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- Title
Colloid Release from Soil Aggregates: Application of Laser Diffraction.
- Authors
Vendelboe, A. L.; Moldrup, P.; Schjønning, P.; Oyedele, D. J.; Jin, Y.; Scow, K. M.; de Jonge, L. W.
- Abstract
The content of water-dispersible colloids (WDC) has a major impact on soil functions and structural stability. In addition, the presence of mobile colloids may increase the risk of colloid-facilitated transport of strongly sorbing environmental contaminants. The WDC content was measured in 39 soils, using laser diffraction, by agitating the samples using a wet-dispersion unit. This approach eliminated the need for long sedimentation times required by the more classical end-over-end shaking approach and provided information about the time-dependent release of WDC. The total clay content of the soils ranged from 0.1 to 0.44 kg kg-1. The WDC content was measured on air-dry and moist 1- to 2-mm aggregates. The WDC content at a reference time was highly correlated to the total clay content (r > 0.91, P < 0.001) for all soils. Only for two sites was the WDC content correlated to the content of clay not associated with organic C (r > 0.89, P < 0.001), calculated as a function of total organic C and total clay. The colloid release rates were highly correlated with the total clay content (r > 0.84, P < 0.001). The WDC content in moist aggregates measured using laser diffraction was correlated with the WDC content measured using a more classical end-over-end method (r > 0.89, P < 0.05) and in 100-cm³ undisturbed soil cores (r > 0.89, P < 0.05). The universal correlation between the contents of WDC and total clay could be highly useful in risk assessments of colloids and colloid-facilitated transport of environmental contaminants.
- Subjects
RHEOLOGY; INDUSTRIAL lasers; OPTICS; RISK assessment; DUE diligence; INVESTMENT analysis
- Publication
Vadose Zone Journal, 2012, Vol 11, Issue 1, p16
- ISSN
1539-1663
- Publication type
Article
- DOI
10.2136/vzj2011.0070