Microaggregates

Mummey DL, Stahl PD (2004) Analysis of soil whole- and inner-microaggregate bacterial communities. Microb Ecol 48 41-50... 

Bongiovanni MD, Lobartini JC (2006) Particulate organic matter, carbohydrate, humic acid contents in soil macro- and microaggregates as affected by cultivation. Geoderma 136 660-665... 

Cornea, A., Janovick, J. A., Maya-Nunez, G and Conn, P. M. (2001) Gonadotropinreleasing hormone receptor microaggregation. Rate monitored by fluorescence resonance energy transfer. J. Biol. Client. 276, 2153-2158. 

Pinheiro-Dick, D. Schwertmann, U. (1996) Microaggregates from oxisols and inceptisols dispersion through selective dissolutions and physicochemical treatments. Geoderma 74 49-63... 

Medium-chain alcohols such as 2-butoxyethanol (BE) exist as microaggregates in water which in many respects resemble micellar systems. Mixed micelles can be formed between such alcohols and surfactants. The thermodynamics of the system BE-sodlum decanoate (Na-Dec)-water was studied through direct measurements of volumes (flow denslmetry), enthalpies and heat capacities (flow microcalorimetry). Data are reported as transfer functions. The observed trends are analyzed with a recently published chemical equilibrium model (J. Solution Chem. 13,1,1984). By adjusting the distribution constant and the thermodynamic property of the solute In the mixed micelle. It Is possible to fit nearly quantitatively the transfer of BE from water to aqueous NaDec. The model Is not as successful for the transfert of NaDec from water to aqueous BE at low BE concentrations Indicating self-association of NaDec Induced by BE. The model can be used to evaluate the thermodynamic properties of both components of the mixed micelle. 

In such studies. It Is preferable to use two surfactants with widely different CMC s so as to explore the possibility of coexistence of two types of mixed micelles, 2 In 3 and 3 In 2. In this respect, the system cetyltrlmethylammonlum bromide (CTAB)-2-butoxyetha-nol (BE)-water Is being Investigated (14). Unfortunately, with CTAB, the CMC Is too low to allow thermodynamic measurements below the CMC. Still, this study shows unambiguously that BE dissolves In the CTAB micelles and also that CTAB can distribute Itself In the BE microaggregates. 

Bossuyt, H., Six, J., and Hendrix, P. F. (2004). Rapid incorporation of carbon from fresh residues into newly formed stable microaggregates within earthworm casts. Eur. J. Soil Sci. 55, 393-399. 

Six, J., Elliott, E. T., and Paustian, K. (2000a). Soil macroaggregate turnover and microaggregate formation A mechanism for C sequestration under no-tillage agriculture. Soil Biol. Biochem. 32(14), 2099-2103. 

Monreal, C. M., Schnitzer, M., Schulten, H.-R., Campbell, C. A., and Anderson, D. W. (1995). Soil organic structures in macro- and microaggregates of a cultivated Brown Chernozem. Soil Biol. Biochem. 27, 845-853. 

Figure 17.18. (A) Carbon contents in an entire microaggregate from an alfisol at Arnot Forest in Upstate New York (500-nm resolution). (B) Detail of the microaggregate (red box in A) (50-nm resolution). (C) X-ray map of B. (D) Cluster map [3 components, 20 clusters, without first component PCA GUI 1.0 developed by Lerotic et al. (2004)]. (E) Individual clusters from D numbers in each cluster map correspond to spectra shown in Figure 17.19 (J. Lehmann, unpublished data 2006, measured as described in Lehmann et al., 2007). See color insert.

Lehmann, J., Kinyangi, J., and Solomon, D. (2007). Organic matter stabilization in soil microaggregates Imphcations from spatial heterogeneity of organic carbon contents and carbon forms. Biogeochemistry. 85,45-57. 

Wan, J., Tyliszczak, T., and Tokunaga, T. K. (2007). Organic carbon distribution, speciation, and elemental correlation within soil microaggregates Apphcation of STXM and NEXAFS spectroscopy. Geochim. Cosmochim. Acta 71, 5439-5449. 

Estuarine water column particulates, primarily derived from rivers, adjacent wetland systems, and resuspension events, have been shown to be important in controlling the fate and transport of chemicals in estuaries. In particular, mineral surfaces on these particles have been shown to be important in binding organic molecules, gels, and microaggregates. 

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