Barium is a relatively abundant element in the crustal environments, Ba quantities can range from anywhere between 200ppm to 900ppm. Most common forms of Ba-minerals found in the environment are barite (BaSO4), witherite (BaCO3) and hollandite (Ba2Mn8O16). Ba is a useful element; it is used in various industries as a component in drilling fluids, in medical research and in manufacturing of various substances such as glass, ceramics, printing paper etc. However high quantity of Ba can be potentially toxic for the human body and can impair plant growth. It is therefore, important to review the terrestrial biogeochemical cycle of Ba, which is less studied and less understood than the oceanic biogeochemical cycle of Ba. Additionally, terrestrial systems face a diverse climate and are not as stable as the oceanic systems. Due to this the terrestrial biogeochemical cycle of barium is continuously changing and is more dynamic than the oceanic cycle. By studying one part of the cycle, i.e. the interaction of Ba in the atmosphere with the geosphere in the Mojave desert, NV, I propose a study to test the hypothesis that occurrence of, Ba-mineral, barite, in desert soils is mainly driven by dust flux. The proposal includes methodology for dust collection, sample analysis using XRF, XRD and SEM.EDS techniques and potential budget and timeline. Evidence supporting this claim would suggest that dust transports such minerals, affects the soil chemistry of desert soils and the interaction of various terrestrial systems.

As a unique habitat that encompasses steep environmental gradients, it is important to evaluate threats posed to the intertidal zone by rapid climate change. It is thought that intertidal ectotherms are living close to their physiological limit; therefore slight changes in temperature could result in high levels of mortality. Past studies on intertidal species measured thermal tolerance under constant temperatures, neglecting to consider the impacts of natural variation in field temperatures. I conducted a study on the barnacle, Balanus glandula, to assess if a variable thermal environment would alter thermal tolerance. Barnacles were acclimated in an intertidal mesocosm to either daily cold (maximum 20.4◦C), daily warm (maximum 26.5◦C), or variable (two days cold, two days warm) low-tide temperatures. I measured each barnacle’s critical thermal maximum (CTmax) by increasing air temperature 6◦C/hour and identifying the point at which the barnacle ceased to function. Barnacles exposed to any warm temperatures demonstrated an increased thermal tolerance, suggesting that this population of barnacles is capable of shifting their thermal maximum. Furthermore, acclimation to thermal heterogeneity raised thermal maximum, reinforcing the need for future thermal tolerance studies to incorporate biologically-relevant thermal regimes in laboratory experiments. These results demonstrate that B. glandula in the field are well-adapted for increasing air temperatures.

Flowering in Arabidopsis thalina is controlled by multiple pathways and is repressed by cold. To understand how A. thalina molecularly responds to cold stress temperatures, we subjected seedlings to different temperatures of cold stress for four days. Specifically, we conducted quantitative PCR of CONSTANS (CO) and the F-Box protein FKF1 to observe specifically how cold temperatures might affect the flowering time of a plant. We found a 16°C cold stress temperature increased both CO and FKF1 transcription when compared to a 24°C control. The increased expression of both CO and FKF1 may serve as a priming pathway that enables plants to be ready to flower at the precise moment when spring arrives.

According to optimal foraging theory, generalist predators, such as spiders, are thought to feed indiscriminately on prey according to its availability, especially when food is scarce. In contrast, generalists can display selective feeding decisions under regimes of high prey abundance, but few studies have tracked changes in prey choice on a seasonal basis under open field conditions. Additionally, adaptations to surviving winter have been largely ignored in the research of foraging behavior. To elucidate this, I monitored prey availability and collected common forest-dwelling wolf spiders for molecular gut-content analysis, in parallel for 18 months, to assess the temporal changes occurring in spider preferences of common leaf litter prey. In addition, to determine if any physiological improvements to resisting low temperature mortality were affecting spider foraging, I also collected spiders monthly to track changes in spider supercooling points. The results revealed that spiders do exhibit selective feeding throughout the year, and appear to do so in a way that diversifies their diets. Also, despite low litter temperatures putting them in severe freezing risk, cold tolerance in these spiders remained unchanged throughout the winter, which suggests opportunity for growth during this uncompetitive period is paramount to accumulating survivorship-increasing, but also mobility-decreasing, cryoprotectants.

Numerous causes have been implicated in contributing to amphibian population declines since the 1980's, with habitat modification, ultraviolet radiation (UV-B) and environmental contaminants (such as glyphosate-based herbicide) being among the most common. This study identifies the effects of a generic glyphosate-based herbicide (GLY- 4 Plus) on mortality, immune function, body condition, and morphological plasticity of larvae of the spotted salamander (Ambystoma maculatum) under conditions that reflect open and closed canopy light regimes. Larval salamander responses to glyphosate-based herbicide varied depending on UV-B conditions. In general, it appears that an open canopy (i.e. greater UV-B exposure) may confer fitness benefits. In the presence of herbicide, survival was higher in an open canopy UV-B regime and pooled open canopy survival was higher than that of closed canopy treatments. In the absence of herbicide, body condition and immune function were positively related with amount of UV-B. Finally, herbicide presence appeared to affect morphology under low UV-B conditions. UV-induced breakdown of surfactant or a complex interaction between temperature stratification and trophic relations is potentially responsible for the observed patterns in survival and body condition. However, the mechanistic underpinnings of improved immune function and morphological differences are less clear. As deforestation is likely to continue, amphibians may find themselves in ponds with increasingly open canopies. Combined with the knowledge that some amphibians can become locally adapted to UV exposure and develop pesticide tolerance, the probability of surviving exposure to this herbicide may be elevated in open canopy ponds. These results emphasize the complexity of natural systems and the importance of including multiple factors in experiments.

The study compares the total number of dwellings in Newcastle-upon-Tyne according to the 1991 Census and the local authority Housing Department. This is to assess whether the explanation of the differences at the local scale, can contribute to the understanding of Census underenumeration at the national scale. The significance of dwelling figures is established by reference to Census underenumeration, the Estimating with Confidence (EwC) project, housing need and government finance. The study also draws on literature about GIS in local government in order to highlight the need for the local analysis of dwelling figures for research and policy purposes, and to demonstrate the benefits of integrating Census and local authority data. The study describes the processes of data collection, integration and interpretation from both the Census and local authority sources. Total residential dwellings, occupied council stock and total vacant dwellings from both sources are compared and the differences are standardised. The standardised differences are then mapped (using z- scores) at the District scale and at Housing Area, Housing Neighbourhood, Ward and ED resolutions. Areas with large differences above or below the expected differences are highlighted and their characteristics are noted. The observed differences are then correlated with some of the characteristic of the areas in the form of dwelling structure, tenure, imputed residents and accommodation not used as main residence. These characteristics are then compared with those of areas with EwC non-response adjustment figures. The correlation analysis is carried out at two scales with the same resolution. This includes all the EDs in the City, then focuses on the EDs within Benwell and Scotswood Wards. This is to highlight the significant associations, specific to these Wards. Benwell and Scotswood are selected because of their patterns of vacancy differences, which are found to be in contrast to the city-wide pattern. The Census excess of vacancies in these Wards are also found to be greater than those in other Wards and greater (more than 1.4 standard deviations) than the city-wide expected average difference. The correlation analysis at the City scale finds that EDs with higher Census vacancy counts than the local authority data, share similar characteristics with EDs containing high EwC non-response adjustment figures. These are EDs with greater number of flats in residential buildings and local authority rented dwellings. In Benwell and Scotswood this pattern changes to greater number of flats in commercial buildings, converted flats and privately rented dwellings. The last stage of the study explains the differences in the selected variables using the individual property records (ED profiles). The study finds that at District (City) scale, the Census counts of total residential dwellings and occupied council stock are slightly higher than those from the local authority data. The Census vacancy figures however, are significantly less than local authority figures, mainly due to definitional differences and data collection methods used. The opposite pattern of higher Census vacancy figures is observed in Benwell and Scotswood. The reason for this is found to be due to vacant dwellings awaiting demolition, which were included in the 1991 Census vacancy figures but not in the local authority datasets. An example of how different definitions and data collection methods caused the observed differences. The study illustrates that the comparison of local authority and Census data can highlight areas with large differences (in vacant, occupied council stock or total residential dwelling counts) through data standardisation. The characteristics of these areas are found to be similar to those of areas reported as difficult to enumerate, in the national studies of Census underenumeration. The study also illustrates that these differences can be associated with Census non-response an...

Surface streams in karst landscapes are often characterized by high nutrient levels due to incomplete filtration through series of innumerable, below-ground conduits. Seasonal growth of the filamentous alga, Cladophora, is typically associated with nutrient-rich waters. This research compared macroinvertebrate food web structure between riverine reaches with contrasting underlying karst topography, nutrient levels, and Cladophora cover during summer 2012 and autumn 2013. Recent work in these reaches found a high correlation between Cladophora cover and nutrient content, particularly nitrate. Four questions were addressed during this study: 1. Do longitudinal trends in algal and consumer δ13C values relate to decreased DIC availability in larger watersheds? 2. Are trophic niche breadths narrower in more karstified reaches than in less karstified reaches due to longitudinal differences in Cladophora standing stocks? 3. Do differences in trophic-dynamic relationships between primary consumers and their food resources reflect the marked distinction in Cladophora standing stocks in two sections of the upper Green River that flow through differing levels of karstification? 4. Are consumers assimilating primarily autochthonous or allochthonous food resources? Consumers and algae became more 13C-depleted in downstream reaches, which is opposite to published data in other streams. Underlying causes for this pattern are uncertain, but one plausible cause is an increase in DIC availability downstream. Karstrelated hydrology may potentially alter or even reverse normal longitudinal gradients within in-stream producer and subsequently, consumer δ13C values. Since consumers were sampled during low-Cladophora conditions during 2013 and within a few weeks of the onset of the Cladophora bloom in 2012, stable isotopic results may be more representative of primary consumer diets during pre- Cladophora bloom periods. Although Cladophora cover was significantly higher in downstream reaches during both years, food-web structure was similar in all reaches. Consumer niche breadth was similar across reaches, and mixing model analyses suggested that primary consumers in all reaches assimilated similar amounts of Cladophora. The contribution of both autochthonous and allochthonous food resources to the assimilated diet of primary consumers appeared to be similarly important. These results suggest that allochthonous resources may be important in some midreach food webs, especially during periods of low algal growth.

This thesis examines the link between airborne flux estimates of CO$ sb2$, sensible heat, and water vapor, and surface parameters retrieved by remote sensing. Chapter 1 analyses the relationship between surface temperature and vegetation indices, obtained from the Advanced Very High Resolution Radiometer on board of NOAA-9 and -10 satellites, and fluxes of sensible heat, latent heat, and CO$ sb2$, estimated from aircraft. Linear relationships between CO$ sb2$ and the Normalized Difference Vegetation Index (NDVI) or the Simple Ratio vegetation index (SR) are found on a daily basis, but a highly nonlinear relationship appears for the seasonal variation. Latent Heat fluxes showed the poorest correlations with surface parameters. A seasonal linear relationship appeared between sensible heat and NDVI. Local extreme flux values due to the intermittency of boundary layer dynamics largely contribute to lower the correlations; such variations are the reason for the difficulties in relating fluxes obtained from single overpasses and over short distances to fixed points at the surface. This problem is further examined in Chapter 2, in which conditional sampling of airborne flux estimates is used to characterize the turbulent structures that are carrying flux, and their link to the surface. The analysis confirms that few extreme events may carry a significant fraction of the flux. Missing or hitting one of these structures may translate into very large oscillations on the flux estimate that are often not directly coupled to surface characteristics. A much clearer surface 'signature' emerges when measurements are taken within the surface layer, since the reorganization of turbulent structures that takes place with increasing height will result in a merging of the signature that came from different sources at the surface. This helps to explain some of the poor correlations obtained in Chapter 1 and reinforces the need for a better understanding of the distributions of these tu

Atmospheric inversion has recently become an important tool in estimating CO2 sinks and sources albeit that the existing inversion results are often uncertain and differ considerably in terms of the spatiotemporal variations of the inverted carbon flux. More measurements combined with terrestrial ecosystem information are expected to improve the estimates of global surface carbon fluxes which are used to understand the relationships between variabilities of the terrestrial carbon cycle and anomalies of climatic factors. Inversions using more observations have often been hampered by the intense diurnal variations of CO2 concentrations at continental sites. Diurnal variations of the surface flux are included with atmospheric boundary dynamics in order to improve the atmospheric inversion accuracy. Modeling experiments conducted in this study show that inverse estimates of the carbon flux are more sensitive to the variation of the atmospheric boundary layer dynamics than to the diurnal variation in the surface flux. It is however generally better to consider both diurnal variations in the inversion than to consider only either of them. Forest carbon dynamics is closely related to stand age. This useful terrestrial ecosystem information has been used as an additional constraint to the atmospheric inversion. The inverse estimates with this constraint over North America exhibit an improved correlation with carbon sink estimates derived from eddy-covariance measurements and remotely-sensed data, indicating that the use of age information can improve the accuracy of atmospheric inversions. Terrestrial carbon uptake is found mainly in northern land, and a strong flux density is revealed in southeastern North America in an improved multi-year inversion from 2002 to 2007. The global interannual variability of the flux is dominated by terrestrial ecosystems. The interannual variabilities of regional terrestrial carbon cycles could be mostly explained by monthly anomalies of climatic conditions or short-time extreme meteorological events. Monthly anomalies of the inverted fluxes have been further analyzed against the monthly anomalies of temperature and precipitation to quantitatively assess the responses of the global terrestrial carbon cycle to climatic variabilities and to determine the dominant mechanisms controlling the variations of terrestrial carbon exchange.

Atmospheric inversion has recently become an important tool in estimating CO2 sinks and sources albeit that the existing inversion results are often uncertain and differ considerably in terms of the spatiotemporal variations of the inverted carbon flux. More measurements combined with terrestrial ecosystem information are expected to improve the estimates of global surface carbon fluxes which are used to understand the relationships between variabilities of the terrestrial carbon cycle and anomalies of climatic factors. Inversions using more observations have often been hampered by the intense diurnal variations of CO2 concentrations at continental sites. Diurnal variations of the surface flux are included with atmospheric boundary dynamics in order to improve the atmospheric inversion accuracy. Modeling experiments conducted in this study show that inverse estimates of the carbon flux are more sensitive to the variation of the atmospheric boundary layer dynamics than to the diurnal variation in the surface flux. It is however generally better to consider both diurnal variations in the inversion than to consider only either of them. Forest carbon dynamics is closely related to stand age. This useful terrestrial ecosystem information has been used as an additional constraint to the atmospheric inversion. The inverse estimates with this constraint over North America exhibit an improved correlation with carbon sink estimates derived from eddy-covariance measurements and remotely-sensed data, indicating that the use of age information can improve the accuracy of atmospheric inversions. Terrestrial carbon uptake is found mainly in northern land, and a strong flux density is revealed in southeastern North America in an improved multi-year inversion from 2002 to 2007. The global interannual variability of the flux is dominated by terrestrial ecosystems. The interannual variabilities of regional terrestrial carbon cycles could be mostly explained by monthly anomalies of climatic conditions or short-time extreme meteorological events. Monthly anomalies of the inverted fluxes have been further analyzed against the monthly anomalies of temperature and precipitation to quantitatively assess the responses of the global terrestrial carbon cycle to climatic variabilities and to determine the dominant mechanisms controlling the variations of terrestrial carbon exchange.