Colloid-facilitated transport

Colloid-facilitated transport designates a transport process by which colloidal particles serve as transport vector[1] of diverse contaminants in the surface water (sea water, lakes, rivers, fresh water bodies) and in underground water circulating in fissured rocks[2] (limestone, sandstone, granite, ...). The transport of colloidal particles in surface soils and in the ground can also occur, depending on the soil structure, soil compaction, and the particles size, but the importance of colloidal transport was only given sufficient attention during the 1980 years.[3] Radionuclides, heavy metals, and organic pollutants, easily sorb onto colloids suspended in water and that can easily act as contaminant carrier.

Various types of colloids are recognised: inorganic colloids (clay particles, silicates, iron oxy-hydroxides, ...), organic colloids (humic and fulvic substances). When heavy metals or radionuclides form their own pure colloids, the term "Eigencolloid" is used to designate pure phases, e.g., Tc(OH)4, Th(OH)4, U(OH)4, Am(OH)3. Colloids have been suspected for the long range transport of plutonium on the Nevada Nuclear Test Site. They have been the subject of detailed studies for many years. However, the mobility of inorganic colloids is very low in compacted bentonites and in deep clay formations[4] because of the process of ultrafiltration occurring in dense clay membrane.[5] The question is less clear for small organic colloids often mixed in porewater with truly dissolved organic molecules.[6][7]

See also

References
  1. Frimmel, Fritz H.; Frank von der Kammer; Hans-Curt Flemming (2007). Colloidal transport in porous media (1 ed.). Springer. p. 292. ISBN 978-3-540-71338-8.
  2. Alonso, U.; T. Missana; A. Patelli; V. Rigato (2007). "Bentonite colloid diffusion through the host rock of a deep geological repository". Physics and Chemistry of the Earth, Parts A/B/C. 32 (1–7): 469–476. Bibcode:2007PCE....32..469A. doi:10.1016/j.pce.2006.04.021. ISSN 1474-7065.
  3. de Jonge, L.W.; C. Kjaergaard; P. Moldrup (2004). "Colloids and colloid-facilitated transport of contaminants in soils: An introduction". Vadose Zone Journal. 3 (2): 321–325. doi:10.2113/3.2.321.
  4. Voegelin, A.; Kretzschmar, R. (December 2002). "Stability and mobility of colloids in Opalinus Clay". Technischer Bericht / NTB. Nagra Technical Report 02-14. Institute of Terrestrial Ecology, ETH Zürich: 47. ISSN 1015-2636.
  5. "Diffusion of colloids in compacted bentonite". Archived from the original on 2009-03-04. Retrieved 2009-02-12.
  6. Wold, Susanna; Trygve Eriksen (2007). "Diffusion of humic colloids in compacted bentonite". Physics and Chemistry of the Earth, Parts A/B/C. 32 (1–7): 477–484. Bibcode:2007PCE....32..477W. doi:10.1016/j.pce.2006.05.002. ISSN 1474-7065.
  7. Durce, D.; Salah, S.; Maes, N. (2016). Presence and mobility of colloidal particles. COVRA report N° OPERA-PU-SCK614 (Report). Archived from the original on 2017-04-09. Retrieved 2017-04-08.

Software programs for modeling colloid-facilitated transport
  • The Geochemist's Workbench
  • Hydrus


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