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Doctor of Philosophy / Department of Agronomy / Charles W. Rice / Soil C sequestration in agricultural ecosystems is an immediate and significant option to mitigate the increase in the atmospheric CO2 concentration. The objectives of this study were to determine 1) the influence of crop and soil management practices applicable to Kansas (i.e., tillage, N fertilization, and crop rotations) on soil C and N, C sequestration rates, soil aggregation and aggregate-associated C and N; and 2) the influence of long-term tillage practices on SOC and total N, soil aggregation and aggregate-associated C and N in three soil types: an Oxisol (Brazil), a Vertisol (Argentina), and a Mollisol (Kansas, USA). The Kansas experiments included: tillage (conventional tillage (CT), reduced tillage (RT) and no-tillage (NT)) and native prairie; nitrogen (N) fertilization rates; and crop rotations comprising various combinations of winter wheat (Triticum aestivum L.), grain sorghum (Sorghum bicolor L. Moench), and soybean (Glycine max L. Merrill). The presence of a fallow period negatively affected C sequestration rates even under NT systems. Nitrogen fertilization generally increased C sequestration rates. Rotations that contained wheat or sorghum had the greatest C sequestration rates while continuous soybean had the lowest rates. Cultivation decreased the amount of macroaggregates with a concomitment increased in the amount of microaggregates. Wheat and sorghum increased total C in the macroaggregate fraction (>250 mm) under NT while soybean had the lowest C concentration. Cultivation reduced microbial biomass C and N and potentially mineralizable C and N. The combination of conservation tillage and rotations that produced a greater amount of residue had greater C sequestration rates. In the Oxisol, NT had greater amounts of large macroaggregates (>2000 mm) than CT, however no differences between tillage practices were detected in the Vertisol and Mollisol. Cultivation of native grassland reduced the amount of macroaggregates and the associated C and N concentration; however NT tended to be more similar to the native grassland. Overall, our results indicated that the use of conservation tillage could be an important strategy to sequester C in these agroecosystems. The adoption of management practices that enhance C sequestration would be important for reducing GHGs emissions and maintaining the sustainability of agricultural systems.

Les régions urbaines imposent d’intenses et multiples changements environnementaux sur les écosystèmes qu’elles contiennent et qui les entourent, et les réponses des écosystèmes à ces environnements urbains est encore relativement peu connue, même pour des processus fondamentaux comme les cycles du carbone (C) et de l’azote (N). Ce travail utilise une chronoséquence de systèmes sol-arbre d’alignement (plantations de Tilia tomentosa Moench) de 75 ans, situés à Paris, comme étude de cas principale, afin de détecter des tendances de long terme dans les cycles urbain du C et du N et d’en inférer les potentiels mécanismes sous-jacents. Un patron d’accumulation du C et du N dans les sols de rue est décrit, et nous faisons l’hypothèse que le C dérivé des racines, et le N issu des dépôts atmosphérique et apports animaux, s’accumulent dans ces sols. Ensuite, une analyse des fractions organo-minérales des sols suggère qu’il y a bien une accumulation de matière organique du sol (MOS) relativement récente. Les analyses 13C et 15N suggèrent que les racines sont un contributeur majeur à cette augmentation de la teneur en MOS et de la rétention du N exogène. Les taux de nitrification et de dénitrification potentielles augmentent avec l’âge des systèmes de rue, ce qui semble être déterminé par une augmentation des bactéries oxydant l’ammoniaque. Les dynamiques de long terme pour le C semblent caractérisées by une augmentation des apport hypogés couplée à des mécanismes de stabilisation du C racinaire. Pour le N, les sorties de N semblent contrebalancées par d’importants apports exogènes et les racines, apports dont une partie est retenue dans la biomasse végétale (racines) et la MOS. / Urban areas impose multiple and intense environmental changes on the ecosystems they contain or that surround them, and the ecosystem responses to urban environments are still poorly known, even on fundamental ecosystem processes such as carbon (C) and nitrogen (N) cycling. The dynamics of urban ecosystems, especially on the long-term, have received little attention. The present work uses a 75-year chronosequence of street soil-tree systems (plantations of Tilia tomentosa Moench) in Paris, France, as its main case study to detect long-term patterns in urban C and N cycling and infer potential underlying mechanisms. This thesis describes age-related patterns of C and N accumulation in soils, and we hypothesize that tree root-derived C and deposited N from the atmosphere and animal waste accumulate in soils. Then, an analysis of soil particle-size fractions further points towards a recent accumulation of soil organic matter (SOM), and 13C and 15N analysis suggests that tree roots are a major contributor to the increase of SOM content and N retention. Potential nitrification and denitrification rates increase with street system age, which seems driven by an increase in ammonia-oxidising bacteria. The long-term dynamics of C seem characterized by increasing belowground inputs coupled with root-C stabilization mechanisms. For N, the losses are likely compensated by exogenous inputs, part of which is retained in plant biomass (roots) and SOM.These results are then discussed in light of results obtained on Parisian black locust systems (Robinia pseudoacacia Linnæus), as well as other data, and management recommendations are proposed.

Yes / Objectives Studies of the carbon and nitrogen stable isotope ratios (δ13C and δ15N) of modern tissues with a fast turnover, such as hair and fingernails, have established the relationship between these values in mothers and their infants during breastfeeding and weaning. Using collagen from high-resolution dentine sections of teeth which form in the perinatal period we investigate the relationship between diet and physiology in this pivotal stage of life. Materials and Methods Childhood dentine collagen δ13C and δ15N profiles were produced from horizontal sections of permanent and deciduous teeth following the direction of development. These were from two 19th-century sites (n = 24) and a small number (n = 5) of prehistoric samples from Great Britain and Ireland. Results These high-resolution data exhibit marked differences between those who survived childhood and those who did not, the former varying little and the latter fluctuating widely. Discussion Breastfeeding and weaning behavior have a significant impact on the morbidity and mortality of infants and the adults they become. In the absence of documentary evidence, archaeological studies of bone collagen of adults and juveniles have been used to infer the prevalence and duration of breastfeeding. These interpretations rely on certain assumptions about the relationship between isotope ratios in the bone collagen of the adult females and the infants who have died. The data from this study suggest a more complex situation than previously proposed and the potential for a new approach to the study of maternal and infant health in past populations.

Yes / Background: stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) in bone and dentine collagen have been used for over 30 years to estimate palaeodiet, subsistence strategy, breastfeeding duration and migration within burial populations. Recent developments in dentine microsampling allow improved temporal resolution for dietary patterns. Aim: We propose a simple method which could be applied to human teeth to estimate chronological age represented by dentine microsamples in the direction of tooth growth, allowing comparison of dietary patterns between individuals and populations. The method is tested using profiles from permanent and deciduous teeth of two individuals. Subjects and methods: using a diagrammatic representation of dentine development by approximate age for each human tooth (based on the Queen Mary University of London Atlas) (AlQahtani et al., 2010), we estimate the age represented by each dentine section. Two case studies are shown: comparison of M1 and M2 from a 19th century individual from London, England, and identification of an unknown tooth from an Iron Age female adult from Scotland. Results and conclusions: The isotopic profiles demonstrate that variations in consecutively-forming teeth can be aligned using this method to extend the dietary history of an individual, or identify an unknown tooth by matching the profiles.

Yes / Archaeological skeletal material from most sites represents a cross-sectional, opportunistic sample of the burials. These are influenced by the proportion and area of the site which is excavated, the taphonomic conditions and survival of tissues. This may not be representative of the population, and in an attritional cemetery may represent a long period of use, during which humans will have differing life-courses. Here we describe a commingled skeletal assemblage, the only human remains recovered from the historically significant medieval site of St Stephen’s Chapel, Palace of Westminster, London. Using carbon (δ13C) and nitrogen (δ15N) stable isotope ratios of bulk bone collagen and incremental dentine to investigate dietary life histories from 5 individuals, we combine the evidence with radiocarbon dating to assign them to two different temporal cohorts.

<p>Stone Age research on Northern Europe frequently makes gross generalizations about the Mesolithic and Neolithic, although we still lack much basic knowledge on how the people lived. The transition from the Mesolithic to the Neolithic in Europe has been described as a radical shift from an economy dominated by marine resources to one solely dependent on farming. Both the occurrence and the geographical extent of such a drastic shift can be questioned, however. It is therefore important to start out at a more detailed level of evidence in order to present the overall picture, and to account for the variability even in such regional or chronological overviews. Fifteen Stone Age sites were included in this study, ranging chronologically from the Early Mesolithic to the Middle or Late Neolithic, c. 8300–2500 BC, and stretching geographically from the westernmost coast of Sweden to the easternmost part of Latvia within the confines of latitudes 55–59° N. The most prominent sites in terms of the number of human and faunal samples analysed are Zvejnieki, Västerbjers and Skateholm I–II. Human and faunal skeletal remains were subjected to stable carbon and nitrogen isotope analysis to study diet and ecology at the sites. Stable isotope analyses of human remains provide quantitative information on the relative importance of various food sources, an important addition to the qualitative data supplied by certain artefacts and structures or by faunal or botanical remains. A vast number of new radiocarbon dates were also obtained.</p><p>In conclusion, a rich diversity in Stone Age dietary practice in the Baltic Region was demonstrated. Evidence ranging from the Early Mesolithic to the Late Neolithic show that neither chronology nor location alone can account for this variety, but that there are inevitably cultural factors as well. Food habits are culturally governed, and therefore we cannot automatically assume that people at similar sites will have the same diet. </p><p>Stable isotope studies are very important here, since they tell us what people actually consumed, not only what was available, or what one single meal contained. We should not be deceived in inferring diet from ritually deposited remains, since things that were mentally important were not always important in daily life. Thus, although a ritual and symbolic norm may emphasize certain food categories, these may in fact contribute very little to the diet. By the progress of analysis of intra-individual variation, new data on life history changes have been produced, revealing mobility patterns, breastfeeding behaviour and certain dietary transitions. The inclusion of faunal data has proved invaluable for understanding the stable isotope ecology of a site, and thereby improve the precision of the interpretations of human stable isotope data. The special case of dogs, though, demonstrates that these animals are not useful for inferring human diet, since, due to the number of roles they possess in human society, dogs could deviate significantly from humans in their diet, and in several cases have been proved to do so. </p><p>When evaluating radiocarbon data derived from human and animal remains from the Pitted-Ware site of Västerbjers on Gotland, the importance of establishing the stable isotope ecology of the site before making deductions on reservoir effects was further demonstrated. </p><p>The main aim of this thesis has been to demonstrate the variation and diversity in human practices, challenging the view of a “monolithic” Stone Age. By looking at individuals and not only at populations, the whole range of human behaviour has been accounted for, also revealing discrepancies between norm and practice, which are frequently visible both in the archaeological record and in present-day human behaviour. </p>

Anthropogenic activities surrounding horticulture, agriculture and recreation have increased dispersal of invasive earthworms. The introduction of earthworms initiates many physical and chemical alterations in forest soils previously unoccupied by earthworms. Three trials were performed to assess the effects of earthworms on soil-water dynamics, C and N and defensive/storage compound production by a native plant. The first trial was a greenhouse experiment, performed to assess the impact of two ecologically contrasting invasive earthworm species on percolate and evaporative soil water loss. Mesocosms were constructed to simulate a typical forest Entisol commonly penetrated by the species of interest, Lumbricus terrestris and Amynthas agrestis. Earthworms were added in pair and combination to replicate an average population density observed in Vermont. Percolate water was collected and evaporative water loss balance was recorded over a period of 140 days. C and N were quantified in A-horizon bulk and aggregate soil as well as the subsoil. Residual surface leaf litter was also quantified. Results indicated significantly increased evaporative water loss where either worm was present. Conversely, percolate water loss was significantly reduced in presence L. terrestris alone. C and N analysis revealed that only L. terrestris had a significant effect on aggregate soil C. While the abundance of many herbaceous species is reduced at invasive earthworm sites, Arisaema triphyllum anecdotally have greater densities where earthworms are present. It has been hypothesized that the greater density is caused by a trait that allows this plant to store Ca, often observed at increased concentrations in earthworm invaded soils as Ca-oxalate Here, we tested the hypothesis that oxalate increases in A. triphyllum when earthworms are present. As such, we conducted a two-way factorial greenhouse trial to test whether the changes to soil properties made by two invasive earthworm species (Amynthas agrestis and Lumbricus rubellus) or their physical presence (and bioturbation) had an effect on the plant production of oxalate. Upon quantification of variable soluble oxalate in corms after senescence, we found that earthworm presence increased water soluble and total oxalate significantly as well as marginally significantly in the case of HCl soluble oxalate. No significant changes in oxalate concentrations were observed under soil treatments alone. Carbon and nitrogen are found extensively in both terrestrial and atmospheric cycles. A shift in the equilibrium of these elements can suggest a strong interaction between an introduced variable (invasive earthworms in this case) and the abiotic environment. To better understand changes in soil properties with earthworm invasion, a 112-day mesocosm study was undertaken to examine C and N dynamics. Two epi-endogeic invasive earthworm species Lumbricus rubellus and Amynthas agrestis were selected for study. Greenhouse gas production by total mesocosm and soil were monitored. Gas flux measurements on 11 dates indicate both worm species increase CO2 and N2O emitted from mesocosm system as well as soil. Mesocosm total C and N (mass balance) indicate significantly more N but no change in C where earthworms are present. This indicates a disruption of denitrification by earthworm invasion that results in increased N2O emissions. This research is the first to examine these variables in concert and confirms holistic view is essential when examining natural systems.

This work has been a study of systems, mostly of sulfa-drugs, showing polymorphic behaviour. Using different means as solid state NMR, X-ray analysis, and theoretical calculations, we have seen how it is possible to understand results obtained from the different techniques, proving how the study of polymorphic systems needs cooperative advice from the different techniques that are able to detect polymorphic differences. Within the sulfa-drugs I have been mostly concentrating on sulfanilamide, studying (^13)C and (^15)N solid state NMR spectra of the different polymorphs. The NMR parameters that have been most interesting to study, have been the relaxation times that have revealed complicated motion of the molecule despite it being a small molecule. In order to obtain detailed information from (^15)N spectra it has been necessary to enrich the samples and this has enabled a study of the shielding tensors of the nitrogens in the molecule. (^13)C spectra were also recorded of systems studied sulfathiazole solvates that proved to show some of the same solid state effects in the NMR spectra as sulfanilamide. Shielding calculations have proved to be still limited in order to obtain reliable information on the shielding of both and (^13)C (^15)N nuclei but considering hydrogen-bonded molecules, as opposed to isolated molecules, seemed to have improved the calculations quite a lot, so that some idea of intermolecular effects could be deducted. Exact positions of the hydrogen has proved to be essential as well in order to improve the calculations. Finally a case study for the REDOR pulse sequence has been carried out. Different attempts to understand the effects influencing this particular experiment have been carried out on 20% and 99% doubly enriched glycine, as well as on a particular sample, doubly enriched BRL55834, but the internuclear distances measured with this technique still displayed some uncertainties that made results not thoroughly reliable.

Essa pesquisa teve como objetivo principal avaliar o desempenho de um reator de leito estruturado e fluxo contínuo, sob diferentes condições operacionais como aeração intermitente e recirculação do efluente, na remoção biológica de carbono e nitrogênio de uma água residuária sintética. Foi utilizado um reator vertical, construído em acrílico, com um volume total de 11,6 L e um volume útil de 6,1 L. O meio suporte utilizado para fixação dos microrganismos foi espuma de poliuretano na forma de cilindros dispostos verticalmente suportados por hastes, presos nas extremidades. A razão de recirculação utilizada durante todo o experimento foi igual a 5. Os períodos adotados de aeração e não aeração foram de 2 horas e 1 hora, respectivamente. Estabelecidos a vazão de recirculação e os períodos de aeração e não aeração, estudou-se o efeito da variação do TDH na eficiência de remoção de \'N\'-total e DQO. Como resultado, observou-se que a melhor condição operacional foi com TDH de 12 horas, que apresentou eficiência de remoção de \'N\'-total de 82% e remoção de DQO de 89%. O sistema mostrou-se estável ao ser operado nessas condições, apresentando pouca variação nos resultados. Por outro lado, quando o sistema foi operado com TDH de 8 horas e 10 horas, houve queda nas eficiências de remoção de \'N\'-total para valores de 49% e 45% respectivamente. Com relação à remoção de DQO, as eficiências com TDH de 8 horas e 10 horas foram de 85% e 88% respectivamente, indicando uma boa remoção de matéria orgânica mesmo com TDH menor. Não houve presença significativa de biomassa no efluente, indicando que a biomassa permaneceu fortemente aderida ao meio suporte. Foram realizados ensaios cinéticos para determinação das velocidades de nitrificação e desnitrificação da biomassa do reator operando em sua melhor condição operacional. Por meio e perfis temporais em reatores em batelada, obteve-se uma velocidade de nitrificação via \'N\'-amoniacal de 1,43 mg\'N\'/gSSV.h. As velocidades de nitrificação via \'N\'-nitrito foram 1,87 mg\'N\'/gSSV.h e 1,3 mg\'N\'/gSSV.h. Na desnitrificação de \'N\'-nitrato à \'N\'-nitrito, foram obtidas velocidades de 3,4 mg\'N\'/gSSV.h e 4,0 mg\'N\'/gSSV.h. Para a desnitrificação de \'N\'-nitrito a \'N IND.2\', as velocidades obtidas foram 2,3 mg\'N\'/gSSV.h e 2,9 mg\'N\'/gSSV.h. / This research aimed at evaluating the performance of a structured bed reactor continuously fed, operated with intermittent aeration and effluent recirculation, in the biological removal of carbon and nitrogen from a synthetic effluent. A vertical reactor was built in acrylic, with a total volume of 11.6 L and a working volume of 6.1 L. Polyurethane foam cylinders supported by sticks vertically disposed were used for biomass attachment. The recirculation flow rate was 5. Aerated and non-aerated periods ware 2 hours and 1 hour, respectively. Once established the recirculation flow and the length of aerated and non-aerated period, the study of effect of the hydraulic retention time (HRT) on the removal efficiencies of Total-\'N\' and COD was started. The best operating condition was achieved with HDT of 12 hours, with removal efficiency of Total-\'N\' and COD removal of 82% of 89% respectively. Under such condition, the system exhibited high stability with little variation of the monitoring parameters. On the other hand, when the system was operated with HDT of 8 hours and 10 hours, there was a decrease in removal efficiencies of Total-\'N\', to 49% and 45% respectively. Regarding COD removal, the efficiencies at HDT of 8 hours and 10 hours were 85% and 88% respectively, indicating that organic matter removal efficiency is not limited in such range of HDT. The low concentration of suspended solids in the effluent indicates the biomass was firmly attached to the bed. Kinetic assays were performed to determine the rates of nitrification and denitrification in the reactor operating at its best operational condition. Temporal profiles obtained from batch reactors allowed for obtaining an ammonia oxidation rate of 1.43 mg\'N\'/gVSS.h. The nitrite oxidation rates were 1.87 mg\'N\'/gVSS.h and 1.3 mg\'N\'/gVSS.h. The reduction rates of nitrate to nitrite were 3.4 mg\'N\'/gVSS.h and 4.0 mg\'N\'/gSSV.h. The denitrification rate of nitrite to \'N IND.2\' were 2.3 mg\'N\'/gSSV.h and 2.9 mg\'N\'/gSSV.h.