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Labile Dissolved Nickel (Ni) Concentrations In The North Pacific, Calyn M. Crawford
Labile Dissolved Nickel (Ni) Concentrations In The North Pacific, Calyn M. Crawford
USF Tampa Graduate Theses and Dissertations
Nickel (Ni) is an important micronutrient for phytoplankton and bacteria that serves as a required co-factor in several metalloenzymes. Despite these known biological uses, total dissolved Ni concentrations remain elevated in global surface waters, in contrast to the surface depletion commonly observed for macronutrients and other nutrient-type trace elements. A prevailing hypothesis for the muted depletion of dissolved Ni concentrations in surface waters is that dissolved Ni in seawater is not in a bioavailable form. The chemical lability of Ni in seawater provides insight into Ni speciation and bioavailability, but few measurements have been made in the open ocean to …
A Process-Based Approach To Evaluating The Role Of Organic Ligands In Trace Metal Cycling In The Marine Environment, Travis Mellett
A Process-Based Approach To Evaluating The Role Of Organic Ligands In Trace Metal Cycling In The Marine Environment, Travis Mellett
USF Tampa Graduate Theses and Dissertations
In addition to control by major nutrient elements (nitrogen, phosphorous, and silicon) growth and community composition of marine phytoplankton is also regulated by trace element nutrients (iron, copper, manganese, zinc, cobalt, nickel, and cadmium). Of these, iron is the most influential in the modern ocean, regulating phytoplankton growth and carbon export in high-nutrient low-chlorophyll regimes and exerting an important control on the marine nitrogen cycle through its role in di-nitrogen fixation. The distributions of these metals has the capacity to control primary production and phytoplankton community composition through differences in cellular quotas or metal sensitivities amongst species. The relationship between …
Investigating The Isotope Signatures Of Dissolved Iron In The Southern Atlantic Ocean, Brent A. Summers
Investigating The Isotope Signatures Of Dissolved Iron In The Southern Atlantic Ocean, Brent A. Summers
USF Tampa Graduate Theses and Dissertations
Iron (Fe), used as a cofactor in nitrogen fixation and photosynthesis by oceanic microorganisms, has extremely low dissolved concentrations in the surface ocean, leading to widespread limitation of phytoplankton growth. Dissolved Fe isotope ratios (δ56Fe) have been shown to be useful in helping to quantify the sources and cycling of Fe in the oceans if Fe source signatures and fractionation processes are well understood. Here, this thesis presents data from GEOTRACES section GA10W, and investigate the isotopic signature of sediment-derived dissolved Fe from the South Atlantic margins. My results show that there are both shallow (δ56Fe of -0.2‰) and deep …
Spatiotemporal Changes Of Microbial Community Assemblages And Functions In The Subsurface, Madison C. Davis
Spatiotemporal Changes Of Microbial Community Assemblages And Functions In The Subsurface, Madison C. Davis
USF Tampa Graduate Theses and Dissertations
The subsurface hosts diverse microbial community assemblages and functions. These communities play an important role in biogeochemical cycling and groundwater purification. Many physicochemical factors affect microbial communities and can cause short-term or long-term perturbations. Subsurface microbes are susceptible to anthropogenic changes in the environment, which can be caused by nutrient inputs or municipal groundwater extraction. Despite the importance of the subsurface microbiome, these microbial communities are poorly characterized. This dissertation describes the characterization of spatiotemporal drivers of subsurface microbial communities through a variety of techniques that include eDNA analyses, bioinformatics, hydrochemical analyses, stable isotope geochemistry, and multivariate statistics. Three coastal …
The Distribution And Biogeochemistry Of Subtropical Intertidal Microbial Mats, Bert D. Anderson
The Distribution And Biogeochemistry Of Subtropical Intertidal Microbial Mats, Bert D. Anderson
USF Tampa Graduate Theses and Dissertations
Microbial mats have played an important role in the carbon (C) and nutrient cycles since the Archean Eon and modern mats are important contributors to the biogeochemistry of intertidal wetlands. Microbial mats are flat assemblages of microbes that are currently found in many unvegetated habitats globally. Intertidal salt pans are a common habitat for microbial mats, however little is known about the distribution of microbial mats within the intertidal landscape. Understanding the spatial distribution of microbial mats is critical to developing quantitative estimates of the impacts of microbial mats on their ecosystems. We photographically measured the presence and density of …