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Polymers can be decorated with functional groups (FGs) to confer specific and tuneable properties to the molecules. By varying the chemical architecture, concentration, and distribution of the FGs on the polymer, it is possible to control the chemical and physical properties of the polymers. Such functionalised polymers are applied broadly, in chemical synthesis, biological science, chemical engineering, medicine, agriculture, food science, optical science, and the energy sector. This thesis is devoted to the study of functionalised polyethylene/polypropylene (PE/PP) copolymers used to control friction and wear in combustion engines. The aim is to investigate how the distribution of FGs on linear PE/PP copolymers controls the structural, dynamical, and tribological properties of the molecules when dissolved in n-heptane (representing an oil), either in bulk, or confined and sheared between solid iron oxide surfaces (representing the moving parts of engines). Large-scale atomistic molecular dynamics simulations are used to gain detailed and unique insights on the links between molecular-scale and tribological properties. Simulations of isolated copolymers in solution are carried out to explore how the radius of gyration, end-toend distance, and scattering form factor are dictated by the distribution of a proprietary FG. It is shown that the size of a copolymer can vary by as much as 38% by varying the FG distribution, due to the association of the FGs in solution. It is found that solvophobic interactions are responsible for this association, and the results are supported by simulations of different FGs without the opportunity to stack. Predicted form factors will enable comparisons to be made with future X-ray and neutron scattering experiments. The shear viscosity is found to correlate well with the FG distribution and copolymer size at low concentration, while at high concentration the viscosity does not seem to depend with FG distribution, in agreement with the lack of variation in static structure. Next, the properties of copolymers solutions confined between iron oxide surfaces are explored, in static conditions and under shear. It is found that the FG distribution strongly affects the nature of the adsorption of the copolymers, and the response of the adsorbed film to shear, as measured by mass-density and velocity profiles across the liquid layer.

Anthropogenic activities, such as rapid agricultural expansion, have led to a decline inbiodiversity and the fragmentation of natural habitats. Incorporating non-crop habitat within agricultural landscapes, even at small scales, can enhance biodiversity and promote ecosystem services like biological pest control through spillover. Spillover of beneficial arthropods from non-crop habitats into crop systems is responsible for effective pest management without the financial or ecological detriments; however, spillover in the opposite direction is less understood. We sought to reveal more about the functional diversity of non-crop edges surrounding differing crop varieties, corn and soybean, to gain greater insights to the overall community dynamics of agroecosystems. Fourteen agricultural fields in Wood County, Ohio were selected based on crop variety and the presence of vegetation patches. Arthropods were sampled using sweep-nets, sorted, identified, and categorized into one of four functional groups based on their ecological roles. We collected over 18,000 arthropods belonging to over 480 different taxa. We found significant species overlap between crop varieties, with 202 species commonly shared out of a total of 341 species for corn and 343 species for soybean. The Shannon and Simpson’s diversity indices revealed no significant differences between the edges of the two varieties. Mann- Whitney tests indicated no significant differences in species richness of each of the four functional groups between corn and soybean sites. A two-way repeated measures analysis of variance highlighted a significant relationship between time and species richness but indicated no significant difference between the species richness of the crop edges. Corn and soybean as cultivated crops offer similar resources, so it is understandable to see strong similarities in species composition of their edge communities. Given the analogous nature of these agroecosystem edges, similar management strategies could be implemented, thus streamlining pest management practices for farmers. Further simplifying pest management with the use of natural ecosystem services like biological control could improve quality of product and overall biodiversity. Continued investigation of functional diversity as well as more focused analysis of species interactions could greatly enhance our understanding of agroecosystems and enhance our ability to formulate useful conservation management practices in the agricultural industry.

In the era of unprecedented biodiversity loss and a subsequent loss of ecosystem function, a core goal of restoration ecology is to identify planting strategies to restore ecosystem functions like soil carbon sequestration. Plant diversity, functional groups and functional traits can all be leveraged to improve ecosystem function, but there are major gaps in our understanding of which strategies are most impactful for increasing soil carbon (C). In this study, we seeded common California grassland species in 210 experimental plots and examined how plant functional groups, functional traits and diversity metrics influenced five unique soil carbon pools. We also evaluated effects of precipitation and land use history treatments on soil C pools across two years to examine how environmental conditions mediate plant-soil interactions, and if there are time lags in those effects. Land use history was the biggest single predictor of soil C, with the duration of shrubs on the site prior to our experiment outweighing the effects of all other variables. In linear mixed-effects model comparisons, environmental variables (precipitation, land use and year) alone best explained particulate organic carbon (POC), while adding species diversity metrics improved predictions for total carbon (TC), microbial biomass carbon (MBC) and mineral-associated organic carbon (MAOC). However, functional and species diversity correlated negatively with soil C pools in some environmental conditions, showing that diversity itself may not always boost soil C levels. Water-extractable organic carbon (WEOC) did not vary with any plant or environmental model. Analyzing effects of individual variables, we found that diversity, functional trait, and functional group correlations varied across soil C pools, environmental context, and the year of vegetation measured. These results suggest that different plant strategies contribute to soil C pools through disparate pathways on various timescales. Our study highlights how dynamic soil C is in grassland systems and that additional work is needed before restoration managers can use trait-based approaches to sequester soil C in various site contexts.

The surface structure–binding property relationships in the selective removal of regulated ions in complex wastewaters were investigated in order to aid in the surface design strategies that can be applied to tackle a wide range of environmental challenges presented by regulated cations and anions. Functionalized silica adsorbents and zero-valent iron (ZVI) materials were studied in order to meet the new US EPA effluent limitation guidelines. The binding of Hg2+ by mercaptan-functionalized silica possessing different physical characteristics was explored through experimental investigations and theoretical calculations. The DFT calculations suggested a simultaneous monodentate and bidentate Hg2+ complex formation on sulfur-containing surface functional groups that strongly depends on the Hg2+ concentration. Theoretical Hg2+ adsorption isotherms predicted by DFT calculations have shown that even when the adsorbent surface had heterogeneous adsorption sites capable of a simultaneous monodentate and bidentate complexation, the adsorption still followed the Langmuir model.Five sulfur-containing functional groups were studied for the adsorption of Hg2+ from simulated wastewater with toxic and nontoxic compositions reported in flue gas desulfurization (FGD) wastewater. It was found that the molecular structure of a functional group greatly influences its activity toward cation binding.The affinity of Hg2+ towards the functional groups of this research as measured by the experimental Henry’s Law constants suggested a correlation with corresponding theoretical HOMO energies and interaction energies.A systematic study of the application of ZVI materials for FGD wastewater remediation has established optimal process conditions, and nanoparticle structure-property relationships for the reduction and removal of Se6+, a key regulated species, using pure ZVI and several bimetallic ZVI compositions, as well as an improved mechanistic understanding of Se sequestration. The improved Se sequestration occurs through the corrosion of nanosized ZVI (nano ZVI), which facilitates direct Se6+ reduction to elemental Se0 and Se2- at the ZVI surface. Finally, the mechanism involved in the reaction of regulated ions with nano ZVI in the presence of an applied weak magnetic field (WMF) was also investigated. The magnetic gradient force produced by ferromagnetic ZVI particles had a greater influence on the rate of selenite diffusion in solution than the Lorentz force due to the externally applied weak magnetic field. Moreover, the magnetic gradient force was suggested to suppress ZVI corrosion reactions. Despite changes in the iron oxide layer under the WMF influence, the rate of selenate reduction has not been significantly affected in the short-term reactions of a few hours. Most crucially, WMF had a negligible effect on the rate of mass transport of selenate anions, as compared to the dominant effect of forced convection. On the other hand, magnetic field gradient force suppressing corrosion of ZVI may be beneficial for longer-term stability of ZVI in aqueous environmental conditions, where longer reaction times are necessary. The suppression of ZVI corrosion can prevent the depletion of electrons in the ZVI particle, extending the effectiveness of ZVI for the target reactions.

A key uncertainty in ecology is how concurrent global change factors will interact to affect terrestrial ecosystems. Humans have altered Earth’s carbon dioxide (CO2) concentrations, climate, nutrient levels, and biodiversity, all of which affect plant communities and ecosystem function. Yet, few multi-factor field studies exist to examine interactive effects of global changes on plants and ecosystems. I characterized the physiological responses of perennial grassland species from four plant functional groups (C3 grasses, C4 grasses, nitrogen-fixing leguminous forbs, and non-leguminous forbs) to single and interactive global changes including elevated carbon dioxide, increased soil nitrogen supply, reduced rainfall, and climate warming. I also determined how elevated CO2, increased soil nitrogen supply, and planted species richness affected total ecosystem carbon (C) storage over 19 years. These studies took place in the open-air, global change grassland ecosystem experiment, BioCON (Biodiversity x CO2 x Nitrogen), located at the Cedar Creek Ecosystem Science Reserve in Minnesota, USA. I present evidence that (1) the ability of plants to capture additional C as atmospheric CO2 rises via photosynthesis may be more limited than traditionally believed; (2) substantial, sustained declines in stomatal conductance and increases in water-use efficiency under elevated CO2 occur widely among grassland species; (3) global change factors interact in complex ways to affect photosynthesis, and how factors interact varies among grassland species; and (4) declines in biodiversity may influence ecosystem C storage more than a 50% increase in CO2 or high rates of nitrogen deposition in perennial grassland systems. These findings show that simple predictions of plant physiological responses to global changes based on theoretical expectations of isolated effects and on functional classifications of species are not sufficient – global changes and other environmental factors interact in complex ways to impact responses of species. These results also highlight the importance of biodiversity in promoting ecosystem function and call into question whether elevated CO2 will increase the C sink in grassland ecosystems and help to slow climate change.

Phytoplankton play important roles in marine food webs and biogeochemicalcycles. The ability to understand natural changes in phytoplankton populations are acentral goal in biological oceanography; however, the dynamics of phytoplanktonpopulations are often noisy and difficult to predict. The portfolio effect in ecology is aconcept that relies on the aggregation of data to reduce the variance of individualpopulations. We test whether the aggregation of data across multiple species can helpimprove the predictions of phytoplankton assemblages one month into the future. Usingempirical dynamic modelling, we assess the predictability of phytoplanktonassemblages in varying group sizes, and show that certain assemblages ofphytoplankton species are more predictable in groups rather than as individual species.

Considerable knowledge gaps remain in our understanding of the response of waterbird communities and population dynamics in response to flows in floodplain ecosystems. Conservation of inland wetlands relies on the effective management of environmental flows for flood-dependent biota, including waterbirds. I investigated how waterbird communities responded to a flow pulse in the Macquarie Marshes, an internationally recognised (Ramsar-listed) wetland. Two environmental flow pulses were released in early September (4,882 ML) and mid-October (28,911 ML) and four survey periods (1-4) occurred in August, October (before the 28,911 ML flow), December and January. I surveyed waterbirds at 17 sites before (August, October), during (December) and after (January) the larger of two environmental flow releases (totalling 33,793 ML in 2014-15). I compared waterbird response to flows across three wetland types: channels, lagoons and floodplains. I used generalised linear models to test for the effect of flow and other environmental variables on total waterbird relative abundance and number of species and for each functional or taxonomic response group: ducks, herbivores, large waders, piscivores and shorebirds. Duck counts for all surveyed wetlands were highest in survey period 1 (48± SE 20.29), herbivores in survey period 2 (3.71±0.11), large waders in survey period 3 (11.75±8.81), piscivores in survey period 4 (2.69±2.18) and shorebirds in survey period 2 (11.41±5.88). Wetland type and local inundation had a significant effect on waterbird abundance and the number of species at all sites and survey periods, with lagoons and floodplains supporting the highest numbers. Lagoon and floodplain sites were standardised (4 ha) area, to allow comparisons in waterbird density. To determine whether waterbird behaviour varied with resource availability following a flow pulse, I separately modelled the number of birds engaged in one of three behaviours (feeding, locomoting, roosting) per functional group, as a proportion relative to the other behaviours at a site. Lagoons supported the greatest proportion of feeding waterbirds, with a high proportion of large waders (0.60±0.12), while floodplains had large proportions of locomoting large waders (0.40±0.09) and shorebirds (0.55±0.12). Channels had limited foraging habitat, but provided roosting opportunities for waterbirds, especially piscivores (0.10±0.05). I also collected macro-invertebrate samples at floodplain and lagoon sites and found the proportion of ducks feeding was positively associated with macro-invertebrate (prey) biomass. The feeding activity (number of actions per 1-minute) of two common species (yellow-billed spoonbill Platalea flavipes and black-winged stilt Himantopus himantopus) was strongly positively correlated with lagoon wetlands. This study identifies site-specific variables (local inundation and wetland type) as important drivers of waterbird abundance. Lagoons supported the greatest relative abundance of waterbirds as well as the highest proportion of feeding activity. This study supports the release of environmental flows to create and maintain habitat for waterbirds, during a relatively dry season. Further understanding of the spatio-temporal dynamics between waterbird functional groups, flow and other environmental variables would assist in the development of measurable targets to sustain waterbird feeding habitat.

6,6’-Dimethoxygossypol (DMG) is a natural product of the cotton variety Gossypium barbadense and a derivative of gossypol. Gossypol has been shown to form an abundant number of clathrates with a large variety of compounds. One of the primary reasons why gossypol can form clathrates has been because of its ability to from extensive hydrogen bonding networks due to its hydroxyl and aldehyde functional groups. Prior to this work, the only known solvate that DMG formed was with acetic acid. DMG has methoxy groups substituted at two hydroxyl positions, and consequently there is a decrease in its ability to form hydrogen bonds. Crystallization experiments were set up to see whether, like gossypol, DMG could form clathrates. The following results presented prove that DMG is capable of forming clathrates (S1 and S2) and two new polymorphs (P1 and P2) of DMG have been reported.

Urbanization has resulted in massive transformation of natural habitats with profound effects on biodiversity. Addressing the problems associated with anthropogenic deterioration of the environment requires solid understanding of the factors driving these changes. Habitat patch size, edge effects, and the presence of invasive species are among the key features of the urban landscape affecting local communities. My study focused on the effects of habitat edges, the exotic ant Nylanderia flavipes, and the invasive herb garlic mustard on local ant diversity in deciduous forest fragments of northeastern Ohio. In addition, I explored the value of common ant collecting techniques for estimating ant diversity.When compared to pitfall trapping, Winkler litter extraction showed greater species richness and higher abundance of ants and exhibited the advantage of a more complete inventory. Winkler extraction may completely replace pitfall trapping in temperate forests with well-developed litter layer, and inventorying programs may benefit from the inclusion of this technique as a rapid and effective ant-collecting tool. Our study documents predictable edge-associated changes in species richness, community composition and functional groups, occurring in local forest ant assemblages. Edge effects are most pronounced within the first 25m, which may have implications for the conservation of forest-dwelling fauna. At the sites where Nylanderia flavipes occurred, we found a 6-fold increase in ant abundance, with 87% of the ants being N. flavipes. The numerical dominance of this species did not lead to detectable changes in the species richness and abundance of the native ant community, but was responsible for decreased community evenness. This is likely indicative of a recent introduction with populations still being in their latency period. The high local abundance of N. flavipes may give it a competitive advantage and affect native ants through exploitative competition. Plots invaded by garlic mustard showed significant reduction in leaf-litter depth, correlated with increased abundance of nonnative earthworms, but no detectable effects on ant species richness or community composition. My results suggest that regional sylvan ant communities are unaffected by the generally presumed negative effects of garlic mustard, or that these effects are more subtle or confounded by other dominating factors.