Utilization of Nitrogen, Sulfur, and Phosphorus

Many contaminants contain nitrogen, phosphorus, or sulfur, and degradative organisms may utilize one or more of these leaving the major part of the substrate intact. This is particularly important for munitions-related compounds with a high N/C ratio, when the addition of carbon sources may lead to the favorable development of anaerobic or facultatively anaerobic microorganisms. 

There is substantial evidence from the aquatic environment for the existence of threshold concentrations below which rates of degradation of xenobiotics are slow or even negligible (Alexander 1985). A number of hypotheses have been put forward including the critical concentrations required for 

Many contaminated sites are located in areas with temperatures considerably less than 15°C, and investigations into the role of temperature have therefore been carried out. Some of the cardinal results have been discussed in Chapter 4, and it may be concluded that although the rates at 4-5°C may be low, selection of organisms for adaptation to the ambient temperature will generally ensure that degradative activity is retained. There may, however, be selective degradation of specific groups of components in mixtures such as PCBs. 

Alexander M (1985) Biodegradation of organic chemicals. Environ Sci Technol 18 106-111. 

Alexander M (1995a) Biodegradation and Bioremediation. Academic Press Inc, San Diego, California. 

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