:
no
Test temperature:
Not reported.
Analytical monitoring:
yes
Details on sampling:
Sediment and water samples were taken up to 1.5 km downstream from the mine at 50 – 150-m intervals. The sediments were sampled using a
stainless steel trowel. The samples were air-dried at 25 °C for 72 h and then disaggregated, sieved to -10 mesh or <2 mm and ground to a fine powder in a
‘Tema’ mill. This finely milled soil (-80 mesh or <180 mm) was used for chemical analysis and the <2-mm fraction was used for measuring pH (sample:de-ionized water = 1:2.5), organic matter content using the loss-on-ignition method (Ball, 1964), cation exchange capacity and soil texture analysis (Hesse, 1971).
Details on test conditions:
TEST CONDITIONS
- Organic matter %: 1.9-6.9 (geomean: 3.7)
- pH H2O: 3.0-6.7 (geomean: 4.1)
- Clay %: not reported
- CEC: 6.9-16 cmolc/kg (geomean 11.8)

Phase system:
solids-water in sediment
Type:
log Kp
Value:
> 5.21
Adsorption and desorption constants:
Kp (solids-water in sediment) is higher than 161000 L/kg dw.
Concentration of test substance at end of adsorption equilibration period:
Concentration solid phase = 9-462 mg Bi/kg dw with geomean 161 mg Bi/kg dw.
Concentration solution phase = <1 µg Bi/L.
Validity criteria fulfilled:
not specified
Conclusions:
No reliable results: no guideline followed, not all paired measurements, no individual data available. Study is disregarded.
Endpoint:
adsorption / desorption, other
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study not performed according to international guideline but well documented and scientifically acceptable.
Justification for type of information:
Please see read-across justification attached below.
Reason / purpose:
read-across source
Qualifier:
no guideline followed
Principles of method if other than guideline:
Monitoring of ambient Bi concentration in sediment and corresponding pore water from remote lakes in Sweden.
GLP compliance:
not specified
Type of method:
other: monitoring study
Media:
sediment
Radiolabelling:
no
Test temperature:
Not reported.
Analytical monitoring:
yes
Details on sampling:
Sediment cores of some 30 cm were collected in the summer 2002 from the deepest part of 4 lakes in Sweden. Pelagic water samples were taken at 0.5 m, in the thermoclines and some 1.5 m above the sediment water interface. The upper parts of the cores (0–10 cm) were sliced into 1 cm sections while deeper down 3 cm sections were used. Sectioning and phase separations were done in a nitrogen atmosphere. The pore water was recovered after centrifugation at 20,000 g for 30 minutes. The solid phase was freeze dried, homogenised and leached with concentrated nitric acid on a hot plate (sampling 2002) or in a microwave oven. The metals released in these treatments are referred to as the acid-leachable concentration (ALC).
Computational methods:
Kp (L/kg dw) = Bi concentration in sediment (mg Bi/kg dw) / Bi concentration in water (mg Bi/L)
Phase system:
solids-water in sediment
Type:
log Kp
Value:
4.3 - 4.5
Adsorption and desorption constants:
Kp (solids-water in sediment) range is 19950-31620 L/kg dw
Concentration of test substance at end of adsorption equilibration period:
Concentration solid phase = 0.06-1.2 mg Bi/kg dw
Concentration solution phase = 0.85±0.41 µg Bi/L
Statistics:
No information on statistics is given.
Validity criteria fulfilled:
yes
Conclusions:
No guideline followed, but study well performed and well documented. Adsorption experiment resulted in a log Kp (solids-water in sediment) range of 4.3-4.5 with an average of 4.4.

Description of key information

The estimated adsorption coefficient of bismuth subnitrate is in the range 21.7 to 31.82 L/Kg and the log Koc is estimated to be in the range 1.3 to 1.5. The log Kp values for read-across substance, bismuth, are detailed below.

Key value for chemical safety assessment

Koc at 20 °C:
31.82

Additional information

An experimental study was considered to be technically not feasible due to low solubility of bismuth subnitrate in organic solvents. It was therefore considered acceptable to use an approach based upon Quantitative Structural-Activity Relationship (QSAR). The QSAR model of choice was the EPI Suite v4.10 published by the United States Environmental Protection Agency, which has estimated the adsorption coefficient to be 21.7 to 31.82 L/Kg and the log Koc to be 1.3 to 1.5.

Three reliable studies (all Klimisch 2) are available for adsorption/desorption of the read-across substance, bismuth, in sediment and suspended matter. The Kp values are calculated based on paired monitoring data of dissolved elemental Bi concentrations in water and Bi concentration in corresponding sediment or suspended matter. For sediment, 2 reliable Kp values are available: a log Kp of 4.4 for sediments from a lake in Sweden and a mean log Kp of 3.28 for freshwater rivers in Argentina (range: 2.75-3.80). The median of both values was selected for the log Kp solids-water in sediment to be used in the chemical safety assessment: 3.84.

One study reports reliable data for Kp of suspended matter, with a log Kp value of 5.62 for suspended matter from the St Lawrence river (Canada) and a log Kp value of 5.71 for suspended matter from the effluent of a Montreal purification plant. The median of both values was selected for the log Kp solids-water in suspended matter to be used in the chemical safety assessment: 5.66.

No reliable data were identified for adsorption/desorption of Bi substances in soil. Harvey et al. (2007) report a log KP of 2.83 L/kg dw in a review on Kp values for metals, but the original data could not be assessed for their quality (Klimisch 4). A Kp value for soil could also be estimated by comparing the background concentration of Bi in European surface water and soil as reported in the FOREGS database (Salminen et al., 2005), assuming that these median values are relevant for the compartments and represent a state of chemical equilibrium and surface water concentration is a good estimate for pore water concentration in soil. The FOREGS (Forum of European Geological Surveys) Geochemical Baseline Mapping Programs main aim was to provide high quality, multi-purpose environmental geochemical background data for stream water, stream sediment, floodplain sediment, soil, and humus across Europe. A baseline background concentration was defined as the concentration of an element in the present or past corresponding to very low anthropogenic pressure (i.e., close to the natural background). The median and 90th percentile of total Bi concentrations in topsoil samples are <0.5 and 0.7 mg Bi/kg dw and the median and 90th percentile of dissolved Bi concentration in stream water are 0.002 and 0.007 µg Bi/L. This results in log Kp values for solids-water in soil between 5.0 and 5.4 L/kg dw. This is significantly higher than the Kp value for sediment, whereas Kp soil is generally lower than Kp sediment. Therefore, the estimated Kp based on Bi concentrations in soil and surface water is not judged reliable. Although its reliability could not be assessed, the value of 2.83 from the review by Harvey et al. (2007) was selected as a tentative log Kp soil-water in soil for the chemical safety assessment.

Salminen, R. (Chief-editor), Batista, M.J., Bidovec, M. Demetriades, A., De Vivo. B., De Vos, W., Duris, M., Gilucis, A., Gregorauskiene, V., Halamic, J., Heitzmann, P., Lima, A., Jordan, G., Klaver, G., Klein, P., Lis, J., Locutura, J., Marsina, K., Mazreku, A., O'Connor, P.J., Olsson, S.Å., Ottesen, R.-T., Petersell, V., Plant, J.A., Reeder, S., Salpeteur, I., Sandström, H., Siewers, U., Steenfelt, A., Tarvainen, T., 2005. Geochemical Atlas of Europe. Part 1 – Background Information, Methodology and Maps. Geological Survey of Finland, Espoo, Finland, 526 pp. ISBN 951-690-921-3 [also available at: http://www.gtk.fi/publ/foregsatlas/].


Other adsorption coefficient indicated as dimensionless:
- log Kp (solids-water in suspended matter) ,5.66
- log Kp (solids-water in sediment) ,3.84
- log Kp (solids-water in soil) ,2.83

[LogKoc: 1.5]