994 resultados para Land-bridge island


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Surface energy processes has an essential role in urban weather, climate and hydrosphere cycles, as well in urban heat redistribution. The research was undertaken to analyze the potential of Landsat and MODIS data in retrieving biophysical parameters in estimating land surface temperature & heat fluxes diurnally in summer and winter seasons of years 2000 and 2010 and understanding its effect on anthropogenic heat disturbance over Delhi and surrounding region. Results show that during years 2000-2010, settlement and industrial area increased from 5.66 to 11.74% and 4.92 to 11.87% respectively which in turn has direct effect on land surface temperature (LST) and heat fluxes including anthropogenic heat flux. Based on the energy balance model for land surface, a method to estimate the increase in anthropogenic heat flux (Has) has been proposed. The settlement and industrial areas has higher amounts of energy consumed and has high values of Has in all seasons. The comparison of satellite derived LST with that of field measured values show that Landsat estimated values are in close agreement within error of 2 degrees C than MODIS with an error of 3 degrees C. It was observed that, during 2000 and 2010, the average change in surface temperature using Landsat over settlement & industrial areas of both seasons is 1.4 degrees C & for MODIS data is 3.7 degrees C. The seasonal average change in anthropogenic heat flux (Has) estimated using Landsat & MODIS is up by around 38 W/m(2) and 62 W/m(2) respectively while higher change is observed over settlement and concrete structures. The study reveals that the dynamic range of Has values has increased in the 10 year period due to the strong anthropogenic influence over the area. The study showed that anthropogenic heat flux is an indicator of the strength of urban heat island effect, and can be used to quantify the magnitude of the urban heat island effect. (C) 2013 Elsevier Ltd. All rights reserved.

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Diking and holding water on salt marshes ("impounding" the marsh) is a management technique used on Merritt Island National Wildlife Refuge (MINWR) and elsewhere in the Southeast to: a) prevent the reproduction of saltmarsh mosquitos, and b) attract wintertering waterfowl and other marsh, shore, and wading birds. Because of concern that diking and holding water may interfere with the production of estuarine fish and shellfish, impoundment managers are being asked to consider altering management protocol to reduce or eliminate any such negative influence. How to change protocol and preserve effective mosquito control and wildlife management is a decision of great complexity because: a) the relationships between estuarine organisms and the fringing salt marshes at the land-water interface are complex, and b) impounded marshes are currently good habitat for a variety of species of fish and wildlife. Most data collection by scientists and managers in the area has not been focused on this particular problem. Furthermore, collection of needed data may not be possible before changes in protocol are demanded. Therefore, the purpose of this document is two-fold: 1) to suggest management alternatives, given existing information, and 2) to help identify research needs that have a high probability of leading to improved simultaneous management of mosquitos, waterfowl, other wildlife, freshwater fish, and estuarine fish and shellfish on the marshland of the Merritt Island National Wildlife Refuge. (92 page document)

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The aim of this study was to develop a methodology, based on satellite remote sensing, to estimate the vegetation Start of Season (SOS) across the whole island of Ireland on an annual basis. This growing body of research is known as Land Surface Phenology (LSP) monitoring. The SOS was estimated for each year from a 7-year time series of 10-day composited, 1.2 km reduced resolution MERIS Global Vegetation Index (MGVI) data from 2003 to 2009, using the time series analysis software, TIMESAT. The selection of a 10-day composite period was guided by in-situ observations of leaf unfolding and cloud cover at representative point locations on the island. The MGVI time series was smoothed and the SOS metric extracted at a point corresponding to 20% of the seasonal MGVI amplitude. The SOS metric was extracted on a per pixel basis and gridded for national scale coverage. There were consistent spatial patterns in the SOS grids which were replicated on an annual basis and were qualitatively linked to variation in landcover. Analysis revealed that three statistically separable groups of CORINE Land Cover (CLC) classes could be derived from differences in the SOS, namely agricultural and forest land cover types, peat bogs, and natural and semi-natural vegetation types. These groups demonstrated that managed vegetation, e.g. pastures has a significantly earlier SOS than in unmanaged vegetation e.g. natural grasslands. There was also interannual spatio-temporal variability in the SOS. Such variability was highlighted in a series of anomaly grids showing variation from the 7-year mean SOS. An initial climate analysis indicated that an anomalously cold winter and spring in 2005/2006, linked to a negative North Atlantic Oscillation index value, delayed the 2006 SOS countrywide, while in other years the SOS anomalies showed more complex variation. A correlation study using air temperature as a climate variable revealed the spatial complexity of the air temperature-SOS relationship across the Republic of Ireland as the timing of maximum correlation varied from November to April depending on location. The SOS was found to occur earlier due to warmer winters in the Southeast while it was later with warmer winters in the Northwest. The inverse pattern emerged in the spatial patterns of the spring correlates. This contrasting pattern would appear to be linked to vegetation management as arable cropping is typically practiced in the southeast while there is mixed agriculture and mostly pastures to the west. Therefore, land use as well as air temperature appears to be an important determinant of national scale patterns in the SOS. The TIMESAT tool formed a crucial component of the estimation of SOS across the country in all seven years as it minimised the negative impact of noise and data dropouts in the MGVI time series by applying a smoothing algorithm. The extracted SOS metric was sensitive to temporal and spatial variation in land surface vegetation seasonality while the spatial patterns in the gridded SOS estimates aligned with those in landcover type. The methodology can be extended for a longer time series of FAPAR as MERIS will be replaced by the ESA Sentinel mission in 2013, while the availability of full resolution (300m) MERIS FAPAR and equivalent sensor products holds the possibility of monitoring finer scale seasonality variation. This study has shown the utility of the SOS metric as an indicator of spatiotemporal variability in vegetation phenology, as well as a correlate of other environmental variables such as air temperature. However, the satellite-based method is not seen as a replacement of ground-based observations, but rather as a complementary approach to studying vegetation phenology at the national scale. In future, the method can be extended to extract other metrics of the seasonal cycle in order to gain a more comprehensive view of seasonal vegetation development.

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Although soil algae are among the main primary producers in most terrestrial ecosystems of continental Antarctica, there are very few quantitative studies on their relative proportion in the main algal groups and on how their distribution is affected by biotic and abiotic factors. Such knowledge is essential for understanding the functioning of Antarctic terrestrial ecosystems. We therefore analyzed biological soil crusts from northern Victoria Land to determine their pH, electrical conductivity (EC) water content (W), total and organic C (TC and TOC) and total N (TN) contents, and the presence and abundance of photosynthetic pigments. In particular, the latter were tested as proxies for biomass and coarse-resolution community structure. Soil samples were collected from five sites with known soil algal communities and the distribution of pigments was shown to reflect differences in the relative proportions of Chlorophyta, Cyanophyta and Bacillariophyta in these sites. Multivariate and univariate models strongly indicated that almost all soil variables (EC, W, TOC and TN) were important environmental correlates of pigment distribution. However, a significant amount of variation is independent of these soil variables and may be ascribed to local variability such as changes in microclimate at varying spatial and temporal scales. There are at least five possible sources of local variation: pigment preservation, temporal variations in water availability, temporal and spatial interactions among environmental and biological components, the local-scale patchiness of organism distribution, and biotic interactions. (C) 2009 Elsevier Ltd. All rights reserved.

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Concentrations of major ions, silicate and nutrients (total N and P) were measured in samples of surface water from 28 lakes in ice-free areas of northern Victoria Land (East Antarctica). Sixteen lakes were sampled during austral summers 2001/02, 2003/04, 2004/05 and 2005/06 to assess temporal variation in water chemistry. Although samples showed a wide range in ion concentrations, their composition mainly reflected that of seawater. In general, as the distance from the sea increased, the input of elements from the marine environment (through aerosols and seabirds) decreased and there was an increase in nitrate and sulfate concentrations. Antarctic lakes lack outflows and during the austral summer the melting and/or ablation of ice cover, water evaporation and leaching processes in dry soils determine a progressive increase in water ion concentrations. During the five-year monitoring survey, no statistically significant variation in the water chemistry were detected, except for a slight (hardly significant) increase in TN concentrations. However, Canonical Correspondence Analysis (CCA) indicated that other factors besides distance from the sea, the presence of nesting seabirds, the sampling time and percentage of ice cover affect the composition of water in Antarctic cold desert environments.

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This study aimed to: (1) assess differences between two quantitative sampling methods of soil microarthropods (visual census vs. stone washing) in ice-free areas located along a latitudinal gradient (from 72 degrees 37'S to 74 degrees 42'S) in northern Victoria Land (Antarctica); (2) furnish preliminary results on the abundance and diversity of mites and springtails in the studied areas. Visual census yielded reliable density estimates for adult collembolans and larger prostigmatic mites but did not detect small species. The study updates the distribution of several mites, including the southernmost record of an Oribatida species at global scale. Species composition was correlated with latitude but the uneven abundance distribution and local high beta-diversity probably reflect habitat fragmentation and population isolation. Under this circumstance nested sampling design should be usefully employed. Priorities and suitable methods for studying terrestrial microarthropod communities in continental Antarctica are discussed.

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Natural ecosystems are increasingly exposed to multiple anthropogenic stressors, including land-use change, deforestation, agricultural intensification, and urbanisation, all of which have led to widespread habitat fragmentation, which is also likely to be amplified further by predicted climate change. The potential interactive effects of these different stressors cannot be determined by studying each in isolation, although such synergies have been largely ignored in ecological field studies to date. Here, we use a model system of naturally fragmented islands in a braided river network, which is exposed to periodic inundation, to investigate the interactive effects of habitat isolation and flood disturbance. Food web structure was similar across the islands during periods of hydrological stability, but several key properties were altered in the aftermath of flood disturbance, based on distance of the islands from the regional source pool of species: taxon richness and mean food chain length declined with habitat isolation after flooding, while the proportion of basal species increased. Greater species turnover through time reflected the slower process of re-colonisation on the more distant islands following disturbance. Increased variability of several food web properties over a 1-year period highlighted the reduced temporal stability of isolated habitat fragments. Many of these effects reflected the differential successes of predator and prey species at re-colonising the islands: even though larger, more mobile consumers may reach the more distant islands first, they cannot establish populations until the lower trophic levels have successfully reassembled. These results highlight the susceptibility of fragmented ecosystems to environmental perturbations. © 2013 Elsevier Ltd.

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This paper presents findings based on a palynological investigation of artificially accreting (plaggen) soils from the settlement of Village Bay, Hirta, in the St Kilda archipelago, which was perhaps the most distant and inhospitable outpost of sustained human habitation in the British Isles. The soils were developed principally through the addition of turf ash and seabird waste, although some ash may have been derived from upland peats. It is assumed that the woodland pollen signal (much lower in the soils than in an upland peat site nearby) represents off-island sources. Corylus avellana-type pollen (frequent in upland sites), along with Potentilla-type, may provide markers in the Village Bay profiles for the addition of ashed hillside turf, and possibly peat, to the plaggen soils. Cereal-type pollen is well represented through the profiles and is often strongly associated with the record for Chrysanthemum segetum (corn marigold), a frequent indicator of arable land. The Brassicaceae signal may partly reflect the cultivation of cabbages; Chelidonium majus (greater celandine) may have been grown for medicinal use. Soil mixing has rendered radiocarbon dating meaningless at this site, but the establishment of a change in cultivation regime before AD 1830 may have been identified from the patterns of pollen concentration and preservation in the profiles. © 2008 Elsevier B.V. All rights reserved.

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Bridge weigh-in-motion (B-WIM), a system that uses strain sensors to calculate the weights of trucks passing on bridges overhead, requires accurate axle location and speed information for effective performance. The success of a B-WIM system is dependent upon the accuracy of the axle detection method. It is widely recognised that any form of axle detector on the road surface is not ideal for B-WIM applications as it can cause disruption to the traffic (Ojio & Yamada 2002; Zhao et al. 2005; Chatterjee et al. 2006). Sensors under the bridge, that is Nothing-on-Road (NOR) B-WIM, can perform axle detection via data acquisition systems which can detect a peak in strain as the axle passes. The method is often successful, although not all bridges are suitable for NOR B-WIM due to limitations of the system. Significant research has been carried out to further develop the method and the NOR algorithms, but beam-and-slab bridges with deep beams still present a challenge. With these bridges, the slabs are used for axle detection, but peaks in the slab strains are sensitive to the transverse position of wheels on the beam. This next generation B-WIM research project extends the current B-WIM algorithm to the problem of axle detection and safety, thus overcoming the existing limitations in current state-of–the-art technology. Finite Element Analysis was used to determine the critical locations for axle detecting sensors and the findings were then tested in the field. In this paper, alternative strategies for axle detection were determined using Finite Element analysis and the findings were then tested in the field. The site selected for testing was in Loughbrickland, Northern Ireland, along the A1 corridor connecting the two cities of Belfast and Dublin. The structure is on a central route through the island of Ireland and has a high traffic volume which made it an optimum location for the study. Another huge benefit of the chosen location was its close proximity to a nearby self-operated weigh station. To determine the accuracy of the proposed B-WIM system and develop a knowledge base of the traffic load on the structure, a pavement WIM system was also installed on the northbound lane on the approach to the structure. The bridge structure selected for this B-WIM research comprised of 27 pre-cast prestressed concrete Y4-beams, and a cast in-situ concrete deck. The structure, a newly constructed integral bridge, spans 19 m and has an angle of skew of 22.7°.

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Dissertação de Mestrado em Ambiente, Saúde e Segurança.

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This thesis explores the importance of literary New York City in the urban narratives of Edith Wharton and Anzia Yezierska. It specifically looks at the Empire City of the Progressive Period when the concept of the city was not only a new theme but also very much a typical American one which was as central to the American experience as had been the Western frontier. It could be argued, in fact, that the American city had become the new frontier where modern experiences like urbanization, industrialization, immigration, and also women's emancipation and suffrage, caused all kinds of sensations on the human scale from smoothly lived assimilation and acculturation to deeply felt alienation because of the constantly shifting urban landscape. The developing urban space made possible the emergence of new female literary protagonists like the working girl, the reformer, the prostitute, and the upper class lady dedicating her life to 'conspicuous consumption'. Industrialization opened up city space to female exploration: on the one hand, upper and middle class ladies ventured out of the home because of the many novel urban possibilities, and on the other, lower class and immigrant girls also left their domestic sphere to look for paid jobs outside the home. New York City at the time was not only considered the epicenter of the world at large, it was also a city of great extremes. Everything was constantly in flux: small brownstones made way for ever taller skyscrapers and huge waves of immigrants from Europe pushed native New Yorkers further uptown on the island, adding to the crowdedness and intensity of the urban experience. The city became a polarized urban space with Fifth Avenue representing one end of the spectrum and the Lower East Side the other. Questions of space and the urban home greatly mattered. It has been pointed out that the city setting functions as an ideal means for the display of human nature as well as social processes. Narrative representations of urban space, therefore, provide a similar canvas for a protagonist's journey and development. From widely diverging vantage points both Edith Wharton and Anzia Yezierska thus create a polarized city where domesticity is a primal concern. Looking at all of their New York narratives by close readings of exterior and interior city representations, this thesis shows how urban space greatly affects questions of identity, assimilation, and alienation in literary protagonists who cannot escape the influence of their respective urban settings. Edith Wharton's upper class "millionaire" heroines are framed and contained by the city interiors of "old" New York, making it impossible for them to truly participate in the urban landscape in order to develop outside of their 'Gilt Cages'. On the other side are Anzia Yezierska's struggling "immigrant" protagonists who, against all odds, never give up in their urban context of streets, rooftops, and stoops. Their New York City, while always challenging and perpetually changing, at least allows them perspectives of hope for a 'Promised Land' in the making. Central for both urban narrative approaches is the quest for a home as an architectural structure, a spiritual resting place, and a locus for identity forming. But just as the actual city embraces change, urban protagonists must embrace change also if they desire to find fulfillment and success. That this turns out to be much easier for Anzia Yezierska's driven immigrants rather than for Edith Wharton's well established native New Yorkers is a surprising conclusion to this urban theme.

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Survey map and description of the land belonging to the Welland Canal Company at Dunnville. Created by The Welland Canal Company. Included is a written description of the land along with a drawing of the land. There are two seperate surveys done for the lands: Survey #1 (Pp. 148-149) noteable features include; the Grand River, the original boundry of the Grand River, marsh overflow, marsh, feeder river, bridge, Broad street, Lock street, Main street, embankment, dam (600 ft.), lines between lots, reserve for the ships yard, reserve for lock and dry dock, lands occupied by the canal and towpath to guard gate. The land totals 9 acres, and 3 roads, including the street. Survey #2 (Pp. 150-151) completed by George Keefer noteable features include; embankment, marsh overflow, original channel of the Grand River, salt spring, bridges, wier, proposed waste wier, Van Riper's home, proposed bridge, sulphur spring, road, Sulphur Creek, division between lots 12-17. The land totals 27 acres, and 2 perches. Surveyors notes can be seen in pencil and red ink on the survey.See also Pp. 148-151

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Survey map of the lands of the Welland Canal Company in Thorold. Created by The Welland Canal Company. Noteable features include; Company's land, reservoir, channel of canal, bridge, Pine street, Mullen street, lot divisions. The plan is titled "Plan of Lands belonging to the Welland Canal Company being the West half of lot no. 29 and the East half of lot no.30 in the township of Thorold, adjoining Marlats Reservoir laid out in town lots, November 24th, 1834". Surveyor notes are seen in pencil on the map.

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In 1846, the governments of Upper Canada and the State of New York initiated the creation of two companies that would be authorized to build a bridge over the Niagara River. The bridge was to be owned by both companies, respectively known as the Niagara Falls Suspension Bridge Company (Canadian) and the International Bridge Company (American). A suspension bridge was completed in 1848. This bridge was later replaced by a second suspension bridge that accommodated railways, built in 1853-54. However, the increasing weight of trains made it necessary for the bridge to be redesigned, and a third bridge was completed in 1886. Eventually, this bridge was replaced by a steel arch bridge, which was completed in 1897.