When considering pathways of contaminants to pristine areas, the focus has been largely on atmospheric and oceanic transfer. In this study, sediment cores were used to study a far less investigated but very effective pathway of persistent organic pollutants (POPs) to pristine ecosystems: the biotransport by migrating sockeye salmon (Oncorhynchus nerka). To quantify the importance of salmon as a biotransporter of contaminants, surface sediments of lakes in Alaska and British Columbia spanning a wide gradient of salmon returns (0--40,000 salmon per km2) were analyzed. Regressions of contaminant concentrations in the surface sediments with the number of returning salmon revealed a very strong, positive relationship. Especially for the lakes that received high numbers of spawners, sockeye salmon were found to be a more important source of PCBs (Polychorinated biphenyls) than the atmosphere. Furthermore, the quality of the relationship of PCB concentration with sockeye salmon spawners was found to be best for PCB congeners that are most abundant in sockeye salmon muscle tissue. Down-core profiles were analyzed to examine if the relationship between contaminant concentrations and sockeye salmon numbers can also be found historically within a lake. To investigate this question, contaminant concentrations in the 210Pb dated sediments were compared to historical sockeye salmon counts provided by authorities in Alaska and British Columbia. The results indicate that although it is possible to find the relationship between sockeye salmon spawners and contaminant concentration in down-core profiles, it is influenced by numerous factors. Such factors can arise from contaminant patterns that result from sources other than salmon, or simply very low sedimentation rates, which lead to very low resolutions in the down-core profiles.

Mercury (Hg) is a contaminant of global concern due to its toxicity to humans and other organisms. Methylmercury (MeHg) is the most hazardous form of mercury commonly found in the environment, as it bioaccumulates in aquatic food webs. Its production has been linked with microbial sulfate reduction in soils and sediments. Mine tailings cover vast land areas and release acidity and toxic metals, including Hg, to the environment. Sulfate-reducing bacteria (SRB) are active in mine tailings, indicating the potential for MeHg formation. This study investigated MeHg levels in mine tailings and the chemical and microbiological factors that might lead to significant MeHg contamination. Acidic base-metal tailings from northern Ontario were examined because they host active SRB but Hg and MeHg concentrations were unknown. Gold mine tailings from Nova Scotia were studied because Hg amalgamation was used there around 1860-1940, leaving Hg-rich tailings of unknown MeHg content and microbiology. MeHg accumulated in organic material in both environments. Acidic tailings contained negligible levels of MeHg, except for the Kidd Metsite tailings, which featured ≤ 12 nmol kg-1 MeHg in bulk tailings and 88 pM MeHg in porewaters, corresponding to a zone of sulfate reduction in the surficial layer (pH 3.7). Gold mine tailings featured a wide range of both HgT (0.2 - 53.5 mumol kg-1) and MeHg (< detection limit - 56.4 nmol kg-1). HgT levels decreased with distance from the stamp mills where ore was pulverized and treated with Hg. MeHg was influenced by multiple factors including HgT concentration, hydrological conditions, redox conditions, and demethylation. Seasonal fluctuations in MeHg were observed in one bog-type gold tailings dump. Analysis of DNA from MeHg-contaminated tailings and cultures detected Gram-positive (Firmicutes) and -negative (Deltaproteobacteria ) SRB in both types of tailings. A Deltaproteobacteria related sequence from the Kidd Metsite was unrelated to cultured lineages but 98-99% related to sequences detected in acid mine drainage elsewhere. This organism may be an important contributor to MeHg levels in acidic situations. DNA from gold tailings and cultures revealed a highly biodiverse bacterial community that included at least five Deltaproteobacteria spp. and sequences related to Hg-resistant genera.

Temporal and spatial investigations of seven ecosystems in the St. Lawrence River (the 'Main Channel', a creek, a wetland and embayments) near the city of Cornwall, Ontario revealed more intense biogeochemical activity in near-shore ecosystems. The resulting gradients between near-shore ecosystems and the 'Main Channel' exist despite the Great Lakes' strong buffering effect, which is reflected in the well mixed water masses of the 'Main Channel', with consistent average d 18OH2O and d DH2O values of -6.9 and -50‰ VSMOW, respectively. These isotopic compositions also reflect lake-surface evaporation. The evaporated water is then added to atmospheric vapor and produces a deuterium excess of 11.8 +/- 1.4‰ in local rain at Cornwall that indicates admixture of evaporated Great Lakes water to the local precipitation. Precipitation over the Great Lakes catchment area contributes 3.9% of Mg2+ and 31.2% of SO42- to the major ion flux of the `Main Channel', with other major elements (Ca 2+, Na+, K+, Cl-, SiO 2) falling between these two end-members. The pCO2 of waters ranges from values close to atmospheric equilibrium, 358 ppmV in the 'Main Channel', to as high as ∼5450 ppmV in near-shore ecosystems indicating their higher groundwater influx and more active decomposition of organic matter. This gradient is also manifest in isotopic compositions of dissolved inorganic carbon, with d 13CDIC values ranging from +2.2 to -13.7‰ VPDB for the 'Main Channel' and near-shore ecosystems, respectively. Photosynthesis and detrital inputs are both significant contributors to the POC pool in the isolated embayments. The former dominates during warm seasons, with POC concentrations up to 2663 m g/L. Near-shore ecosystems have a wide range of d 13CPOC values (-31.5 to -16.3‰), but this variability is not reflected in the 'Main Channel.' The carbon cycle studies are the most essential part of this work and outline three major ecosystems for the St. Lawrence River: (1) The 'Main Channel' and related ecosystems that are dominated by the Great Lakes and exchange processes with the atmosphere; (2) nearshore ecosystems (creeks and wetlands) that are dominated by groundwater and decomposition of organic matter; (3) isolated embayments that, during the warm season, also have a strong photosynthetic component. The latter two types of ecosystems are the most active in carbon recycling, indicating their importance in terms of net primary productivity. They also mark the locations with the highest vulnerability to anthropogenic influences. (Abstract shortened by UMI.)

The non-timber forest products (NTFPs) sector in Nepal is being promoted with the concept of sustainable management as articulated by the Convention on Biological Diversity. To promote and regulate this sector, Nepal adopted the Herbs and NTFP Development Policy in 2004. The goal of this thesis was to assess the effectiveness of this policy along with other forestry and natural resource policies in Nepal concerning the conservation and sustainable use of NTFPs. I conducted open-ended semi-structured interviews with 28 key informants in summer 2006 in Nepal where I also collected relevant documents and publications. I did qualitative analysis of data obtained from interviews and document review. The research found many important issues that need to be addressed to promote the NTFP sector as envisioned by the Government of Nepal. The findings of this research will help to further implement the policy and promote the NTFP sector through sustainable management practices.

Tributyltin (TBT) and its degradation products dibutyltin (DBT) and monobutyltin (MBT) have been quantitatively analyzed in environmental water samples using gas chromatography with flame photometric detection and gas chromatography/mass spectrometry (GC/MS). The butyltins were extracted from environmental samples with hexane/0.2% tropolone and derivatized with hexyl magnesium bromide to form hexylbutyltins. Full scanning GC/MS was used for confirmation of peak identifications and quantification was done by selective ion monitoring (methane chemical ionization) at m/z 319 (TBT) and m/z 347 (DBT, MBT and tripentyltin, the internal standard). Calibration curves were linear and detection limits were less than 2 ngL&\sp{lcub}-1{rcub}&. GC/MS and GC with flame photometric detection were compared as quantification methods and were shown to give similar results at the low ngL&\sp{lcub}-1{rcub}& levels. Water samples from Southern Chesapeake Bay were analyzed for TBT in areas of high boating activity. Several sites around a marina were sampled at repeated intervals. High spatial and temporal variability was noted. Reproducible concentration gradients were apparent, with the highest TBT levels near marinas and boatyards. Equilibrium sorption of TBT was measured on selected estuarine and freshwater sediments. Isotherms from twenty-four hour sorption and desorption equilibrations were linear with sorption coefficients between 1.1 &\times& 10&\sp2& and 8.2 &\times& 10&\sp3& Lkg&\sp{lcub}-1{rcub}&. Sorption coefficients decreased with increasing salinity and varied by a factor of two over the salinity range 0-34&\perthous&. Desorption kinetics were measured and indicated an initial fast rate followed by a slower rate. Water and sediment concentrations for TBT at locations in the Chesapeake Bay system were used to calculate apparent sorption coefficients that generally agreed with laboratory measured sorption coefficients. Exceptionally high apparent sorption coefficients were found near areas of high vessel activity and may be the result of TBT paint chips in the sediment.

Since the discovery of the Gulf of Mexico, it has become an area of extensive exploration. The Gulf of Mexico harbors specific commodities that are essential in our modern economy. Oil companies provided money and technology to find and study locations for oil exploitation. With the onset of seismic data acquisition, it was possible to gain a more comprehensive understanding of the formation and structure of this unique basin that is in constant dynamic disequilibrium, and facilitates hydrocarbon leakage. The natural seepage of oil and gas to the sea floor is of interest because these “leaks” expel methane which is potentially a significant factor in the global Carbon cycle. Determining the migration pathways through the sedimentary strata to the various primary conduits at the sea floor provides a comprehensive understanding of the large scale dynamic “plumbing system” in the Gulf of Mexico. One of the objectives in this research was to quantify the rate and volume of oil and gas released from two natural seeps in lease blocks GC600 (1200 m depth) and MC118 (850 m depth). Our purpose was to determine variability in bubble size and release rates at three individual vents and to estimate how changes in pressure affect bubble release rates. Observations with autonomous video cameras (VTLC) captured the formation of individual bubbles as they were released through gas hydrate outcrops. Image processing techniques determined bubble type (oily, gaseous, and mixed: oily and gaseous), size distribution, release rate, and temporal variations (observation intervals from 3 h to 26 d). One vent at GC600 (Birthday Candles) released oily bubbles with an average diameter of 5.0 mm (std. 1.30) at a rate of 4.37 bubbles s⁻¹. A second vent at GC600 (Mega Plume) released mixed oil and gas bubbles with an average diameter of 3.9 mm (std. 1.19) at a rate of 103 bubbles s⁻¹ (std. 24.6). A third vent at MC118 (Rudyville) released gaseous bubbles with an average diameter of 3.0 mm (std. 1.99) at a rate of 127 bubbles s⁻¹ (std. 34.1). To quantify bubble release, a robust image processing technique was developed that is adaptable to the various environments found in deep-sea oil and gas vents.   Our second objective was to constrain the migration of hydrocarbons from the source rock to the sea floor. A compilation of data sets from the macro to micro scale were used to describe the overall sequence of hydrocarbon migration and discharge from ~15 kmbsf to the water column. Geochemical similarities were found by fingerprinting oil samples from reservoir, active vents and sea-surface to show migration connectivity from source to seafloor. To support the geochemical data, measurements of fluxes and the magnitude of fluid flow indicators (e.g. bacteria mats, hydrate mounds, etc.) were compiled, and we have attempted to categorize and quantify the various processes that sequester hydrocarbons. Different stages of upward hydrocarbon flow were characterized by visual and morphological tracers. Varying reflectivity values in seismic and subbottom profile data delineate salt distribution, fault position, and acoustic blanking zones. Local geomorphological features such as hydrate mounds, carbonate hardground cover, and chemosynthetic communities, suggest passive/focused fluid flow. VTLC records and acoustic targets detected by swath mapping were used to determine the number of vents in the seep zone. We used a systems approach to combine the various data sets at different scales and resolutions to quantify values for the hydrocarbon budget at GC600. Finally, our third objective was to describe the type of benthic communities that frequented the vents in our study and to determine the evolutionary stage of the seep zone. Natural seeps provide a source of energy to chemosynthetic communities in seep areas. We used the autonomous VTLC that was deployed for extended periods of time for an “uninterrupted” view of the behavior of animals within this particular seep zone. We observed a number of metazoans including ice worms burrowing in hydrate outcrops, fish feeding on thick bacteria mats, swarms of annelids, and curious eels and crabs visiting bubble streams. By analyzing the type of organisms within the seep zone, we could determine that these seeps were immature based on the community composition. More matured seeps would include more authigenic carbonate hard grounds, less focused fluid flow (bubbling) and increased abundance of mussels and possibly tube worms. Of particular interest was the sheer abundance of ice worms (~2.8 x 10⁴ in GC600) that inhabit the gas hydrate outcrops and don’t seem to have any predators. Where they go once the gas hydrate dissociates is still an open question. / A Dissertation submitted to the Department of Earth, Ocean, and Atmospheric Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester 2016. / June 3, 2016. / autonomous video time lapse camera, bubbles, Gulf of mexico, migration, Natural hydrocarbon seeps / Includes bibliographical references. / Ian R. MacDonald, Professor Directing Dissertation; Tarek Abichou, University Representative; Bill Dewar, Committee Member; Jeff Chanton, Committee Member; Michael Abrams, Committee Member.

Polybrominated diphenyl ether (PBDE) flame retardants are widely used as non-reactive additives in textiles, polyurethane foams, plastics, furnishings, and electronic products. as a result of substantial, long-term usages, PBDEs have contaminated humans, wildlife, air, water, soil, and sediment, even in remote areas. Although the North American and Asian (particularly Chinese) markets have consumed the majority of global PBDE production, knowledge about PBDE contamination is limited in these two regions. Therefore, this research aimed to investigate PBDE contamination in some Chinese and North American areas by examining the birds of prey that have been considered as sensitive monitoring species for organochlorine contamination. Particular interests were in the bioaccumulation of BDE-209, a predominant congener in Deca-BDE and the only PBDE formulation still in use worldwide. It is widely believed to have limited bioavailability. The study was primarily performed in three regions: Beijing in North China, New England and the Chesapeake Bay regions in the U.S. to our best knowledge this study is the first to examine PBDE contamination in terrestrial raptors from both North America and Asia. The results revealed (1) dissimilar PBDE congener distribution patterns between aquatic and terrestrial birds of prey, suggesting that individual congeners may be subject to differences in bioaccumulation, biomagnification or metabolism in the aquatic and terrestrial environments; (2) substantial biomagnification of PBDEs (BMF = 41.4) in the Chesapeake Bay fish-osprey egg chain; (3) an influence by diet preference and living habitat on the contamination burdens and congener profiles in the birds; (4) substantial PBDE contamination in the Chinese birds of prey, indicating elevated exposure due to extensive application of PBDEs in the city; (5) record-high BDE-209 concentrations in Chinese kestrels and U.S. peregrine falcon eggs, indicating the substantial accumulation of this congener in the terrestrial birds of prey; (6) significantly higher BDE-209 concentrations in the urban peregrine falcon eggs, indicating a greater abundance of Deca-BDE in the urban environment; (7) a rapid increase in BDE-209 concentrations in the northeastern U.S. peregrine eggs, which may have resulted from the continuing use of Deca-BDE; and (8) a potential breakdown of BDE-209 to less brominated and more bioavailable congeners. A review of studies in birds of prey worldwide clearly indicated a greater abundance of BDE-209 in the North American and Chinese birds compared to European species. This follows well the global market demand pattern of Deca-BDE, in which North America and Asia have historically consumed 44% and 41% of the world's total production, respectively. The above findings of high BDE-209 concentrations, short doubling time, and potential biodegradation in the terrestrial birds of prey, indicate the need to limit unnecessary Deca-BDE release to the environment.

Climate change poses problems for agriculture in the Global South. Smallholders in the Global South are often considered highly vulnerable to climate change as a result of their farms being located in marginal environments, their insecure land tenure and lack of technology, and their participation in unpredictable regional and world markets. Analyzing how smallholders perceive climate change and attendant risk, the factors that enable and constrain their adaptive capacity, and the social impacts of state led projects designed to mitigate the impacts of climate change may provide crucial insights for developing effective climate adaption projects and policies. This research examined smallholder perceptions of climate change and their ability to adapt to it in the Loess Plateau region of China. The study also investigated the outcomes of the introduction of a drip irrigation project designed to address water scarcity problems in Gansu, China, as well as smallholder farmer perceptions and knowledge of water saving irrigation technologies in general. Data were collected through interviews and a household survey of smallholders in the region. Smallholders were found to have low levels of perceived ability to adapt to climate change without government assistance. Further, it was found that smallholder perceptions of climate change are structured through their observations of and interactions with dynamic, networked socio-natural assemblages. The labor demands of drip irrigation technology are shown to contradict extant irrigation and livelihood practices and the social institutions that underlie them, both creating new vulnerabilities for farmers and causing system abandonment. The dissertation results suggest that adaptation interventions designed to mitigate the impacts of climate change on smallholders in the Loess Plateau region of China should be holistic and address the day-to-day problems and risks that smallholders face if the interventions are to successfully adapt smallholders to future climate change without causing unintended consequences.

The effect of reduced gravity on the balanced management of liquid, gaseous and ionic fluxes in unsaturated porous media remains a central challenge for plant-based bio-regenerative life support systems needed for long-duration space missions. This research investigated how shifting capillary and gravitational forces alter the sample-scale transport and distribution of fluids in mm-sized porous ceramic aggregates. Measurements in variably saturated media conducted on the International Space Station in microgravity ($sim1cdot10^{-3} g_{earth}$) and measurements during parabolic flight in variable gravity encompassing microgravity, terrestrial gravity and hypergravity ($sim1.8 g_{earth}$) were supported by numerical modeling based on fundamental, earth-derived soil-physical relationships. Measurements of water fluxes in rigid saturated media suggested Darcian flow unaffected by gravity. Observations of hydraulic potential and sample water content were used to estimate the primary draining and wetting water-retention characteristic (WRC). Terrestrial parameterizations of the WRC were largely unaffected by reduced gravity. However, because the WRC is hysteretic, heterogenous water-content distributions resulted within the confines of the primary draining and wetting characteristics. Ensuing distributions were fundamentally different from terrestrial observations and were stable in the absence of a significant gravity gradient. We showed that these distributions, though unexpected, could be predicted using the Richards equation. One consequence of altered water distribution could be the reduction in, and increased tortuosity of, continuous gas-filled pathways for diffusive transport compared to terrestrial estimates. Measurements of oxygen diffusion in microgravity suggested reduced diffusivities during draining. These observations, particularly for the smaller particle-sized media, were suggestive of the delayed formation of critical air-filled pathways at lower water contents. This dissertation further uses a case history of a stratified root-zone developed based on water-retention characteristics of different particle-sized media. The root-zone design provided a more uniform water-content distribution at terrestrial gravity suggested to provide more optimal conditions for root growth. Additionally, the design and testing of a novel integrated sensor for measurements of water content based on the dissipation of heat and estimation of nutrient status based on electrical resistivity are discussed. These results should provide insights into microgravity fluid distribution and transport contributing to the design and implementation of controllable plant-growth systems for use in microgravity and future planetary habitats.

Free-living Uinta ground squirrels (Spermophilus armatus) were instrumented with miniaturized ECG radio-transmitters to measure their short-term and long-term heart rate responses to social interactions. A continuous trapping and direct observation program prior to and during the study provided complete behavioral and life history information for virtually all ground squirrels on the 22-acre study area. Three broad categories of heart rate information were obtained: responses by squirrels (1) in their burrows, (2) above ground during social interactions, and (3) above ground when animals were not fighting and when conspecifics were both absent and present. Marked changes in the heart rate of ground squirrels occurred even as animals behaved in their burrows and conspecifics were absent. Some changes were caused by motor behaviors and appeared commensurate with different degrees of physical exertion. Others were evident among inactive animals and took the form of diurnal cardiac rhythms which were independent of immediate motor behavior hut nonetheless attuned to aboveground activity cycles. The heart rate of all ground squirrels increased well above burrow baselines when animals behaved aboveground. The greatest elevations occurred during social interactions which ranged from mere threat to physical combat. Combat encounters elicited responses which frequently exceeded 400 beats/minute as compared to burrow and aboveground baselines for inactive animals of 269 and 284 beats/minute , respectively. Threat interactions produced less dramatic increases, but because threat usually lasted longer, it was perhaps as stressful as combat. There were no significant differences between peak responses of dominants and subordinates, initiates and recipients of aggression, or sex and age classes. However, the duration of cardiac response was less for dominants and hence, they apparently experienced less stress than subordinates. Increases in heart rate, independent of motor behavior and immediate social interactions, were also observed as female ground squirrels roamed within and/or made occasional excurs ions outside their home ranges. These cardiac changes occurred regardless of the presence or absence of conspecifics in the vicinity. It was concluded that such cardiac acceleration represented chronic response to social interactions and was elicited by spatial factors, specifically spatial familiarity, which acted as conditioned stimuli (previously paired with combat). Such chronic responses were greatest during the initial establishment of territories by females, decreased during territoriality, and increased again following the breakdown of territoriality. So territoriality acted to reduce the magnitude of heart rate response and hence, stress among females. The mere presence of conspecifics within the immediate vicinity of an instrumented ground squirrel tended to elevate its heart rate. Therefore, even in the absence of overt social interactions, conditions of crowding also contributed towards chronic stress in the population. The effects upon heart rate with respect to an individual's sex, age, reproductive condilion, and its spatial and social relationship with neighboring ground squirrels are also discussed. Finally, the roles which social and nonsocial factors play in regulating animal numbers on the study are described.