Persistence of Organics in Soil-Water Systems

Equation 8.29b reveals that O is related to the amount of organic added and its rate of decomposition. 

Additional factors controlling the rate of decomposition include carbon chain unsaturation, which increases rate of decomposition, number, and position of Cl atoms on an aromatic ring. For example, 2,4-dichlorophenoxyacetic acid is degraded readily, whereas 2,4,5-trichlorophenoxyacetic acid is more resistant. Finally, the position of attachment of a side chain alters the decomposition rate of aromatic compounds. For 

ORGANIC MATTER, NITROGEN, PHOSPHORUS, SYNTHETIC ORGANICS 

TABLE 8.8. Hydrolysis Half-Lives for Several Groups of Organic Constituents 

Pesticides represent a wide range of agricultural chemicals used to control various pests. The persistence of such chemicals in the soil is undesirable because of the potential of these chemicals to affect various crops differently, their bioaccumulation in various crops, and their leaching into ground and/or surface water. A brief description of the various classes of pesticides, with respect to their persistence behavior, is given below  

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