ISSN:0730-7268    

DOI:10.1002/etc.5620151101

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractThe biodegradation of13C‐labeled 2,4‐dichlorophenol (DCP labeled at the C‐2 and C‐6 positions), in the presence and absence of natural organic matter (NOM), by the white‐rot fungusPhanerochaete chrysosporium, was examined using13C‐nuclear magnetic resonance (NMR). Using this method permitted the chemistry occurring at or near the labeled site to be followed. The formation of alkyl ethers and alkene ethers was observed. No aromatic by‐products were detected, indicating that aromatic compounds are quickly degraded. Examining the reaction with time shows the exponential removal of 2,4‐DCP and the consequential formation of labeled by‐products, whose concentration reaches a maximum just before all 2,4‐DCP is consumed. After this, the by‐products degrade exponentially. The presence of NOM causes 2,4‐DCP to be removed from the aqueous phase more quickly than in its absence and also causes the by‐products to reach their maximum concentration much earlier. Degradation of the by‐products occurs at a much greater rate in the presence of NOM. One hypothesis for this behavior is that the NOM interacts with 2,4‐DCP and its by‐products, allowing them to be incorporated into the fungal biomass.13C‐nuclear magnetic resonance spectra of the fungal biomass after NaOH extraction show the presence of alka

ISSN:0730-7268    

DOI:10.1002/etc.5620151102

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractThis study investigated the interactions between organic chemicals and components of the soil matrix and their effects on subsequent microbial mineralization kinetics. Five14C‐labeled chemicals (anionic, cationic, and nonionic surfactants) were aseptically sorbed to montmorillonite, kaolinite, illite, sand, humic acids, and fulvic acids. Small amounts of these sorbed chemicals were dosed to an acidic, sludge‐amended agricultural soil (Rossmoyne) to a final added chemical concentration of 50 ng g−1. Controls received the same final added concentration of the chemicals in water. The ratio of sorbed chemical to soil was kept low to minimize changes to the soil mineralogy, chemistry, and microbiology. Microbial mineralization of the chemicals to14CO2was measured over a period of 60 to 70 d, and the data were fitted to first‐order and 3/2‐order mineralization models. Association with the soil constituents inhibited the mineralization of the chemicals in the following rank (from least to greatest effect): controls ≈ sand

ISSN:0730-7268    

DOI:10.1002/etc.5620151103

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractNaphthalene has been transported approx. 400 m via groundwater flow from buried subsurface coal tar to an organic matter‐rich seep area where the water emerges at the foot of a hill in a field study site. We have tested several hypotheses for explaining why naphthalene persists in seep sediments. In aerobic laboratory flask assays, conversion of14C‐naphthalene to14CO2occurred and was not stimulated by amendments with vitamins or inorganic nutrients. Thus, neither toxicity nor nutrient limitation were the cause of naphthalene persistence. At the site, in situ sediment oxygen concentrations were below detection. Oxygen‐limited naphthalene biodegradation was demonstrated both by measuring no conversion of14C‐naphthalene to14CO2in samples of seep sediments prepared anaerobically and by measuring naphthalene loss from anaerobic nitrate‐amended slurry‐phase incubations of the sediment only after O2was added. However, when H2O2was added as an O2source to site sediments in situ in a randomized block design, no discernible naphthalene loss occurred. The possibility that decreased bioavailability might contribute to naphthalene persistence was investigated by monitoring14CO2evolved by microorganisms added to γ‐ray sterilized sediments that had been exposed under aseptic conditions to14C‐labeled naphthalene for periods ranging from 0 to 28 d. Resulting patterns in the extent and rate of naphthalene mineralization revealed an inverse relationship to the duration of contact with the sediment, but only when the mixed microbial inoculum had been enriched on aqueous‐phase naphthalene. We conclude that oxygen limitation is the most probable cause for lack of naphthalene biodegradation at our field study site. However, diffusion or sorption reactions ma

ISSN:0730-7268    

DOI:10.1002/etc.5620151104

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractExperiments were carried out to determine the effects of mineralogy on the biodegradability of components of a whole fuel by a soil microbial consortium. Samples of quartz sand (Fischer Sea Sand) and illite clay (API 35) were spiked with marine diesel fuel, aged, slurried, and inoculated, and concentrations of fuel components were monitored over time. To help distinguish biotic from abiotic processes, identical samples were poisoned with mercuric chloride and were run in parallel. While there was chromatographic and biomarker evidence ofn‐alkane biodegradation in the sand samples, illite samples showed no evidence of biogenic loss of aliphatic components. Polycyclic aromatic hydrocarbons, on the other hand, were lost equivalently on both minerals and in both cases were lost to a much greater extent than were total petroleum hydrocarbons (TPHs). These results suggest thatunder our experimental conditions, illite inhibited the bioavailability of some TPH components to the soil microbial consortiu

ISSN:0730-7268    

DOI:10.1002/etc.5620151105

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractThe literature on microbial degradation of polycyclic aromatic hydrocarbon (PAH) compounds in soils and sediments shows that microbial biotreatment rates are highly variable. Although it is believed that these disparate results are somehow attributable to the bioavailability of PAH compounds, current understanding does not allow prediction of this phenomenon. This work evaluated relationships between coal tar composition and aqueous naphthalene concentration and between the rate of naphthalene mass transfer and microbial mineralization of naphthalene. The use of a dissolution‐degradation framework for identifying rate‐controlling phenomena in slurry biotreatment of coal tar is discussed. Experiments were performed in slurry systems with two coal tars for which naphthalene was the principal component. In slurry systems coal tar was present either as a single 0.7‐ml globule or as coated onto 250‐μm‐diameter microporous silica beads. Independent tests were conducted with these systems to assess the rates of naphthalene mass transfer and rates of naphthalene biomineralization. The area‐dependent mass transfer coefficient of naphthalene in the coal tar‐silica beads system was three orders of magnitude greater than for the single coal tar globule. A coupled, solute‐mass transfer biodegradation model was used to compare initial biomineralization rates with rates of naphthalene dissolution. Analysis of the results showed that the rate of biomineralization of naphthalene in the systems containing single coal tar globules was influenced by the rate of mass transfe

ISSN:0730-7268    

DOI:10.1002/etc.5620151106

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractTime‐dependent diffusion and/or sorption reactions were proposed as a mechanism for protecting polycyclic aromatic hydrocarbons (PAHs) in surface and subsurface sediments from a coal tar waste‐contaminated field site.14C‐labeled phenanthrene was aged in both subsurface sand and organic matter‐rich seep sediments that had previously been sterilized by gamma irradiation. After aging periods ranging from 0 to 28 d, the sediments were dispensed to replicate vials and inoculated with site‐derived phenanthrene‐degrading microorganisms (with and without previous enrichment on phenanthrene), and cumulative14CO2production was measured. When pure culture and mixed inocula originated from the seep sediments, phenanthrene mineralization from sand sediment samples was retarded with longer aging periods. However, when a mixed inoculum originating from the sand sediments was tested, aging of the phenanthrene had only a slight or no effect on its rate or extent of mineralization. Thus, the susceptibility of phenanthrene to biodegradation varied with the source of the microbial inocula. When gamma‐irradiated seep sediments were the sorbent, all mineralization of14C phenanthrene was eliminated. Several hypotheses were tested for explaining this sorbent‐dependent inhibition of phenanthrene metabolism. Gamma radiation‐induced changes in the sorptive properties of the seep sediment seeme

ISSN:0730-7268    

DOI:10.1002/etc.5620151107

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractLaboratory and field investigations were undertaken to determine the fate, disposition, and persistence of the insecticide diflubenzuron in California rice culture. Water solubility was similar in distilled/deionized water (88.8 ± 4.0 μg/L) and rice field water (92.6 ± 3.5 μg/L), while the measured Henry's law constant was 2.34 ± 0.02 × 10−1Pa.m3/mole. Diflubenzuron was rapidly photodegraded in field water primarily to the more stable chlorophenylurea and difluorobenzoic acid; field water photolysate was equally toxic toDaphnia magnaas pure insecticide solutions. Applications to experimental rice field plots resulted in rapid dissipation of diflubenzuron (half‐life 27.3 h), nonpersistent sediment residues, and significant partitioning into the surface m

ISSN:0730-7268    

DOI:10.1002/etc.5620151108

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractMicrobial anaerobic dechlorination of hexachlorobenzene (HCB) was examined in sediment slurries amended with two classes of nonionic surfactant, polyoxyethylene (POE) sorbitan fatty acid esters (Tweens) and POE alcohols (Brijs). The rationale for surfactant addition was to increase the bioavailability of highly sorbed organic pollutants to degrading microorganisms by enhancing their solubility. The solubility of HCB was initially enhanced via micellar partitioning; however, primary degradation of most surfactants occurred within 10 d. Dechlorination activity was significantly reduced at POE alcohol concentrations above the critical micelle concentration (cmc), with or without the occurrence of surfactant degradation. Tween 80 decreased HCB dechlorination at concentrations significantly above the cmc (1,500–5,000 mg/L). At concentrations closer to the cmc (300–1,200 mg/L), Tween 80 increased dechlorination rate constants four‐ to fivefold in acclimated slurries. Additions of Tween 80 at or below the cmc (3, 30, 300, and 911 mg/L) stimulated dechlorination activity in unacclimated slurries that exhibited very little activity in unamended controls. An average of 89% of HCB was dechlorinated after 90 d, compared to 20% in unamended sediments. No effect was observed for POE alcohols at these sub‐cmc levels. The lack of a stimulated response for the POE alcohols suggests that Tween 80 may not be acting simply as a source of carbon or

ISSN:0730-7268    

DOI:10.1002/etc.5620151109

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractSince speciation can affect bioavailability and toxicity of copper in aquatic systems, accurate predictions of effects of bioavailable forms require detection and/or measurement of these forms. To develop an approach for measurement of bioavailable copper, a copper sulfate solution (CuSO4·3Cu(OH)2·H2O) was used in 10‐d aqueous and sediment toxicity tests withHyalella aztecaSaussure. These tests encompassed ranges of pH (6.5 to 8.1), alkalinity (10 to 70 mg/L as CaCO3), hardness (10 to 70 mg/L as CaCO3), and conductivity (30 to 300 μmho/cm). Changes in copper speciation were measured using atomic absorption spectroscopy (AA) for dissolved copper and differential pulse anodic stripping voltammetry (DPASV) for labile copper, and concentrations were evaluated relative to amphipod survival. Ten‐day LC50s based on AA‐measured aqueous copper concentrations ranged from 42 to 142 μg Cu/L, and LC50s based on DPASV‐measured copper concentrations ranged from 17.4 to 24.8 μg Cu/L. In 10‐d tests using copper‐amended sediments with diverse characteristics and AA‐measured copper concentrations spanning an order of magnitude, total copper concentrations were not predictive of sediment toxicity, butH. aztecasurvival was explained by DPASV measurements that varied by ≤4%. In order to make defensible estimates of the potential risk of metals in sediments or water, it is essential to identify the fraction of total metal that is bioavailable. In these experiments, DPASV was useful for measuring bioavailable copper in aqueous and sediment

ISSN:0730-7268    

DOI:10.1002/etc.5620151110

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY