Susan T. Bagley

Crater lake and post-eruption hydrothermal activity, El Chichón Volcano, Mexico

Abstract Explosive eruptions of Volcan El Chichon in Chiapas, Mexico on March 28 and April 3–4, 1982 removed 0.2 km3 of rock to form a 1-km-wide 300-m-deep summit crater. By late April 1982 a lake had begun to form on the crater floor, and by November 1982 it attained a maximum surface area of 1.4 × 105 m2 and a volume of 5 × 106 m3. Accumulation of 4–5 m of rainfall between July and October 1982 largely formed the lake. In January 1983, temperatures of fumaroles on the crater floor and lower crater walls ranged from 98 to 115°C; by October 1983 the maximum temperature of fumarole emissions was 99°C. In January 1983 fumarole gas emissions were greater than 99 vol. % H2O with traces of CO2, SO2, and H2S. The water of the lake was a hot (T = 52–58°C), acidic (pH = 0.5), dilute solution (34,046 mg L−1 dissolved solids; Cl/S = 20.5). Sediment from the lake contains the same silicate minerals as the rocks of the 1982 pyroclastic deposits, together with less than 1% of elemental sulfur. The composition and temperature of the lake water is attributed to: (1) solution of fumarole emissions; (2) reaction of lake water with hot rocks beneath the lake level; (3) sediments washed into the lake from the crater walls; (4) hydrothermal fluids leaching sediments and formational waters in sedimentary rocks of the basement; (5) evaporation; and (6) precipitation.

Klebsiella planticola sp. nov.: A new species of enterobacteriaceae found primarily in nonclinical environments

The nameKlebsiella planticola sp. nov. is proposed for a group of organisms isolated primarily from botanical and daquatic environments. Both numerical and molecular taxonomy techniques show that the species belongs within the genusKlebsiella and that it is distinct from other described species of the genus. The new species has 3 biogroups.K. planticolla is phenotypically identical toK. pneumoniae in classical biochemical tests, but it is distinguishable fromK. pneumoniae based on its ability to grow at 10°C and its inability to produce gas from lactose at 44.5°C. Additional reactions that can be used in combination with the temperature criteria includel-sorbose fermentation and ability to utilize hydroxy-l-proline as a sole carbon source. Strain V-236 (ATCC 33531; CDC 4245-72) is the type strain of the new species.

Highly Water‐Soluble, Fluorescent, Conjugated Fluorene‐Based Glycopolymers with Poly(ethylene glycol)‐Tethered Spacers for Sensitive Detection of Escherichia coli

Two bromide-bearing, fluorene-based, conjugated polymers with oligo(ethylene glycol)- and poly(ethylene glycol)-tethered spacers have been prepared by the Suzuki coupling polymerization of bromide-bearing, fluorene monomers. beta-Glucose and alpha-mannose residues have been covalently attached to the conjugated polymers by post-polymerization functionalization of the precursor polymers with thiol-functionalized carbohydrates under basic conditions through thioether linkage. A glucose-bearing glycopolymer with oligo(ethylene glycol)-tethered spacers (polymer A) displays poor water solubility. However, glycopolymers with poly(ethylene glycol)-tethered spacers (polymers B and C) are highly water-soluble due to their long, flexible, hydrophilic spacers. Incubation of the ORN178 strain of Escherichia coli (E. coli) with alpha-mannose-bearing glycopolymer (polymer C) results in the formation of fluorescent cell clusters, causing significant red shifts in UV/Vis absorption and fluorescent spectra of the polymer through multivalent cooperative interactions of the polymeric carbohydrates with the bacterial pili. In contrast, polymer C displays no interactions with a mutant ORN208 strain of E. coli.

A One-Dimensional Computational Model for Studying the Filtration and Regeneration Characteristics of a Catalyzed Wall-Flow Diesel Particulate Filter

A one-dimensional, two layer computational model was developed to predict the behavior of a clean and particulate-loaded catalyzed wall-flow diesel particulate filter (CPF). The model included the mechanisms of particle deposition inside the CPF porous wall and on the CPF wall surface, the exhaust flow field and temperature field inside the CPF, as well as the particulate catalytic oxidation mechanisms accounting for the catalyst-assisted particulate oxidation by the catalytic coating in addition to the conventional particulate thermal oxidation. The paper also develops the methodology for calibrating and validating the model with experimental data. Steady state loading experiments were performed to calibrate and validate the model. The experimental data were collected on a Corning EX-80 cordierite filter (100 cpi) with a loading of 5-g/ft 3 Pt in the MEX catalyst type formulation using a 1995 Cummins M11-330E heavy-duty diesel engine with manual EGR and conventional low sulfur fuel (375 ppm sulfur). Good agreement was obtained between the model predictions for pressure drop, particulate mass filtration efficiency, particulate mass retained, and filter temperature profile. The model was also used with experimental data to estimate the filter clean wall permeability, the packing density of the particulate deposited inside the filter wall, the particulate layer packing density, porosity, and permeability, as well as the activation energy and frequency factor of the particulate thermal and catalytic oxidation, including the maximum thickness of the particulate layer in contact with the catalyst. The particulate layer packing density, porosity, and permeability were then correlated with the exhaust gas Peclet number to provide a better understanding of particulate properties under various engine loads. This model can be used as a tool to predict the pressure drop across the CPF, the particulate mass filtration efficiency, the downstream particulate concentration, and the particulate mass retained inside the CPF for different filter geometries and physical properties, as well as for different engine operating conditions. In conjunction with designed experiments, the model can also be utilized to characterize (by determing the model constants) catalyzed particulate filters with different catalysts and catalyst loadings.

Results of the IPCS collaborative study on complex mixtures.

The International Programme on Chemical Safety (IPCS) sponsored a collaborative study to examine the intra- and inter-laboratory variation associated with the preparation and bioassay of complex chemical mixtures. The mixtures selected were National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs). 20 laboratories worldwide participated in the collaborative trial. The participating laboratories extracted the organic portion of two particulate samples--an air-particulate sample and a diesel-particulate sample--and bioassayed the extracts. The laboratories simultaneously bioassayed a NIST-prepared extract of coal tar and two control compounds (benzo[a]pyrene, and 1-nitropyrene). The bioassay method used was the Salmonella/mammalian microsome plate-incorporation test using strains TA98 and TA100. Study design also allowed for a comparison of sonication and Soxhlet extraction techniques. The mean extractable masses for the air particles and diesel particles were approximately 5% and 17.5%, respectively. The particulate samples were mutagenic in both strains with and without activation in all 20 laboratories. For TA100 the with and without activation slope values for the air particulate were 162 and 137 revertants per mg particles, respectively. For TA98 the respective diesel slope values were 268 and 269. The mutagenicity slope values for the diesel particles ranged from 3090 (TA98, +S9) to 6697 (TA100, +S9) revertants per mg particles. The coal tar solution was negative for both strains when exogenous activation was not used but was mutagenic in both strains with exogenous activation. The benzo[a]pyrene and 1-nitropyrene were used as positive controls and gave results consistent with the literature. This paper provides a complete summary of the data collected during the collaborative study. Companion papers provide further analysis and interpretation of the results.

An Experimental Study of Active Regeneration of an Advanced Catalyzed Particulate Filter by Diesel Fuel Injection Upstream of an Oxidation Catalyst

Passive regeneration (oxidation of particulate matter without using an external energy source) of particulate filters in combination with active regeneration is necessary for low-load engine operating conditions. For low-load conditions, the exhaust gas temperatures are less than 250\mDC and the PM oxidation rate due to passive regeneration is less than the PM accumulation rate. The objective of this research was to experimentally investigate active regeneration of a catalyzed particulate filter (CPF) using diesel fuel injection in the exhaust gas after the turbocharger and before a diesel oxidation catalyst (DOC) and to collect data for extending the MTU 1-D, 2-layer model to include the simulation of active regeneration. The engine used in this study was a 2002 Cummins ISM turbocharged 10.8 L heavy-duty diesel engine with cooled EGR. The exhaust after-treatment system consisted of a Johnson Matthey DOC and CPF (a CCRT\sR). Steady-state loading experiments at 20% load at rated speed were performed for different times in order to achieve three particulate matter loadings of 1.1, 2.2 and 4.1 grams of particulate/liter of filter. Active regeneration was carried out at three CPF-inlet temperatures of 500, 550 and 600\mDC to cover a range of temperatures and filter loadings for thermal regeneration. The dependent data of fuel usage, time of regeneration, mass of PM oxidized and maximum substrate temperature are presented as a function of mass loading and inlet CPF temperature. The results show that higher CPF-inlet temperature and particulate matter mass loading are more effective for regeneration of the CPF and lower fuel usage in grams of PM oxidized per gallon of fuel used whereas low temperatures and lower mass loadings were not as effective due to lower reaction rates. 90% of the HC from the diesel fuel injection were oxidized across the DOC while the other 10% were oxidized across the CPF under the test conditions.

Thermophilic biofiltration of methanol and α-pinene

Biofiltration systems utilizing thermophilic (55C) bacteria were constructed and tested for the removal of methanol and α-pinene — two important volatile organic compounds (VOCs) in the forest products industry. Thermophilic bacterial mixtures that can degrade both methanol and α-pinene were obtained via enrichment techniques. Two bench-scale thermophilic biofiltration systems (1085 and 1824 cm3) were used to examine compound removals at different residence times, with influent concentrations of 110 ppmv methanol and 15 ppmv α-pinene. At a residence time of 10.85 min, the smaller system had removal efficiencies of >98% for methanol, but only 23% for α-pinene. The larger system was operated with the same parameters to evaluate residence time and surfactant effects on compound removals. At a residence time of 18.24 min, both methanol and α-pinene removal rates were ≥95%. However, α-pinene removal dropped to 26% at a residence time of 6.08 min; methanol removal was not affected. Subsequent addition of a surfactant mixture increased α-pinene removal to 94% at the shortest residence time. No residual α-pinene was detected with the support medium Celite R-635, indicating that the surfactant may increase mass transfer of α-pinene. Journal of Industrial Microbiology & Biotechnology (2001) 26, 127–133.

Interlaboratory comparison of HPLC-fluorescence detection and GC/MS: analysis of PAH compounds present in diesel exhaust.

For laboratories involved in polycyclic aromatic hydrocarbon (PAH) analyses in environmental samples, it is very useful to participate in interlaboratory comparison studies which provide a mechanism for comparing analytical methods. This is particularly important when PAH analyses are routinely done using a single technique. The results are reported for such an interlaboratory comparison study, in which the four selected participating laboratories quantitatively analyzed several PAH compounds in diesel exhaust samples. The samples included particle and vapor phase extracts collected and prepared at Michigan Technological University (MTU PE and MTU VE, respectively), a diesel particle extract prepared by the National Institute for Standards and Technology (NIST, SRM 1975), and a fully characterized diesel particle sample (NIST SRM 1650). One of the laboratories used only HPLC-FLD, one used only GC/MS and two laboratories used both methods for the routine analysis of PAH in environmental samples. Data were obtained for five PAH compounds: fluoranthene, pyrene, benz[a]anthracene, benzo[a]pyrene, and benzo[g, h,i]perylene. The mean PAH levels found for SRM 1650 were outside the range reported by NIST. The range in the reported means was from 24% lower than certified for benz[a]anthracene to 41% higher for benzo[g,h,i]perylene. For the previously uncharacterized samples in this study (SRM 1975, MTU PE and MTU VE), two-thirds of the reported results were higher for the HPLC-FLD method than for the GC/MS. The range in differences between methods was from-54 to+31% calculated as the difference in GC/MS value relative to the HPLC value for each of the compared compounds. Coefficients of variation for the uncharacterized samples appeared to be higher, in most (but not all) cases, for the HPLC-FLD than for the GC/MS. The resolution of certain PAH isomers (e.g. benz[a]anthracene and chrysene, or the benzofluoranthenes), was better, as expected, for HPLC than for GC. Generally lower detection limits (by an order of magnitude or more) were reported for GC/MS than for HPLC-FLD. On the basis of this limited study, it seems as though significant differences may exist between laboratories, if not between methods, in the analysis of certain PAH compounds in real diesel samples by HPLC-FLD compared to GC/MS. If possible, measurements should be made using both methods. This is particularly important where potential interferences are undefined or subject to change, as is frequently the case with real environmental samples.

Biofiltration for the removal and ‘detoxification’ of a complex mixture of volatile organic compounds

A study was performed to determine the effectiveness of using biofiltration for the removal of a complex mixture of volatile organic compounds (VOCs) air-stripped from petroleum hydrocarbons. A biofilter was constructed which contained 264 cm3 of packing material (Celite® R-635). The unit was inoculated with a mixed culture containing a hydrocarbon-degrading Pseudomonas sp and an Alcaligenes sp. Several of the major compounds in the VOC mixture were monitored individually, along with the total VOCs, using gas chromatography. The average influent concentration of the VOC mixture was 320 ppmv and the average total VOC removal rate was over 56%, with the average removal rate of the monitored individual compounds ranging from 49–90%. After 30 days of operation the average overall removal rate was 69% and the removal of the major compounds averaged 92%. The toxicity and mutagenicity of the air stream was monitored using the Microtox and Ames assays, respectively. These data show marked decreases in toxicity and mutagenicity of the air stream as a result of the biofiltration treatment. The biofiltration system, therefore, was not only effective in removing VOCs from the air stream over an extended time-period, but was also effective in greatly reducing the toxicity and mutagenicity associated with the remaining VOCs.

Characterization of mutagenic subfractions of diesel exhaust modified by ceramic particulate traps

Protocols were developed for collection and characterization of heavy-duty diesel exhaust hydrocarbons. Dichloromethane extracts of particulate and gaseous-phase samples were partitioned between hexane and methanol, and the highly mutagenic (Ames TA98) methanolic fractions were further separated with reverse-phase HPLC. Twenty-eight polycyclic aromatic hydrocarbons (PAH), including 4-nitro- and 13 oxy-PAH derivatives, were tentatively identified in the active (moderately polar) HPLC fractions with GC/MS. In terms of raw exhaust emissions (milligrams per cubic meter), the use of the ceramic traps caused reduced levels of particulate and associated organic compounds. Total mutagenic activity also decreased with the traps,but to a lesser extent than the decrease in particulate. Many of the identified PAH were common to both the particulate and gaseous-phase samples collected under the same conditions. Calculated hydrocarbon balances showed that more hydrocarbons passed through the samplers when the ceramic traps were used. 46 references, 5 figures, 5 tables.