The development of a sterile, PAH-spiked, aged marine sediment for biodegradation experiments: chemical results

Apitz, Sabine E.; Arias, Ernest; Clawson, Sheri A; Lin, Eleanor W; Melcher, Rebecca J; Hemmingsen, Barbara B.

doi:10.1016/s0146-6380(99)00073-x

Cited by 15 publications

(8 citation statements)

References 26 publications

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“…In the first (ONR-1), sediment mesocosms were irradiated at four levels (0, 2.5, 3.5, and 5 megarads) and spiked with a mixture of PAHs. As described in a preliminary report (3) and in detail in this paper, sterility was not achieved in these sediments, even at 5 megarads. To achieve sterility and to assess the impacts of sample handling without PAH addition, a second experiment (ONR-2) was carried out using higher irradiation levels and repeat irradiation to kill endospores.…”

supporting

confidence: 49%

“…This pattern suggested that fungal survivors were able to proliferate in the former sediments because of lowered bacterial numbers but that the generally higher numbers and earlier appearance of bacteria in the latter sediments restrained fungal growth. These fungi were not PAH degraders, as indicated by the stable levels of PAHs in these mesocosms (3). The fungi could seriously interfere with subsequent studies of the spiked aged sediments after reinoculation with PAHdegrading bacteria.…”

Section: Resultsmentioning

confidence: 96%

“…While there is ongoing input of PAHs into sediments at various levels and rates, many sites contain sediments that have been contaminated by PAHs for months to years, during which time weathering and sequestration may alter the contaminants, their relationship to sediment constituents, and their availability to microbes. Thus, experimental sediments containing known amounts of PAHs must be aged in the absence of PAH-degrading bacteria (3,20). We were able to accomplish this with the irradiated ONR-1 and four of the successfully irradiated ONR-2 mesocosms even though the heterotrophs able to grow in air and endospore formers eventually reappeared.…”

Section: Discussionmentioning

confidence: 97%

“…Total organic carbon and dissolved organic carbon (DOC) in subsamples of each mesocosm were measured as described in the work of Apitz et al (3). PAHs were extracted with a dichloromethane-acetone mixture with sonication and analyzed after cleanup with a 5972 series Mass Selective Detector in ion-selective mode (3).…”

Section: Methodsmentioning

confidence: 99%

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Impact of Irradiation and Polycyclic Aromatic Hydrocarbon Spiking on Microbial Populations in Marine Sediment for Future Aging and Biodegradability Studies

Melcher

Apitz²,

Hemmingsen

2002

Appl Environ Microbiol

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Experiments were carried out to develop methods to generate well-characterized, polycyclic aromatic hydrocarbon (PAH)-spiked, aged but minimally altered sediments for fate, biodegradation, and bioavailability experiments. Changes in indigenous bacterial populations were monitored in mesocosms constructed of relatively clean San Diego Bay sediments, with and without exposure to gamma radiation, and then spiked with five different PAHs and hexadecane. While phenanthrene and chrysene degraders were present in the unspiked sediments and increased during handling, PAH spiking of nonirradiated sediments led to dramatic increases in their numbers. Phenotypic characterization of isolates able to grow on phenanthrene or chrysene placed them in several genera of marine bacteria: Vibrio, Marinobacter or Cycloclasticus, Pseudoalteromonas, Marinomonas, and Halomonas. This is the first time that marine PAH degraders have been identified as the latter two genera, expanding the diversity of marine bacteria with this ability. Even at the highest irradiation dose (10 megarads), heterotrophs and endospore formers reappeared within weeks. However, while bacteria from the unirradiated sediments had the capacity to both grow on and mineralize 14 C-labeled phenanthrene and chrysene, irradiation prevented the reappearance of PAH degraders for up to 4 months, allowing spikes to age onto the sediments, which can be used to model biodegradation in marine sediments.

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supporting

confidence: 49%

Section: Resultsmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

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Impact of Irradiation and Polycyclic Aromatic Hydrocarbon Spiking on Microbial Populations in Marine Sediment for Future Aging and Biodegradability Studies

Melcher

Apitz²,

Hemmingsen

2002

Appl Environ Microbiol

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“…Experiments showed that a dose of 30 Mrad of γirradiation caused no measurable changes in isotopic signature, chemical composition, crystallographic structure, or homogenization temperatures of fluid inclusions in rocks and minerals analogous to those found on Mars. Recently, the use of γ-irradiation in studies of microbial respiration rates and geochemical reaction rates of natural soils has gained popularity (Golde et al, 1994;Apitz et al, 1999;Getenga et al, 2004;Herbert et al, 2005;Manning et al, 2006). However, descriptions of the effects of moderate doses of ionizing radiation on whole soils or even naturally occurring minerals remain incomplete.…”

Section: Introductionmentioning

confidence: 99%