Dissertationen: „Soil biology“

1

Li, Ka Chi Jarvis. „The biology of deep soil microbacteria“. Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58949.

Der volle Inhalt der Quelle

Annotation:

The use of antibiotics to treat bacterial infections has been one of the most significant breakthroughs in modern medicine. However, drug resistance is increasingly threatening the efficacy of the current repertoire of antimicrobials. The search for novel classes of antimicrobials from microbes in varied natural environments has become a useful approach to this issue. The topic of my thesis is to study the resistome and the microbial composition of deep soil samples collected from the Vancouver campus of UBC, and to use these soils in the isolation of Actinobacteria with the potential of producing new antimicrobials. The detection of antibiotic resistance genes in these soils was carried out by a PCR approach. I found a spatial relationship between the presence of genes aac(3), erm, vanX and tetM/otrA and the different microbial populations in various layers of soil. The bacterial community compositions of these soils were determined by metagenomic sequencing of the small subunit 16S rRNA gene. The results of these analyses prompted a search in the Actinobacteria-rich soil samples as the sources for isolation of novel antibiotic-producing bacteria. Twenty-two bacterial isolates were isolated and screened for the production of inhibitory compounds against a panel of bacterial pathogens. The principal focus of this thesis is the study of Microbacterium strains isolated from soil. Microbacterium is a genus of Actinobacteria first discovered in 1919 by Dr. Sigurd Orla-Jensen. To date, there have been 97 distinct species of microbacteria identified from a wide variety of natural, clinical and manmade environments. Representatives of the genus have been implicated as plant commensals and for the bioremediation of environmental contaminants. The microbacteria have not been studied for the production of antimicrobials. Microbacterium sp. D3N3, isolated from a deep soil sample, produces phenylacetic acid which displays broad-spectrum antimicrobial activity and other bioactivities such as gene activation in Staphylococcus aureus as well as weak additive interactions with the antibiotics tetracycline, colistin, ampicillin and novobiocin. Four microbacteriophages that infect two Microbacterium strains from this work were isolated from the UBC wastewater treatment plant, sea water and a soil sample from UBC Wreck beach.
Science, Faculty of
Microbiology and Immunology, Department of
Graduate

APA, Harvard, Vancouver, ISO und andere Zitierweisen

2

Schneider, Katja. „Feeding biology and diversity of oribatid mites (Oribatida, Acari)“. Phd thesis, Connect to this title online, 2005. http://elib.tu-darmstadt.de/diss/000585/.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

3

Sutanto, Yovita. „Manure from grazing cattle effects on soil microbial communities and soil quality in northern West Virginia pastures /“. Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3933.

Der volle Inhalt der Quelle

Annotation:

Thesis (M.S.)--West Virginia University, 2005.
Title from document title page. Document formatted into pages; contains vii, 72 p. : ill. (some col.), map. Includes abstract. Includes bibliographical references.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

4

Reeve, Jennifer Rose. „Soil quality, microbial community structure, and organic nitrogen uptake in organic and conventional farming systems“. Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Summer2007/j_reeve_071207.pdf.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

5

Sheremata, Tamara W. „The influence of soil organic matter on the fate of trichloroethylene in soil“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0017/NQ44582.pdf.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

6

Carter, Jonathan Philip. „Population biology of Trichoderma spp. used as inoculants“. Thesis, University of Reading, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329046.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

7

Heppell, James. „Optimising plant and soil management“. Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/373886/.

Der volle Inhalt der Quelle

Annotation:

This thesis is an accumulation of work regarding the role of phosphorus (P) and water in soils in relation to crop growth and food production. We use a multiscale modelling approach to initially capture the interactions of soil and water on a single cylindrical root and further expand to a growing root structure. Moreover, we have a multi-physics problem involving fluid dynamics of water uptake in plants, and reactive solute transport in the soil for plant P uptake. We use detailed climate data and the super computer at the University of Southampton (Iridis 4) to parameterise our models. These facilities allow us to analyse the root structure as well as P and water in the soil in great detail. The collaboration of mathematics, biology and operational research makes it possible to complete this project. The analytical models recently developed within our group have shown to agree remarkably well with full 3D simulation models. These analytical models help provide the structure for the models used within this thesis and will for the first time enable us to start using optimisation techniques to find the optimal conditions for increasing plant P uptake efficiency. By using mathematical models to predict plant P and water uptake within the soil, we have addressed a number of questions surrounding the optimal plant root structure for P accumulation, and the survival of crops in a low P environment. In addition, we were able to predict the behaviour of water in the soil over the course of a full year. And finally, utilising all the above, we have outlined the optimal fertiliser and soil management strategy.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

8

Ives, David. „Assessing the Impact of Genetically Modified Canola Cultivars on the Biology of Soil“. Thesis, Griffith University, 2017. http://hdl.handle.net/10072/370734.

Der volle Inhalt der Quelle

Annotation:

Biotechnological development of transgenic crops and widespread international adoption has stimulated comprehensive research into their effects on the soil environment. Insects (both target and non-target), weeds, aquatic environments, and soils have all been extensively researched. Since the first commercial GM crop in 1995, the debate surrounding controversial aspects of their biology has polarised issues concerning insects, weeds, and the concentration of technology within a few multinational biotechnology corporations. The effect of transgenic crops on the biology of soils seemed to attract less attention. This thesis examines the interactions between transgenic canola plants through their root exudates and residues with the surrounding soil, its microbes, and their biology. The discovery of the commensal relationship of root exudates and their microbial partners has revolutionised the research into soil microbiology. From this knowledge of soil science, scientists now understand the critical importance of a healthy and abundant soil biome. This thesis focuses on the microbiology of soil. The effects of genotype on soil bacterial and fungal physiology of genetically modified (GM) canola are compared statistically with other cultivars which are genetically modified through conventional plant breeding rather than through genomic engineering, and with the canola cultivar from which the GM variety was developed. The research differentiates the effects of four canola genotypes on microbial DNA and enzymology in a greenhouse trial format. Specifically, the objective of the research is to focus on changes in microbial enzymatic activity of key functional enzymes in protein metabolism, and carbon (C), phosphorus (P), and sulphur (S) mineralisation. The effects on DNA concentration are also studied. The main results of this research generally suggest the effects of cultivar genetic differences with respect to their interactions through root exudates and residues on microbial enzymatic activity are generally not significantly different. Moreover, there are no significant differences in the effect of root exudates on DNA concentrations. This generally accords with the majority of refereed publications and therefore provides confidence to the growing of transgenic canola and to transgenic plants and technology generally. The review and analysis conducted also indicates an emerging trend to broaden the research efforts onto the study of farms and the systems of agriculture under which crops are grown. The findings of this thesis are based on an experimental method and data gathering using phosphorescence to measure changes in enzyme activity and DNA concentration. The statistical analysis employed ANOVA with randomised complete blocking for repeated measures using multiple sampling during the course of the plant‘s lifespan. Further statistical analysis using one-way ANOVA and sequential linear modelling were also employed to study the nature of effects in more detail where the initial analysis suggested significant differences. Furthermore, panel regression analysis examined time-series effects to gain an understanding of how sampling date and therefore stage of the plant‘s growth affected outcomes. The panel analysis indicated that Beta-gluconase enzyme activity significantly influenced soil DNA concentrations. There were limited numbers of occasions when statistical differences between genotypes were found. Overall the experimental results favour the argument that the transgenic canola crops do not damage the soil environment in any significant manner. Therefore it seems that the crops may safely continue to play a major role in meeting the future challenges of world food security. The qualitative data gathered via visits to contributing canola growers during the study enabled comparisons to be made between real world practices with experimental results, as well as results from the literature. Together such a process allowed the author to gain significant insights into the complex decisions the farmers must make in the choice of their employed technologies, including seed genetics. In summary, the major findings are:  minimal impact on protein and amino acid metabolism;  little or no effect on P mineralisation;  carbohydrate metabolism through breakdown of C residues unaffected;  minimal changes in S metabolism;  insignificant differences in DNA concentrations between genotypes;  some insights gained into the nutrient needs of microorganisms;  measurement by phosphorescence is both practical and inexpensive;  there were a number of environmental advantages emerging from the use of GM technology, including improved accumulations of soil carbon through organic matter increase and improvement in soil structure and fertility, as well as changes to less toxic and persistent herbicides;  productivity improvement created by GM technology is comparable with results from conventional plant breeding There are some limitations to the study that should be noted, as follows:  The impact of herbicides on microbial physiology was not explored due to aspects beyond the scope of this study;  The study on the whole was a greenhouse situation and did not directly involve farms;  The study was limited to one soil type (Vertisol) as a second soil type (Chromosol) inhibited germination and growth of the canola seedlings. An attempt to explore the types and Orders of microbes and how they changed during the development of the various plant genotypes was unsuccessful technically. The following areas are suggested as being relevant for further investigation:  Phospho Lipid Fatty Acid extractions and genomic techniques remain desirable technologies if resources and experience are available to implement them. These complex technologies can quantify individual microorganisms, including pathogens, giving deeper understanding;  Additional information about the effect of herbicides on the criteria being measured would be helpful in differentiating their impact alone on microbial function. This would require special analytical chemistry procedures for herbicide residue extraction and chromatography, a larger study, and greater financial resources;  Translating the experiment to a field study over several years in differing soil types would produce additional information such as yields, production penalties, respective costs, and practical outcomes, as well as soil microbial effects and thus provide a complete picture for the issues involved. Hence a clearer choice of the systems under which different cultivars are grown can be related to environmental outcomes.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text

APA, Harvard, Vancouver, ISO und andere Zitierweisen

9

Schradin, Kelly Dawn. „The role of plant-soil feedback in exotic plant invasion: soil type, biotic or abiotic factors?“ Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1334073581.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

10

Morris, Sherri Jeakins. „Distribution patterns and scale dependency of microbial abundance and processes in relation to soil chemistry and vegetation in hardwood forest soils /“. The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487949508367988.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

11

Drees, Kevin Paul. „Quantitative analysis of soil microbial diversity in the hyperarid Atacama Desert, Chile“. Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/284318.

Der volle Inhalt der Quelle

Annotation:

The Atacama Desert of northern Chile is one of the most arid regions on Earth. The central plateau, between the coastal escarpment and the Andes, is devoid of vegetation and receives only millimeters of rain every few years. Though plants are absent in the soils of this desert, perhaps bacteria can survive, and even thrive, in these hyperarid conditions. This dissertation represents the first comprehensive study of bacterial diversity in the driest central latitudes (approximately 24°S) of the Atacama Desert. Study 1 covers the development of a soil DNA extraction method for the study of soil bacterial populations. This method was field tested in an ecology study in the Santa Catalina Mountains of southern Arizona. In Study 2, Atacama soils were sampled in two transects at approximately 24°S and 25°S. The first transect runs across the absolute (plantless) desert and through several narrow bands of sparse vegetation at high altitudes in the Andes. The second transect is within the well-developed fog zone near Paposo on the Pacific coastal escarpment, where an endemic plant community called lomas is established. Analysis of DGGE profiles of bacterial !6S rRNA genes extracted from these soils with Kruskal's Isotonic Multidimensional Scaling indicates that the bacterial populations cluster into several groups, including the low diversity populations of the core absolute desert, and the higher diversity high elevation Andean populations influenced by the vegetation of Andean biomes. Only one group clustered in the lomas; the rest of the profiles were unique, demonstrating the high diversity of bacterial populations within this diverse vegetation community. Soil 3107, which is within the absolute desert, clustered with the Andean bacterial populations. This soil lies within the transition zone between the low precipitation of the absolute desert (approximately 2.4 mm per year) and the higher precipitation of the high elevation Andes (approximately 47.1 mm per year). This Andean bacterial population may extend further into the absolute desert than the Andean vascular plants due to superior aridity tolerance. Alternatively, this bacterial population may be a relic from when the Andean vegetation advanced through this elevation in a wet period 3000 years ago.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

12

Eriksson, Mikael. „The Role of Soil Biology and Plant Health – Brandywine Tomatoes Grown with Different Microbial Additions“. Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-290296.

Der volle Inhalt der Quelle

Annotation:

The microbial life in the soil is essential for providing a functioning habitat for plants to grow. A literature study was conducted to investigate the knowledge and science behind soil biology. The purpose of this study was to define what is soil health and how it is influenced by the soil microbial communities. The literature study concluded that the ability of soil biology to benefit plants includes a variety of aspects. Nutrient availability, soil structure and pest resistance are all greatly influenced by soil microbes. To practically examine these theories, an experiment was conducted where Brandywine tomatoes where grown in three different scenarios. A commercial potting soil, Hasselfors ekojord, was used as substrate in all groups. In the control group (C) the plants were grown only in the substrate. In the second group (R), the seeds where treated with a microbial inoculum and then planted in the substrate. In the third group (RE), the same treatment as in R was done to the seeds and here, compost extract were also added to the RE group. The plants were grown in separate pots in a greenhouse and the growth rate was observed and documented as well as the total harvest. In the end of the growing season a chemical and biological analysis was done to the soil as well as a sap analysis on the leaves. The plant growth where similar among the groups although R and RE showed slightly higher growth rates in the later stages of the growing season. The harvested fruit was highest in C but not significantly. The microbial contents were high in all soils though more fungi communities in the RE and bacterial communities in C. The chemical analysis showed high nitrate concentrations in the leaves in C. In R and especially RE the nitrate conversion into amino acids and proteins where higher wish indicates that these groups are more resilient to pests like aphids.
Det mikrobiella livet i jorden är avgörande för att skapa en fungerande livsmiljö för växter. En litteraturstudie genomfördes för att undersöka nuvarande kunskap och vetenskap bakom markbiologi. Syftet med denna studie var att definiera markhälsa och hur den påverkas av det mikrobiella livet i jorden. Slutsatsen från denna litteraturstudie var att jordbiologins förmåga att gynna växter innefattar en rad olika aspekter. Näringstillgänglighet, markstruktur och skadedjursbeständighet påverkas starkt av jordmikrober. För att praktiskt granska dessa teorier genomfördes ett experiment där Brandywine-tomater odlades i tre olika scenarier. En kommersiell plantjord, Hasselfors ekojord, användes som huvudsubstrat i alla grupper. I kontrollgruppen (C) odlades växterna endast i substratet. I den andra gruppen (R) behandlades frön med en mikrobiell ympning innan de såddes i substratet.I den tredje gruppen (RE) utfördes samma fröbehandling som i R och kompostextrakt tillsattes också till RE-gruppen. Växterna odlades i separata krukor i ett växthus och tillväxthastigheten observerades och dokumenterades liksom den totala skörden. I slutet av växtsäsongen gjordes en kemisk och biologisk analys av jorden samt en savanalys på bladen. Tillväxten var likartad bland grupperna även om R och RE visade något högre tillväxttakt i de senare stadierna av växtsäsongen. Skördad frukt per planta var högst i C, dock intesignifikant. Den mikrobiella koncentrationen var hög i alla jordar men mer svamporienterat i RE och bakterieorienterat i C. Den kemiska analysen visade högt nitratinnehåll i bladen i C. I R och särskilt i RE var nitratomvandlingen till aminosyror och proteiner högre vilket indikerar att dessa grupper är mer motståndskraftiga mot skadedjur så som bladlöss.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

13

Timling, Ina. „Peeking through a frosty window| Molecular insights into the communities of Arctic soil fungi“. Thesis, University of Alaska Fairbanks, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3607060.

Der volle Inhalt der Quelle

Annotation:

Fungi are thought to be one of the most diverse groups of organisms in the Arctic. They drive mineral and energy cycles and influence the occurrence of other organisms as mutualists (mycorrhizae, endophytes, lichens), decomposers and pathogens. Nevertheless, information on fungal biodiversity and distribution patterns in relation to environments across the Arctic is still sparse. Molecular methods were used to examine the diversity and community structures of ectomycorrhizal fungi (EMF) associated with two principal arctic host plants, Salix arctica and Dryas integrifolia, as well as total soil fungal communities of adjacent disturbed and undisturbed areas of patterned-ground features across the five bioclimatic subzones (A-E) of the North American Arctic. Key findings include the following: (1) More diverse fungal communities had been observed than previously known. These communities encompass nearly all fungal phyla and included all fungal guilds. However, a few species-rich fungal families dominated these fungal communities. (2) Surprisingly, species richness did not decline with latitude. (3) The most abundant fungal taxa were widely distributed in and beyond the Arctic. Yet root (EMF) and soil fungal communities showed niche preferences in regard to bioclimatic subzones. Furthermore, disturbed and undisturbed patterned ground features harbored different soil fungal communities with the exception of the coldest subzone A. In contrast, EMF community composition was not affected by host plant identity. (4) Fungal communities in the warmest subzone E were distinct from the other arctic subzones and the majority of taxa matched fungi from the boreal forest. (5) Key drivers of fungal community and guild composition along the bioclimatic gradient included regional climate, pH as well as vegetation composition and productivity across the subzones. At the local scale of patterned-ground features, fungal communities were correlated with vegetation composition and microclimate. With a warming climate, I would expect an enhanced colonization of patterned-ground features by vascular plants that would then affect fungal community structure not only at the species level, but also at the level of fungal guilds. In particular I would expect increases in fungi that are symbiotic with plants and a northward shift of both plant and fungal taxa.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

14

Vázquez, Rosa I. „Decomposition rates of organic amendments and soil organic matter fractions as indicators of soil quality : an on-farm study of organic and conventional dairy farms in Ohio /“. The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488202678776313.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

15

Fisha, Phuti Cedric. „Characterisation of selected soil properties using remote sensing techniques“. Thesis, University of Limpopo, 2019. http://hdl.handle.net/10386/2861.

Der volle Inhalt der Quelle

Annotation:

Thesis (M. Sc. (Soil Science)) --University of Limpopo, 2019
Many conventional laboratory methods are used to characterise spatial and temporal variation of soil properties in order to understand soil quality for different purposes. Currently there is a high demand for accurate soil information by land users. Therefore there is a need to develop a rapid, inexpensive, non-destructive and accurate technique that could compensate or replace conventional laboratory methodologies. Remote sensing has the potential to serve as an alternative approach to characterise soil properties due to its advantages over conventional laboratory methods such as it is rapid, non-destructive and it has low cost. The objectives of this study were to: (i) evaluate the ability of proximal soil sensing to characterise soil properties namely organic matter, soil moisture content, macronutrients, soil texture, cation exchange capacity (CEC), and pH. (ii) Identify bands of relevance from proximal soil sensing (300-2400 nm) that can provide acceptable reflectance variation for different levels of selected soil properties. (iii) Evaluate the performance of models developed from multispectral space-borne image in characterising selected soil properties. In this study spectroradiometer (proximal sensor) and worldview 2 satellite images (space-borne) were the two remote sensing techniques used to collect information about soil at Syferkuil experimental farm of the University of Limpopo. Visible and near infrared spectral data of 98 soil samples were collected at the study site using Analytical spectral device (ASD) field spectroradiometer. Spectral reflectance from spectroradiometer and those extracted from worldview 2 satellite image were used to develop prediction models of selected soil properties using Partial least square regression (PLSR). Bands of relevance were also identified from PLSR models developed from spectral data acquired by spectroradiometer. The results showed that estimation accuracy of PLSR models developed using spectral data from proximal soil sensing were excellent (Category A) for clay, sand, soil organic matter (SOM), and soil moisture content, while good prediction accuracy (Category B) was observed for other soil properties such as silt, ammonium, nitrate, active acidity (pHw), calcium, magnesium, phosphorus, potassium, sulphur, CEC, and reserve acidity (pHKCl). Then, relevant bands which contributed greatly in the prediction of these soil attributes were selected from the electromagnetic spectrum, the range was from 451 nm to 2400 nm. These bands fall within visible, shortwave infrared and near-infrared x regions of electromagnetic spectrum. In addition all selected soil properties were approximately quantitatively estimated using spectral data from satellite image. Based on the results obtained it can be concluded that proximal soil sensing has the ability to predict selected soil properties with various accuracies and it can be used as an alternative technique to characterise soil properties of South African soils. Soil predicting models developed from proximal soil sensing data also showed that there are bands of relevance within spectral range of 451 nm to 2400 nm. However more work is required for space-borne sensing before it can be used as one of the soil characterisation methods since its prediction accuracy was low as compared to that of hyperspectral proximal soil sensing. Keywords: Space-borne sensing; proximal soil sensing; soil characterisation.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

16

Al-Turki, Ahmad I. „Myrosinase activity in soil and impact of Brassica on plant-microbe interactions /“. The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486394475979013.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

17

Wiryono. „A Gradient Analysis of The Soil-Vegetation Complex in The Neotoma Valley /“. The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487935125882383.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

18

Ferdous, J. (Jannatul). „Germination and growth of Deschampsia cespitosa and Festuca ovina in arsenic soil“. Master's thesis, University of Oulu, 2018. http://urn.fi/URN:NBN:fi:oulu-201811173060.

Der volle Inhalt der Quelle

Annotation:

Arsenic contaminated soil is one of the major arsenic sources for potential harmful ecological impact on living organisms. Phytoremediation using viable plant species is an emerging, biological technology for the removal of toxic contaminants from soil. Although hyperaccumulating plants and plant varieties are known, there is still a need to find new (and preferably local) plant species for phytoremediation. The aim of this study was to investigate the germination and growth of two grass species common in the northern Fennoscandia with respect to the influences of high concentration arsenic. The study was conducted on Deschampsia cespitosa and Festuca ovina species that were collected from both arsenic contaminated and arsenic free areas at Green Stone Belt area in Kittilä, Central Lapland. Seed germination, seedling growth and cuttings growth in both the arsenic contaminated soil (collected from Kuotko area) and controlled soil (collected from Kallo area) were observed over a period of 8 weeks (2017 to 2018). Seed or cutting origin, soil type and inoculant plant origin, all either contaminated (arsenic) or control, were the studied factors. Germination and leaf number of Deschampsia cespitosa were significantly affected by contaminated condition originated seed and soil and performance was markedly better in controlled condition. Germination of Festuca ovina was also significantly higher in controlled condition originated seed although the performance was better in contaminated condition soil. Leaf number of Festuca ovina performed better in contaminated condition originated seed. In cuttings growth, leaf number For Festuca ovina, was higher in controlled condition originated plants than on contaminated condition. Oppositely contaminated condition soil type produced longer leaves. Leaf number and leaf length of Deschampsia cespitosa were not significantly affected by arsenic treatment. Festuca ovina resulted slightly higher shoot biomass in controlled condition than contaminated condition. Root biomass of both Deschampsia cespitosa and Festuca ovina were not affected by arsenic treatment. The overall results show that Deschampsia cespitosa and Festuca ovina were both affected in the arsenic concentrated soil. However, Deschampsia cespitosa did suffer from high arsenic soil conditions whereas Festuca ovina was as fruitful in arsenic concentrated soil as in control soil in all the greenhouse growth experiments including germination and growth results.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

19

Mueller, Sabrina R. „Chromium, DNA, and Soil Microbial Communities“. Cincinnati, Ohio : University of Cincinnati, 2006. http://rave.ohiolink.edu/etdc/view.cgi?acc_num=ucin1141334651.

Der volle Inhalt der Quelle

Annotation:

Thesis (Ph. D.)--University of Cincinnati, 2008.
Advisor: Brian K. Kinkle. Title from electronic thesis title page (viewed Apr. 23, 2009). Keywords: SEC-ICP-MS; Fungal community; bacterial community; DGGE. Includes abstract. Includes bibliographical references.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

20

Ramsay, Amanda J. „Early changes in soil under birch and heather“. Thesis, University of Aberdeen, 1990. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU548639.

Der volle Inhalt der Quelle

Annotation:

Heather plants were established, by Dr. John Miles, in gaps created in existing birch stands in 1979 at Craggan (NJ190322) and birch trees planted in heather moorland during 1977-1980 at Delnalyne (NJ189175). This study attempts to identify the processes leading to differential soil development beneath the two contrasting vegetation types over the period 1985-88 i.e. c 6 years after establishment. Field work involved the chemical analysis of soil solution and estimates of microbial biomass and basal respiration rates under birch and heather at both sites. Laboratory-based experiments were conducted to investigate the trends observed in the field. Major changes in soil processes were attributed to rapid growth and therefore nutrient uptake by the transplanted species. However, some of the changes due to birch trees, which were observed during studies of birch chronosequences by Miles &'38 Young (1980) and Miles (1981) can be attributed to high nutrient inputs in throughfall and litter under birch, which affect abiotic processes and stimulate microbial activity and nutrient transformation rates. Root inputs also influenced biological processes.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

21

Gentry, Terry Joe. „Molecular ecology of chlorobenzoate degraders in soil“. Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/289936.

Der volle Inhalt der Quelle

Annotation:

A series of three experiments were conducted to determine the diversity of indigenous chlorobenzoate (CB) degraders in soil and to investigate the use of different methods of bioaugmentation for remediation of contaminated soil. In the first study, soil was amended with either 500 or 1000 μg of 3-CB g⁻¹ and was either uninoculated or inoculated with the 3-CB degrader Comamonas testosteroni BR60. Bioaugmentation with C. testosteroni BR60 increased 3-CB degradation at both contaminant levels, and the increase was more pronounced at the higher level due to contaminant inhibition of indigenous 3-CB degraders. Bioaugmentation also appeared to reduce the deleterious effects that 3-CB contamination had on indigenous soil microbial populations as evidenced by changes in culturable heterotrophic bacterial populations. In the second study, two similar pristine soils were contaminated with 500 μg of 2-, 3-, or 4-CB g⁻¹ . The two soils differed in their ability to degrade the compounds with one degrading 2- and 4-CB and the other degrading 3- and 4-CB. Several hundred degraders were isolated, grouped according to DNA fingerprints, and selected degraders were identified by 16S rDNA sequences. The identity of the CB degraders differed between the two soils. The results indicated that the development of 2-, 3-, and 4-CB degrader populations was site-specific even for the soils that developed under similar soil-forming conditions. The third study also used the two soils from the second study. This project investigated the potential for use of activated soil, which contained an indigenous degrader population, as a bioaugmentation inoculant. An aliquot of a given soil that contained an indigenous 2-, 3-, or 4-CB degrader population was added to a soil that did not have an indigenous degrader population for the same contaminant. The study found that bioaugmentation with activated soil increased degradation of each 2-, 3-, and 4-CB but only if the activated soil was pre-exposed to the contaminant prior to use for bioaugmentation. The results from these three studies indicate that CB degrader populations are diverse and variable in pristine soils and, if not present in contaminated soils, appropriate degrader populations may be established via different bioaugmentation strategies.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

22

Baker, Paul. „The distribution and diversity of actinomycetes in soil fractions“. Thesis, University of Warwick, 1997. http://wrap.warwick.ac.uk/59518/.

Der volle Inhalt der Quelle

Annotation:

The results presented were concerned with the survival of Streptomyces coelicolor A3(2) (pll673) inoculated into soil microcosms, which were destructively fractionated so that the total propagules and spore counts could be determined in each of the soil fractions. It was found that this microorganism became associated with the smallest soil aggregates at the time of inoculation but with incubation of the soil microcosms the mycelia and spores became attached to the larger soil aggregates. In the sterile soil, the streptomycete growth was much greater than in nonsterile soil, perhaps due to the increased supply of nutrients created by autoclaving the soil, and the lack of competition. Many of the newly formed spores in sterile soil were not attached to the soil aggregates, which may have enabled them to be distributed to new micro sites. When the distribution of indigenous actinomycetes in soil was investigated, it ressembled the distribution of Streptomyces coelicolor in nonsterile soil after the inoculant had been through one life cycle. Actinomycetes were then isolated from each of the soil fractions, as well as the unfractionated soil, and each of these strains were identified to genera, if possible. It was found that many of the micromonosporas and streptosporangia were isolated from the 63-251 μm soil aggregates, probably because this fraction contained low eubacterial and streptomycetes populations caused by the low organic content within this soil fraction. There was a high eubacterial count in the 2-20 μm soil aggregates and although the actinomycetes were outcompeted within this soil fraction, their diversity was greatest within this fraction. This diversity was also reflected by their production of different secondary metabolites. DNA was extracted from each of the isolates and amplified using specifically designed primers for high GC microorganisms. Each of the products were individually run on denaturing gradient gels. It was found that the amplified products from actinomycetes formed bands on the denaturing gels which migrated to 3 positions. Each of these positions corresponded to major groups of actinomycetes of which streptomycetes formed one group. The patterns corresponding to the isolates of each soil fraction would be compared with the amplified products derived from in situ soil DNA extracts. It was found that the results were not comparable but this work is still being investigated.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

23

Keskin, Sheena Margaret. „Photosynthetic adaptations in grasses to abnormal levels of soil cations“. Thesis, University of Central Lancashire, 1985. http://clok.uclan.ac.uk/20893/.

Der volle Inhalt der Quelle

Annotation:

This research investigated adaptation of photosynthesis manifest in populations of grasses adapted to growth on abnormal levels of cations. The main investigative plants belong to the Agrostis genus. Plants were sampled from habitats with soi.ls which provided a range of abnormal levels of cations; mine spoil sites with heavy metal contaminations, calcareous and acidic sites with contrasting levels of cations particularly calcium and serpentine sites with low calcium and high magnesium and nickel levels were sampled. Barley and lettuce were used as comparative material as they are more routinely used in photosynthesis investigations. A commercially available seed stock of a heavy metal tolerant cultivar of Festuca rubra was compared with a non—tolerant cultivar. The comparative responses of plants to metals were examined using a range of monitors of photosynthetic reactions including fluorescence, oxygen evolution and light—induced electron transport. Techniques involving the measurement of steady state emission fluorescence spectra of excised leaves were standardised and applied. The soil conditiens were shovn to have a marked effect on the flucrescence spectra of leaves of barley plants grown in a rccge of soil typcs. The assay of light—induced oxygen evolution from excised leaf segments of the Merlin cultivar of Festuca clearly showed that increased resistance to metal inhibition is also present in the leaves as well as in the roots. The increased tolerance could be due to modifications of the cell wall or cytoplasm as has been extensively studied in the root. However a greater relative metal tolerance was also demonstrated in this cultivar at the level of the chioroplast membranes. Isolated, broken (type D) chloroplasts from ten Agrostis ecotypes showed a variation in their sensitivities to metals in the light—induced photosynthetic electron transport through photosystem 2. The chloroplasts from the mine spoil Agrostis races were more resistant to inhibition by the heavy metals (Pb, Zn, Cu, Ni, Cd) in general, although the degree of tolerance did not always relate directly to the root toiernr.ce indices or exchangeable soil metal content. A co—sensitivity between calcium and cadmium was revealed in the roots and in the chloroplasts which is probably related to the similarity in the two cations ionic radii. Plants from high calcium soils showed an increased tolerance to cadmium. The results recorded from work on chlorcplasts isolated from lettuce, barley and Agrostis ecotypes showed that Ca" can have fundamental effects on photosynthesis, both stimulatory and inhibitory. Ca 2+ was shown to stimulate the light—induced photosynthetic electron transport rates through PS2 and to protect isolated chloroplasts from loss of acti'Qity with ageing. Hcwever the degree and nature of the Ca2+ effect was dependent on plant species, ecotype, growing conditions and experimental protocol of CaZ+ addition. 'A marked inhibition with incubation in Ca' 4 after IL extraction was measured in four Agrostis races which originated from soils with low exchangeable calcium levels. However not all low soil_CaZ+ Azrostis ecot ypes were inhibited and this was interpreted to indicate a division between distributional calciftges and physiological calciophcbes. SE! PAGE profiles of chloroplasts from within Agrostis and Festuca were compared for differences in the band regions reported in the literature to be associated with metal tolerance and Ca2+ binding in other species. Variations in the levels of proteins in the 30 and 36 kDa ranges have been obsened in the Pb— and Znresistant Festuca. In the Agrostis, Ca 2 /Cd'' sensitivity in three races is co—incidental with reduction in a band La the region of 30-33 kDa. A loss or gain of a specific band could not be associated with heavy metal tolerance in the Agrostis chloroplasts. It is therefore clear from this work that photosynthetic activity of isolated chloroplasts depends on (a) the heavy metalard Ca2+ content of the soils at the collection site (b) the Ca2+ level of the growth medium (c) the level of Ca 2 in the extraction buffer. The variable ebloroplast activity is probably a reflection of genetic adaptations of the plants to variable growth conditions. This is reflected in variations in proteins in the chloroplasts.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

24

Barakat, Mohammad 1962. „Seasonal fluctuation in soil and thatch microbial populations in an 80%:20% sand:peat creeping bentgrass putting green“. Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/277909.

Der volle Inhalt der Quelle

Annotation:

A study was conducted to determine the influence of a bio-organic amendment 'Greens Restore' (6N-1P-3K) and a nitrogen fertilizer (21N-7P-14K) on the microbial numbers, thatch degradation, and soil respiration. A complete randomized block design was used with 3 treatments/4 replications. Both treatments were applied at a rate of 28.6 kg N/ha every 60 and 30 days for the first and second year respectively. No significant changes were observed due to treatments for all the parameters measured except for soil fungi and thatch thickness. Control plots had the lowest and the fertilized plots had the highest values for both parameters. Microbial numbers showed significant differences with time except for the denitrifiers. Thatch bacterial, fungal, and actinomycetes numbers were greater than in soil. Two peaks in microbial numbers and soil respiration occurred in spring and autumn. Soil pH also changed with time and peaked in spring and autumn.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

25

Leiva, Soto Andrea S. „Effects of Soil Balancing Treatments on Soils, Vegetable Crops and Weeds in Organically Managed Farms“. The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu151514193894181.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

26

Turk, Colleen Mary 1961. „The effect of microorganisms on soil structure development in copper mine tailing“. Thesis, The University of Arizona, 1995. http://hdl.handle.net/10150/291594.

Der volle Inhalt der Quelle

Annotation:

Organic matter amendments have long been known to improve native organic matter content, aggregation and structure of soils. In the laboratory, however, organic matter amendments to autoclaved soils have no such effect. This may explain the failure of many reclamation attempts on mine tailing wastes, which often proceed without regard for the microbiological processes necessary for soil formation and cycling of plant nutrients. In this study, incubation of tailing waste with soil microbes and a simple carbon source proved sufficient to increase the formation of water stable aggregates from tailing particles. Autoclaved control samples showed no change in aggregation. The incorporation of microbial cell mass into the mineral matrix of the tailing was observed using scanning electron microscopy. These results suggest that microbial activity is necessary in order to incorporate organic matter into the abiotic matrix of tailing, promoting aggregation and ultimately soil formation from this material.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

27

Buratti, James Paul. „Some soil-plant relationships of the halophyte, Salicornia europaea L“. The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1399561518.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

28

Nairn, Robert W. „Biogeochemistry of newly created riparian wetlands : evaluation of water quality changes and soil development /“. Connect to resource, 1996. http://rave.ohiolink.edu/etdc/view.cgi?acc%5Fnum=osu1251216965.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

29

Durrett, Melody S. „Spatial variability in plant and soil properties on New Zealand seabird islands, and the effects of introduced rats“. Thesis, University of Alaska Fairbanks, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3624440.

Der volle Inhalt der Quelle

Annotation:

Seabirds are ecosystem engineers with two major impacts on island ecosystems: they bring large quantities of marine nutrients to the terrestrial environment in the form of guano, carcasses, feathers, eggs, and spilled food, and they disturb the soil surface. Burrowing seabirds can denude the soil surface of all seedlings and leaf litter, plowing them under and loosening the soil. However, seabirds are colonial, and burrows are not even spaced over the surface of an island, producing spatial variability within a single island that might reveal how seabird activities control island ecosystem function.

In this dissertation I review seabird island ecology in general, focusing on how introduced predators have reduced seabird populations, interrupting seabird activities and altering island ecology. I then describe three studies designed to quantify the effects of seabirds on soil and plant properties within individual islands and compare these patterns across islands varying in seabird density, especially where seabirds have declined because of invasive rats (Rattus spp.).

I used geostatistics to quantify the spatial variance in seabird burrows and various soil and plant properties (including soil and leaf N) within six islands of low, intermediate, and high burrow density. I found that burrow density was not a good predictor at within-island scales, and though the variance of some soil properties (pH, soil δ¹⁵N, and soil compaction) peaked on intermediate islands as expected, variables reflecting the soil N cycle (net ammonification and net nitrification potential, NH₄⁺ and NO₃^-) continued to increase in variability on very high-density seabird islands. Ecosystem properties clearly responded to seabirds at different spatial scales, possibly because seabirds deposit guano at different spatial scales than they dig.

Using data within three rat-invaded and three rat-free islands, I used structural equation models to examine seabird influences on N cycling. I found some mechanisms that were constant across islands, such seabird-related decreases in soil water and pH, but other mechanisms differed between invaded and uninvaded islands, suggesting that rats manifest an alternative state for island N cycles, which may or may not be reversible.

Finally, I investigated whether plants can use ammonia (NH₃ gas) volatilized from seabird islands, measuring NH₃ concentrations across 10 islands and within a single island where I also experimentally manipulated plant N demand. Both rat-invaded and rat-free islands produced meaningful concentrations of NH₃ gas, and multiple plant species including Melicytus ramiflorus and Coprosma macrocarpa used it for up to 20% and 30% (respectively) of their total leaf N. Plant N demand modified NH₃ uptake, suggesting that plants located not on seabird colonies, but downwind, may benefit the most from this gaseous N source.

I suggest that future studies attempt to estimate thresholds of burrow density at which seabird-controlled ecosystem properties can recover from rat invasion.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

30

Diawara, Aïssatou. „Molecular and epidemiological studies on human soil-transmitted helminths before and after albendazole treatment“. Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119411.

Der volle Inhalt der Quelle

Annotation:

Soil transmitted helminths (STHs) are gastrointestinal nematodes of humans. Periodic deworming with albendazole (ABZ) and mebendazole (MBZ) is applied to control STHs. However, repeated treatment can cause selection of mutations in the β-tubulin gene at codons 167, 198 and 200 leading to resistance. To maintain an effective control strategy it is crucial to identify resistance, if any, at an early stage. Method: We have developed accurate molecular assays for STHs to detect β-tubulin genetic changes at codons 200, 167 and 198 associated with resistance. We also optimized the in vitro egg hatch assay (EHA) for canine hookworms and have applied it to human hookworms for assessing the response to BZs. Both assays have been tested on samples collected in endemic countries. Furthermore we carried out a 14-month longitudinal study in Haiti to investigate the response of STHs to two rounds of ABZ treatment in endemic communities naive for ABZ. Results: We validated genetic markers with control plasmids in hookworms, A. lumbricoides and T. trichiura for codons 167,198 and 200. We also identified at low frequency, before and after treatment, the resistance-associated SNP at codon position 200 in hookworms from Kenya, while the egg reduction rate (ERR) values indicated good drug efficacy. In A. lumbricoides, a SNP at position 167 was identified at high frequency before and after one drug treatment of subjects in Haiti, Kenya and Panama while ABZ efficacy remained high. In T. trichiura, the SNP at codon position 200 was detected and there was a significant increase in the homozygous resistance-type in Haiti and Kenya after one round of ABZ treatment. The associated drug efficacies, based on faecal egg counts (FEC), were low in Kenya and moderate in Haiti. From this result in Haiti, we classified subjects infected with T. trichiura into good, intermediate or poor ABZ responders. The frequency of SNPs 198 and 200 increased significantly after one round of ABZ treatment in the intermediate and poor response groups. Conclusion: This study has shown for the first time evidence of an association between genetic changes in the β-tubulin gene of T. trichiura and poor ABZ efficacy against this parasite.
Contexte: Les géohelminthes sont des nématodes parasitant le système gastrointestinal de l'Homme. Pour lutter contre les géohelminthiases une des stratégies consiste à déparasiter périodiquement avec l'albendazole (ABZ) et le mébendazole (MBZ). Cependant, l'utilisation répétitive de BZ peut causer une sélection au niveau du gène de la β-tubuline aux codons 167, 198 et 200 et entraîner une résistance. Pour maintenir une stratégie de contrôle efficace, il est indispensable de détecter rapidement la résistance, si présente. Méthode : Dans ce contexte, nous avons développé pour les géohelminthes des tests moléculaires précis pour détecter les changements génétiques de la β-tubuline aux codons 167, 198 et 200, associés à la résistance. Nous avons aussi optimisé un test in vitro, le EHA, chez les ankylostomes infestant la race canine. Les deux tests (moléculaire et in vitro), ont été expérimentés sur des échantillons collectés dans des pays endémiques aux géohelminthes. De plus, nous avons mené, une étude longitudinale de 14 mois en Haiti afin d'investiguer la réponse des géohelminthes à deux traitements d'ABZ. Résultat: Dans cette étude, des marqueurs génétiques des codons 200 chez les ankylostomes, puis 167 et 198 chez les ankylostomes, A. lumbricoides et T. trichiura ont été validés par des plasmides de contrôles. Nous avons aussi identifié à faible fréquence avant et après traitement, le SNP 200 chez des ankylostomes collectés au Kenya. Cependant, l'efficacité de l'ABZ était élevée. Chez A. lumbricoides, le SNP 167 a été identifié à forte fréquence avant et après traitement en Haiti, au Kenya et au Panama alors que l'efficacité de l'ABZ était élevée. Chez T. trichiura, le SNP 200 a été détecté et il y a eu une augmentation significative de l'homozygote de type résistant chez les parasites collectés au Kenya et en Haiti. L'efficacité de l'ABZ estimée par le nombre d'œufs compté, était faible au Kenya et modérée en Haiti. A partir de ces résultats, en Haiti, nous avons classés les individus infestés par T. trichiura en trois groupes de réponse à l'ABZ : "bonne", "intermédiaire" et "faible" réponse au traitement. Après un traitement, les fréquences des SNPs 198 et 200 ont augmenté significativement dans les groupes de réponse intermédiaire et faible. Conclusion : Cette étude a montré pour la première fois, la preuve de l'existence d'une association entre les changements génétiques au niveau de la β-tubuline et la faible efficacité de l'ABZ chez T. trichiura.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

31

Owojori, Olugbenga J. (Olugbenga John). „Influence of clay content and salinity on the bioavailability and toxicity of metals (copper and zinc) to soil organisms“. Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1484.

Der volle Inhalt der Quelle

Annotation:

Thesis (PhD (Botany and Zoology))—University of Stellenbosch, 2009.
ENGLISH ABSTRACT: Metal pollution is a problem of increasing global concern. It could arise from industrial activities, as well as pesticide use in agriculture, among other sources. For adequate protection of the soil ecosystem from metal toxicity, the bioavailability of metals must be properly evaluated. A plethora of soil factors affect the bioavailability of metals to soil organisms. These include pH, clay and organic matter contents, salinity among others. While much is known about the influence of some of these parameters, little is known on how clay content and salinity modify the bioavailability of metals to soil organisms. This study investigated the influence of clay content and salinity on partitioning, uptake and toxicity of two essential metals (Cu and Zn) to the earthworm Eisenia fetida in separate laboratory trials. Partitioning of the metals was evaluated with 0.01 M CaCl2, DTPA (di-ethylene-triamine-penta acetic acid), and nitric acid extractions. The metal content of worms was determined by acid digestion, while growth, cocoon production, and mortality were used as endpoints showing toxicity to metals and/or salinity. To test the validity of some of the laboratory results, a field study was undertaken, using the earthworm Aporrectodea caliginosa. Further, the study assessed the effect of salinity, using a battery of laboratory tests (acute, chronic and avoidance tests) with natural and/or artificial soils on four species of organisms (a collembolan Folsomia candida, a potworm Enchytraeus doerjesi and two earthworm species E. fetida and A. caliginosa), representing different feeding patterns and ecological roles in soil. Results showed that with increased clay content, there was increased availability of Cu in the substrate, and increased toxicity to E. fetida as shown by data for mortality and growth. The situation with Zn was less significant at sub-lethal concentrations but much so at lethal concentrations. DTPA and CaCl2 extracted metals revealed changes in partitioning of Cu and Zn with changes in clay content, but this trend was not always consistent. Both DTPA and CaCl2 revealed increased availability of Zn in substrates with increased salinity. Salinity had an additive to synergistic effect with Zn in toxicity to E. fetida. When combined with Cu, salinity also increased the availability of Cu as shown by CaCl2 extracted fraction, and had additive effect on toxicity of Cu to the earthworm. The field study did not succeed in in iv confirming the results of the laboratory study due to confounding role of flooding after heavy rainfall and subsequent leaching of salts and Cu. The results of the experiment on acute and chronic toxicity tests for NaCl on E. fetida showed LC50 of 5436 mg/kg NaCl and EC50 for growth and cocoon production of 4985 and 2020 mg/kg NaCl. These values showed that earthworms might be negatively affected in many soils containing fairly moderate concentrations of salts. Similarly, A. caliginosa could not survive in natural soil containing relatively low salt concentrations (EC = 1.62 dS/m) while reproduction was severely affected at lower EC value of 0.52 dS/m. F. candida and E. doerjesi could survive in the highest salinity soil (EC = 1.62 dS/m) used in this study but their reproduction was severely affected from 1.03 dS/m. Overall, it appears that of all the taxa used, earthworm species were the most sensitive to saline stress and could proof useful in determining ‘safe levels’ of salt in contaminated soils. The results of the avoidance test showed that A. caliginosa avoided both natural and artificial saline soil containing concentrations lower than those avoided by E. fetida. The conclusion is that the influence of clay content and salinity on the bioavailability of Cu and Zn depends largely on the metal in question, but generally speaking, bioavailability and toxicity of the metals were reduced with increased clay content while the opposite was true for salinity. If the species used in this study can be seen as fairly representative of a wide range of soil organisms, the conclusion is that salinisation of soil will be detrimental to most soil organisms at relatively low saline concentrations. Given the role of beneficial soil organisms in several soil processes which in turn contribute to soil fertility and sustainable use of land, it is recommended that any farming practices that may lead to an increase in salt content of agricultural soils should be discouraged.
AFRIKAANSE OPSOMMING: Metaalbesoedeling is ‘n probleem wat toenemende globale kommer veroorsaak. Dit kan ontstaan as gevolg van industriële aktiwiteite sowel as van plaagmiddelgebruik in die landbou en ander bronne.Ten einde die grondekostelsel genoegsaam te beskerm, moet die biobeskikbaarheid van metale ge-evalueer word. ‘n Verskeidenheid van grondfaktore be-invloed die biobeskikbaarheid van metale vir grondorganismes Hulle sluit onder andere in pH, klei, organiese inhoud en soutgehalte. Hoewel heelwat bekend is oor die rol van sommige van hierdie parameters, is min bekend oor hoe klei en soutgehalte die biobeskikbaarheid van metale vir grondorganismes kan modifieer. Hierdie studie het die invloed van kleiinhoud and soutgehalte op die verdeling/partisie, opname en toksisiteit van twee essensiële metale (Cu en Zn) vir die erdwurm Eisenia fetida in afsonderlike laboratoriumproewe ondersoek. Kompartementele verdeling van die metale is geevalueer deur middel van ekstraksie-metodes met 0.01 M CaCl2, DTPA (di-etileentriamien- penta asysnsuur), en salpertersuur ekstraksies. Die metaalinhoud van wurms is bepaal deur suurverterings en spektrofotometriese analises te doen terwyl groei, kokonproduksie en mortaliteit van organismes gebruik is as gevoeligheidseindpunte om toksisiteit van metale en soutgehalte aan te toon. Om die geldigheid van somige van die laboratoriumresultate te toets, is ‘n veldstudie ook onderneem met die erdwurm Aporrectodea caliginosa. Die effek van soutgehalte is verder ondersoek deur ‘n battery van laboratoriumtoetse met vier spesies (‘n kollembool Folsomia candida,’n potwurm Enchytraeus doerjesi en twee erdwurmspesies E. fetida en A. caliginosa), wat verskillende voedingspatrone verteenwoordig. Die resultate het getoon dat met toenmende klei-inhoud was daar ‘n toename in die beskikbaarheid van Cu vir opname vanuit die substraat, asook ‘n toename in toksisiteit vir E. fetida soos deur die gegewens vir mortaliteit en groei uitgewys. Die situasie met Zn was minder betekenisvol by subletale konsentrasies en selfs baie minder so by letale konsentrasies. DTPA en CaCl2 ge-ekstraheerde metale het veranderinge in die partisie/verdeling van Cu en Zn uitgewys met verandering in klei-inhoud, maar die tendens was nie altyd konstant nie. Beide DTPA en CaCl2 ekstraksie het toenemende beskikbaarheid van Zn in substrate uitgewys met toenemende soutinhoud. Soutinhoud het ‘n additiewe/toegevoegde tot sinergistiese vi toksisiteitseffek saam met Zn vir E. fetida. In kombinasie met Cu het soutgehalte ook die geskatte biobeskikbaarheid van Cu verhoog soos uitgewys deur die CaCl2, geekstraheerde fraksie, en het ‘n additiewe effek gehad op die toksisitiet van Cu vir die erdwurm. Die veldstudie kon nie die resultate van die laboratoriumstudie bevestig nie weens die belemmerende rol van vloede na swaar reënneerslae en daaropvolgende uitloging van soute en Cu. Die resultate van die eksperimentele ondersoek na die akute en chroniese effekte van NaCl op E. fetida het ‘n LC50 van 5436 mg/kg NaCl en EC50 vir groei en kokonproduksie van 4985 en 2020 mg/kg NaCl opgelewer. Hierdie waardes het aangetoon dat erdwurms moontlik negatief beinvloed kan word in baie gronde wat ‘n redelike gemiddelde konsentrasie van soute bevat. Soortgelyk kon A. caliginosa nie oorleef in natuurllike grond wat relatief lae soutkonsentrasies bevat het (EC=1.62 dS/m) nie terwyl voortplanting sterk ge-affekteer is by ‘n lae EC waarde van 0.52 dS/m. F. candida en E. doerjesi kon oorleef in die grond met die hoogste soutgehalte (EC= 1.62 dS/m) maar hulle voortplanting is ernstig geknou vanaf 1.03 dS/m. In geheel blyk dit dat van allle taksa wat gebruik is, erdwurms die sensitiefste was vir die stres wat deur soutgehalte veroorsaak is. Die kennis kan nuttig wees in die bepaling van “veilige vlakke” van sout in gekontamineerde gronde. Die resultate van die vermydingstoetse het getoon dat A. caliginosa beide natuurlike en kunsmatig versoute gronde vermy het by konsentrasies wat heelwat laer was as dié wat deur E. fetida vermy is Die gevolgtrekking is dat die invloed van klei en soutgehalte op die biobeskikbaarheid van Cu en Zn grootliks afhanklik is van die metale wat betrokke is en dat biobeskikbaarheid en toksisiteit normaalweg verminder het met verhoogde klei-inhoud, met die teenoorgestelde wat waar was in die geval van soutgehalte. Indien die spesies wat in die studie gebruik is beskou kan word as redelik verteenwoordigend van ‘n wye reeks van grondorganismes, is die gevolgtrekking dat versouting van gronde nadelig sal wees vir meeste grondorganismes, selfs by relatief lae soutkonsentrasies. In die lig van die rol wat nuttige grondorganismes speel in verskeie grondprosesse wat bydraend is tot grondvrugbaarheid en volhoubare gebruik van gronde, word dit aanbeveel dat enige boerderypraktyk wat mag lei tot verhoging van die soutinhoud van landbougronde ontmoedig moet word.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

32

Deniston-sheets, Holly M. „Short Term Shifts in Soil Nematode Food Feb Structure and Nutrient Cycling Following Sustainable Soil Management in a California Vineyard“. DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2021.

Der volle Inhalt der Quelle

Annotation:

Evaluating soil health using bioindicator organisms has been suggested as a method of analyzing the long-term sustainability of agricultural management practices. The main objective of this study was to determine the effects of vineyard management strategies on soil food web structure and function, using nematodes as bioindicators by calculating established nematode ecological indices. Three field trials were conducted in a commercial Pinot Noir vineyard in San Luis Obispo, California; the effects of (i) fertilizer type (organic and inorganic), (ii) weed management (herbicide and tillage), and (iii) cover crops (high or low water requirements) on nematode community structure, soil nutrient content, and crop quality and yield were analyzed. Overall, although nematode ecological indices indicated that all plots had disturbed soil food webs, the indices proved to be less useful for measuring subtle differences in soil management over the short-term than anticipated. They showed few differences treatments. In general, the most pronounced differences were seen by sample location (under the vine or in the tractor row) and sample date, rather than treatment. None of the evaluated strategies affected crop quality, although fertilizer had a slight effect on yield. However, several indices were correlated with soil chemical parameters, including pH, nitrogen, carbon, and, to a lesser extent, EC. These results indicate that while nematode indices can be useful for comparing the state of the soil food web under long-term soil conditions, they may not be a robust measure of how agricultural management practices change soil health over a single growing season.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

33

Kuperman, Roman Gregory. „Relationships between acidic deposition, soil invertebrate communities, microbial activity, and litter decomposition in oak-hickory forests /“. The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487843688958806.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

34

Flynn, Laura J. „Soil seed stocks of tropical hardwood hammocks in southern Florida : implications for restoration“. FIU Digital Commons, 1998. http://digitalcommons.fiu.edu/etd/3342.

Der volle Inhalt der Quelle

Annotation:

Tropical hardwood hammocks are evergreen, broad-leaved forests occurring in southern Florida and throughout the Caribbean basin. 1 examined the soil seed stocks of hardwood hammocks in six south Florida sites. Three sites represent urban, fragmented forests situated along coastal uplands of mainland Florida and three sites are located in relatively undisturbed forests in northern Key Largo. The purpose of my research was to determine the species composition and abundance of seeds in the soil, and to determine the abundance and distribution of exotic seeds in this community. Seed bank characteristics were determined by collecting soil samples every 5 m along two 50 m transects at each site. A total of 1970 seedlings, representing 64 species emerged from all combined soil samples. Approximately, 4% of the seedlings were exotic. Sites differed in total seed density and in species composition of the seed bank. Detrended Correspondence Analysis showed distinct species composition patterns from mainland and Keys seed banks. Based on seed bank patterns and phenological data, I classified seed bank strategies for hardwood hammock species. To understand the potential role of a soil seed bank in restoration of hardwood hammocks, I examined how buried seeds corresponded to the vegetation. Importance values, based on relative basal area, relative frequency, and relative cover were calculated for trees and shrubs. I compared these importance values with species percentages of seeds recovered in the soil. Similarity of buried seeds to the vegetation was low, using Jaccard's coefficient. Detrended Correspondence Analysis showed distinct seed bank and vegetation associations. A comparison of successional stages represented in the vegetation and the seed bank shows that there are consistent ratios between early, mid and late successional species among the sites. Based on these results, I recommend that the seed bank be considered when restoring tropical hardwood forests.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

35

Arthur, Mickey Francis. „Soils containing 2,3,7,8-tetrachlorodibenzo-p-dioxin : aspects of their microbial activity and the potential for their microbially-mediated decontamination /“. The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487330761218489.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

36

Aloudah, Eman A. „Isolation and identification of oil degrading bacteria from oil contaminated soil“. DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 2015. http://digitalcommons.auctr.edu/dissertations/2965.

Der volle Inhalt der Quelle

Annotation:

Oil spills are a universal threat impacting local, national and world communities alike. Bioremediation that is natural, efficient, economical and safe is the best solution for protecting the environment from oil related damages. In this study, motor oil degrading bacteria were isolated from oil-contaminated soil samples from a suburban Atlanta, Georgia community. Mineral salt broth containing 1 Ow-40 motor oil as the sole carbon source was used to isolate motor oil degrading bacteria. Motor oil tolerant and metabolizing bacteria were identified using morphological and biochemical tests. Two bacterial isolates were then tested for their tolerance varying concentrations of diesel and kerosene oils for comparison with motor oil consumption. Observed results suggest that the isolated bacteria from oil contaminated soil possess abilities to metabolize motor oil, kerosene and diesel. Knowledge of the tolerance ranges of the isolated bacteria can indicate their potential to be of use in the remediation of terrestrial petroleum oil spills in a manner that is natural, economical, quick and efficient.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

37

Goodfriend, Wendy Lynn 1965. „Exploring a community of saline soil microorganisms: Who, where, and when“. Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282313.

Der volle Inhalt der Quelle

Annotation:

The abundance, distribution, and diversity of the soil microbial community from a seawater-irrigated, halophyte agroecosystem was examined. The abundance and trophic composition of decomposers responded to the biochemical composition of residue from three salt-tolerant plants, Salicornia bigelovii, Suaeda sp., and Batis maritima. Decomposers were also influenced by the decomposition environment as it interacted with residue resource quality. The microbial community responded to the availability of residues and the planting density of the halophyte Salicornia bigelovii (Chenopodiaceae) in a season-long study at a research farm in Sonora, Mexico. Soil microbial biomass, activity and efficiency, as well as nematode abundance and trophic composition, generally increased in association with soil-incorporated halophyte residues. However, soil moisture and salinity, which decreased with depth, may also have been influential. Microbial biomass and activity responded to plant density only after plants entered senescence. This result suggested that live-root exudations were not available to the microbial community possibly due to competition with plant roots for available nutrient resources. An increase in the abundance of plant-feeding, but not bacterial- or fungal-feeding, nematodes was associated with the presence of S. bigelovii. The functional diversity of a microbial community from an agronomic halophyte system was compared to natural and constructed halophyte salt marsh communities. Functional diversity of the microbial community at the agronomic sites was intermediate compared to the other sites; e.g., higher than the constructed marsh but lower than the natural salt marshes. Relationships among the study communities determined by microbial functional diversity reflected both habitat and geographical influences.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

38

Johansson, Linda. „Temperature sensitivity of decomposition in a boreal mixed mire in northern Sweden“. Thesis, Linköpings universitet, Tema vatten i natur och samhälle, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-60285.

Der volle Inhalt der Quelle

Annotation:

Carbon accumulation in soils constitutes a significant sink for carbon. How the climate change with increasing temperatures will affect the soil carbon storage represents uncertainty of the predictions in the climate change ecosystem feedback mechanisms. In this study the temperature impact on the decomposition of the large carbon pools in peatlands was investigated. Peat cores from different microtopographic units in a boreal oligotrophic minerogenic mire in northern Sweden were collected from in three depths (5-10, 10-15 and 15-20 centimeters below the surface). The samples were incubated at four temperatures: 4, 9, 14 and 19°C and the heterotrophic respiration (CO2- production) was measured hourly or 37 days. Unexpectedly, basal respiration did not show any correlation with temperature. However, the exponential increase in respiration (µ) was correlated with temperature: i.e. giving Q10 values between 2 (SE +/- 0.36) and 5 (SE +/-1.05). Soil depth or vegetation covers did not affect temperature response (Q10) of µ. The substrate induced respiration (SIR) did not occour but for a few of the samples. The conclusion from this study is that degradation of peat seams not be affected by a temperature increase. The addition of glucose, nitrogen and phosphorus increased with increasing temperature with a Q10 value as expected.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

39

Dittmer, Kyle Michael. „Mitigating Gaseous Nitrogen and Carbon Losses from Northeastern Agricultural Soils via Alternative Soil Management Practices“. ScholarWorks @ UVM, 2019. https://scholarworks.uvm.edu/graddis/1161.

Der volle Inhalt der Quelle

Annotation:

Traditional agricultural practices often result in gaseous losses of nitrous oxide (N2O), ammonia (NH3), and carbon dioxide (CO2), representing a net loss of nutrients from agricultural soils, which negatively impacts crop yield and requires farmers to increase nutrient inputs. By adopting best management practices (BMPs; i.e., no-tillage, cover crops, sub-surface manure application, and proper manure application timing), there is great potential to reduce these losses. Because N2O and CO2 are also greenhouse gases (GHGs), climate change mitigation via BMP adoption and emissions reductions would be an important co-benefit. However, adopting a no-tillage and cover cropping system has had setbacks within the Northeast, primarily due to concerns regarding manure nitrogen (N) losses in no-tillage systems as well as uncertainty surrounding the benefits of cover crops. This thesis used two field-trials located in Alburgh, Vermont to assess differences in (i) GHG emissions from agricultural soils, (ii) nitrate and ammonium retention, (iii) corn yield and protein content, and (iv) N uptake and retention via cover crop scavenging under a combination of different BMPs. Chapter 1 evaluates the effects of different reduced-tillage practices and manure application methods (i.e., vertical-tillage, no-tillage, manure injection, and broadcast manure application) on reducing N2O and CO2 emissions, retaining inorganic N, and improving crop yields. Greenhouse gas measurements were collected every other week for the growing season of 2015-2017 via static chamber method using a photoacoustic gas analyzer. Results from this study showed that tillage regimes and manure application method did not interact to affect any of the three research objectives, although differences between individual BMPs were observed. Notably, vertical tillage enhanced CO2 emissions relative to no-tillage, demonstrating the role of soil disturbance and aeration on aerobic microbial C transformations. Manure injection was found to significantly enhance both N2O and CO2 emission relative to broadcast application, likely due to the formation of anerobic micro-zones created from liquid manure injection. However, plots that received manure injection retained greater concentrations of soil nitrate, a vital nutrient for quality crop production, thereby highlighting a major tradeoff between gaseous N losses and N retention with manure injection. Chapter 2 evaluates the effects of tillage practices and timing of manure application to increase N retention with the use of cover crops in order to mitigate GHG emissions, enhance soil nitrate and ammonium retention, and improve cropping system N uptake. Treatments at this field trial consisted of a combination of the presence or absence of cover crops, no-tillage or conventional-tillage, and spring or fall manure application. Greenhouse gas emissions were measured every other week via static chamber method using a gas chromatograph for the growing season of 2018. Results from this study showed that the presence of cover crops enhanced both N2O and CO2 emissions relative to fallow land, irrespective of tillage regime and manure application season, likely as a result of greater N and carbon substrates entering the soil upon cover crop decomposition. Due to enhanced N2O emissions with cover crops, cover crops did not retain significantly greater inorganic N in the system upon termination.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

40

Rose, Caroline Gayle. „Temporal Changes in the Microbial Community of a PAH-Contaminated Soil during Bench-Top Bioremediation“. Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28540.

Der volle Inhalt der Quelle

Annotation:

Contamination of soils with PAHs, substances that can pose serious environmental and human health risks, is a serious problem. Removal of risk requires effective and sustainable methods to decrease or eliminate toxicological hazard. Bioremediation is a sustainable option that can be accomplished by a variety of means. However, due to the limitations of classical culturing methods, there is a paucity of information regarding the composition of soil microbial communities, and moreover, the identity of organisms involved in contaminant catabolism. Newer, molecular techniques directly examine metagenomic DNA or RNA, and provide opportunities to investigate the genetic constitution of soil samples without the need for culturing. 16S rRNA has proven to be a valuable tool in the identification of soil microbes due to its highly conserved nature throughout the bacterial kingdom, in addition to inclusion of variable regions that are unique to a particular organism, or closely related group of organisms. This study used analysis of 16S rRNA gene sequences to examine the temporal changes in the soil microbial community in a PAH-contaminated soil during bioremediation. These results were compared with previously observed temporal changes in the chemical composition of the same soil during bioremediation. Interplay between the temporal changes of soil microbial community and the temporal changes of the PAH concentration was observed. The PAH concentration decreased an average of 77% across all treatments and reactors. Soil micro-organisms whose growth during treatment corresponded with a decline in PAH concentration included several known PAH-degraders such as Achromobacter, Acidovorax, Pseudomonas, Rhodanobacter and Stenotrophomonas. The metagenomic approach employed in this study can be used to evaluate innovative bioremediation methods, and moreover, identify members of the microbial community that are critical for the catabolism of PAHs.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

41

Klemm, Sara. „Microbial responses to the biostimulation of Subartic hydrocarbon-contaminated soil under seasonal freeze-thaw conditions“. Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86944.

Der volle Inhalt der Quelle

Annotation:

Nutrient-deficient, acidic soil from Resolution Island, Nunavut was contaminated with petroleum hydrocarbons during operations from 1954-1973 at a former radar station. Two mesocosm tanks containing ~200 kg hydrocarbon-contaminated Resolution Island soil each were exposed to a seasonal freezing profile designed to simulate in situ ground conditions after the summer landfarming season. Soil from one tank was treated with 100.0 mg N kg-1 soil and 2.0 g CaCO3 kg-1 soil, while the second mesocosm remained untreated. Aliphatic nC10-nC16 hydrocarbon biodegradation was enhanced by soil treatments after an initial acclimation period, which corresponded to Actinomycetales and Rhodanobacter population growth from 2.4ºC to -2.1ºC. These Actinomycetales and Rhodanobacter populations probably represented hydrocarbonoclastic K-strategists and hydrocarbon metabolite-utilizing r-strategists, respectively. Additionally, a novel indigenous archaeal community was related to Thaumachaeota ammonia oxidizers but not associated with hydrocarbon biodegradation. Two diazotrophic Burkholderia isolates from the soil also degraded 14C-naphthalene and/or 14C-phenanthrene at -5°C.
Une terre acide pauvre en éléments nutritifs provenents de Resolution Island, Nunavut, a été contaminé par des hydrocarbures pétroliers durant les opérations d'une ancienne base de radar entre 1954 - 1973. Deux réservoirs mésocosmes contenant ~200 kg de terre de Resolution Island contaminée par des hydrocarbures ont été sujet à un profil saisonnier de gel et dégel conçu pour simuler les conditions du sol in situ après la saison estivale d'exploitation. La terre dans un réservoir a été traite avec 100.0 mg N kg-1 de terre et 2.0 g CaCO3 kg-1 de terre, tandis que le deuxième réservoir n'a reçu aucun traitement. La biodégradation d'hydrocarbures aliphatiques (nC10 à nC16) a été stimulée par l'ajout d'éléments nutritifs après une période initiale d'acclimatisation, qui correspondait à une croissance des populations Actinomycetales et Rhodanobacter de 2.4ºC à -2.1ºC. Ces populations Actinomycetales et Rhodanobacter ont probablement représenté des K-stratégistes hydrocarbonoclastes et des r-stratégistes utilisant des métabolites d'hydrocarbures, respectivement. De plus, la communauté originale indigène d'archaea était apparentée aux oxydeurs d'ammoniac Thaumachaeota, mais n'était pas associée avec la biodégradation d'hydrocarbures. Deux isolats Burkholderia diazotrophiques de la terre ont aussi dégradé du 14C-naphtalène et/ou du 14C-phénanthrène à -5°C.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

42

Henderson, Rachel A. „Partitioning Soil CO2 Efflux through Vertical Profiles of Manipulated Forests in MOFEP“. University of Toledo / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1177701393.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

43

Penuela, Useche Viviana. „Influences of yard management intensity on urban soil biogeochemistry“. Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5386.

Der volle Inhalt der Quelle

Annotation:

Soils are critical to ecosystem function as they provide essential nutrients for primary producers, habitat and organic energy for decomposers, and storage of organic matter. Irrigation with reclaimed water is an increasingly popular water conservation strategy; yet its high salinity and nutrient content potentially affect soil properties. In this study, set in a residential neighborhood of Tampa (U.S.). I tested whether there are distinct lawn system management strategies characterized by systematic differences in reclaimed water usage and irrigation and fertilization practices. I then investigated whether soil biogeochemistry responds to lawn system management strategy. My results indicated that amendment strategy, which includes water source type, frequency of fertilization, and frequency of irrigation varies among residents of comparable neighborhoods. In this case, these three categories of management behaviors tend to co-occur. Analysis of irrigation water samples collected in this study showed significant differences between potable and reclaimed water. Mainly, reclaimed water had higher conductivity and phosphate content than potable water. When looking at the soil biogeochemical characteristics of the study area I found that there were significant differences in soil nutrients and microbial biomass across amendment strategy. Soils with a high amendment strategy (frequently irrigation with nutrient-rich reclaimed water, plus frequent fertilizer addition) showed higher conductivity and a higher microbial biomass than soils on lawns with a low amendment strategy (infrequent irrigation with dilute potable water, plus infrequent fertilizer addition). A positive correlation between soil conductivity and microbial biomass was observed. These findings suggest that high amendment strategy increases the input flux of some nutrients to the soils and acts as a nutrient resource for soil microorganisms. The differences between soil and microbial biomass amendment strategy support the idea that decisions made by individuals about which management intensity strategy to use do affect the spatial variability of the ecosystem. These results contribute to the hypothesis of urban ecological urbanization by looking at the vertical social interactions between municipalities and individual homeowners. These interactions might explain the observed spatial variability of ecological characteristics. The results of this research affect the way information about the advantages of using reclaim water is advertised, in particular to homeowners.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

44

Kurek, Danielle K. „Effects of prescribed burning on soil physical, biological, and chemical properties of the Oak Openings region of Northwest Ohio“. Toledo, Ohio : University of Toledo, 2010. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1271430752.

Der volle Inhalt der Quelle

Annotation:

Thesis (M.S.)--University of Toledo, 2010.
Typescript. "Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Masters of Science Degree in Biology." "A thesis entitled"--at head of title. Title from title page of PDF document. Bibliography: p. 58-63.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

45

Freund, Stephanie M. „Biological Soil Crust Cover and Richness in Two Great Basin Vegetation Zones“. Thesis, University of Nevada, Reno, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10001568.

Der volle Inhalt der Quelle

Annotation:

Biological soil crusts are communities of bacteria, microfungi, algae, lichens, and/or bryophytes that colonize the surfaces of soils where other vegetation is sparse. Soil crust communities are best known from the world’s arid and semiarid regions, including North America’s hot and cool deserts, where they aid in soil stabilization and aggregation, reduce erosion, and contribute to nutrient inputs in the soil. Although a significant body of work has emerged on soil crust function in arid and semiarid environments, there is still much to be learned about their geographical distributions within and across different vegetation communities. Sagebrush shrublands and pinyon-juniper woodlands are common communities in the central Great Basin, but this region is under-studied with respect to biological crust composition and distribution. I collected data on soil pH and the cover of plant functional groups and biological soil crusts in sagebrush and pinyon-juniper zones in the Wassuk Range of western Nevada. Regression models revealed that in the shrublands, soil crusts associate negatively to rock cover and positively to moderately dense shrub canopy. In the woodlands, ground-cover of rocks and woody litter have a negative association with soil crusts. Sagebrush and pinyon-juniper communities are facing many stressors and undergoing changes in structure. My results offer a possible starting point for assessing how the biological crusts in these habitats might respond to these changes based on their current distributional controls. Future research should further explore the response of biological crusts to trajectories of change in the central Great Basin ecoregion.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

46

Wang, Jiann-Ming. „Intrinsic and enhanced biodegradation of polyaromatic hydrocarbons in aqueous and soil systems“. Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284046.

Der volle Inhalt der Quelle

Annotation:

Bioremediation is currently one of the most popular methods for remediating soil and groundwater contaminated by organic compounds. However, it has been found that the availability of the target contaminant to the microbial populations capable of degrading the compound may serve as a limiting factor in many systems. Thus, there is interest in the use of solubilization agents for enhancing bioavailability of organic contaminants. The impact of hydroxypropyl-β-cyclodextrin (HPCD) on the biodegradation of polycyclic aromatic hydrocarbons (PAHs) was investigated in a batch study. Results showed that HPCD can significantly increase the apparent solubility of phenanthrene, which had a major impact on the biodegradation rate of phenanthrene. For example, in the presence of 10⁵ mg L⁻¹ HPCD, the substrate utilization rate increased 5.5 times and only 0.3% of the phenanthrene remained at the end of a 48-hour incubation. It strongly suggests that HPCD can significantly increase the bioavailability, and thereby enhance the biodegradation, of phenanthrene. Biodegradation is often of great importance for the transport, fate, and remediation of organic contaminants in the subsurface. When modeling biodegradation processes, it is usually assumed that the microbial population responsible for biodegradation is composed of a single species. However, this is unlikely to be true for many, if not most, field situations. The effect of multiple species of degraders on phenanthrene biodegradation and transport in a saturated soil (with a high phenanthrene sorption capacity) was evaluated with a series of miscible-displacement experiments. Breakthrough curves obtained for the non-sterile column experiment exhibited oscillations in microbial populations as well as in oxygen and phenanthrene concentrations during the 6 months of continuous injection of a constant-concentration phenanthrene solution. This behavior is due to the response of the heterogeneous bacterial population (24 species) to substrates and oxygen availability, wherein population dynamics is hypothesized to be mediated by competition and other multi-species interactions. The dynamics of heterogeneous microbial populations, especially under growth conditions, should be considered when evaluating contaminant biodegradation and transport in natural subsurface systems.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

47

Keogh, Teri M. „Changes in competition intensity, herbivory and stress along a soil depth gradient in an old field“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0021/MQ58467.pdf.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

48

Dyen, Michael. „Culture-dependent and independent microbial analyses of petroleum hydrocarbon contaminated Arctic soil in a mesocosm system“. Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19249.

Der volle Inhalt der Quelle

Annotation:

Microbial-based strategies were investigated for eventual bioremediation of petroleum hydrocarbon-contaminated, acidic soils from Resolution Island (RI), Nunavut. A biotreatability assessment phase one study determined that supplementation of soil with commercial fertilizer and lime enhanced hydrocarbon mineralization. Phase two applied these conditions to large scale mesocosm trials, containing ~150 kg soil, incubated in a temperature cycle that represented the ambient summer conditions on RI (10 d of 1°C - 10°C for 60 d). Culture-dependent and –independent analyses of RI soil microbial communities showed the mesocosm treatment enhanced hexadecane mineralization, increased the enumerations of total microbes and viable, cold-adapted hydrocarbon-degrading microorganisms. DGGE analyses indicated emergence of a hydrocarbon-degrading community and 16S rRNA gene clone libraries showed bacterial population shift in mesocosm soils. Potentially novel isolated strains included those able to grow on hydrocarbons alone while under acidic or sub-zero conditions. This microbiological study addressed RI site conditions and presents a potential bioremediation.
Des techniques s'appuyant sur la microbiologie ont été utilisée pour évaluer la biorestauration future de sols acides, contaminés par des hydocarbures pétroliers, à Resolution Island (RI), Nunavut. Premièrement, une étude de biotraitabilité a permis de determiner que l'amendement du sol avec des fertilisants de type commercial et de la chaux améliore la dégradation des hydrocarbures. La phase deux a consisté en l'application de ces conditions à des essais de mesocosmes à grande échelle incubés à des températures représentant les conditions estivales de RI, i.e. cycle de 10 jrs (1°C-10°C) pendant 60 jrs. Des analyses de microbiologie classique et de biologie moléculaire des communatés microbiennes du sol de RI ont démontré que l'amendement des mésocosmes a permis une augmentaion de la minéralisation de l'hexadécane et un accroîssement du dénombrement de total de microorganismes ainsi que des microorganismes viables, adaptés au froid et dégradant les hydrocarbures. Des analyses par DGGE ont démontré l'apparition d'un communauté microbienne dégradant les hydrocarbures et une librairie de clones d'ARNr 16S a souligné un réarrangement des populations microbiennes présentes dans les sols de mesocosmes. Des nouvelles souches ont été isolées, incluant certaines pouvant croître sur une source unique d'hydrocarbures sous des conditions acides ou sous-zéro. Cet étude microbiologique a été faite sous des conditions respectant celles présente à RI et présente des procédés pouvant être utilisées pour la bioremediation du site.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

49

Thiet, Rachel Kay. „Soil microbial community pattern and process : impacts on vascular plant communities in three ecosystems of high conservation value /“. The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486459267521939.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

50

Al-Ouran, Ratib Musa. „Biology of transmission stages of Eimeria vermiformis (Ernst, Chobotar and Hammond, 1971) and Trichuris muris (Schrank, 1788)“. Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276188.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

Dissertationen zum Thema „Soil biology“

Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an