Rates of Microbial Transformation of Polycyclic Aromatic Hydrocarbons in Water and Sediments in the Vicinity of a Coal-Coking Wastewater Discharge

Abstract

To facilitate predictions of the transport and fate of contaminants at future coal conversion facilities, rates of microbial transformation of polycyclic aromatic hydrocarbons were measured in stream water and sediment samples collected in the vicinity of a coal-coking treated wastewater discharge from November 1977 through August 1979. Six radiolabeled polycyclic aromatic hydrocarbons were incubated with sediment and water samples; 14 CO 2 , cell-bound 14 C, and polar transformation products were isolated and quantified. Whereas 14 CO 2 and bound 14 C were major transformation products in sediment assays, soluble polar 14 C dominated transformation in water samples. Mean rate constants (measured at 20°C) in sediments collected downstream from the effluent outfall were 7.8 × 10 −2 h −1 (naphthalene), 1.6 × 10 −2 h −1 (anthracene), and 3.3 × 10 −3 h −1 [benz(a)anthracene], which corresponded to turnover times of 13, 62, and 300 h, respectively. No unequivocal evidence for transformation of benzo(a)pyrene or dibenz(a,h)anthracene was obtained. Only naphthalene and anthracene transformations were observed in water samples; rate constants were consistently 5- and 20-fold lower, respectively, than in the corresponding sediment samples. The measured rate constants for anthracene transformation in July 1978 sediment samples were not related to total heterotroph numbers. In late July 1978, the effluent was diverted from the primary study area; however, no differences were observed either in transformation rate constants or in the downstream/upstream sediment rate constant ratio. These results are consistent with the hypothesis that continuous inputs of polycyclic aromatic hydrocarbons result in an increased ability within a microbial community to utilize certain polycyclic aromatic hydrocarbons. However, because transformation rates remained elevated for more than 1 year after removal of the polycyclic aromatic hydrocarbon source, microbial communities may shift only slowly in response to changes in polycyclic aromatic hydrocarbon concentrations.

Microbial Ecology, Toxicology and Chemical Fate of Methyl Isothiocyanate in Riparian Soils From the Upper Sacramento River

“…Given this level of toxicity, it is not surprising that soils recurrently treated with CH 3 NCS show evidence of changes in microbial processes indicative of adaptation or physiologic accommodation [11]. This is also consistent with the effects of other xenobiotics on microbial populations, as demonstrated by Herbes [12].…”

Effects of chemical structure and exposure on the microbial degradation of polycyclic aromatic hydrocarbons in freshwater and estuarine ecosystems

“…This indicates : that not all heterotrophs were able to utilize PAHs as substrates and total heterotrophic microbial populations may not be a reliable indicator of the hydrocarbon-degrading potential of aquatic sediments. Similar adaptive increases in oil-degrading microbial populations without increases in total heterotrophic activity have been reported in sediments near oil-fields in the North Sea [36] and in the vicinity of a coal-coking wastewater discharge [12]. The degradation of many aromatic hydrocarbons is plasmid mediated in heterotrophic microorganisms [37] and the physiological, enzymatic and genetic differences between adapted and unadapted sediment microorganisms are important features to be considered in determining the recalcitrance of a pollutant.…”

“…The ability of these naturally diverse assemblages of microorganisms to degrade PAHs depends to a large extent on the physical and chemical nature of the ecosystem and the history of previous chemical exposure. Biodegradation rates for some PAHs have been previously reported in water [12,[14][15][16]351 and sediments [lo-151. However, the present study provides data from the use of sediment: water microcosms for a comparative study of the effects of past chemical exposure and adaptation of sediment microbial populations on the mineralization rates of six PAHs in both estuarine and freshwater ecosystems.…”

“…The mineralization of benzo[a]pyrene has been previously examined in sediments. Herbes and coworkers [12,13] did not detect mineralization of benzo[a]pyrene in sediments in the vicinity of a coal-coking wastewater discharge, but did report a turnover time of about 178 wk for benzo[a]pyrene in petroleum-contaminated sediments. Massie et al reported daily mineralization rates for benzo[a]pyrene which ranged from 0.1 to 26.8 pg/m2.cm for sediments in the North Sea 1361.…”

Effects of Substrate Mineralogy on the Biodegradability of Fuel Components

“…Second, petroleum products are mixtures of hundreds of aliphatic and aromatic organic compounds, the relative proportions of which vary greatly between fuel type and somewhat between batches of the same type. Each component differs in its reactivity, solubility, volatility, mineral surface affinity, and biodegradability [1][2][3][4]. Furthermore, the mode of introduction of the contaminant into the soil or sediment, postdepositional weathering, and diverse mobility characteristics of the components can drastically alter the composition of the bulk fuel contaminant.…”