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1
Tenywa, Moses Makooma. "Soil erosion overland flow processes on spatially variable soils /". The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu148784853136528.
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2
Lotfabad, Soheila Karimi. "The transport processes in soil bioremediation". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0010/NQ59983.pdf.
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3
Peruzzo, Luca. "Geoelectrical approaches for characterizing soil geochemical processes and soil-root interactions". Thesis, Bordeaux 3, 2019. http://www.theses.fr/2019BOR30015.
Testo completoAbstract (sommario):
Cette thèse porte sur les possibilités que les méthodes d’imagerie géoélectrique offrent à la fois pour la caractérisation des processus géochimiques mais aussi pour l’étude d’interaction sol-racines. La ligne conductrice de ce travail, repose sur la position centrale de la qualité des sols et des interactions racines-sols dans de nombreux problèmes environnementaux. En effet, un nombre croissant d’études rapportent l’importance des interactions mutuelles entre les racines et le sol. Dans cette optique, cette thèse explore l’utilisation le développements approfondis de méthodes géoélectriques. Les processus physico-chimiques ainsi que les interaction sol-racines sont à l’origine de mouvement d’eau et de soluté, d’altération de la structure des sols ainsi que de perturbations biologiques. Les méthodes géoélectriques sont potentiellement sensibles à ces modifications hydrologique et biochimique. La méthode de Polarisation Provoquée Spectrale (PPS) a été combinée avec des analyses et des modélisations géochimiques permettant de connaitre sa sensibilité à la composition du fluide interstitiel (contenu dans l’espace poral), du pH et de la force ionique. Plus particulièrement, la signature PPS de la substitution Na+/Cu2+ a été analysée car il s’agit d’un critère pertinent traduisant la qualité d’un sol et reconnu mondialement. L’analyse PPS a été réalisée sur un sable (silicate) saturé et pour des concentrations typiques de Na+/Cu2+ que l’on trouve classiquement dans des sols exposés à des utilisations de pesticides au Cuivre (Cu). Les résultats ont montré que le pH et la force ionique ont été les variables prépondérantes contrôlant le signal PPS, alors que des effets négligeables sont liés à la substitution Cu/Na. L’utilisation simultanée d’analyses chimiques et géophysiques en laboratoire a permis de mieux caractériser les processus de complexation étudiés et d’appuyer considérablement l’interprétation des signaux PPS. Enfin, la tomographie de résistivité électrique et la méthode de Mise-A-La-Masse ont été combinées pour développer une nouvelle approche d'imagerie du chemin préférentiel emprunté par le courant électrique dans le système racines-sols. Etant donné que la conduction électrique dans le sol et les racines est principalement électrolytique, l'approche proposée repose sur le mouvement de l'eau et des solutés dans le système racines-sol. Le potentiel de la méthode pour son application in-situ a été testée à l’aide d’une série d’expériences sur une vigne. À la suite des résultats prometteurs, la méthode a été développée et appliquée lors d’une expérience en laboratoire portant sur la croissance racinaire dans un rhizotron de plantes de coton et de maïs. La méthode s'est révélée sensible aux différences physiologiques entre les espèces et éventuellement à la réponse de la plante aux facteurs de stress environnementaux. De nouvelles expériences contrôlant les variables physiologiques des tissus racinaires sont nécessaires pour une meilleure compréhension de leurs influences. Les développements technologiques récents soutiennent fortement la diffusion de l’imagerie et du suivi géoélectriques à l'échelle du terrain. Dans ce contexte prometteur, les résultats de cette thèse contribuent au développement d'approches géoélectriques pour l'étude du sol et de ses interactions mutuelles avec les racines des plantes à des échelles spatio-temporelles pertinentesIn this thesis I investigate some of the possibilities offered by the use of geoelectrical methods for characterizing soil geochemical processes and root-soil interactions. The motivation for this thesis arises from the pivotal role of soil quality and root-soil interactions in manifold environmental issues. In addition, there is growing evidence of the importance of mutual interactions between roots and soil, for this reason this thesis explores the use of geoelectrical methods for more comprehensive approaches. Both soil physicochemical processes and root-soil interactions involve, among others, the movement of water and solutes, altercations of the soil structure, and biological feedbacks. Geoelectrical methods are potentially sensitivity to these hydrogeological and biogeochemical modifications. The Spectral Induced Polarization (SIP) method was combined with geochemical analyses and modeling in order to investigate its sensitivity to pore fluid composition, pH, and ionic strength. In particular, the SIP signature of Na+/Cu2+ substitution was investigated because of their worldwide relevance for soil quality. The SIP investigation focused on saturated silica, and explored concentrations of Na+ and Cu2+ that are typical to agricultural soils exposed to the use of Cu pesticides. The results showed how pH and ionic strength were the main variables controlling the SIP signals, while negligible effects were related to the Cu/Na substitution. The concurrent use of chemical and geophysical laboratory experiments allowed a better characterization of the investigated complexation processes and significantly supported the interpretation of the SIP signals. The Electrical Resistivity Tomography and the Mise-A-La-Masse methods were combined to develop a novel approach for imaging the electric current pathways in the root-soil system. Since the current conduction in soil and roots is mostly electrolytic, the proposed approach relates to the movement of water and solutes within the root-soil system. The potential of the method for field investigations was explored with a set of experiments on a grapevine. In light of the promising results, the method was further developed and applied to rhizotron laboratory experiments on cotton and maize plants. The method proved to be sensitive to inter-species physiological differences and possibly to the plant response to environmental stressors. New experiments with physiological analyses of root tissues are needed to elucidate these aspects. Emerging technologies are strongly supporting to the diffusion of imaging and monitoring geoelectrical applications at the field-scale. In this promising context, the results of this thesis contribute to the development of geoelectrical approaches for studying soil and its mutual interactions with plant roots over relevant spatiotemporal scales
4
Becher, Marina. "Cryogenic soil processes in a changing climate". Doctoral thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-112509.
Testo completoAbstract (sommario):
A considerable part of the global pool of terrestrial carbon is stored in high latitude soils. In these soils, repeated cycles of freezing and thawing creates soil motion (cryoturbation) that in combination with other cryogenic disturbance processes may play a profound role in controlling the carbon balance of the arctic soil. Conditions for cryogenic soil processes are predicted to dramatically change in response to the ongoing climate warming, but little is known how these changes may affect the ability of arctic soils to accumulate carbon. In this thesis, I utilize a patterned ground system, referred to as non-sorted circles, as experimental units and quantify how cryogenic soil processes affect plant communities and carbon fluxes in arctic soils. I show that the cryoturbation has been an important mechanism for transporting carbon downwards in the studied soil over the last millennia. Interestingly, burial of organic material by cryoturbation appears to have mainly occurred during bioclimatic events occurring around A.D. 900-1250 and A.D. 1650-1950 as indicated by inferred 14C ages. Using a novel photogrammetric approach, I estimate that about 0.2-0.8 % of the carbon pool is annually subjected to a net downward transport induced by the physical motion of soil. Even though this flux seems small, it suggests that cryoturbation is an important transporter of carbon over centennial and millennial timescales and contributes to translocate organic matter to deeper soil layers where respiration proceeds at slow rates. Cryogenic processes not only affect the trajectories of the soil carbon, but also generate plant community changes in both species composition and abundance, as indicated by a conducted plant survey on non-sorted circles subjected to variable differential frost heave during the winter. Here, disturbance-tolerant plant species, such as Carex capillaris and Tofieldia pusilla, seem to be favoured by disturbance generated by the differential heave. Comparison with findings from a previous plant survey on the site conducted in the 1980s suggest that the warmer temperatures during the last decades have resulted in decreased differential heave in the studied non-sorted circles. I argue that this change in cryogenic activity has increased abundance of plants present in the 1980s. The fact that the activity and function of the non-sorted circles in Abisko are undergoing changes is further supported by their contemporary carbon dioxide (CO2) fluxes. Here, my measurements of CO2 fluxes suggest that all studied non-sorted circles act as net CO2 sources and thus that the carbon balance of the soils are in a transition state. My results highlight the complex but important relationship between cryogenic soil processes and the carbon balance of arctic soils.
5
Tanaka, Ueru. "MECHANISMS AND PROCESSES OF SOIL SURFACE CRUSTING". Kyoto University, 1997. http://hdl.handle.net/2433/202417.
Testo completoAbstract (sommario):
Kyoto University (京都大学)0048
新制・論文博士
博士(農学)
乙第9610号
論農博第2144号
新制||農||747(附属図書館)
学位論文||H9||N3068(農学部図書室)
16502
UT51-97-H447
(主査)教授 小﨑 隆, 教授 關谷 次郎, 教授 丸山 利輔
学位規則第4条第2項該当
6
Md, Som Amelia. "The impact of biochar on soil processes and its potential in soil remediation". Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648221.
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7
Heitman, Joshua L. "Measurement of coupled soil heat and water processes". [Ames, Iowa : Iowa State University], 2007.
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8
Moreland, Scott J. "Traction Processes of Wheels in Loose, Granular Soil". Research Showcase @ CMU, 2013. http://repository.cmu.edu/dissertations/278.
Testo completoAbstract (sommario):
This dissertation presents analyses of subsurface motions of soil beneath different traction devices and develops new explanations of traction processes of wheels operating in loose granular soil based on these observations. This dissertation shows how these findings are useful for the development of planetary rover mobility systems.
Shear Interface Imaging Analysis (SIIA), is a new technique, developed as part of this thesis research. SIIA is employed for visualizing the effects of wheel operation on the soil beneath a rim, in richer detail than before possible. SIIA relies on high-speed imaging of sub-surface soil and on computer vision software to produce soil displacement fields, of high fidelity. The resulting data provides new insight and can reveal misconceptions about how wheels generate traction.
Two comprehensive studies relying on SIIA are undertaken: the investigation of wheel grouser mechanics and the investigation of push-roll locomotion. Soil forward motion, at a wheel leading edge, is identified as a key behavior for the grousered wheels. As a result, an equation for grouser height/spacing relationship to achieve a higher performance grouser configuration is developed and validated. This expression relates grouser configuration to wheel parameters (wheel radius) and operational parameters (sinkage and slip).
The soil mechanics behind Push-roll locomotion for high net traction and soft ground applications are presented. SIIA reveals that high thrust generated by push-roll locomotion is due to ground failure of the soil. Confirmation of the type of soil failure and of the application of operation in soft ground (where most vehicles would be embedded), brings forward the mobility gains of this non-typical locomotion mode and as a possible use for future planetary missions.
Additionally, insight into fundamental traction processes such as thrust, sinkage and motion resistance, are discussed with experimental evidence from soil displacement fields. This research proves that accounting for soil motion is of the utmost importance for the understanding of traction in loose, granular soils.
As a result of the specific technique utilized for directly studying soil motion, this research enables improved analysis and new design relevant to planetary rover mobility.
9
Laughlin, R. J. "Processes responsible for denitrification in a grassland soil". Thesis, Queen's University Belfast, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403169.
Testo completo
10
Hensley, Patricia Jane. "Accelerated physical modelling of transport processes in soil". Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292742.
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11
Fuß, Roland. "Diffusion processes of soluble organic substances in soil and their effect on ecological processes". kostenfrei, 2009. http://mediatum2.ub.tum.de/node?id=683922.
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12
Scanlan, Craig Anthony. "Processes and effects of root-induced changes to soil hydraulic properties". University of Western Australia. School of Earth and Environment, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0188.
Testo completoAbstract (sommario):
[Truncated abstract] Root-induced changes to soil hydraulic properties (SHP) are an essential component in understanding the hydrology of an ecosystem, and the resilience of these to climate change. However, at present our capacity to predict how roots will modify SHP and the consequences of this is limited because our knowledge of the processes and effects are highly fragmented. Also, current models used to investigate the relationship between plants and root-induced changes to SHP are based on empirical relationships which have limited applicability to the various and often contrasting ecosystems that occur. This thesis focuses specifically on the quantifying the processes by which roots modify SHP and developing models that can predict changes to these and the water balance. Both increase and decreases in saturated hydraulic conductivity have been attributed to the presence of roots. In general, decreases occur when the root system is relatively young, and increases occur when the roots senesce and begin to decay, creating voids for water flow. The evidence available suggests that the change in pore geometry created by roots is the dominant process by which roots modify SHP because they are more permanent and of a greater magnitude than changes to fluid properties or soil structure. We first quantified the effects of wheat roots on SHP of a coarse sand with a laboratory experiment where we measured changes in both SHP and the root system at 3, 5, 7 and 9 weeks after sowing (weeks). ... The main message that can be drawn from this thesis is that root-induced changes to SHP are dynamic, and dependent upon the combination of soil texture, connectivity of root-modified pores and the ratio of root radius to pore radius. Consequently, root-induced changes to the water balance have the same dependencies. The work in this thesis provides a significant first step towards improving our capacity to predict how roots modify soil hydraulic properties. By defining the range for the parameters used to predict how the soil is modified by roots, we are able to make quantitative assessments of how a property such as hydraulic conductivity will change for a realistic circumstance. Also , for the first time we have measured changes in soil hydraulic properties and roots and have been able to establish why a rapid change from a root-induced decrease to increase in Ks occurred. The link between physiological stage of the root system, and the changes that are likely to occur has implications for understanding how roots modify SHP: it may provide an effective tool for predicting when the switch from a decrease to increase occurs. Further work is required to test the validity of the assumptions we have made in our models that predict changes to SHP. While we have endeavoured to define the parameter space for those parameters that we have introduced, there is still some uncertainty about the connectivity of root-modified pores. Also, the parameterisation of the soil domain with roots is based upon work that measures 'fine' roots only which may not provide a true representation of the effect trees and perennial shrubs have on SHP. It is inevitable that root-induced changes to SHP will affect the fate of solutes in the soil, and temporal dynamics of root-induced changes to these may be particularly important for the timing of nutrient and pesticide leaching.
13
Zheng, David W. "Theoretical studies linking soil food webs and ecosystem processes /". Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1998. http://epsilon.slu.se/avh/1998/91-576-5347-X.gif.
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14
Funakawa, Shinya. "SOIL-FORMING PROCESSES UNDER NATURAL FOREST IN NORTHERN KYOTO". Kyoto University, 1993. http://hdl.handle.net/2433/168912.
Testo completoAbstract (sommario):
本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものであるKyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第5467号
農博第767号
新制||農||656(附属図書館)
学位論文||H5||N2591(農学部図書室)
UT51-93-J522
京都大学大学院農学研究科農芸化学専攻
(主査)教授 久馬 一剛, 教授 古川 久雄, 教授 岩坪 五郎
学位規則第4条第1項該当
15
Hayashi, Yuki. "Effects of Soil Structural Development on Soil Hydraulic Properties and Hydrological Processes in Forested Hillslopes". Kyoto University, 2009. http://hdl.handle.net/2433/123989.
Testo completoAbstract (sommario):
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第14677号
農博第1759号
新制||農||969(附属図書館)
学位論文||H21||N4450(農学部図書室)
UT51-2009-D389
京都大学大学院農学研究科森林科学専攻
(主査)教授 水山 高久, 教授 谷 誠, 教授 太田 誠一
学位規則第4条第1項該当
16
Van, de Water James Gordon 1963. "Physical and chemical processes affecting forced ventilation of benzene and p-xylene in a desert soil". Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277044.
Testo completoAbstract (sommario):
The rate at which volatile organic compounds (VOCs) are removed from the vadose zone by forced ventilation may be reduced by slow micro-scale processes such as diffusion through intra-aggregate and pore water and slow reactions at sorption sites located at the soil-water interface. Column experiments using benzene and p-xylene were performed in order to simulate cleanup of VOC's in the vadose zone by forced ventilation. Analytical solutions of the one-dimensional advection-dispersion equation coupled to mass transfer equations were fitted to the data. Parameter estimates were used in order to determine time scales of diffusion through water, desorption from, and sorption to, soil organic matter. Lower limits for the time scales for these processes were calculated to be on the order of minutes. Results indicate that these micro-scale processes reduce the rate of removal on the laboratory scale but may have no effect on the field scale.
17
Zhang, Xudong. "Wavelet-domain hyperspectral soil texture classification". Master's thesis, Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-04012004-142420.
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18
Altaee, Ali. "Metal removal from soil by electrokinetic processes : the effects of inorganic soil components on the process". Thesis, University of Brighton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408749.
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19
Boyce, Emma Elizabeth Ruth. "Modelling of transport processes in heterogeneous soils". Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339466.
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20
Nambuthiri, Susmitha Surendran. "Soil water and crop growth processes in a farmer's field". Lexington, Ky. : [University of Kentucky Libraries], 2010. http://hdl.handle.net/10225/1140.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--University of Kentucky, 2010.Title from document title page (viewed on May 12, 2010). Document formatted into pages; contains: xii, 310 p. : ill. (some col.). Includes abstract and vita. Includes bibliographical references (p. 298-309).
21
Huang, Ying. "Treatment of PCB-contaminated soil by stabilization and solidification processes". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ39663.pdf.
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Gooding, Dominic Edward Maxwell. "Improved processes for the production of soil-cement building blocks". Thesis, University of Warwick, 1994. http://wrap.warwick.ac.uk/4453/.
Testo completoAbstract (sommario):
Stabilised-soil cement building blocks are an established building material in many areas of the Less Developed World. This thesis has been split into three parts. Part A presented an overview of the process of soil-stabilisation and outlined the roles which soil structure and curing play in stabilisation. It examined methods of testing soils, highlighting errors presented in the published literature and presenting corrected testing procedures and unified plans for their implementation. Part B examined the conventional quasi-static block compaction process (slowly applied pressure) and established that no cost-effective increase in the compacted block density can be achieved by altering such moulding configurations as mould-wall roughness, mould-wall taper, number of applied pressure cycles and double-sided pressure application. The tests were also used to assess the plausibility of several theoretical mechanisms underlying quasi -static compaction. Cement may be traded against compaction pressure for a given final cured strength. The relation of compaction pressure and cement content to well-cured strength was established for 50 mm diameter cylinders and used to assess the financial benefit of high-pressure compaction. It was shown that savings in the cost of cement associated with high-pressure compaction were outweighed by the additional cost of such machinery. However there were additional benefits found to high-density compaction, beyond the saving in stabiliser costs. It was established that a highdensity moulding machine in the range £1000 - £1500 would allow these benefits to become cost competitive. Part C examined both experimentally and theoretically an alternative dynamic (impact blow) compaction process, establishing that optimised dynamic compaction may produce strength equivalent to quasi-static high-density moulding while requiring only 25-50 % of the energy. Five theoretical models of the process were developed and the Combined Airlock/Friction/Compression Wave Model was shown to have the most explanatory power.
23
Graham, Terrece F. "Taking Root in Foreign Soil| Adaptation Processes of Imported Universities". Thesis, The George Washington University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10141538.
Testo completoAbstract (sommario):
The fall of the Berlin Wall in 1989 ushered in a period of change in higher-education systems across the former Eastern bloc. Reform-minded leaders in the region sought to introduce western models and policies promoted by foreign development aid agendas. Private higher-education institutions emerged. This qualitative multiple case study examines three universities based on the western, private, nonprofit model that were established during the post-Cold War transition period: the American University of Central Asia (Kyrgyz Republic), South East European University (Macedonia), and the American University in Bulgaria. These institutions, founded through a process of negotiation involving the national government, U.S. and European governments, and nongovernmental organizations, offered an alternative to state universities. This negotiation continued as these institutions adapted to their changing sociopolitical contexts. The study explores the interplay of global, national, and local influences at the level of these institutions. The research presented is based on data collected on field visits through interviews with faculty and administrators and focus groups with students, as well as document analysis. Findings from the study shed light on how new institutions strive to establish legitimacy. The financial support for these institutions evolved from an initial heavy dependence on support from foreign aid agencies to greater reliance on tuition and responsiveness to the higher education market. The ability to adapt to shifting circumstances while maintaining a consistent sense of identity, despite turnover of faculty and administrators, proved vital. These universities, to varying degrees, were able to strike a balance between the global and local that allowed them to establish themselves as highly regarded institutions in their respective countries. As interest in transnational education grows, this study offers insights into finding a balance between global and local that results in a sustainable higher education endeavor.
24
Abdalgader, Naser. "Ecotoxicology of nanoparticles : effects on plant growth and soil processes". Thesis, Bangor University, 2014. http://digitool.jmu.ac.uk:8881/R/?func=dbin-jump-full&object_id=158084.
Testo completoAbstract (sommario):
The uptake and impact of CdS and ZnO NPs in/on maize roots and shoots was investigated and compared with their soluble bulk materials (ZnClz and CdClz). The plants were grown in Eutric Cambisol soil for 21 days. The soil was treated with seven concentrations (0.1-1.25 mg kg-I) for each metal. The Tolerance Index (T!), the Agronomical Efficiency (AE), the Bio-Concentration Ratio (BCR), the Relative Increase Percentage (RI), uptake and uptake %. were calculated for maize roots and shoots. The concentration of metals in maize roots and shoots following treatments of soil with either NPs or bulk materials increased relative to control samples. In addition, the concentration of all metals was higher in maize roots than in shoots across all metals concentrations studied. The uptake of Cd and Zn by maize roots and shoots grown in soils treated with bulk compounds was higher than for those grown in equivalent treated soil with NPs. The majority of NPs and their bulk materials had no significant negative effects on maize growth parameters. However, CdS NPs, CdClz and ZnO NPs had negative effects on the length of maize roots and shoots at the highest metal soil ratio (1.0 and 1.25 mg kg-I). The calculated maize growth parameters (TI, AE, BCR, RI, uptake and uptake %) were varied in maize roots and shoots depending on the plant part, growth period and metal treatments. The toxic effects of CdS NPs (0-100 mg L-1) and ZnO NPs (0-1000 mg L-1) on the germination and the development of maize root were studied for 8 days. The results indicated that the concentration of Zn in maize seeds and roots was higher than Cd for equivalent initial NPs concentrations. Most of the NP concentrations studied had a negative effect on the length and dry weight of maize roots. Germination of maize seed was reduced by the ZnO NPS (68.6%) more than that of CdS (58.1 %). The uptake of CdS, ZnO, and CuO NPs was also investigated for maize plants grown in Eutric Cambisol soil and hydroponic culture over 21 days. High NPs concentrations were used across both growth mediums (0.01-1.0 g kg-1 /g L-1). The TI, AE, BCR, RI, uptake and uptake % were also calculated for maize roots and shoots. The concentration of all NPs showed a similar trend of accumulation behaviour in maize roots and shoots to those found in low concentrations of NPs « 1.25 mg kg-1). The concentration of all metals in maize roots and shoots grown in nutrient solution containing NPs was higher than those grown in the NP treated soil. In addition, the impact of all NPs indicate that CuO and CdS NPs has negative effect on the length of maize roots and shoots at the highest concentrations in both cultures. Moreover, the dry weight of maize shoots was decreased by CdS NPs at the highest concentration in hydroponic culture. The calculated maize growth parameters were also varied in maize roots and shoots depending on the plant part, growth period and metal concentrations. The adsorption kinetics and desorption % of CdS, ZnO, and CuO NPs was studied on the surface of four soils using the batch method. Adsorption isotherms were evaluated by Freundlich and Langmuir model. The results of study suggest that the adsorption of all NPs increased as a function of increasing NPs concentrations until the adsorption equilibrium was reached across all soils. The relative mean adsorption of NPs in four soils was found to follow the following order: Cu > Cd >' Zn. Results also indicated that the highest adsorption of NP on soils was as follows: Libyan sandy soil> Eutric Cambisol soil > Sandy soil > Haplic podzol soil. The adsorption results for all NPs were best modelled using Freundlich equation across all soils. The kinetic behaviour of all studied NPs toward four soils showed the pseudo-second order rather than pseudo-first order kinetics. The mean desorption % of NPs in four soils was found to follow the following order: Zn > Cd > Cu. The effect of CdS, CuO, and ZnO NPs on the rate of nitrogen mineralization was investigated in Eutric Cambisol, Haplic podzol, and Sandy soil over 28 days, three concentrations of each metal NP were used (0.01-l.0 g kg-1). The influence of all test NPs on soils respiration rate was also examined for 48 hours using the same NPs concentrations above. The results of nitrogen mineralization revealed that, the concentration of nitrate (N03-) accumulated readily in three soils; however, the concentrations of ammonium (NH/), dissolved organic nitrogen (DON) and free amino acids had low levels of accumulation across all of test soil and NP types. The comparison results of NPs impact indicated that the large majority of NPs failed to reveal any significant effect upon nitrogen mineralization under any of the NP concentrations save that for amino acid concentrations. Results of soil respiration revealed that no negative significant impacts for all NPs on soil respiration across all NPs and soil types.
25
McCarthy, Dawn R. "Belowground Carbon Processes in Managed Oak-Hickory Forests of Southeastern Ohio". Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1226451729.
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26
Reyes, Javier. "EXPLORING SPATIAL AND TEMPORAL VARIABILITY OF SOIL AND CROP PROCESSES FOR IRRIGATION MANAGEMENT". UKnowledge, 2018. https://uknowledge.uky.edu/pss_etds/107.
Testo completoAbstract (sommario):
Irrigation needs to be applied to soils in relatively humid regions such as western Kentucky to supply water for crop uptake to optimize and stabilize yields. Characterization of soil and crop variability at the field scale is needed to apply site specific management and to optimize water application. The objective of this work is to propose a characterization and modeling of soil and crop processes to improve irrigation management. Through an analysis of spatial and temporal behavior of soil and crop variables the variability in the field was identified. Integrative analysis of soil, crop, proximal and remote sensing data was utilized. A set of direct and indirect measurements that included soil texture, electrical conductivity (EC), soil chemical properties (pH, organic matter, N, P, K, Ca, Mg and Zn), NDVI, topographic variables, were measured in a silty loam soil near Princeton, Kentucky. Maps of measured properties were developed using kriging, and cokriging. Different approaches and two cluster methods (FANNY and CLARA) with selected variables were applied to identify management zones. Optimal scenarios were achieved with dividing the entire field into 2 or 3 areas. Spatial variability in the field is strongly influenced by topography and clay content. Using Root Zone Water Quality Model 2.0 (RZWQM), soil water tension was modeled and predicted at different zones based on the previous delineated zones. Soil water tension was measured at three depths (20, 40 and 60 cm) during different seasons (20016 and 2017) under wheat and corn. Temporal variations in soil water were driven mainly by precipitation but the behavior is different among management zones. The zone with higher clay content tends to dry out faster between rainfall events and reveals higher fluctuations in water tension even at greater depth. The other zones are more stable at the lower depth and share more similarities in their cyclic patterns. The model predictions were satisfactory in the surface layer but the accuracy decreased in deeper layers. A study of clay mineralogy was performed to explore field spatial differences based on the map classification. kaolinite, vermiculite, HIV and smectite are among the identified minerals. The clayey area presents higher quantity of some of the clay minerals. All these results show the ability to identify and characterize the field spatial variability, combining easily obtainable data under realistic farm conditions. This information can be utilized to manage resources more effectively through site specific application.
27
Gräff, Thomas. "Soil moisture dynamics and soil moisture controlled runoff processes at different spatial scales : from observation to modelling". Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5447/.
Testo completoAbstract (sommario):
Soil moisture is a key state variable that controls runoff formation, infiltration and partitioning of radiation into latent and sensible heat. However, the experimental characterisation of near surface soil moisture patterns and their controls on runoff formation remains a challenge. This subject was one aspect of the BMBF-funded OPAQUE project (operational discharge and flooding predictions in head catchments). As part of that project the focus of this dissertation is on: (1) testing the methodology and feasibility of the Spatial TDR technology in producing soil moisture profiles along TDR probes, including an inversion technique of the recorded signal in heterogeneous field soils, (2) the analysis of spatial variability and temporal dynamics of soil moisture at the field scale including field experiments and hydrological modelling, (3) the application of models of different complexity for understanding soil moisture dynamics and its importance for runoff generation as well as for improving the prediction of runoff volumes.
To fulfil objective 1, several laboratory experiments were conducted to understand the influence of probe rod geometry and heterogeneities in the sampling volume under different wetness conditions. This includes a detailed analysis on how these error sources affect retrieval of soil moisture profiles in soils.
Concerning objective 2 a sampling strategy of two TDR clusters installed in the head water of the Wilde Weißeritz catchment (Eastern Ore Mountains, Germany) was used to investigate how well “the catchment state” can be characterised by means of distributed soil moisture data observed at the field scale. A grassland site and a forested site both located on gentle slopes were instrumented with two Spatial TDR clusters that consist of up to 39 TDR probes.
Process understanding was gained by modelling the interaction of evapotranspiration and soil moisture with the hydrological process model CATFLOW. A field scale irrigation experiment was carried out to investigate near subsurface processes at the hillslope scale. The interactions of soil moisture and runoff formation were analysed using discharge data from three nested catchments: the Becherbach with a size of 2 km², the Rehefeld catchment (17 km²) and the superordinate Ammelsdorf catchment (49 km²).
Statistical analyses including observations of pre-event runoff, soil moisture and different rainfall characteristics were employed to predict stream flow volume. On the different scales a strong correlation between the average soil moisture and the runoff coefficients of rainfall-runoff events could be found, which almost explains equivalent variability as the pre-event runoff. Furthermore, there was a strong correlation between surface soil moisture and subsurface wetness with a hysteretic behaviour between runoff soil moisture.
To fulfil objective 3 these findings were used in a generalised linear model (GLM) analysis which combines state variables describing the catchments antecedent wetness and variables describing the meteorological forcing in order to predict event runoff coefficients. GLM results were compared to simulations with the catchment model WaSiM ETH. Hereby were the model results of the GLMs always better than the simulations with WaSiM ETH. The GLM analysis indicated that the proposed sampling strategy of clustering TDR probes in typical functional units is a promising technique to explore soil moisture controls on runoff generation and can be an important link between the scales. Long term monitoring of such sites could yield valuable information for flood warning and forecasting by identifying critical soil moisture conditions for the former and providing a better representation of the initial moisture conditions for the latter.Abflussentwicklung, Infiltration und die Umverteilung von Strahlung in latenten und sensiblen Wärmestrom werden maßgeblich durch die Bodenfeuchte der vadosen Zone gesteuert. Trotz allem, gibt s wenig Arbeiten die sich mit der experimentellen Charakterisierung der Bodenfeuchteverteilung und ihre Auswirkung auf die Abflussbildung beschäftigen. Der Fokus dieser Dissertation wurde darauf ausgerichtet: (1) die Methode des Spatial TDR und deren Anwendbarkeit einschließlich der Inversion des TDR Signals in heterogenen Böden zu prüfen, (2) die Analyse der räumlichen und zeitlichen Dynamik der Bodenfeuchte auf der Feldskala einschließlich Feldexperimenten und hydrologischer Modellierung, (3) der Aufbau verschiedener Modellanwendungen unterschiedlicher Komplexität um die Bodenfeuchtedynamiken und die Abflussentwicklung zu verstehen und die Vorhersage des Abflussvolumens zu verbessern. Um die Zielsetzung 1 zu erreichen, wurden verschiedene Laborversuche durchgeführt. Hierbei wurde der Einfluss der Sondenstabgeometrie und verschiedener Heterogenitäten im Messvolumen bei verschiedenen Feuchtegehalten untersucht. Dies beinhaltete eine detaillierte Analyse wie diese Fehlerquellen die Inversion des Bodenfeuchteprofils beeinflussen. Betreffend der Zielsetzung 2, wurden 2 TDR-Cluster in den Quellgebieten der Wilden Weißeritz installiert (Osterzgebirge) und untersucht, wie gut der Gebietszustand mit räumlich hochaufgelösten Bodenfeuchtedaten der Feldskala charakterisiert werden kann. Um die Interaktion zwischen Evapotranspiration und Bodenfeuchte zu untersuchen wurde das hydrologische Prozessmodell CATFLOW angewendet. Ein Beregnungsversuch wurde durchgeführt um die Zwischenabflussprozesse auf der Hangskala zu verstehen. Die Interaktion zwischen Bodenfeuchte und Abflussentwicklung wurde anhand von drei einander zugeordneten Einzugsgebieten analysiert. Statistische Analysen unter Berücksichtigung von Basisabfluss, Bodenvorfeuchte und verschiedenen Niederschlagscharakteristika wurden verwendet, um auf das Abflussvolumen zu schließen. Auf den verschiedenen Skalen konnte eine hohe Korrelation zwischen der mittleren Bodenfeuchte und dem Abflussbeiwert der Einzelereignisse festgestellt werden. Hierbei konnte die Bodenfeuchte genauso viel Variabilität erklären wie der Basisabfluss. Im Hinblick auf Zielsetzung 3 wurden “Generalised liner models” (GLM) genutzt. Dabei wurden Prädiktorvariablen die den Gebietszustand beschreiben und solche die die Meteorologische Randbedingungen beschreiben genutzt um den Abflussbeiwert zu schätzen. Die Ergebnisse der GLMs wurden mit Simulationsergebnissen des hydrologischen Gebietsmodells WaSiM ETH verglichen. Hierbei haben die GLMs eindeutig bessere Ergebnisse geliefert gegenüber den WaSiM Simulationen. Die GLM Analysen haben aufgezeigt, dass die verwendete Messstrategie mehrerer TDR-Cluster in typischen funktionalen Einheiten eine viel versprechende Methode ist, um den Einfluss der Bodenfeuchte auf die Abflussentwicklung zu verstehen und ein Bindeglied zwischen den Skalen darstellen zu können. Langzeitbeobachtungen solcher Standorte sind in der Lage wichtige Zusatzinformationen bei der Hochwasserwarnung und -vorhersage zu liefern durch die Identifizierung kritischer Gebietszustände für erstere und eine bessere Repräsentation der Vorfeuchte für letztere.
28
Bentley, W. A. "Influences of soil nutrients, waterlogging, and disturbance factors on forest processes along a New Zealand soil chronosequence". Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596580.
Testo completoAbstract (sommario):
To test how soil nitrogen (N) and phosphorus (P) limit plant growth along a soil fertility gradient, I conducted the first fertilization experiment of its kind in a temperate rain forest, using sixty 20 x 20 m plots that sampled a retrogressive chronosequence. The effects of adding N and P fertilizer, alone and in combination, were established by measuring changes in soil chemistry, foliar N and P concentrations, photosynthetic capacity, and tree diameter and root growth. Adding P increased soil P levels similarly across all forest types, while adding N or P separately increased the soil aerobic N mineralization rate, but there was no synergistic effect. Foliar nutrient content, radial tree growth and photosynthetic capacity responses to fertilizer addition differed between species and varied with respect to surface, while root proliferation responded positively to P addition on two surfaces, but not on the third. I carried out a correlative study to examine the influences of soil waterlogging and soil nutrient levels on tree growth, floristic composition, light, and litter decomposition. Using an established grid of soil sampling points within eight 1.5-ha mapped forest strands situated across the chronosequence, I explored the relationship between soil conditions and neighbourhood processes. My results indicate that on older surfaces, soil waterlogging is an increasingly important factor influencing forest processes. Finally, to investigate the role of disturbance factors on forest age, size, and species composition, I collected tree ring cores from six common tree species in three established 1.5-ha mapped stands. I found that the dominant conifer species was hardly regenerating under present-day conditions, but had recruited en masse about 600 years ago, suggesting a widespread disturbance event or synchronous senescence at that time. Other species of conifer and angiosperm had more continuous regeneration, suggesting that they are capable of regeneration within smaller gaps in the forest.
29
Garcia-Chevesich, Pablo Andres. "Erosion Processes and Control". Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195844.
Testo completoAbstract (sommario):
This dissertation represents a unique contribution to the Spanish literature of soil erosion. The author of this document has written and published "Procesos y control de la erosion", a textbook about the engineering of soil erosion processes and the design of the most up-to-date methods and products used for erosion control. The text has been presented in Appendix A.Besides the above, the author of this dissertation is an active committee member at the International Erosion Control Association (IECA), specifically the International Development and the SOIL Fund programs. IECA members are drawn from individuals and erosion control business of different sizes. However, there was a lack of knowledge within IECA members about the formation of post-fire water repellent layers. For instance, Appendix B is represented by an article written by the author of this document, published in Environmental Connection (Volume 2, Issue 3), on July of 2008. The article gives a general description of what post-fire water repellency is, how is it formed, what factors affect it, its consequences on soil erosion, and how to control soil erosion on an efficient way when such a layer has been formed as a consequence of fire.Finally, Appendix C is a research paper in process of submission to the International Journal of Wildland Fire, about the formation of post-fire water repellent layers on Chilean Monterrey pine plantations. Since water repellent layers following wildfires have never been documented on Chilean soils, the need for such a publication is urgent, because Chilean land managers have been ignorant of such phenomenon.
30
Sande, Leif Andrew. "Experimental Studies on Infiltration/Soil-Water Movement Processes and Green-AMPT Modeling". Thesis, North Dakota State University, 2011. https://hdl.handle.net/10365/29329.
Testo completoAbstract (sommario):
Experimental studies on infiltration/soil-water movement processes are vital to
better understanding movement of soil-water in the vadose zone. The objective of this
experimental research was to investigate infiltration/soil-water movement processes
utilizing laboratory experiments and computer modeling. Small scale laboratory soil box
infiltration experiments were conducted and utilized for the improved parameterization of
the Green-Ampt (GA) saturated moisture content parameter to produce an effective
moisture content parameter (Be) for utilization in a modified GA model. By incorporating ?e
values into GA modeling, modeling results showed greatly improved wetting front
prediction across different soil conditions. A new soil packing method was proposed for
replicating complex microtopographical surfaces with uniform bulk densities in laboratory
soil box experiments which proved efficient and effective at accomplishing both objectives.
A rainfall simulator and an instantaneous-profile laser scanner were used to simulate
rainfall and quantify surface microtopography for experiments. The results clearly show the
effect of microtopography on infiltration and soil-water movement characteristics. This
offers valuable insight into infiltration/soil-water movement processes as affected by
different soil and surface microtopographic conditions.National Science Foundation (Grant No. EAR-0907588)
31
Creamer, Rachel. "Assessing the effects of metals on soil invertebrates, processes and ecosystems". Thesis, University of Newcastle Upon Tyne, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427300.
Testo completo
32
Shibata, Makoto. "Soil Ecosystem Processes in Tropical Forests, Savanna, and Croplands of Cameroon". Kyoto University, 2018. http://hdl.handle.net/2433/232365.
Testo completoAbstract (sommario):
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第21164号
農博第2290号
新制||農||1060(附属図書館)
学位論文||H30||N5138(農学部図書室)
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 舟川 晋也, 教授 縄田 栄治, 教授 北山 兼弘
学位規則第4条第1項該当
33
Rodriguez, Andres F. "Soil Building Processes in Reconstructed Tree Islands in The Everglades, Florida". FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/1021.
Testo completoAbstract (sommario):
Soil building processes were studied in reconstructed tree islands in the Loxahatchee Impoundment Landscape Assessment, Florida. Soil building was evaluated by measuring litter production, litter decomposition, soil accretion, and changes in soil elevation under different hydrologic conditions, and by determining physicochemical characteristics of newly accreted soils. Tree islands showed higher litter production and soil accretion but a larger loss of soil elevation caused by subsidence at higher elevations and shorter inundation periods. Newly accreted soils exhibited higher nutrient concentrations, and organic matter (OM) than older soils. Most of the soil phosphorus was stored in the organic fraction. A positive correlation was found between soil nutrients and OM. Reconstructed tree islands are increasing in soil OM and nutrients, generating a positive feedback that increases tree productivity, and soil building. These findings contribute to the understanding of tree islands’ dynamics and can be used by managers for restoration efforts in the Everglades.
34
Blacker, Joshua John. "Chemical weathering processes leading to soil development in Arctic glacial forefields". Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/20696/.
Testo completoAbstract (sommario):
Few Arctic forefields have been studied previously for their role in soil formation and in the carbon cycle. Yet, despite their prevailing polar climate, their soils may develop quickly and be extensive. Rock water residence times are prolonged in glacial tills that contain a rock flour component with high surface area and reactive that amasses in the forefields of glaciers as they retreat. Rapid sulfide oxidation and carbonate dissolution could be a potential CO2 source to the atmosphere, while silicate-weathering and soil organic carbon accumulation a CO2 sink. The extent of these sink-source reactions, and the soil forming processes that affect these, were tested over a century of Arctic forefield soil formation. In young, subglacial till-based moraine soils, the rapid depletion of accessory sulfide and carbonates minerals in the initial, and up to about 60-years of exposure, reflected widespread sulfide oxidation and carbonate dissolution. Defining young forefield soils as a potential transient CO2 source to the atmosphere, since potential CO2 sinks, namely calcium silicate mineral weathering and soil organic carbon accumulation were retarded, and limited to the older moraine soils. The slow onset of biological evolution in Arctic forefields and proton consumption by carbonates, present in the forefield lithologies, are suggested as the principal reasons for the limited silicate weathering and in turn soil formation. The results from this thesis may have new implications for the carbon cycle. Given glacial–interglacial cycles that have waxed and waned throughout Earth history, and carbonate and sulfide minerals are common in most lithologies made up of low to medium grade metamorphic and metasedimentary rocks. However, higher resolution temporal (diurnal to seasonal) and spatial field studies are needed in-order to more confidentially up-scale these findings beyond a glacier catchment scale.
35
Dose, Heather Lynn. "Advancing Soil Health: Linking Belowground Microbial Processes to Aboveground Land Management". Diss., North Dakota State University, 2016. http://hdl.handle.net/10365/25546.
Testo completoAbstract (sommario):
Advancing soil health lies at the intersection of belowground microbial processes and aboveground land management. However, linking microbial processes to land use is difficult. Understanding the response of soil microbes to management factors will provide agricultural producers and land managers with information regarding best management practices that not only improve soil health, but also maximize profitability. This study advances the understanding of microbial responses to land management by measuring microbial response to a) amendment application and tile drainage to remediate sodic soils, b) cover crop growth and tile drainage to ameliorate saline soils and c) tillage and fertilizer management factors on Bradyrhizobium japonicum, a symbiotic bacteria needed for biological N fixation in soybeans (Glycine max L.). Multiple time point measurements of soil microbial enzymes and functional gene copy numbers from three field experiments were used to determine microbial responses to land management. Key findings indicate that gypsum amendment applications, although effective at reducing sodicity, reduce soil enzyme activity levels in the short-term while tile drainage has no effect on microbial response to sodic soils. This work also demonstrates that the quantity of nitrifiers and denitrifiers can be used as either short?term or long?term indicators of soil health which reflect overall ecosystem health in sodic soils. In contrast to sodic soils, nitrifiers and denitrifiers are not useful indicators of soil health in saline soils as these microbial communities exhibit salinity induced community tolerance. Finally, tillage system and N availability have the greatest effect on B. japonicum numbers and activity in the soil. The lower amount of N obtained from biological N fixation in soybeans grown under no till systems reflects the reduced reliance on B. japonicum for plant N needs. Inoculated populations of B. japonicum are important for early season biological N fixation, but persistent and diverse populations of B. japonicum play an important role in late season N fixation in the lateral soybean root nodules. Overall, this work demonstrates that monitoring soil microbial activity can be useful for producers and land managers looking to improve soil health.USDA-Natural Resources Conservation Service-Conservation Innovation Grant
North Dakota Soybean Council
North Dakota Agricultural Experiment Station Fellowship
North Dakota Water Resources Research Institute Fellowship
36
Duston, Stephanie Ann. "Capturing and Characterizing Soluble Organic Matter Dynamics in Soil Formation Processes". Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/99850.
Testo completoAbstract (sommario):
Dissolved organic matter (DOM) is a highly complex, heterogeneous mix of compounds with diverse functional groups that contribute to several environmental processes such as organo-mineral complexation, nutrient bioavailability, and mineral dissolution. Because of these contributions of DOM to important ecosystem processes, it is often of interest to quantify the flux of DOM moving through different parts of ecosystems. Unfortunately, the complexity and variability of DOM makes quantification and chemical analysis of fluxes challenging. This thesis has two components, the first examines the potential of using four different resins for the purpose of quantifying time-integrated DOM fluxes across two source (e.g. Douglas fir and Yellow poplar) and concentration (30 and 5 mg C/L) leaf-extracts. The second explores how water soluble organic matter (WSOM) changes along spatial gradients of podzolization in a northeast glaciated headwater catchment. Findings from the resin study suggest that quaternary amine Cl- resins with a cross-linked polyacrylamide matrix and gel structure have the best suitability for in-situ sampling of DOM over time. While these resins only captured and allowed for the analysis of ~ 30% of dissolved organic carbon (C) in a series of laboratory studies, it is recognized that only ~50% of natural DOM may be ionized and sorbed electrostatically. Thus, for mass balance approaches, the use of resins would require an adjustment factor to better estimate soluble loads. Though, the observed robustness across source and concentration suggests that resins may be appropriate for indexing DOM fluxes to compare across space, time, or treatments. The second portion of this study examined chemical characteristics of water-soluble organic matter (WSOM) extracted from soils and of DOM sampled from shallow groundwater wells. Quantification of WSOM carbon content and spectroscopic analyses were used to compare samples based on genetic horizon and to compare differences along gradients of lateral and vertical podzolization. Findings show that there were significant trends in WSOM characteristics along podzolization horizon sequences which are indicative of microbial processing along the hillslope. Comparing spatial development of podzols (e.g. lateral versus vertical) found that WSOM in laterally developed E horizons are more microbial in nature when compared to vertically developed E horizons. There were also significant trends between WSOM extractions and groundwater collected from zones of soil development along a hillslope transect, which suggests some homogenization of WSOM as it is processed and transported downslope. This is evidenced by corresponding trends in fluorescence index, freshness index, and protein percent that were indicative of biogeochemical changes due to microbial processing and complexation. Characterizing WSOM can help predict trends in podzolization, and can help identify hotspots of biogeochemical processing.Dissolved organic matter (DOM) is made up of many different compounds that collectively contribute to several important environmental processes. The quantity and chemistry of DOM are known to vary by location on the landscape. Often, these differences are important indicators of ecosystem properties or processes. Despite the importance of DOM to ecosystem processes, sampling and analysis remain a key challenge because of DOM variability over time. This research tested a way to passively sample how much DOM moves through a location over a period of time using resins, which attract and bind a large proportion of DOM compounds so that they can be quantified. Overall, I found that one type of resin, with specific chemical and physical structure, was better at attracting and quantifying DOM and may be useful in comparing the quantity of DOM that moves through a system over time. Separately, I also looked at the chemical characteristics of DOM in different types of soils at different points along a forested hillslope in order to better understand spatial patterns of important soil processes. The results of this work identified trends in fluorescence characteristics of DOM, and indicate changes in DOM between different types of soil along the hillslope as they undergo microbial processing. There is also evidence from comparing water and soil samples that DOM from different sources become more similar as the DOM is processed and transported downslope. Characterizing DOM can help predict trends with regards to important environmental processes and allows us to identify hotspots of nutrient sources and sinks in forests.
37
Cenini, Valeria Laura. "Linkages between soil enzyme activities and critical ecosystem processes in grasslands". Thesis, Ulster University, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.692819.
Testo completoAbstract (sommario):
Soils are important life-supporting systems to human society and their long-term sustainability is high on both the scientific and political agenda. However soil functioning remains poorly understood because of the difficulty in studying complex biogeochemical interactions, which mostly occur belowground. This PhD study aims to improve the understanding of plant-soil-microbial interactions in grassland ecosystems. First, it was addressed how key microbial functions (i.e. extracellular enzyme activities) might respond to common management practices (e.g. nutrient fertilization) and to land use change (i.e. conversion from arable to grassland). Second potential linkages between enzyme activities and critical ecosystem processes such as soil carbon (C) and nitrogen (N) sequestration were investigated.
38
Marriott, Susan B. "Floodplain processes, palaeosols and alluvial architecture : modelling and field studies". Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321271.
Testo completo
39
Barella, Ortiz Anais. "Analysis and modelling of soil moisture and evaporation processes, implications for climate change". Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066115/document.
Testo completoAbstract (sommario):
Cette thèse étudie l'évaporation et l'humidité du sol, deux paramètres clefs du cycle hydrologique et du système climatique.L'évaporation potentielle (ETP) est un paramètre clef pour les modèles hydrologiques et agronomiques qui décrit les interactions entre la surface et l'atmosphère. Il constitue la base des estimations de l'évaporation réelle. Nous avons évalué, à l'échelle globale et pour le climat actuel ainsi que pour les changements attendus, des estimations de l'ETP basées sur des principes physiques ainsi que des approches empiriques. La méthode d'estimation du flux potentiel conseillée par la Food and Agriculture Organization (FAO) montre une sous évaluation par rapport au schéma de surface, ce qui a pu être relié à certaines hypothèses faites. Ceci implique aussi une sensibilité plus faible au changement climatique de la formulation proposée par la FAO. Nous avons aussi constaté que les méthodes empiriques ne représentent pas correctement l'impact du changement climatique sur l'ETP.L'humidité du sol est analysée du point de vue de la température de brillance en Bande-L (TB). Cette mesure du rayonnement émis par la surface dans une bande spectrale sensible à l'eau dans les premiers centimètres du sol, constitue une des pistes pour l'estimation de l'humidité de surface depuis l'espace. Des mesures de TB ont été comparées, au dessus de la Péninsule Ibérique, à des données simulées par deux schémas de surface. Un bon accord a été trouvé entre les observations et les simulations sur l'évolution temporelle des signaux. Par contre, les structures spatiales peuvent être très différentes au cours de l'automne et l'hiver à cause de cycles annuels très contrastésThis thesis deals with the study of evaporation and soil moisture, t wo main parameters of the hydrological cycle, and thus the climate system. First, potential evaporation (ET P ) is analysed. It is an important input to hydrological and agronomic models, key to describe the interactions between the surface e and the atmosphere, and the basis of most of the estimations of actual evapora tion. Physically-based and empirical methods to estimate ET P are evaluated, at a global scale, under current climate conditions and in a changing climate. The former methods correspond to those implemented in land surface models (LSM) and the Food and Agriculture Organization (F AO) reference evapotranspiration equation. The assumptions made in FAO's method underest imate ET P if compared to LSM methods. They also result in a lower sensitive ty of ET P to climate change. In addition, empirical equations are not able to reproduce the impact of climate change on ET P if compared to that from LSM methods. Soil moisture is the second aim of this thesis. It is treated t hrough the analysis of brightness temperatures (TB). These are a measure of the radiation emitted by the surface , and thus an optimum parameter to use in remote sensing techniques for soi l moisture retrieval. Measured TB from the Soil Moisture and Ocean Salinity (SMOS) mission are compared, over the Iberian Peninsula, to two sets of TB modelled estimates from two LSM. There is a good agreement in the temporal evolution between them. However, discrepancy es are found regarding the spatial structures, which become more evident during fall and winter and are mainly explained by differences in the annual cycle of measured and modelled TB
40
Wilson, Clare A. "Processes of post-burial change in soils under archaeological monuments : a micromorphological study with particular reference to the processes of clay and iron redistribution". Thesis, University of Stirling, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341209.
Testo completo
41
Chen, Shu-Kang. "Use of key indicator processes to assess the effects of fungicides on soil microbial processes and nitrogen dynamics /". The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487944660929768.
Testo completo
42
Townsend, Geoffrey Stephen. "Rate processes in aluminium mobilization from soils to surface waters". Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315123.
Testo completo
43
Donkin, Steven Glenn. "A soil toxicity test using the nematode Caenorhabditis elegans and some applications to studying metal ion sorption processes in soils". Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/25423.
Testo completo
44
Nave, Lucas Emil. "Nitrogen cycling in the northern hardwood forest soil, plant, and atmospheric processes /". Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1196187071.
Testo completo
45
Hellawell, Emma Elizabeth. "Modelling transport processes in soil due to hydraulic density and electrical gradients". Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240839.
Testo completo
46
Achatz, Michaela [Verfasser]. "Hyphal mediated transport processes of the allelochemical juglone in soil / Michaela Achatz". Berlin : Freie Universität Berlin, 2013. http://d-nb.info/1045604208/34.
Testo completo
47
Quine, T. A. "An evaluation of soil analysis for determining formation processes on archaeological sites". Thesis, University of Strathclyde, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382402.
Testo completo
48
Jones, Nastassia Nicole. "The analysis of humic substances as an electron donor for soil processes /". Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1400959831&sid=7&Fmt=2&clientId=1509&RQT=309&VName=PQD.
Testo completoAbstract (sommario):
Thesis (M.S.)--Southern Illinois University Carbondale, 2007."Department of Molecular Biology, Microbiology and Biochemistry." Includes bibliographical references (leaves 59-66). Also available online.
49
Girkin, Nicholas T. "Tropical forest greenhouse gas emissions : root regulation of soil processes and fluxes". Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/52949/.
Testo completoAbstract (sommario):
Tropical forested peatlands are a major carbon store and are a significant source of global carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions. While the role of environmental variables, including temperature and water table depth have been relatively well studied, uncertainty remains in the extent to which plant roots regulate greenhouse gas (GHG) fluxes and peat biogeochemistry. This study examined the role of roots, and root inputs of carbon and oxygen in regulating fluxes from peat under two dominant plant species, Campnosperma panamensis and Raphia taedigera, a broadleaved evergreen tree and canopy palm, in San San Pond Sak wetland, in Bocas del Toro Province, Panama. A combination of in situ and ex situ experiments were performed between February 2015 and August 2017. Small scale variation in GHG fluxes and peat biogeochemistry was measured at two distances within the rooting zones of C. panamensis and R. taedigera. Peat organic matter properties were assessed using Rock-Eval 6 pyrolysis. Results indicated significant variation in CH4 but not CO2 fluxes at different distances within the rooting zone, with CH4 fluxes subsequently linked to measures of the overall size of the available organic carbon pool (S2). Rock-Eval pyrolysis data was used to construct a three-pool model of organic matter thermostability which indicated significant differences in organic matter composition between peats derived from different botanical origins, in addition to a high level of heterogeneity within the rooting zone. Changes in GHG production and peat biogeochemical properties in response to the addition of root exudate analogues were assessed in an ex situ anoxic incubation experiment. A combination of organic acids and sugars, identified as common forest plant root exudate components, were added over a two week period to peats derived from C. panamensis and R. taedigera. GHG fluxes varied significantly between treatments but not by peat botanical origin, and were associated with significant changes in soil properties including, pH and redox potential, thereby demonstrating a link between plant root carbon inputs, peat properties and GHG fluxes. In situ mesocosms were used to assess the effects of root exclusion on peat biogeochemistry and GHG fluxes. Partial and full root exclusion significantly reduced dissolved oxygen concentrations and was associated with greater root necromass. Full root exclusion increased CH4 fluxes five-six fold compared to partial root exclusion, equivalent to an 86 - 90% reduction in CH4 oxidation, demonstrating the important role of root inputs of oxygen in mitigating CH4 efflux from tropical peat. A 13CO2 pulse labelling experiment was conducted using both R. taedigera, C. panamensis, and Symphonia globulifera, a second broadleaved evergreen tree species, to demonstrate a direct link between plant photosynthesis and CH4 fluxes, and identify aspects of the bacterial and fungal community associated with the turnover of labile carbon. The extent of 13C enrichment of CH4 differed significantly between plant types (palms vs broadleaved evergreen trees), as did the extent of net CH4 efflux. Phospholipid fatty acid (PLFA) biomarker analysis indicated both peat types were dominated by Gram negative bacteria. There was strong 13C enrichment of Gram negative bacteria, supporting their previously proposed role as important decomposers of labile carbon. Collectively, these results demonstrate that root inputs of carbon and oxygen can strongly regulate tropical peatland GHG fluxes, and that the extent of regulation can vary significantly between tropical wetland plant species from contrasting dominant plant types. This is particularly important in understanding regulatory processes in a globally significant carbon store and understanding possible consequences of land use change in the tropics.
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Lundgren, Andreas. "Effects of wild boar (Sus scrofa) on soil processes and tree growth". Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-446681.
Testo completoAbstract (sommario):
Wild boars (Sus scrofa) have increased rapidly in population size and home range since their reintroduction to the Swedish fauna. Through their rooting behaviour, the boars can cause great disturbance to the ecosystem. The consequences of this disturbance have been recorded in many parts of the world but the effects they have on boreal forest ecosystems have been less studied.In this study I examined to what extent wild boars affect (i) the soil microbial community, (ii) the soil respiration, (iii) the soil C and nutrient content, as well as (iv) the growth of trees in a boreal forest in central Sweden. Enclosures that have harboured wild boars for seven years were compared with nearby areas without wild boars in both a pine forest and a spruce forest. Using phospholipid fatty acid (PLFA) analyses, the soil microbial biomass, community, and fungi:bacteria ratio were investigated in the treatments. The soil respiration was measured monthly from June to November. The total soil concentrations of C, N and P were examined as well as the availability of N in the form of NO3-and NH4+. Tree growth was measured by measuring tree ring width and comparisons were made by looking at the relative ring width of tree cores before and after the introduction of wild boars. I found that the soil microbial community did generally not differ between the treatments, except for a higher fungi:bacteria ratio within the enclosures. Soil respiration was consistently lower in the enclosures throughout all months. Soil nutrient levels were similar between the treatments except for a slightly lowertotal P content and NO3-content in the pine forest enclosure. Lastly, the tree growth was severely decreased by the presence of wild boars. In summary my study suggests that anincrease of the wild boar population in boreal forests may have a minor impact on many soil processes, while tree growth can be hampered. However, studies in natural ecosystems are needed to investigate this effect further.