Biogeochemistry Commons^™

Temporal Variability Of Fluorescent Dissolved Organic Matter At A Brackish, Tidal Marsh-Estuary Interface, Alana B. Menendez

Dissertations and Theses

Marshes are both terrestrial and aqueous, sitting as an intermediate between land and water. Studies over constrained numbers of tidal cycles have demonstrated that these marshes are net exporters of dissolved organic carbon (DOC) to adjoining estuaries, however, there is need for continuous monitoring to better understand the temporal variability of this flux: tidally, seasonally, and during episodic rain events. Through use of a YSI EXO2 sonde, an in situ optical sensor at the interface of the brackish, tidal Kirkpatrick Marsh and Rhode River sub-estuary in Edgewater, Maryland (located on the northwestern shore of the Chesapeake Bay), we were able …

Unraveling The Fingerprints Of Nox Using Stable Isotopes: Implications For Nox Source Partitioning And Oxidation Chemistry, Wendell William Walters

Open Access Dissertations

The nitrogen (N) and oxygen (O) stable isotope composition (δ15N & δ18O) of nitrogen oxides (NOx )may be a useful tool for constraining NOx emission sources as well as for understanding the atmospheric oxidation pathways responsible for its removal if various NOx sources and sink processes exhibit characteristic isotopic compositions (“fingerprints”). However, this requires (1) an accurate and complete inventory of δ15N(NOx) values from major emission sources, (2) an assessment of the kinetic and equilibrium isotope effects that can impact δ15N and δ18O values of NOx, (3) and test these assumptions by conducting accurate in situ δ15N and δ18O measurements …

Examining Denitrification In Agricultural Ditch Sediments Vegetated With Rice Cutgrass (Leersia Oryzoides): Modeling Seasonal Variation Across Increasing Levels Of Nitrate Loading And Model Application To Pre-Existing Datasets, Shannon Lee Speir

Graduate Theses and Dissertations

Nitrogen (N) derived from fertilizer application in agricultural systems may contribute to significant environmental impacts, including eutrophication of fresh and coastal waters. Rice cutgrass (Leersia oryzoides) can significantly enhance denitrification potential in agricultural ditch sediments, but relationships with known drivers are not well understood. To address this, I examined effects of nitrate (NO3-) availability on dinitrogen gas (N2) and NO3- fluxes seasonally in Chapter 2. Denitrification rates were measured as N2 flux from intact vegetated sediment cores using Membrane Inlet Mass Spectrometry (MIMS). Michaelis-Menten models were developed from observations to mathematically describe N2 fluxes across the spring, summer, and fall …

Direct Evidence For Microbial-Derived Soil Organic Matter Formation And Its Ecophysiological Controls, Cynthia M. Kallenbach, Serita D. Frey, A. Stuart Grandy

Faculty Publications

Soil organic matter (SOM) and the carbon and nutrients therein drive fundamental submicron- to global-scale biogeochemical processes and influence carbon-climate feedbacks. Consensus is emerging that microbial materials are an important constituent of stable SOM, and new conceptual and quantitative SOM models are rapidly incorporating this view. However, direct evidence demonstrating that microbial residues account for the chemistry, stability and abundance of SOM is still lacking. Further, emerging models emphasize the stabilization of microbial-derived SOM by abiotic mechanisms, while the effects of microbial physiology on microbial residue production remain unclear. Here we provide the first direct evidence that soil microbes produce …

Long-Term Warming Alters Carbohydrate Degradation Potential In Temperate Forest Soils, Grace Pold, Andrew F. Billings, Jeff L. Blanchard, Daniel B. Burkhardt, Serita D. Frey, Jerry M. Melillo, Julia Schnabel, Linda T. A. Van Diepen, Kristen M. Deangelis

Faculty Publications

As Earth's climate warms, soil carbon pools and the microbial communities that process them may change, altering the way in which carbon is recycled in soil. In this study, we used a combination of metagenomics and bacterial cultivation to evaluate the hypothesis that experimentally raising soil temperatures by 5°C for 5, 8, or 20 years increased the potential for temperate forest soil microbial communities to degrade carbohydrates. Warming decreased the proportion of carbohydrate-degrading genes in the organic horizon derived from eukaryotes and increased the fraction of genes in the mineral soil associated with Actinobacteria in all studies. Genes associated with …

Whiting Events Off Southwest Florida: Remote Sensing And Field Observations, Jacqueline Long

USF Tampa Graduate Theses and Dissertations

“Whiting” is a term used to describe a sharply defined patch of water that contains high levels of suspended, fine-grained calcium carbonate (CaCO₃). These features are named for their bright (at times white) appearance when compared to surrounding waters, and have been found to occur globally, persisting for multiple consecutive days. Although whitings have been widely studied using chemical, biological, geological, and physical techniques, there has been little effort to document their spatio-temporal distributions in a systematic way, not to mention the lack of consensus on what generates whitings and allows them to persist for days to weeks …

Soil Microbial Biomass And Function Are Altered By 12 Years Of Crop Rotation, Marshall D. Mcdaniel, A. Stuart Grandy

Faculty Publications

Declines in plant diversity will likely reduce soil microbial biomass, alter microbial functions, and threaten the provisioning of soil ecosystem services. We examined whether increasing temporal plant biodiversity in agroecosystems (by rotating crops) can partially reverse these trends and enhance soil microbial biomass and function. We quantified seasonal patterns in soil microbial biomass, respiration rates, extracellular enzyme activity, and catabolic potential three times over one growing season in a 12-year crop rotation study at the W. K. Kellogg Biological Station LTER. Rotation treatments varied from one to five crops in a 3-year rotation cycle, but all soils were sampled under …

Silica Uptake And Release In Live And Decaying Biomass In A Northern Hardwood Forest, Wim Clymans, Daniel J. Conley, John J. Battles, Patrick J. Frings, Mary Margaret Koppers, Gene E. Likens, Chris E. Johnson

Civil and Environmental Engineering - All Scholarship

In terrestrial ecosystems, a large portion (20–80%) of the dissolved Si (DSi) in soil solution has passed through vegetation. While the importance of this “terrestrial Si filter” is generally accepted, few data exist on the pools and fluxes of Si in forest vegetation and the rate of release of Si from decomposing plant tissues. We quantified the pools and fluxes of Si through vegetation and coarse woody debris (CWD) in a northern hardwood forest ecosystem (Watershed 6, W6) at the Hubbard Brook Experimental Forest (HBEF) in New Hampshire, USA. Previous work suggested that the decomposition of CWD may have significantly …

Limiting Nutrient Contaminants From Agricultural Non-Point Sources: Nutrient Monitoring At Eku’S Meadowbrook Farm, Madison County, Kentucky, Walter S. Borowski, Jonathan M. Malzone

EKU Faculty and Staff Scholarship

Sources of contamination to U.S. waterways have largely shifted from industrial, point sources to agricultural and other non-point sources associated with common human activities. EKU’s Meadowbrook Farm explores best-practices in agriculture and animal husbandry that not only act to increase the efficiency of farm operations, but also to limit environmental effects such as the eutrophification of its neighboring watershed.

We recently started a collaboration with the Farm and the EKU Department of Agriculture, which are developing methods to sequester phosphorus and thus limit nutrient export to the adjacent Muddy Creek watershed. Our task is to quantify the amount of phosphorus …

Sources, Distributions, And Dynamics Of Dissolved Organic Matter In The Canada And Makarov Basins, Yuan Shen, Ronald Benner, Lisa Robbins, Jonathan Wynn

Faculty Publications

A comprehensive survey of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) was conducted in the Canada and Makarov Basins and adjacent seas during 2010–2012 to investigate the dynamics of dissolved organic matter (DOM) in the Arctic Ocean. Sources and distributions of DOM in polar surface waters were very heterogeneous and closely linked to hydrological conditions. Canada Basin surface waters had relatively low DOC concentrations (69 ± 6 μmol L−1), CDOM absorption (a325: 0.32 ± 0.07 m−1) and CDOM-derived lignin phenols (3 ± 0.4 nmol L−1), and high spectral slope values (S275–295: 31.7 ± …

Comparison Of Permanganate-Oxidizable Carbon And Mineralizable Carbon For Assessment Of Organic Matter Stabilization And Mineralization, Tunsisa T. Hurisso, Steve W. Culman, William R. Horwath, Jordon Wade, Deandra Cass, Joshua W. Beniston, Timothy M. Bowles, A. Stuart Grandy, Alan J. Franzluebbers, Meagan E. Schipanski, Shawn T. Lucas, Carmen M. Ugarte

Faculty Publications

Permanganate-oxidizable C (POXC) and mineralizable C (as determined by short-term aerobic incubation of rewetted soil) are measures of active organic matter that may provide early indication of soil C stabilization and mineralization processes. To date, the relationship between these two promising active organic matter tests has not been comprehensively evaluated, and little is known about their functional role in the soil ecosystem. Here, we examined the relationship between POXC and mineralizable C across a wide range of soil types, management histories, and geographic locations across the United States (13 studies, 76 total sites; n = 1071) and the ability of …

Using Rare Earth Elements To Constrain Particulate Organic Carbon Flux In The East China Sea, Chin-Chang Hung, Ya-Feng Chen, Shih-Chieh Hsu, Kui Wang, Jianfang Chen, David J. Burdige

OES Faculty Publications

Fluxes of particulate organic carbon (POC) in the East China Sea (ECS) have been reported to decrease from the inner continental shelf towards the outer continental shelf. Recent research has shown that POC fluxes in the ECS may be overestimated due to active sediment resuspension. To better characterize the effect of sediment resuspension on particle fluxes in the ECS, rare earth elements (REEs) and organic carbon (OC) were used in separate two-member mixing models to evaluate trap-collected POC fluxes. The ratio of resuspended particles from sediments to total trap-collected particles in the ECS ranged from 82-94% using the OC mixing …

High-Resolution Signatures Of Oxygenation And Microbiological Activity In Speleothem Fluid Inclusions, Nigel Blamey, Penelope J. Boston, Laura Rosales-Lagarde

International Journal of Speleology

Speleothems frequently host “fossil” fluids that were trapped in small inclusions during growth. Such fluids may provide valuable clues to past microbial, geochemical, and climatic processes during their formation. However, one difficulty is to understand which gases represent background atmosphere and fluids within a given cave system at a particular time, and which may be the product of post-trapping residual microbial activity or abiotic chemical reactions? Do we have any hope of sorting out these differences? The success depends on a quantitative understanding of the gas composition trapped in the inclusions and an understanding of the interactions of cave mineralogy, …

Slowed Biogeochemical Cycling In Sub-Arctic Birch Forest Linked To Reduced Mycorrhizal Growth And Community Change After A Defoliation Event, Thomas C. Parker, Jesse J. Sadowsky, Haley Dunleavy, Jens-Arne Subke, Serita D. Frey, Philip A. Wookey

Faculty Publications

Sub-arctic birch forests (Betula pubescens Ehrh. ssp. czerepanovii) periodically suffer large-scale defoliation events caused by the caterpillars of the geometrid moths Epirrita autumnata and Operophtera brumata. Despite their obvious influence on ecosystem primary productivity, little is known about how the associated reduction in belowground C allocation affects soil processes. We quantified the soil response following a natural defoliation event in sub-arctic Sweden by measuring soil respiration, nitrogen availability and ectomycorrhizal fungi (EMF) hyphal production and root tip community composition. There was a reduction in soil respiration and an accumulation of soil inorganic N in defoliated plots, symptomatic of a slowdown …

Quantifying Peat Carbon Accumulation In Alaska Using A Process-Based Biogeochemistry Model, Sirui Wang, Qianlai Zhuang, Zicheng Yu, Scott Bridgham, Jason K. Keller

Education Faculty Articles and Research

This study uses an integrated modeling framework that couples the dynamics of hydrology, soil thermal regime, and ecosystem carbon and nitrogen to quantify the long-term peat carbon accumulation in Alaska during the Holocene. Modeled hydrology, soil thermal regime, carbon pools and fluxes, and methane emissions are evaluated using observation data at several peatland sites in Minnesota, Alaska, and Canada. The model is then applied for a 10,000 year (15 ka to 5 ka; 1 ka = 1000 cal years before present) simulation at four peatland sites. We find that model simulations match the observed carbon accumulation rates at fen sites …

Eleven Years Of Crop Diversification Alters Decomposition Dynamics Of Litter Mixtures Incubated With Soil, M. D. Mcdaniel, A. Stuart Grandy, Lisa K. Tiemann, Michael N. Weintraub

Faculty Publications

Agricultural crop rotations have been shown to increase soil carbon (C), nitrogen (N), and microbial biomass. The mechanisms behind these increases remain unclear, but may be linked to the diversity of crop residue inputs to soil organic matter (SOM). We used a residue mixture incubation to examine how variation in long-term diversity of plant communities in agroecosystems influences decomposition of residue mixtures, thus providing a comparison of the effects of plant diversification on decomposition in the long term (via crop rotation) and short term (via residue mixtures). Three crop residue mixtures, ranging in diversity from two to four species, were …

Development And Curation Of The Sample Data Library For The Astrobiogeochemistry Laboratory, Meika R. Nwaomah, Lorenia Jimenez, Michael Tuite

STAR Program Research Presentations

In 2011, the National Science Foundation (NSF) initiated EarthCube, an integrated cyber infrastructure initiative, to tackle challenges within geoscience research. EarthCube’s goal is to improve public access and collaboration within the geoscience community. During the summer of 2015, the Astrobiogeochemistry Laboratory (abcLab) joined the collective efforts of EarthCube by developing the Sample Data Library (SDL) for the Jet Propulsion Laboratory (JPL). The main focus of the SDL concentrates on effectively curating the samples collected by researchers within the Planetary Chemistry and Astrobiology section at JPL. The goal of this summer internship was to assimilate field notes, images, and from data …

The Role Of Organic Matter In The Fate And Transport Of Antibiotic Resistance, Metals, And Nutrients In The Karst Of Northwest Arkansas, Victor Lee Roland Ii

Graduate Theses and Dissertations

Organic matter (OM) in the environment acts as a nutrient, but may also act as a transport vector for harmful chemical compounds and bacteria. Acetate is a labile form of OM produced during fermentation in anaerobic lagoons used to store animal fecal-waste from concentrated animal feeding operations (CAFOs). Dry and liquid fertilizers from CAFOs pose a threat to groundwater by introducing excessive amounts of nutrients (e.g. OM, nitrate and ammonia), metals, and antibiotic compounds. In the epikarst of Northern Arkansas in the Buffalo River watershed additional input of labile dissolved organic carbon (DOC) from liquid CAFO waste-fertilizers was hypothesized to …

Precision Control Of Soil Nitrogen Cycling Via Soil Functional Zone Management, Alwyn Williams, Adam S. Davis, Patrick M. Ewing, A. Stuart Grandy, Daniel A. Kane, Roger T. A. Koide, David A. Mortensen, Richard G. Smith, Sieglinde S. Snapp, Kurt A. Spokas, Anthony C. Yannarell, Nicholas R. Jordan

Faculty Publications

Managing the soil nitrogen (N) cycle is a major component of agricultural sustainability. Soil functional zone management (zonal management) is a novel agroecological strategy for managing row-crop agroecosystems. It may improve the efficiency of soil N cycling compared with conventional and no-tillage approaches, by managing the timing and location (crop row vs inter-row) of key soil N cycling processes. We compared N mineralization and availability during the period of maize peak N demand in crop rows and inter-rows in zonal management and conventional chisel plow tillage systems at four sites across the US Corn Belt over three growing seasons. Under …

Coastal Ocean And Shelf-Sea Biogeochemical Cycling Of Trace Elements And Isotopes: Lessons Learned From Geotraces, Matthew A. Charette, Phoebe J. Lam, Maeve C. Lohan, Eun Young Kwon, Vanessa Hatje, Catherine Jeandel, Alan M. Shiller, Gregory A. Cutter, Alex Thomas, Philip W. Boyd

OES Faculty Publications

Continental shelves and shelf seas play a central role in the global carbon cycle. However, their importance with respect to trace element and isotope (TEI) inputs to ocean basins is less well understood. Here, we present major findings on shelf TEI biogeochemistry from the GEOTRACES programme as well as a proof of concept for a new method to estimate shelf TEI fluxes. The case studies focus on advances in our understanding of TEI cycling in the Arctic, transformations within a major river estuary (Amazon), shelf sediment micronutrient fluxes and basin-scale estimates of submarine groundwater discharge. The proposed shelf flux tracer …