Accession Number : ADA264106

Title :   Geochemical, Genetic, and Physiological Control of Pollutant Biodegradation

Descriptive Note : Annual rept. 30 Sep 91-29 Sep 92,


Personal Author(s) : Madsen, Eugene L ; Lion, Leonard W

Full Text :

Report Date : 25 Nov 1992

Pagination or Media Count : 54

Abstract : The proposed research was designed to utilize a combination of laboratory and field studies to identify physical, chemical, genetic, and physiological influences that govern the accumulation and biodegradation of polycyclic aromatic hydrocarbons (PAHs). These and related compounds are among the chemicals whose environmental fate has been targeted by the U.S. Air Force Bioenvironmental Research Program. We have conducted a prior, independent study that has shown that, despite the presence of PAH mineralizing microorganisms. PAHs persist at a site where freshwater sediments are fed by PAH-contaminated ground water. Hypotheses to be tested address fundamental mechanisms for the persistence of environmental pollutants, these include: (1) the rate of delivery meets or exceeds the rate of biodegradation; (2) the PAHs are not available to microbial populations due to sorption onto the sediment organic matter, complexation reactions with dissolved organic carbon, or due to the physical arrangement of the sediment matrix which prevents contact between PAHs and microorganisms; (3) the microorganisms may be physiologically limited by the presence of preferred metabolic substrates or toxic or inhibitory substances, or by the lack of proper final electron acceptors, electron donors, or inorganic or organic nutrients; and (4) PAHs may persist simply due to restricted distribution and abundance of biodegradation genes in naturally occurring microbial populations. By working in an iterative manner between field observations and controlled laboratory determinations, we intend to systematically test the above hypotheses and thus identify constraints on microbiological processes that mineralize PAHs (naphthalene and phenanthrene) at the field site.


Subject Categories : Anatomy and Physiology
      Organic Chemistry
      Water Pollution and Control

Distribution Statement : APPROVED FOR PUBLIC RELEASE