Organic matter refractory

A number of studies have detected Maillard reaction products (melanoidins) in refractory organic matter from natural environments—for example, from sediments from a west African upwelling (Zegouagh et al., 1999) and archeological plant remains (Evershed et al., 1997). Poirer et al. (2000,2002) and Quenea et al. (2006a) showed that the refractory organic matter isolated from different soils consists in part of cross-linked melanoidins poorly resolved by 13C NMR spectroscopy. The presence of amide structures in soil as elucidated by 15N NMR is ascribed to either preserved proteinacious structures or melanoidin-type macromolecules (Derenne and Largeau, 2001). 

Zegouagh, Y., Derenne, S., Largeau, C., Betrand, P., Sicre, M-.A., Shot, A., and Rousseau, B. (1999). Refractory organic matter in sediments from the north-west African upwelling system Abundance, chemical structure and origin. Org. Geochem. 30,83-99. 

Selective extraction was used to operationally determine the quantitative and qualitative distributions of PCB 8 and saturated hydrocarbons among free lipid (FL), humic acid (HA), and humin (HU) fractions of four contaminated estuarine sediments. In all samples, over 90% of the total sedimentary PCB s and hydrocarbons were extracted with FL fractions. Bound (HA and HD) and free assemblages of these compounds may have derived from different sources. Two polar, chlorinated pollutants also detected In this study, hexachlorophene (HCP) and pentachlorophenol (PCP), were proportionately more concentrated In bound fractions than the non-polar compounds HCP was detected only In HA fractions and was probably chemically hound to refractory organic matter. Selective extraction Is a promising technique for Investigating strongly bound polar pollutants, such as HCP, which apparently are not recovered by conventional solvent extraction. 

Polar pollutants, such as chlorinated phenols, can occur largely as chemically bound components of refractory organic matter. 

Fontanier, C., Jorissen, F. j., Chaillou, G., Anschutz, P., Gr mare, a. Griveaud, C. 2005. Live foraminiferal faunas from a 2800 m deep lower canyon station from the Bay of Biscay faunal response to focusing of refractory organic matter. Deep-Sea Research I, 52, 1189-1227. 

By reviewing microscopic observations, physicochemical properties and numerical simulations of colloid dynamics, BufQe et al. [24] have developed a three-component picture of the heteroaggregation of colloids. In marine systems the three components are inorganic colloids (IC), refractory organic matter (ROM) with characteristics similar to freshwater fulvic material, and fibrillar polymers (FP). 

Fig. 4. Aggregates formed in a three-component, colloidal system [24], Refractory (fulvic-like) organic matter (ROM) is represented by small dots, inorganic colloids (IC) by larger, shaded spheres and fibriUar polymers (FP) by ribbons. In addition to small (submicron) and larger (> 1 mm) aggregates, refractory organic matter and fibrillar polysaccharides can also form gels [78] where inorganic colloids can develop internally after condensation...

Refractory organic matter Surfactants 2-6 Organic matter resistant to conventional treatments... 

Reimers CE, AUeau Y, Bauer JE, Delaney J, Girguis PR, Schrader PS, Stecher HA m. Redox effects on the microhial degradation of refractory organic matter in marine sediments. Geochim Cosmochim Acta 2013 121 582-598. 

---