<p> Bird migration is the regular seasonal movements between breeding and nonbreeding grounds. In general, birds that breed in the Northern Hemisphere tend to migrate northward in the spring to take advantage of increasing insect populations and lower predation pressures and fly south when food availability and weather conditions decline. Embarking on a journey that can stretch a thousand miles round trip is a dangerous and arduous undertaking. While en route migrants must stop and feed to replenish their depleted energy reserves, often in unfamiliar locations with unknown predation pressures. They also must react to weather conditions during flight and while on the ground. Additionally, areas of high quality habitats where birds can refuel efficiently and safely may be few and far between. Therefore, it's not surprising that mortality rates can be higher during migration than at any other period of the year. Behavioral decisions such as where and where to stop, how long to stay, and when to leave all involve costs and benefits with an ultimate goal to balance the costs and benefits on order to achieve a successful and efficient migration. Optimal migration theory, aims to explain how migrants balance behavioral and physiological parameters of migration that minimize total time spent on migration, total energy expended, or mortality risk. The eventual result of these optimization pressures is thought to be a gradient of behavioral strategies that optimize different combinations of the three currencies: time, energy, and risk. I investigated how migratory behaviors of North American songbirds in the autumn balance the three currencies. More specifically I 1) explored how stopover site selection varies across migratory strategies at the landscape (Chapter 2) and habitat-patch (Chapter 3) scale; 2) investigated the importance of wind for the evolution and maintenance of migratory routes (Chapter 4); and 3) explored how selection of wind conditions for migratory departure affects overall behavioral strategies (Chapter 5). With this research, I hope to further our predictive abilities of migratory behaviors under various environmental and geographic situations using an optimal migration framework.</p>

<p> This project explored the potential fate and transport of seawater-based drilling fluid used in the Antarctic Drilling Program (ANDRILL) South McMurdo Sound project (SMS). The SMS drilling reported a loss of 5.6 &times; 10⁵ liters of drilling fluid to the surrounding formation throughout a borehole depth of 1139m. The introduction of these drilling fluids raise concerns of potential contamination to a pristine, isolated environment. The volume of fluid lost to the subsurface is unrecoverable and will only break down through natural attenuation processes, such as biodegradation. The objectives of this study are to estimate the extent of fluid migration laterally from the borehole and to determine when biodegradation of the water-based drilling fluid is effectively occurring. Variable density groundwater flow modeling (SEAWAT) was used to simulate the environment around the borehole. Applying stresses similar to the drilling events produced an estimate of how far fluid will be transported as drilling fluid is being circulated. Results show the fluid to migrate up to 7.5m into the subsurface. Additionally, laboratory microcosms were set up to incubate drilling fluid samples at various temperatures (5, 25, and 50&deg;C) under aerobic and anaerobic conditions. Experimental data collected over 188 days was analyzed to evaluate the time frame when biodegradation of drilling fluids occurred. Carbon isotope fractionation (¹³C/¹²C) was used to determine the ability of the drilling fluids to be used as a food source. Biological data observed changes in microbial growth using DNA quantification, and changes in microbial communities using Biolog EcoPlates&trade;. Results show a positive correlation between the increase of &delta;¹³C (&permil;) values and an increase in DNA (ng/&micro;l) quantity. Data from geochemical and community changes indicate biodegradation of the drilling fluid occurred between time 40 and time 100. The methods employed to investigate fate and transport is a unique approach, and applied to these water-based drilling fluids for the first time in this study.</p>

<p> Endocrine disrupting chemicals are a group of exogenous compounds which disrupt the endocrine functions of human and wildlife. This disruption might be in the synthesis, storage, release, and actions of specific hormones. Endocrine disrupting chemicals encompass a variety of chemical classes including drugs, compounds used in plastic consumer products manufacturing, pollutants, insecticides, herbicides, and even naturally-occurring botanical products like phytoestrogens. Most of these disrupters produce estrogenic properties because of having structural similarity to endogenous 17 beta estradiol. Mimicking estradiol, they can interfere with its actions resulting in the development of several diseases, such as nervous system, diabetes, obesity, breast cancers, and reproductive impairments. One of the endocrine disrupting chemicals of most interest is bisphenol A. </p><p> Bisphenol A is a carbon-based synthetic compound and it is used in epoxy resins, polycarbonate plastics, fungicides, antioxidants, stabilizers in rubber, and as a component of dental sealants. Numerous studies have found that bisphenol A may accidentally leak into canned foods or plastic bottled drinks ingested by humans. Studies indicate that bisphenol A effects are due to its estrogenic activity and the ability to bind and activate the estrogen receptor specifically. A growing number of studies have indicated that bisphenol A might be responsible for reduction in sperm count, spermatogenesis, aromatase, seminal fluid, 17 beta hydroxysteroid dehydrogenase activity, and testosterone biosynthesis. The primary objective of this capstone project is to review the available literature in order to determine the mechanism of bisphenol A action on testosterone biosynthesis. The working hypothesis was that bisphenol A-induced reduction in testosterone production may be due predominantly to inhibition of 17 beta beta hydroxysteroid dehydrogenase rather than an increase in aromatase enzyme activity. This study had the following specific aims: 1) review the sex steroid biosynthesis pathway, 2) review the endocrine disrupting chemicals; 3) determine a mechanism by which bisphenol A mimics estrogen and affects testosterone synthesis. Literature review was conducted using the databases PubMed, Ovid Medline, CINAHL Plus, as well as the search engine Google Scholar for the period 1940 to present. The keywords used: bisphenol A, testosterone, luteinizing hormone, 17 beta hydroxysteriod dehydrogenase enzymes. It was found that human studies were limited to urine measurements in which increased bisphenol A correlated with decreased sperm account and seminal fluid volume. In animal studies, bisphenol A reduced testosterone production by direct action on the leydig cells. In the ovarian granulosa cells, bisphenol A reduced aromatase enzyme activity but unlikely to be the method, in the testes as, a decrease in aromatase activity would cause an increase in testosterone level. Since bisphenol A causes significant decrease in testosterone biosynthesis, this suggests that the inhibition of 17 beta hydroxysteroid dehydrogenase, the enzyme that converts androstenedione to testosterone, is probably the principal target for bisphenol A. In conclusion, the literature supports a strong threat from bisphenol A on male reproductive function and every action must be taken seriously to reduce the exposure of male to this endocrine disrupting chemical. </p>

<p> Green roofs are an established best management practice (BMP) for storm water mitigation because of their ability to retain precipitation runoff. The purpose of this study was to quantify storm water retention of <i> Sedum</i> and native plant green roof systems at three substrate depths (10, 15, 20 cm). Survival of plants on green roof systems is dependent on how quickly they can establish themselves. This study also determined native and <i>Sedum</i> plant roof surface coverage at three green roof growth media depths (10, 15, 20 cm). A mixture of six <i>Sedum</i> species (<i>S. spurium, S. sexangulare, S. album, S. Immergrunchen, S. kamtschaticum</i>, and <i>S. reflexum</i>) and four native species (<i>Sporolus cryplandrus, Boutelous curtipendula, B. gracilis </i>, and <i>Penstamen pallidus</i>) were planted into the built-in-place systems (BIPs) on June 20, 2014. </p><p> There were 137 precipitation events totaling to 158.2 cm during the entire (June 20, 2014-June 30, 2015) study period and there were 87 precipitation events with a total precipitation of 108.1 cm during storm water collection (Oct. 31, 2015 until June 30, 2015). During the study period, mean storm water retention of green roof systems planted with native (>58%) and <i>Sedum </i> (>53%) species were identical regardless of growth media depth. Mean storm water retention in green roof systems planted with native and <i> Sedum</i> species in all growth media depths were greater than mean storm water retention of non-vegetated roof models (32%). </p><p> Green roof plant surface coverage plays an important role in water retention of storm water runoff. During the dormant period (January 23, 2015), roof coverage by <i>Sedum</i> plants was greater than roof coverage by native plants. In addition, green roof surface coverage by <i>Sedum</i> plants was the same regardless of depth (>89%). Green roof surface coverage of native plants in 10 cm depth achieved less coverage than native plants in 15 and 20 cm depths. These results differ from the plant-growing season (June 30, 2015). Green roof surface coverage by native plants in green roof systems with 15 and 20 cm growth media depth were identical to the roof coverage by <i>Sedum</i> plants in green roof systems with 10, 15, or 20 growth media depth. Green roof surface coverage by native plants in green roof systems with 10 cm growth media depth was less than the roof coverage in all green roof systems in this study. </p><p> Analysis of covariance was used to determine if green roof surface coverage by native and <i>Sedum</i> plants affected mean storm water retention. During the study period green roof surface coverage by native and <i> Sedum</i> plants did not affect storm water retention regardless of growth media depth. </p><p> This green roof research demonstrates that green roof systems planted with native plant species are effective tools for retaining storm water in the mid-western region of the United States. After 9 months, there was no difference in storm water retention between native and <i>Sedum</i> species planted in 10, 15, and 20 cm growth media depth. Each green roof module retained more storm water than the traditional, non-vegetated roof model. Both native and <i>Sedum</i> species planted on green roofs in 10, 15, and 20 cm media depth achieved more than 69 percent green roof surface coverage after nine months.</p>

<p> The main goals of this study were to map the current distribution of the invasive eastern gray squirrel in California as of 2016, to project the potential future geographic range of the species, and to identify areas where the future range of the eastern gray squirrel is likely to overlap the range of the native western gray squirrel. Location data were obtained from museum specimens, wildlife rehabilitation centers, a roadkill database, and research-grade citizen observations. Ecological niche models were created with Maxent, while range and habitat suitability maps were produced with ArcGIS software. Populations of eastern gray squirrels are currently concentrated around Sacramento, the San Francisco Bay, Monterey, and Bellota. The highest priority areas for control and eradication are areas of western gray squirrel habitat near existing eastern gray squirrel populations, including both peninsulas of the San Francisco Bay, areas near Santa Cruz, Oakland, Santa Rosa, and the Monterey Peninsula.</p>

We are living in the era of climate change which becomes more complicated whenever some new environmental issue emerges only to get linked with this already existing challenge. Engineered nanoparticle (NP) contamination is of such issue which may become a major environmental problem under some circumstances in the decades to come. NP-based technologies have proven themselves useful and have the potential for greater promise, but they could become more than a nuisance. Unfortunately, very limited information is available on the environmental impacts of NPs in general and soil in particular. In this thesis, I examined the impact of NPs on soil microbial communities and by trying to avoid the presence of existing NPs I used soil from arctic regions. To examine the effect of another anthropogenic change on the same soil, I investigated the impacts of freeze-thaw cycles (FTCs). This thesis demonstrated that Ag-NPs and Cu-NPs cause a shift in microbial communities. The use of culture-dependent and culture-independent assessment techniques for microbial communities inspired the development of a toxicity indicator. This tool assigned the highest toxicity index to Ag-NPs and a low toxicity to SiO2-NPs. Supporting in vitro studies confirmed that Bradyrhizobium canariense was particularly sensitive towards Ag-NPs. Further analysis showed that a mixture of Ag-, Cu-, and SiO2-NPs were toxic. FTCs were also a significant stress; they had a differential impact upon soil communities derived from different arctic sites. My results suggest that the impact of climate change at high latitudes may not be predictable. Finally, I used a FTC regime shown not have an impact on low arctic sites and compared two different concentrations of Ag-NPs and Ag-microparticles and validated the higher toxicity impact of Ag-NPs on both bacterial and fungal communities. Taken together, these findings represent an initial attempt to try to understand the impacts of two stresses attributable to human activities on arctic soils, soils that are crucial to the health of our planet. / Thesis (Ph.D, Biology) -- Queen's University, 2013-06-03 22:36:24.182

<p>Green roofs have many ecological benefits that address numerous modern environmental issues. Many studies have evaluated Sedums on green roofs; on the other hand, there is much interest in native plant performance on a green roof. In my study, Green Roof Blocks were planted with 3 experimental treatments: native plants only; native species plus Sedums; and Sedums only. The native species only treatment consisted of Eragrostis spectabilis, Coreopsis lanceolata, Penstemon pallidus, Penstemon hirsutus, Koeleria marcantha, Rudbeckia hirta, Aster laevis and Carex muhlenbergii. These areas were planted with one plug per native species for a total of eight plugs per Green Roof Block. Natives were interspersed between existing Sedum plantings in the native species plus Sedum planting treatment. There was again one plug per six species, but only six native plugs per block. The species in these planting areas were Bouteloua gracilis, Buchloe dactyloides, Asclepius verticillata, Bouteloua curtipendula, Geum triflorum and Sporobolus cryptandrus. All native plants were planted in the two treatments on 5/29/2013 and 6/5/2013. All plants in the study plots were irrigated weekly as needed in 2013 and 2014. On November 7 and 8, 2013, June 10 and 23, 2014, June 2015, November 2015, and April 2016 native plant survival was measured. In the plots with natives only, survival ranged from 0 to 86 percent at the end of the study. To date, Coreopsis lanceolata and Penstemon pallidus have the greatest percent survival in the natives only planting area at 86 and 45 percent respectively. In the plots with natives plus Sedums, native plant survival ranged from 0 to 70 percent at the end of the study. Survival of the four native grasses was greater than 99 percent in the first growing season. To date, the only native species remaining in the natives plus Sedums planting area is Buchloe dactyloides, with about 70 percent survival. In addition, the forb Coreopsis lanceolata has rapidly spread outside the initial planting areas, indicating that this native species not only survives on the roof, but is able to reproduce successfully.

<p> The use of wood pellet boilers for residential space heating has significantly increased over the past decade. Wood pellets are a biomass-based renewable energy made by pelletizing debarked wood fiber. Compared to log wood and wood chips, wood pellets have higher energy density, relatively uniform fuel quality, easier to automate their use, and therefore, are being more widely used.</p><p> A typical wood pellet heating system has three components: the boiler (energy generation unit), the thermal energy storage (TES) tank (energy storage unit), and the building (energy consumption unit). The three components form into two loops: the boiler to TES tank loop and the TES tank to building loop. </p><p> Three modern wood pellet boilers were installed and monitored in this research. Two 25 kW boilers (PB and WPB) were installed in the end of 2014 and a 50 kW boiler (LGB) was installed in March of 2016. PB is used only for radiant floor heating and WPB is used for traditional baseboard/cast iron radiators space heating as well as providing domestic hot water (DHW) supply. LGB boiler is used for concrete slab heating. The three boiler installations provide different methods of heating and different levels of building heat demand.</p><p> This research first evaluated the performance of residential scale wood pellet boilers (25 &ndash; 50 kW) in terms of boiler operation characteristics, thermal efficiency, boiler emissions, TES tank stratification and discharge efficiency, etc. Comparisons were also made among different boilers and suggestions for improvements were made. A process dynamic simulation using VMGSim was built up based on the field monitoring data. Good agreement between the simulation and field data was found. The model was then used to size the TES tank with respect to different boiler capacities and heating demands. A system sizing algorithm was provided in the end. The results will be used to compose a guidance document for wood pellet boiler heating systems. </p>

<p> Nitrous acid (HONO) is a photochemical source of hydroxyl radical that plays an important role in initiating radical reactions leading to photochemical air pollution and aerosol formation in the lower atmosphere. Field studies suggest nocturnal and daytime HONO sources that stem from heterogeneous reactions on environmental surfaces. However, the mechanisms are not well-understood and atmospheric models under-predict daytime HONO levels by 30&ndash;50%. The main aim of this research is to examine proposed nocturnal and daytime sources with a focus on elucidating the mechanisms of HONO formation and understanding the variables controlling this important process. Results from four projects are presented. The first project focuses on aqueous nitrate (₃^&ndash;) photolysis and the role that nitrogen dioxide (NO₂) hydrolysis plays in the formation process. The second involves linking the flux of HONO from agricultural and urban soil samples to ammonia oxidizing bacteria and archaea. The third project elucidates the mechanism of NO₂ reduction on surfaces containing humic acids (HA), specifically focusing on quinone and hydroquinone redox chemistry. The fourth project seeks to explain how nitrate photolysis on HA or iron surfaces can be an important daytime source of HONO. We suggest that NO₃^&ndash; photolysis in the presence of chromophoric compounds and OH radical scavengers, which are naturally present on the environment surfaces, help explain the higher than expected daytime HONO levels observed during recent field studies. </p>

<p> Sediment bioturbators play an important ecological role and may both be affected by contaminants in the sediment and affect the fate and distribution of these contaminants. This is especially important for the many contaminants, like lead, for which sediments serve as a sink upon the contaminants&rsquo; release into the environment. In this study, I investigated the toxicity of sediment Pb to a freshwater bioturbator, the effect of bioturbation on the environmental distribution of the Pb, the effect of sediment characteristics on the bioturbation-mediated transfer of Pb from the sediment to the water column, and this transfer&rsquo;s toxicological consequences for planktonic organisms. Experiments were conducted in microcosms with control sediment or Pb-spiked sediment, the freshwater oligochaete Lumbriculus variegatus served as the model bioturbator, and the water flea Daphnia magna served as the model planktonic organism. The rate of bioturbation of the oligochaete was quantified using luminophores. </p><p> The bioturbation resulted in the transfer of Pb from the sediment to the water column. However, it did not affect Pb levels in the worm tissue or in the sediment. The environmental distribution of Pb among water column, biota, and sediment in the presence of the bioturbator was dependent on sediment characteristic like organic content, silt/clay content, and the pH of the sediment. Bioturbation by L. variegatus increased bioaccumulation of Pb in D. magna; however, this Pb had no toxic effect on survival, reproduction, and biomass of D. magna under the specific conditions used here. Quantification of the bioturbation rates of L. variegatus showed that the intensity of the bioturbation was enhanced at higher densities of the oligochaete but reduced at high sedimentary Pb concentrations. Overall this study demonstrated that bioturbation by L. variegatus can transfer Pb from the sediment to the water column, and that this transfer is dependent on sediment characteristics. The Pb transferred as a result of the bioturbation can enhance Pb availability to organisms in the water column, and potentially cause toxic effects in these organisms.</p>