Refractory dissolved organic matter

Bertilsson, S., and B. Allard. 1996. Sequential photochemical and microbial degradation of refractory dissolved organic matter in a humic freshwater system. Archiv fur Hydrobiologie 48 133-141. 

Miller, W. L., and M. A. Moran. 1997. Interaction of photochemical and microbial processes in the degradation of refractory dissolved organic matter from a coastal marine environment. Limnology and Oceanography 42 1317-1324. 

Ogawa, H., Y. Amagai, I. Koike, K. Kaiser, and R. Benner. 2001. Production of refractory dissolved organic matter by bacteria. Science 292 917—920. 

Schulten, H.-R., Leinweber, R, and Jandl, G. (2002). Analytical pyrolysis of humic substances and dissolved organic matter in water. In Refractory Organic Substances (ROS) in the Environment, Frimmel, F. H., Abbt-Braun, G., Heumann, K. G., Hock, B., Ludemann, H.-D., and Spiteller, M., eds., Wiley-VCH, Weinheim, pp. 163-187. 

Hertkorn, N., Benner, R., Frommberger, M., Schmitt-Kopplin, P., Witt, M., Kaiser, K., Kettrup. A., and Hedges, J. I. (2006). Characterization of a major refractory component of marine dissolved organic matter. Geochim. Cosmochim. Acta 70, 2990-3010. 

Yamashita, Y., and Tanoue, E. (2008). Production of bio-refractory fluorescent dissolved organic matter in the ocean interior. Nature Geosci., doi 10.1038/ngeo279. 

While specific compounds such as siderophores have been found in natural waters, the bulk of the dissolved organic matter (DOM) is made up of relatively refractory compounds known as humic substances. These substances exhibit complex, ill-defined structures with the actual structure depending markedly on the source of the organic material. DOM in the open ocean is almost entirely authochthonous and formed by condensation, polymerisation and partial oxidation of smaller molecules such as triglycerides, sugars and amino acids and exhibits very little aromatic character [78]. In contrast, the DOM in fresh and coastal waters is largely allochthonous and derived... 

Dissolved organic matter, expressed as chemical oxygen demand (COD) or total organic carbon (TOC), including methane, volatile fatty acids (in particular in the acid phase of the waste stabilization Christensen and Kjeldsen (1989), and more refractory compounds, e.g., fulvic-like and humic-like compounds. 

Hertkom, N. Benner, R. Frotmnherger, M. Schmitt-Kopplin, P. Witt, M. Kaiser, K. Kettrap, A. Hedges, J.I. Characterization of a Major Refractory Component of Marine Dissolved Organic Matter. Geochimica et Cosmochimica Acta 2006, 70,2990-3010. 

The elemental sulfur (Sq) in Equation 3 is generally dissolved as a polysulfide ion. In iron-poor sediment or sediment in which iron resides largely in refractory minerals, only small amounts of sulfide minerals form. Excess H2S in these sediments slowly reacts with organic matter to form organosulfur. 

Titanium. Titanium dioxide has been determined as the yellow peroxidation complex at 410 nm (13). Refractory titanium requires more vigorous dissolution than is used in S-385. After a nitric acid wet ashing is performed to oxidize all organic matter, the titanium solution is heated to 400°C in 8 ml of 40% ammonium sulfate in sulfuric acid until all remaining solids are dissolved. The solution is diluted for aspiration into a nitrous oxide-acetylene flame with detection at 364.3 nm. Five ml of 1 N ammonium fluoride is added to the final solution to stabilize Ti enhancement. 

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