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Environmental fate & pathways

Adsorption / desorption

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Description of key information

The log Kp values for read-across substance, bismuth, are detailed below.

Key value for chemical safety assessment

Other adsorption coefficients

Type:
log Kp (solids-water in suspended matter)
Value in L/kg:
5.66

Other adsorption coefficients

Type:
log Kp (solids-water in sediment)
Value in L/kg:
3.84

Other adsorption coefficients

Type:
log Kp (solids-water in soil)
Value in L/kg:
2.83

Additional information

Three reliable studies (all Klimisch 2) are available for adsorption/desorption of 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 L/kg for sediments from a lake in Sweden and a mean log Kp of 3.28 L/kg for freshwater rivers in Argentina (range: 2.75-3.80 L/kg). 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 L/kg dw.

One study reports reliable data for Kp of suspended matter, with a log Kp value of 5.62 L/kg for suspended matter from the St Lawrence river (Canada) and a log Kp value of 5.71 L/kg 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 L/kg dw.

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/].