Biogeochemistry Commons^™

Linking Decomposition Reactions In Arctic Soils To Microbial Enzyme Production, Jane Karen Martinez

Open Access Theses & Dissertations

Microbial processes such as soil enzyme production are a major driver of decomposition and a current topic of interest in arctic soils due to the effects of climate warming. Despite the advances in understanding soil enzymes, there are still knowledge gaps regarding the role of enzymes in decomposition. In this dissertation, I addressed three of those gaps in the following chapters: (Ch.2) to explore the location of enzymes within the soil matrix, (Ch.3) to identify peptides matched to soil enzymes produced by microorganisms for organic matter decomposition, and (Ch.4) understand the longevity of enzymes in the soil after microbial production. …

The Terroir Of Swiss Cheese: A Temporal And Geomorphological Investigation Of The Martian Co2 Sublimation Pits, Racine D. Cleveland

Graduate Theses and Dissertations

Observations by NASA Mars Global Surveyor showed evidence of rough topography on the South Pole of Mars. The topography is the result of CO2 sublimation processes that occur through the changing seasons on the red planet. These sublimation areas are known to scientists as Swiss Cheese Features (SCF). SCF are erosional degradation pits that have been studied for over two decades. Studies show that these SCF increase in area over time, but these values are collected by hand on a per feature basis. Models for the pit evolution have also played a part in understanding these SCF. This work is …

Dissolved Copper Distributions In The Western Mississippi Sound: Characterizing An Unrecognized Endmember, Megan Hansen

Honors Theses

This study examined the distribution of dissolved copper (Cu) in the western Mississippi Sound, as the element can be beneficial or harmful to organisms depending on its concentration and its chemical form. A mixing experiment eliminated flocculation as a control on Cu distributions during estuarine mixing in both dissolved and colloidal fractions. Field sampling of the western Mississippi Sound occurred during a low river discharge period, and distributions of Cu indicated conservative mixing between fresh ([Cu] ≈ 17 nM) and saline ([Cu] ≈ 2 nM) sources in mid-to-high salinities. Storm outfalls were sampled after rain events to evaluate the impact …

The Phosphorus Puzzle: Why Metal Phosphites Could Be The Missing Piece, Eleanor Boyle, Thomas J. Leyden Iii

Symposium of Student Scholars

It is well understood that phosphorylation of organic molecules is a keystone mechanism toward developing early cell function. However, the source of phosphorous in prebiotic chemistry is under debate. Phosphate minerals were abundant on the early Earth, but they are highly insoluble. In comparison, metal phosphites are significantly more soluble. While they may not have been preserved in the geological record, there are several plausible pathways for their formation under prebiotic conditions. We hypothesize that metal phosphites were a major source of phosphorus. To test our hypothesis, we synthesized and characterized metal phosphites, containing the most abundant cations on the …

The Effects Of Imposed Drought And Nutrient Availability On Soil Microbial Biomass And Enzyme Activity In A Long-Term Restored Grassland, Ashley A. Wojciechowski

2023 Midwest Ecology & Evolution Conference

Restoring agricultural lands back to grassland aims to reverse many negative impacts of agriculture on the ecosystem including nutrient export from soil and depletion of soil carbon. Planting prairie on agricultural soil promotes recovery of soil microbial biomass and their enzymes, which create demand for nitrogen by microbes to reduce the rate of nutrient cycling and loss. A complicating factor in the development of a restored grassland the influence of several anthropogenic global changes including increasing frequency of drought and nutrient enrichment. Drought has been found to negatively affect microbial biomass, soil enzyme activity and nutrient cycling. Nutrient (often N) …

Trait-Based Assembly Of Arbuscular Mycorrhizal Fungal Communities Determines Soil Carbon Formation And Retention, Caitlyn C. A. Horsch, Pedro M. Antunes, Catherine Fahey, A. Stuart Grandy, Cynthia M. Kallenbach

Faculty Publications

Fungi are crucial for soil organic carbon (SOC) formation, especially for the more persistent mineral-associated organic C (MAOC) pool. Yet, evidence for this often overlooks arbuscular mycorrhizal fungi (AMF) communities and how their composition and traits impact SOC accumulation.

We grew sudangrass with AMF communities representing different traits conserved at the family level: competitors, from the Gigasporaceae family; ruderals, from the Glomeraceae family; or both families combined. We labeled sudangrass with 13C-CO2 to assess AMF contributions to SOC, impacts on SOC priming, and fungal biomass persistence in MAOC.

Single-family AMF communities decreased total SOC by 13.8%, likely due to fungal …

Strategies For Achieving Agriculture Carbon Peak And Carbon Neutrality In China Based On View Of Biogeochemical Cycle, Shiqi Yang, Xin Yan

Bulletin of Chinese Academy of Sciences (Chinese Version)

Biogeochemical cycle is the basic theory of matter (elements) flow among atmosphere, hydrosphere, biosphere and lithosphere, which provides important guidance to achieving the national goal of agriculture carbon peak (ACP) and agriculture carbon neutrality (ACN). As a basic industry, agriculture has large-scale temporal and spatial influence on the greenhouse effect, hence great importance should be attached to ACP and ACN in order to assist the overall strategy of achieving national carbon peak and neutrality. Based on the view of biogeochemical cycle and connotations of ACP and ACN, this article analyzes the paths to achieve ACP and ACN, and discusses the …

Meridional Survey Of The Central Pacific Reveals Iodide Accumulation In Equatorial Surface Waters And Benthic Sources In The Abyssal Plain, Rintaro Moriyasu, Kenneth M. Bolster, Dalton S. Hardisty, David C. Kadko, Mark P. Stephens, James W. Moffett

Faculty Publications

The distributions of iodate and iodide were measured along the GEOTRACES GP15 meridional transect at 152°W from the shelf of Alaska to Papeete, Tahiti. The transect included oxygenated waters near the shelf of Alaska, the full water column in the central basin in the North Pacific Basin, the upper water column spanning across seasonally mixed regimes in the north, oligotrophic regimes in the central gyre, and the equatorial upwelling. Iodide concentrations are highest in the permanently stratified tropical mixed layers, which reflect accumulation due to light-dependent biological processes, and decline rapidly below the euphotic zone. Vertical mixing coefficients (K …

Soil Microbial Legacies Influence Freeze–Thaw Responses Of Soil, Melissa A. Pastore, Aimee T. Classen, Marie E. English, Serita D. Frey, Melissa A. Knorr, Karin Rand, E. Carol Adair

Faculty Publications

Warmer winters with less snowfall are increasing the frequency of soil freeze–thaw cycles across temperate regions. Soil microbial responses to freeze–thaw cycles vary and some of this variation may be explained by microbial conditioning to prior winter conditions, yet such linkages remain largely unexplored. We investigated how differences in temperature history influenced microbial community composition and activity in response to freeze–thaw cycles.

We collected soil microbial communities that developed under colder (high elevation) and warmer (low elevation) temperature regimes in spruce-fir forests, then added each of these soil microbial communities to a sterile bulk-soil in a laboratory microcosm experiment. The …

Dust Deposition To The Bermuda Region: A Comparison Of Estimates Using Seasonally-Resolved Measurements Of Aluminum In Water-Column, Aerosol, And Rain Samples, Tara Williams, Peter Sedwick, Bettina Sohst, Joe Resing, Kristen Buck, Salvatore Caprara, Rod Johnson, Dan Ohnemus, Ben Twining, Alessandro Tagliabue

College of Sciences Posters

Dust deposition is a major source of bioactive trace elements to the surface ocean, yet this flux remains difficult to constrain. Previously, time-averaged dust flux has been estimated using surface ocean dissolved aluminum (DAl) concentrations, assumed values for aerosol aluminum solubility (%Al_S), and the residence time of DAl in the surface mixed layer (SML). We apply this method to estimate dust deposition in the Bermuda Atlantic Time-series Study (BATS) region using water-column DAl data from cruises in 2019, which is compared with direct flux estimates from contemporaneous measurements of aluminum in aerosols and rain collected on Bermuda. Seasonal …

The Identification Of New Directions For The Research Of Adhd, Andrew Burkhardt

Legacy Theses & Dissertations (2009 - 2024)

ADHD is a disease commonly associated with childhood; however, recently adult cases of ADHD have been on the rise. The cause of ADHD is not yet known but can be treated. The issue with the treatment of ADHD is the use of heavily restricted stimulants. The use of these medications carry many health risks, most notability addiction. ADHD also has many co-morbidities like anxiety and autism. This makes ADHD a complex disorder, making the identification of a cause difficult. However, by identifying how drugs used to treat ADHD work, combined with genetic testing, areas of interest start to appear. An …

Epiphytic Diatom Production On The Seagrass Thalassia Testudinum In Northern Gulf Of Mexico, Jonathan L. Venable, Shayna A. Sura, Jeffrey W. Krause

Gulf and Caribbean Research

No abstract provided.

Quantifying The Carbon Stored And Sequestered By The Trees On Pomona College’S Campus, Paola A. Giron-Carson

Scripps Senior Theses

We are experiencing a climate crisis that must be confronted with strategic mitigation. Pomona College contributes to the climate crisis through its emissions for which there is a baseline record. However there is no baseline record of the climate mitigation currently performed by the trees on Pomona’s campus through carbon storage. This study seeks to determine a current baseline quantity of carbon stored and sequestrated by Pomona’s trees as well as possible courses of climate mitigation for Pomona College to take. Initial information gathering was conducted through interviews with several stakeholders. This study was conducted using data collected prior to …

Spatiotemporal Dynamics And Biogeochemical Responses In A Tidally Restricted Moro Cojo Slough, Ryan Chiu

Master's Theses

Four years of observational data for Moro Cojo Slough (MCS), a Mediterranean climate estuary in central California, linked anthropogenic nutrient loading and hydrological modifications to a shift in net ecosystem metabolism (NEM) that differs from the characteristic net heterotrophic behavior of most estuarine systems. A lack of precipitation and limited flushing during the dry seasons, as evidenced from hypersaline waters, contribute to high ecosystem respiration rates that drove NEM to nearly balanced or net autotrophic. During the wet seasons, increased runoff and nutrient loading due to precipitation elevated primary production rates within MCS, characterizing the system as net autotrophic. Box …

Food Waste Storage Gaseous Emissions Detection And Quantification Using Infrared Spectroscopy, Ryley A. Burton-Tauzer

Cal Poly Humboldt theses and projects

A growing interest in sustainable waste management and the implementation of new policies have prompted a shift towards alternative resource recovery methods for organic waste, including food waste. To effectively assess alternative food waste treatment scenarios, it is important to evaluate the life cycle impacts associated with each scenario. The storage phase of food waste, encompassing its accumulation in kitchens, and storage in bins for collection and transportation, has been overlooked as a source of greenhouse gases in previous studies. This investigation aimed to identify the greenhouse gases emitted during the initial five-day period of low-oxygen storage. An open dynamic …

Understanding The Impacts Of Freshwater Fluxes On The Biogeochemistry Of The Coastal Arctic: A Case Study Of Prudhoe Bay, Francesca Lingo

Dissertations and Theses

The Arctic region, undergoing significant environmental changes due to rapid warming, faces alterations in air temperatures, melting permafrost, declining sea ice, and changes in riverine inputs. These shifts have profound implications for Arctic coastal ecology and biogeochemical cycles. This study, focusing on Alaska's North Slope, explores the influence of freshwater fluxes on water optical properties, vital for accurate satellite remote sensing interpretations. Our approach combined field measurements, existing data, and satellite remote sensing retrievals to identify biogeochemical gradients and their seasonal and interannual variations. A novel finding was the unique CDOM composition in Prudhoe Bay, characterized by a lower molecular …

Fine Characterization Of Leafing Phenology In The Brazilian Atlantic Forest By Optical And Microwave Remote Sensing, James B. Bell

Dissertations and Theses

Tropical forests provide important ecosystem functions in the global biosphere, but they remain among the most poorly understood elements of land surface models, especially with regard to their seasonal dynamics. For instance, in seasonally dry forests, the pattern of the annual green-up in their canopies closely follows annual patterns of rainfall. The same, however, does not occur in wet forest canopies which are dominated by evergreen trees. In the latter, water is not scarce enough to limit leaf photosynthetic function. Canopy leafing phenology in these forests is therefore poorly characterized by optical remote sensing methods which are not sensitive to …

Shallow Water Coral Distribution And Its Response To Climate Change, Amaury De Jesus

Dissertations and Theses

Shallow water corals are one of the main reef-building organisms that secrete carbonates as their skeletons, and therefore, are one of the major sinks of CO2 in the ocean. These reef builders are also very crucial to marine environments and human society. As the global energy demand continues rising, fossil fuel burning increases at a faster pace despite the increase in energy supply using clean and renewable energy. The increase of CO2 in the atmosphere has been shown to exacerbate global warming and may cause ocean acidification, threatening the habitat of shallow-water corals. Many recent observations show alarming signs of …

Interactions Of Bioactive Trace Metals In Shipboard Southern Ocean Incubation Experiments, Shannon M. Burns, Randelle M. Bundy, William Abbott, Zuzanna Abdala, Alexa R. Sterling, P. Dreux Chappell, Bethany D. Jenkins, Kristen N. Buck

OES Faculty Publications

In the Southern Ocean, it is well‐known that iron (Fe) limits phytoplankton growth. Yet, other trace metals can also affect phytoplankton physiology. This study investigated feedbacks between phytoplankton growth and dissolved Fe, manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and cadmium (Cd) concentrations in Southern Ocean shipboard incubations. Three experiments were conducted in September–October 2016 near the West Antarctic Peninsula: Incubations 1 and 3 offshore in the Antarctic Circumpolar Current, and Incubation 2 inshore in Bransfield Strait. Additions of Fe and/or vitamin B₁₂ to inshore and offshore waters were employed and allowed assessment of metal (M) …

Authigenic Iron Is A Significant Component Of Oceanic Labile Particulate Iron Inventories, Laura E. Sofen, Olga A. Antipova, Kristen N. Buck, Salvatore Caprara, Lauren Chacho, Rodney J. Johnson, Gabriella Kim, Peter Morton, Daniel C. Ohnemus, Sara Rauschenberg, Peter N. Sedwick, Alessandro Tagliabue, Benjamin S. Twining

OES Faculty Publications

Particulate phases transport trace metals (TM) and thereby exert a major control on TM distribution in the ocean. Particulate TMs can be classified by their origin as lithogenic (crustal material), biogenic (cellular), or authigenic (formed in situ), but distinguishing these fractions analytically in field samples is a challenge often addressed using operational definitions and assumptions. These different phases require accurate characterization because they have distinct roles in the biogeochemical iron cycle. Particles collected from the upper 2,000 m of the northwest subtropical Atlantic Ocean over four seasonal cruises throughout 2019 were digested with a chemical leach to operationally distinguish labile …