Land application of biosolids has been demonstrated to improve nutrient availability (mainly N and P) and improve organic matter in soils, but the effects of biosolids on C sequestration and N cycling in the Mid-Atlantic region is not well understood. The objectives were: 1) to investigate soil C sequestration at sites with a long-term history of biosolids either in repeated application or single large application; 2) to characterize and compare soil C chemistry using advanced 13C nuclear magnetic resonance (NMR) and C (1s) near edge x-ray absorption fine structure (NEXAFS) spectroscopic techniques; and 3) to compare biosolids types and tillage practices on short-term N availability in the Coastal Plain soils. Biosolids led to C accumulation in the soil surface (< 15 cm) after long-time application in both Piedmont and Coastal Plain soils. The C saturation phenomenon occurred in Coastal Plain soils, thus additional soil C accumulation was not achieved by increasing C inputs from biosolids to the Coastal Plain. Soil organic C from profiles in the field sites was not different at depths below the plow layer (15-60 cm). The quantitative NMR analyses concluded that O-alkyl C was the dominant form in the particulate organic matter (POM), followed by aromatic C, alkyl C, COO/N-C=O, aromatic C-O, OCH3 / NCH and ketones and aldehydes. The aliphatic C and aromatic C were enriched but the O-alkyl C was decreased in the biosolids-amended soils. The changes indicated that the biosolids-derived soil C was more decomposed and, thus, more stable than the control. The NEXAFS spectra showed that O-alkyl C was the dominant form in the POM extracted from biosolids-amended soils, followed by aromatic C, alkyl C, carboxylic C and phenolic C groups. These results were similar to those from NMR analysis. The regression and correlation analyses of C functional groups in the POM between NEXAFS and NMR indicated that both techniques had good sensitivity for the characterization of C from biosolids-amended soils. To evaluate short-term biosolids N availability, a three-year field study to investigate the effects of lime-stabilized (LS) and anaerobically digested (AD) biosolids on N availability in a corn-soybean rotation under conventional tillage and no-tillage practices was set up in 2009-2011. Results showed that both LS and AD biosolids increased spring soil nitrate N, plant tissue N at silking, post-season corn stalk nitrate N, grain yield, and soil total N by the end of the growing season. The same factors used to calculate plant available N for incorporated biosolids can be used on biosolids applied to no-till systems in coarse-textured soils. All these results indicated that the application of biosolids affects the long-term quantification and qualification of soil organic C and also improve short-term N availability in the Mid-Atlantic region. / Ph. D.

The equatorial Pacific is a dynamic region, characterized by zonal and meridional asymmetries in both the ocean and the atmosphere. The asymmetries in the eastern equatorial Pacific (EEP) reach a maximum in northern hemisphere fall, when southern hemisphere trade winds cross the equator and drive the upwelling of cold, CO₂ and nutrient-rich waters along a shallow thermocline, fueling marine primary production. Interannual perturbations in ocean heat content also result in El Niño or La Niña events, which diminish or amplify these asymmetries. In this dissertation, multi-proxy paleo-records derived from marine sediment cores are used to reconstruct fundamental aspects of the coupled ocean-atmosphere system in the EEP and to evaluate the hypothesis that changes in the seasonal distribution of equatorial insolation, which were primarily controlled by Earth’s precession, influenced the mean state and variability of the EEP in the late Pleistocene. EEP thermocline depth, reconstructed from the δ18O of multiple species of planktic foraminifera that lived at different depths in the water column, was found to oscillate between a La Niña-like and an El Niño-like state on precession timescales, in close phase with equatorial insolation during northern hemisphere late summer/early fall. EEP export production, reflected in sedimentary 231Pa/230Th, was influenced by changes in high latitude nutrient leakage and upwelling and, at times, varied on precession timescales. Glacial increases in EEP deep ocean carbon storage, reconstructed from sedimentary authigenic 238U, occurred independently of changes in local export production. Individual δ18O analyses of the surface-dwelling foraminifera Globigerinoides ruber were used to reconstruct EEP sea-surface variability during the last interglacial and penultimate glacial period. While sea-surface variance was not significantly different from that of the late Holocene, the paleo-record suggests that the strength and frequency of ENSO events varied with changes in equatorial insolation during northern hemisphere late summer/early fall and with EEP thermocline depth.

This thesis investigates innovative and sustainable methods for the extraction and recovery of critical metals from various waste streams, with the goal of reducing reliance on primary ores and minimizing the associated environmental impact. As global demand for these essential materials grows, finding effective alternatives becomes increasingly urgent. This research is structured around four main chapters, each addressing different aspects of metal recovery in the hydrometallurgical process and focusing on integrating environmentally friendly processes. By exploring advanced extraction techniques and the use of novel materials, this work aims to contribute to the development of greener technologies in the field of materials recovery. Chapter 1 introduces a new framework that combines critical element recovery from waste-to-energy fly ash (WTE FA) with carbon sequestration, addressing environmental concerns related to the growing demand for materials in green technologies. This study integrates electrochemical Zn recovery with carbon capture, utilization, and storage (CCUS), demonstrating the potential for carbon-neutral Zn recovery. Using renewable acids (HNO₃), Ca and Zn were leached undermild conditions (pH 3), followed by electrochemical separation for high-purity Zn recovery. The unique morphology of the feedstock facilitated rapid metal extraction, while water wash pretreatment removed Ca-rich salts for subsequent carbonation, converting the remaining Ca into high-purity calcite. Chapter 2 develops new ligand systems that selectively extract and release critical elements, such as lanthanides, from solutions containing competing metal ions. A tunable molecular scaffold based on tris(2-aminoethyl)amine was functionalized with salicylaldehydes to create imine ligands that effectively extracted Ce, even in the presence of Mg and Ca. The study employed CO₂ as a stimulus for re-extraction, producing cerium carbonate and high-purity ceria. This pHswing mechanism, driven by controlled CO₂ partial pressure, enables efficient recovery of energy-relevant elements from unconventional resources, demonstrating the potential of green chemistry in metal recovery. Chapter 3 develops silica gel functionalized with polyethyleneimine (PEI), known as μOHMs, for the efficient and selective capture of heavy metal ions on both batch and continuous scales. Maximum adsorption capacities for Cu, Zn and Ni ions are 63.5, 43.1, and 36.2 mg/g, respectively, at pH 5.5. The adsorption process follows pseudo-second-order kinetics and the Langmuir isotherm model. Thermodynamic experiments indicate spontaneous, exothermic removal governed by monolayer chemisorption. Performance tests demonstrate a consistent removal rate of 33.5 mg/g for Cu after fifty cycles, highlighting the effectiveness of amine group complexation in heavy metal capture. Chapter 4 examines 2-hydroxyaryloximes as effective candidates for metal separation, forming stable, size-selective pseudo-macrocyclic dimers through hydrogen-bonding networks. These ligands exhibit pH-dependent coordination properties influenced by the phenolic oxygen's protonation state. The chapter explores the structure-property relationships of seven 2-hydroxyaryloximes in liquid-liquid extraction schemes for Ni and Co. It presents a generalizedmultigram synthesis and concentration- and solvent-dependent characterization. Steric and electronic effects from peripheral substituent modifications on the dimerization constant and pKa values were systematically investigated using NMR and potentiometric titrations. These findings demonstrate the potential of these ligands for "pH-swing" separations of energy-relevant metals. Overall, this thesis addresses critical challenges in sustainable metal recovery by employing interdisciplinary approaches that encompass chemistry, materials science, and chemical engineering. By integrating innovative techniques and materials, the research identifies effective strategies for extracting valuable metals from unconventional waste sources while minimizing environmental impact. The findings contribute significantly to the development of greener processes and materials, presenting viable alternatives to traditional extraction methods. Furthermore, this work supports sustainability in metal recovery by promoting the efficient use of resources, reducing waste, and enhancing the overall viability of circular economy principles in the field of materials recovery.

A storage and enhanced coalbed methane (CO2-ECBM) test will store up to 20,000 tons of carbon dioxide in a stacked coal reservoir in southwest Virginia. The test involves two phases of CO2 injection operations. Phase I was conducted from July 2, 2015 to April 15, 2016, and injected a total of 10, 601 tons of CO2. After a reservoir soaking period of seven months, Phase II is scheduled to begin Fall 2016. The design of the monitoring program for the test considered several site-specific factors, including a unique reservoir geometry, challenging surface terrain, simultaneous CBM production activities which complicate the ability to attribute signals to sources. A multi-scale approach to the monitoring design incorporated technologies deployed over different, overlapping spatial and temporal scales selected for the monitoring program include dedicated observation wells, CO2 injection operations monitoring, reservoir pressure and temperature monitoring, gas and formation water composition from offset wells tracer studies, borehole liquid level measurement, microseismic monitoring, surface deformation measurement, and various well logs and tests. Integrated interpretations of monitoring results from Phase I of the test have characterized enhanced permeability, geomechanical variation with depth, and dynamic reservoir injectivity. Results have also led to the development of recommended injection strategy for CO2-ECBM operations. The work presented here describes the development of the monitoring program, including design considerations and rationales for selected technologies, and presents monitoring results and interpretations from Phase I of the test. / Ph. D. / Recent efforts to manage and reduce atmospheric carbon dioxide (CO₂) emissions include the development of technologies for carbon capture, utilization, and storage (CCUS) operations. CCUS technologies are used to capture CO₂ emissions from a power plant or other point source, transport the captured CO₂ to a field site, and inject the CO₂ underground into a geologic reservoir. There it is securely stored within a deep, sealed geologic formation and/or is utilized to enhance oil or gas recovery from the formation. CCUS operations conducted on a commercial scale could play an important role in combating anthropogenic climate change. Field tests for carbon storage and utilization operations support the objective of scaling up by demonstrating the storage potential of target reservoirs, the profit potential from enhanced recovery, and the safety of all field operations. Field tests are monitored intensively in order to understand reservoir behavior in response to CO₂ injection and to evaluate progress toward project objectives. An ongoing small-scale carbon storage and utilization test in southwest Virginia is testing the potential for CO₂ storage and enhanced gas recovery from a depleted coalbed methane reservoir. The carbon storage and enhanced coalbed methane (CO₂-ECBM) test will store up to 20,000 tons of carbon dioxide in a coal reservoir composed of approximately 20 individual seams. The test involves two phases of CO₂ injection operations. Phase I was conducted from July 2, 2015, to April 15, 2016, and injected a total of 10,601 tons of CO₂. After a reservoir soaking period of seven months, Phase II is scheduled to begin in Fall 2016. The design of the monitoring program for the test considered several site-specific factors, including a unique reservoir geometry, challenging surface terrain, and simultaneous coalbed methane production activities which complicate the ability to attribute signals to sources. A multi-scale approach to the monitoring design incorporated technologies deployed over different, overlapping spatial and temporal scales. The work presented here describes the development of the monitoring program, including design considerations and rationales for selected technologies, and presents monitoring results and interpretations from Phase I of the test.

Due to concern over the increasing concentration of carbon dioxide in the atmosphere, forest researchers and managers are currently studying the effects of varying silvicultural and harvesting practices on the carbon dynamics of intensely managed forest ecosystems. Soil carbon dioxide efflux resulting from soil microbial activity and root respiration is one of the major components of the total carbon flux in forested ecosystems. In an effort to examine the response of soil carbon dioxide efflux to changes in soil factors, nutrient availability, temperature, and moisture, soil respiration rates were measured monthly over an entire year in a two-year-old loblolly pine (Pinus taeda L.) plantation subjected to fertilization and mulching treatments. A dynamic, closed-chamber infrared gas analysis system was used to measure efflux rates from plots treated with one of four treatment combinations including: nitrogen (115 kg/ha) and phosphorus (11.5 kg/ha) fertilization with black landscape cloth (mulch), fertilization without mulch, mulch without fertilization, and no treatment (control). For each treatment combination, plots were established at the seedling base and 1.22 m away from the seedling base to examine the effect of seedling roots on soil carbon dioxide efflux rates. Soil temperature and moisture were measured at each chamber position monthly and soil coarse fragments, soil nutrient levels, percent carbon, root biomass and coarse woody debris were measured beneath 64 chambers at the end of the study. Fertilization had no significant effect on efflux rates during any of our monthly sampling sessions despite the fact that fertilized seedlings experienced significant increases in both above and belowground biomass. Conversely, regression analysis of growing season soil carbon dioxide efflux rates revealed a slightly negative correlation with both total seedling nutrient uptake and biomass. Rates in plots with mulching were significantly higher than rates from non-mulched plots during five monthly measurement sessions, and higher rates in mulched plots during winter months was attributable to warmer soil temperatures. Rates at the seedling base were always significantly higher than rates in plots away from the seedling. Although rates were always higher at the seedling base, the variability observed was only weakly correlated with the amount of pine roots present beneath respiration chambers. Utilizing soil temperature and moisture, soil carbon, and cuvette fine root biomass in a regression model explained 54% of the variance observed in efflux rates across the yearlong study period. Soil temperature alone explained 42.2% of the variance, followed by soil carbon and soil moisture at 5.2% and 2.7% respectively. The amount of pine fine roots under measurement chambers accounted for only 2.4% of the variance. An additional 1.5% was explained by other factors such as soil phosphorus, coarse woody debris, non-pine root biomass, and soil calcium. An examination of the factors affecting the spatial patterns of soil carbon dioxide efflux revealed that total soil carbon and the amount of fine pine root biomass beneath cuvette base rings explain 38% and 11% respectively, of the observed variability in mean annual soil carbon dioxide efflux from differing plots. The most influential factor affecting soil carbon dioxide efflux during the yearlong study period was soil temperature and modeling of seasonal soil carbon dioxide efflux rates from managed forests using both soil temperature and moisture should be achievable with the establishment of data sets and statistical models covering a range of sites differing in productivity, stand age, and management intensity. The establishment of data sets and statistical models across a variety of forest sites should account for the changing influence of soil carbon levels, aboveground biomass, microbial activity, organic matter inputs, and root biomass on soil carbon dioxide efflux. / Master of Science

About 12% of earth’s peatlands have been drained for peat extraction or agriculture and turned peatlands into carbon sources with reduced biodiversity, water retention and downstream water quality. Rewetting is a strategy used to restore peatlands water table and peat forming vegetation, including Sphagnum spp. which are key species in facilitating water retention, peat- and carbon accumulation in bogs. Halmstad University and Sydvatten have been conducting a scientific study, including a one-year-baseline study on a drained bog in Halmstad, scheduled to be rewetted by ditch blocking. The collected data on bog vegetation in this thesis shall be used as baselines for the scientific study. The aim was to understand if rewetting increases the coverage of peat forming vegetation in drained bogs with the hypotheses that Sphagnum moss have higher degree of coverage in wet compared to drained bogs, and that the plant community in wet bogs are dominated by Sphagnum moss while the drained bog is dominated by brown moss. The estimated mean percent coverage of Sphagnum moss, brown moss (other Bryophytes), heather shrubs, sedges, and reeds was compared between the drained bog, scheduled to be rewetted to a wet bog where ditch clearing has not happened for the last 80 years. My result showed that brown mosses of woody species had a greater and dominant mean coverage at the drained bog, indicating a shift to forest vegetation following drainage. Reeds, sedges, and heathers showed no significant difference between sites. Sphagnum moss demonstrated a significantly higher mean coverage in the wet bog, dominating the vegetation. This reflects a typical bog succession, influenced by Sphagnum mosses capacity of outcompeting other plants. These findings support the hypothesis and indicate that within 80 years, there can be a shift to a peat forming-Sphagnum- dominated bog community in previously drained bogs, through ditch blocking.

The application of olivine to coastal areas is a proposed method of removing carbon dioxide from the atmosphere for climate change mitigation. Olivine is abundant and dissolves relatively fast, but it contains trace amounts of nickel (Ni), chromium (Cr), and cobalt (Co) which may be toxic to marine biota in cases of widespread coastal olivine spreading. Prior studies have suggested that Ni concentrations in marine sediments and/or the overlying water column due to olivine dissolution could be a limiting factor for its carbon capture potential. Therefore, it is critical to understand and model the processes affecting trace metal bioavailability after olivine application. This research used sand and sediments collected from a natural olivine beach (Papakōlea) and a black sand control beach (Richardson) in Hawaii to measure the adsorption of Ni, Cr, and Co to suspended particulate matter (SPM) in the water column and to beach sediments in equilibrium with pore water. The experimentally derived adsorption isotherms were then used for phase distribution modeling in the water column and sediment pore water at both sites. Cr was observed to readily precipitate in seawater without suspended solids, meaning its exposure pathway for marine organisms will likely be via sediment, regardless of interactions with solid phases. Co uptake from solution may have been influenced by biological processes based on its continuous adsorption over 30 days, but more study ofcobalt adsorption to SPM is required because of conflicting results in a repeated experiment. Thus, Ni was the focus of the phase distribution modeling in this work. Ni adsorption from seawater to SPM generated from both Papakōlea and Richardson sediments followed Langmuir adsorption models. Parameters for Ni adsorption to SPM from Papakōlea at pH 7.81 were KL = 2.74 L/kg and qmax = 931 mg/kg and for Richardson SPM at pH 8.00 they were KL = 5.69 L/kg and qmax = 1446 mg/kg. Ni adsorption to SPM was strongly affected by pH with the qmax for Richardson SPM nearly eight times greater at pH 8.00 than at pH 7.77. Ni adsorption to Papakōlea SPM was five times greater than Ni adsorption to Richardson SPM at comparable pH. Ni adsorption to beach sediments from both sites was measured for five pHs between 7.27 and 8.73. Ni adsorption was observed to be strongly affected by pH and sediment type. A significant adsorption edge was observed for the Papakōlea sediment between pH 8.00 and 8.22, while a gradual increase in adsorption was observed between pH 7.27 and pH 8.15 for the Richardson sediment. Ni adsorption to the beach sediments from pore water at the typical seawater pH of 8.05 was calculated by interpolation between adsorption models at surrounding pH values. Calculated Ni adsorption to Papakōlea sediment at pH 8.05 was linear with Kd = 22.4 L/kg while Ni adsorption to Richardson sediment at pH 8.05 followed a Langmuir model with KL = 0.8 L/kg and qmax = 179 mg/kg. Phase distribution models constructed with the experimentally derived adsorption isotherms predicted that over 85% of the Ni in the water column is dissolved. This result was similar for the water columns at both beaches and was based on typical coastal total suspended solids (TSS) concentrations (5-20 mg/L). Therefore, it is predicted that transport of Ni into marine sediments by SPM settling is much smaller than bulk transport of dissolved Ni into the open ocean. In contrast, the pore water models predict that over 95% of total Ni is adsorbed to the solid phase for both sediments. In a scenario where dissolved Ni concentration in the pore water is the maximum safe level of 8.2 ppb (US EPA environmental quality standard; EQS), Ni adsorbed to the sediment at both sites is predicted to be less than 10% of safe levels, the Florida Department of Environmental Protection’s threshold exposure limit (TEL) of 15.9 mg Ni per kg of sediment. These adsorbed Ni concentrations are likely a better indicator of threshold sediment Ni concentrations because presumably Ni adsorbed to sediments is more readily bioavailable than Ni in the structure of the olivine. In this case, dissolved Ni would be of more environmental concern than Ni in seabed sediments at sites of olivine enrichment. However, it will be important to investigate the bioavailability of Ni directly from the olivine structure to confirm this conclusion. If dissolved Ni concentration in the pore water is the limiting factor for safe application of olivine, then olivine loading rates should be based on site-specific conditions (mixing regime and the residence time of seawater in the sediment pores) to maintain a dissolved Ni concentration less than the EQS. For Papakōlea Beach, with 70% olivine in thesediments, the dissolved Ni concentrations in the pore waters were measured to be at background seawater concentrations. This is likely because of the rapid mixing and high- energy wave action at this beach. Under these conditions, very little Ni would be adsorbed to the sediments. Additional site-specific studies of Ni and Co adsorption to beach sediments should be conducted to gain a more complete understanding of the fate and transport of these trace metals and the risks posed to coastal ecosystems by their release. More experiments are needed to characterize Co adsorption in seawater to SPM and beach sediment. Additionally, Ni adsorption experiments should be performed on a wider variety of beach sediments to estimate its fate and transport at specific locations of potential olivine enrichment. Also, Ni adsorption to Papakōlea SPM was measured at pH 7.81, and since adsorption is expected to be much greater at seawater pH, the Ni adsorption experiment should be repeated at a pH greater than that of seawater to allow the construction of adsorption isotherms for Papakōlea SPM at seawater pH by interpolation. Additionally, experiments need to be conducted to determine the bioavailability of trace metals in the olivine itself and adsorbed to the olivine.

Compost application to rangelands has the potential to sequester carbon (C) and add essential plant nutrients to the soil. The California Department of Food and Agriculture's (CDFA) Healthy Soils Project (HSP) provides financial support to farmers and landowners to implement innovative practices that promote soil health. The CDFA is currently recommending compost application rates of 6-10 tons per acre; however, previous research suggests that degraded soils may require a larger dose of compost to overcome limitations, therefore this recommendation might not meet soil health or soil carbon sequestration objectives. This study examines the compost rate effects on soil health, while also utilizing a comparison between soils with differing ages but similar environmental factors through the use of a rangeland chronosequence. Previous studies lack the combination of rate comparisons paired with soil development. Compost was applied at rates of 0, 10, 20, and 30 tons/acre across the two marine terraces, T1 and T2. Terrace one (T1) is the less developed sandy loam, approximately 50,000 years old, and terrace two (T2) is the more developed sandy clay loam soil, approximately 120,000 years old. The interactions between the treatment and pre-existing mineral soil properties were examined to quantify the mechanisms behind C accrual and soil health on degraded soils. A randomized block design was utilized with 4 blocks per terrace, each 1-acre block containing each of the four treatments (Control, Low, Moderate, High). Carbon sequestration was measured by testing soil GHG emissions as well as various pools of C within the soil such as total soil carbon (TC), labile soil carbon (POXC), and mineralizable carbon (Min C). Soil health factors were analyzed through measuring soil cations (Mg2+, Ca2+, Na+, K+), micronutrient/heavy metal availability (Znex, Mnex, Feex, Cuex), phosphorous (Olsen P), soil pH, total nitrogen (N) mineralization of nitrogen (PMN). Soil physical properties such as aggregate stability, water holding capacity (WHC), bulk density (Db), and aboveground biomass were also measured. Pre-existing site characteristics such as amorphous iron and aluminum oxides (Fe/Al-oxides) were examined as possible mechanisms for C storage. Data was analyzed via ANOVA and Tukey HSD mean separation to test significance. Linear mixed and mixed effects models were created to evaluate significance of site characteristics and assess which characteristic drives variability in soil C across the terraces. Year one results show a statistically significant increase in percent carbon (TC) and labile carbon (POXC) in the top 5 cm of T2 between the 30 ton/acre treatment compared to 10 ton/acre treatment and the control. Similarly, levels of extractable Ca2+, K+, and Mg2+ were significantly higher in the plots with 30 t/acre of compost compared to the control plots in T2, as well as for Kex, in T1. Finally, WHC significantly improved in the soil treated with 30 t/acre of compost compared to 10 t/acre in T2, and Db significantly improved in the soil treated with 30 t/acre of compost compared to the control in T2. One-year post-application, soil C, soil mineralogy/health, and soil physical properties significantly increased and/or improved when treated with the high 30 t/acre compost levels compared to the low and/or control treatments. Two years after compost application, we see similar results with increased TC, Caex, and Mgex in the high application rates compared to the low and control in T2, and we also see the emergence of increased total nitrogen (TN) and extractable Znex in the 30 t/acre treatment plots compared to the 10 t/acre and control plots in T2. However, two years post-application, POXC, WHC, and Db now longer showed significant differences between any rates in T2, though they each appeared to follow the same trend. Interestingly, results three years post-application showed continued TC and TN, Ca2+ and Mg2+ and Znex significance in the 30 t/acre treated plots compared to the low 10 t/acre plots in T2. Furthermore, TC, Min C, and TN all significantly increased in the 30 t/acre treatment plots in 2023 compared to the level’s measures in the 30 t/acre plots in 2021, suggesting continued C-sequestration and soil health benefits up to three years after a single compost application. Other soil health components such as POXC, extractable cations (K+, Ca2+, Na+, and Mg2+), Znex and Cuex, did not continue to increase into year three, but rather remained constant or slightly decreased, indicating an initial spike in nutrients immediately after compost application, followed by a decline back to “normal” values for some aspects of soil health. However, Alox did emerge as significantly higher under the 30 t/acre treatment compared to the 10 t/acre treatment in T2 in year three and showed a trend towards increasing levels of Alox between 2021 and 2023. This could indicate a lag in the effects of compost on the soil, with some nutrients emerging as significant three years after compost application. An analysis of correlation between C content (TC, Min C, and POXC) and mineralogical properties (Fe/Al-oxides, clay percent) and the compost treatment levels were determined using linear mixed-effects models (MEM). Across all three years, the linear MEM showed that Feox, Alox, and clay percent were the main predictors of TC storage, with Alox showing the strongest effect, while compost treatment was significant, but had a smaller effect size. For Min C, the MEM shows Alox is the most significant predictor across all years, but an R2 of only 0.18 suggests that factors not included in the model, or year-specific conditions, are also affecting MinC. The MEM for POXC shows that Feox, Alox and clay impact POXC in 2021, with Feox influencing POXC across three years. No significant treatment effects were observed on amorphous iron (Feox) or clay content on either terrace in any year, meanwhile Alox levels significantly increased with increasing compost application in 2022 and 2023. between terraces in 2022 and 2023, with T2 showing higher levels compared to T1. The linear MEM results indicate that Feox, clay percent, and Alox all significantly predict C storage within the soil after accounting for compost treatments. Since compost directly affects Alox, it is likely that compost and Alox are collinear, and thus compost indirectly influences TC through increasing Alox. In 2021, Feox and clay percent solely predict C storage, by 2023 Alox emerges as the most significant predictor of C storage. This collinearity may be attributed to the release of Alox into the soil from compost treatments. Alox is both a mediator through which compost influences C, and still a valid, strong predictor of TC storage. The findings from this analysis indicate 1) an application rate of 30 tons/acre is more effective at sequestering C and improving soil health over the traditional 10 tons/acre, 2) pre-existing site characteristics and differences in pedogenic soil development (Alox and Feox and clay percent) are the key factors modulating soil health outcomes from compost application, and 3) continued C benefits across multiple years may be realized after a one-time application.

The built environment must innovate and adopt new materials and construction practices in order to meet current and forecasted environmental challenges, economic uncertainties and construction pressures. The specification of mass timber materials and building assemblies will play a major role in addressing these issues. The objectives of this research are fourfold: 1) Develop a deeper understanding among construction professionals of the role mass timber buildings can have in greatly reducing CO2 emissions through the use of renewable forest products and the storage of carbon in buildings; 2) Provide insights into the utilization of mass timber products for architectural application that advance environmental sustainability – while moving toward continued industry acceptance and parity with other well-known structural materials (steel and concrete); 3) Expand current knowledge among architects, builders and developers of mass timber construction by examining and addressing the real-life challenges and benefits of mass timber implementation – including the environmental impacts, economic drivers and construction practices that promote architectural adoption; 4) Educate the construction industry to better understand the real “value” of mass timber construction and how best to implement mass timber products. Furthermore, the outcomes of this research will convey valuable information for future research that explores the architectural and environmental benefits associated with the implementation of mass timber; and can serve as a valuable tool for additional studies on how the construction industry might further innovate and evolve to meet the pressing demands of building development. The accomplish these research objectives, this dissertation will be divided into five sections: 1) Introduction; 2) Carbon matters: Evaluating the aggregated impact of sequestered carbon from projects in a mass timber architecture design studio; 3) Pioneering mass timber in Mississippi: Lessons learned and the carbon story of the Lost Rabbit mixed-use development; 4) Pioneering mass timber in Utah: Best practices, lessons learned and the carbon story of the Baltic Pointe commercial office building; and 5) Conclusion.

With rising concentrations of CO₂ in the Earth's atmosphere causing concern about climate change, many solutions are being presented to decrease emissions. One of the proposed solutions is to sequester excess CO₂ in geological formations such as basalt. The deep subsurface is known to harbor much of the microbial biomass on earth and questions abound as to how this deep life is going to respond to the injection of CO₂. Many studies have used model microorganisms to demonstrate the ability of microbes to aid in the safe, permanent sequestration of CO₂ in the subsurface. The objective of this research is to characterize the microbial community present in the basalts at the Wallula pilot carbon sequestration well prior to the injection of CO₂ and then perform laboratory studies to determine how the native microbial community will respond to carbon sequestration conditions. Six samples were collected from the Wallula pilot well prior to the injection of CO₂ into the system. The microorganisms in these samples were characterized by pyrosequencing of 16S rRNA genes, revealing a community dominated by the Proteobacteria, Firmicutes, and Actinobacteria. The organisms detected were related to microbes known to metabolize hydrogen, sulfur, and single carbon compounds. These microorganisms may be stimulated in formations located at the fringe of the pool of injected CO₂. Laboratory studies revealed that the native microbial community suffered a two order of magnitude loss of population upon exposure to CO₂ under carbon sequestration conditions. The community also shifted from being dominated by Proteobacteria prior to CO₂ exposure to being dominated by Firmicutes after exposure. Specifically, the genus Alkaliphilus, which was previously undetected, appeared after CO₂ exposure and became dominant. The dominance of Alkaliphilus, along with other rare organisms which did not compose a majority of the population prior to the introduction of CO₂ to the system, indicates that members of the rare biosphere may be better adapted to changing environmental conditions specific to CO₂ sequestration than other indigenous cells. Thus, the rare biosphere should be examined closely as part of any environmental study, as these minority microorganisms may be the first indication of perturbation or impact. / Graduation date: 2013