Download or read book Biomarker and Carbon Isotope Constraints 13C 14C delta 13 C Delta 14 C on Sources and Cycling of Particulate Organic Matter Discharged by Large Siberian Rivers Draining Permafrost Areas written by Maria Winterfeld and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Biomarker and Carbon Isotope Constraints d13C D14C on Sources and Cycling of Particulate Organic Matter Discharged by Large Siberian Rivers Draining Permafrost Areas written by and published by . This book was released on 2014 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Carbon Isotopes delta 13C Delta 14C and Trace Elements Ba Mn Y in Small Mountainous Rivers and Coastal Coral Skeletons in Puerto Rico written by Ryan Patrick Moyer and published by . This book was released on 2008 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: [Abstract: Tropical small mountainous rivers (SMRs) may transport up to 33% of the total carbon (C) delivered to the oceans. However, these fluxes are poorly quantified and historical records of land-ocean carbon delivery are rare. Corals have the potential to provide such records in the tropics because they are long-lived, draw on dissolved inorganic carbon (DIC) for calcification, and isotopic variations within their skeletons are useful proxies of palaeoceanographic variability. The ability to quantify riverine C inputs to the coastal ocean and understand how they have changed through time is critical to understanding global carbon budgets in the context of modern climate change. A seasonal dual isotope (13C & 14C) characterization of the three major C pools in two SMRs and their adjacent coastal waters within Puerto Rico was conducted in order to understand the isotope signature of DIC being delivered to the coastal oceans. Additionally a 56-year record of paired coral skeletal C isotopes ([delta]13C & [Delta]14C) and trace elements (Ba/Ca, Mn/Ca, Y/Ca) is presented from a coral growing ~1 km from the mouth of an SMR. Four major findings were observed: 1) Riverine DIC was more depleted in [delta]13C and [Delta]14C than seawater DIC, 2) the correlation of [delta]13C and [Delta]14C was the same in both coral skeleton and the DIC of the river and coastal waters, 3) Coral [delta]13C and Ba/Ca were annually coherent with river discharge, and 4) increases in coral Ba/Ca were synchronous with the timing of depletions of both [delta]13C and [Delta]14C in the coral skeleton and increases in river discharge. This study represents a first-order comprehensive C isotope analysis of major C pools being transported to the coastal ocean via tropical SMRs. The strong coherence between river discharge and coral [delta]13C and Ba/Ca, and the concurrent timing of increases in Ba/Ca with decreases in [delta]13C and [Delta]14C suggest that river discharge is simultaneously recorded by multiple geochemical records. Based on these findings, the development of coral-based proxies for the history of land-ocean carbon flux would be invaluable to understanding the role of tropical land-ocean carbon fluxes in the context of global climate change.

Download or read book Organic Matter Sources Transformations and Fates in Northern High Latitude Regions on the Forefront of Climate Change written by Megan Irene Behnke and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate change is dramatically altering the global carbon cycle. The warming caused by climate change is approximately twice the global average in Arctic and contiguous northern high-latitude regions, which are thus especially susceptible to ecosystem shifts (e.g. permafrost thaw, wetland drying/wetting cycle exacerbation). Rivers process and transport organic matter (OM) from land where warming is destabilizing previously stabilized carbon stocks to the ocean. This dissertation examines how fluvial OM in northern high latitudes responds to climate change, and how the fate of such OM may influence the global carbon cycle. Specifically, it focuses on how the source and processing of dissolved and particulate organic matter (DOM and POM) interact to dictate OM fate. To do so, Fourier-transform ion cyclotron resonance mass spectrometry, carbon isotopes ([capital delta]14C, [small delta]13C), and data on OM concentrations and carbon to nitrogen (C:N) ratios are used. Across the pan-Arctic (Chapters 2 and 3) and northeast Pacific coastal temperate rainforest (NPCTR; Chapters 4 and 5), sources appear to influence the fate of DOM (Chapters 2, 4, and 5) and POM (Chapter 3). Both landscape-scale factors like permafrost or agricultural extent (Chapters 2 and 3) and watershed slope and wetland extent (Chapters 3, 4, and 5), as well as specific source types like tree canopy or bark and soil layer (Chapters 4 and 5) impact OM molecular, isotopic, and elemental compositions and thus processing. Further, seasonality varies between the pan-Arctic watershed (Chapters 2 and 3) and the NPCTR (Chapters 4 and 5), leading to differential timing of the strongest terrestrial carbon source impacts on the system.In large pan-Arctic rivers, spring freshet contains DOM primarily sourced from terrestrial material but also includes a latent high-energy subsidy that explains the historical paradox of freshet DOM's bulk terrestrial composition but apparent high biolability. Winter riverine DOM is mostly sourced from old, microbially degraded groundwater DOM. This work uncovered a stable core Arctic riverine fingerprint (CARF) present in all samples from six years. The CARF may contribute to a carbon sink of aged DOM that appears to persist in the global ocean. Further, this dissertation uses a decade of compositional data on POM to untangle multiple allochthonous and autochthonous pan-Arctic and watershed-specific POM endmembers sourced from literature (for the full list of literature values used in endmembers, see supplementary file "Table B5.csv"). The three tracers used (C:N ratio, [small delta]13C, and [capital delta]14C) appear to reveal a substantial, previously overlooked aquatic biomass signal in POM (~53% of the annual pan-Arctic POM flux which averages 4391 Gg/y of exported particulate organic carbon). Splitting soil endmember values into shallow and deep soil pools (mean [plus or minus] standard deviation: -228 [plus or minus] 211 volume -492 [plus or minus] 173%) rather than the less representative traditional active layer and permafrost categories (-300 ± 236 volume -441 ± 215‰) also improved endmember resolution. In the NPCTR, dissolved organic carbon concentrations as high as 167 mgCL-1 were found in tree DOM (which proved highly biolabile in this study; >50%). Since the NPCTR is hypermaritime, tree DOM fluxes may be substantial. Condensed aromatic formulae comprised as much as 38% relative abundance of spruce and hemlock bark leachate DOM. Coniferous trees could thus be major condensed aromatic sources. Soil wetness determined DOM composition and response to microbial processing. Source-specific marker formulae were discovered in multiple soil and tree sources, and though the majority were consumed during bioincubations certain marker formulae persisted. All of these source-specific marker formulae (of which >90% were from spruce stemflow) were then located downstream in the watershed demonstrating that tree DOM may escape biodegradation. Summertime in the NPCTR yields the most terrestrial DOM, which then appears to degrade during the colder, wetter, fall-spring period. Despite these seasonal trends two metrics of fresh terrestrial DOM contribution (marker formulae and modified aromaticity index) did not show any significant relationships with hydrologic or temperature variables. Antecedent conditions (rather than precipitation alone) thus seems to control molecular terrestrial connectivity. Climate change is modifying both the sources and seasons that this dissertation shows to influence DOM composition and fate in northern regions. Increasing precipitation intensity in the NPCTR may tighten land-ocean linkages, while warming, permafrost thaw, and increasing CO2 concentrations could enhance allochthonous and autochthonous POM fluxes and the contribution of old, microbially processed, stable DOM to the Arctic Ocean. This work shows that an improved understanding of current controls on OM composition and fate will be necessary to predict future changes in northern high-latitude ecosystem carbon cycling and its role in furthering global climate change.

Download or read book Investigating Sources of Molecular Uncharacterized Organic Carbon in Sinking Particles from Three Ocean Basins written by Leslie Roland and published by . This book was released on 2007 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Local Land use Impact on the Isotopic Character and Age of Carbon in Unglaciated Small Temperate Watersheds written by Teresa Huey and published by . This book was released on 2011 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The impact of local land-use practices on the transfer of carbon from land to small headwater streams is understudied despite the fact that it has the most pronounced impact on stream carbon at these scales. We measured the stream water concentration, [delta]13C, and [Delta]14C of dissolved organic carbon [DOC], particulate organic carbon [POC], and dissolved inorganic carbon [DIC] in temperate headwater streams. The streams drained a forested, unimproved pasture, large and small mixed land-use, and tilled and no-till corn watershed in Coshocton, Ohio in the fall, spring, and summer and during a winter and spring storm event. Annual carbon fluxes of DOC and POC were greatest in the tilled corn watershed than in all other watershed types. Stream [delta]13C-DOC values indicate that this carbon pool was mainly derived from the present overlying vegetation. [Delta]14C-DOC was all modern suggesting vegetative root exudates contributing to the DOC pool. [Delta]13C-POC values indicate that this carbon pool was derived from a mixture of C3 vegetation and soil organic matter in the non-corn watersheds, and C4 vegetation in both corn watersheds. [Delta]14C-POC values indicate that in the non-corn watersheds, this carbon pool was derived from a mixture of modern overlying vegetation and deeper pre-agricultural soil. Corn [delta]13C-DIC and [Delta]14C-DIC indicate that DIC was derived from atmospheric CO2 equilibration interactions suggesting that respired DOC and POC minimally contribute to the DIC pool. [delta]13C-DIC and [Delta]14C-DIC values in the non-corn watersheds indicate that a mixture of carbonate bedrock dissolution and respiration of organic matter are the primary sources of carbon to this pool. Overall, the flux, isotopic signature, and radiocarbon age of the three carbon pools show that crop practices, especially when tilled, enhance carbon delivery to streams and reduce the residence time of carbon in the watershed.

Download or read book Global Assessment of Radiocarbon Isotopic Analysis for Particulate and Dissolved Organic Carbon in Riverine Systems written by Ashley Tucker and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Rivers are a significant source of particulate and dissolved organic carbon (POC, DOC) into inland waters and coastal systems and provide a fundamental linkage between the terrestrial, oceanic, and atmospheric carbon reservoirs. Recent studies have examined the relationship between the quantity and form (POC vs. DOC) of carbon delivered to the aquatic system; however, little is known about the age of POC and DOC exported and how the radiocarbon age may vary with latitude, topographic gradient, vegetation, and land use. I provide the first global synthesis of published radiocarbon values of POC and DOC ([upper case delta]14C). Inclusion of DOC and POC parameters ([mu]M, [lower case delta]13C, [upper case delta]14C) reveal significant driving forces of DOC ([mu]M), latitude, and elevation (m) as capable of explaining 25% of the variability in DO14C in rivers and POC ([mu]M) and latitude accounting for 15% of the variability in PO14C. When [lower case delta]13C of DOC and POC and latitude were incorporated with [upper case delta]14C of DOC observations, 61% of the variability in DOC age was explained revealing the necessity to include dissolved and particulate fractions of organic carbon to yield the most robust predictive models. This study found a global trend of increasing age of DOC and increasing [lower case delta]13C of DOC and POC with increasing latitude. My study suggests future research should incorporate both particulate and dissolved OC parameters along with elevation, vegetation, land cover, and climate zones to increase understanding of what drives the age of carbon exported in riverine systems.

Download or read book Isotopic Signatures 14C 13C 15N as Tracers of Sources and Cyling of Soluble and Particulate Organic Matter in the Santa Monica Basin California written by P. M. Williams and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Biogeochemical Dynamics at Major River Coastal Interfaces written by Thomas Bianchi and published by Cambridge University Press. This book was released on 2014 with total page 673 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive, state-of-the-art synthesis of biogeochemical dynamics and the impact of human alterations at major river-coastal interfaces for advanced students and researchers.

Download or read book Characterization of Terrestrial Organic Carbon in the Amazon System Insights from Biomarkers and Their Isotopic Composition Delta C 13 and Delta 14C written by Shuwen Sun 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 Use of Stable Isotopes of Carbon and Nitrogen to Identify Sources of Organic Matter to Bed Sediments of the Tualatin River Oregon written by Bernadine Bonn and published by . This book was released on 2010 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: The potential sources of organic matter to bed sediment of the Tualatin River in northwestern Oregon were investigated by comparing the isotopic fractionation of carbon and nitrogen and the carbon/nitrogen ratios of potential sources and bed sediments. Samples of bed sediment, suspended sediment, and seston, as well as potential source materials, such as soil, plant litter, duckweed, and wastewater treatment facility effluent particulate were collected in 1998-2000. Based on the isotopic data, terrestrial plants and soils were determined to be the most likely sources of organic material to Tualatin River bed sediments. The [delta]13C fractionation matched well, and although the [delta]15N and carbon/nitrogen ratio of fresh plant litter did not match those of bed sediments, the changes expected with decomposition would result in a good match. The fact that the isotopic composition of decomposed terrestrial plant material closely resembled that of soils and bed sediments supports this conclusion. Phytoplankton probably was not a major source of organic matter to bed sediments. Compared to the values for bed sediments, the [delta]13C values and carbon/nitrogen ratios of phytoplankton were too low and the [delta]15N values were too high. Decomposition would only exacerbate these differences. Although phytoplankton cannot be considered a major source of organic material to bed sediment, a few bed sediment samples in the lower reach of the river showed a small influence from phytoplankton as evidenced by lower [delta]13C values than in other bed sediment samples. Isotopic data and carbon/nitrogen ratios for bed sediments generally were similar throughout the basin, supporting the idea of a widespread source such as terrestrial material. The [delta]15N was slightly lower in tributaries and in the upper reaches of the river. Higher rates of sediment oxygen demand have been measured in the tributaries in previous studies and coupled with the isotopic data may indicate the presence of more labile organic matter in these areas. Results from this study indicate that strategies to improve oxygen conditions in the Tualatin River are likely to be more successful if they target sources of soil, leaf litter, and other terrestrially derived organic materials to the river rather than the instream growth of algae.

Download or read book Chemical Biomarkers in Aquatic Ecosystems written by Thomas S. Bianchi and published by Princeton University Press. This book was released on 2011-02-28 with total page 417 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook provides a unique and thorough look at the application of chemical biomarkers to aquatic ecosystems. Defining a chemical biomarker as a compound that can be linked to particular sources of organic matter identified in the sediment record, the book indicates that the application of these biomarkers for an understanding of aquatic ecosystems consists of a biogeochemical approach that has been quite successful but underused. This book offers a wide-ranging guide to the broad diversity of these chemical biomarkers, is the first to be structured around the compounds themselves, and examines them in a connected and comprehensive way. This timely book is appropriate for advanced undergraduate and graduate students seeking training in this area; researchers in biochemistry, organic geochemistry, and biogeochemistry; researchers working on aspects of organic cycling in aquatic ecosystems; and paleoceanographers, petroleum geologists, and ecologists. Provides a guide to the broad diversity of chemical biomarkers in aquatic environments The first textbook to be structured around the compounds themselves Describes the structure, biochemical synthesis, analysis, and reactivity of each class of biomarkers Offers a selection of relevant applications to aquatic systems, including lakes, rivers, estuaries, oceans, and paleoenvironments Demonstrates the utility of using organic molecules as tracers of processes occurring in aquatic ecosystems, both modern and ancient

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 Carbon Isotopic Evidence for Biodegradation of Organic Contaminants in the Shallow Vadose Zone of the Radioactive Waste Management Complex written by and published by . This book was released on 2003 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: Waste material buried in drums in the shallow subsurface at the Radioactive Waste Management Facility (RWMC) of the Idaho National Engineering and Environmental Laboratory (INEEL) contained significant amounts of organic compounds including lubricating oils and chlorinated solvents. CO2 concentrations in pore gas samples from monitoring wells in the vicinity of the disposal pits are 3 to 5 times higher than the concentrations in nearby background wells. The stable carbon isotope ratios ([delta]13C values) of CO2 from the disposal pits averaged 2.4. less than CO2 from the background wells, indicating that the elevated CO2 concentrations around the pits were derived from source materials with [delta]13C values in the range of -24{per_thousand} to -29{per_thousand}. These [delta]13C values are typical of lubricating oils, but higher than most solvents. The radiocarbon (14C) contents of CO2 across most of the site were significantly elevated above modern concentrations due to reactor blocks buried in a subsurface vault at the site. However, several samples collected from the high-CO2 zone on the far side of the RWMC from the reactor blocks had very low 14C contents (less than 0.13 times modern), confirming production from lubricating oils manufactured from fossil hydrocarbons. The magnitude of the CO2 anomaly observed at the site is consistent with intrinsic biodegradation rates on the order of 0.5 to 3.0 metric tons of carbon per year.

Download or read book The Organic Carbon Cycle in the Arctic Ocean written by Rüdiger Stein and published by Springer Science & Business Media. This book was released on 2011-06-27 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flux, preservation, and accumulation of organic carbon in marine systems are controlled by various mechanisms including primary p- duction of the surface water, supply of terrigenous organic matter from the surrounding continents, biogeochemical processes in the water column and at the seafloor, and sedimentation rate. For the world's oceans, phytoplankton productivity is by far the largest organic carbon 9 source, estimated to be about 30 to 50 Gt (10 tonnes) per year (Berger et al. 1989; Hedges and Keil 1995). By comparison, rivers contribute -1 about 0. 15 to 0. 23 Gt y of particulate organi.

Download or read book Elucidating Temporal Variability in Organic Matter Sources and Cycling in Tropical Rivers written by Erin Elizabeth Ellis and published by . This book was released on 2012 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tropical rivers are large sources of carbon to the atmosphere and the ocean. The composition of riverine organic matter (OM) affects the size of these fluxes by governing how much carbon will be returned to the atmosphere while in transit versus exported to the ocean, where carbon can be permanently buried in marine sediments. Carbon isotopes coupled with biomarker measurements are powerful tools to elucidate the sources and cycling of OM in rivers, yet few studies have employed them in the tropics. Here I use carbon isotopes (stable and radiocarbon) and biomarker measurements of higher plants and soils to address the following topics: sources of organic carbon respired in rivers; terrestrial OM sources to rivers; the age of riverine OM. In the Amazon Basin, in situ respiration rates are high enough to support the high carbon dioxide gas evasion rates occurring in many white-water rivers. C4 grasses, C3 plants, and phytoplankton fuel respiration, with phytoplankton being important during the low-water season. On the mainstem, C4 grasses are an important substrate for respiration during the rising-water stage, but other sources dominate during falling water. In the Mekong Basin, vascular plants contribute to 15-76 percent of the particulate organic carbon (POC) exported by the river, with phytoplankton and higher plants dominating OM composition during the dry and rainy seasons, respectively. The age of lignin exported by the Mekong is consistently young (produced within the last 15 years), and it cycles amidst POC of varying ages, ranging from contemporary during the rainy season, to over 3,000 years old during the rising-water period. The aged signal observed during the dry period is likely due to the increasing influence from carbon derived from the Upper Basin (the Chinese mountains and the Tibetan Plateau), whereas the young rainy-season values reflect carbon derived from the Lower Basin. Seasonal variability in the composition of particulate lignin corroborates these findings. Finally, the highest concentrations of branched tetraether lipids were found in floodplains and lake beds, suggesting that anaerobic environments may be a significant source of these biomarkers to the river, with production likely occurring within the river.

Download or read book Modeling CH4 and CO2 Cycling Using Porewater Stable Isotopes in a Thermokarst Bog in Interior Alaska written by and published by . This book was released on 2015 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantifying rates of microbial carbon transformation in peatlands is essential for gaining mechanistic understanding of the factors that influence methane emissions from these systems, and for predicting how emissions will respond to climate change and other disturbances. In this study, we used porewater stable isotopes collected from both the edge and center of a thermokarst bog in Interior Alaska to estimate in situ microbial reaction rates. We expected that near the edge of the thaw feature, actively thawing permafrost and greater abundance of sedges would increase carbon, oxygen and nutrient availability, enabling faster microbial rates relative to the center of the thaw feature. We developed three different conceptual reaction networks that explained the temporal change in porewater CO2, CH4, [delta]13C-CO2 and [delta]13C-CH4. All three reaction-network models included methane production, methane oxidation and CO2 production, and two of the models included homoacetogenesis -- a reaction not previously included in isotope-based porewater models. All three models fit the data equally well, but rates resulting from the models differed. Most notably, inclusion of homoacetogenesis altered the modeled pathways of methane production when the reaction was directly coupled to methanogenesis, and it decreased gross methane production rates by up to a factor of five when it remained decoupled from methanogenesis. The ability of all three conceptual reaction networks to successfully match the measured data indicate that this technique for estimating in-situ reaction rates requires other data and information from the site to confirm the considered set of microbial reactions. Despite these differences, all models indicated that, as expected, rates were greater at the edge than in the center of the thaw bog, that rates at the edge increased more during the growing season than did rates in the center, and that the ratio of acetoclastic to hydrogenotrophic methanogenesis was greater at the edge than in the center. In both locations, modeled rates (excluding methane oxidation) increased with depth. A puzzling outcome from the effort was that none of the models could fit the porewater dataset without generating "fugitive" carbon (i.e., methane or acetate generated by the models but not detected at the field site), indicating that either our conceptualization of the reactions occurring at the site remains incomplete or our site measurements are missing important carbon transformations and/or carbon fluxes. This model-data discrepancy will motivate and inform future research efforts focused on improving our understanding of carbon cycling in permafrost wetlands.