Organic carbon in soil

In addition, dissolved organic carbon (DOC) is also an important soil solution solute affecting speciation and bioavailability of many trace elements in soil solution. Many trace elements and heavy metals complex with dissolved organic carbon. This is especially important in arid and semi-arid environments since high soil pH increases the solubility of organic molecules and accordingly increases concentrations of dissolved organic carbon in soil solution. 

Schumacher, B.A. 2002. Methods for the determination of total organic carbon in soils and sediments. US EPA Report, NCEA-C-1282, EMASC-001. 

Although these reservoirs may be highly contaminated with PCDD/PCDFs, the chemical and physical properties of these compounds imply that dioxins and furans will stay adsorbed to organic carbon in soils or other particles. On the other hand, mobilization can occur in the presence of lipophilic solvents (leaching into deeper layers of soils and/or groundwater) or in cases of erosion or run-off from topsoil (translocation into the neighbourhood). Experience has shown that transport of PCDD/PCDFs due to soil erosion and run-off does not play a major role in environmental contamination and human exposure (Fiedler 1995, 1999). 

Charles and Simmons [18] have reviewed methods for determining total, inorganic and organic carbon in soils and sediments, particularly limitations and sources of error associated with dry combustion and wet oxidation techniques. Preferred methods, for greater quantitative... 

Groundwater. Alachlor has a high potential to leach to groundwater due to its weak capacity to adsorb onto organic carbon in soil (U.S. EPA, 1986). 

Tinsley, J. (1950) Determination of organic carbon in soils by dichromate mixtures. Proceedings of the 4th International Congress of Soil Science, Vol. 1, 161. 

Kaiser, K., M. Kaupenjohann, and W. Zech. 2001. Sorption of dissolved organic carbon in soils Effects of soil sample storage, soil-to-solution ratio, and temperature. Geoderma 99 317-328. 

Malcolm, R. K. 1993. Concentration and composition of dissolved organic carbon in soils, streams and groundwaters. In Organic Substances in Soil and Water Natural Constituents and Their Influence on Contaminant Behavior. (A. J. Beck, K. C. Jones, M. H. B. Hayes, and U. Mingelgrin, eds.), pp. 19—30, Royal Society of Chemistry, Cambridge, UK. 

Yano, Y., W. H. McDowell, and N. E. Kinner. 1998. Quantification of biodegradable dissolved organic carbon in soil solution with flow-through bioreactors. Soil Science Society of America Journal 62 1556-1564. 

Dissolved organic carbon in soil solution has been shown to increase, decrease, or have little or no measurable effect on the initial binding of triazines to soil. No relationship was found between dissolved organic carbon and sorption of terbuthylazine on two soils however, in a third soil, sorption Kd was inversely correlated to dissolved organic carbon (Zsolnay et al., 1994). Similarly, dissolved organic content from some sources increased atrazine sorption, but from other sources had no effect (Barriuso et al., 1992a). 

Bascomb, C.L. (1968) Distribution of pyrophosphate-extractable iron and organic carbon in soils of various groups./. Soil Sci., 19, 251-268. 

Organic carbon in soil can be measured by oxidation with acid... 

As noted, POPs sorb strongly to natural organic carbon in soil and sediment particles. Thus, soils and sediments are a major environmental sink for POPs that may subsequently be biotransformed microbially via enantioselective aerobic and anaerobic reactions. Understanding this enantioselectivity may provide enhanced insights into the enzymes and populations involved, and allows prediction of degradation rates of POPs sequestered in a long-term reservoir. 

C, sorption isotherm, converted form organic carbon in soils, Briggs 1981)... 

Eswatan, H., E. van Den Berg, and P. Reich. 1993- Organic carbon in soils of the world. Soil Science and Social American Journal 57 192-194. 

Post W. M. (1993) Organic carbon in soil and the global carbon cycle. In The Global Carbon Cycle (ed. M. Heimann). Springer, New York, pp. 277-302. 

Figure 10.9 Relationship between S, the aqueous solubility, and K c, the adsorption or distribution coefficient for some molecular organic substances on organic carbon in soil.

It is also assumed that hydrophobic organic chemicals partition only into the organic matter in soils, sediment, and suspended sediment. Further, the organic matter in soils and sediment is not as well represented by octanol as is the lipids in biota. Empirically it has been found that the organic carbon (in soils and sediment)-water partition coefficient, Kocy/ u defined as... 

Burringh. (1984). Organic carbon in soils of the world. In The Role of Terrestrial Vegetation in the Global Carbon Cycle Measurement by Remote Sensing. (G. M. Woodwell, Ed.), pp. 91-109. Wiley, New York. 

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