Organic release from soils

Soil minerals play a stabilizing role in organic matter. The Al and Fe that complex and stabilize organic matter against microbial decomposition are released from soil minerals during soil formation. The supply rates apparently control the content of soil organic matter to a great extent. This is demonstrated by the relationship between pyrophosphate-extractable C and pyrophosphate-extractable Al plus Fe (Wada 1995). 

Carbon dioxide is the most common inorganic extractant used for the extraction of organic compounds in soil. Under pressure, it remains in the liquid state and can be used to extract organic compounds from soil. When the pressure is released, the carbon dioxide becomes a gas and is thus removed from the extracted components. An additional benefit is that liquid carbon dioxide is converted to gas at relatively low temperatures, thus limiting the loss of... 

Wang, S. and Mulligan, C.N. (2006) Effect of natural organic matter on arsenic release from soils and sediments into groundwater. Environmental Geochemistry and Health, 28(3), 197-214. 

The overall release of water soluble organic carbon from soil, on which this model for xylan hydrolysis is based, was expressed as three additive terms (15) ... 

TABLE 1.4. Overall Diffusion Coefficients of Cd Release from Soils by 10 mol L Low-Molecular-Mass Organic Acids During a 0.25 to 1-h Reaction Period... 

Krishnamurti, G. S. R.. Ciesliiiski. G., Huang, P. M., and Van Rees, K. C. J. (1997). Kinetics of cadmium release from soils as influenced by organic acids implication in cadmium availability. J. Environ. Qual. 26, 271-277. 

The amount of nitrogen released from soils of similar type is usually closely related to the amount of nitrogen or organic matter in the soil. This is illustrated in Fig. 14.1 taken... 

The latter process was termed biological mineralisation. The release of P and S in esters on the other hand is strongly controlled by the supply of, and need for the element which is released from soil organic matter by extracellular enzymes (biochemical mineralisation). These concepts, portrayed in Fig. 6, can accommodate the variability of C N S P ratios and the greater variability for P than for S in soil organic matter, and provide a rationale for understanding the stability of P in different soils. 

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