Throughout the last glacial period, massive volumes of icebergs were discharged periodically from the Hudson Strait region during so-called Heinrich (H) events depositing sediments in distinct layers across the North Atlantic as they melted. The objective of this research was to measure and describe sedimentation associated with a meltwater plume discharged during the H1 ice-rafting event (14–19 ka) by examining sediment texture. The H1 layer was sampled in 11 piston cores that cover about 4000 km of the slope between Hudson Strait and the Bay of Fundy and range in water depth from 818–2740 m. Disaggregated inorganic grain size (DIGS) distributions were determined using a Coulter Counter. Additionally, carbonate content and the coarse fraction were measured and DIGS spectra were parameterized using an inverse ?oc model and sorted using entropy analysis. Results suggest that H1 layer sediments were mainly delivered by plume, ice-rafting and turbidity currents. In general, plume deposition was only significant proximally and distal sediments were mainly delivered by ice-rafting. However, the lack of plume deposited sediments distally does not necessarily imply the absence of a plume.

Organic matter which is insoluble in common solvents and non-oxidising acids often comprises the quantitatively most important fraction of organic matter in sediments. This operationally defined material is usually simply termed 'insoluble organic matter' (IOM) or 'kerogen' when it is isolated from ancient sediments. Indeed, kerogen is regarded as the most abundant form of carbon on the planet. The molecular character of this generic material has not been fully elucidated, principally because of its insolubility which limits instrumental methods of analysis to those applicable to solid substrates. This thesis describes the quantitative isolation of IOM from lacustrine and marine sediments and two species of methanogenic bacteria using a sequential isolation procedure. A range of synthetic IOMs (melanoidins) was also prepared. The dissolution of IOM and melanoidins obtained in this manner was then attempted using the acidic ionic liquid l-ethyl-3- methylimidazolium chloride-aluminium (III) chloride. Two synthetic dendrimers containing similar functional groups to those observed in sedimentary IOM were used to try and assess the mode of action of the ionic liquid. Ionic liquid treatment of the DCM soluble dendrimers resulted in the formation of 7 - 62 % of material that was no longer soluble in DCM, whilst the soluble components had been substantially altered. The ionic liquid was found to non-quantitatively promote ether cleavage, protonation and rearrangement reactions. IOM was isolated from lacustrine Rostherne Mere, UK, sediments (7 - 3 0 % dry weight), Kimmeridge Clay, Dorset (11 - 12 %) and methanogenic bacteria (Methanococcus jannaschii, 3 %; Methanobacterium thermoaiitotrophicum, 0.1 %) using a time-consuming isolation procedure involving over forty separate chemical manipulations. Monitoring of the sequential isolation of IOM and characterisation of the final isolates was carried out using solid-state NMR, IR, elemental analysis, pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), scanning electron microscopy, and the newer surface sensitive technique of time of flight-secondary ion mass spectrometry (ToF-SIMS). Less than 1 % of sedimentary IOM and 5 % of Kimmeridge Clay IOM was soluble in DCM following ionic liquid treatment, whilst alkyl chains were lost from the insoluble portion which also increased in aromaticity. The poor yield recovered following ionic liquid treatment of M. jannaschii IOM (5 %) was attributed to loss of volatile material during hydrolysis. Following ionic liquid treatment 93 - 96 % of the melanoidins remained insoluble in DCM although their character had been altered, becoming more condensed. This ionic liquid dissolution procedure has not provided the substantial progress in elucidating the molecular character of IOM promised by earlier reports.

published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

In 2005, box cores were collected throughout the Hudson Bay and Strait. A detailed micropaleontological data set has been generated from these cores for this study and is combined with geochemical and geochronological data to observe temporal and spatial oceanographic changes throughout the bay and strait. All of the cores show an increase in tintinnid species and agglutinated foraminifera, and coincident decreases in calcareous foraminifera in younger core sections. In general, these microfossil trends are correlated with higher organic matter content of the younger core sections. This results from a more extensive freshwater plume that causes lowered pH in the superficial sediments and conditions less favourable for the preservation of calcareous tests. Furthermore, with a 14C age constraint in one of the cores, the mid-Holocene depositional and paleoceanographic history is represented, and provides evidence of marine invasion by 7100 cal yrs BP.

Pelagic clays cover nearly one half of the ocean floor, but are rarely used for paleoceanographic research because of their extremely slow sedimentation rates, post-depositional alteration(s), and the lack of biogenic material available to provide ages. My dissertation develops and applies approaches to study pelagic clays by targeting the largest marine sediment province in the world: the South Pacific Gyre (SPG). I present an unprecedented spatially and temporally extensive paleoceanographic history of the SPG and discuss authigenic processes in pelagic clays that are linked to changes in global seawater composition through the Cenozoic. My research was based on an extensive inorganic geochemical dataset I developed from samples gathered during Integrated Ocean Drilling Program Expedition 329. I applied multivariate statistical techniques (e.g., Q-mode factor analysis and constrained least squares multiple linear regression (CLS)) to the dataset in order to (a) identify the existence of six end-members in pelagic clay (namely, eolian dust, Fe/Mn-oxyhydroxides, apatite, excess Si, and two types of volcanic ash), (b) quantify their abundances, (c) determine their mass accumulation rates, and (d) infer major features in the paleoceanographic evolution of the SPG. Key parts of my research also developed improved MATLAB codes to facilitate and speed the search for best fitting end-member combinations in CLS modeling. Additionally, I expanded the natural gamma radiation instrumental capabilities on the D/V JOIDES Resolution to quantify concentrations of uranium, thorium, and potassium. I dated the pelagic clay at four of the IODP sites with a cobalt-based age model that I developed, and documented that the seawater behavior of cobalt determines the extent to which this method can be applied. Collectively, the results track the spatial extent of dust deposition in the SPG during the aridification of Australia, dispersed ash accumulation from episodes of Southern Hemisphere volcanism, and other features of Earth’s evolution during the Cenozoic. I further quantified two geochemically distinct types of authigenic ash alterations within the pelagic clay, indicating that altered ashes may be a significant and variable sink of magnesium in seawater over geologic timescales.

No description available.

Since the late 18th century, chemicals have been industrially produced, and used by consumers. Today, the number of registered chemicals are over 150 000 in North America and Europe alone, and the number is predicted to increase. Industrial or anthropogenic chemicals can, directly or indirectly, be released into the ecosystem during their lifetime, where they can cause harm to human health and the environment. Depending on their properties, chemicals can travel far away from its source, causing global contamination. Through this, the Arctic region becomes a sink for many different types of contaminants. Because of the danger certain chemicals pose, techniques to detect and identify them in environmental samples have evolved during recent years. In these cases, non-targeted screening methods are commonly used to characterise contaminants in samples.In this study, surface sediment samples were collected on three locations in the Hudson Bay (Canada). The samples were analysed using two different instruments: a comprehensive two-dimensional gas chromatograph coupled to a high resolution time-of-flight mass spectrometer (GC×GC-HR-ToF-MS) and a gas chromatograph coupled with a Orbitrap mass spectrometer (GC-Orbitrap-MS). After data acquisition and processing, certain components were identified in both datasets, and their semi-quantitative concentrations were calculated.Overall, 32 compounds were detected and identified in the Orbitrap dataset, and 17 of these were also detected in the GC×GC dataset. The concentration was determined semi-quantitively for the identified compounds and ranged from 0.005–333 ng/g dry weight (d.w.) for the Orbitrap dataset, and 0.013–278 ng/g d.w. for the GC×GC dataset, which was below, or in the lower half, of concentration ranges from previous studies. Overall, the data processing for Orbitrap data seems to be more advanced and evolved than for GC×GC data, causing differences between the results from the two instruments.

The Understen-Märket trench is located in the Southern Quark and is the only deep-water connection between the Baltic Propper and the Gulf of Bothnia. Bathymetric mapping reveals a number of eroded channels and drift deposits exists on the seafloor, indicating that the area is heavily affected by current activity. Bottom current behavior in the area is not thoroughly understood, but generally in the BalticBasin, there is southward flowing fresh surface waters compensated by denser northward-flowing more saline bottom waters. The dominant direction of flow for bottom waters in the Southern Quark is northward. Northward speeds often exceed the threshold required to erode fine material on the seafloor. Using geophysical data and marine sediment cores, this study shows that current eroded channels and drift deposits in the Understen-Märket trench were initially formed in the late Holocene between 3 – 4kyr BP, during the transition from the Littorina to the Post Littorina stages of the Baltic Sea. Application of the sortable silt (SS) proxy for current sorting show three distinct regimes that closely match the assigned lithologic units (LU) based on core descriptions. Downcore grain size analysis of three marine sediment cores reveals a gradual boundary to sandy sediments that caps two of the cores recovered from an eroded channel. The third core was recovered from the drift deposit which mostly consists of silt. The progressive coarsening suggests that the current activity has increased during the late Holocene. A simplified model is presented that shows how moderate (20-50 m) shallowing of the sill, which has occurred in response to isostatic rebound between 8 and 4 kyr BP, could have generated the higher current speeds seen today. However, this should be explored using more advanced paleo-circulation models.

No description available.

(Bahasa Indonesia) Analisa yang terperinci mengenai lingkungan di masa lalu, iklim dan sejarah penggunaaan lahan di wilayah Indonesia sangat penting untuk memperoleh pemahaman yang lebih baik mengenai hubungan manusia-lingkungan dan untuk mencegah ketidakpastian perkembangan wilayah tersebut di masa depan. Indonesia merupakan salah satu wilayah yang memiliki keanekaragaman terbesar, dan pada saat yang bersamaan juga merupakan salah satu Negara yang mempunyai jumlah penduduk terpadat di dunia. Seiring dengan sejarah, pengaruh dari aktivitas manusia pada suatu daerah menjadi semakin kuat. Penelitian ini dilakukan untuk mengakses peranan manusia terhadap perubahan lingkungan. Penelitian kami difokuskan pada rekonstruksi pola vegetasi di masa lampau, perubahan lingkungan dan interaksi antara manusia dan lingkungan yang tercermin dalam sedimen laut di perairan Indonesia. Dua macam pendekatan yang digunakan dalam studi ini adalah: polen (serbuik sari), yang berasal dari darat dan diharapkan bisa memberikan informasi yang beragam tentang vegetasi dan dinamika penggunaan lahan, dan organic dinoflagelata yang berasal dari lingkungan laut dan merefleksikan perubahan parameter air secara kuantitatif (misal. SST, SSS) dan kualitatif (mis: kondisi tropic dilihat dari segi makro-elemen utama dan oksigen terlarut dalam air). Selain itu, arang mikro dipelajari untuk mendapatkan data mengenai sejarah kebakaran di wilayah tersebut dan untuk memperoleh data tambahan untuk interpretasi polen dan data dinoflagelata. Penelitian dilakukan di dua situs sebagai perbandingan: pertama, di wilayah Jawa yang padat penduduk dengan sejarah panjang dari dampak aktivitas manusia yang menghasilkan lanskap pertanian yang luas, dan yang kedua, di wilayah Kalimantan Selatan dengan kepadatan penduduk yang tidak terlalu tinggi dan tidak banyak perubahan akibat pengaruh aktivitas manusia dan masih merupakan vegetasi alami. Metode yang digunakan, palinologi laut memerlukan perhatian khusus dalam interpretasi data. Faktor pengendapan polen adalah sangat penting, terutama untuk daerah-daerah dengan pengaruh kuat dari angin dan arus laut seperti wilayah Indonesia dimana sistem iklim secara keseluruhan didorong sebagian oleh pergantian musim. Untuk mendapatkan beberapa pemikiran mengenai transportasi sedimen di wilayah ini, kami mempelajari dan membahas secara rinci perbedaan jumlah polen yang dikumpulkan pada kondisi musim hujan yang berbeda serta selama waktu perpindahan musim. Subyek manuskrip pertama kami adalah kemelimpahan dan komposisi taksa modern polen dan spora yang didapat dari sedimen yang terakumulasi di Samudera India sebelah barat daya Jawa. Hasil yang diperoleh digunakan untuk interpretasi lebih lanjut dari fosil polen laut. Sejarah intensifikasi penggunaan lahan dan perubahan vegetasi lebih dari 3500 tahun yang lalu yang diperoleh dari dinoflagelata dan kumpullan polen dari sedimen laut dipresentasikan dalam jurnal yang kedua. Studi ini didasarkan pada perbandingan dua core laut dari lepas Laut Jawa dekat Kalimantan Barat (Sungai Jelai) and bagian timur laut Jawa (Sungai/Bengavan Solo). Pada manuskrip yang ketiga, hasil ini diperbandingkan dengan sedimen core dari lepas pantai yang diambil dari bagian hulu sungai Pembuang. Studi ini membahas mengenai hasil analisa geokimia dan analisa dinoflagelata dalam cakupan paleoekologi dan paleoenvironment. Manuskrip kelima membahas tentang keragaman polen dalam core sedimen laut dari wilayah Indonesia. Studi ini merangkum pengetahuan yang diperoleh selama meneliti core sedimen dari Laut Jawa dan dari studi perangkap sedimen di Samudera Hindia. Dalam bentuk atlas polen, kami memberikan hasil analisis secara rinci dari daftar taksa polen dan dilengkapi dengan foto mikro pada tingkat fokus yang berbeda. Hasil keseluruhan dari penelitian ini akan memberikan kontribusi pada pengetahuan tentang dinamika ekosistem dan sejarah alam di wilayah Indonesia dan dapat membantu investigasi paleoekologi dan paleo-iklim di masa depan secara lebih rinci.