Biogeochemistry Commons^™

Phosphorus Export From A Restored Wetland Ecosystem In Response To Natural And Experimental Hydrologic Fluctuations, Marcelo Ardón, Shaena Montanari, Jennifer L. Morse, Martin W. Doyle, Emily S. Bernhardt

Environmental Science and Management Faculty Publications and Presentations

Wetland restoration is a commonly used approach to reduce nutrient loading to freshwater and coastal ecosystems, with many wetland restoration efforts occurring in former agricultural fields. Restored wetlands are expected to be effective at retaining or removing both nitrogen and phosphorus (P), yet restoring wetland hydrology to former agricultural fields can lead to the release of legacy fertilizer P. Here, we examined P cycling and export following rewetting of the Timberlake Restoration Project, a 440 ha restored riverine wetland complex in the coastal plain of North Carolina. We also compared P cycling within the restored wetland to two minimally disturbed …

The Distribution And Comparative Biogeochemistry Of Silver With Other Selected Trace Metals In Coastal Waters Near Massachusetts, Usa, Christian F. Krahforst

Graduate Doctoral Dissertations

Water samples and hydrologic data were collected during 1994-1996 in New England coastal waters near Massachusetts, USA to examine the distribution of silver and other trace metals (Cu, Pb, Cd, Zn, and Fe) in the coastal systems of Massachusetts and Cape Cod Bays. These investigations were designed to test the hypothesis that silver could serve as a tracer of dispersion of municipal wastewater in Boston Harbor into Massachusetts and Cape Cod Bays and estimate the relative contribution of wastewater discharge to the overall silver budget of the Massachusetts Bays system. Silver concentrations in both particulate and filtered (<0.4 µm) fractions averaged 103 and 117 pmol kg-1 for Boston Harbor, 34 and 10 pmol kg-1 in western Massachusetts Bay, and 11 and 7 pmol kg-1 in the central portion of Massachusetts Bay, respectively. Average Ag concentrations in southern Gulf of Maine coastal waters were 10 and 2 pmol kg-1 for filtered and particulate fractions, respectively. While nearly half of the silver existed in particulate form in Boston Harbor, nearly 80% of the silver in Massachusetts and Cape Cod Bays occurred in the filterable fraction. Coastal water surveys revealed non-conservative Ag behavior and probably the result of incomplete mixing of three or more water masses with unique Ag signatures (e.g., Merrimack River, Boston Harbor, surface and intermediate Gulf of Maine waters). Quasi-steady state mass balance approaches estimate most of the silver entering into the Massachusetts Bays system during the study period was the result of municipal wastewater discharge to Boston Harbor (84-93%).

Multivariate analyses …

Carbon Isotopic Fractionation Across A Late Cambrian Carbonate Platform: A Regional Response To The Spice Event As Recorded In The Great Basin, Jonathan Lloyd Baker

UNLV Theses, Dissertations, Professional Papers, and Capstones

Geochemical models have suggested that the late Cambrian was characterized by a greenhouse climate with high pCO2. Furthermore, stableisotope analyses within the Great Basin have documented a large carbonate isotope (δ13Ccarb) excursion, known as the Steptoean Positive Carbon Isotope Excursion (SPICE). This event has been documented globally, and is interpreted as having resulted from enhanced organic carbon burial. Unless the size of carbon reservoirs in the Cambrian ocean was significantly different from those of the Cenozoic, this forcing should have resulted in a comparable carbon-isotope excursion in organic matter (δ13Corg). It is also predicted that increased organic carbon burial would …

Phosphorus Uptake In Rhodomonas Salina (Wislouch) And Its Effect On Allocation And Elimination In Acartia Tonsa (Dana), Danna Palladino

OES Theses and Dissertations

Phosphorus is a key element in important biochemical compounds, such as RNA and phospholipids, and can become limiting in a variety of marine systems. The uptake of phosphorus into biochemical fractions (protein, low molecular weight (LMW) compounds, lipid, polysaccharide and nucleic acid) in Acartia tonsa fed ³³P -labeled Rhodomonas salina was examined. R. salina was cultured on two variations of one media that in one case contained phosphorus in balance and the other out of balance with relation to other standard f/2 components. The P-balanced (PB) media had a N:P ratio of 24.5, which is higher than that found …

Virus Silicification Under Simulated Hot Spring Conditions, James R. Laidler, Kenneth M. Stedman

Biology Faculty Publications and Presentations

Silicification of organisms in silica-depositing environments can impact both their ecology and their presence in the fossil record. Although microbes have been silicified under laboratory and environmental conditions, viruses have not. Bacteriophage T4 was successfully silicified under laboratory conditions that closely simulated those found in silica-depositing hot springs. Virus morphology was maintained, and a clear elemental signature of phosphorus was detected by energy-dispersive X-ray spectrophotometry (EDS).

Biogeochemical Investigation Of Soda Lake, Kathryn Bywaters, Shaneen Braswell, David Crowther, Bernadette Leonis, Jeremy Memmott, Farrah Moazeni, Christian H. Fritsen

Undergraduate Research Opportunities Program (UROP)

Big Soda Lake, Nevada, is a terminal, volcanic crater lake whose water level is maintained exclusively by groundwater. The crater is composed of volcanic, basaltic sand and the lake is ~60 m deep (Rush, 1972). The lake is meromictic with a distinct chemocline (Kimmel et al. 1978). The chemocline currently rests at ~40 m and is reflected in both specific conductivity and salinity measurements. Below the chemocline a redox gradient develops with highly reducing conditions. The pH is consistent throughout the depth of the lake at ~9.5, proving that it is alkaline in nature. It is further stratified by both …

Enrichments Of Heavy Sulfur (34s) In Sulfide Minerals: Gas Hydrates, Methane Delivery, And Anaerobic Methane Oxidation, Walter S. Borowski, Namcy M. Rodriguez, Charles K. Paull, William Ussler Iii

EKU Faculty and Staff Scholarship

The sulfur isotopic composition of authigenic, sedimentary sulfide minerals is largely controlled by sulfate reduction and related processes within sedimentary environments. Histograms show that that d³⁴S values of sulfide minerals forming in depositional and diagenetic environments are most often negative (d³⁴S < 0^o/_oo CDT) reflecting the original isotopic composition of seawater sulfate (now ~21^o/_oo), microbially-mediated fractionations of ~-8 to -40^o/_oo (a = 1.029-1.059) during sulfate reduction, and more extreme fractionations caused by sulfur disproportionation. Enrichments of heavy sulfur (d³⁴S > 0^o/_oo) in sulfide …

Identifying Controls On Surface Carbon Dioxide Efflux In A Semi-Arid Ecosystem, Katrina Elsie Ladd

Boise State University Theses and Dissertations

This study focused on soil respiration, the least constrained process in the terrestrial carbon cycle, and a source of uncertainty for model predicted ecosystem response to climate change. Respiration processes that make up soil respiration respond to environmental influencing factors, temperature, and moisture. Respiration responses vary by site, time of year, and also year to year, confounding determination of individual influence of the factors, making soil respiration difficult to model. This research took advantage of the climate characteristics of a semi-arid system, in order to observe soil temperature and moisture influence on soil respiration. Field measurements of soil surface CO …

Cellulosic Ethanol: The Benefits, Obstacles, And Implications For Nebraska, Cassidee Lin Thompson

Department of Environmental Studies: Undergraduate Student Theses

Abstract Ethanol is a biofuel that has unique capabilities to mitigate global climate change by reducing greenhouse gas emissions while simultaneously supporting rural economies and decreasing the United States’ dependence on foreign oil. Currently, the state of Nebraska depends on corn ethanol, which may be unsustainable. Cellulosic ethanol is a promising alternative but it is not without its problems, including high production costs and potential environmental damage. This thesis is an attempt to understand the benefits, downfalls, and processes of corn-based and cellulosic ethanol and the potential implications to Nebraska. This research should shed some light on the current obstacles …

Temporal And Spatial Variations In Freshwater 14C Reservoir Effects: Lake Mývatn, Northern Iceland, Philippa L. Ascough, G. T. Cook, M. J. Church, E. Dunbar, Á. Einarsson, Thomas H. Mcgovern, A. J. Dugmore, Sophia Perdikaris, H. Hastie, A. Friðriksson, H. Gestsdóttir

School of Global Integrative Studies: Faculty Publications

Lake Mývatn is an interior highland lake in northern Iceland that forms a unique ecosystem of international scientific importance and is surrounded by a landscape rich in archaeological and paleoenvironmental sites. A significant freshwater reservoir effect (FRE) has been identified in carbon from the lake at some Viking (about AD 870–1000) archaeological sites in the wider region (Mývatnssveit). Previous accelerator mass spectrometry (AMS) measurements indicated this FRE was about 1500–1900 ¹⁴C yr. Here, we present the results of a study using stable isotope and ¹⁴C measurements to quantify the Mývatn FRE for both the Viking and modern periods. …

Trace Metal Biogeochemistry In The Western North Pacific, Peter Lynn Morton

OES Theses and Dissertations

Dissolved and suspended particulate samples collected during the Intergovernmental Oceanographic Commission 2002 Contaminant Baseline Survey were analyzed to determine the surface and vertical distributions of Cd, Co, Cu, Mn, Ni Zn and Pb across the western and central North Pacific.

Dissolved trace metal concentrations were measured using a novel isotope dilution-ICP-MS method after extraction over an 8-hydroxyquinoline resin column and validated through the use of the SAFe consensus reference materials. Filtered suspended particulate matter was digested using an HCl/HNO3/HF mixture and analyzed by HR-ICP-MS to obtain total particulate concentrations for the trace metals and other tracer elements such as Al, …

Concentrations, Distributions And Chemical Speciation Of Zinc And Cadmium In The Equatorial And South Atlantic Ocean, Gonzalo G. Carrasco

OES Theses and Dissertations

Certain trace metals are important cofactors in enzymatic systems and are thus, essential for life in the world's oceans. Two of these metals, Zn and Cd, are required by phytoplankton for enzymes that facilitate carbon uptake (Morel and Price, 2003). In seawater the total dissolved concentration of a metal (MTD) is distributed among different chemical species and this chemical speciation dictates a metal's bioavailability. Strong organic metal-binding ligands greatly affect the metal's chemical speciation in the ocean, potentially limiting phytoplankton growth by reducing the concentrations of Zn²⁺ and Cd²⁺, the bioavailable forms of these two metals to …

On The Fractional Solubillity Of Copper In Marine Aerosols: Toxicity Of Aeolian Copper Revisited, Edward R. Sholkovitz, Peter N. Sedwick, Thomas M. Church

OES Faculty Publications

Paytan et al. (2009) argue that the atmospheric deposition of aerosols lead to copper concentrations that are potentially toxic to marine phytoplankton in a large area of tropical and subtropical North Atlantic Ocean. A key assumption in their model is that all marine aerosols (mineral dust and anthropogenic particles) have a high (40%) fractional solubility of copper. Our data show that the fractional solubility of copper for Saharan dust over the Sargasso Sea and Bermuda is significantly lower (1-7%). In contrast, anthropogenic aerosols with non-Saharan sources have significantly higher values (10-100%). Hence, the potential Cu toxicity in the tropical and …

The Widespread Occurrence Of Coupled Carbonate Dissolution/Reprecipitation In Surface Sediments On The Bahamas Bank, David J. Burdige, Xinping Hu, Richard C. Zimmerman

OES Faculty Publications

Using two complimentary approaches (pore water advection/diffusion/reaction modeling and stable isotope mass balance calculations) we show that carbonate dissolution/reprecipitation occurs on early diagenetic time scales across a broad range of sediments on the Great Bahamas Bank. The input of oxygen into the sediments, which strongly controls sediment carbonate dissolution, has two major sources belowground input by seagrasses (that is, seagrass O₂ pumping), and permeability-driven advective pore water exchange. The relative importance of these O₂ delivery mechanisms depends on both seagrass density, and on how bottom water flow interacts with the seagrass canopy and leads to this advective exchange. …

A Seasonal Study Of Dissolved Cobalt In The Ross Sea, Antarctica: Micronutrient Behavior, Absence Of Scavenging, And Relationships With Zd, Cd, And P., M. A. Saito, T. J. Goepfert, A. E. Noble, E. M. Bertrand, Peter N. Sedwick, Giacomo R. Ditullio

OES Faculty Publications

We report the distribution of cobalt (Co) in the Ross Sea polynya during austral summer 2005-2006 and the following austral spring 2006. The vertical distribution of total dissolved Co (dCo) was similar to soluble reactive phosphate (PO(4)(3-)), with dCo and PO(4)(3-) showing a significant correlation throughout the water column (r(2) = 0.87, 164 samples). A strong seasonal signal for dCo was observed, with most spring samples having concentrations ranging from similar to ~ 45-85 pM, whereas summer dCo values were depleted below these levels by biological activity. Surface transect data from the summer cruise revealed concentrations at the low range …

Variations In Synechococcus Cell Quotas Of Phosphorus, Sulfur, Manganese, Iron, Nickel, And Zinc Within Mesoscale Eddies In The Sargasso Sea, Benjamin S. Twining, Daliangelis Nunez-Milland, Stefan Vogt, Rodney S. Johnson, Peter N. Sedwick

OES Faculty Publications

The quotas of P, S, Mn, Fe, Ni, and Zn in individual Synechococcus cells collected from the surface and deep chlorophyll maximum (DCM) layer of three mesoscale eddies in the Sargasso Sea were measured using synchrotron X-ray fluorescence microscopy. Cells in a mode-water eddy had significantly higher P (57 +/- 10 amol) and Mn (28 +/- 7 zmol) cell quotas than cells collected from a cyclone (22 +/- 2 amol and 10 +/- 1 zmol, respectively) or anticyclone (25 +/- 3 amol and 18 +/- 3 zmol, respectively). Conversely, Ni and Zn quotas were significantly higher in the cells from …

Temporal Controls On Dissolved Organic Matter And Lignin Biogeochemistry In A Pristine Tropical River, Democratic Republic Of Congo, Robert G. M. Spencer, Peter J. Hernes, Rosmarie Ruf, Andy Baker, Rachael Y. Dyda, Aron Stubbins, Johan Six

Chemistry & Biochemistry Faculty Publications

Dissolved organic carbon (DOC), lignin biomarkers, and the optical properties of dissolved organic matter (DOM) were measured in the Epulu River (northeast Democratic Republic of Congo) with the aim of investigating temporal controls on the quantity and chemical composition of DOM in a tropical rainforest river. Three different periods defined by stages of the hydrologic regime of the region, (1) post dry flushing period, (2) intermediary period, and (3) start of the dry period/post flush, were sampled. Temporal variability in DOM quantity and quality was observed with highest DOC, lignin concentration (Σ₈) and carbon‐normalized (Λ₈) values …

Apparent Seasonal Cycle In Isotopic Discrimination Of Carbon In The Atmosphere And Biosphere Due To Vapor Pressure Deficit, Ashley P. Ballantyne, J. B. Miller, P. P. Tans

Ecosystem and Conservation Sciences Faculty Publications

We explore seasonal variability in isotopic fractionation by analyzing observational data from the atmosphere and the biosphere, as well as simulated data from a global model. Using simulated values of atmospheric CO₂ and its carbon isotopic composition, we evaluated different methods for specifying background concentrations when calculating the isotopic signature of source CO₂ (δ_s) to the atmosphere. Based on this evaluation, we determined that free troposphere measurements should be used when available as a background reference when calculating δ_s from boundary layer observations. We then estimate the seasonal distribution of δ_s from monthly …

Copper Isotope Fractionation During Surface Adsorption And Intracellular Incorporation By Bacteria, Jesica Urbina Navarrete

Open Access Theses & Dissertations

Copper isotopes may prove to be a useful tool for investigating bacteria-metal interactions recorded in natural waters, soils, and rocks. However, experimental data that constrain Cu isotope fractionation in biologic systems are limited and unclear. In this study we utilized Cu isotopes (65Cu) as a tool to investigate Cu-bacteria interactions, including surface adsorption and intracellular incorporation. Experiments were conducted with individual Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacterial species as well as with bacterial consortia from several natural environments. Adsorption experiments were conducted with live or dead cells over the pH range 2.5 to 6. Surface adsorption of Cu …

Carbon Dioxide Exchange In A Permafrost-Dominated Boreal Wetland In The Northwest Territories, Canada, Andrea J. Kenward

Theses and Dissertations (Comprehensive)

Northern boreal wetland complexes are substantial reservoirs for carbon and play a crucial role in both regional and global carbon budgets but they are showing significant signs of impact by climate change. This study examined the carbon dioxide flux of a high boreal wetland during the snowmelt and growing season of 2008 in Scotty Creek Basin, located near Fort Simpson (61°18'N, 121°18'W), Northwest Territories. This basin is not only responding to shifts in atmospheric temperatures, but it is also under additional pressure from increasing permafrost degradation. A dynamic closed-system chamber was used to monitor and quantify mid-day total respiration (R …