Download or read book A Lipid Biomarker Investigation of Organic Matter Sources and Methane Cycling in Alaskan Thaw Lake Sediments written by Mark Richard Williams and published by . This book was released on 2012 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Barrow Peninsula is located on the North Slope of Alaska with much of it consisting of high latitude wetlands. Thaw lakes, an important feature of these wetlands, have been shown to be significant sources of methane to the atmosphere; however the origins of the methane remain poorly constrained. We have used lipid biomarkers to better understand biogenic methane production in lake sediments by characterizing microbial communities that may be involved in methane cycling as well as the organic matter that is available as substrates for methanogens.
Download or read book Lipid Biomarker Composition of Particulate Organic Matter in the Lower Chesapeake Bay written by Elizabeth A. Canuel and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this report we present results from a sampling program designed to characterize the abundance, sources, and composition of particulate organic matter (POM) in the lower Chesapeake Bay. To meet these objectives, we used measurements of bulk parameters (total suspended solids, chlorophylls, particulate carbon and nitrogen concentrations) combined with information on the concentration of two classes of lipid biomarker compounds (fatty acids and sterols). In addition to providing baseline information on the sources and composition of POM important to the lower Bay, the study addressed spatial and temporal variations in organic matter quality. This was accomplished using an experimental design which incorporated seasonal samplings to investigate temporal variability. Spatial variability was examined by comparison of sites located at the mouths of two tributaries (York and Rappahannock Rivers) to two sites located in the Bay mainstem. A further goal of the research project was to improve our understanding of the role of biological and physical processes in controlling the distribution and quality of organic matter. This information can then be used to understand how POM composition changes spatially and temporally in this region of the CB and to provide important insights regarding the nutritional value of the POM to consumer organisms.
Download or read book A Lipid Biomarker and Stable Isotopic Investigation of Ediacaran and Modern Marine Microbial Communities and Carbon Cycling written by Carina Lee and published by . This book was released on 2016 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented here are two studies of marine organic matter preservation and cycling, from the enigmatic late Ediacaran Shuram excursion of South Oman and from the modern hypersaline microbial mats of Guerrero Negro, Baja California, Mexico.
Download or read book Lipidomic and Genomic Investigation of Mahoney Lake B C written by Roderick Bovee and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Photic-zone euxinia (PZE) is associated with several times in Earth's history including Phanerozoic extinction events and long parts of the Proterozoic. One of the best modern analogues for extreme PZE is Mahoney Lake in British Columbia, Canada where a dense layer of purple sulfur bacteria separate the oxic mixolimnion from one of the most sulfidic monimolimnions in the world. These purple sulfur bacteria are known to produce the carotenoid okenone. Okenone's diagenetic product, okenane, has potential as a biomarker for photic-zone euxinia, so understanding its production and transport is important for interpreting the geologic record. In the following dissertation, I examine Mahoney Lake with a multi-proxy approach. I use lipid biomarkers to understand organic matter production burial in the lake and find strong evidence of lateral transport of organic matter from shoreline microbial mats to the lake-bottom sediments. I also find evidence of okenone production in these shoreline mats and a carotenoid previously unreported in the environment, Thiothece-484, associated with the okenone synthetic pathway. Finally, I develop a new bioinformatics method to examine high-throughput metagenomic data and use this method to start understanding how the metabolic and lipid synthetic pathways of microbial communities in the lake are associated with each other.
Download or read book Tracking Environmental Change Using Lake Sediments written by William M. Last and published by Springer Science & Business Media. This book was released on 2002-06-30 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theory Instrumentation NIR analysis of sediment samples Uses of NIRS in palaeolimnology Future perspectives Summary References Fly-ash particles. Neil Rose 319 12. Introduction A brief history Methods of extraction and enumeration Temporal distribution Spatial distribution Source apportionment The future Summary Acknowledgements References Part III: Stable Isotope Techniques 13. Application of stable isotope techniques to inorganic and biogenic carbonates. Emi Ito 351 Introduction Nomenclature and systematics of lake-water Mg/Ca and Sr/Ca ratios of lake-water of dissolved inorganic carbon (DIC) Carbonates in lake-sediments Mollusks Ostracodes Charaphytes Isotope analysis Preparation of carbonate samples for isotope analysis Conclusions Summary Acknowledgments References 14. Carbon and oxygen isotope analysis of lake sediment cellulose: methods and applications. Brent B. Wolfe, Thomas W. D. Edwards, Richard J. Elgood & Kristina R. M. Beuning 373 xi Introduction Stable isotope tracers in lake Historical development Methods Key criteria for paleohydrologic reconstruction Applications Future research directions Summary Acknowledgements References Nitrogen isotopes in palaeolimnology. Michael R. Talbot 15. 401 Introduction Nitrogen in lakes: forms and distribution Nitrogen isotopes Nitrogen isotope studies in palaeolimnology: sampling and measurement Some examples Closing remarks Summary Acknowledgments References Glossary, acronyms and abbreviations 441 Index 493 xiii PREFACE The explosive growth of paleolimnology over the past two decades has provided impetus for the publication of this series of monographs detailing the numerous advances and new techniques being applied to the interpretation of lake histories. This is the second volume in the series and deals mainly with physical and geochemical analytical techniques.
Download or read book Deciphering the Relationships Between Reactivity and Sources of Organic Matter in Marine Sediments written by Felipe Sales de Freitas and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Composition and Distribution of Lipid Biomarkers in Altamaha Estuarine Sediments written by Wei Shi and published by . This book was released on 1998 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Carbon Sources and Trophic Connectivity in Seafloor Food Webs in the Alaska Arctic and Sub Arctic written by Laura Elizabeth Oxtoby and published by . This book was released on 2016 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stable isotope analysis offers critical insight into organic matter pathways that sustain and link consumers in a food web. Indirect examination of organic matter sources and consumer diets using stable isotope analysis is especially valuable in the Alaska Arctic and sub-Arctic marine realm, where organisms of interest are difficult to observe given their remote habitat and elusive behavior. The research objective of this body of work was to use novel applications of stable isotope analysis to extend our understanding of organic matter sources, trophic pathways, and resource competition among benthic consumers. Microphytobenthos, a community of photosynthesizing unicellular microscopic algal cells on the seafloor sediment, has not been included in stable isotope food web models in the Alaska Arctic and sub-Arctic due to challenges associated with sample collection and analysis. I constrained the isotopic composition of this potential algal source by integrating field measurements, physiological relationships previously established by laboratory studies, and a range of algal growth rates specific to high latitude primary production. Relative to other sources of primary production in the Arctic, sub-Arctic, and lower latitude ecosystems, estimates for stable carbon isotope values of total organic carbon from microphytobenthos in the Beaufort and Chukchi seas were higher than those for Arctic riverine organic matter, but lower than ice algal sources and microphytobenthos measurements from lower latitudes. To further elucidate trophic pathways and resource partitioning among benthic invertebrate consumers, I combined compound-specific stable isotope analysis, a relatively new analytical tool, with fatty acid analysis to estimate proportional contributions of algal sources from ice, open ocean, and surface sediments to common polychaete and bivalve consumers in the Bering Sea. Benthic invertebrates were collected in 2009-2010 and represented a diverse range of feeding strategies, including the suspension/surface deposit-feeding bivalves Macoma calcarea and Ennucula tenuis, the subsurface deposit-feeding bivalve, Nuculana radiata, the head down deposit-feeding polychaete Leitoscoloplos pugettensis, and the predator/scavenger Nephtys spp. Differences in dominant algal sources to these invertebrate consumers corresponded, for the most part, to feeding strategy. Bivalves primarily obtained fatty acids from surface sediments, whereas L. pugettensis obtained fatty acids from a microbially altered phytodetrital fatty acid pool, and Nephtys spp. from ice algal fatty acids acquired indirectly through predation. This multi-proxy compound-specific stable isotope approach was then applied to examine dietary overlap between Pacific walruses (Odobenus rosmarus divergens) and bearded seals (Erignathus barbatus) in 2009-2011 who feed primarily on benthic invertebrate prey. Differences in the relative proportions of fatty acids produced exclusively by benthic prey (non-methylene interrupted fatty acids) indicated that walruses and bearded seals had divergent diets. Proportional contributions of algal sources from ice, open ocean, and surface sediments to the prey consumed by walruses and bearded seals also varied. Walruses consumed prey that relied primarily on benthic and pelagic carbon sources (i.e., suspension/surface and subsurface deposit-feeding bivalves). In contrast, bearded seals consumed prey that relied on benthic and ice algal carbon sources (i.e., omnivorous and predatory benthic invertebrates). In conclusion, this research revealed that, in the recent study years, benthic food webs in the Alaska Arctic and sub-Arctic contained several trophic pathways linking consumers to distinct organic matter sources. Consequently, projected changes in algal production with future climate warming may elicit species-specific responses among benthic organisms.
Download or read book Lipid Biomarker Elemental and Isotopic Evidence for Lacustrine Organic Matter Preservation and Source written by Pratigya J. Polissar and published by . This book was released on 1999 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Lipid Biomarkers and Organic Matter Carbon Isotopes in Estuarine Sediments as Proxies for Evaluating Seawater Intrusion written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Export of Terrestrial Organic Matter Into a Sub Arctic Basin written by and published by . This book was released on 2007 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Biomarker Study of Bellingham Bay written by Jessica L. Shulman and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding sediment sources and fluxes throughout coastal zones is essential to evaluate shoreline stability, ecosystem health, and the potential for carbon storage. In Bellingham Bay, WA, like many developed coastal settings, urban areas have replaced forested cover and altered sediment fluxes, yet little is known of their offshore impacts. I analyzed n-alkanes, found in plant leaf waxes preserved in marine sediments of Bellingham Bay to characterize sediment sources and reconstruct changes in the relative contributions of eelgrass beds to sedimentary organic matter since pre-industrial times using a linear mixing model. Eight 2-meter-long cores were analyzed in order to determine how sediment sources have changed spatially throughout Bellingham Bay. Terrestrial plants contributed the majority of the organic matter to marine sediments in Bellingham Bay. n-Alkane biomarkers show a clear increase in terrestrial sources since pre-industrial times to modern day. The relative contribution of eelgrass to sedimentary organic matter peaked at 28% at a depth of 80 cm, which roughly correlates with the year 1712, and has been in steady decline since. This research has been conducted in collaboration with the U.S. Geological Survey Coastal Habitats in Puget Sound Project, which is examining the impacts of sediment transport on local marine environments. Results from my study show how eelgrass biomarker relative abundances corelate with long-term changes in carbon storage.
Download or read book Environmental assessment of the Alaskan Continental Shelf written by Vera Alexander and published by . This book was released on 1978 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Sources and Cycling of Dissolved Organic Carbon Across a Landscape of Arctic Delta Lakes written by Suzanne E. Tank and published by . This book was released on 2009 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved organic carbon (DOC) is a key regulator of aquatic ecosystems, and the primary substrate for aquatic bacteria. However, variations in function between different DOC sources are rarely studied. Arctic Mackenzie Delta lakes exhibit striking differences in DOC composition, with DOC sources ranging from C produced as a byproduct of aquatic plant (macrophyte) photosynthesis, to C derived from permafrost melting (thermokarst), and C delivered to lakes via river-water. This study assessed how variations in DOC source regulate the composition of the within-lake pool, drive bacterial metabolism and the contribution of bacterial biomass to higher trophic levels, and affect CO2 flux from Delta lakes. DOC-specific tracers showed macrophyte-derived DOC to comprise less than 15% of the DOC pool in macrophyte-rich lakes, despite macrophyte C levels 7-12-fold greater than total DOC. However, bacterial 13C indicated that bacteria preferentially incorporate DOC generated by macrophytes, while surveys and incubation experiments showed that bacterial metabolism is rapid on macrophytic DOC, with high rates of bacterial biomass production relative to respiratory loss as CO2. Accordingly, 13C, 15N, and fatty acid biomarkers demonstrated that zooplankton from macrophyte-rich lakes receive a greater proportion of their biomass from bacterial organic matter than zooplankton from other lake types. At the same time, however, experiments indicated that the high pH resulting from rapid photosynthesis in macrophyte-rich lakes can decrease the rate of bacterial metabolism over the short-term, and increase CO2 respiration at the expense of bacterial biomass production. In contrast, DOC-specific tracers indicated that thermokarst-derived DOC accumulates in lakes. Incubation experiments and In situ surveys revealed thermokarst DOC to be a relatively poor bacterial substrate, which resulted in proportionately more CO2 respiration, relative to bacterial biomass production, than observed for other Delta DOC sources. Moreover, multi-year surveys demonstrated that thermokarst lakes exhibit high levels of CO2 emission, despite clear undersaturation in other lakes, presumably because permafrost-derived DOC was largely respired by bacteria. Understanding the divergent roles played by the contrasting sources of DOC to Delta lakes both adds insight to the functioning of other lake regions, globally, and helps clarify the effect of climate-induced changes in DOC on northern lakes.
Download or read book Lipid Biomarkers of Microbial Communities Involved in Carbon Dioxide and Methane Cycling at Volcanic CO2 Vents written by Birte I. Oppermann and published by . This book was released on 2010 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Distribution and Characterization of Organic Matter Using Lipid Biomarkers A Case Study in a Pristine Tropical Bay in NE Brazil written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seasonal Dynamics of Organic Matter and Inorganic Nitrogen in Surface Waters of Alaskan Arctic Streams and Rivers written by Matthew Solomon Khosh and published by . This book was released on 2015 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate-linked changes in hydrology and biogeochemical processes within Arctic watersheds are likely already affecting fluvial export of waterborne materials, including organic matter (OM) and dissolved inorganic nitrogen (DIN). Our understanding of Arctic watershed OM and DIN export response to climate change is hampered by a lack of contemporary baselines, as well as a dearth of seasonally comprehensive studies. This work focuses on characterizing OM and DIN concentrations and sources in six streams/rivers on the North Slope of Alaska during the entirety of the hydrologic year (May through October) in 2009 and 2010. The highest OM concentrations occurred during spring snowmelt, with results indicating that terrestrial vegetation leachates are the major source of dissolved OM, while particulate OM originates from a degraded soil source. Over the hydrologic year, soils became a progressively increasing source of dissolved OM, while autochthonous production made up a sizeable proportion of particulate OM during base flow conditions. DIN concentrations were low throughout the spring and summer and increased markedly during the late summer and fall. Our findings suggest that penetration of water into thawed mineral soils, and a reduction in nitrogen assimilation relative to remineralization, may increase DIN export from Arctic watersheds during the late summer and fall. Although recent studies of Arctic rivers have emphasized the importance of the spring thaw period on OM export, our understanding of the mechanisms that control water chemistry observations during this time are still lacking. Experimental leaching results, from experiments conducted in 2014, suggest that aboveground plant biomass is a major source of dissolved OM in Arctic catchments during the spring, and that the timing of freezing and drying conditions during the fall may impact dissolved OM leaching dynamics on that same material the following snowmelt. Improved knowledge of OM and DIN temporal trends and the mechanisms that control seasonal concentrations is essential for understanding export dynamics of these water constituents in Arctic river systems. Perhaps more importantly, increased understanding of the seasonal controls on OM and DIN export in Arctic rivers is critical for predicting how these systems will respond under future climate change scenarios.
