Parmely H. Pritchard

Biological and abiotic degradation of xenobiotic compounds in in vitro estaurine water and sediment/water systems

Abstract First-order biotic and abiotic degradation rate constants of 14 pesticides were determined in estuarine water and sediment/water slurry systems. Test systems used environmentally realistic concentrations of pesticides in sterile and nonsterile samples of water and sediment taken directly from the field. Thiobencarb, sulprofos, chlorothalonil, diclofop-methyl, fenthion, oxyfluorfen, methoxychlor, phorate, and trifluralin all showed significantly (p

Use of inoculation in bioremediation

Abstract There are many possible situations where inoculation of chemically-contaminated sites with microorganisms possessing unique and specialized metabolic capabilities could significantly enhance bioremediation. However, there have been very few successful uses of inoculation to date. By more careful attention to selection and application of the inoculants, however, it is quite reasonable to expect that inoculation could become a major and effective component of biological cleanup methods.

Effect of inoculation on the biodegradation of wathered Prudhoe Bay crude oil

SummaryEnrichment cultures from oil-contaminated beach material from Prince William Sound, Alaska, generated both a mixed bacterial community of indigenous, oil-degrading marine microorganisms and a pure culture oil-degrader, strain EI2V. The mixed and axenic cultures were used in comparative shake flask studies of inoculation on biodegradation of Prudhoe Bay crude oil. Within 12 h following inoculation of homogenized, oiled beach material with the mixed culture, total CO2 production was increased 2-fold relative to a noninoculated control. Moreover, measurements of phenanthrene degradation (as determined by the release of14CO2 from [9-14C]phenanthrene) showed a 2-or 3-fold greater degradation when inoculated with either strain EI2V or with the mixed culture, respectively. However, as medium was replaced by a simulated tidal cycle, the observed stimulation of CO2 production decreased, and the addition of strain EI2V had no greater effect on total CO2 production than the addition of inorganic nutrients alone. Chemical analysis of oil recovered after 7 days incubation also suggested that, while these cultures are capable of efficient biodegradation of Prudhoe Bay crude in liquid culture, inoculation of beach material with high numbers of these microorganisms had little effect on the rate and extent of biodegradation of weathered crude oil. Overall, the sustained stimulatory effect was no greater than that observed with the addition of inorganic nutrients alone.

A shake-flask test for estimation of biodegradability of toxic organic substances in the aquatic environment

Disadvantages of current biodegradation tests are examined: the need for high substrate concentrations, lack of parent compound concentration measurements, no estimation of sediment effects, failure to indicate compounds to which microbial populations must adapt to degrade, and lack of site specificity in innocula selection. A modified river die-away test is proposed for determining biodegradability of organic compounds and testing for toxic degradation products. The present test uses shake flasks containing sterile (2% formalin) and nonsterile site water: both with, and without, site sediment (500 mg/liter). Concurrent toxicity testing with mysids or daphnids provides a sensitive assay for the detection of toxic metabolites. Examples of three test compounds are given: methyl parathion, which undergoes rapid, sediment-mediated biodegradation; dibutylphthalate, to which some microbial communities exhibit an adaptation phenomenon; and methoxychlor, which has a relatively low water solubility and high sediment partition coefficient. The relative merits of this test procedure are discussed.

Biotic and abiotic degradation rates of methyl parathion in freshwater and estuarine water and sediment samples

Abstract Statistical analysis of degradation rates of methyl parathion samples from two Gulf Coast estuaries over a three-year period indicated that biodegradation occurred in the presence of sediment but was insignificant in water. Sediment rates always showed the same relative five-fold difference at a primary site within each estuarine area. Samples from 11 ancillary sites indicated biodegradation rates in sediments can be subdivided into two groupings which were independent of seasonal differences (excluding temperature). Spatial variations in rates, therefore, may be of minor environmental significance for this chemical in estuarine areas.

Preliminary development of a bench-scale treatment system for aerobic degradation of trichloroethylene

Our results have demonstrated that TCE may be biodegraded to nontoxic products under certain conditions. Trichloroethylene is apparently degraded by strain G4 to CO2, cellular carbon, and inorganic chloride. This activity requires aerobic conditions and exposure of the organism to certain aromatic compounds. This exposure is required to induce the bio-synthesis of one or more enzymes that fortuitously degrade TCE. The normal function of the enzyme(s) is the metabolism of the aromatic compounds. Evidence from the work with environmental samples indicates that the natural microflora in a variety of areas is capable of TCE degradation if stimulated by the appropriate aromatic compounds. These results are presently being applied to the development of bench-scale continuous treatment systems for further assessment of biodegradation as a means for detoxification of TCE-contaminated sites.