Biogeochemistry Commons^™

Climate Anomalies And Primary Production In Lake Superior, Marcel L. Dijkstra

Dissertations, Master's Theses and Master's Reports - Open

This dissertation supports the modeling of primary production in Lake Superior by offering site specific kinetics and algorithms developed from lab experiments performed on the natural phytoplankton assemblage of Lake Superior. Functions, developed for temperature, light and nutrient conditions and the maximum specific rate of primary production, were incorporated in a 1D specific primary production model and confirmed to published in-situ measured rates of primary production.

An extensive data set (supporting model calibration and confirmation), with a fine spatiotemporal resolution, was developed from field measurements taken bi-weekly during the sampling seasons of 2011, 2012 and 2014; considered to be meteorologically …

The Relative Importance Of Methanogenesis In The Decomposition Of Organic Matter In Northern Peatlands, J. Elizabeth Corbett, Malak M. Tfaily, David J. Burdige, Paul H. Glaser, Jeffrey P. Chanton

OES Faculty Publications

Using an isotope-mass balance approach and assuming the equimolar production of CO₂ and CH₄ from methanogenesis (e.g., anaerobic decomposition of cellulose), we calculate that the proportion of total CO₂ production from methanogenesis varies from 37 to 83% across a variety of northern peatlands. In a relative sense, methanogenesis was a more important pathway for decomposition in bogs (80 ± 13% of CO₂ production) than in fens (64 ± 5.7% of CO₂ production), but because fens contain more labile substrates they may support higher CH4 production overall. The concentration of CO₂ produced from methanogenesis (CO …

Iron Supply And Demand In Antarctic Shelf Ecosystem, D. J. Mcgillicuddy Jr., Peter N. Sedwick, Michael S. Dinniman, K. R. Arrigo, T. S. Bibby, B. J. W. Greenan, Eileen E. Hofmann, John M. Klinck, W. O. Smith Jr., S. L. Mack, C. M. Marsay, B. M. Sohst, G. L. Van Dijken

OES Faculty Publications

The Ross Sea sustains a rich ecosystem and is the most productive sector of the Southern Ocean. Most of this production occurs within a polynya during the November-February period, when the availability of dissolved iron (dFe) is thought to exert the major control on phytoplankton growth. Here we combine new data on the distribution of dFe, high-resolution model simulations of ice melt and regional circulation, and satellite-based estimates of primary production to quantify iron supply and demand over the Ross Sea continental shelf. Our analysis suggests that the largest sources of dFe to the euphotic zone are wintertime mixing and …

Heterotrophic And Autotrophic Contribution To Dinitrogen Fixation In The Gulf Of Aqaba, Eyal Rahav, Barak Herut, Margaret R. Mulholland, Natalia Belkin, Hila Elifantz, Ilana Berman-Frank

OES Faculty Publications

We evaluated the seasonal contribution of heterotrophic and autotrophic diazotrophy to the total dinitrogen (N₂) fixation in the photic zone of a pelagic station in the northern Gulf of Aqaba, Red Sea. N₂ fixation rates were highest during a Trichodesmium bloom in winter (0.7 nmol N l^-1 d^-1), decreased 7-fold 1 wk later throughout the upper 200 m (~0.1 nmol N l^-1) d^-1), and were significantly coupled with both primary and bacterial productivity. N₂ fixation rates were generally higher in the upper 200 m (~0.4 nmol N l^{-1 …}

Divergent Responses Of Atlantic Coastal And Oceanic Synechococcus To Iron Limitation, Katherine R. M. Mackey, Anton F. Post, Matthew R. Mcilvin, Gregory A. Cutter, Seth G. John, Mak A. Saito

OES Faculty Publications

Marine Synechococcus are some of the most diverse and ubiquitous phytoplankton, and iron (Fe) is an essential micronutrient that limits productivity in many parts of the ocean. To investigate how coastal and oceanic Atlantic Synechococcus strains acclimate to Fe availability, we compared the growth, photophysiology, and quantitative proteomics of two Synechococcus strains from different Fe regimes. Synechococcus strain WH8102, from a region in the southern Sargasso Sea that receives substantial dust deposition, showed impaired growth and photophysiology as Fe declined, yet used few acclimation responses. Coastal WH8020, from the dynamic, seasonally variable New England shelf, displayed a multitiered, hierarchical cascade …

Ecosystem Regime Change Inferred From The Distribution Of Trace Metals In Lake Erie Sediments, Fasong Yuan, Richard Depew, Cheryl Soltis-Muth

Biological, Geological, and Environmental Faculty Publications

Many freshwater and coastal marine ecosystems across the world may have undergone an ecosystem regime change due to a combination of rising anthropogenic disturbances and regional climate change. Such a change in aquatic ecosystems is commonly seen as shifts in algal species. But considerably less detail is known about the eutrophication history in terms of changes in algal productivity, particularly for a large lake with a great deal of spatial variability. Here we present an analysis of trace metals (Cu, Ni, Cd, and Pb) on a sediment core recovered from Lake Erie, off the Vermilion coast of northern Ohio, USA, …

A Remote Sensing Based Early Warning System For Algal Blooms In Kuwait Bay And Coastal Waters, Cameron Manche

Masters Theses

The Kuwait Bay and its coastal waters are being threatened by a perpetual hazard, the proliferation of harmful algal blooms (HABS). The frequency of HAB occurrences is a growing problem that is only reported subsequent to the onset of a HAB event. Little effort has been invested in investigating the spatial and temporal distribution of these events in Kuwait Bay and even less is known about their controlling factors. All previous studies within the Kuwait Bay have focused either on measuring nutrient availability and the biodiversity of algal species.

The overall study objective is four-fold: (1) to monitor the spatial …

Utilizing Indicator Of Reduction In Soils Tubes To Affirm A Serpentinitic Hydric Soil On The California Central Coast, Jason Demoss

Natural Resources Management and Environmental Sciences

Wetlands are vital ecosystems that are crucial in maintaining the life of rare and unique soils, plants, and animals. These ecosystems are key players in water storage, water filtration, carbon storage, and harboring unique species. Since the intervention of human development on the Earth’s surface, almost 50% of the Earth’s original wetlands have either been damaged or destroyed. The identification and assessment of both new and old wetlands is crucial in the survival of these precious ecosystems and their conservation. A 3 month-long study was performed to confirm the hydric status of a soil derived from serpentinitic parent material. The …

Carbon And Nitrogen Dynamics From Slow Pools Of Soil Organic Matter In A Temperate Forest: Pyrogenic Organic Matter And And Root Litter, Fernanda Dos Santos

Dissertations, Theses, and Capstone Projects

Soil organic matter (SOM) is the dominant reservoir of organic carbon (OC) in terrestrial ecosystems, storing approximately three times the size of the C pool in the atmosphere. In temperate forests, a major fraction of the SOM consists of slowly decaying soil organic C (SOC) pools. While slowly cycling C pools constitute a large reservoir of stable C in soils, the dominant environmental factors controlling this C pool remain unresolved. This research investigates two significant, but poorly characterized slowly decaying C pools: fine root litter (< 2mm) and thermally altered plant biomass (pyrogenic organic matter, PyOM). Specifically, I used compound-specific stable isotope analysis (¹³C and ¹⁵N) as my main methodological approach to examine the (1) …

Carbon Losses From Pyrolysed And Original Wood In A Forest Soil Under Natural And Increased N Deposition, B. Maestrini, S. Abiven, N. Singh, J. Bird, M. W. I. Schmidt

Publications and Research

Pyrogenic organic matter (PyOM) plays an important role as a stable carbon (C) sink in the soils of terrestrial ecosystems. However, uncertainties remain about in situ turnover rates of fire-derived PyOM in soil, the main processes leading to PyOM-C and nitrogen (N) losses from the soil, and the role of N availability on PyOM cycling in soils. We measured PyOM and native soil organic carbon losses from the soil as carbon dioxide and dissolved organic carbon (DOC) using additions of highly 13C-labelled PyOM (2.03 atom %) and its precursor pinewood during 1 year in a temperate forest soil. The field …

Speleothem And Biofilm Formation In A Granite/Dolerite Cave, Northern Sweden, Therese Sallstedt, Magnus Ivarsson, Johannes Lundberg, Rabbe Sjöberg, Juan Ramón Vidal Romaní

International Journal of Speleology

Tjuv-Antes grotta (Tjuv-Ante's Cave) located in northern Sweden is a round-abraded sea cave ('tunnel cave'), about 30 m in length, formed by rock-water abrasion in a dolerite dyke in granite gneiss. Abundant speleothems are restricted to the inner, mafic parts of the cave and absent on granite parts. The speleothems are of two types: cylindrical (coralloid, popcorn-like), and flowstone (thin crusts). Coralloids correspond to terrestrial stromatolite speleothems in which layers of light calcite alternate with dark, silica-rich laminae. The dark laminae are also enriched in carbon and contain incorporated remains of microorganisms. Two types of microbial communities can be distinguished …

Investigation Of The Flow And Fate Of Nitrate In Epikarst At The Savoy Experimental Watershed, Northwest Arkansas, Jozef Laincz

Graduate Theses and Dissertations

Many karst aquifers are at high risk of nitrate contamination due to a combination of vulnerable geology characterized by thin soils and conduit flow, and excess inputs of nutrients from animal feeding operations. One zone that is present in many karst regions and could play an important role in nitrate attenuation due to properties such as increased residence time and matrix-water contact is the upper, weathered portion of karst, the epikarst. However, the understanding of this role is lacking, and the objective of this dissertation was to elucidate it. The fate of nitrate in the epikarst was traced along a …

Ice Caves On Extraterrestrial Bodies: What Are The Prospects For Speleogenesis And Detection?, Penelope J. Boston

The International Workshop on Ice Caves

Potential mechanisms for creating cavities in icy extraterrestrial bodies have been tentatively explored by several authors. On one hand we have examples of mechanisms that create caves in water ice here on Earth. In addition, there may be unique mechanisms on other Solar System objects that do not occur on Earth but might produce cavities, e.g. sublimation of comets upon perihelion passage. The methods of detecting such cavities depend upon the nature of the icy body in question, the potential for orbital or landed missions to visit those bodies in the future, and remote or landed methods for detecting the …

Characterization Of Rain And Stormwater Nitrogen Inputs To The Mississippi Sound: A Landscape Approach, Joshua Michael Allen

Master's Theses

Urbanization in coastal watersheds is becoming an increasingly important issue in the world. Increased impervious surface cover, a factor of urbanization, has drawn more attention to stormwater runoff as a source of contamination to receiving waters. In this study, nitrogen species from rain and stormwater were analyzed across three different landscape types along the Mississippi Sound (hardened, residential, and pristine), as well as from drainage pipes that flow directly into to the Mississippi Sound. Nitrogen stable isotopes were used to trace the stormwater nitrogen to the surface waters and biota within the Sound.

The objective of this study was to …

Integrating Microbial Physiology And Physio-Chemical Principles In Soils With The Microbial-Mineral Carbon Stabilization (Mimics) Model, William R. Wieder, A. Stuart Grandy, Cynthia M. Kallenbach, Gordon B. Bonan

Faculty Publications

A growing body of literature documents the pressing need to develop soil biogeochemistry models that more accurately reflect contemporary understanding of soil processes and better capture soil carbon (C) responses to environmental perturbations. Models that explicitly represent microbial activity offer inroads to improve representations of soil biogeochemical processes, but have yet to consider relationships between litter quality, functional differences in microbial physiology, and the physical protection of microbial byproducts in forming stable soil organic matter (SOM). To address these limitations, we introduce the MIcrobial-MIneral Carbon Stabilization (MIMICS) model, and evaluate it by comparing site-level soil C projections with observations from …

Land-Use Legacies Regulate Decomposition Dynamics Following Bioenergy Crop Conversion, Cynthia M. Kallenbach, A. Stuart Grandy

Faculty Publications

Land-use conversion into bioenergy crop production can alter litter decomposition processes tightly coupled to soil carbon and nutrient dynamics. Yet, litter decomposition has been poorly described in bioenergy production systems, especially following land-use conversion. Predicting decomposition dynamics in postconversion bioenergy production systems is challenging because of the combined influence of land-use legacies with current management and litter quality. To evaluate how land-use legacies interact with current bioenergy crop management to influence litter decomposition in different litter types, we conducted a landscape-scale litterbag decomposition experiment. We proposed land-use legacies regulate decomposition, but their effects are weakened under higher quality litter and …

Mass And Nutrient Loss In Decaying Hardwood Boles At Hubbard Brook, Chris E. Johnson

Civil and Environmental Engineering - All Scholarship

No abstract provided.

Changes In Tundra Plant And Soil Organic Geochemical Composition In Response To Long-Term Increased Winter Precipitation In N. Alaska, Olivia Miller

Open Access Theses

Tundra ecosystem soils store half of the global soil organic carbon (SOC) pool and have the potential to release large amounts of greenhouse gases, primarily CH₄ and CO₂. As climates warm and permafrost thaws, the emissions of these gases as organic matter decomposition rates increase may become increasingly important to the chemistry of the atmosphere. Increases in precipitation that accompany warming, may shift tundra vegetative composition from moss/graminoid- to shrub-dominated systems. These vegetation shifts may result in important feedback effects as altered plant and litter chemistry may affect SOC storage in soils. Questions investigated include: 1) How …

Analysing The Spatio-Temporal Impacts Of The 2003 And 2010 Extreme Heatwaves On Plant Productivity In Europe, A. Bastos, C. M. Trigo, R. M. Trigo, Steven W. Running

Ecosystem and Conservation Sciences Faculty Publications

In the last decade, Europe has been stricken by two outstanding heatwaves, the 2003 event in western Europe and the 2010 episode over Russia. Both events were characterized by record-breaking temperatures and widespread socioeconomic impacts, including significant increments on human mortality, decreases in crop yields and in hydroelectric production. Previous works have shown that an extreme climatic event does not always imply an extreme response by ecosystems. This work attempts to assess how extreme was the vegetation response to the heatwaves during 2003 and 2010 in Europe, in order to quantify the impacts of the two events on carbon fluxes …

Organic Copper Binding Ligands And Thiol Compounds Produced By Bacteria And In The Elizabeth River, Virginia, Christina Louise Dryden

OES Theses and Dissertations

This dissertation presents work focusing on copper and organic copper binding ligands in laboratory cultures and the Elizabeth River, Virginia. Laboratory cultures of the marine bacterium Vibrio parahaemolyticus were used to demonstrate the influence of elevated copper concentrations on copper-complexing ligand and thiol production. Copper-complexing ligands similar in binding strength to the strongest natural ligands were detected in V. parahaemolyticus cultures (log K′_CuL = 11.8–13.2). A strong correlation (r² = 0.973) was found between total thiol and copper-complexing ligand concentrations at all copper concentrations examined.

A yearlong seasonal study was undertaken in a heavily polluted estuary to ascertain …