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Microcosm experiments to enhance the bioremediation of a No.2 fuel oil-contaminated soilRunyon, Thomas Alvin, 1963- January 1989 (has links)
Soil microcosm experiments were conducted to identify soil amendments which enhance the biodegradation of a No. 2 (diesel) fuel in soil. Microcosm amendments in Phase 1 included yeast extract, acetate, methane, and activated sludge. Combinations of these amendments resulted in 16 different treatments. Phase 2 soil microcosms contained combinations of methane and methanotroph additions resulting in four different treatments. Gas chromatography was used to determine the time and treatment-dependent concentration of C12-C18 n-alkanes during Phase 1 and, C14-C19 n-alkanes during Phase 2. Results from Phase 1 indicated that the most extensive biodegradation occurred in methane and activated sludge-supplemented microcosms. Acetate and/or yeast extract inhibited biodegradation by soil and/or activated sludge microorganisms. Addition of methane relieved inhibition by these amendments. Methane and/or methanotroph additions to Phase 2 microcosms did not enhance biodegradation relative to unamended microcosms. In general, n-alkanes longer than n-C12 were equally degraded in soil microcosms.
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Polyphasic examination of microbial communities in soils contaminated with organic pollutantsJuck, David F. January 2001 (has links)
No description available.
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Polyphasic examination of microbial communities in soils contaminated with organic pollutantsJuck, David F. January 2001 (has links)
A polyphasic approach was used to examine the impact of contamination on soil microbial community structure. Two systems were examined using a combined biochemical and molecular biological approach. Petroleum hydrocarbon contaminated soils from two Northern Canadian sites, representing long-term contamination, were examined using Biolog GN plates and PCR-denaturing gradient gel electrophoresis (DGGE) analysis of total community 16S rDNA. Results obtained using both methods demonstrated a positive correlation between samples that was based on the geographical origin of the samples, not on contamination level. In the second system, non-contaminated soil was contaminated with the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) to monitor the effect of short- to medium-term contamination. Changes in the soil microbial community were examined using PCR-DGGE of total community 16S rDNA combined with RDX mineralization and chemical analysis of intermediates. The non-contaminated loam soil had an inherent RDX degradative capability and contamination of soil columns with 1000 mg RDX/kg soil did not significantly change the 16S rDNA bacterial community profile. The bacterial diversity remained high as estimated by the number of bands present in the DGGE and by NQ-78704 statistical rarefaction analysis of 16S rDNA clone RFLPs. The same soil, used in 10% soil slurries (w/v), demonstrated two apparently different RDX degradation mechanisms based on mineralization and chemical analysis. The differences were based on aerobic versus anaerobic conditions and the presence/absence of Na3 citrate. PCR-DGGE performed on 16S rDNA from aerobic slurries amended with Na3-citrate detected the stimulation of 3 operational taxonomic units, identified as Stenotrophomonas sp., Sphingomonas sp. and a member of the Alcaligenaceae. The results from the two systems examined (short- to medium-term and long-term contamination) demonstrated the utility of a polyphasic approach in the examina
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Cutting fluid aerosol from splash in turning : analysis for environmentally conscious machiningAtmadi, Alexander 08 1900 (has links)
No description available.
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Quaternary environmental changes and engineering properties of offshore soils in Hong KongChoy, Suk-fong., 蔡淑芳. January 2004 (has links)
published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy
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Assessment of cadium (Cd) and lead (Pb) contamination in the soils of pre-school facilities in the City of Cape TownNkoe, Nozi 'Mabafokeng January 2009 (has links)
Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2009. / In the last two centuries, the natural state of the environment has changed
significantly due to anthropogenic activities. With an estimated half-life of 15 -
1100 years for cadmium in soils, the metal remains a threat to the ecosystem. In
general, most soils contain <1 mg/kg, except those contaminated from discrete
sources or developed on parent materials with very high cadmium contents.
Anthropogenic lead in soil has several well recognized major sources, namely,
lead based paint, mining and smelting activities, manures, sewage sludge usage
in agriculture and contamination from vehicle exhausts. Since lead is a heavy
metal, over time it will settle down and build up in soil. The main aim of this study
was to determine the degree of cadmium and lead contamination of soil, in and
around selected pre-school facilities in the City of Cape Town (CCT). A number
of pre-school facilities, particularly those nearby heavy traffic, were selected in
the CeT. Natural soil and sand pit soil samples were collected and analysed for
cadmium and lead. Low soil moisture is normally associated with high pH, as
found in the present study. High pH values are in turn associated with low toxicity
of metal contaminants. Most urban populations rely heavily on motor vehicles
and vehicle-related pollution has been an increasing concern in recent years
(before 2006). Air pollution in the CCT is trapped by inversion layers. In this
study it has been found that cadmium is not a significant contaminant in the soils
of pre-school facilities in the CCT. The Cape Town administration area was
found to be the most contaminated with this metal. This study showed that the
Cape Town administration area also had the highest lead concentrations in pre-school soils in the CCT. This can be attributed to the higher density of industry
and traffic activities (study conducted pre-2006) in this area. There is a need for
further research to determine the relationship between soil metal concentrations
and blood metal levels, especially in children.
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Biofilm Formation of Escherichia coli from Surface Soils is Influenced by Variation in Cell Envelope, Iron Metabolism, and Attachment Factor GenesPetersen, Morgan L. January 2018 (has links)
Biofilm formation may increase survival and persistence of Escherichia coli in the highly variable conditions of soil environments, though it remains unknown the extent variation in biofilm formation affects survival. We asked what genetic traits influence biofilm formation in phylogroup D E. coli isolates from surface soils, and are they associated with the soil environment? Biofilm density was analyzed and compared with soil environment characteristics. Isolates produced more biofilm per unit growth at 15°C than 37°C. Biofilm formation was greater in soil isolates than fecal isolates and in soils with moisture and higher calcium and pH levels. A GWAS analysis found variants involved in cell envelope formation and structure were associated with biofilm formed at 37°C, and stress response and iron acquisition variants were associated with biofilm formed at 15°C. Motility variants were associated with a negative effect on biofilm formed and adhesion variants associated with a positive effect. / National Science Foundation (NSF) award no. DEB-1453397 to P.W.B. / ND-EPSCoR
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A Study of Soil Organic Matter and Its Controlling Factors in Portland, OregonDillon, Megan 01 January 2011 (has links)
Traditionally, local above- and below-ground plant and microbial communities, temperature and precipitation, topography and texture and composition of parent material have been thought to govern the soil processes that lead to soil organic matter accumulation over decades or centuries. Soil organic matter is a substantial global reservoir of carbon and disturbance of equilibrated soils often leads to efflux of significant quantities of CO2. Anthropogenic influences shift the inputs, disturb the structure and alter the biochemistry of soil, profoundly disrupting soil-forming processes. Urbanization leads to soil organic matter equilibria that are different from those in naturally forming soils. Measurement of soil organic matter in diverse cities suggests that they differ in their capacity to accumulate soil organic matter. Here I quantify soil organic matter and examine the limitations of its accumulation within cities by comparing differences in soil organic matter and natural and anthropogenic characteristics at the neighborhood, city and regional scales in Portland, Oregon to that in the Pacific Northwest. I found that each Portland neighborhood has distinct urban characteristics and tree and shrub community composition, but soil organic matter content is indistinguishable among them. Across Portland, neither vegetation structure nor urban factors appear to directly influence soil organic matter content. Rather, microbial biomass, bulk density and total nitrogen appear to be important factors controlling soil organic matter content in Portland. The amount of soil organic matter stored in Portland's soils is statistically indistinguishable from Pacific Northwest soils, in contrast to other temperate cities.
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The Influence of Acid Rain on the Engineering Properties of a Sensitive ClayHoppe, Edward 02 1900 (has links)
No description available.
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Effect of perennial water on soil, vegetation and wild herbivore distribution in southeastern Zimbabwe.Clegg, Sarah. 19 December 2013 (has links)
The effects of artificially supplied perennial water on soil properties, vegetation dynamics and the
distribution of large herbivores was investigated in southeastern Zimbabwe. Data collection took
place between March 1997 and July 1998. Water points were situated primarily on three different
soil types (clay-loam, sandy-clay-loam and sand), and in four different vegetation types (Hill
communities, Colophospermum mopane veld, Acacia nigrescens woodland and Albizia petersiana
woodland). One water point in C. mopane veld (Bandama) had been closed two years prior to data
collection, while another, in the Hill community (Manyoka), had been introduced, two years prior to data collection.
Changes in physical (infiltration) and chemical (organic carbon and nutrients) properties of
soils around water points were largely restricted to within 100 m of water. Chemical enrichment of
the soil occurred only at water points that had been in place for more than two years. Soil surface
conditions were altered to distances beyond 100 m from water. Manyoka (the new water point) was
an exception, with extreme changes limited to within 100 m of water.
Herbaceous and woody species composition changed in response to distance from water
with changes best described by asymptotic equations. Changes in species composition of the woody
component appeared to be longer lasting than changes to the herbaceous component. Most perennial
grass species declined close to water, but Urochloa mosambicensis increased close to water in areas
outside of the Hills. Herbaceous species diversity was adversely affected by distance from water on
sandy soils (Hill communities and A. petersiana woodland), but was largely unaffected on clay-loam
(A. nigrescens woodland) and sandy-clay-loam soils (C. mopane veld). Woody species
composition and density was altered out to 500 m from perennial water in Acacia nigrescens
woodland on clay-loam soils. Results suggest that this vegetation type may be susceptible to bush
encroachment close to water. Trends in woody canopy utilisation were generally similar to trends in
woody species composition, and it is proposed that the former may be used to indicate future
changes in the latter. Conversion of trees to shrubs was highest at Manyoka (the new water point)
indicating that woody destruction by elephants is extreme during the initial years following water introduction.
Large herbivore biomass was greatest close to water (< 1 km) during the dry season but not
during the wet season. Herbivore species distributions appeared to be influenced by the position of
perennial water, but since all range was within easy access of water, it is unlikely that animal
distributions were constrained directly by the position of surface water. It is more likely that
herbivores were spatially separated on the basis of habitat type. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1999.
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