Geosciences Department Dissertations Collection

Inversion and analysis of chromophoric dissolved organic matter in estuarine and coastal regions using hyperspectral remote sensing

Zhu, Weining — Mon, 24 Sep 2012 11:00:57 PDT

CDOM (chromophoric dissolved organic matter) plays an important role in determining underwater light field and aquatic photochemical and biological processes. Knowing CDOM properties, origin, sink, content, and distribution is able to provide us not only a useful approach to evaluate, but also a new perspective to understand water quality, carbon cycle, as well as the climate change. Remote sensing inversion of CDOM bears the potential capability to assess CDOM at large scale, but it has not been fully investigated yet. Particularly, the previous approaches cannot meet the accuracy and spatial resolution requirement for analyzing complex waters in estuarine and coastal regions. Therefore, a new scheme, which combines a newly developed inversion algorithm and hyperspectral remote sensing, is proposed to solve problems encountered in CDOM evaluation. This research covers three study sites, in the estuarine and coastal regions of the Mississippi River, Hudson River, and Neponset River. Very high resolution in situ data were collected in these sites and EO-1 Hyperion satellite images were also acquired accordingly. Based on a quasi-analytical algorithm (QAA), a QAA-CDOM algorithm was developed, by which CDOM absorption coefficient a_g(440) is separated from a_dg(440)(total absorption coefficient of CDOM and non-algal particles). Some QAA's parameters and functions were also optimized, using available datasets (in situ, IOCCG, and NOMAD). Result validation in the Atchafalaya plume has proved that QAA-CDOM is capable of estimating a_g(440) in excellent accuracy (RMSE=0.11 m⁻¹ and R²=0.73 in the Atchafalaya River plume region). More importantly, applying QAA-CDOM to other locations, including the Mississippi River, Amazon River, and Moreton Bay, also derived very reasonable and accurate a_g(440), covering a wide range from 0.01 to 15 m⁻¹. This confirms that our method is applicable to a wide range of estuarine regions. The uncertainties involved in CDOM inversion were also analyzed, aiming to know the origin, magnitude, and propagation of uncertainty in different inversion phases. This work strongly indicates that the proposed scheme, QAA-CDOM hyperspectral remote sensing inversion, is robust and reliable to quantify CDOM's concentration, distribution and dynamic for diverse waters, and hence can be applied to other regions.^

Calcareous nannofossil records of Miocene sea level at the Marion Plateau (Northeastern Australia); and Pliocene-Pleistocene formation of cold water carbonate mounds (Northeastern Atlantic Continental Margin)

Browning, Emily — Mon, 24 Sep 2012 11:00:19 PDT

The revised age models for the upper Oligocene to middle Miocene interval of the Marion Plateau have been used to identify eleven sequence boundaries and sequences sets at the Marion Plateau; MSA1.2 (23.1 Ma), MSA1.4 (22.1 Ma), MSA2.1 (21.2 Ma), MSB1.1 (18.4 Ma), MSB1.2 (17.3 Ma), MSB2.1 (16.5 Ma), MSB2.2 (15.6 Ma), MSB2.3 (14.8 Ma), MSB3.1 (13.6 Ma), MSB3.2 (12.9 Ma), and MSB3.3 (11.8 Ma). The complementary Miocene oxygen isotope events Mi1, Mi1a, Mi1aa, Mi2, Mi2b, Mi3a, Mi3, Mi4, Mi5a, Mi5, and Mi6 are recognized in the Marion Plateau sequences. In addition correlation to sequences on the New Jersey margin, the Gulf of Papua, Great Australian Bight, and McMurdo Sound Antarctica indicate that these sequences are controlled by glacio-eustasy, primarily the increase of ice volume on Antarctica. Changes in the preservation, assemblage structure and diversity of calcareous nannofossils as well as %planktic foraminifera, %neritics coincide with transgressive phases and sequence boundaries. The principles of `highstand shedding' are illustrated at the Marion Plateau by enhanced preservation of calcareous nannofossil, deposition of glauconite, unconformities and condensed intervals associated with early to middle Miocene sequence boundaries. Variations in surface water nutrient and temperature conditions at the Marion Plateau throughout the Miocene coincide with climatic events of the early Miocene (23 – 17 Ma), the Middle Miocene Climatic Optimum (17.6 – 15.4 Ma), and Middle Miocene Climatic Transition (14.8 – 13.8 Ma), and the stepwise growth of ice sheets on Antarctica. Calcareous nannofossil communities show evidence for precessional and eccentricity orbital forcing during the Middle Miocene Climatic Optimum, as well as a significantly cooler surface water mass at the Marion Plateau coinciding with the onset of the Middle Miocene Climatic Transition and Mi3a (14.8 Ma) glacial event. Changes in surface water fertility and temperature during the Middle Miocene Climatic Optimum agree with other studies that posit growth of significant ice volume on Antarctica starting as early as ∼17.35 Ma. Further evidence for significant cooling at the Mi3a (14.8 Ma) glacial event agrees with studies suggesting a step-wise cooling for the formation of a semi- permanent Antarctic ice sheet and thermohaline circulation, starting first at 14.8 Ma (Mi3a) and intensifying at 13.9 Ma (Mi3).^

Mammalian Species Origin and Geographical Dispersal Patterns Correlate With Changes in Chromosome Structure, Exemplified in Lemurs (Madagascar) and Bats (Worldwide)

Kolnicki, Robin Lee — Thu, 30 Aug 2012 07:33:00 PDT

The origin and geographical distribution of mammalian species (my examples are lemurs and bats) correlate with predictable chromosomal structural changes (KFT=karyotypic fission theory). Chromosome studies provide information about fertility between individuals and they are significant for identification of the geographical origin of reproductive isolation within mammal families. Each family predictably has chromosome sets with numbers that range from one to double the lowest number of chromosomes. The chromosome numbers of all species within a single family are used to reconstruct that family’s evolutionary geographical dispersion. Polymorphic chromosome numbers (that is a range such as 34, 35, 36, 37, and 38) in a single population indicate the location where chromosomal diversification arose. Chromosome numbers of descending order correlate with relative distance from fission epicenters as the fissioned chromosomes gradually spread to neighboring populations. Furthermore, the location of chromosomal diversification (that is “karyotypic fission events) is associated with geographical “zones of transition” (after Professor R.W. Wilkie). My analysis, mapped one (Lepilemuridae) of the five families of lemurs (Class Mammalia, Order Primates, sub-order Lemuridae). The origin of this family’s diversification is here hypothesized to have occurred at an ecological transition zone in Northern Madagascar between a humid evergreen-forest that extends to the East relative to a dry deciduous forest along the West Coast. My analysis of Vespertilionidae (insectivorous bats representing one third of all bat species) suggests a diversification event occurred in Asia; South China.

Geographical distribution is important in the formation of biological diversity. A single species can inhabit a wide range and exhibit great diversity that is brought about by natural selection. The Holarctic reindeer found in Scandinavia, Russia, China, Canada and Alaska (including caribou) are all a single species Rangifertarandus that exhibits variation in size and in coat pattern, changes brought about by adaptive selection by the environment or human selective breeding but they all have 70 similar chromosomes and they are all reproductively compatible. There is a single species of reindeer. Although, there is measurable DNA sequence divergence; there has been no “speciation” as these circumpolar cervids are genetically compatible.

Compound-Specific Hydrogen Isotopes of Lipid Biomarkers in Lake El’gygytgyn, Ne Russia

Wilkie, Kenna M. K. — Thu, 30 Aug 2012 07:32:51 PDT

Recent successful drilling operations at Lake El'gygytgyn, NE Russia have recovered sediment cores back to 3.6Ma, representing the longest time-continuous sediment record of past climate change in the terrestrial Arctic. Analysis of the hydrogen isotopic ratio (δD) of specific organic biomarkers allows reconstruction of past hydrological conditions, thereby providing a powerful tool for reconstructing past Arctic climate changes. Compound specific isotopic analysis of sedimentary lipids from this remote basin provides new insights into the climate evolution of the Arctic, capturing the mechanisms and dynamics of the last two glacial-interglacial transitions, potentially enhancing the accuracy of modeled future climate change projections and presenting an opportunity to estimate past polar amplification of climate change. The results of this research document the first continuous, high fidelity continental record of reconstructed δD in precipitation from terrestrial plant leaf waxes in the High Arctic spanning the last 120 ka. The hydrogen isotopic composition of lipid biomarkers were determined from previously obtained Lake El'gygytgyn sediment cores and compared with other multi-proxy evidence of past climate change within the lake basin. The modern isotope hydrology and controls on the δD lipid signal were first established within the El'gygytgyn Basin from modern precipitation, stream and lake waters, ice cover as well as modern vegetation, water column and lake bottom surface sediments in order to provide a modern context to properly constrain and interpret paleoclimatic proxy data. Reconstructed δD records of paleoprecipitation and temperature at Lake El'gygytgyn lead other northern hemisphere climate records (e.g. North Greenland Ice Core Project, NGRIP δ18O records) and are in phase with other continental and Antarctic climate records, suggesting early high northern latitude continental warming prior to established glacial-interglacial transitions. The data set generated here leads to multiple avenues of future work and provides critical insights into Arctic paleoclimate and paleohydrology, contributing to our understanding of high latitude environmental change over geological timescales. Collectively, the results of this dissertation research will provide a context for paleoclimate reconstructions and future organic geochemical and stable isotope analysis. Future application of compound-specific H isotope analyses to long drill cores (recovered in 2009; ~315m of sediment) will potentially provide a quantitative high-resolution record of paleoclimatic and paleoenvironmental changes spanning the last 3.6 Ma.

Diatoms as Recorders of Sea Ice in the Bering and Chukchi Seas: Proxy Development and Application

Caisse, Beth A. — Wed, 29 Aug 2012 12:05:39 PDT

The recent, rapid decline in Arctic summer sea ice extent has prompted questions as to the rates and magnitude of previous sea ice decline and the affect of this physical change on icerelated ecosystems. However, satellite data of sea ice only extends back to 1978, and mapped observations of sea ice prior to the 1970s are sparse at best. Inventories of boreal ecosystems are likewise hampered by a paucity of investigations spanning more than the past few decades. Paleoclimate records of sea ice and related primary productivity are thus integral to understanding how sea ice responds to a changing climate. Here I examine modern sedimentation, decadal-scale climate change in the recent past, and centennial- to millennial-scale changes of the past 400 ka using both qualitative and quantitative diatom data in concert with sedimentology and organic geochemistry.

Diatom taxonomy and corresponding ecological affinities are compiled in this study and updated for the Bering Sea region and then used as recorders of past climate changes. In recent decades, the Pacific Decadal Oscillation and the strength of the Aleutian Low are reflected by subtle changes in sediment diatom assemblages at the Bering Sea shelf-slope break. Farther back in time, the super-interglacial, marine isotope stage (MIS) 11 (428-390ka), began in Beringia with extreme productivity due to flooding of the Bering Land Bridge. A moisture-driven advance of Beringian glaciers occurred while eustatic sea level was high, and insolation and seasonality both decreased at the global peak of MIS 11. Atlantic/Pacific teleconnections during MIS 11 include a reversal in Bering Strait throughflow at 410 ka and a relationship between North Atlantic Deep Water Formation and Bering Sea productivity. Finally, concentrations of the biomarker-based sea ice proxy, IP25, are compared to sea ice concentration across the Bering and Chukchi seas. Changes in the concentration of IP25 in the sediments may be driven by the length of time that the epontic diatom bloom lasts. When combined with a sediment-based proxy for sea surface temperatures, IP25 can be used to reconstruct spring ice concentration.

An isotopic perspective on climatic change in tropical South America from the modern through the Last Glacial period

Kanner, Lisa C — Mon, 16 Apr 2012 14:15:05 PDT

The overarching goal of this study is to investigate the nature of precipitation variability in tropical South America over interannual to orbital timescales during the last 50,000 years. In order to address high-resolution climate changes over modern and ancient timescales, this research integrates instrumental records with model simulations and proxy reconstructions from geologic archives. The specific region of focus is the central Peruvian Andes (12°S, 76°W), where recent temperature and precipitation changes are magnified and glacial retreat has accelerated. ^ Monthly output of modern simulations from isotope-enabled global circulation models are validated using precipitation and temperature observations from the Peruvian Meteorological Service (SENAMHI). Interpretation of model results is focused on analysis of the oxygen isotopic composition of precipitation, which also can be readily measured in geologic archives. Interannual variability for the last 133 years (1870–2003) demonstrate that precipitation in central Peruvian Andes is largely influenced by upstream variability, primarily related to the intensity of the South American Summer Monsoon. Over decadal timescales, the sea surface temperatures in the tropical Pacific Ocean and the North Atlantic Ocean also affect the strength of regional summer precipitation. ^ Speleothems (cave samples) were recently collected in the central Peruvian Andes and are used extend the climate record through Holocene and Last Glacial periods. Two stalagmite samples from Huagapo Cave demonstrate that an intensification of regional precipitation is associated with an increase in austral summer insolation over the Holocene. A significant deviation from mean-state changes is observed in the Late Holocene when monsoon intensity decreases, tropical sea surface temperatures increase, and paleoclimatic records indicate a shift to El Niño-like conditions. A stalagmite collected from Pacupahuain Cave grew over a 35,000-year interval (16,000–50,000 years ago) during the Last Glacial period. Abrupt millennial-scale events demonstrate that the SASM is sensitive to high latitude temperature changes in both hemispheres. The dating-precision of speleothem samples provides constraints on the timing of abrupt events in the high North and South Atlantic. Future work includes development of additional stalagmite samples that span distinct intervals of time over the last 275,000 years.^

Subjects of Scale / Spaces of Possibility: Producing Co-operative Space in Theory and Enterprise

Cornwell, Janelle Terese — Mon, 05 Dec 2011 11:01:50 PST

This dissertation addresses key questions raised in Human Geography and Economic Geography concerning scale and the production of space, alternative economic geographies and co-operative economic development. It is the product of a five year ethnographic investigation with co-operative enterprises in Western Massachusetts and the broader Connecticut River Valley of Western New England. It explores neglected questions about how subjects are producing co-operative economic identities, enterprises and development strategies amid capitalist cultural dominance; and how structural, financial and governmental aspects of their enterprises participate in cultivating the desire and capacity to expand co-operative space. In line with poststructuralist feminist perspectives within and outside the disciplines of Human and Economic Geography, each chapter challenges ontological presumptions often made about the economy, scale, power and size and offers theoretical contributions based upon empirical research with co-operative enterprises.The three chapters of this dissertation explore the co-production of co-operative space and subjects; the "practices of scale" in the Valley Alliance of Worker Co-operatives; and co-operative development in a regional context. They challenge the presumptions that space and economy are (and must be) structured by capitalism; power is constituted by hierarchy, size and "scale"; and subjects and subjectivity are insignificant to the project of constructive development. Contrary to structuralist critiques of worker co-operatives based upon size, political conservatism and vulnerability, I argue that worker owned enterprises empower workers despite capitalist cultural dominance and relative size.

Annual to seasonal resolution analysis of late Pleistocene and Holocene sediment in Saanich Inlet, British Columbia, Canada

Kanamaru, Kinuyo — Thu, 16 Jun 2011 13:15:23 PDT

This thesis aims to combine long high-resolution sediment data with information on sedimentation processes in and around Saanich Inlet, to better understand the seasonal sedimentation mechanisms in Saanich Inlet from the late Pleistocene to the early Holocene. These understandings are used to establish sediment provenance in Saanich Inlet with seasonal to sub-seasonal resolution, and to help understand paleoclimatic variations between 10700 and 2150 ¹⁴C calibrated (cal) a BP (= cal yr BP). ^ In Saanich Inlet, elemental variability within laminated sediments is largely controlled by mineralogical changes in the sediment caused by changes in sediment provenance and primary productivity. In particular, on Vancouver Island, gold and platinum group elements (PGE), occurring in soils as a result of weathering of metamorphic and igneous rocks during the process of pedogenesis, are only observed within a restricted area of naturally occurring minerals, which concentrate those elements in soil. Therefore, preferential deposition of such minor elements can be strongly related to a change in sediment provenance. Chalcophile elements, such as Cu, have successfully proven to be reliable indicators of heterogenic-origin and/or bottom water redox conditions. Furthermore, sediment provenance along the western slope basin near Bamberton are distinguished and identified by a strong expression of enriched excess CaCO₃ in both organic (high Ca/Ti and Sr/Ca) and inorganic (high Ca/Ti and low Sr/Ca) forms. ^ This dissertation is divided into five related and complementary parts. The first chapter introduces Saanich Inlet and provides an overview of climatic and oceanographic patterns. The second chapter explains the methodology used in this work, and the third and fourth chapters, which are intended for publication, examine paleoclimatic and oceanographic variability during selected intervals of the Holocene in sub-seasonal (third chapter) and multi-annual to decadal (fourth chapter) scales. The last chapter summarizes the conclusions. Because of this format, some repetition of the introductory material exists in the main chapters. ^

Lacustrine Records of Holocene Climate and Environmental Change from the Lofoten Islands, Norway

Balascio, Nicholas L. — Wed, 06 Apr 2011 08:29:14 PDT

Lakes sediments from the Lofoten Islands, Norway, can be used to generate well resolved records of past climate and environmental change. This dissertation presents three lacustrine paleoenvironmental reconstructions that show evidence for Holocene climate changes associated with North Atlantic climate dynamics and relative sea-level variations driven by glacio-isostatic adjustment. This study also uses distal tephra deposits (cryptotephra) from Icelandic volcanic eruptions to improve the chronologies of these reconstructions and explores new approaches to crypto-tephrochronology. Past and present conditions at Vikjordvatnet, Fiskebølvatnet, and Heimerdalsvatnet were studied during four field seasons conducted from 2007-2010. Initially, each lake was characterized by measuring water column chemistry, logging annual temperature fluctuations, and conducting bathymetric and seismic surveys. Sediment cores were then collected and analyzed using multiple techniques, including: sediment density, magnetic susceptibility, loss-on-ignition, total carbon and nitrogen, δ¹³C and δ¹⁵N of organic matter, and elemental compositions acquired by scanning X-ray fluorescence. Chronologies were established using radiocarbon dating and tephrochronology. A 13.8 cal ka BP record from Vikjordvatnet provides evidence for glacial activity during the Younger Dryas cold interval and exhibits trends in Ti, Fe, and organic content during the Holocene that correlate with regional millennial-scale climate trends and provide evidence for more rapid events. A 9.7 cal ka BP record from Fiskebølvatnet shows a strong signal of sediment inwashing likely driven by local geomorphic conditions, although there is evidence that increased inwashing at the onset of the Neoglacial could have been associated with increased precipitation. Heimerdalsvatnet provides a record of relative sea-level change. A 7.8 cal ka BP sedimentary record reflects changes in salinity and water column conditions as the lake was isolated and defines sea-level regression following the Tapes transgression. Cryptotephra horizons were identified in sediments of Heimerdalsvatnet, Vikjordvatnet, and Sverigedalsvatn. They were also found in a Viking-age boathouse excavated along the shore of Inner Borgpollen. These include the GA4-85, BIP-24a, SILK-N2, Askja, 860 Layer B, Hekla 1158, Hekla 1104, Vedde Ash, and Saksunarvatn tephra. This research project also explored the use of scanning XRF to locate cryptotephra in lacustrine sediments and presents experimental results of XRF scans of tephra-spiked synthetic sediment cores.

Reading Landscape: Mid-Century Modernism and the Landscape Idea

Blankenship, Jeffrey David — Wed, 06 Apr 2011 08:29:04 PDT

This dissertation traces the recovery of the landscape idea during the middle decades of the 20th century by a group of public intellectuals, scholars and designers responding to the everyday realities of the modern American built environment. That recovery served as a corrective to modernism's construction of landscape as either abstract utopian space or retrogressive historical tableau. The primary catalyst for this renewed interest in landscape as a representation of human cultures and their complex relationship with the natural world was the essayist and critic John Brinckerhoff Jackson (1909-1996) and his magazine Landscape. During the years of Jackson's editorship (1951-1968), the magazine became a locus for intellectual exchange, a gathering place for a community of scholars from different disciplines who were drawn to Jackson's unique voice. Jackson's essays in the magazine used the term landscape in a way that was not common outside of the field of human geography. Here landscape did not describe a picturesque or painterly scene, nor did it describe a process of beautification. Jackson wrote of landscapes that seemed somewhat prosaic: the everyday, ordinary environments of city streets, rural farms, individual dwellings, highways and the commercial strip. He insisted that understanding how to read these places for their social, cultural and ecological content was a necessary--though too rarely employed--prelude to imagining new prototypes for the design and management of human environments. The mid-century intellectual milieu fostered by J.B. Jackson ultimately nurtured a contemporary (and still evolving) understanding of landscape as a conceptual medium composed of a diversity of cultures, layers of visible history and hidden narratives and an interdependent human ecology that continues to shape landscape theory and practice today.