Due to accelerated climatic warming during the past fifty years, interest and concerns have been growing about changes in the ecological integrity of shallow freshwater ponds that dominate the landscape of the Hudson Bay Lowlands (HBL). Climatic warming is altering the hydrological processes that influence the water balances in these ponds, but knowledge remains insufficient to determine the effects these changes have on ecological conditions in the ponds. To address this knowledge gap, this study examines the relations between current hydrological and limnological conditions and recently deposited sedimentary assemblages of diatoms and photosynthetic pigments in 23 shallow ponds in the HBL. The knowledge from the contemporary studies will be used to inform paleolimnological reconstructions using multiple proxies at two ponds to assess how hydroecological conditions have changed during the past several centuries in response to climatic variations. Water samples were collected three times in 2010 to explore the relations between current hydrological and limnological conditions. The climatic conditions in 2010 provided an excellent opportunity to assess the effects that continued climate warming may exert on hydrolimnological conditions in the study ponds as the warm, dry conditions during the early thaw-season (May- mid-July) followed by extremely wet conditions for the remainder of the thaw-season are likely representative of future climate scenarios. The analysis revealed that the water chemistry in the ponds evolved along one of four different ‘trajectories’ throughout the thaw-season in 2010. These seasonal patterns of limnological conditions closely aligned with similar patterns identified in a study of contemporary hydrological conditions (Light, 2011; Wolfe et al., 2011). The patterns identified in both the hydrological and limnological studies were attributed to differences among ponds in catchment characteristics and hydrological connectivity with adjacent basins. Surface sediment samples were collected in 2010 to determine if hydrolimnological conditions are reflected in the distribution of recently deposited diatom and pigment communities. It was determined that diatom community composition was most highly influenced by the availability of microhabitat in the ponds which did not appear to be controlled by hydrological conditions. Nitrogen availability was determined to be indirectly influencing diatom community composition as the nitrogen-limited conditions in the ponds favoured the proliferation of N2-fixing cyanobacterial mats that provided a large amount of epiphytic habitat in the majority of the study ponds. This resulted in the complete domination of diatom assemblages by one diatom specie that was closely associated with these algal mats in the surface sediments of most ponds. Aphanizophyll, a photosynthetic pigment representative of nitrogen-fixing cyanobacteria, was also in the highest concentration in most of the study ponds as a result of the nitrogen-limiting conditions that allowed these organisms to dominate. Ponds located in the tundra ecozone were also found to have the highest overall pigment concentration which was related to a longer growing season due to the small size of these ponds that resulted in earlier ice-off conditions. The longer growing season of ponds in the tundra ecozone may also be due to high winds that cause a decrease in snow cover, lower surface albedos and an earlier onset of the spring thaw. The paleolimnological reconstruction of two of the ponds revealed similar shifts in diatom community composition in the stratigraphic record even though patterns of past change in their basin hydrology, as explored though the analysis of the δ18OPW record archived in the aquatic cellulose contained in the pond sediments, was very different. The water balance of “Left Lake” was found to be highly influenced by increased evaporation associated with recent warming trends as it is a relatively small basin that becomes hydrologically isolated after the melt period. However, “Erin Lake” was not as susceptible to evaporation during the recent warming trend due to its larger catchment and hydrological connections to other ponds. Both of these ponds experienced marked changes in the diatom assemblages. The changes were characterized by a shift from assemblages containing both small, adnate, benthic taxa that prefer mineral grain substrates and epiphytic taxa that are associated with the cyanobacterial mats covering the pond bottoms to assemblages entirely dominated by epiphytic taxa. The shift in diatom community composition occurred ~1820 in Left Lake, but the timing cannot be determined with any degree of confidence in Erin Lake as no diatoms are observed in the sediment record during the period when the change occurred (~1550 to 1850) due to preservation issues. Analysis of fossil pigments indicates that nitrogen-fixing cyanobacteria have been important to the ecology of the ponds over the entire sediment record. However, there is a trend towards lower concentrations of pigments representative of N2-fixing cyanobacteria in the most recent sediments. The trend in cyanobacterial pigment concentrations coincides with inferred changes in nitrogen availability from the geochemical analysis of the pond sediments by Light (2011). This recent shift in nutrient status may be the result of a number of factors including the increased atmospheric deposition of anthropogenically-derived nitrogen or changes in biogeochemical cycling in the ponds.

Due to accelerated climatic warming during the past fifty years, interest and concerns have been growing about changes in the ecological integrity of shallow freshwater ponds that dominate the landscape of the Hudson Bay Lowlands (HBL). Climatic warming is altering the hydrological processes that influence the water balances in these ponds, but knowledge remains insufficient to determine the effects these changes have on ecological conditions in the ponds. To address this knowledge gap, this study examines the relations between current hydrological and limnological conditions and recently deposited sedimentary assemblages of diatoms and photosynthetic pigments in 23 shallow ponds in the HBL. The knowledge from the contemporary studies will be used to inform paleolimnological reconstructions using multiple proxies at two ponds to assess how hydroecological conditions have changed during the past several centuries in response to climatic variations. Water samples were collected three times in 2010 to explore the relations between current hydrological and limnological conditions. The climatic conditions in 2010 provided an excellent opportunity to assess the effects that continued climate warming may exert on hydrolimnological conditions in the study ponds as the warm, dry conditions during the early thaw-season (May- mid-July) followed by extremely wet conditions for the remainder of the thaw-season are likely representative of future climate scenarios. The analysis revealed that the water chemistry in the ponds evolved along one of four different ‘trajectories’ throughout the thaw-season in 2010. These seasonal patterns of limnological conditions closely aligned with similar patterns identified in a study of contemporary hydrological conditions (Light, 2011; Wolfe et al., 2011). The patterns identified in both the hydrological and limnological studies were attributed to differences among ponds in catchment characteristics and hydrological connectivity with adjacent basins. Surface sediment samples were collected in 2010 to determine if hydrolimnological conditions are reflected in the distribution of recently deposited diatom and pigment communities. It was determined that diatom community composition was most highly influenced by the availability of microhabitat in the ponds which did not appear to be controlled by hydrological conditions. Nitrogen availability was determined to be indirectly influencing diatom community composition as the nitrogen-limited conditions in the ponds favoured the proliferation of N2-fixing cyanobacterial mats that provided a large amount of epiphytic habitat in the majority of the study ponds. This resulted in the complete domination of diatom assemblages by one diatom specie that was closely associated with these algal mats in the surface sediments of most ponds. Aphanizophyll, a photosynthetic pigment representative of nitrogen-fixing cyanobacteria, was also in the highest concentration in most of the study ponds as a result of the nitrogen-limiting conditions that allowed these organisms to dominate. Ponds located in the tundra ecozone were also found to have the highest overall pigment concentration which was related to a longer growing season due to the small size of these ponds that resulted in earlier ice-off conditions. The longer growing season of ponds in the tundra ecozone may also be due to high winds that cause a decrease in snow cover, lower surface albedos and an earlier onset of the spring thaw. The paleolimnological reconstruction of two of the ponds revealed similar shifts in diatom community composition in the stratigraphic record even though patterns of past change in their basin hydrology, as explored though the analysis of the δ18OPW record archived in the aquatic cellulose contained in the pond sediments, was very different. The water balance of “Left Lake” was found to be highly influenced by increased evaporation associated with recent warming trends as it is a relatively small basin that becomes hydrologically isolated after the melt period. However, “Erin Lake” was not as susceptible to evaporation during the recent warming trend due to its larger catchment and hydrological connections to other ponds. Both of these ponds experienced marked changes in the diatom assemblages. The changes were characterized by a shift from assemblages containing both small, adnate, benthic taxa that prefer mineral grain substrates and epiphytic taxa that are associated with the cyanobacterial mats covering the pond bottoms to assemblages entirely dominated by epiphytic taxa. The shift in diatom community composition occurred ~1820 in Left Lake, but the timing cannot be determined with any degree of confidence in Erin Lake as no diatoms are observed in the sediment record during the period when the change occurred (~1550 to 1850) due to preservation issues. Analysis of fossil pigments indicates that nitrogen-fixing cyanobacteria have been important to the ecology of the ponds over the entire sediment record. However, there is a trend towards lower concentrations of pigments representative of N2-fixing cyanobacteria in the most recent sediments. The trend in cyanobacterial pigment concentrations coincides with inferred changes in nitrogen availability from the geochemical analysis of the pond sediments by Light (2011). This recent shift in nutrient status may be the result of a number of factors including the increased atmospheric deposition of anthropogenically-derived nitrogen or changes in biogeochemical cycling in the ponds.

The Hudson-James Bay Lowlands (HJBL) are composed of fens and bogs frequently intersected by rivers and punctured by bioherms (ancient reef mounds) rising from bedrock aquifer. The peatlands exist partly due to minimal vertical losses limited by the low hydraulic conductivity (K) of the Tyrrell Sea sediments and small vertical gradients between the surface and bedrock aquifers. The recent development of an open-pit mine; DeBeers Victor Diamond Mine within the HJBL requires dewatering of the regional limestone aquifer to a depth of 200 mbgs. Two major components in assessing the potential impacts of dewatering on the hydrogeological regime and the sensitive peatland ecosystem are: the characteristics and behaviour of the Tyrrell Sea aquitard, and bioherms as potential recharge enhancing features. The Victor Tyrrell Sea (VTS) deposits are clayey silt with low LL, low PI, and no smectite clay minerals. The clay fraction consists of quartz, illite, chlinochlore, and usually calcite. The deposits are normally consolidated with Cc values of 0.08-0.155 and void ratios of 0.52-0.77. The VTS deposits are grey with pockets of black graphite and frequent shells. The K rages from 6.6x10-9 to 4.7x10-8 m/s. GEO-SLOPE™ finite element modeling software was used to investigate the sensitivity of surface drainage and consolidation behaviour in regard to the range of measured VTS parameters. The behaviours were also compared to classic clay aquitard types such as Lake Agassiz and Lake Champlain. Unit thickness, K, and the K modifier function have the greatest impact on the rate and magnitude of consolidation, and vertical drainage of the surface. The K of the underlying till is extremely important because they can be a buffer between the dewatered bedrock aquifer and the VTS. The characteristics of the sediments and the flow regime surrounding three outcropping bioherms which increase vertical drainage are investigated and a conceptual model of flow is proposed. The sediments in profile around bioherms have different levels of stratification but always contain silt and sand units. The hydraulic conditions at eight nested piezometers and the stratigraphy as defined by a series of auger hole profiles was considered to develop a conceptual model. The flow regime presented is of radial flow towards the bioherms enhanced by high K sediments between the peat and bedrock becoming vertical flow when the high K sediments contact vertical channels in the rock. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2013-02-06 14:47:13.582

A dissertation presented to the graduate school of the University of Florida in partial fulfillment of the requirements for the degree of Doctor of Philosophy. 2009 / Submitted by Leonardo Martinez-Acchini (leonardo.acchini@unila.edu.br) on 2017-11-01T01:49:38Z No. of bitstreams: 1 martineza_l.pdf: 1737664 bytes, checksum: a522807aa2f99a94e70dedfdaee49734 (MD5) / Made available in DSpace on 2017-11-01T01:49:38Z (GMT). No. of bitstreams: 1 martineza_l.pdf: 1737664 bytes, checksum: a522807aa2f99a94e70dedfdaee49734 (MD5) Previous issue date: 2009 / This research is about cultural and linguistic change among western Bolivian highland and valley peasants who have been migrating to the country’s eastern lowlands in the recent years, a very widespread phenomenon in developing economies of the Andean neo-tropics today. In particular, I want to know how Quechua-speaking people from the highlands and valleys adapt to lowland culture; which ethnic traits and linguistic resources they keep, and which ones they abandon; and which strategies they utilize to ease the process of adaptation. The results indicate that highland migrants who settled in the lowland community of Cuatro Cañadas (department of Santa Cruz) speak less Quechua among themselves, and especially with their children, although they assign great importance to the maintenance of this language. Four specific cultural practices that were selected as indicators of Quechua mode of life were measured and analyzed. The results indicate that there is a substantial reduction of these practices in the lowlands. Also, inter-ethnic marriage (highlanders seeking lowlanders), thought to be an important strategy of adaptation, was found to be a preference for a reduced proportion of both the single migrant population and the married population. Therefore, migrants in Cuatro Cañadas are reducing their traditional linguistic behavior and the practice of specific cultural traditions, but their alliance patterns are still somewhat conservative. In spite of this process of acculturation, the theoretical framework used in this research argues that highland migrants do not fully own Cuatro Cañadas: they are trapped between traditional, modern and globalizing codes, and just embrace the hybrid nature of their identities, which makes them speak and behave in certain ways depending on which ethnic identity they want to activate.

No description available.

Les premiers essais agricoles dans les terres basses de la Guyane française commencent dès 1763 sur les côtes de Kourou. Ce fut le début d’une entreprise qui, sous la forme de dents de scie, va marquer l’économie de cette colonie française de l’Amérique du sud jusqu’à nos jours. Les terres noyées de la Guyane française, sont toutes localisées sur la bande côtière et correspondent à des zones humides (tourbières, mangroves, marais). Au début de la colonisation, en 1604 précisément, les Français se sont établis sur l’île de Cayenne, et ont occupés les terres hautes, situées plus à l’intérieur du continent. L’agriculture de ces terres a débuté à la même période, selon le modèle d’agriculture sur brûlis développé par les autochtones. Ce modèle traditionnel convenait à la production des denrées alimentaires pour des petits groupes. Néanmoins, au bout d’un siècle, leur rendement ne satisfaisait plus au commerce de la colonie. L’épuisement ou la faible productivité de ces terres hautes à la fin du XVIIIeme siècle, a ainsi occasionné une ruée ver les terres basses. Le développement de ces terres noyées avait déjà été entrepris par les Hollandais (Guyane hollandaise), mais ces zones humides rebutaient encore les Colons-Planteurs en Guyane française. Dès l’arrivée de V. Malouet (nouvel intendant de la colonie) vers 1778, les techniques d’assèchement et de construction de polders se développent en Guyane française sous la direction de l’ingénieur J. S. Guisan. Ce dernier essaya de faire des terres noyées, la réponse aux problèmes agricoles de la Guyane française. Mais, les différents évènements socio-politiques qui touchèrent la France à cette époque (Révolution française, abolition de l’esclavage, activités aurifères), mirent fin dès 1848 à cette entreprise. Certaines contraintes climatiques doivent également être considérées. Un siècle plus tard, vers 1950 avec le lancement du plan vert, les rizières de Mana témoignent encore de l’importance de la culture des terres basses en Guyane française. / The first agricultural trials in the lowlands of French Guyana started in AD 1763 on Kourou coasts. It was the beginning of an initiative that will mark the economy of this French colony of South America until today. The flooded lands of French Guyana are all located on the coastal strip. This area is composed of wetlands (peatlands, mangrove and swamps). At the beginning of colonisation, in AD 1604 exactly, French people established themselves on the Cayenne Island and on the uplands (mainland). The cultivation of these uplands started at the same time, adopting the slash-and-burn agriculture developed by autochthonous people. More, this agricultural model was butter suited to foodstuffs production for small groups. However, early in the century, their performance no longer satisfied trade of the colony. Depletion or low production of these uplands at the end of the XVIIIth century, caused a rush to the lowlands. The development of these low lands has already been undertaken by the Dutch (Dutch Guyana), but these wetlands were still rejected by the Colon-planters in the French Guyana. As soon as V. Malouet arrived (new intendant of the colony) ca. AD 1778, the techniques of dewatering and polder construction developed in the French Guyana under the supervision of the engineer J. S. Guisan. He tried to manage the flooded lands as an answer to agricultural problems of the French Guyana. But, several socio-political events occurred in France at this period (the French Revolution, the abolition of slavery, the gold-bearing activity) put a stop to this process in AD 1848. Climate control should also be considered. One century later, around AD 1950, Mana rice fields still testify of the importance of cultivation of lowland of French Guyana, in particular thanks to the launch of the green plan.Keys words: French Guyana

The subject of this study is attitudes towards Gaelic Scotland to be found in Lowland Scottish historiography of the late fourteenth to the late sixteenth century; the authors examined were John of Fordun, Andrew Wyntoun, Walter Bower, John Mair, Hector Boece, John Leslie and George Buchanan. In the first part of the thesis the historical works were examined with respect to the attitude of each individual author towards the Highlanders of his own time. It was found that the earlier authors - i.e. Fordun, Wyntoun, Bower and Mair - mirror anti-Highland feeling and prejudice that were widespread in their own Lowland surroundings. They further the image of the Highlander as a savage. The later authors, by contrast, look upon their Gaelic contemporaries from a humanistic, or rather, 'primitivistic', point of view: to them the Gaelic Scots with their simple way of life represent the virtuous and noble customs and traditions of the Scottish forefathers. The second part of the thesis was concerned with the historians' presentation of Gaelic kings and kingship. Special attention was paid to their understanding of the Gaelic succession law; here, a lack of comprehension could be noted among the authors, which led to a distorted presentation of the reigns and characters of a number of Gaelic kings of tenth- and eleventh-century Scotland. In this historical part, no substantial difference in presentation could be found between the earlier and the sixteenth-century authors, mainly because the latter did not carry out any historical research of their own. In the case of Fordun, Wyntoun, Bower and Mair, perceptions of Gaelic Scotland are rooted in the traditional negative attitudes of their own times and surroundings; this corresponds to a lack of understanding of aspects of the Gaelic element in Scottish history. The humanist historians, on the other hand, propose a view of Gaelic Scotland which is in opposition to the views of their own Lowland contemporaries, and which they do not back up in their presentations of Scottish history.

Rapidly changing climates in northern Canada make the western Hudson Bay region an area of high importance for paleoenvironmental studies. Long-term changes in assemblages of diatoms (microscopic algae) were analyzed from lake sediment cores from Baker Lake, Nunavut, and Lake AT01, northern Ontario, to track responses to past environmental changes. Diatom assemblages dating to 6700 years ago in AT01 were initially characterized by cold- tolerant Fragilarioid assemblages, but shifted to an assemblage dominated by large benthic species and Cymbella diluviana consistent with the timing of the Holocene Thermal Maximum after 6300 years BP. A possible drainage event in Lake AT01 may have added significant hydrologic control on the diatom assemblages. The post-industrial period is marked by the largest compositional shifts in both records. Assemblages during the 20th century are indicative of reduced ice cover and enhanced thermal stratification linked to a climate regime shift noted in Hudson Bay since the mid-1990’s.

Approximately 7000 to 8000 years ago when Hudson Bay became ice-free the Tyrrell Sea flooded the Hudson basin and deposited fine grained marine sediments overlaying the previous glacial tills. Coincident with the ablation of the ice sheet isostatic rebound occurred causing regression of the Tyrell Sea and the emergence of a flat, relatively impermeable surface that would eventually host one of the world’s largest wetlands: the Hudson Bay Lowlands. The low permeability marine sediments and low regional slope reduced recharge and runoff, respectively, so that basal tidal marshes were established, and with isostatic up lift were eventually replaced by swamp forests and then forested and non-forested bogs. Recent discovery of kimberlite (diamondiferous) pipes in an area of the lowlands has led the development of an open-pit diamond mine which requires dewatering of the regional aquifer. Dewatering is depressurizing the surrounding Silurian bedrock that underlies the marine sediments. It was hypothesized that these marine sediments would act as a confining layer, isolating the overlying peatlands from the regional bedrock aquifer. We tested this hypothesis by instrumenting a 1.5 km long transect located within the zone of the mine’s influence that crossed various bogs and fens overlying these marine sediments, and was anchored at both ends by bedrock outcrops (bioherms), which represented areas of no marine sediment. Along this transect wells and piezometers were installed within the peat profile and upper marine sediments and bedrock to determine changes in water table and hydraulic head. The exposed bedrock outcrops (bioherms) did act as local drainage nodes, however, this effect was limited to ~30 m, beyond which water tables and hydraulic heads were similar to a control site located 25 km away. However, within this 30 m zone daily losses of water by the enhanced recharge often exceeded those of evapotranspiration (~3mm/day) representing a major local loss of water to the system. It is the distance to bedrock, rather than distance to bioherm, that determines strength of recharge. In areas of thinner marine sediments the daily fluxes were similar (but less) than those in the areas directly surrounding the bioherms, despite being 100s of meters away from the bioherms. The stratigraphy surrounding the bioherms lead to complicated flow regimes with higher conductivity layers (e.g., sands) circumventing the lower permeability marine sediments which may help extend the effect of the bioherms beyond the 30 m distance. The drying peat around the bioherms, and the elevated nature of the bioherms in a flat landscape, put them at increased risk for lighting strikes and thus fires; however, very little viable fuel exists in the peatlands around the bioherms and any fires that might occur would be confined to the bioherm and not spread into the surrounding peatland. Overall, at least within the first 5 years of aquifer dewatering, seasonal weather played the dominant role in affecting the hydrology of the peatlands; a heavy snow pack and cool, wet summer can mask, or at least minimize the effects of aquifer dewatering.

Approximately 7000 to 8000 years ago when Hudson Bay became ice-free the Tyrrell Sea flooded the Hudson basin and deposited fine grained marine sediments overlaying the previous glacial tills. Coincident with the ablation of the ice sheet isostatic rebound occurred causing regression of the Tyrell Sea and the emergence of a flat, relatively impermeable surface that would eventually host one of the world’s largest wetlands: the Hudson Bay Lowlands. The low permeability marine sediments and low regional slope reduced recharge and runoff, respectively, so that basal tidal marshes were established, and with isostatic up lift were eventually replaced by swamp forests and then forested and non-forested bogs. Recent discovery of kimberlite (diamondiferous) pipes in an area of the lowlands has led the development of an open-pit diamond mine which requires dewatering of the regional aquifer. Dewatering is depressurizing the surrounding Silurian bedrock that underlies the marine sediments. It was hypothesized that these marine sediments would act as a confining layer, isolating the overlying peatlands from the regional bedrock aquifer. We tested this hypothesis by instrumenting a 1.5 km long transect located within the zone of the mine’s influence that crossed various bogs and fens overlying these marine sediments, and was anchored at both ends by bedrock outcrops (bioherms), which represented areas of no marine sediment. Along this transect wells and piezometers were installed within the peat profile and upper marine sediments and bedrock to determine changes in water table and hydraulic head. The exposed bedrock outcrops (bioherms) did act as local drainage nodes, however, this effect was limited to ~30 m, beyond which water tables and hydraulic heads were similar to a control site located 25 km away. However, within this 30 m zone daily losses of water by the enhanced recharge often exceeded those of evapotranspiration (~3mm/day) representing a major local loss of water to the system. It is the distance to bedrock, rather than distance to bioherm, that determines strength of recharge. In areas of thinner marine sediments the daily fluxes were similar (but less) than those in the areas directly surrounding the bioherms, despite being 100s of meters away from the bioherms. The stratigraphy surrounding the bioherms lead to complicated flow regimes with higher conductivity layers (e.g., sands) circumventing the lower permeability marine sediments which may help extend the effect of the bioherms beyond the 30 m distance. The drying peat around the bioherms, and the elevated nature of the bioherms in a flat landscape, put them at increased risk for lighting strikes and thus fires; however, very little viable fuel exists in the peatlands around the bioherms and any fires that might occur would be confined to the bioherm and not spread into the surrounding peatland. Overall, at least within the first 5 years of aquifer dewatering, seasonal weather played the dominant role in affecting the hydrology of the peatlands; a heavy snow pack and cool, wet summer can mask, or at least minimize the effects of aquifer dewatering.