Colloidal organic matter

Initial tests of Brownian pumping required the measurement of Th in colloids separated from seawater samples. " Th proved to be an especially useful tracer of colloidal uptake of metal species because of its constant source and relative abundance. Baskaran et al. (1992) and Moran and Buesseler (1992) used cross-flow filtration to separate the colloidal fraction and both studies reported significant (up to 78% of total) " Th in this fraction. Subsequent work largely supported these observations (Moran and Buesseler 1993 Huh and Prahl 1995) and suggested the importance of colloidal organic matter in scavenging Th (Niven et al. 1995). 

Bioavailability of Metals, Nonmetals and Xenobiotics Immobilized on Soil Components, (4) Distribution and Activity of Biomolecules in Terrestrial Systems, (5) Interactions between Soil Microbial Biomass and Organic Matter/Nutrient Transformations, and (6) Impact of Interactions among Soil Mineral Colloids, Organic Matter and Biota on Risk Assessment and Restoration of Terrestrial Ecosystems. There were 2 plenary lectures, 9 invited speakers, 36 oral presentations and 45 posters. Dr. N. Senesi from University of Bari, Italy, presented an IUPAC lecture entitled Metal-Humic... 

Fig. 2.10 Mean colloidal organic matter (COM - zooplankton+phytoplankton+dissolved organic carbon) burden [kmol P/m2], integrated over the uppermost 90 m (euphotic zone).

Fig. 2.13 Mean fraction of DDT bound on detritus (upper panels) and colloidal organic matter (lower panels) in the euphotic zone [%].

Figure 6.1. Species around soil particles. CC, day colloid COM, colloidal organic matter. 

Brownawell, B.J. The role of colloid organic matter in the marine geochemistiy of PCBs, Ph.D. Dissertation, Woods Hole-MIT Joint Program. Cambridge, MA. 1986. 

Electrodialysis Relies on proven technology 85,000 11,000 Membrane fonhng and clogging by residnal colloidal organic matter in gronndwater may reqnire more skill and care than other systems discussed in this application. 

Hence, in principle, we could explain the discrepancies between predicted and observed BAFt values by the reduction of the bioavailability of the compounds caused by sorption to colloidal organic matter present in the culture media. We should note, however, that depending on the nature of the dissolved organic matter (i.e., molecular size distribution, aromaticity, polarity, etc.), the KiDOC value of a compound may vary considerably (see Section 9.4). 

After you have done your model calculation, you realize that the measured Ctop value is nearly twice as big as the value you have calculated. You remember that colloidal organic matter can significantly change the behavior of the PCBs in the water column (see Table 23.5). Your measurements give an average concentration of colloidal organic matter of [DOC] = 3.2 xlO-3 kg m 3. Modify the above calculations and check whether the colloids can explain the discrepancy between observation and model calculation. 

Effect of Dissolved or Colloidal Organic Matter (Suspended Particulates or "Third Phase")... 

Herbert, B. E., and P. M. Bertsch. 1995. Characterization of dissolved and colloidal organic matter in soil solution A review. In Carbon Forms and Functions in Forest Soils (W. W. McFee and J. M. Kelly, Eds.), pp. 63-88, Soil Science Society of America, Madison, WI. 

Chin, Y. P., and P. M. Gschwend. 1992. Partitioning of PAHs between porewater colloidal organic matter and marine interstitial waters. Environmental Science and Technology 26 1621. 

Koenings, J. P., and F. F. Hooper. 1976. The influence of colloidal organic matter on iron and iron-phosphorus cycling in an acid bog lake. Limnology and Oceanography 21 684-696. 

Pan Ming Huang received his Ph.D. degree in soil science at the University of Wisconsin, Madison, in 1966. He is Professor Emeritus of Soil Science at the University of Saskatchewan, Saskatoon, Canada. His research work has significantly advanced the frontiers of knowledge on the formation chemistry and nature and surface reactivity of mineral colloids, organic matter, and organomineral complexes... 

Benedetti, M., Ranville, J.F., Ponthieu, M. and Pinheiro, J.P. (2002) Field-flow fractionation characterization and binding properties of particulate and colloidal organic matter from the Rio Amazon and Rio Negro, Organic Chemisrty 33, 269-279. 

Coagulation processes in estuaries are affected by other factors such as clay composition, particle size, and concentration of dissolved organic matter, to mention a few. For example, early work has shown that metal hydroxides can flocculate from dis-solved/colloidal organic matter during the mixing of river-derived iron and seawater in the mixing zone of estuaries (Sholkovitz, 1976, 1978 Boyle et al, 1977 Mayer, 1982) (more details are provided on metal colloidal interactions in chapter 14). Surface sediments in... 

It is well known that DOM exists in different size fractions in aquatic systems (Sharp, 1973) and that a large portion of estuarine DOM is composed of colloidal organic matter (Whitehouse et al., 1989 Filella and Buffle, 1993 Guo et al., 1995, 1999 Martin et al., 1995 Sempere and Cauwet, 1995 Guo and Santschi, 1997 Cauwet, 2002). 

Figure 13.14 Relationship between A14C and C N ratios in macromolecular colloidal organic matter (COM) fractions (COMj = >1 kDa <0.02 pm, COMio = >1 kDa <0.02 pm) in Galveston Bay, July 1993. (Modified from Guo et al., 1997.)...

Guo, L., Santschi, P.H., and Baskaran, M. (1997) Interaction of thorium isotopes with colloidal organic matter in oceanic environments. Colloids Surf. A, Physiochem. Eng. Aspect 120, 255-271. 

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