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<p> The vegetational colonization and development preceding the establishment of lichen-heath was examined on a Hudson Bay coastal raised-beach system. A continuous and directional developmental sequence of approximately 200 years was quantified on both a coastal intraridge sample sequence and on an inland interridge sample sequence. Increasing gradients of elevation, soil peat thickness and soil organic matter coincide with the vegetational development, however no appreciable changes in soil pH or concentrations of available nutrients were detected and it is concluded that these parameters have little influence on the development of lichen-heath at this site. Community composition over the ridge profile forms a second major vegetational gradient which appears to be affected primarily by environmental factors related to ridge morphology and orientation. The interactions of environmental factors in the development of lichen-heath are discussed.</p> / Thesis / Master of Science (MSc)

Mercury (Hg) cannot be degraded. Therefore only two principal processes are available for the treatment of Hg-contaminated soil: (1) the separation of Hg from the soil or (2) the stabilisation of Hg within the soil. Prior to selecting a suitable treatment technique, it is necessary to have an understanding of Hg behaviour in contaminated soil, i.e., distribution in particle size fractions, dissolution at different pH and in the presence of chlorides, and mobilisation using various extractants. The thesis aims to evaluate the potential for applying soil washing to decontaminate the Hg-contaminated soil. The Hg contamination originated from inappropriate waste disposal, chlor-alkali process and harbour activities, and the soil was also polluted by other trace elements, i.e., Zn, Cu and Pb, etc. The soil was fractionated from fine to coarse particles to study the effectiveness of physical separation. A pH-static titration ranging from pH 3 to 11 was performed to assess the mobility of Hg in response to pH changes. The chloride influence on Hg mobilisation was studied using an HCl solution of different concentrations as the leachant. Batch leaching tests were used to evaluate Hg solubility in water, and extraction efficiency by various extractants. The extractants derived from wastes were acidogenic leachates generated from biodegradable wastes, and alkaline leachates produced from fly/bottom ashes. The studied soil consisted of dominant coarse-grained fractions, which is usually suitable for particle size separation. However, dry sieving has been shown to be insufficient to separate clean from contaminated soil fractions although the Hg concentrations decreased with increasing particle sizes. The reasons are likely to be: (i) the physical attachment of fines to coarse particles; (ii) the strong chemical bond of soil organic matter (OM) and minerals for Hg. Distilled water could barely mobilise the Hg from the soil, most likely due to firm chemical bonding between the soil and Hg. Despite the fact that enhanced Hg dissolution was observed at pH 5 and 11 in this study, soil washing by pH adjustment was insufficient for Hg removal. The introduction of chlorides did not facilitate the Hg mobilisation either. Retention of Hg in the soil by OM seemed to be predominant over Hg mobilisation by chlorides. Chemical extraction by leachates from wastes as well as EDTA solution and NaOH solutions showed that neither alkaline nor acidic leachates could facilitate Hg removal from the soil. Mercury was firmly bound in the soil matrix and no more than 1.5% of the total Hg could be removed by any of the tested extractants. Future research should therefore focus on the development of Hg immobilisation techniques.

At ~662 gigatonnes of carbon (GtC), marine dissolved organic matter (DOM) is the largest reduced pool of actively cycling carbon and nitrogen in the oceans1. Operationally defined as smaller than 0.1µm in size, this carbon reservoir comprises all non-living organic matter smaller than a bacterial cell and comprises organic colloids and molecules spanning as a continuum of sizes ranging from marine viruses and large macromolecules (e.g. DNA, enzymes) to small organic molecules (e.g. polymers and monomers)2. With deep apparent 14C-ages ranging between 4900-6400 ybp 3,4, marine DOM is anomalously old given timescales of global ocean ventilation (1000-1500 years). The great age of DOM has remained one of the most elusive lines of scientific inquiry in Chemical Oceanography for decades. The size and molecular composition of DOM has been shown to be a key variable in determining its biological reactivity (e.g. cycling rate) and long-term persistence in the deep ocean5,6. Despite the importance of DOM in the marine carbon and nitrogen cycles, we lack a detailed understanding of the molecular composition of DOM. Due to the high concentration of salts in seawater relative to DOM, it is difficult to analyze the molecular composition of seawater with conventional chemical- or size- fractionation methods without introducing bias (i.e. isolating only hydrophobic and/or high molecular weight DOM). In fact, it is commonly reported that >80% of DOM remains uncharacterized at the molecular level (e.g. not readily identifiable as an individual known biomolecule)5. Nuclear magnetic resonance (NMR) spectroscopy has been used as a tool for several decades to describe the composition of marine DOM isolates7. For example, 13C-NMR of major high molecular weight DOM functional groups at the molecular-level demonstrated that DOM is largely made up of reactive polysaccharides with low aromaticity compared to terrestrial DOM8. To date, all marine DOM NMR measurements have been made on size-fractionated DOM or chemically-fractionated (e.g. solid phase extracted) DOM isolates. In this thesis, I report the first Proton (1H) NMR composition of total seawater DOM from seawater samples collected from 10 stations in Baffin Bay aboard the CCGS Amundsen (2019). Samples were measured using 1H-NMR at uOttawa following a novel water suppression method established by Lam and Simpson9. The use of this method has allowed for the first molecular composition assessment of total seawater DOM to be measured (e.g. without any chemical or size fractionation). I report the % relative abundance of individual biomarkers and determine molar concentrations of two compound classes of interest. These results are shown in Ocean Data View section plots, and are listed within appendix tables, to provide a comprehensive depiction of the changing concentrations of dissolved organic carbon (DOC), total carbohydrates (TCHO), and carboxyl-rich alicyclic molecules (CRAM). In this thesis, I explore changes in the abundance of these unique DOM compound classes and discuss how the composition of DOM directly determines its bioavailability and thus cycling in Baffin Bay 5. The core objective of my thesis was to measure DOM concentrations for TCHO and CRAM, as well as to calculate the production and removal of these key DOM compounds in Baffin Bay due to either physical and/or biological processes. We found that the concentration of both TCHO and CRAM decreased with depth throughout Baffin Bay. This is consistent with previous work suggesting the rapid cycling of carbohydrates, however it contradicts the current paradigm of CRAM cycling. Our results indicate between 21-43% of CRAM produced in the surface is subsequently removed at depth. Rapid cycling of a surface CRAM population suggests that not all CRAM can be considered recalcitrant DOM We live in a time of unprecedented global change. The Arctic Ocean is warming at a rate at least four times faster than the global average10. The impact of a rapidly warming, freshening and increasingly acidified Arctic Ocean on the biogeochemistry of DOM remains unknown. It is imperative that more DOM research be conducted as early as possible in order to better understand these impacts and inform future research directions. The distribution and cycling of CRAM in Baffin Bay provide novel and fundamental knowledge of DOM cycling in a key Arctic region, but could also potentially occur throughout the global ocean. Such data will no doubt be of use in informing future iterations of Earth System Climate models seeking to forecast how the marine carbon cycle will respond to global change.

京都大学 / 新制・課程博士 / 博士(農学) / 甲第24325号 / 農博第2530号 / 新制||農||1096(附属図書館) / 学位論文||R5||N5427(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 德地 直子, 教授 柴田 昌三, 教授 舘野 隆之輔 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

The aim of this thesis was the experimental evaluation of thermogravimetry (TG) to assess the status of organic matter supply in agricultural soils. TG is an innovative analytical method for recording thermal mass losses (TML) during heating of soil samples from room temperature to 950 °C. The determination of TML in 10 °C temperature increments (TG indicators) is a central method of TG data evaluation. There is a very close correlation between selected temperature ranges and classically determined soil properties (organic carbon, total nitrogen and clay content). The regression parameters of these relationships can be used to estimate soil properties and to assess the quality of SOM.:List of Tables VI List of Figures VII List of Abbreviations VIII Summary 10 Zusammenfassung 13 Chapter One – Synthesis: Thermogravimetry – a promising technique to assess the status of organic matter supply in agricultural soils 16 1 Introduction 16 1.1 Soils and agriculture 16 1.2 The Importance of soil organic matter (SOM) 17 1.3 Current challenges in the assessment of SOM as an indicator of soil quality 18 1.4 Main objectives 20 2 Methodological Approach 22 2.1 General approach 22 2.2 Experimental areas and soil description 22 2.3 Application of thermogravimetric analysis (TG) 28 2.4 Experimental design 29 2.4.1 SOC content determination using TML (chapter two and chapter five) 29 2.4.2 Detectability of thermal stabilities of organic amendments in soil samples using TML (chapter two) 30 2.4.3 Comparison between biological and thermal stability of SOM (chapter two and chapter three) 30 2.4.4 Linking thermogravimetric data with soil properties, thermal stability of SOM and SOC fractions (chapter four and chapter five) 31 3 Results and Discussion 32 3.1 Thermogravimetric-based fingerprint predictions of soil properties and soil organic matter stability (chapter two and chapter three) 32 3.2 Linking thermogravimetric indicators with functional SOC fractions to assess SOM quality (chapter four and chapter five) 35 4. Research needs and perspectives 37 5. Conclusion 40 References 40 Chapter Two: Contribution of organic amendments to soil organic matter detected by thermogravimetry 51 Chapter Three: Detectability of degradable organic matter in agricultural soils by thermogravimetry 52 Chapter Four: Linking soil organic matter thermal stability with contents of clay, bound water, organic carbon and nitrogen 53 Chapter Five: Linking thermogravimetric data with soil organic carbon fractions 54 Appendix 55 List of publications 55 Acknowledgments 56

Oyster reefs in the western Mississippi Sound (WMS) are dependent on the salinity moderation by freshwater input. However, freshwater brings in high amount of pollutants, which affect the oysters negatively. Oyster diebacks happened as a result of hypoxia caused by excessive organic matter input to WMS in summer 2017. Colored dissolved organic matter (CDOM) is widely used as a proxy for determining organic matter distribution. In this study, hyperspectral and multispectral remote sensing data collected using unmanned aerial systems and in situ CDOM data were used to develop algorithms in order to retrieve CDOM remotely. Collected physical and biogeochemical parameters were used to understand the carbon fluxes regulating the quality and quantity of CDOM. Developed algorithms showed high accuracy after accounting for seasonal variations of CDOM. Further, seasonal induced photodegradation, photosynthesis, calcification, and exchange of CO2 were identified as possible factors that affect the carbon dynamics in the study area.

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