Black carbon (BC), a stable form of organic carbon (OC), is a byproduct of the incomplete combustion of biomass, biofuels, and fossil fuel. The main objectives of this research are to examine the spatial distribution of OC and BC in urban soil and determine the influence of tree canopy cover and landscape maintenance on soil carbon accumulation. Soil sampling was conducted at 29 sites throughout the City of Denton, Texas, in May 2019. Samples were collected from underneath post oak canopies and in adjacent open areas and were analyzed for total carbon (TC), total organic carbon (TOC), total N (TN), C:N ratio, and BC. Although maintenance levels had no significant effect, TOC was greater underneath trees (5.47%, 5.30 kg/m2) than lawns (3.58%, 4.84 kg/m2) at the surface 0-10 cm. Total nitrogen concentration was also greater underneath trees (0.43%) than lawns (0.31%) at the surface 0-10 cm. Preliminary results for BC were closely correlated to TOC. The lack of difference in C:N ratio between cover types indicates that leaf litter quality may not be the primary driving factor in soil C and N accumulation. Instead, differences in soil properties may be best explained by manual C inputs and greater atmospheric deposition of C and N to soils with tree canopy cover. Identifying patterns and potential drivers of soil OC and BC accumulation is important because soil carbon sequestration not only reduces atmospheric CO2, but also may provide additional pollution mitigation benefits, thereby contributing to a more sustainable urban environment.

The Red Sea is an arid environment, without riverine inputs, oligotrophic waters and extreme temperature and salinity. Avicennia marina is the dominant vegetation in the shores of the Red Sea. However, little is known about their distribution, dynamics, and services. Therefore, the aim of this Ph.D. was to obtain the basic information needed to evaluate their role in the coastal ecosystems and quantify their services. With that objective we 1) estimated the past and present distribution of mangroves in the Red Sea, 2) investigated the growth, leave production and floration 3) examined the growth limiting factors 4) measured the nutrients and heavy metal dynamics in the leaves and 5) estimated carbon sequestration. We found an increase of about 12% in the last 41 years, which contrasts with global trends of decrease. The extreme conditions in the Red Sea contributed to limit their growth resulting in stunted trees. Hence, we surveyed Central Red Sea mangroves to estimate their node production with an average of 9.59 node y-1 then converted that number into time to have a plastochrone interval of 38 days. As mangroves are taller in the southern Red Sea where both temperature and nutrients are higher than the Central Red Sea, we assessed nutrient status Avicennia marina propagules and naturally growing leaves to find the leaves low in nutrient concentrations (N < 1.5 %, P < 0.09 %, Fe < 0.06) and that nutrients are reabsorbed before shedding the leaves (69%, 72% and 35% for N, P, and Fe respectively). As a result, we conducted a fertilization experiment (N, P, Fe and combinations) to find that iron additions alone led to significant growth responses. Moreover, we estimated their leaf production and used our previous estimates of both the total cover mangrove in the Red Sea along with plastochrone interval to assess their total nutrients flux per year to be 2414 t N, 139 t P and 98 t Fe. We found them to sequester 34 g m-2 y-1, which imply 4590 tons of carbon sequestered per year for the total mangroves covered by the Red Sea.

The increasing concentration of CO2 in the atmosphere and the rapidly growing amount of waste (industrial and electronic) are two major environmental challenges faced by humanity today. Carbon capture, storage, and utilization (CCUS) aims to address the CO2 challenge and has been shown to be a promising means of CO2 mitigation. For carbon capture, amine scrubbing is an example of an effective means to separate CO2 from other gases, particularly natural gas and hydrogen. Carbon storage entails the injection of CO2 into natural geologic formations, such as basalt, to form permanent, harmless carbonates. Lastly, carbon utilization involves conversion of carbon to chemicals and fuels through a variety of pathways, such as carbon mineralization. Many large-scale projects on CCUS have been conducted, with ongoing research in the aforementioned areas of CCUS. The first half of this dissertation addresses carbon storage and utilization, specifically focusing on carbon mineralization, in order to evaluate the potential for CO2 storage in basalt and CO2 utilization in the transformation of industrial waste to valuable carbonates. The mounting amount of electronic waste (e-waste) presents a significant challenge in the flow of valuable elements, especially as it relates to the materials cycle. E-waste contains valuable metals, such as copper, gold, silver, iron, and nickel, and contains much higher amounts of these metals than the amounts found in ores. Thus, the recycling of metals from e-waste is favorable and has gained attention over the last few years. E-waste is a complex mixture of metals, plastics, and refractory materials. The brominated flame retardants in the e-waste are of particular concern as they become hazardous when burned. Lead is also often found in the solder material of e-waste. The risks associated with the toxic and hazardous components of e-waste, along with the heterogeneity in composition, challenge the development of recycling and processing methods for e-waste. While recent developments, such as hydrometallurgy i.e. chemical leaching, have lessened the hazards during processing, pyrometallurgical techniques, which involve smelting, remain the most commonly used treatment. Metal extraction and recovery processes are multi-step techniques that usually involve energy-intensive mechanical processing, and depending on the type of waste, the selectivity of metal separation processes can be quite low. Specifically, for Lithium-ion batteries (LIB), the majority of recycling techniques cannot recover Co and Ni simultaneously. The latter half of this dissertation explores new, sustainable separation processes for the recovery of metals from e-waste, Printed circuit boards (PCB) and LIB, via morphological changes induced by supercritical CO2 and via electrochemical techniques. Chapter 2 presents an evaluation of the potential of sub-seafloor basalt in the Cascadia Basin offshore Washington State and British Columbia for CO2 storage. Basalt samples from the Cascadia Basin were tested for the extraction of Ca, Mg, and Fe to assess the ability of the basalt to form carbonates under the experimental conditions of injection with CO2. Combining laboratory results with modeling studies from collaborators, and comparisons to existing data on the reactivity of oceanic basalt demonstrated that the basalt formations in the Cascadia Basin are a feasible option for large-scale, permanent CO2 storage. In Chapter 3, the reaction of CO2 and industrial waste for Ca and Mg extraction, is investigated in greater detail in the tailored synthesis of high purity precipitate calcium carbonate (PCC) from slag. Different ligands were studied for the extraction of Ca and Mg and various experimental conditions, such as heating, controlling the pH, and bubbling with air vs. CO2 were studied for the formation of calcium carbonates from the steel slag. A novel synthesis method involving the dissolution of the slag using ligands, heating, and precipitation via bubbling with air or CO2 using the Ca-rich solution derived from dissolution, was developed. High purity PCC was successfully produced, making the proposed synthesis process a promising pathway for carbon management and sustainable waste transformation. In Chapter 4, a critical review of current metal extraction and recovery techniques for the treatment and processing of electronic waste is presented. The complexity of e-waste requires the development of new metallurgical processes that can separate and extract metals from unconventional components such as plastics and a wide range of metals. This chapter focuses on the science and engineering of both conventional and innovative separation and recovery technologies for e-waste with special attention given to the overall sustainability. Physical separation processes, including disassembly and magnetic separation, as well as thermal treatment of the polymeric component, such as pyrolysis, are discussed for the separation of metals and non- metals from e-waste. The subsequent metal recovery processes through pyrometallurgy, hydrometallurgy, and biometallurgy are also discussed in depth. Finally, insights on future research towards sustainable treatment and recovery of e-waste are highlighted, including the use of supercritical CO2. Chapter 5 investigates the use of supercritical CO2 for the extraction of metals from electronic waste, specifically Printed circuit boards (PCB). The complexity of PCB was first simplified by synthesizing laminate polymer and metal “model PCB” samples, where the polymer component was polycarbonate (PC) and the metal component was Cu foil. Through controlled studies of the effect of supercritical CO2 (scCO2) and sulfuric acid on the model PCB samples, a thorough understanding of the role of CO2 in the supercritical CO2/co-solvent system was developed. The scCO2/co-solvent system was found to induce permanent, morphological changes in the samples in just 30 minutes. Building on these results, a two-step metal extraction process for waste PCB was proposed. First, the pre-treatment of small pieces of waste PCB with scCO2 and sulfuric acid, and second, chemical leaching at ambient temperature and pressure in a sulfuric acid and hydrogen peroxide solution. This process was demonstrated to yield ~80% Cu extraction in under four hours, without the need for vigorous and energy-intensive mechanical processing, as the starting materials were small pieces of waste PCB, neither shredded nor crushed. The final part of the thesis presents a study on the electrochemical recovery of Co and Ni from spent Lithium-ion batteries (LIB). Galvanostatic deposition and stripping of the metals were performed using a sulfuric acid-based electrolyte with concentrations of Co and Ni based upon waste LIB solution. A complexing agent, specifically EDTA, was introduced into the electrolyte to selectively deposit one metal over the other. The concentration of EDTA was maintained at the concentration of Co and Ni in the solution, and the pH values of the solution were varied to study the effect of pH on the ratio of Co/Ni in the deposit. In the presence of EDTA, the pH of the solution had a significant impact on the ratio of Co/Ni, making the electrochemical process presented in this study an effective, sustainable approach to simultaneous and tunable metal recovery from waste LIBs.

Fluid-rock interaction causes an exchange of isotopes or elements through various reactions. The rate of these reactions strongly depends on temperature. The interaction involves dissolution precipitation, chemical exchange reactions, redox reactions, diffusion, and their combinations. The goal of studying fluid-rock interaction is to understand the change in mineral chemistry of the rock materials when in contact with an aqueous solution. These processes occur in all regions of the Earth where aqueous solutions are found. This work is comprised of three independent studies which provide an understanding about crystallization processes under multiple hydrothermal conditions with geological and environmental applications. In the chapter 1, subsurface rock and CO2-saturated brine reactions were evaluated under laboratory hydrothermal conditions when injected carbon dioxide is in contact with sedimentary strata at a planned sequestration sites at Kemper County Mississippi. Five rock samples were taken from different depths using core cuttings for experimentation. The results reveal no reaction of clay particles and CO2-rich fluid; in contrast, in samples from the depth of the unconformity, significant formation of secondary minerals occurred by reaction with the rock sample at the unconformity. The second study focuses on the incorporation of uranium (VI) into the crystal lattice of calcite at hydrothermal conditions. This study was designed to understand uranium (VI) behaviors in a calcite-fluid system at elevated temperatures due to decay of radioactive waste from nuclear power plants. The results showed uranyl hydroxide formation was preferred at hydrothermal conditions, 120 – 350 oC. The incorporation of U6+ in calcite lattices was evaluated, though the data showed a limited amount of U6+ entrapment. The third study focuses on quantification of the retention of Mg/Ca, Sr/Ca, and d18O during the aragonite-calcite transformation process as well as evaluation of the transformation rate. The results show partial retention of Mg and Sr during aragonite transformation to calcite in Mg-, Sr-free solutions, but no retention of d18O. Aragonite oxygen isotope composition was erased during mineral transformation because fractionation was controlled by temperature and the d18O of the bulk solution.

No description available.

Planned grazing management in rangelands may improve carbon sequestration potential of soils by increasing plant biomass and the rate of nutrient cycling, which might mitigate global warming. The effects of high-intensity, short-duration planned grazing of sheep on several soil and ecosystem properties were investigated on a mixed grassland in San Luis Obispo, CA. The objectives of this study were to (a) identify soil properties related to soil C sequestration in rangelands; (b) determine if planned grazing improved soil carbon sequestration; (c) quantify changes in identified variables in grazed and rested plots; and (d) analyze any changes in plant species composition attributable to grazing. Total rest exclosures and short-duration grazing by sheep at average stocking densities of 115,000 pounds per acre were applied at two sites with clay-loam soils: a rangeland site that had been rested for over 50 years (REX), and an adjacent site that was previously rested for over 50 years, and subsequently grazed for six years (GR). Bare soil, live plants, plant litter, and perennial and annual plant densities were not different between sites. Soil organic carbon (SOC) was higher at the GR site, but total nitrogen was not different between sites, resulting in higher C:N ratios at the GR site. Soil pH was lower at the GR site, moisture was higher at the GR site, and bulk density and aggregate stability were not different between sites. There was a higher incidence of black soils at the REX site, suggesting perhaps a difference in soil mineralogy which may impact SOC. Treatment did not have an effect on any of the variables investigated except perennial plant diversity, in which grazed plots had lower species diversity than rested plots. Site aspect may have an effect on the results, as the GR site was northwest-facing while the REX site was south-facing. It is possible that higher SOC at the GR site is due to topography, rather than grazing management. Further investigation is required, but if grazing can be used in California as a strategy for increasing soil carbon sequestration, the rates of desertification may be slowed and damage caused to the ecosystem by global warming may be reduced.

An enhanced coal-bed methane facility in Russell County, Virginia is targeting lower Pennsylvanian coals for CO2 storage, but the shallow sandstone units intercalated with the coals may also prove to be potential CO2 reservoirs, since the injection apparatus is already in place. Using samples from a continuous core in southwestern Virginia, this detailed review of the petrography and local volume of the Breathitt Formation sandstone units examines their diagenetic alterations in order to assess the units' reservoir quality. The high-frequency sequences of immature sandstones, heterolithics, shales and coals in Russell County represent deposits from the transverse fluvial facies association of a broad braided-fluvial drainage system in the central Appalachian Basin. The sandstone units within these sequences are laterally extensive, maintaining similar thickness and gamma ray signature across the study area. Lower Pennsylvanian sandstone units are consistently sublitharenite with a diagenetic mineral assemblage including siderite, chlorite, kaolinite, albite, illite, silica and calcite. Primary porosity is not preserved, but secondary porosity (5 ± 3.1 %) has developed at the expense of feldspars and unstable lithic fragments. Permeability assessments collected in Grimm (2010) measured impervious values (0.005-0.008mD) for the medium-coarse grained sublitharenites. At the temperatures and pressures present within these units, CO₂ is unlikely to react with either the primary or diagenetic mineralogy in a way that negatively impacts continued injection on human time scales. Low pore volume and permeability due to the timing of certain authigenic mineral emplacement are the main hindrance to reservoir quality. Lower Pennsylvanian sandstones are not viable potential reservoirs for carbon sequestration. / Master of Science

Carbon dioxide sequestration in coal-bed methane fields has potential to add significant recoverable reserves and extend the production life of coal-bed methane fields while at the same time providing a geologic sink for atmospheric greenhouse gases. The ability to relate the thickness, extent, and quality of coal seams to their relative position within a sequence is fundamental in determining the sequestration potential of a geologic formation. This thesis documents the carbon dioxide storage capacity and enhanced coalbed methane recovery of lower Pennsylvanian coal-bearing siliciclastic strata within the Bradshaw CBM field, southern McDowell County, WV. Analysis of outcrop, gamma ray and density logs, and eight cross-sections within the study area reveals a hierarchy of bounding discontinuities and architectural elements. Discontinuities are both erosional (unconformable) and depositional (condensed) surfaces of 3rd-order (~2.5 Ma) and 4th-order (~400 k.y.) origin. Architectural elements bound by 4th-order erosional discontinuities consist of upward-fining lowstand and transgressive incised valley fill, alluvial, and estuarine deposits, and upward-coarsening highstand deltaic deposits, representing 4th-order sequences. 4th-order sequences are stacked into composite 3rd-order sequences. Sequence development is attributed to higher frequency (~400 k.y.) 4th-order Milankovitch orbital eccentricity cycles superimposed on lower frequence (~2.5 Ma) orbital eccentricity cycles. Coal seams occur in the transgressive and highstand systems tracts, associated with 4th-order flooding surfaces and high-frequency deltaic autocycles, respectively. Transgressive coal-bed development is attributed to Milankovitch driven glacio-eustacy while highstand coal-bed development is attributed to autocyclic deltaic influences. Assessment of carbon dioxide storage capacity within coals of the lower Pennsylvanian Pocahontas and Bottom Creek formations in the Bradshaw CBM field indicates that 19 million tons of carbon dioxide can be sequestered. Sequestration of carbon dioxide within the Bradshaw CBM field has the potential to increase coal-bed methane recovery by as much as 52 billion cubic feet. / Master of Science

This study explores the biophysical potential and economic attractiveness of black spruce (Picea mariana) regeneration in eastern Canada under future climate changes. It integrates process-based ecosystem model simulated forest productivities from three major global climate models (GCMs), growth and yield formulations specific to black spruce and economic analyses to determine the overall investment value of black spruce, both including and excluding carbon sequestration benefits. Net present value (NPV) was estimated to represent the financial attractiveness of long-rotation forest plantations through time. It was assumed that stands would not be harvested at volumes less than 80 m3 ha-1. The price of stumpage was set to $20 m-3, stand establishment cost was set to $500 ha-1, and the discount rate was considered at 4%, with sensitivity analyses conducted around these assumptions. The growth and yield of black spruce was simulated for an extreme future climate scenario – IPCC-RCP 8.5. The results suggested a general North-South gradient in forest productivity where gross merchantable wood volumes increased with decreasing latitudes. This pattern was also observed in NPVs, with higher values projected for the southern portion of the study area. Based on the base economic assumptions and sensitivity analyses, study results suggested that black spruce plantations are not economically attractive, unless carbon sequestration benefits of at least $5 ton-1 CO2 are realized. Further sensitivity analyses showed that discount rate plays a significant role in determining the optimal harvest age and value. Furthermore, the optimal harvest rotation age increases with increasing carbon price by approximately 9 to 18 years. / Thesis / Master of Science (MSc)

The southern end of the Black Warrior Basin has been the site of limited drilling operations, but a critical need now exists to establish a greater understanding of the regional stratigraphy. The objectives of this study were to define a sequence stratigraphic framework for the southernmost Black Warrior Basin, to identify chronostratigraphic timelines within depositional environments, identify regional transgressive and high stand systems tracts. This information was used to identify three target reservoirs, characterize petrophysical properties, and confirm integrity of reservoir and seal formations for geologic storage. Methods include correlation of petrophysical well logs in the study area, well log analysis, as well as petrographic and core analyses. Five cycles were identified in well log cross sections. Sequence boundaries will be identified in both cross sections seismic data. Cretaceous sediments deposited above a regional sequence boundary above the Paleozoic that may represent as much as ~141 ma of erosion or non-deposition. The results of this study will contribute to development of a proposed geologic carbon sequestration facility in Kemper County, Mississippi.